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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

    2016-10-01

    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. Parabolic tapers for overmoded waveguides

    Science.gov (United States)

    Doane, J.L.

    1983-11-25

    A waveguide taper with a parabolic profile, in which the distance along the taper axis varies as the square of the tapered dimension, provides less mode conversion than equal length linear tapers and is easier to fabricate than other non-linear tapers.

  3. 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.

  4. Does it take one to know one? Endorsement of conspiracy theories is influenced by personal willingness to conspire.

    Science.gov (United States)

    Douglas, Karen M; Sutton, Robbie M

    2011-09-01

    We advance a new account of why people endorse conspiracy theories, arguing that individuals use the social-cognitive tool of projection when making social judgements about others. In two studies, we found that individuals were more likely to endorse conspiracy theories if they thought they would be willing, personally, to participate in the alleged conspiracies. Study 1 established an association between conspiracy beliefs and personal willingness to conspire, which fully mediated a relationship between Machiavellianism and conspiracy beliefs. In Study 2, participants primed with their own morality were less inclined than controls to endorse conspiracy theories - a finding fully mediated by personal willingness to conspire. These results suggest that some people think 'they conspired' because they think 'I would conspire'.

  5. 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.

  6. 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.

  7. Taper Preparation Variability Compared to Current Taper Standards Using Computed Tomography

    Directory of Open Access Journals (Sweden)

    Richard Gergi

    2012-01-01

    Full Text Available Introduction. The purpose of this study was to compare the taper variation in root canal preparations among Twisted Files and PathFiles-ProTaper .08 tapered rotary files to current standards. Methods. 60 root canals with severe angle of curvature (between 25∘ and 35∘ and short radius (<10 mm were selected. The canals were divided randomly into two groups of 30 each. After preparation with Twisted Files and PathFiles-ProTaper to size 25 taper .08, the diameter was measured using computed tomography (CT at 1, 3, and 16 mm. Canal taper preparation was calculated at the apical third and at the middle-cervical third. Results. Of the 2 file systems, both fell within the ±.05 taper variability. All preparations demonstrated variability when compared to the nominal taper .08. In the apical third, mean taper was significantly different between TF and PathFiles-ProTaper ( value < 0.0001; independent -test. Mean Taper was significantly higher with PathFile-ProTaper. In the middle-cervical third, mean Taper was significantly higher with TF ( value = 0.015; independent -test. Conclusion. Taper preparations of the investigated size 25 taper .08 were favorable but different from the nominal taper.

  8. Tapered optical fibres for sensing

    Science.gov (United States)

    Martan, Tomas; Kanka, Jiri; Kasik, Ivan; Matejec, Vlastimil

    2008-11-01

    Recently, optical fibre tapers have intensively been investigated for many applications e.g. in telecommunications, medicine and (bio-) chemical sensing. The paper deals with enhancement of evanescent-field sensitivity of the solid-core microstructured fibre with steering-wheel air-cladding. Enhancement of a performance of the microstructured fibre is based on reduction of fibre core diameter down to narrow filament by tapering thereby defined part of light power is guided by an evanescent wave traveling in axial cladding air holes. The original fibre structure with outer diameter of 125 µm was reduced 2×, 2.5×, 3.33×, and 4× for increasing relatively small intensity overlap of guided core mode at wavelength of 1.55 μm with axial air holes. The inner structures of tapered microstructured fibre with steering-wheel aircladding were numerically analyzed and mode intensity distributions were calculated using the FDTD technique. Analyzed fiber tapers were prepared by constructed fibre puller employing 'flame brush technique'.

  9. 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....

  10. Mode field diameter preserving fiber tapers

    DEFF Research Database (Denmark)

    Noordegraaf, Danny; Maack, M. D.; Skovgaard, P. M. W.;

    2011-01-01

    concentric dual-core fibers, which couple light from an inner core to an outer core through a taper. Fibers with a 6 μm MFD feedthrough and a 15 μm polarization maintaining feedthrough are demonstrated experimentally. Simulations of the MFD in the tapered dual-core fibers are also presented....

  11. 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...... physics lies in that when propagating along the direction towards the tip both the group and phase velocities of the plasmons supported by the tapered graphene waveguide are reduced accordingly, eventually leading to nanofocusing at the tip with a huge enhancement of optical fields. The nanofocusing...... of optical fields in tapered graphene plasmonic waveguides could be potentially exploited in the enhancement of light–matter interactions....

  12. Tapered silicon nanowires for enhanced nanomechanical sensing

    Science.gov (United States)

    Malvar, O.; Gil-Santos, E.; Ruz, J. J.; Ramos, D.; Pini, V.; Fernandez-Regulez, M.; Calleja, M.; Tamayo, J.; San Paulo, A.

    2013-07-01

    We investigate the effect of controllably induced tapering on the resonant vibrations and sensing performance of silicon nanowires. Simple analytical expressions for the resonance frequencies of the first two flexural modes as a function of the tapering degree are presented. Experimental measurements of the resonance frequencies of singly clamped nanowires are compared with the theory. Our model is valid for any nanostructure with tapered geometry, and it predicts a reduction beyond two orders of magnitude of the mass detection limit for conical resonators as compared to uniform beams with the same length and diameter at the clamp.

  13. Reconfigurable tapered coaxial slot antenna for hepatic microwave ablation.

    Science.gov (United States)

    Malhotra, Neeru; Marwaha, Anupma; Kumar, Ajay

    2016-01-01

    Microwave ablation is rapidly being rediscovered and developed for treating many cancers of liver, lung, kidney and bone, as well as arrhythmias and other medical conditions. The microwaves ablate tissue by heating it to cytotoxic temperatures. The microwave antenna design suffers the challenges of effective coupling and penetration into body tissues, uncontrolled power deposition due to applicator construction limitations affecting uniform heating of target region, and narrowband operation leading to mismatch for many patients and detrimental heating. To meet out the requirements of wideband operation and localized lesion reconfigurable linearly tapered slot interstitial wideband antenna has been proposed for working in the 1.38 GHz to 4.31 GHz frequency band. The performance of the antenna is evaluated by using FEM-based HFSS software. The slot height and taper height are reconfigured for parametric analysis achieving maximum impedance matching and spherical ablation zone without requiring any additional adjustable structures. The tapering of the slot in coaxial antenna generates current distribution at the edges of the slot for maximizing specific absorption rate.

  14. Owners and Managers of Former Salvage Operations at Former Textile Plant in Tennessee Sentenced to Prison for Conspiracy Associated with Illegal Asbestos Removal Conspirators ordered to pay $10.3 million in restitution

    Science.gov (United States)

    ATLANTA - U.S. District Judge Ronnie Greer sentenced five people to prison terms in federal court in Greeneville, Tennessee, late yesterday for conspiring to commit Clean Air Act offenses in connection with the illegal removal and disposal of asbest

  15. The advantages of a tapered whisker.

    Directory of Open Access Journals (Sweden)

    Christopher M Williams

    Full Text Available The role of facial vibrissae (whiskers in the behavior of terrestrial mammals is principally as a supplement or substitute for short-distance vision. Each whisker in the array functions as a mechanical transducer, conveying forces applied along the shaft to mechanoreceptors in the follicle at the whisker base. Subsequent processing of mechanoreceptor output in the trigeminal nucleus and somatosensory cortex allows high accuracy discriminations of object distance, direction, and surface texture. The whiskers of terrestrial mammals are tapered and approximately circular in cross section. We characterize the taper of whiskers in nine mammal species, measure the mechanical deflection of isolated felid whiskers, and discuss the mechanics of a single whisker under static and oscillatory deflections. We argue that a tapered whisker provides some advantages for tactile perception (as compared to a hypothetical untapered whisker, and that this may explain why the taper has been preserved during the evolution of terrestrial mammals.

  16. Physiological changes associated with the pre-event taper in athletes.

    Science.gov (United States)

    Mujika, Iñigo; Padilla, Sabino; Pyne, David; Busso, Thierry

    2004-01-01

    : cortisone ratio, plasma and urinary catecholamines, growth hormone and insulin-like growth factor-1 are sometimes affected and changes can correlate with changes in an athlete's performance capacity. From a neuromuscular perspective, the taper usually results in markedly increased muscular strength and power, often associated with performance gains at the muscular and whole body level. Oxidative enzyme activities can increase, along with positive changes in single muscle fibre size, metabolic properties and contractile properties. Limited research on the influence of the taper on athletes' immune status indicates that small changes in immune cells, immunoglobulins and cytokines are unlikely to compromise overall immunological protection. The pre-event taper may also be characterised by psychological changes in the athlete, including a reduction in total mood disturbance and somatic complaints, improved somatic relaxation and self-assessed physical conditioning scores, reduced perception of effort and improved quality of sleep. These changes are often associated with improved post-taper performances. Mathematical models indicate that the physiological changes associated with the taper are the result of a restoration of previously impaired physiological capacities (fatigue and adaptation model), and the capacity to tolerate training and respond effectively to training undertaken during the taper (variable dose-response model). Finally, it is important to note that some or all of the described physiological and psychological changes associated with the taper occur simultaneously, which underpins the integrative nature of relationships between these changes and performance enhancement.

  17. 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.

  18. On the treatment of noise and conspiring bias in dual-frequency differential Global Navigation Satellite Systems

    Science.gov (United States)

    Bruckner, Dean C.

    Four primary contributions are made to the treatment of noise and conspiring bias for dual frequency differential Global Satellite Navigation Systems (GNSSs). These contributions enhance accuracy and protection levels for aircraft precision approach and landing operations and similar applications. A statistical characterization is presented of Global Positioning System (GPS) user range error as an uncorrelated, normally distributed random variable with non-zero mean over the length of the aircraft precision approach operation. This leads directly to modeling GPS error in the position domain as multivariate normal with non-zero mean. Based on this model, a vertical composite protection level VPLc and a horizontal composite protection level HPLc are each implemented as univariate normal distributions with non-zero means. A method is presented by which exact values---that is, values accurate to a user-defined error tolerance and consistent with statistical assumptions---of VPL c and HPLc are obtained, and by which computationally efficient approximations may be evaluated. A statistical quadratic form under the multivariate normal distribution is then used to derive a new class of protection levels based on the probability enclosed within a radius defined in two or more dimensions. A central chi-square representation of this quadratic form is also presented, and is incorporated into a six-step computational procedure for the two-dimensional composite radial protection level RPLc. This procedure is extended to the composite spherical protection level (SPLc) and the ellipsoidal protection level (EPLc). Two additional algorithms are presented for dual-frequency differential Global Positioning System (GPS) use. Performance improvements are achieved first through the exchange of pseudorange noise and multipath for reducible biases using a modified Code Noise and Multipath (CNMP) algorithm applied both to reference station and aircraft ranging measurements. In this algorithm

  19. Intermodal Energy Transfer in a Tapered Optical Fiber: Optimizing Transmission

    CERN Document Server

    Ravets, S; Kordell, P R; Wong-Campos, J D; Rolston, S L; Orozco, L A

    2013-01-01

    We present an experimental and theoretical study of the energy transfer between modes during the tapering process of an optical nanofiber through spectrogram analysis. The results allow optimization of the tapering process, and we measure transmission in excess of 99.95% for the fundamental mode. We quantify the adiabaticity condition through calculations and place an upper bound on the amount of energy transferred to other modes at each step of the tapering, giving practical limits to the tapering angle.

  20. Exponentially tapered Josephson flux-flow oscillator

    DEFF Research Database (Denmark)

    Benabdallah, A.; Caputo, J. G.; Scott, Alwyn C.

    1996-01-01

    We introduce an exponentially tapered Josephson flux-flow oscillator that is tuned by applying a bias current to the larger end of the junction. Numerical and analytical studies show that above a threshold level of bias current the static solution becomes unstable and gives rise to a train of flu......, and (iv) better impedance matching to a load....

  1. Radiation losses of step-tapered channel waveguides.

    Science.gov (United States)

    Marcuse, D

    1980-11-01

    We compute the radiation losses of a rectangular dielectric waveguide (integrated optics channel waveguide) that is tapered so that its wider cross-sectional dimension increases by roughly a factor of three while its narrow dimension remains constant. As the waveguide widens its refractive index decreases to ensure that the waveguide supports only one guided mode. The taper is approximated by a discontinuous staircase curve. A rectangular waveguide taper of 2-microm thickness, tapering from 3- to 10-microm width through fourteen steps of 0.25-microm height, has a minimum loss (at 0.6328-microm wavelength) of 0.13 dB for a 200-microm taper length.

  2. 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?"

  3. Performance of a tapered pulse tube

    Energy Technology Data Exchange (ETDEWEB)

    Swift, G.; Allen, M.; Woolan, J.J. [Cryenco Inc., Denver, CO (United States)

    1998-02-01

    In a well instrumented pulse tube refrigerator having 1,500 W of cooling power at 125 K, the authors have measured the figure of merit of a tapered pulse tube at several operating points. At operating points near the operating point for which the taper was designed, the figure of merit is 0.96. This is close to the theoretical optimum figure of merit 0.97 calculated for this pulse tube considering only two loss mechanisms: heat conduction in the metal pulse tube wall and ordinary thermoacoustic heat transport in the gas within a few thermal penetration depths of the wall. At operating points farther from the design operating point, the measured figure of merit is much lower, as streaming driven convection adds a third loss mechanism.

  4. Cooling arrangement for a tapered turbine blade

    Science.gov (United States)

    Liang, George

    2010-07-27

    A cooling arrangement (11) for a highly tapered gas turbine blade (10). The cooling arrangement (11) includes a pair of parallel triple-pass serpentine cooling circuits (80,82) formed in an inner radial portion (50) of the blade, and a respective pair of single radial channel cooling circuits (84,86) formed in an outer radial portion (52) of the blade (10), with each single radial channel receiving the cooling fluid discharged from a respective one of the triple-pass serpentine cooling circuit. The cooling arrangement advantageously provides a higher degree of cooling to the most highly stressed radially inner portion of the blade, while providing a lower degree of cooling to the less highly stressed radially outer portion of the blade. The cooling arrangement can be implemented with known casting techniques, thereby facilitating its use on highly tapered, highly twisted Row 4 industrial gas turbine blades that could not be cooled with prior art cooling arrangements.

  5. Performance of an elliptically tapered neutron guide

    Science.gov (United States)

    Mühlbauer, Sebastian; Stadlbauer, Martin; Böni, Peter; Schanzer, Christan; Stahn, Jochen; Filges, Uwe

    2006-11-01

    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.

  6. Performance of an elliptically tapered neutron guide

    Energy Technology Data Exchange (ETDEWEB)

    Muehlbauer, Sebastian [Physik-Department E21, Technische Universitaet Muenchen, D-85747 Garching (Germany)]. E-mail: sebastian.muehlbauer@frm2.tum.de; Stadlbauer, Martin [Physik-Department E21, Technische Universitaet Muenchen, D-85747 Garching (Germany); Boeni, Peter [Physik-Department E21, Technische Universitaet Muenchen, D-85747 Garching (Germany); Schanzer, Christan [Labor fuer Neutronenstreuung, Paul Scherrer Institut, CH-5232 Villingen PSI (Switzerland); Stahn, Jochen [Labor fuer Neutronenstreuung, Paul Scherrer Institut, CH-5232 Villingen PSI (Switzerland); Filges, Uwe [Labor fuer Neutronenstreuung, Paul Scherrer Institut, CH-5232 Villingen PSI (Switzerland)

    2006-11-15

    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.

  7. 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.

  8. Sunflower Array Antenna with Adjustable Density Taper

    OpenAIRE

    Maria Carolina Viganó; Giovanni Toso; Gerard Caille; Cyril Mangenot; Lager, Ioan E.

    2009-01-01

    A deterministic procedure to design a nonperiodic planar array radiating a rotationally symmetric pencil beam pattern with an adjustable sidelobe level is proposed. The elements positions are derived by modifying the peculiar locations of the sunflower seeds in such a way that the corresponding spatial density fits a Taylor amplitude tapering law which guarantees the pattern requirements in terms of beamwidth and sidelobe level. Different configurations, based on a Voronoi cell spatial tessel...

  9. Effects of taper on swim performance. Practical implications.

    Science.gov (United States)

    Houmard, J A; Johns, R A

    1994-04-01

    Competitive swimmers commonly focus upon optimising performance at a single competition. A period where training volume is incrementally reduced or "tapered" often precedes such a competition. The use of taper is justified as increases in muscular power, and the restoration of plasma haematocrit, haemoglobin and creatine kinase are evident with this training reduction. A consistent performance improvement of approximately 3% has also been reported with taper in competitive swimmers. However, there are limitations in terms of what comprises a successful taper schedule. It appears that a taper which improves performance involves a substantial (60 to 90%) graded reduction in training volume, and daily high intensity interval work over a 7- to 21-day period. Training frequency should be reduced by no more than 50%; a more conservative estimate would be to reduce frequency by approximately 20%. Optimal performance is likely when the reduction in training frequency is combined with the qualitative knowledge of the coach and/or athlete during taper.

  10. 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 spectral width of the tapered laser is significantly narrowed compared to the freely running laser....

  11. Tapering practices of Croatian open-class powerlifting champions.

    Science.gov (United States)

    Grgic, Jozo; Mikulic, Pavle

    2016-10-27

    The aim of this study was to explore tapering practices among 10 Croatian open-class powerlifting champions (mean ± SD: age 29.2 ± 3.2 years; Wilks coefficient 355.1 ± 54.8). The athletes were interviewed about their tapering practices using a semi-structured interview, after which the audio content was transcribed. The athletes reported decreasing training volume during the taper by 50.5 ± 11.7% using a step type or an exponential type of taper with a fast decay. Training intensity was maintained or increased during the taper, and it reached its highest values 8 ± 3 days before the competition. Training frequency was reduced or maintained during the taper. The final week included a reduction in training frequency by 47.9 ± 17.5% with the last training session performed 3 ± 1 days before the competition. The participants typically stated that the main reasons for conducting the taper were maintaining strength and reducing the amount of fatigue. They also stated that (a) the taper was structured identically for the squat, bench press, and the deadlift; (b) the training during the taper was highly specific, the assistance exercises were removed, and the same equipment was used as during competition; (c) the source of information for tapering was their coach, and training fluctuated based on the coach's feedback; and (d) nutrition, foam rolling, static stretching, and massage were all given extra attention during the taper. These results may aid athletes and coaches in strength sports in terms of the optimization of tapering variables.

  12. Phase Centers of Subapertures in a Tapered Aperture Array.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Bickel, Douglas L. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-11-01

    Antenna apertures that are tapered for sidelobe control can also be parsed into subapertures for Direction of Arrival (DOA) measurements. However, the aperture tapering complicates phase center location for the subapertures, knowledge of which is critical for proper DOA calculation. In addition, tapering affects subaperture gains, making gain dependent on subaperture position. Techniques are presented to calculate subaperture phase center locations, and algorithms are given for equalizing subapertures’ gains. Sidelobe characteristics and mitigation are also discussed.

  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. Welding-fume-induced transmission loss in tapered optical fibers

    Science.gov (United States)

    Yi, Ji-Haeng

    2015-09-01

    This paper presents a method for sensing welding fumes in real time. This method is based on the results of nanoparticle-induced optical-fiber loss experiments that show that the losses are determined by the nanoparticle density and the taper waist. The tapered fiber is obtained by applying heat radiated from hot quartz, and monitoring is done in real time. First, the durability of the tapered fiber during the welding process is proven. Then, the loss is categorized by using the sizes of welding fume particles. The sensitivity to welding fumes increases with increasing size of the particles; consequently, the dimension of the taper waist decreases.

  15. Measurement of Liquid Viscosities in Tapered or Parabolic Capillaries.

    Science.gov (United States)

    Ershov; Zorin; Starov

    1999-08-01

    The possibility of using tapered or parabolic capillaries for measurement of liquid viscosities is investigated both experimentally and theoretically. It is demonstrated that even small deviations in capillary radius from a constant value may substantially affect measurement results. Equations are derived which allow correct analysis of the measurement results in tapered or parabolic capillaries. The following cases are analyzed: a water imbibition into a tapered or parabolic capillary and displacement of one liquid by another immiscible liquid in tapered or parabolic capillaries. Two possibilities are considered: (a) the narrow end of the capillary as capillary inlet and (b) the wide end of the capillary as capillary inlet. Copyright 1999 Academic Press.

  16. Laminar phase flow for an exponentially tapered Josephson oscillator

    DEFF Research Database (Denmark)

    Benabdallah, A.; Caputo, J. G.; Scott, Alwyn C.

    2000-01-01

    Exponential tapering and inhomogeneous current feed were recently proposed as means to improve the performance of a Josephson flux flow oscillator. Extensive numerical results backed up by analysis are presented here that support this claim and demonstrate that exponential tapering reduces...... the small current instability region and leads to a laminar flow regime where the voltage wave form is periodic giving the oscillator minimal spectral width. Tapering also leads to an increased output power. Since exponential tapering is not expected to increase the difficulty of fabricating a flux flow...

  17. Low-crosstalk Si arrayed waveguide grating with parabolic tapers.

    Science.gov (United States)

    Ye, Tong; Fu, Yunfei; Qiao, Lei; Chu, Tao

    2014-12-29

    A silicon arrayed waveguide grating (AWG) with low channel crosstalk was demonstrated by using ultra-short parabolic tapers to connect the AWG's free propagation regions and single-mode waveguides. The tapers satisfied the requirements of low-loss mode conversion and lower channel crosstalk from the coupling of neighboring waveguides in the AWGs. In this work, three different tapers, including parabolic tapers, linear tapers, and exponential tapers, were theoretically analyzed and experimentally investigated for a comparison of their effects when implemented in AWGs. The experimental results showed that the AWG with parabolic tapers had a crosstalk improvement up to 7.1 dB compared with the others. Based on the advantages of parabolic tapers, a 400-GHz 8 × 8 cyclic AWG with 2.4 dB on-chip loss and -17.6~-25.1 dB crosstalk was fabricated using a simple one-step etching process. Its performance was comparable with that of existing AWGs with bi-level tapers, which require complicated two-step etching fabrication processes.

  18. 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.

  19. 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...

  20. 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...

  1. Window taper functions for subaperture processing.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2013-12-01

    It is well known that the spectrum of a signal can be calculated with a Discrete Fourier Transform (DFT), where best resolution is achieved by processing the entire data set. However, in some situations it is advantageous to use a staged approach, where data is first processed within subapertures, and the results are then combined and further processed to a final result. An artifact of this approach is the creation of grating lobes in the final response. The nature of the grating lobes, including their amplitude and spacing, is an artifact of window taper functions, subaperture offsets, and subaperture processing parameters. We assess these factors and exemplify their effects.

  2. Soliton blueshift in tapered photonic crystal fibers.

    Science.gov (United States)

    Stark, S P; Podlipensky, A; Russell, P St J

    2011-02-25

    We show that solitons undergo a strong blueshift in fibers with a dispersion landscape that varies along the direction of propagation. The experiments are based on a small-core photonic crystal fiber, tapered to have a core diameter that varies continuously along its length, resulting in a zero-dispersion wavelength that moves from 731 nm to 640 nm over the transition. The central wavelength of a soliton translates over 400 nm towards a shorter wavelength. This is accompanied by strong emission of radiation into the UV and IR spectral regions. The experimental results are confirmed by numerical simulation.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    ) that are confined laterally between the tapered groove sidewalls and propagate either along the groove axis or normal to the planar surface, and channeled plasmon polaritons (CPPs) that occupy the tapered groove profile and propagate exclusively along the groove axis. Both GSPs and CPPs exhibit an assortment...

  4. 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.

  5. 5 CFR 353.303 - Restoration rights of TAPER employees.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Restoration rights of TAPER employees... Restoration rights of TAPER employees. An employee serving in the competitive service under a temporary... employee serving in a position classified above GS-15), is entitled to be restored to the position he...

  6. Heat-and-pull rig for fiber taper fabrication

    Science.gov (United States)

    Ward, Jonathan M.; O'Shea, Danny G.; Shortt, Brian J.; Morrissey, Michael J.; Deasy, Kieran; Nic Chormaic, Síle G.

    2006-08-01

    We describe a reproducible method of fabricating adiabatic tapers with 3-4μm diameter. The method is based on a heat-and-pull rig, whereby a CO2 laser is continuously scanned across a length of fiber that is being pulled synchronously. Our system relies on a CO2 mirror mounted on a geared stepper motor in order to scan the laser beam across the taper region. We show that this system offers a reliable alternative to more traditional rigs incorporating galvanometer scanners. We have routinely obtained transmission losses between 0.1 and 0.3dB indicating the satisfactory production of adiabatic tapers. The operation of the rig is described in detail and an analysis on the produced tapers is provided. The flexibility of the rig is demonstrated by fabricating prolate dielectric microresonators using a microtapering technique. Such a rig is of interest to a range of fields that require tapered fiber fabrication such as microcavity-taper coupling, atom guiding along a tapered fiber, optical fiber sensing, and the fabrication of fused biconical tapered couplers.

  7. Realization of Tapered Waveguide by Stretching the Rod Waveguide

    Institute of Scientific and Technical Information of China (English)

    XIA Ke-yu; YU Rong-jin; MENG Hua-mao

    2004-01-01

    By stretching the rod waveguide with different velocities in opposite directions,the tapered waveguide can be fabricated.In condition of taking no account of volume expansion caused by heating and under the assumptions of volume conservation,the rod waveguide can be stretched freely in the heated region without being stretched outside of the heated region. A model,which shows the relation of the transition shape and the two factors,that is the ratio of two velocity and the heated region length,is presented for the shape of the taper transition through mathematic deduction.Based on this model,a desired tapered waveguide can be fabricated.The tapered waveguide are widely used for fabricating tapered fiber couplers and sensors.In addition,the conclusion can be used for fabricating fused fiber coupler.

  8. Sensitive acoustic vibration sensor using single-mode fiber tapers.

    Science.gov (United States)

    Li, Yi; Wang, Xiaozhen; Bao, Xiaoyi

    2011-05-01

    Optical fiber sensors are a good alternative to piezoelectric devices in electromagnetic sensitive environments. In this study, we reported a fiber acoustic sensor based on single-mode fiber (SMF) tapers. The fiber taper is used as the sensing arm in a Mach-Zehnder interferometer. Benefiting from their micrometer dimensions, fiber tapers have shown higher sensitivities to the acoustic vibrations than SMFs. Under the same conditions, the thinnest fiber taper in this report, with a diameter of 1.7 µm, shows a 20 dB improvement in the signal to noise ratio as compared to that of an SMF. This acoustic vibration sensor can detect the acoustic waves over the frequencies of 30 Hz-40 kHz, which is limited by the acoustic wave generator in experiments. We also discussed the phase changes of fiber tapers with different diameters under acoustic vibrations.

  9. The atomic world spooky? It ain't necessarily so! emergent quantum mechanics, how the classical laws of nature can conspire to cause quantum-like behaviour

    CERN Document Server

    van Holten, Theo

    2017-01-01

    The present book takes the discovery that quantum-like behaviour is not solely reserved to atomic particles one step further. If electrons are modelled as vibrating droplets instead of the usually assumed point objects, and if the classical laws of nature are applied, then exactly the same behaviour as in quantum theory is found, quantitatively correct! The world of atoms is strange and quantum mechanics, the theory of this world, is almost magic. Or is it? Tiny droplets of oil bouncing round on a fluid surface can also mimic the world of quantum mechanics. For the layman - for whom the main part of this book is written - this is good news. If the everyday laws of nature can conspire to show up quantum-like phenomena, there is hope to form mental pictures how the atomic world works. The book is almost formula-free, and explains everything by using many sketches and diagrams. The mathematical derivations underlying the main text are kept separate in a -peer reviewed - appendix. The author, a retired professor ...

  10. Tapering Practices of New Zealand's Elite Raw Powerlifters.

    Science.gov (United States)

    Pritchard, Hayden J; Tod, David A; Barnes, Matthew J; Keogh, Justin W; McGuigan, Michael R

    2016-07-01

    Pritchard, HJ, Tod, DA, Barnes, MJ, Keogh, JW, and McGuigan, MR. Tapering practices of New Zealand's elite raw powerlifters. J Strength Cond Res 30(7): 1796-1804, 2016-The major aim of this study was to determine tapering strategies of elite powerlifters. Eleven New Zealand powerlifters (28.4 ± 7.0 years, best Wilks score of 431.9 ± 43.9 points) classified as elite were interviewed, using semistructured interviews, about their tapering strategies. Interviews were transcribed verbatim and content analyzed. Total training volume peaked 5.2 ± 1.7 weeks from competition while average training intensity (of 1 repetition maximum) peaked 1.9 ± 0.8 weeks from competition. During tapering, volume was reduced by 58.9 ± 8.4% while intensity was maintained (or slightly reduced) and the final weight training session was performed 3.7 ± 1.6 days out from competition. Participants generally stated that tapering was performed to achieve full recovery; that accessory work was removed around 2 weeks out from competition; and deadlifting takes longer to recover from than other lifts. Typically participants stated that trial and error, and changes based on "feel" were the sources of tapering strategies; equipment used and movements performed during tapering are the same as in competition; nutrition was manipulated during the taper (for weight cutting or performance aims); and poor tapering occurred when too long (1 week or more) was taken off training. These results suggest that athletes may benefit from continuing to strength train before important events with reduced volume and maintained intensity. Only exercises that directly assist sports performance should remain in the strength program during tapering, to assist with reductions in fatigue while maintaining/improving strength expression and performance.

  11. Pulse propagation in the tapered wiggler

    Science.gov (United States)

    Al-Abawi, H.; McIver, J. K.; Moore, G. T.; Scully, M. O.

    Theory and preliminary numerical calculations are presented for coherent optical and electron pulse propagation in a free-electron laser with a tapered wiggler. Since only trapped electrons contribute significantly to the laser radiation, it is possible to define generalized 'slow' space-time coordinates in terms of which the electron pulse envelope may be considered constant. The theory is outlined first for the helical wiggler and then is developed for an arbitrary quasiperiodic wiggler, using a more rigorous 'multiple-scaling' approach. In the latter case a modified definition of the electron phase angle is required, and optical harmonic generation is predicted. The numerical calculations show that substantial energy extraction is achievable, but that the optical pulse rapidly breaks up into a series of spikes in the time domain. Surprisingly, the optical spectrum remains quite smooth in appearance.

  12. Group delay and dispersion tailoring in nonadiabatic tapered fibers

    Science.gov (United States)

    Mas, Sara; Palací, Jesús; Martí, Javier

    2016-09-01

    The dispersion profile of a nonadiabatic tapered singlemode fiber is characterized and dynamically tuned. Its group delay and dispersion parameters are measured and compared to those of a standard singlemode fiber. The dispersion profile can be tuned by introducing a phase shift through mechanical stretching. Coarse tuning is also obtained by varying the surrounding medium of the tapered fiber. Dispersion values up to 700 ps/nm·km in nonadiabatic tapered fibers are obtained for the first time. Dynamic tuning exposed here can be very useful in applications such as nonlinearities or soliton generation.

  13. 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....

  14. Development of small bore, high speed tapered roller bearing

    Science.gov (United States)

    Morrison, F. R.; Gassel, S. S.; Bovenkerk, R. L.

    1981-01-01

    The performance of four rolling bearing configurations for use on the input pinion shaft of a proposed commercial helicopter transmission was evaluated. The performance characteristics of a high speed tapered roller bearing operating under conditions comparable to those existing at this input pinion shaft were defined. The tapered roller bearing shaft support configuration was developed for the gearbox using commercially available bearing designings. The configuration was optimized and interactive thermomechanically system analyzed. Automotive pinion quality tapered roller bearings were found to be reliable under load and speed conditions in excess of those anticipated in the helicopter transmission. However, it is indicated that the elastohydrodynamic lubricant films are inadequate.

  15. Slow light in tapered slot photonic crystal waveguide

    Institute of Scientific and Technical Information of China (English)

    WU Jun; LI YanPing; YANG ChuanChuan; PENG Chao; WANG ZiYu

    2009-01-01

    A slotted single-mode photonic crystal waveguide with a linear tapered slot is presented to realize slow light, whose dispersion curve is shifted by changing the slot width. When the slot width is reduced, the band curve shifts in the tapered structure, and the group velocity of light approach zero at the cut-off frequency. Therefore, different frequency components of the guided light are slowed down even loca-lized along the propagation direction inside a tapered slot photonic crystal waveguide. Furthermore, this structure can confine slow light-wave in a narrow slot waveguide, which may effectively enhance the interaction between slow light and the low-index wave-guiding materials filled in the slot. In addition, this tapered slot structure can be used to compensate group velocity dispersion of slow light by mod-ifying the structure, thus opening the opportunity for ultra-wide bandwidth slow light.

  16. Low Loss S-Bend Structure With Tapered Curved Waveguides

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A novel S-bend with tapered curved waveguides is proposed. The normalized transmitted power is greater than the conventional bend with weakly guided waveguides. Small size and low loss can be reached by the proposed S-bend.

  17. Optimization of tapered busses for solar cell contacts

    Science.gov (United States)

    Landis, G. A.

    1979-01-01

    Some fraction of the power produced by a solar cell is necessarily lost by series resistance associated with the metallized contact grid and by shadowing of cell active area by the grid. There are several approaches to reducing these losses, such as choosing a more efficient pattern, optimizing line spacing, and using tapered buses. The present paper analyzes tapered lines and derives from this analysis a theoretical lower bound to metallization power loss, independent of pattern chosen.

  18. Optical inclinometer based on fibre-taper-modal Michelson interferometer

    Science.gov (United States)

    Amaral, L. M. N.; Frazão, O.; Santos, J. L.; Lobo Ribeiro, A. B.

    2010-09-01

    An inclinometer sensor based on optical fibre-taper-modal Michelson interferometer is demonstrated. The magnitude of the tilt (bending angle of the fibre taper interferometer) is obtained by passive interferometric interrogation based on the generation of two quadrature phase-shifted signals from two fibre Bragg gratings. Optical phase-to-rotation sensitivity of 1.13 rad/degree with a 14 mrad/√Hz resolution is achieved.

  19. Vertical Dynamic Impedance of Tapered Pile considering Compacting Effect

    Directory of Open Access Journals (Sweden)

    Wenbing Wu

    2013-01-01

    Full Text Available Based on complex stiffness transfer model, the vertical vibration of tapered pile embedded in layered soil is theoretically investigated by considering the compacting effect of the soil layer surrounding the tapered pile in the piling process. Allowing for the stratification of the surrounding soil and variable crosssection of the tapered pile, the pile-soil system is discretized into finite segments. By virtue of the complex stiffness transfer model to simulate the compacting effect, the complex stiffness of different soil segments surrounding the tapered pile is obtained. Then, substituting the complex stiffness into the vertical dynamic governing equation of tapered pile, the analytical solution of vertical dynamic impedance of tapered pile under vertical exciting force is derived by means of the Laplace technique and impedance function transfer method. Based on the presented solutions, the influence of compacting effect of surrounding soil on vertical dynamic impedance at the pile head is investigated within the low frequency range concerned in the design of dynamic foundation.

  20. The effects of tapering on power-force-velocity profiling and jump performance in professional rugby league players.

    Science.gov (United States)

    de Lacey, James; Brughelli, Matt; McGuigan, Michael; Hansen, Keir; Samozino, Pierre; Morin, Jean-Benoit

    2014-12-01

    The purpose of this study was to investigate the effects of a preseason taper on individual power-force-velocity profiles and jump performance in professional National Rugby League players. Seven professional rugby league players performed concentric squat jumps using ascending loads of 25, 50, 75, 100% body mass before and after a 21-day step taper leading into the in-season. Linear force-velocity relationships were derived, and the following variables were obtained: maximum theoretical velocity (V0), maximum theoretical force (F0), and maximum power (Pmax). The players showed likely-to-very likely increases in F0 (effect size [ES] = 0.45) and Pmax (ES = 0.85) from pre to posttaper. Loaded squat jump height also showed likely-to-most likely increases at each load (ES = 0.83-1.04). The 21-day taper was effective at enhancing maximal power output and jump height performance in professional rugby players, possibly as a result of a recovery from fatigue and thus increased strength capability after a prolonged preseason training period. Rugby league strength and conditioning coaches should consider reducing training volume while maintaining intensity and aerobic conditioning (e.g., step taper) leading into the in-season.

  1. 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.

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

    Science.gov (United States)

    Zahedi, Moosarreza Shamsyeh; Khan, Mir Yaseen Ali

    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.

  3. Stem taper equations for poplars growing on farmland in Sweden

    Institute of Scientific and Technical Information of China (English)

    Birger Hjelm

    2013-01-01

    We developed a simple polynomial taper equation for poplars growing on former farmland in Sweden and also evaluated the performance of some well-known taper equations.In Sweden there is an increasing interest in the use of poplar.Effective management of poplar plantations for high yield production would be facilitated by taper equations providing better predictions of stem volume than currently available equations.In the study a polynomial stem taper equation with five parameters was established for individual poplar trees growing on former farmland.The outputs of the polynomial taper equation were compared with five published equations.Data for fitting the equations were collected from 69 poplar trees growing at 37 stands in central and southern Sweden (lat.55-60° N).The mean age of the stands was 21 years (range 14-43),the mean density 984 stemsha-1 (198-3,493),and the mean diameter at breast height (outside bark) 25 cm (range 12-40).To verify the tested equations,performance of accuracy and precision diameter predictions at seven points along the stem was closely analyzed.Statistics used for evaluation of the equations indicated that the variable exponent taper equation presented by Kozak (1988) performed best and can be recommended.The stem taper equation by Kozak (1988) recommended in the study is likely to be beneficial for optimising the efficiency and profitability of poplar plantation management.The constructed polynomial equation and the segmented equation presented by Max & Burkhart (1976) were second and third ranked.Due to the statistical complexity of Kozak's equation,the constructed polynomial equation is alternatively recommended when a simple model is requested and larger bias is accepted.

  4. Single muscle fiber gene expression with run taper.

    Science.gov (United States)

    Murach, Kevin; Raue, Ulrika; Wilkerson, Brittany; Minchev, Kiril; Jemiolo, Bozena; Bagley, James; Luden, Nicholas; Trappe, Scott

    2014-01-01

    This study evaluated gene expression changes in gastrocnemius slow-twitch myosin heavy chain I (MHC I) and fast-twitch (MHC IIa) muscle fibers of collegiate cross-country runners (n = 6, 20±1 y, VO₂max = 70±1 ml•kg-1•min-1) during two distinct training phases. In a controlled environment, runners performed identical 8 kilometer runs (30:18±0:30 min:s, 89±1% HRmax) while in heavy training (∼72 km/wk) and following a 3 wk taper. Training volume during the taper leading into peak competition was reduced ∼50% which resulted in improved race times and greater cross-section and improved function of MHC IIa fibers. Single muscle fibers were isolated from pre and 4 hour post run biopsies in heavily trained and tapered states to examine the dynamic acute exercise response of the growth-related genes Fibroblast growth factor-inducible 14 (FN14), Myostatin (MSTN), Heat shock protein 72 (HSP72), Muscle ring-finger protein-1 (MURF1), Myogenic factor 6 (MRF4), and Insulin-like growth factor 1 (IGF1) via qPCR. FN14 increased 4.3-fold in MHC IIa fibers with exercise in the tapered state (Ptwitch muscle fiber performance gains previously observed after taper in competitive endurance athletes.

  5. Temperature distribution and scuffing of tapered roller bearing

    Science.gov (United States)

    Wang, Ailin; Wang, Jiugen

    2014-11-01

    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.

  6. 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.

  7. Induced Charge Electrokinetic Phenomena in Tapered Conducting Nanochannels

    CERN Document Server

    Zhao, Cunlu

    2010-01-01

    We conducted a fundamental study of electrokinetics in conducting (ideally polarizable) tapered nanochannels. Based on the theory of induced charge electrokinetics, the external driving electric fields polarize the uncharged conducting walls of nanochannels and consequently induce surface charges on these walls which also can play the roles of physiochemical bond charges in conventional electrokinetics. Due to complex coupling involved in the problem, the complete model including the Poisson equation for electric potential, the Nernst-Planck equation for ions transport and the Navier-stokes equation for liquid transport are adopted to numerically investigate the electrokinetic phenomena inside the tapered nanofluidic nanochannel with conducting walls. The results reveal that, the flow inside the tapered conducting nanochannel exhibit so-called full wave flow rectification that the electrolyte solution always flows from the narrow end of a nanochannel to the wide end for either a forward bias (electric field f...

  8. Optically active mechanical modes of tapered optical fibers

    CERN Document Server

    Wuttke, Chrisitan; Rauschenbeutel, Arno

    2013-01-01

    Tapered optical fibers with a nanofiber waist are widely used tools for efficient coupling of light to photonic devices or quantum emitters via the nanofiber's evanescent field. In order to ensure well-controlled coupling, the phase and polarization of the nanofiber guided light field have to be stable. Here, we show that in typical tapered optical fibers these quantities exhibit high-frequency thermal fluctuations. They originate from high-Q torsional oscillations that opto-mechanically couple to the nanofiber-guided light. We present a simple ab-initio theoretical model that quantitatively explains the torsional mode spectrum and that can be used to design tapered optical fibers with tailored mechanical properties.

  9. Confinement loss in adiabatic photonic crystal fiber tapers

    Science.gov (United States)

    Kuhlmey, Boris T.; Nguyen, Hong C.; Steel, M. J.; Eggleton, Benjamin J.

    2006-09-01

    We numerically study confinement loss in photonic crystal fiber (PCF) tapers and compare our results with previously published experimental data. Agreement between theory and experiment requires taking into account hole shrinkage during the tapering process, which we measure by using a noninvasive technique. We show that losses are fully explained within the adiabatic approximation and that they are closely linked to the existence of a fundamental core-mode cutoff. This cutoff is equivalent to the core-mode cutoff in depressed-cladding fibers, so that losses in PCF tapers can be obtained semiquantitatively from an equivalent depressed-cladding fiber model. Finally, we discuss the definition of adiabaticity in this open boundary problem.

  10. Acoustic vibration sensor based on nonadiabatic tapered fibers.

    Science.gov (United States)

    Xu, Ben; Li, Yi; Sun, Miao; Zhang, Zhen-Wei; Dong, Xin-Yong; Zhang, Zai-Xuan; Jin, Shang-Zhong

    2012-11-15

    A simple and low-cost vibration sensor based on single-mode nonadiabatic fiber tapers is proposed and demonstrated. The environmental vibrations can be detected by demodulating the transmission loss of the nonadiabatic fiber taper. Theoretical simulations show that the transmission loss is related to the microbending of the fiber taper induced by vibrations. Unlike interferometric sensors, this vibration sensor does not need any feedback loop to control the quadrature point to obtain a stable performance. In addition, it has no requirement for the coherence of the light source and is insensitive to temperature changes. Experimental results show that this sensing system has a wide frequency response range from a few hertz to tens of kilohertz with the maximal signal to noise ratio up to 73 dB.

  11. Single muscle fiber gene expression with run taper.

    Directory of Open Access Journals (Sweden)

    Kevin Murach

    Full Text Available This study evaluated gene expression changes in gastrocnemius slow-twitch myosin heavy chain I (MHC I and fast-twitch (MHC IIa muscle fibers of collegiate cross-country runners (n = 6, 20±1 y, VO₂max = 70±1 ml•kg-1•min-1 during two distinct training phases. In a controlled environment, runners performed identical 8 kilometer runs (30:18±0:30 min:s, 89±1% HRmax while in heavy training (∼72 km/wk and following a 3 wk taper. Training volume during the taper leading into peak competition was reduced ∼50% which resulted in improved race times and greater cross-section and improved function of MHC IIa fibers. Single muscle fibers were isolated from pre and 4 hour post run biopsies in heavily trained and tapered states to examine the dynamic acute exercise response of the growth-related genes Fibroblast growth factor-inducible 14 (FN14, Myostatin (MSTN, Heat shock protein 72 (HSP72, Muscle ring-finger protein-1 (MURF1, Myogenic factor 6 (MRF4, and Insulin-like growth factor 1 (IGF1 via qPCR. FN14 increased 4.3-fold in MHC IIa fibers with exercise in the tapered state (P<0.05. MSTN was suppressed with exercise in both fiber types and training states (P<0.05 while MURF1 and HSP72 responded to running in MHC IIa and I fibers, respectively, regardless of training state (P<0.05. Robust induction of FN14 (previously shown to strongly correlate with hypertrophy and greater overall transcriptional flexibility with exercise in the tapered state provides an initial molecular basis for fast-twitch muscle fiber performance gains previously observed after taper in competitive endurance athletes.

  12. In vivo oxide-induced stress corrosion cracking of Ti-6Al-4V in a neck-stem modular taper: Emergent behavior in a new mechanism of in vivo corrosion.

    Science.gov (United States)

    Gilbert, Jeremy L; Mali, Sachin; Urban, Robert M; Silverton, Craig D; Jacobs, Joshua J

    2012-02-01

    In vivo modular taper corrosion in orthopedic total joint replacements has been documented to occur for head-neck tapers, modular-body tapers, and neck-stem tapers. While the fretting corrosion mechanism by which this corrosion occurs has been described in the literature, this report shows new and as yet unreported mechanisms at play. A retrieved Ti-6Al-4V/Ti-6Al-4V neck-stem taper interface, implanted for 6 years is subjected to failure analysis to document taper corrosion processes that lead to oxide driven crack formation on the medial side of the taper. Metallurgical sectioning techniques and scanning electron microscopy analysis are used to document the taper corrosion processes. The results show large penetrating pitting attack of both sides of the taper interface where corrosion selectively attacks the beta phase of the microstructure and eventually consumes the alpha phase. The pitting attack evolves into plunging pits that ultimately develop into cracks where the crack propagation process is one of corrosion resulting in oxide formation and subsequent reorganization. This process drives open the crack and advances the front by a combination of oxide-driven crack opening stresses and corrosion attack at the tip. The oxide that forms has a complex evolving structure including a network of transport channels that provide access of fluid to the crack tip. This emergent behavior does not appear to require continued fretting corrosion to propagate the pitting and cracking. This new mechanism is similar to stress corrosion cracking where the crack tip stresses arise from the oxide formation in the crack and not externally applied tensile stresses.

  13. 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.

  14. 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.

  15. 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 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 order...

  16. Tapered plasma channels to phase-lock accelerating and focusing forces in laser-plasma accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Rittershofer, W.; Schroeder, C.B.; Esarey, E.; Gruner, F.J.; Leemans, W.P.

    2010-05-17

    Tapered plasma channels are considered for controlling dephasing of a beam with respect to a plasma wave driven by a weakly-relativistic, short-pulse laser. Tapering allows for enhanced energy gain in a single laser plasma accelerator stage. Expressions are derived for the taper, or longitudinal plasma density variation, required to maintain a beam at a constant phase in the longitudinal and/or transverse fields of the plasma wave. In a plasma channel, the phase velocities of the longitudinal and transverse fields differ, and, hence, the required tapering differs. The length over which the tapered plasma density becomes singular is calculated. Linear plasma tapering as well as discontinuous plasma tapering, which moves beams to adjacent plasma wave buckets, are also considered. The energy gain of an accelerated electron in a tapered laser-plasma accelerator is calculated and the laser pulse length to optimize the energy gain is determined.

  17. Fabrication and characterization of bare Ge-Sb-Se chalcogenide glass fiber taper

    Science.gov (United States)

    Luo, Baohua; Wang, Yingying; Sun, Ya'nan; Dai, Shixun; Yang, Peilong; Zhang, Peiqing; Wang, Xunsi; Chen, Feifei; Wang, Rongping

    2017-01-01

    In this work, Ge15Sb20Se65 bare glass fiber with a diameter of 500 μm was fabricated, and then tapered with different tapering parameters. The analysis of Raman and energy dispersive X-ray spectra (EDS) indicated that, a slight change in the chemical composition of the glass, fiber and tapering fiber has negligible effect on the glass structure. It was found that, the waist diameter decreases exponentially with increasing tapering length and speed, and high quality taper fiber with the cone diameter of 2.65 μm can be achieved under the optimal tapering conditions. Finally, the simulated and experimental results of the output transmission under different waist length and taper ratio show that the transmission decreases with increasing waist length and taper ratio.

  18. Optimization of group delay response of (apodized) tapered fiber Bragg grating by shaping taper transition and apodization window

    Science.gov (United States)

    Markowski, Konrad; Jedrzejewski, Kazimierz; Osuch, Tomasz

    2016-09-01

    This article presents implementation of the Simulated Annealing (SA) algorithm for tapered fiber Bragg gratings (TFBGs) design. Particularly, together with well-known Coupled Mode Theory (CMT) and Transfer Matrix Method (TMM) the algorithm optimizes the group delay response of TFBG, by simultaneous shaping of both apodization function and tapered fiber transition profile. Prior to the optimization process, numerical model for TFBG design has been validated. Preliminary results reveal great potential of the SA-based approach and with proper definition of the design criteria may be even applied for optimization of the spectral properties of TFBGs.

  19. 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....

  20. Deep-blue supercontinnum sources with optimum taper profiles – verification of GAM

    DEFF Research Database (Denmark)

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

    2012-01-01

    We use an asymmetric 2 m draw-tower photonic crystal fiber taper to demonstrate that the taper profile needs careful optimisation if you want to develop a supercontinuum light source with as much power as possible in the blue edge of the spectrum. In particular we show, that for a given taper...

  1. Tapered optical fiber sensor for chemical pollutants detection in seawater

    Science.gov (United States)

    Irigoyen, Maite; Sánchez-Martin, Jose Antonio; Bernabeu, Eusebio; Zamora, Alba

    2017-04-01

    Three tapered silica optical fibers, uncoated and coated with metallic (Al or Cu) and dielectric layers (TiO2), are employed to determine the presence of oil and Hazardous and Noxious Substances (HNS from now on) in water, by means of the measurement of their spectral transmittance. With our experimental assembly, the presence of oil and HNS spills can be detected employing the three different kinds of tapers, since the complete range of refractive indices of the pollutants (1.329–1.501) is covered with these tapers. The most suitable spectral range to detect the presence of a chemical pollutant in seawater has been identified and a complete spectral characterization of the three types of optical fiber tapers has been carried out. The results obtained show that, in general terms, these devices working together can be employed for the early detection of oil and HNS spills in seawater in a marine industrial environment. These sensors have many advantages, such as its low cost, its simplicity and versatility (with interesting properties as quick response and repeatability), and especially that they can be self-cleaned with seawater in motion.

  2. Heat-and-pull rig for fiber taper fabrication

    NARCIS (Netherlands)

    Ward, Jonathan M.; O'Shea, Danny G.; Shortt, Brian J.; Morrissey, Michael J.; Deasy, Kieran; Chormaic, Sile G. Nic

    2006-01-01

    We describe a reproducible method of fabricating adiabatic tapers with 3-4 mu m diameter. The method is based on a heat-and-pull rig, whereby a CO(2) laser is continuously scanned across a length of fiber that is being pulled synchronously. Our system relies on a CO(2) mirror mounted on a geared ste

  3. Structural Analysis of Taper-Threaded Rebar Couplers

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Seok Jae [Univ. of Ulsan, Ulsan (Korea, Republic of); Kwon, Hyuk Mo; Seo, Sang Hwan [Sammi Precision Co. Ltd., Ulsan (Korea, Republic of)

    2014-05-15

    A number of rebar couplers were developed by the leading companies. The information about the products is available from the company website. However, the theory on the taper-threaded coupler is not available. In this paper, the mechanics of the taper-thread was developed to understand the effect of the tightening torque. Structural analysis of our own newly developed rebar coupler was done to improve the strength of the coupler. The taper-threaded rebar coupler was analyzed. The tightening of the rebar into the coupler developed a circumferential stress in the coupler. The circumferential stress depends on the coefficient of friction as well as the tightening torque. The circumferential stress is less than the allowable stress 20 kgf/mm{sup 2} of the material for the coefficient of friction greater than 0.1. The tightening of the rebar into the coupler and the subsequent tensioning was simulated using CATIA. Linear elastic analysis considering contact was done. The tightening of the taper-threaded rebar developed a uniform stress distribution in both standard coupler and position coupler. On the other hand, the tightening of the nut in the axial direction developed a non-uniform stress distribution. Similarly the tensioning also developed a non-uniform stress distribution.

  4. Impedance Matching of Tapered Slot Antenna using a Dielectric Transformer

    Science.gov (United States)

    Simons, R. N.; Lee, R. Q.

    1998-01-01

    A new impedance matching technique for tapered slot antennas using a dielectric transformer is presented. The technique is demonstrated by measuring the input impedance, Voltage Standing Wave Ratio (VSWR) and the gain of a Vivaldi antenna (VA). Measured results at Ka-Band frequencies are presented and discussed.

  5. Linearly tapered slot antenna circular array for mobile communications

    Science.gov (United States)

    Simons, Rainee N.; Kelly, Eron; Lee, Richard Q.; Taub, Susan R.

    1993-01-01

    The design, fabrication and testing of a conformal K-band circular array is presented. The array consists of sixteen linearly tapered slot antennas (LTSA). It is fed by a 1:16 microstrip line power splitter via electromagnetic coupling. The array has an omni-directional pattern in the azimuth plane. In the elevation plane the beam is displaced above the horizon.

  6. Terahertz field imaging inside tapered parallel plate waveguides

    DEFF Research Database (Denmark)

    Iwaszczuk, Krzysztof; Andryieuski, Andrei; Lavrinenko, Andrei

    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...

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

    DEFF Research Database (Denmark)

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

    2010-01-01

    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...

  8. 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 in...

  9. 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…

  10. 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.

  11. Nonlinear Vibration of an Elastically Restrained Tapered Beam

    DEFF Research Database (Denmark)

    Karimpour, S; Ganji, S.S; Barari, Amin;

    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 re...

  12. Wear of K3 and ProTaper files after simulated clinical use in curved canals

    Directory of Open Access Journals (Sweden)

    Patrícia de Almeida Rodrigues Silva e Souza

    2009-01-01

    Full Text Available Objective: To assess wear, after simulated clinical use of K3 (SybronEndo, Orange, CA, EUA and ProTaper files (Dentsply-Maillefer, Tulsa, Oklahoma, EUA in 46 mesiovestibular roots of human maxillary first molars, recently extracted and with mean angulation of 40°.Methods: The teeth were divided as follows: a K3 (SybronEndo, Orange, CA, EUA (with radial bands and b ProTaper (Dentsply-Maillefer, Tulsa, Oklahoma, EUA (without radial bands. The files were assessed by scanning electronic microscopy before first use to visualize fabrication defects, and after 7 and 13 cycles of debridement in the canals. Debridement with files K3 (SybronEndo, Orange, CA, EUA and ProTaper (Dentsply-Maillefer, Tulsa, Oklahoma, EUA was performed in accordance with the manufacturers’ recommendations. The criteria for wear assessment were: defects (stretching, shortening/spiral inversion, presence of craters, oblique cracks and fracture. After assessment by SEM and before they were used, metal barbs on the crest of the spirals and oblique scratches due to the machining process were found in all the files.Results: In the K3 system (SybronEndo, Orange, CA, USA, after being used seven times, all the instruments showed cutting angle defects,and 25/08 and 25/10 had oblique cracks in the body of the active part leading to ductile fracture after being used for the eighth time. In the ProTaper system (Dentsply-Maillefer, Tulsa, Oklahoma, USA, after being used seven times, in addition to cutting angle defects, the files also presented cracks, and ruptile fracture occurred in F3 during use for the thirteenth time. At the end of preparation, craters were seen along the active part of the files.Conclusion: In the final analysis, it was seen that the system are equivalent with regard to the defects found, irrespective of the active part design,being proportional to the number of cycles of use, and these defects could act as points of greater fragility, favoring fracture.

  13. Loss Factor of Tapered Structures for Short Bunches

    Energy Technology Data Exchange (ETDEWEB)

    Blednykh, A.

    2011-03-28

    Using the electromagnetic simulation code ECHO, we have found a simple phenomenological formula that accurately describes the loss factor for short bunches traversing an axisymmetric tapered collimator. In this paper, we consider tapered collimators with rectangular cross-section and use the GdfidL code to calculate the loss factor dependence on the geometric parameters for short bunches. The results for both axisymmetric and rectangular collimators are discussed. The behaviour of the impedance of tapered structures for very short bunches in the optical regime has been determined in refs. [10,11]. Here, for the loss factors for two particular geometries, we have studied the departure from the optical regime behaviour as bunch length is increased. In both cases, the ratio of the loss factor for the tapered collimator to the loss factor in the optical regime is a function only of the scaling parameter {sigma}L/d{sup 2}. The fact that the bunch length a and the taper length L appear as a product is consistent with the recent scaling derived by Stupakov in ref. [12], since there is only a weak dependence on g. One noteworthy fact that is not a priori expected is that only the larger radius or vertical half-aperture d appears. The reduction factor is independent of b. Moreover, it is striking that the specific form involving the arctan given in Eq. (5) holds for both geometries, with only the coefficient {mu} differing by a factor of {approx}2 for flat vs round. This suggests that there may be a useful phenomenological form for more general geometries which may follow from natural extensions of Eq. (5). This possibility is presently being investigated.

  14. Review on the Evolution of Co-conspirator Vicarious Liability Rule in American Criminal Law%美国刑法共谋者替代责任规则之演进述评

    Institute of Scientific and Technical Information of China (English)

    张淑芳; 林俊辉

    2012-01-01

    The issue as to whether a conspirator should be held liable for the substantive crimes committed by his co-conspirators has gone through a process of evolution from negativism to basical affirmativeness and finally to substantial restriction.The standard of attenuation in kind is the restatement of the standard of reasonable foreseeability.As a result,it could not impose strict limit on Pinkerton Rule.The standard of attenuation in fact or more than minor participation is better for imposing limit on conspiratorial vicarious liability and excluding the conspirators,who are minor participators in the conspiracy and attenuated from the substantive crimes,from the vicarious liability.It is necessary for Chinese Criminal Law to refer to the standard of attenuation in fact or more than minor participation to deal with the similar cases.%共谋者是否对共同共谋者实行的实体犯罪承担替代责任,美国刑法以平克顿案为分水岭,经历否定论→基本肯定论→实质限定论的演变历程。类型弱化标准是可合理预见性标准的重述,可能无法确保对平克顿规则的严格限制。事实弱化标准或超出轻微参与标准,更有利于限制共谋者替代责任的适用范围,将轻微参与共谋而与实体犯罪的实行存在弱化关系的共谋者排除在替代责任的适用范围之外。事实弱化或超出轻微参与标准,对我国处理类似案件具有借鉴意义。

  15. Carbon dioxide laser fabrication of fused-fiber couplers and tapers.

    Science.gov (United States)

    Dimmick, T E; Kakarantzas, G; Birks, T A; Russell, P S

    1999-11-20

    We report the development of a fiber taper and fused-fiber coupler fabrication rig that uses a scanning, focused, CO(2) laser beam as the heat source. As a result of the pointlike heat source and the versatility associated with scanning, tapers of any transition shape and uniform taper waist can be produced. Tapers with both a linear shape and an exponential transition shape were measured. The taper waist uniformity was measured and shown to be better than +/-1.2%. The rig was also used to make fused-fiber couplers. Couplers with excess loss below -0.1 dB were routinely produced.

  16. Optimization of the soliton self-frequency shift in a tapered photonic crystal fiber

    DEFF Research Database (Denmark)

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

    2009-01-01

    Soliton propagation is modeled in a tapered photonic crystal fiber for various taper profiles with the purpose of optimizing the soliton self-frequency shift (SSFS) in such geometries. An optimal degree of tapering is found to exist for tapers with an axially uniform waist. In the case of axially...... nonuniform waists, an additional enhancement of the SSFS is achieved by varying the taper waist diameter along its length in a carefully designed fashion in order to present an optimal level of group-velocity dispersion to the soliton at each point, thus avoiding the spectral recoil due to the emission...

  17. Theoretical model of the modulation transfer function for fiber optic taper

    Science.gov (United States)

    Wang, Yaoxiang; Tian, Weijian; Bin, XiangLi

    2005-02-01

    Fiber optic taper has been used more and more widely as a relay optical component in the integrated taper assembly image intensified sensors for military and medical imaging application. In this paper, the transmission characteristic of energy in the taper is analyzed, and following the generalized definition of the modulation transfer function for sampled imaging system, a spatial averaged impulse response and a corresponding MTF component that are inherent in the sampling process of taper are deduced, and the mathematical model for evaluating the modulation transfer function of fiber optic taper is built. Finally, the dynamic and static modulation transfer function curves simulated by computer have been exhibited.

  18. 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.

  19. 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.

  20. An in vitro analysis of separation of multi-use ProTaper Universal and ProTaper Next instruments in extracted mandibular molar teeth.

    Science.gov (United States)

    Ertas, Huseyin; Capar, Ismail Davut

    2015-01-01

    This study investigated the separation incidence of reused ProTaper Universal and ProTaper Next rotary instruments and identified the location of separated fragments. The root canals of extracted human mandibular molars were prepared with 10 assorted sets of ProTaper Universal and ProTaper Next instruments. After each preparation, instrument sets were autoclaved. This arrangement was repeated until an instrument fractured. The number of prepared teeth until fracture occurred was recorded for each instrument set. Teeth in which the instruments fractured were analyzed to determine the separation grade, apical relation, and coronal position. Fracture surfaces of the instruments were examined with scanning electron microscope. ProTaper Universal instruments fractured after application to a mean of 7.3 teeth, and ProTaper Next instruments after application to a mean of 5.7 teeth (p > 0.05). In the ProTaper Universal and ProTaper Next groups, F2 and X1 were the most commonly fractured instruments, respectively. Torsional and cyclic failures were evenly distributed in both the groups. The mean lengths of the fractured fragments of the instruments showed no statistically significant difference. The distance between the tip of the fractured instruments and apical constriction was similar (p > 0.05). However, the mean distance between the root canal orifice and coronal part of the fractured instrument was shorter in the ProTaper Next group (p ProTaper Universal and ProTaper Next instruments was the same for preparation of mandibular molar teeth. None of the instruments were fractured in the first usage.

  1. 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.

  2. Optimized tapered dipole nanoantenna as efficient energy harvester.

    Science.gov (United States)

    El-Toukhy, Youssef M; Hussein, Mohamed; Hameed, Mohamed Farhat O; Heikal, A M; Abd-Elrazzak, M M; Obayya, S S A

    2016-07-11

    In this paper, a novel design of tapered dipole nanoantenna is introduced and numerically analyzed for energy harvesting applications. The proposed design consists of three steps tapered dipole nanoantenna with rectangular shape. Full systematic analysis is carried out where the antenna impedance, return loss, harvesting efficiency and field confinement are calculated using 3D finite element frequency domain method (3D-FEFD). The structure geometrical parameters are optimized using particle swarm algorithm (PSO) to improve the harvesting efficiency and reduce the return loss at wavelength of 500 nm. A harvesting efficiency of 55.3% is achieved which is higher than that of conventional dipole counterpart by 29%. This enhancement is attributed to the high field confinement in the dipole gap as a result of multiple tips created in the nanoantenna design. Furthermore, the antenna input impedance is tuned to match a wide range of fabricated diode based upon the multi-resonance characteristic of the proposed structure.

  3. Complex coupled-mode theory for tapered optical waveguides.

    Science.gov (United States)

    Mu, Jianwei; Huang, Wei-Ping

    2011-03-15

    A coupled-mode formulation based on complex local modes is developed for tapered and longitudinally varying optical waveguides. Different from the conventional coupled-mode theory that requires integration over the entire spectrum of radiation modes, the new formulation treats the radiation fields via discrete complex modes similarly to the guided modes. Accuracy, convergence, and scope of validity for the solutions of the complex coupled-mode equations are investigated in detail for a typical single-mode waveguide taper. It is demonstrated that the complex coupled-mode theory has overcome the difficulties of the conventional theory in simulation of radiation field effects while preserving the simplicity and intuitiveness of this popular method.

  4. The structural damping of composite beams with tapered boundaries

    Science.gov (United States)

    Coni, M.; Benchekchou, B.; White, R. G.

    1994-11-01

    Most metallic and composite structures of conventional construction are lightly damped. It is obviously advantageous, in terms of response to in-service dynamic loading, if damping can be increased with minimal weight addition. This report describes finite element analyses and complementary experiments carried out on composite, carbon fiber reinforced plastic, beams with tapered boundaries composed of layers of highly damped composite material. It is shown that modal damping of the structure may be significantly increased by this method.

  5. Tapered Diode-pumped continuous-wave alexandrite laser

    OpenAIRE

    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,...

  6. Design optimization of a tapered mirror for microfocusing optics

    Institute of Scientific and Technical Information of China (English)

    MAO Cheng-Wen; XI Zai-Jun; YU Xiao-Han; XIAO Ti-Qiao

    2009-01-01

    A facile microfocusing optical design is presented which is optimized for less slope error against the traditional tapered mirror. The essential idea of the innovation is based on the characteristics of the slope-error curve for the prototype. The relationship between the mirror shape of the improved model and the driving moments is established. Analytical results have been compared with the results of the prototype. The design demonstrates theoretically that smaller slope error is obtained with longer active length.

  7. 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.

  8. Large deflection of flexible tapered functionally graded beam

    Institute of Scientific and Technical Information of China (English)

    A.R.Davoodinik; G.H.Rahimi

    2011-01-01

    In this paper the semi-analytical analyses of the flexible cantilever tapered functionally graded beam under combined inclined end loading and intermediate loading are studied.In order to derive the fully non-linear equations governing the non-linear deformation,a curvilinear coordinate system is introduced.A general non-linear second order differential equation that governs the shape of a deflected beam is derived based on the geometric nonlinearities,infinitesimal local displacements and local rotation concepts with remarkable physical properties of functionally graded materials.The solutions obtained from semi-analytical methods are numerically compared with the existing elliptic integral solution for the case of a flexible uniform cantilever functionally graded beam.The effects of taper ratio,inclined end load angle and material property gradient on large deflection of the beam are evaluated.The Adomian decomposition method will be useful toward the design of tapered functionally graded compliant mechanisms driven by smart actuators.

  9. Stratification criteria to fit taper functions on pine boles

    Directory of Open Access Journals (Sweden)

    Hassan Camil David

    2014-09-01

    Full Text Available This paper aimed to evaluate the accuracy of taper functions fitted with and without stratification on Pinus sp. trees. Three strata were allocated using diameter at 1.3 m above the ground, artificial form factor and Schiffel’s form quotient as stratification criteria. Schöepfer, Kozak et al. Hradetzky, Garcia et al., Ormerod and Demaerchalk taper functions were tested and the one which best fitted to the total population was selected by statistics standard error of estimate in percentage (syx%, adjusted coefficient of determination (R²aj. and residual scatterplots. After this, the selected function was fitted with data stratified and the gain of accuracy was evaluated by two statistical methods. As results, Hradetzky’s function adjusted better when compared to the others. Equations obtained for the total population and for strata are statistically different. Stratification by form factor and by form quotient provide considerable reduction of errors, reaching up to 50%, however it was not observed expressive reduction for stratification by diameter at 1.3 above the ground. So, the stratification by form factor is recommended for fitting taper functions to boles of Pinus sp.

  10. 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.

  11. Single-mode fiber linearly tapered planar waveguide tunable coupler

    Science.gov (United States)

    Das, Alok K.; Hussain, Anwar

    1997-09-01

    We developed a simple system of tunable fiber film coupler using a linearly tapered thin-film planar waveguide (PWG) evanescently coupled by a single-mode distributed fiber half-coupler. We investigate the characteristics of the coupler theoretically and experimentally taking into consideration the refractive index ( n f ) of nonuniform films, the magnitude of nonuniformity ( m ) of the films, and the source wavelength ( ). The thickness variation of the nonuniform film is along the direction of propagation of optical power. Tapered and plano concave thin films of a mix of oils as well as a plano concave poly(methyl methacrylate) film were fabricated to serve as nonuniform PWG s. Similar to single-mode fiber with a uniform thickness PWG coupler, such a coupler also provides light modulation with a change of n f . However, position shifting of a half-coupler in a tapered PWG structure along the direction of propagation exhibits the variation of fiber throughput power. This action serves as a simple system for a tunable fiber film coupler. Wavelength-dependent throughput fiber power for such a coupler also behaves as a filter. The center wavelength can be controlled by shifting the position of the half-coupler. A coupling fiber as a half-coupler can be used for efficient coupling. We performed a theoretical analysis of the structure using Marcuse s model and observed good agreement with the experimental results.

  12. 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.

  13. Ion-exchanged tapered-waveguide laser in neodymium-doped BK7 glass.

    Science.gov (United States)

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

    2000-10-01

    We report what is to our knowledge the first operation of a planar dielectric tapered-waveguide laser. The waveguide laser is fabricated by potassium-ion exchange in Nd(3+) -doped BK7 glass and consists of a single-mode channel waveguide of a few micrometers' width followed by a linear taper up to a broad region with a width of ~180microm . A slope efficiency of 42% is found both in the tapers and in standard channel waveguides fabricated upon the same substrate, indicating that the tapers and the channels have similar internal losses; hence the low-loss nature of the tapered beam expansion. The output from either end of the tapered structure is found to be nearly diffraction limited.

  14. Computationally generated velocity taper for efficiency enhancement in a coupled-cavity traveling-wave tube

    Science.gov (United States)

    Wilson, Jeffrey D.

    1989-01-01

    A computational routine has been created to generate velocity tapers for efficiency enhancement in coupled-cavity TWTs. Programmed into the NASA multidimensional large-signal coupled-cavity TWT computer code, the routine generates the gradually decreasing cavity periods required to maintain a prescribed relationship between the circuit phase velocity and the electron-bunch velocity. Computational results for several computer-generated tapers are compared to those for an existing coupled-cavity TWT with a three-step taper. Guidelines are developed for prescribing the bunch-phase profile to produce a taper for efficiency. The resulting taper provides a calculated RF efficiency 45 percent higher than the step taper at center frequency and at least 37 percent higher over the bandwidth.

  15. Calculation of Taper Rolling Time in Plan View Pattern Control Process

    Institute of Scientific and Technical Information of China (English)

    JIAO Zhi-jie; HU Xian-lei; ZHAO Zhong; LIU Xiang-hua; WANG Guo-dong

    2006-01-01

    The forward slip model with adhesion was used to derive the formula of calculating taper rolling time. The relation between the rolling time and the taper length and the relation between the rolling time and the taper thickness can be obtained. The numerical solution for this formula was used on-site. According to the simulation result, the roll gap value should be changed linearly with rolling time.

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

    DEFF Research Database (Denmark)

    Pu, Minhao; Liu, Liu; Ou, Haiyan;

    2010-01-01

    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 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...

  17. Characterization of arbitrary fiber taper profiles with optical microscopy and image processing algorithms

    Science.gov (United States)

    Farias, Heric D.; Sebem, Renan; Paterno, Aleksander S.

    2014-08-01

    This work reports results from the development of a software to process the parameters involved in the characterization of fiber taper profiles, while using optical microscopy, a high-definition camera and a high- precision translation stage as the moveable base on which the taper is positioned. In addition to this procedure, image processing algorithms were customized to process the acquired images. With edge detection algorithms in the stitched image, one would be able to characterize the given taper radius curve that represents the taper profile when the camera has a sufficient resolution. As a consequence, the proposed fiber taper characterization procedure is a first step towards a high-resolution characterization of fiber taper diameters with arbitrary profiles, specially this case, in which tapers are fabricated with the stepwise technique that allows the production of non- biconical profiles. The parameters of the stitched images depends on the used microscope objective and the length of the characterized tapers. A non-biconical arbitrary taper is measured as an example for the illustration of the developed software and procedure.

  18. Compound-taper feedhorn for the DSN 70-meter antennas

    Science.gov (United States)

    Manshadi, F.; Hartop, R.

    1987-08-01

    A novel X-band feedhorn was designed for the Deep Space Network (DSN) 70-meter antennas. The feedhorn is a compound-taper structure consisting of a corrugated flared section and a corrugated straight section. This feedhorn is designed to closely initiate the characteristics of the standard feedhorn, while providing the proper phase center location, without adding any significant loss to the system. The use of the existing feedhorn and the ease of manufacturing the corrugated straight section have resulted in major overall cost savings.

  19. Compound-taper feed horn for NASA 70-m antennas

    Science.gov (United States)

    Manshadi, Farzin; Hartop, Rob

    1988-09-01

    A novel X-band feedhorn was designed for the Deep Space Network (DSN) 70-meter antennas. The feedhorn is a compound-taper structure consisting of a corrugated flared section and a corrugated straight section. This feedhorn is designed to closely imitate the characteristics of the standard feedhorn, while providing the proper phase center location, without adding any significant loss to the system. The use of the existing feedhorn and the ease of manufacturing the corrugated straight section have resulted in major overall cost savings.

  20. 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.

  1. Frequency characteristics of tapered backfire helical antenna with loaded termination

    Science.gov (United States)

    Nakano, H.; Iio, S.; Yamauchi, J.

    1984-06-01

    Effects of loaded termination on a tapered backfire bifilar helical antenna are numerically and experimentally investigated over a wide frequency range of ratio 1:1.7. With the help of the scalar potential for a lumped resistance at the arm end, the current distribution along the helical wire is determined. It is found that nearly constant input impedance, high front-to-back ratio and low axial ratio are realised. The inherent absolute gain is not significantly deteriorated in spite of the use of a terminal resistor. The existence of the phase centre is also demonstrated, and the phase centre location is presented as a function of frequency.

  2. X-Ray Propagation in Tapered Planar Waveguide

    Science.gov (United States)

    Dolocan, Andrei; van der Veen, J. Friso

    The present paper focuses on the tapered planar waveguide solution for an initial given wave form. The algorithm is constructed in distributions space such that the calculations can be actually computed by taking some hypothesis regarding the mode series which appear. The whole argument leads to the conclusion that the wave is compressed towards the waveguide in the direction of tilting, leading thereafter to a focusing phenomena. We present two alternative constructions in order to compute the convolution which gives the wave inside the waveguide. The hypothesis are providing results in good approximation with the real evolution of the field within the definition domain.

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

    OpenAIRE

    Mary Kinue Nakamune Uezu; Maria Leticia Borges Britto; Cleber K. Nabeshima; Raul Capp Pallotta

    2010-01-01

    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...

  4. 机用镍钛器械ProTaper Next和ProTaper Universal在模拟根管内成形的能力%Shaping ability of ProTaper Next and ProTaper Universal Ni-Ti rotary endodontic instruments in simulated root canals

    Institute of Scientific and Technical Information of China (English)

    刘文哲; 陈广盛

    2014-01-01

    背景:目前机用镍钛锉尚无国际统一标准,应用于临床的几种镍钛系统在横截面形态、锥度变化、组成数量、中心钢量及切割刃角度等方面均有独特设计,使其清理成形能力、安全性能、切割效率等方面存在差异。ProTaper Next是在ProTaper Universal基础上的改良及创新,其在组成数量、刃部横截面形态、与根管壁接触点及尖端锥度等方面均进行了改进。  目的:利用树脂模拟根管比较机用镍钛器械ProTaper Next和ProTaper Universal在弯曲根管内的成形能力。方法:使用机用镍钛器械ProTaper Next和ProTaper Universal采用冠向下法预备两组模拟树脂根管,预备过程中记录预备时间和器械变形及分离的发生,预备结束后使用Adobe Photoshop v7.0软件测量根管内外侧壁树脂去除量,并计算器械中心定位力。  结果与结论:两组器械形变方面差异无显著性意义;ProTaper Next预备时间较ProTaper Universal明显缩短(P composition number, central steel volume, and cutting edge angle, so there are some differences in cleanup capability, security, and cutting efficiency. ProTaper Next is developed based on the ProTaper Universal, and its composition number, blade cross-sectional shape, contact point with the root canal wal and the tip tapers are al improved. OBJECTIVE:To compare the shaping ability between ProTaper Next and ProTaper Universal Ni-Ti rotary endodontic instruments by preparing the simulated root canals. METHODS: Two groups of resin blocks were prepared by ProTaper Next and ProTaper Universal respectively. Preparation time and incidence of canal aberration and instruments failure were recorded. After preparation, the images taken before and after preparation were superimposed and analyzed by software Adobe Photoshop v7.0. We measured the amount of resin removed at the inner and outer canal wals. The centering ability was also assessed. RESULTS AND

  5. 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.

  6. 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.

  7. Flow and acoustic features of a supersonic tapered nozzle

    Science.gov (United States)

    Gutmark, E.; Bowman, H. L.; Schadow, K. C.

    1992-05-01

    The acoustic and flow characteristics of a supersonic tapered jet were measured for free and shrouded flow configurations. Measurements were performed for a full range of pressure ratios including over- and underexpanded and design conditions. The supersonic tapered jet is issued from a converging-diverging nozzle with a 3∶1 rectangular slotted throat and a conical diverging section leading to a circular exit. The jet was compared to circular and rectangular supersonic jets operating at identical conditions. The distinct feature of the jet is the absence of screech tones in the entire range of operation. Its near-field pressure fluctuations have a wide band spectrum in the entire range of measurements, for Mach numbers of 1 to 2.5, for over- and underexpanded conditions. The free jet's spreading rate is nearly constant and similar to the rectangular jet, and in a shroud, the pressure drop it is inducing is linearly proportional to the primary jet Mach number. This behavior persisted in high adverse pressure gradients at overexpanded conditions, and with nozzle divergence angles of up to 35°, no inside flow separation was observed.

  8. 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.

  9. 机用镍钛器械ProTaper Next和ProTaper Universal在模拟根管内成形的能力

    Institute of Scientific and Technical Information of China (English)

    刘文哲; 陈广盛

    2014-01-01

    背景:目前机用镍钛锉尚无国际统一标准,应用于临床的几种镍钛系统在横截面形态、锥度变化、组成数量、中心钢量及切割刃角度等方面均有独特设计,使其清理成形能力、安全性能、切割效率等方面存在差异。ProTaper Next是在ProTaper Universal基础上的改良及创新,其在组成数量、刃部横截面形态、与根管壁接触点及尖端锥度等方面均进行了改进。目的:利用树脂模拟根管比较机用镍钛器械ProTaper Next和ProTaper Universal在弯曲根管内的成形能力。方法:使用机用镍钛器械ProTaper Next和ProTaper Universal采用冠向下法预备两组模拟树脂根管,预备过程中记录预备时间和器械变形及分离的发生,预备结束后使用Adobe Photoshop v7.0软件测量根管内外侧壁树脂去除量,并计算器械中心定位力。结果与结论:两组器械形变方面差异无显著性意义;ProTaper Next预备时间较ProTaper Universal明显缩短(P 〈0.05)。两组根管预备后中下段均有部分偏移。ProTaper Next X2在根管弯曲内侧在大多数测量点切割的树脂量少于ProTaper Universal F2(P 〈0.05)。ProTaper Next在大多数测量点的中心定位能力好于ProTaper Universal(P 〈0.05)。结果证实,两组镍钛器械ProTaper Next和ProTaper Universal均能较好地完成根管预备;在预备根管中下段时,都会造成一定程度上的偏移,但ProTaper Next的中心定位力总体上较ProTaper Universal好。

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

    DEFF Research Database (Denmark)

    Hassan, Hafeez Ul; Fasano, Andrea; Nielsen, Kristian;

    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...

  11. Spectral beam combining of a 980 nm tapered diode laser bar

    DEFF Research Database (Denmark)

    Vijayakumar, Deepak; Jensen, Ole Bjarlin; Ostendorf, Ralf;

    2010-01-01

    We demonstrate spectral beam combining of a 980 nm tapered diode laser bar. The combined beam from 12 tapered emitters on the bar yielded an output power of 9.3 W at 30 A of operating current. An M2 value of 5.3 has been achieved along the slow axis. This value is close to that of a free running...

  12. Low insertion loss SOI microring resonator integrated with nano-taper couplers

    DEFF Research Database (Denmark)

    Pu, Minhao; Frandsen, Lars Hagedorn; Ou, Haiyan;

    2009-01-01

    We demonstrate a microring resonator working at TM mode integrated with nano-taper couplers with 3.6dB total insertion loss. The measured insertion loss of the nano-taper coupler was only 1.3dB for TM mode....

  13. Ultra-low loss nano-taper coupler for Silicon-on-Insulator ridge waveguide

    DEFF Research Database (Denmark)

    Pu, Minhao; Liu, Liu; Ou, Haiyan;

    2010-01-01

    A nano-taper coupler is optimized specially for the transverse-magnetic mode for interfacing light between a silicon-on-insulator ridge waveguide and a single-mode fiber. An ultra-low coupling loss of ~0.36dB is achieved for the nano-taper coupler....

  14. Tapering off benzodiazepines in long-term users : an economic evaluation

    NARCIS (Netherlands)

    Oude Voshaar, Richard C; Krabbe, Paul F M; Gorgels, Wim J M J; Adang, Eddy M M; van Balkom, Anton J L M; van de Lisdonk, Eloy H; Zitman, Frans G

    2006-01-01

    BACKGROUND: Discontinuation of benzodiazepine usage has never been evaluated in economic terms. This study aimed to compare the relative costs and outcomes of tapering off long-term benzodiazepine use combined with group cognitive behavioural therapy (TO+CBT), tapering off alone (TOA) and usual care

  15. Tapering off benzodiazepines in long-term users: an economic evaluation.

    NARCIS (Netherlands)

    Oude Voshaar, R.C.; Krabbe, P.F.M.; Gorgels, W.J.M.J.; Adang, E.M.M.; Balkom, A.J.L.M. van; Lisdonk, E.H. van de; Zitman, F.G.

    2006-01-01

    BACKGROUND: Discontinuation of benzodiazepine usage has never been evaluated in economic terms. This study aimed to compare the relative costs and outcomes of tapering off long-term benzodiazepine use combined with group cognitive behavioural therapy (TO+CBT), tapering off alone (TOA) and usual care

  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. A Report of Successful Procedural, Clinical, and Angiographic Outcomes with a Tapered Stent of a Patient in Naturally Tapered Coronary Vessel

    Science.gov (United States)

    Kumar, Yerra Shiv

    2017-01-01

    In cases involving stenosis or occlusions in major parts of a long vessel, natural tapering of coronary vessels may create dilemma in deciding the optimal stent size during percutaneous coronary intervention. In this regard, tapered stents have been developed recently. Herein, we present a case of 67-year-old male patient with triple vessel disease including two tandem lesions in naturally tapered Left Anterior Descending (LAD) artery. The patient received a 3.0–2.5x60 mm Sirolimus-eluting BioMime Morph stent (Meril life Sciences, Gujarat, India) in the mid-distal LAD lesion along with conventional stent implantations in other two lesions. The procedure was successful and good coronary flow was obtained after revascularization. The patient remained asymptomatic thereafter. At one year, angiographic follow-up revealed good flow and no restenosis in the LAD vessel. We are of opinion that using tapered stents with decremented diameter may offer the advantages of excellent adaptation to vessel size, vessel tapering, and good apposition in patients with long coronary lesions in tapered vessels.

  18. Hormonal responses to training and its tapering off in competitive swimmers: relationships with performance.

    Science.gov (United States)

    Mujika, I; Chatard, J C; Padilla, S; Guezennec, C Y; Geyssant, A

    1996-01-01

    During a winter training season, the effects of 12 weeks of intense training and 4 weeks of tapering off (taper) on plasma hormone concentrations and competition performance were investigated in a group of highly trained swimmers (n = 8). Blood samples were collected and the swimmers performed their speciality in competition at weeks 10 (mid-season), 22 (pre-taper) and 26 (post-taper). No statistically significant changes were observed in the concentrations of total testosterone (TT), non-sex hormone binding globulin-bound-testosterone (NSBT), cortisol (C), luteinising hormone, thyroid stimulating hormone, triiodothyronine, thyroxine plasma catecholamines, creatine kinase and ammonia during training and taper. Mid-season NSBT: C ratio and the amount of training were statistically related (r = 0.82, P swimmers' performance capacities throughout the training season.

  19. Asymmetric Draw-Tower Tapers for Supercontinuum Generation and Verification of the Novel Concept of Group-Acceleration Matching

    DEFF Research Database (Denmark)

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

    2012-01-01

    We present the first short asymmetrical draw-tower photonic crystal fiber taper for maximizing the power in the blue edge of a supercontinuum. The results clearly emphasize the importance of the taper shape on the spectrum.......We present the first short asymmetrical draw-tower photonic crystal fiber taper for maximizing the power in the blue edge of a supercontinuum. The results clearly emphasize the importance of the taper shape on the spectrum....

  20. Group-Acceleration Matching in Tapered Optical Fibers for Maximising the Power in the Blue-Edge of a Supercontinuum

    DEFF Research Database (Denmark)

    Sørensen, Simon Toft; Judge, Alex; Thomsen, Carsten L.;

    2011-01-01

    We show that the gradient of a tapered fiber has a major impact on the power actually available in the blueedge of a supercontinuum. We ascribe this to a groupacceleration mismatch induced by the taper.......We show that the gradient of a tapered fiber has a major impact on the power actually available in the blueedge of a supercontinuum. We ascribe this to a groupacceleration mismatch induced by the taper....

  1. 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 4.0 mm 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 3.5 mm, the mean fracture forces for 8° and 10° taper groups were 1638.9 N ± 20.3 and 1577.1 N ± 103.2, respectively, both larger than that for the 6° taper group of 1475.0 N ± 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.

  2. High Efficiency Electron-Laser Interactions in Tapered Helical Undulators

    Science.gov (United States)

    Duris, Joseph Patrick

    Efficient coupling of relativistic electron beams with high power radiation lies at the heart of advanced accelerator and light source research and development. The inverse free electron laser is a stable accelerator capable of harnessing very high intensity laser electric fields to efficiently transfer large powers from lasers to electron beams. In this dissertation, we first present the theoretical framework to describe the interaction, and then apply our improved understanding of the IFEL to the design and numerical study of meter-long, GeV IFELs for compact light sources. The central experimental work of the dissertation is the UCLA BNL helical inverse free electron laser experiment at the Accelerator Test Facility in Brookhaven National Laboratory which used a strongly tapered 54cm long, helical, permanent magnet undulator and a several hundred GW CO2 laser to accelerate electrons from 52 to 106MeV, setting new records for inverse free electron laser energy gain (54MeV) and average accelerating gradient (100MeV/m). The undulator design and fabrication as well as experimental diagnostics are presented. In order to improve the stability and quality of the accelerated electron beam, we redesigned the undulator for a slightly reduced output energy by modifying the magnet gap throughout the undulator, and we used this modified undulator to demonstrated capture of >25% of the injected beam without prebunching. In the study of heavily loaded GeV inverse free electron lasers, we show that a majority of the power may be transferred from a laser to the accelerated electron beam. Reversing the process to decelerate high power electron beams, a mechanism we refer to as tapering enhanced stimulated superradiant amplification, offers a clear path to high power light sources. We present studies of radiation production for a wide range of wavelengths (10mum, 13nm, and 0.3nm) using this method and discuss the design for a deceleration experiment using the same undulator used

  3. Tapered Six-Dimensional Cooling Channel for a Muon Collider

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, R.B.; Fernow, R.C.

    2011-03-28

    A high-luminosity muon collider requires a reduction of the six-dimensional emittance of the captured muon beam by a factor of {approx} 10{sup 6}. Most of this cooling takes place in a dispersive channel that simultaneously reduces all six phase space dimensions. We describe a tapered 6D cooling channel that should meet the requirements of a muon collider. The parameters of the channel are given and preliminary simulations are shown of the expected performance. A complete scheme for cooling a muon beam sufficiently for use in a muon collider has been previously described. This scheme uses separate 6D ionization cooling channels for the two signs of the particle charge. In each, a channel first reduces the emittance of a train of muon bunches until they can be injected into a bunch-merging system. The single muon bunches, one of each sign, are then sent through a second tapered 6D cooling channel where the transverse emittance is reduced as much as possible and the longitudinal emittance is cooled to a value below that needed for the collider. The beam can then be recombined and sent through a final cooling channel using high-field solenoids that cools the transverse emittance to the required values for the collider while allowing the longitudinal emittance to grow. This paper mainly describes the design of the 6D cooling channel before bunch merging. Cooling efficiency is conveniently measured using a parameter Q, which is defined as the rate of change of 6D emittance divided by the rate of change of the number of muons in the beam. In a given lattice Q starts off small due to losses from initial matching, then rises to a large value (Q {approx} 15 is typical for the channels discussed here), and finally falls as the emittance of the beam approaches its equilibrium value. The idea for the 6D cooling channel described here originated with the RFOFO cooling ring. This design evolved into a helical channel referred to as a 'Guggenheim' in order to avoid

  4. Cold neutron microprobe for materials analysis using tapered capillary optics

    Science.gov (United States)

    Sharov, V. A.; Xiao, Q.-F.; Ponomarev, I. Yu.; Mildner, D. F. R.; Chen-Mayer, H. H.

    2000-09-01

    A prototype monolithic capillary lens for focusing neutrons produced by thermally drawing straight multicapillary bundles has been characterized with cold neutrons, and gives an intensity gain of a factor of 25 at a focal distance of 8 mm, over the focal spot area of width 87 μm. This is over an order of magnitude smaller in area than for the multifiber capillary lens. The spatial resolution available with the lens has been tested with prompt gamma measurements on slivers of dysprosium. Background problems that can affect the spatial resolution of measurements taken at the focal position of the lens are addressed. The boron glass of the tapered monolithic lens provides good shielding from unfocused neutrons in the vicinity of the lens focus.

  5. Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection

    Directory of Open Access Journals (Sweden)

    Dong Luo

    2016-12-01

    Full Text Available In this study, tapered polymer fiber sensors (TPFSs have been employed to detect the vibration of a reinforced concrete beam (RC beam. The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM system in civil engineering.

  6. Subwavelength focusing of light by a tapered microtube

    CERN Document Server

    Fu, Jian; Fang, Wei

    2010-01-01

    We propose a mechanism for subwavelength focusing at optical frequencies based on the use of a tapered microtube fabricated from a glass capillary tube. Using coherent illumination at 671nm and a near-field scanning optical microscope probe which was mounted on a 3-axis piezo nanopositioning stage, a sequence of 2-D intensity profiles were obtained. Our experimental results reveal the smallest focal spot with a near diffraction-limited full width at half-maximum of ~435nm(0.65{\\lambda})at a distance of ~1.47{\\mu}m (2.2{\\lambda}) from the output endface of microtube. The experimental results are in excellent agreement with our numerical simulation.

  7. Growth strategies to control tapering in Ge nanowires

    Directory of Open Access Journals (Sweden)

    P. Periwal

    2014-04-01

    Full Text Available We report the effect of PH3 on the morphology of Au catalyzed Ge nanowires (NWs. Ge NWs were grown on Si (111 substrate at 400 °C in the presence of PH3, using vapor-liquid-solid method by chemical vapor deposition. We show that high PH3/GeH4 ratio causes passivation at NW surface. At high PH3 concentration phosphorous atoms attach itself on NW surface and form a self-protection coating that prevents conformal growth and leads to taper free nanostructures. However, in case of low PH3 flux the combination of axial and radial growth mechanism occurs resulting in conical structure. We have also investigated axial PH3-intrinsic junctions in Ge NWs. The unusual NW shape is attributed to a combination of catalyzed, uncatalyzed and diffusion induced growth.

  8. Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection.

    Science.gov (United States)

    Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

    2016-12-16

    In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering.

  9. Analysis of the Tem Mode Linearly Tapered Slot Antenna

    Science.gov (United States)

    Janaswamy, R.; Schaubert, D. H.; Pozar, D. M.

    1985-01-01

    The theoretical analysis of the radiation characteristics of the TEM mode Linearly Tapered Slot Antenna (LTSA) is presented. The theory presented is valid for antennas with air dielectric and forms the basis for analysis of the more popular dielectric-supported antennas. The method of analysis involves two steps. In the first step, the aperture distribution in the flared slot is determined. In the second step, the equivalent magnetic current in the slot is treated as radiating in the presence of a conducting half-plane and the far-field components are obtained. Detailed comparison with experiment is made and excellent agreement is obtained. Design curves for the variation of the 3 dB and 10 dB beamwidths as a function of the antenna length, with the flare angle as a parameter, are presented.

  10. Analysis of the transverse electromagnetic mode linearly tapered slot antenna

    Science.gov (United States)

    Janaswamy, R.; Schaubert, D. H.; Pozar, D. M.

    1986-01-01

    A theoretical analysis of the radiation characteristics of the transverse electromagnetic mode linearly tapered slot antenna is presented. The theory presented is valid for antennas with air dielectric and forms the basis for analysis of the more popular dielectric-supported antennas. The method of analysis involves two steps. In the first step, the aperture distribution in the flared slot is determined. In the second step, the equivalent magnetic current in the slot is treated as radiating in the presence of a conducting half-plane, and the far-field components are obtained. Design curves for the variation of the 3-dB and 10-dB beamwidths as a function of the antenna length, with the flare angle as a parameter, are presented.

  11. Thin-ribbon tapered coupler for dielectric waveguides

    Science.gov (United States)

    Yeh, C.; Otoshi, T. Y.; Shimabukuro, F. I.

    1994-05-01

    A recent discovery shows that a high-dielectric constant, low-loss, solid material can be made into a ribbon-like waveguide structure to yield an attenuation constant of less than 0.02 dB/m for single-mode guidance of millimeter/submillimeter waves. One of the crucial components that must be invented in order to guarantee the low-loss utilization of this dielectric-waveguide guiding system is the excitation coupler. The traditional tapered-to-a-point coupler for a dielectric rod waveguide fails when the dielectric constant of the dielectric waveguide is large. This article presents a new way to design a low-loss coupler for a high- or low-dielectric constant dielectric waveguide for millimeter or submillimeter waves.

  12. Salivary hormones, IgA, and performance during intense training and tapering in judo athletes.

    Science.gov (United States)

    Papacosta, Elena; Gleeson, Michael; Nassis, George P

    2013-09-01

    The aims of this study were to identify the time course of change of salivary testosterone (sT), cortisol (sC), and IgA (SIgA); mood state; and performance capacity during a 2-week taper in judo athletes and to examine the diurnal variation in these salivary markers. Eleven male judo athletes completed 5 weeks of training: 1 week of normal training (NORM), 2 weeks of intensified training (INT), and 2 weeks of exponential tapering (TAPER). Once per week subjects completed vertical and horizontal countermovement jump tests, a grip strength test, a Special Judo Fitness Test, a multistage aerobic fitness test, a 3 × 300-m run test, and anthropometric measurement. Subjects also completed questionnaires to assess mood state and muscle soreness. Two daily saliva samples (at 0700 and 1900) were collected at the end of each week during NORM and INT and every day during TAPER. Increased morning sT, decreased evening sC, lower muscle soreness, and enhanced mood state (p TAPER. A significant 7.0% improvement in 3 × 300-m performance time, a 6.9% improvement in the vertical jump (p TAPER. The higher values of salivary variables were observed in the morning. This study indicates that salivary hormones display diurnal variation. Furthermore, changes in hormonal responses, mood state, and muscle soreness precede enhancements in performance and mucosal immunity, suggesting that judo athletes taper for at least a week before competition.

  13. Simple method for manufacturing and optical characterization of tapered optical fibres

    Science.gov (United States)

    Zakrzewski, A.; Pięta, A.; Patela, S.

    2016-12-01

    Photonic devices often use light delivered by a single-mode telecommunication fibre. However, as the diameter of the core of the optical fibre is of 10 microns, and the transverse dimensions of the photonic waveguides are usually micrometer or less, there is an issue of incompatibility. The problem may be solved by application of tapered optical fibres. For efficient light coupling, the taper should be prepared so as to create a beam of long focal length and small spot diameter in the focus. The article describes the design, fabrication and characterization of tapered optical fibres prepared with a fibre-optic fusion splicer. We modelled the tapers with FDTD method, for estimation of the influence of the tapered length and angle on the spot diameter and the focal length of an outgoing beam. We fabricated tapers from a standard single mode fibre by the Ericsson 995 PMfi- bre-optic fusion splicer. We planned the splicing technology so as to get the needed features of the beam. We planned a multistep fusion process, with optimized fusion current and fusion time. The experimental measurements of best tapered optical fibres were carried out by the knife-edge method.

  14. Reduction Rate of Dragload and Downdrag of Piles by Taper Angles

    Institute of Scientific and Technical Information of China (English)

    孔纲强; 周立朵; 彭怀风; 顾红伟

    2016-01-01

    Taper angle is one of the effective methods to reduce the dragload and downdrag of piles under the surcharge load. The model tests on the tapered pile and uniform cross-section pile embedded in sand were carried out under the surcharge load. The values of dragload and downdrag of piles versus the surcharge loads were meas-ured. Based on the concentric cylinder shearing theory, a simplified theoretical model for calculating the dragload and downdrag of tapered piles with small taper angles under the surcharge load was proposed considering the angle effect. The correctness of the developed theoretical model was validated through comparing with the model test results obtained in this study and previous literature. Then the parametric studies of the taper angle, surcharge, strength and modulus of soil were discussed. It is shown that the tapered pile with the taper angle of 3° can reduce approximately 65% of the maximum dragload value and 30% of the downdrag value compared with a uniform cross-section pile. The value of downdrag can be decreased by approximately 50% compared with a uniform cross-section pile in the same average pile diameter.

  15. Tapered joint design for power transmission of MW-grade wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Jong Hun; Bae, Jun Woo; Oh, Han Yong [Dept. of Mechatronics, Jungwon University, Geosan (Korea, Republic of); Kwon, Yong Chul [Kyeongnam Technopark, Changwon (Korea, Republic of)

    2015-11-15

    This study focuses on the design of the tapered joints of a wind power turbine. The main variables of the tapered joint are the transmitted torque, shaft diameter, contact area of the tapered ring, and tightening torque of the bolts, which applies a compressive pressure from the hub to the shaft. The stress distribution of the taper fit was calculated under axisymmetric plane strain conditions because of the small taper angle. The axial displacement of the clamp can be calculated from the radial elastic deformation and the taper angle. The stress field of each ring is obtained from the cylinder stress equation. To verify the accuracy of the calculation, finite element (FE) analysis was performed, and the results of the calculation and FE analysis were compared. The hoop stress of the tapered surface showed a discrepancy of approximately 10, but the trends of the stress distributions of each component and the relative movement obtained by FE analysis were in good agreement with the analytical calculation results.

  16. 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

    laser emits in excess of 9 W single-frequency output power with a good beam quality. The output from the tapered diode laser is frequency doubled using periodically poled MgO:LiNbO3. We investigate the modulation potential of the green light and improve the modulation depth from 1:4 to 1:50.......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...

  17. Wavelength-dependent femtosecond pulse amplification in wideband tapered-waveguide quantum well semiconductor optical amplifiers.

    Science.gov (United States)

    Xia, Mingjun; Ghafouri-Shiraz, H

    2015-12-10

    In this paper, we study the wavelength-dependent amplification in three different wideband quantum well semiconductor optical amplifiers (QWAs) having conventional, exponentially tapered, and linearly tapered active region waveguide structures. A new theoretical model for tapered-waveguide QWAs considering the effect of lateral carrier density distribution and the strain effect in the quantum well is established based on a quantum well transmission line modeling method. The temporal and spectral characteristics of amplified femtosecond pulse are analyzed for each structure. It was found that, for the amplification of a single femtosecond pulse, the tapered-waveguide QWA provides higher saturation gain, and the output spectra of the amplified pulse in all three structures exhibit an apparent redshift and bandwidth narrowing due to the reduction of carrier density; however, the output spectrum in the tapered-waveguide amplifier is less distorted and exhibits smaller bandwidth narrowing. For the simultaneous amplification of two femtosecond pulses with different central frequencies, in all the three structures, two peaks appear in the output spectra while the peak at the frequency closer to the peak frequency of the QWA gain spectrum receives higher amplification due to the frequency (wavelength) dependence of the QWA gain. At a low peak power level of the input pulse, the bandwidth of each window in the tapered structure is larger than that of the conventional waveguide structure, which aggravates the spectrum alias in the amplification of femtosecond pulses with different central frequencies. As the peak powers of the two pulses increase, the spectrum alias in the conventional waveguide becomes more serious while there are small changes in the tapered structures. Also, we have found that in the amplification of a femtosecond pulse train, the linear-tapered QWAs exhibit the fastest gain recovery as compared with the conventional and exponentially tapered QWAs.

  18. Tapered dielectric structure in metal as a wavelength-selective surface plasmon polariton focuser

    Institute of Scientific and Technical Information of China (English)

    Zhang Yang; Zhao Qing; Liao Zhi-Min; Yu Da-Peng

    2009-01-01

    Symmetric tapered dielectric structures in metal have demonstrated applications such as the nanofocusing of surface plasmon polaxitons, as well as the waveguiding of V-channel polaxitons. Yet the fabrication of smooth-surfaced tapered structure remains an obstacle to most researchers. We have successfully developed a handy method to fabricate metal-sandwiched tapered nanostructures simply with electron beam lithography. Though these structures are slightly different from conventional symmetric V-shaped structures, systematic simulations show that similar functionality of surface plasmon polaxiton nanofocusing can still be achieved, When parameters are properly selected, wavelengthselective nanofocusing of surface plasmon polaritons can be obtained.

  19. 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.

  20. Extraordinary optical transmission with tapered slits: effect of higher diffraction and slit resonance orders

    DEFF Research Database (Denmark)

    Sondergaard, T.; Bozhevolnyi, S. I.; Beermann, J.;

    2012-01-01

    Transmission through thin metal films with a periodic arrangement of tapered slits is considered. Transmission maps covering a wide range of periods, film thicknesses, and taper angles are presented. The maps show resonant transmission when fundamental and higher-order slit resonances are excited....... A study of the effect on transmission of different combinations of available transmission and reflection diffraction orders show optimum total transmission when only the fundamental reflection order and higher transmission diffraction orders are available. The optimum taper angle is shown...

  1. Highly Sensitive Refractive Index Sensor Based on Adiabatically Tapered Microfiber Long Period Gratings

    Directory of Open Access Journals (Sweden)

    Choong Leng Ng

    2013-10-01

    Full Text Available We demonstrate a refractive index sensor based on a long period grating (LPG inscribed in a special photosensitive microfiber with double-clad profile. The fiber is tapered gradually enough to ensure the adiabaticity of the fiber taper. In other words, the resulting insertion loss is sufficiently small. The boron and germanium co-doped inner cladding makes it suitable for inscribing gratings into its tapered form. The manner of wavelength shift for refractive indices (RIs differs from conventional LPG, and the refractive index detection limit is 1.67 × 10−5.

  2. Riccati parameterized self-similar waves in tapered graded-index waveguides

    Science.gov (United States)

    Goyal, Amit; Gupta, Rama; Loomba, Shally; Kumar, C. N.

    2012-10-01

    We present a large family of self-similar waves by tailoring the tapering function, through Riccati parameter, in a tapered graded-index nonlinear waveguide amplifier. We show the existence of bright similaritons, self-similar Akhmediev breathers and self-similar rogue waves for generalized nonlinear Schrödinger equation with constant dispersion and nonlinearity, and a distributed gain. We illustrate the procedure to amplify the intensity of self-similar waves using isospectral Hamiltonian approach. This approach provides a handle to find analytically a wide class of tapering function and thus enabling one to control the self-similar wave structure and dynamical behavior.

  3. Quantification of the Contact Area at the Head-Stem Taper Interface of Modular Hip Prostheses.

    Directory of Open Access Journals (Sweden)

    Florian Witt

    Full Text Available Corrosion of modular taper junctions of hip implants may be associated with clinical failure. Taper design parameters, as well as the intraoperatively applied assembly forces, have been proposed to affect corrosion. Fretting corrosion is related to relative interface shear motion and fluid ingress, which may vary with contact force and area. It was hypothesised in this study that assembly forces modify the extent and distribution of the surface contact area at the taper interface between a cobalt chrome head and titanium stem taper with a standard threaded surface profile. Local abrasion of a thin gold coating applied to the stem taper prior to assembly was used to determine the contact area after disassembly. Profilometry was then used to assess permanent deformation of the stem taper surface profile. With increasing assembly force (500 N, 2000 N, 4000 N and 8000 N the number of stem taper surface profile ridges in contact with the head taper was found to increase (9.2±9.3%, 65.4±10.8%, 92.8±6.0% and 100% and the overall taper area in contact was also found to increase (0.6±0.7%, 5.5±1.0%, 9.9±1.1% and 16.1±0.9%. Contact was inconsistently distributed over the length of the taper. An increase in plastic radial deformation of the surface ridges (-0.05±0.14 μm, 0.1±0.14 μm, 0.21±0.22 μm and 0.96±0.25 μm was also observed with increasing assembly force. The limited contact of the taper surface ridges at lower assembly forces may influence corrosion rates, suggesting that the magnitude of the assembly force may affect clinical outcome. The method presented provides a simple and practical assessment of the contact area at the taper interface.

  4. Fusion splice between tapered inhibited coupling hypocycloid-core Kagome fiber and SMF.

    Science.gov (United States)

    Zheng, Ximeng; Debord, Benoît; Vincetti, Luca; Beaudou, Benoît; Gérôme, Frédéric; Benabid, Fetah

    2016-06-27

    We report for the first time on tapering inhibited coupling (IC) hypocycloid-core shape Kagome hollow-core photonic crystal fibers whilst maintaining their delicate core-contour negative curvature with a down-ratio as large as 2.4. The transmission loss of down-tapered sections reaches a figure as low as 0.07 dB at 1550 nm. The tapered IC fibers are also spliced to standard SMF with a total insertion loss of 0.48 dB. These results show that all-fiber photonic microcells with the ultra-low loss hypocycloid core-contour Kagome fibers is now possible.

  5. 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.

  6. 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.

  7. Efficient formalism for treating tapered structures using the Fourier modal method

    DEFF Research Database (Denmark)

    Østerkryger, Andreas Dyhl; Gregersen, Niels

    2016-01-01

    We investigate the development of the mode occupations in tapered structures using the Fourier modal method. In order to use the Fourier modal method, tapered structures are divided into layers of uniform refractive index in the propagation direction and the optical modes are found within each...... layer. This is not very efficient and in this proceeding we take the first steps towards a more efficient formalism for treating tapered structures using the Fourier modal method. We show that the coupling coefficients through the structure are slowly varying and that only the first few modes...

  8. Analysis of Semi-conductor Laser Diode with Two-dimension Nonlinearly Tapered Waveguide

    Institute of Scientific and Technical Information of China (English)

    LI Hong; HAUNG Dexiu

    2001-01-01

    A novel semiconductor laser diode with a two-dimension nonlinearly tapered waveguide is proposed and its property is studied by Fourier expanding method. It is shown that coupling loss between the semiconductor laser diode and a single mode fiber is reduced effectively, the reduction role of the nonlinearly tapered waveguide is more apparent than that of a linearly tapered waveguide , the minimum coupling loss is 0.36 dB, and the far field divergence is decreased. The reduction mechanism is discussed.

  9. Geometric and dimensional characteristics of simulated curved canals prepared with proTaper instruments

    OpenAIRE

    Renata de Castro Martins; Maria Guiomar de Azevedo Bahia; Vicente Tadeu Lopes Buono

    2010-01-01

    OBJECTIVE: This study identified which regions of ProTaper instruments work during curved root canal instrumentation. MATERIAL AND METHODS: Twelve ProTaper instruments of each type, S1, S2, F1, and F2, were assessed morphometrically by measuring tip angle, tip length, tip diameter, length of each pitch along the cutting blades, and instrument diameter at each millimeter from the tip. Curved canals in resin blocks were explored with manual stainless steel files and prepared with ProTaper instr...

  10. Suitability of Secondary PEEK Telescopic Crowns on Zirconia Primary Crowns: The Influence of Fabrication Method and Taper

    Directory of Open Access Journals (Sweden)

    Susanne Merk

    2016-11-01

    Full Text Available This study investigates the retention load (RL between ZrO2 primary crowns and secondary polyetheretherketone (PEEK crowns made by different fabrication methods with three different tapers. Standardized primary ZrO2 crowns were fabricated with three different tapers: 0°, 1°, and 2° (n = 10/group. Ten secondary crowns were fabricated (i milled from breCam BioHPP blanks (PM; (ii pressed from industrially fabricated PEEK pellets (PP (BioHPP Pellet; or (iii pressed from granular PEEK (PG (BioHPP Granulat. One calibrated operator adjusted all crowns. In total, the RL of 90 secondary crowns were measured in pull-off tests at 50 mm/min, and each specimen was tested 20 times. Two- and one-way ANOVAs followed by a Scheffé’s post-hoc test were used for data analysis (p < 0.05. Within crowns with a 0° taper, the PP group showed significantly higher retention load values compared with the other groups. Among the 1° taper, the PM group presented significantly lower retention loads than the PP group. However, the pressing type had no impact on the results. Within the 2° taper, the fabrication method had no influence on the RL. Within the PM group, the 2° taper showed significantly higher retention load compared with the 1° taper. The taper with 0° was in the same range value as the 1° and 2° tapers. No impact of the taper on the retention value was observed between the PP groups. Within the PG groups, the 0° taper presented significantly lower RL than the 1° taper, whereas the 2° taper showed no differences. The fabrication method of the secondary PEEK crowns and taper angles showed no consistent effect within all tested groups.

  11. Spatiotemporal periodicity of dislocation dynamics in a two-dimensional microfluidic crystal flowing in a tapered channel

    Science.gov (United States)

    Gai, Ya; Leong, Chia Min; Cai, Wei; Tang, Sindy K. Y.

    2016-10-01

    When a many-body system is driven away from equilibrium, order can spontaneously emerge in places where disorder might be expected. Here we report an unexpected order in the flow of a concentrated emulsion in a tapered microfluidic channel. The velocity profiles of individual drops in the emulsion show periodic patterns in both space and time. Such periodic patterns appear surprising from both a fluid and a solid mechanics point of view. In particular, when the emulsion is considered as a soft crystal under extrusion, a disordered scenario might be expected based on the stochastic nature of dislocation dynamics in microscopic crystals. However, an orchestrated sequence of dislocation nucleation and migration is observed to give rise to a highly ordered deformation mode. This discovery suggests that nanocrystals can be made to deform more controllably than previously thought. It can also lead to novel flow control and mixing strategies in droplet microfluidics.

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

    Science.gov (United States)

    Nunes, Matheus Henrique; Görgens, Eric Bastos

    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.

  13. Effect of preparation taper and height on strength and retention of zirconia crowns.

    Science.gov (United States)

    Ersu, Bahadir; Narin, Duygu; Aktas, Guliz; Yuzugullu, Bulem; Canay, Senay

    2012-01-01

    This study aimed to determine the effect of the taper and height of tooth preparations on the fracture strength and retention of zirconia crowns. Sixty-four dies were designed to simulate a crown preparation. Dies were machined with a height of either 4 mm (n = 16) or 7 mm (n = 16) and a taper of either 6 degrees (n = 16) or 20 degrees (n = 16). Copings were created from Lava zirconia blanks. Retention tests were performed using a universal testing machine. Copings were recemented on the dies, thermocycled, and tested for fracture strength. Data were analyzed using factorial analysis of variance. Retention was greater in the taller and less-tapered preparation designs. Taller preparations showed superior fracture strength. Preparing posterior teeth with higher axial walls and less taper is recommended to achieve increased retention and strength for zirconia crowns.

  14. 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.

  15. 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.

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

    Directory of Open Access Journals (Sweden)

    Matheus Henrique Nunes

    Full Text Available 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.

  17. 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.

  18. Attenuation measurement of infrared optical fibers by use of a hollow-taper-based coupling method.

    Science.gov (United States)

    Ilev, I K; Waynant, R W; Bonaguidi, M A

    2000-07-01

    An alternative method for attenuation measurement of infrared (IR) fibers is described. The method includes a simple technique for direct laser-to-fiber coupling with an uncoated glass hollow taper. The operating principle of the hollow taper is based on the grazing-incidence effect of light reflection. The hollow taper forms a smooth Gaussian-shaped profile of the output laser emission and provides the proper conditions for equilibrium-mode distribution of optical power within the test IR fibers. The experimental hollow-taper-based coupling method is used for measurement of attenuation and bending losses of various kinds of IR fiber, including solid-core (fluoride, chalcogenide, and germanium-doped) and hollow fibers.

  19. Corrosion on the acetabular liner taper from retrieved modular metal-on-metal total hip replacements.

    Science.gov (United States)

    Gascoyne, Trevor C; Dyrkacz, Richard M; Turgeon, Thomas R; Burnell, Colin D; Wyss, Urs P; Brandt, Jan-M

    2014-10-01

    Eight retrieved metal-on-metal total hip replacements displayed corrosion damage along the cobalt-chromium alloy liner taper junction with the Ti alloy acetabular shell. Scanning electron microscopy indicated the primary mechanism of corrosion to be grain boundary and associated crevice corrosion, which was likely accelerated through mechanical micromotion and galvanic corrosion resulting from dissimilar alloys. Coordinate measurements revealed up to 4.3mm(3) of the cobalt-chromium alloy taper surface was removed due to corrosion, which is comparable to previous reports of corrosion damage on head-neck tapers. The acetabular liner-shell taper appears to be an additional source of metal corrosion products in modular total hip replacements. Patients with these prostheses should be closely monitored for signs of adverse reaction towards corrosion by-products.

  20. 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.

  1. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Morrissey, Michael J.; Deasy, Kieran [Department of Applied Physics and Instrumentation, Cork Institute of Technology, Cork (Ireland); Photonics Centre, Tyndall National Institute, University College Cork, Prospect Row, Cork (Ireland); Wu Yuqiang; Nic Chormaic, Sile [Photonics Centre, Tyndall National Institute, University College Cork, Prospect Row, Cork (Ireland); Department of Physics, University College Cork, Cork (Ireland); Chakrabarti, Shrabana [Photonics Centre, Tyndall National Institute, University College Cork, Prospect Row, Cork (Ireland)

    2009-05-15

    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.

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

    Science.gov (United States)

    Morrissey, Michael J.; Deasy, Kieran; Wu, Yuqiang; Chakrabarti, Shrabana; Nic Chormaic, Síle

    2009-05-01

    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.

  4. Effect of Hematocrit on Wall Shear Stress for Blood Flow through Tapered Artery

    OpenAIRE

    Singh, A. K.; Singh, D. P.

    2013-01-01

    The purpose of this study to show the effects of Hematocrit (Red blood cells), height of stenosis, porous parameter and velocity of blood on wall shear stress of the flow of blood through tapered artery. The study reveals that wall shear stress reduces for increasing Hematocrit percentage. It is also observed that wall shear stress increases as stenosis height and porous parameter increase whereas it decreases with the increasing values of velocity of blood and slope of tapered artery.

  5. Optical Detection of Single Nanoparticles with a Sub-wavelength Fiber-Taper

    CERN Document Server

    Zhu, Jiangang; Yang, Lan

    2013-01-01

    A nanoparticle detection scheme with single particle resolution is presented. The sensor contains only a taper fiber thus offering the advantages of compactness and installation flexibility. Sensing method is based on monitoring the transmitted light power which shows abrupt jumps with each particle binding to the taper surface. The experimental validation of the sensor is demonstrated with polystyrene nanoparticles of radii 120 nm and 175 nm in the 1550 nm wavelength band.

  6. Carbon nanotube/polymer composite coated tapered fiber for four wave mixing based wavelength conversion.

    Science.gov (United States)

    Xu, Bo; Omura, Mika; Takiguchi, Masato; Martinez, Amos; Ishigure, Takaaki; Yamashita, Shinji; Kuga, Takahiro

    2013-02-11

    In this paper, we demonstrate a nonlinear optical device based on a fiber taper coated with a carbon nanotube (CNT)/polymer composite. Using this device, four wave mixing (FWM) based wavelength conversion of 10 Gb/s Non-return-to-zero signal is achieved. In addition, we investigate wavelength tuning, two photon absorption and estimate the effective nonlinear coefficient of the CNTs embedded in the tapered fiber to be 1816.8 W(-1)km(-1).

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

    OpenAIRE

    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...

  8. Non-Newtonian model study for blood flow through a tapered artery with a stenosis

    Directory of Open Access Journals (Sweden)

    Noreen Sher Akbar

    2016-03-01

    Full Text Available The blood flow through a tapered artery with a stenosis is analyzed, assuming the blood as tangent hyperbolic fluid model. The resulting nonlinear implicit system of partial differential equations is solved analytically with the help of perturbation method. The expressions for shear stress, velocity, flow rate, wall shear stress and longitudinal impedance are obtained. The variations of power law index m, Weissenberg number We, shape of stenosis n and stenosis size δ are discussed different type of tapered arteries.

  9. 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.

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

    OpenAIRE

    2009-01-01

    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 co...

  11. WGM-Resonator/Tapered-Waveguide White-Light Sensor Optics

    Science.gov (United States)

    Stekalov, Dmitry; Maleki, Lute; Matsko, Andrey; Savchenkov, Anatoliy; Iltchenko, Vladimir

    2007-01-01

    Theoretical and experimental investigations have demonstrated the feasibility of compact white-light sensor optics consisting of unitary combinations of (1) low-profile whispering-gallery-mode (WGM) resonators and (2) tapered rod optical waveguides. These sensors are highly wavelength-dispersive and are expected to be especially useful in biochemical applications for measuring absorption spectra of liquids. These sensor optics exploit the properties of a special class of non-diffracting light beams that are denoted Bessel beams because their amplitudes are proportional to Bessel functions of the radii from their central axes. High-order Bessel beams can have large values of angular momentum. In a sensor optic of this type, a low-profile WGM resonator that supports modes having large angular momenta is used to generate high-order Bessel beams. As used here, "low-profile" signifies that the WGM resonator is an integral part of the rod optical waveguide but has a radius slightly different from that of the adjacent part(s).

  12. 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

  13. Effects of Tapered Betafunction in the LCLS Undulators

    CERN Document Server

    Goldammer, K; Huang, Z

    2005-01-01

    The Linac coherent Light Source (LCLS) is an x-ray free-electron laser (FEL) project based on the SLAC linac. With its nominal set of electron beam, focusing and undulator parameters, it is designed to achieve SASE saturation at an undulator length of about 100m with an average power of 10GW. In order to keep the electron beam focused in the undulators, a FODO lattice is integrated along the entire length of the undulators. Nominally, the quadrupoles strengths are chosen to produce nearly constant beta function and beam size along the undulator, optimized for the FEL interaction in the exponential growth regime. Since these quadrupoles are electromagnetic, it is possible to adjust the individual quadrupole strength to vary the beta function and the beam size along the undulator, tailoring the FEL interaction in the startup and the saturation regimes. In this paper, we present simulation studies of the tapered beta function in the LCLS undulator and discuss the generated x-ray properties.

  14. Slow-Light Propagation in a Tapered Dielectric Periodic Waveguide over Broad Frequency Range

    Institute of Scientific and Technical Information of China (English)

    FANG Yi-Jiao; CHEN Zhuo; WANG Zhen-Lin

    2011-01-01

    @@ A tapered waveguide composed of a one-dimensional periodic arrangement of dielectric materialis proposed for light trapping.The equifrequency contours(EFC) of silicon-air multilayer photonic crystals within the first bandgap region are first studied.A zero-group-velocity at the first Brillouin zone boundary along the grating vector is predicted.The propagation constants and eigenfrequencies of the first-order guiding modes are numerically investigated for photonic crystal waveguide structures with a finite thickness.Different frequency components of the guiding modes are found to slov and stop at different thicknesses inside such a tapered waveguide structure.In addition,the time-evolution of a femto-second pulse propagating in the tapered waveguide is also demonstrated.%A tapered waveguide composed of a one-dimensional periodic arrangement of dielectric material is proposed for light trapping. The equifrequency contours (EFC) of silicon-air multilayer photonic crystals within the first bandgap region are first studied. A zero-group-velocity at the first Brillouin zone boundary along the grating vector is predicted. The propagation constants and eigenfrequencies of the first-order guiding modes are numerically investigated for photonic crystal waveguide structures with a finite thickness. Different frequency components of the guiding modes are found to slow and stop at different thicknesses inside such a tapered waveguide structure. In addition, the time-evolution of a femto-second pulse propagating in the tapered waveguide is also demonstrated.

  15. Morse taper dental implants and platform switching: The new paradigm in oral implantology

    Science.gov (United States)

    Macedo, José Paulo; Pereira, Jorge; Vahey, Brendan R.; Henriques, Bruno; Benfatti, Cesar A. M.; Magini, Ricardo S.; López-López, José; Souza, Júlio C. M.

    2016-01-01

    The aim of this study was to conduct a literature review on the potential benefits with the use of Morse taper dental implant connections associated with small diameter platform switching abutments. A Medline bibliographical search (from 1961 to 2014) was carried out. The following search items were explored: “Bone loss and platform switching,” “bone loss and implant-abutment joint,” “bone resorption and platform switching,” “bone resorption and implant-abutment joint,” “Morse taper and platform switching.” “Morse taper and implant-abutment joint,” Morse taper and bone resorption,” “crestal bone remodeling and implant-abutment joint,” “crestal bone remodeling and platform switching.” The selection criteria used for the article were: meta-analysis; randomized controlled trials; prospective cohort studies; as well as reviews written in English, Portuguese, or Spanish languages. Within the 287 studies identified, 81 relevant and recent studies were selected. Results indicated a reduced occurrence of peri-implantitis and bone loss at the abutment/implant level associated with Morse taper implants and a reduced-diameter platform switching abutment. Extrapolation of data from previous studies indicates that Morse taper connections associated with platform switching have shown less inflammation and possible bone loss with the peri-implant soft tissues. However, more long-term studies are needed to confirm these trends. PMID:27011755

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

    Science.gov (United States)

    Asgekar, V; Lehnert, U; Michel, P

    2012-01-01

    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.

  17. An inexpensive heat-and-pull rig for fiber taper fabrication

    CERN Document Server

    Ward, J; Shortt, B; Morrissey, M; Deasy, K; Chormaic, S N

    2006-01-01

    We describe an inexpensive and reproducible method of fabricating adiabatic tapers with 3-4 micron diameter. The method is based on a heat-and-pull rig, whereby a CO2 laser is continuously scanned across a length of fiber that is being pulled synchronously. Our system relies on a CO2 mirror mounted on an inexpensive geared stepper motor in order to scan the laser beam across the taper region and ensure adiabaticity. We show that this system offers a reliable alternative to more traditional rigs incorporating galvanometer scanners. We have routinely obtained transmission losses between 0.1 and 0.3 dB. The operation of the rig is described in detail and an analysis on the produced tapers is provided. The flexibility of the rig is demonstrated by fabricating prolate dielectric microresonators using the microtapering technique. Such a rig is of interest to a range of fields that require tapered fiber fabrication such as microcavity-taper coupling, atom guiding along a tapered fiber, optical fiber sensing and the ...

  18. 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.

  19. 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.

  20. Optical trapping of microparticles using silicon nitride waveguide junctions and tapered-waveguide junctions on an optofluidic chip.

    Science.gov (United States)

    Cai, Hong; Poon, Andrew W

    2012-10-01

    We study optical trapping of microparticles on an optofluidic chip using silicon nitride waveguide junctions and tapered-waveguide junctions. We demonstrate the trapping of single 1 μm-sized polystyrene particles using the evanescent field of waveguide junctions connecting a submicrometer-sized input-waveguide and a micrometer-sized output-waveguide. Particle trapping is localized in the vicinity of the junction. We also demonstrate trapping of one and two 1μm-sized polystyrene particles using tapered-waveguide junctions connecting a submicrometer-sized singlemode input-waveguide and a micrometer-sized multimode output-waveguide. Particle trapping occurs near the taper output end, the taper center and the taper input end, depending on the taper aspect ratio.

  1. 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.

  2. 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

    OpenAIRE

    Fauzia Ashraf; Pushpa Shankarappa; Abhinav Misra; Asheesh Sawhney; Nandamuri Sridevi; Anu Singh

    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...

  3. Trapping and Propelling Microparticles at Long Range by Using an Entirely Stripped and Slightly Tapered No-Core Optical Fiber

    Directory of Open Access Journals (Sweden)

    Yen-Si Huang

    2013-02-01

    Full Text Available A stripped no-core optical fiber with a 125 µm diameter was transformed into a symmetric and unbroken optical fiber that tapers slightly to a 45-µm-diameter waist. The laser light can be easily launched into the no-core optical fiber. The enhanced evanescent wave of the slightly tapered no-core optical fiber can attract nearby 5-µm-diameter polystyrene microparticles onto the surface of the tapered multimode optical fiber within fast flowing fluid and propel the trapped particles in the direction of the light propagation to longer delivery range than is possible using a slightly tapered telecom single-mode optical fiber.

  4. Trapping and propelling microparticles at long range by using an entirely stripped and slightly tapered no-core optical fiber.

    Science.gov (United States)

    Sheu, Fang-Wen; Huang, Yen-Si

    2013-02-28

    A stripped no-core optical fiber with a 125 µm diameter was transformed into a symmetric and unbroken optical fiber that tapers slightly to a 45-µm-diameter waist. The laser light can be easily launched into the no-core optical fiber. The enhanced evanescent wave of the slightly tapered no-core optical fiber can attract nearby 5-µm-diameter polystyrene microparticles onto the surface of the tapered multimode optical fiber within fast flowing fluid and propel the trapped particles in the direction of the light propagation to longer delivery range than is possible using a slightly tapered telecom single-mode optical fiber.

  5. Flexural-torsional vibration of a tapered C-section beam

    Science.gov (United States)

    Dennis, Scott T.; Jones, Keith W.

    2017-04-01

    Previous studies have shown that numerical models of tapered thin-walled C-section beams based on a stepped or piecewise prismatic beam approximation are inaccurate regardless of the number of elements assumed in the discretization. Andrade recently addressed this problem by extending Vlasov beam theory to a tapered geometry resulting in new terms that vanish for the uniform beam. (See One-Dimensional Models for the Spatial Behaviour of Tapered Thin-Walled Bars with Open Cross-Sections: Static, Dynamic and Buckling Analyses, PhD Thesis, University of Coimbra, Portugal, 2012, https://estudogeral.sib.uc.pt) In this paper, we model the coupled bending-twisting vibration of a cantilevered tapered thin-walled C-section using a Galerkin approximation of Andrade's beam equations resulting in an 8-degree-of-freedom beam element. Experimental natural frequencies and mode shapes for 3 prismatic and 2 tapered channel beams are compared to model predictions. In addition, comparisons are made to detailed shell finite element models and exact solutions for the uniform beams to confirm the validity of the approach. Comparisons to the incorrect stepped model are also presented.

  6. Non-linear critical taper model and determination of accretionary wedge strength

    Science.gov (United States)

    Yang, Che-Ming; Dong, Jia-Jyun; Hsieh, Yuan-Lung; Liu, Hsueh-Hua; Liu, Cheng-Lung

    2016-12-01

    The critical taper model has been widely used to evaluate the strength contrast between the wedge and the basal detachment of fold-and-thrust belts and accretionary wedges. However, determination of the strength parameters using the traditional critical taper model, which adopts the Mohr-Coulomb failure criterion, is difficult, if not impossible. In this study, we propose a modified critical taper model that incorporates the non-linear Hoek-Brown failure criterion. The parameters in the proposed critical Hoek-Brown wedge CHBW model can be directly evaluated via field investigations and laboratory tests. Meanwhile, the wedge strength is a function of the wedge thickness, which is oriented from stress non-linearity. The fold-and-thrust belt in western central Taiwan was used as an example to validate the proposed model. The determined wedge strength was 0.86 using a representative wedge thickness of 5.3 km; this was close to the inferred value of 0.6 from the critical taper. Interestingly, a concave topographic relief is predicted as a result of the wedge thickness dependency of the wedge strength, even if the wedge is composed of homogeneous materials and if the strength of the detachment is uniform. This study demonstrates that the influence of wedge strength on the critical taper angle can be quantified by the spatial distribution of strength variables and by the consideration of the wedge thickness dependency of wedge strength.

  7. Experimental stress-strain analysis of tapered silica optical fibers with nanofiber waist

    CERN Document Server

    Holleis, Sigrid; Wuttke, Christian; Schneeweiss, Philipp; Rauschenbeutel, Arno

    2014-01-01

    We experimentally determine tensile force-elongation diagrams of tapered optical fibers with a nanofiber waist. The tapered optical fibers are produced from standard silica optical fibers using a heat and pull process. Both, the force-elongation data and scanning electron microscope images of the rupture points indicate a brittle material. Despite the small waist radii of only a few hundred nanometers, our experimental data can be fully explained by a nonlinear stress-strain model that relies on material properties of macroscopic silica optical fibers. This is an important asset when it comes to designing miniaturized optical elements as one can rely on the well-founded material characteristics of standard optical fibers. Based on this understanding, we demonstrate a simple and non-destructive technique that allows us to determine the waist radius of the tapered optical fiber. We find excellent agreement with independent scanning electron microscope measurements of the waist radius.

  8. Experimental stress–strain analysis of tapered silica optical fibers with nanofiber waist

    Energy Technology Data Exchange (ETDEWEB)

    Holleis, S.; Hoinkes, T.; Wuttke, C.; Schneeweiss, P.; Rauschenbeutel, A. [Vienna Center for Quantum Science and Technology, TU Wien—Atominstitut, Stadionallee 2, 1020 Vienna (Austria)

    2014-04-21

    We experimentally determine tensile force–elongation diagrams of tapered optical fibers with a nanofiber waist. The tapered optical fibers are produced from standard silica optical fibers using a heat and pull process. Both, the force–elongation data and scanning electron microscope images of the rupture points indicate a brittle material. Despite the small waist radii of only a few hundred nanometers, our experimental data can be fully explained by a nonlinear stress–strain model that relies on material properties of macroscopic silica optical fibers. This is an important asset when it comes to designing miniaturized optical elements as one can rely on the well-founded material characteristics of standard optical fibers. Based on this understanding, we demonstrate a simple and non-destructive technique that allows us to determine the waist radius of the tapered optical fiber. We find excellent agreement with independent scanning electron microscope measurements of the waist radius.

  9. 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.

  10. Analytical Model for the End-Bearing Capacity of Tapered Piles Using Cavity Expansion Theory

    Directory of Open Access Journals (Sweden)

    Suman Manandhar

    2012-01-01

    Full Text Available On the basis of evidence from model tests on increasing the end-bearing behavior of tapered piles at the load-settlement curve, this paper proposes an analytical spherical cavity expansion theory to evaluate the end-bearing capacity. The angle of tapering is inserted in the proposed model to evaluate the end-bearing capacity. The test results of the proposed model in different types of sands and different relative densities show good effects compared to conventional straight piles. The end-bearing capacity increases with increases in the tapering angle. The paper then propounds a model for prototypes and real-type pile tests which predicts and validates to evaluate the end-bearing capacity.

  11. Waveguide tapering for beam-width control in a waveguide transducer.

    Science.gov (United States)

    Kwon, Young Eui; Jeon, Hyun Joong; Kim, Hoe Woong; Kim, Yoon Young

    2014-03-01

    In a waveguide transducer that transmits an ultrasonic wave through a waveguide unit to a test structure, it is most preferred to send a non-dispersive ultrasonic wave of a narrow beam width. However, there is an unresolved conflict between the generation of the non- or less-dispersive wave and the transmission of a narrow-beam wave into a test structure. Among others, the thickness of the waveguide unit in a waveguide transducer is the key variable determining these two conflicting criteria, but the use of a uniformly-thick waveguide of any thickness cannot fulfill the two conflicting criteria simultaneously. In this study, we propose a specially-engineered tapered waveguide unit for the simultaneous satisfaction. An excitation unit is installed at the end of the thin region of the tapered waveguide and generates only the lowest non-dispersive shear-horizontal wave. Then the generated wave propagates through the tapered region of the waveguide unit and reaches the thick region of the waveguide with insignificant mode conversion to higher modes. If the tapered waveguide is used, the surviving lowest mode in the thick region of the waveguide is shown to carry most of the transmitted power and is finally propagated into a test structure. Because the beam size of the propagated wave and the thickness of the contacting waveguide region are inversely related, the thick contacting region of the tapered waveguide ensures narrow beam width. Numerical and experimental investigations were performed to check the effectiveness of the proposed waveguide-tapering approach.

  12. Evaluation of the tapered PMMA fiber sensor response due to the ionic interaction within electrolytic solutions

    Science.gov (United States)

    Batumalay, M.; Rahman, H. A.; Kam, W.; Ong, Y. S.; Ahmad, F.; Zakaria, R.; Harun, S. W.; Ahmad, H.

    2014-01-01

    A tapered plastic multimode fiber (PMMA) optical sensor is proposed and demonstrated for continuous monitoring of solutions based on different concentration of sodium chloride and glucose in deionized water The tapered PMMA fiber was fabricated using an etching method involving deionized water and acetone to achieve a waist diameter and length of 0.45 mm and 10 mm, respectively, and was used to investigate the effect of straight, U-shape, and knot shape against concentration for both sodium chloride and glucose. The results show that there is a strong dependence of the electrolytic and non-electrolytic nature of the chemical solutions on the sensor output. It is found that the sensitivity of the sodium chloride concentration sensor with the straight tapered fiber probe was 0.0023 mV/%, which was better than the other probe arrangements of U-shape and knot. Meanwhile, the glucose sensor performs with the highest sensitivity of 0.0026 mV/wt % with the knot-shaped tapered fiber probe. In addition, a tapered PMMA probe which was coated by silver film was fabricated and demonstrated using calcium hypochlorite (G70) solution. The working mechanism of such a device is based on the observed increment in the transmission of the sensor that is immersed in solutions of higher concentration. As the concentration varies from 0 ppm to 6 ppm, the output voltage of the sensor increases linearly from 3.61 mV to 4.28 mV with a sensitivity of 0.1154 mV/ppm and a linearity of more than 99.47%. The silver film coating increases the sensitivity of the proposed sensor due to the effective cladding refractive index, which increases with the coating and thus allows more light to be transmitted from the tapered fiber.

  13. Coupling between angled-facet amplifiers and tapered lens-ended fibers

    DEFF Research Database (Denmark)

    Wang, Zheng; Mikkelsen, Benny; Pedersen, Bo

    1991-01-01

    The coupling between angled facet amplifiers and tapered lens-ended fibers is investigated theoretically and experimentally. The theoretical investigation is based on a three-dimensional plane wave model which accounts for the phase differences introduced by the angled facets. The coupling...... is investigated with respect to the beam parameters of the amplifier waveguide and the tapered lens-ended fiber, and with respect to the fiber position. The excess coupling losses due to the facet angle and to the variation of the fiber lens radius are investigated theoretically and found to be in good agreement...

  14. Polarization insensitive all-fiber mode-lockers functioned by carbon nanotubes deposited onto tapered fibers

    Science.gov (United States)

    Song, Yong-Won; Morimune, Keiyo; Set, Sze Y.; Yamashita, Shinji

    2007-01-01

    The authors demonstrate a nonblocked all-fiber mode locker operated by the interaction of carbon nanotubes with the evanescent field of propagating light in a tapered fiber. Symmetric cross section of the device with the randomly oriented nanotubes guarantees the polarization insensitive operation of the pulse formation. In order to minimize the scattering, the carbon nanotubes are deposited within a designed area around the tapered waist. The demonstrated passively pulsed laser has the repetition rate of 7.3MHz and the pulse width of 829fs.

  15. A refractive index sensor based on taper Michelson interferometer in multimode fiber

    Science.gov (United States)

    Fu, Xinghu; Zhang, Jiangpeng; Wang, Siwen; Fu, Guangwei; Liu, Qiang; Jin, Wa; Bi, Weihong

    2016-11-01

    A refractive index sensor based on taper Michelson interferometer in multimode fiber is proposed. The Hydrofluoric acid corrosion processing is studied in the preparation of single cone multimode optical fiber sensor. The taper Michelson interferometer is fabricated by changing corrosion time. The relationship between fiber sensor feature and corrosion time is analyzed. The experimental results show that the interference spectrum shift in the direction of short wave with the increase of the refractive index. The refractive index sensitivity can reach 115.8008 nm/RIU. Thereby, it can be used in detecting the refractive index in different areas including the environmental protection, health care and food production.

  16. Directional anemometer based on an anisotropic flat-clad tapered fiber Michelson interferometer

    Science.gov (United States)

    Lee, Cheng-Ling; Lee, Chung-Fen; Li, Chai-Ming; Chiang, Tsai-Ching; Hsiao, Ying-Li

    2012-07-01

    This work demonstrates a sensitive directional anemometer that is based on a pendulum-type of anisotropic flat-clad tapered fiber Michelson interferometer (AFCTFMI). The AFCTFMI is fabricated by tapering an anisotropic flat-cladding fiber to establish structural anisotropy, and enables the sensing of the direction and magnitude of flowing air (wind). Wavelength shifts and fringes visibility of the measured interference fringes are correlated with the magnitude and furthermore the direction of the wind. Experimental results agree closely with the theoretical analysis. The directional anemometer can simultaneously and effectively indicate the direction, and sensitively measure the magnitude of wind.

  17. 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....

  18. 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.

  19. Temperature or strain induced adjustable-chirp characteristics of uniform fibre grating with tapered metal coating

    Institute of Scientific and Technical Information of China (English)

    Liu Yan; Li Bin; Zheng Kai; Tan Zhong-Wei; Chen Yong; Wang Yan Hua; Ren Wen-Hua; Jian Shui-Sheng

    2007-01-01

    Temperature and strain characteristics of uniform fibre grating with tapered metal coatings have been analysed theoretically, by which adjustable chirp characteristics of such gratings are shown. Electroplating is adopted to fabricate such gratings, and the tapered metal coating is obtained by gradually drawing the fibre grating out of the solution during the process of electroplating. The gradually changing cross-sectional area of the metal coating is calculated by a newly suggested numerical method. By combining the theoretical and numerical simulation analyses, the gratings' characteristics are given at various temperatures and strains. The results obtained using such a method are also testified by experiments.

  20. Shaping ability of ProTaper NEXT, ProTaper Universal and iRace files in simulated S-shaped canals.

    Science.gov (United States)

    Hiran-us, Sirawut; Pimkhaokham, Somsinee; Sawasdichai, Jirapat; Ebihara, Arata; Suda, Hideaki

    2016-04-01

    The aim of this study was to determine the shaping ability of three nickel-titanium endodontic file systems by comparing three parameters: canal deviation, apical foramen position and instrumentation time. A glide path was established in 30 simulated S-shaped canal blocks that were randomly assigned into three groups (n = 10): ProTaper Universal, ProTaper NEXT and iRace. Each group was instrumented per its manufacturer's directions. Pre- and postoperative images were superimposed to determine any canal deviation or change in apical foramen position. The instrumentation times were recorded. The iRace system resulted in the least mean canal deviation. The apical foramen position was least shifted by the iRace system. The iRace system also required the least instrumentation time. The iRace system demonstrated the most favourable shaping ability in all three parameters.

  1. Experimental Measurement of the Static Coefficient of Friction at the Ti-Ti Taper Connection in Total Hip Arthroplasty

    NARCIS (Netherlands)

    Bitter, T.; Khan, I.; Marriott, T.; Schreurs, B.W.; Verdonschot, N.J.J.; Janssen, D.

    2016-01-01

    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 achiev

  2. Feasibility of early tapering of cyclosporine following reduced-intensity stem cell transplantation for advanced hematologic or solid malignancies.

    Science.gov (United States)

    Hori, Akiko; Kami, Masahiro; Ohnishi, Mutsuko; Murashige, Naoko; Kojima, Rie; Takaue, Yoichi

    2005-07-01

    Although some researchers have reported that early tapering of cyclosporine is feasible and beneficial to augment graft-versus-leukemia effects after conventional stem-cell transplantation, there is little information on the feasibility of this strategy following reduced-intensity stem cell transplantation (RIST). We summarized outcomes of 17 patients who underwent early tapering of cyclosporine following RIST from HLA-identical siblings.

  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. Tapered toothbrush filaments in relation to gingival abrasion, removal of plaque and treatment of gingivitis

    NARCIS (Netherlands)

    Versteeg, P.A.; Piscaer, M.; Rosema, N.A.M.; Timmerman, M.F.; van der Velden, U.; van der Weijden, G.A.

    2008-01-01

    Objectives: To compare a tapered filament toothbrush (TFTB) to a control toothbrush (ADA) in their potential to cause gingival abrasion and improve the gingival condition following a period of experimental gingivitis. Methods: Thirty-two subjects refrained from brushing mandibular teeth for 21 days.

  5. 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.

  6. Analysis the fatigue using pro taper rotary instruments durin instrumentation of extrated mandibular premolars. SEM observation.

    OpenAIRE

    Siragusa, Martha; Racciatti, Gabriela; García, María

    2007-01-01

    Recibido: Marzo 2007 Aceptado: Julio 2007 Siragusa, Martha; Racciatti, Gabriela y García, María. Analysis the fatigue using pro taper rotary instruments durin instrumentation of extrated mandibular premolars. SEM observation. Electronic Journal of Endodontics Rosario [Online], Volumen 2 Número 13. [octubre 2007]. http://www.endojournal.com.ar/journal/index.php/ejer/article/view/44. ISSN 1666-6143.

  7. 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

  8. 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…

  9. A COMPATIBLE ESTIMATION MODEL OF STEM VOLUME AND TAPER FOR Acacia mangium Willd. PLANTATIONS

    Directory of Open Access Journals (Sweden)

    Haruni Krisnawati

    2016-04-01

    Full Text Available This study describes the establishment of a compatible volume estimation model for Acacia mangium Willd on the basis of 279 felled sample trees collected from the A. mangium plantation stands in South Sumatra, Indonesia. The model comprises of a total volume model and a stem taper model, which is compatible in the sense of the total volume obtained by integration of the taper model being equal to that computed by the total volume model. Several well-known total volume functions were evaluated including constant form factor, combined variable, generalized combine variable, logarithmic, generalized logarithmic and Honer transformed variables. A logarithmic model was determined to be the best and was then used as the basis for deriving the taper model. Appropriate statistical procedures were used in model fitting to account for the problems of heteroscedasticity and autocorrelation that are associated with the construction of volume and taper functions. The simultaneous fitting method of the Seemingly Unrelated Regression (SUR improved the parameter estimates and goodness-of-fit statistics while ensuring numeric consistency among the component models and reducing the total squared error obtained by an independent fitting method. The developed model can be used to estimate total stem volume, merchantable volume to any merchantability diameter limit at any height, and (possibly height of any diameter based on only easily measurable parameters such as diameter at breast height and total tree height for the species analysed.

  10. 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.

  11. Parametric study of elastic stiffness for the leaf type holddown spring assembly with uniformly tapered width

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ki Nam; Seo, Jeong Min; Lee, Jin Suk [Korea Atomic Energy Research Institute, Daeduk (Korea, Republic of)

    1996-05-01

    A formula for the elastic stiffness of the leaf type holddown spring(HDS) assembly with uniformly tapered width from w{sub 0} to w{sub 1} (w{sub 0} , w{sub 1}) has been analytically derived by applying the engineering beam theory and Casiliano`s theory based on strain energy. Elastic stiffnesses for the tapered-width HDSs which are newly designed in the same dimensional design spaces as 14x14 type and 17x17 type KOFA HDS assembly have been estimated form the derived formula and also parametric study of elastic stiffness for their HDSs have been carried out. It is found that elastic stiffnesses of the newly designed tapered-width HDS assemblies have been about 32 {approx} 33 % about higher than those of KOFA holddown spring assemblies, and that effects of axial and shear force on the elastic stiffness have been 0.15 {approx} 0.21 % of the elastic stiffness. Therefore in case that the newly designed tapered-width HDS assemblies have been adapted in KOFA, it is expected that numbers of leaves composing a HDS assembly could be lessened by on due to their having a high elastic stiffness. 13 tabs., 23 figs., 16 refs. (Author) .new.

  12. Narrow line width operation of a 980 nm gain guided tapered diode laser bar

    DEFF Research Database (Denmark)

    Vijayakumar, Deepak; Jensen, Ole Bjarlin; Barrientos-Barria, Jessica;

    2011-01-01

    We demonstrate two different schemes for the spectral narrowing of a 12 emitter 980 nm gain guided tapered diode laser bar. In the first scheme, a reflective grating has been used in a Littman Metcalf configuration and the wavelength of the laser emission could be narrowed down from more than 5.5...

  13. 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

  14. 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 ...

  15. Truncated acoustic black hole structure with the optimized tapering shape and damping coating

    DEFF Research Database (Denmark)

    Ih, Jeong-Guon; Kim, Miseong; Lee, Ik Jin

    2016-01-01

    The acoustic black hole (ABH) structure can be an option as a vibration damper by providing a tapered wedge at the end of a beam or plate. However, not much work has been done on design to yield an effective ABH design for such a plate. We attempt to optimize the shape of the ABH to effectively...

  16. Tapered Optical Fiber Sensor for Label-Free Detection of Biomolecules

    Directory of Open Access Journals (Sweden)

    Xingwei Wang

    2011-03-01

    Full Text Available This paper presents a fast, highly sensitive and low-cost tapered optical fiber biosensor that enables the label-free detection of biomolecules. The sensor takes advantage of the interference effect between the fiber’s first two propagation modes along the taper waist region. The biomolecules bonded on the taper surface were determined by demodulating the transmission spectrum phase shift. Because of the sharp spectrum fringe signals, as well as a relatively long biomolecule testing region, the sensor displayed a fast response and was highly sensitive. To better understand the influence of various biomolecules on the sensor, a numerical simulation that varied biolayer parameters such as thickness and refractive index was performed. The results showed that the spectrum fringe shift was obvious to be measured even when the biolayer was only nanometers thick. A microchannel chip was designed and fabricated for the protection of the sensor and biotesting. Microelectromechanical systems (MEMS fabrication techniques were used to precisely control the profile and depth of the microchannel on the silicon chip with an accuracy of 2 μm. A tapered optical fiber biosensor was fabricated and evaluated with an Immune globulin G (IgG antibody-antigen pair.

  17. 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

    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...

  18. Step-tapered operation of the FEL: Efficiency enhancement and two-colour operation

    NARCIS (Netherlands)

    Jaroszynski, D. A.; Prazeres, R.; Glotin, F.; Marcouille, O.; Ortega, J. M.; Oepts, D.; van der Meer, A. F. G.; Knippels, G.M.H.; van Amersfoort, P. W.

    1996-01-01

    We present measurements of the temporal and spectral properties of radiation produced from the step-tapered undulator infrared free-electron lasers (FELs), CLIO in France and FELIX in the Netherlands. Using a two section undulator with independently adjustable deflection parameters, K, the FEL will

  19. Vibration-Assisted Femtosecond Laser Drilling with Controllable Taper Angles for AMOLED Fine Metal Mask Fabrication

    Directory of Open Access Journals (Sweden)

    Wonsuk Choi

    2017-02-01

    Full Text Available This study investigates the effect of focal plane variation using vibration in a femtosecond laser hole drilling process on Invar alloy fabrication quality for the production of fine metal masks (FMMs. FMMs are used in the red, green, blue (RGB evaporation process in Active Matrix Organic Light-Emitting Diode (AMOLED manufacturing. The taper angle of the hole is adjusted by attaching the objective lens to a micro-vibrator and continuously changing the focal plane position. Eight laser pulses were used to examine how the hole characteristics vary with the first focal plane’s position, where the first pulse is focused at an initial position and the focal planes of subsequent pulses move downward. The results showed that the hole taper angle can be controlled by varying the amplitude of the continuously operating vibrator during femtosecond laser hole machining. The taper angles were changed between 31.8° and 43.9° by adjusting the vibrator amplitude at a frequency of 100 Hz. Femtosecond laser hole drilling with controllable taper angles is expected to be used in the precision micro-machining of various smart devices.

  20. Tapering Long-term Opioid Therapy in Chronic Noncancer Pain: Evidence and Recommendations for Everyday Practice.

    Science.gov (United States)

    Berna, Chantal; Kulich, Ronald J; Rathmell, James P

    2015-06-01

    Increasing concern about the risks and limited evidence supporting the therapeutic benefit of long-term opioid therapy for chronic noncancer pain are leading prescribers to consider discontinuing the use of opioids. In addition to overt addiction or diversion, the presence of adverse effects, diminishing analgesia, reduced function and quality of life, or the absence of progress toward functional goals can justify an attempt at weaning patients from long-term opioid therapy. However, discontinuing opioid therapy is often hindered by patients' psychiatric comorbidities and poor coping skills, as well as the lack of formal guidelines for the prescribers. The aim of this article is to review the existing literature and formulate recommendations for practitioners aiming to discontinue long-term opioid therapy. Specifically, this review aims to answer the following questions: What is an optimal opioid tapering regimen? How can the risks involved in a taper be managed? What are the alternatives to an opioid taper? A PubMed literature search was conducted using the keywords chronic pain combined with opioid withdrawal, taper, wean and detoxification. Six hundred ninety-five documents were identified and screened; 117 were deemed directly relevant and are included. On the base of this literature review, this article proposes evidence-based recommendations and expert-based suggestions for clinical practice. Furthermore, areas of lack of evidence are identified, providing opportunities for further research.

  1. Biorheological Model on Flow of Herschel-Bulkley Fluid through a Tapered Arterial Stenosis with Dilatation

    Directory of Open Access Journals (Sweden)

    S. Priyadharshini

    2015-01-01

    Full Text Available An analysis of blood flow through a tapered artery with stenosis and dilatation has been carried out where the blood is treated as incompressible Herschel-Bulkley fluid. A comparison between numerical values and analytical values of pressure gradient at the midpoint of stenotic region shows that the analytical expression for pressure gradient works well for the values of yield stress till 2.4. The wall shear stress and flow resistance increase significantly with axial distance and the increase is more in the case of converging tapered artery. A comparison study of velocity profiles, wall shear stress, and flow resistance for Newtonian, power law, Bingham-plastic, and Herschel-Bulkley fluids shows that the variation is greater for Herschel-Bulkley fluid than the other fluids. The obtained velocity profiles have been compared with the experimental data and it is observed that blood behaves like a Herschel-Bulkley fluid rather than power law, Bingham, and Newtonian fluids. It is observed that, in the case of a tapered stenosed tube, the streamline pattern follows a convex pattern when we move from r/R=0 to r/R=1 and it follows a concave pattern when we move from r/R=0 to r/R=-1. Further, it is of opposite behaviour in the case of a tapered dilatation tube which forms new information that is, for the first time, added to the literature.

  2. Restorasi Resin Komposit Menggunakan Pasak Tapered Self Threading Pada Molar Ketiga Kiri Mandibula

    Directory of Open Access Journals (Sweden)

    Ellen Krisanti

    2013-06-01

    Composite Resin Restoration Using Tapered Self Threading Poston Left Mandibular Third Molar. Root canal morphology of mandibular third molar has more complex variation than the other molars. In third molar, the extraction teeth are often executed; however, the third molar can be maintained in other conditions. One visit root canal treatment is a therapy option for this case. The purpose of this case report is to show the success of one visit root canal treatment in third molar with pulp necrosis by restoring the composite resin through tapered self-treading post. A 20 year-old female patient who came to the Prof Soedomo RSGM, FKG UGM complained about the pain when chewing food on her third molar and positive in percussion. The radiographs showed that there was an incomplete restoration. There was a gap between cavities with restoration. The treatment plan for this case was one visit root canal treatment and composite resin with tapered self-threading post as final restoration. From the case, it can concluded that one visit root canal treatment results in a smaller chance for microorganism recontamination than the multi-visit in order to ensure the success of the treatment. Direct composite resin restoration with tapered self-threading dowel is an alternative restoration after endodontic treatment because it works out faster and more retentive.

  3. A comparison between different propagative schemes for the simulation of tapered step index slab waveguides

    NARCIS (Netherlands)

    Haes, Jan; Baets, Roel; Weinert, C.M.; Gravert, M.; Nolting, H.P.; Andrade, M. Adelaide; Leite, A.; Bissessur, Hans K.; Davies, J.B.; Ettinger, Robert D.; Ctyroky, Jiri; Ducloux, E.; Ratovelomanana, F.; Vodjdani, N.; Helfert, Stefan; Pregla, Reinholt; Wijnands, F.H.G.M.; Hoekstra, H.J.W.M.; Krijnen, G.J.M.

    1996-01-01

    The performance and accuracy of a number of propagative algorithms are compared for the simulation of tapered high contrast step index slab waveguides. The considered methods include paraxial as well as nonparaxial formulations of optical field propagation. In particular attention is paid to the val

  4. 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...

  5. Longitudinal polarizability and enhancement factor of a tapered optical gold nanoantenna

    Science.gov (United States)

    Gazizov, A. R.; Kharintsev, S. S.; Salakhov, M. Kh

    2016-05-01

    This work focuses on the mechanism of electric field enhancement near a tapered optical antenna and the calculation of a complex field enhancement factor as a function of tip material, its curvature radius and cone angle. In this paper, an analytical model of longitudinal polarizability, taking into account retardation and dynamic polarization effects, is developed for evaluating the field enhancement factor.

  6. 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

    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...

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

    Directory of Open Access Journals (Sweden)

    José Návar

    2013-07-01

    Full Text Available Taper functions are required in modern forest management in estimation of 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 recommended taper 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. 

  8. (PECASE 08) - ION-Conducting Network Membranes Using Tapered Block Copolymers

    Science.gov (United States)

    2015-07-08

    on Google Scholar citations as of June 24, 2015 1. [17] Roy, R.; Park, J. K.; Young, W.; Mastroianni, S.; Tureau, M. S.; Epps, T. H., III...accepted Patents and Patent Applications Wei-Fan Kuan and Thomas H. Epps, III, “Tapered Block Copolymer Electrolytes.” U.S. Pat. Appl. 14592441 filed on

  9. 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

    2016-08-15

    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.

  10. 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.

  11. Effects of Self-Adjusting File, Mtwo, and ProTaper on the root canal wall

    NARCIS (Netherlands)

    Hin, E.S.; Wu, M.K.; Wesselink, P.R.; Shemesh, H.

    2013-01-01

    Introduction The purpose of this ex vivo study was to observe the incidence of cracks in root dentin after root canal preparation with hand files, self-adjusting file (SAF), ProTaper, and Mtwo. Methods One hundred extracted mandibular premolars with single canals were randomly selected. Two angulate

  12. Friction Stir Welding of Tapered Thickness Welds Using an Adjustable Pin Tool

    Science.gov (United States)

    Adams, Glynn; Venable, Richard; Lawless, Kirby

    2003-01-01

    Friction stir welding (FSW) can be used for joining weld lands that vary in thickness along the length of the weld. An adjustable pin tool mechanism can be used to accomplish this in a single-pass, full-penetration weld by providing for precise changes in the pin length relative to the shoulder face during the weld process. The difficulty with this approach is in accurately adjusting the pin length to provide a consistent penetration ligament throughout the weld. The weld technique, control system, and instrumentation must account for mechanical and thermal compliances of the tooling system to conduct tapered welds successfully. In this study, a combination of static and in-situ measurements, as well as active control, is used to locate the pin accurately and maintain the desired penetration ligament. Frictional forces at the pin/shoulder interface were a source of error that affected accurate pin position. A traditional FSW pin tool design that requires a lead angle was used to join butt weld configurations that included both constant thickness and tapered sections. The pitch axis of the tooling was fixed throughout the weld; therefore, the effective lead angle in the tapered sections was restricted to within the tolerances allowed by the pin tool design. The sensitivity of the FSW process to factors such as thickness offset, joint gap, centerline offset, and taper transition offset were also studied. The joint gap and the thickness offset demonstrated the most adverse affects on the weld quality. Two separate tooling configurations were used to conduct tapered thickness welds successfully. The weld configurations included sections in which the thickness decreased along the weld, as well as sections in which the thickness increased along the weld. The data presented here include weld metallography, strength data, and process load data.

  13. 980 nm tapered lasers with photonic crystal structure for low vertical divergence

    Science.gov (United States)

    Ma, Xiaolong; Qu, Hongwei; Zhao, Pengchao; Liu, Yun; Zheng, Wanhua

    2016-10-01

    High power tapered lasers with nearly diffraction-limited beam quality have attracted much attention in numerous applications such as nonlinear frequency conversion, optical pumping of solid-state and fiber lasers, medical treatment and others. However, the large vertical divergence of conventional tapered lasers is a disadvantage, which makes beam shaping difficult and expensive in applications. Diode lasers with photonic crystal structure can achieve a large mode size and a narrow vertical divergence. In this paper, we present tapered lasers with photonic crystal structure emitting at 980 nm. The epitaxial layer is grown using metal organic chemical vapor deposition. The device has a total cavity length of 2 mm, which consists of a 400-um long ridge-waveguide section and a 1600-um long tapered section. The taper angle is 4°. An output power of 3.3 W is achieved with a peak conversion efficiency of 35% in pulsed mode. The threshold current is 240 mA and the slope efficiency is 0.78 W/A. In continuous wave mode, the output power is 2.87 W, which is limited by a suddenly failure resulting from catastrophic optical mirror damage. The far field divergences with full width at half maximum are 12.3° in the vertical direction and 2.9° in the lateral direction at 0.5 A. At high injection level the vertical divergence doesn't exceed 16°. Beam quality factor M2 is measured based on second moment definition in CW mode. High beam quality is demonstrated by M2 value of less than 2 in both vertical and lateral directions.

  14. 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

  15. 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.

  16. Drug levels, immunogenicity and assessment of active sacroiliitis in patients with axial spondyloarthritis under biologic tapering strategy.

    Science.gov (United States)

    Almirall, Miriam; Gimeno, Ramón; Salman-Monte, Tarek Carlos; Iniesta, Silvia; Lisbona, Maria Pilar; Maymó, Joan

    2016-04-01

    The aim of the study was to assess drug levels, immunogenicity and sacroiliitis on MRI in patients with axial spondyloarthritis under biologic tapering strategy. Consecutive patients with axial spondyloarthritis who remained in low disease activity more than 1 year after dose tapering of infliximab and adalimumab were included. Plasma drug concentrations of TNF inhibitors and anti-drug antibodies were determined, and MRI of sacroiliac joints was evaluated. Of twenty patients included, eighteen had therapeutic drug levels, no patient had anti-drug antibodies, and no patient had active sacroiliitis on MRI. These data could support the biologic tapering strategy and their maintenance over time.

  17. 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...

  18. Body Image

    Science.gov (United States)

    ... About Us Contact Us Text size | Print | Body Image Developing a positive body image and a healthy mental attitude is crucial to ... on for tips to have a healthy body image. Topics About body image When you look in ...

  19. 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.

  20. 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)

    Ashraf, Fauzia; 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 ProTaper Universal rotary files caused more dentinal cracks than ProTaper Next and HyFlex CM. Instrumentation short AF reduced the risk of dentinal defects.

  1. 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.

  2. Tapered ZnO Whiskers: {hkil}-Specific Mosaic Twinning VLS Growth from a Partially Molten Bottom Source

    Directory of Open Access Journals (Sweden)

    Chen Shuei-Yuan

    2009-01-01

    Full Text Available Abstract Zn particulates overlaid with wurtzite (W-type ZnO condensates having nearly orthogonal and facets were found to self-catalyze unusual tapered W-ZnO whiskers upon isothermal atmospheric annealing, i.e., thermal oxidation, at 600 °C. Analytical electron microscopic observations indicated that such whiskers formed tapered slabs having mosaic and twinned domains. The tapered whiskers can be rationalized by an alternative vapor–liquid–solid growth, i.e., {hkil}-specific coalescence twinning growth from the ZnO condensates taking advantage of a partially molten bottom source of Zn and the adsorption of atoms at the whisker tips and ledges under the influence of capillarity effect. The tapered whiskers having strong photoluminescence at 391 nm and with a considerable flexibility could have potential applications.

  3. 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.

  4. Low threshold fiber taper coupled rare earth ion-doped chalcogenide microsphere laser

    Institute of Scientific and Technical Information of China (English)

    李超然; 戴世勋; 张勤远; 沈祥; 王训四; 张培晴; 路来伟; 吴越豪; 吕社钦

    2015-01-01

    We report the applications of a low-cost and environmentally friendly chalcogenide glass, 75GeS2-15Ga2S3-10CsI, in building active microsphere laser oscillators. A silica fiber taper is used as the coupling mechanism. With an 808-nm laser diode as a pump source, we show that a high-Q (∼6×104) laser mode could be obtained from a 75-µm diameter microsphere that is coupled with a 1.77-µm waist-diameter fiber taper. The threshold of the incident pump power is 1.39 mW, which is considerably lower than those of previously reported free-space coupled chalcogenide microsphere lasers. We also note an apparent enhancement in laser power generated from this chalcogenide microsphere laser.

  5. 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.

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

    Science.gov (United States)

    Schmidt, Slawa; Engelke, Pascal; Piglosiewicz, Björn; Esmann, Martin; Becker, Simon F; Yoo, Kyungwan; Park, Namkyoo; Lienau, Christoph; Groß, Petra

    2013-11-01

    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 light on the nanoscale.

  7. Efficient system modeling for a small animal PET scanner with tapered DOI detectors.

    Science.gov (United States)

    Zhang, Mengxi; Zhou, Jian; Yang, Yongfeng; Rodríguez-Villafuerte, Mercedes; Qi, Jinyi

    2016-01-21

    A prototype small animal positron emission tomography (PET) scanner for mouse brain imaging has been developed at UC Davis. The new scanner uses tapered detector arrays with depth of interaction (DOI) measurement. In this paper, we present an efficient system model for the tapered PET scanner using matrix factorization and a virtual scanner geometry. The factored system matrix mainly consists of two components: a sinogram blurring matrix and a geometrical matrix. The geometric matrix is based on a virtual scanner geometry. The sinogram blurring matrix is estimated by matrix factorization. We investigate the performance of different virtual scanner geometries. Both simulation study and real data experiments are performed in the fully 3D mode to study the image quality under different system models. The results indicate that the proposed matrix factorization can maintain image quality while substantially reduce the image reconstruction time and system matrix storage cost. The proposed method can be also applied to other PET scanners with DOI measurement.

  8. Dynamic response of tapered optical multimode fiber coated with carbon nanotubes for ethanol sensing application.

    Science.gov (United States)

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

    2015-05-04

    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.

  9. EVALUATION OF NO SEGMENTED TAPER MODELS TO ESTIMATE HEIGHT AND MERCHANTABLE VOLUME FROM Eucalyptus sp. STEMS

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Martinelli de Souza

    2009-10-01

    Full Text Available This work aimed to evaluate different taper models in the estimate of the merchantable height and volume and along the bole volumes of Eucalyptus sp., to the obtention of multiproducts. Considering the data of rigorous scaling of trees of Eucalyptus sp. with 16 years-old, it was appraised the models of taper of Demaerschalk (1972, Ormerod (1973, Schöepfer (1966, Hradetzky (1976, Garay (1979 and Biging (1984. Based on graphical analysis of the residues and on the statistics bias (B, average of the differences (MD and deviation pattern of the differences (DPD, it could be verified that, in the estimate of the merchantable height and volume of the models, Biging, Schöepfer and Hradetzky presented the best results, followed by the models of Garay, which have also shown good results. In general, considering the treatment of the volumes of the logs, the Biging model presented the best resuts.

  10. The application of tapered multi-mode fiber in laser signal simulation

    Science.gov (United States)

    Yin, Ruiguang; Guo, Hao; Liang, Weiwei; Zhang, Wenpan; Li, Hui

    2016-09-01

    According to laser signal simulation, the advantage of application of tapered multi-mode fiber on laser pulse signal transmission was analyzed. By optical system simulation, the effect on the coupling efficiency of 1.06μm laser pulse signal of different angle was analyzed. By optical experiment, the coupling efficiency and transmission mode of different incident angle and force condition were confirmed. Combining the application of simulation system, with convex lens, frosted glass and optical integrator on the outlet of fiber, the far-field energy distribution was measured. According the receiving optical system entrance pupil, the effect on the beam quality to the simulation result was analyzed. The results showed that the application of tapered multi-mode fiber on laser pulse signal simulation is feasible, and the equipment has been used in the engineering projects.

  11. 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.

  12. The tapered slot antenna - A new integrated element for millimeter-wave applications

    Science.gov (United States)

    Yngvesson, K. Sigfrid; Kim, Young-Sik; Korzeniowski, T. L.; Kollberg, Erik L.; Johansson, Joakim F.

    1989-01-01

    Tapered slot antennas (TSAs) with a number of potential applications as single elements and focal-plane arrays are discussed. TSAs are fabricated with photolithographic techniques and integrated in either hybrid or MMIC circuits with receiver or transmitter components. They offer considerably narrower beams than other integrated antenna elements and have high aperture efficiency and packing density as array elements. Both the circuit and radiation properties of TSAs are reviewed. Topics covered include: antenna beamwidth, directivity, and gain of single-element TSAs; their beam shape and the effect of different taper shapes; and the input impedance and the effects of using thick dielectrics. These characteristics are also given for TSA arrays, as are the circuit properties of the array elements. Different array structures and their applications are also described.

  13. 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.

  14. Single-mode tapered optical fiber loop immunosensor II: assay of anti-cholera toxin immunoglobulins

    Science.gov (United States)

    Marks, Robert S.; Hale, Zoe M.; Levine, Myron M.; Lowe, C. R.; Payne, Frank P.

    1994-07-01

    An evanescent wave immunoassay for cholera antitoxin immunoglobulins was performed using a single mode tapered optical fiber loop sensor. The transducer was silanized with 3- glycidoxypropyltrimethoxysilane and chemically modified to link covalently either cholera toxin B subunit or a synthetic peptide derived from it, CTP3. The sensor was exposed to seral fluids, obtained from human volunteers having been exposed to live virulent Vibrio cholerae 01 and shown to produce rice-water stools. Other toxins of interest, such as Clostridium botulinum toxin A, have been tested on similar systems. The bound unlabelled immunoglobulins were then exposed to a mixture of FITC-anti-IgG and TRITC-anti-IgA, without requirement for a separation step. The emanating fluorescent emissions of fluorescein and rhodamine, excited by the input laser light, were coupled back into the guided mode of the tapered fiber, and used to determine the concentrations of the complementary antigens.

  15. 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.

  16. 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.

  17. The tapered slot antenna - A new integrated element for millimeter-wave applications

    Science.gov (United States)

    Yngvesson, K. Sigfrid; Kim, Young-Sik; Korzeniowski, T. L.; Kollberg, Erik L.; Johansson, Joakim F.

    1989-02-01

    Tapered slot antennas (TSAs) with a number of potential applications as single elements and focal-plane arrays are discussed. TSAs are fabricated with photolithographic techniques and integrated in either hybrid or MMIC circuits with receiver or transmitter components. They offer considerably narrower beams than other integrated antenna elements and have high aperture efficiency and packing density as array elements. Both the circuit and radiation properties of TSAs are reviewed. Topics covered include: antenna beamwidth, directivity, and gain of single-element TSAs; their beam shape and the effect of different taper shapes; and the input impedance and the effects of using thick dielectrics. These characteristics are also given for TSA arrays, as are the circuit properties of the array elements. Different array structures and their applications are also described.

  18. 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.

  19. Large-aperture, tapered fiber-coupled, 10-kHz particle-image velocimetry.

    Science.gov (United States)

    Hsu, Paul S; Roy, Sukesh; Jiang, Naibo; Gord, James R

    2013-02-11

    We demonstrate the design and implementation of a fiber-optic beam-delivery system using a large-aperture, tapered step-index fiber for high-speed particle-image velocimetry (PIV) in turbulent combustion flows. The tapered fiber in conjunction with a diffractive-optical-element (DOE) fiber-optic coupler significantly increases the damage threshold of the fiber, enabling fiber-optic beam delivery of sufficient nanosecond, 532-nm, laser pulse energy for high-speed PIV measurements. The fiber successfully transmits 1-kHz and 10-kHz laser pulses with energies of 5.3 mJ and 2 mJ, respectively, for more than 25 min without any indication of damage. It is experimentally demonstrated that the tapered fiber possesses the high coupling efficiency (~80%) and moderate beam quality for PIV. Additionally, the nearly uniform output-beam profile exiting the fiber is ideal for PIV applications. Comparative PIV measurements are made using a conventionally (bulk-optic) delivered light sheet, and a similar order of measurement accuracy is obtained with and without fiber coupling. Effective use of fiber-coupled, 10-kHz PIV is demonstrated for instantaneous 2D velocity-field measurements in turbulent reacting flows. Proof-of-concept measurements show significant promise for the performance of fiber-coupled, high-speed PIV using a tapered optical fiber in harsh laser-diagnostic environments such as those encountered in gas-turbine test beds and the cylinder of a combustion engine.

  20. Orthogonal Control of Stability and Tunable Dry Adhesion by Tailoring the Shape of Tapered Nanopillar Arrays.

    Science.gov (United States)

    Cho, Younghyun; Kim, Gyuseok; Cho, Yigil; Lee, Su Yeon; Minsky, Helen; Turner, Kevin T; Gianola, Daniel S; Yang, Shu

    2015-12-16

    Tapered nanopillar structures of different cross-sectional geometries including cone-, pencil-like, and stepwise are prepared from anodized aluminum oxide templates. The shape effect on the adhesion strength is investigated in experiments and simulation. Cone-shaped nanopillars are highly bendable under load and can recover after unloading, thus, warranting high adhesion strength, 34 N cm(-2) . The pencil-like and stepwise nano-pillars are, however, easily fractured and are not recoverable under the same conditions.

  1. Size stabilization of surface-supported liquid aerosols using tapered optical fiber coupling

    OpenAIRE

    Karadağ, Yasin; Jonas, Alexandr; Küçükkara, İbrahim; Kiraz, Alper

    2013-01-01

    We demonstrate long-term size stabilization of surface-supported liquid aerosols of salt-water. Single tapered optical fibers were used to couple the light from independent heating and probe lasers into individual microdroplets that were kept on a superhydrophobic surface in a high-humidity chamber. Size stabilization of microdroplets resulted from competition between resonant absorption of the infrared heating laser by a microdroplet whispering gallery mode and water condensation in the samp...

  2. High-sensitivity, evanescent field refractometric sensor based on a tapered, multimode fiber interference.

    Science.gov (United States)

    Wang, Pengfei; Brambilla, Gilberto; Ding, Ming; Semenova, Yuliya; Wu, Qiang; Farrell, Gerald

    2011-06-15

    We propose and experimentally demonstrate an enhanced evanescent field fiber refractometer based on a tapered multimode fiber sandwiched between two single-mode fibers. Experiments show that this fiber sensor offers ultrahigh sensitivity [better than 1900 nm/RIU at a refractive index (RI) of 1.44] for RI measurements within the range of 1.33-1.44, in agreement with the theoretical predictions. This is the highest value reported to date (to our knowledge) in the literature.

  3. Refractive index sensor based on an abrupt taper Michelson interferometer in a single-mode fiber.

    Science.gov (United States)

    Tian, Zhaobing; Yam, Scott S-H; Loock, Hans-Peter

    2008-05-15

    A simple refractive index sensor based on a Michelson interferometer in a single-mode fiber is constructed and demonstrated. The sensor consists of a single symmetrically abrupt taper region in a short piece of single-mode fiber that is terminated by approximately 500 nm thick gold coating. The sensitivity of the new sensor is similar to that of a long-period-grating-type sensor, and its ease of fabrication offers a low-cost alternative to current sensing applications.

  4. Optical flowmeter using a modal interferometer based on a single nonadiabatic fiber taper.

    Science.gov (United States)

    Frazão, O; Caldas, P; Araújo, F M; Ferreira, L A; Santos, J L

    2007-07-15

    A novel in-fiber modal interferometer is presented that is based on a nonadiabatic biconical fused taper that couples light between the cladding and the core, combined with the Fresnel reflection at the fiber end. It is observed that the returned light from this fiber structure shows a channeled spectrum similar to that of a two-wave Michelson interferometer. The application of this device as a fiber optic flowmeter sensor is demonstrated.

  5. Four-wave mixing instabilities in tapered and photonic crystal fibers

    OpenAIRE

    Biancalana, Fabio; Skryabin, Dmitry V.; Ortigosa-Blanch, Arturo

    2002-01-01

    We present an analytical study of four-wave mixing instabilities in tapered fibers and photonic crystal fibers. Our approach avoids the use of Taylor expansion for the linear susceptibility and the slowly-varying envelope approximation. This allows us to describe the generation of sidebands strongly detuned from the pump wave with simultaneous account for the entire dispersion characteristic of a fiber, which is found to be important for describing properly the key role of the parametric inst...

  6. 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.

  7. 600 W power scalable single transverse mode tapered double-clad fiber laser.

    Science.gov (United States)

    Filippov, V; Chamorovskii, Y; Kerttula, J; Kholodkov, A; Okhotnikov, O G

    2009-02-02

    Pump propagation and absorption in active tapered double-clad fiber has been analyzed based on a ray optics approach. Optimization of the longitudinal shape, absorption and angular distribution of the pump beam allowed for power scaling of a ytterbium fiber laser up to 600 W with high beam quality (M2fiber can be avoided, resulting in high overall efficiency, in good agreement with the presented model.

  8. 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

  9. Comparison of Dentinal Crack Formation With Reciproc, Mtwo and ProTaper Root Canal Preparation Systems

    Directory of Open Access Journals (Sweden)

    Nazari Moghaddam

    2016-06-01

    Full Text Available Background Instrumentation with rotary instruments could potentially cause dentinal cracks possibly leading to tooth fracture. Reciproc files require a single file to finalize the root canal preparation and the effect of this procedure has not been compared with other systems. Objectives The aim of this study was to compare the incidence of dentinal micro-cracks following root canal preparations with ProTaper, Mtwo and Reciproc files. Materials and Methods In an experimental in vitro trial, 80 maxillary and mandibular first molars were selected and their crowns and distal roots were cut. The roots were then examined to remove any previous cracks and defects. An impression polyether material was used to simulate teeth periodontal ligament (PDL. The teeth were divided to four experimental groups (n = 20 and prepared using Reciproc, Mtwo and ProTaper or remained unprepared as a control group. The specimens were then sectioned horizontally on 3, 5 and 9 mm from the apex and number of micro-cracks was determined by stereomicroscope. The incidence of dentinal cracks on different systems or sections were statistically analyzed by means of the chi-square test. Results Dentinal defects on 3-mm, 5-mm and 9-mm sections from the apex were noted in 10 (5.6%; 7 (3.9% and 9 (5.0% samples of all, respectively. Following canal preparation using Reciproc, ProTaper and Mtwo systems, the defects were observed in 7 (3.9%, 12 (6.7% and 7 (3.9% the sections, respectively. No significant differences were observed regarding the defect incidence on the studied instrumentation files or sections. Conclusions Regarding the study limitations, dentinal cracks were observed in all files and distances from the apex. Although there was more crack incidence in ProTaper files, no significant differences were noted regarding the studied systems and sections from the apex.

  10. 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.

  11. Wizard CD Plus and ProTaper Universal: analysis of apical transportation using new software

    Directory of Open Access Journals (Sweden)

    Daiana Giannastasio

    2013-09-01

    Full Text Available OBJECTIVE: This study has two aims: 1 to evaluate the apical transportation of the Wizard CD Plus and ProTaper Universal after preparation of simulated root canals; 2 to compare, with Adobe Photoshop, the ability of a new software (Regeemy in superposing and subtracting images. MATERIAL AND METHODS: Twenty five simulated root canals in acrylic-resin blocks (with 20º curvature underwent cone beam computed tomography before and after preparation with the rotary systems (70 kVp, 4 mA, 10 s and with the 8×8 cm FoV selection. Canals were prepared up to F2 (ProTaper and 24.04 (Wizard CD Plus instruments and the working length was established to 15 mm. The tomographic images were imported into iCAT Vision software and CorelDraw for standardization. The superposition of pre- and post-instrumentation images from both systems was performed using Regeemy and Adobe Photoshop. The apical transportation was measured in millimetres using Image J. Five acrylic resin blocks were used to validate the superposition achieved by the software. Student's t-test for independent samples was used to evaluate the apical transportation achieved by the rotary systems using each software individually. Student's t-test for paired samples was used to compare the ability of each software in superposing and subtracting images from one rotary system per time. RESULTS: The values obtained with Regeemy and Adobe Photoshop were similar to rotary systems (P>0.05. ProTaper Universal and Wizard CD Plus promoted similar apical transportation regardless of the software used for image's superposition and subtraction (P>0.05. CONCLUSION: Wizard CD Plus and ProTaper Universal promoted little apical transportation. Regeemy consists in a feasible software to superpose and subtract images and appears to be an alternative to Adobe Photoshop.

  12. Stem surface roughness alters creep induced subsidence and 'taper-lock' in a cemented femoral hip prosthesis.

    Science.gov (United States)

    Norman, T L; Thyagarajan, G; Saligrama, V C; Gruen, T A; Blaha, J D

    2001-10-01

    The clinical success of polished tapered stems has been widely reported in numerous long term studies. The mechanical environment that exists for polished tapered stems, however, is not fully understood. In this investigation, a collarless, tapered femoral total hip stem with an unsupported distal tip was evaluated using a 'physiological' three-dimensional (3D) finite element analysis. It was hypothesized that stem-cement interface friction, which alters the magnitude and orientation of the cement mantle stress, would subsequently influence stem 'taper-lock' and viscoelastic relaxation of bone cement stresses. The hypothesis that creep-induced subsidence would result in increases to stem-cement normal (radial) interface stresses was also examined. Utilizing a viscoelastic material model for the bone cement in the analysis, three different stem-cement interface conditions were considered: debonded stem with zero friction coefficient (mu=0) (frictionless), debonded stem with stem-cement interface friction (mu=0.22) ('smooth' or polished) and a completely bonded stem ('rough'). Stem roughness had a profound influence on cement mantle stress, stem subsidence and cement mantle stress relaxation over the 24-h test period. The frictionless and smooth tapered stems generated compressive normal stress at the stem-cement interface creating a mechanical environment indicative of 'taper-lock'. The normal stress increased with decreasing stem-cement interface friction but decreased proximally with time and stem subsidence. Stem subsidence also increased with decreasing stem-cement interface friction. We conclude that polished stems have a greater potential to develop 'taper-lock' fixation than do rough stems. However, subsidence is not an important determinant of the maintenance of 'taper-lock'. Rather subsidence is a function of stem-cement interface friction and bone cement creep.

  13. 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....

  14. Optimum fiber tapers for increasing the power in the blue-edge of a supercontinuum - group-acceleration matching

    DEFF Research Database (Denmark)

    Sørensen, Simon Toft; Judge, Alexander; Thomsen, Carsten L.;

    2011-01-01

    and blueshifts an increased fraction of the energy in its DW when the gradient is decreased. This is quantified by the group-acceleration mismatch between the soliton and DW at the entrance of the taper. These findings have direct implications for the achievable power in the blue edge of a supercontinuum...... generated in a tapered fiber and explain observations of a lack of power in the blue edge....

  15. Cleaning capacity promoted by motor-driven or manual instrumentation using ProTaper Universal system: Histological analysis

    OpenAIRE

    Matheus Franco da Frota; Idomeo Bonetti Filho; Fábio Luiz Camargo Villela Berbert; Emilio Carlos Sponchiado; André Augusto Franco Marques; Lucas da Fonseca Roberti Garcia

    2013-01-01

    Aim: The aim of this study was to assess the cleaning capacity of the Protaper system using motor-driven or manual instrumentation. Materials and Methods: Ten mandibular molars were randomly separated into 2 groups (n = 5) according to the type of instrumentation performed, as follows: Group 1 - instrumentation with rotary nickel-titanium (Ni-Ti) files using ProTaper Universal System (Dentsply/Maillefer); and, Group 2 - instrumentation with Ni-Ti hand files using ProTaper Universal (Den...

  16. Transportation and Centering Ability of Neoniti and ProTaper Instruments; A CBCT Assessment

    Science.gov (United States)

    Madani, Zahrasadat; Soleymani, Ali; Bagheri, Tasnim; Moudi, Ehsan; Bijani, Ali; Rakhshan, Vahid

    2017-01-01

    Introduction: Transportation is an important iatrogenic endodontic error which might cause failure. This study evaluated the canal transportation caused by Neoniti and ProTaper instruments, using cone-beam computed tomography (CBCT) cross sections. Methods and Materials: This in vitro experimental study was performed on 40 mesiobuccal roots of maxillary first molars. The teeth were scanned with CBCT. They were randomly divided into 2 groups (n=20) that were prepared using either Neoniti or ProTaper files. An endodontist prepared the canal according to the manufacturer’s guidelines. Prepared canals were re-scanned. The pre-instrumentation and post-instrumentation CBCT volumes were sectioned at 1 to 9-mm distances from the apex. The extent of canal dentine removal in mesial and distal directions were measured in each cross-section. Canal transportation and instrument centering ability were estimated based on the extents of root wall removal and were compared in both groups. Results: The groups were rather similar in terms of transportation and centering ability (P>0.05). However, canal preparation on mesial and distal walls was statistically significantly less in the Neoniti group, at most cross-sections. Transportation of both groups was not significantly different (P>0.05). Centering ability of both instruments was not significantly different (P>0.05). Conclusion: Neoniti and ProTaper instruments might have proper centering ability and minimum transportations. Both instruments might cause similar extents of transportation and centering abilities. PMID:28179923

  17. 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)

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

    Science.gov (United States)

    Marschall, Sebastian; Klein, Thomas; Wieser, Wolfgang; Biedermann, Benjamin R; Hsu, Kevin; Hansen, Kim P; Sumpf, Bernd; Hasler, Karl-Heinz; Erbert, Götz; Jensen, Ole B; Pedersen, Christian; Huber, Robert; Andersen, Peter E

    2010-07-19

    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 chromatic dispersion in standard optical fiber. We developed a novel light source with a tapered amplifier as gain medium, and investigated the FDML performance comparing two fiber delay lines with different dispersion properties. We introduced an additional gain element into the resonator, and thereby 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 microm in air (approximately 11 microm 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.

  19. Statistics and frequency-domain moveout for multiple-taper receiver functions

    Science.gov (United States)

    Park, J.; Levin, V.

    2016-10-01

    The multiple-taper correlation (MTC) algorithm for the estimation of teleseismic receiver functions (RFs) has desirable statistical properties. This paper presents several adaptations to the MTC algorithm that exploit its frequency-domain uncertainty estimates to generate stable RFs that include moveout corrections for deeper interfaces. Narrow-band frequency averaging implicit in spectral cross-correlation restricts the MTC-based RF estimates to resolve Ps converted phases only at short delay times, appropriate to the upper 100 km of Earth's lithosphere. The Ps conversions from deeper interfaces can be reconstructed by the MTC algorithm in two ways. Event cross-correlation computes a cross-correlation of single-taper spectrum estimates for a cluster of events rather than for a set of eigenspectrum estimates of a single P coda. To extend the reach of the algorithm, pre-stack moveout corrections in the frequency domain preserves the formal uncertainties of the RF estimates, which are used to weight RF stacks. Moving-window migration retains the multiple-taper approach, but cross-correlates the P-polarized motion with time-delayed SH and SV motion to focus on a Ps phase of interest. The frequency-domain uncertainties of bin-averaged RFs do not translate directly into the time domain. A jackknife over data records in each bin stack offers uncertainty estimates in the time domain while preserving uncertainty weighting in the frequency-domain RF stack.

  20. 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.

  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. An experimental approach for the determination of axial and flexural wavenumbers in circular exponentially tapered bars

    Science.gov (United States)

    Kalkowski, Michał K.; Muggleton, Jen M.; Rustighi, Emiliano

    2017-03-01

    Whilst the dynamics of tapered structures have been extensively studied numerically and analytically, very few experimental results have been presented to date. The main aim of this paper is to derive and demonstrate an experimental method enabling both axial and flexural wavenumbers in exponentially tapered bars to be estimated. Our particular interest in this type of tapering is motivated by its occurrence in naturally grown structures such as tree roots, with an outlook towards remote root mapping. Decomposing a dynamic response into a sum of contributing waves, we propose a method in which two independent wavenumbers can be calculated from five equispaced measurements. The approach was demonstrated in an experiment on a freely suspended wooden specimen supported by theoretical modelling. For axial waves we used the well-established elementary rod theory, whereas for flexural waves we build a piecewise uniform model based on the Timoshenko beam theory. The estimates calculated from the experimental data were compared with the analytical and numerical results and showed good agreement. The limitations of the method include an appropriate choice of sensor spacing, the effect of sensor misalignments and the assumption of small wavenumber variation for flexural waves.

  3. The micropolar fluid model for blood flow through a tapered artery with a stenosis

    Institute of Scientific and Technical Information of China (English)

    Kh. S. Mekheimer; M. A. El Kot

    2008-01-01

    A micropolar model for axisymmetric blood flow through an axially nonsymmetreic but radially symmetric mild stenosis tapered artery is presented. To estimate the effect of the stenosis shape, a suitable geometry has been considered such that the axial shape of the stenosis can be changed easily just by varying a parameter (referred to as the shape parameter). The model is also used to study the effect of the taper angle φ. Flow parameters such as the velo-city, the resistance to flow (the resistance impedance), the wall shear stress distribution in the stenotic region and its magnitude at the maximum height of the stenosis (stenosis throat) have been computed for different values of the shape parameter n, the taper angle φ, the coupling number N and the micropolar parameter m. It is shown that the resistance to flow decreases with increasing the shape parameter n and the micropolar parameter m while it increases with increasing the coupling number N. So, the magnitude of the resistance impedance is higher for a micropolar fluid than that for a Newtonian fluid model. Finally, the velocity profile, the wall shear stress distribution in the stenotic region and its magni-tude at the maximum height of the stenosis are discussed for different values of the parameters involved on the problem.

  4. Influences of Taper Geometry Modified Oil-Grooves on Load Carrying Capacity of Crosshead Bearings

    Science.gov (United States)

    Kitahara, Tatsumi; Otsubo, Masaru; Nakahara, Daisuke

    The crosshead bearing in large two-stroke diesel engines operates under severe lubrication conditions, because the bearing oscillates within a small angle at a low speed and is always subject to a high downward load. The recent trend towards more compact engines with increased output raises the bearing specific load, thereby causing the lubrication severity to increase significantly. Thus it is very important to improve the load carrying capacity of the crosshead bearing. In the present study, experiments using a dynamically loaded bearing seizure test apparatus were carried out to clarify the influences of the clearance ratio and the oil-groove geometry on the load carrying capacity. The electrical resistance of the oil film was also measured to evaluate the extent of the oil film formation. The major results are: (1) A decrease in the clearance ratio is effective in enhancing squeeze action on the entirety of the bearing pads, thereby improving the load carrying capacity. When the clearance ratio becomes too low, however, the ability to form an adequate wedge film is degraded, causing the load carrying capacity to decrease; (2) A significant improvement in the load carrying capacity can be expected, because incorporating the taper geometry on both sides of the oil-groove promotes a thicker oil film; and (3) A taper geometry with a subtended length of 5 degrees and a taper angle of 0.1 degree produces the maximum load carrying capacity.

  5. Second-Order Nonlinear Analysis of Steel Tapered Beams Subjected to Span Loading

    Directory of Open Access Journals (Sweden)

    Ali Hadidi

    2014-03-01

    Full Text Available A second-order elastic analysis of tapered steel members with I-shaped sections subjected to span distributed and concentrated loadings is developed. Fixed end forces and moments as well as exact stiffness matrix of tapered Timoshenko-Euler beam are obtained with exact geometrical properties of sections. The simultaneous action of bending moment, shear, and axial force including P−δ effects is also considered in the analysis. A computer code has been developed in MATLAB software using a power series method to solve governing second-order differential equation of equilibrium with variable coefficients for beams with distributed span loading. A generalized matrix condensation technique is then utilized for analysis of beams with concentrated span loadings. The accuracy and efficiency of the results of the proposed method are verified through comparing them to those obtained from other approaches such as finite element methods, which indicates the robustness and time saving of this method even for large scale frames with tapered members.

  6. 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.

  7. 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.

  8. Vibration Analysis of Rotating Tapered Timoshenko Beams by a New Finite Element Model

    Directory of Open Access Journals (Sweden)

    Bulent Yardimoglu

    2006-01-01

    Full Text Available A new finite element model is developed and subsequently used for transverse vibrations of tapered Timoshenko beams with rectangular cross-section. The displacement functions of the finite element are derived from the coupled displacement field (the polynomial coefficients of transverse displacement and cross-sectional rotation are coupled through consideration of the differential equations of equilibrium approach by considering the tapering functions of breadth and depth of the beam. This procedure reduces the number of nodal variables. The new model can also be used for uniform beams. The stiffness and mass matrices of the finite element model are expressed by using the energy equations. To confirm the accuracy, efficiency, and versatility of the new model, a semi-symbolic computer program in MATLAB® is developed. As illustrative examples, the bending natural frequencies of non-rotating/rotating uniform and tapered Timoshenko beams are obtained and compared with previously published results and the results obtained from the finite element models of solids created in ABAQUS. Excellent agreement is found between the results of new finite element model and the other results.

  9. 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.

  10. Nonadiabatic tapered optical fiber sensor for measurement of antimicrobial activity of silver nanoparticles against Escherichia coli.

    Science.gov (United States)

    Zibaii, Mohammad Ismail; Latifi, Hamid; Saeedian, Zahra; Chenari, Zinab

    2014-06-05

    Silver nanoparticles (SNPs) exhibit antibacterial properties via bacterial inactivation and growth inhibition but the mechanism is not yet completely understood. In this study a label free and rapid detection method for study of antimicrobial activity of the SNP against Escherichia coli (E. coli K-12) is investigated using a nonadiabtic tapered fiber optic (NATOF) biosensor. The results show that SNPs interact with bacteria either by anchoring to or penetrating into the bacterial cell layer. These mechanism changes the refractive index (RI) of the tapered region, which in turn lead to the changes in the optical characteristics of the tapered fiber and output signals. With similar conditions for bacteria, the inhibition rate of the E. coli growth was measured by colony counting method as an experimental control and the results were compared with those obtained from the fiber sensor measurements. For SNP concentrations ranging from 0 to 50 μg ml(-1) the inhibition rates of the E. coli growth were measured to be from 1.27 h(-1) to -0.69 h(-1) and from -3.00×10(-3) h(-1) to -1.98×10(-2) h(-1) for colony counting and optical fiber biosensor, respectively. The results demonstrate the potential of the proposed NATOF biosensor as a label free and rapid sensing platform for understanding the mechanism of antibacterial effects of SNPs.

  11. 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.

  12. A piecewise continuous Timoshenko beam model for the dynamic analysis of tapered beam-like structures

    Science.gov (United States)

    Shen, Ji Yao; Abu-Saba, Elias G.; Mcginley, William M.; Sharpe, Lonnie, Jr.; Taylor, Lawrence W., Jr.

    1992-01-01

    Distributed parameter modeling offers a viable alternative to the finite element approach for modeling large flexible space structures. The introduction of the transfer matrix method into the continuum modeling process provides a very useful tool to facilitate the distributed parameter model applied to some more complex configurations. A uniform Timoshenko beam model for the estimation of the dynamic properties of beam-like structures has given comparable results. But many aeronautical and aerospace structures are comprised of non-uniform sections or sectional properties, such as aircraft wings and satellite antennas. This paper proposes a piecewise continuous Timoshenko beam model which is used for the dynamic analysis of tapered beam-like structures. A tapered beam is divided into several segments of uniform beam elements. Instead of arbitrarily assumed shape functions used in finite element analysis, the closed-form solution of the Timoshenko beam equation is used. Application of the transfer matrix method relates all the elements as a whole. By corresponding boundary conditions and compatible conditions a characteristic equation for the global tapered beam has been developed, from which natural frequencies can be derived. A computer simulation is shown in this paper, and compared with the results obtained from the finite element analysis. While piecewise continuous Timoshenko beam model decreases the number of elements significantly; comparable results to the finite element method are obtained.

  13. ProTaper和ProTaper Universal机用镍钛器械在模拟根管内成形能力的研究%Shaping Ability between ProTaper and ProTaper Universal Ni--Ti Rotary Endodontic Instruments in Simulated Root Canals.

    Institute of Scientific and Technical Information of China (English)

    张瑜; 彭彬; 任小琼

    2011-01-01

    目的:利用树脂模拟根管比较机用ProTaper和ProTaper Universal在弯曲根管内的成形能力.方法:使用机用ProTaper和ProTaper Universal预备两组模拟树脂根管,记录预备时间、树脂切割量、外形改变等,并对预备前后模拟根管形态改变、弯曲内外侧去除树脂量的多少进行分析和比较.结果:两组器械在预备时间上、器械变形方面无显著性差异,但预备后根管中下段均有部分偏移.ProTaper Universal F1、F2在弯曲内侧切割的树脂量多于ProTaper,而F3的树脂切割量少于ProTaper F3.结论:两组器械均能较好地完成根管预备,但是在预备根管中下段时,都会造成一定程度上的偏移.%Objective: To compare the shaping ability between ProTaper and ProTaper Universal instruments by preparing the simulated root canals. Methods.. Two groups resin blocks were prepared by ProTaper and ProTaper Universal, respectively. We recorded the preparation time, materials removal and changing of the root canal shape.The images before and after preparation were superimposed and analyzed by software ImagePro Plus 5.0. Results:Both instruments caused apical transportation. ProTaper Universal Fl and F2 removed more materials than ProTaper Fl and F2, however F3 removed less materials. Conclusion: Two instruments show a good performance in preparing but both create some apical transportation.

  14. The histological and elemental characterisation of corrosion particles from taper junctions

    Science.gov (United States)

    Oliver, R. A.; Zicat, B.; Walter, W. L.; Walter, W. K.; Walsh, W. R.

    2016-01-01

    Objectives This study aimed to characterise and qualitatively grade the severity of the corrosion particles released into the hip joint following taper corrosion. Methods The 26 cases examined were CoC/ABG Modular (n = 13) and ASR/SROM (n = 13). Blood serum metal ion levels were collected before and after revision surgery. The haematoxylin and eosin tissue sections were graded on the presence of fibrin exudates, necrosis, inflammatory cells and corrosion products. The corrosion products were identified based on visible observation and graded on abundance. Two independent observers blinded to the clinical patient findings scored all cases. Elemental analysis was performed on corrosion products within tissue sections. X-Ray diffraction was used to identify crystalline structures present in taper debris. Results The CoC/ABG Modular patients had a mean age of 64.6 years (49.4 to 76.5) and ASR/SROM patients had a mean age of 58.2 years (33.3 to 85.6). The mean time in situ for CoC/ABG was 4.9 years (2 to 6.4) and ASR/SROM was 6.1 years (2.5 to 8.1). The blood serum metal ion concentrations reduced following revision surgery with the exception of Cr levels within CoC/ABG. The grading of tissue sections showed that the macrophage response and metal debris were significantly higher for the ASR/SROM patients (p < 0.001). The brown/red particles were significantly higher for ASR/SROM (p < 0.001). The taper debris contained traces of titanium oxide, chromium oxide and aluminium nitride. Conclusion This study characterised and qualitatively graded the severity of the corrosion particles released into the hip joint from tapers that had corrosion damage. Cite this article: S. Munir, R. A. Oliver, B. Zicat, W. L. Walter, W. K. Walter, W. R. Walsh. The histological and elemental characterisation of corrosion particles from taper junctions. Bone Joint Res 2016;5:370–378. DOI: 10.1302/2046-3758.59.2000507. PMID:27608650

  15. Influence of NiTi alloy on the root canal shaping capabilities of the ProTaper Universal and ProTaper Gold rotary instrument systems

    Directory of Open Access Journals (Sweden)

    Jussaro Alves DUQUE

    Full Text Available Abstract Objective This study aimed to evaluate the influence of the NiTi wire in Conventional NiTi (ProTaper Universal PTU and Controlled Memory NiTi (ProTaper Gold PTG instrument systems on the quality of root canal preparation. Material and Methods Twelve mandibular molars with separate mesial canals were scanned using a high-definition microcomputed tomography system. The PTU and PTG instruments were used to shape twelve mesial canals each. The canals were scanned after preparation with F2 and F3 instruments of the PTU and PTG systems. The analyzed parameters included the remaining dentin thickness at the apical and cervical levels, root canal volume and untouched canal walls. Data was analyzed for statistical significance by the Friedman and Dunn’s tests. For the comparison of data between groups, the Mann-Whitney test was used. Results In the pre-operative analysis, there were no statistically significant differences between the groups in terms of the area and volume of root canals (P>.05. There was also no statistically significant difference between the systems with respect to root canal volume after use of the F2 and F3 instruments. There was no statistical difference in the dentin thickness at the first apical level between, before and after instrumentation for both systems. At the 3 cervical levels, the PTG maintained centralization of the preparation on the transition between the F2 and F3 instruments, which did not occur with the PTU. Conclusion The Conventional NiTi (PTU and Controlled Memory NiTi (PTG instruments displayed comparable capabilities for shaping the straight mesial root canals of mandibular molars, although the PTG was better than the PTU at maintaining the centralization of the shape in the cervical portion.

  16. Cyclic fatigue resistance, torsional resistance, and metallurgical characteristics of V taper 2 and V taper 2H rotary NiTi files.

    Science.gov (United States)

    Chang, S W; Shim, K S; Kim, Y C; Jee, K K; Zhu, Q; Perinpanayagam, H; Kum, K Y

    2016-11-01

    The aim of this study was to compare the cyclic fatigue resistance, torsional resistance, and metallurgical characteristics of conventional NiTi wire (V taper 2, V2) and CM wire (V taper 2H, V2H)-based files. Cyclic fatigue and torsional resistance of V2 and V2H were investigated by measuring the number of cycles to fracture, maximum torque at fracture, and maximum angle at fracture. The typical patterns of fatigue and torsional fractures were investigated using a scanning electron microscope (SEM). The metallurgical characteristics were investigated by differential scanning calorimetry (DSC) from -100 °C to 100 °C. The austenite finishing temperature (Af) of each instrument was also measured. The microstructures of the instruments were investigated by a transmission electron microscope (TEM) along with selected area diffraction pattern analysis. The results were statistically analyzed by Mann-Whitney U-test (p = 0.05). V2H showed significantly higher cyclic fatigue resistance and torsional resistance than V2. SEM images of the fractured surfaces showed typical patterns of fatigue and torsional fracture. The DSC analysis of V2 showed one small peak in both the heating and cooling curves. The Af of V2 was -0.32 °C. V2H showed two remarkable peaks in the heating curve and one remarkable peak in the cooling curve. The Af of V2H was 33.25 °C. The TEM analysis showed that both V2 and V2H are mainly composed of austenite. In conclusion, V2H showed higher cyclic fatigue resistance and torsional resistance than V2. The superior properties of V2H could be attributed to the annealing effect and possibly the martensite phase. SCANNING 38:564-570, 2016. © 2016 Wiley Periodicals, Inc.

  17. Influence of NiTi alloy on the root canal shaping capabilities of the ProTaper Universal and ProTaper Gold rotary instrument systems

    Science.gov (United States)

    DUQUE, Jussaro Alves; VIVAN, Rodrigo Ricci; CAVENAGO, Bruno Cavalini; AMOROSO-SILVA, Pablo Andrés; BERNARDES, Ricardo Affonso; de VASCONCELOS, Bruno Carvalho; DUARTE, Marco Antonio Hungaro

    2017-01-01

    Abstract Objective This study aimed to evaluate the influence of the NiTi wire in Conventional NiTi (ProTaper Universal PTU) and Controlled Memory NiTi (ProTaper Gold PTG) instrument systems on the quality of root canal preparation. Material and Methods Twelve mandibular molars with separate mesial canals were scanned using a high-definition microcomputed tomography system. The PTU and PTG instruments were used to shape twelve mesial canals each. The canals were scanned after preparation with F2 and F3 instruments of the PTU and PTG systems. The analyzed parameters included the remaining dentin thickness at the apical and cervical levels, root canal volume and untouched canal walls. Data was analyzed for statistical significance by the Friedman and Dunn’s tests. For the comparison of data between groups, the Mann-Whitney test was used. Results In the pre-operative analysis, there were no statistically significant differences between the groups in terms of the area and volume of root canals (P>.05). There was also no statistically significant difference between the systems with respect to root canal volume after use of the F2 and F3 instruments. There was no statistical difference in the dentin thickness at the first apical level between, before and after instrumentation for both systems. At the 3 cervical levels, the PTG maintained centralization of the preparation on the transition between the F2 and F3 instruments, which did not occur with the PTU. Conclusion The Conventional NiTi (PTU) and Controlled Memory NiTi (PTG) instruments displayed comparable capabilities for shaping the straight mesial root canals of mandibular molars, although the PTG was better than the PTU at maintaining the centralization of the shape in the cervical portion. PMID:28198973

  18. Influence of short rear end tapers on the wake of a simplified square-back vehicle: wake topology and rear drag

    Science.gov (United States)

    Perry, Anna-Kristina; Pavia, Giancarlo; Passmore, Martin

    2016-11-01

    As vehicle manufacturers work to reduce energy consumption of all types of vehicles, external vehicle aerodynamics has become increasingly important. Whilst production vehicle shape optimisation methods are well developed, the need to make further advances requires deeper understanding of the highly three-dimensional flow around bluff bodies. In this paper, the wake flow of a generic bluff body, the Windsor body, based on a square-back car geometry, was investigated by means of balance measurements, surface pressure measurements and 2D particle image velocimetry planes. Changes in the wake topology are triggered by the application of short tapers (4 % of the model length) to the top and bottom edges of the base, representing a shape optimisation that is realistic for many modern production vehicles. The base drag is calculated and correlated with the aerodynamic drag data. The results not only show the effectiveness of such small devices in modifying the time average topology of the wake but also shed some light on the effects produced by different levels of upwash and downwash on the bi-stable nature of the wake itself.

  19. Comparison of Pressure Changes by Head and Neck Position between High-Volume Low-Pressure and Taper-Shaped Cuffs: A Randomized Controlled Trial

    Directory of Open Access Journals (Sweden)

    Nobuyasu Komasawa

    2015-01-01

    Full Text Available The present study compared changes in cuff pressure by head and neck position between high-volume low-pressure (HVLP and taper-shaped (taper cuffs in a prospective randomized clinical trial. Methods. Forty patients were intubated using tracheal tubes with either HVLP (n=20; HVLP group or taper-shaped (n=20; Taper group cuffs. Initial cuff pressure was adjusted to 15, 20, or 25 cmH2O in the neutral position. Cuff pressure was evaluated after changing the head and neck positions to flexion, extension, and rotation. Results. Cuff pressure significantly increased with flexion in both HVLP and Taper groups at all initial cuff pressures. It significantly increased with extension in the HVLP group, but not in the Taper group. Cuff pressure did not significantly differ with rotation in either group and was significantly smaller in the Taper group during flexion and extension than in the HVLP group, regardless of initial cuff pressure. Conclusion. Cuff pressure changes with head and neck flexion and extension were smaller in the Taper group than in the HVLP group. Our results highlight the potential for taper cuffs to prevent excessive cuff pressure increases with positional changes in the head and neck. This trial is registered with UMIN000016119.

  20. Comparison of Pressure Changes by Head and Neck Position between High-Volume Low-Pressure and Taper-Shaped Cuffs: A Randomized Controlled Trial.

    Science.gov (United States)

    Komasawa, Nobuyasu; Mihara, Ryosuke; Imagawa, Kentaro; Hattori, Kazuo; Minami, Toshiaki

    2015-01-01

    The present study compared changes in cuff pressure by head and neck position between high-volume low-pressure (HVLP) and taper-shaped (taper) cuffs in a prospective randomized clinical trial. Methods. Forty patients were intubated using tracheal tubes with either HVLP (n = 20; HVLP group) or taper-shaped (n = 20; Taper group) cuffs. Initial cuff pressure was adjusted to 15, 20, or 25 cmH2O in the neutral position. Cuff pressure was evaluated after changing the head and neck positions to flexion, extension, and rotation. Results. Cuff pressure significantly increased with flexion in both HVLP and Taper groups at all initial cuff pressures. It significantly increased with extension in the HVLP group, but not in the Taper group. Cuff pressure did not significantly differ with rotation in either group and was significantly smaller in the Taper group during flexion and extension than in the HVLP group, regardless of initial cuff pressure. Conclusion. Cuff pressure changes with head and neck flexion and extension were smaller in the Taper group than in the HVLP group. Our results highlight the potential for taper cuffs to prevent excessive cuff pressure increases with positional changes in the head and neck. This trial is registered with UMIN000016119.

  1. 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.

  2. Fitting and Calibrating a Multilevel Mixed-Effects Stem Taper Model for Maritime Pine in NW Spain

    Science.gov (United States)

    Arias-Rodil, Manuel; Castedo-Dorado, Fernando; Cámara-Obregón, Asunción; Diéguez-Aranda, Ulises

    2015-01-01

    Stem taper data are usually hierarchical (several measurements per tree, and several trees per plot), making application of a multilevel mixed-effects modelling approach essential. However, correlation between trees in the same plot/stand has often been ignored in previous studies. Fitting and calibration of a variable-exponent stem taper function were conducted using data from 420 trees felled in even-aged maritime pine (Pinus pinaster Ait.) stands in NW Spain. In the fitting step, the tree level explained much more variability than the plot level, and therefore calibration at plot level was omitted. Several stem heights were evaluated for measurement of the additional diameter needed for calibration at tree level. Calibration with an additional diameter measured at between 40 and 60% of total tree height showed the greatest improvement in volume and diameter predictions. If additional diameter measurement is not available, the fixed-effects model fitted by the ordinary least squares technique should be used. Finally, we also evaluated how the expansion of parameters with random effects affects the stem taper prediction, as we consider this a key question when applying the mixed-effects modelling approach to taper equations. The results showed that correlation between random effects should be taken into account when assessing the influence of random effects in stem taper prediction. PMID:26630156

  3. 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.

  4. The effect of preparation height and taper on cement lute stress: a three-dimensional finite element analysis.

    Science.gov (United States)

    Jacobsen, P H; Wakefieldt, A J; O'Doherty, D M; Rees, J S

    2006-12-01

    Three dimensional finite element models of an upper second premolar and molar with full veneer gold crown preparations were developed from extracted samples. The cement lute width was kept constant at 40 microm, but the height and preparation taper were varied. For both models the preparation height was either 1.5 mm (short preparation) or 3 mm (long preparation). The preparation taper was either 10 degree or 30 degree, giving a total of eight models. Each model was loaded with a 10 N horizontal load, a 10 N vertical load or a 10 N load distributed across the occlusal surface. The maximum shear stress and the maximum Von Mises' stress in the cement lute of each model were recorded. For the premolar, the maximum shear stresses ranged from 0.3-5.43 MPa and the maximum Von Mises' stress ranged from 1.44-14.98 MPa. For the molar, the maximum shear stresses ranged from 0.15-5.22 MPa and the maximum Von Mises' stress ranged from 0.3 7-15.02 MPa. The stress fields were consistently higher in the premolar with a 30 degree preparation taper compared to the 10 degree taper. The attainment of a cavity taper of 100 is still important to minimise stress in the cement lute and is particularly important in teeth with a lower preparation surface area such as a premolar

  5. Analysis and design of the taper in metal-grating periodic slow-wave structures for rectangular Cerenkov masers

    Institute of Scientific and Technical Information of China (English)

    Chen Ye; Zhao Ding; Wang Yong; Shu Wen

    2012-01-01

    The hybrid-mode dispersion equation of the metal-grating periodic slow-wave structure for a rectangular Cerenkov maser is derived by using the Borgnis function and field-matching methods.An equivalent-circuit model for the taper of the groove depth that matches the smooth waveguide to the metal-grating structure is proposed.By using the equivalentcircuit method,as well as the Ansoft high frequency structure simulator(HFSS)code,an appropriate electromagnetic mode for beam-wave interaction is selected and the equivalent-circuit analysis on the taper is given.The calculated results show that a cumulative reflection coefficient of 0.025 for the beam-wave interaction structure at a working frequency of 78.1 GHz can be reached by designing the exponential taper with a TEz10 rectangular waveguide mode as the input and the desired TEχ10 mode as the output.It is worth pointing out that by using the equivalent-circuit method,the complex field-matching problems from the traditional field-theory method for taper design can be avoided,so the taper analysis process is markedly simplified.

  6. Acrylic-based 1×2 Y-Branch POF coupler with high index contrast waveguide taper

    Science.gov (United States)

    Ehsan, A. A.; Abd Rahman, M. K.

    2011-01-01

    An acrylic-based 1x2 Y-Branch POF coupler consists of input POF waveguide, a middle high index contrast waveguide taper and output POF waveguides has been developed. The optical device is based on a 1x2 Y-branch coupler design with a middle high index contrast waveguide taper. Device modeling has been performed using non-sequential ray tracing with an insertion loss of 4.68 dB and coupling ratio of 50:50. Low cost acrylic material has been used for the device substrate. This middle waveguide taper region is constructed on the acrylic block itself without using any additional optical waveguiding medium injected into the engraved taper region. Fabrication of the devices is done by producing the device structures on an acrylic block using high speed CNC machining tool. Input and output POF fibers are inserted in to this device structure in such a way that they are passively aligned to the middle waveguide taper structure. The measured insertion loss is 7.5 dB and with a splitting ratio of 50:50.

  7. Stress distribution of new generation of Twisted Files in comparison with ProTaper: A finite element analysis

    Directory of Open Access Journals (Sweden)

    Harsha Pujari

    2013-01-01

    Full Text Available Aim: To compare and evaluate the stress distribution of new generation of Twisted File in comparison with ProTaper under bending or torsional conditions using a finite - element analysis model. Materials and Methods: Two NiTi files, a ProTaper file and the latest generation nickel titanium file which is the Twisted File of similar tip diameter were scanned using White light scanning system. Through this a real size digitized models of the two brands of NiTi instruments were obtained. Then, the outline of the instrument was extracted from the stacks of 3D data in software. Finally a mesh of linear, eight-noded, hexahedral elements was overlaid onto the rendered 3D image. The behavior of the instrument under bending or torsional loads was then analyzed mathematically in the software (ABAQUS V6, 5-1 taking into consideration the non linear mechanical characteristic of NiTi material. The results were expressed as von Mises stresses and were calculated by the von Mises criteria. Results: Higher stress values were seen in Twisted Files than the ProTaper universal, however, the angular deflection was seen to be more in Twisted Files. Conclusion: As more angular deflection was seen in Twisted File it was more flexible than ProTaper Universal but did not have the uniform stress distribution like the ProTaper universal.

  8. 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.

  9. High Efficiency Energy Extraction from a Relativistic Electron Beam in a Strongly Tapered Undulator

    Science.gov (United States)

    Sudar, N.; Musumeci, P.; Duris, J.; Gadjev, I.; Polyanskiy, M.; Pogorelsky, I.; Fedurin, M.; Swinson, C.; Kusche, K.; Babzien, M.; Gover, A.

    2016-10-01

    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, supported by simulations of the radiation field evolution, 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.

  10. 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.

  11. Amplitude Tapers for Planar Arrays Using the McClellan Transformation: Concepts and Preliminary Design Experiments

    Science.gov (United States)

    2010-04-29

    transformation: a phase-only prototype transforms to a two-dimensional taper that lacks the phase-only property. A straightforward IEEE Xplore subject search...A 2-D FIR filter structure derived from the Chebyshev recursion,” IEEE Trans. Circuits and Systems, vol. 24, no. 7, pp. 372–378, July 1977. [Online...transformations for two-dimensional digital filtering—Part I: Design,” IEEE Trans. Circuits and Systems, 3It is odd to associate the term “recursion” with FIR

  12. Beaming of helical light from plasmonic vortices via adiabatically tapered nanotip

    CERN Document Server

    Garoli, Denis; Gorodetski, Yuri; Tantussi, Francesco; De Angelis, Francesco

    2016-01-01

    We demonstrate the generation of far-field propagating optical beams with a desired orbital angular momentum by using a smooth optical mode transformation between a plasmonic vortex and free space Laguerre-Gaussian modes. This is obtained by means of an adiabatically tapered gold tip surrounded by a spiral slit. The proposed physical model, backed up by the numerical study, brings about an optimized structure which is fabricated by using highly reproducible secondary electron lithography technique. Optical measurements of the structure excellently agree with the theoretically predicted far-field distributions. This architecture provides a unique platform for a localized excitation of plasmonic vortices followed by its beaming.

  13. Automated quantification of bronchiectasis, airway wall thickening and lumen tapering in chest CT

    DEFF Research Database (Denmark)

    Perez-Rovira, Adria; Kuo, Wieying; Petersen, Jens

    were obtained using a fully automatic, in-house developed, segmentation method. Subsequently, for each detected airway branch, the Airway-Artery Ratio (AAR, ratio between airway outer wall and accompanying artery radius, a bronchiectasis measurement), Wall-Artery Ratio (WAR, ratio between airway wall...... thickness and accompanying artery radius), and inter-branch Lumen-Ratio (LR, ratio between a branch's lumen and its parent branch lumen radius, a tapering measurement) were computed. Because CF-related structural abnormalities only affect a portion of branches, the 75th percentile was used as summarising...

  14. 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...... 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...

  15. 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.

  16. Influence of a thin metal layer on a beam propagation in a biconical optical fibre taper

    Science.gov (United States)

    Stasiewicz, K. A.; Moś, J. E.

    2016-12-01

    The paper presents results of a simulation of the plasmon effect achieved between a thin precious metal layer and a biconical optical fibre taper, manufactured on a standard single mode fibre. Gold, silver and titanium were used as a metal which fulfilled a cladding function for a small diameter structure. For simulation Mode Solution software was used on which modal and frequency analyses of a wavelength were provided in the range of 800-1700 nm. A displacement of a plasmon pick in dependence of thickness of a deposited precious layer for the highest plasmon effects was observed.

  17. 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

  18. Blood flow of Jeffrey fluid in a catherized tapered artery with the suspension of nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ellahi, R., E-mail: rellahi@engr.ucr.edu [Department of Mechanical Engineering, University of California Riverside (United States); Department of Mathematics and Statistics, FBAS, IIU, Islamabad (Pakistan); Rahman, S.U. [Department of Mathematics and Statistics, FBAS, IIU, Islamabad (Pakistan); Nadeem, S. [Department of Mathematics, Quaid-i-Azam University Islamabad (Pakistan)

    2014-08-14

    Current letter deals with the mathematical models of Jeffrey fluid via nanoparticles in the tapered stenosed atherosclerotic arteries. The convection effects of heat transfer with catheter are also taken into account. The nonlinear coupled equations of nanofluid model are simplified under mild stenosis. The solutions for concentration and temperature are found by using homotopy perturbation method, whereas for velocity profile the exact solution is calculated. Moreover, the expressions for flow impedance and pressure rise are computed and discussed through graphs for different physical quantities of interest. The streamlines have also been presented to discuss the trapping bolus discipline.

  19. Blood flow of Jeffrey fluid in a catherized tapered artery with the suspension of nanoparticles

    Science.gov (United States)

    Ellahi, R.; Rahman, S. U.; Nadeem, S.

    2014-08-01

    Current letter deals with the mathematical models of Jeffrey fluid via nanoparticles in the tapered stenosed atherosclerotic arteries. The convection effects of heat transfer with catheter are also taken into account. The nonlinear coupled equations of nanofluid model are simplified under mild stenosis. The solutions for concentration and temperature are found by using homotopy perturbation method, whereas for velocity profile the exact solution is calculated. Moreover, the expressions for flow impedance and pressure rise are computed and discussed through graphs for different physical quantities of interest. The streamlines have also been presented to discuss the trapping bolus discipline.

  20. Geometric wakefield regimes study of a rectangular tapered collimator for ATF2

    CERN Document Server

    Fuster-Martinez, Nuria; Latina, Andrea; Snuverink, Jochem

    2016-01-01

    In this paper we study the discrepancy found between the wakefield impact effect induced by a rectangular tapered collimator prototype for ATF2 calculated using analytical models, calculated from CST PS numerical simulations and implemented in the tracking code PLACET v1.0.0. In order to get consistent results between the analytical calculations, CST PS simulations and the tracking code PLACET v1.0.0 the collimator wakefield module in PLACET v1.0.0 has to be modified. The changes have been implemented in the tracking code PLACET v1.0.1.

  1. A Broadband and High Gain Tapered Slot Antenna for W-Band Imaging Array Applications

    Directory of Open Access Journals (Sweden)

    Dong Sik Woo

    2014-01-01

    Full Text Available A broadband and high gain tapered slot antenna (TSA by utilizing a broadband microstrip- (MS- to-coplanar stripline (CPS balun has been developed for millimeter-wave imaging systems and sensors. This antenna exhibits ultrawideband performance for frequency ranges from 70 to over 110 GHz with the high antenna gain, low sidelobe levels, and narrow beamwidth. The validity of this antenna as imaging arrays is also demonstrated by analyzing mutual couplings and 4-element linear array. This antenna can be applied to mm-wave phased array, imaging array for plasma diagnostics applications.

  2. Linearly Tapered Slot Antenna Radiation Characteristics at Millimeter-Wave Frequencies

    Science.gov (United States)

    Simons, Rainee N.; Lee, Richard Q.

    1998-01-01

    An endfire travelling wave antenna, such as, a linearly tapered slot antenna (LTSA) is a viable alternative to a patch antenna at millimeter-wave frequencies because of its simple design and ease of fabrication. This paper presents the radiation characteristics of LTSA at higher millimeter-wave frequencies. The measured radiation patterns are observed to be well behaved and symmetric with the main beam in the endfire direction. The measured gain is about 10 dB. The LTSAs have potential wireless applications at 50 GHz, 77 GHz, and 94 GHz.

  3. Morse taper implants at different bone levels: a finite element analysis of stress distribution

    OpenAIRE

    Toniollo, Marcelo Bighetti; Macedo, Ana Paula; Palhares, Daniel; Calefi, Paulo Linares; Sorgini, Danilo Balero; Mattos, Maria da Gloria Chiarello de

    2012-01-01

    AIM: To explore the biomechanical effects of the different implantation bone levels of Morse taper implants, employing a finite element analysis (FEA). METHODS: Dental implants (TitamaxCM) with 4x13 mm and 4x11 mm, and their respective abutments with 3.5 mm height, simulating a screwed premolar metal-ceramic crown, had their design performed using the software AnsysWorkbench 10.0. They were positioned in bone blocks, covered by 2.5 mm thickness of mucosa. The cortical bone was designed with 1...

  4. 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.

  5. Forced Response of Polar Orthotropic Tapered Circular Plates Resting on Elastic Foundation

    Directory of Open Access Journals (Sweden)

    A. H. Ansari

    2016-01-01

    Full Text Available Forced axisymmetric response of polar orthotropic circular plates of linearly varying thickness resting on Winkler type of elastic foundation has been studied on the basis of classical plate theory. An approximate solution of problem has been obtained by Rayleigh Ritz method, which employs functions based upon the static deflection of polar orthotropic circular plates. The effect of transverse loadings has been studied for orthotropic circular plate resting on elastic foundation. The transverse deflections and bending moments are presented for various values of taper parameter, rigidity ratio, foundation parameter, and flexibility parameter under different types of loadings. A comparison of results with those available in literature shows an excellent agreement.

  6. 16 W output power by high-efficient spectral beam combining of DBR-tapered diode lasers.

    Science.gov (United States)

    Müller, André; Vijayakumar, Deepak; Jensen, Ole Bjarlin; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E; Petersen, Paul Michael

    2011-01-17

    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 3.3 (slow axis) match the M2-values of the laser with lowest spatial coherence. The principle of 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.

  7. Reactant gas transport and cell performance of proton exchange membrane fuel cells with tapered flow field design

    Energy Technology Data Exchange (ETDEWEB)

    Liu, H.C.; Yan, W.M. [Department of Mechatronic Engineering, Huafan University, Shih-Ting, Taipei 223, Taiwan (ROC); Soong, C.Y. [Department of Aerospace and Systems Engineering, Feng Chia University, Seatwen, Taichung 407, Taiwan (ROC); Chen, Falin [Institute of Applied Mechanics, National Taiwan University, Taipei 106, Taiwan (ROC); Chu, H.S. [Department of Mechanical Engineering, National Chiao-Tung University, Hsinchu 300, Taiwan (ROC)

    2006-07-14

    The objective of this work is to examine the reactant gas transport and the cell performance of a proton exchange membrane fuel cell (PEMFC) with a tapered flow channel design. It is expected that, with the reduction in the channel depth along the streamwise direction, the reactant fuel gas in the tapered channel can be accelerated as well as forced into the gas diffuser layer to enhance the electrochemical reaction and thus augment the cell performance. The effects of liquid water formation on the reactant gas transport are taken into account in the present study. Numerical predictions show that the cell performance can be enhanced with the fuel channel tapered, and the enhancement is more noticeable at a lower voltage. The results also reveal that the liquid water effect in general influences the cell performance and the effect becomes significant at lower voltages. (author)

  8. Reactant gas transport and cell performance of proton exchange membrane fuel cells with tapered flow field design

    Science.gov (United States)

    Liu, H. C.; Yan, W. M.; Soong, C. Y.; Chen, Falin; Chu, H. S.

    The objective of this work is to examine the reactant gas transport and the cell performance of a proton exchange membrane fuel cell (PEMFC) with a tapered flow channel design. It is expected that, with the reduction in the channel depth along the streamwise direction, the reactant fuel gas in the tapered channel can be accelerated as well as forced into the gas diffuser layer to enhance the electrochemical reaction and thus augment the cell performance. The effects of liquid water formation on the reactant gas transport are taken into account in the present study. Numerical predictions show that the cell performance can be enhanced with the fuel channel tapered, and the enhancement is more noticeable at a lower voltage. The results also reveal that the liquid water effect in general influences the cell performance and the effect becomes significant at lower voltages.

  9. 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

    In order to achieve durability of flat roofs with external insulation, it is necessary to secure proper drainage of the roof, i.e. to avoid water leaking into the insulation. The design of the tapered insulation of the roof is quite difficult as requirements with respect to both drainage...... and insulation has to be fulfilled. Based on a given design of the tapered insulation the total heat loss coefficient of the roof can be calculated using formulae in EN ISO 6946 for typical segments of the tapered insulation. Performing design and calculations for large roofs with numerous different segments can...... 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...

  10. Temperature-independent strain sensor based on a tapered Bragg fibre fabricated using a CO2 laser

    Science.gov (United States)

    Martins, T. J. M.; Marques, M. B.; Roy, P.; Jamier, R.; Février, S.; Frazão, O.

    2016-05-01

    Temperature-independent strain measurement is achieved resorting to a taper fabricated on a Bragg fibre using a CO2 laser. The characteristic bimodal interference of an untapered Bragg fibre is rendered multimode after taper fabrication and the resulting transmission spectra are analysed as temperature and strain change. The intrinsic strain sensitivity exhibited by the Bragg fibre is increased 15 fold after tapering and reaches 22.68 pm/μepsilon. The difference in wavelength shift promoted by variations in temperature and strain for the two fringes studied is examined and strain sensing with little temperature sensitivity is achieved, presenting a sensitivity of 2.86 pm/μepsilon, for strain values up to 400 μepsilon.

  11. 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......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...... of 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....

  12. Modal demultiplexing properties of tapered and nanostructured optical fibers for in vivo optogenetic control of neural activity.

    Science.gov (United States)

    Pisanello, Marco; Della Patria, Andrea; Sileo, Leonardo; Sabatini, Bernardo L; De Vittorio, Massimo; Pisanello, Ferruccio

    2015-10-01

    Optogenetic approaches to manipulate neural activity have revolutionized the ability of neuroscientists to uncover the functional connectivity underlying brain function. At the same time, the increasing complexity of in vivo optogenetic experiments has increased the demand for new techniques to precisely deliver light into the brain, in particular to illuminate selected portions of the neural tissue. Tapered and nanopatterned gold-coated optical fibers were recently proposed as minimally invasive multipoint light delivery devices, allowing for site-selective optogenetic stimulation in the mammalian brain [Pisanello , Neuron82, 1245 (2014)]. Here we demonstrate that the working principle behind these devices is based on the mode-selective photonic properties of the fiber taper. Using analytical and ray tracing models we model the finite conductance of the metal coating, and show that single or multiple optical windows located at specific taper sections can outcouple only specific subsets of guided modes injected into the fiber.

  13. 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.

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

    Directory of Open Access Journals (Sweden)

    Xiaolu Tang

    Full Text Available 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.

  15. Computational fluid dynamics evaluation of incomplete stent apposition in a tapered artery

    Science.gov (United States)

    Poon, Eric; Thondapu, Vikas; Ooi, Andrew; Hayat, Umair; Barlis, Peter; Moore, Stephen

    2015-11-01

    Coronary stents are deployed to prop open blocked arteries and restore normal blood flow, however in-stent restenosis (ISR) and stent thrombosis (ST) remain possibly catastrophic complications. Computational fluid dynamics (CFD) analyses can elucidate the pathological impact of alterations in coronary hemodynamics and correlate wall shear stress (WSS) with atherosclerotic processes. The natural tapering of a coronary artery often leads to proximal incomplete stent apposition (ISA) where stent struts are not in contact with the vessel wall. By employing state-of-the-art computer-aided design (CAD) software, generic open-cell and closed-cell coronary stent designs were virtually deployed in an idealised tapered coronary artery. Pulsatile blood flow (80 mL/min at 75 beats/min) was carried out numerically on these CAD models using a finite volume solver. CFD results reveal significant fluctuations in proximal WSS and large recirculation regions in the setting of proximal ISA, resulting in regions of high wall shear stress gradient (WSSG) that have been previously linked to poor endothelial cell coverage and vascular injury. The clinical significance of these proximal high WSSG regions will be correlated with findings from high-resolution in-vivo imaging. Supported by the Australian Research Council (LP120100233) and Victorian Life Sciences Computation Initiative (VR0210).

  16. Robust nonsticky superhydrophobicity by the tapering of aligned ZnO nanorods.

    Science.gov (United States)

    Tian, Jian; Zhang, Yaping; Zhu, Jie; Yang, Zhongzhen; Gao, Xuefeng

    2014-04-04

    The robust nonsticky superhydrophobicity of aligned nanoneedle films is reported. A facile, efficient, cheap, and available method based on the diffusion-limited crystal growth principle is proposed for controlling the tapering of ZnO nanorods, the profiles of which can be tuned effectively by synergetic control over reaction time and temperature in an extremely strong alkaline reaction system. The synthesized nanoneedle, nanopencil, and nanorod arrays are chosen for studying the effects of nanoscale topography on anti-droplet-sticking ability. After silanization, all of them show excellent quasi-static anti-droplet-stickiness, and water adhesion along the normal and lateral directions can be greatly reduced by the tapering of nanorods and eliminated by sharp nanoneedles. However, their antisticking stability is distinct under the droplet impact: the nanoneedle sample is still nonsticky but the nanorod sample loses its antisticking ability. Only ensuring the liquid/air interface is in the suspended nonwetting state is insufficient to obtain robust nonsticky surfaces, which also require extremely low solid-liquid van der Waals attraction.

  17. Biconically Tapered Fiber Optic Probes for Rapid Label-Free Immunoassays

    Directory of Open Access Journals (Sweden)

    John Miller

    2015-04-01

    Full Text Available We report use of U-shaped biconically tapered optical fibers (BTOF as probes for label-free immunoassays. The tapered regions of the sensors were functionalized by immobilization of immunoglobulin-G (Ig-G and tested for detection of anti-IgG at concentrations of 50 ng/mL to 50 µg/mL. Antibody-antigen reaction creates a biological nanolayer modifying the waveguide structure leading to a change in the sensor signal, which allows real-time monitoring. The kinetics of the antibody (mouse Ig-G-antigen (rabbit anti-mouse IgG reactions was studied. Hydrofluoric acid treatment makes the sensitive region thinner to enhance sensitivity, which we confirmed by experiments and simulations. The limit of detection for the sensor was estimated to be less than 50 ng/mL. Utilization of the rate of the sensor peak shift within the first few minutes of the antibody-antigen reaction is proposed as a rapid protein detection method.

  18. Precise control of the optical microfiber tapering process based on monitoring of intermodal interference.

    Science.gov (United States)

    Yu, Yang; Zhang, Xueliang; Song, Zhangqi; Wang, Jianfei; Meng, Zhou

    2014-12-10

    This paper describes the effective rectification of the estimated diameter of an optical microfiber (OM) during the tapering process. A high-coherence laser is used to monitor the OM-tapering process. The evolution of the intermodal interference between the fundamental mode and the coupled modes can be clearly observed. We analyze the point in time at which the excited mode vanishes and use that to justify the correlative diameter of the fabricated OM for the first time, to the best of our knowledge. By comparing the measured cutoff time of the coupled LP(02) mode and the theoretically predicted value, we can judge whether the theoretical estimation of the OM diameter has been correctly obtained, and we can introduce a modification method with feedback by changing the initial parameters or the manufacturing conditions to ensure OM diameter accuracy. This identification and rectification method is helpful for precise fabrication of OMs with different waist lengths and waist diameters, and it can also be used to check the repeatability of OMs.

  19. Low threshold fiber taper coupled rare earth ion-doped chalcogenide microsphere laser

    Science.gov (United States)

    Li, Chao-Ran; Dai, Shi-Xun; Zhang, Qing-Yuan; Shen, Xiang; Wang, Xun-Si; Zhang, Pei-Qing; Lu, Lai-Wei; Wu, Yue-Hao; Lv, She-Qin

    2015-04-01

    We report the applications of a low-cost and environmentally friendly chalcogenide glass, 75GeS2-15Ga2S3-10CsI, in building active microsphere laser oscillators. A silica fiber taper is used as the coupling mechanism. With an 808-nm laser diode as a pump source, we show that a high-Q (˜ 6×104) laser mode could be obtained from a 75-μm diameter microsphere that is coupled with a 1.77-μm waist-diameter fiber taper. The threshold of the incident pump power is 1.39 mW, which is considerably lower than those of previously reported free-space coupled chalcogenide microsphere lasers. We also note an apparent enhancement in laser power generated from this chalcogenide microsphere laser. Project supported by the National Natural Science Foundation of China (Grant Nos. 61177087 and 61435009), the National Key Basic Research Program of China (Grant No. 2012CB722703), the Program for Innovative Research Team of Ningbo City, China (Grant No. 2009B21007) , the K. C. Wong Magna Fund in Ningbo University, the Open Fund of the State Key Laboratory of Luminescent Materials and Devices (South China University of Technology), China (Grant No. 2014-skllmd-01), and the Natural Science Foundation of Ningbo City, China (Grant No. 2014A610125).

  20. Plasma Density Tapering for Laser Wakefield Acceleration of Electrons and Protons

    Science.gov (United States)

    Ting, A.; Gordon, D.; Helle, M.; Kaganovich, D.; Sprangle, P.; Hafizi, B.

    2010-11-01

    Extended acceleration in a Laser Wakefield Accelerator can be achieved by tailoring the phase velocity of the accelerating plasma wave, either through profiling of the density of the plasma or direct manipulation of the phase velocity. Laser wakefield acceleration has also reached a maturity that proton acceleration by wakefield could be entertained provided we begin with protons that are substantially relativistic, ˜1 GeV. Several plasma density tapering schemes are discussed. The first scheme is called "bucket jumping" where the plasma density is abruptly returned to the original density after a conventional tapering to move the accelerating particles to a neighboring wakefield period (bucket). The second scheme is designed to specifically accelerate low energy protons by generating a nonlinear wakefield in a plasma region with close to critical density. The third scheme creates a periodic variation in the phase velocity by beating two intense laser beams with laser frequency difference equal to the plasma frequency. Discussions and case examples with simulations are presented where substantial acceleration of electrons or protons could be obtained.

  1. Study on self-imaging properties for line-tapered multimode interference couplers

    Science.gov (United States)

    Le, ZiChun; Huang, SunGang; Fu, MingLei; Dong, Wen; Zhang, Jie; Zhang, Ming

    2011-10-01

    The line-tapered multimode interference (MMI) couplers have advantage of compact dimension compared with conventional straight MMI couplers and then are more suitable for integrated optical components. In this paper, the self-imaging properties including general self-image and overlapping-image properties for the line-tapered MMI couplers are discussed thoroughly. Based on the width equation we defined, compact equations for the positions, amplitudes, phases of general images and overlapping images are deduced. Three disciplines for general self-imaging and four disciplines for overlapping-imaging are summarized and discussed. In addition, the overlapping-image properties are further studied by matrix analytic method and an inductive reasoning method of constructing phase and intensity matrix is developed based on it. Finally, all the theoretical results are compared with simulations results obtained by the finite-difference beam propagation method (FD-BPM). Both theoretical and simulation results are shown in this paper and demonstrated to be coincided with each other to a great extent.

  2. Periodic dislocation dynamics in two-dimensional concentrated emulsion flowing in a tapered microchannel

    Science.gov (United States)

    Gai, Ya; Leong, Chia Min; Cai, Wei; Tang, Sindy K. Y.

    2016-11-01

    Here we report a surprising order in concentrated emulsion when flowing as a monolayer in a tapered microfluidic channel. The flow of droplets in micro-channels can be non-trivial, and may lead to unexpected phenomena such as long-period oscillations and chaos. Previously, there have been studies on concentrated emulsions in straight channels and channels with bends. The dynamics of how drops flow and rearrange in a tapered geometry has not yet been characterized. At sufficiently slow flow rates, the drops arrange into a hexagonal lattice. At a given x-position, the time-averaged droplet velocities are uniform. The instantaneous drop velocities, however, reveal a different, wave-like pattern. Within the rearrangement zone where the number of rows of drops decreases from N to N-1, there is always a drop moved faster than the others. Close examination reveals the anomalous velocity profile arises from a series of dislocations that are both spatial and temporal periodic. To our knowledge, such reproducible dislocation motion has not been reported before. Our results are useful in novel flow control and mixing strategies in droplet microfluidics as well as modeling crystal plasticity in low-dimensional nanomaterials.

  3. Electrochemical impedance spectroscopy investigation on the clinical lifetime of ProTaper rotary file system.

    Science.gov (United States)

    Penta, Virgil; Pirvu, Cristian; Demetrescu, Ioana

    2014-01-01

    The main objective of the current paper is to show that electrochemical impedance spectroscopy (EIS) could be a method for evaluating and predicting of ProTaper rotary file system clinical lifespan. This particular aspect of everyday use of the endodontic files is of great importance in each dental practice and has profound clinical implications. The method used for quantification resides in the electrochemical impedance spectroscopy theory and has in its main focus the characteristics of the surface titanium oxide layer. This electrochemical technique has been adapted successfully to identify the quality of the Ni-Ti files oxide layer. The modification of this protective layer induces changes in corrosion behavior of the alloy modifying the impedance value of the file. In order to assess the method, 14 ProTaper sets utilized on different patients in a dental clinic have been submitted for testing using EIS. The information obtained in regard to the surface oxide layer has offered an indication of use and proves that the said layer evolves with each clinical application. The novelty of this research is related to an electrochemical technique successfully adapted for Ni-Ti file investigation and correlation with surface and clinical aspects.

  4. MMF and calcineurin taper in recurrent hepatitis C after liver transplantation: impact on histological course.

    Science.gov (United States)

    Bahra, Marcus; Neumann, U I F P; Jacob, Dietmar; Puhl, Gero; Klupp, Jochen; Langrehr, Jan M; Berg, Thomas; Neuhaus, Peter

    2005-02-01

    Hepatitis C virus (HCV) recurrence after orthotopic liver transplantation (OLT) is almost universal. The optimal immunosuppression for these patients is still under discussion. We designed a retrospective case-control study to evaluate the effect of mycophenolate mofetil (MMF) treatment in patients with recurrent hepatitis C. Forty patients with histologically proven hepatitis C recurrence after OLT were treated with MMF and calcineurin inhibitor (CNI) taper for 24 months and matched with 40 non-MMF-treated positive liver transplant recipients. Liver biopsies were obtained prior to MMF treatment and after a mean follow-up of 24 months. Histological changes were evaluated utilizing the Metavir score. Comparison of fibrosis/inflammation showed no impairment of histological findings during MMF treatment. In contrast, histological findings of the 40 non-MMF patients showed a significant increase of severity for inflammation/fibrosis. Viral load was similar in both groups. The course of alanin amino transferase (ALT) levels measured during MMF treatment showed a significant decrease. MMF in combination with CNI taper showed a positive effect on fibrosis progression, graft inflammation and ALT levels and may improve the clinical course of HCV after OLT, however, the antiviral properties of MMF are still unconfirmed.

  5. 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...

  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.

  7. 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.

  8. Electrochemical Impedance Spectroscopy Investigation on the Clinical Lifetime of ProTaper Rotary File System

    Science.gov (United States)

    Pirvu, Cristian; Demetrescu, Ioana

    2014-01-01

    The main objective of the current paper is to show that electrochemical impedance spectroscopy (EIS) could be a method for evaluating and predicting of ProTaper rotary file system clinical lifespan. This particular aspect of everyday use of the endodontic files is of great importance in each dental practice and has profound clinical implications. The method used for quantification resides in the electrochemical impedance spectroscopy theory and has in its main focus the characteristics of the surface titanium oxide layer. This electrochemical technique has been adapted successfully to identify the quality of the Ni-Ti files oxide layer. The modification of this protective layer induces changes in corrosion behavior of the alloy modifying the impedance value of the file. In order to assess the method, 14 ProTaper sets utilized on different patients in a dental clinic have been submitted for testing using EIS. The information obtained in regard to the surface oxide layer has offered an indication of use and proves that the said layer evolves with each clinical application. The novelty of this research is related to an electrochemical technique successfully adapted for Ni-Ti file investigation and correlation with surface and clinical aspects. PMID:24605336

  9. Electrochemical Impedance Spectroscopy Investigation on the Clinical Lifetime of ProTaper Rotary File System

    Directory of Open Access Journals (Sweden)

    Virgil Penta

    2014-01-01

    Full Text Available The main objective of the current paper is to show that electrochemical impedance spectroscopy (EIS could be a method for evaluating and predicting of ProTaper rotary file system clinical lifespan. This particular aspect of everyday use of the endodontic files is of great importance in each dental practice and has profound clinical implications. The method used for quantification resides in the electrochemical impedance spectroscopy theory and has in its main focus the characteristics of the surface titanium oxide layer. This electrochemical technique has been adapted successfully to identify the quality of the Ni-Ti files oxide layer. The modification of this protective layer induces changes in corrosion behavior of the alloy modifying the impedance value of the file. In order to assess the method, 14 ProTaper sets utilized on different patients in a dental clinic have been submitted for testing using EIS. The information obtained in regard to the surface oxide layer has offered an indication of use and proves that the said layer evolves with each clinical application. The novelty of this research is related to an electrochemical technique successfully adapted for Ni-Ti file investigation and correlation with surface and clinical aspects.

  10. 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.

  11. Evanescent field interaction of tapered fiber with graphene oxide in generation of wide-bandwidth mode-locked pulses

    Science.gov (United States)

    Ahmad, H.; Faruki, M. J.; Razak, M. Z. A.; Tiu, Z. C.; Ismail, M. F.

    2017-02-01

    Pulses with picosecond pulse widths are highly desired for high precision laser applications. A mode-locked pulse laser utilizing evanescent field interaction of a tapered fiber with graphene oxide (GO) is demonstrated. A homemade fabrication stage was used to fabricate the tapered fiber using systematic flame brushing and a GO solution was used to coat the microfiber using optical deposition technique. Pulse trains with a pulse width of 3.46 ps, a 3 dB optical bandwidth of 11.82 nm and a repetition rate of 920 kHz were obtained. The system has substantial potential for many crucial medical, communication, bio processing, military, and industrial applications.

  12. All-fiber modal interferometer based on an up-taper-core-offset structure for curvature sensing

    Institute of Scientific and Technical Information of China (English)

    马林; 齐艳辉; 孙将; 康泽新; 简水生

    2015-01-01

    A high-sensitivity curvature sensor based on an up-taper-core-offset structure is proposed and demonstrated in this paper. Here two specially designed cascaded up-tapers with maximum diameters of 247 µm and 251 µm, respectively, are used as a cladding mode exciting component. The excited cladding modes will propagate in the cladding and re-couplers with the core mode at the core-offset jointing point. When the curvature is changed, the dip wavelength of the sensor will shift to a blue wavelength and an average curvature sensitivity of more than−12.5 nm/m−1 is achieved within the measured curvature intervals.

  13. Real-time monitoring of intracellular signal transduction in PC12 cells by non-adiabatic tapered optical fiber biosensor

    Science.gov (United States)

    Zibaii, M. I.; Latifi, H.; Asadollahi, A.; Noraeipoor, Z.; Dargahi, L.

    2014-05-01

    Real-time observation of intracellular process of signal transduction is very useful for biomedical and pharmaceutical applications as well as for basic research work of cell biology. For feasible and reagentless observation of intracellular alterations in real time, we examined the use of a nonadiabatic tapered optical fiber (NATOF) biosensor for monitoring of intracellular signal transduction that was mainly translocation of protein kinase C via refractive index change in PC12 cells adhered on tapered fiber sensor without any indicator reagent. PC12 cells were stimulated with KCl . Our results suggest that complex intracellular reactions could be real-time monitored and characterized by NATOF biosensor.

  14. Research on taper zone coupling from single-core fiber to annular-core hollow beam fiber

    Science.gov (United States)

    Tong, Chengguo; Zhang, Tao; Li, Jianqi; Wang, Pengfei; Kang, Chong; Yuan, Libo

    2016-11-01

    We designed and manufactured a novel annular-core hollow beam fiber which could directly yield ring light with a central dark spot inside the beam employing MCVD technique and a custom-made fiber drawing tower. The tapered fiber zone geometric shapes at varied stretching speed between the single-core fiber and the annular-core hollow beam fiber were studied theoretically. According to the beam propagation method, the bi-tapered coupling energy transmission between these two fibers was simulated and analyzed. Moreover, by adopting a fusion splicing and stretching technique at the fiber-linked point, an effective coupling approach had been fulfilled.

  15. RhoA, Rho kinase, JAK2, and STAT3 may be the intracellular determinants of longevity implicated in the progeric influence of obesity: Insulin, IGF-1, and leptin may all conspire to promote stem cell exhaustion.

    Science.gov (United States)

    Tapia, Patrick C

    2006-01-01

    seen with the inexorable passage of time. Besides the obvious utility for the management for human age-related dysfunction that investigation of pharmacologic inhibitors of these proteins would provide, interventions such as caloric restriction and possibly intermittent fasting may beneficially influence stem cell proliferation dynamics and reduce intracellular correlates of mitogenic drive. Integrating the findings present in the present body of research may reveal endocrinological states that are compatible with longevity, and will also provide novel insight into the specific proteomic determinants of age-related physiologic decline, ushering in a new epoch of medicine that fosters the management of the "pre-etiopathology" of chronic disease and disability of aging, therefore mitigating the suffering widely thought to be inherent in the latter stages of life.

  16. Dentinal crack formation during root canal preparations by the twisted files and ProTaper Universal%TF与ProTaper Universal镍钛器械根管预备后牙根微裂的体外研究

    Institute of Scientific and Technical Information of China (English)

    吴丽娟; 于飞

    2015-01-01

    目的:比较TF与ProTaper Universal镍钛器械根管预备后牙根微裂的发生情况.方法:30颗离体下颌切牙随机分成3组(n=10),两实验组分别使用TF和ProTaper Universal镍钛锉预备根管至#25/0.06和F2,对照组不进行根管预备.根管预备后,距根尖孔3 mm、6 mm、9 mm处进行水平切盘,体视显微镜下观察牙根不同横截面牙根微裂的发生情况.结果:对照组未观察到牙根微裂.实验组中,TF和ProTaper Universal组产生牙根微裂的比例分别为10%(1/10)和60%(6/10),两者之间差异有统计学意义(P<0.05).结论:使用TF镍钛系统进行根管预备产生的牙根微裂明显低于ProTaper Universal.

  17. Armor and anesthesia: exposure, feeling, and the soldier's body.

    Science.gov (United States)

    MacLeish, Kenneth T

    2012-03-01

    For many civilians, the high-tech weapons, armor, and military medicine with which U.S. soldiers are equipped present an image of lethal capacity and physical invulnerability. But, as this article explores, soldiers themselves just as often associate the life-sustaining technology of modern warfare with feelings that range from a pragmatic ambivalence about exposure to harm all the way to profoundly unsettling vulnerability. This article, based on fieldwork among soldiers and military families at the U.S. Army's Ft. Hood, examines sensory and affective dimensions of soldiers' intimate bodily relationships with the technologies that alternately or even simultaneously keep them alive and expose them to harm. I argue that modern military discipline and technology conspire to cultivate soldiers as highly durable, capable, unfeeling, interchangeable bodies, or what might be called, after Susan Buck-Morss (1992), anesthetic subjects. But for soldiers themselves, their training, combat environment, protective gear, and weapons are a rich font of both emotional and bodily feeling that exists in complex tension with the also deeply felt military imperative to carry on in the face of extreme discomfort and danger.

  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. Performance of tapered column packed-bed bioreactor for ethanol production.

    Science.gov (United States)

    Hamamci, H; Ryu, D D

    1987-06-01

    A tapered column type of bioreactor system packed with immobilized Saccharomyces cerevisiae was used to study the bioreactor performance as a function of design and operating variables. The performance of tapered column bioreactor system was found to be better than that of the conventional cylindrical column reactor system for the ethanol fermentation. The new bioreactor design alleviated problems associated with carbon dioxide evolution and provided a significantly better flow pattern for both liquid and gas phases in the bioreactor without local channelling. A mathematical simulation model, which takes into account of the axial convection and dispersion, interphase mass transfer, and apparent kinetic design parameters, was developed. The effect of radial concentration gradients on the bioreactor performance was found to be insignificant. For the reactor system studied, the maximum ethanol productivity obtained was 60 g ethanol/L gel/h, and the maximum glucose assimilation rate was 140 g glucose/L gel/h. One of the most important findings from this study was that the apparent kinetic parameters change at the glucose concentration of 2 g/L This change was found to be due to the changes in yeast physiology and metabolism. The values of V(m) (') and V(m) (') decreased from 0.8 to 0.39 g ethanol/g cell/h and from 97mM to 11mM, respectively. The substrate inhibition constant was estimated as 0.76M and the product inhibition constant was determined as 113 g ethanol/L The degree of product inhibition showed practically a linear relationship with an increasing ethanol concentration. Based on the hydro-dynamic analysis of the bioreactor system, it was found that the Peclet number, N(Pe) was not a strong function of the flow velocity at low flow rates through the bioreactor system, but its value decreased somewhat at an interstitial velocity greater than 0.03 cm/s. The tapered column bioreactor system showed a much better flow pattern of gas and liquid phases within the

  20. Synthesis and Luminescent Properties of Planar-tip and Tapered-tip ZnO Nanorod Arrays

    Institute of Scientific and Technical Information of China (English)

    Chun-wen WANG; Jr-hau HE; Lih-juann CHEN

    2008-01-01

    Vertically aligned ZnO nanorods were synthesized on a-plane sapphire via a metal catalyzed vapor phase transport and condensation process in a two-zone vacuum furnace. Planar-tip and tapered-tip ZnO nanorods were successfully synthesized by utilizing different source materials under the same growth conditions. The growth mechanisms were proposed to be vapor-liquid-solid (VLS) process for planar-tip ZnO nanorods and a combination of VLS and self-catalyzed processes for tapered-tip ZnO nanorods. From cathodoluminescence (CL) measurements, tapered-tip ZnO nanorods have more intense green emission than planar-tip ZnO nanorods, and therefore possess higher oxygen vacancy concentration than planar-tip ZnO nanorods. From CL characteristics, well-aligned planar-tip ZnO nanorods shall serve effectively as laser source, while well-aligned tapered-tip ZnO nanorods are suitable for direction-related optical applications.

  1. Segmented taper equations with crown ratio and stand density for Dahurian Larch (Larix gmelinii) in Northeastern China

    Institute of Scientific and Technical Information of China (English)

    JIANG Li-chun; LIU Rui-long

    2011-01-01

    Segmented taper equation was selected to model stem profileof Dahurian larch (Larix gmelinii Rupr.). The data were based on stemanalysis of 74 trees from Dailing Forest Bureau in Heilongjiang Province,Northeastern China. Two taper equations with crown ratio and standbasal area were derived from the Max and Burkhart's (1976) taper equa-tion. Three taper equations were evaluated: (1) the original equation, (2)the original equation with crown ratio, and (3) the original equation withbasal area. SAS NLIN and SYSNLIN procedures were used to fit taperequations. Fit statistics and cross-validation were used to evaluate theaccuracy and precision of these models. Parameter estimates showed that the original equation with inclusion of crown ratio and basal area vari-ables provided significantly different parameter estimates with lowerstandard errors. Overall fit statistics indicated that the root mean squareerror (RMSE) for diameter outside and inside bark decreased respec-tively by 10% and 7% in the original model with crown ratio and by 12%and 7.2% in the original model with basal area. Cross-validation furtherconfirmed that the original equation with inclusion of crown ratio andbasal area variables provided more accurate predictions at the lowersection (relative heights, 50%) for both outside and inside bark diameters.

  2. 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) agr...

  3. 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.

  4. Beliefs about the causes of depression and recovery and their impact on adherence, dosage, and successful tapering of antidepressants

    NARCIS (Netherlands)

    Klein, Nicola; van Rijsbergen, Gerard; Burger, Huibert; ten Doesschate, Mascha C.; Hollon, Steven D.; Bockting, Claudi

    2016-01-01

    Background: Continuation of antidepressant medication (ADM) after remission is widely used to prevent depressive relapse/recurrence. Little is known about predictors of ADM use in terms of adherence, dosage, and successful tapering. The current study aimed to explore beliefs about the causes of depr

  5. Revision Total Hip Arthroplasty Using a Modular Tapered Stem With Distal Fixation Good Short-Term Results in 125 Revisions

    DEFF Research Database (Denmark)

    Ovesen, Ole; Emmeluth, Claus; Hofbauer, Christian;

    2009-01-01

    After 2 to 7 years we reviewed 125 prosthetic hip arthroplasty stem revisions using a modular tapered stem with distal fixation. Median age of these patients was 68 (33-92) years. Baseline and follow-up data were registered prospectively according to the Danish Hip Arthroplasty Registry. Survival...

  6. 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

  7. 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.; van der Sluis, 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-ve

  8. Centering Ability of ProTaper Next and WaveOne Classic in J-Shape Simulated Root Canals.

    Science.gov (United States)

    Troiano, Giuseppe; Dioguardi, Mario; Cocco, Armando; Giuliani, Michele; Fabiani, Cristiano; D'Alessandro, Alfonso; Ciavarella, Domenico; Lo Muzio, Lorenzo

    2016-01-01

    Introduction. The aim of this study was to evaluate and compare the shaping and centering ability of ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland) and WaveOne Classic systems (Dentsply Maillefer) in simulated root canals. Methods. Forty J-shaped canals in resin blocks were assigned to two groups (n = 20 for each group). Photographic method was used to record pre- and postinstrumentation images. After superimposition, centering and shaping ability were recorded at 9 different levels from the apex using the software Autocad 2013 (Autodesk Inc., San Rafael, USA). Results. Shaping procedures with ProTaper Next resulted in a lower amount of resin removed at each reference point level. In addition, the pattern of centering ability improved after the use of ProTaper Next in 8 of 9 measurement points. Conclusions. Within the limitations of this study, shaping procedures with ProTaper Next instruments demonstrated a lower amount of resin removed and a better centering ability than WaveOne Classic system.

  9. 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

  10. Effect of Patency File on Transportation and Curve Straightening in Canal Preparation with ProTaper System.

    Science.gov (United States)

    Hasheminia, Seyed Mohsen; Farhadi, Nastaran; Shokraneh, Ali

    2013-01-01

    The aim of this ex vivo study was to evaluate the effect of using a patency file on apical transportation and curve straightening during canal instrumentation with the ProTaper rotary system. Seventy permanent mandibular first molars with mesiobuccal canals, measuring 18-23 mm in length and with a 25-40° curvature (according to the Schneider method), were selected. The working lengths were determined and the teeth were mounted and divided into two experimental groups: (A) prepared by the ProTaper system without using a patency file (n = 35) and (B) prepared by the ProTaper system using a patency file (n = 35). Radiographs taken before and after the preparation were imported into Photoshop software and the apical transportation, and curve straightening were measured. Data were analyzed using independent t-test. Partial correlation analysis was performed to evaluate the relationship between the initial curvature, transportation, and curve straightening (α = 0.05). Using a patency file during canal preparation significantly decreased both apical transportation and curve straightening (P ProTaper rotary system.

  11. 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.

  12. 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.

  13. Comparison of modeling of the rotating tapered axially functionally graded Timoshenko and Euler-Bernoulli microbeams

    Science.gov (United States)

    Shafiei, Navvab; Kazemi, Mohammad; Ghadiri, Majid

    2016-09-01

    The target of this paper is to present an exhaustive study on the small scale effect on vibrational behavior of a rotary tapered axially functionally graded (AFG) microbeam on the basis of Timoshenko and Euler-Bernoulli beam and modified couple stress theories. The variation of the material properties and cross section along the longitudinal direction of the microbeam are taken into consideration as a linear function. Hamilton's principle is used to derive the equations for cantilever and propped cantilever boundary conditions and the generalized differential quadrature method (GDQM) is employed to solve the equations. By parametric study, the effects of small-scale parameter, rates of cross section change of the microbeam and angular velocity on the fundamental and second frequencies of the microbeam are studied. Also, comparison between the frequencies of Timoshenko and Euler-Bernoulli microbeams are presented. The results can be used in many applications such as micro-robots and biomedical microsystems.

  14. All-fibre micro-ring resonator based on tapered microfibre

    Institute of Scientific and Technical Information of China (English)

    Dong Xiao-Wei; Lu Shao-Hua; Feng Su-Chun; Xu Ou; Jian Shui-Sheng

    2008-01-01

    In this paper, bendloss characteristics of an optical fibre are investigated in detail, and the results show that the resonator with a smaller ring radius, wider free spectrum range (FSR), higher fineness (f) and quality-factor (Q) can be achieved by using microfibres. Based on the improved fused taper technique, a high-quality microfibre with 5 μm radius has been fabricated, and an all-fibre micro-ring resonator with a radius of only 500 μm is realized using self-coiling coupling method. The good-resonant characteristic makes the all-fibre device be expected to avoid bendloss and connection loss associated with planar waveguide integration.

  15. Sub-nanometer tuning of mode-locked pulse by mechanical strain on tapered fiber

    Science.gov (United States)

    Ahmad, Harith; Faruki, Md Jahid; Tiu, Zian Cheak; Thambiratnam, K.

    2017-03-01

    A tunable mode-locked fiber laser based on the non-linear polarization rotation (NPR) technique is proposed and demonstrated. A passively generated mode-locked output is obtained with a repetition rate of about 70 ns and an average output power of 0.7 mW, as well as a laser efficiency of 0.53%. The mode-locked pulses can be tuned over a span of 4.4 nm, from 1560.6 nm to 1556.2, corresponding to a stretching of the tapered fiber from 0 to 100 μm in 10 μm increments. The pulses have an average signal-to-noise ratio of about 41 dB in the frequency domain, indicating a highly stable mode-locked output. The system can repeat and reverse the generation of these pulses, a crucial criterion of many communications and sensing applications.

  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.

  17. Microwave sidebands for laser cooling by direct modulation of a tapered amplifier

    Science.gov (United States)

    Mahnke, J.; Kulas, S.; Geisel, I.; Jöllenbeck, S.; Ertmer, W.; Klempt, C.

    2013-06-01

    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 × 109 87Rb 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 benefit a wide range of applications reaching from atom-based mobile sensors to the laser cooling of molecules.

  18. Rotation and deformation of human red blood cells with light from tapered fiber probes

    Science.gov (United States)

    Liu, Xiaoshuai; Huang, Jianbin; Li, Yuchao; Zhang, Yao; Li, Baojun

    2017-01-01

    Dynamic rotation and deformation of human red blood cells (RBCs) are extremely important to investigate the survival and mechanical features of cells, which will be of great physiological and pathological significance. Here, we report an optical approach that is capable of both rotating and deforming RBCs with light from two tapered fiber probes (TFPs). With laser beams at the wavelength of 980 nm injected into the TFPs, a single RBC was rotated around different axes while single or multiple RBCs were stretched by adjusting the points of action and magnitude of the optical forces from the TFPs. The biological safety of the approach was also discussed by taking the laser power required into account.

  19. Evaluation of taper functions aiming Eucalyptus sp stem optimizatio for multi-products

    Directory of Open Access Journals (Sweden)

    Adriano Ribeiro de Mendonça

    2007-03-01

    Full Text Available This work evaluate different models for estimating volume and height along the stem, in order to guarantee more precise inputs in the optimization systems for obtaining multi-products. It was tested the taper equations proposed by Demaerschalk, Ormerod, Schoepfer and Hradelzky. These models were tested for the commercial diameter of 7 and 28 cm in Eucalyptus sp. trees. The database was obtained from upper stem diameter measurements of 16 years-old trees, in a total of 32 sample trees for the model fitting and 27 sample trees for the validation test. Based on the graphic residual analysis, on the statistics (correlation coefficient, relative standard error, “bias” (B, average of the differences (MD and standard deviation of the differences (DPD and on the test of Leite & Oliveira (2002, it was verified that the Ormerod model presented better volume estimates and the Schoepfer model provided better height results.

  20. Mid-infrared supercontinuum generation in tapered As2S3 chalcogenide planar waveguide

    Science.gov (United States)

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

    2016-10-01

    We numerically demonstrate mid-infrared supercontinuum generation in a non-uniformly tapered chalcogenide planar waveguide. This planar rib waveguide of As2S3 glass on MgF2 is 2 cm long with increasing etch depth longitudinally to manage the total dispersion. This waveguide has zero dispersion at two wavelengths. The dispersion profile varies along the propagation distance, leading to continuous modification of the phase-matching condition for dispersive wave emission and enhancement of energy transfer efficiency between solitons and dispersive waves. Numerical simulations are conducted for secant input pulses at a wavelength of 1.55 μm with a width of 50 fs and peak power of 2 kW. Results show this proposed scheme significantly broadens the generated continuum, extending from ~1 to ~7 μm.

  1. Broadband frequency conversion via adiabatically tapered $\\chi^{(2)}$ waveguide in photonic integrated circuits

    CERN Document Server

    Xiong, Xiao; Guo, Xiang; Tang, Hong X; Ren, Xi-Feng; Guo, Guang-Can

    2016-01-01

    We propose to use the integrated aluminum nitride waveguide with engineered width variation to achieve optical frequency conversion based on $\\chi^{(2)}$ nonlinear effect on a photonic chip. We show that in an adiabatically tapered waveguide, the frequency conversion has a much broader bandwidth and the efficiency within the bandwidth is almost constant, which is favorable for short pulses. We demonstrate both analytically and numerically an "area law" for the frequency conversion, i.e. the product of bandwidth and efficiency is conserved as long as peak conversion efficiency does not saturate. The adiabatic structure shows higher saturation thresholds in pump power or interaction length, outperforming the conventional uniform waveguide design. With our approach, high-efficiency and wavefront-keeping conversion for short pulses is possible on a photonic chip, which will surely find applications for scalable on-chip information processing.

  2. Four-wave mixing instabilities in photonic-crystal and tapered fibers.

    Science.gov (United States)

    Biancalana, F; Skryabin, D V; Russell, P St J

    2003-10-01

    Four-wave mixing instabilities are theoretically studied for continuous wave propagation in ultrasmall core photonic-crystal and tapered fibers. The waveguide, or geometrical, contribution to the overall dispersion of these structures is much stronger than in conventional fibers. This leads to the appearance of unstable frequency bands that are qualitatively and quantitatively different from those seen in conventional fibers. The four-wave mixing theory developed here is based on the full wave equation, which allows rigorous study of the unstable bands even when the detunings are of the order of the pump frequency itself. Solutions obtained using the generalized nonlinear Schrödinger equation, which is an approximate version of the full wave equation, reveal that it suffers from several deficiencies when used to describe four-wave mixing processes.

  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. 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.

  5. 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...

  6. Optimization of silicon-on-insulator based optical switch using tapered waveguides

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Optimiz ed 2×2 switches based on silicon-on-insulator (SOI) were demonstrated. In the design, single mode rib waveguides and multimode interferences (MMIs) are connected by tapered waveguides to reduce the mode coupling loss between the two types of waveguides. The average insertion loss of the switches is about -16.9 dB and the excess loss of one is measured of -1.3 dB. The worst crosstalk is larger than 25 dB. Experimental results indicate that some of the main characteristics of optical switches are improved in the modified design, which is according with theoretic analysis. The novel design can be used to improve the characteristics of optical switch matrixes based on 2×2 switch units.

  7. 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.

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

    Science.gov (United States)

    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 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

  9. Propagation source wavelet phase extraction using multi-taper method coherence estimation

    Science.gov (United States)

    Hariri Naghadeh, Diako; Morley, Christopher Keith

    2017-02-01

    It is possible to use statistical methods to extract the propagation source wavelet phase from seismic data without getting information from a well log. Using kurtosis as a high-order statistics can preserve the phase of the signal but it is highly sensitive to outliers. A new method is introduced here called the multi-taper method coherence estimation. Two steps are required: first, a cosine function that includes the dominant frequency and maximum amplitude of signal is chosen. Secondly, the maximum coherence in the frequency band of the signal, which shows the best phase matching between the time series is determined. To validate this new method real data sets were chosen and the extracted wavelet phases for noise free and noisy data sets were compared with data extracted from a well log. Extracted wavelets using Kurtosis were also generated for comparison, and demonstrate the improved results using the new method.

  10. Non-contact Measurement of Damaged External Tapered Thread Based on Linear Array CCD

    Science.gov (United States)

    He, F. J.; Zhang, R. J.; Du, Z. J.; Cui, X. M.

    2006-10-01

    The non-contact measurement of external tapered thread based on linear array CCD is presented to decrease the measuring error caused by local damage area contrast to the measurement with mechanical gauges. The thread is scanned by linear array CCD and the signal is processed by first order difference to obtain thread contour. For the thread with damage on tooth flank and deformation on generating line, the Hough transform and weighted least squares are adopted to reduce the local defects and to set up fitted thread contour equations that can reflect the real dimension. Then the dimensions can be calculated based on these equations according to the definition. The paper also presents the method to evaluate the local damage. Experiment shows that the method is suitable for the measurement of damaged thread.

  11. Analytical model for extracting mechanical properties of a single cell in a tapered micropipette

    Science.gov (United States)

    He, J. H.; Xu, W.; Zhu, L.

    2007-01-01

    A simple solid mechanical model has been developed to extract the mechanical properties of a single cell in a tapered micropipette. This analytical model is derived using the definition of elastic modulus and force equilibrium. Using the authors' model, an elastic modulus of 21.80±4.91Pa, a Poisson ratio of 0.46±0.03, and a friction coefficient of 0.0274±0.0077 are extracted for a neutrophil cell. The model is verified by finite element software and shows good agreement with experiments. The biophysical basis of the model and application in microfluidic channels for cancer cell research are discussed, while a comparison is made with other models.

  12. Enhanced THz extinction of single plasmonic antennas with conically tapered waveguides

    CERN Document Server

    Schaafsma, Martijn C; Berrier, Audrey; Gomez-Rivas, Jaime

    2012-01-01

    We demonstrate experimentally the resonant extinction of THz radiation by a single plasmonic bowtie antenna, formed by two n-doped Si monomers with a triangular shape and facing apexes. This demonstration is achieved by placing the antenna at the output aperture of a conically tapered waveguide, which enhances the intensity of the incident THz field at the antenna position by a factor 10. The waveguide also suppresses the background radiation that otherwise is transmitted without being scattered by the antenna. Bowtie antennas, supporting localized surface plasmon polaritons, are relevant due to their ability of resonantly enhancing the field intensity at the gap separating the two triangular elements. This gap has subwavelength dimensions, which allows the concentration of THz radiation beyond the diffraction limit. The combination of a bowtie plasmonic antenna and a conical waveguide may serve as a platform for far-field THz time-domain spectroscopy of single nanostructures placed in the gap.

  13. Analysis of 3D curve expansion of conical cam with oscillating tapered roller follower

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper focuses on the analysis of running conditions and machining processes of conical cam with oscillating follower. We point out the common errors existing in the design and machining of the widely used plane expansion method of conical cam trough-out line. We show that the motion can be divided into two parts, i.e. the oscillating motion of oscillating bar and the rotary motion of oscillating bar relative to the conical cam. By increasing the rotary motion of oscillating bar, the motion path of tapered roller on oscillating bar (i.e. contour surface of conical cam) can be expanded on the cylinder. Based on these analyses,we present a creative and effective designing and machining method for 3D curve expansion of conical cam with oscillating follower.

  14. 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.

  15. 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.

  16. Effects of mold geometry and taper angles on the filling mechanism of a nanoimprinted polymer using molecular dynamics

    Science.gov (United States)

    Wu, Cheng-Da; Fang, Te-Hua; Lin, Jen-Fin

    2014-10-01

    Molecular dynamics simulations are used to investigate how the nanoimprint lithography mechanism influences the filling interaction and mechanical deformation on polymethylmethacrylate (PMMA) surfaces. The effects of two mold geometries and various taper angles were investigated using stress, slip vector, molecular trajectories, and applied force analysis. For the PMMA formation mechanism on a concave-like mold imprint, the molecules were extruded upward into the mold space after the molecules on two sides were downward compressed by the mold. The formation mechanism is opposite to that for the tip-like mold imprint because the molecules are firstly compressed downward by the tip. The results show that the slowest filled areas of the pattern were at the two corners of the tip where stress value was low. The filling speed in both the tip-like mold and the concave-like mold imprint increased with the taper angle increased due to filling space and smaller capillary flow. Due to the effect of capillary flow, the concave-like mold needs much more loading force to transfer the pattern than the tip-like mold. The loading force and curve oscillation increased with the taper angle in the tip-like mold imprint, but they significantly increased with decreasing taper angle in the concave-like mold. The high stress was mainly concentrated on the molecules near the tip and underneath the mold for the tip-like mold and the concave-like mold imprint, respectively. The relationship of the magnitude of taper angle to the loading force is similar to stress and slip vector.

  17. Effect of the sterilization on the cutting efficiency of ProTaper® and K3® endodontic instruments

    Directory of Open Access Journals (Sweden)

    Alex Niederauer Becker

    2009-12-01

    Full Text Available Objective: This objective of this study was to evaluate the effect of sterilization on the cutting efficiency of rotary endodontic instruments, ProTaper® (Dentsply Maillefer Instruments S.A., Ballaigues, Suíça and K3® (Sybron/Kerr, Orange, CA, USA, by the time X weighing method. Method: For this purpose, 60 simulated canals and 66 instruments were used (36 of the ProTaper® system, (Dentsply Maillefer Instruments S.A., Ballaigues, Switzerland and 30 of the K3® system (Sybron/Kerr, Orange, CA, USA. The rotary instruments were divided into four experimental groups. The instruments in Group A (K3®, Sybron/Kerr, Orange, CA, USA and Group B (ProTaper®, Dentsply Maillefer Instruments S.A., Ballaigues, Switzerland, were subjected to a process of cleaning and sterilization. Whereas the instruments in Group C (K3®, Sybron/Kerr, Orange, CA, USA and Group D (ProTaper®, Dentsply Maillefer Instruments S.A., Ballaigues, Switzerland, were subjected to the cleanness process only, and were not sterilized. Results: As regards analysis of the results, the Student’s-t test was used, by which it was verified that the instruments in Group had greater cutting efficiency in comparison with those in Group B. Similarly the instruments in Group C had greater cutting efficiency in comparison with those in Group D, nevertheless, there was no statistically significant difference. Moreover, as regards the number times of use, there was also no statistically significant difference between the experimental groups. However in all the groups there was a decrease in the cutting efficiency with an increasing number of times of use. Conclusion: Thus, the cutting efficiency of rotary endodontic instruments K3® (Sybron/Kerr, Orange, CA, USA and ProTaper® (Dentsply Maillefer Instruments S.A., Ballaigues, Suição was not statistically affected after the use of 6 autoclave sterilization cycles.

  18. Metallurgical analysis and fatigue resistance of WaveOne and ProTaper nickel-titanium instruments.

    Science.gov (United States)

    Pirani, Chiara; Ruggeri, Oddone; Cirulli, Pier Paolo; Pelliccioni, Gian Andrea; Gandolfi, Maria Giovanna; Prati, Carlo

    2014-07-01

    The aim of the study was to evaluate cyclic fatigue resistance of two NiTi instruments and to analyse their surface, fractographic and matrix morphology under ESEM/EDS and optical microscopy. WaveOne Primary and ProTaper Universal F2 brand new instruments were subjected to fatigue testing in an artificial canal with 5.0 mm radius and 60° angle of curvature. Seventy-two instruments were divided into three groups (n = 24), according to the selected kinematics: WaveOne using reciprocation (A); ProTaper using reciprocation (B) or rotation (C). Time to fracture was recorded. Data were analysed with ANOVA and Tukey test. ESEM/EDS analysis was conducted on new files to examine surface characteristics and on fractured fragments to identify the fractographic features. Metallographic analysis was performed with optical microscope on new instruments to evaluate alloy properties. Significant differences were found with Group A, which was statistically more resistant to cyclic fatigue (P ProTaper files the presence of deep milling marks. ESEM fractographic analysis of WaveOne showed multiple crack origins with an area of fatigue propagation wider than ProTaper instruments, in which a single crack origin could be detected. EDS analysis confirmed the equiatomic NiTi composition. Metallographic analysis under optical microscope revealed in WaveOne instruments the presence of nano-crystalline martensitic grains embedded in austenite matrix, presence which could not be found in ProTaper files. WaveOne NiTi files revealed higher resistance to fatigue stress, suggesting extended working time in clinical applications.

  19. Body contact and body language

    DEFF Research Database (Denmark)

    Winther, Helle Dagmar

    2008-01-01

    ­logue between a written text and a visceral on-line performance involving photographs and music, the reader/audience has the possibility to be touched both sensually and intellectually, although through communication is in cyberspace, missing the liveliness of direct body language. Udgivelsesdato: 2008-May......Body contact and body language are unique and existential and, although culturally dependent and socially embodied, they are also universal communication forms. For small children all over the world, warm, close and nourishing body contact is fundamental to their embodied experi­ence of themselves...... 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...

  20. Body Basics

    Science.gov (United States)

    ... more 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 Heart and Circulatory System Immune ...

  1. 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...

  2. Body Language

    Institute of Scientific and Technical Information of China (English)

    JosephDeVeto

    2004-01-01

    When we speak,we use much more than just words. We also communicate with our face. our hands,and even our own body. This Kind of communication ean be called “body language” or “non-verbal eommunieation”. Non-verbal

  3. 机用镍钛器械 ProTaper 预备磨牙根管的临床评价%Clinical evaluation on the preparation of molar root canals with ProTaper rotary instruments X

    Institute of Scientific and Technical Information of China (English)

    许志亮

    2015-01-01

    目的:评价机用 ProTaper 镍钛根管器械行磨牙根管预备的临床疗效。方法2011年1月至2013年12月选取患有磨牙牙髓炎或根尖周炎的患者99例,共116颗磨牙;随机分为实验组(49例,58颗牙)和对照组(50例,58颗牙)。对照组用不锈钢 K 型锉预备根管,实验组用机用镍钛器 ProTaper 根管锉预备根管。充填根管过程两组患者均采用侧向加压法。根据 X 线片评价根管预备和充填效果,且记录每颗患牙的单个根管预备所用时间、术后不良反应及远期疗效。结果与对照组相比,机用 ProTaper 镍钛器械预备单根管所耗时间短,根管预备后疼痛发生率低,根管适充率高,根管治疗术后1年疗效好。结论使用机用 ProTaper 器械进行恒磨牙根管预备快速、高效,根充效果好,术后疼痛少,值得临床推广。%Objective To evaluate the quality of molar root canal preparation using ProTaper rotary instruments. Methods From January 2011 to December 2013,99 adult patients with 116 affected molars who were diagnosed to receive root canal treatment were divided into two groups based on the randomly - paired principle. There were 58 teeth in each group. In group A,root canals were prepared with rotary ProTaper files in crown - down mode,and in group B root canals were prepared with traditional stainless steel K files by hand. All root canals were obturated with lateral condensation method. The time consumed in preparation of each canal was recorded. The outcome of root filling and side effects occurred af-ter the operation were also noted. 1 year later all the cases were revisited and the therapeutic results were verified. Results Time consumed in the preparation of group A was significantly less than group B. Exact filling rate of canals prepared with rotary ProTaper files was higher than with k files and side effects after the operation such as tooth ache and swelling less occurred. One year

  4. Comparative study of material loss at the taper interface in retrieved metal-on-polyethylene and metal-on-metal femoral components from a single manufacturer.

    Science.gov (United States)

    Bills, Paul; Racasan, Radu; Bhattacharya, Saugatta; Blunt, Liam; Isaac, Graham

    2017-04-01

    There have been a number of reports on the occurrence of taper corrosion and/or fretting and some have speculated on a link to the occurrence of adverse local tissue reaction specifically in relation to total hip replacement which have a metal-on-metal bearing. As such a study was carried out to compare the magnitude of material loss at the taper in a series of retrieved femoral heads used in metal-on-polyethylene bearings with that in a series of retrieved heads used in metal-on-metal bearings. A total of 36 metal-on-polyethylene and 21 metal-on-metal femoral components were included in the study all of which were received from a customer complaint database. Furthermore, a total of nine as-manufactured femoral components were included to provide a baseline for characterisation. All taper surfaces were assessed using an established corrosion scoring method and measurements were taken of the female taper surface using a contact profilometry. In the case of metal-on-metal components, the bearing wear was also assessed using coordinate metrology to determine whether or not there was a relationship between bearing and taper material loss in these cases. The study found that in this cohort the median value of metal-on-polyethylene taper loss was 1.25 mm(3) with the consequent median value for metal-on-metal taper loss being 1.75 mm(3). This study also suggests that manufacturing form can result in an apparent loss of material from the taper surface determined to have a median value of 0.59 mm(3). Therefore, it is clear that form variability is a significant confounding factor in the measurement of material loss from the tapers of femoral heads retrieved following revision surgery.

  5. Synthesis of Tapered CdS Nanobelts and CdSe Nanowires with Good Optical Property by Hydrogen-Assisted Thermal Evaporation

    Directory of Open Access Journals (Sweden)

    Wang Min

    2009-01-01

    Full Text Available Abstract The tapered CdS nanobelts and CdSe nanowires were prepared by hydrogen-assisted thermal evaporation method. Different supersaturation leads to two different kinds of 1D nanostructures. The PL measurements recorded from the as-prepared tapered CdS nanobelts and CdSe nanowires show only a bandgap emission with relatively narrow full-width half maximum, which means that they possess good optical property. The as-synthesized high-quality tapered CdS nanobelts and CdSe nanowires may be excellent building blocks for photonic devices.

  6. 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...

  7. 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....... 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...... presents an overview of our knowledge about the taphomic processes as well as the methods used in bog body research....

  8. Body Language

    Institute of Scientific and Technical Information of China (English)

    王芳

    2008-01-01

    @@ For Teachers: The Wordless Language Spoken by Everyone by Pamela Osment An old saying goes:"Actions speak louder than words."That's true according to communication experts.Some studies show that up to 90 percent of communication is nonverbal.Though you might say one thing,your body movements may indicate something entirely different.This nonverbal way of communicating is called body language.The Universal(通用的)Language

  9. 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

  10. Five-order SRSs and supercontinuum generation from a tapered tellurite microstructured fiber with longitudinally varying dispersion

    Science.gov (United States)

    Liao, Meisong; Yan, Xin; Gao, Weiqing; Duan, Zhongchao; Qin, Guanshi; Suzuki, Takenobu; Ohishi, Yasutake

    2011-08-01

    We try to obtain stable supercontinuum (SC) generation with broad bandwidth under relative simple pump conditions. We use a 1.3-m-long highly nonlinear tellurite microstructured fiber and pump it by a 15 ps 1064 nm fiber laser. One segment of the fiber is tapered from a core diameter of 3.4 μm to 1.3 μm. For the first time five-order stimulated Raman scatterings (SRSs) are observed for soft glass fibers. SC covering 730-1700 nm is demonstrated with the pump-pulse-energy of several nJ. The mechanisms of SC broadening are mainly SRS, self-phase modulation (SPM) and cross phase modulation (XPM). The tapered segment has two advantages. Firstly it increases the nonlinearity of fiber by several times. Secondly, it acts as a compensation for the dispersion of the untapered segment, and mitigates the walk-off between pump pulse and SRS peaks.

  11. SERS Taper-Fiber Nanoprobe Modified by Gold Nanoparticles Wrapped with Ultrathin Alumina Film by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Wenjie Xu

    2017-02-01

    Full Text Available A taper-fiber SERS nanoprobe modified by gold nanoparticles (Au-NPs with ultrathin alumina layers was fabricated and its ability to perform remote Raman detection was demonstrated. The taper-fiber nanoprobe (TFNP with a nanoscale tip size under 80 nm was made by heated pulling combined with the chemical etching method. The Au-NPs were deposited on the TFNP surface with the electrostatic self-assembly technology, and then the TFNP was wrapped with ultrathin alumina layers by the atomic layer deposition (ALD technique. The results told us that with the increasing thickness of the alumina film, the Raman signals decreased. With approximately 1 nm alumina film, the remote detection limit for R6G aqueous solution reached 10−6 mol/L.

  12. Growth of tapered silica nanowires with a shallow U-shaped vapor chamber: Growth mechanism and structural and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Danqing; Zhang, Xi, E-mail: xizhang@scu.edu.cn; Wei, Jianglin; Gu, Gangxu; Xiang, Gang, E-mail: gxiang@scu.edu.cn [Department of Physics, Sichuan University, Chengdu 610064 (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China)

    2015-04-28

    Traditional chemical vapor deposition method modified with a shallow U-shaped vapor chamber has been used to synthesize tapered bamboo shoot-like (BS-like) amorphous SiO{sub 2} nanowires (NWs) on Si (100) substrates without catalyst. The key innovation of this approach lies in a creation of swirling flow of the reactant vapors during the growth, which leads to a harvest of tapered silica NWs with lengths up to several microns. The unique structures and corresponding luminescence properties of the BS-like NWs were studied and their relationship with the evaporated active reactants was explored. A thermodynamic model that considers the critical role of the vapor flow during the growth is proposed to understand the structural and optical features. The shallow U-shaped vapor chamber-aided approach may provide a viable way to tailor novel structure of NWs for potential applications in nano-devices.

  13. Generation of parabolic similaritons in tapered silicon photonic wires: comparison of pulse dynamics at telecom and mid-infrared wavelengths.

    Science.gov (United States)

    Lavdas, Spyros; Driscoll, Jeffrey B; Jiang, Hongyi; Grote, Richard R; Osgood, Richard M; Panoiu, Nicolae C

    2013-10-01

    We study the generation of parabolic self-similar optical pulses in tapered Si photonic nanowires (Si-PhNWs) at both telecom (λ=1.55 μm) and mid-infrared (λ=2.2 μm) wavelengths. Our computational study is based on a rigorous theoretical model, which fully describes the influence of linear and nonlinear optical effects on pulse propagation in Si-PhNWs with arbitrarily varying width. Numerical simulations demonstrate that, in the normal dispersion regime, optical pulses evolve naturally into parabolic pulses upon propagation in millimeter-long tapered Si-PhNWs, with the efficiency of this pulse-reshaping process being strongly dependent on the spectral and pulse parameter regime in which the device operates, as well as the particular shape of the Si-PhNWs.

  14. 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.

  15. Growth of tapered silica nanowires with a shallow U-shaped vapor chamber: Growth mechanism and structural and optical properties

    Science.gov (United States)

    Zhang, Danqing; Zhang, Xi; Wei, Jianglin; Gu, Gangxu; Xiang, Gang

    2015-04-01

    Traditional chemical vapor deposition method modified with a shallow U-shaped vapor chamber has been used to synthesize tapered bamboo shoot-like (BS-like) amorphous SiO2 nanowires (NWs) on Si (100) substrates without catalyst. The key innovation of this approach lies in a creation of swirling flow of the reactant vapors during the growth, which leads to a harvest of tapered silica NWs with lengths up to several microns. The unique structures and corresponding luminescence properties of the BS-like NWs were studied and their relationship with the evaporated active reactants was explored. A thermodynamic model that considers the critical role of the vapor flow during the growth is proposed to understand the structural and optical features. The shallow U-shaped vapor chamber-aided approach may provide a viable way to tailor novel structure of NWs for potential applications in nano-devices.

  16. High-temperature sensor based on an abrupt-taper Michelson interferometer in single-mode fiber.

    Science.gov (United States)

    Xu, Le; Jiang, Lan; Wang, Sumei; Li, Benye; Lu, Yongfeng

    2013-04-01

    This study proposes a high-temperature sensor based on an abrupt fiber-taper Michelson interferometer (FTMI) in single-mode fiber fabricated by a fiber-taper machine and electric-arc discharge. The proposed FTMI is applied to measure temperature and refractive index (RI). A high temperature sensitivity of 118.6 pm/°C is obtained in the temperature range of 500°C-800°C. The wavelength variation is only -0.335 nm for the maximum attenuation peak, with the external RI changed from 1.333 to 1.3902, which is desirable for high-temperature sensing to eliminate the cross sensitivity to RI.

  17. Investigation of Nucleation Mechanism and Tapering Observed in ZnO Nanowire Growth by Carbothermal Reduction Technique.

    Science.gov (United States)

    Kar, Ayan; Low, Ke-Bin; Oye, Michael; Stroscio, Michael A; Dutta, Mitra; Nicholls, Alan; Meyyappan, M

    2011-12-01

    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.

  18. Low-temperature tapered-fiber probing of diamond NV ensembles coupled to GaP microcavities

    CERN Document Server

    Fu, K -M C; Santori, C; Faraon, A; Beausoleil, R G

    2011-01-01

    In this work we present a platform for testing the device performance of a cavity-emitter system, using an ensemble of emitters and a tapered optical fiber. This method provides high-contrast spectra of the cavity modes, selective detection of emitters coupled to the cavity, and an estimate of the device performance in the single- emitter case. Using nitrogen-vacancy (NV) centers in diamond and a GaP optical microcavity, we are able to tune the cavity onto the NV resonance at 10 K, couple the cavity-coupled emission to a tapered fiber, and measure the fiber-coupled NV spontaneous emission decay. Theoretically we show that the fiber-coupled average Purcell factor is 2-3 times greater than that of free-space collection; although due to ensemble averaging it is still a factor of 3 less than the Purcell factor of a single, ideally placed center.

  19. Microstructural features in fractured high nitrogen stainless steel hip prostheses: a retrieval study of polished, tapered femoral stems.

    Science.gov (United States)

    Swarts, Eric; Kop, Alan; Jones, Noel; Keogh, Cathie; Miller, Susan; Yates, Piers

    2008-03-01

    Six fractured high nitrogen stainless steel (HNSS), polished, tapered hip stems have been reviewed for analysis. Clinical data suggests that poor proximal support (loosening), varus positioning, and canal morphology are implicated in the failure of these stems. Metallurgical assessment reveals a number of microstructural deficiencies contributing to failure. Of significance is poor grain homogeneity and larger grain size near the surface of the fractured stems. It appears some polished, tapered HNSS stems are at risk when combinations of these clinical and metallurgical features occur. As the control of grain size, microstructural uniformity, and inclusion content are critical for optimum mechanical performance, it is important the manufacturers review processing methods to further minimize the risk of component failure.

  20. 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.

  1. Signifying Bodies

    DEFF Research Database (Denmark)

    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...... of, for example, how rheumatoid arthritis sufferers view their treatment, how decisions are made in simulated emergencies, and how therapists and homeopaths use distributed language and cognition with their clients....

  2. 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 ...

  3. Development and First Results of the Width-Tapered Beam Method for Adhesion Testing of Photovoltaic Material Systems

    Energy Technology Data Exchange (ETDEWEB)

    Bosco, Nick; Tracy, Jared; Dauskardt, Reinhold; Kurtz, Sarah

    2016-11-21

    A fracture mechanics based approach for quantifying adhesion at every interface within the PV module laminate is presented. The common requirements of monitoring crack length and specimen compliance are circumvented through development of a width-tapered cantilever beam method. This technique may be applied at both the module and coupon level to yield a similar, quantitative, measurement. Details of module and sample preparation are described and first results on field-exposed modules deployed for over 27 years presented.

  4. Changes in selected biochemical, muscular strength, power, and endurance measures during deliberate overreaching and tapering in rugby league players.

    Science.gov (United States)

    Coutts, A; Reaburn, P; Piva, T J; Murphy, A

    2007-02-01

    The purpose of this study was to examine the influence of overreaching on muscle strength, power, endurance and selected biochemical responses in rugby league players. Seven semi-professional rugby league players (.VO(2max) = 56.1 +/- 1.7 mL . kg (-1) . min (-1); age = 25.7 +/- 2.6 yr; BMI = 27.6 +/- 2.0) completed 6 weeks of progressive overload training with limited recovery periods. A short 7-day stepwise reduction taper immediately followed the overload period. Measures of muscular strength, power and endurance and selected biochemical parameters were taken before and after overload training and taper. Multistage fitness test running performance was significantly reduced (12.3 %) following the overload period. Although most other performance measures tended to decrease following the overload period, only peak hamstring torque at 1.05 rad . s (-1) was significantly reduced (p taper, a significant increase in peak hamstring torque and isokinetic work at both slow (1.05 rad . s (-1)) and fast (5.25 rad . s (-1)) movement velocities were observed. Minimum clinically important performance decreases were measured in a multistage fitness test, vertical jump, 3-RM squat and 3-RM bench press and chin-up (max) following the overload period. Following the taper, minimum clinically important increases in the multistage fitness test, vertical jump, 3-RM squat and 3-RM bench press and chin-up (max) and 10-m sprint performance were observed. Compared to resting measures, the plasma testosterone to cortisol ratio, plasma glutamate, plasma glutamine to glutamate ratio and plasma creatine kinase activity demonstrated significant changes at the end of the overload training period (p < 0.05). These results suggest that muscular strength, power and endurance were reduced following the overload training, indicating a state of overreaching. The most likely explanation for the decreased performance is increased muscle damage via a decrease in the anabolic-catabolic balance.

  5. 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.

  6. The Cost Effectiveness of Tapered versus Abrupt Discontinuation of Oral Cyclosporin Microemulsion for the Treatment of Psoriasis

    OpenAIRE

    Leona Hakkaart-van Roijen; Paul Verboom; W. Ken Redekop; Karien R. Touw; Rutten, Frans F. H.

    2001-01-01

    Objective: To assess the cost effectiveness of tapered versus abrupt discontinuation of a microemulsion formulation of cyclosporin in patients with chronic plaque psoriasis. Methods: A cost-effectiveness analysis was performed in parallel with a nonblind, multicentre, international clinical trial of the safety and efficacy of intermittent short courses of cyclosporin. Direct and indirect costs were considered within a 1-year period following randomisation. Patients: Patients with chronic plaq...

  7. The efficacy of the self-adjusting file and ProTaper for removal of calcium hydroxide from root canals

    Directory of Open Access Journals (Sweden)

    Gisele Faria

    2013-07-01

    Full Text Available OBJECTIVE: The goal of this study was to evaluate the efficacy of the Self-Adjusting File (SAF and ProTaper for removing calcium hydroxide [Ca(OH2] from root canals. MATERIAL AND METHODS: Thirty-six human mandibular incisors were instrumented with the ProTaper system up to instrument F2 and filled with a Ca(OH2-based dressing. After 7 days, specimens were distributed in two groups (n=15 according to the method of Ca(OH2 removal. Group I (SAF was irrigated with 5 mL of NaOCl and SAF was used for 30 seconds under constant irrigation with 5 mL of NaOCl using the Vatea irrigation device, followed by irrigation with 3 mL of EDTA and 5 mL of NaOCl. Group II (ProTaper was irrigated with 5 mL of NaOCl, the F2 instrument was used for 30 seconds, followed by irrigation with 5 mL of NaOCl, 3 mL of EDTA, and 5 mL of NaOCl. In 3 teeth Ca(OH2 was not removed (positive control and in 3 teeth canals were not filled with Ca(OH2 (negative control. Teeth were sectioned and prepared for the scanning electron microscopy. The amounts of residual Ca(OH2 were evaluated in the middle and apical thirds using a 5-score system. RESULTS: None of the techniques completely removed the Ca(OH2 dressing. No difference was observed between SAF and ProTaper in removing Ca(OH2 in the middle (P=0.11 and the apical (P=0.23 thirds. CONCLUSION: The SAF system showed similar efficacy to rotary instrument for removal of Ca(OH2 from mandibular incisor root canals.

  8. Apical root canal transportation of different pathfinding systems and their effects on shaping ability of ProTaper Next

    OpenAIRE

    Turker, Sevinc Aktemur; Uzunoglu, Emel

    2015-01-01

    Background This study aimed to compare glide path preparation of different pathfinding systems and their effects on the apical transportation of ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland) in mesial root canals of extracted human mandibular molars, using digital subtraction radiography. Material and Methods The mesial canals of 40 mandibular first molars (with curvature angles between 25° and 35°) were selected for this study. The specimens were divided randomly into 4 groups ...

  9. Effectiveness of ProTaper retreatment system associated with organic solvents in the removal of root canal filling material

    OpenAIRE

    Guiotti, Flávia Angélica [UNESP; Kuga, Milton Carlos; Renato de Toledo LEONARDO; Gisselle Moraima CHÁVEZ-ANDRADE; Magro, Miriam Graziele [UNESP; Cavenago, Bruno Cavalini; Faria, Gisele

    2013-01-01

    Aim: To evaluate the effectiveness of ProTaper universal retreatment system in the removal of root canal filling material with thermomechanical compaction, in comparison to manualmechanical technique, associated with orange oil or eucalyptol. Materials and methods: Forty extracted lower incisors were filled with thermomechanical compaction technique. After 3 years, the root canal filling was removed by: G1 - manualmechanical technique with orange oil; G2 - manual-mechanical technique with euc...

  10. Comparison of the cleaning capacity of Mtwo and Pro Taper rotary systems and manual instruments in primary teeth

    OpenAIRE

    Mohammad Reza Azar; Laya Safi; Afshin Nikaein

    2012-01-01

    Background: Root canal cleaning is an important step in endodontic therapy. In order to develop better techniques, a new generation of endodontic instruments has been designed. The aim of this study was to compare the effectiveness of manual K-files (Mani Co, Tokyo, Japan) and two rotary systems-Mtwo (Dentsply-Maillefer, Ballaigues, Switzerland) and ProTaper (VDW, Munich, Germany)-for root canal preparation in primary molars. Materials and Methods: India ink was injected to 160 mesiobucca...

  11. 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.

  12. Body parts

    Science.gov (United States)

    Ayiter, Elif

    2010-01-01

    In this project, the artist wishes to examine corporeality in the virtual realm, through the usage of the (non)-physical body of the avatar. An art installation created in the virtual world of Second Life, which is meant to be accessed with site specific avatars, will provide the creative platform whereby this investigation is undertaken. Thus, "body parts" seeks to challenge the residents of virtual environments into connecting with the virtual manifestations, i.e., avatars of others in an emotionally expressive/intimate manner.

  13. 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.

  14. The tension sensor of Photonic Crystal Fiber based on core-offset splicing and waist-enlarged fiber taper

    Science.gov (United States)

    Fu, Guangwei; Li, Qifeng; Li, Yunpu; Yang, Jiandong; Fu, Xinghu; Bi, Weihong; Li, Yanjun

    2016-10-01

    A tension sensor of Photonic Crystal Fiber(PCF) is presented based on core-offset splicing and waist-enlarged fiber taper. The tension response characteristics of the sensor are studied experimentally. To analyzing the modal interference, many samples with different PCF lengths between the two splicing areas, different core-offset distances and different waist-enlarged fiber taper diameters are fabricated and tested. When the tension range is 0 to 4000μɛ, the results show that the spectrum is blue shift with the increasing of the axial tension. The sensitivity is-2.1 pm/μɛ. The experimental results show that the tension sensitivity can be not influenced by the PCF lengths, the core-offset distances.The waist-enlarged fiber taper diameters and the tension sensor is very sensitive to axial tension and the relationship between the wavelength shift and tension is linearity. To determine the number of the interfering modes, the transmission spectra of these sensor is transformed by the fast fourier transform (FFT) method. There are several peaks in the spatial frequency spectra at these sensors. Only one cladding mode is dominantly excited, while the other cladding modes are weak. The spatial frequency is proportional to the differential mode group index. Compared with the traditional fiber sensor, this sensor has some advantages including the easily fabricated, simple structure and high sensitivity. It can be used in industrial production, building monitoring, aerospace and other fields.

  15. Effects of design parameters on carrying capacity of a double-row tapered roller slewing bearing used in wind turbine

    Directory of Open Access Journals (Sweden)

    Yunfeng Li

    2016-07-01

    Full Text Available Mechanical model with detailed design parameters of a rotor slewing bearing with the structure type of double-row tapered roller for supporting the rotor of the wind turbine was presented. The internal geometrical relationships of the rotor slewing bearing were established in the Cartesian coordinate system. The elastic contact deformations between each tapered roller and the raceways were expressed through the geometrical transformation. The mechanical model was established using the equilibrium relations in the rotor slewing bearing. The safety factor and the fatigue life which represents, respectively, the ability of resisting the rolling contact plastic deformation failure and the rolling contact fatigue failure of the rotor slewing bearing were obtained based on the solution of the mechanical model. Effects of the detailed design parameters such as axial clearance, contact angle, and roller semi-cone angle on the carrying capacity of the rotor slewing bearing were analyzed. The results show that right amount of small negative axial clearance, increase in contact angle, and decrease in roller semi-cone angle are advantageous for enhancing the carrying capacity of the rotor slewing bearing. This provides the basis for the reasonable value selection of the design parameters of the double-row tapered roller slewing bearing for supporting the rotor of the wind turbine.

  16. Deriving Merchantable Volume in Poplar through a Localized Tapering Function from Non-Destructive Terrestrial Laser Scanning

    Directory of Open Access Journals (Sweden)

    Yuan Sun

    2016-04-01

    Full Text Available Timber volume is an important ecological component in forested landscapes. The application of terrestrial laser scanning (TLS to volume estimation has been widely accepted though few species have well-calibrated taper functions. This research uses TLS technology in poplar (Populus × canadensis Moench cv. ‘I-72/58’ to extract stem diameter at different tree heights and establish the relationship between point cloud data and stem curve, which constitutes the basis for volume estimation of single trees and the stand. Eight plots were established and scanned by TLS. Stem curve functions were then fitted after extraction of diameters at different height, and tree heights from the point cloud data. Lastly, six functions were evaluated by R2 and RMSE. A modified Schumacher equation was the most suitable taper function. Volume estimates from the TLS-derived taper function were better than those derived using the stem-analysis data. Finally, regression analysis showed that predictions of stem size were similar when data were based on TLS versus stem analysis. Its high accuracy and efficiency indicates that TLS technology can play an important role in forest inventory assessment.

  17. 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.

  18. 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.

  19. Sputtered Pt electrode structures with smoothly tapered edges by bi-layer resist lift-off

    Energy Technology Data Exchange (ETDEWEB)

    Preiss, Elisabeth M., E-mail: elisabeth.preiss@de.bosch.com [Robert Bosch GmbH, Corporate Sector Research and Advance Engineering, Robert-Bosch-Campus 1, 71272 Renningen (Germany); Saarland University, Lab for Micromechanics, Microfluidics, and Microactuators, 66123 Saarbruecken (Germany); Krauss, Andreas [Robert Bosch GmbH, Corporate Sector Research and Advance Engineering, Robert-Bosch-Campus 1, 71272 Renningen (Germany); Seidel, Helmut [Saarland University, Lab for Micromechanics, Microfluidics, and Microactuators, 66123 Saarbruecken (Germany)

    2015-12-31

    A lift-off process using a bi-layer resist consisting of an image reversal resist on top and a lift-off resist at the bottom was used to structure Ti–Pt thin films. DC magnetron sputtered metal films patterned by this process show ultra smooth edges, ideal for applications such as interdigitated electrodes in resistive gas sensors including thin-film based sensitive coatings with thicknesses below 100 nm. Profiles of processed structures were analyzed by scanning electron microscopy and surface profilometer. The thickness profile and structure width were controlled by using different resist thicknesses and undercut lengths. Results were compared with iterative simulations by a geometric shadowing model, predicting undersputtering length and profile structure of the experimentally manufactured samples in good agreement. Target-to-substrate distance variation was found to have only a minor influence on the sputtering result. - Highlights: • Ti–Pt electrode structures were prepared using sputtering bi-layer-resist lift-off. • Prepared lift-off electrodes can be used for good overgrowth of thin films. • Ultra-smoothly tapered edges were controlled by the process parameters. • Simulations using a geometric shadowing model confirm our experimental results.

  20. 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.

  1. Adiabatically tapered hyperbolic metamaterials for dispersion control of high-k waves.

    Science.gov (United States)

    West, Paul R; Kinsey, Nathaniel; Ferrera, Marcello; Kildishev, Alexander V; Shalaev, Vladimir M; Boltasseva, Alexandra

    2015-01-14

    Hyperbolic metamaterials (HMMs) have shown great promise in the optical and quantum communities due to their extremely large, broadband photonic density of states. This feature is a direct consequence of supporting photonic modes with unbounded k-vectors. While these materials support such high-k waves, they are intrinsically confined inside the HMM and cannot propagate into the far-field, rendering them impractical for many applications. Here, we demonstrate how the magnitude of k-vectors can be engineered as the propagating radiation passes through media of differing dispersion relations (including type II HMMs and dielectrics) in the in-plane direction. The total outcoupling efficiency of waves in the in-plane direction is shown to be on average 2 orders of magnitude better than standard out-of-plane outcoupling methods. In addition, the outcoupling can be further enhanced using a proposed tapered HMM waveguide that is fabricated using a shadowed glancing angle deposition technique; thereby proving the feasibility of the proposed device. Applications for this technique include converting high-k waves to low-k waves that can be out-coupled into free-space and creating extremely high-k waves that are quickly quenched. Most importantly, this method of in-plane outcoupling acts as a bridge through which waves can cross between the regimes of low-k waves in classical dielectric materials and the high-k waves in HMMs with strongly reduced reflective losses.

  2. Compact Elliptically Tapered Slot Antenna with Non-uniform Corrugations for Ultra-wideband Applications

    Directory of Open Access Journals (Sweden)

    F. G. Zhu

    2013-04-01

    Full Text Available A small size elliptically tapered slot antenna (ETSA fed by coplanar waveguide (CPW for ultra-wideband (UWB applications is proposed. It is printed on an FR4 substrate and occupies a size of 37×34×0.8 mm^3. A pair of quarter circular shapes is etched on the radiator to reduce the size. To overcome the limitation of uniform corrugation, non-uniform corrugation is utilized to reduce the cross-polarization level. A parametric study is carried out to investigate the effects of circular cut and corrugations. In order to validate the design, a prototype is fabricated and measured. Both simulated and measured results confirm that the proposed antenna achieves a good performance of a reflection coefficient below -10 dB from 3.1 GHz to 10.6 GHz, including a maximum antenna gain of 8.1dBi, directional patterns in the end-fire direction, low cross-polarization level below -20 dB and linear phase response. The antenna is promising for applications in UWB impulse radar imaging.

  3. 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.

  4. Step-tapered operation of the FEL: efficiency enhancement and two-colour operation

    Science.gov (United States)

    Jaroszynski, D. A.; Prazeres, R.; Glotin, F.; Marcouillé, O.; Ortega, J. M.; Oepts, D.; van der Meer, A. F. G.; Knippels, G. M. H.; van Amersfoort, P. W.

    1996-02-01

    We present measurements of the temporal and spectral properties of radiation produced from the step-tapered undulator infrared free-electron lasers (FELs), CLIO in France and FELIX in the Netherlands. Using a two section undulator with independently adjustable deflection parameters, K, the FEL will operate either with an enhanced efficiency and improved spectral properties (with a small positive ΔK step) or simultaneously at two frequencies (for large ΔK). Using a dispersion-free hole output coupler the maximum wavelength difference {δλ}/{λ}, has now been extended to more than {δλ}/{λ} ≈ 0.6. We also present measurements that show that the FEL FELIX will produce significant power simultaneously at two wavelengths by coherent spontaneous emission when the wavelength is long and the electron bunch is short. The efficiency, spectral and temporal properties have been measured. We show that at the maximum efficiency, ΔK ≈ 0.02, the optical pulses generated are smooth and close to Fourier transform limited. By adjusting ΔK the optical pulse duration can be varied by a factor of 2 or more and sidebands due to synchrotron oscillations can be suppressed.

  5. 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.

  6. Evaluation of factors that allow the clinician to taper inhaled corticosteroids in childhood asthma

    Directory of Open Access Journals (Sweden)

    Kentaro Matsuda

    1999-01-01

    Full Text Available Inhaled corticosteroids are potent and effective treatment agents for controlling symptoms of childhood asthma. However, there are no predictive factors that help to determine which patients with asthma are likely to be tapered off inhaled corticosteroids successfully. We examined whether any factor or combination of factors could help the clinician safely discontinue inhaled steroid therapy. Thirty-six asthmatic children whose symptoms were stable on low-dose beclomethasone dipropionate (BDP were divided by parental choice into two groups: maintenance BDP (n = 11 and no BDP (n = 25. Methacholine inhalation tests were performed at the beginning of the study and after 1 month. Twelve children (48% who had BDP discontinued developed exacerbations after 2–3 months, whereas there were no problems in the maintenance group. The no BDP group was retrospectively divided into two subgroups: exacerbation (+ and (−. The threshold to methacholine in the exacerbation (+ subgroup decreased significantly in advance of clinical symptoms. The two subgroups were analyzed statistically by two-group discriminant function analysis. The change in threshold to methacholine, the dose and potency of drugs, duration of asthma and gender (female correlated with exacerbation. These results suggest that discontinuation of inhaled steroids should be done carefully, even in stable asthmatic children. The methacholine inhalation test, gender, drugs and history may be used as references for discontinuing inhaled steroids.

  7. Tapered Glass-Fiber Microspike: High-Q Flexural Wave Resonator and Optically Driven Knudsen Pump

    Science.gov (United States)

    Pennetta, Riccardo; Xie, Shangran; Russell, Philip St. J.

    2016-12-01

    Appropriately designed optomechanical devices are ideal for making ultra-sensitive measurements. Here we report a fused-silica microspike that supports a flexural resonance with a quality factor greater than 100 000 at room temperature in vacuum. Fashioned by tapering single-mode fiber (SMF), it is designed so that the core-guided optical mode in the SMF evolves adiabatically into the fundamental mode of the air-glass waveguide at the tip. The very narrow mechanical linewidth (20 mHz) makes it possible to measure extremely small changes in resonant frequency. In a vacuum chamber at low pressure, the weak optical absorption of the glass is sufficient to create a temperature gradient along the microspike, which causes it to act as a microscopic Knudsen pump, driving a flow of gas molecules towards the tip where the temperature is highest. The result is a circulating molecular flow within the chamber. Momentum exchange between the vibrating microspike and the flowing molecules causes an additional restoring force that can be measured as a tiny shift in the resonant frequency. The effect is strongest when the mean free path of the gas molecules is comparable with the dimensions of the vacuum chamber. The system offers a novel means of monitoring the behavior of weakly absorbing optomechanical sensors operating in vacuum.

  8. 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.

  9. 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.

  10. Comparison of ProTaper and Mtwo retreatment systems in the removal of resin-based root canal obturation materials during retreatment.

    Science.gov (United States)

    Iriboz, Emre; Sazak Öveçoğlu, Hesna

    2014-04-01

    To evaluate the effectiveness of the ProTaper and Mtwo retreatment systems for removal of resin-based obturation techniques during retreatment. A total of 160 maxillary anterior teeth were enlarged to size 30 using ProTaper and Mtwo rotary instruments. Teeth were randomly divided into eight groups. Resilon + Epiphany, gutta-percha + Epiphany, gutta-percha + AH Plus and gutta-percha + Kerr Pulp Canal Sealer (PCS) combinations were used for obturation. ProTaper and Mtwo retreatment files were used for removal of root canal treatments. After clearing the roots, the teeth were split vertically into halves, and the cleanliness of the canal walls was determined by scanning electron microscopy. Specimens obturated with gutta-percha and Kerr PCS displayed significantly more remnant obturation material than did specimens filled with resin-based obturation materials. Teeth prepared with Mtwo instruments contained significantly more remnant filling material than did teeth prepared with ProTaper. ProTaper files were significantly faster than Mtwo instruments in terms of the mean time of retreatment and time required to reach working length. The Resilon + Epiphany and AH Plus + gutta-percha obturation materials were removed more easily than were the Epiphany + gutta-percha and Kerr PCS + gutta-percha obturation materials. Although ProTaper retreatment files worked faster than did Mtwo retreatment files in terms of removing root canal obturation materials, both retreatment systems are effective, reliable and fast.

  11. 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

  12. Sacralising Bodies

    DEFF Research Database (Denmark)

    Kaur, Ravinder

    2010-01-01

    In post-revolution Iran, the sacred notion of martyrdom has been transformed into a routine act of government – a moral sign of order and state sovereignty. Moving beyond the debates of the secularisation of the sacred and the making sacred of the secular, this article argues that the moment...... of 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......-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...

  13. Carotid stenting using tapered and nontapered stents: associated neurological complications and restenosis rates.

    Science.gov (United States)

    Brown, Katherine E; Usman, Asad; Kibbe, Melina R; Morasch, Mark D; Matsumura, Jon S; Pearce, William H; Amaranto, Daniel J; Eskandari, Mark K

    2009-01-01

    Self-expanding stent design systems for carotid artery stenting (CAS) have morphed from nontapered (NTS) to tapered (TS); however, the impact of this change is unknown. We reviewed the outcomes of CAS with these two broad categories of stents in a single-center retrospective review of 308 CAS procedures from May 2001 to July 2007. Nitinol self-expanding TS or NTS coupled with cerebral embolic protection devices were used to treat extracranial carotid occlusive disease. Data analysis included demographics, procedural records, duplex exams, and conventional arteriography. Mean follow-up was 18 months (range 1-69). Restenosis was defined as >or=80% in-stent carotid artery stenosis by angiography. The mean age of the entire cohort was 71.3 years (75% men, 25% women). Of the 308 cases, 233 were de novo lesions and 75 had a prior ipsilateral carotid endarterectomy (n = 44) or external beam radiation exposure (n = 31). Preprocedure neurological symptoms were present in 30% of patients. TS were used in 156 procedures and NTS in 152 procedures. The 30-day ipsilateral stroke and death rates were 1.3% and 0.3%, respectively. An additional three (1.0%) posterior circulation strokes occurred. There was no statistically significant difference in the 30-day total stroke rates between TS (3.2%, n = 5) and NTS (1.3%, n = 2) (p = 0.5). At midterm follow-up, restenosis or asymptomatic occlusion was detected in eight cases (2.6%). All occurred in arteries treated with NTS, and this was statistically different when compared to arteries treated with TS (p = 0.03). Furthermore, a post-hoc subgroup analysis revealed significant correlation (chi(2) = 0.02) for restenosis in "hostile necks" when separated by TS vs. NTS. Early CAS outcomes between TS and NTS are comparable. In contrast, self-expanding nitinol TS may have a lower incidence of significant restenosis or asymptomatic occlusion when compared to NTS.

  14. Evaluation of Capacity of Essential Oils in Dissolving ProTaper Universal Gutta-Percha points

    Science.gov (United States)

    Ramos, Thaís Isabel Ferreira; Câmara, Andréa Cruz

    2016-01-01

    Purpose Solvents may be used to remove the filling materials. The purpose of this in vitro study was to evaluate and compare the efficacy of formulated orange oil, orange oil and formulated eucalyptol in dissolving F3 ProTaper Universal Gutta-percha points. Material and methods 200 samples were used and divided into four groups, further divided in fifty samples for each solvent. The samples were weighed on an analytical balance before being subjected to the action of solvents. Subsequently, they were put onto watch glasses, 7X45mm in length, and immersed into solutions for the following times: 5, 10, 20, 25 and 30 minutes. The loss of mass was recorded by weighing samples after every minute of action of the solvent on the points. Data were statistically analyzed by Kruskal-Wallis test at a significance level of 5%. Results All solvents showed that the first five minutes of action was the period of greatest dissolving power. In terms of immersion time, xylol (control group) exhibited a markedly superior ability in dissolving the gutta-percha points compared to other solvents and, also, showed statistically significant differences. A continuous dissolution was observed in all groups. Formulated orange oil presented a markedly superior solvent effect on filling materials compared to orange oil and formulated eucalyptol; however, there were no statistically significant differences. Conclusion Considering the results obtained and methodology employed, it can be concluded that xylol was the most effective solvent in dissolving gutta-percha points, followed by formulated orange oil, orange oil and formulated eucalyptol oil. PMID:27789910

  15. Effect of Preparation Taper, Height and Marginal Design Under Varying Occlusal Loading Conditions on Cement Lute Stress: A Three Dimensional Finite Element Analysis.

    Science.gov (United States)

    Tripathi, Siddhi; Amarnath, Gowdagere Shamanna; Muddugangadhar, Byrasandra Channapa; Sharma, Ashish; Choudhary, Suchismita

    2014-12-01

    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, vertical point load distributed axial load. The maximum shear stress and Von Mises stress within the cement lute were recorded. The maximum shear stresses ranged from 1.70 to 3.93 MPa (horizontal point loading), 0.66 to 3.04 MPa (vertical point loading), 0.38 to 0.87 MPa (distributed loading). The maximum Von Mises stresses ranged from 3.39 to 10.62 MPa (horizontal point loading), 1.93 to 8.58 MPa (vertical point loading) and 1.49 to 3.57 MPa (distributed loading). The combination of 10° taper and 5 mm height had the lowest stress field while the combination of 30° taper and 5 mm height had the highest stress field. Distributed axial loading shows least stress, better stress homogenization and gives a favorable prognosis for the fixed prostheses. Smaller preparation taper of 10° is biomechanically more acceptable than a 30° taper. It is desirable to decrease taper as height increases. The chamfer margin design is associated with greater local cement stresses toward the margins that could place the cement at greater risk for microfracture and failure.

  16. 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

  17. Changes in Muscle Architecture, Explosive Ability, and Track and Field Throwing Performance Throughout a Competitive Season and Following a Taper.

    Science.gov (United States)

    Bazyler, Caleb D; Mizuguchi, Satoshi; Harrison, Alex P; Sato, Kimitake; Kavanaugh, Ashley A; DeWeese, Brad H; Stone, Michael H

    2016-08-26

    The purpose of this study was to examine the effects of an overreach and taper on measures of muscle architecture, jumping, and throwing performance in Division I collegiate throwers preparing for conference championships. Six collegiate track and field throwers (3 hammer, 2 discus, 1 javelin) trained for 12 weeks using a block-periodization model culminating with a one week overreach followed by a 3 week taper (ORT). Session rating of perceived exertion training load (RPETL) and strength training volume-load times bar displacement (VLd) were recorded weekly. Athletes were tested pre- and post-ORT on measures of vastus lateralis architecture, unloaded and loaded squat and countermovement jump performance, underhand and overhead throwing performance, and competition throwing performance. There was a statistical reduction in weight training VLd/session (d=1.21, p<0.05) and RPETL/session (d=0.9, p<0.05) between the in-season and ORT training phases. Five of six athletes improved overhead throw and competition throwing performance following the ORT (d=0.50, p<0.05). Vastus lateralis muscle thickness statistically increased following the in-season training phase (d=0.28, p<0.05), but did not change following the ORT. Unloaded countermovement jump peak force and relative peak power improved significantly following the ORT (d=0.59, p<0.05, d=0.31, p<0.05, respectively). These findings demonstrate that an overreaching week followed by a 3-week taper is an effective means of improving explosive ability and throwing performance in collegiate track and field throwers despite the absence of detectable changes in muscle architecture.

  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. Effectiveness of the self-adjusting file versus ProTaper systems to remove the smear layer in artificially induced internal root resorption cavities

    Directory of Open Access Journals (Sweden)

    Senem Yigit Özer

    2013-01-01

    Full Text Available Aim: Smear layer removal from artificially prepared internal root resorption (IRR cavities using the self-adjusting file (SAF system with activated continuous irrigation or the ProTaper system (Dentsply Maillefer, Ballaigues, Switzerland with conventional syringe/needle irrigation was compared. Materials and methods: Twenty-eight maxillary central incisors were selected, decoronated and 20 of them were randomizedly splited along the coronal plane into labial and lingual sections, and artificial IRR cavities were prepared in both walls. Tooth segments were rejoined and teeth were divided into two groups. Each group (n = 10 was prepared using the SAF or ProTaper system with 12-mL 5.25% NaOCl and 12-mL 17% EDTA. Root canals were prepared in six intact positive control teeth using the SAF or ProTaper system with 5.25% NaOCl and 17% EDTA. As negative controls, two intact teeth were prepared using NaOCl only. Roots were than split longitudinally from the rejoined segments and samples were evaluated under scanning electron microscopy using a five-point scoring system. Results: Most SAF (87% and ProTaper (83% samples (P > 0.05, had scores of 1 and 2 indicating clean canal walls for the IRR cavities. Conclusions: SAF with activated continuous irrigation and ProTaper with conventional syringe/needle irrigation both successfully removed the smear layer from artificially prepared IRR cavities

  20. Efficacy of Twisted File Adaptive, Reciproc and ProTaper Universal Retreatment instruments for root-canal-filling removal: A cone-beam computed tomography study.

    Science.gov (United States)

    Akbulut, Makbule Bilge; Akman, Melek; Terlemez, Arslan; Magat, Guldane; Sener, Sevgi; Shetty, Heeresh

    2016-01-01

    The aim of this study was to evaluate the efficacy of Twisted File (TF) Adaptive, Reciproc, and ProTaper Universal Retreatment (UR) System instruments for removing root-canal-filling. Sixty single rooted teeth were decoronated, instrumented and obturated. Preoperative CBCT scans were taken and the teeth were retreated with TF Adaptive, Reciproc, ProTaper UR, or hand files (n=15). Then, the teeth were rescanned, and the percentage volume of the residual root-canal-filling material was established. The total time for retreatment was recorded, and the data was statistically analyzed. The statistical ranking of the residual filling material volume was as follows: hand file=TF Adaptive>ProTaper UR=Reciproc. The ProTaper UR and Reciproc systems required shorter periods of time for retreatment. Root canal filling was more efficiently removed by using Reciproc and ProTaper UR instruments than TF Adaptive instruments and hand files. The TF Adaptive system was advantageous over hand files with regard to operating time.

  1. On-chip two-mode division multiplexing using tapered directional coupler-based mode multiplexer and demultiplexer

    DEFF Research Database (Denmark)

    Ding, Yunhong; Xu, Jing; Da Ros, Francesco;

    2013-01-01

    Abstract: We demonstrate a novel on-chip two-mode division multiplexing circuit using a tapered directional coupler-based TE0&TE1 mode multiplexer and demultiplexer on the silicon-on-insulator platform. A low insertion loss (0.3 dB), low mode crosstalk (...), and large fabrication tolerance (20 nm) are measured. An on-chip mode multiplexing experiment is carried out on the fabricated circuit with non return-to-zero (NRZ) on-off keying (OOK) signals at 40 Gbit/s. The experimental results show clear eye diagrams and moderate power penalty for both TE0 and TE1...... modes....

  2. Transmission properties of fluorocarbon polymer-coated silver hollow glass waveguide with tapered section for Er:YAG laser light

    Science.gov (United States)

    Wang, You; Hiraga, Hajime; Miura, Daisuke; Kato, Yuji; Miyagi, Mitsunobu

    1996-11-01

    We have succeeded in fabricating low-loss fluorocarbon polymer (FCP)-coated silver hollow glass waveguides by using a liquid-flow coating method. The thickness of a FCP film is strongly dependent on the flow speed and the concentration of FCP solution. It is shown that the optimum condition exists for depositing the polymer to reduce the roughness of layer. The transmission loss of the fabricated waveguide with inner diameter of 700 micrometers is about 0.2 dB/m for Er:YAG laser light. An efficient tapered coupler with a lens is also investigated to couple the laser beam with large diameter to small-bore waveguides.

  3. 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.

  4. High efficiency 600-mW pHEMT distributed power amplifier employing drain impedance tapering technique

    DEFF Research Database (Denmark)

    Narendra, Kumar; Anand, Lokesh; Pragash, Sangaran;

    2008-01-01

    4-stage distributed power amplifier (DPA) employing tapering the drain load networks to achieve high efficiency is reported. The active device with enhancement mode pHEMT (pseudomorphic High Electron Mobility Transistor) technology is used. Measurement results of 600 mW, 30 % of power-aided-effic......-aided-efficiency (PAE) and gain of 10 dB is achieved within frequency range of 10–1800 MHz. Low supply voltage of 4.5 V is used for each device. Good agreement between measured and simulated results is obtained....

  5. 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.

  6. Analysis of the use of tapered graded-index polymer optical fibers for refractive-index Sensors.

    Science.gov (United States)

    Arrue, J; Jiménez, F; Aldabaldetreku, G; Durana, G; Zubia, J; Lomer, M; Mateo, J

    2008-10-13

    The behavior of tapered graded-index polymer optical fibers is analyzed computationally for different refractive indices of the surrounding medium. This serves to clarify the main parameters affecting their possible performance as refractive-index sensors and extends an existing study of similar structures in glass fibers. The ray-tracing method is employed, its specific implementation is explained, and its results are compared with experimental ones, both from our laboratory and from the literature. The results show that the current commercial graded-index polymer optical fibers can be used to measure a large range of refractive indices with several advantages over glass fibers.

  7. Simulation of Variable Viscosity and Jeffrey Fluid Model for Blood Flow Through a Tapered Artery with a Stenosis

    Institute of Scientific and Technical Information of China (English)

    Noreen Sher Akbar; S. Nadeem

    2012-01-01

    Non-Newtonian fluid model for blood flow through a tapered artery with a stenosis and variable viscosity by modeling blood as Jeffrey fluid has been studied in this paper. The Jeffrey fluid has two parameters, the relaxation time A1 and retardation time A2. The governing equations are simplified using the case of mild stenosis. Perturbation method is used to solve the resulting equations. The effects of non-Newtonian nature of blood on velocity profile, temperature profile, wall shear stress, shearing stress at the stenotsis throat and impedance of the artery are discussed. The results for Newtonian fluid are obtained as special case from this model.

  8. Efficient generation of 3.9 W of diffraction-limited green light with spectrally combined tapered diode lasers

    DEFF Research Database (Denmark)

    Müller, André; Jensen, Ole Bjarlin; Andersen, Peter E.

    We propose an efficient concept increasing the power of diode laser systems in the visible spectral range. In comparison with second harmonic generation of single emitters, spectral beam combining with subsequent sum-frequency generation enhances the available power significantly. Combining two...... 1060 nm tapered diode lasers, we achieve a 2.5-3.2 fold increase of green light with a maximum power of 3.9 Watts in a diffraction-limited beam. At this level, diode lasers have a high application potential, for example, within the biomedical field. In order to enhance the power even further, our...... concept can be expanded combining multiple diode lasers....

  9. 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.

  10. 应用 ProTaper 镍钛系统去除根管内牙胶%Removal of gutta percha in root canal therapy with Pro Taper nickel titanium system

    Institute of Scientific and Technical Information of China (English)

    刘颖; 曹伟; 杨春山; 刘彩霞

    2016-01-01

    目的:评价不同方法去除根管内牙胶的效果。方法选取60颗下颌前磨牙,逐步后退法预备根管,AH-plus 糊剂加牙胶尖冷侧压充填,保存2周后随机分为3组,每组20颗离体牙。A 组使用不锈钢器械联合氯仿治疗,B 组使用 ProTaper 镍钛系统治疗,C 组使用 ProTaper 镍钛系统联合显微镜下超声冲洗,分别去除根管内的充填物。记录各组的工作所用时间,并观察3组根管壁的清洁度。结果C 组所用时间和根尖孔碎屑量均明显低于 A 组和 B 组,差异具有统计学意义(P <0.05),C 组根管壁的清洁度明显优于 A 组和 B 组,差异均具有统计学意义(P <0.05)。结论根管再治疗中,配合使用显微超声技术可提高机用镍钛器械工作效率,提高根管壁的清洁度。%Objective To evaluate the results of different methods in removing the root canal gutta percha.Methods Select 60 man-dibular premolars with step-back techinique during root canal prepartion,and the mandibular premolars were stored for 2 weeks after AH-plus paste and gutta percha cold lateral condensation.And then they were randomly divided into 3 groups to remove the root canal filling.Group A were given manually cleaning and shaping with stainless steel instruments combined with chloroform.Group B were given Pro Taper nickel ti-tanium system.Group C were given Pro Taper nickel titanium system combined with microscopic ultrasound technology.The completion time of the 3 groups were recorded and the root canal wall cleanliness of the 3 groups were carefully observed.Results The competition time and amount of debris of apical foramen in group C were both significantly less than those of group A and group B,with statistically significant difference (P <0.05).And the cleanliness of root canal wall of group A was significantly better than that of group A and group B (P <0.05). Conclusion During the root canal retreatment,mechanically use

  11. 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.

  12. 三种根管预备器械预备根管根尖碎屑推出量和根管清理能力的比较%Self-adjusting files, ProTaper Next and ProTaper Universal:a comparative study of root canal cleanness and the amount of apically extruded debris during root canal preparation

    Institute of Scientific and Technical Information of China (English)

    伍婉翠; 陈广盛

    2015-01-01

    BACKGROUND:Amount of debris extruded apicaly is an important indicator to evaluate the effect of root canal preparation instrument. Studies have shown that debris extruded apicaly can cause post-treatment pain, and thus, reducing the amount of debris extruded apicaly can decrease the incidence of post-treatment pain. OBJECTIVE:To compare the root canal cleanness and the amount of apicaly extruded debris during root canal preparation with Self-adjusting files, ProTaper Next and ProTaper Universal. METHODS:Forty-five premolars with single canal were divided into three groups randomly, and then prepared by Self-adjusting files, ProTaper Next and ProTaper Universal, respectively. Debris extruded apicaly was colected, dried and weighed. Then roots were longitudinaly sectioned and observed under scanning electronic microscope to evaluate the cleanness of the root canal. RESULTS AND CONCLUSION:The amount of apicaly extruded debris in the ProTaper Universal group was significantly higher than that in the Self-adjusting files group and ProTaper Next group (P 0.05). Scores on debris and smear layer were lower in the group of Self-adjusting files than the groups of ProTaper Next and ProTaper Universal (P 0.05). These findings indicate that the Self-adjusting files and ProTaper Next can extrude less debris beyond the apical foramen, which may decrease the incidence of post-treatment pain. Cleaning ability of Self-adjusting files is better than ProTaper Next and ProTaper Universal.%背景:根尖碎屑推出量是评价根管预备器械预备效果的一项重要指标。研究表明,推出根尖孔的碎屑将引起根管治疗后疼痛,减少根尖区碎屑的推出可降低术后疼痛发生率。目的:比较新型镍钛器械自调节根管锉、ProTaper Next和传统镍钛器械ProTaper Universal预备人下颌单根管前磨牙的根尖碎屑推出量和根管清理能力。方法:将45颗离体人下颌单根管前磨牙随机均分为3组,分别使用新

  13. [Multifaceted body. I. The bodies of medicine].

    Science.gov (United States)

    Saraga, M; Bourquin, C; Wykretowicz, H; Stiefel, F

    2015-02-11

    The human body is the object upon which medicine is acting, but also lived reality, image, symbol, representation and the object of elaboration and theory. All these elements which constitute the body influence the way medicine is treating it. In this series of three articles, we address the human body from various perspectives: medical (1), phenomenological (2), psychosomatic and socio-anthropological (3). This first article discusses four distinct types of representation of the body within medicine, each related to a specific epistemology and shaping a distinct kind of clinical legitimacy: the body-object of anatomy, the body-machine of physiology, the cybernetic body of biology, the statistical body of epidemiology.

  14. Evaluación in vitro de la fractura de los instrumentos rotatorios Mtwo® y ProTaper®

    Directory of Open Access Journals (Sweden)

    Sandra Bibiana Rodríguez Gutiérrez

    2012-11-01

    Full Text Available Introducción: el éxito del tratamiento endodóntico depende dela eliminación de los microorganismos con la preparación quimiomecánica. Los instrumentos rotatorios de Níquel-Titanio ofrecenuna mayor flexibilidad y eficiencia en el corte, pero la fracturade estos puede ocurrir inesperadamente por fatiga del metal.Objetivo: determinar in vitro el primer instrumento que presentefractura y el número de usos antes de observarla en los sistemasrotatorios Mtwo® y ProTaper®. Metodología: estudio experimentalin vitro con presentación de resultados descriptivos comparativos.Se utilizó un total de 50 instrumentos rotatorios ProTaper® y40 Mtwo® para preparar cubos acrílicos Maillefer® con curvassimuladas registrándose cuál es la primera lima de cada serie quese fracturó y cuántos usos soportó cada juego de limas antes de lafractura. Resultados: el número de usos antes de la fractura paraProTaper® es 3.9 y para Mtwo® es 9.7 La primera lima ProTaper®en fracturarse fue la F1 y para Mtwo® es la 25/.06. Conclusión: laduración de los instrumentos rotatorios de Mtwo® es mayor a losde ProTaper® (p 0.0001. Se observó una incidencia relativamentealta de fractura para el instrumento F1 del sistema ProTaper® a los4 usos y del instrumento 25/.06 para el sistema Mtwo® a los 10 usos,con una baja incidencia de deformación o cambio en la estructuraidentificable macroscópicamente antes de presentarse la falla.

  15. 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.

  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

    2016-06-11

    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. Multi-dimensional optimization of a terawatt seeded tapered Free Electron Laser with a Multi-Objective Genetic Algorithm

    Science.gov (United States)

    Wu, Juhao; Hu, Newman; Setiawan, Hananiel; Huang, Xiaobiao; Raubenheimer, Tor O.; Jiao, Yi; Yu, George; Mandlekar, Ajay; Spampinati, Simone; Fang, Kun; Chu, Chungming; Qiang, Ji

    2017-02-01

    There is a great interest in generating high-power hard X-ray Free Electron Laser (FEL) in the terawatt (TW) level that can enable coherent diffraction imaging of complex molecules like proteins and probe fundamental high-field physics. A feasibility study of producing such X-ray pulses was carried out employing a configuration beginning with a Self-Amplified Spontaneous Emission FEL, followed by a "self-seeding" crystal monochromator generating a fully coherent seed, and finishing with a long tapered undulator where the coherent seed recombines with the electron bunch and is amplified to high power. The undulator tapering profile, the phase advance in the undulator break sections, the quadrupole focusing strength, etc. are parameters to be optimized. A Genetic Algorithm (GA) is adopted for this multi-dimensional optimization. Concrete examples are given for LINAC Coherent Light Source (LCLS) and LCLS-II-type systems. Analytical estimate is also developed to cross check the simulation and optimization results as a quick and complimentary tool.

  18. 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.

  19. Free Transverse Vibration Analysis of Axially Functionally Graded Tapered Euler-Bernoulli Beams through Spline Finite Point Method

    Directory of Open Access Journals (Sweden)

    Peng Liu

    2016-01-01

    Full Text Available A new model for the free transverse vibration of axially functionally graded (FG tapered Euler-Bernoulli beams is developed through the spline finite point method (SFPM by investigating the effects of the variation of cross-sectional and material properties along the longitudinal directions. In the proposed method, the beam is discretized with a set of uniformly scattered spline nodes along the beam axis instead of meshes, and the displacement field is approximated by the particularly constructed cubic B-spline interpolation functions with good adaptability for various boundary conditions. Unlike traditional discretization and modeling methods, the global structural stiffness and mass matrices for beams of the proposed model are directly generated after spline discretization without needing element meshes, generation, and assembling. The proposed method shows the distinguished features of high modeling efficiency, low computational cost, and convenience for boundary condition treatment. The performance of the proposed method is verified through numerical examples available in the published literature. All results demonstrate that the proposed method can analyze the free vibration of axially FG tapered Euler-Bernoulli beams with various boundary conditions. Moreover, high accuracy and efficiency can be achieved.

  20. Analysis of elastic stiffness for the leaf type holddown spring assembly with uniformly tapered thickness based on strain energy method

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-03-01

    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 energies due to bending moment, shear and axial force. Comparisons on the elastic stiffnesses have been made with test results and evaluated values from the derived formula for the 14x14 and 17x17 type KOFA HDS, and it has found that most of the differences were in the range of 1-2% of the evaluated elastic stiffnesses and that the elastic stiffness of the HDS was mainly caused by bending moment because effects of shear and axial forces on the elastic stiffness were in the range of 0.09-0.16%. And in addition, it has found that the derived formula could be applicable to HDS designed by Westinghouse. 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. 8 tabs., 4 figs., 22 refs. (Author) .new.