Comparative evaluation of cyclic fatigue resistance of D-RaCe and ProTaper retreatment instruments in curved artificial canals.

PubMed

Topçuoğlu, H S; Topçuoğlu, G; Aktı, A

2016-06-01

To compare the cyclic fatigue resistance of D-RaCe and ProTaper rotary nickel-titanium (NiTi) retreatment files when used in curved artificial canals. A total of 120 new D-RaCe DR2 and ProTaper D3 retreatment files were tested in stainless steel artificial canals having 45° and 60° angles of curvature. Thirty instruments of each of the file systems were tested in both angles of curvature (n = 30). The retreatment instruments were rotated until fracture to calculate the number of cycles to failure. The length of each fractured fragment was recorded. Data were analysed by independent sample t-test. Fractured surfaces of the instruments were analysed by scanning electron microscopy. In the canal with 45° angle of curvature, no significant difference was observed between the retreatment systems (P > 0.05); on the other hand, in the canal with 60° angle of curvature, D-RaCe DR2 instruments had greater cyclic fatigue resistance than ProTaper D3 (P < 0.05). No difference was observed between the retreatment instruments regarding the lengths of fractured fragments (P > 0.05). The fracture surfaces of the instruments had morphologic characteristics of ductile fracture. D-RaCe DR2 instrument exhibited greater cyclic fatigue resistance than ProTaper D3 only in root canals with 60° angle of curvature. © 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Pressure Distribution Over a Thick, Tapered and Twisted Monoplane Wing Model-NACA 81-J

NASA Technical Reports Server (NTRS)

Wenzinger, Carl J

1932-01-01

This reports presents the results of pressure distribution tests on a thick, tapered and twisted monoplane wing model. The investigation was conducted for the purpose of obtaining data on the aerodynamic characteristics of the new wing and to provide additional information suitable for use in the design of tapered cantilever wings. The tests included angles of attack up to 90 degrees. The span loading over the wing was approximately of elliptical shape, which gave rise to relatively small bending moments about the root. The angle of zero lift for all sections along the span varied only within plus or minus 0.4 degree of the angle of zero lift for the whole wing, resulting in small leading edge loads for the high-speed condition of flight. The results also add to the available information for the study of large angles of attack.

Efficiency considerations for the purely tapered interference fit (TIF) abutments used in dental implants.

PubMed

Bozkaya, Dinçer; Müftü, Sinan

2004-08-01

A tapered interference fit provides a mechanically reliable retention mechanism for the implant-abutment interface in a dental implant. Understanding the mechanical properties of the tapered interface with or without a screw at the bottom has been the subject of a considerable amount of studies involving experiments and finite element (FE) analysis. In this paper, approximate closed-form formulas are developed to analyze the mechanics of a tapered interference fit. In particular, the insertion force, the efficiency, defined as the ratio of the pull-out force to insertion force, and the critical insertion depth, which causes the onset of plastic deformation, are analyzed. It is shown that the insertion force is a function of the taper angle, the contact length, the inner and outer radii of the implant, the static and the kinetic coefficients of friction, and the elastic modulii of the implant/abutment materials. The efficiency of the tapered interference fit, which is defined as the ratio of the pull-out force to insertion force, is found to be greater than one, for taper angles that are less than 6 deg when the friction coefficient is 0.3. A safe range of insertion forces has been shown to exist. The lower end of this range depends on the maximum pull-out force that may occur due to occlusion in the multiple tooth restorations and the efficiency of the system; and the upper end of this range depends on the plastic deformation of the abutment and the implant due to interference fit. It has been shown that using a small taper angle and a long contact length widens the safe range of insertion forces.

Mechanical aspects of degree of cement bonding and implant wedge effect.

PubMed

Yoon, Yong-San; Oxland, Thomas R; Hodgson, Antony J; Duncan, Clive P; Masri, Bassam A; Choi, Donok

2008-11-01

The degree of bonding between the femoral stem and cement in total hip replacement remains controversial. Our objective was to determine the wedge effect by debonding and stem taper angle on the structural behavior of axisymmetric stem-cement-bone cylinder models. Stainless steel tapered plugs with a rough (i.e. bonded) or smooth (i.e. debonded) surface finish were used to emulate the femoral stem. Three different stem taper angles (5 degrees , 7.5 degrees , 10 degrees ) were used for the debonded constructs. Non-tapered and tapered (7.5 degrees ) aluminum cylindrical shells were used to emulate the diaphyseal and metaphyseal segments of the femur. The cement-aluminum cylinder interface was designed to have a shear strength that simulated bone-cement interfaces ( approximately 8MPa). The test involved applying axial compression at a rate of 0.02mm/s until failure. Six specimens were tested for each combination of the variables. Finite element analysis was used to enhance the understanding of the wedge effect. The debonded stems sustained about twice as much load as the bonded stem, regardless of taper angle. The metaphyseal model carried 35-50% greater loads than the diaphyseal models and the stem taper produced significant differences. Based on the finite element analysis, failure was most probably by shear at the cement-bone interface. Our results in this simplified model suggest that smooth (i.e. debonded) stems have greater failure loads and will incur less slippage or shear failure at the cement-bone interface than rough (i.e. bonded) stems.

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

NASA Technical Reports Server (NTRS)

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.

Asymmetrical dual tapered fiber Mach-Zehnder interferometer for fiber-optic directional tilt sensor.

PubMed

Lee, Cheng-Ling; Shih, Wen-Cheng; Hsu, Jui-Ming; Horng, Jing-Shyang

2014-10-06

This work proposes a novel, highly sensitive and directional fiber tilt sensor that is based on an asymmetrical dual tapered fiber Mach-Zehnder interferometer (ADTFMZI). The fiber-optic tilt sensor consists of two abrupt tapers with different tapered waists into which are incorporated a set of iron spheres to generate an asymmetrical strain in the ADTFMZI that is correlated with the tilt angle and the direction of inclination. Owing to the asymmetrical structure of the dual tapers, the proposed sensor can detect the non-horizontal/horizontal state of a structure and whether the test structure is tilted to clockwise or counterclockwise by measuring the spectral responses. Experimental results show that the spectral wavelengths are blue-shifted and red-shifted when the sensor tilts to clockwise (-θ) and counterclockwise ( + θ), respectively. Tilt angle sensitivities of about 335 pm/deg. and 125 pm/deg. are achieved in the -θ and + θ directions, respectively, when the proposed sensing scheme is utilized.

A tapered dielectric waveguide solar concentrator for a compound semiconductor photovoltaic cell.

PubMed

Park, Minkyu; Oh, Kyunghwan; Kim, Jeong; Shin, Hyun Woo; Oh, Byung Du

2010-01-18

A novel tapered dielectric waveguide solar concentrator is proposed for compound semiconductor solar cells utilizing optical fiber preform. Its light collecting capability is numerically simulated and experimentally demonstrated for feasibility and potential assessments. Utilizing tapered shape of an optical fiber preform with a step-index profile, low loss guidance was enhanced and the limitation in the acceptance angle of solar radiation was alleviated by an order of magnitude. Using a solar simulator the device performances were experimentally investigated and discussed in terms of the photocurrent improvements. Total acceptance angle exceeding +/- 6 degrees was experimentally achieved sustaining a high solar flux.

Wedge-Shaped GaN Nanowalls: A Potential Candidate for Two-Dimensional Electronics and Spintronics

NASA Astrophysics Data System (ADS)

Deb, Swarup; Dhar, Subhabrata

Schrödingerand Poisson equations are solved self-consistently in order to obtain the potential and charge density distribution in n-type GaN nanowalls tapered along c-axis by different angles. The study shows two-dimensional (2D) quantum confinement of electrons in the central vertical plane of the wall for the entire range of tapering. Calculation of room temperature electron mobility in the 2D channel shows a steady decrease with the increase of the inclination angle of the side facets with respect to the base. However, it is interesting to note that the mobility remains to be much larger than that of bulk GaN even for the inclination angle of 65∘. The properties of high mobility and the vertical orientation of the 2DEG plane in this system can be exploited in fabricating highly conducting transparent interconnects and field effect transistors, which can lead to large scale integration of 2D devices in future.

Limited climate control of the Chugach/St. Elias thrust wedge in southern Alaska demonstrated by orogenic widening during Pliocene to Quaternary climate change

NASA Astrophysics Data System (ADS)

Meigs, Andrew

2014-05-01

Critical taper wedge theory is the gold standard by which climate control of convergent orogenic belts is inferred. The theory predicts (and models reproduce) that an orogenic belt narrows if erosion increases in erosion in the face of a constant tectonic influx. Numerous papers now argue on the basis of thermochronologic data that the Chugach/ St. Elias Range (CSE) of southern Alaska narrowed as a direct response to Quaternary climate change because glaciers dominated erosion of the orogenic belt. The CSE formed in response to collision of a microplate with North America and is notable because glacial erosion has dominated the CSE for the past 5 to 6 Ma. An increase in sediment accumulation rates in the foreland basin over that time suggests that glacial erosion become more efficient. If correct, it is possible that glacial erosion outpaced rock influx thereby inducing a climatically controlled narrowing of the orogenic wedge during the Quaternary. Growth strata preserved within the wedge provide a test of that interpretation because they demonstrate the spatial and temporal pattern of deformation during the Pliocene to Quaternary climate transition. A thrust front established between 6 and 5 Ma jumped towards the foreland by 30 and 15 km at 1.8 and 0.25 Ma, respectively. Distributed deformation within the thrust belt accompanied the thrust front relocations. Continuous exhumation recorded by low-temperature thermochronometers occurred contemporaneously with the shortening, parallel the structural not the topographic grain, and ages become younger towards the foreland as well. Interpreted in terms of critical wedge theory, continuous distributed deformation reflects a sub-critical wedge taper resulting from the combined effects of persistent exhumation and incremental accretion and orogenic widening via thrust front jumps into the undeformed foreland. Taper angle varies according to published cross-sections and ranges from 3 to 9 degrees. If the wedge oscillated about critical taper, a pore fluid ratio between 0.7 and 0.97 is suggested by range of taper angles. Thus, the thrust belt response to Pliocene to Quaternary climate change and a likely increase in glacial coverage is in fact the opposite of the expected response of a critical-taper wedge to an increase in hinterland erosion rate. The CSE hovered near critical taper throughout the Quaternary and the tectonic influx equaled or exceeded the erosional efflux, implying that glacial erosion was paced by, not independent of, tectonic rock uplift rate.

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

PubMed Central

Kanda, Akio; Kaneko, Kazuo; Obayashi, Osamu; Mogami, Atsuhiko

2016-01-01

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. PMID:27127668

Mechanics of the taper integrated screwed-in (TIS) abutments used in dental implants.

PubMed

Bozkaya, Dinçer; Müftü, Sinan

2005-01-01

The tapered implant-abutment interface is becoming more popular due to the mechanical reliability of retention it provides. Consequently, understanding the mechanical properties of the tapered interface with or without a screw at the bottom has been the subject of a considerable amount of studies involving experiments and finite element (FE) analysis. This paper focuses on the tapered implant-abutment interface with a screw integrated at the bottom of the abutment. The tightening and loosening torques are the main factors in determining the reliability and the stability of the attachment. Analytical formulas are developed to predict tightening and loosening torque values by combining the equations related to the tapered interface with screw mechanics equations. This enables the identification of the effects of the parameters such as friction, geometric properties of the screw, the taper angle, and the elastic properties of the materials on the mechanics of the system. In particular, a relation between the tightening torque and the screw pretension is identified. It was shown that the loosening torque is smaller than the tightening torque for typical values of the parameters. Most of the tightening load is carried by the tapered section of the abutment, and in certain combinations of the parameters the pretension in the screw may become zero. The calculations performed to determine the loosening torque as a percentage of tightening torque resulted in the range 85-137%, depending on the values of taper angle and the friction coefficient.

Application of fiber tapers in astronomy

NASA Astrophysics Data System (ADS)

Marcel, Jaclyn; Haynes, Roger; Bland-Hawthorn, Joss

2006-06-01

Fiber tapers have the potential to significantly advance instrument technology into the realm of fully integrated optical systems. Our initial investigation was directed at the use of fiber tapers as f-ratio transformation devices. Using a technique developed for testing focal ratio degradation (FRD), a collimated light source was injected at different angles into various fiber taper samples and the far-field profile of the fiber output was observed. We compare the FRD present in the optical fiber tapers with conventional fibers and determine how effectively fiber tapers perform as image converters. We demonstrate that while silica fiber tapers may have slightly more intrinsic FRD than conventional fibers they still show promise as adiabatic mode transformers and are worth investigating further for their potential use in astronomical instruments. In this paper we present a brief review of the current status of fiber tapers with particular focus on the astronomical applications. We demonstrate the conservation of etendue in the taper transformation process and present the experimental results for a number of different taper profiles and manufacturers.

Free torsional vibrations of tapered cantilever I-beams

NASA Astrophysics Data System (ADS)

Rao, C. Kameswara; Mirza, S.

1988-08-01

Torsional vibration characteristics of linearly tapered cantilever I-beams have been studied by using the Galerkin finite element method. A third degree polynomial is assumed for the angle of twist. The analysis presented is valid for long beams and includes the effect of warping. The individual as well as combined effects of linear tapers in the width of the flanges and the depth of the web on the torsional vibration of cantilever I-beams are investigated. Numerical results generated for various values of taper ratios are presented in graphical form.

Polarization insensitive and low-loss coupling mode-size converter from super luminescent diode to silica-based planar lightwave circuit

NASA Astrophysics Data System (ADS)

She, Xuan; Li, Bei; Chen, Kan; Li, Ke; Shu, Xiaowu; Liu, Cheng

2017-02-01

We present a design of a laterally tapered optical waveguide mode-size converter from super luminescent diode (SLD) to silica-based planar lightwave circuit (PLC). The mode-size converter is based on silica-based PLC. By using three dimensional semi-vectorial beam propagation methods, laterally tapered waveguides with different boundaries are simulated and compared with each other, where the factors of polarization-dependent loss and coupling loss are mainly focused on. The results show that the most influential factor for polarization-dependent loss is the ratio of the divergence angle of SLD in the horizontal direction and the vertical direction. The refractive index difference Δ between core layer and cladding layer, core width of endface and taper length influence coupling loss mostly, while the effect of all side boundaries is within 0.05 dB. We also investigate the SLD misalignment tolerance and wavelength bandwidth's impact on coupling loss. Furthermore, we examine the performance of the mode-size converter based on a particular SLD which has a divergence angle of 30°×45°. By optimizing the parameters of the tapered waveguide, the coupling efficiency is increased to 62.4% and the polarization-dependent loss is reduced to 0.035 dB. Meanwhile, it eΔnables us to reduce the coupling loss variation to 0.05dB with core width of endface fabrication tolerance of ±0.5 μm and taper length tolerance of ±0.5 mm. The proposed mode-size converter has been demonstrated to be well performed, implying its application in the optical transceiver module using SLD as light source and hybrid integration of III-V semiconductor waveguiding devices and PLCs.

Measuring the charge density of a tapered optical fiber using trapped microparticles.

PubMed

Kamitani, Kazuhiko; Muranaka, Takuya; Takashima, Hideaki; Fujiwara, Masazumi; Tanaka, Utako; Takeuchi, Shigeki; Urabe, Shinji

2016-03-07

We report the measurements of charge density of tapered optical fibers using charged particles confined in a linear Paul trap at ambient pressure. A tapered optical fiber is placed across the trap axis at a right angle, and polystyrene microparticles are trapped along the trap axis. The distance between the equilibrium position of a positively charged particle and the tapered fiber is used to estimate the amount of charge per unit length of the fiber without knowing the amount of charge of the trapped particle. The charge per unit length of a tapered fiber with a diameter of 1.6 μm was measured to be 2-1+3×10 -11 C/m.

The Effects of Torsional Preloading on the Torsional Resistance of Nickel-titanium Instruments.

PubMed

Oh, Seung-Hei; Ha, Jung-Hong; Kwak, Sang Won; Ahn, Shin Wook; Lee, WooCheol; Kim, Hyeon-Cheol

2017-01-01

This study evaluated the effect of torsional preloading on the torsional resistance of nickel-titanium (NiTi) endodontic instruments. WaveOne Primary (Dentsply Maillefer, Ballaigues, Switzerland) and ProTaper Universal F2 (Dentsply Maillefer) files were used. The ultimate torsional strength until fracture was determined for each instrument. In the phase 1 experiment, the ProTaper and WaveOne files were loaded to have a maximum load from 2.0 up to 2.7 or 2.8 Ncm, respectively. In the phase 2 experiment, the number of repetitions of preloading for each file was increased from 50 to 200, whereas the preloading torque was fixed at 2.4 Ncm. Using torsionally preloaded specimens from phase 1 and 2, the torsional resistances were calculated to determine the ultimate strength, distortion angle, and toughness. The results were analyzed using 1-way analysis of variance and Duncan post hoc comparison. The fracture surfaces and longitudinal aspect of 5 specimens per group were examined under a scanning electron microscope. All preloaded groups showed significantly higher ultimate strength than the unpreloaded groups (P < .05). There was no significant difference among all groups for distortion angle and toughness. Although WaveOne had no significant difference between the repetition groups for ultimate strength, fracture angle, and toughness, ProTaper had a higher distortion angle and toughness in the 50-repetition group compared with the other repetition groups (P < .05). Scanning electron microscopic examinations of the fractured surface showed typical features of torsional fracture. Torsional preloading within the ultimate values could enhance the torsional strength of NiTi instruments. The total energy until fracture was maintained constantly, regardless of the alloy type. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Shorter, rough trunnion surfaces are associated with higher taper wear rates than longer, smooth trunnion surfaces in a contemporary large head metal-on-metal total hip arthroplasty system.

PubMed

Brock, Timothy M; Sidaginamale, Raghavendra; Rushton, Steven; Nargol, Antoni V F; Bowsher, John G; Savisaar, Christina; Joyce, Tom J; Deehan, David J; Lord, James K; Langton, David J

2015-12-01

Taper wear at the head-neck junction is a possible cause of early failure in large head metal-on-metal (LH-MoM) hip replacements. We hypothesized that: (i) taper wear may be more pronounced in certain product designs; and (ii) an increased abductor moment arm may be protective. The tapers of 104 explanted LH-MoM hip replacements revised for adverse reaction to metal debris (ARMD) from a single manufacturer were analyzed for linear and volumetric wear using a co-ordinate measuring machine. The mated stem was a shorter 12/14, threaded trunnion (n=72) or a longer, smooth 11/13 trunnion (n=32). The abductor moment arm was calculated from pre-revision radiographs. Independent predictors of linear and volumetric wear included taper angle, stem type, and the horizontal moment arm. Tapers mated with the threaded 12/14 trunnion had significantly higher rates of volumetric wear (0.402 mm3/yr vs. 0.123 mm3/yr [t=-2.145, p=0.035]). There was a trend to larger abductor moment arms being protective (p=0.055). Design variation appears to play an important role in taper-trunnion junction failure. We recommend that surgeons bear these findings in mind when considering the use of a short, threaded trunnion with a cobalt-chromium head. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Experiments on tandem diffusers with boundary-layer suction applied in between

NASA Technical Reports Server (NTRS)

Barna, P. S.

1979-01-01

Experiments were performed on conical diffusers of various configurations with the same, but rather unusually large, 16:1 area ratio. Because available performance data on diffusers fall short of very large area ratio configurations, an unconventional design, consisting of two diffusers following each other in tandem, was proposed. Both diffusers had the same area ratio of 4:1, but had different taper angles. While for the first diffuser (called leading) the angle remained constant, for the second (called follower), the taper angle was stepped up to higher values. Boundary layer control, by way of suction, was applied between the diffusers, and a single slot suction ring was inserted between them. The leading diffuser had an enclosed nominal divergence angle 2 theta = 5 degrees, while the follower diffusers had either 10, 20, 30, or 40 degrees, respectively, giving 4 combinations. The experiments were performed at four different Reynolds numbers with various suction rates. The rates indicate a general improvement in the performance of all diffusers with boundary layer suction. It appears that the improvement of the pressure recovery depends on both the Reynolds number and the suction rate, and the largest increase, 0.075, was found at the lowest R sub e when the follower divergence was 2 theta = 40 degrees.

Turbine airfoil to shround attachment

DOEpatents

Campbell, Christian X; Morrison, Jay A; James, Allister W; Snider, Raymond G; Eshak, Daniel M; Marra, John J; Wessell, Brian J

2014-05-06

A turbine airfoil (31) with an end portion (42) that tapers (44) toward the end (43) of the airfoil. A ridge (46) extends around the end portion. It has proximal (66) and distal (67) sides. A shroud platform (50) is bi-cast onto the end portion around the ridge without bonding. Cooling shrinks the platform into compression (62) on the end portion (42) of the airfoil. Gaps between the airfoil and platform are formed using a fugitive material (56) in the bi-casting stage. These gaps are designed in combination with the taper angle (44) to accommodate differential thermal expansion while maintaining a gas seal along the contact surfaces. The taper angle (44) may vary from lesser on the pressure side (36) to greater on the suction side (38) of the airfoil. A collar portion (52) of the platform provides sufficient contact area for connection stability.

Collection of Light From an Optical Fiber With a Numerical Aperture Greater Than One

NASA Technical Reports Server (NTRS)

Egalon, Claudio O. (Inventor); Rogowski, Robert S. (Inventor)

1996-01-01

In an optical fiber having NA greater than 1, light may be internally reflected when it strikes the fiber end at a fiber-air interface. This problem may be overcome by modification of the fiber by reverse tapering the core. Light is redirected by the taper to strike the interface at an angle closer to normal. This allows light to exit the fiber end that would by internally reflected in an untapered fiber of NA greater than 1. The novelty of the present invention lies in the tapering of the fiber core for increased through transmission of light. Prior art devices have made use of fiber tapers to achieve mode control or fiber coupling. The problem of internal reflection has not been addressed as it is one that is not as important in fibers having NA less than 1, which are more common. In chemical sensing it is advantageous to make use of fibers having higher NA due to an increased sensitivity. However the advantages in sensitivity are diminished due to the loss of signal at the fiber-air interface. The present invention overcomes the problem of loss at the interface, thus facilitating the use of high NA fibers for chemical sensing.

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

PubMed Central

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

2015-01-01

In this work, the dielectrophoretic force (FDEP) response of Aluminium Microelectrode Arrays with tapered profile is investigated through experimental measurements and numerical simulations. A standard CMOS processing technique with a step for the formation of a tapered profile resist is implemented in the fabrication of Tapered Aluminium Microelectrode Arrays (TAMA). The FDEP is investigated through analysis of the Clausius-Mossotti factor (CMF) and cross-over frequency (fxo). The performance of TAMA with various side wall angles is compared to that of microelectrodes with a straight cut sidewall profile over a wide range of frequencies through FEM numerical simulations. Additionally, electric field measurement (EFM) is performed through scanning probe microscopy (SPM) in order to obtain the region of force focus in both platforms. Results showed that the tapered profile microelectrodes with angles between 60° and 70° produce the highest electric field gradient on the particles. Also, the region of the strongest electric field in TAMA is located at the bottom and top edge of microelectrode while the strongest electric field in microelectrodes with straight cut profile is found at the top corner of the microelectrode. The latter property of microelectrodes improves the probability of capturing/repelling the particles at the microelectrode’s side wall. PMID:25970255

A tapered aluminium microelectrode array for improvement of dielectrophoresis-based particle manipulation.

PubMed

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

2015-05-11

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

Tool for reading psychrometric charts

NASA Technical Reports Server (NTRS)

De Angelo, F. T.

1969-01-01

Three-legged, clear plastic tool is designed so that the angles of each leg correspond with the angles of psychometric chart construction for each of the three required scales. The appropriate edges are tapered to the chart surface.

Comparative evaluation of the shaping ability of two different nickel-titanium rotary files in curved root canals of extracted human molar teeth.

PubMed

Ferrara, Giulia; Taschieri, Silvio; Corbella, Stefano; Ceci, Caterina; Del Fabbro, Massimo; Machtou, Pierre

2017-02-01

The aim of the present study was to compare the shaping ability of two different nickel-titanium rotary files in the curved root canals of extracted human molar teeth. Thirty root canals of 17 extracted human molars teeth were randomly assigned to two experimental groups (n = 15): ProTaper Next and ProTaper Universal (PTU), on the basis of the rotary files system used. The final size of all apical foramina was 0.25 mm in diameter. Standardized digital radiographs were taken before and after instrumentation in both clinical and proximal views, with a size 10 K-file inserted into the canal for the determination of the angle of curvature and apical transportation. Preparation time and fractured or deformed instruments were also recorded. The unpaired Student's t-test was used to compare results. There was no significant difference between the two instruments with respect to canal straightening and apical transportation before and after instrumentation (P > 0.05). The use of both instruments resulted in a significant reduction in the angle of curvature after instrumentation (P < 0.05). Instrumentation time was significantly greater for PTU (P < 0.05). The ProTaper Universal and ProTaper Next systems performed similarly with regard to the straightening of curved root canals and apical transportation. ProTaper Next was significantly faster than ProTaper Universal. © 2015 Wiley Publishing Asia Pty Ltd.

Waveguide-loaded silica fibers for coupling to high-index micro-resonators

NASA Astrophysics Data System (ADS)

Latawiec, P.; Burek, M. J.; Venkataraman, V.; Lončar, M.

2016-01-01

Tapered silica fibers are often used to rapidly probe the optical properties of micro-resonators. However, their low refractive index precludes phase-matching when coupling to high-index micro-resonators, reducing efficiency. Here, we demonstrate efficient optical coupling from tapered fibers to high-index micro-resonators by loading the fibers with an ancillary adiabatic waveguide-coupler fabricated via angled-etching. We demonstrate greatly enhanced coupling to a silicon multimode micro-resonator when compared to coupling via the bare fiber only. Signatures of resonator optical bistability are observed at high powers. This scheme can be applied to resonators of any size and material, increasing the functional scope of fiber coupling.

The use of paper honeycomb for prototype blade construction for small to medium-sized wind driven generators

NASA Technical Reports Server (NTRS)

Meyer, H.

1973-01-01

Paper honeycomb is used for the construction of conventional, propeller-type, windmill blades. Using fairly simple techniques and conventional power tools, it is possible to shape both simple foils and more complex foils with or without tapered plan forms and with or without varying profiles. A block of honeycomb, in its compressed form, is mounted on a wedge and run through a bandsaw with the table at an appropriate tilt angle. It is the combination of the wedge angle and the table angle that gives the tapered planform and profile shape. Next the honeycomb is expanded on the shaft and jigged to give the desired angles of attack. With the honeycomb fixed in position, the blade is covered with a fine weave fiberglass cloth. Any surface quality can then be achieved with filling and sanding.

Fabrication and characterization of tapered graphite/epoxy box beams

NASA Astrophysics Data System (ADS)

Yen, S.-C.; Gopal, P.; Dharani, L. R.

1993-04-01

Graphite/epoxy (T300/934) prepreg is used to fabricate tapered box beams with a taper angle of 2 deg between the top and bottom walls. The prepreg is cured on a segmented steel core using a hot-press. A screw arrangement is used to apply curing pressure in the horizontal direction, while the platens of the hot-press apply pressure in the vertical direction. The inplane bending stiffness of the beam is determined by 3-point bend test and is found to be in agreement with theory.

High pressure, high current, low inductance, high reliability sealed terminals

DOEpatents

Hsu, John S [Oak Ridge, TN; McKeever, John W [Oak Ridge, TN

2010-03-23

The invention is a terminal assembly having a casing with at least one delivery tapered-cone conductor and at least one return tapered-cone conductor routed there-through. The delivery and return tapered-cone conductors are electrically isolated from each other and positioned in the annuluses of ordered concentric cones at an off-normal angle. The tapered cone conductor service can be AC phase conductors and DC link conductors. The center core has at least one service conduit of gate signal leads, diagnostic signal wires, and refrigerant tubing routed there-through. A seal material is in direct contact with the casing inner surface, the tapered-cone conductors, and the service conduits thereby hermetically filling the interstitial space in the casing interior core and center core. The assembly provides simultaneous high-current, high-pressure, low-inductance, and high-reliability service.

[Factors influencing bonding fixed restorations].

PubMed

Medić, Vesna; Obradović-Djuricić, Kosovka

2008-01-01

Crown displacement often occurs because the features of tooth preparations do not counteract the forces directed against restorations. The purpose of this study was to evaluate the effect of preparation designs on retention and resistance of fixed restorations. The study was performed on 64 differently sized stainless steel dies. Also, caps which were used for evaluated retention were made of stainless steel for each die. After cementing the caps on experimental dies, measuring of necessary tensile forces to separate cemented caps from dies was done. Caps, which were made of a silver-palladium alloy with a slope of 600 to the longitudinal axis formed on the occlusal surface, were used for evaluating resistance. A sudden drop in load pressure recorded by the test machine indicated failure for that cap. A significant difference was found between the tensile force required to remove the caps from the dies with different length (p < 0.05) and different taper (p < 0.01). The greatest retentive strengths (2579.2 N and 2989.8 N) were noticed in experimental dies with the greatest length and smallest taper. No statistically significant (p > 0.05) differences were found between tensile loads for caps cemented on dies with different diameter. Although there was an apparent slight increase in resistance values for caps on dies with smaller tapers, the increase in resistance for those preparation designs was not statistically significant. There was a significant difference among the resistance values for caps on dies with different length (p < 0.01) and diameter (p < 0.05). In the light of the results obtained, it could be reasonably concluded that retention and resistance of the restoration is in inverse proportion to convergence angle of the prepared teeth. But, at a constant convergence angle, retention and resistance increase with rising length and diameter.

Aerodynamic Load Measurements and Opening Characteristics of Automatic Leading Edge Slats on a 45 deg Sweptback Wing at Transonic Speeds

NASA Technical Reports Server (NTRS)

Arabian, Donald D.; Runckel, Jack F.; Reid, Charles F, Jr.

1961-01-01

Measurements of the normal force and chord force were made on the slats of a sting-mounted wing-fuselage model through a Mach number range of 0.60 to 1.03 and at angles of attack from 0 to 20 deg at subsonic speeds and from 0 to 8 deg at Mach number 1.03. The 20-percent-chord tapered leading-edge slats extended from 25 to 95 percent of the semispan and consisted of five segments. The model wing had 45 deg sweep, an aspect ratio of 3.56, a taper ratio of 0.3, and NACA 64(06)AO07 airfoil sections. Slat forces and moments were determined for the slats in the almost-closed and open positions for spanwise extents of 35 to 95 percent and 46 to 95 percent of the semispan. The results of the investigation showed little change in the slat maximum force and moment coefficients with Mach number. The coefficients for the open and almost-closed slat positions had similar variations with angle of attack. The loads on the individual slat segments were found to increase toward the tip for moderate angles of attack and decrease toward the tip for high angles of attack. An analysis of the opening and closing characteristics of aerodynamically operated slats opening on a circular-arc path is included.

High-flux low-divergence positron beam generation from ultra-intense laser irradiated a tapered hollow target

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Jian-Xun; College of Electronic Engineering, Wuhan 430019; Ma, Yan-Yun, E-mail: yanyunma@126.com

By using two-dimensional particle-in-cell simulations, we demonstrate high-flux dense positrons generation by irradiating an ultra-intense laser pulse onto a tapered hollow target. By using a laser with an intensity of 4 × 10{sup 23 }W/cm{sup 2}, it is shown that the Breit-Wheeler process dominates the positron production during the laser-target interaction and a positron beam with a total number >10{sup 15} is obtained, which is increased by five orders of magnitude than in the previous work at the same laser intensity. Due to the focusing effect of the transverse electric fields formed in the hollow cone wall, the divergence angle of the positronmore » beam effectively decreases to ∼15° with an effective temperature of ∼674 MeV. When the laser intensity is doubled, both the positron flux (>10{sup 16}) and temperature (963 MeV) increase, while the divergence angle gets smaller (∼13°). The obtained high-flux low-divergence positron beam may have diverse applications in science, medicine, and engineering.« less

Effect of Tail Dihedral on Lateral Control Effectiveness at High Subsonic Speeds of Differentially Deflected Horizontal-Tail Surfaces on a Configuration having a Thin Highly Tapered Wing

NASA Technical Reports Server (NTRS)

Fournier, Paul G.

1959-01-01

Tests have been conducted in the Langley high-speed 7- by 10-foot tunnel to determine the effect of tail dihedral on lateral control effectiveness of a complete-model configuration having differentially deflected horizontal-tail surfaces. Limited tests were made to determine the lateral characteristics as well as the longitudinal characteristics in sideslip. The wing had an aspect ratio of 3, a taper ratio of 0.14, 28.80 deg sweep of the quarter-chord line with zero sweep at the 80-percent-chord line, and NACA 65A004 airfoil sections. The test Mach number range extended from 0.60 to 0.92. There are only small variations in the roll effectiveness parameter C(sub iota delta) with negative tail dihedral angle. The tail size used on the test model, however, is perhaps inadequate for providing the roll rates specified by current military requirements at subsonic speeds. The lateral aerodynamic characteristics were essentially constant throughout the range of sideslip angle from 12 deg to -12 deg. A general increase in yawing moment was noted with increased negative dihedral throughout the Mach number range.

Full Scale Span Load Distribution on a Tapered Wing with Split Flaps of Various Spans

NASA Technical Reports Server (NTRS)

Parsons, John F; Silverstein, Abe

1937-01-01

Pressure-distribution tests were conducted in the full-scale wind tunnel on a 2:1 tapered U.S.A. 45 airfoil equipped with 20 percent chord split trailing-edge flaps of various spans. A special installation was employed in the tests utilizing a half-span airfoil mounted vertically above a reflection plane. The airfoil has a constant chord center section and rounded tips and is tapered in thickness from 18 percent c at the root to 9 percent c at the tip. The aerodynamic characteristics, given by the usual dimension less coefficients, are presented graphically as functions of flap span and angle of attack as well as by semispan load diagrams. The results indicate, in general, that only a relatively small increase in the normal-force coefficient is to be expected by extending the flap span of an airfoil-flap combination, similar to the one tested, beyond 70 percent of the wing span.

Deep and tapered silicon photonic crystals for achieving anti-reflection and enhanced absorption.

PubMed

Hung, Yung-Jr; Lee, San-Liang; Coldren, Larry A

2010-03-29

Tapered silicon photonic crystals (PhCs) with smooth sidewalls are realized using a novel single-step deep reactive ion etching. The PhCs can significantly reduce the surface reflection over the wavelength range between the ultra-violet and near-infrared regions. From the measurements using a spectrophotometer and an angle-variable spectroscopic ellipsometer, the sub-wavelength periodic structure can provide a broad and angular-independent antireflective window in the visible region for the TE-polarized light. The PhCs with tapered rods can further reduce the reflection due to a gradually changed effective index. On the other hand, strong optical resonances for TM-mode can be found in this structure, which is mainly due to the existence of full photonic bandgaps inside the material. Such resonance can enhance the optical absorption inside the silicon PhCs due to its increased optical paths. With the help of both antireflective and absorption-enhanced characteristics in this structure, the PhCs can be used for various applications.

Fabrication and application of a non-contact double-tapered optical fiber tweezers.

PubMed

Liu, Z L; Liu, Y X; Tang, Y; Zhang, N; Wu, F P; Zhang, B

2017-09-18

A double-tapered optical fiber tweezers (DOFTs) was fabricated by a chemical etching called interfacial layer etching. In this method, the second taper angle (STA) of DOFTs can be controlled easily by the interfacial layer etching time. Application of the DOFTs to the optical trapping of the yeast cells was presented. Effects of the STA on the axile trapping efficiency and the trapping position were investigated experimentally and theoretically. The experimental results are good agreement with the theoretical ones. The results demonstrated that the non-contact capture can be realized for the large STA (e.g. 90 deg) and there was an optimal axile trapping efficiency as the STA increasing. In order to obtain a more accurate measurement result of the trapping force, a correction factor to Stokes drag coefficient was introduced. This work provided a way of designing and fabricating an optical fiber tweezers (OFTs) with a high trapping efficient or a non-contact capture.

Basic Pressure Measurements at Transonic Speeds on a Thin 45 deg Sweptback Highly Tapered Wing With Systematic Spanwise Twist Variations

NASA Technical Reports Server (NTRS)

Mugler, John P., Jr.

1959-01-01

Pressure distributions obtained in the Langley 8-foot transonic pressure tunnel on a thin, highly tapered, twisted, 45 deg sweptback wing in combination with a body are presented. The wing has a linear span-wise twist variation from 0 deg at 10 percent of the semispan to 6 deg at the tip. The tip is at a lower angle of attack than the root. Tests were made at stagnation pressures of 1.0 and 0.5 atmosphere, at Mach numbers from 0.800 to 1.200, and at angles of attack from -4 to 12 deg.

Improved power and efficiency for tapered lasers with optimized photonic crystal structures

NASA Astrophysics Data System (ADS)

Ma, Xiaolong; Qu, Hongwei; Zhao, Shaoyu; Zhou, Xuyan; Lin, Yuzhe; Zheng, Wanhua

2017-10-01

High power and high beam quality laser sources are required in numerous applications such as nonlinear frequency conversion, optical pumping of solid-state and fiber lasers, material processing and others. Tapered lasers can provide a high output power while keeping a high beam quality. However, the conventional tapered lasers suffer from a large vertical beam divergence. We have demonstrated 2-mm long tapered lasers with photonic crystal structures. A high beam quality and a narrow vertical divergence are achieved. In this paper, we optimized the photonic crystal structure and fabricated a 4-mm long tapered laser to further increase the output power and the wall-plug efficiency. Compared with our precious wafer, the optimized structure has a lower doping level to reduce the internal loss. The period of the photonic crystal structure and the thickness of the upper cladding are also reduced. The device has a 1-mm long ridge-waveguide section and a 3-mm long tapered section. The taper angle is 4°. An output power of 7.3 W is achieved with a peak wall-plug efficiency of 46% in continuous-wave mode. The threshold current is around 500 mA and the slope efficiency is 0.93 W/A. In pulsed mode, the output power is 15.6 W and the maximum wall-plug efficiency is 48.1%. The far-field divergence with full width at half maximum is 6.3° for the lateral direction at 3 A. The vertical far-field beam divergence is around 11° at different injection levels. High beam qualities are demonstrated by beam quality factor M2 of 1.52 for the lateral direction and 1.54 for the vertical direction.

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

PubMed

Merk, Susanne; Wagner, Christina; Stock, Veronika; Eichberger, Marlis; Schmidlin, Patrick R; Roos, Malgorzata; Stawarczyk, Bogna

2016-11-08

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.

Eigenvalue equation and core-mode cutoff of weakly guiding tapered fiber as three layer optical waveguide and used as biochemical sensor.

PubMed

Linslal, C L; Mohan, P M S; Halder, A; Gangopadhyay, T K

2012-06-01

The core-mode cutoff plays a major role in evanescent field absorption based sensors. A method has been proposed to calculate the core-mode cutoff by solving the eigenvalue equations of a weakly guiding three layer optical waveguide graphically. The variation of normalized waveguide parameter (V) is also calculated with different wavelengths at core-mode cutoff. At the first step, theoretical analysis of tapered fiber parameters has been performed for core-mode cutoff. The taper angle of an adiabatic tapered fiber is also analyzed using the length-scale criterion. Secondly, single-mode tapered fiber has been developed to make a precision sensor element suitable for chemical detection. Finally, the sensor element has been used to detect absorption peak of ethylenediamine. Results are presented in which an absorption peak at 1540 nm is observed.

Angle selective fiber coupler.

PubMed

Barnoski, M K; Morrison, R J

1976-01-01

Angle selective input coupling through the side of a slightly tapered section of Corning highly multimode fiber has been experimentally demonstrated for the first time. This coupling technique allows the possibility of fabricating bidirectional (duplex) couplers for systems employing single strands of multimode, low loss fiber.

Influence of depressed-index outer ring on evanescent tunneling loss in tapered double-cladding fibers.

PubMed

Chen, Nan-Kuang; Hsu, Kuei-Chu; Liaw, Shien-Kuei; Lai, Yinchieh; Chi, Sien

2008-08-01

A tapered fiber with a depressed-index outer ring is fabricated and dispersion engineered to generate a widely tunable (1250-1650 nm) fundamental-mode leakage loss with a high cutoff slope (-1.2 dB/nm) and a high attenuation for stop band (>50 dB) by modification of both waveguide and material dispersions. The higher cutoff slope is achieved with a larger cross angle between the two refractive index dispersion curves of the tapered fiber and surrounding optical liquids through the use of depressed-index outer ring structures in double-cladding fibers.

Effect of twist on single-mode fiber-optic 3 × 3 couplers

NASA Astrophysics Data System (ADS)

Chen, Dandan; Ji, Minning; Peng, Lei

2018-01-01

In the fabricating process of a 3 × 3 fused tapered coupler, the three fibers are usually twisted to be close-contact. The effect of twist on 3 × 3 fused tapered couplers is investigated in this paper. It is found that though a linear 3 × 3 coupler may realize equal power splitting ratio theoretically by twisting a special angle, it is hard to be fabricated actually because the twist angle and the coupler's length must be determined in advance. While an equilateral 3 × 3 coupler can not only realize approximate equal power splitting ratio theoretically but can also be fabricated just by controlling the elongation length. The effect of twist on the equilateral 3 × 3 coupler lies in the relationship between the equal ratio error and the twist angle. The more the twist angle is, the larger the equal ratio error may be. The twist angle usually should be no larger than 90° on one coupling period length in order to keep the equal ratio error small enough. The simulation results agree well with the experimental data.

Tapered Microfluidic for Continuous Micro-Object Separation Based on Hydrodynamic Principle.

PubMed

Ahmad, Ida Laila; Ahmad, Mohd Ridzuan; Takeuchi, Masaru; Nakajima, Masahiro; Hasegawa, Yasuhisa

2017-12-01

Recent advances in microfluidic technologies have created a demand for a simple and efficient separation intended for various applications such as food industries, biological preparation, and medical diagnostic. In this paper, we report a tapered microfluidic device for passive continuous separation of microparticles by using hydrodynamic separation. By exploiting the hydrodynamic properties of the fluid flow and physical characteristics of micro particles, effective size based separation is demonstrated. The tapered microfluidic device has widening geometries with respect to specific taper angle which amplify the sedimentation effect experienced by particles of different sizes. A mixture of 3-μm and 10-μm polystyrene microbeads are successfully separated using 20° and 25° taper angles. The results obtained are in agreement with three-dimensional finite element simulation conducted using Abaqus 6.12. Moreover, the feasibility of this mechanism for biological separation is demonstrated by using polydisperse samples consists of 3-μm polystyrene microbeads and human epithelial cervical carcinoma (HeLa) cells. 98% of samples purity is recovered at outlet 1 and outlet 3 with flow rate of 0.5-3.0 μl/min. Our device is interesting despite adopting passive separation approach. This method enables straightforward, label-free, and continuous separation of multiparticles in a stand-alone device without the need for bulky apparatus. Therefore, this device may become an enabling technology for point of care diagnosis tools and may hold potential for micrototal analysis system applications.

Relative contributions from the ventricle and arterial tree to arterial pressure and its amplification: an experimental study

PubMed Central

Alastruey, Jordi; Chowienczyk, Phil; Rutten, Marcel C. M.; Segers, Patrick; Schaeffter, Tobias

2017-01-01

Arterial pressure is an important diagnostic parameter for cardiovascular disease. However, relative contributions of individual ventricular and arterial parameters in generating and augmenting pressure are not understood. Using a novel experimental arterial model, our aim was to characterize individual parameter contributions to arterial pressure and its amplification. A piston-driven ventricle provided programmable stroke profiles into various silicone arterial trees and a bovine aorta. Inotropy was varied in the ventricle, and arterial parameters modulated included wall thickness, taper and diameter, the presence of bifurcation, and a native aorta (bovine) versus silicone. Wave reflection at bifurcations was measured and compared with theory, varying parent-to-child tube diameter ratios, and branch angles. Intravascular pressure-tip wires and ultrasonic flow probes measured pressure and flow. Increasing ventricular inotropy independently augmented pressure amplification from 17% to 61% between the lower and higher systolic gradient stroke profiles in the silicone arterial network and from 10% to 32% in the bovine aorta. Amplification increased with presence of a bifurcation, decreasing wall thickness and vessel taper. Pulse pressure increased with increasing wall thickness (stiffness) and taper angle and decreasing diameter. Theoretical predictions of wave transmission through bifurcations werre similar to measurements (correlation: 0.91, R2 = 0.94) but underestimated wave reflection (correlation: 0.75, R2 = 0.94), indicating energy losses during mechanical wave reflection. This study offers the first comprehensive investigation of contributors to hypertensive pressure and its propagation throughout the arterial tree. Importantly, ventricular inotropy plays a crucial role in the amplification of peripheral pressure wave, which offers opportunity for noninvasive assessment of ventricular health. NEW & NOTEWORTHY The present study distinguishes contributions from cardiac and arterial parameters to elevated blood pressure and pressure amplification. Most importantly, it offers the first evidence that ventricular inotropy, an indicator of ventricular function, is an independent determinant of pressure amplification and could be measured with such established devices such as the SphygmoCor. PMID:28576835

Relative contributions from the ventricle and arterial tree to arterial pressure and its amplification: an experimental study.

PubMed

Gaddum, Nicholas; Alastruey, Jordi; Chowienczyk, Phil; Rutten, Marcel C M; Segers, Patrick; Schaeffter, Tobias

2017-09-01

Arterial pressure is an important diagnostic parameter for cardiovascular disease. However, relative contributions of individual ventricular and arterial parameters in generating and augmenting pressure are not understood. Using a novel experimental arterial model, our aim was to characterize individual parameter contributions to arterial pressure and its amplification. A piston-driven ventricle provided programmable stroke profiles into various silicone arterial trees and a bovine aorta. Inotropy was varied in the ventricle, and arterial parameters modulated included wall thickness, taper and diameter, the presence of bifurcation, and a native aorta (bovine) versus silicone. Wave reflection at bifurcations was measured and compared with theory, varying parent-to-child tube diameter ratios, and branch angles. Intravascular pressure-tip wires and ultrasonic flow probes measured pressure and flow. Increasing ventricular inotropy independently augmented pressure amplification from 17% to 61% between the lower and higher systolic gradient stroke profiles in the silicone arterial network and from 10% to 32% in the bovine aorta. Amplification increased with presence of a bifurcation, decreasing wall thickness and vessel taper. Pulse pressure increased with increasing wall thickness (stiffness) and taper angle and decreasing diameter. Theoretical predictions of wave transmission through bifurcations werre similar to measurements (correlation: 0.91, R 2 = 0.94) but underestimated wave reflection (correlation: 0.75, R 2 = 0.94), indicating energy losses during mechanical wave reflection. This study offers the first comprehensive investigation of contributors to hypertensive pressure and its propagation throughout the arterial tree. Importantly, ventricular inotropy plays a crucial role in the amplification of peripheral pressure wave, which offers opportunity for noninvasive assessment of ventricular health. NEW & NOTEWORTHY The present study distinguishes contributions from cardiac and arterial parameters to elevated blood pressure and pressure amplification. Most importantly, it offers the first evidence that ventricular inotropy, an indicator of ventricular function, is an independent determinant of pressure amplification and could be measured with such established devices such as the SphygmoCor. Copyright © 2017 the American Physiological Society.

Influence of topographically patterned angled guidelines on directed self-assembly of block copolymers

NASA Astrophysics Data System (ADS)

Rebello, Nathan; Sethuraman, Vaidyanathan; Blachut, Gregory; Ellison, Christopher J.; Willson, C. Grant; Ganesan, Venkat

2017-11-01

Single chain in mean-field Monte Carlo simulations were employed to study the self-assembly of block copolymers (BCP) in thin films that use trapezoidal guidelines to direct the orientation and alignment of lamellar patterns. The present study explored the influence of sidewall interactions and geometry of the trapezoidal guidelines on the self-assembly of perpendicularly oriented lamellar morphologies. When both the sidewall and the top surface exhibit preferential interactions to the same block of the BCP, trapezoidal guidelines with intermediate taper angles were found to result in less defective perpendicularly orientated morphologies. Similarly, when the sidewall and top surface are preferential to distinct blocks of the BCP, intermediate tapering angles were found to be optimal in promoting defect free structures. Such results are rationalized based on the energetics arising in the formation of perpendicularly oriented lamella on patterned substrates.

Experimental aerodynamic characteristics for slender bodies with thin wings at angles of attack from 0 deg to 58 deg and Mach numbers from 0.6 to 2.0

NASA Technical Reports Server (NTRS)

Jorgensen, L. H.; Howell, M. H.

1976-01-01

An experimental investigation was conducted in the Ames 6-by-6-Foot Wind Tunnel to measure the static aerodynamic characteristics for bodies of circular and elliptic cross section with various thin flat-plate wings. Eighteen configuration combinations were tested at Mach numbers of 0.6, 0.9, 1.2, 1.5, and 2.0 at angles of attack from 0 deg to 58 deg. The data demonstrate that taper ratio and aspect ratio had only small effect on the aerodynamic characteristics, especially at the higher angles of attack. Undesirable side forces and yawing moments, which developed at angles of attack greater than about 25 deg, were generally no greater than those for the bodies tested alone. As for the bodies alone, the side forces and yawing moments increased as the nose fineness ratio increased and/or as the subsonic Mach number decreased.

Dynamic illumination of spatially restricted or large brain volumes via a single tapered optical fiber

PubMed Central

Pisanello, Marco; Oldenburg, Ian A.; Sileo, Leonardo; Markowitz, Jeffrey E.; Peterson, Ralph E.; Della Patria, Andrea; Haynes, Trevor M.; Emara, Mohamed S.; Spagnolo, Barbara; Datta, Sandeep Robert; De Vittorio, Massimo; Sabatini, Bernardo L.

2017-01-01

Optogenetics promises spatiotemporal precise control of neural processes using light. However, the spatial extent of illumination within the brain is difficult to control and cannot be adjusted using standard fiber optics. We demonstrate that optical fibers with tapered tips can be used to illuminate either spatially restricted or large brain volumes. Remotely adjusting the light input angle to the fiber varies the light-emitting portion of the taper over several millimeters without movement of the implant. We use this mode to activate dorsal versus ventral striatum of individual mice and reveal different effects of each manipulation on motor behavior. Conversely, injecting light over the full numerical aperture of the fiber results in light emission from the entire taper surface, achieving broader and more efficient optogenetic activation of neurons when compared to the standard flat-faced fiber stimulation. Thus, tapered fibers permit focal or broad illumination that can be precisely and dynamically matched to experimental needs. PMID:28628101

High-efficiency power transfer for silicon-based photonic devices

NASA Astrophysics Data System (ADS)

Son, Gyeongho; Yu, Kyoungsik

2018-02-01

We demonstrate an efficient coupling of guided light of 1550 nm from a standard single-mode optical fiber to a silicon waveguide using the finite-difference time-domain method and propose a fabrication method of tapered optical fibers for efficient power transfer to silicon-based photonic integrated circuits. Adiabatically-varying fiber core diameters with a small tapering angle can be obtained using the tube etching method with hydrofluoric acid and standard single-mode fibers covered by plastic jackets. The optical power transmission of the fundamental HE11 and TE-like modes between the fiber tapers and the inversely-tapered silicon waveguides was calculated with the finite-difference time-domain method to be more than 99% at a wavelength of 1550 nm. The proposed method for adiabatic fiber tapering can be applied in quantum optics, silicon-based photonic integrated circuits, and nanophotonics. Furthermore, efficient coupling within the telecommunication C-band is a promising approach for quantum networks in the future.

Dynamic illumination of spatially restricted or large brain volumes via a single tapered optical fiber.

PubMed

Pisanello, Ferruccio; Mandelbaum, Gil; Pisanello, Marco; Oldenburg, Ian A; Sileo, Leonardo; Markowitz, Jeffrey E; Peterson, Ralph E; Della Patria, Andrea; Haynes, Trevor M; Emara, Mohamed S; Spagnolo, Barbara; Datta, Sandeep Robert; De Vittorio, Massimo; Sabatini, Bernardo L

2017-08-01

Optogenetics promises precise spatiotemporal control of neural processes using light. However, the spatial extent of illumination within the brain is difficult to control and cannot be adjusted using standard fiber optics. We demonstrate that optical fibers with tapered tips can be used to illuminate either spatially restricted or large brain volumes. Remotely adjusting the light input angle to the fiber varies the light-emitting portion of the taper over several millimeters without movement of the implant. We use this mode to activate dorsal versus ventral striatum of individual mice and reveal different effects of each manipulation on motor behavior. Conversely, injecting light over the full numerical aperture of the fiber results in light emission from the entire taper surface, achieving broader and more efficient optogenetic activation of neurons, compared to standard flat-faced fiber stimulation. Thus, tapered fibers permit focal or broad illumination that can be precisely and dynamically matched to experimental needs.

Investigation of Wing Characteristics at a Mach Number of 1.53 II : Swept Wings of Taper Ratio 0.5

NASA Technical Reports Server (NTRS)

Vincenti, Walter G; Van Dyke, Milton D; Matteson, Frederick H

1948-01-01

Measured values of lift, drag, and pitching moment at M(sub o) = 1.53 are presented for seven wings varying in sweep angle from 60 degrees sweepforward to 60 degrees sweepback. All wings had a cambered, double-wedge section 5-percent thick and a common taper ratio of 0.5. The experimental results are compared with the predictions of the linear theory.

Tapered pulse tube for pulse tube refrigerators

DOEpatents

Swift, Gregory W.; Olson, Jeffrey R.

1999-01-01

Thermal insulation of the pulse tube in a pulse-tube refrigerator is maintained by optimally varying the radius of the pulse tube to suppress convective heat loss from mass flux streaming in the pulse tube. A simple cone with an optimum taper angle will often provide sufficient improvement. Alternatively, the pulse tube radius r as a function of axial position x can be shaped with r(x) such that streaming is optimally suppressed at each x.

Basic Pressure Measurements at Transonic Speeds on a Thin 45 deg Sweptback Highly Tapered Wing with Systematic Spanwise Twist Variations

NASA Technical Reports Server (NTRS)

Mugler, John P., Jr.

1958-01-01

Pressure distributions are presented for a thin highly tapered untwisted 45 deg sweptback wing in combination with a body. These tests were made in the Langley 8-foot transonic pressure tunnel at both 1.0 and 0.5 atmosphere stagnation pressures at Mach numbers from 0.800 to 1.200 through an angle-of-attack range of -4 deg to 12 deg.

Zero degree contour cutting below 100 μm feature size with femtosecond laser

NASA Astrophysics Data System (ADS)

Stolberg, Klaus; Friedel, Susanna

2016-03-01

By the use of a 16 W femtosecond laser we demonstrate steep wall angles and small feature spacings for non-thermal melt-free laser drilling and contour cutting of 100 to 500 μm thick metals like Cu-alloy, stainless steel, titanium and tantalum as well as for ceramics and polymer (polycarbonate). Especially processing of thin materials is a challenge, because heat accumulation in thermal processing usually causes mechanical distortion or edge melting as well as material. The combination of beam deflection in trepanning optics and sample motion allowed us to work in a special "laser milling mode" with rotating beam. Zero degree taper angle as well as positive or negative tapers can be achieved at micrometer scale.

Theoretical stability and control characteristics of wings with various amounts of taper and twist

NASA Technical Reports Server (NTRS)

Pearson, Henry A; Jones, Robert T

1938-01-01

Stability derivatives have been computed for twisted wings of different plan forms that include variations in both the wing taper and the aspect ratio. Taper ratios of 1.0, 0,50, and 0.25 are considered for each of three aspect ratios: 6, 10, and 16. The specific derivatives for which results are given are the rolling-moment and the yawing-moment derivatives with respect to (a) rolling velocity, (b) yawing velocity, and (c) angle of sideslip. These results are given in such a form that the effect of any initial symmetrical wing twist (such as may be produced by flaps) on the derivatives may easily be taken into account. In addition to the stability derivatives, results are included for determining the theoretical rolling moment due to aileron deflection and a series of influence lines is given by which the loading across the span may be determined for any angle-of-attack distribution that may occur on the wing plan forms considered. The report also includes incidental references to the application of the results.

Orthodontic Bracket Manufacturing Tolerances and Dimensional Differences between Select Self-Ligating Brackets

PubMed Central

Major, Thomas W.; Carey, Jason P.; Nobes, David S.; Major, Paul W.

2010-01-01

In all manufacturing processes there are tolerances; however, orthodontic bracket manufacturers seldom state the slot dimensional tolerances. This experiment develops a novel method of analyzing slot profile dimensions using photographs of the slot. Five points are selected along each wall, and lines are fitted to define a trapezoidal slot shape. This investigation measures slot height at the slot's top and bottom, angles between walls, slot taper, and the linearity of each wall. Slot dimensions for 30 upper right central incisor self-ligating stainless steel brackets from three manufacturers were evaluated. Speed brackets have a slot height 2% smaller than the nominal 0.559 mm size and have a slightly convergent taper. In-Ovation brackets have a divergent taper at an average angle of 1.47 degrees. In-Ovation is closest to the nominal value of slot height at the slot base and has the smallest manufacturing tolerances. Damon Q brackets are the most rectangular in shape, with nearly 90-degree corners between the slot bottom and walls. Damon slot height is on average 3% oversized. PMID:20981299

Evaluation of the Orogenic Belt Hypothesis for the Formation of Thaumasia, Mars

NASA Astrophysics Data System (ADS)

Nahm, A. L.; Schultz, R. A.

2008-12-01

The Thaumasia Highlands (TH) and Solis Planum are two of the best-known examples of compressional tectonics on Mars. The TH is a region of high topography located in the southern portion of the Tharsis Province, Mars. Solis Planum is located in eastern Thaumasia. Two hypotheses for the formation of this region have been suggested: sliding on a weak horizon or thrusting analogous to orogenic wedges on Earth. Both hypotheses require a shallowly dipping to sub-horizontal weak horizon below Thaumasia. Wrinkle ridges in Solis Planum are also inferred to sole into a décollement. If Thaumasia formed by thrusting related to sliding on a décollement, then certain conditions must be met as in critical taper wedge mechanics (CTWM) theory. If the angle between the surface slope and the basal décollement is less than predicted by the critical taper equation, the 'subcritical' wedge will deform internally until critical taper is achieved. Once the critical taper has been achieved, internal deformation ceases and the wedge will slide along its base. Formation of orogenic belts on Earth (such as the Central Mountains in Taiwan) can be described using CTWM. This method is applied here to the Thaumasia region on Mars. The surface slope (alpha) was measured in three locations: Syria Planum-Thaumasia margin, Solis Planum, and the TH. Topographic slopes were compared to the results from the critical taper equation. Because the dip of the basal décollement (beta) cannot be measured directly as on Earth, the dip angle was varied at 0 - 10 degrees; these values span the range of likely values based on terrestrial wedges. Pore fluid pressure (lambda) was varied between 0 (dry) and 0.9 (overpressured); these values span the full range of this important unknown parameter. Material properties, such as the coefficients of internal friction and of the basal décollement, were varied using reasonable values. Preliminary results show that for both reasonable (such as lambda = 0, mu b = 0.85, beta = 0 deg) and extreme (such as lambda = 0.9, mu b = 0.1, beta greater than 0 deg) values of the parameters for Mars, the predicted critical taper angle was typically lower than the measured slope, rendering the orogenic belt hypothesis for the formation of the TH invalid. Comparable analysis of Solis Planum shows it also lacks a décollement.

Tests of three tapered airfoils based on the N.A.C.A. 2200, the N.A.C.A.-M6, and the Clark Y sections

NASA Technical Reports Server (NTRS)

Anderson, Raymond F

1934-01-01

Three tapered airfoils based on the N.A.C.A. 2200, the N.A.C.A.-M6, and the Clark Y sections were tested in the variable-density wind tunnel at a Reynolds Number of approximately 3,100,000. The models, which were of aspect ratio 6, had constant core center sections and rounded tips, and tapered in thickness from 18 percent at the roots to 9 percent at the tips. The aerodynamic characteristics are given by the usual dimensionless coefficients plotted for both positive and negative angles of attack and by effective profile-drag coefficients plotted against lift coefficients.

Wing-Alone Aerodynamic Characteristics to High Angles of Attack at Subsonic and Transonic Speeds.

DTIC Science & Technology

1982-11-01

support subsystems, the test- ing of these models consumes a disproportionate amount of model construction effort and wind-tunnel testing time compared...constant taper ratio with the exception of the aspect ratio 4, taper ratio 0.5 wing at subsonic speeds; the anomalous behavior of this wing is likely...0000000 ...... 0 0 0i 010... 0.. .......... .. .............. tt.. 4t t * PS4 Oft* .. MM.~0o004.0 s.t~o.4

A comparison of three Ni-Ti rotary instruments in apical transportation.

PubMed

Javaheri, Homan Hossein; Javaheri, Ghasem Hossein

2007-03-01

The purpose of this study was to compare apical transportation and changes in canal curvature of three nickel-titanium (Ni-Ti) rotary instruments: Hero 642, RaCe, and ProTaper. Mesiobuccal canals of 60 maxillary first molars (with angles of curvature between 25 degrees and 35 degrees) were prepared with a torque-control, low-speed engine. Canals were prepared using the crown-down technique to the size of #30. Using a radiographic platform, reproducible preinstrumentation and postinstrumentation radiographs were taken. A computer analysis allowed magnification and superimposition of the images. The central axes of initial and final instruments were radiographically superimposed to measure transportation at 1 mm from WL. Data were analyzed using repeated-measures ANOVA. A statistically significant difference in apical transportation was found in ProTaper group. The results suggest that ProTaper file system be implemented in combination with other less tapered more flexible systems, like RaCe, in preparing curved canals.

Nonimaging optics in luminescent solar concentration.

PubMed

Markman, B D; Ranade, R R; Giebink, N C

2012-09-10

Light trapped within luminescent solar concentrators (LSCs) is naturally limited in angular extent by the total internal reflection critical angle, θcrit, and hence the principles of nonimaging optics can be leveraged to increase LSC concentration ratio by appropriately reshaping the edges. Here, we use rigorous ray-tracing simulations to explore the potential of this concept for realistic LSCs with compound parabolic concentrator (CPC)-tapered edges and show that, when applied to a single edge, the concentration ratio is increased by 23% while maintaining >90% of the original LSC optical efficiency. Importantly, we find that CPC-tapering all of the edges enables a significantly greater intensity enhancement up to 35% at >90% of the original optical efficiency, effectively enabling two-dimensional concentration through a cooperative, ray-recycling effect in which rays rejected by one CPC are accepted by another. These results open up a significant opportunity to improve LSC performance at virtually no added manufacturing cost by incorporating nonimaging optics into their design.

Retention Load Values of Telescopic Crowns Made of Y-TZP and CoCr with Y-TZP Secondary Crowns: Impact of Different Taper Angles

PubMed Central

Merk, Susanne; Wagner, Christina; Stock, Veronika; Schmidlin, Patrick R.; Roos, Malgorzata; Eichberger, Marlis; Stawarczyk, Bogna

2016-01-01

This study aimed to examine and compare the retention load values (RL) of different telescopic crown assemblies (Y-TZP and CoCr primary crowns with electroformed and Y-TZP secondary crowns each) with three different taper angles (0°, 1° and 2°). Thirty Y-TZP primary crowns with electroformed gold copings (Z/G group) and Y-TZP secondary crowns (Z/Z group) and 30 CoCr primary crowns with electroformed gold copings (C/G group) and Y-TZP secondary crowns (C/Z group), each with taper angles of 0°, 1° and 2°, were fabricated, respectively. With the exception of the electroformed gold copings, all specimens were Computer-Aided-Design/Computer-Aided-Manufacturing (CAD/CAM)-milled, then sintered and afterwards manually adapted. In order to stabilize the gold copings, they were fixed in a tertiary structure. The secondary crowns were constructed with a hook, which ensured self-alignment with an upper chain. Afterwards, 20 pull-off test cycles were performed in a universal testing machine under artificial saliva and after weighing the secondary crowns with a 5 kg object for 20 s. Data were analyzed by one-way and two-way Analysis of Variance (ANOVA). C/Z with 1° showed higher (p = 0.009) RL than 0° and 2° tapers. C/G at 1° also showed higher (p = 0.001) RL than at tapers of 0° and 2°. Z/G and C/G at 0° showed lower RL than Z/Z and C/Z (p < 0.001). Primary crowns had no impact on the 0° group. Z/G showed lower RL as compared to C/Z within the 1° group (p = 0.007) and Z/Z in the 2° group (p = 0.006). The primary crown material had no influence on RL. Electroformed copings showed lower RL. Further investigations for 1° as well as for the long-term performance after thermomechanical aging are necessary. PMID:28773477

Incident polarization angle and temperature dependence of polarization and spectral response characteristics in optical fiber couplers.

PubMed

Namihira, Y; Kawazawa, T; Wakabayashi, H

1991-03-20

The incident polarization angle and temperature dependence of the polarization and spectral response characteristics of three different types of fiber coupler are presented. The couplers are (1) the biconicalfused- twisted-taper single-mode fiber (coupler A), (2) the asymmetric-etched-fused-taper wavelength division multiplex (coupler B), and (3) the biconical-polished polarization maintaining fiber (coupler C), respectively. It is confirmed experimentally that the polarization characteristics of couplers A and B vary greatly with temperature, but those of coupler C are independent of temperature. Also, the wavelength dependence characteristics of the power splitting ratio of couplers B and C have almost no change with temperature. However, the wavelength dependence of coupler A is greatly changed with temperature. Comparing couplers A and B, it is postulated that the sinusoidal variations of the polarization state vs the incident polarization angle are due to the stress birefringence caused by the fiber twisting when the fused fiber coupler is fabricated and packaged.

Optical loss analysis and parameter optimization for fan-shaped single-polarization grating coupler at wavelength of 1.3 µm band

NASA Astrophysics Data System (ADS)

Ushida, Jun; Tokushima, Masatoshi; Sobu, Yohei; Shimura, Daisuke; Yashiki, Kenichiro; Takahashi, Shigeki; Kurata, Kazuhiko

2018-05-01

Fan-shaped grating couplers (F-GCs) can be smaller than straight ones but are less efficient in general in coupling to single-mode fibers. To find a small F-GC with sufficiently high fiber-coupling characteristics, we numerically compared the dependencies of coupling efficiencies on wavelengths, the starting width of gratings, and misalignment distances among 25, 45, and 60° tapered angles of fan shape by using the three-dimensional finite-difference time domain method. A F-GC with a tapered angle of 25° exhibited the highest performances for all dependencies. The optical loss origins of F-GCs were discussed in terms of the electric field structures in them and scattering at the joint between the fan-shaped slab and channel waveguide. We fabricated an optimized 25° F-GC by using ArF photolithography, which almost exactly reproduced the optical coupling efficiency and radiation angle characteristics that were numerically expected.

Cyclic fatigue resistance of two nickel-titanium rotary instruments in interrupted rotation.

PubMed

Pedullà, E; Lizio, A; Scibilia, M; Grande, N M; Plotino, G; Boninelli, S; Rapisarda, E; Lo Giudice, G

2017-02-01

To investigate the influence of interrupted rotation on cyclic fatigue of two nickel-titanium rotary instruments. Cyclic fatigue of 300 new ProTaper Next size X1; X2 and Mtwo size 10, .04 taper; size 15, .05 taper; size 20, .06 taper and size 25, .06 taper instruments was tested in continuous or interrupted rotation. Fifty files of the same brand and size were randomly assigned to five groups (n = 10). Group 1 instruments were tested in continuous rotation; groups 2 and 3 in paused rotation for 1 s every 10 or 20 s, respectively; groups 4 and 5 in interrupted rotation for 5 s every 10 or 20 s, respectively. Cyclic fatigue was expressed in time to fracture (TtF) in an artificial canal with 60° angle and 5 mm radius of curvature. The fracture surface was examined with a scanning electron microscope (SEM). Data were evaluated by two-way analysis of variance. Cyclic fatigue of groups 2 and 4 of ProTaper Next X2 and Mtwo size 25, .06 taper was significantly lower than that of group 1 of the same instruments (P < 0.01). ProTaper Next X2 had significantly reduced cyclic fatigue in groups 3 and 5 (P < 0.05). No differences were found by interrupting the rotation for 1 or 5 s in all instruments (P > 0.05). Fatigue of other instruments was not affected by interrupted rotation (P > 0.05). Interrupted rotation reduced cyclic fatigue resistance of ProTaper Next X2 and Mtwo size 25, .06 taper, especially when a higher number of interruptions was performed. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Charts for Determining Preliminary Values of Span-load, Shear, Bending-moment, and Accumulated-torque Distributions of Swept Wings of Various Taper Ratios

NASA Technical Reports Server (NTRS)

Wollner, Bertram C

1948-01-01

Contains charts for use in determining preliminary values of the spanwise-load, shear, bending-moment, and accumulated-torque distributions of swept wings. The charts are based on strip theory and include four aerodynamic-load distributions, two section-moment distributions, and two inertia-load distributions. The taper ratios considered cover the range from 1.0 to 0 and the results are applicable to any angle of sweep.

Nonlinear acoustic streaming in straight and tapered tubes

NASA Astrophysics Data System (ADS)

Tuttle, Brian C.

In thermoacoustic and Stirling devices such as the pulse-tube refrigerator, efficiency is diminished by the formation of a second-order mean velocity known as Rayleigh streaming. This flow emerges from the interaction of the working gas with the wall of the tube in a thin boundary layer. Recent studies have suggested that streaming velocity can be decreased in a tube by tapering it slightly. This research investigates that claim through the development of a numerical model of Rayleigh streaming in variously tapered tubes. It is found that the numerical simulation of streaming in a straight tube compares well with theory, and the application of different thermal boundary conditions at the tube wall shows that for pressurized helium, inner streaming vortices which appear near an adiabatic tube wall do not develop near an isothermal wall. An order analysis indicates that the temperature dependence of viscosity and thermal conductivity contributes appreciably to an accurate numerical model of streaming. Comparison of Rayleigh streaming in tapered tubes shows the effects of taper angle on the circulation and velocity of the mean flow.

Vibration sensitivity of the scanning near-field optical microscope with a tapered optical fiber probe.

PubMed

Chang, Win-Jin; Fang, Te-Hua; Lee, Haw-Long; Yang, Yu-Ching

2005-01-01

In this paper the Rayleigh-Ritz method was used to study the scanning near-field optical microscope (SNOM) with a tapered optical fiber probe's flexural and axial sensitivity to vibration. Not only the contact stiffness but also the geometric parameters of the probe can influence the flexural and axial sensitivity to vibration. According to the analysis, the lateral and axial contact stiffness had a significant effect on the sensitivity of vibration of the SNOM's probe, each mode had a different level of sensitivity and in the first mode the tapered optical fiber probe was the most acceptive to higher levels of flexural and axial vibration. Generally, when the contact stiffness was lower, the tapered probe was more sensitive to higher levels of both axial and flexural vibration than the uniform probe. However, the situation was reversed when the contact stiffness was larger. Furthermore, the effect that the probe's length and its tapered angle had on the SNOM's probe axial and flexural vibration were significant and these two conditions should be incorporated into the design of new SNOM probes.

Intra-aortic balloon shape change: effects on volume displacement during inflation and deflation.

PubMed

Khir, Ashraf William; Bruti, Gianpaolo

2013-07-01

It has been observed that operating the intra-aortic balloon at an angle to the horizontal resulted in a reduction of the volume displaced toward the coronary arteries and compromised afterload reduction. Therefore, the aim of this work is to examine whether changing the current balloon shape, which has not been altered for 40 years, could compensate for the negative hemodynamic effects due to angulation. We tested two tapered balloons, increasing diameter (TID) and decreasing diameter (TDD), and compared the results with those obtained from a standard cylindrical balloon. The balloons were tested in vitro at 60 beats/min and a static pressure of 90 mm Hg. The balloons were operated at four angles (0°, 20°, 30°, 45°), and the pressure at three locations along the balloon (base, middle, and tip) was also measured. Flow rate upstream of the tip of the balloon was also measured to indicate the flow displaced toward the coronary circulation. The relative volume displaced toward (VUTVi) and suctioned away from (VUTVd) the simulated ascending aorta, during inflation and deflation, respectively, is reduced when a standard cylindrical balloon is operated at an angle to the horizontal. The TDD provided the greatest VUTVi and also produced the largest pulse pressure during deflation. Although the TID provided less VUTVi and VUTVd at smaller angles, it was not markedly affected by the change of angle. According to these results, different balloon shapes analyzed, with comparable volume to that of a cylindrical balloon, produced greater inflation and deflation benefits, at the horizontal and at a range of angles to the horizontal. Further investigations are required to optimize the shape of the tapered balloons to fit into the available physiological space. © 2013 Wiley Periodicals, Inc. and International Center for Artificial Organs and Transplantation.

Comparative study of ProTaper gold, reciproc, and ProTaper universal for root canal preparation in severely curved root canals

PubMed Central

Arslan, Hakan; Yildiz, Ezgi Doganay; Gunduz, Hicran Ates; Sumbullu, Meltem; Bayrakdar, Ibrahim Sevki; Karatas, Ertugrul; Sumbullu, Muhammed Akif

2017-01-01

Aim: The aim of this study is to evaluate the root canal transportation, centering ability, and instrumentation times with the ProTaper Gold (Dentsply Tulsa Dental, Tulsa, OK, USA), Reciproc (VDW, Munich, Germany), and ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland) using cone-beam computed tomography (CBCT). Materials and Methods: Thirty mesial root canals of mandibular first molars with curvature angles of 35°–70° and radii of 2–6 mm were included in the study. Root canal instrumentation was performed up to F2 or R25. The instrumentation times were recorded. CBCT scanning was performed both pre- and post-instrumentation. Root canal transportation and the centering ratio were calculated for groups, and the data were analyzed using a one-way ANOVA and least significant difference post hoc tests for the instrumentation time, root canal transportation, and centering ratio at the 95% confidence level (P = 0.05). Results: At 3, 5, and 7 mm levels, there was no significant difference in the root canal transportation and centering ratio among the groups (P > 0.05). There were significant differences between the Reciproc and ProTaper Universal groups in the instrumentation times (P < 0.05). Conclusion: Root canal transportation and the centering ratio with the ProTaper Gold were similar to those obtained with the ProTaper Universal and Reciproc. PMID:29259355

Enhancing the hydrodynamic performance of a tapered swept-back wing through leading-edge tubercles

NASA Astrophysics Data System (ADS)

Wei, Zhaoyu; Lian, Lian; Zhong, Yisen

2018-06-01

The hydrodynamic benefit of implementing leading-edge (LE) tubercles on wings at very low Reynolds numbers ( Res) has not been thoroughly elucidated to date, though their benefits at relatively higher Res are well-studied. Through wind tunnel testing at Re = 5.5 × 104, we found that the LE tubercles increase the lift at all pitch angles tested and slightly reduce the drag at a pitch angle of 4° < α < 10°, which finally results in a significant hydrodynamic performance enhancement at lower pitch angles. Flow visualization reveals that the hydrodynamic performance enhancement is due to the favourable attached flows downstream of the tubercle peaks. The attached flows are believed to be closely related to the downwash and momentum exchange within the boundary layers, which originate from surface and streamwise-aligned counter-rotating vortex pairs (CVPs).

Influence of radiation on MHD peristaltic blood flow through a tapered channel in presence of slip and joule heating

NASA Astrophysics Data System (ADS)

Ahamad, N. Ameer; Ravikumar, S.; Govindaraju, Kalimuthu

2017-07-01

The aim of the present attempt was to investigate an effect of slip and joule heating on MHD peristaltic Newtonian fluid through an asymmetric vertical tapered channel under influence of radiation. The Mathematical modeling is investigated by utilizing long wavelength and low Reynolds number assumptions. The effects of Hartmann number, porosity parameter, volumetric flow rate, radiation parameter, non uniform parameter, shift angle, Prandtl number, Brinkman number, heat source/sink parameter on temperature characteristics are presented graphically and discussed in detail.

Tapered microelectrode array system for dielectrophoretically filtration: fabrication, characterization, and simulation study

NASA Astrophysics Data System (ADS)

Buyong, Muhamad Ramdzan; Larki, Farhad; Takamura, Yuzuru; Majlis, Burhanuddin Yeop

2017-10-01

This paper presents the fabrication, characterization, and simulation of microelectrode arrays system with tapered profile having an aluminum surface for dielectrophoresis (DEP)-based manipulation of particles. The proposed structure demonstrates more effective electric field gradient compared with its counterpart with untapered profile. Therefore, according to the asymmetric distribution of the electric field in the active region of microelectrode, it produces more effective particle manipulation. The tapered aluminum microelectrode array (TAMA) fabrication process uses a state-of-the-art technique in the formation of the resist's taper profile. The performance of TAMA with various sidewall profile angles (5 deg to 90 deg) was analyzed through finite-element method numerical simulations to offer a better understanding of the origin of the sidewall profile effect. The ability of capturing and manipulating of the device was examined through modification of the Clausius-Mossotti factor and cross-over frequency (f). The fabricated system has been particularly implemented for filtration of particles with a desired diameter from a mixture of particles with three different diameters in an aqueous medium. The microelectrode system with tapered side wall profile offers a more efficient platform for particle manipulation and sensing applications compared with the conventional microelectrode systems.

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

NASA Astrophysics Data System (ADS)

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.

Strong field acceleration and steering of ultrafast electron pulses from a sharp metallic nanotip.

PubMed

Park, Doo Jae; Piglosiewicz, Bjoern; Schmidt, Slawa; Kollmann, Heiko; Mascheck, Manfred; Lienau, Christoph

2012-12-14

We report a strong, laser-field induced modification of the propagation direction of ultrashort electron pulses emitted from nanometer-sized gold tapers. Angle-resolved kinetic energy spectra of electrons emitted from such tips are recorded using ultrafast near-infrared light pulses of variable wavelength and intensity for excitation. For sufficiently long wavelengths, we observe a pronounced strong-field acceleration of electrons within the field gradient at the taper apex. We find a distinct narrowing of the emission cone angle of the fastest electrons. We ascribe this to the field-induced steering of subcycle electrons as opposed to the diverging emission of quiver electrons. Our findings are corroborated by simulations based on a modified Simpleman model incorporating the curved, vectorial field gradient in the vicinity of the tip. Our results indicate new pathways for designing highly directional nanometer-sized ultrafast electron sources.

Stability and control characteristics of an airplane model having a 45.1 degree swept-back wing with aspect ratio 2.50 and taper ratio 0.42 and a 42.8 degree swept-back horizontal tail with aspect ratio 3.87 and taper ratio 0.49

NASA Technical Reports Server (NTRS)

Schuldenfrei, Marvin; Comisarow, Paul; Goodson, Kenneth W

1947-01-01

Tests were made of an airplane model having a 45.1 degree swept-back wing with aspect ratio 2.50 and taper ratio 0.42 and a 42.8 degree swept-back horizontal tail with aspect ratio 3.87 and taper ratio 0.49 to determine its low-speed stability and control characteristics. The test Reynolds number was 2.87 x 10(6) based on a mean aerodynamic chord of 2.47 feet except for some of the aileron tests which were made at a Reynolds number of 2.05 x 10(6). With the horizontal tail located near the fuselage juncture on the vertical tail, model results indicated static longitudinal instability above a lift coefficient that was 0.15 below the lift coefficient at which stall occurred. Static longitudinal stability, however, was manifested throughout the life range with the horizontal tail located near the top of the vertical tail. The use of 10 degrees negative dihedral on the wing had little effect on the static longitudinal stability characteristics. Preliminary tests of the complete model revealed an undesirable flat spot in the yawing-moment curves at low angles of attack, the directional stability being neutral for yaw angles of plus-or-minus 2 degrees. This undesirable characteristic was improved by replacing the thick original vertical tail with a thin vertical tail and by flattening the top of the dorsal fairing.

Finite element analysis of mechanics of lateral transmission of force in single muscle fiber.

PubMed

Zhang, Chi; Gao, Yingxin

2012-07-26

Most of the myofibers in long muscles of vertebrates terminate within fascicles without reaching either end of the tendon, thus force generated in myofibers has to be transmitted laterally through the extracellular matrix (ECM) to adjacent fibers; which is defined as the lateral transmission of force in skeletal muscles. The goal of this study was to determine the mechanisms of lateral transmission of force between the myofiber and ECM. In this study, a 2D finite element model of single muscle fiber was developed to study the effects of mechanical properties of the endomysium and the tapered ends of myofiber on lateral transmission of force. Results showed that most of the force generated is transmitted near the end of the myofiber through shear to the endomysium, and the force transmitted to the end of the model increases with increased stiffness of ECM. This study also demonstrated that the tapered angle of the myofiber ends can reduce the stress concentration near the myofiber end while laterally transmitting force efficiently. Copyright © 2012 Elsevier Ltd. All rights reserved.

Charge deposition dependence of electron transmission through PET nanocapillaries and a tapered glass microcapillary

NASA Astrophysics Data System (ADS)

Tanis, J. A.; Keerthisinghe, D.; Wickramarachchi, S. J.; Ikeda, T.; Stolterfoht, N.

2018-05-01

Charge deposition dependences of electron transmission through insulating PET nanocapillaries and a tapered glass microcapillary are reported and differences with HCI transmission are noted. Investigations were conducted for electrons with incident energies 500-1000 eV, corresponding to energies per charge similar to those used for HCI studies, incident on (1) an array of PET nanocapillaries (density ∼5 × 108/cm2) with diameters 100 nm in a foil of thickness 12 μm, and (2) on a tapered glass microcapillary with inlet/outlet diameters of 800/100 μm and a length of ∼35 mm. The transmission was measured for incident electrons at small sample tilt angles ranging from 0° to 5° with respect to the beam direction. For most angles, including those near zero degrees, there was an initial quiet period during which essentially no transmission was observed, followed by large rises in the transmission during relatively short periods of charge deposition before equilibrium of the transmission was reached. The resulting equilibrium was stable, blocked or had frequent oscillations depending on the incident energy and the capillary used. Observations for both capillaries show that a negative charge patch is needed to guide incident electrons through the capillaries similar to the manner in which HCIs are guided through capillaries.

Atmospheric microwave refractivity and refraction

NASA Technical Reports Server (NTRS)

Yu, E.; Hodge, D. B.

1980-01-01

The atmospheric refractivity can be expressed as a function of temperature, pressure, water vapor content, and operating frequency. Based on twenty-year meteorological data, statistics of the atmospheric refractivity were obtained. These statistics were used to estimate the variation of dispersion, attenuation, and refraction effects on microwave and millimeter wave signals propagating along atmospheric paths. Bending angle, elevation angle error, and range error were also developed for an exponentially tapered, spherical atmosphere.

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

PubMed

Witt, Florian; Gührs, Julian; Morlock, Michael M; Bishop, Nicholas E

2015-01-01

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.

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

PubMed Central

Witt, Florian; Gührs, Julian; Morlock, Michael M.; Bishop, Nicholas E.

2015-01-01

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. PMID:26280914

Investigation of the Characteristics of a High-Aspect-Ratio Wing in the Langley 8-Foot High-Speed Tunnel

NASA Technical Reports Server (NTRS)

Whitcomb, Richard T.

1940-01-01

An investigation of the characteristics of a wing with an aspect ratio of 9.0 and an NACA 65-210 airfoil section has been made at Mach number up to 0.925. The wing tested has a taper ratio of 2.5:1.0, no twist, dihedral, or sweepback, and 20-percent - chord 37.5-percent-semispan plain ailerons. The results showed that serious changes in the normal-force characteristics occurred when the Mach number was increased above 0.74 at angles of attack between 4 deg. and 10 deg. and above 0.80 at 0 deg. angle of attack.Because of small outboard shifts in the lateral center of load, the bending moment at the root for conditions corresponding to a 3g pull-out at an altitude of 35,000 feet increased by approximately 5% when the Much number was increased beyond 0.83 the negative pitching moments for the high angles of attack increased, whereas those for the low angles of attack decreased with a resulting large increase in the negative slope of the pitching-moment curves. A large increase occurred in the values of the drag coefficients for the range of lift coefficients needed for level flight at an altitude of 35,000 feet when the Mach number was increased beyond a value of 0.80. The wakes at a station 2.82 root chords behind the wing quarter-chord line extended approximately a chord above the wing chord line for the angles of attack required to recover from high-speed dives at high Mach numbers.

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

PubMed Central

Hasheminia, Seyed Mohsen

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 < 0.001). There were significant relationships between the angle of curvature, transportation and curve straightening in pairs (P < 0.001). Apical patency is recommended during root canal preparation with the ProTaper rotary system. PMID:24159390

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

PubMed

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 < 0.001). There were significant relationships between the angle of curvature, transportation and curve straightening in pairs (P < 0.001). Apical patency is recommended during root canal preparation with the ProTaper rotary system.

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

PubMed Central

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. PMID:26509152

Tapered optical fiber tip probes based on focused ion beam-milled Fabry-Perot microcavities

NASA Astrophysics Data System (ADS)

André, Ricardo M.; Warren-Smith, Stephen C.; Becker, Martin; Dellith, Jan; Rothhardt, Manfred; Zibaii, M. I.; Latifi, H.; Marques, Manuel B.; Bartelt, Hartmut; Frazão, Orlando

2016-09-01

Focused ion beam technology is combined with dynamic chemical etching to create microcavities in tapered optical fiber tips, resulting in fiber probes for temperature and refractive index sensing. Dynamic chemical etching uses hydrofluoric acid and a syringe pump to etch standard optical fibers into cone structures called tapered fiber tips where the length, shape, and cone angle can be precisely controlled. On these tips, focused ion beam is used to mill several different types of Fabry-Perot microcavities. Two main cavity types are initially compared and then combined to form a third, complex cavity structure. In the first case, a gap is milled on the tapered fiber tip which allows the external medium to penetrate the light guiding region and thus presents sensitivity to external refractive index changes. In the second, two slots that function as mirrors are milled on the tip creating a silica cavity that is only sensitive to temperature changes. Finally, both cavities are combined on a single tapered fiber tip, resulting in a multi-cavity structure capable of discriminating between temperature and refractive index variations. This dual characterization is performed with the aid of a fast Fourier transform method to separate the contributions of each cavity and thus of temperature and refractive index. Ultimately, a tapered optical fiber tip probe with sub-standard dimensions containing a multi-cavity structure is projected, fabricated, characterized and applied as a sensing element for simultaneous temperature and refractive index discrimination.

Tests of Round and Flat Spoilers on a Tapered Wing in the NACA 19-Foot Pressure Wind Tunnel

NASA Technical Reports Server (NTRS)

Wenzinger, Carl J; Bowen, John D

1941-01-01

Several arrangements of round and flat spanwise spoilers attached to the upper surface of a tapered wing were tested in the NACA 19-foot pressure wind tunnel to determine the most effective type, location, and size of spoiler necessary to reduce greatly the lift on the wings of large flying boats when moored. The effect of the various spoilers on the lift, the drag, and the pitching-moment characteristics of the tapered wing was measured over a range of angles of attack from zero to maximum lift. The most effective type of spoiler was found to be the flat type with no space between it and the wing surface. The chordwise location of such a spoiler was not critical within the range investigated, from 5 to 20 percent of the wing chord from the leading edge.

Design of multiple-ply laminated composite tapered beams

NASA Technical Reports Server (NTRS)

Rodriguez, P.

1993-01-01

A study of a special case of symmetric laminated composite cantilever beams is presented. The approach models beams that are tapered both in depth and width and investigates the effect of the ply layup angle and the ply taper on bending and interlaminar shearing stresses. For the determination of stresses and deflections, the beam stiffness matrices are expressed as linear functions of the beam length. Using classical lamination theory (CLT) the stiffness matrices are determined and assembled at strategic locations along the length of the beam. They are then inverted and necessary stiffness parameters are obtained numerically and extracted for determination of design information at each location chosen. Several ply layup configurations are investigated, and design considerations are presented based on the findings. Finally, recommendations for the design of these beams are presented, and a means for anticipating the location of highest stresses is offered.

Design of multiple-ply laminated composite tapered beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez, P.

1993-06-01

A study of a special case of symmetric laminated composite cantilever beams is presented. The approach models beams that are tapered both in depth and width and investigates the effect of the ply layup angle and the ply taper on bending and interlaminar shearing stresses. For the determination of stresses and deflections, the beam stiffness matrices are expressed as linear functions of the beam length. Using classical lamination theory (CLT) the stiffness matrices are determined and assembled at strategic locations along the length of the beam. They are then inverted and necessary stiffness parameters are obtained numerically and extracted formore » determination of design information at each location chosen. Several ply layup configurations are investigated, and design considerations are preSDsented based on the findings. Finally, recommendations for the design of these beams are presented, and a means for anticipating the location of highest stresses is offered.« less

Influence of cyclic torsional preloading on cyclic fatigue resistance of nickel - titanium instruments.

PubMed

Pedullà, E; Lo Savio, F; Boninelli, S; Plotino, G; Grande, N M; Rapisarda, E; La Rosa, G

2015-11-01

To evaluate the effect of different torsional preloads on cyclic fatigue resistance of endodontic rotary instruments constructed from conventional nickel-titanium (NiTi), M-Wire or CM-Wire. Eighty new size 25, 0.06 taper Mtwo instruments (Sweden & Martina), size 25, 0.06 taper HyFlex CM (Coltene/Whaledent, Inc) and X2 ProTaper Next (Dentsply Maillefer) were used. The Torque and distortion angles at failure of new instruments (n = 10) were measured, and 0% (n = 10), 25%, 50% and 75% (n = 20) of the mean ultimate torsional strength as preloading condition were applied according to ISO 3630-1 for each brand. The twenty files tested for every extent of preload were subjected to 20 or 40 torsional cycles (n = 10). After torsional preloading, the number of cycles to failure was evaluated in a simulated canal with 60° angle of curvature and 5 mm of radius of curvature. Data were analysed using two-way analysis of variance. The fracture surface of each fragment was examined with a scanning electron microscope (SEM). Data were analysed by two-way analyses of variance. Preload repetitions did not influence the cyclic fatigue of the three brands; however, the 25%, 50% and 75% torsional preloading significantly reduced the fatigue resistance of all instruments tested (P < 0.01, P < 0.001 and P < 0.0001, respectively) except for the HyFlex CM preloaded with 25% of the maximum torsional strength (P > 0.05). Torsional preloads reduced the cyclic fatigue resistance of conventional and treated (M-wire and CM-wire) NiTi rotary instruments except for size 25, 0.06 taper HyFlex CM instruments with a 25% of torsional preloading. © 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.

The influence of simulated clinical use on the flexibility of rotary ProTaper Universal, K3 and EndoSequence nickel-titanium instruments.

PubMed

Viana, A C D; Pereira, E S J; Bahia, M G A; Buono, V T L

2013-09-01

To investigate the influence of cyclic flexural and torsional loading on the flexibility of ProTaper Universal, K3 and EndoSequence nickel-titanium instruments, in view of the hypothesis that these types of loading would decrease the flexibility of the selected NiTi rotary files. The instruments evaluated were S2 and F1 ProTaper Universal, sizes 20 and 25, .06 taper K3, and sizes 20 and 25, .06 taper EndoSequence. Flexibility was determined by 45° bending tests according to ISO 3630-1 specification. Values of the bending moment (MB ) obtained with new instruments were considered as the control group (CG). Bending tests were then conducted in instruments previously fatigued to one-fourth and three-fourths of their average fatigue life (fatigue groups, FG¼ and FG¾), as well as after cyclic torsional loading (torsional group, TG). Fatigue tests were carried out in a bench device that allowed the files to rotate freely inside an artificial canal with an angle of curvature of 45° and a radius of 5 mm. Cyclic torsional loading tests were performed that entailed rotating the instrument from zero angular deflection to 180° and then returning to zero applied torque in 20 cycles. Data were analysed using one-way analysis of variance at a significance level of 5%. Simulated clinical use by means of flexural fatigue tests did not affect the flexibility of the instruments, except for a significant increase in flexibility observed in a few instruments (P < 0.05). In addition, comparative statistical analyses between the values of MB measured in new instruments and after cyclic torsional loading showed no significant differences between them (P > 0.05). The flexibility of rotary ProTaper Universal, K3 and EndoSequence NiTi instruments, measured in bending tests, was not adversely affected by simulated clinical use in curved root canals. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Influence of design and clinical factors on the removal force ratio in tapered implant-abutment interfaces.

PubMed

Aguirrebeitia, Josu; Abasolo, Mikel; Müftü, Sinan; Vallejo, Javier

2017-04-01

A previous study investigated the effects of the preload and taper-angle mismatch in tapered implant systems on the removal force characteristics of the self-locking mechanism. The present study builds upon the previous one and introduces the effects of the time elapsed between insertion and removal and the presence of saliva in the implant-abutment interface as 2 new additional parameters. The purpose of this in vitro study was to elucidate the influences of design and clinical parameters on the removal force for implant systems that use tapered interference fit (TIF) type connections by measuring the force needed to remove an abutment from an implant. Ninety-six implants with tapered abutment-implant interfaces specifically built for an unreplicated factorial design were tested on a custom-built workbench for removal force. Four levels were chosen for the preload, F P , and the taper mismatch Δθ; 3 levels for the wait time t; and 2 levels for the saliva presence s at the interface. A regression model was used based on physical reasoning and a theoretical understanding of the interface. A 4-way ANOVA was used to evaluate the influence of the main effects and interactions (α=.05). The experiments strongly indicated that preload, taper mismatch, and saliva presence are relevant variables in removal force. The wait time becomes important when its effect is evaluated along with the preload. The results of this study can be used for decision making in the design and use of TIF type systems. The study supports the use of artificial saliva in any implant design experiment because of its significance in the removal force of the abutment. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Stability and Control Characteristics of a Complete Airplane Model Having a Wing with Quarter-chord Line Swept Back 40 Degrees, Aspect Ratio 2.50, and Taper Ratio 0.42

NASA Technical Reports Server (NTRS)

Schulderfrei, Marvin; Comisarow, Paul; Goodson, Kenneth W

1951-01-01

An investigation has been made of a complete airplane model having a wing with the quarter-chord line swept back 40 degrees, aspect ratio 2.50, and taper ratio 0.42 to determine its low-speed stability and control characteristics. The longitudinal stability investigation included stabilizer and tail-off tests with different wing dihedral angles (Gamma = 0 degrees and Gamma = -10 degrees) over an angle-of-attack range for the cruising and landing configurations and tests. with a high horizontal-tail location (Gamma = -10 degrees) for the cruising configuration. Tests were made of the wing alone and to determine the effect of wing end plates in pitch. Lateral stability characteristics were determined for the airplane with different geometric wing dihedrals, with end plates, and with several dorsal modifications. Tests were made with ailerons and spoilers to determine control characteristics.

Cyclic fatigue behavior of nickel-titanium dental rotary files in clinical simulated root canals.

PubMed

Chi, Chih-Wen; Li, Chun-Chieh; Lin, Chun-Pin; Shin, Chow-Shing

2017-04-01

Dental rotary instruments can be applied in multiple conditions of canals, but unpredictable fatigue fracture may happen. This study evaluated the fatigue lives of two batches of nickel-titanium (NiTi) dental rotary files operating in clinically simulated root canals. Single-step cyclic fatigue tests were carried out to assess the performance of two batches of NiTi files (ProTaper and ProFile) in nine combinations of simulated canals (cylinder radii 5 mm, 7.5 mm, and 10 mm, and insertion angles 20°, 40°, and 60°). Two-step cyclic fatigue tests were carried out in simulated root canals with the same radius by using the following two sets of insertion angles: (20°, 40°), (20°, 60°), (40°, 20°), and (60°, 20°). Fracture surfaces were observed by scanning electron microscopy. The single-step cyclic fatigue results showed that cyclic fatigue lives of the files decreased with increasing insertion angles or decreasing cylinder radius. The ProFile #25 .04 file was more fatigue resistant than the ProTaper F2 file. In two-step cyclic fatigue tests, the total fatigue lives were usually more than 100% when the files operated at a lower strain and then at a higher strain. By scanning electron microscopy, a larger area of fatigue striation corresponded to a longer fatigue life. Cyclic fatigue life can be influenced by the strains and geometries of files. The fatigue life was prolonged when the files operated at a lower strain and then at a higher strain. However, the fatigue life was shortened if the loading sequence was reversed. Copyright © 2016. Published by Elsevier B.V.

Experimental and computational investigation of Morse taper conometric system reliability for the definition of fixed connections between dental implants and prostheses.

PubMed

Bressan, Eriberto; Lops, Diego; Tomasi, Cristiano; Ricci, Sara; Stocchero, Michele; Carniel, Emanuele Luigi

2014-07-01

Nowadays, dental implantology is a reliable technique for treatment of partially and completely edentulous patients. The achievement of stable dentition is ensured by implant-supported fixed dental prostheses. Morse taper conometric system may provide fixed retention between implants and dental prostheses. The aim of this study was to investigate retentive performance and mechanical strength of a Morse taper conometric system used as implant-supported fixed dental prostheses retention. Experimental and finite element investigations were performed. Experimental tests were achieved on a specific abutment-coping system, accounting for both cemented and non-cemented situations. The results from the experimental activities were processed to identify the mechanical behavior of the coping-abutment interface. Finally, the achieved information was applied to develop reliable finite element models of different abutment-coping systems. The analyses were developed accounting for different geometrical conformations of the abutment-coping system, such as different taper angle. The results showed that activation process, occurred through a suitable insertion force, could provide retentive performances equal to a cemented system without compromising the mechanical functionality of the system. These findings suggest that Morse taper conometrical system can provide a fixed connection between implants and dental prostheses if proper insertion force is applied. Activation process does not compromise the mechanical functionality of the system. © IMechE 2014.

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

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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.

Theoretical investigation for excitation light and fluorescence signal of fiber optical sensor using tapered fiber tip.

PubMed

Yuan, Yinquan; Ding, Liyun

2011-10-24

For fiber optical sensor made of tapered fiber tip, the effects of the geometrical parameters of tapered tip on two important factors have been investigated. One factor is the intensity of the evanescent wave into fluorescent layer through core-medium interface; the other is the intensity of fluorescence signal transmitted from fluorescent layer to measurement end. A dependence relation of the intensity of fluorescence signal transmitted from fluorescent layer to measurement end upon the geometrical parameters of tapered tip has been obtained. Theoretical results show that the intensity of the evanescent wave into fluorescent layer rises with the decrease of the end diameter of tapered tip, and the increase of the tip length; and the transmitted power of fluorescence signal increases linearly with the increase of the tip length due to the contribution of the side area of tapered tip. © 2011 Optical Society of America

The Aerodynamic Performance of the 24 Inch Houck Configuration

DTIC Science & Technology

2007-03-01

a reference center of gravity for the aircraft must be picked . For the data reduction in this study, the center of gravity was placed at the...30 mph (Re ≈ 125K) for three different angles of attack of interest. An angle of attack of -2º was picked because lift was approximately zero at...likely be reduced with a more tapered trailing edge. The normalized turbulent kinetic energy reaches a peak value of approximately 0.012. The u

Multimode Brillouin spectrum in a long tapered birefringent photonic crystal fiber.

PubMed

Tchahame, Joël Cabrel; Beugnot, Jean-Charles; Kudlinski, Alexandre; Sylvestre, Thibaut

2015-09-15

We investigate the stimulated Brillouin scattering (SBS) in a long tapered birefringent solid-core photonic crystal fiber (PCF) and compare our results with a similar but untapered PCF. It is shown that the taper generates a broadband and multipeaked Brillouin spectrum, while significantly increasing the threshold power. Furthermore, we observe that the strong fiber birefringence gives rise to a frequency shift of the Brillouin spectrum which increases along the fiber. Numerical simulations are also presented to account for the taper effect and the birefringence. Our findings open a new means to control or inhibit the SBS by tapering photonic crystal fibers.

Welding-fume-induced transmission loss in tapered optical fibers

NASA Astrophysics Data System (ADS)

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.

Measuring bacterial growth by refractive index tapered fiber optic biosensor.

PubMed

Zibaii, Mohammad Ismail; Kazemi, Alireza; Latifi, Hamid; Azar, Mahmoud Karimi; Hosseini, Seyed Masoud; Ghezelaiagh, Mohammad Hossein

2010-12-02

A single-mode tapered fiber optic biosensor was utilized for real-time monitoring of the Escherichia coli (E. coli K-12) growth in an aqueous medium. The applied fiber tapers were fabricated using heat-pulling method with waist diameter and length of 6-7μm and 3mm, respectively. The bacteria were immobilized on the tapered surface using Poly-l-Lysine. By providing the proper condition, bacterial population growth on the tapered surface increases the average surface density of the cells and consequently the refractive index (RI) of the tapered region would increase. The adsorption of the cells on the tapered fiber leads to changes in the optical characteristics of the taper. This affects the evanescent field leading to changes in optical throughput. The bacterial growth rate was monitored at room temperature by transmission of a 1558.17nm distributed feedback (DFB) laser through the tapered fiber. At the same condition, after determining the growth rate of E. coli by means of colony counting method, we compared the results with that obtained from the fiber sensor measurements. This novel sensing method, promises new application such as rapid analysis of the presence of bacteria. Copyright © 2010 Elsevier B.V. All rights reserved.

Distributed Bragg reflector tapered diode lasers emitting more than 10 W at 1154 nm

NASA Astrophysics Data System (ADS)

Feise, D.; Bugge, F.; Matalla, M.; Thies, A.; Ressel, P.; Blume, G.; Hofmann, J.; Paschke, K.

2018-02-01

Distributed Bragg reflector tapered diode lasers (DBR-TPL) emitting at 1154 nm are ideal light sources to be implemented into medical devices and hand-held tools for treatment in dermatology and ophthalmology at 577 nm due to their high spectral radiance enabling second harmonic generation from near infrared to yellow. In this work, we present DBR-TPLs which are able to emit more than 10 W in continuous-wave operation with a narrow spectral emission at 1154 nm and a very good beam quality providing excellent spectral radiance. The investigated DBRTPLs are based on three different epitaxial structures with varying vertical far field angles of 35°, 26°, and 17°. To optimize the coupling efficiency into non-linear crystals we studied DBR-TPL with a vertical far field angle of approx. 17° based on an asymmetrical super large optical cavity epitaxial structure. At a pump current of 18 A these devices are able to emit more than 9 W at 25°C and nearly 11 W at 10°C. The spectral emission is very narrow (ΔλFWHM = 18 pm) and single mode over the entire current range. While the beam quality factor M2 according to the 1/e2-level remains 1.1, the M2 according to second order moments deteriorates when the laser is pumped with higher currents. Therefore, the power content in the central lobe increases somewhat less rapidly than the total power.

Self-folding mechanics of graphene tearing and peeling from a substrate

NASA Astrophysics Data System (ADS)

He, Ze-Zhou; Zhu, Yin-Bo; Wu, Heng-An

2018-06-01

Understanding the underlying mechanism in the tearing and peeling processes of graphene is crucial for the further hierarchical design of origami-like folding and kirigami-like cutting of graphene. However, the complex effects among bending moduli, adhesion, interlayer interaction, and local crystal structure during origami-like folding and kirigami-like cutting remain unclear, resulting in challenges to the practical applications of existing theoretical and experimental findings as well as to potential manipulations of graphene in metamaterials and nanodevices. Toward this end, classical molecular dynamics (MD) simulations are performed with synergetic theoretical analysis to explore the tearing and peeling of self-folded graphene from a substrate driven by external force and by thermal activation. It is found that the elastic energy localized at the small folding ridge plays a significant role in the crack trajectory. Due to the extremely small bending modulus of monolayer graphene, its taper angle when pulled by an external force follows a scaling law distinct from that in case of bilayer graphene. With the increase in the initial width of the folding ridge, the self-folded graphene, motivated by thermal fluctuations, can be self-assembled by spontaneous self-tearing and peeling from a substrate. Simultaneously, the scaling law between the taper angle and adhesive energy is independent of the motivations for thermal activation-induced self-assembly and external force tearing, providing effective insights into the underlying physics for graphene-based origami-like folding and kirigami-like cutting.

Comparison of cyclic fatigue resistance of novel nickel-titanium rotary instruments.

PubMed

Capar, Ismail Davut; Ertas, Huseyin; Arslan, Hakan

2015-04-01

New files (ProTaper Next/HyFlex/OneShape) are made from novel nickel-titanium (NiTi) alloys/treatments. The purpose of this study was to compare the cyclic fatigue resistance of these new instruments with that of Revo-S instruments. Four groups of 20 NiTi endodontic instruments were tested in steel canals with a 3 mm radius and a 60° angle of curvature. The cyclic fatigue of the following NiTi instruments with a tip size 25 and 0.06 taper that were manufactured with different alloys was tested: ProTaper Next X2 (M-Wire), OneShape (conventional NiTi), Revo-S Shaping Universal (conventional NiTi) and HyFlex 25/0.6 (controlled memory NiTi wire). A one-way anova and post-hoc Tukey's test (α = 0.05) revealed that the HyFlex files had the highest fatigue resistance and the Revo-S had the least fatigue resistance among the groups (P < 0.001). © 2014 Australian Society of Endodontology.

Improved Miniaturized Linear Ion Trap Mass Spectrometer Using Lithographically Patterned Plates and Tapered Ejection Slit

NASA Astrophysics Data System (ADS)

Tian, Yuan; Decker, Trevor K.; McClellan, Joshua S.; Bennett, Linsey; Li, Ailin; De la Cruz, Abraham; Andrews, Derek; Lammert, Stephen A.; Hawkins, Aaron R.; Austin, Daniel E.

2018-02-01

We present a new two-plate linear ion trap mass spectrometer that overcomes both performance-based and miniaturization-related issues with prior designs. Borosilicate glass substrates are patterned with aluminum electrodes on one side and wire-bonded to printed circuit boards. Ions are trapped in the space between two such plates. Tapered ejection slits in each glass plate eliminate issues with charge build-up within the ejection slit and with blocking of ions that are ejected at off-nominal angles. The tapered slit allows miniaturization of the trap features (electrode size, slit width) needed for further reduction of trap size while allowing the use of substrates that are still thick enough to provide ruggedness during handling, assembly, and in-field applications. Plate spacing was optimized during operation using a motorized translation stage. A scan rate of 2300 Th/s with a sample mixture of toluene and deuterated toluene (D8) and xylenes (a mixture of o-, m-, p-) showed narrowest peak widths of 0.33 Th (FWHM).

Some Effects of Sweep and Aspect Ratio on the Transonic Flutter Characteristics of a Series of Thin Cantilever Wings Having a Taper Ratio of 0.6

NASA Technical Reports Server (NTRS)

Jones, G. W., Jr.; Unangst, J. R.

1963-01-01

An investigation of the flutter characteristics of a series of thin cantilever wings having taper ratios of 0.6 was conducted in the Langley transonic blowdown tunnel at Mach numbers between 0.76 and 1.42. The angle of sweepback was varied from 0 degrees to 60 degrees on wings of aspect ratio 4, and the aspect ratio was varied from 2.4 to 6.4 on wings with 45 degrees of sweepback. The results are presented as ratios between the experimental flutter speeds and the reference flutter speeds calculated on the basis of incompressible two-dimensional flow. These ratios, designated the flutter-speed ratios, are given as functions of Mach number for the various wings. The flutter-speed ratios were characterized, in most cases, by values near 1.0 at subsonic speeds with large increases in the speed ratios in the range of supersonic speeds investigated. Increasing the sweep effected increases in the flutter-speed ratios between 0 degrees and 30 degrees followed by progressive reductions of the speed ratios to nearly 1.0 as the sweep was increased from 30 degrees to 60 degrees. Reducing the aspect ratio from 6.4 to 2.4 resulted in progressively larger values of the flutter-speed ratios throughout the Mach number range investigated.

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

PubMed

Desai, Shrikar R; Singh, Rika; Karthikeyan, I

2013-09-01

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. 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. 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. 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.

Wide-angle full-vector beam propagation method based on an alternating direction implicit preconditioner

NASA Astrophysics Data System (ADS)

Chui, Siu Lit; Lu, Ya Yan

2004-03-01

Wide-angle full-vector beam propagation methods (BPMs) for three-dimensional wave-guiding structures can be derived on the basis of rational approximants of a square root operator or its exponential (i.e., the one-way propagator). While the less accurate BPM based on the slowly varying envelope approximation can be efficiently solved by the alternating direction implicit (ADI) method, the wide-angle variants involve linear systems that are more difficult to handle. We present an efficient solver for these linear systems that is based on a Krylov subspace method with an ADI preconditioner. The resulting wide-angle full-vector BPM is used to simulate the propagation of wave fields in a Y branch and a taper.

Wide-angle full-vector beam propagation method based on an alternating direction implicit preconditioner.

PubMed

Chui, Siu Lit; Lu, Ya Yan

2004-03-01

Wide-angle full-vector beam propagation methods (BPMs) for three-dimensional wave-guiding structures can be derived on the basis of rational approximants of a square root operator or its exponential (i.e., the one-way propagator). While the less accurate BPM based on the slowly varying envelope approximation can be efficiently solved by the alternating direction implicit (ADI) method, the wide-angle variants involve linear systems that are more difficult to handle. We present an efficient solver for these linear systems that is based on a Krylov subspace method with an ADI preconditioner. The resulting wide-angle full-vector BPM is used to simulate the propagation of wave fields in a Y branch and a taper.

Wind tunnel research comparing lateral control devices, particularly at high angles of attack XI : various floating tip ailerons on both rectangular and tapered wings

NASA Technical Reports Server (NTRS)

Weick, Fred E; Harris, Thomas A

1933-01-01

Discussed here are a series of systematic tests being conducted to compare different lateral control devices with particular reference to their effectiveness at high angles of attack. The present tests were made with six different forms of floating tip ailerons of symmetrical section. The tests showed the effect of the various ailerons on the general performance characteristics of the wing, and on the lateral controllability and stability characteristics. In addition, the hinge moments were measured for the most interesting cases. The results are compared with those for a rectangular wing with ordinary ailerons and also with those for a rectangular wing having full-chord floating tip ailerons. Practically all the floating tip ailerons gave satisfactory rolling moments at all angles of attack and at the same time gave no adverse yawing moments of appreciable magnitude. The general performance characteristics with the floating tip ailerons, however, were relatively poor, especially the rate of climb. None of the floating tip ailerons entirely eliminated the auto rotational moments at angles of attack above the stall, but all of them gave lower moments than a plain wing. Some of the floating ailerons fluttered if given sufficiently large deflection, but this could have been eliminated by moving the hinge axis of the ailerons forward. Considering all points including hinge moments, the floating tip ailerons on the wing with 5:1 taper are probably the best of those which were tested.

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

PubMed Central

Türker, Sevinç-Aktemur

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 with 10 canals each. Glide paths were created in group 1 with #10, #15 and #20 K-type (Dentsply Maillefer, Ballaigues, Switzerland) stainless steel manual files; in group 2 with Path-File (Dentsply Maillefer) #1, #2, and #3 and in group 3 with #16 ProGlider (Dentsply Maillefer) rotary instruments; in group 4 no glide paths were created. All canals were instrumented up to ProTaper Next X2 to the working length. A double digital radiograph technique was used, pre and post-instrumentation, to assess whether apical transportation and/or aberration in root canal morphology occurred. Instrument failures were also recorded. The data were analyzed statistically using ANOVA and Tukey tests (p<0.05). Results No significant differences were found among groups regarding apical transportation (p>0.05). Two ProTaper Next instruments failed in-group 4. Conclusions Within the parameters of this study, there was no difference between the performance of path-finding files and ProTaper Next system maintained root canal curvature well and was safe to use either with path-finding files or alone. Key words:Glide path, PathFile, ProGlider, ProTaper Next, transportation. PMID:26330936

Selecting superior yellow birch trees; a preliminary guide.

Treesearch

Knud E. Clausen; Richard M. Godman

1967-01-01

Describes procedures to follow and characteristics to consider in selecting superior yellow birch trees. The first selection should be on the basis of tree quality. Characteristics to consider are as follows: for the stem--straightness, roundness, taper grain, self-pruning, and absence of defects; for the crown--apical dominance, branch angle, and branch diameter;...

First-and Second-Order Displacement Transfer Functions for Structural Shape Calculations Using Analytically Predicted Surface Strains

NASA Technical Reports Server (NTRS)

Ko, William L.; Fleischer, Van Tran

2012-01-01

New first- and second-order displacement transfer functions have been developed for deformed shape calculations of nonuniform cross-sectional beam structures such as aircraft wings. The displacement transfer functions are expressed explicitly in terms of beam geometrical parameters and surface strains (uniaxial bending strains) obtained at equally spaced strain stations along the surface of the beam structure. By inputting the measured or analytically calculated surface strains into the displacement transfer functions, one could calculate local slopes, deflections, and cross-sectional twist angles of the nonuniform beam structure for mapping the overall structural deformed shapes for visual display. The accuracy of deformed shape calculations by the first- and second-order displacement transfer functions are determined by comparing these values to the analytically predicted values obtained from finite element analyses. This comparison shows that the new displacement transfer functions could quite accurately calculate the deformed shapes of tapered cantilever tubular beams with different tapered angles. The accuracy of the present displacement transfer functions also are compared to those of the previously developed displacement transfer functions.

Performance study of winglets on tapered wing with curved trailing edge

NASA Astrophysics Data System (ADS)

Ara, Ismat; Ali, Mohammad; Islam, Md. Quamrul; Haque, M. Nazmul

2017-06-01

Induced drag is the result of wingtip vortex produced from generating lift by finite wing. It is one of the main drags that an aircraft wing encounters during flight. It hampers aircraft performance by increasing fuel consumption and reducing endurance, range and speed. Winglets are used to reduce the induced drag. They weakens wingtip vortex and thus reduces induced drag. This paper represents the experimental investigation to reduce induced drag using winglet at the wingtip. A model of tapered wing with curved trailing edge (without winglet) as well as two similar wings with blended winglet and double blended winglet are prepared using NACA 4412 aerofoil in equal span and surface area. All the models are tested in a closed circuit subsonic wind tunnel at air speed of 108 km/h (0.09 Mach). Reynolds number of the flow is 2.28 × 105 on the basis of average chord length of the wings. The point surface static pressures at different angles of attack from -4° to 24° are measured for each of the wing and winglet combinations through different pressure tapings by using a multi-tube water manometer. From the static pressure distribution, lift coefficient, drag coefficient and lift to drag ratio of all models are calculated. From the analysis of calculated values, it is found that both winglets are able to minimize induced drag; however, the tapered curved trailing edge span with blended winglet provides better aerodynamic performance.

Further Development of Ko Displacement Theory for Deformed Shape Predictions of Nonuniform Aerospace Structures

NASA Technical Reports Server (NTRS)

Ko, William L.; Fleischer, Van Tran

2009-01-01

The Ko displacement theory previously formulated for deformed shape predictions of nonuniform beam structures is further developed mathematically. The further-developed displacement equations are expressed explicitly in terms of geometrical parameters of the beam and bending strains at equally spaced strain-sensing stations along the multiplexed fiber-optic sensor line installed on the bottom surface of the beam. The bending strain data can then be input into the displacement equations for calculations of local slopes, deflections, and cross-sectional twist angles for generating the overall deformed shapes of the nonuniform beam. The further-developed displacement theory can also be applied to the deformed shape predictions of nonuniform two-point supported beams, nonuniform panels, nonuniform aircraft wings and fuselages, and so forth. The high degree of accuracy of the further-developed displacement theory for nonuniform beams is validated by finite-element analysis of various nonuniform beam structures. Such structures include tapered tubular beams, depth-tapered unswept and swept wing boxes, width-tapered wing boxes, and double-tapered wing boxes, all under combined bending and torsional loads. The Ko displacement theory, combined with the fiber-optic strain-sensing system, provide a powerful tool for in-flight deformed shape monitoring of unmanned aerospace vehicles by ground-based pilots to maintain safe flights.

Assessment of Retention and Resistance Form of Tooth Preparations for All Ceramic Restorations using Digital Imaging Technique.

PubMed

Muruppel, Alex M; Thomas, Joyce; Saratchandran, Sudeep; Nair, Dinesh; Gladstone, Sheeba; Rajeev, Milen M

2018-02-01

This in vitro study evaluated the resistance form of die preparations for all ceramic restorations and, thereby, explored the concept of effective taper and its correlation between the ideal in theory and actual in the clinical situation by analyzing the digital images of the die preparations. Scanned digital images of 114 die preparations for all ceramic restorations (n = 114) were collected from a dental laboratory. All the images were also analyzed digitally using Adobe Photoshop® software to analyze the degree of taper (angle of convergence) of each preparation and then applied the Zuckerman's circle, and the Lewis perpendicular methods were used to measure the resistance form. For the current study, the overall average degree of taper was found to be 20.9° (range, 2-80°), which is more than what is recommended by most previous studies and also sharply greater than the textbook ideal of 3 to 6°. Mean degree of taper for maxillary was 17.56° (anterior-10.50°, posterior-23.7°), and for mandibular teeth, it was 25.22° (anterior-15°, posterior- 28.45°). Out of the 64 analyzed images of maxillary teeth, 61 presented resistance form, while 3 were without it. Out of the 50 mandibular teeth analyzed, 38 possessed resistance form, whereas 12 were without. All the anterior teeth showed resistance form irrespective of the arch. The degree of taper showed a significant relationship with resistance and retention form, which was inversely proportional to each other. The recommended "degree of taper" is not always the clinically achievable as advocated in textbooks, as it is modified by various factors in the actual clinical situation. The study provides scientific background regarding the relationship between the degree of taper with resistance and retention form, and the relationship was found to be inversely proportional to each other. The recommended "degree of taper" is not always the clinically achievable as advocated in textbooks, and it is modified by various modifying or limiting factors in the actual clinical situation.

Fiber optic biosensor fabricated for measuring the growth rate of Escherichia coli K-12 in the aqueous

NASA Astrophysics Data System (ADS)

Zibaii, M. I.; Kazemi, A.; Latifi, H.; Karimi Azar, M.; Hosseini, S. M.; Ghezelaiagh, M. H.

2010-09-01

A single-mode tapered fiber optic biosensor was utilized for real-time monitoring of the Escherichia coli (E. coli K-12) growth in an aqueous medium. The applied fiber tapers were fabricated using heat-pulling method with waist diameter and length of 6-7μm and 3mm, respectively. The bacteria were immobilized on the tapered surface using Poly-L-Lysine. By providing the proper condition, bacterial population growth on the tapered surface increases the average surface density of the cells and consequently the refractive index (RI) of the tapered region would increase. The adsorption of the cells on the tapered fiber leads to changes in the optical characteristics of the taper. This affects the evanescent field leading to changes in optical throughput. The bacterial growth rate was monitored at room temperature by transmission of a 1558.17nm distributed feedback (DFB) laser through the tapered fiber. At the same condition, after determining the growth rate of E. coli by means of colony counting method, we compared the results with that obtained from the fiber sensor measurements. This novel sensing method, promises new application such as rapid analysis of the presence of bacteria.

Tapered GRIN fiber microsensor.

PubMed

Beltrán-Mejía, Felipe; Biazoli, Claudecir R; Cordeiro, Cristiano M B

2014-12-15

The sensitivity of an optical fiber microsensor based on inter-modal interference can be considerably improved by tapering a short extension of the multimode fiber. In the case of Graded Index fibers with a parabolic refractive index profile, a meridional ray exhibits a sinusoidal path. When these fibers are tapered, the period of the propagated beam decrease down-taper and increase up-taper. We take advantage of this modulation -along with the enhanced overlap between the evanescent field and the external medium- to substantially increase the sensitivity of these devices by tuning the sensor's maximum sensitivity wavelength. Moreover, the extension of this device is reduced by one order of magnitude, making it more propitious for reduced space applications. Numerical and experimental results demonstrate the success and feasibility of this approach.

Numerical Calculations of Short-Range Wakefields of Collimators

NASA Astrophysics Data System (ADS)

Ng, C. K.

2001-12-01

The performance of future linear colliders are limited by the effect of short-range collimator wakefields on the beam. The beam quality is sensitive to the positioning of collimators at the end of the linac. The determination of collimator wakefields has been difficult, largely because of the scarcity of measurement data, and of the limitation of applicability of analytical results to realistic structures. In this paper, numerical methods using codes such as MAFIA are used to determine a series of tapered collimators with rectangular apertures that have been built for studies at SLAC (Stanford Linear Accelerator Center). We will study the dependences of the wakefield on the collimator taper angle, the collimator gap as well as the bunch length. Calculations are also compared with measurements.

Dwarf mistletoe does not increase trunk taper in released red firs in California

Treesearch

Robert F. Scharpf

1977-01-01

Dwarf mistletoe had no noticeable effect on trunk taper of young, dominant and codominant red firs 4 to 22 inches (10.2 to 55.9 cm) d.b.h. Also, taper was not influenced by live crown ratio of infected and uninfected trees. Trees less than 7 inches d.b.h. had significantly more taper than larger trees, irrespective of dwarf mistletoe.

Experimental results for characterization of a tapered plastic optical fiber sensor based on SPR

NASA Astrophysics Data System (ADS)

Cennamo, N.; Galatus, R.; Zeni, L.

2015-05-01

The experimental results obtained with two different Plastic Optical Fiber (POF) geometries, tapered and not-tapered, for a sensor based on Surface Plasmon Resonance (SPR) are presented. SPR is used for determining the refractive index variations at the interface between a gold layer and a dielectric medium (aqueous medium). In this work SPR sensors in POF configurations, useful for bio-sensing applications, have been realized for the optimization of the sensitivity and experimentally tested. The results show as the sensitivity increases with the tapered POF configuration, when the refractive index of aqueous medium increases.

49 CFR 393.136 - What are the rules for securing large boulders?

Code of Federal Regulations, 2010 CFR

2010-10-01

...-separated points of contact that prevent its tendency to roll in any direction. (5) If a boulder is tapered...) Only chain may be used as tiedowns to secure large boulders. (2) Tiedowns which are in direct contact... boulder. Whenever practicable, the angle of the chains must not exceed 45 degrees from the horizontal. ...

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

PubMed Central

Desai, Shrikar R.; Singh, Rika; Karthikeyan, I.

2013-01-01

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. PMID:24174759

Vertical Root Fracture initiation in curved roots after root canal preparation: A dentinal micro-crack analysis with LED transillumination

PubMed Central

Martín-Biedma, Benjamín; Varela-Patiño, Purificación; Ruíz-Piñón, Manuel; Castelo-Baz, Pablo

2017-01-01

Background One of the causative factors of root defects is the increased friction produced by rotary instrumentation. A high canal curvature may increase stress, making the tooth more susceptible to dentinal cracks. The purpose of this study was to evaluate dentinal micro-crack formation with the ProTaper NEXT and ProTaper Universal systems using LED transillumination, and to analyze the micro-crack generated at the point of maximum canal curvature. Material and Methods 60 human mandibular premolars with curvatures between 30–49° and radii between 2–4 mm were used. The root canals were instrumented using the Protaper Universal® and Protaper NEXT® systems, with the aid of the Proglider® system. The obtained samples were sectioned transversely before subsequent analysis with LED transillumination at 2 mm and 8 mm from the apex and at the point of maximum canal curvature. Defects were scored: 0 for no defects; and 1 for micro-cracks. Results Root defects were not observed in the control group. The ProTaper NEXT system caused fewer defects (16.7%) than the ProTaper Universal system (40%) (P<0.05). The ProTaper Universal system caused significantly more micro-cracks at the point of maximum canal curvature than the ProTaper NEXT system (P<0.05). Conclusions Rotary instrumentation systems often generate root defects, but the ProTaper NEXT system generated fewer dentinal defects than the ProTaper Universal system. A higher prevalence of defects was found at the point of maximum curvature in the ProTaper Universal group. Key words:Curved root, Micro-crack, point of maximum canal curvature, ProTaper NEXT, ProTaper Universal, Vertical root fracture. PMID:29167712

Ceramic Heads Decrease Metal Release Caused by Head-taper Fretting and Corrosion.

PubMed

Kocagoz, Sevi B; Underwood, Richard J; MacDonald, Daniel W; Gilbert, Jeremy L; Kurtz, Steven M

2016-04-01

Metal release resulting from taper fretting and corrosion is a clinical concern, because wear and corrosion products may stimulate adverse local tissue reactions. Unimodular hip arthroplasties have a conical taper between the femoral head (head bore taper) and the femoral stem (stem cone taper). The use of ceramic heads has been suggested as a way of reducing the generation of wear and corrosion products from the head bore/stem cone taper junction. A previous semiquantitative study found that ceramic heads had less visual evidence of fretting-corrosion damage compared with CoCr heads; but, to our knowledge, no studies have quantified the volumetric material loss from the head bore and stem cone tapers of a matched cohort of ceramic and metal heads. We asked: (1) Do ceramic heads result in less volume of material loss at the head-stem junction compared with CoCr heads; (2) do stem cone tapers have less volumetric material loss compared with CoCr head bore tapers; (3) do visual fretting-corrosion scores correlate with volumetric material loss; and (4) are device, patient, or intraoperative factors associated with volumetric material loss? A quantitative method was developed to estimate volumetric material loss from the head and stem taper in previously matched cohorts of 50 ceramic and 50 CoCr head-stem pairs retrieved during revision surgery for causes not related to adverse reactions to metal particles. The cohorts were matched according to (1) implantation time, (2) stem flexural rigidity, and (3) lateral offset. Fretting corrosion was assessed visually using a previously published four-point, semiquantitative scoring system. The volumetric loss was measured using a precision roundness machine. Using 24 equally spaced axial traces, the volumetric loss was estimated using a linear least squares fit to interpolate the as-manufactured surfaces. The results of this analysis were considered in the context of device (taper angle clearance, head size, head offset, lateral offset, stem material, and stem surface finish) and patient factors that were obtained from the patients' operative records (implantation time, age at insertion, activity level, and BMI). The cumulative volumetric material losses estimated for the ceramic cohort had a median of 0.0 mm(3) per year (range, 0.0-0.4 mm(3)). The cumulative volumetric material losses estimated for the CoCr cohort had a median of 0.1 mm(3) per year (range, 0.0-8.8 mm(3)). An order of magnitude reduction in volumetric material loss was found when a ceramic head was used instead of a CoCr head (p < 0.0001). In the CoCr cohort, the femoral head bore tapers had a median material loss of 0.02 mm(3) (range, 0.0-8.7 mm(3)) and the stem cone tapers had a median material loss of 0.0 mm(3) (range, 0.0-0.32 mm(3)/year). There was greater material loss from femoral head bore tapers compared with stem cone tapers in the CoCr cohort (p < 0.001). There was a positive correlation between visual scoring and volumetric material loss (Spearman's ρ = 0.67, p < 0.01). Although visual scoring was effective for preliminary screening to separate tapers with no or mild damage from tapers with moderate to severe damage, it was not capable of discriminating in the large range of material loss observed at the taper surfaces with moderate to severe fretting-corrosion damage, indicated with a score of 3 or 4. We observed no correlations between volumetric material loss and device and patient factors. The majority of estimated material loss from the head bore-stem cone junctions resulting from taper fretting and corrosion was from the CoCr head bore tapers as opposed to the stem cone tapers. Additionally, the total material loss from the ceramic cohort showed a reduction in the amount of metal released by an order of magnitude compared with the CoCr cohort. We found that ceramic femoral heads may be an effective means by which to reduce metal release caused by taper fretting and corrosion at the head bore-stem cone modular interface in THAs.

Applications of Ko Displacement Theory to the Deformed Shape Predictions of the Doubly-Tapered Ikhana Wing

NASA Technical Reports Server (NTRS)

Ko, William L.; Richards, W. Lance; Fleischer, Van Tran

2009-01-01

The Ko displacement theory, formulated for weak nonuniform (slowly changing cross sections) cantilever beams, was applied to the deformed shape analysis of the doubly-tapered wings of the Ikhana unmanned aircraft. The two-line strain-sensing system (along the wingspan) was used for sensing the bending strains needed for the wing-deformed shapes (deflections and cross-sectional twist) analysis. The deflection equation for each strain-sensing line was expressed in terms of the bending strains evaluated at multiple numbers of strain-sensing stations equally spaced along the strain-sensing line. For the preflight shape analysis of the Ikhana wing, the strain data needed for input to the displacement equations for the shape analysis were obtained from the nodal-stress output of the finite-element analysis. The wing deflections and cross-sectional twist angles calculated from the displacement equations were then compared with those computed from the finite-element computer program. The Ko displacement theory formulated for weak nonlinear cantilever beams was found to be highly accurate in the deformed shape predictions of the doubly-tapered Ikhana wing.

Cementless Tapered Wedge Femoral Stems Decrease Subsidence in Obese Patients Compared to Traditional Fit-and-Fill Stems.

PubMed

Grant, Tanner W; Lovro, Luke R; Licini, David J; Warth, Lucian C; Ziemba-Davis, Mary; Meneghini, Robert M

2017-03-01

Femoral component stability and resistance to subsidence is critical for osseointegration and clinical success in cementless total hip arthroplasty. The purpose of this study was to radiographically evaluate the anatomic fit and subsidence of 2 different proximally tapered, porous-coated modern cementless femoral component designs. A retrospective cohort study of 126 consecutive cementless total hip arthroplasties was performed. Traditional fit-and-fill stems were implanted in the first 61 hips with the remaining 65 receiving morphometric tapered wedge stems. Preoperative bone morphology was radiographically assessed by the canal flare index. Canal fill in the coronal plane, subsidence, and the sagittal alignment of stems was measured digitally on immediate and 1-month postoperative radiographs. Demographics and canal flare indices were similar between groups. The percentage of femoral canal fill was greater in the tapered wedge compared to the fit-and-fill stem (P = .001). There was significantly less subsidence in the tapered wedge design (0.3 mm) compared to the fit-and-fill design (1.1 mm) (P = .001). Subsidence significantly increased as body mass index (BMI) increased in the fit-and-fill stems, a finding not observed in the tapered wedge design (P = .013). An anatomically designed morphometric tapered wedge femoral stem demonstrated greater axial stability and decreased subsidence with increasing BMI than a traditional fit-and-fill stem. The resistance to subsidence, irrespective of BMI, is likely due to the inherent axial stability of a tapered wedge design and may be the optimal stem design for obese patients. Copyright © 2016 Elsevier Inc. All rights reserved.

Improving the Fabrication of Semiconductor Bragg Lasers

NASA Astrophysics Data System (ADS)

Chen, Eric Ping Chun

Fabrication process developments for Bragg reflection lasers have been optimized in this thesis using resources available to the group. New e-beam lithography and oxide etch recipes have been developed to minimize sidewall roughness and residues. E-beam evaporated metal contacts for semiconductor diode laser utilizing oblique angle deposition have also been developed in-house for the first time. Furthermore, improvement in micro-loading effect of DFB laser etching has been demonstrated where the ratio of tapered portion of the sidewall to total etch depth is reduced by half, from 33% to 15%. Electrical, optical and thermal performance of the fabricated lasers are characterized. Comparing the results to previous generation lasers, average dynamic resistance is decreased drastically from 14 Ohms to 7 Ohms and threshold current density also reduced from 1705A/cm2 to 1383A/ cm2. Improvement in laser performance is result of reduced loss from optimized fabrication processes. BRL bow-tie tapered lasers is then fabricated for the first time and output power of 18mW at 200mA input is measured. Benefiting from the increased effective area and better carrier utilization, reduction in threshold current density from 1383A/cm 2 to 712A/cm2 is observed.

Thermal actuator improvements: tapering and folding

NASA Astrophysics Data System (ADS)

Sinclair, Michael J.; Wang, Kerwin

2003-04-01

Electrothermal actuation is not a popular technology for today"s MEMS transducers due to its relatively slow response and large appetite for power. The large displacement with high force and low voltage gives reason to try to improve thermal actuator"s operating characteristics. This paper describes some improvements to thermal actuators, mainly in increased output energy per actuator chip area and area utilization. The devices presented here are a variation of the chevron thermal actuator - one with two sets of thermally expanding beams pushing at a slight angle on either side of a suspended shuttle, causing it to be displaced parallel to the substrate. One improvement is to taper the thermal expansion beams so they exhibit a higher strain energy, allowing a larger thermal input power and hence more output mechanical power per beam. Another improvement is to move (fold) both sets of thermal beams to the same side of the shuttle so all are exerting force on the same side. The thermal expansion beams cause compression against the shuttle and work against one or two orthogonal cold beams in tension to produce an output force and displacement. This resembles a pseudo-bimorph array with the exception of having far fewer non-force-producing beams to bend.

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

PubMed Central

MARTINS, Renata de Castro; BAHIA, Maria Guiomar de Azevedo; BUONO, Vicente Tadeu Lopes

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 instruments until the apical end following four distinct sequences of instrumentation: S1; S1 and S2; S1, S2, and F1; S1, S2, F1, and F2. Image analysis was employed for measuring canal diameters. The diameters of the canals and diameters of the instruments were compared. Data were analyzed by one-way ANOVA and Tukey’s test. Results No statistically significant difference was found between the canals and instrument diameters (p>0.05). The largest diameters in the end-point of the instrumented canals were obtained with F1 and F2 instruments and in the initial and middle thirds with S1 and S2 instruments. Conclusions All instruments worked at the tip and along their cutting blades, being susceptible to fail by torsion, fatigue, or the combination of these two mechanisms. PMID:20379681

Nonlinear Analysis of Bonded Composite Single-LAP Joints

NASA Technical Reports Server (NTRS)

Oterkus, E.; Barut, A.; Madenci, E.; Smeltzer, S. S.; Ambur, D. R.

2004-01-01

This study presents a semi-analytical solution method to analyze the geometrically nonlinear response of bonded composite single-lap joints with tapered adherend edges under uniaxial tension. The solution method provides the transverse shear and normal stresses in the adhesive and in-plane stress resultants and bending moments in the adherends. The method utilizes the principle of virtual work in conjunction with von Karman s nonlinear plate theory to model the adherends and the shear lag model to represent the kinematics of the thin adhesive layer between the adherends. Furthermore, the method accounts for the bilinear elastic material behavior of the adhesive while maintaining a linear stress-strain relationship in the adherends. In order to account for the stiffness changes due to thickness variation of the adherends along the tapered edges, their in-plane and bending stiffness matrices are varied as a function of thickness along the tapered region. The combination of these complexities results in a system of nonlinear governing equilibrium equations. This approach represents a computationally efficient alternative to finite element method. Comparisons are made with corresponding results obtained from finite-element analysis. The results confirm the validity of the solution method. The numerical results present the effects of taper angle, adherend overlap length, and the bilinear adhesive material on the stress fields in the adherends, as well as the adhesive, of a single-lap joint

Connecting Molecular Dynamics Simulations and Fluids Density Functional Theory of Block Copolymers

NASA Astrophysics Data System (ADS)

Hall, Lisa

Increased understanding and precise control over the nanoscale structure and dynamics of microphase separated block copolymers would advance development of mechanically robust but conductive materials for battery electrolytes, among other applications. Both coarse-grained molecular dynamics (MD) simulations and fluids (classical) density functional theory (fDFT) can capture the microphase separation of block copolymers, using similar monomer-based chain models and including local packing effects. Equilibrium free energies of various microphases are readily accessible from fDFT, which allows us to efficiently determine the equilibrium nanostructure over a large parameter space. Meanwhile, MD allows us to visualize specific polymer conformations in 3D over time and to calculate dynamic properties. The fDFT density profiles are used to initialize the MD simulations; this ensures the MD proceeds in the appropriate microphase separated state rather than in a metastable structure (useful especially for nonlamellar structures). The simulations equilibrate more quickly than simulations initialized with a random state, which is significant especially for long chains. We apply these methods to study the interfacial behavior and microphase separated structure of diblock and tapered block copolymers. Tapered copolymers consist of pure A and B monomer blocks on the ends separated by a tapered region that smoothly varies from A to B (or from B to A for an inverse taper). Intuitively, tapering increases the segregation strength required for the material to microphase separate and increases the width of the interfacial region. Increasing normal taper length yields a lower domain spacing and increased polymer mobility, while larger inverse tapers correspond to even lower domain spacing but decreased mobility. Thus the changes in dynamics with tapering cannot be explained by mapping to a diblock system at an adjusted effective segregation strength. This material is based upon work supported by the National Science Foundation under Grant 1454343 and the Department of Energy under Grant DE-SC0014209.

A method for estimating the rolling moment due to spin rate for arbitrary planform wings

NASA Technical Reports Server (NTRS)

Poppen, W. A., Jr.

1985-01-01

The application of aerodynamic theory for estimating the force and moments acting upon spinning airplanes is of interest. For example, strip theory has been used to generate estimates of the aerodynamic characteristics as a function of spin rate for wing-dominated configurations for angles of attack up to 90 degrees. This work, which had been limited to constant chord wings, is extended here to wings comprised of tapered segments. Comparison of the analytical predictions with rotary balance wind tunnel results shows that large discrepancies remain, particularly for those angles-of-attack greater than 40 degrees.

Theoretical antisymmetric span loading for wings of arbitrary plan form at subsonic speeds

NASA Technical Reports Server (NTRS)

Deyoung, John

1951-01-01

A simplified lifting-surface theory that includes effects of compressibility and spanwise variation of section lift-curve slope is used to provide charts with which antisymmetric loading due to arbitrary antisymmetric angle of attack can be found for wings having symmetric plan forms with a constant spanwise sweep angle of the quarter-chord line. Consideration is given to the flexible wing in roll. Aerodynamic characteristics due to rolling, deflected ailerons, and sideslip of wings with dihedral are considered. Solutions are presented for straight-tapered wings for a range of swept plan forms.

The point-spread function of fiber-coupled area detectors

PubMed Central

Holton, James M.; Nielsen, Chris; Frankel, Kenneth A.

2012-01-01

The point-spread function (PSF) of a fiber-optic taper-coupled CCD area detector was measured over five decades of intensity using a 20 µm X-ray beam and ∼2000-fold averaging. The ‘tails’ of the PSF clearly revealed that it is neither Gaussian nor Lorentzian, but instead resembles the solid angle subtended by a pixel at a point source of light held a small distance (∼27 µm) above the pixel plane. This converges to an inverse cube law far from the beam impact point. Further analysis revealed that the tails are dominated by the fiber-optic taper, with negligible contribution from the phosphor, suggesting that the PSF of all fiber-coupled CCD-type detectors is best described as a Moffat function. PMID:23093762

Minimum work analysis on the critical taper accretionary wedges- insights from analogue modeling

NASA Astrophysics Data System (ADS)

Santimano, Tasca; Rosenau, Matthias; Oncken, Onno

2014-05-01

The Critical taper theory (CTT) is a fundamental concept for the understanding of mountain building processes. Based on force balance it predicts the preferred steady state geometry of an accretionary wedge system and its tectonic regime (extensive, compressive, stable). However, it does not specify which structures are formed and reactivated to reach the preferred state. The latter can be predicted by the minimum work concept. Here we test both concepts and their interplay by analysing two simple sand wedge models which differ only in the thickness of the basal detachment (a layer of glass beads). While the steady state critical taper is controlled by internal and basal friction coefficients and therefore the same in all experiments, different processes can minimise work by 1. reducing gravitational work e.g. by lowering the amount of uplift or volume uplifted, or 2. reducing frictional work e.g. by lowering the load or due to low friction coefficient along thrusts. Since a thick detachment allows entrainment of low friction material and therefore lowering of the friction along active thrusts, we speculate that the style of wedge growth will differ between the two models. We observe that the wedge with a thin basal detachment localizes strain at the toe of the wedge periodically and reactivate older faults to reach the critical topography. On the contrary, in the wedge with the thicker detachment layer, friction along thrusts is lowered due to the entrainment of low friction material from the detachment zone, subsequently increasing the lifetime of a thrust. Long thrust episodes are always followed by a fault of shorter lifetime, with the aim of reaching the critical taper. From the two experiments, we analyze the time-series evolution of the wedge to infer the work done by the two styles of deformation and predict the trend over time to differ but the maximum work to be similar Our observations show that the critical taper theory determines the geometry of the wedge in particular the taper angle. However the path and style of deformation that the wedge adopts i.e. strain partitioning or deformation along one fault, is determined by the energetically lowest pathway. The observation is especially evident in wedges with added complexities or random changes as the wedge matures. This study combines two theories to explain variability in the results of analogue models and perhaps may aid in understanding the complexity in natural wedges. It also delineates that two different mechanics of deformation can lead to the same geometrical wedge or final topography.

Retention Load of Telescopic Crowns with Different Taper Angles between Cobalt-Chromium and Polyetheretherketone Made with Three Different Manufacturing Processes Examined by Pull-Off Test.

PubMed

Wagner, Christina; Stock, Veronika; Merk, Susanne; Schmidlin, Patrick R; Roos, Malgorzata; Eichberger, Marlis; Stawarczyk, Bogna

2018-02-01

To investigate the retention loads of differently fabricated secondary telescopic polyetheretherketone (PEEK) crowns on cobalt-chromium primary crowns with different tapers. Cobalt-chromium primary crowns with 0°, 1°, and 2° tapers were constructed, milled, and sintered. Corresponding secondary crowns were fabricated by milling, pressing from pellets, and pressing from granules. For these nine test groups, the pull-off tests of each crown combination were performed 20 times, and the retention loads were measured (Zwick 1445, 50 mm/min). Data were analyzed using linear regression, covariance analysis, mixed models, Kruskal-Wallis, and Mann-Whitney U-test, together with the Benferroni-Holm correction. The mixed models covariance analysis reinforced stable retention load values (p = 0.162) for each single test sequence. There was no interaction between the groups and the separation cycles (p = 0.179). Milled secondary crowns with 0° showed the lowest mean retention load values compared to all tested groups (p = 0.003) followed by those pressed form pellets with 1°. Regarding the different tapers, no effect of manufacturing method on the results was observed within 1° and 2° groups (p = 0.540; p = 0.052); however, among the 0° groups, the milled ones showed significantly the lowest retention load values (p = 0.002). Among the manufacturing methods, both pressed groups showed no impact of taper on the retention load values (p > 0.324 and p > 0.123, respectively), whereas among the milled secondary crowns, the 0° taper showed significantly lower retention load values than the 1° and 2° taper (p < 0.002). Based on these results, telescopic crowns made of PEEK seem to show stable retention load values for each test sequence; however, data with thermo-mechanical aging are still required. In addition, further developments in CAD/CAM manufacturing of PEEK materials for telescopic crowns are warranted, especially for 0°. © 2016 by the American College of Prosthodontists.

Fibre laser cutting of polycaprolactone sheet for stents manufacturing: A feasibility study

NASA Astrophysics Data System (ADS)

Guerra, Antonio J.; Farjas, Jordi; Ciurana, Joaquim

2017-10-01

The role of the stent is temporary and it is limited to the intervention and shortly thereafter. Bioresorbable polymer stents were introduced to overcome this problem, making the stent manufacturing process rather difficult considering the complexity of the material. The stent forecast sale makes constant technology development necessary on this field. The adaptation of the laser manufacturing industry to these new materials is costly, thus further studies employing different sorts of lasers are necessary. This paper aims to explore the feasibility of 1.08 μm wavelength fibre laser to cut polycaprolactone sheet, which is especially interesting for long-term implantable devices, such as stents. The laser cut samples were analysed by Differential Scanning Calorimetry (DSC), Tensile Stress Test, and Optical Microscopy in order to study the effects of the laser process over the workpiece. The parameters measured were: taper angle, dimensional precision, material structure changes and mechanical properties changes. Results showed a dimensional precision above 95.75% with a taper angle lower than 0.033°. The laser ablation process has exhibited a minor influence upon material properties. Results exhibit the feasibility of fibre laser to cut polycaprolactone, making the fibre laser an alternative to manufacture stents.

Cyclic fatigue analysis of twisted file rotary NiTi instruments used in reciprocating motion.

PubMed

Gambarini, G; Gergi, R; Naaman, A; Osta, N; Al Sudani, D

2012-09-01

To evaluate the cyclic fatigue fracture resistance of engine-driven twisted file (TF) instruments under reciprocating movement. A sample of 30 size 25, 0.08 taper NiTi TF instruments was tested in a simulated canal with 60˚ angle of curvature and a 3 mm radius. During mechanical testing, different movement kinematics were used at a constant speed, which resulted in three experimental groups (each group n = 10). The instruments from the first group (G1) were rotated until fracture occurred. The instruments in the second (G2) and third group (G3) were driven under reciprocating movement with different angles of reciprocation. The time of fracture for each instrument was measured, and statistical analysis was performed using one-way analysis of variance followed by Tukey's Honestly Significant Different test. Reciprocating movement resulted in a significantly longer cyclic fatigue life (P < 0.0001) when compared with continuous rotation. No difference was found between reciprocation 150° clockwise/30° counterclockwise (CW/CCW) and 30° CW/150° CCW. The reciprocating movement was associated with an extended cyclic fatigue life of the TF size 0.25, 0.08 taper instruments in comparison with conventional rotation. © 2012 International Endodontic Journal.

Cleaning effectiveness and shaping ability of rotary ProTaper compared with rotary GT and manual K-Flexofile.

PubMed

Liu, Sheng-Bo; Fan, Bin; Cheung, Gary S P; Peng, Bing; Fan, Ming-Wen; Gutmann, James L; Song, Ya-Ling; Fu, Qiang; Bian, Zhuan

2006-12-01

To compare the cleaning efficacy and shaping ability of engine-driven ProTaper and GT files, and manual preparation using K-Flexofile instruments in curved root canals of extracted human teeth. 45 canals of maxillary and mandibular molars with curvatures between 25 degrees and 40 degrees were divided into three groups. The groups were balanced with regard to the angle and the radius of canal curvature. Canals in each group were prepared to an apical size of 25 with either the rotary ProTaper or GT system, or manually with K-Flexofile using the modified double-flared technique. Irrigation was done with 2 mL 2.5% NaOCl after each instrument and, as the final rinse, 10 mL 2.5% NaOCl then 10 mL 17% EDTA and finally 5 mL distilled water. The double-exposure radiographic technique was used to examine for the presence of apical transportation. The time required to complete the preparation, as well as any change in working length after preparation were recorded. The roots were then grooved and split longitudinally. The amounts of debris and smear layer were evaluated at the apical, middle and coronal regions under the scanning electron microscope. Data were analyzed either parametrically with the F-test or non-parametrically using the Kruskal-Wallis test, where appropriate. Two GT files but none of the K-Flexofile and ProTaper instruments separated. For debris removal, the ProTaper group achieved a better result than GT (P < 0.05) but not the K-Flexofile group at all three regions (apical, middle and coronal). K-Flexofiles produced significantly less smear layer than ProTaper and GT files only in the middle third of the canal (P < 0.01). Both NiTi rotary instruments maintained the original canal shape better than the K-Flexofiles (P < 0.05) and required significantly less time to complete the preparation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsutani, Takaomi; Taya, Masaki; Ikuta, Takashi

A parallel image detection system using an annular pupil for electron optics were developed to realize an increase in the depth of focus, aberration-free imaging and separation of amplitude and phase images under scanning transmission electron microscopy (STEM). Apertures for annular pupils able to suppress high-energy electron scattering were developed using a focused ion beam (FIB) technique. The annular apertures were designed with outer diameter of oe 40 {mu}m and inner diameter of oe32 {mu}m. A taper angle varying from 20 deg. to 1 deg. was applied to the slits of the annular apertures to suppress the influence of high-energymore » electron scattering. Each azimuth angle image on scintillator was detected by a multi-anode photomultiplier tube assembly through 40 optical fibers bundled in a ring shape. To focus the image appearing on the scintillator on optical fibers, an optical lens relay system attached with CCD camera was developed. The system enables the taking of 40 images simultaneously from different scattered directions.« less

Supercontinuum generation from 437 to 2850 nm in a tapered fluorotellurite microstructured fiber

NASA Astrophysics Data System (ADS)

Wang, F.; Jia, Z. X.; Yao, C. F.; Wang, S. B.; Hu, M. L.; Wu, C. F.; Ohishi, Y.; Qin, W. P.; Qin, G. S.

2016-12-01

We demonstrated supercontinuum (SC) generation in a tapered fluorotellurite microstructured fiber (MF) with a sub-micrometer core diameter. Fluorotellurite MFs based on TeO2-BaF2-Y2O3 glasses were fabricated by using a rod-in-tube method and a tapered fluorotellurite MF with a minimum core diameter of ~0.65 µm was prepared by employing a tapering system. A 1560 nm femtosecond fiber laser was used as the pumping source. With increasing the peak power of the launched pump laser to ~11 kW, SC light expanding from 437 to 2850 nm was generated in the tapered fluorotellurite MF. In addition, relatively strong blue-shifted dispersive wave at ~489 nm was also observed from the tapered fluorotellurite MF.

Tapering Practices of Croatian Open-Class Powerlifting Champions.

PubMed

Grgic, Jozo; Mikulic, Pavle

2017-09-01

Grgic, J and Mikulic, P. Tapering practices of Croatian open-class powerlifting champions. J Strength Cond Res 31(9): 2371-2378, 2017-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.

Composite drill pipe and method for forming same

DOEpatents

Leslie, James C; Leslie, II, James C; Heard, James; Truong, Liem; Josephson, Marvin

2014-04-15

Metal inner and outer fittings configured, the inner fitting configured proximally with an external flange and projecting distally to form a cylindrical barrel and stepped down-in-diameter to form an abutment shoulder and then projecting further distally to form a radially inwardly angled and distally extending tapered inner sleeve. An outer sleeve defining a torque tube is configured with a cylindrical collar to fit over the barrel and is formed to be stepped up in diameter in alignment with the first abutment shoulder to then project distally forming a radially outwardly tapered and distally extending bonding surface to cooperate with the inner sleeve to cooperate with the inner sleeve in forming a annular diverging bonding cavity to receive the extremity of a composite pipe to abut against the abutment shoulders and to be bonded to the respective bonding surfaces by a bond.

Connector adapter

NASA Technical Reports Server (NTRS)

Dean, Richard J. (Inventor); Hacker, Scott C. (Inventor); Burge, Scott W. (Inventor); Dartez, Toby W. (Inventor)

2007-01-01

An adapter for installing a connector to a terminal post, wherein the connector is attached to a cable, is presented. In an embodiment, the adapter is comprised of an elongated collet member having a longitudinal axis comprised of a first collet member end, a second collet member end, an outer collet member surface, and an inner collet member surface. The inner collet member surface at the first collet member end is used to engage the connector. The outer collet member surface at the first collet member end is tapered for a predetermined first length at a predetermined taper angle. The collet includes a longitudinal slot that extends along the longitudinal axis initiating at the first collet member end for a predetermined second length. The first collet member end is formed of a predetermined number of sections segregated by a predetermined number of channels and the longitudinal slot.

Secondary electron emission from textured surfaces

NASA Astrophysics Data System (ADS)

Huerta, C. E.; Patino, M. I.; Wirz, R. E.

2018-04-01

In this work, a Monte Carlo model is used to investigate electron induced secondary electron emission for varying effects of complex surfaces by using simple geometric constructs. Geometries used in the model include: vertical fibers for velvet-like surfaces, tapered pillars for carpet-like surfaces, and a cage-like configuration of interlaced horizontal and vertical fibers for nano-structured fuzz. The model accurately captures the secondary electron emission yield dependence on incidence angle. The model shows that unlike other structured surfaces previously studied, tungsten fuzz exhibits secondary electron emission yield that is independent of primary electron incidence angle, due to the prevalence of horizontally-oriented fibers in the fuzz geometry. This is confirmed with new data presented herein of the secondary electron emission yield of tungsten fuzz at incidence angles from 0-60°.

Comparison for 1030nm DBR-tapered diode lasers with 10W central lobe output power and different grating layouts for wavelength stabilization and lateral spatial mode filtering

NASA Astrophysics Data System (ADS)

Müller, André; Zink, Christof; Fricke, Jörg; Bugge, Frank; Erbert, Götz; Sumpf, Bernd; Tränkle, Günther

2018-02-01

1030 nm DBR tapered diode lasers with different lateral layouts are presented. The layout comparison includes lasers with straight waveguide and grating, tapered waveguide and straight grating, and straight waveguide and tapered grating. The lasers provide narrowband emission and optical output powers up to 15 W. The highest diffraction-limited central lobe output power of 10.5 W is obtained for lasers with tapered gratings only. Small variations in central lobe output power with RW injection current density also indicate the robustness of that layout. For lasers with tapered waveguides, high RW injection current densities up to 150 A/mm2 have to be applied in order to obtain high central lobe output powers. Lasers with straight waveguide and grating operate best at low RW injection current densities, 50 A/mm2 applied in this study. Using the layout optimizations discussed in this study may help to increase the application potential of DBR tapered diode lasers.

Moment method analysis of linearly tapered slot antennas

NASA Technical Reports Server (NTRS)

Koeksal, Adnan

1993-01-01

A method of moments (MOM) model for the analysis of the Linearly Tapered Slot Antenna (LTSA) is developed and implemented. The model employs an unequal size rectangular sectioning for conducting parts of the antenna. Piecewise sinusoidal basis functions are used for the expansion of conductor current. The effect of the dielectric is incorporated in the model by using equivalent volume polarization current density and solving the equivalent problem in free-space. The feed section of the antenna including the microstripline is handled rigorously in the MOM model by including slotline short circuit and microstripline currents among the unknowns. Comparison with measurements is made to demonstrate the validity of the model for both the air case and the dielectric case. Validity of the model is also verified by extending the model to handle the analysis of the skew-plate antenna and comparing the results to those of a skew-segmentation modeling results of the same structure and to available data in the literature. Variation of the radiation pattern for the air LTSA with length, height, and taper angle is investigated, and the results are tabulated. Numerical results for the effect of the dielectric thickness and permittivity are presented.

Moment method analysis of linearly tapered slot antennas: Low loss components for switched beam radiometers

NASA Technical Reports Server (NTRS)

Koeksal, Adnan; Trew, Robert J.; Kauffman, J. Frank

1992-01-01

A Moment Method Model for the radiation pattern characterization of single Linearly Tapered Slot Antennas (LTSA) in air or on a dielectric substrate is developed. This characterization consists of: (1) finding the radiated far-fields of the antenna; (2) determining the E-Plane and H-Plane beamwidths and sidelobe levels; and (3) determining the D-Plane beamwidth and cross polarization levels, as antenna parameters length, height, taper angle, substrate thickness, and the relative substrate permittivity vary. The LTSA geometry does not lend itself to analytical solution with the given parameter ranges. Therefore, a computer modeling scheme and a code are necessary to analyze the problem. This necessity imposes some further objectives or requirements on the solution method (modeling) and tool (computer code). These may be listed as follows: (1) a good approximation to the real antenna geometry; and (2) feasible computer storage and time requirements. According to these requirements, the work is concentrated on the development of efficient modeling schemes for these type of problems and on reducing the central processing unit (CPU) time required from the computer code. A Method of Moments (MoM) code is developed for the analysis of LTSA's within the parameter ranges given.

Some Effects of Horizontal-Tail Position on the Vertical-Tail Pressure Distributions of a Complete Model in Sideslip at High Subsonic Speeds

NASA Technical Reports Server (NTRS)

Alford, William J., Jr.

1958-01-01

An investigation has been made in the Langley high-speed 7- by 10-foot tunnel of some effects of horizontal-tail position on the vertical-tail pressure distributions of a complete model in sideslip at high subsonic speeds. The wing of the model was swept back 28.82 deg at the quarter-chord line and had an aspect ratio of 3.50, a taper ratio of 0.067, and NACA 65A004 airfoil sections parallel to the model plane of symmetry. Tests were made with the horizontal tail off, on the wing-chord plane extended, and in T-tail arrangements in forward and rearward locations. The test Mach numbers ranged from 0.60 to 0.92, which corresponds to a Reynolds number range from approximately 2.93 x 10(exp 6) to 3.69 x 10(exp 6), based on the wing mean aerodynamic chord. The sideslip angles varied from -3.9 deg to 12.7 deg at several selected angles of attack. The results indicated that, for a given angle of sideslip, increases in angle of attack caused reductions in the vertical-tail loads in the vicinity of the root chord and increases at the midspan and tip locations, with rearward movements in the local chordwise centers of pressure for the midspan locations and forward movements near the tip of the vertical tail. At the higher angles of attack all configurations investigated experienced outboard and rearward shifts in the center of pressure of the total vertical-tail load. Location of the horizontal tail on the wing- chord plane extended produced only small effects on the vertical-tail loads and centers of pressure. Locating the horizontal tail at the tip of the vertical tail in the forward position caused increases in the vertical-tail loads; this configuration, however, experienced considerable reduction in loads with increasing Mach number. Location of the horizontal tail at the tip of the vertical tail in the rearward position produced the largest increases in vertical-tail loads per degree sideslip angle; this configuration experienced the smallest variations of loads with Mach number of any of the configurations investigated.

Horizontally staggered lightguide solar concentrator with lateral displacement tracking for high concentration applications.

PubMed

Ma, Hongcai; Wu, Lin

2015-07-10

We present the design of a horizontally staggered lightguide solar concentrator with lateral displacement tracking for high concentration applications. This solar concentrator consists of an array of telecentric primary concentrators, a horizontally staggered lightguide layer, and a vertically tapered lightguide layer. The primary concentrator is realized by two plano-aspheric lenses with lateral movement and maintains a high F-number over an angle range of ±23.5°. The results of the simulations show that the solar concentrator achieves a high concentration ratio of 500× with ±0.5° of acceptance angle by a single-axis tracker and dual lateral translation stages.

GAUGING APPARATUS

DOEpatents

Ruggles, C.A.

1957-08-27

A swinging arm gage designed to measure radial angles, tapering, sloping, or arcuate concave surfaces is described. The principle of the swinging arm gage is that in any spherical system, radii and radial lines established by them pass through the center of the sphere. Thus if an arm be made to pivot at the sphere center, the path of the swinging end can be guided by a can so set as to establish the proper center angle, and dial indicators on the arm can be zeroed on a master object, angular and dimensional manufacturing errors can be determined on a duplicate object. This device makes possible a considerable saving of time in measuring complex arcuate contours.

Shaping ability of ProFile.04 Taper Series 29 rotary nickel-titanium instruments in simulated root canals. Part 1.

PubMed

Thompson, S A; Dummer, P M

1997-01-01

The aim of this study was to determine the shaping ability of ProFile.04 Taper Series 29 nickel-titanium instruments in simulated canals. A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by ProFile instruments using a step-down approach. Part 1 of this two-part report describes the efficacy of the instruments in terms of preparation time, instrument failure, canal blockages, loss of canal length and three-dimensional canal form. The time necessary for canal preparation was not influenced significantly by canal shape. No instrument fractures occurred but a total of 52 instruments deformed. Size 6 instruments deformed the most followed by sizes 5, 3 and 4. Canal shape did not influence significantly instrument deformation. None of the canals became blocked with debris and loss of working distance was on average 0.5 mm or less. Intracanal impressions of canal form demonstrated that most canals had definite apical stops, smooth canal walls and good flow and taper. Under the conditions of this study, ProFile.04 Taper Series 29 rotary nickel-titanium instruments prepared simulated canals rapidly and created good three-dimensional form. A substantial number of instruments deformed but it was not possible to determine whether this phenomenon occurred because of the nature of the experimental model or through an inherent design weakness in the instruments.

Torsion and bending properties of shape memory and superelastic nickel-titanium rotary instruments.

PubMed

Ninan, Elizabeth; Berzins, David W

2013-01-01

Recently introduced into the market are shape memory nickel-titanium (NiTi) rotary files. The objective of this study was to investigate the torsion and bending properties of shape memory files (CM Wire, HyFlex CM, and Phoenix Flex) and compare them with conventional (ProFile ISO and K3) and M-Wire (GT Series X and ProFile Vortex) NiTi files. Sizes 20, 30, and 40 (n = 12/size/taper) of 0.02 taper CM Wire, Phoenix Flex, K3, and ProFile ISO and 0.04 taper HyFlex CM, ProFile ISO, GT Series X, and Vortex were tested in torsion and bending per ISO 3630-1 guidelines by using a torsiometer. All data were statistically analyzed by analysis of variance and the Tukey-Kramer test (P = .05) to determine any significant differences between the files. Significant interactions were present among factors of size and file. Variability in maximum torque values was noted among the shape memory files brands, sometimes exhibiting the greatest or least torque depending on brand, size, and taper. In general, the shape memory files showed a high angle of rotation before fracture but were not statistically different from some of the other files. However, the shape memory files were more flexible, as evidenced by significantly lower bending moments (P < .008). Shape memory files show greater flexibility compared with several other NiTi rotary file brands. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Perception of the upright and susceptibility to motion sickness as functions of angle of tilt and angular velocity in off-vertical rotation. [human tolerance to angular accelerations

NASA Technical Reports Server (NTRS)

Miller, E. F., II; Graybiel, A.

1973-01-01

Motion sickness susceptibility of four normal subjects was measured in terms of duration of exposure necessary to evoke moderate malaise (MIIA) as a function of velocity in a chair rotated about a central axis tilted 10 deg with respect to gravitational upright. The subjects had little or no susceptibility to this type of rotation at 2.5 and 5.0 rpm, but with further increases in rate, the MIIA endpoint was always reached and with ever shorter test durations. Minimal provocative periods for all subjects were found at 15 or 20 rpm. Higher rotational rates dramatically reversed the vestibular stressor effect, and the subjects as a group tended to reach a plateau of relatively low susceptibility at 40 and 45 rpm. At these higher velocities, furthermore, the subjects essentially lost their sensation of being tilted off vertical. In the second half of the study, the effect of tilt angle was varied while the rotation rate was maintained at a constant 17.5 rpm. Two subjects were completely resistant to symptoms of motion sickness when rotated at 2.5 deg off vertical; with greater off-vertical angles, the susceptibility of all subjects increased sharply at first, then tapered off in a manner reflecting a Fechnerian function.

Microleakage of the prosthetic abutment/implant interface with internal and external connection: in vitro study.

PubMed

Larrucea Verdugo, Carlos; Jaramillo Núñez, Guido; Acevedo Avila, Ariel; Larrucea San Martín, Carlo

2014-09-01

This study determined the degree of marginal microleakage of the abutment-implant interface on platforms with Morse taper connection and external connection. For this in vitro study, 42 implants, 21 with external connection and 21 with Morse taper connection, were used, immersed in acrylic resin cylinders. Each implant was joined by a prosthetic abutment screw tightened at different degrees, forming the six study groups: (1) External connection, manual tightening (2) External connection, 20 Newton (N) tightening (3) External connection, 30 N tightening (4) Morse taper connection, manual tightening (5) Morse taper connection, 20 N tightening (6) orse taper connection, 30 N tightening. All samples were subjected to load cycling and thermocycling. Then, they were submerged in a solution of 0.2% methylene blue for 24 h. Finally, the microleakage was measured via 20× optical microscopy in each study group, average was obtained, and Mann-Whitney test was applied. Statistically significant differences (P < 0.001) were found between the levels of microleakage presented in the Morse taper connection implants (1.48) and external connection implants (2.8) in all three types of tightening. Microleakage levels decreases when increasing torque is applied to the screws. Morse taper connection implants showed lower levels of microleakage than external connection implants; also, it was observed that microleakage decreases in the way torque increases. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Influence of cross-sectional design and dimension on mechanical behavior of nickel-titanium instruments under torsion and bending: a numerical analysis.

PubMed

Zhang, En-Wei; Cheung, Gary S P; Zheng, Yu-Feng

2010-08-01

The aim of this study was to examine the influence of the cross-sectional configuration and dimensions (size and taper) on the torsional and bending behavior of nickel-titanium rotary instruments, taking into account the nonlinear mechanical properties of material. Ten cross-sectional configurations, square, triangular, U-type, S-type (large and small), convex-triangle, and 4 proprietary ones (Mani NRT and RT2, Quantec, and Mtwo), were analyzed under torsion or bending by using a 3-dimensional finite element method. The von Mises stresses were correlated with the critical values for various phases of the nickel-titanium material. Different loading conditions led to unequal patterns of stress distribution. Increasing the applied torque or bending angle resulted in a rise in the corresponding stresses in the instrument. Favorable stress distribution without dangerous stress concentration was observed if the material was undergoing superelastic transformation at that applied load. The ultimate strength of the material was not exceeded when the instrument was bent up to a 50-degree curvature. On the other hand, when a torsional moment of greater than 1.0 N*mm was applied, the maximum stresses developed in some designs would exceed the ultimate strength of the material. Little variation in the von Mises stresses was observed for instruments of different nominal sizes and tapers on bending to similar extent. The cross-sectional design has a greater impact than taper or size of the instrument on the stresses developed in the instrument under either torsion or bending. Certain cross-sectional configurations are prone to fracture by excess torsional stresses. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Jet impinging onto a laser drilled tapered hole: Influence of tapper location on heat transfer and skin friction at hole surface

NASA Astrophysics Data System (ADS)

Shuja, S. Z.; Yilbas, B. S.

2013-02-01

Jet emerging from a conical nozzle and impinging onto a tapered hole in relation to laser drilling is investigated and the influence taper location on the heat transfer and skin friction at the hole wall surface is examined. The study is extended to include four different gases as working fluid. The Reynolds stress model is incorporated to account for the turbulence effect in the flow field. The hole wall surface temperature is kept at 1500 K to resemble the laser drilled hole. It is found that the location of tapering in the hole influences the heat transfer rates and skin friction at the hole wall surface. The maximum skin friction coefficient increases for taper location of 0.25 H, where H is the thickness of the workpiece, while Nusselt number is higher in the hole for taper location of 0.75 H.

Pulse compression using a tapered microstructure optical fiber.

PubMed

Hu, Jonathan; Marks, Brian S; Menyuk, Curtis R; Kim, Jinchae; Carruthers, Thomas F; Wright, Barbara M; Taunay, Thierry F; Friebele, E J

2006-05-01

We calculate the pulse compression in a tapered microstructure optical fiber with four layers of holes. We show that the primary limitation on pulse compression is the loss due to mode leakage. As a fiber's diameter decreases due to the tapering, so does the air-hole diameter, and at a sufficiently small diameter the guided mode loss becomes unacceptably high. For the four-layer geometry we considered, a compression factor of 10 can be achieved by a pulse with an initial FWHM duration of 3 ps in a tapered fiber that is 28 m long. We find that there is little difference in the pulse compression between a linear taper profile and a Gaussian taper profile. More layers of air-holes allows the pitch to decrease considerably before losses become unacceptable, but only a moderate increase in the degree of pulse compression is obtained.

Spanwise visualization of the flow around a three-dimensional foil with leading edge protuberances

NASA Astrophysics Data System (ADS)

Stanway, M. J.; Techet, A. H.

2006-11-01

Studies of model humpback whale fins have shown that leading edge protuberances, or tubercles, can lead to delayed stall and increased lift at higher angles of attack, compared to foils with geometrically smooth leading edges. Such enhanced performance characteristics could prove highly useful in underwater vehicles such as gliders or long range AUVs (autonomous underwater vehicles). In this work, Particle Imaging Velocimetry (PIV) is performed on two static wings in a water tunnel over a range of angles of attack. These three- dimensional, finite-aspect ratio wings are modeled after a humpback whale flipper and are identical in shape, tapered from root to tip, except for the leading edge. In one of the foils the leading edge is smooth, whereas in the other, regularly spaced leading edge bumps are machined to simulate the whale’s fin tubercles. Results from these PIV tests reveal distinct cells where coherent flow structures are destroyed as a result of the leading edge perturbations. Tests are performed at Reynolds numbers Re ˜ O(10^5), based on chordlength, in a recirculating water tunnel. An inline six-axis load cell is mounted to measure the forces on the foil over a range of static pitch angles. It is hypothesized that this spanwise breakup of coherent vortical structures is responsible for the delayed angle of stall. These quantitative experiments complement exiting qualitative studies with two dimensional foils.

Combining liquid inertia with pressure recovery from bubble expansion for enhanced flow boiling

NASA Astrophysics Data System (ADS)

Kalani, A.; Kandlikar, S. G.

2015-11-01

In this paper, we demonstrate using liquid inertia force in a taper gap microchannel geometry to provide a high level of heat dissipation capacity accompanied by a high heat transfer coefficient and low pressure drop during flow boiling. The high mass flux increases liquid inertia force and promotes vapor removal from the manifold, thereby increasing critical heat flux (CHF) and heat transfer coefficient. The tapered gap above the microchannels provides an increasing cross-sectional area in the flow direction. This gap allows bubbles to emerge from microchannels and expand within the gap along the flow direction. The bubble evaporation and expansion in tapered gap causes pressure recovery and reduces the total pressure drop. The pressure recovery increases with the increased evaporation rate at higher heat fluxes. Using a 6% taper and a moderately high inlet liquid flow Reynolds number of 1095, we have reached a CHF of 1.07 kW/cm2 with a heat transfer coefficient of 295 kW/m2 °C and a pressure drop of 30 kPa.

Photonic lantern with multimode fibers embedded

NASA Astrophysics Data System (ADS)

Yu, Hai-Jiao; Yan, Qi; Huang, Zong-Jun; Tian, He; Jiang, Yu; Liu, Yong-Jun; Zhang, Jian-Zhong; Sun, Wei-Min

2014-08-01

A photonic lantern is studied which is formed by seven multimode fibers inserted into a pure silica capillary tube. The core of the tapered end has a uniform refractive index because the polymer claddings are removed before the fibers are inserted. Consequently, the light distribution is also uniform. Two theories describing a slowly varying waveguide and multimode coupling are used to analyze the photonic lantern. The transmission loss decreases as the length of the tapered part increases. For a device with a taper length of 3.4 cm, the loss is about 1.06 dB on average for light propagating through the taper from an inserted fiber to the tapered end and 0.99 dB in the reverse direction. For a device with a taper length of 0.7 cm, the two loss values are 2.63 dB and 2.53 dB, respectively. The results show that it is possible to achieve a uniform light distribution with the tapered end and a low-loss transmission in the device if parameters related to the lantern are reasonably defined.

Trunnion Failure of the Recalled Low Friction Ion Treatment Cobalt Chromium Alloy Femoral Head.

PubMed

Urish, Kenneth L; Hamlin, Brian R; Plakseychuk, Anton Y; Levison, Timothy J; Higgs, Genymphas B; Kurtz, Steven M; DiGioia, Anthony M

2017-09-01

Gross trunnion failure (GTF) is a rare complication in total hip arthroplasty (THA) reported across a range of manufacturers. Specific lots of the Stryker low friction ion treatment (LFIT) anatomic cobalt chromium alloy (CoCr) V40 femoral head were recalled in August 2016. In part, the recall was based out of concerns for disassociation of the femoral head from the stem and GTF. We report on 28 patients (30 implants) with either GTF (n = 18) or head-neck taper corrosion (n = 12) of the LFIT CoCr femoral head and the Accolade titanium-molybdenum-zirconium-iron alloy femoral stems. All these cases were associated with adverse local tissue reactions requiring revision of the THA. In our series, a conservative estimate of the incidence of failure was 4.7% (n = 636 total implanted) at 8.0 ± 1.4 years from the index procedure. Failures were associated with a high-offset 127° femoral stem neck angle and increased neck lengths; 43.3% (13 of 30) of the observed failures included implant sizes outside the voluntary recall (27.8% [5 of 18] of the GTF and 75.0% [8 of 12] of the taper corrosion cases). Serum cobalt and chromium levels were elevated (cobalt: 8.4 ± 7.0 μg/mL; chromium: 3.4 ± 3.3 μ/L; cobalt/chromium ratio: 3.7). The metal artifact reduction sequence magnetic resonance imaging demonstrated large cystic fluid collections typical with adverse local tissue reactions. During revision, a pseudotumor was observed in all cases. Pathology suggested a chronic inflammatory response. Impending GTF could be diagnosed based on aspiration of black synovial fluid and an oblique femoral head as compared with the neck taper on radiographs. In our series of the recalled LFIT CoCr femoral head, the risk of impending GTF or head-neck taper corrosion should be considered as a potential diagnosis in a painful LFIT femoral head and Accolade titanium-molybdenum-zirconium-iron alloy THA with unknown etiology. Almost half of the failures we observed included sizes outside of the voluntary recall. Copyright © 2017 Elsevier Inc. All rights reserved.

Optimizing treatment with tumour necrosis factor inhibitors in rheumatoid arthritis-a proof of principle and exploratory trial: is dose tapering practical in good responders?

PubMed

Ibrahim, Fowzia; Lorente-Cánovas, Beatriz; Doré, Caroline J; Bosworth, Ailsa; Ma, Margaret H; Galloway, James B; Cope, Andrew P; Pande, Ira; Walker, David; Scott, David L

2017-11-01

RA patients receiving TNF inhibitors (TNFi) usually maintain their initial doses. The aim of the Optimizing Treatment with Tumour Necrosis Factor Inhibitors in Rheumatoid Arthritis trial was to evaluate whether tapering TNFi doses causes loss of clinical response. We enrolled RA patients receiving etanercept or adalimumab and a DMARD with DAS28 under 3.2 for over 3 months. Initially (months 0-6) patients were randomized to control (constant TNFi) or two experimental groups (tapering TNFi by 33 or 66%). Subsequently (months 6-12) control subjects were randomized to taper TNFi by 33 or 66%. Disease flares (DAS28 increasing ⩾0.6 with at least one additional swollen joint) were the primary outcome. Two hundred and forty-four patients were screened, 103 randomized and 97 treated. In months 0-6 there were 8/50 (16%) flares in controls, 3/26 (12%) with 33% tapering and 6/21 (29%) with 66% tapering. Multivariate Cox analysis showed time to flare was unchanged with 33% tapering but was reduced with 66% tapering compared with controls (adjusted hazard ratio 2.81, 95% CI: 0.99, 7.94; P = 0.051). Analysing all tapered patients after controls were re-randomized (months 6-12) showed differences between groups: there were 6/48 (13%) flares with 33% tapering and 14/39 (36%) with 66% tapering. Multivariate Cox analysis showed 66% tapering reduced time to flare (adjusted hazard ratio 3.47, 95% CI: 1.26, 9.58; P = 0.016). Tapering TNFi by 33% has no impact on disease flares and appears practical in patients in sustained remission and low disease activity states. EudraCT, https://www.clinicaltrialsregister.eu, 2010-020738-24; ISRCTN registry, https://www.isrctn.com, 28955701. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Rheumatology.

Optimizing treatment with tumour necrosis factor inhibitors in rheumatoid arthritis—a proof of principle and exploratory trial: is dose tapering practical in good responders?

PubMed Central

Lorente-Cánovas, Beatriz; Doré, Caroline J; Bosworth, Ailsa; Ma, Margaret H; Galloway, James B; Cope, Andrew P; Pande, Ira; Walker, David; Scott, David L

2017-01-01

Abstract Objectives RA patients receiving TNF inhibitors (TNFi) usually maintain their initial doses. The aim of the Optimizing Treatment with Tumour Necrosis Factor Inhibitors in Rheumatoid Arthritis trial was to evaluate whether tapering TNFi doses causes loss of clinical response. Methods We enrolled RA patients receiving etanercept or adalimumab and a DMARD with DAS28 under 3.2 for over 3 months. Initially (months 0–6) patients were randomized to control (constant TNFi) or two experimental groups (tapering TNFi by 33 or 66%). Subsequently (months 6–12) control subjects were randomized to taper TNFi by 33 or 66%. Disease flares (DAS28 increasing ⩾0.6 with at least one additional swollen joint) were the primary outcome. Results Two hundred and forty-four patients were screened, 103 randomized and 97 treated. In months 0–6 there were 8/50 (16%) flares in controls, 3/26 (12%) with 33% tapering and 6/21 (29%) with 66% tapering. Multivariate Cox analysis showed time to flare was unchanged with 33% tapering but was reduced with 66% tapering compared with controls (adjusted hazard ratio 2.81, 95% CI: 0.99, 7.94; P = 0.051). Analysing all tapered patients after controls were re-randomized (months 6–12) showed differences between groups: there were 6/48 (13%) flares with 33% tapering and 14/39 (36%) with 66% tapering. Multivariate Cox analysis showed 66% tapering reduced time to flare (adjusted hazard ratio 3.47, 95% CI: 1.26, 9.58; P = 0.016). Conclusion Tapering TNFi by 33% has no impact on disease flares and appears practical in patients in sustained remission and low disease activity states. Trail registration EudraCT, https://www.clinicaltrialsregister.eu, 2010-020738-24; ISRCTN registry, https://www.isrctn.com, 28955701 PMID:28968858

Self-equilibrated Tapered Three-stage Tensegrity Mast

NASA Astrophysics Data System (ADS)

Oh, C. L.; Choong, K. K.; Nishimura, T.; Lee, S. W.

2018-04-01

Investigation of tensegrity structures for the space application is ongoing owing to the characteristics of being lightweight and flexible. Tensegrity structures consist of struts and cables are self-stressed and stable under gravitational loading. Form-finding is an important process to obtain the configuration of tensegrity structures that are in self-equilibrated state. Form-finding of tensegrity structures involves a complex computational strategy in solving the geometrical and forces of the structures. This paper aims to form-finding for a tapered three-stage tensegrity mast. The form-finding strategy involves the assemblage of the tensegrity mast, establishment of equilibrium equations and determination of one possible set of coefficient beta. Several cases of configurations with various twist angles with range of 20°-40° are investigated. A configuration with 9 struts and 42 cables satisfying the material elastic conditions was successfully found. The scalable self-equilibrated tensegrity mast is recommended for space applications.

Ultra-wideband microwave absorber by connecting multiple absorption bands of two different-sized hyperbolic metamaterial waveguide arrays.

PubMed

Yin, Xiang; Long, Chang; Li, Junhao; Zhu, Hua; Chen, Lin; Guan, Jianguo; Li, Xun

2015-10-19

Microwave absorbers have important applications in various areas including stealth, camouflage, and antenna. Here, we have designed an ultra-broadband light absorber by integrating two different-sized tapered hyperbolic metamaterial (HMM) waveguides, each of which has wide but different absorption bands due to broadband slow-light response, into a unit cell. Both the numerical and experimental results demonstrate that in such a design strategy, the low absorption bands between high absorption bands with a single-sized tapered HMM waveguide array can be effectively eliminated, resulting in a largely expanded absorption bandwidth ranging from 2.3 to 40 GHz. The presented ultra-broadband light absorber is also insensitive to polarization and robust against incident angle. Our results offer a further step in developing practical artificial electromagnetic absorbers, which will impact a broad range of applications at microwave frequencies.

Tapered whiskers are required for active tactile sensation.

PubMed

Hires, Samuel Andrew; Pammer, Lorenz; Svoboda, Karel; Golomb, David

2013-11-19

Many mammals forage and burrow in dark constrained spaces. Touch through facial whiskers is important during these activities, but the close quarters makes whisker deployment challenging. The diverse shapes of facial whiskers reflect distinct ecological niches. Rodent whiskers are conical, often with a remarkably linear taper. Here we use theoretical and experimental methods to analyze interactions of mouse whiskers with objects. When pushed into objects, conical whiskers suddenly slip at a critical angle. In contrast, cylindrical whiskers do not slip for biologically plausible movements. Conical whiskers sweep across objects and textures in characteristic sequences of brief sticks and slips, which provide information about the tactile world. In contrast, cylindrical whiskers stick and remain stuck, even when sweeping across fine textures. Thus the conical whisker structure is adaptive for sensor mobility in constrained environments and in feature extraction during active haptic exploration of objects and surfaces. DOI: http://dx.doi.org/10.7554/eLife.01350.001.

Pressure distribution on a 1- by 3-meter semispan wing at sweep angles from 0 deg to 40 deg in subsonic flow

NASA Technical Reports Server (NTRS)

Yip, L. P.; Shubert, G. L.

1976-01-01

A 1- by 3-meter semispan wing of taper ratio 1.0 with NACA 0012 airfoil section contours was tested in the Langley V/STOL tunnel to measure the pressure distribution at five sweep angles, 0 deg, 10 deg, 20 deg, 30 deg, and 40 deg, through an angle-of-attack range from -6 deg to 20 deg. The pressure data are presented as plots of pressure coefficients at each static-pressure tap location on the wing. Flow visualization wing-tuft photographs are also presented for a wing of 40 deg sweep. A comparison between theory and experiment using two inviscid theories and a viscous theory shows good agreement for pressure distributions, normal forces, and pitching moments for the wing at 0 deg sweep.

Fretting-corrosion at the modular tapers interface: Inspection of standard ASTM F1875-98.

PubMed

Bingley, Rachel; Martin, Alan; Manfredi, Olivia; Nejadhamzeeigilani, Mahdiyar; Oladokun, Abimbola; Beadling, Andrew Robert; Siddiqui, Sohail; Anderson, James; Thompson, Jonathan; Neville, Anne; Bryant, Michael

2018-05-01

Interest in the degradation mechanisms at the modular tapers interfaces has been renewed due to increased reported cases of adverse reactions to metal debris and the appearance of wear and corrosion at the modular tapers interfaces at revision. Over the past two decades, a lot of research has been expended to understand the degradation mechanisms, with two primary implant loading procedures and orientations used consistently across the literature. ASTM F1875-98 is often used as a guide to understand and benchmark the tribocorrosion processes occurring within the modular tapers interface. This article presents a comparison of the two methods outlined in ASTM F1875-98 as well as a critique of the standard considering the current paradigm in pre-clinical assessment of modular tapers.

Experimental observation of breathing solitons and a third harmonic in a tapered photonic crystal fiber

NASA Astrophysics Data System (ADS)

Wang, F.; Yao, C. F.; Li, C. Z.; Jia, Z. X.; Li, Q.; Wu, C. F.; Ohishi, Y.; Qin, W. P.; Qin, G. S.

2018-02-01

We report the experimental observation of breathing solitons and a third harmonic in a tapered fluorotellurite photonic crystal fiber (PCF) pumped by a 1560 nm femtosecond fiber laser. The PCF has a core diameter that varies continuously along its length, resulting in a zero-dispersion wavelength that moves from 1325 nm to 906 nm over the transition region. By finely controlling the dispersion map of the tapered PCF and increasing the order of the optical solitons, their breathing behavior is observed in the frequency domain and the number of breaths goes up to 9. Furthermore, the breathing behavior of the optical soliton is transferred to the third harmonic through inter-modal phase-matched processes in the tapered PCF, and the third harmonic also breathes with an increase in the pump power.

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

PubMed

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 < 0.05) were evident by the early phases of TAPER. A significant 7.0% improvement in 3 × 300-m performance time, a 6.9% improvement in the vertical jump (p < 0.05), and increased morning and evening SIgA secretion rate (p < 0.01) were observed during the middle-late phases of 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.

Design and performance of tapered cubic anvil used for achieving higher pressure and larger sample cell

NASA Astrophysics Data System (ADS)

Han, Qi-Gang; Yang, Wen-Ke; Zhu, Pin-Wen; Ban, Qing-Chu; Yan, Ni; Zhang, Qiang

2013-07-01

In order to increase the maximum cell pressure of the cubic high pressure apparatus, we have developed a new structure of tungsten carbide cubic anvil (tapered cubic anvil), based on the principle of massive support and lateral support. Our results indicated that the tapered cubic anvil has some advantages. First, tapered cubic anvil can push the transfer rate of pressure well into the range above 36.37% compare to the conventional anvil. Second, the rate of failure crack decreases about 11.20% after the modification of the conventional anvil. Third, the limit of static high-pressure in the sample cell can be extended to 13 GPa, which can increase the maximum cell pressure about 73.3% than that of the conventional anvil. Fourth, the volume of sample cell compressed by tapered cubic anvils can be achieved to 14.13 mm3 (3 mm diameter × 2 mm long), which is three and six orders of magnitude larger than that of double-stage apparatus and diamond anvil cell, respectively. This work represents a relatively simple method for achieving higher pressures and larger sample cell.

Spatial solitons of desired intensity and width and their self-tapering/uptapering in cubic quintic nonlinear medium

NASA Astrophysics Data System (ADS)

Krishna Sarkar, Ram; Medhekar, S.

2007-12-01

In this paper, we have investigated the propagation behavior of a Gaussian beam in cubic quintic nonlinear medium with and without absorption or gain. A governing differential equation for the evolution of beam width with the distance of propagation has been derived using the standard parabolic equation approach. By solving the governing equation numerically for different sets of parameters, we have shown that spatial solitons of fixed width and desired intensity and of fixed intensity and desired width are possible. Such liberty does not exist in other saturable media. We have also investigated self-tapering and self-uptapering of spatial solitons in the presence of absorption or gain and showed that the rate of self-tapering/uptapering is not only controlled by the magnitude of absorption or gain but also by the values of cubic and quintic terms. It is revealed that by self-tapering, the smallest achievable soliton width decreases/increases by increasing the magnitude of the cubic/quintic term. It is also revealed that the smallest achievable soliton width by self-tapering, is smaller for a larger initial width.

A new detector for low Pt physics

NASA Astrophysics Data System (ADS)

Da Via, C.; DeSalvo, R.; Lundin, M.; Mondardini, M. R.; Orear, J.; Shimizu, T.; Shinji, O.

1992-12-01

Elastic pp (or poverlinep) scattering at microradian angles provides a measurement of the total pp (or poverlinep) cross sectio elastic scattering cross section with t (the square of the momentum transfer) and the ratio of real to imaginary scattering amplitudes, as well as an absolute luminosity calibration. A detector is proposed which can measure elastic scattering and small angle processes which are usually missed by a typical 4π detector. The detector consists of a bundle of scintillating fibers. Images from these fibers are transported via glass fiber optics and intensified with two proximity focused image intensifiers. Images are then reduced via an image taper and read out with a charge coupled device (CCD).

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

NASA Astrophysics Data System (ADS)

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.

Impaction Force Influences Taper-Trunnion Stability in Total Hip Arthroplasty.

PubMed

Danoff, Jonathan R; Longaray, Jason; Rajaravivarma, Raga; Gopalakrishnan, Ananthkrishnan; Chen, Antonia F; Hozack, William J

2018-07-01

This study investigated the influence of femoral head impaction force, number of head strikes, the energy sequence of head strikes, and head offset on the strength of the taper-trunnion junction. Thirty titanium-alloy trunnions were mated with 36-mm zero-offset cobalt-chromium femoral heads of corresponding taper angle. A drop tower impacted the head with 2.5J or 8.25J, resulting in 6 kN or 14 kN impaction force, respectively, in a single strike or combinations of 6 kN + 14 kN or 14 kN + 14 kN. In addition, ten 36-mm heads with -5 and +5 offset were impacted with sequential 14 kN + 14 kN strikes. Heads were subsequently disassembled using a screw-driven mechanical testing frame, and peak distraction force was recorded. Femoral head pull-off force was 45% the strike force, and heads struck with a single 14 kN impact showed a pull-off force twice that of the 6 kN group. Two head strikes with the same force did not improve pull-off force for either 6 kN (P = .90) or 14 kN (P = .90). If the forces of the 2 impactions varied, but either impact measured 14 kN, a 51% higher pull-off force was found compared to impactions of either 6 kN or 6 kN + 6 kN. Femoral head offset did not significantly change the pull-off force among -5, 0, and +5 heads (P = .37). Femoral head impaction force influenced femoral head trunnion-taper stability, whereas offset did not affect pull-off force. Multiple head strikes did not add additional stability, as long as a single strike achieved 14 kN force at the mallet-head impactor interface. Insufficient impaction force may lead to inadequate engagement of the trunnion-taper junction. Copyright © 2018 Elsevier Inc. All rights reserved.

Tapered Optical Fiber Probe Assembled with Plasmonic Nanostructures for Surface-Enhanced Raman Scattering Application.

PubMed

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.

Fabrication of an Optical Fiber Micro-Sphere with a Diameter of Several Tens of Micrometers.

PubMed

Yu, Huijuan; Huang, Qiangxian; Zhao, Jian

2014-06-25

A new method to fabricate an integrated optical fiber micro-sphere with a diameter within 100 µm, based on the optical fiber tapering technique and the Taguchi method is proposed. Using a 125 µm diameter single-mode (SM) optical fiber, an optical fiber taper with a cone angle is formed with the tapering technique, and the fabrication optimization of a micro-sphere with a diameter of less than 100 µm is achieved using the Taguchi method. The optimum combination of process factors levels is obtained, and the signal-to-noise ratio (SNR) of three quality evaluation parameters and the significance of each process factors influencing them are selected as the two standards. Using the minimum zone method (MZM) to evaluate the quality of the fabricated optical fiber micro-sphere, a three-dimensional (3D) numerical fitting image of its surface profile and the true sphericity are subsequently realized. From the results, an optical fiber micro-sphere with a two-dimensional (2D) diameter less than 80 µm, 2D roundness error less than 0.70 µm, 2D offset distance between the micro-sphere center and the fiber stylus central line less than 0.65 µm, and true sphericity of about 0.5 µm, is fabricated.

High-sensitivity refractive index sensors based on fused tapered photonic crystal fiber

NASA Astrophysics Data System (ADS)

Fu, Xing-hu; Xie, Hai-yang; Yang, Chuan-qing; Qu, Yu-wei; Zhang, Shun-yang; Fu, Guang-wei; Guo, Xuan; Bi, Wei-hong

2016-05-01

In this paper, a novel liquid refractive index (RI) sensor based on fused tapered photonic crystal fiber (PCF) is proposed. It is fabricated by fusing and tapering a section of PCF which is spliced with two single-mode fibers (SMFs). Due to the fused biconical taper method, the sensor becomes longer and thinner, to make the change of the outside RI has more direct effects on the internal optical field of the PCF, which finally enhances the sensitivity of this sensor. Experimental results show that the transmission spectra of the sensor are red-shifted obviously with the increase of RI. The longer the tapered region of the sensor, the higher the sensitivity is. This sensor has the advantages of simple structure, easy fabrication, high performance and so on, so it has potential applications in RI measurement.

Angle Measurement System (AMS) for Establishing Model Pitch and Roll Zero, and Performing Single Axis Angle Comparisons

NASA Technical Reports Server (NTRS)

Crawford, Bradley L.

2007-01-01

The angle measurement system (AMS) developed at NASA Langley Research Center (LaRC) is a system for many uses. It was originally developed to check taper fits in the wind tunnel model support system. The system was further developed to measure simultaneous pitch and roll angles using 3 orthogonally mounted accelerometers (3-axis). This 3-axis arrangement is used as a transfer standard from the calibration standard to the wind tunnel facility. It is generally used to establish model pitch and roll zero and performs the in-situ calibration on model attitude devices. The AMS originally used a laptop computer running DOS based software but has recently been upgraded to operate in a windows environment. Other improvements have also been made to the software to enhance its accuracy and add features. This paper will discuss the accuracy and calibration methodologies used in this system and some of the features that have contributed to its popularity.

Parametric analysis of swept-wing geometry with sheared wing tips

NASA Technical Reports Server (NTRS)

Fremaux, C. M.; Vijgen, P. M. H. W.; Van Dam, C. P.

1990-01-01

A computational parameter study is presented of potential reductions in induced drag and increases in lateral-directional stability due to sheared wing tips attached to an untwisted wing of moderate sweep and aspect ratio. Sheared tips are swept and tapered wing-tip devices mounted in the plane of the wing. The induced-drag results are obtained using an inviscid, incompressible surface-panel method that models the nonlinear effects due to the deflected and rolled-up wake behind the lifting surface. The induced-drag results with planar sheared tips are compared to straight-tapered tip extensions and nonplanar winglet geometries. The lateral-directional static-stability characteristics of the wing with sheared tips are estimated using a quasi-vortex-lattice method. For certain combinations of sheared-tip sweep and taper, both the induced efficiency of the wing and the relevant static-stability derivatives are predicted to increase compared to the wing with a straight-tapered tip modification.

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

PubMed

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.

Glass light pipes for solar concentration

NASA Astrophysics Data System (ADS)

Madsen, C. K.; Dogan, Y.; Morrison, M.; Hu, C.; Atkins, R.

2018-02-01

Glass waveguides are fabricated using laser processing techniques that have low optical loss with >90% optical throughput. Advanced light pipes are demonstrated, including angled facets for turning mirrors used for lens-to-light pipe coupling, tapers that increase the concentration, and couplers for combining the outputs from multiple lens array elements. Because they are fabricated from glass, these light pipes can support large optical concentrations and propagate broadband solar over long distances with minimal loss and degradation compared to polymer waveguides. Applications include waveguiding solar concentrators using multi-junction PV cells, solar thermal applications and remoting solar energy, such as for daylighting. Ray trace simulations are used to estimate the surface smoothness required to achieve low loss. Optical measurements for fabricated light pipes are reported for use in waveguiding solar concentrator architectures.

Double-clad fiber with a tapered end for confocal endomicroscopy.

PubMed

Lemire-Renaud, Simon; Strupler, Mathias; Benboujja, Fouzi; Godbout, Nicolas; Boudoux, Caroline

2011-11-01

We present a double-clad fiber coupler (DCFC) for use in confocal endomicroscopy to reduce speckle contrast, increase signal collection while preserving optical sectioning. The DCFC is made by incorporating a double-clad tapered fiber (DCTF) to a fused-tapered DCFC for achromatic transmission (from 1265 nm to 1325 nm) of > 95% illumination light trough the single mode (SM) core and collection of > 40% diffuse light through inner cladding modes. Its potential for confocal endomicroscopy is demonstrated in a spectrally-encoded imaging setup which shows a 3 times reduction in speckle contrast as well as 5.5 × increase in signal collection compared to imaging with a SM fiber.

Efficacy of Tramadol Extended-Release for Opioid Withdrawal: A Randomized Clinical Trial.

PubMed

Dunn, Kelly E; Tompkins, D Andrew; Bigelow, George E; Strain, Eric C

2017-09-01

Opioid use disorder (OUD) is a significant public health problem. Supervised withdrawal (ie, detoxification) from opioids using clonidine or buprenorphine hydrochloride is a widely used treatment. To evaluate whether tramadol hydrochloride extended-release (ER), an approved analgesic with opioid and nonopioid mechanisms of action and low abuse potential, is effective for use in supervised withdrawal settings. A randomized clinical trial was conducted in a residential research setting with 103 participants with OUD. Participants' treatment was stabilized with morphine, 30 mg, administered subcutaneously 4 times daily. A 7-day taper using clonidine (n = 36), tramadol ER (n = 36), or buprenorphine (n = 31) was then instituted, and patients were crossed-over to double-blind placebo during a post-taper period. The study was conducted from October 25, 2010, to June 23, 2015. Retention, withdrawal symptom management, concomitant medication utilization, and naltrexone induction. Results were analyzed over time and using area under the curve for the intention-to-treat and completer groups. Of the 103 participants, 88 (85.4%) were men and 43 (41.7%) were white; mean (SD) age was 28.9 (10.4) years. Buprenorphine participants (28 [90.3%]) were significantly more likely to be retained at the end of the taper compared with clonidine participants (22 [61.1%]); tramadol ER retention was intermediate and did not differ significantly from that of the other groups (26 [72.2%]; χ2 = 8.5, P = .01). Time-course analyses of withdrawal revealed significant effects of phase (taper, post taper) for the Clinical Opiate Withdrawal Scale (COWS) score (taper mean, 5.19 [SE, .26]; post-taper mean, 3.97 [SE, .23]; F2,170 = 3.6, P = .03) and Subjective Opiate Withdrawal Scale (SOWS) score (taper mean,8.81 [SE, .40]; post-taper mean, 4.14 [SE, .30]; F2,170 = 15.7, P < .001), but no group effects or group × phase interactions. Analyses of area under the curve of SOWS total scores showed significant reductions (F2,159 = 17.7, P < .001) in withdrawal severity between the taper and post-taper periods for clonidine (taper mean, 13.1; post-taper mean, 3.2; P < .001) and tramadol ER (taper mean, 7.4; post-taper mean, 2.8; P = .03), but not buprenorphine (taper mean, 6.4; post-taper mean, 7.4). Use of concomitant medication increased significantly (F2,159 = 30.7,  P < .001) from stabilization to taper in the clonidine (stabilization mean, 0.64 [SE, .05]; taper mean, 1.54 [SE, .10]; P < .001) and tramadol ER (stabilization mean, 0.53 [SE, .05]; taper mean, 1.19 [SE, .09]; P = .003) groups and from stabilization to post taper in the buprenorphine group (stabilization mean, 0.46 [SE, .05] post-taper mean, 1.17 [SE, .09]; P = .006), suggesting higher withdrawal for those groups during those periods. Naltrexone initiation was voluntary and the percentage of participants choosing naltrexone therapy within the clonidine (8 [22.2%]), tramadol ER (7 [19.4%]), or buprenorphine (3 [9.7%]) groups did not differ significantly (χ2 = 2.5, P = .29). The results of this trial suggest that tramadol ER is more effective than clonidine and comparable to buprenorphine in reducing opioid withdrawal symptoms during a residential tapering program. Data support further examination of tramadol ER as a method to manage opioid withdrawal symptoms. Clinicaltrials.gov Identifier: NCT01188421.

Performance of large-bore tapered-roller bearings under combined radial and thrust load at shaft speeds to 15,000 rpm

NASA Technical Reports Server (NTRS)

Parker, R. J.; Signer, H. R.

1977-01-01

The performance of 120.65-mm bore tapered roller bearings was investigated at shaft speeds up to 15,000 rpm. Temperature distribution and bearing heat generation were determined as a function of shaft speed, radial and thrust loads, lubricant flow rate, and lubricant inlet temperature. Lubricant was supplied by either jets or by a combination of holes through the cone directly to the cone-rib contact and jets at the roller small-end side. Cone-rib lubrication significantly improved high-speed tapered-roller bearing performance, yielding lower cone-face temperatures and lower power loss and allowing lower lubricant flow rates for a given speed condition. Bearing temperatures increased with increased shaft speed and decreased with increased lubricant flow rate. Bearing power loss increased with increased shaft speed and increased lubricant flow rate.

Fiber up-tapering and down-tapering for low-loss coupling between anti-resonant hollow-core fiber and solid-core fiber

NASA Astrophysics Data System (ADS)

Zhang, Naiqian; Wang, Zefeng; Xi, Xiaoming

2017-10-01

In this paper, we demonstrate a novel method for the low-loss coupling between solid-core multi-mode fibers (MMFs) and anti-resonant hollow-core fibers (AR-HCFs). The core/cladding diameter of the MMF is 50/125μm and the mode field diameter of the AR-HCFs are 33.3μm and 71.2μm of the ice-cream type AR-HCFs and the non-node type ARHCFs, respectively. In order to match the mode field diameters of these two specific AR-HCFs, the mode field diameter of the MMFs is increased or decreased by up-tapering or down-tapering the MMFs. Then, according to the principle of coupled fiber mode matching, the optimal diameter of tapered fiber for low-loss coupling is calculated. Based on beam propagation method, the calculated coupling losses without tapering process are 0.31dB and 0.89dB, respectively for a MMF-HCF-MMF structure of the ice-cream type AR-HCFs and the non-node type AR-HCFs. These values can be reduced to 0.096dB and 0.047dB when the outer diameters of the MMF are down-tapered to 116μm and up-tapered to 269μm, respectively. What's more, these results can also be verified by existing experiments.

Passively cooled direct drive wind turbine

DOEpatents

Costin, Daniel P [Chelsea, VT

2008-03-18

A wind turbine is provided that passively cools an electrical generator. The wind turbine includes a plurality of fins arranged peripherally around a generator house. Each of the fins being oriented at an angle greater than zero degrees to allow parallel flow of air over the fin. The fin is further tapered to allow a constant portion of the fin to extend beyond the air stream boundary layer. Turbulence initiators on the nose cone further enhance heat transfer at the fins.

Finite Element Study on Continuous Rotating versus Reciprocating Nickel-Titanium Instruments.

PubMed

El-Anwar, Mohamed I; Yousief, Salah A; Kataia, Engy M; El-Wahab, Tarek M Abd

2016-01-01

In the present study, GTX and ProTaper as continuous rotating endodontic files were numerically compared with WaveOne reciprocating file using finite element analysis, aiming at having a low cost, accurate/trustworthy comparison as well as finding out the effect of instrument design and manufacturing material on its lifespan. Two 3D finite element models were especially prepared for this comparison. Commercial engineering CAD/CAM package was used to model full detailed flute geometries of the instruments. Multi-linear materials were defined in analysis by using real strain-stress data of NiTi and M-Wire. Non-linear static analysis was performed to simulate the instrument inside root canal at a 45° angle in the apical portion and subjected to 0.3 N.cm torsion. The three simulations in this study showed that M-Wire is slightly more resistant to failure than conventional NiTi. On the other hand, both materials are fairly similar in case of severe locking conditions. For the same instrument geometry, M-Wire instruments may have longer lifespan than the conventional NiTi ones. In case of severe locking conditions both materials will fail similarly. Larger cross sectional area (function of instrument taper) resisted better to failure than the smaller ones, while the cross sectional shape and its cutting angles could affect instrument cutting efficiency.

Diagnosis Taper Corrosion: When Is It the Taper and When Is It Something Else?

PubMed

Della Valle, Craig J; Calkins, Tyler E; Jacobs, Joshua J

2018-03-01

There has been an increasing use of modularity at the head-neck junction in total hip arthroplasty to more closely mimic the native anatomy, allowing for optimal leg length and stability. Corrosion at this junction in metal-on-polyethylene bearings can lead to an adverse local tissue reaction (ALTR). This increasingly prevalent condition should be considered in the differential diagnosis of hip pain and difficulty ambulating. A recent symposium by the American Academy of Hip and Knee Surgeons described the diagnosis, etiology, management, and prevention of taper corrosion. This article describes the history, physical, plain and advanced imaging findings, laboratory tests, and other diagnoses that should be taken into consideration when diagnosing taper corrosion. The presence of ALTR due to taper corrosion can mimic other diagnoses such as periprosthetic joint infection, instability, or aseptic loosening. Serum metal levels have been found to be the most effective screening tool for identifying corrosion, but other common causes of hip pain and difficulty ambulating should always be ruled out with the use of radiographs and common laboratory techniques before diagnosing ALTR due to corrosion. Copyright © 2018 Elsevier Inc. All rights reserved.

Sideband instability analysis based on a one-dimensional high-gain free electron laser model

DOE PAGES

Tsai, Cheng-Ying; Wu, Juhao; Yang, Chuan; ...

2017-12-18

When an untapered high-gain free electron laser (FEL) reaches saturation, the exponential growth ceases and the radiation power starts to oscillate about an equilibrium. The FEL radiation power or efficiency can be increased by undulator tapering. For a high-gain tapered FEL, although the power is enhanced after the first saturation, it is known that there is a so-called second saturation where the FEL power growth stops even with a tapered undulator system. The sideband instability is one of the primary reasons leading to this second saturation. In this paper, we provide a quantitative analysis on how the gradient of undulatormore » tapering can mitigate the sideband growth. The study is carried out semianalytically and compared with one-dimensional numerical simulations. The physical parameters are taken from Linac Coherent Light Source-like electron bunch and undulator systems. The sideband field gain and the evolution of the radiation spectra for different gradients of undulator tapering are examined. It is found that a strong undulator tapering (~10 % ) provides effective suppression of the sideband instability in the postsaturation regime.« less

Sideband instability analysis based on a one-dimensional high-gain free electron laser model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsai, Cheng-Ying; Wu, Juhao; Yang, Chuan

When an untapered high-gain free electron laser (FEL) reaches saturation, the exponential growth ceases and the radiation power starts to oscillate about an equilibrium. The FEL radiation power or efficiency can be increased by undulator tapering. For a high-gain tapered FEL, although the power is enhanced after the first saturation, it is known that there is a so-called second saturation where the FEL power growth stops even with a tapered undulator system. The sideband instability is one of the primary reasons leading to this second saturation. In this paper, we provide a quantitative analysis on how the gradient of undulatormore » tapering can mitigate the sideband growth. The study is carried out semianalytically and compared with one-dimensional numerical simulations. The physical parameters are taken from Linac Coherent Light Source-like electron bunch and undulator systems. The sideband field gain and the evolution of the radiation spectra for different gradients of undulator tapering are examined. It is found that a strong undulator tapering (~10 % ) provides effective suppression of the sideband instability in the postsaturation regime.« less

Sideband instability analysis based on a one-dimensional high-gain free electron laser model

NASA Astrophysics Data System (ADS)

Tsai, Cheng-Ying; Wu, Juhao; Yang, Chuan; Yoon, Moohyun; Zhou, Guanqun

2017-12-01

When an untapered high-gain free electron laser (FEL) reaches saturation, the exponential growth ceases and the radiation power starts to oscillate about an equilibrium. The FEL radiation power or efficiency can be increased by undulator tapering. For a high-gain tapered FEL, although the power is enhanced after the first saturation, it is known that there is a so-called second saturation where the FEL power growth stops even with a tapered undulator system. The sideband instability is one of the primary reasons leading to this second saturation. In this paper, we provide a quantitative analysis on how the gradient of undulator tapering can mitigate the sideband growth. The study is carried out semianalytically and compared with one-dimensional numerical simulations. The physical parameters are taken from Linac Coherent Light Source-like electron bunch and undulator systems. The sideband field gain and the evolution of the radiation spectra for different gradients of undulator tapering are examined. It is found that a strong undulator tapering (˜10 %) provides effective suppression of the sideband instability in the postsaturation regime.

Mental health, fatigue and function are associated with increased risk of disease flare following TNF inhibitor tapering in patients with rheumatoid arthritis: an exploratory analysis of data from the Optimizing TNF Tapering in RA (OPTTIRA) trial.

PubMed

Bechman, Katie; Sin, Fang En; Ibrahim, Fowzia; Norton, Sam; Matcham, Faith; Scott, David Lloyd; Cope, Andrew; Galloway, James

2018-01-01

Tapering of anti-tumour necrosis factor (TNF) therapy appears feasible, safe and effective in selected patients with rheumatoid arthritis (RA). Depression is highly prevalent in RA and may impact on flare incidence through various mechanisms. This study aims to investigate if psychological states predict flare in patients' dose tapering their anti-TNF therapy. This study is a post-hoc analysis of the Optimizing TNF Tapering in RA trial, a multicentre, randomised, open-label study investigating anti-TNF tapering in RA patients with sustained low disease activity. Patient-reported outcomes (Health Assessment Questionnaire, EuroQol 5-dimension scale, Functional Assessment of Chronic Illness Therapy fatigue scale (FACIT-F), 36-Item Short Form Survey (SF-36)) were collected at baseline. The primary outcome was flare, defined as an increase in 28-joint count Disease Activity Score (DAS28) ≥0.6 and ≥1 swollen joint. Discrete-time survival models were used to identify patient-reported outcomes that predict flare. Ninety-seven patients were randomised to taper their anti-TNF dose by either 33% or 66%. Forty-one patients flared. Higher baseline DAS28 score was associated with flare (adjusted HR 1.96 (95% CI 1.18 to 3.24), p=0.01). Disability (SF-36 physical component score), fatigue (FACIT-F) and mental health (SF-36 mental health subscale (MH)) predicted flare in unadjusted models. In multivariate analyses, only SF-36 MH remained a statistically significant predictor of flare (adjusted HR per 10 units 0.74 (95% CI 0.60 to 0.93), p=0.01). Baseline DAS28 and mental health status are independently associated with flare in patients who taper their anti-TNF therapy. Fatigue and function also associate with flare but the effect disappears when adjusting for confounders. Given these findings, mental health and functional status should be considered in anti-TNF tapering decisions in order to optimise the likelihood of success. EudraCT Number: 2010-020738-24; ISRCTN: 28955701; Post-results.

Mental health, fatigue and function are associated with increased risk of disease flare following TNF inhibitor tapering in patients with rheumatoid arthritis: an exploratory analysis of data from the Optimizing TNF Tapering in RA (OPTTIRA) trial

PubMed Central

Bechman, Katie; Sin, Fang En; Ibrahim, Fowzia; Norton, Sam; Matcham, Faith; Scott, David Lloyd; Cope, Andrew; Galloway, James

2018-01-01

Background Tapering of anti-tumour necrosis factor (TNF) therapy appears feasible, safe and effective in selected patients with rheumatoid arthritis (RA). Depression is highly prevalent in RA and may impact on flare incidence through various mechanisms. This study aims to investigate if psychological states predict flare in patients’ dose tapering their anti-TNF therapy. Methods This study is a post-hoc analysis of the Optimizing TNF Tapering in RA trial, a multicentre, randomised, open-label study investigating anti-TNF tapering in RA patients with sustained low disease activity. Patient-reported outcomes (Health Assessment Questionnaire, EuroQol 5-dimension scale, Functional Assessment of Chronic Illness Therapy fatigue scale (FACIT-F), 36-Item Short Form Survey (SF-36)) were collected at baseline. The primary outcome was flare, defined as an increase in 28-joint count Disease Activity Score (DAS28) ≥0.6 and ≥1 swollen joint. Discrete-time survival models were used to identify patient-reported outcomes that predict flare. Results Ninety-seven patients were randomised to taper their anti-TNF dose by either 33% or 66%. Forty-one patients flared. Higher baseline DAS28 score was associated with flare (adjusted HR 1.96 (95% CI 1.18 to 3.24), p=0.01). Disability (SF-36 physical component score), fatigue (FACIT-F) and mental health (SF-36 mental health subscale (MH)) predicted flare in unadjusted models. In multivariate analyses, only SF-36 MH remained a statistically significant predictor of flare (adjusted HR per 10 units 0.74 (95% CI 0.60 to 0.93), p=0.01). Conclusions Baseline DAS28 and mental health status are independently associated with flare in patients who taper their anti-TNF therapy. Fatigue and function also associate with flare but the effect disappears when adjusting for confounders. Given these findings, mental health and functional status should be considered in anti-TNF tapering decisions in order to optimise the likelihood of success. Trial registration numbers EudraCT Number: 2010-020738-24; ISRCTN: 28955701; Post-results. PMID:29862047

Volatility and change in chronic pain severity predict outcomes of treatment for prescription opioid addiction.

PubMed

Worley, Matthew J; Heinzerling, Keith G; Shoptaw, Steven; Ling, Walter

2017-07-01

Buprenorphine-naloxone (BUP-NLX) can be used to manage prescription opioid addiction among persons with chronic pain, but post-treatment relapse is common and difficult to predict. This study estimated whether changes in pain over time and pain volatility during BUP-NLX maintenance would predict opioid use during the taper BUP-NLX taper. Secondary analysis of a multi-site clinical trial for prescription opioid addiction, using data obtained during a 12-week BUP-NLX stabilization and 4-week BUP-NLX taper. Community clinics affiliated with a national clinical trials network in 10 US cities. Subjects with chronic pain who entered the BUP-NLX taper phase (n = 125) with enrollment occurring from June 2006 to July 2009 (52% male, 88% Caucasian, 31% married). Outcomes were weekly biologically verified and self-reported opioid use from the 4-week taper phase. Predictors were estimates of baseline severity, rate of change and volatility in pain from weekly self-reports during the 12-week maintenance phase. Controlling for baseline pain and treatment condition, increased pain [odds ratio (OR) = 2.38, P = 0.02] and greater pain volatility (OR = 2.43, P = 0.04) predicted greater odds of positive opioid urine screen during BUP-NLX taper. Increased pain (IRR = 1.40, P = 0.04) and greater pain volatility [incidence-rate ratio (IRR) = 1.66, P = 0.009] also predicted greater frequency of self-reported opioid use. Adults with chronic pain receiving out-patient treatment with buprenorphine-naloxone (BUP-NLX) for prescription opioid addiction have an elevated risk for opioid use when tapering off maintenance treatment. Those with relative persistence in pain over time and greater volatility in pain during treatment are less likely to sustain abstinence during BUP-NLX taper. © 2017 Society for the Study of Addiction.

An improved integrally formed radio frequency quadrupole

DOEpatents

Abbott, S.R.

1987-10-05

An improved radio frequency quadrupole is provided having an elongate housing with an elongate central axis and top, bottom and two side walls symmetrically disposed about the axis, and vanes formed integrally with the walls, the vanes each having a cross-section at right angles to the central axis which tapers inwardly toward the axis to form electrode tips spaced from each other by predetermined distances. Each of the four walls, and the vanes integral therewith, is a separate structural element having a central lengthwise plane passing through the tip of the vane, the walls having flat mounting surfaces at right angles to and parallel to the control plane, respectively, which are butted together to position the walls and vane tips relative to each other. 4 figs.

Monitoring training load, recovery-stress state, immune-endocrine responses, and physical performance in elite female basketball players during a periodized training program.

PubMed

Nunes, João A; Moreira, Alexandre; Crewther, Blair T; Nosaka, Ken; Viveiros, Luis; Aoki, Marcelo S

2014-10-01

This study investigated the effect of a periodized training program on internal training load (ITL), recovery-stress state, immune-endocrine responses, and physical performance in 19 elite female basketball players. The participants were monitored across a 12-week period before an international championship, which included 2 overloading and tapering phases. The first overloading phase (fourth to sixth week) was followed by a 1-week tapering, and the second overloading phase (eighth to 10th week) was followed by a 2-week tapering. ITL (session rating of perceived exertion method) and recovery-stress state (RESTQ-76 Sport questionnaire) were assessed weekly and bi-weekly, respectively. Pretraining and posttraining assessments included measures of salivary IgA, testosterone and cortisol concentrations, strength, jumping power, running endurance, and agility. Internal training load increased across all weeks from 2 to 11 (p ≤ 0.05). After the first tapering period (week 7), a further increase in ITL was observed during the second overloading phase (p ≤ 0.05). After the second tapering period, a decrease in ITL was detected (p ≤ 0.05). A disturbance in athlete stress-recovery state was noted during the second overloading period (p ≤ 0.05), before returning to baseline level in end of the second tapering period. The training program led to significant improvements in the physical performance parameters evaluated. The salivary measures did not change despite the fluctuations in ITL. In conclusion, a periodized training program evoked changes in ITL in elite female basketball players, which appeared to influence their recovery-stress state. The training plan was effective in preparing participants for competition, as indicated by improvements in recovery-stress state and physical performance after tapering.

Comparative study of 6 rotary nickel-titanium systems and hand instrumentation for root canal preparation in severely curved root canals of extracted teeth.

PubMed

Celik, Davut; Taşdemir, Tamer; Er, Kürşat

2013-02-01

Some improvements have been developed with new generations of nickel-titanium (NiTi) rotary instruments that led to their successful and extensive application in clinical practice. The purpose of this in vitro study was to compare the root canal preparations performed by using GT Series X and Twisted File systems produced by innovative manufacturing process with Revo-S, RaCe, Mtwo, and ProTaper Universal systems manufactured directly from conventional nitinol and with stainless steel K-Flexofile instruments. The mesiobuccal root canals of 140 maxillary first permanent molars that had between 30°-40° curvature angle and 4- to 9-mm curvature radius of the root canal were used. After root canal preparations made by using GT Series X, Twisted File, Revo-S, RaCe, Mtwo, and ProTaper Universal NiTi rotary systems and stainless steel K-Flexofile instruments, transportation occurred in the root canal, and alteration of working length (WL) was assessed by using a modified double-digital radiographic technique. The data were compared by the post hoc Tukey honestly significant difference test. NiTi rotary systems caused less canal transportation and alteration of WL than K-Flexofile instruments (P < .05). There was no significant difference between NiTi rotary system groups at any levels (P > .05) except 2.5 mm from the WL. At this level ProTaper Universal system caused significant canal transportation (P < .05). GT Series X and Twisted File rotary systems produced with innovative process were concluded to shape the curved canals to result in minimal canal transportation, similar to Revo-S, RaCe, Mtwo, and ProTaper Universal rotary systems manufactured by traditional methods. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Comparative evaluation of cyclic fatigue resistance of four different nickel-titanium rotary files with different cross-sectional designs and alloy properties.

PubMed

Kaval, Mehmet Emin; Capar, Ismail Davut; Ertas, Hüseyin; Sen, Bilge Hakan

2017-06-01

The purpose of the present study was to evaluate the cyclic fatigue resistance of F6 SkyTaper (Komet Brasseler, Lemgo, Germany), K3XF (SybronEndo, Orange, CA, USA), new generation OneShape (Micro Mega, Besancon, France) and TRUShape 3D conforming files (Dentsply Tulsa Dental Specialties, Tulsa, OK, USA). Ten instruments from each group were selected and allowed to rotate using a low-torque motor in a stainless steel block with 1.5 mm diameter, 3 mm radius of 60° angle of curvature at the manufacturer's recommended speed, and the number of cycles (NCF) from the beginning to the fracture was recorded. The data were analyzed using one-way ANOVA followed by post-hoc Tukey's test (P = 0.05). The ranking of the groups from the highest to the lowest NCF was as follows: F6 SkyTaper (959 ± 92), K3XF (725 ± 71), TRUShape (575 ± 84) and OneShape (289 ± 58). Statistically significant differences were detected between all groups (P < 0.05). Within the limitations of this study, F6 SkyTaper instruments presented the highest cyclic fatigue resistance among the tested instruments. The S-shaped cross-sectional design of F6 SkyTaper instruments could be the most important factor on the superior cyclic life span of these instruments. In endodontic practice, preferring the instruments with higher cyclic fatigue resistance would help to minimize the risk of instrument fractures; therefore especially during the preparation of curved canals, instruments with smaller core area and less cross-sectional metal mass, which could lead higher flexibility, can be proposed.

Critical Coupling Between Optical Fibers and WGM Resonators

NASA Technical Reports Server (NTRS)

Matsko, Andrey; Maleki, Lute; Itchenko, Vladimir; Savchenkov, Anatoliy

2009-01-01

Two recipes for ensuring critical coupling between a single-mode optical fiber and a whispering-gallery-mode (WGM) optical resonator have been devised. The recipes provide for phase matching and aperture matching, both of which are necessary for efficient coupling. There is also a provision for suppressing intermodal coupling, which is detrimental because it drains energy from desired modes into undesired ones. According to one recipe, the tip of the single-mode optical fiber is either tapered in diameter or tapered in effective diameter by virtue of being cleaved at an oblique angle. The effective index of refraction and the phase velocity at a given position along the taper depend on the diameter (or effective diameter) and the index of refraction of the bulk fiber material. As the diameter (or effective diameter) decreases with decreasing distance from the tip, the effective index of refraction also decreases. Critical coupling and phase matching can be achieved by placing the optical fiber and the resonator in contact at the proper point along the taper. This recipe is subject to the limitation that the attainable effective index of refraction lies between the indices of refraction of the bulk fiber material and the atmosphere or vacuum to which the resonator and fiber are exposed. The other recipe involves a refinement of the previously developed technique of prism coupling, in which the light beam from the optical fiber is collimated and focused onto one surface of a prism that has an index of refraction greater than that of the resonator. Another surface of the prism is placed in contact with the resonator. The various components are arranged so that the collimated beam is focused at the prism/resonator contact spot. The recipe includes the following additional provisions:

Double-clad fiber with a tapered end for confocal endomicroscopy

PubMed Central

Lemire-Renaud, Simon; Strupler, Mathias; Benboujja, Fouzi; Godbout, Nicolas; Boudoux, Caroline

2011-01-01

We present a double-clad fiber coupler (DCFC) for use in confocal endomicroscopy to reduce speckle contrast, increase signal collection while preserving optical sectioning. The DCFC is made by incorporating a double-clad tapered fiber (DCTF) to a fused-tapered DCFC for achromatic transmission (from 1265 nm to 1325 nm) of > 95% illumination light trough the single mode (SM) core and collection of > 40% diffuse light through inner cladding modes. Its potential for confocal endomicroscopy is demonstrated in a spectrally-encoded imaging setup which shows a 3 times reduction in speckle contrast as well as 5.5 × increase in signal collection compared to imaging with a SM fiber. PMID:22076259

The frequency and level of sweep in mixed hardwood saw logs in the eastern United States

Treesearch

Peter Hamner; Marshall S. White; Philip A. Araman

2007-01-01

Hardwood sawmills traditionally saw logs in a manner that either orients sawlines parallel to the log central axis (straight sawing) or the log surface (allowing for taper). Sweep is characterized as uniform curvature along the entire length of a log. For logs with sweep, lumber yield losses from straight and taper sawing increase with increasing levels of sweep. Curve...

Dust devils on Mars

NASA Astrophysics Data System (ADS)

Thomas, P.; Gierasch, P. J.

1985-10-01

Viking Orbiter photographic imagery has confirmed the occurrence of dust devils on Mars. The images were of small bright clouds with long, tapered shadows viewed from a nearly-nadir angle. Spectra of the features were consistent with dust and not condensates. A maximum height of 6.8 km and width of 1 km were measured. The dust devils appeared on smooth planes, and had average dimensions of 2 km height and 200 m diam, carrying 3000 kg of dust. The data may be of use in interpreting convective processes on earth.

Diffuser/ejector system for a very high vacuum environment

NASA Technical Reports Server (NTRS)

Riggs, K. E.; Wojciechowski, C. J. (Inventor)

1984-01-01

Turbo jet engines are used to furnish the necessary high temperature, high volume, medium pressure gas to provide a high vacuum test environment at comparatively low cost for space engines at sea level. Moreover, the invention provides a unique way by use of the variable area ratio ejectors with a pair of meshing cones are used. The outer cone is arranged to translate fore and aft, and the inner cone is interchangeable with other cones having varying angles of taper.

Pressure Distribution Over Thick Tapered Airfoils, NACA 81, USA 27c Modified and USA 35

NASA Technical Reports Server (NTRS)

Reid, Elliott G

1926-01-01

At the request of the United States Army Air Service, the tests reported herein were conducted in the 5-foot atmospheric wind tunnel of the Langley Memorial Aeronautical Laboratory. The object was the measurment of pressures over three representative thick, tapered airfoils which are being used on existing or forthcoming army airplanes. The results are presented in the form of pressure maps, cross-plan load and normal force coefficient curves and load contours. The pressure distribution along the chord was found very similar to that for thin wings, but with a tendency toward greater negative pressures. The characteristics of the loading across the span of the U. S. A. 27 C modified are inferior to those of the other two wings; in the latter the distribution is almost exactly elliptical throughout the usual range of flying angles. The form of tip incorporated in these models is not completely satisfactory and a modification is recommended. (author)

Calibration of a microchannel plate based extreme ultraviolet grazing incident spectrometer at the Advanced Light Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakeman, M. S.; Lawrence Berkeley National Laboratory, Berkeley, California 94720; Tilborg, J. van

We present the design and calibration of a microchannel plate based extreme ultraviolet spectrometer. Calibration was performed at the Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL). This spectrometer will be used to record the single shot spectrum of radiation emitted by the tapered hybrid undulator (THUNDER) undulator installed at the LOASIS GeV-class laser-plasma-accelerator. The spectrometer uses an aberration-corrected concave grating with 1200 lines/mm covering 11-62 nm and a microchannel plate detector with a CsI coated photocathode for increased quantum efficiency in the extreme ultraviolet. A touch screen interface controls the grating angle, aperture size, and placementmore » of the detector in vacuum, allowing for high-resolution measurements over the entire spectral range.« less

Adaptable Optical Fiber Displacement-Curvature Sensor Based on a Modal Michelson Interferometer with a Tapered Single Mode Fiber

PubMed Central

Salceda-Delgado, G.; Martinez-Rios, A.; Selvas-Aguilar, R.; Álvarez-Tamayo, R. I.; Castillo-Guzman, A.; Ibarra-Escamilla, B.; Durán-Ramírez, V. M.; Enriquez-Gomez, L. F.

2017-01-01

A compact, highly sensitive optical fiber displacement and curvature radius sensor is presented. The device consists of an adiabatic bi-conical fused fiber taper spliced to a single-mode fiber (SMF) segment with a flat face end. The bi-conical taper structure acts as a modal coupling device between core and cladding modes for the SMF segment. When the bi-conical taper is bent by an axial displacement, the symmetrical bi-conical shape of the tapered structure is stressed, causing a change in the refractive index profile which becomes asymmetric. As a result, the taper adiabaticity is lost, and interference between modes appears. As the bending increases, a small change in the fringe visibility and a wavelength shift on the periodical reflection spectrum of the in-fiber interferometer is produced. The displacement sensitivity and the spectral periodicity of the device can be adjusted by the proper selection of the SMF length. Sensitivities from around 1.93 to 3.4 nm/mm were obtained for SMF length between 7.5 and 12.5 cm. Both sensor interrogations, wavelength shift and visibility contrast, can be used to measure displacement and curvature radius magnitudes. PMID:28574421

Adaptable Optical Fiber Displacement-Curvature Sensor Based on a Modal Michelson Interferometer with a Tapered Single Mode Fiber.

PubMed

Salceda-Delgado, G; Martinez-Rios, A; Selvas-Aguilar, R; Álvarez-Tamayo, R I; Castillo-Guzman, A; Ibarra-Escamilla, B; Durán-Ramírez, V M; Enriquez-Gomez, L F

2017-06-02

A compact, highly sensitive optical fiber displacement and curvature radius sensor is presented. The device consists of an adiabatic bi-conical fused fiber taper spliced to a single-mode fiber (SMF) segment with a flat face end. The bi-conical taper structure acts as a modal coupling device between core and cladding modes for the SMF segment. When the bi-conical taper is bent by an axial displacement, the symmetrical bi-conical shape of the tapered structure is stressed, causing a change in the refractive index profile which becomes asymmetric. As a result, the taper adiabaticity is lost, and interference between modes appears. As the bending increases, a small change in the fringe visibility and a wavelength shift on the periodical reflection spectrum of the in-fiber interferometer is produced. The displacement sensitivity and the spectral periodicity of the device can be adjusted by the proper selection of the SMF length. Sensitivities from around 1.93 to 3.4 nm/mm were obtained for SMF length between 7.5 and 12.5 cm. Both sensor interrogations, wavelength shift and visibility contrast, can be used to measure displacement and curvature radius magnitudes.

[Evaluation of preparation of curved root canals using hand-used ProTaper].

PubMed

Nie, Min; Zhao, Xin-Chen; Peng, Bin; Fan, Ming-Wen; Bian, Zhuan

2009-05-01

To evaluate the shaping ability of hand-used ProTaper on curved canals using Endodontic Cube. Fifty-four curved root canals in vitro were selected and divided into three groups according to the curved degree (alpha), group A: 0 degrees < or = alpha < 25 degrees , group B: 25 degrees < or = alpha < 40 degrees , group C: 40 degrees < or = alpha < 55 degrees . Endodontic Cube was assembled, and each sample was sectioned perpendicular to the axis of the tooth into four sections with Isomer-Buhler in low speed. Then the root canals were prepared with hand-used ProTaper. Before and after shaping, photograph of all the sections were taken under a stereomicroscope. Statistical analyses were performed. The dentin cutting quantity of the whole canal prepared with ProTaper in group B and C was larger than that of group A. The deviation distance of the whole canal prepared by ProTaper in group C was significantly larger than that in group A, and the deviation distance in middle portion larger than that in group B. The maintaining ability in the middle portion of group C by ProTaper was worse than that of group A and B. The curvature of root canal may increase the cutting quantity of the -dentin and reduce the ability of remaining original canal shape prepared by ProTaper.

Distribution of smile line, gingival angle and tooth shape among the Saudi Arabian subpopulation and their association with gingival biotype.

PubMed

AlQahtani, Nabeeh A; Haralur, Satheesh B; AlMaqbol, Mohammad; AlMufarrij, Ali Jubran; Al Dera, Ahmed Ali; Al-Qarni, Mohammed

2016-04-01

To determine the occurrence of smile line and maxillary tooth shape in the Saudi Arabian subpopulation, and to estimate the association between these parameters with gingival biotype. On the fulfillment of selection criteria, total 315 patients belong to Saudi Arabian ethnic group were randomly selected. Two frontal photographs of the patients were acquired. The tooth morphology, gingival angle, and smile line classification were determined with ImageJ image analyzing software. The gingival biotype was assessed by probe transparency method. The obtained data were analyzed with SPSS 19 (IBM Corporation, New York, USA) software to determine the frequency and association between other parameters and gingival biotype. Among the clinical parameters evaluated, the tapering tooth morphology (56.8%), thick gingival biotype (53%), and average smile line (57.5%) was more prevalent. The statistically significant association was found between thick gingival biotype and the square tooth, high smile line. The high gingival angle was associated with thin gingival biotype. The study results indicate the existence of an association between tooth shape, smile line, and gingival angle with gingival biotype.

The effects of tapering on strength performance in trained athletes.

PubMed

Gibala, M J; MacDougall, J D; Sale, D G

1994-11-01

The optimum pre-competition taper procedure for "strength athletes" is not known. We examined voluntary strength and evoked contractile properties of the elbow flexors over a 10 day rest only (ROT) and a 10 day reduced volume taper (RVT) in 8 resistance trained males (23 +/- 2.1 years). Following 3 wks of standardized training of the elbow flexors, subjects were randomly assigned to one of the tapers. Upon completion, they resumed training for 3 wks and completed the other taper. No arm training was performed during the ROT, while high intensity, low volume training was done every second day during the RVT. Maximum isometric (MVC), low (0.52 rad.s-1; LV) and high velocity (3.14 rad.s-1; HV) concentric peak torque, and evoked isometric twitch contractile properties were measured before and after each training phase and every 48 h during each taper. ANOVA comparison of the tapers revealed that MVC increased (p < or = 0.05) over pre-taper values throughout the RVT (measurement days 2, 4, 6, 8 and 10), as did LV at 2, 4, 6, and 8 d. MVC did not change over the ROT but LV was significantly higher on day 2 and lower on days 8 and 10. LV was also greater on days 4, 6, 8 and 10 during the RVT compared to the ROT. The evoked contractile properties remained largely unchanged. The data indicate that resistance-trained athletes can improve low velocity concentric strength for at least 8 days by greatly reducing training volume, but maintaining training intensity.

Do Stem Taper Microgrooves Influence Taper Corrosion in Total Hip Arthroplasty? A Matched Cohort Retrieval Study.

PubMed

Arnholt, Christina M; MacDonald, Daniel W; Underwood, Richard J; Guyer, Eric P; Rimnac, Clare M; Kurtz, Steven M; Mont, Michael A; Klein, Gregg R; Lee, Gwo-Chin; Chen, Antonia F; Hamlin, Brian R; Cates, Harold E; Malkani, Arthur L; Kraay, Matthew J

2017-04-01

Previous studies identified imprinting of the stem morphology onto the interior head bore, leading researchers to hypothesize an influence of taper topography on mechanically assisted crevice corrosion. The purpose of this study was to analyze whether microgrooved stem tapers result in greater fretting corrosion damage than smooth stem tapers. A matched cohort of 120 retrieved head-stem pairs from metal-on-polyethylene bearings was created controlling for implantation time, flexural rigidity, apparent length of engagement, and head size. There were 2 groups of 60 heads each, mated with either smooth or microgrooved stem tapers. A high-precision roundness machine was used to measure and categorize the surface morphology. Fretting corrosion damage at the head-neck junction was characterized using the Higgs-Goldberg scoring method. Fourteen of the most damaged heads were analyzed for the maximum depth of material loss and focused ion beam cross-sectioned to view oxide and base metal. Fretting corrosion damage was not different between the 2 cohorts at the femoral head (P = .14, Mann-Whitney) or stem tapers (P = .35). There was no difference in the maximum depths of material loss between the cohorts (P = .71). Cross-sectioning revealed contact damage, signs of micro-motion, and chromium-rich oxide layers in both cohorts. Microgroove imprinting did not appear to have a different effect on the fretting corrosion behavior. The results of this matched cohort retrieval study do not support the hypothesis that taper surfaces with microgrooved stems exhibit increased in vivo fretting corrosion damage or material release. Copyright © 2016 Elsevier Inc. All rights reserved.

Filling high aspect ratio trenches by superconformal chemical vapor deposition: Predictive modeling and experiment

NASA Astrophysics Data System (ADS)

Wang, Wenjiao B.; Abelson, John R.

2014-11-01

Complete filling of a deep recessed structure with a second material is a challenge in many areas of nanotechnology fabrication. A newly discovered superconformal coating method, applicable in chemical vapor deposition systems that utilize a precursor in combination with a co-reactant, can solve this problem. However, filling is a dynamic process in which the trench progressively narrows and the aspect ratio (AR) increases. This reduces species diffusion within the trench and may drive the component partial pressures out of the regime for superconformal coating. We therefore derive two theoretical models that can predict the possibility for filling. First, we recast the diffusion-reaction equation for the case of a sidewall with variable taper angle. This affords a definition of effective AR, which is larger than the nominal AR due to the reduced species transport. We then derive the coating profile, both for superconformal and for conformal coating. The critical (most difficult) step in the filling process occurs when the sidewalls merge at the bottom of the trench to form the V shape. Experimentally, for the Mg(DMADB)2/H2O system and a starting AR = 9, this model predicts that complete filling will not be possible, whereas experimentally we do obtain complete filling. We then hypothesize that glancing-angle, long-range transport of species may be responsible for the better than predicted filling. To account for the variable range of species transport, we construct a ballistic transport model. This incorporates the incident flux from outside the structure, cosine law re-emission from surfaces, and line-of-sight transport between internal surfaces. We cast the transport probability between all positions within the trench into a matrix that represents the redistribution of flux after one cycle of collisions. Matrix manipulation then affords a computationally efficient means to determine the steady-state flux distribution and growth rate for a given taper angle. The ballistic transport model predicts a deeper position for the peak of the super-conformal growth rate than the diffusion-reaction model, and successfully explains the observation of complete filling. These models can be used to predict the behavior of any system given a small set of kinetic coefficients to describe the growth rate.

The effects of autoclave sterilization on the cyclic fatigue resistance of ProTaper Universal, ProTaper Next, and ProTaper Gold nickel-titanium instruments.

PubMed

Özyürek, Taha; Yılmaz, Koray; Uslu, Gülşah

2017-11-01

It was aimed to compare the cyclic fatigue resistances of ProTaper Universal (PTU), ProTaper Next (PTN), and ProTaper Gold (PTG) and the effects of sterilization by autoclave on the cyclic fatigue life of nickel-titanium (NiTi) instruments. Eighty PTU, 80 PTN, and 80 PTG were included to the present study. Files were tested in a simulated canal. Each brand of the NiTi files were divided into 4 subgroups: group 1, as received condition; group 2, pre-sterilized instruments exposed to 10 times sterilization by autoclave; group 3, instruments tested were sterilized after being exposed to 25%, 50%, and 75% of the mean cycles to failure, then cycled fatigue test was performed; group 4, instruments exposed to the same experiment with group 3 without sterilization. The number of cycles to failure (NCF) was calculated. The data was statistically analyzed by using one-way analysis of variance and post hoc Tukey tests. PTG showed significantly higher NCF than PTU and PTN in group 1 ( p < 0.05). Sterilization significantly increased the NCF of PTN and PTG ( p < 0.05) in group 2. PTN in group 3 had significantly higher cyclic fatigue resistance than PTN group 4 ( p < 0.05). Also, significantly higher NCF was observed for PTG in group 2 than in groups 3 and 4 ( p < 0.05). PTG instrument made of new gold alloy was more resistant to fatigue failure than PTN and PTU. Autoclaving increased the cyclic fatigue resistances of PTN and PTG.

Tabulated Data From a Pressure-Distribution Investigation at Mach Number 2.01 of a 45 Deg Sweptback-Wing Airplane Model at Combined Angles of Attack and Sideslip

NASA Technical Reports Server (NTRS)

Gapcynski, John P.; Landrum, Emma Jean

1958-01-01

A pressure-distribution investigation of a wing-body combination has been conducted in the Langley 4- by 4-foot supersonic pressure tunnel at a Mach number of 2.01. The model configuration consisted of an ogive-circular-cylinder body (fineness ratio of approximately ii) and a wing with 45 deg of sweepback at the quarter-chord line, an aspect ratio of 4, and a taper ratio of 0.2. Data were obtained on high-, mid-, and low-wing configurations and for the body and wing alone for a range of angles of attack and yaw from 0 deg to 15 deg. The tabulated pressure coefficients are presented in this report.

Opioid Abstinence Reinforcement Delays Heroin Lapse during Buprenorphine Dose Tapering

ERIC Educational Resources Information Center

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…

Simple, Flexible, Trigonometric Taper Equations

Treesearch

Charles E. Thomas; Bernard R. Parresol

1991-01-01

There have been numerous approaches to modeling stem form in recent decades. The majority have concentrated on the simpler coniferous bole form and have become increasingly complex mathematical expressions. Use of trigonometric equations provides a simple expression of taper that is flexible enough to fit both coniferous and hard-wood bole forms. As an illustration, we...

The challenge of tree height in Eucalyptus regnans: when xylem tapering overcomes hydraulic resistance.

PubMed

Petit, Giai; Pfautsch, Sebastian; Anfodillo, Tommaso; Adams, Mark A

2010-09-01

*Recent research suggests that increasing conduit tapering progressively reduces hydraulic constraints caused by tree height. Here, we tested this hypothesis using the tallest hardwood species, Eucalyptus regnans. *Vertical profiles of conduit dimensions and vessel density were measured for three mature trees of height 47, 51 and 63 m. *Mean hydraulic diameter (Dh) increased rapidly from the tree apex to the point of crown insertion, with the greatest degree of tapering yet reported (b > 0.33). Conduit tapering was such that most of the total resistance was found close to the apex (82-93% within the first 1 m of stem) and the path length effect was reduced by a factor of 2000. Vessel density (VD) declined from the apex to the base of each tree, with scaling parameters being similar for all trees (a = 4.6; b = -0.5). *Eucalyptus regnans has evolved a novel xylem design that ensures a high hydraulic efficiency. This feature enables the species to grow quickly to heights of 50-60 m, beyond the maximum height of most other hardwood trees.

Investigation of optical transmission loss by using a plasmonic Au nanoparticle assembly on a tapered fiber region

NASA Astrophysics Data System (ADS)

Yi, Ji-Haeng

2015-11-01

The optical transmission loss in a tapered fiber fabricated by using plasmonic Au nanoparticle deposition was investigated in the tapered region of the fiber. The amount of Au nanoparticle deposition was determined as a function of time, and the transmission loss was then compared with the losses of several spatial modes. The higher-order mode was found to affect the rate of increase in the transmission loss during the initial period of deposition, and a lower-order mode was found to contribute to the process during the latter period of deposition.

A comparative evaluation of the increase in root canal surface area and canal transportation in curved root canals by three rotary systems: A cone-beam computed tomographic study

PubMed Central

Prasanthi, Nalam NVD; Rambabu, Tanikonda; Sajjan, Girija S; Varma, K Madhu; Satish, R Kalyan; Padmaja, M

2016-01-01

Aim: The aim of this study was to measure the increase in root canal surface area and canal transportation after biomechanical preparation at 1, 3, and 5 mm short of the apex with three different rotary systems in both continuous rotary and reciprocating rotary motions. Materials and Methods: Sixty freshly extracted human mandibular molars with mesial root canal curvatures between 20° and 30° were included in the study. Teeth were randomly distributed into three groups (n = 20). Biomechanical preparations were done in all the mesial canals. In Group 1, instrumentation was done with ProTaper universal rotary files, Group 2, with K3XF rotary files, and Group 3, with LSX rotary files. Each group was further subdivided into subgroups A and B (n = 10) where instrumentation was done by continuous rotary and reciprocating rotary techniques, respectively. Increase in root canal surface area and canal transportation was measured using the preoperative and postoperative cone-beam computed tomography scans. Statistical Analysis: The data were analyzed by one-way ANOVA followed by Tukey pairwise multiple comparison tests. Results: Increase in root canal surface area was significantly more (P < 0.05) in ProTaper and K3XF groups when compared to LSX group. Canal transportation was significantly more (P < 0.05) in ProTaper group when compared to K3XF and LSX groups. There was no significant difference (P > 0.05) in increase of root canal surface area and canal transportation between continuous rotary and reciprocating rotary techniques for ProTaper Universal, K3XF and LSX groups. Conclusion: LSX rotary system showed minimal increase of root canal surface area and minimal canal transportation when compared to ProTaper and K3XF rotary systems. PMID:27656062

Driver responses to differing urban work zone configurations.

PubMed

Morgan, J F; Duley, A R; Hancock, P A

2010-05-01

This study reports the results of a simulator-based assessment of driver response to two different urban highway work zone configurations. One configuration represented an existing design which was contrasted with a second configuration that presented a reduced taper length prototype work zone design. Twenty-one drivers navigated the two different work zones in two different conditions, one with and one without a lead vehicle; in this case a bus. Measures of driver speed, braking, travel path, and collision frequency were recorded. Drivers navigated significantly closer to the boundary of the work area in the reduced taper length design. This proximity effect was moderated by the significant interaction between lead vehicle and taper length and such interactive effects were also observed for driver speed at the end of the work zone and the number of collisions observed within the work zone itself. These results suggest that reduced taper length poses an increase in risk to both drivers and work zone personnel, primarily when driver anticipation is reduced by foreshortened viewing distances. Increase in such risk is to a degree offset by the reduction of overall exposure to the work zone that a foreshortened taper creates. The benefits and limitations to a simulation-based approach to the assessment and prediction of driver behavior in different work zone configurations are also discussed. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Examination of tapered plastic multimode fiber-based sensor performance with silver coating for different concentrations of calcium hypochlorite by soft computing methodologies--a comparative study.

PubMed

Zakaria, Rozalina; Sheng, Ong Yong; Wern, Kam; Shamshirband, Shahaboddin; Wahab, Ainuddin Wahid Abdul; Petković, Dalibor; Saboohi, Hadi

2014-05-01

A soft methodology study has been applied on tapered plastic multimode sensors. This study basically used tapered plastic multimode fiber [polymethyl methacrylate (PMMA)] optics as a sensor. 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 and 10 mm, respectively. In addition, a tapered PMMA probe, which was coated by silver film, was fabricated and demonstrated using a calcium hypochlorite (G70) solution. The working mechanism of such a device is based on the observation increment in the transmission of the sensor that is immersed in solutions at high concentrations. As the concentration was varied from 0 to 6 ppm, the output voltage of the sensor increased linearly. The silver film coating increased the sensitivity of the proposed sensor because of the effective cladding refractive index, which increases with the coating and thus allows more light to be transmitted from the tapered fiber. In this study, the polynomial and radial basis function (RBF) were applied as the kernel function of the support vector regression (SVR) to estimate and predict the output voltage response of the sensors with and without silver film according to experimental tests. Instead of minimizing the observed training error, SVR_poly and SVR_rbf were used in an attempt to minimize the generalization error bound so as to achieve generalized performance. An adaptive neuro-fuzzy interference system (ANFIS) approach was also investigated for comparison. The experimental results showed that improvements in the predictive accuracy and capacity for generalization can be achieved by the SVR_poly approach in comparison to the SVR_rbf methodology. The same testing errors were found for the SVR_poly approach and the ANFIS approach.

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

PubMed

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.

Do Stem Taper Microgrooves Influence Taper Corrosion in Total Hip Arthroplasty? A Matched Cohort Retrieval Study

PubMed Central

Arnholt, Christina M.; MacDonald, Daniel W.; Underwood, Richard; Guyer, Eric P.; Rimnac, Clare M.; Kurtz, Steven M.; Mont, Michael A.; Klein, Gregg; Lee, Gwo-Chin; Chen, Antonia F.; Hamlin, Brian; Cates, Harold; Malkani, Arthur; Kraay, Matthew

2017-01-01

Background Previous studies identified imprinting of the stem morphology onto the interior head bore, leading researchers to hypothesize an influence of taper topography on mechanically assisted crevice corrosion (MACC). The purpose of this study was to analyze whether micro-grooved stem tapers result in greater fretting corrosion damage than smooth stem tapers. Methods A matched cohort of 120 retrieved head-stem pairs from metal-on-polyethylene bearings was created controlling for implantation time, flexural rigidity, apparent length of engagement, and head size. There were two groups of 60 heads each, mated with either smooth or micro-grooved stem tapers. A high precision roundness machine was used to measure and categorize the surface morphology. Fretting corrosion damage at the head/neck junction was characterized using the Higgs-Goldberg scoring method. Fourteen of the most damaged heads, were analyzed for the maximum depth of material loss and focused ion beam (FIB) cross-sectioned to view oxide and base metal. Results Fretting corrosion damage was not different between the two cohorts at the femoral head (p = 0.14, Mann Whitney) or stem tapers (p = 0.35). There was no difference in the maximum depths of material loss between the cohorts (p = 0.71). Cross sectioning revealed contact damage, signs of micro-motion, and chromium rich oxide layers in both cohorts. Micro-groove imprinting did not appear to have a different effect on the fretting corrosion behavior. Conclusion The results of this matched cohort retrieval study do not support the hypothesis that taper surfaces with micro-grooved stems exhibit increased in vivo fretting corrosion damage or material release. PMID:28111124

Trunnionosis: Does Head Size Affect Fretting and Corrosion in Total Hip Arthroplasty?

PubMed

Del Balso, Christopher; Teeter, Matthew G; Tan, Sok Chuen; Howard, James L; Lanting, Brent A

2016-10-01

Wear and tribocorrosion at the modular head-neck taper interface may be a cause of failure in metal-on-polyethylene total hip arthroplasty (THA). The present investigation endeavored to elucidate the effect of femoral head diameter on fretting and corrosion in retrieved head-neck tapers. A retrieval analysis of THA prostheses in vivo for a minimum of 1 year was performed. Twenty-three femoral heads of 32-mm diameter were matched with 28-mm heads based on time in vivo and head length (-3 mm to +8 mm). All included implants featured a single taper design from a single manufacturer. Fretting and corrosion damage scoring was performed for each implant under stereomicroscopic visualization. Head diameter was observed to affect fretting (P = .01), with 32-mm femoral heads exhibiting greater total fretting scores than 28-mm heads. Fretting damage was greatest (P = .01) in the central concentric zone of the femoral head bore tapers, regardless of head diameter, length, or stem offset. No significant effect on total corrosion scores was observed for any head or stem variable. Retrieved implant total corrosion scores were positively correlated (ρ = 0.51, P < .001) with implantation time. Increased femoral head diameter in THA may produce greater fretting damage owing to and increased head-neck moment arm. There is no associated increase in corrosion with 28-mm and 32-mm heads of this taper design. The longer a THA prosthesis is implanted, the greater the risk of damage due to corrosion. Copyright © 2016 Elsevier Inc. All rights reserved.

Wind-Tunnel Investigation of the Characteristics of Blunt-Nose Ailerons on a Tapered Wing

NASA Technical Reports Server (NTRS)

Toll, Thomas A.

1943-01-01

Characteristics are determined for various modifications of 0.155-chord blunt-nose aileron on semispan model of tapered fighter plane wing. Ailerons with 40 percent nose balance reduced high-speed stick forces. Increased balance chord increases effectiveness and reduces high-speed stick forces. Increased balance chord increases effectiveness and reduces adverse effects of gap at aileron hose. Increase of nose radii increased negative slope of curve hinge-movement coefficient plotted against deflection. Extended deflection range decreased aileron effectiveness for small deflections but increased it at large deflections. Peak pressures at noses of ailerons are relatively high at moderate deflections.

Wind-Tunnel Measurements of Effect of Dive-Recovery Flaps at Transonic Speeds on Models of a Seaplane and a Transport

NASA Technical Reports Server (NTRS)

Heath, Atwood R., Jr.; Ward, Robert J.

1959-01-01

The effects of wing-lower-surface dive-recovery flaps on the aero- dynamic characteristics of a transonic seaplane model and a transonic transport model having 40 deg swept wings have been investigated in the Langley 16-foot transonic tunnel. The seaplane model had a wing with an aspect ratio of 5.26, a taper ratio of 0.333, and NACA 63A series airfoil sections streamwise. The transport model had a wing with an aspect ratio of 8, a taper ratio of 0.3, and NACA 65A series airfoil sections perpendicular to the quarter-chord line. The effects of flap deflection, flap longitudinal location, and flap sweep were generally investigated for both horizontal-tail-on and horizontal-tail-off configurations. Model force and moment measurements were made for model angles of attack from -5 deg to 14 deg in the Mach number range from 0.70 to 1.075 at Reynolds numbers of 2.95 x 10(exp 6) to 4.35 x 10(exp 6). With proper longitudinal location, wing-lower-surface dive-recovery flaps produced lift and pitching-moment increments that increased with flap deflection. For the transport model a flap located aft on the wing proved to be more effective than one located more forward., both flaps having the same span and approximately the same deflection. For the seaplane model a high horizontal tail provided added effectiveness for the deflected-flap configuration.

Temperature sensing through long period fiber gratings mechanically induced on tapered optical fibers.

PubMed

Pulido-Navarro, María Guadalupe; Escamilla-Ambrosio, Ponciano Jorge; Marrujo-García, Sigifredo; Álvarez-Chávez, José Alfredo; Martínez-Piñón, Fernando

2017-07-01

In this work the feasibility of employing two well-known techniques already used on designing optical fiber sensors is explored. The first technique employed involves monomode tapered fibers, which were fabricated using a taper machine designed, built, and implemented in our laboratory. This implementation greatly reduced the costs and fabrication time allowing us to produce the desired taper length and transmission conditions. The second technique used fiber Bragg gratings, which we decided to have mechanically induced and for that reason we devised and produced our own mechanical gratings with the help of a computer numerical control tool. This grating had to be fabricated with aluminum to withstand temperatures of up to 600°C. When light traveling through an optical fiber reaches a taper it couples into the cladding layer and comes back into the core when the taper ends. In the same manner, when the light encounters gratings in the fiber, it couples to the cladding modes, and when the gratings end, the light couples back into the core. For our experimentation, the tapering machine was programmed to fabricate single-mode tapers with 3 cm length, and the mechanically induced gratings characteristics were 5 cm length, and had a period of 500 μm and depth of the period of 300 μm. For the conducting tests, the tapered fiber is positioned in between two aluminum slabs, one grooved and the other plane. These two blocks accomplish the mechanically induced long period grating (LPG); the gratings on the grooved plaque are imprinted on the taper forming the period gratings. An optical spectrum analyzer is used to observe the changes on the transmission spectrum as the temperature varies from 20°C to 600°C. The resultant attenuation peak wavelength in the transmission spectrum shifts up to 8 nm, which is a higher shift compared to what has been reported using nontapered fibers. As the temperature increases there is no longer a shift, but there is significant power loss. Such a characteristic can be used as well for sensing applications.

Functional overreaching: the key to peak performance during the taper?

PubMed

Aubry, Anaël; Hausswirth, Christophe; Louis, Julien; Coutts, Aaron J; LE Meur, Yann

2014-09-01

The purpose of this study is to examine whether performance supercompensation during taper is maximized in endurance athletes after experiencing overreaching during an overload training (OT) period. Thirty-three trained male triathletes were assigned to either OT (n = 23) or normal training groups (n = 10, CTL) during 8 wk. Cycling performance and maximal oxygen uptake (V˙O2max) were measured after 1 wk of moderate training, a 3-wk period of OT, and then each week during 4-wk taper. Eleven of the 23 subjects from the OT group were diagnosed as functionally overreached (F-OR) after the overload period (decreased performance with concomitant high perceived fatigue), whereas the 12 other subjects were only acutely fatigued (AF) (no decrease in performance). According to qualitative statistical analysis, the AF group demonstrated a small to large greater peak performance supercompensation than the F-OR group (2.6% ± 1.1%) and the CTL group (2.6% ± 1.6%). V˙O2max increased significantly from baseline at peak performance only in the CTL and AF groups. Of the peak performances, 60%, 83%, and 73% occurred within the two first weeks of taper in CTL, AF, and OR, respectively. Ten cases of infection were reported during the study with higher prevalence in F-OR (70%) than that in AF (20%) and CTL (10%). This study showed that 1) greater gains in performance and V˙O2max can be achieved when higher training load is prescribed before the taper but not in the presence of F-OR; 2) peak performance is not delayed during taper when heavy training loads are completed immediately prior; and 3) F-OR provides higher risk for training maladaptation, including increased infection risks.

The effects of autoclave sterilization on the cyclic fatigue resistance of ProTaper Universal, ProTaper Next, and ProTaper Gold nickel-titanium instruments

PubMed Central

2017-01-01

Objectives It was aimed to compare the cyclic fatigue resistances of ProTaper Universal (PTU), ProTaper Next (PTN), and ProTaper Gold (PTG) and the effects of sterilization by autoclave on the cyclic fatigue life of nickel-titanium (NiTi) instruments. Materials and Methods Eighty PTU, 80 PTN, and 80 PTG were included to the present study. Files were tested in a simulated canal. Each brand of the NiTi files were divided into 4 subgroups: group 1, as received condition; group 2, pre-sterilized instruments exposed to 10 times sterilization by autoclave; group 3, instruments tested were sterilized after being exposed to 25%, 50%, and 75% of the mean cycles to failure, then cycled fatigue test was performed; group 4, instruments exposed to the same experiment with group 3 without sterilization. The number of cycles to failure (NCF) was calculated. The data was statistically analyzed by using one-way analysis of variance and post hoc Tukey tests. Results PTG showed significantly higher NCF than PTU and PTN in group 1 (p < 0.05). Sterilization significantly increased the NCF of PTN and PTG (p < 0.05) in group 2. PTN in group 3 had significantly higher cyclic fatigue resistance than PTN group 4 (p < 0.05). Also, significantly higher NCF was observed for PTG in group 2 than in groups 3 and 4 (p < 0.05). Conclusions PTG instrument made of new gold alloy was more resistant to fatigue failure than PTN and PTU. Autoclaving increased the cyclic fatigue resistances of PTN and PTG. PMID:29142878

Sanio's laws revisited. Size-dependent changes in the xylem architecture of trees.

PubMed

Mencuccini, Maurizio; Hölttä, Teemu; Petit, Giai; Magnani, Federico

2007-11-01

Early observations led Sanio [Wissen. Bot., 8, (1872) 401] to state that xylem conduit diameters and lengths in a coniferous tree increase from the apex down to a height below which they begin to decrease towards the tree base. Sanio's law of vertical tapering has been repeatedly tested with contradictory results and the debate over the scaling of conduit diameters with distance from the apex has not been settled. The debate has recently acquired new vigour, as an accurate knowledge of the vertical changes in wood anatomy has been shown to be crucial to scaling metabolic properties to plant and ecosystem levels. Contrary to Sanio's hypothesis, a well known model (MST, metabolic scaling theory) assumes that xylem conduits monotonically increase in diameter with distance from the apex following a power law. This has been proposed to explain the three-fourth power scaling between size and metabolism seen across plants. Here, we (i) summarized available data on conduit tapering in trees and (ii) propose a new numerical model that could explain the observed patterns. Data from 101 datasets grouped into 48 independent profiles supported the notions that phylogenetic group (angiosperms versus gymnosperms) and tree size strongly affected the vertical tapering of conduit diameter. For both angiosperms and gymnosperms, within-tree tapering also varied with distance from the apex. The model (based on the concept that optimal conduit tapering occurs when the difference between photosynthetic gains and wall construction costs is maximal) successfully predicted all three major empirical patterns. Our results are consistent with Sanio's law only for large trees and reject the MST assumptions that vertical tapering in conduit diameter is universal and independent of rank number.

Simple taper: Taper equations for the field forester

Treesearch

David R. Larsen

2017-01-01

"Simple taper" is set of linear equations that are based on stem taper rates; the intent is to provide taper equation functionality to field foresters. The equation parameters are two taper rates based on differences in diameter outside bark at two points on a tree. The simple taper equations are statistically equivalent to more complex equations. The linear...

Parabolic tapers for overmoded waveguides

DOEpatents

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.

Optical/Infrared Properties of Atmospheric Aerosols with an In-Situ, Multi-Wavelength, Multichannel Nephelometer System.

DTIC Science & Technology

1985-04-01

from any angle of approach. An angular impetus is imparted to the particle 25 7. motion via the eight evenly spaced entrance vanes. As the particles...measurement cycle. 2 f.. 27 VA NE S M= VANE ASSEMBLY BASE IN SECT SCREEN TUBE PROTECTIVE CPLUGHOUSING HOUSING-DEFLECTORAEOYMIINT SPACING PHAEO YNAI N...AERODYNAMIC FLOW DEFLECTOR OUTER TUJBE TAPERED p. Figure 3 r Wedding PM 1 0 Inlet [I]J 28 . .I .. II | I I J . 1 _1 ! I 7 I ! . ?. . . - 120 -- WEDDING INLET

Optimization of Profile and Material of Abrasive Water Jet Nozzle

NASA Astrophysics Data System (ADS)

Anand Bala Selwin, K. P.; Ramachandran, S.

2017-05-01

The objective of this work is to study the behaviour of the abrasive water jet nozzle with different profiles and materials. Taguchi-Grey relational analysis optimization technique is used to optimize the value with different material and different profiles. Initially the 3D models of the nozzle are modelled with different profiles by changing the tapered inlet angle of the nozzle. The different profile models are analysed with different materials and the results are optimized. The optimized results would give the better result taking wear and machining behaviour of the nozzle.

Spinning Characteristics of Wings III : a Rectangular and Tapered Clark Y Monoplane Wing with Rounded Tips

NASA Technical Reports Server (NTRS)

Bamber, M J; House, R O

1937-01-01

An investigation was made to determine the spinning characteristics of Clark Y monoplane wings with different plan forms. A rectangular wing and a wing tapered 5:2, both with rounded tips, were tested on the N.A.C.A. spinning balance in the 5-foot vertical wind tunnel. The aerodynamic characteristics of the models and a prediction of the angles of sideslip for steady spins are given. Also included is an estimate of the yawning moment that must be furnished by the parts of the airplane to balance the inertia couples and wing yawing moment for spinning equilibrium. The effects on the spin of changes in plan form and of variations of some of the important parameters are discussed and the results are compared with those for a rectangular wing with square tips. It is concluded that for a conventional monoplane using Clark Y wing the sideslip will be algebraically larger for the wing with the rounded tip than for the wing with the square tip and will be largest for the tapered wing. The effect of plan form on the spin will vary with the type of airplane; and the provision of a yawing-moment coefficient of -0.025 (i.e., opposing the spin) by the tail, fuselage, and interference effects will insure against the attainment of equilibrium on a steady spin for any of the plan forms tested and for any of the parameters used in the analysis.

Cyclic fatigue resistance of XP-endo Shaper compared with different nickel-titanium alloy instruments.

PubMed

Elnaghy, Amr; Elsaka, Shaymaa

2018-04-01

The aims of this study were to assess and compare the resistance to cyclic fatigue of XP-endo Shaper (XPS; FKG Dentaire, La Chaux-de-Fonds, Switzerland) instruments with TRUShape (TRS; Dentsply Tulsa Dental Specialties, Tulsa, OK, USA), HyFlex CM (HCM; Coltene, Cuyahoga Falls, OH, USA), Vortex Blue (VB; Dentsply Tulsa Dental Specialties), and iRace (iR; FKG Dentaire) nickel-titanium rotary instruments at body temperature. Size 30, 0.01 taper of XPS, size 30, 0.04 taper of HCM, VB, iR, and size 30, 0.06 taper of TRS instruments were immersed in saline at 37 ± 1 °C during cyclic fatigue testing. The instruments were tested with 60° angle of curvature and a 3-mm radius of curvature. The number of cycles to failure (NCF) was calculated and the length of the fractured segment was measured. Fractographic examination of the fractured surface was performed using a scanning electron microscope. The data were analyzed statistically using Kruskal-Wallis H test and Mann-Whitney U tests. Statistical significance was set at P < 0.05. XPS had a significantly greater NCF compared with the other instruments (P < 0.001). The topographic appearance of the fracture surfaces of tested instruments revealed ductile fracture of cyclic fatigue failure. XPS instruments exhibited greater cyclic fatigue resistance compared with the other tested instruments. XP-endo Shaper instruments could be used more safely in curved canals due to their higher fatigue resistance.

Comparison of arch forms between Egyptian and North American white populations.

PubMed

Bayome, Mohamed; Sameshima, Glenn T; Kim, Yoonji; Nojima, Kunihiko; Baek, Seung-Hak; Kook, Yoon-Ah

2011-03-01

The aim of this study was to evaluate the morphologic differences in the mandibular arches of Egyptian and North American white subjects. The sample included 94 Egyptian subjects (35 Class I, 32 Class II, and 27 Class III) and 92 white subjects (37 Class I, 29 Class II, and 26 Class III). The subjects were grouped according to arch form types (tapered, ovoid, and square) to compare their frequency distribution between ethnic groups in each Angle classification. The most facial portions of 13 proximal contact areas were digitized on scanned images of mandibular casts to estimate the corresponding clinical bracket point for each tooth. Four linear and 2 proportional measurements were taken. In comparing arch dimensions, intermolar width was narrower in Egyptians than in the whites (P = 0.001). There was an even frequency distribution of the 3 arch forms in the Egyptian group. On the other hand, the most frequent arch form was ovoid followed by tapered and square in the white group; the square arch form was significantly less frequent than the tapered and ovoid arch forms (P = 0.029). The arch forms of Egyptians are narrower than those of whites. The distribution of the arch form types in Egyptians showed similar frequency, but the square arch form was less frequent in whites. It is recommended to select narrower archwires from the available variations to suit many Egyptian patients. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

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

PubMed

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.

Piezoelectric energy harvester having planform-tapered interdigitated beams

DOEpatents

Kellogg, Rick A [Tijeras, NM; Sumali, Hartono [Albuquerque, NM

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.

Relay telescope for high power laser alignment system

DOEpatents

Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.

2006-09-19

A laser system includes an optical path having an intracavity relay telescope with a telescope focal point for imaging an output of the gain medium between an image location at or near the gain medium and an image location at or near an output coupler for the laser system. A kinematic mount is provided within a vacuum chamber, and adapted to secure beam baffles near the telescope focal point. An access port on the vacuum chamber is adapted for allowing insertion and removal of the beam baffles. A first baffle formed using an alignment pinhole aperture is used during alignment of the laser system. A second tapered baffle replaces the alignment aperture during operation and acts as a far-field baffle in which off angle beams strike the baffle a grazing angle of incidence, reducing fluence levels at the impact areas.

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

NASA Astrophysics Data System (ADS)

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.

A Rotational and Axial Motion System Load Frame Insert for In Situ High Energy X-Ray Studies (Postprint)

DTIC Science & Technology

2015-09-08

N) without sample slippage. Equally critical is the applied tightening torque of the tapered compression nut in order to provide the necessary...preloaded linear ball spline which enables torque to be transferred to both the upper and lower rotation stages despite the fact that their vertical...interference fit, where a collet and tapered compression nut act to impart increasing pressure on the grip region of the specimen as increasing torque is

[INVITED] Magnetic field vector sensor by a nonadiabatic tapered Hi-Bi fiber and ferrofluid nanoparticles

NASA Astrophysics Data System (ADS)

Layeghi, Azam; Latifi, Hamid

2018-06-01

A magnetic field vector sensor based on super-paramagnetic fluid and tapered Hi-Bi fiber (THB) in fiber loop mirror (FLM) is proposed. A two-dimensional detection of external magnetic field (EMF) is experimentally demonstrated and theoretically simulated by Jones matrix to analyze the physical operation in detail. A birefringence is obtained due to magnetic fluid (MF) in applied EMF. By surrounding the THB with MF, a tunable birefringence of MF affect the transmission of the sensor. Slow and fast axes of this obtained birefringence are determined by the direction of applied EMF. In this way, the transmission response of the sensor is depended on the angle between the EMF orientation and the main axes of polarization maintaining fiber (PMF) in FLM. The wavelength shift and intensity shift versus EMF orientation show a sinusoidal behavior, while the applied EMF is constant. Also, the changes in the intensity of EMF in a certain direction results in wavelength shift in the sensor spectrum. The maximum wavelength sensitivity of 214 pm/mT is observed.

Supercontinuum generation in a tapered tellurite microstructured optical fiber

NASA Astrophysics Data System (ADS)

Yan, X.; Ohishi, Y.

2014-07-01

Supercontinuum generation (SCG) was investigated in tapered tellurite microstructured optical fibers (MOFs) for various taper profiles. We emphasize on the procedure for finding the dispersion profile that achieve the best width of the SC spectra. An enhancement of the SCG is achieved by varying the taper waist diameter along its length in a carefully designed, and an optimal degree of tapering is found to exist for tapers with an axially uniform waist. We also show the XFROG spectrograms of the pulses propagating through different tapered fibers, confirming the optimized taper conditions.

Heat release, time required, and cleaning ability of MTwo R and ProTaper universal retreatment systems in the removal of filling material.

PubMed

Bramante, Clovis Monteiro; Fidelis, Natasha Siqueira; Assumpção, Tatiana Santos; Bernardineli, Norberti; Garcia, Roberto Brandão; Bramante, Alexandre Silva; de Moraes, Ivaldo Gomes

2010-11-01

This ex vivo study evaluated the heat release, time required, and cleaning efficacy of MTwo (VDW, Munich, Germany) and ProTaper Universal Retreatment systems (Dentsply/Maillefer, Ballaigues, Switzerland) and hand instrumentation in the removal of filling material. Sixty single-rooted human teeth with a single straight canal were obturated with gutta-percha and zinc oxide and eugenol-based cement and randomly allocated to 3 groups (n = 20). After 30-day storage at 37 °C and 100% humidity, the root fillings were removed using ProTaper UR, MTwo R, or hand files. Heat release, time required, and cleaning efficacy data were analyzed statistically (analysis of variance and the Tukey test, α = 0.05). None of the techniques removed the root fillings completely. Filling material removal with ProTaper UR was faster but caused more heat release. Mtwo R produced less heat release than the other techniques but was the least efficient in removing gutta-percha/sealer. ProTaper UR and MTwo R caused the greatest and lowest temperature increase on root surface, respectively; regardless of the type of instrument, more heat was released in the cervical third. Pro Taper UR needed less time to remove fillings than MTwo R. All techniques left filling debris in the root canals. Copyright © 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Distribution of smile line, gingival angle and tooth shape among the Saudi Arabian subpopulation and their association with gingival biotype

PubMed Central

AlQahtani, Nabeeh A.; Haralur, Satheesh B.; AlMaqbol, Mohammad; AlMufarrij, Ali Jubran; Al Dera, Ahmed Ali; Al-Qarni, Mohammed

2016-01-01

Objectives: To determine the occurrence of smile line and maxillary tooth shape in the Saudi Arabian subpopulation, and to estimate the association between these parameters with gingival biotype. Materials and Methods: On the fulfillment of selection criteria, total 315 patients belong to Saudi Arabian ethnic group were randomly selected. Two frontal photographs of the patients were acquired. The tooth morphology, gingival angle, and smile line classification were determined with ImageJ image analyzing software. The gingival biotype was assessed by probe transparency method. The obtained data were analyzed with SPSS 19 (IBM Corporation, New York, USA) software to determine the frequency and association between other parameters and gingival biotype. Results: Among the clinical parameters evaluated, the tapering tooth morphology (56.8%), thick gingival biotype (53%), and average smile line (57.5%) was more prevalent. The statistically significant association was found between thick gingival biotype and the square tooth, high smile line. The high gingival angle was associated with thin gingival biotype. Conclusions: The study results indicate the existence of an association between tooth shape, smile line, and gingival angle with gingival biotype. PMID:27195228

Design and cold test of period-tapered double-ridge-loaded folded waveguide slow wave structure for Ka band TWTs

NASA Astrophysics Data System (ADS)

Lu, Zhigang; Su, Zhicheng; Wei, Yanyu

2018-05-01

A double-ridge-loaded folded waveguide (DRL-FW) travelling wave tube (TWT) based on period-tapered structure is proposed. Through analysing the dispersion characteristics of the DRL-FW slow wave structure (SWS), the physical mechanism of the band-edge oscillation is obtained. Period-tapered SWS is proposed and analysed for verifying the feasibility in suppressing upper-band-edge oscillation and increasing the output power. Then the electromagnetic characteristics and the beam-wave interaction of TWT based on the period-tapered DRL-FW SWS are investigated. The calculation results predict that it potentially could provide continuous wave power over 600W from 29 GHz to 32 GHz without upper-band-edge oscillation. The bandwidth expands from 29-31GHz to 29-32GHz and electron efficiency is increased from more than 8.3% to more than 11%, while the range of operating voltage expands from 22kV-22.5kV to 22kV-24kV. The corresponding saturated gain can reach over 36.8 dB. In addition, we have carried out experimental tests on the transmission characteristics of period-tapered DRL-FW SWS. The cold test results show that the voltage stand-wave ratio (VSWR) is below 1.8 in the range of 29-32GHz. Good transmission characteristics greatly reduce the risk of reflection wave oscillation, thus improving the stability of DRL-FW TWT.

Automated touch sensing in the mouse tapered beam test using Raspberry Pi.

PubMed

Ardesch, Dirk Jan; Balbi, Matilde; Murphy, Timothy H

2017-11-01

Rodent models of neurological disease such as stroke are often characterized by motor deficits. One of the tests that are used to assess these motor deficits is the tapered beam test, which provides a sensitive measure of bilateral motor function based on foot faults (slips) made by a rodent traversing a gradually narrowing beam. However, manual frame-by-frame scoring of video recordings is necessary to obtain test results, which is time-consuming and prone to human rater bias. We present a cost-effective method for automated touch sensing in the tapered beam test. Capacitive touch sensors detect foot faults onto the beam through a layer of conductive paint, and results are processed and stored on a Raspberry Pi computer. Automated touch sensing using this method achieved high sensitivity (96.2%) as compared to 'gold standard' manual video scoring. Furthermore, it provided a reliable measure of lateralized motor deficits in mice with unilateral photothrombotic stroke: results indicated an increased number of contralesional foot faults for up to 6days after ischemia. The automated adaptation of the tapered beam test produces results immediately after each trial, without the need for labor-intensive post-hoc video scoring. It also increases objectivity of the data as it requires less experimenter involvement during analysis. Automated touch sensing may provide a useful adaptation to the existing tapered beam test in mice, while the simplicity of the hardware lends itself to potential further adaptations to related behavioral tests. Copyright © 2017 Elsevier B.V. All rights reserved.

Cyclic fatigue resistance of ProTaper Universal instruments when subjected to static and dynamic tests.

PubMed

Lopes, Hélio P; Britto, Izabelle M O; Elias, Carlos N; Machado de Oliveira, Julio C; Neves, Mônica A S; Moreira, Edson J L; Siqueira, José F

2010-09-01

This study evaluated the number of cycles to fracture of ProTaper Universal S2 instruments when subjected to static and dynamic cyclic fatigue tests. ProTaper Universal S2 instruments were used until fracture in an artificial curved canal under rotational speed of 300 rpm in either a static or a dynamic test model. Afterward, the length of the fractured segments was measured and fractured surfaces and helical shafts analyzed by scanning electron microscopy (SEM). The number of cycles to fracture was significantly increased when instruments were tested in the dynamic model (P<.001). Instrument separation occurred at the point of maximum flexure within the artificial canals, i.e., the midpoint of the curved canal segment. SEM analysis revealed that fractured surfaces exhibited characteristics of the ductile mode. Plastic deformation was not observed in the helical shaft of fractured instruments. The number of cycles to fracture ProTaper Universal S2 instruments significantly increased with the use of instruments in a dynamic cyclic fatigue test compared with a static model. These findings reinforce the need for performing continuous pecking motions during rotary instrumentation of curved root canals. Copyright (c) 2010 Mosby, Inc. All rights reserved.

The Influence of Contamination and Cleaning on the Strength of Modular Head Taper Fixation in Total Hip Arthroplasty.

PubMed

Krull, Annika; Morlock, Michael M; Bishop, Nicholas E

2017-10-01

Intraoperative interface contamination of modular head-stem taper junctions of hip implants can lead to poor fixation strength, causing fretting and crevice corrosion or even stem taper fracture. Careful cleaning before assembly should help to reduce these problems. The purpose of this study was to determine the effect of cleaning (with and without drying) contaminated taper interfaces on the taper fixation strength. Metal or ceramic heads were impacted onto titanium alloy stem tapers with cleaned or contaminated (fat or saline solution) interfaces. The same procedure was performed after cleaning and drying the contaminated interfaces. Pull-off force was used to determine the influence of contamination and cleaning on the taper strength. Pull-off forces after contamination with fat were significantly lower than those for uncontaminated interfaces for both head materials. Pull-off forces after application of saline solution were not significantly different from those for uncontaminated tapers. However, a large variation in taper strength was observed, pull-off forces for cleaned and dried tapers were similar to those for uncontaminated tapers for both head materials. Intraoperative contamination of taper interfaces may be difficult to detect but has a major influence on taper fixation strength. Cleaning of the stem taper with saline solution and drying with gauze directly before assembly allows the taper strength of the pristine components to be achieved. Not drying the taper results in a large variation in pull-off forces, emphasizing that drying is essential for sufficient and reproducible fixation strength. Copyright © 2017 Elsevier Inc. All rights reserved.

Design of Friction Stir Welding Tool for Avoiding Root Flaws

PubMed Central

Ji, Shude; Xing, Jingwei; Yue, Yumei; Ma, Yinan; Zhang, Liguo; Gao, Shuangsheng

2013-01-01

In order to improve material flow behavior during friction stir welding and avoid root flaws of weld, a tool with a half-screw pin and a tool with a tapered-flute pin are suggested. The effect of flute geometry in tool pins on material flow velocity is investigated by the software ANSYS FLUENT. Numerical simulation results show that high material flow velocity appears near the rotational tool and material flow velocity rapidly decreases with the increase of distance away from the axis of the tool. Maximum material flow velocity by the tool with the tapered-flute pin appears at the beginning position of flute and the velocity decreases with the increase of flow length in flute. From the view of increasing the flow velocity of material near the bottom of the workpiece or in the middle of workpiece, the tool with the half-screw pin and the tool with the tapered-flute pin are both better than the conventional tool. PMID:28788426

Design of Friction Stir Welding Tool for Avoiding Root Flaws.

PubMed

Ji, Shude; Xing, Jingwei; Yue, Yumei; Ma, Yinan; Zhang, Liguo; Gao, Shuangsheng

2013-12-12

In order to improve material flow behavior during friction stir welding and avoid root flaws of weld, a tool with a half-screw pin and a tool with a tapered-flute pin are suggested. The effect of flute geometry in tool pins on material flow velocity is investigated by the software ANSYS FLUENT. Numerical simulation results show that high material flow velocity appears near the rotational tool and material flow velocity rapidly decreases with the increase of distance away from the axis of the tool. Maximum material flow velocity by the tool with the tapered-flute pin appears at the beginning position of flute and the velocity decreases with the increase of flow length in flute. From the view of increasing the flow velocity of material near the bottom of the workpiece or in the middle of workpiece, the tool with the half-screw pin and the tool with the tapered-flute pin are both better than the conventional tool.

Theoretical axial wall angulation for rotational resistance form in an experimental-fixed partial denture

PubMed Central

2017-01-01

PURPOSE The aim of this study was to determine the influence of long base lengths of a fixed partial denture (FPD) to rotational resistance with variation of vertical wall angulation. MATERIALS AND METHODS Trigonometric calculations were done to determine the maximum wall angle needed to resist rotational displacement of an experimental-FPD model in 2-dimensional plane. The maximum wall angle calculation determines the greatest taper that resists rotation. Two different axes of rotation were used to test this model with five vertical abutment heights of 3-, 3.5-, 4-, 4.5-, and 5-mm. The two rotational axes were located on the mesial-side of the anterior abutment and the distal-side of the posterior abutment. Rotation of the FPD around the anterior axis was counter-clockwise, Posterior-Anterior (P-A) and clockwise, Anterior-Posterior (A-P) around the distal axis in the sagittal plane. RESULTS Low levels of vertical wall taper, ≤ 10-degrees, were needed to resist rotational displacement in all wall height categories; 2–to–6–degrees is generally considered ideal, with 7–to–10–degrees as favorable to the long axis of the abutment. Rotation around both axes demonstrated that two axial walls of the FPD resisted rotational displacement in each direction. In addition, uneven abutment height combinations required the lowest wall angulations to achieve resistance in this study. CONCLUSION The vertical height and angulation of FPD abutments, two rotational axes, and the long base lengths all play a role in FPD resistance form. PMID:28874995

Mechanics of the tapered interference fit in dental implants.

PubMed

Bozkaya, Dinçer; Müftü, Sinan

2003-11-01

In evaluation of the long-term success of a dental implant, the reliability and the stability of the implant-abutment interface plays a great role. Tapered interference fits provide a reliable connection method between the abutment and the implant. In this work, the mechanics of the tapered interference fits were analyzed using a closed-form formula and the finite element (FE) method. An analytical solution, which is used to predict the contact pressure in a straight interference, was modified to predict the contact pressure in the tapered implant-abutment interface. Elastic-plastic FE analysis was used to simulate the implant and abutment material behavior. The validity and the applicability of the analytical solution were investigated by comparisons with the FE model for a range of problem parameters. It was shown that the analytical solution could be used to determine the pull-out force and loosening-torque with 5-10% error. Detailed analysis of the stress distribution due to tapered interference fit, in a commercially available, abutment-implant system was carried out. This analysis shows that plastic deformation in the implant limits the increase in the pull-out force that would have been otherwise predicted by higher interference values.

White light supercontinuum generation in a Y-shaped microstructured tapered fiber pumped at 1064 nm.

PubMed

Cascante-Vindas, J; Díez, A; Cruz, J L; Andrés, M V

2010-07-05

We report the generation of supercontinuum in a Ge-doped Y-shape tapered fiber pumped at 1064 nm in the ns pump regime. The taper was designed to have long taper transitions and a taper waist with a core diameter of 0.9 mum. The large air-filling fraction and diameter of the air-hole microstructure reduces the confinement loss at long wavelengths so, enabling the extension of the spectrum to longer wavelengths. Along the taper transition the zero-dispersion wavelength decreases as the diameter of the taper becomes smaller. The spectral components generated along the taper transition pump the taper waist, enhancing the generation of short wavelengths. A flat spectrum spanning from 420 nm to 1850 nm is reported.

A Wind-Tunnel Investigation of a Transonic-Transport Configuration Utilizing Drag-Reducing Devices at Mach Numbers from 0.20 to 1.03

NASA Technical Reports Server (NTRS)

Loving, Donald L.

1961-01-01

The static longitudinal stability and control and lateral characteristics of a transonic-transport model, incorporating recent drag-reducing devices, has been investigated in the Langley 8-foot transonic pressure tunnel. The wing was cambered, had a thickened root and a taper ratio of 0.3. Wing sweepback angles of 45 degrees and 40 degrees were investigated with corresponding aspect ratios of 7 and 8, respectively. Modifications to the model for reducing the drag were: a forward fuselage addition and special bodies (four big enough to house jet engines) added to the upper surface of the wing. Other components and changes investigated included an empennage, a wing-tip body, wing fences, wing trailing-edge flaps, horizontal-tail settings, and wing dihedral angle. The investigation covered the Mach number range from 0.20 to 1.03 for the angle-of-attack range from -5 degrees to 15.4 degrees, and a sideslip angle of -5 degrees, in the Reynolds number range from 0.52 times 10(exp 6) to 1.94 times 10(exp 6) based on the wing mean aerodynamic chord. The various fuselage and wing additions delayed the drag-rise Mach number and greatly reduced the drag beyond the drag rise. The wing bodies markedly alleviated unstable pitch tendencies throughout the test Mach number range. At low landing speeds, the wing bodies exhibited little interference with the ability of trailing-edge flaps to increase the lift near maximum lift coefficient; and the use of fences greatly reduced the severe longitudinal instability trend at landing attitudes. The model with a 6 degree dihedral angle exhibited positive lateral and directional stability characteristics in the presence of the fuselage and wing additions. An increase in drag-rise Mach number associated with the fuselage and wing additions on the 40 degree sweptback wing combination was similar to that for the comparable 45 degree combination. These additions did, however, reduce the drag of the 40 degree sweptback configurations more than the 45 degree configurations in the transonic speed range.

High power tapered lasers with optimized photonic crystal structure for low divergence and high efficiency

NASA Astrophysics Data System (ADS)

Ma, Xiaolong; Qu, Hongwei; Qi, Aiyi; Zhou, Xuyan; Ma, Pijie; Liu, Anjin; Zheng, Wanhua

2018-04-01

High power tapered lasers are designed and fabricated. A one-dimensional photonic crystal structure in the vertical direction is adopted to narrow the far field divergence. The thickness of the defect layer and the photonic crystal layers are optimized by analyzing the optical field theoretically. For tapered lasers, the continuous-wave power is 7.3 W and the pulsed power is 17 W. A maximum wall-plug efficiency of 46% under continuous-wave operation and 49.3% in pulsed mode are obtained. The beam divergences are around 11° and 6° for the vertical and lateral directions, respectively. High beam qualities are also obtained with a vertical M2 value of 1.78 and a lateral M2 value of 1.62. As the current increases, the lateral M2 value increases gradually while the vertical M2 value remains around 2.

Corrugated metal-coated tapered tip for scanning near-field optical microscope.

PubMed

Antosiewicz, Tomasz J; Szoplik, Tomasz

2007-08-20

This paper addresses an important issue of light throughput of a metal-coated tapered tip for scanning near-field microscope (SNOM). Corrugations of the interface between the fiber core and metal coating in the form of parallel grooves of different profiles etched in the core considerably increase the energy throughput. In 2D FDTD simulations in the Cartesian coordinates we calculate near-field light emitted from such tips. For a certain wavelength range total intensity of forward emission from the corrugated tip is 10 times stronger than that from a classical tapered tip. When realized in practice the idea of corrugated tip may lead up to twice better resolution of SNOM.

Numerical modelling of physical processes in a ballistic laboratory setup with a tapered adapter and plastic piston used for obtaining high muzzle velocities

NASA Astrophysics Data System (ADS)

Bykov, N. V.

2014-12-01

Numerical modelling of a ballistic setup with a tapered adapter and plastic piston is considered. The processes in the firing chamber are described within the framework of quasi- one-dimensional gas dynamics and a geometrical law of propellant burn by means of Lagrangian mass coordinates. The deformable piston is considered to be an ideal liquid with specific equations of state. The numerical solution is obtained by means of a modified explicit von Neumann scheme. The calculation results given show that the ballistic setup with a tapered adapter and plastic piston produces increased shell muzzle velocities by a factor of more than 1.5-2.

[Deformation evaluation of ProTaper nickel-titanium rotary instruments in curved canals instrumentation in vitro].

PubMed

Yan, Hong; Ren, Min; Yin, Xing-Zhe; Zhao, Shu-Yan; Zhang, Cheng-Fei

2008-04-01

To evaluate the deformation of ProTaper rotary instruments using in root canals of different curvature in vitro. Extracted first mandibular molars were divided into two experimental groups according to the curvature of mesial buccal canals: group A with moderate curvature and group B with severe curvature. Only the mesial buccal canals of all these teeth were prepared with 6 sets of new ProTaper rotary instruments individually. Additionally, the control group was established with a set of new ProTaper rotary instruments. After finishing each canal preparation, the instruments accompanied by control were examined under the stereomicroscope by an inspector without knowing the group. If distortion, unwinding, abrasion or fracture occurred within one set of instruments, then the whole set was disposed. The sets without problems were in use until 30 times. After 5, 10, 20 times canal preparation, S1, F1 files without deformation under stereomicroscope were examined under scanning electron microscope (SEM). Deformation of ProTaper rotary instruments happened after 12 times in group A and after 7 times in group B. In these two experimental groups, microcracks were found increasing with the times of use under SEM in the instruments without deformation under stereomicroscope. The microcracks on tip of instruments were deep in the early use and became smoother after 10 times. Similar changes happened on knife-edge of instruments, and the microcracks extended over the edge after 20 times use. Root canals with severe curvature tend to damage ProTaper rotary instruments more frequently than moderately curved canals. ProTaper rotary instruments are appropriate to treat less than 7 root canals with severe curvature or 12 root canals with moderate curvature. Stereomicroscope is recommended to detect early damages on Ni-Ti rotary instruments, for preventing instruments fracture in clinic.

Potential relationship between design of nickel-titanium rotary instruments and vertical root fracture.

PubMed

Kim, Hyeon-Cheol; Lee, Min-Ho; Yum, Jiwan; Versluis, Antheunis; Lee, Chan-Joo; Kim, Byung-Min

2010-07-01

Nickel-titanium (NiTi) rotary files can produce cleanly tapered canal shapes with low tendency of transporting the canal lumen. Because NiTi instruments are generally perceived to have high fracture risk during use, new designs have been marketed to lower fracture risks. However, these design variations may also alter the forces on a root during instrumentation and increase dentinal defects that predispose a root to fracture. This study compared the stress conditions during rotary instrumentation in a curved root for three NiTi file designs. Stresses were calculated using finite element (FE) analysis. FE models of ProFile (Dentsply Maillefer, Ballaigues, Switzerland; U-shaped cross-section and constant 6% tapered shaft), ProTaper Universal (Dentsply; convex triangular cross-section with notch and progressive taper shaft), and LightSpeed LSX (Lightspeed Technology, Inc, San Antonio, TX; noncutting round shaft) were rotated within a curved root canal. The stress and strain conditions resulting from the simulated shaping action were evaluated in the apical root dentin. ProTaper Universal induced the highest von Mises stress concentration in the root dentin and had the highest tensile and compressive principal strain components at the external root surface. The calculated stress values from ProTaper Universal, which had the biggest taper shaft, approached the strength properties of dentin. LightSpeed generated the lowest stresses. The stiffer file designs generated higher stress concentrations in the apical root dentin during shaping of the curved canal, which raises the risk of dentinal defects that may lead to apical root cracking. Thus, stress levels during shaping and fracture susceptibility after shaping vary with instrument design. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Simple fabrication of antireflective silicon subwavelength structure with self-cleaning properties.

PubMed

Kim, Bo-Soon; Ju, Won-Ki; Lee, Min-Woo; Lee, Cheon; Lee, Seung-Gol; Beom-Hoan, O

2013-05-01

A subwavelength structure (SWS) was formed via a simple chemical wet etching using a gold (Au) catalyst. Single nano-sized Au particles were fabricated by metallic self-aggregation. The deposition and thermal annealing of the thin metallic film were carried out. Thermal annealing of a thin metallic film enables the creation of metal nano particles by isolating them from each other by means of the self-aggregation of the metal. After annealing, the samples were soaked in an aqueous etching solution of hydrofluoric acid and hydrogen peroxide. When silicon (Si) was etched for 2 minutes using the Au nano particles, the reflectance was decreased almost 0% over the entire wavelength range from 300 to 1300 nm due to its deep and steeply double tapered structure. When given varying incident angle degrees from 30 degrees to 60 degrees, the reflectance was also maintained at less than 3%. Following this, the etched silicon was treated with a plasma-polymerized fluorocarbon (PPFC) film of about 5 nm using an ICP reactor for surface modification. The result of this surface treatment, the contact angle increased significantly from 27.5 degrees to 139.3 degrees. The surface modification was successful and maintained almost 0% reflectance because of the thin film deposition.

[Mechanical properties of nickel-titanium files following multiple heat sterilizations].

PubMed

Testarelli, L; Gallottini, L; Gambarini, G

2003-04-01

The effect of cycles of sterilization procedures on nickel-titanium (NiTi) endodontic instruments is a serious concern for practitioners. There is no agreement in the literature whether these procedures could adversely affect the mechanical properties of endodontic files, and, consequently, increase the risk of intracanal failure. The purpose of this study was to evaluate the mechanichal resistance of Hero (MicroMega, Besancon, France) instruments, before and after sterilization procedures. Thirty 02, 04, 06 tapered Hero size 30 new instruments were chosen and divided into 3 groups. Group A (control) were tested according to ANSI/ADA Spec.no 28 for torsional resistance, angle of torque and angle at breakage (45 inverted exclamation mark ). Group B files were first sterilized with chemiclave for 10 cycles of 20 minutes at 124 inverted exclamation mark C and then tested as described above. Group C files were first sterilized with glass beads for 10 cycles of 20 sec. at 250 inverted exclamation mark C and then tested as described above. Data were collected and statistically analyzed (t-paired test). Differences among the 3 groups were statistically not significant for both tests. All data were well within Spec.no 28 standard values. From the results of the present study, we may conclude that repeated sterilization procedures do not adversely affect the mechanichal resistance of Hero files.

Physical constraints, fundamental limits, and optimal locus of operating points for an inverted pendulum based actuated dynamic walker.

PubMed

Patnaik, Lalit; Umanand, Loganathan

2015-10-26

The inverted pendulum is a popular model for describing bipedal dynamic walking. The operating point of the walker can be specified by the combination of initial mid-stance velocity (v0) and step angle (φm) chosen for a given walk. In this paper, using basic mechanics, a framework of physical constraints that limit the choice of operating points is proposed. The constraint lines thus obtained delimit the allowable region of operation of the walker in the v0-φm plane. A given average forward velocity vx,avg can be achieved by several combinations of v0 and φm. Only one of these combinations results in the minimum mechanical power consumption and can be considered the optimum operating point for the given vx,avg. This paper proposes a method for obtaining this optimal operating point based on tangency of the power and velocity contours. Putting together all such operating points for various vx,avg, a family of optimum operating points, called the optimal locus, is obtained. For the energy loss and internal energy models chosen, the optimal locus obtained has a largely constant step angle with increasing speed but tapers off at non-dimensional speeds close to unity.

[Shaping ability of multi-taper nickel-titanium files in simulated resin curved root canal].

PubMed

Luo, Hong-Xia; Huang, Ding-Ming; Jia, Liu-He; Luo, Shi-Gao; Gao, Xiao-Jie; Tan, Hong; Zhou, Xue-Dong

2006-08-01

To compare the shaping ability of ISO standard stainless steel K files and multi-taper ProTaper nickel-titanium files in simulated resin curved root canals. METHODS Thirty simulated resin root canals were randomly divided into three groups and prepared by stainless steel K files, hand ProTaper, rotary ProTaper, respectively. The amount of material removed from inner and outer wall and canal width after canal preparation was measured, while the canal curvature before and after canal preparation and canals aberrations were recorded. The stainless steel K files removed more material than hand ProTaper and rotary ProTaper at the outer side of apex and inner side of curvature (P < 0.05). The mean degree of straightening in stainless steel K files group was significantly bigger than in ProTaper group (P < 0.05). The canals prepared by ProTaper had no evident aberration. The shaping ability of ProTaper is better than stainless steel K files.

Data and performances of selected aircraft and rotorcraft

NASA Astrophysics Data System (ADS)

Filippone, Antonio

2000-11-01

The purpose of this article is to provide a synthetic and comparative view of selected aircraft and rotorcraft (nearly 300 of them) from past and present. We report geometric characteristics of wings (wing span, areas, aspect-ratios, sweep angles, dihedral/anhedral angles, thickness ratios at root and tips, taper ratios) and rotor blades (type of rotor, diameter, number of blades, solidity, rpm, tip Mach numbers); aerodynamic data (drag coefficients at zero lift, cruise and maximum absolute glide ratio); performances (wing and disk loadings, maximum absolute Mach number, cruise Mach number, service ceiling, rate of climb, centrifugal acceleration limits, maximum take-off weight, maximum payload, thrust-to-weight ratios). There are additional data on wing types, high-lift devices, noise levels at take-off and landing. The data are presented on tables for each aircraft class. A graphic analysis offers a comparative look at all types of data. Accuracy levels are provided wherever available.

Fiber-optic evanescent-field sensor for attitude measurement

NASA Astrophysics Data System (ADS)

Liu, Yun; Chen, Shimeng; Liu, Zigeng; Guang, Jianye; Peng, Wei

2017-11-01

We proposed a new approach to attitude measurement by an evanescent field-based optical fiber sensing device and demonstrated a liquid pendulum. The device consisted of three fiber-optic evanescent-filed sensors which were fabricated by tapered single mode fibers and immersed in liquid. Three fiber Bragg gratings were used to measure the changes in evanescent field. And their reflection peaks were monitored in real time as measurement signals. Because every set of reflection responses corresponded to a unique attitude, the attitude of the device could be measured by the three fiber-optic evanescent-filed sensors. After theoretical analysis, computerized simulation and experimental verification, regular responses were obtained using this device for attitude measurement. The measurement ranges of dihedral angle and direction angle were 0°-50° and 0°-360°. The device is based on cost-effective power-referenced scheme. It can be used in electromagnetic or nuclear radiation environment.

Integrally formed radio frequency quadrupole

DOEpatents

Abbott, Steven R.

1989-01-01

An improved radio frequency quadrupole (10) is provided having an elongate housing (11) with an elongate central axis (12) and top, bottom and two side walls (13a-d) symmetrically disposed about the axis, and vanes (14a-d) formed integrally with the walls (13a-d), the vanes (14a-d) each having a cross-section at right angles to the central axis (12) which tapers inwardly toward the axis to form electrode tips (15a-d) spaced from each other by predetermined distances. Each of the four walls (13a-d), and the vanes (14a-d) integral therewith, is a separate structural element having a central lengthwise plane (16) passing through the tip of the vane, the walls (13a-d) having flat mounting surfaces (17, 18) at right angles to and parallel to the control plane (16), respectively, which are butted together to position the walls and vane tips relative to each other.

Relay telescope including baffle, and high power laser amplifier utilizing the same

DOEpatents

Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.

2006-09-19

A laser system includes an optical path having an intracavity relay telescope with a telescope focal point for imaging an output of the gain medium between an image location at or near the gain medium and an image location at or near an output coupler for the laser system. A kinematic mount is provided within a vacuum chamber, and adapted to secure beam baffles near the telescope focal point. An access port on the vacuum chamber is adapted for allowing insertion and removal of the beam baffles. A first baffle formed using an alignment pinhole aperture is used during alignment of the laser system. A second tapered baffle replaces the alignment aperture during operation and acts as a far-field baffle in which off angle beams strike the baffle a grazing angle of incidence, reducing fluence levels at the impact areas.

Membrane voltage changes in passive dendritic trees: a tapering equivalent cylinder model.

PubMed

Poznański, R R

1988-01-01

An exponentially tapering equivalent cylinder model is employed in order to approximate the loss of the dendritic trunk parameter observed from anatomical data on apical and basilar dendrites of CA1 and CA3 hippocampal pyramidal neurons. This model allows dendritic trees with a relative paucity of branching to be treated. In particular, terminal branches are not required to end at the same electrotonic distance. The Laplace transform method is used to obtain analytic expressions for the Green's function corresponding to an instantaneous pulse of current injected at a single point along a tapering equivalent cylinder with sealed ends. The time course of the voltage in response to an arbitrary input is computed using the Green's function in a convolution integral. Examples of current input considered are (1) an infinitesimally brief (Dirac delta function) pulse and (2) a step pulse. It is demonstrated that inputs located on a tapering equivalent cylinder are more effective at the soma than identically placed inputs on a nontapering equivalent cylinder. Asymptotic solutions are derived to enable the voltage response behaviour over both relatively short and long time periods to be analysed. Semilogarithmic plots of these solutions provide a basis for estimating the membrane time constant tau m from experimental transients. Transient voltage decrement from a clamped soma reveals that tapering tends to reduce the error associated with inadequate voltage clamping of the dendritic membrane. A formula is derived which shows that tapering tends to increase the estimate of the electrotonic length parameter L.

Simulation and experimental validation of droplet dynamics in microchannels of PEM fuel cells

NASA Astrophysics Data System (ADS)

Ashrafi, Moosa; Shams, Mehrzad; Bozorgnezhad, Ali; Ahmadi, Goodarz

2016-12-01

In this study, dynamics of droplets in the channels of proton exchange membrane fuel cells with straight and serpentine flow-fields was investigated. Tapered and filleted channels were suggested for the straight and serpentine flow-fields respectively in order to improve water removal in channels. Surface tension and wall adhesion forces were applied by using the volume of fluid method. The hydrophilic walls and hydrophobic gas diffusion layer were considered. The mechanism of droplets movement with different diameters was studied by using the Weber and capillary numbers in simple and tapered straight channels. It was illustrated that the flooding was reduced in tapered channel due to increase of water removal rate, and available reaction sites improved subsequently. In addition, film flow was formed in the tapered channel more than the simple channel, so pressure fluctuation was decreased in the tapered channel. Moreover, the water coverage ratio of hydrophilic tapered surface was more than the simple channel, which enhanced water removal from the channel. The filleted serpentine channel was introduced to improve water removal from the simple serpentine channel. It was shown by observation of the unsteady and time-averaged two-phase pressure drop that in the filleted serpentine channels, the two-phase pressure drop was far less than the simple serpentine channel, and also the accumulation of water droplets in the elbows was less leading to lower pressure fluctuation. The numerical simulation results were validated by experiments.

Fatigue testing of metric bolts fitted with lip-type nuts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dragoni, E.

This paper addresses the effect of the external shape of lip-type nuts on the fatigue strength of commercial M10 bolts loaded in tension. Evolving from the standard configuration, six nut geometries are compared, characterized by lips of different shape (cylindrical, tapered or both) and length. Testing and statistical treatment of the data are performed in accordance with a JSME standard involving 14 specimens for each geometry. Within the class of merely cylindrical lips, only limited advantages over the standard assembly are detected. In particular, the bolt strength remains mostly unaffected by lengthening of the lip beyond one third of themore » nut height. Conversely, tapering of the lip end so as to thin its wall around the entry section of the bolt results in substantial improvements. In this case, the strength increase is roughly proportional to the taper length. Adoption of a tapered lip covering two thirds of the nut height enhances the bolt strength by about one fourth with respect to the standard geometry.« less

Fabrication and characterization of a nanometer-sized optical fiber electrode based on selective chemical etching for scanning electrochemical/optical microscopy.

PubMed

Maruyama, Kenichi; Ohkawa, Hiroyuki; Ogawa, Sho; Ueda, Akio; Niwa, Osamu; Suzuki, Koji

2006-03-15

We have already reported a method for fabricating ultramicroelectrodes (Suzuki, K. JP Patent, 2004-45394, 2004). This method is based on the selective chemical etching of optical fibers. In this work, we undertake a detailed investigation involving a combination of etched optical fibers with various types of tapered tip (protruding-shape, double- (or pencil-) shape and triple-tapered electrode) and insulation with electrophoretic paint. Our goal is to establish a method for fabricating nanometer-sized optical fiber electrodes with high reproducibility. As a result, we realized pencil-shaped and triple-tapered electrodes that had radii in the nanometer range with high reproducibility. These nanometer-sized electrodes showed well-defined sigmoidal curves and stable diffusion-limited responses with cyclic voltammetry. The pencil-shaped optical fiber, which has a conical tip with a cone angle of 20 degrees , was effective for controlling the electrode radius. The pencil-shaped electrodes had higher reproducibility and smaller electrode radii (r(app) < 1.0 nm) than those of other etched optical fiber electrodes. By using a pencil-shaped electrode with a 105-nm radius as a probe, we obtained simultaneous electrochemical and optical images of an implantable interdigitated array electrode. We achieved nanometer-scale resolution with a combination of scanning electrochemical microscopy SECM and optical microscopy. The resolution of the electrochemical and optical images indicated sizes of 300 and 930 nm, respectively. The neurites of living PC12 cells were also successfully imaged on a 1.6-microm scale by using the negative feedback mode of an SECM.

Forearc Basin Stratigraphy and Interactions With Accretionary Wedge Growth According to the Critical Taper Concept

NASA Astrophysics Data System (ADS)

Noda, Atsushi

2018-03-01

Forearc basins are important constituents of sediment traps along subduction zones; the basin stratigraphy records various events that the basin experienced. Although the linkage between basin formation and accretionary wedge growth suggests that mass balance exerts a key control on their evolution, the interaction processes between basin and basement remain poorly understood. This study performed 2-D numerical simulations in which basin stratigraphy was controlled by changes in sediment fluxes with accretionary wedge growth according to the critical taper concept. The resultant stratigraphy depended on the degree of filling (i.e., whether the basin was underfilled or overfilled) and the volume balance between the sediment flux supplied to the basin from the hinterland and the accommodation space in the basin. The trenchward progradation of deposition with onlapping contacts on the trenchside basin floor occurred during the underfilled phase, which formed a wedge-shaped sedimentary unit. In contrast, the landward migration of the depocenter, with the tilting of strata, was characteristic for the overfilled phase. Condensed sections marked stratigraphic boundaries, indicating when sediment supply or accommodation space was limited. The accommodation-limited intervals could have formed during the end of wedge uplift or when the taper angle decreased and possibly associated with the development of submarine canyons as conduits for bypassing sediments from the hinterland. Variations in sediment fluxes and their balance exerted a strong influence on the stratigraphic patterns in forearc basins. Assessing basin stratigraphy could be a key to evaluating how subduction zones evolve through their interactions with changing surface processes.

[Continuous observation of canal aberrations in S-shaped simulated root canal prepared by hand-used ProTaper files].

PubMed

Xia, Ling-yun; Leng, Wei-dong; Mao, Min; Yang, Guo-biao; Xiang, Yong-gang; Chen, Xin-mei

2009-08-01

To observe the formation of canal aberrations in S-shaped root canals prepared by every file of hand-used ProTaper. Fifteen S-shaped simulated resin root canals were selected. Each root canal was prepared by every file of hand-used ProTaper following the manufacturer instruction. The images of canals prepared by S1, S2, F1, F2 and F3 were taken and stored, which were divided into group S1, S2, F1, F2 and F3. One image of canal unprepared was superposed with the images of the same root canal in these five groups respectively to observe the types and number of canal aberrations, which included unprepared area, danger zone, ledge, elbow, zip and perforation. SPSS12.0 software pakage was used for Fisher's exact probabilities in 2x2 table. Unprepared area decreased following preparation by every file of ProTaper, but it still existed when the canal preparation was finished. The incidence of danger zone, elbow and zip in group F1 was 15/15, 11/15, 4/15, respectively, which was significantly higher than that in group S2(2/15,0,0) (P<0.001). Ledge appeared after prepared by F2, and increased sharply in group F3. None perforation was found in all groups. The incidence of canal aberrations begins to increase after prepared by finishing files of ProTaper.The presence of unprepared area suggests that it is essential to rinse canal abundantly during complicated canal preparation and canal antisepsis after preparation.

Coherent beam combining architectures for high power tapered laser arrays

NASA Astrophysics Data System (ADS)

Schimmel, G.; Janicot, S.; Hanna, M.; Decker, J.; Crump, P.; Erbert, G.; Witte, U.; Traub, M.; Georges, P.; Lucas-Leclin, G.

2017-02-01

Coherent beam combining (CBC) aims at increasing the spatial brightness of lasers. It consists in maintaining a constant phase relationship between different emitters, in order to combine them constructively in one single beam. We have investigated the CBC of an array of five individually-addressable high-power tapered laser diodes at λ = 976 nm, in two architectures: the first one utilizes the self-organization of the lasers in an interferometric extended-cavity, which ensures their mutual coherence; the second one relies on the injection of the emitters by a single-frequency laser diode. In both cases, the coherent combining of the phase-locked beams is ensured on the front side of the array by a transmission diffractive grating with 98% efficiency. The passive phase-locking of the laser bar is obtained up to 5 A (per emitter). An optimization algorithm is implemented to find the proper currents in the five ridge sections that ensured the maximum combined power on the front side. Under these conditions we achieve a maximum combined power of 7.5 W. In the active MOPA configuration, we can increase the currents in the tapered sections up to 6 A and get a combined power of 11.5 W, corresponding to a combining efficiency of 76%. It is limited by the beam quality of the tapered emitters and by fast phase fluctuations between emitters. Still, these results confirm the potential of CBC approaches with tapered lasers to provide a high-power and high-brightness beam, and compare with the current state-of-the-art with laser diodes.

Nonlinear analysis of aortic flow in living dogs.

NASA Technical Reports Server (NTRS)

Ling, S. C.; Atabek, H. B.; Letzing, W. G.; Patel, D. J.

1973-01-01

A nonlinear theory which considered the convective accelerations of blood and the nonlinear elastic behavior and taper angle of the vascular wall was used to study the nature of blood flow in the descending thoracic aorta of living dogs under a wide range of pressures and flows. Velocity profiles, wall friction, and discharge waves were predicted from locally measured input data about the pressure-gradient wave and arterial distention. The results indicated that a major part of the mean pressure gradient was balanced by convective accelerations; the theory, which took this factor into account, predicted the correct velocity distributions and flow waves.

Influence of axial movement on fatigue of ProFile Ni-Ti rotary instruments: an in vitro evaluation.

PubMed

Avoaka, Marie-Chantal; Haïkel, Youssef

2010-05-01

The aim of this study was to evaluate the influence of the axial movement and the angle of curve (in degrees) on fatigue of nickel-titanium (Ni-Ti) ProFile rotary endodontic instruments. Ni-Ti ProFile rotary instruments (Maillefer SA, Ballaigues, Switzerland), 25 mm long in the range of ISO size 15 to 40 with two tapers (0.4 and 0.6) were evaluated. They are divided in two groups: the instruments with axial movement and those without axial movement. The system used to test the fatigue is maintained in mechanical conditions as close as possible to the clinical situation. The axial movement is in the order of 2 mm in corono-apical direction with a frequency of 1 Hz. The concave radii incorporating a notched V-form for guiding the instruments were: 5; 7,5 and 10 mm. The rotary system is mounted on an electric handpiece and rotated at 350 rpm speed as recommended by the manufacturers. The instruments are rotated until their separation, and the time, in seconds, is recorded. Statistical evaluation is undertaken using a two-way t-test to identify significant differences between variables in the study (p <0.05). We found significant statistical difference (p<0.05) between Ni-Ti engine drive ProFile instruments incorporating an axial movement and the instruments without axial movement with the same radius of curvature, size and taper.The incorporation of the axial movement increases significantly the life-span of the ProFile rotary instruments. This should reduce the risk of the instrument separation during the endodontic treatment.

Experimental Investigation of Superradiance in a Tapered Free-Electron Laser Amplifier

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hidaka, Y.; She, Y.; Murphy, J.B.

2011-03-28

We report experimental studies of the effect of undulator tapering on superradiance in a single-pass high-gain free-electron laser (FEL) amplifier. The experiments were performed at the Source Development Laboratory (SDL) of National Synchrotron Light Source (NSLS). Efficiency was nearly tripled with tapering. Both the temporal and spectral properties of the superradiant FEL along the uniform and tapered undulator were experimentally characterized using frequency-resolved optical gating (FROG) images. Numerical studies predicted pulse broadening and spectral cleaning by undulator tapering Pulse broadening was experimentally verified. However, spectral cleanliness degraded with tapering. We have performed first experiments with a tapered undulator and amore » short seed laser pulse. Pulse broadening with tapering expected from simulations was experimentally confirmed. However, the experimentally obtained spectra degraded with tapering, whereas the simulations predicted improvement. A further numerical study is under way to resolve this issue.« less

Where science meets practice: Olympic coaches' crafting of the tapering process.

PubMed

Ritchie, Darren; Allen, Justine B; Kirkland, Andrew

2018-05-01

Although there is research providing physiologically-based guidance for the content of the taper, this study was the first to examine how coaches actually implement the taper. The purpose of this study was to examine the taper planning and implementation processes of successful Olympic coaches leading up to major competitions and how they learned about tapering. Seven track and field coaches participated in semi-structured interviews exploring their tapering processes. To be considered for inclusion, coaches were required to have coached one or more athletes to an Olympic or Paralympic medal. Through a process of axial and open coding interview transcripts were analysed and lower and higher order themes developed describing the coaches' tapering processes. Our findings indicate that the strategies employed to achieve the desired physiological adaptions of the taper were consistent with research (e.g., reduction in volume whilst maintaining intensity and frequency). However, our findings also suggest that tapering is far from a straight forward "textbook" process. The taper was not restricted to physiological outcomes with coaches considering athletes' psychological as well as physical state. Coaches also involved the athlete in the process, adapted the taper to the athlete, continually monitored its progress, and adapted it further as required.

Interventional MRI: tapering improves the distal sensitivity of the loopless antenna.

PubMed

Qian, Di; El-Sharkawy, AbdEl-Monem M; Atalar, Ergin; Bottomley, Paul A

2010-03-01

The "loopless antenna" is an interventional MRI detector consisting of a tuned coaxial cable and an extended inner conductor or "whip". A limitation is the poor sensitivity afforded at, and immediately proximal to, its distal end, which is exacerbated by the extended whip length when the whip is uniformly insulated. It is shown here that tapered insulation dramatically improves the distal sensitivity of the loopless antenna by pushing the current sensitivity toward the tip. The absolute signal-to-noise ratio is numerically computed by the electromagnetic method-of-moments for three resonant 3-T antennae with no insulation, uniform insulation, and with linearly tapered insulation. The analysis shows that tapered insulation provides an approximately 400% increase in signal-to-noise ratio in trans-axial planes 1 cm from the tip and a 16-fold increase in the sensitive area as compared to an equivalent, uniformly insulated antenna. These findings are directly confirmed by phantom experiments and by MRI of an aorta specimen. The results demonstrate that numerical electromagnetic signal-to-noise ratio analysis can accurately predict the loopless detector's signal-to-noise ratio and play a central role in optimizing its design. The manifold improvement in distal signal-to-noise ratio afforded by redistributing the insulation should improve the loopless antenna's utility for interventional MRI. (c) 2010 Wiley-Liss, Inc.

Criteria for Seismic Splay Fault Activation During Subduction Earthquakes

NASA Astrophysics Data System (ADS)

Dedontney, N.; Templeton, E.; Bhat, H.; Dmowska, R.; Rice, J. R.

2008-12-01

As sediment is added to the accretionary prism or removed from the forearc, the material overlying the plate interface must deform to maintain a wedge structure. One of the ways this internal deformation is achieved is by slip on splay faults branching from the main detachment, which are possibly activated as part of a major seismic event. As a rupture propagates updip along the plate interface, it will reach a series of junctions between the shallowly dipping detachment and more steeply dipping splay faults. The amount and distribution of slip on these splay faults and the detachment determines the seafloor deformation and the tsunami waveform. Numerical studies by Kame et al. [JGR, 2003] of fault branching during dynamic slip-weakening rupture in 2D plane strain showed that branch activation depends on the initial stress state, rupture velocity at the branching junction, and branch angle. They found that for a constant initial stress state, with the maximum principal stress at shallow angles to the main fault, branch activation is favored on the compressional side of the fault for a range of branch angles. By extending the part of their work on modeling the branching behavior in the context of subduction zones, where critical taper wedge concepts suggest the angle that the principal stress makes with the main fault is shallow, but not horizontal, we hope to better understand the conditions for splay fault activation and the criteria for significant moment release on the splay. Our aim is to determine the range of initial stresses and relative frictional strengths of the detachment and splay fault that would result in seismic splay fault activation. In aid of that, we conduct similar dynamic rupture analyses to those of Kame et al., but use explicit finite element methods, and take fuller account of overall structure of the zone (rather than focusing just on the branching junction). Critical taper theory requires that the basal fault be weaker than the overlying material, so we build on previous work by incorporating the effect of strength contrasts between the basal and splay faults. The relative weakness of the basal fault is often attributed to high pore pressures, which lowers the effective normal stress and brings the basal fault closer to failure. We vary the initial stress state, while maintaining a constant principal stress orientation, to see how the closeness to failure affects the branching behavior for a variety of branch step-up angles.

In-situ Tapering of Chalcogenide Fiber for Mid-infrared Supercontinuum Generation

PubMed Central

Rudy, Charles W.; Marandi, Alireza; Vodopyanov, Konstantin L.; Byer, Robert L.

2013-01-01

Supercontinuum generation (SCG) in a tapered chalcogenide fiber is desirable for broadening mid-infrared (or mid-IR, roughly the 2-20 μm wavelength range) frequency combs1, 2 for applications such as molecular fingerprinting, 3 trace gas detection, 4 laser-driven particle acceleration, 5 and x-ray production via high harmonic generation. 6 Achieving efficient SCG in a tapered optical fiber requires precise control of the group velocity dispersion (GVD) and the temporal properties of the optical pulses at the beginning of the fiber, 7 which depend strongly on the geometry of the taper. 8 Due to variations in the tapering setup and procedure for successive SCG experiments-such as fiber length, tapering environment temperature, or power coupled into the fiber, in-situ spectral monitoring of the SCG is necessary to optimize the output spectrum for a single experiment. In-situ fiber tapering for SCG consists of coupling the pump source through the fiber to be tapered to a spectral measurement device. The fiber is then tapered while the spectral measurement signal is observed in real-time. When the signal reaches its peak, the tapering is stopped. The in-situ tapering procedure allows for generation of a stable, octave-spanning, mid-IR frequency comb from the sub harmonic of a commercially available near-IR frequency comb. 9 This method lowers cost due to the reduction in time and materials required to fabricate an optimal taper with a waist length of only 2 mm. The in-situ tapering technique can be extended to optimizing microstructured optical fiber (MOF) for SCG10 or tuning of the passband of MOFs, 11 optimizing tapered fiber pairs for fused fiber couplers12 and wavelength division multiplexers (WDMs), 13 or modifying dispersion compensation for compression or stretching of optical pulses.14-16 PMID:23748947

The study of the thermally expanded core technique in end-pumped (N+1)×1 type combiner

NASA Astrophysics Data System (ADS)

Wu, Juan; Sun, Yinhong; Wang, Yanshan; Li, Tenglong; Feng, Yujun; Ma, Yi

2015-02-01

Tapering will raise the signal loss in an end-pumped (N+1)×1 type combiner. In this paper, the Thermally Expanded Core (TEC) technique is used in the signal loss optimization experiment with the tapering ratio of the pump combiner is 0.6. The experimental results indicate that the coupling efficiency of the 1.55μm signal light increases from 81.1% to 86.6%, after being heated 10 minutes at the homo-waist region of the tapered signal fiber with an 8mm wide hydroxygen flame. Detail analysis shows that the TEC technique can both reduce the loss of the LP01 mode and the LP11 mode in the signal fiber.

Ultraviolet, visible, and infrared laser delivery using laser-to-fiber coupling via a grazing-incidence-based hollow taper

NASA Astrophysics Data System (ADS)

Ilev, Ilko K.; Waynant, Ronald W.

2001-01-01

We present a novel all-optical-waveguide method for ultraviolet (UV), visible (VIS) and infrared (IR) laser delivery including a lens-free method of laser-to-fiber coupling using a simple uncoated glass hollow taper. Based on the grazing incidence effect, the hollow taper provides a way of direct launching, without any intermediate focusing elements, high power laser radiation into delivery fibers. Because of the mutual action of the nearly parallel laser excitation, the mode coupling process, and mode filtering effect, the hollow taper serves as a mode converter that transforms the highly multimode profile of the input laser emission into a high-quality Gaussian-shaped profile at the taper output. When the grazing incidence effect of the taper is applied to laser delivery, the maintenance of high reflectance coefficients in a wide spectral region allows to utilize the same uncoated hollow taper for laser radiation in the UV, VIS and IR ranges. Applying the experimental hollow-taper based delivery systems, we obtain high laser- to-taper and taper-to-fiber coupling efficiencies.

Tapering Practices of Strongman Athletes.

PubMed

Winwood, Paul W; Dudson, Mike K; Wilson, Daniel; Mclaren-Harrison, Justice K H; Redjkins, Vladislav; Pritchard, Hayden J; Keogh, Justin W L

2018-05-01

Winwood, PW, Dudson, MK, Wilson, D, Mclaren-Harrison, JKH, Redjkins, V, Pritchard, HJ, and Keogh, JWL. Tapering practices of strongman athletes. J Strength Cond Res 32(5): 1181-1196, 2018-This study provides the first empirical evidence of how strongman athletes taper for strongman competitions. Strongman athletes (n = 454) (mean ± SD: 33.2 ± 8.0 years, 178.1 ± 10.6 cm, 108.6 ± 27.9 kg, 12.6 ± 8.9 years general resistance training, 5.3 ± 5.0 years strongman implement training) completed a self-reported 4-page internet survey on tapering practices. Analysis by sex (male and female), age (≤30 and >30 years), body mass (≤105 and >105 kg), and competitive standard (local/regional amateur, national amateur and professional) was conducted. Eighty-seven percent (n = 396) of strongman athletes reported that they used a taper. Athletes stated that their typical taper length was 8.6 ± 5.0 days, with the step taper the most commonly performed taper (52%). Training volume decreased during the taper by 45.5 ± 12.9%, and all training ceased 3.9 ± 1.8 days out from competition. Typically, athletes reported that training frequency and training duration stayed the same or decreased and training intensity decreased to around 50% in the last week. Athletes generally stated that tapering was performed to achieve recovery, rest, and peak performance; the deadlift, yoke walk, and stone lifts/work took longer to recover from than other lifts; assistance exercises were reduced or removed in the taper; massage, foam rolling, nutritional changes, and static stretching were strategies used in the taper; and, poor tapering occurred when athletes trained too heavy/hard or had too short a taper. These data will assist strongman athletes and coaches in the optimization of tapering variables leading to more peak performances. Future research could investigate the priming and preactivation strategies strongman athletes use on competition day.

Single muscle fiber adaptations with marathon training.

PubMed

Trappe, Scott; Harber, Matthew; Creer, Andrew; Gallagher, Philip; Slivka, Dustin; Minchev, Kiril; Whitsett, David

2006-09-01

The purpose of this investigation was to characterize the effects of marathon training on single muscle fiber contractile function in a group of recreational runners. Muscle biopsies were obtained from the gastrocnemius muscle of seven individuals (22 +/- 1 yr, 177 +/- 3 cm, and 68 +/- 2 kg) before, after 13 wk of run training, and after 3 wk of taper. Slow-twitch myosin heavy chain [(MHC) I] and fast-twitch (MHC IIa) muscle fibers were analyzed for size, strength (P(o)), speed (V(o)), and power. The run training program led to the successful completion of a marathon (range 3 h 56 min to 5 h 35 min). Oxygen uptake during submaximal running and citrate synthase activity were improved (P < 0.05) with the training program. Muscle fiber size declined (P < 0.05) by approximately 20% in both fiber types after training. P(o) was maintained in both fiber types with training and increased (P < 0.05) by 18% in the MHC IIa fibers after taper. This resulted in >60% increase (P < 0.05) in force per cross-sectional area in both fiber types. Fiber V(o) increased (P < 0.05) by 28% in MHC I fibers with training and was unchanged in MHC IIa fibers. Peak power increased (P < 0.05) in MHC I and IIa fibers after training with a further increase (P < 0.05) in MHC IIa fiber power after taper. These data show that marathon training decreased slow-twitch and fast-twitch muscle fiber size but that it maintained or improved the functional profile of these fibers. A taper period before the marathon further improved the functional profile of the muscle, which was targeted to the fast-twitch muscle fibers.

Coupled tapering/uptapering of Thirring type soliton pair in nonlinear media

NASA Astrophysics Data System (ADS)

Prasad, Shraddha; Dutta, Manoj Kumar; Sarkar, Ram Krishna

2018-03-01

The paper investigates coupled tapering/uptapering of Thirring type soliton pair, employing Beam Propagation Method. It is seen that, the pair uptapers in presence of losses and tapers in presence of gain. When the first beam has gain and the second one has losses in the nonlinear medium, the second beam induces uptapering in the first beam, while, first beam induces tapering in the second beam. When the medium provides gain/losses to only one of the two beams, the beam undergoes tapering/uptapering and also induces tapering/uptapering to the other loss less beam; however, magnitude of tapering/uptapering are different.

Numerical modelling on stimulated Brillouin scattering characterization for Graphene-clad tapered silica fiber

NASA Astrophysics Data System (ADS)

Lee, Hui Jing; Abdullah, Fairuz; Ismail, Aiman

2017-11-01

This paper presents finite numerical modelling on the cross-sectional region of tapered single mode fiber and graphene-clad tapered fiber. Surface acoustic wave propagation across the tapered surface region on tapered single mode fiber has a high threshold power at 61.87 W which is challenging to overcome by the incident pump wave. Surface acoustic wave propagation of fiber surface however made tapered wave plausible in the optical sensor application. This research introduces graphene as the cladding layer on tapered fiber, acoustic confinement occurs due to the graphene cladding which lowers the threshold power from 61.87 W to 2.17 W.

Buprenorphine tapering schedule and illicit opioid use

PubMed Central

Ling, Walter; Hillhouse, Maureen; Domier, Catherine; Doraimani, Geetha; Hunter, Jeremy; Thomas, Christie; Jenkins, Jessica; Hasson, Albert; Annon, Jeffrey; Saxon, Andrew; Selzer, Jeffrey; Boverman, Joshua; Bilangi, Richard

2011-01-01

Aims To compare the effects of a short or long taper schedule after buprenorphine stabilization on participant outcomes as measured by opioid-free urine tests at the end of each taper period. Design This multi-site study sponsored by Clinical Trials Network (CTN, a branch of the US National Institute on Drug Abuse) was conducted from 2003 to 2005 to compare two taper conditions (7 days and 28 days). Data were collected at weekly clinic visits to the end of the taper periods, and at 1-month and 3-month post-taper follow-up visits. Setting Eleven out-patient treatment programs in 10 US cities. Intervention Non-blinded dosing with Suboxone® during the 1-month stabilization phase included 3 weeks of flexible dosing as determined appropriate by the study physicians. A fixed dose was required for the final week before beginning the taper phase. Measurements The percentage of participants in each taper group providing urine samples free of illicit opioids at the end of the taper and at follow-up. Findings At the end of the taper, 44% of the 7-day taper group (n = 255) provided opioid-free urine specimens compared to 30% of the 28-day taper group (n = 261; P = 0.0007). There were no differences at the 1-month and 3-month follow-ups (7-day = 18% and 12%; 28-day = 18% and 13%, 1 month and 3 months, respectively). Conclusion For individuals terminating buprenorphine pharmacotherapy for opioid dependence, there appears to be no advantage in prolonging the duration of taper. PMID:19149822

Monitoring the fabrication of tapered optical fibres

NASA Astrophysics Data System (ADS)

Mullaney, K.; Correia, R.; Staines, S. E.; James, S. W.; Tatam, R. P.

2017-04-01

A variety of optical methods to enhance the process of making optical fibre tapers are explored. A thermal camera was used to both refine the alignment of the optical components and optimize the laser power profile during the tapering process. The fibre transmission was measured to verify that the tapers had the requisite optical characteristics while the strain experienced by the fibre while tapering was assessed using an optical fibre Bragg grating. Using these techniques, adiabatic tapers were fabricated with a 2% insertion loss.

A CFD Database for Airfoils and Wings at Post-Stall Angles of Attack

NASA Technical Reports Server (NTRS)

Petrilli, Justin; Paul, Ryan; Gopalarathnam, Ashok; Frink, Neal T.

2013-01-01

This paper presents selected results from an ongoing effort to develop an aerodynamic database from Reynolds-Averaged Navier-Stokes (RANS) computational analysis of airfoils and wings at stall and post-stall angles of attack. The data obtained from this effort will be used for validation and refinement of a low-order post-stall prediction method developed at NCSU, and to fill existing gaps in high angle of attack data in the literature. Such data could have potential applications in post-stall flight dynamics, helicopter aerodynamics and wind turbine aerodynamics. An overview of the NASA TetrUSS CFD package used for the RANS computational approach is presented. Detailed results for three airfoils are presented to compare their stall and post-stall behavior. The results for finite wings at stall and post-stall conditions focus on the effects of taper-ratio and sweep angle, with particular attention to whether the sectional flows can be approximated using two-dimensional flow over a stalled airfoil. While this approximation seems reasonable for unswept wings even at post-stall conditions, significant spanwise flow on stalled swept wings preclude the use of two-dimensional data to model sectional flows on swept wings. Thus, further effort is needed in low-order aerodynamic modeling of swept wings at stalled conditions.

Influence of CAD/CAM scanning method and tooth-preparation design on the vertical misfit of zirconia crown copings.

PubMed

Castillo Oyagüe, Raquel; Sánchez-Jorge, María Isabel; Sánchez Turrión, Andrés

2010-12-01

To evaluate the influence of scanning method, finish line type and occlusal convergence angle of the teeth preparations on the vertical misfit of zirconia crown copings. 20 standardized stainless-steel master dies were machined simulating full-crown preparations. The total convergence angle was 15 degrees or 20 degrees (n=10 each). Two of the finish line types: a chamfer (CH) and a shoulder (SH) were prepared around the contour of each abutment. Over these dies, 20 structures were made by CAD/CAM (Cercon, Dentsply). An optical laser digitized the wax patterns of 10 single-unit copings (WS), and 10 abutments were direct-scanned to design the cores by computer (DS). Zirconia milled caps were luted onto the models under constant seating pressure. Vertical discrepancy was assessed by SEM. Misfit data were analyzed using ANOVA and Student-Newman-Keuls (SNK) test for multiple comparisons at alpha = 0.05. Vertical gap measurements of WS copings were significantly higher than those of DS frames (P < 0.0001). SH exhibited statistically higher discrepancies than CH when combined with a 15-degree occlusal convergence angle regardless of the scanning method (P < 0.05). The taper angle of the preparation (15 degrees vs. 20 degrees) had no effect on the marginal adaptation of chamfered samples.

High-brightness 1.3 μm InAs/GaAs quantum dot tapered laser with high temperature stability.

PubMed

Cao, Yulian; Ji, Haiming; Xu, Pengfei; Gu, Yongxian; Ma, Wenquan; Yang, Tao

2012-10-01

We demonstrate high-brightness 1.3 μm tapered lasers with high temperature stability by using p-doped InAs/GaAs quantum dots (QDs) as the active region. It is found that the beam quality factor M(2) for the devices is almost unchanged as the light power and temperature increase. The almost constant M(2) results from the p-doped QD active region.

Experimental aerodynamic characteristics for slender bodies with thin wings and tail at angles of attack from 0 deg to 58 deg and Mach numbers from 0.6 to 2.0

NASA Technical Reports Server (NTRS)

Jorgensen, L. H.; Nelson, E. R.

1976-01-01

An experimental investigation was conducted by wind tunnel to measure the static aerodynamic characteristics for bodies of circular and elliptic cross section with various thin flat plate wings and a thin tail consisting of horizontal and vertical parts. The wings had aspect ratios of 4 and taper ratios of about 0, 0.25, and 0.5. Two additional wings, which had taper ratios near 0.25 and aspect ratios of about 3 and 5, were also tested in combination with the bodies and tail. All wings had about the same planform area. The exposed area of the horizontal portion of the tail was about 33 to 36 percent of the exposed area of the wings. The exposed area of the vertical tail fin was about 22 to 24 percent of the exposed area of the wings. The elliptic body, with an a/b = 2 cross section, had the same length and axial distribution of cross sectional area as the circular body. The circular body had a cylindrical aftersection of fineness ratio 7, and it was tested with the wings and tail in combination with tangent ogive noses that had fineness ratios of 2.5, 3.0, 3.5, and 5.0. In addition, an ogive nose with a rounded tip and an ogive nose with two different nose strake arrangements were used. Nineteen configuration combinations were tested at Mach numbers of 0.6, 0.9, 1.5, and 2.0 at angles of attack from 0 to 58 deg. The Reynolds numbers, based on body base diameter, were about 4.3 X 100,000.

Measurement Sensitivity Of Liquid Droplet Parameters Using Optical Fibers

NASA Astrophysics Data System (ADS)

Das, Alok K.; Mandal, Anup K.

1990-02-01

A new clad probing technique is used to measure the size, number, refractive index and viscosity of liquid droplets sprayed from a pressure nozzle on an uncoated core-clad fiber. The probe monitors the clad mode power loss within the leaky ray zone represented as a three region fiber. Liquid droplets measured are Glycerine, commercial grade Turpentine, Linseed oil and some oil mixtures. The measurement sensitivity depends on probing conditions and clad diameter which is observed experimentally and verified analytically. A maximum sensitivity is obtained for the tapered probe-fiber diameter made equal to the clad thickness. A slowly tapered probe-fiber and a small end angle as well as separation of the sensor-fiber and the probe-fiber further improve the sensitivity. Under the best probing condition for 90-percent Glycerine droplets of - 50 micron diameter and a 50/125 micron sensor fiber with clad refractive index of 1.465 and 0.2 NA, the measured sensitivity per drop is 0.015 and 0.006 dB, respectively, for (10-20) and (100-200) droplets. Sensitivities for different systems are shown. The sensitivity is optimized by choosing proper fiber for known liquids.

Evaluation of arch form between Vietnamese and North American Caucasians using 3-dimensional virtual models.

PubMed

Trang, Vu Thi Thu; Park, Jae Hyun; Bayome, Mohamed; Shastry, Shruti; Mellion, Alex; Kook, Yoon-Ah

2015-01-01

The purpose of this study was to investigate the three-dimensional (3D) morphologic differences in the mandibular arch of Vietnamese and North American White subjects. The sample included 113 Vietnamese subjects (41 Class I, 37 Class II and 35 Class III) and 96 White subjects (29 Class I, 30 Class II and 37 Class III). The samples were regrouped according to arch form types (tapered, ovoid, and square) to compare the frequency distribution of the three arch forms between ethnic groups in each angle classification. The facial axis point of each tooth was digitized on 3D virtual models. Four linear and two ratio variables were measured. In comparing arch dimensions, the intercanine and intermolar widths were wider in Vietnamese than in Whites (p < 0.001, p = 0.042, respectively). In the White group, there was even frequency distribution of the three arch forms. However, in the Vietnamese group, the square arch form was the most frequent followed by tapered and ovoid arch forms. The arch forms of Whites were narrower than Vietnamese. In North American Whites, the distribution of the arch form types showed similar frequency. In Vietnamese, the square arch form was more frequent.

Methods for In-Flight Wing Shape Predictions of Highly Flexible Unmanned Aerial Vehicles: Formulation of Ko Displacement Theory

NASA Technical Reports Server (NTRS)

Ko, William L.; Fleischer, Van Tran

2010-01-01

The Ko displacement theory is formulated for a cantilever tubular wing spar under bending, torsion, and combined bending and torsion loading. The Ko displacement equations are expressed in terms of strains measured at multiple sensing stations equally spaced on the surface of the wing spar. The bending and distortion strain data can then be input to the displacement equations to calculate slopes, deflections, and cross-sectional twist angles of the wing spar at the strain-sensing stations for generating the deformed shapes of flexible aircraft wing spars. The displacement equations have been successfully validated for accuracy by finite-element analysis. The Ko displacement theory that has been formulated could also be applied to calculate the deformed shape of simple and tapered beams, plates, and tapered cantilever wing boxes. The Ko displacement theory and associated strain-sensing system (such as fiber optic sensors) form a powerful tool for in-flight deformation monitoring of flexible wings and tails, such as those often employed on unmanned aerial vehicles. Ultimately, the calculated displacement data can be visually displayed in real time to the ground-based pilot for monitoring the deformed shape of unmanned aerial vehicles during flight.

Cleaning and shaping curved root canals: Mtwo vs ProTaper instruments, a lab comparison.

PubMed

Kuzekanani, Maryam; Walsh, Laurence J; Yousefi, Mohammad Ali

2009-01-01

The purpose of this study was to compare root canal preparation in curved canals in molar teeth with the rotary NiTi Mtwo and ProTaper systems in terms of canal shape and smear layer. Mesiobuccal canals of 60 molar teeth with angles of curvature between 25 and 35 degrees were prepared with a torque controlled low speed engine; 30 canals for each system. Each individual instrument was used to prepare four root canals and the time required for preparation was recorded. Standardized radiographs were taken before and following instrumentation and used to determine changes in canal curvature. There was no significant difference in preparation time between the two systems. No instruments separated during use. The Mtwo system gave a statistically smaller change in canal curvature and thus was better for maintaining the original shape of the root canal, with less transportation (P less than 0.05). The greatest difference was seen for maxillary molar teeth. When prepared root canals were examined by SEM there was no difference between the two systems at the coronal, middle or apical thirds. Overall, the results of this study suggest that Mtwo instruments are preferable for situations where canals are curved, particularly for maxillary molars.

2D constant-loss taper for mode conversion

NASA Astrophysics Data System (ADS)

Horth, Alexandre; Kashyap, Raman; Quitoriano, Nathaniel J.

2015-03-01

Proposed in this manuscript is a novel taper geometry, the constant-loss taper (CLT). This geometry is derived with 1D slabs of silicon embedded in silicon dioxide using coupled-mode theory (CMT). The efficiency of the CLT is compared to both linear and parabolic tapers using CMT and 2D finite-difference time-domain simulations. It is shown that over a short 2D, 4.45 μm long taper the CLT's mode conversion efficiency is ~90% which is 10% and 18% more efficient than a 2D parabolic or linear taper, respectively.

Evaluation of retention and fracture resistance of different fiber reinforced posts: An in vitro study.

PubMed

Pruthi, Varun; Talwar, Sangeeta; Nawal, Ruchika Roongta; Pruthi, Preeti Jain; Choudhary, Sarika; Yadav, Seema

2018-01-01

The aim of this study was to evaluate retention & fracture resistance of different fibre posts. 90 extracted human permanent maxillary central incisors were used in this study. For retention evaluation, after obturation, post space preparation was done in all root canals and posts were cemented under three groups. Later, the posts were grasped & pulled out from the roots with the help of a three-jaw chuck at a cross-head speed of 5mm/min. Force required to dislodge each post was recorded in Newtons. To evaluate the fracture behavior of posts, artificial root canals were drilled into aluminium blocks and posts were cemented. Load required to fracture each post was recorded in Newtons. The results of the present study show the mean retention values for Fibrekleer Parallel post were significantly greater than those for Synca Double tapered post & Bioloren Tapered post. The mean retention values of the Double tapered post & the tapered post were not statistically different. The Synca Double tapered post had the highest mean load to fracture, and this value was significantly higher than those of FibreKleer Parallel & Bioloren Tapered post. The mean fracture resistance values of Parallel & tapered post were not statistically different. This study showed parallel posts to have better retention than tapered and double tapered posts. Regarding the fracture resistance, double tapered posts were found to be better than parallel and tapered posts.

Tapered fiber nanoprobes: plasmonic nanopillars on tapered optical fiber tips for large EM enhancement.

PubMed

Savaliya, Priten; Dhawan, Anuj

2016-10-01

Employing finite difference time domain simulations, we demonstrate that electromagnetic field enhancement is substantially greater for tapered optical fibers with plasmonic nanostructures present on their tips as compared with non-tapered optical fibers having those plasmonic nanostructures, or with tapered optical fibers without the plasmonic nanostructures. We also carried out fabrication of plasmonic nanostructures on optical fiber tips.

Optical fiber nanoprobe preparation for near-field optical microscopy by chemical etching under surface tension and capillary action.

PubMed

Mondal, Samir K; Mitra, Anupam; Singh, Nahar; Sarkar, S N; Kapur, Pawan

2009-10-26

We propose a technique of chemical etching for fabrication of near perfect optical fiber nanoprobe (NNP). It uses photosensitive single mode optical fiber to etch in hydro fluoric (HF) acid solution. The difference in etching rate for cladding and photosensitive core in HF acid solution creates capillary ring along core-cladding boundary under a given condition. The capillary ring is filled with acid solution due to surface tension and capillary action. Finally it creates near perfect symmetric tip at the apex of the fiber as the height of the acid level in capillary ring decreases while width of the ring increases with continuous etching. Typical tip features are short taper length (approximately 4 microm), large cone angle (approximately 38 degrees ), and small probe tip dimension (<100 nm). A finite difference time domain (FDTD) analysis is also presented to compare near field optics of the NNP with conventional nanoprobe (CNP). The probe may be ideal for near field optical imaging and sensor applications.

The Influence of the Aerodynamic Span Effect on the Magnitude of the Torsional-divergence Velocity and on the Shape of the Corresponding Deflection Mode

NASA Technical Reports Server (NTRS)

Hildebrand, Francis B; Reissner, Eric

1944-01-01

A procedure which takes into account the aerodynamic span effect is given for the determination of the torsional-divergence velocities of monoplanes. The explicit solutions obtained in several cases indicate that the aerodynamic span effect may increase the divergence velocities found by means of the section-force theory by as much as 17 to 40 percent. It is found that the magnitude of the effect increases with increasing degree of stiffness taper and decreases with increasing degree of chord taper. By a slight extension of the present method it is possible to analyze the elastic deformations of wings, and the resultant lift distributions, before torsional divergence occurs.

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

PubMed Central

Xu, Wenjie; Chen, Zhenyi; Chen, Na; Zhang, Heng; Liu, Shupeng; Hu, Xinmao; Wen, Jianxiang; Wang, Tingyun

2017-01-01

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. PMID:28245618

Soliton self-frequency shift and third-harmonic generation in a four-hole As₂S₅ microstructured optical fiber.

PubMed

Cheng, Tonglei; Usaki, Ryo; Duan, Zhongchao; Gao, Weiqing; Deng, Dinghuan; Liao, Meisong; Kanou, Yasuhire; Matsumoto, Morio; Misumi, Takashi; Suzuki, Takenobu; Ohishi, Yasutake

2014-02-24

Soliton self-frequency shift (SSFS) and third-harmonic generation (THG) are observed in a four-hole As2S5 chalcogenide microstructured optical fiber (MOF). The As2S5 MOF is tapered to offer an ideal environment for SSFS. After tapering, the zero-dispersion wavelength (ZDW) shifts from 2.02 to 1.61 μm, and the rate of SSFS can be enhanced by increasing the energy density of the pulse. By varying the average input power from 220 to 340 mW, SSFS of a soliton central wavelength from 2.206 to 2.600 μm in the mid-infrared is observed in the tapered segment, and THG at 632 nm is observed in the untapered segment.

Refractive index sensor based on plastic optical fiber with tapered structure.

PubMed

De-Jun, Feng; Guan-Xiu, Liu; Xi-Lu, Liu; Ming-Shun, Jiang; Qing-Mei, Sui

2014-04-01

This work reports a refractive index sensor made of plastic optical fiber (POF) with tapered structure. Transmission loss is measured when the external environment's refractive index changes from 1.33 to 1.41. Three wavelengths (532, 633, and 780 nm) are used to evaluate the sensitivity of the sensor, and results indicate that 633 nm is the best sensing wavelength due to the increased levels of sensitivity achieved at this wavelength. A biconical sensing structure is designed to enhance the sensitivity of the sensor. A sensitivity of 950 μW/RIU at 633 nm is obtained for a biconical sensing structure when launched power is 1 mW. Due to its sensitivity to the refractive index and simple construction, POF with tapered structure has potential applications in the biosensing field.

Linearly chirped tapered fiber-Bragg-grating-based Fabry-Perot cavity and its application in simultaneous strain and temperature measurement.

PubMed

Markowski, Konrad; Jędrzejewski, Kazimierz; Marzęcki, Michał; Osuch, Tomasz

2017-04-01

A novel concept of a Fabry-Perot (F-P) cavity composed of two linearly chirped fiber Bragg gratings written in a thermally fused fiber taper is presented. Both chirped gratings are written in counter-directional chirp configuration, where chirps resulting from the optical fiber taper profile and linearly increasing grating periods cancel each other out, forming a high-quality F-P resonator. A new strain-sensing mechanism is proposed in the presented structure, which is based on strain-induced detuning of the F-P resonator. Due to the different strain and temperature responses of the cavity, the resonator can be used for the simultaneous measurement of these physical quantities, or it can be used as a temperature-independent strain sensor.

Method and apparatus for making superconductive magnet coils

DOEpatents

Borden, A.R.

1983-11-07

A curved, shell-type magnet coil, adapted to be used in a superconducting magnet, is wound by providing a mandrel having a tubular cylindrical mid-portion terminating at both ends in tapered end portions formed with longitudinal slots having flexible fingers therebetween. An elongated electrical conductor is wound around an elongated oval-shaped pole island engaged with the outside of the cylindrical mid-portion, to form a multiplicity of oval-shaped turns engaged with a 180-degree segment of the mandrel. The coil turns have longitudinal portions with curved portions therebetween, engaging the tapered end portions of the mandrel. Upon completion of the winding, tapered expansion members are fully inserted into the tapered end portions, to displace the flexible fingers outwardly into a cylindrical form and to displace the curved portions of the turns into a shape conforming to such cylindrical form while also exerting increased tension upon the turns to minimize draping of the turns and to enhance the mechanical integrity of the coil. A half cylinder clamp may then be employed to clamp the coil, whereupon the coil may be solidified by the use of an epoxy adhesive.

Method and apparatus for making superconductive magnet coils

DOEpatents

Borden, Albert R.

1985-01-01

A curved, shell-type magnet coil, adapted to be used in a superconducting magnet, is wound by providing a mandrel having a tubular cylindrical mid-portion terminating at both ends in tapered end portions formed with longitudinal slots having flexible fingers therebetween. An elongated electrical conductor is wound around an elongated oval-shaped pole island engaged with the outside of the cylindrical mid-portion, to form a multiplicity of oval-shaped turns engaged with a 180-degree segment of the mandrel. The coil turns have longitudinal portions with curved portions therebetween, engaging the tapered end portions of the mandrel. Upon completion of the winding, tapered expansion members are fully inserted into the tapered end portions, to displace the flexible fingers outwardly into a cylindrical form and to displace the curved portions of the turns into a shape conforming to such cylindrical form while also exerting increased tension upon the turns to minimize draping of the turns and to enhance the mechanical integrity of the coil. A half cylinder clamp may then be employed to clamp the coil, whereupon the coil may be solified by the use of an epoxy adhesive.

Spectrum online-tunable Mach-Zehnder interferometer based on step-like tapers and its refractive index sensing characteristics

NASA Astrophysics Data System (ADS)

Zhao, Yong; Chen, Mao-qing; Xia, Feng; Hu, Hai-feng

2017-11-01

A novel refractive index (RI) sensor based on an asymmetrical Mach-Zehnder interferometer (MZI) with two different step-like tapers is proposed. The step-like taper is fabricated by fusion splicing two half tapers with an appropriate offset. By further applying offset and discharging to the last fabricated step-like taper of MZI, influence of taper parameters on interference spectrum is investigated using only one device. This simple technique provides an on-line method to sweep parameters of step-like tapers and speeds up the optimization process of interference spectrum, meanwhile. In RI sensing experiment, the sensor has a high sensitivity of -185.79 nm/RIU (refractive index unit) in the RI range of 1.3333-1.3673.

Damped gyroscopic effects and axial-flexural-torsional coupling using spinning finite elements for wind-turbine blades characterization

NASA Astrophysics Data System (ADS)

Velazquez, Antonio; Swartz, R. Andrew

2013-04-01

Renewable energy sources like wind are important technologies, useful to alleviate for the current fossil-fuel crisis. Capturing wind energy in a more efficient way has resulted in the emergence of more sophisticated designs of wind turbines, particularly Horizontal-Axis Wind Turbines (HAWTs). To promote efficiency, traditional finite element methods have been widely used to characterize the aerodynamics of these types of multi-body systems and improve their design. Given their aeroelastic behavior, tapered-swept blades offer the potential to optimize energy capture and decrease fatigue loads. Nevertheless, modeling special complex geometries requires huge computational efforts necessitating tradeoffs between faster computation times at lower cost, and reliability and numerical accuracy. Indeed, the computational cost and the numerical effort invested, using traditional FE methods, to reproduce dependable aerodynamics of these complex-shape beams are sometimes prohibitive. A condensed Spinning Finite Element (SFE) method scheme is presented in this study aimed to alleviate this issue by means of modeling wind-turbine rotor blades properly with tapered-swept cross-section variations of arbitrary order via Lagrangian equations. Axial-flexural-torsional coupling is carried out on axial deformation, torsion, in-plane bending and out-of-plane bending using super-convergent elements. In this study, special attention is paid for the case of damped yaw effects, expressed within the described skew-symmetric damped gyroscopic matrix. Dynamics of the model are analyzed by achieving modal analysis with complex-number eigen-frequencies. By means of mass, damped gyroscopic, and stiffness (axial-flexural-torsional coupling) matrix condensation (order reduction), numerical analysis is carried out for several prototypes with different tapered, swept, and curved variation intensities, and for a practical range of spinning velocities at different rotation angles. A convergence study for the resulting natural frequencies is performed to evaluate the dynamic collateral effects of tapered-swept blade profiles in spinning motion using this new model. Stability analysis in boundary conditions of the postulated model is achieved to test the convergence and integrity of the mathematical model. The proposed framework presumes to be particularly suitable to characterize models with complex-shape cross-sections at low computation cost.

[Shaping ability of two nickel-titanium rotary systems in simulated S-shaped canals].

PubMed

Luo, Hong-xia; Huang, Ding-ming; Zhang, Fu-hua; Tan, Hong; Zhou, Xue-dong

2008-01-01

To evaluate the shaping ability of two nickel-titanium rotary systems (ProTaper and Hero642) in simulated S-shaped canals. Thirty simulated S-shaped canals were randomly divided into three groups and prepared by ProTaper, Hero642, ProTaper combined with Hero642 respectively. All the canals were scanned before and after instrumentation, and the amount of material removed in the inner and outer wall and the canal width after instrumentation were measured with a computer image analysis program. There was significant difference in the amount of material removed at the inner side of apical curvature and outer side of apex between ProTaper combined with Hero642 and ProTaper files (P < 0.05) at the same tip size. The inner and outer wall of the canals were evenly prepared by ProTaper combined with Hero642, and the taper of canals were better than those prepared by Hero642. ProTaper combined with Hero 642 had better shaping ability to maintain the original shape and could create good taper canals in the simulated S-shaped canal model.

Principles of managing Vancouver type B periprosthetic fractures around cemented polished tapered femoral stems.

PubMed

Quah, Conal; Porteous, Matthew; Stephen, Arthur

2017-05-01

The management of periprosthetic fractures around total hip replacements is a complex and challenging problem. Getting it right first time is an important factor in reducing the morbidity, mortality and financial burden associated with these injuries. Understanding and applying the basic principles of fracture management helps increase the chance of successful treatment. Based on these principles, we suggest a treatment algorithm for managing periprosthetic fractures around polished tapered femoral stems.

Effect of a Dielectric Overlay on a Linearly Tapered Slot Antenna Excited by a Coplanar Waveguide

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Lee, Richard Q.; Perl, Thomas D.; Silvestro, John

1993-01-01

The effect of a dielectric overlay on a linearly tapered slot antenna (LTSA) is studied. The LTSA under study has very wide bandwidth and excellent radiation patterns. A dielectric overlay improves the patterns and directivity of the antenna by increasing the electrical length and effective aperture of the antenna. A dielectric overlay can also be used to reduce the physical length of the antenna without compromising the pattern quality.

The relationship between seizures, interictal spikes and antiepileptic drugs.

PubMed

Goncharova, Irina I; Alkawadri, Rafeed; Gaspard, Nicolas; Duckrow, Robert B; Spencer, Dennis D; Hirsch, Lawrence J; Spencer, Susan S; Zaveri, Hitten P

2016-09-01

A considerable decrease in spike rate accompanies antiepileptic drug (AED) taper during intracranial EEG (icEEG) monitoring. Since spike rate during icEEG monitoring can be influenced by surgery to place intracranial electrodes, we studied spike rate during long-term scalp EEG monitoring to further test this observation. We analyzed spike rate, seizure occurrence and AED taper in 130 consecutive patients over an average of 8.9days (range 5-17days). We observed a significant relationship between time to the first seizure, spike rate, AED taper and seizure occurrence (F (3,126)=19.77, p<0.0001). A high spike rate was related to a longer time to the first seizure. Further, in a subset of 79 patients who experienced seizures on or after day 4 of monitoring, spike rate decreased initially from an on- to off-AEDs epoch (from 505.0 to 382.3 spikes per hour, p<0.00001), and increased thereafter with the occurrence of seizures. There is an interplay between seizures, spikes and AEDs such that spike rate decreases with AED taper and increases after seizure occurrence. The direct relationship between spike rate and AEDs and between spike rate and time to the first seizure suggests that spikes are a marker of inhibition rather than excitation. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Numerical modelling on pulsatile flow of Casson nanofluid through an inclined artery with stenosis and tapering under the influence of magnetic field and periodic body acceleration

NASA Astrophysics Data System (ADS)

Ponalagusamy, R.; Priyadharshini, S.

2017-11-01

The present study investigates the pulsatile flow of Casson nanofluid through an inclined and stenosed artery with tapering in the presence of magnetic field and periodic body acceleration. The iron oxide nanoparticles are allowed to flow along with it. The governing equations for the flow of Casson fluid when the artery is tapered slightly having mild stenosis are highly non-linear and the momentum equations for temperature and concentration are coupled and are solved using finite difference numerical schemes in order to find the solutions for velocity, temperature, concentration, wall shear stress, and resistance to blood flow. The aim of the present study is to analyze the effects of flow parameters on the flow of nanofluid through an inclined arterial stenosis with tapering. These effects are represented graphically and concluded that the wall shear stress profiles enhance with increase in yield stress, magnetic field, thermophoresis parameter and decreases with Brownian motion parameter, local temperature Grashof number, local nanoparticle Grashof number. The significance of the model is the existence of yield stress and it is examined that when the rheology of blood changes from Newtonian to Casson fluid, the percentage of decrease in the flow resistance is higher with respect to the increase in the parameters local temperature Grashof number, local nanoparticle Grashof number, Brownian motion parameter, and Prandtl number. It is pertinent to observe that increase in the Brownian motion parameter leads to increment in concentration and temperature profiles. It is observed that the concentration of nanoparticles decreases with increase in the value of thermophoresis parameter.

Octave spanning supercontinuum in an As₂S₃ taper using ultralow pump pulse energy.

PubMed

Hudson, Darren D; Dekker, Stephen A; Mägi, Eric C; Judge, Alexander C; Jackson, Stuart D; Li, Enbang; Sanghera, J S; Shaw, L B; Aggarwal, I D; Eggleton, Benjamin J

2011-04-01

An octave spanning spectrum is generated in an As₂S₃ taper via 77 pJ pulses from an ultrafast fiber laser. Using a previously developed tapering method, we construct a 1.3 μm taper that has a zero-dispersion wavelength around 1.4 μm. The low two-photon absorption of sulfide-based chalcogenide fiber allows for higher input powers than previous efforts in selenium-based chalcogenide tapered fibers. This higher power handling capability combined with input pulse chirp compensation allows an octave spanning spectrum to be generated directly from the taper using the unamplified laser output.

Geometry-based pressure drop prediction in mildly diseased human coronary arteries.

PubMed

Schrauwen, J T C; Wentzel, J J; van der Steen, A F W; Gijsen, F J H

2014-06-03

Pressure drop (△p) estimations in human coronary arteries have several important applications, including determination of appropriate boundary conditions for CFD and estimation of fractional flow reserve (FFR). In this study a △p prediction was made based on geometrical features derived from patient-specific imaging data. Twenty-two mildly diseased human coronary arteries were imaged with computed tomography and intravascular ultrasound. Each artery was modelled in three consecutive steps: from straight to tapered, to stenosed, to curved model. CFD was performed to compute the additional △p in each model under steady flow for a wide range of Reynolds numbers. The correlations between the added geometrical complexity and additional △p were used to compute a predicted △p. This predicted △p based on geometry was compared to CFD results. The mean △p calculated with CFD was 855±666Pa. Tapering and curvature added significantly to the total △p, accounting for 31.4±19.0% and 18.0±10.9% respectively at Re=250. Using tapering angle, maximum area stenosis and angularity of the centerline, we were able to generate a good estimate for the predicted △p with a low mean but high standard deviation: average error of 41.1±287.8Pa at Re=250. Furthermore, the predicted △p was used to accurately estimate FFR (r=0.93). The effect of the geometric features was determined and the pressure drop in mildly diseased human coronary arteries was predicted quickly based solely on geometry. This pressure drop estimation could serve as a boundary condition in CFD to model the impact of distal epicardial vessels. Copyright © 2014 Elsevier Ltd. All rights reserved.

Assessment of Corrosion, Fretting, and Material Loss of Retrieved Modular Total Knee Arthroplasties.

PubMed

Martin, Audrey J; Seagers, Kirsten A; Van Citters, Douglas W

2017-07-01

Modular junctions in total hip arthroplasties have been associated with fretting, corrosion, and debris release. The purpose of this study is to analyze damage severity in total knee arthroplasties of a single design by qualitative visual assessment and quantitative material loss measurements to evaluate implant performance and patient impact via material loss. Twenty-two modular knee retrievals of the same manufacturer were identified from an institutional review board-approved database. Junction designs included tapers with an axial screw and tapers with a radial screw. Constructs consisted of 2 metal alloys: CoCr and Ti6Al4V. Components were qualitatively scored and quantitatively measured for corrosion and fretting. Negative values represent adhered material. Statistical differences were analyzed using sign tests. Correlations were tested with a Spearman rank order test (P < .05). The median volumetric material loss and the maximum linear depth for the total population were -0.23 mm 3 and 5.84 μm, respectively. CoCr components in mixed metal junctions had higher maximum linear depth (P = .007) than corresponding Ti components. Fretting scores of Ti6Al4V alloy components in mixed metal junctions were statistically higher than the remaining groups. Taper angle did not correlate with material loss. Results suggest that CoCr components in mixed metal junctions are more vulnerable to corrosion than other components, suggesting preferential corrosion when interfacing with Ti6Al4V. Overall, although corrosion was noted in this series, material loss was low, and none were revised for clinical metal-related reaction. This suggests the clinical impact from corrosion in total knee arthroplasty is low. Copyright © 2017 Elsevier Inc. All rights reserved.

Geometric analysis of root canals prepared by four rotary NiTi shaping systems.

PubMed

Hashem, Ahmed Abdel Rahman; Ghoneim, Angie Galal; Lutfy, Reem Ahmed; Foda, Manar Yehia; Omar, Gihan Abdel Fatah

2012-07-01

A great number of nickel-titanium (NiTi) rotary systems with noncutting tips, different cross-sections, superior resistance to torsional fracture, varying tapers, and manufacturing method have been introduced to the market. The purpose of this study was to evaluate and compare the effect of 4 rotary NiTi preparation systems, Revo-S (RS; Micro-Mega, Besancon Cedex, France), Twisted file (TF; SybronEndo, Amersfoort, The Netherlands), ProFile GT Series X (GTX; Dentsply, Tulsa Dental Specialties, Tulsa, OK), and ProTaper (PT; Dentsply Maillefer, Ballaigues, Switzerland), on volumetric changes and transportation of curved root canals. Forty mesiobuccal canals of mandibular molars with an angle of curvature ranging from 25° to 40° were divided according to the instrument used in canal preparation into 4 groups of 10 samples each: group RS, group TF, group GTX, and group PT. Canals were scanned using an i-CAT CBCT scanner (Imaging Science International, Hatfield, PA) before and after preparation to evaluate the volumetric changes. Root canal transportation and centering ratio were evaluated at 1.3, 2.6, 5.2, and 7.8 mm from the apex. The significance level was set at P ≤ .05. The PT system removed a significantly higher amount of dentin than the other systems (P = .025). At the 1.3-mm level, there was no significant difference in canal transportation and centering ratio among the groups. However, at the other levels, TF maintained the original canal curvature recording significantly the least degree of canal transportation as well as the highest mean centering ratio. The TF system showed superior shaping ability in curved canals. Revo-S and GTX were better than ProTaper regarding both canal transportation and centering ability. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Sensitivity enhancement of fluorescence detection in CE by coupling and conducting excitation light with tapered optical fiber.

PubMed

Yang, Xiupei; Huo, Feng; Yuan, Hongyan; Zhang, Bo; Xiao, Dan; Choi, Martin M F

2011-01-01

This paper reports the enhancement of sensitivity of detection for in-column fiber optic-induced fluorescence detection system in CE by tapered optical fiber (TOF). Two types of optical fiber, TOF and conventional cylindrical optical fiber (COF), were employed to construct the CE (TOF-CE and COF-CE) and were compared for sensitivity to riboflavin (RF). The fluorescence intensities from a RF sample with excitation light sources and fibers at various coupling angles were investigated. The fluorescence signal from TOF-CE was ca. ten times that of COF-CE. In addition, the detection performance of four excitation light source-fiber configurations including Laser-TOF, Laser-COF, LED-TOF, and LED-COF were compared. The LODs for RF were 0.21, 0.82, 0.80, and 7.5 nM, respectively, for the four excitation light source-fiber configurations. The results demonstrate that the sensitivity obtained by LED-TOF is close to that of Laser-COF. Both Laser-TOF and LED-TOF can greatly improve the sensitivity of detection in CE. TOF has the major attribute of collecting and focusing the excitation light intensity. Thus, the sensitivity obtained by LED-TOF without focusing lens is just same as that of LED-COF with a focusing lens. This demonstrates that the CE system can be further simplified by eliminating the focusing lens for excitation light. LED-TOF-CE and LED-COF-CE system were applied to the separation and determination of RF in real sample (green tea), respectively. The tapered fiber optic-induced fluorescence detection system in CE is an ideal tool for trace analysis. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sensitive Leptospira DNA detection using tapered optical fiber sensor.

PubMed

Zainuddin, Nurul H; Chee, Hui Y; Ahmad, Muhammad Z; Mahdi, Mohd A; Abu Bakar, Muhammad H; Yaacob, Mohd H

2018-03-23

This paper presents the development of tapered optical fiber sensor to detect a specific Leptospira bacteria DNA. The bacteria causes Leptospirosis, a deadly disease but with common early flu-like symptoms. Optical single mode fiber (SMF) of 125 μm diameter is tapered to produce 12 μm waist diameter and 15 cm length. The novel DNA-based optical fiber sensor is functionalized by incubating the tapered region with sodium hydroxide (NaOH), (3-Aminopropyl) triethoxysilane and glutaraldehyde. Probe DNA is immobilized onto the tapered region and subsequently hybridized by its complementary DNA (cDNA). The transmission spectra of the DNA-based optical fiber sensor are measured in the 1500 to 1600 nm wavelength range. It is discovered that the shift of the wavelength in the SMF sensor is linearly proportional with the increase in the cDNA concentrations from 0.1 to 1.0 nM. The sensitivity of the sensor toward DNA is measured to be 1.2862 nm/nM and able to detect as low as 0.1 fM. The sensor indicates high specificity when only minimal shift is detected for non-cDNA testing. The developed sensor is able to distinguish between actual DNA of Leptospira serovars (Canicola and Copenhageni) against Clostridium difficile (control sample) at very low (femtomolar) target concentrations. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bending stiffness, torsional stability, and insertion force of cementless femoral stems.

PubMed

Incavo, S J; Johnson, C C; Churchill, D L; Beynnon, B D

2001-04-01

In cementless total hip arthroplasty, increased femoral stem flexibility and decreased fracture propensity are desirable characteristics. The slotting and tapering of the stem have been introduced to achieve this. These features should not, however, be allowed to interfere with the ability of the distal stem to provide initial mechanical stability, especially under rotation. This study was done to investigate the ability of slotted and tapered stem designs to reduce stiffness and insertion force while still maintaining adequate torsional strength. The torsional strength, maximum insertion force, and insertional work of straight, slotted, and taper stems were measured by inserting each type into rigid polyurethane foam and torque testing to failure. Bending stiffness of each stem design was calculated using numerical methods. When compared to a straight stem, a unislot stem has similar torsional strength, maximum insertional force, and work of insertion. The bending stiffness is decreased by 19% to 82% depending on the bending direction. A trislot design decreased torque strength by 29%, maximal insertion force by 36%, and work by 11%. Bending stiffness was decreased by 74% and was not dependent on bending direction. A 0.5-mm taper decreased torque strength by 11% and insertional work by 14%. No difference was seen in maximum insertional force. We conclude that the design features studied (slots and taper) are effective in decreasing stem stiffness and reducing fracture propensity.

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

PubMed

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.

Studies on low-loss coupling of non-node anti-resonant hollow-core fiber and tapered fiber

NASA Astrophysics Data System (ADS)

Zhang, Naiqian; Wang, Zefeng; Liu, Wenbo; Xi, Xiaoming

2017-10-01

Up to now, near almost optical fiber gas lasers employ/adopt the scheme of free-space coupling, which increases the difficulty to adjust the optical path, and has poor stability. All-fiber structure fiber-gas lasers are important development directions in the future. We established the numerical model of SMF-28 type tapered single-mode fiber and non-node hollow-core fiber. When the SMF-28 type single-mode fiber has a waist diameter of 40μm when the light source is LP01 fundamental mode with 1550nm wavelength, the mode field diameter is the largest. Meanwhile, we simulated that the equivalent mode field diameter of non-node anti-resonant hollow-core fiber is about 75μm at the same 1550nm wavelength light source. Then, we use different waist diameters of SMF-28 type tapered fibers injected to the non-node anti-resonant hollow-core fiber in simulation and experiments. In the scheme of the single-ended low-loss coupling, the simulation results indicate that the best waist diameter of tapered fiber is 40μm, and the calculated maximum coupling efficiency is 83.55%. Meanwhile, the experimental result of maximum coupling efficiency is 80.74% when the best waist diameter of tapered fiber is also 40μm. As for the double-ended low-loss coupling, the calculated maximum coupling efficiency is near 83.38%.

The Association between Outpatient Buprenorphine Detoxification Duration and Clinical Treatment Outcomes: A Review

PubMed Central

Sigmon, Stacey C.; Strain, Eric C.; Heil, Sarah H.; Higgins, Stephen T.

2011-01-01

Background The association between buprenorphine taper duration and treatment outcomes is not well understood. This review evaluated whether duration of outpatient buprenorphine taper is significantly associated with treatment outcomes. Methods Studies that were published in peer-reviewed journals, administered buprenorphine as an outpatient taper to opioid-dependent participants, and provided data on at least one of three primary treatment outcome measures (opioid abstinence, retention, peak withdrawal severity) were reviewed. Primary treatment outcomes were evaluated as a function of taper duration using hierarchical linear regressions using pre-taper maintenance as a cofactor. Results Twenty-eight studies were reviewed. Taper duration significantly predicted percent of opioid-negative samples provided during treatment, however pre-taper maintenance period predicted percent participants abstinent on the final day of treatment. High rates of relapse were reported. No significant association between taper duration and retention in treatment or peak withdrawal severity was observed. Conclusion The data reviewed here suggest taper duration is associated with opioid abstinence achieved during detoxification but not with other markers of treatment outcome. The reviewed studies varied widely on several parameters (e.g., frequency of urinalysis testing, provision of ancillary medications) that may influence treatment outcome and thus could have interfered with the ability to identify relationships between taper duration and outcomes. Future studies evaluating opioid detoxification should utilize rigorous experimental methods and report a wider range of outcome measures in order to help advance our understanding of the association between taper duration and treatment outcomes. PMID:21741781

Non-contact printing of optical waveguides using capillary bridges.

PubMed

Theiler, Pius M; Lütolf, Fabian; Ferrini, Rolando

2018-04-30

Non-contact printing methods such as inkjet, electro hydrodynamic, and aerosol printing have attracted attention for their precise deposition of functional materials that are needed in printed electronics, optoelectronics, photonics, biotechnology, and microfluidics. In this article, we demonstrate printing of tapered optical waveguides with losses of 0.61 ± 0.26 dB/cm, with the best performing structure achieving 0.19 dB/cm. Such continuous features are indispensable for successfully printing functional patterns, but they are often corrupted by capillary forces. The proposed inkjet printing method uses these forces to align liquid bridges into continuous features, enabling the printing of smooth lines on substrates with arbitrary contact angles.

Integral method for the calculation of three-dimensional, laminar and turbulent boundary layers

NASA Technical Reports Server (NTRS)

Stock, H. W.

1978-01-01

The method for turbulent flows is a further development of an existing method; profile families with two parameters and a lag entrainment method replace the simple entrainment method and power profiles with one parameter. The method for laminar flows is a new development. Moment of momentum equations were used for the solution of the problem, the profile families were derived from similar solutions of boundary layer equations. Laminar and turbulent flows at the wings were calculated. The influence of wing tapering on the boundary layer development was shown. The turbulent boundary layer for a revolution ellipsoid is calculated for 0 deg and 10 deg incidence angles.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding Xueyong; Li Hongfan; Lv Zhensu

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

Effectiveness of Flow Control for Alleviation of Twin-Tail Buffet

NASA Technical Reports Server (NTRS)

Sheta, Essam F.; Kandil, Osama A.; Yang, Zhi

1998-01-01

Effectiveness of active flow control for twin- tail buffet alleviation is investigated. Tangen- tial leading-edge blowing (TLEB) and flow suction along the vortex cores (FSVC) of the lead- ing edges of the delta wing are used to delay the vortex breakdown flow upstream of the twin tail. The combined effect of the TLEB and FSVC is also investigated. A parametric study of the effects of the spanwise position of the suction tubes and volumetric suction flow rate on the twin-tail buffet response are also investigated. The TLEB moves the path of leading-edge vortices laterally towards the twin tail, which increases the aero- dynamic damping on the tails. The FSVC effectively delays the breakdown location at high angles of attack. The computational model consists of a sharp-edged delta wing of aspect ratio one and swept-back flexible twin tail with taper ratio of 0.23. This complex multidisciplinary problem is solved sequentially using three sets of equations for the fluid flow, aeroelastic response and grid deformation, on a dynamic multi-block grid structure. The computational model is pitched at 30 deg. angle of attack. The freestream Mach number and Reynolds number are 0.3 and 1.25 million, respectively. The model is investigated for the inboard position of the twin tails, which corresponds to a separation distance between the twin tails of 33% of the wing span.

Blue treatment enhances cyclic fatigue resistance of vortex nickel-titanium rotary files.

PubMed

Plotino, Gianluca; Grande, Nicola M; Cotti, Elisabetta; Testarelli, Luca; Gambarini, Gianluca

2014-09-01

The aim of the present study was to evaluate the difference in cyclic fatigue resistance between Vortex Blue (Dentsply Tulsa Dental, Tulsa, OK) and Profile Vortex nickel-titanium (Dentsply Tulsa Dental) rotary instruments. Two groups of nickel-titanium endodontic instruments, ProFile Vortex and Vortex Blue, consisting of identical instruments in tip size and taper (15/.04, 20/.06, 25/.04, 25/.06, 30/.06, 35/.06, and 40/.04) were tested. Ten instruments from each system and size were tested for cyclic fatigue resistance, resulting in a total of 140 new instruments. All instruments were rotated in a simulated root canal with a 60° angle of curvature and a 5-mm radius of curvature of a specific cyclic fatigue testing device until fracture occurred. The number of cycles to failure and the length of the fractured tip were recorded for each instrument in each group. The mean values and standard deviation were calculated, and data were subjected to 1-way analysis of variance and a Bonferroni t test. Significance was set at the 95% confidence level. When comparing the same size of the 2 different instruments, a statistically significant difference (P < .05) was noted between all sizes of Vortex Blue and Profile Vortex instruments except for tip size 15 and .04 taper (P = 1.000). No statistically significant difference (P > .05) was noted among all groups tested in terms of fragment length. Vortex Blue showed a significant increase in cyclic fatigue resistance when compared with the same sizes of ProFile Vortex. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Influence of axial movement on fatigue of PROFILE* NI-TI rotary instruments: an in vitro evaluation

PubMed Central

Avoaka, Marie-Chantal; Haïkel, Youssef

2010-01-01

The aim of this study was to evaluate the influence of the axial movement and the angle of curve (in degrees) on fatigue of nickel-titanium (Ni-Ti) ProFile’ rotary endodontic instruments. Ni-Ti ProFile’ rotary instruments (Maillefer SA, Ballaigues, Switzerland), 25 mm long in the range of ISO size 15 to 40 with two tapers (0.4 and 0.6) were evaluated. They are divided in two groups: the instruments with axial movement and those without axial movement. The system used to test the fatigue is maintained in mechanical conditions as close as possible to the clinical situation. The axial movement is in the order of 2mm in corono-apical direction with a frequency of 1Hz. The concave radii incorporating a notched V-form for guiding the instruments were: 5; 7,5 and 10 mm. The rotary system is mounted on an electric handpiece and rotated at 350 rpm speed as recommended by the manufacturers. The instruments are rotated until their separation, and the time, in seconds, is recorded. Statístícal evaluation is undertaken using a two-way t-test to identify significant differences between variables in the study (p <0,05). We found significant statistical difference (p<0,05) between Ni-Ti engine drive ProFile’ instruments incorporating an axial movement and the instruments without axial movement with the same radius of curvature, size and taper. The incorporation of the axial movement increases significantly the life-span of the ProFile’ rotary instruments. This should reduce the risk of the instrument separation during the endodontic treatment. PMID:20507289

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

PubMed

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

2016-01-01

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. To comparatively evaluate the amount of apically extruded debris with V-Taper, ProTaper Next, and the self-adjusting File (SAF) system. 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. 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). 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.

Gaussian Filtering with Tapered Oil-Filled Photonic Bandgap Fibers

NASA Astrophysics Data System (ADS)

Brunetti, A. C.; Scolari, L.; Weirich, J.; Eskildsen, L.; Bellanca, G.; Bassi, P.; Bjarklev, A.

2008-10-01

A tunable Gaussian filter based on a tapered oil-filled photonic crystal fiber is demonstrated. The filter is centered at λ = 1364 nm 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 increasing the temperature from 25 °C to 100 °C. The measurements are compared to a simulated spectrum obtained by means of a vectorial Beam Propagation Method model.

Effect of reciprocating file motion on microcrack formation in root canals: an SEM study.

PubMed

Ashwinkumar, V; Krithikadatta, J; Surendran, S; Velmurugan, N

2014-07-01

To compare dentinal microcrack formation whilst using Ni-Ti hand K-files, ProTaper hand and rotary files and the WaveOne reciprocating file. One hundred and fifty mandibular first molars were selected. Thirty teeth were left unprepared and served as controls, and the remaining 120 teeth were divided into four groups. Ni-Ti hand K-files, ProTaper hand files, ProTaper rotary files and WaveOne Primary reciprocating files were used to prepare the mesial canals. Roots were then sectioned 3, 6 and 9 mm from the apex, and the cut surface was observed under scanning electron microscope (SEM) and checked for the presence of dentinal microcracks. The control and Ni-Ti hand K-files groups were not associated with microcracks. In roots prepared with ProTaper hand files, ProTaper rotary files and WaveOne Primary reciprocating files, dentinal microcracks were present. There was a significant difference between control/Ni-Ti hand K-files group and ProTaper hand files/ProTaper rotary files/WaveOne Primary reciprocating file group (P < 0.001) with ProTaper rotary files producing the most microcracks. No significant difference was observed between teeth prepared with ProTaper hand files and WaveOne Primary reciprocating files. ProTaper rotary files were associated with significantly more microcracks than ProTaper hand files and WaveOne Primary reciprocating files. Ni-Ti hand K-files did not produce microcracks at any levels inside the root canals. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Electromagnetic field tapering using all-dielectric gradient index materials.

PubMed

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

2016-07-28

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

In-line optical fiber sensors based on cladded multimode tapered fibers.

PubMed

Villatoro, Joel; Monzón-Hernández, David; Luna-Moreno, Donato

2004-11-10

The use of uniform-waist cladded multimode tapered optical fibers is demonstrated for evanescent wave spectroscopy and sensors. The tapering is a simple, low-loss process and consists of stretching the fiber while it is being heated with an oscillating flame torch. As examples, a refractive-index sensor and a hydrogen sensor are demonstrated by use of a conventional graded-index multimode optical fiber. Also, absorbance spectra are measured while the tapers are immersed in an absorbing liquid. It is found experimentally that the uniform waist is the part of the taper that contributes most to the sensor sensitivity. The taper waist diameter may also be used to adjust the sensor dynamic range.

Tapered enlarged ends in multimode optical fibers.

PubMed

Brenci, M; Falciai, R; Scheggi, A M

1982-01-15

Radiation characteristics of multimode fibers with enlarged tapers were investigated on a number of samples obtained by varying the fiber drawing speed with a given law corresponding to a prefixed taper profile. The characterization of the fibers was made by near- and far-field intensity pattern measurements as well as by measuring the losses introduced by the taper. With a suitable choice of parameters the taper constitutes a reasonable low-loss component useful, for example, for either efficient coupling to large-spot high-power density sources or connecting fibers of different sizes. Conversely at the exit of the fiber the taper can be used for beam shaping which is of interest for mechanical or surgical applications.

Ultrastructure of the spermatozoon of Dipylidium caninum (Cestoda, Cyclophyllidea, Dilepididae), an intestinal parasite of Canis familiaris.

PubMed

Miquel, J; Marchand, B

1997-01-01

We report for the first time the ultrastructure of the spermatozoon of a Dilepididae cestode. The mature spermatozoa of Dipylidium caninum is filiform and tapered at both ends and lacks mitochondria. The anterior extremity exhibits an apical cone of electron-dense material measuring about 600 nm in length and a single helicoidal crested-like body that is 150 nm thick. This single crested-like body is spiralized at an angle of about 40 degrees to the spermatozoon axis. The axoneme, showing the 9 + "l" pattern of the Platyhelminthes, lacks a periaxonemal sheath. The cortical microtubules constitute a continuous, submembranous, electron-dense material, and they are also twisted at an angle of about 40 degrees to the spermatozoon axis. Moreover, the nucleus is coiled in a helix around the axoneme, which is centrally located throughout its length. We demonstrate for the first time the presence of peripheral microtubules twisted to the spermatozoon axis up to the posterior extremity of the gamete.

Utilizing laser interference lithography to fabricate hierarchical optical active nanostructures inspired by the blue Morpho butterfly

NASA Astrophysics Data System (ADS)

Siddique, Radwanul H.; Faisal, Abrar; Hünig, Ruben; Bartels, Carolin; Wacker, Irene; Lemmer, Uli; Hoelscher, Hendrik

2014-09-01

The famous non-iridescent blue of the Morpho butter by is caused by a `Christmas tree' like nanostructure which is a challenge for common fabrication techniques. Here, we introduce a method to fabricate this complex morphology utilizing dual beam interference lithography. We add a reflective coating below the photoresist to create a second interference pattern in vertical direction by exploiting the back reflection from the substrate. This vertical pattern exposes the lamella structure into the photosensitive polymer while the horizontal interference pattern determines the distance of the ridges. The photosensitive polymer is chosen accordingly to create the Christmas tree' like tapered shape. The resulting artificial Morpho replica shows brilliant non-iridescent blue up to an incident angle of 40. Its optical properties are close to the original Morpho structure because the refractive index of the polymer is close to chitin. Moreover, the biomimetic surface is water repellent with a contact angle of 110.

77 FR 45588 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the People's Republic of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-01

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-601] Tapered Roller Bearings and... new shipper review (``NSR'') of the antidumping duty order on tapered roller bearings from the People... The notice announcing the antidumping duty order on tapered roller bearings from the PRC was published...

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

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-04

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-601] Tapered Roller Bearings and... on tapered roller bearings (``TRBs'') from the People's Republic of China (``PRC'') meets the... published in the Federal Register on June 15, 1987. See Antidumping Duty Order; Tapered Roller Bearings and...

76 FR 45777 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the People's Republic of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-01

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-601] Tapered Roller Bearings and... tapered roller bearings (``TRBs'') from the People's Republic of China (``PRC'') meets the statutory and... Register on June 15, 1987. See Antidumping Duty Order; Tapered Roller Bearings and Parts Thereof, Finished...

Simple Expressions for the Design of Linear Tapers in Overmoded Corrugated Waveguides

DOE PAGES

Schaub, S. C.; Shapiro, M. A.; Temkin, R. J.

2015-08-16

In this paper, simple analytical formulae are presented for the design of linear tapers with very low mode conversion loss in overmoded corrugated waveguides. For tapers from waveguide radius a2 to a1, with a11a 2/λ. Here, λ is the wavelength of radiation. The fractional loss of the HE 11 mode in an optimized taper is 0.0293(a 2-a 1) 4/amore » $$2\\atop{1}$$1a$$2\\atop{2}$$. These formulae are accurate when a2≲2a 1. Slightly more complex formulae, accurate for a 2≤4a 1, are also presented in this paper. The loss in an overmoded corrugated linear taper is less than 1 % when a 2≤2.12a 1 and less than 0.1 % when a 2≤1.53a 1. The present analytic results have been benchmarked against a rigorous mode matching code and have been found to be very accurate. The results for linear tapers are compared with the analogous expressions for parabolic tapers. Finally, parabolic tapers may provide lower loss, but linear tapers with moderate values of a 2/a 1 may be attractive because of their simplicity of fabrication.« less

Enhancing sensitivity of biconical tapered fiber sensors with multiple passes through the taper

NASA Astrophysics Data System (ADS)

Cohoon, Gregory; Boyter, Chris; Errico, Michael; Vandervoort, Kurt; Salik, Ertan

2010-03-01

A single biconical fiber taper is a simple and low-cost yet powerful sensor. With a distinct strength in refractive index (RI) sensing, biconical tapered fiber sensors can find their place in handheld sensor platforms, especially as biosensors that are greatly needed in health care, environmental protection, food safety, and biodefense. We report doubling of sensitivity for these sensors with two passes through the tapered region, which becomes possible through the use of sensitive and high-dynamic-range photodetectors. In a proof-of-principle experiment, we measured transmission through the taper when it was immersed in isopropyl alcohol-water mixtures of varying concentrations, in which a thin gold layer at the tip of the fiber acted as a mirror enabling two passes through the tapered region. This improved the sensitivity from 0.43 dB/vol % in the single-pass case to 0.78 dB/vol % with two passes through the taper. The refractive index detection limit was estimated to be ~1.2×10-5 RI units (RIU) and ~0.6×10-5 RIU in the single- and double-pass schemes, respectively. We predict that further enhancement of sensitivity may be achieved with a higher number of passes through the taper.

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

PubMed Central

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

2016-01-01

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

Biomechanical Three-Dimensional Finite Element Analysis of Single Implant-Supported Prostheses in the Anterior Maxilla, with Different Surgical Techniques and Implant Types.

PubMed

Verri, Fellippo Ramos; Santiago, Joel Ferreira; Almeida, Daniel Augusto; de Souza Batista, Victor Eduardo; Araujo Lemos, Cleidiel Aparecido; Mello, Caroline Cantieri; Pellizzer, Eduardo Piza

The aim of this study was to use three-dimensional finite element analysis to analyze the stress distribution transferred by single implant-supported prostheses placed in the anterior maxilla using different connections (external hexagon, internal hexagon, or Morse taper), inclinations of the load (0, 30, or 60 degrees), and surgical techniques for placement (monocortical/conventional, bicortical, or bicortical with nasal floor elevation). Nine models representing a bone block of this region were simulated by computer-aided design software (InVesalius, Rhinoceros, SolidWorks). Each model received one implant, which supported a cemented metalloceramic crown. Using FEMAP software, finite elements were discretized while simulating a 178-N load at 0, 30, and 60 degrees relative to the long axis of the implant. The problem was solved in NEi Nastran software, and postprocessing was performed in FEMAP. Von Mises stress and maximum principal stress maps were made. The von Mises stress analysis revealed that stress increased with increasing inclination of the load, from 0 to 30 to 60 degrees. Morse taper implants showed less stress concentration around the cervical and apical areas of the implant. The bicortical technique, associated or not with nasal floor elevation, contributed to decreasing the stress concentration in the apical area of the implant. Maximum principal stress analysis showed that the increase in inclination was proportional to the increase in stress on the bone tissue in the cervical area. Lower stress concentrations in the cortical bone were obtained with Morse taper implants and the bicortical technique compared with other connections and surgical techniques, respectively. Increasing the inclination of the applied force relative to the long axis of the implant tended to overload the peri-implant bone tissue and the internal structure of the implants. The Morse taper connection and bicortical techniques seemed to be more favorable than other connections or techniques, respectively, for restoring the anterior maxilla.

Endodontic shaping performance using nickel-titanium hand and motor ProTaper systems by novice dental students.

PubMed

Tu, Ming-Gene; Chen, San-Yue; Huang, Heng-Li; Tsai, Chi-Cheng

2008-05-01

Preparing a continuous tapering conical shape and maintaining the original shape of a canal are obligatory in root canal preparation. The purpose of this study was to compare the shaping performance in simulated curved canal resin blocks of the same novice dental students using hand-prepared and engine-driven nickel-titanium (NiTi) rotary ProTaper instruments in an endodontic laboratory class. Twenty-three fourth-year dental students attending China Medical University Dental School prepared 46 simulated curved canals in resin blocks with two types of NiTi rotary systems: hand and motor ProTaper files. Composite images were prepared for estimation. Material removed, canal width and canal deviation were measured at five levels in the apical 4 mm of the simulated curved canals using AutoCAD 2004 software. Data were analyzed using Wilcoxon's rank-sum test. The hand ProTaper group cut significantly wider than the motor rotary ProTaper group in the outer wall, except for the apical 0 mm point. The total canal width was cut significantly larger in the hand group than in the motor group. There was no significant difference between the two groups in centering canal shape, except at the 3 mm level. These findings show that the novice students prepared the simulated curved canal that deviated more outwardly from apical 1 mm to 4 mm using the hand ProTaper. The ability to maintain the original curvature was better in the motor rotary ProTaper group than in the hand ProTaper group. Undergraduate students, if following the preparation sequence carefully, could successfully perform canal shaping by motor ProTaper files and achieve better root canal geometry than by using hand ProTaper files within the same teaching and practicing sessions.

Parametric Fin-Body and Fin-Plate Database for a Series of 12 Missile Fins

NASA Technical Reports Server (NTRS)

Allen, Jerry M.

2001-01-01

A cooperative experimental investigation has been performed to obtain a systematic fin-body and fin-plate database for a series of 12 missile fins. These data are intended to complement and extend the information contained in the Triservice missile project and to provide a systematic set of experimental data from which fin-body interference factors can be derived. Data were obtained with the fins mounted on both an axisymmetric body and on a flat plate that was used to simulate fin-alone measurements. The experiments were conducted at Mach numbers from 0.60 to 3.95; fin deflection angles of 0 deg, 10 deg, and -10 deg; and angles of attack up to 30 deg on the body and up to 95 deg on the flat plate. The data were obtained from three-component balances attached to the fins and a six-component balance located in the axisymmetric body. The data obtained in this project are documented in tabular form in this report. In addition, selected data are presented in graphical form to illustrate the effects of the test variables. These variables are configuration angle of attack; Mach number; and fin parameters of deflection angle, planform size, taper ratio, and aspect ratio. A very limited comparison with the Triservice missile data is made to illustrate the consistency between the data from these two projects.

The role of heterogeneous fluid pressures in the shape of critical-taper submarine wedges, with application to Barbados

NASA Astrophysics Data System (ADS)

Yeh, En-Chao; Suppe, John

2014-05-01

Some classic accretionary wedges such as Nankai trough and Barbados are mechanically heterogeneous based on their spatial variation in taper, showing inward decrease in surface slope α without covariation in detachment dip β. Possible sources of regional heterogeniety include variation in fluid pressure, density, cohesion and fault strength, which can be constrained by the seismic or borehole observable parameter, fluid-retention depth Z_FRD, below which compaction is strongly diminished. In particular the Hubbert-Rubey fluid-pressure weakening can be addressed as (1-lambda)~0.6Z_FRD/Z. We recast the heterogeneous critical-taper wedge theory of Dahlen (1990) in terms of the observable Z_FRD/H, where H is the detachment depth, which allows for real world applications. For example, seismic velocity and borehole data from the Barbados shows that the fluid-retention depth Z_FRD is approximately constant and Z_FRD/H decreases inward. This leads to a factor of four inward decreases in wedge strength, dominated by fluid pressure, with only a second-order role for density and cohesion. An inward decrease in wedge strength should by itself produce an increase in taper, therefore the observed decreasing taper must be dominated by decreasing fault strength mu_b* from 0.03 to 0.01. Static fluid-pressures along the detachment in equilibrium with the overlying wedge predict the observed wedge geometry well, given a constant intrinsic friction coefficient mu_b=0.15.

Diagnostics of electron-heated solar flare models. III - Effects of tapered loop geometry and preheating

NASA Technical Reports Server (NTRS)

Emslie, A. G.; Li, Peng; Mariska, John T.

1992-01-01

A series of hydrodynamic numerical simulations of nonthermal electron-heated solar flare atmospheres and their corresponding soft X-ray Ca XIX emission-line profiles, under the conditions of tapered flare loop geometry and/or a preheated atmosphere, is presented. The degree of tapering is parameterized by the magnetic mirror ratio, while the preheated atmosphere is parameterized by the initial upper chromospheric pressure. In a tapered flare loop, it is found that the upward motion of evaporated material is faster compared with the case where the flare loop is uniform. This is due to the diverging nozzle seen by the upflowing material. In the case where the flare atmosphere is preheated and the flare geometry is uniform, the response of the atmosphere to the electron collisional heating is slow. The upward velocity of the hydrodynamic gas is reduced due not only to the large coronal column depth, but also to the increased inertia of the overlying material. It is concluded that the only possible electron-heated scenario in which the predicted Ca XIX line profiles agree with the BCS observations is when the impulsive flare starts in a preheated dense corona.

Soliton propagation in tapered silicon core fibers.

PubMed

Peacock, Anna C

2010-11-01

Numerical simulations are used to investigate soliton-like propagation in tapered silicon core optical fibers. The simulations are based on a realistic tapered structure with nanoscale core dimensions and a decreasing anomalous dispersion profile to compensate for the effects of linear and nonlinear loss. An intensity misfit parameter is used to establish the optimum taper dimensions that preserve the pulse shape while reducing temporal broadening. Soliton formation from Gaussian input pulses is also observed--further evidence of the potential for tapered silicon fibers to find use in a range of signal processing applications.

Monitoring techniques for the manufacture of tapered optical fibers.

PubMed

Mullaney, Kevin; Correia, Ricardo; Staines, Stephen E; James, Stephen W; Tatam, Ralph P

2015-10-01

The use of a range of optical techniques to monitor the process of fabricating optical fiber tapers is investigated. Thermal imaging was used to optimize the alignment of the optical system; the transmission spectrum of the fiber was monitored to confirm that the tapers had the required optical properties and the strain induced in the fiber during tapering was monitored using in-line optical fiber Bragg gratings. Tapers were fabricated with diameters down to 5 μm and with waist lengths of 20 mm using single-mode SMF-28 fiber.

Mode conversion in a tapered fiber via a whispering gallery mode resonator and its application as add/drop filter.

PubMed

Huang, Ligang; Wang, Jie; Peng, Weihua; Zhang, Wending; Bo, Fang; Yu, Xuanyi; Gao, Feng; Chang, Pengfa; Song, Xiaobo; Zhang, Guoquan; Xu, Jingjun

2016-02-01

Based on the conversion between the fundamental mode (LP01) and the higher-order mode (LP11) in a tapered fiber via a whispering gallery mode resonator, an add/drop filter was proposed and demonstrated experimentally, in which the resonator only interacted with one tapered fiber, rather than two tapered fibers as in conventional configurations. The filter gains advantages of easy alignment and low scattering loss over the other filters based on tapered fiber and resonator, and will be useful in application.

The fabrication of a tapered fiber connector and its coupling efficiency

NASA Astrophysics Data System (ADS)

Qinggui, Hu; Chengzhong, Li

2017-11-01

In order to reduce the adverse influence of transversal displacement of the optical fiber connector, we propose the directional tapered communication fiber connector, in which the fiber head is tapered according to the signal transmission direction to improve efficiency. We used a flame-brush technique to produce the tapered fiber successfully. In the next step, two experiments in different environments were performed; one in a static environment and the other in a vibration environment. The first experiment shows that the efficiency of the tapered connector is higher than that of the common connector in the same transversal displacement. The second experiment shows that the efficiency of the tapered connector is higher than that of the common connector in the same frequency and amplitude.

Multiple-taper spectral analysis: A stand-alone C-subroutine

NASA Astrophysics Data System (ADS)

Lees, Jonathan M.; Park, Jeffrey

1995-03-01

A simple set of subroutines in ANSI-C are presented for multiple taper spectrum estimation. The multitaper approach provides an optimal spectrum estimate by minimizing spectral leakage while reducing the variance of the estimate by averaging orthogonal eigenspectrum estimates. The orthogonal tapers are Slepian nπ prolate functions used as tapers on the windowed time series. Because the taper functions are orthogonal, combining them to achieve an average spectrum does not introduce spurious correlations as standard smoothed single-taper estimates do. Furthermore, estimates of the degrees of freedom and F-test values at each frequency provide diagnostics for determining levels of confidence in narrow band (single frequency) periodicities. The program provided is portable and has been tested on both Unix and Macintosh systems.

Bolus administration of steroid therapy is more favorable than the conventional use in preventing decrease of bone density and the increase of body fat percentage in patients with inflammatory bowel disease.

PubMed

Farkas, Klaudia; Bálint, Anita; Valkusz, Zsuzsanna; Szepes, Zoltán; Nagy, Ferenc; Szűcs, Mónika; Bor, Renáta; Wittmann, Tibor; Molnár, Tamás

2014-09-01

The effects of short course of corticosteroids on the metabolic processes and bone formation has not been well studied. Our aim was to compare the efficacy, the side effects and the bone and lipid metabolisms in IBD patients using bolus or conventional tapering of methylprednisolone for 12 weeks. Nineteen IBD patients received intravenous methylprednisolone of 1mg/kg for 5 days tapered by 4 mg per week. Patients were prospectively randomized in two groups. In "conventional" group (I) steroids were given daily. In "pulse" group (II) weekly doses of steroids were given on special days of the week. The body mass index (BMI) was measured before and after the corticosteroid therapy. Blood samples were collected to assess glucose level, electrolytes, cholesterol and triglyceride levels, inflammatory parameters, cortisol, osteocalcin and crosslaps values. Total body composition analysis was performed at the beginning and at the end of the steroid therapy. In Group I, BMI increased, total body bone density decreased significantly at the end of the steroid therapy. Body fat percent showed a tendency to be higher at the end of steroid therapy in Group I. Cholesterol level increased significantly in Group I patients. The decrease in serum cortisol level was more remarkable in Group I vs. Group II after steroid therapy. Less side-effect occurred in Group II vs. Group I. Our results suggest that bolus tapering of corticosteroids may have more favorable short term outcome than conventional tapering that may revolutionize steroid therapy in IBD. Copyright © 2014 European Crohn's and Colitis Organisation. Published by Elsevier B.V. All rights reserved.

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

NASA Technical Reports Server (NTRS)

Murri, Gretchen B.

1999-01-01

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

Levitating spherical particle in a slightly tapered tube at low Reynolds numbers: application to the low-flow rate rotameters.

PubMed

Champmartin, S; Ambari, A; Chhabra, R P

2012-12-01

In this study, a theoretical framework is developed to predict the equilibrium conditions of a non-neutrally buoyant sphere placed in a vertical conical tube as encountered in liquid rotameters. The analysis presented herein is applicable for a sphere heavier than the surrounding fluid, situated on the axis of a slightly tapered tube. The sphere is subject to the laminar flow conditions with the Reynolds numbers ranging between the Stokes type regimes up to values corresponding to slightly inertial regimes. In this work, we assume that the aperture angle of the tube is small and that the drag force is mainly due to the dissipation located in the gap between the tube and the sphere. Under these conditions, it is possible to consider the tube as locally cylindrical and we can use the results previously obtained for the correction factor of the Stokes force on a sphere subject to a Poiseuille flow in a tube of constant cross-section. We obtain an equation relating the flow rate to the vertical position of the sphere in the tube and the validity of this analysis is demonstrated by applying it to a commercially available rotameter. The present study provides a simple but sound theoretical method to calibrate such flowmeters.

A mathematical model for describing the mechanical behaviour of root canal instruments.

PubMed

Zhang, E W; Cheung, G S P; Zheng, Y F

2011-01-01

The purpose of this study was to establish a general mathematical model for describing the mechanical behaviour of root canal instruments by combining a theoretical analytical approach with a numerical finite-element method. Mathematical formulas representing the longitudinal (taper, helical angle and pitch) and cross-sectional configurations and area, the bending and torsional inertia, the curvature of the boundary point and the (geometry of) loading condition were derived. Torsional and bending stresses and the resultant deformation were expressed mathematically as a function of these geometric parameters, modulus of elasticity of the material and the applied load. As illustrations, three brands of NiTi endodontic files of different cross-sectional configurations (ProTaper, Hero 642, and Mani NRT) were analysed under pure torsion and pure bending situation by entering the model into a finite-element analysis package (ANSYS). Numerical results confirmed that mathematical models were a feasible method to analyse the mechanical properties and predict the stress and deformation for root canal instruments during root canal preparation. Mathematical and numerical model can be a suitable way to examine mechanical behaviours as a criterion of the instrument design and to predict the stress and strain experienced by the endodontic instruments during root canal preparation. © 2010 International Endodontic Journal.

Levitating spherical particle in a slightly tapered tube at low Reynolds numbers: Application to the low-flow rate rotameters

NASA Astrophysics Data System (ADS)

Champmartin, S.; Ambari, A.; Chhabra, R. P.

2012-12-01

In this study, a theoretical framework is developed to predict the equilibrium conditions of a non-neutrally buoyant sphere placed in a vertical conical tube as encountered in liquid rotameters. The analysis presented herein is applicable for a sphere heavier than the surrounding fluid, situated on the axis of a slightly tapered tube. The sphere is subject to the laminar flow conditions with the Reynolds numbers ranging between the Stokes type regimes up to values corresponding to slightly inertial regimes. In this work, we assume that the aperture angle of the tube is small and that the drag force is mainly due to the dissipation located in the gap between the tube and the sphere. Under these conditions, it is possible to consider the tube as locally cylindrical and we can use the results previously obtained for the correction factor of the Stokes force on a sphere subject to a Poiseuille flow in a tube of constant cross-section. We obtain an equation relating the flow rate to the vertical position of the sphere in the tube and the validity of this analysis is demonstrated by applying it to a commercially available rotameter. The present study provides a simple but sound theoretical method to calibrate such flowmeters.

An Investigation of Wing and Aileron Loads Due to Deflected Inboard and Outboard Ailerons on a 4-Percent-Thick 30 deg Sweptback Wing at Transonic Speeds

NASA Technical Reports Server (NTRS)

Whitcomb, Charles F.; Critzos, Chris C.; Brown, Philippa F.

1961-01-01

An investigation has been conducted in the Langley 16-foot transonic tunnel to determine the changes in wing loading characteristics due to deflections of a plain faired flap-type inboard aileron, a plain faired flap-type outboard aileron, and a slab-sided thickened trailing edge outboard aileron. The test wing was 4 percent thick and had 30 sweep of the quarter chord, an aspect ratio of 3.0, a taper ratio of 0.2, and NACA 65A004 airfoil sections. The loading characteristics of the deflected ailerons were also investigated. The model was a sting-mounted wing-body combination, and pressure measurements over one wing panel (exposed area) and the ailerons were obtained for angles of attack from 0 to 20 at deflections up to +/- 15 deg for Mach numbers between 0.80 and 1.03. The test Reynolds number based on the wing mean aerodynamic chord was about 7.4 x 10(exp 6). The results of the investigation indicated that positive deflection of the plain faired flap-type inboard aileron caused significant added loading over the wing sections outboard of the aileron at all Mach numbers for model angles of attack from 0 deg or 4 deg up to 12 deg. Positive deflection of the two outboard ailerons (plain faired and slab sided with thickened trailing edge) caused significant added loading over the wing sections inboard of the ailerons for different model angle-of-attack ranges at the several test Mach numbers. The loading shapes over the ailerons were irregular and would be difficult to predict from theoretical considerations in the transonic speed range. The longitudinal and lateral center-of-pressure locations for the ailerons varied only slightly with increasing angle of attack and/or Mach number. Generally, the negative slopes of the variations of aileron hinge-moment coefficient with aileron deflection for all three ailerons varied similarly with Mach number at the test angles of attack.

Structural evolution of self-ordered alumina tapered nanopores with 100 nm interpore distance

NASA Astrophysics Data System (ADS)

Li, Juan; Li, Congshan; Gao, Xuefeng

2011-10-01

We in-detail investigated the profile evolution processes of highly ordered alumina under the cyclic treatment of mild anodizing of aluminum foils in oxalic acid followed by etching in phosphoric acid. With the cyclic times increasing, the profiles of nanopores were gradually evolved into the parabola-like, trumpet-like and conical shape. Although the inserted etching itself nearly had no impact on the growth rate of the nanopores due to the rapid recovering of thinned barrier layer at the initial stage of next anodizing, overmuch etching could bring apparent side effects such as wall-breaking, thinning and taper-removing from the top down. The anodizing and etching kinetics and their synergetic effects in modulating different aspect ratios and open sizes of conical pores were studied systematically. These findings are helpful to tailor high-quality anodic alumina taper-pores with tunable profiles.

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

PubMed

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.

Tapered fiber based Brillouin random fiber laser and its application for linewidth measurement.

PubMed

Gao, Song; Zhang, Liang; Xu, Yanping; Lu, Ping; Chen, Liang; Bao, Xiaoyi

2016-12-12

A one-end pumping Brillouin random fiber laser (BRFL) based on a 5-km tapered fiber (TF) is demonstrated. The enhanced Rayleigh scattering and the increased power density from tapering in the TF provide good directionality and a high degree of coherent feedback. Both the transmitting and TF enhanced Rayleigh scattered pump lights formed effective bi-direction pumping for the Brillouin gain in the standing cavity configuration in the distributed way as the gain and random feedback in the same fiber. The linewidth of the laser shows ~1.17 kHz while the relative intensity noise (RIN) has been verified to be suppressed comparing with that of the two-end pumping of the standard single mode fiber (SMF). Furthermore, utilizing the proposed laser, a high-resolution (~kHz) linewidth measurement method is demonstrated without long delay fiber (>100km) and extra frequency shifter thanks to the acoustic frequency shift from fiber itself.

Effect of apical size and taper on volume of irrigant delivered at working length with apical negative pressure at different root curvatures.

PubMed

de Gregorio, Cesar; Arias, Ana; Navarrete, Natalia; Del Rio, Veronica; Oltra, Enrique; Cohenca, Nestor

2013-01-01

The purpose of this investigation was to determine the effect that apical preparation size and preparation taper have on the volume of irrigant delivered at the working length for different canal curvatures using apical negative pressure irrigation. One hundred fifty-five human teeth (55 maxillary canines and 100 mandibular molars) were used in this study. Root canals were prepared with rotary instruments to a size 35.04 and separated into 3 experimental groups according to their degree of curvature: group A (n = 50) included canal curvatures ranging from 0° to 10°, group B (n = 50) from 11° to 30°, and group C (n = 50) from 31° to 65°. Samples of each curvature group were further randomized to experimental subgroups according to the apical size and taper as follow: 35.06, 40.04, 40.06, 45.04, and 45.06. The apical third was irrigated using a microcannula and the volume of NaOCl suctioned at the working length under negative pressure was measured over a period of 30 seconds using a fluid recovery trap. Positive controls consisted of measuring the maximum volume of 5.25% NaOCl capable of being suctioned by the microcannula from an open glass vial over 30 seconds. Negative control was the volume of irrigant aspirated by the microcannula with a preparation size of 25.04 over 30 seconds. The volume of irrigant was significantly greater when the apical preparation size increased from 35.06 to 40.04. As the apical preparation taper increased further from 40.04 to 40.06, the volume of irrigant significantly improved in group B, but it was not significant in group A. Apical preparation sizes greater than 40.06 did not show an increase of the volume of irrigant aspirated. The degree of root canal curvature decreased the volume of irrigant at the working length for a given apical size and taper. An apical preparation of 40.06 significantly increased the volume and exchange of irrigant at the working length regardless of curvature. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Comparative evaluation of rotary ProTaper, Profile, and conventional stepback technique on reduction in Enterococcus faecalis colony-forming units and vertical root fracture resistance of root canals.

PubMed

Singla, Mamta; Aggarwal, Vivek; Logani, Ajay; Shah, Naseem

2010-03-01

The purpose of this in vitro study was to evaluate the effect of various root canal instrumentation techniques with different instrument tapers on cleaning efficacy and resultant vertical root fracture (VRF) strength of the roots. Fifty human mandibular first premolar roots were enlarged to ISO size 20, inoculated with Enterococcus faecalis [ATCC2912] for 72 hours and divided into 5 groups: group I: prepared with .02 taper hand instruments ISO size 40; group II: Profile .04 taper size 40; group III: Profile .06 taper size 40; group IV: ProTaper size F4; and group V (control group) further divided into: Va: with bacterial inoculation and no mechanical instrumentation; and Group Vb: neither bacterial inoculation nor mechanical instrumentation. Cleaning efficacy was evaluated in terms of reduction of colony forming units (CFUs). The VRF strength was evaluated using D11 spreader as wedge in an Instron testing machine. Root canals instrumented with ProTaper and 6% Profile instruments showed maximum reduction in CFUs, with statistically insignificant difference between them. The VRF resistance decreased in all instrumented groups. The difference of VRF between 2% and 4% taper Profile groups was statistically insignificant (P = .195). One-way analysis of variance showed that canals instrumented with ProTaper F4 showed maximum reduction in VRF resistance compared with control uninstrumented group. Profile 6% taper instruments offer the advantage of maximum debridement without significant reduction in root fracture resistance. Copyright 2010 Mosby, Inc. All rights reserved.

The effect of screw taper on interference fit during load to failure at the soft tissue/bone interface.

PubMed

Mann, Charles J; Costi, John J; Stanley, Richard M; Dobson, Peter J

2005-10-01

The effect of screw geometry on the pullout strength of an anterior cruciate ligament reconstruction is well documented. The effect of a truly tapered screw has not been previously investigated. Thirty bovine knees in right and left knee pairs were collected. Superficial digital flexors from the hind legs of sheep were harvested to form a quadruple tendon graft. For each knee pair, one tendon graft was fixed using a tapered screw (n=15) and the other with a non-tapered screw (n=15). Interference screws were manufactured from stainless steel, and apart from the tapered or non-tapered profile were identical. The screws were inserted into a tibial tunnel already containing the tendon graft. The interference fit was tested by extensile load to failure tests. The insertion torque of the screws and first sign of load to failure (by pullout) of the interference fit were recorded. Results were analysed using paired t-tests. The results indicated that tapered screws have significantly higher resistance to interference failure (p=0.007) and insertion torque (p<0.001) than non-tapered screws. The improved biomechanical performance of tapered screws demonstrated in this study may translate into superior clinical results, particularly at the tibial attachment of hamstring anterior cruciate ligament reconstruction, and also of hamstring fixation to the medial femoral condyle for patella instability.

Hand-operated and rotary ProTaper instruments: a comparison of working time and number of rotations in simulated root canals.

PubMed

Pasqualini, Damiano; Scotti, Nicola; Tamagnone, Lorenzo; Ellena, Federica; Berutti, Elio

2008-03-01

The aim of this study was to compare the effective shaping time and number of rotations required by an endodontist working with hand and rotary ProTaper instruments to completely shape simulated root canals. Eighty Endo Training Blocks (curved canal shape) were used. Manual preflaring was performed with K-Flexofiles #08-10-12-15-17 and #20 Nitiflex at a working length of 18 mm. Specimens were then randomly assigned to 2 different groups (n = 40); group 1 was shaped by using hand ProTaper and group 2 with ProTaper rotary. The number of rotations made in the canal and the effective time required to achieve complete canal shaping were recorded for each instrument. Differences between groups were analyzed with the nonparametric Mann-Whitney U test (P < .05). Hand ProTaper required significantly fewer rotations (P < .001) than rotary ProTaper, whereas the effective working time to fully shape the simulated canal was significantly higher (P < .001) with hand ProTaper.

1.4-7.2  μm broadband supercontinuum generation in an As-S chalcogenide tapered fiber pumped in the normal dispersion regime.

PubMed

Wang, Yingying; Dai, Shixun; Li, Guangtao; Xu, Dong; You, Chenyang; Han, Xin; Zhang, Peiqing; Wang, Xunsi; Xu, Peipeng

2017-09-01

We report a broadband supercontinuum (SC) generation in chalcogenide (ChG) step-index tapered fibers pumped in the normal dispersion regime. The fibers consisting of As 2 S 3 core and As 38 S 62 cladding glasses were fabricated using the isolated stacked extrusion method. A homemade tapering platform allows us to accurately control the core diameters and transition region lengths of the tapered fibers. An SC generation spanning from 1.4 to 7.2 μm was achieved by pumping a 12-cm-long tapered fiber with femtosecond laser pulses at 3.25 μm. To the best of our knowledge, this is the broadest SC generation obtained experimentally in tapered fibers when pumped in the normal dispersion regime so far. The effects of waist diameter and transition region length of the tapered fiber on the SC spectral behavior were also investigated.

A 160 W single-frequency laser based on an active tapered double-clad fiber amplifier

NASA Astrophysics Data System (ADS)

Trikshev, A. I.; Kurkov, A. S.; Tsvetkov, V. B.; Filatova, S. A.; Kertulla, J.; Filippov, V.; Chamorovskiy, Yu K.; Okhotnikov, O. G.

2013-06-01

We present a CW single-frequency laser at 1062 nm (linewidth <3 MHz) with 160 W of total output power based on a two stage fiber amplifier. A GTWave fiber is used for the first stage of the amplifier. A tapered double-clad fiber (T-DCF) is used for the second stage of the amplifier. The high output power is achieved due to the amplified spontaneous emission (ASE) filtering and increased stimulated Brillouin scattering (SBS) threshold inherent to the axially non-uniform geometry.

Ultra-low-loss optical fiber nanotapers.

PubMed

Brambilla, Gilberto; Finazzi, Vittoria; Richardson, David

2004-05-17

Optical fiber tapers with a waist size larger than 1microm are commonplace in telecommunications and sensor applications. However the fabrication of low-loss optical fiber tapers with subwavelength diameters was previously thought to be impractical due to difficulties associated with control of the surface roughness and diameter uniformity. In this paper we show that very-long ultra-low-loss tapers can in fact be produced using a conventional fiber taper rig incorporating a simple burner configuration. For single-mode operation, the optical losses we achieve at 1.55microm are one order of magnitude lower than losses previously reported in the literature for tapers of a similar size. SEM images confirm excellent taper uniformity. We believe that these low-loss structures should pave the way to a whole range of fiber nanodevices.

Out-of-plane dynamic stability analysis of curved beams subjected to uniformly distributed radial loading

NASA Astrophysics Data System (ADS)

Sabuncu, M.; Ozturk, H.; Cimen; S.

2011-04-01

In this study, out-of-plane stability analysis of tapered cross-sectioned thin curved beams under uniformly distributed radial loading is performed by using the finite-element method. Solutions referred to as Bolotin's approach are analysed for dynamic stability, and the first unstable regions are examined. Out-of-plane vibration and out-of-plane buckling analyses are also studied. In addition, the results obtained in this study are compared with the published results of other researchers for the fundamental frequency and critical lateral buckling load. The effects of subtended angle, variations of cross-section, and dynamic load parameter on the stability regions are shown in graphics

Optimal Shape of a Gamma-ray Collimator: single vs double knife edge

NASA Astrophysics Data System (ADS)

Metz, Albert; Hogenbirk, Alfred

2017-09-01

Gamma-ray collimators in nuclear waste scanners are used for selecting a narrow vertical segment in activity measurements of waste vessels. The system that is used by NRG uses tapered slit collimators of both the single and double knife edge type. The properties of these collimators were investigated by means of Monte Carlo simulations. We found that single knife edge collimators are highly preferable for a conservative estimate of the activity of the waste vessels. These collimators show much less dependence on the angle of incidence of the radiation than double knife edge collimators. This conclusion also applies to cylindrical collimators of the single knife edge type, that are generally used in medical imaging spectroscopy.

Effect of Weld Tool Geometry on Friction Stir Welded AA2219-T87 Properties

NASA Technical Reports Server (NTRS)

Querin, Joseph A.; Schneider, Judy A.

2008-01-01

In this study, flat panels of AA2219-T87 were friction stir welded (FSWed) using weld tools with tapered pins The three pin geometries of the weld tools included: 0 (straight cylinder), 30 , and 60 angles on the frustum. For each weld tool geometry, the FSW process parameters were optimized to eliminate defects. A constant heat input was maintained while varying the process parameters of spindle rpm and travel speed. This provided a constant heat input for each FSW weld panel while altering the hot working conditions imparted to the workpiece. The resulting mechanical properties were evaluated from tensile test results of the FSW joint.

A novel photonic crystal fiber Mach-Zehnder interferometer for enhancing refractive index measurement sensitivity

NASA Astrophysics Data System (ADS)

Zhao, Yong; Xia, Feng; Hu, Hai-feng; Chen, Mao-qing

2017-11-01

A novel refractive index (RI) sensor based on photonic crystal fiber Mach-Zehnder interferometer (PCF-MZI) was proposed. It was realized by cascading a section of PCF with half-taper collapse regions (HTCRs) between two single mode fibers (SMFs). The relationship between RI sensitivity and interference length of the PCF-MZI was firstly investigated. Both simulation and experimental results showed that RI sensitivity increased with the increase of interference length. Afterwards, influence of HTCR parameters on RI sensitivity was experimentally investigated to further improve the sensitivity. With intensification of arc discharge intensity in HTCR fabrication process, HTCR with larger maximum taper diameter and longer collapsed region length was obtained, which enhanced evanescent field of the PCF-MZI and then generated higher RI sensitivity. Consequently, a high RI sensitivity of 181.96 nm/refractive index unit (RIU) was achieved in the RI range of 1.3333-1.3574. Increasing arc discharge intensity in HTCR fabrication process has the capacity to improve RI sensitivity of PCF-MZI and meanwhile provides higher mechanical strength and longer sensor life compared to the traditional method of tapering the fiber, which improves the RI sensitivity at the cost of reducing mechanical strength of the sensor. This PCF-MZI was characterized by high RI sensitivity, ease of fabrication, high mechanical strength, and robustness.

Functional significance of the taper of vertebrate cone photoreceptors

PubMed Central

Hárosi, Ferenc I.

2012-01-01

Vertebrate photoreceptors are commonly distinguished based on the shape of their outer segments: those of cones taper, whereas the ones from rods do not. The functional advantages of cone taper, a common occurrence in vertebrate retinas, remain elusive. In this study, we investigate this topic using theoretical analyses aimed at revealing structure–function relationships in photoreceptors. Geometrical optics combined with spectrophotometric and morphological data are used to support the analyses and to test predictions. Three functions are considered for correlations between taper and functionality. The first function proposes that outer segment taper serves to compensate for self-screening of the visual pigment contained within. The second function links outer segment taper to compensation for a signal-to-noise ratio decline along the longitudinal dimension. Both functions are supported by the data: real cones taper more than required for these compensatory roles. The third function relates outer segment taper to the optical properties of the inner compartment whereby the primary determinant is the inner segment’s ability to concentrate light via its ellipsoid. In support of this idea, the rod/cone ratios of primarily diurnal animals are predicted based on a principle of equal light flux gathering between photoreceptors. In addition, ellipsoid concentration factor, a measure of ellipsoid ability to concentrate light onto the outer segment, correlates positively with outer segment taper expressed as a ratio of characteristic lengths, where critical taper is the yardstick. Depending on a light-funneling property and the presence of focusing organelles such as oil droplets, cone outer segments can be reduced in size to various degrees. We conclude that outer segment taper is but one component of a miniaturization process that reduces metabolic costs while improving signal detection. Compromise solutions in the various retinas and retinal regions occur between ellipsoid size and acuity, on the one hand, and faster response time and reduced light sensitivity, on the other. PMID:22250013

Three-dimensional patterning in polymer optical waveguides using focused ion beam milling

NASA Astrophysics Data System (ADS)

Kruse, Kevin; Burrell, Derek; Middlebrook, Christopher

2016-07-01

Waveguide (WG) photonic-bridge taper modules are designed for symmetric planar coupling between silicon WGs and single-mode fibers (SMFs) to minimize photonic chip and packaging footprint requirements with improving broadband functionality. Micromachined fabrication and evaluation of polymer WG tapers utilizing high-resolution focused ion beam (FIB) milling is performed and presented. Polymer etch rates utilizing the FIB and optimal methods for milling polymer tapers are identified for three-dimensional patterning. Polymer WG tapers with low sidewall roughness are manufactured utilizing FIB milling and optically tested for fabrication loss. FIB platforms utilize a focused beam of ions (Ga+) to etch submicron patterns into substrates. Fabricating low-loss polymer WG taper prototypes with the FIB before moving on to mass-production techniques provides theoretical understanding of the polymer taper and its feasibility for connectorization devices between silicon WGs and SMFs.

Apically extruded debris with three contemporary Ni-Ti instrumentation systems: an ex vivo comparative study.

PubMed

Logani, Ajay; Shah, Naseem

2008-01-01

To comparatively evaluate the amount of apically extruded debris when ProTaper hand, ProTaper rotary and ProFile systems were used for the instrumentation of root canals. Thirty minimally curved, mature, human mandibular premolars with single canals were randomly divided into three groups of ten teeth each. Each group was instrumented using one of the three instrumentation systems: ProTaper hand, ProTaper rotary and ProFile. Five milliliters of sterile water were used as an irrigant. Debris extruded was collected in preweighed polyethylene vials and the extruded irrigant was evaporated. The weight of the dry extruded debris was established by comparing the pre- and postinstrumentation weight of polyethylene vials for each group. The Kruskal-Wallis nonparametric test and Mann-Whitney U test were applied to determine if significant differences existed among the groups ( P< 0.05). All instruments tested produced a measurable amount of debris. No statistically significant difference was observed between ProTaper hand and ProFile system ( P > 0.05). Although ProTaper rotary extruded a relatively higher amount of debris, no statistically significant difference was observed between this type and the ProTaper hand instruments ( P > 0.05). The ProTaper rotary extruded significantly more amount of debris compared to the ProFile system ( P< 0.05). Within the limitations of this study, it can be concluded that all instruments tested produced apical extrusion of debris. The ProTaper rotary extruded a significantly higher amount of debris than the ProFile.

Stability of tapered and parallel-walled dental implants: A systematic review and meta-analysis.

PubMed

Atieh, Momen A; Alsabeeha, Nabeel; Duncan, Warwick J

2018-05-15

Clinical trials have suggested that dental implants with a tapered configuration have improved stability at placement, allowing immediate placement and/or loading. The aim of this systematic review and meta-analysis was to evaluate the implant stability of tapered dental implants compared to standard parallel-walled dental implants. Applying the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement, randomized controlled trials (RCTs) were searched for in electronic databases and complemented by hand searching. The risk of bias was assessed using the Cochrane Collaboration's Risk of Bias tool and data were analyzed using statistical software. A total of 1199 studies were identified, of which, five trials were included with 336 dental implants in 303 participants. Overall meta-analysis showed that tapered dental implants had higher implant stability values than parallel-walled dental implants at insertion and 8 weeks but the difference was not statistically significant. Tapered dental implants had significantly less marginal bone loss compared to parallel-walled dental implants. No significant differences in implant failure rate were found between tapered and parallel-walled dental implants. There is limited evidence to demonstrate the effectiveness of tapered dental implants in achieving greater implant stability compared to parallel-walled dental implants. Superior short-term results in maintaining peri-implant marginal bone with tapered dental implants are possible. Further properly designed RCTs are required to endorse the supposed advantages of tapered dental implants in immediate loading protocol and other complex clinical scenarios. © 2018 Wiley Periodicals, Inc.

Impact of root canal preparation size and taper on coronal-apical micro-leakage using glucose penetration method

PubMed Central

Tabrizizadeh, Mehdi; Hekmati-Moghadam, Seyed-Hossein; Hakimian, Roqayeh

2014-01-01

Objectives: The purpose of this in vitro study was to assess the effect of root canal preparation size and taper on the amounts of glucose penetration. Material and Methods: For conducting this experimental study, eighty mandibular premolars with single straight canals were divided randomly into 2 experimental groups of 30 samples each and 2 control groups. Using K-files and the balance force technique, canals in group 1 were prepared apically to size 25 and coronally to size 2 Peesoreamer. Group 2 were instrumented apically and coronally to size 40 and size 6 Peesoreamer, respectively. Rotary instrumentation was accomplished in group 1; using size 25 and .04 tapered and in group 2, size 35 and .06 tapered Flex Master files. Canals were then obturated by lateral compaction of cold gutta-percha. Glucose penetration through root canal fillings was measured at 1, 8, 15, 22 and 30 days. Data were recorded as mmol/L and statistically analyzed with Mann-Whitney U test (P value=. 05). Results: In comparison to group 1, group 2 showed significant glucose leakage during the experimental period (P value < .0001). Also, in each experimental group, the amount of micro-leakage was significantly increased at the end of the study. Conclusions: Under the condition of this study, the amounts of micro-leakage through root canal fillings are directly related to the size and taper of root canal preparation and reducing the preparation size may lead to less micro-leakage. Key words:Dental leakage, root canal preparation, endodontics. PMID:25593654

Screw-in forces during instrumentation by various file systems.

PubMed

Ha, Jung-Hong; Kwak, Sang Won; Kim, Sung-Kyo; Kim, Hyeon-Cheol

2016-11-01

The purpose of this study was to compare the maximum screw-in forces generated during the movement of various Nickel-Titanium (NiTi) file systems. Forty simulated canals in resin blocks were randomly divided into 4 groups for the following instruments: Mtwo size 25/0.07 (MTW, VDW GmbH), Reciproc R25 (RPR, VDW GmbH), ProTaper Universal F2 (PTU, Dentsply Maillefer), and ProTaper Next X2 (PTN, Dentsply Maillefer, n = 10). All the artificial canals were prepared to obtain a standardized lumen by using ProTaper Universal F1. Screw-in forces were measured using a custom-made experimental device (AEndoS- k , DMJ system) during instrumentation with each NiTi file system using the designated movement. The rotation speed was set at 350 rpm with an automatic 4 mm pecking motion at a speed of 1 mm/sec. The pecking depth was increased by 1 mm for each pecking motion until the file reach the working length. Forces were recorded during file movement, and the maximum force was extracted from the data. Maximum screw-in forces were analyzed by one-way ANOVA and Tukey's post hoc comparison at a significance level of 95%. Reciproc and ProTaper Universal files generated the highest maximum screw-in forces among all the instruments while M-two and ProTaper Next showed the lowest ( p < 0.05). Geometrical differences rather than shaping motion and alloys may affect the screw-in force during canal instrumentation. To reduce screw-in forces, the use of NiTi files with smaller cross-sectional area for higher flexibility is recommended.

Tapered fiber optical tweezers for microscopic particle trapping: fabrication and application

NASA Astrophysics Data System (ADS)

Liu, Zhihai; Guo, Chengkai; Yang, Jun; Yuan, Libo

2006-12-01

A novel single tapered fiber optical tweezers is proposed and fabricated by heating and drawing technology. The microscopic particle tapping performance of this special designed tapered fiber probe is demonstrated and investigated. The distribution of the optical field emerging from the tapered fiber tip is numerically calculated based on the beam propagation method. The trapping force FDTD analysis results, both axial and transverse, are also given.

Supercontinuum generation in an imaging fiber taper

NASA Astrophysics Data System (ADS)

Shi, Kebin; Omenetto, Fiorenzo G.; Liu, Zhiwen

2006-12-01

We report on supercontinuum generation in individual fibers of a commercial Schott imaging fiber taper. Supercontinuum spectrum covering a wavelength range from about 500 nm to 1 μm was obtained. Unlike conventional approaches which use either a single micro-structured photonic crystal fiber (PCF) or an individual fiber or PCF taper, the availability of many fibers in an imaging taper can open new possibilities to independently and controllably generate supercontinuum arrays.

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

PubMed Central

UEZU, Mary Kinue Nakamune; BRITTO, Maria Leticia Borges; NABESHIMA, Cleber K.; PALLOTTA, Raul Capp

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 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. PMID:21308282

Peak insertion torque values of five mini-implant systems under different insertion loads.

PubMed

Quraishi, Erma; Sherriff, Martyn; Bister, Dirk

2014-06-01

To assess the effect of 1 and 3 kg insertion load on five makes of self-drilling mini-implants on peak insertion torque values to establish risk factors involved in the fracture of mini-implants. Two different loads were applied during insertion of 40 mini-implants from five different manufacturers (Dual Top(™) (1·6×8 mm), Infinitas(™) (1·5×9 mm), Ortho Easy(™) (1·7×8 mm), Spider Screw(™) (1·5×8 mm) and Vector TAS(™) (1·4×8 mm)) into acrylic blocks at 8 rev/min utilizing a Motorized Torque Measurement Stand. Peak insertion torque values for both loads were highest for Vector TAS followed by Ortho Easy and Dual Top and were nearly three times higher than Infinitas (original version) and Spider Screws(TM). The log-rank test showed statistically significant differences for both loads for Vector TAS, Ortho Easy and Spider Screws. Unlike other designs tested, both tapered mini-implant designs (Spider Screw and Infinitas) showed a tendency to buckle in the middle of the body but fractured at the tip. Non-tapered mini-implants fractured at significantly higher torque values compared to tapered designs under both loads. Increased pressure resulted in slightly higher maximum torque values at fracture for some of the mini-implant designs, although this is unlikely to be of clinical relevance. Tripling insertion pressure from 1 to 3 kg increased the risk of bending tapered mini-implants before fracture. © 2014 British Orthodontic Society.

Mid-infrared supercontinuum generation spanning from 1.9 to 5.7 μm in a chalcogenide fiber taper with ultra-high NA

NASA Astrophysics Data System (ADS)

Wang, Yingying; Dai, Shixun; Peng, Xuefeng; Zhang, Peiqing; Wang, Xunsi; You, Chenyang

2018-01-01

We report a broadband supercontinuum generation in a chalcogenide fiber taper with an ultra-high numerical aperture. The chalcogenide step-index fiber consisting of As2Se3 core and As2S3 cladding was fabricated by using the isolated stacked extrusion method. The fiber taper with a core diameter of 1.75 μm was prepared by employing a homemade tapering setup. By pumping the fiber taper with a femtosecond laser pulses at 3.3 μm, a broadband supercontinuum generation spanning from 1.9 to 5.7 μm was achieved.

Incidence of Dentinal Crack after Root Canal Preparation by ProTaper Universal, Neolix and SafeSider Systems

PubMed Central

Harandi, Azadeh; Mirzaeerad, Sina; Mehrabani, Mahgol; Mahmoudi, Elham; Bijani, Ali

2017-01-01

Introduction: This study aimed to compare the incidence of dentinal crack formation by instrumentation with ProTaper Universal system (rotary, multi-file system), SafeSider (reciprocation movement, multi-file system) and Neolix (rotary, single-file system). Methods and Materials: In this in vitro study, 60 freshly extracted mandibular first molars were randomly divided into three experimental groups (n=15) and a control group containing unprepared teeth (n=15). Instrumentation in different groups was accomplished using either ProTaper, Neolix or SafeSider systems up to 25/0.08. The teeth were then sectioned at 3, 6 and 9 mm from the apex, and observed under a stereomicroscope for presence of dentinal cracks. Data were analyzed with Chi square test, Fisher’s exact test and Bonferroni correction. Results: Micro cracks were seen in all experimental groups (13.3% in ProTaper, 26.7% in SafeSider and 40% in Neolix). There was a significant difference between Neolix and the control groups in microcrack formation (P=0.042). Micro cracks mainly occurred in the coronal section (9 mm). No microcrack occurred in the control group. Conclusion: Neolix rotary single-file system caused more dentinal cracks compared to the unprepared roots. All the instrumentation systems increased the number of micro cracks compared to unprepared teeth. PMID:29225637

Lateral bending of tapered piezo-semiconductive nanostructures for ultra-sensitive mechanical force to voltage conversion.

PubMed

Araneo, Rodolfo; Falconi, Christian

2013-07-05

Quasi-1D piezoelectric nanostructures may offer unprecedented sensitivity for transducing minuscule input mechanical forces into high output voltages due to both scaling laws and increased piezoelectric coefficients. However, until now both theoretical and experimental studies have suggested that, for a given mechanical force, lateral bending of piezoelectric nanowires results in lower output electric potentials than vertical compression. Here we demonstrate that this result only applies to nanostructures with a constant cross-section. Moreover, though it is commonly believed that the output electric potential of a strained piezo-semiconductive device can only be reduced by the presence of free charges, we show that the output piezopotential of laterally bent tapered nanostructures, with typical doping levels and very small input forces, can be even increased up to two times by free charges.Our analyses confirm that, though not optimal for piezoelectric energy harvesting, lateral bending of tapered nanostructures with typical doping levels can be ideal for transducing tiny input mechanical forces into high and accessible piezopotentials. Our results provide guidelines for designing high-performance piezo-nano-devices for energy harvesting, mechanical sensing, piezotronics, piezo-phototronics, and piezo-controlled chemical reactions, among others.

Micromachined silicon acoustic delay line with improved structural stability and acoustic directivity for real-time photoacoustic tomography

NASA Astrophysics Data System (ADS)

Cho, Young; Kumar, Akhil; Xu, Song; Zou, Jun

2017-03-01

Recent studies have shown that micromachined silicon acoustic delay lines can provide a promising solution to achieve real-time photoacoustic tomography without the need for complex transducer arrays and data acquisition electronics. However, as its length increases to provide longer delay time, the delay line becomes more vulnerable to structural instability due to reduced mechanical stiffness. In addition, the small cross-section area of the delay line results in a large acoustic acceptance angle and therefore poor directivity. To address these two issues, this paper reports the design, fabrication, and testing of a new silicon acoustic delay line enhanced with 3D printed polymer micro linker structures. First, mechanical deformation of the silicon acoustic delay line (with and without linker structures) under gravity was simulated by using finite element method. Second, the acoustic crosstalk and acoustic attenuation caused by the polymer micro linker structures were evaluated with both numerical simulation and ultrasound transmission testing. The result shows that the use of the polymer micro linker structures significantly improves the structural stability of the silicon acoustic delay lines without creating additional acoustic attenuation and crosstalk. In addition, a new tapered design for the input terminal of the delay line was also investigate to improve its acoustic directivity by reducing the acoustic acceptance angle. These two improvements are expected to provide an effective solution to eliminate current limitations on the achievable acoustic delay time and out-of-plane imaging resolution of micromachined silicon acoustic delay line arrays.

Polarimetric Doppler spectrum of backscattered echoes from nonlinear sea surface damped by natural slicks

NASA Astrophysics Data System (ADS)

Yang, Pengju; Guo, Lixin

2016-11-01

Based on the Lombardini et al. model that can predict the hydrodynamic damping of rough sea surfaces in the presence of monomolecular slicks and the "choppy wave" model (CWM) that can describe the nonlinear interactions between ocean waves, the modeling of time-varying nonlinear sea surfaces damped by natural or organic sea slicks is presented in this paper. The polarimetric scattering model of second-order small-slope approximation (SSA-II) with tapered wave incidence is utilized for evaluating co- and cross-polarized backscattered echoes from clean and contaminated CWM nonlinear sea surfaces. The influence of natural sea slicks on Doppler shift and spectral bandwidth of radar sea echoes is investigated in detail by comparing the polarimetric Doppler spectra of contaminated sea surfaces with those of clean sea surfaces. A narrowing of Doppler spectra in the presence of oil slicks is observed for both co- and cross-polarization, which is qualitatively consistent with wave-tank measurements. Simulation results also show that the Doppler shifts in slicks can increase or decrease, depending on incidence angles and polarizations.

Structural interpretation and physical property estimates based on COAST 2012 seismic reflection profiles offshore central Washington, Cascadia subduction zone

NASA Astrophysics Data System (ADS)

Webb, S. I.; Tobin, H. J.; Everson, E. D.; Fortin, W.; Holbrook, W. S.; Kent, G.; Keranen, K. M.

2014-12-01

The Cascadia subduction zone has a history of large magnitude earthquakes, but a near-total lack of plate interface seismicity, making the updip limit of the seismogenic zone difficult to locate. In addition, the central Cascadia accretionary prism is characterized by an extremely low wedge taper angle, landward vergent initial thrusting, and a flat midslope terrace between the inner and outer wedges, unlike most other accretionary prisms (e.g. the Nankai Trough, Japan). The Cascadia Open Access Seismic Transect (COAST) lines were shot by R/V Marcus Langseth in July of 2012 off central Washington to image this subduction zone. Two trench-parallel and nine trench-perpendicular lines were collected. In this study, we present detailed seismic interpretation of both time- and depth-migrated stacked profiles, focused on elucidating the deposition and deformation of both pre- and syn-tectonic sediment in the trench and slope. Distribution and timing of sediments and their deformation is used to unravel the evolution of the wedge through time. Initially, interpretation of the time-sections is carried out to support the building of tomographic velocity models to aid in the pre-stack depth migration (PSDM) of selected lines. In turn, we use PSDM velocity models to estimate porosity and pore pressure conditions at the base of the wedge and across the basal plate interface décollement where possible, using established velocity-porosity transforms. Interpretation in this way incorporates both accurate structural relationships and robust porosity models to document wedge development and present-day stress state, in particular regions of potential overpressure. Results shed light on the origin and evolution of the mid-slope terrace and the low taper angle for the forearc wedge. This work may shed light ultimately on the position of the potential updip limit of the seismogenic zone beneath the wedge.

A Tree Taper Model Based on Similar Triangles and Use of Crown Ratio as a Measure of Form in Taper Equations for Longleaf Pine

Treesearch

Dennis J. Shaw; Ralph S. Meldahl; John S. Kush; Greg L. Somers

2003-01-01

We used data from 322 natural longleaf pine (Pinus palustris Mill.) trees to include crown ratio as a continuous variable in taper equations. The data were divided into 10 crown-ratio classes and fitted taper equations into each class to detect trends in the coefficients. For application to longleaf pine, we replaced coefficients that exhibited a...

STIR-Physics: Cold Atoms and Nanocrystals in Tapered Nanofiber and High-Q Resonator Potentials

DTIC Science & Technology

2016-11-02

STIR- Physics : Cold Atoms and Nanocrystals in Tapered Nanofiber and High-Q Resonator Potentials We worked on a tapered fiber in cold atomic cloud...reviewed journals: Number of Papers published in non peer-reviewed journals: Final Report: STIR- Physics : Cold Atoms and Nanocrystals in Tapered Nanofiber...other than abstracts): Number of Peer-Reviewed Conference Proceeding publications (other than abstracts): Books Number of Manuscripts: 0.00Number of

Trial of Tocilizumab in Giant-Cell Arteritis.

PubMed

Stone, John H; Tuckwell, Katie; Dimonaco, Sophie; Klearman, Micki; Aringer, Martin; Blockmans, Daniel; Brouwer, Elisabeth; Cid, Maria C; Dasgupta, Bhaskar; Rech, Juergen; Salvarani, Carlo; Schett, Georg; Schulze-Koops, Hendrik; Spiera, Robert; Unizony, Sebastian H; Collinson, Neil

2017-07-27

Giant-cell arteritis commonly relapses when glucocorticoids are tapered, and the prolonged use of glucocorticoids is associated with side effects. The effect of the interleukin-6 receptor alpha inhibitor tocilizumab on the rates of relapse during glucocorticoid tapering was studied in patients with giant-cell arteritis. In this 1-year trial, we randomly assigned 251 patients, in a 2:1:1:1 ratio, to receive subcutaneous tocilizumab (at a dose of 162 mg) weekly or every other week, combined with a 26-week prednisone taper, or placebo combined with a prednisone taper over a period of either 26 weeks or 52 weeks. The primary outcome was the rate of sustained glucocorticoid-free remission at week 52 in each tocilizumab group as compared with the rate in the placebo group that underwent the 26-week prednisone taper. The key secondary outcome was the rate of remission in each tocilizumab group as compared with the placebo group that underwent the 52-week prednisone taper. Dosing of prednisone and safety were also assessed. Sustained remission at week 52 occurred in 56% of the patients treated with tocilizumab weekly and in 53% of those treated with tocilizumab every other week, as compared with 14% of those in the placebo group that underwent the 26-week prednisone taper and 18% of those in the placebo group that underwent the 52-week prednisone taper (P<0.001 for the comparisons of either active treatment with placebo). The cumulative median prednisone dose over the 52-week period was 1862 mg in each tocilizumab group, as compared with 3296 mg in the placebo group that underwent the 26-week taper (P<0.001 for both comparisons) and 3818 mg in the placebo group that underwent the 52-week taper (P<0.001 for both comparisons). Serious adverse events occurred in 15% of the patients in the group that received tocilizumab weekly, 14% of those in the group that received tocilizumab every other week, 22% of those in the placebo group that underwent the 26-week taper, and 25% of those in the placebo group that underwent the 52-week taper. Anterior ischemic optic neuropathy developed in one patient in the group that received tocilizumab every other week. Tocilizumab, received weekly or every other week, combined with a 26-week prednisone taper was superior to either 26-week or 52-week prednisone tapering plus placebo with regard to sustained glucocorticoid-free remission in patients with giant-cell arteritis. Longer follow-up is necessary to determine the durability of remission and safety of tocilizumab. (Funded by F. Hoffmann-La Roche; ClinicalTrials.gov number, NCT01791153 .).

Tapering strategies in elite British endurance runners.

PubMed

Spilsbury, Kate L; Fudge, Barry W; Ingham, Stephen A; Faulkner, Steve H; Nimmo, Myra A

2015-01-01

The aim of the study was to explore pre-competition training practices of elite endurance runners. Training details from elite British middle distance (MD; 800 m and 1500 m), long distance (LD; 3000 m steeplechase to 10,000 m) and marathon (MAR) runners were collected by survey for 7 days in a regular training (RT) phase and throughout a pre-competition taper. Taper duration was [median (interquartile range)] 6 (3) days in MD, 6 (1) days in LD and 14 (8) days in MAR runners. Continuous running volume was reduced to 70 (16)%, 71 (24)% and 53 (12)% of regular levels in MD, LD and MAR runners, respectively (P < 0.05). Interval running volume was reduced compared to regular training (MD; 53 (45)%, LD; 67 (23)%, MAR; 64 (34)%, P < 0.05). During tapering, the peak interval training intensity was above race speed in LD and MAR runners (112 (27)% and 114 (3)%, respectively, P < 0.05), but not different in MD (100 (2)%). Higher weekly continuous running volume and frequency in RT were associated with greater corresponding reductions during the taper (R = -0.70 and R = -0.63, respectively, both P < 0.05). Running intensity during RT was positively associated with taper running intensity (continuous intensity; R = 0.97 and interval intensity; R = 0.81, both P < 0.05). Algorithms were generated to predict and potentially prescribe taper content based on the RT of elite runners. In conclusion, training undertaken prior to the taper in elite endurance runners is predictive of the tapering strategy implemented before competition.

The effect of preparation taper on the retention of cemented cast crowns under lateral fatigue loading.

PubMed

Cameron, Stephen M; Morris, W Jack; Keesee, Stephen M; Barsky, Todd B; Parker, M Harry

2006-06-01

Clinicians have used resistance form as a basis for determining guidelines for preparation design to ensure clinical success of cemented cast restorations. Disagreement on whether clinical success follows the on-off or linear nature of resistance form continues. The purpose of this study was to evaluate the number of cycles required to dislodge a cemented complete crown casting under a cyclic lateral load as a function of taper and to compare this relationship for the resistive and nonresistive ranges of taper. Three dies were milled from stainless steel at each of the following tapers: 4, 8, 12, 16, 20, 24, 28, and 32 degrees. A gold-palladium metal-ceramic alloy crown was fabricated for each die, cemented, and subjected to lateral cyclic loading until failure or 1,000,000 cycles. The limiting taper for the dies with their given height and base was 26.6 degrees. Dies with taper less than 26.6 degrees had resistance form, whereas dies with taper larger than 26.6 degrees did not. A linear regression (alpha=.05) was used to evaluate the relation of cycles at dislodgement to taper. The average number of cycles to crown dislodgement or completion for each taper (SD), in units of 10,000, was as follows: 4 degrees, 100 (0); 8 degrees, 100 (0); 12 degrees, 93.54 (16.56); 16 degrees, 61.33 (38.47); 20 degrees, 25.73 (34.67); 24 degrees, 4.33 (7.36); 28 degrees, 0.06 (0.08); and 32 degrees, 0.05 (0.09). The crowns in the resistive area less than 26.6 degrees that demonstrated failure showed a linear regression with a correlation coefficient of -0.995 between the average number of cycles to dislodge the crown and the taper. The slope was significantly different from zero (P=.0048), with a value of -7.58 and a standard error of 0.53. The number of cycles required to cause crown dislodgement was linear after 12 degrees in the resistive area and nearly zero for preparations in the nonresistive area. The limiting taper concept closely predicted the transition point where the slope of the graph of cycles to dislodgement as a function of taper abruptly changed.

Effects of taper and space settings of telescopic Ce-TZP/A crowns on retentive force and settling.

PubMed

Nakagawa, Shusuke; Torii, Katsunori; Tanaka, Masahiro

2017-03-31

The aim of this study was to investigate the effect of the taper and space setting of using Ce-TZP/A on retentive force and secondary crown settling. The taper were 2°, 4°, and 6°, and the space settings were 0 and 10 μm. The applied loads were 50 and 100 N. The taper had a significant effect on retentive force and settling at both loads (p<0.05). The space settings did not have a significant effect on retentive force or settling at either load (p<0.05). The taper of the telescopic crowns and the load affected the retentive force and the settling.

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

PubMed Central

Sheu, Fang-Wen; Huang, Yen-Si

2013-01-01

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. PMID:23449118

Double-pass tapered amplifier diode laser with an output power of 1 W for an injection power of only 200 μW.

PubMed

Bolpasi, V; von Klitzing, W

2010-11-01

A 1 W tapered amplifier requiring only 200 μW of injection power at 780 nm is presented in this paper. This is achieved by injecting the seeding light into the amplifier from its tapered side and feeding the amplified light back into the small side. The amplified spontaneous emission of the tapered amplifier is suppressed by 75 dB. The double-passed tapered laser, presented here, is extremely stable and reliable. The output beam remains well coupled to the optical fiber for a timescale of months, whereas the injection of the seed light did not require realignment for over a year of daily operation.

Characterized Brillouin scattering in silica optical fiber tapers based on Brillouin optical correlation domain analysis.

PubMed

Zou, Weiwen; Jiang, Wenning; Chen, Jianping

2013-03-11

This paper demonstrates stimulated Brillouin scattering (SBS) characterization in silica optical fiber tapers drawn from commercial single mode optical fibers by hydrogen flame. They have different waist diameters downscaled from 5 μm to 42 μm. The fully-distributed SBS measurement along the fiber tapers is implemented by Brillouin optical correlation domain analysis technique with millimeter spatial resolution. It is found that the Brillouin frequency shift (BFS) in the waist of all fiber tapers is approximately the same (i.e., ~11.17 GHz at 1550 nm). However, the BFS is gradually reduced and the Brillouin gain decreases from the waist to the untapered zone in each fiber taper.

Using a slightly tapered optical fiber to attract and transport microparticles.

PubMed

Sheu, Fang-Wen; Wu, Hong-Yu; Chen, Sy-Hann

2010-03-15

We exploit a fiber puller to transform a telecom single-mode optical fiber with a 125 microm diameter into a symmetric and unbroken slightly tapered optical fiber with a 50 microm diameter at the minimum waist. When the laser light is launched into the optical fiber, we can observe that, due to the evanescent wave of the slightly tapered fiber, the nearby polystyrene microparticles with 10 microm diameters will be attracted onto the fiber surface and roll separately in the direction of light propagation. We have also simulated and compared the optical propulsion effects on the microparticles when the laser light is launched into a slightly tapered fiber and a heavily tapered (subwavelength) fiber, respectively.

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

PubMed

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.

Improved Tennis Racquets Have Tapered Strings

NASA Technical Reports Server (NTRS)

Noever, David A.

1995-01-01

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

A Review of Multimode Interference in Tapered Optical Fibers and Related Applications.

PubMed

Wang, Pengfei; Zhao, Haiyan; Wang, Xianfan; Farrell, Gerald; Brambilla, Gilberto

2018-03-14

In recent years, tapered optical fibers (TOFs) have attracted increasing interest and developed into a range of devices used in many practical applications ranging from optical communication, sensing to optical manipulation and high-Q resonators. Compared with conventional optical fibers, TOFs possess a range of unique features, such as large evanescent field, strong optical confinement, mechanical flexibility and compactness. In this review, we critically summarize the multimode interference in TOFs and some of its applications with a focus on our research project undertaken at the Optoelectronics Research Centre of the University of Southampton in the United Kingdom.

A Review of Multimode Interference in Tapered Optical Fibers and Related Applications

PubMed Central

Wang, Pengfei; Zhao, Haiyan; Wang, Xianfan; Brambilla, Gilberto

2018-01-01

In recent years, tapered optical fibers (TOFs) have attracted increasing interest and developed into a range of devices used in many practical applications ranging from optical communication, sensing to optical manipulation and high-Q resonators. Compared with conventional optical fibers, TOFs possess a range of unique features, such as large evanescent field, strong optical confinement, mechanical flexibility and compactness. In this review, we critically summarize the multimode interference in TOFs and some of its applications with a focus on our research project undertaken at the Optoelectronics Research Centre of the University of Southampton in the United Kingdom. PMID:29538333

Influence of resonance tube geometry shape on performance of thermoacoustic engine.

PubMed

Bao, Rui; Chen, Guobang; Tang, Ke; Jia, Zhengzhong; Cao, Weihua

2006-12-22

Based on the linear thermoacoustics, a symmetrical standing-wave thermoacoustic engine is simulated with a cylindrical tube and a tapered one as the resonance tube, respectively. The experiments with both cylindrical and tapered tubes are carried out. The suppression of nonlinear effects due to tapered tube as the resonance tube is discussed. Both simulation and experimental results show that the performance of the tapered tube is better than cylindrical one as the resonance tube.

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

PubMed Central

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

2016-01-01

Introduction. The aim of the present study was to evaluate the dentinal cracks after root canal preparation with rotary files: Gates Glidden, ProTaper Universal, ProTaper Next, and HyFlex CM at different instrumentation lengths. Methodology. Sixty-five mandibular premolars were mounted in the acrylic tube with simulated periodontal ligaments and the apex was exposed. The root canals were instrumented with different rotary files, namely, ProTaper Universal, ProTaper Next, and HyFlex CM, to the major apical foramen (AF), short AF, and beyond AF. The root apex was stained with 1% methylene blue dye and digital images of apical surface of every tooth were taken and development of dentinal defects was determined by using stereomicroscope. Multinomial logistic regression test was performed to identify influencing factors. Results. Instrumentation with rotary files terminated 2 mm short AF and did not cause any cracks. Significantly less cracks were seen when instrumentation with rotary files terminated 1 mm short apical foramen when compared with the instrumentation terminated at or beyond apical foramen (p < 0.05). Conclusion. ProTaper Universal rotary files caused more dentinal cracks than ProTaper Next and HyFlex CM. Instrumentation short AF reduced the risk of dentinal defects. PMID:27446636

Damage Patterns at the Head-Stem Taper Junction Helps Understand the Mechanisms of Material Loss.

PubMed

Hothi, Harry S; Panagiotopoulos, Andreas C; Whittaker, Robert K; Bills, Paul J; McMillan, Rebecca A; Skinner, John A; Hart, Alister J

2017-01-01

Material loss at the taper junction of metal-on-metal total hip arthroplasties has been implicated in their early failure. The mechanisms of material loss are not fully understood; analysis of the patterns of damage at the taper can help us better understand why material loss occurs at this junction. We mapped the patterns of material loss in a series of 155 metal-on-metal total hip arthroplasties received at our center by scanning the taper surface using a roundness-measuring machine. We examined these material loss maps to develop a 5-tier classification system based on visual differences between different patterns. We correlated these patterns to surgical, implant, and patient factors known to be important for head-stem taper damage. We found that 63 implants had "minimal damage" at the taper (material loss <1 mm 3 ), and the remaining 92 implants could be categorized by 4 distinct patterns of taper material loss. We found that (1) head diameter and (2) time to revision were key significant variables separating the groups. These material loss maps allow us to suggest different mechanisms that dominate the cause of the material loss in each pattern: (1) corrosion, (2) mechanically assisted corrosion, or (3) intraoperative damage or poor size tolerances leading to toggling of trunnion in taper. Copyright © 2016 Elsevier Inc. All rights reserved.

Freeway work zone lane capacity.

DOT National Transportation Integrated Search

2009-01-01

The focus of this report is a capacity analysis of two long-term urban freeway Work Zones. Work Zone #1 : tapered four mainline lanes to two, using two separate tapers; Work Zone #2 tapered two mainline lanes to one. : Work Zone throughput was analyz...

Tapered structure construction

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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.

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

PubMed

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

2016-06-01

OBJECTIVE This study investigated the optimum injection volume of polymethylmethacrylate (PMMA) to augment a novel fenestrated pedicle screw (FPS) with diameter-tapered perforations in the osteoporotic vertebral body, and how the distribution characteristics of PMMA affect the biomechanical performance of this screw. METHODS Two types of FPSs were designed (FPS-A, composed of 6 perforations with an equal diameter of 1.2 mm; and FPS-B, composed of 6 perforations each with a tapered diameter of 1.5 mm, 1.2 mm, and 0.9 mm from tip to head. Each of 28 human cadaveric osteoporotic vertebrae were randomly assigned to 1 of 7 groups: FPS-A1.0: FPS-A+1.0 ml PMMA; FPS-A1.5: FPS-A+1.5 ml PMMA; FPS-A2.0: FPS-A+2.0 ml PMMA; FPS-B1.0: FPS-B+1.0 ml PMMA; FPS-B1.5: FPS-B+1.5 ml PMMA; FPS-B2.0: FPS-B+2.0 ml PMMA; and conventional pedicle screws (CPSs) without PMMA. After the augmentation, 3D CT was performed to assess the cement distribution characteristics and the cement leakage rate. Axial pullout tests were performed to compare the maximum pullout force thereafter. RESULTS The CT construction images showed that PMMA bone cement formed a conical mass around FPS-A and a cylindrical mass around FPS-B. When the injection volume was increased from 1.0 ml to 2.0 ml, the distribution region of the PMMA cement was enlarged, the PMMA was distributed more posteriorly, and the risk of leakage was increased. When the injection volume reached 2.0 ml, the risk of cement leakage was lower for screws having diameter-tapered perforations. The pullout strengths of the augmented FPS-A groups and FPS-B groups were higher than that of the CPS group (p < 0.0001). All FPS-B groups had a higher pullout strength than the FPS-A groups. CONCLUSIONS The diameter of the perforations affects the distribution of PMMA cement. The diameter-tapered design enabled PMMA to form larger bone-PMMA interfaces and achieve a relatively higher pullout strength, although statistical significance was not reached. Study results indicated 1.5-ml of PMMA was a conservative volume for PMMA augmentation; more cement injection would significantly increase the risk of cement leakage.

Evidence for Reduced Fatigue Resistance of Contemporary Rotary Instruments Exposed to Body Temperature.

PubMed

de Vasconcelos, Rafaela Andrade; Murphy, Sarah; Carvalho, Claudio Antonio Talge; Govindjee, Rajiv G; Govindjee, Sanjay; Peters, Ove A

2016-05-01

The purpose of this study was to evaluate the effect of 2 different temperatures (20°C and 37°C) on the cyclic fatigue life of rotary instruments and correlate the results with martensitic transformation temperatures. Contemporary nickel-titanium rotary instruments (n = 20 each and tip size #25, including Hyflex CM [Coltene, Cuyahoga Falls, OH], TRUShape [Dentsply Tulsa Dental Specialties, Tulsa, OK], Vortex Blue [Dentsply Tulsa Dental Specialties], and ProTaper Universal [Dentsply Tulsa Dental Specialties]) were tested for cyclic fatigue at room temperature (20°C ± 1°C) and at body temperature (37°C ± 1°C). Instruments were rotated until fracture occurred in a simulated canal with an angle curvature of about 60° and a radius curvature of 3 mm; the center of the curvature was 4.5 mm from the instrument tip. The number of cycles to fracture was measured. Phase transformation temperatures for 2 instruments of each brand were analyzed by differential scanning calorimetry. Data were analyzed using the t test and 1-way analysis of variance with the significance level set at 0.05. For the tested size and at 20°C, Hyflex CM showed the highest resistance to fracture; no significant difference was found between TRUShape and Vortex Blue, whereas ProTaper Universal showed the lowest resistance to fracture. At 37°C, resistance to fatigue fracture was significantly reduced, up to 85%, for the tested instruments (P < .001); at that temperature, Hyflex CM and Vortex Blue had similar and higher fatigue resistance compared with TRUShape and ProTaper Universal. Under the conditions of this study, using a novel testing design, immersion in water at simulated body temperature was associated with a marked decrease in the fatigue life of all rotary instruments tested. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Local Seismicity Recorded by ChilePEPPER: Implications for Dynamic Accretionary Prism Response and Long-term Prism Evolution

NASA Astrophysics Data System (ADS)

de Moor, A.; Trehu, A. M.; Tryon, M. D.

2015-12-01

To investigate the dynamic response of the outer accretionary wedge updip from the patch of greatest slip during the Mw8.8 2010 Maule earthquake, 10 Ocean Bottom Seismometers (OBS) were deployed from May 2012 to March 2013 in a small array with an inter-instrument spacing of ~12 km . Nine instruments were recovered, with 4 recording data on 3 intermediate-band 3-component seismometers and a differential pressure gauge and 5 recording data from absolute pressure gauges. [note: All instruments were also equipped with a fluid flow meter sensitive to flow rates as low as 0.0001 cm/yr in or out of the sediments. However, no flow signal was detected.] Here we present hypocenters for 569 local events that have S-P times less than 17 seconds (i.e. within ~125 km of the array) using hand-picked arrival times and a 1D velocity model derived from a 2D seismic refraction profile through the region (Moscoso et al 2011, EPSL). We analyze the distribution of seismicity in the context of published slip models, ChilePEPPER high-resolution seismic reflection data, critical taper analysis done by Cubas et al 2013 (EPSL), and offshore gravity data. The data show distinct segmentation within the outer prism. The northern section of the study area is characterized by a lack of seismicity, accretion of nearly all incoming sediment and a prism at critical taper. In contrast, abundant seismicity, significant sediment underthrusting at the deformation front and a prism below critical taper angle characterize the southern part of the study area. Both coseismic slip and post-rupture local seismicity can be related to density anomalies within the upper plate as revealed by free air gravity data corrected for the effects of bathymetry and the subducting plate. [ChilePEPPER - Project Evaluating Prism Post-Earthquake Response

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

PubMed

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

2017-08-01

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.

A combined paging alert and web-based instrument alters clinician behavior and shortens hospital length of stay in acute pancreatitis.

PubMed

Dimagno, Matthew J; Wamsteker, Erik-Jan; Rizk, Rafat S; Spaete, Joshua P; Gupta, Suraj; Sahay, Tanya; Costanzo, Jeffrey; Inadomi, John M; Napolitano, Lena M; Hyzy, Robert C; Desmond, Jeff S

2014-03-01

There are many published clinical guidelines for acute pancreatitis (AP). Implementation of these recommendations is variable. We hypothesized that a clinical decision support (CDS) tool would change clinician behavior and shorten hospital length of stay (LOS). Observational study, entitled, The AP Early Response (TAPER) Project. Tertiary center emergency department (ED) and hospital. Two consecutive samplings of patients having ICD-9 code (577.0) for AP were generated from the emergency department (ED) or hospital admissions. Diagnosis of AP was based on conventional Atlanta criteria. The Pre-TAPER-CDS-Tool group (5/30/06-6/22/07) had 110 patients presenting to the ED with AP per 976 ICD-9 (577.0) codes and the Post-TAPER-CDS-Tool group (5/30/06-6/22/07) had 113 per 907 ICD-9 codes (7/14/10-5/5/11). The TAPER-CDS-Tool, developed 12/2008-7/14/2010, is a combined early, automated paging-alert system, which text pages ED clinicians about a patient with AP and an intuitive web-based point-of-care instrument, consisting of seven early management recommendations. The pre- vs. post-TAPER-CDS-Tool groups had similar baseline characteristics. The post-TAPER-CDS-Tool group met two management goals more frequently than the pre-TAPER-CDS-Tool group: risk stratification (P<0.0001) and intravenous fluids >6L/1st 0-24 h (P=0.0003). Mean (s.d.) hospital LOS was significantly shorter in the post-TAPER-CDS-Tool group (4.6 (3.1) vs. 6.7 (7.0) days, P=0.0126). Multivariate analysis identified four independent variables for hospital LOS: the TAPER-CDS-Tool associated with shorter LOS (P=0.0049) and three variables associated with longer LOS: Japanese severity score (P=0.0361), persistent organ failure (P=0.0088), and local pancreatic complications (<0.0001). The TAPER-CDS-Tool is associated with changed clinician behavior and shortened hospital LOS, which has significant financial implications.

Guided-Mode-Leaky-Mode-Guided-Mode Fiber Interferometer and Its High Sensitivity Refractive Index Sensing Technology.

PubMed

Wang, Qi; Li, Chunyue; Zhao, Chengwu; Li, Weizheng

2016-06-01

A cascaded symmetrical dual-taper Mach-Zehnder interferometer structure based on guided-mode and leaky-mode interference is proposed in this paper. Firstly, the interference spectrum characteristics of interferometer has been analyzed by the Finite Difference-Beam Propagation Method (FD-BPM). When the diameter of taper waist is 20 μm-30 μm, dual-taper length is 1 mm and taper distance is 4 cm-6 cm, the spectral contrast is higher, which is suitable for sensing. Secondly, experimental research on refractive index sensitivity is carried out. A refractive index sensitivity of 62.78 nm/RIU (refractive index unit) can achieved in the RI range of 1.3333-1.3792 (0%~25% NaCl solution), when the sensor structure parameters meet the following conditions: diameter of taper waist is 24 μm, dual-taper length is 837 μm and taper distance is 5.5 cm. The spectrum contrast is 0.8 and measurement resolution is 1.6 × 10(-5) RIU. The simulation analysis is highly consistent with experimental results. Research shows that the sensor has promising application in low RI fields where high-precision measurement is required due to its high sensitivity and stability.

Modeling and simulation performance of sucker rod beam pump

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aditsania, Annisa, E-mail: annisaaditsania@gmail.com; Rahmawati, Silvy Dewi, E-mail: silvyarahmawati@gmail.com; Sukarno, Pudjo, E-mail: psukarno@gmail.com

2015-09-30

Artificial lift is a mechanism to lift hydrocarbon, generally petroleum, from a well to surface. This is used in the case that the natural pressure from the reservoir has significantly decreased. Sucker rod beam pumping is a method of artificial lift. Sucker rod beam pump is modeled in this research as a function of geometry of the surface part, the size of sucker rod string, and fluid properties. Besides its length, sucker rod string also classified into tapered and un-tapered. At the beginning of this research, for easy modeling, the sucker rod string was assumed as un-tapered. The assumption provedmore » non-realistic to use. Therefore, the tapered sucker rod string modeling needs building. The numerical solution of this sucker rod beam pump model is computed using finite difference method. The numerical result shows that the peak of polished rod load for sucker rod beam pump unit C-456-D-256-120, for non-tapered sucker rod string is 38504.2 lb, while for tapered rod string is 25723.3 lb. For that reason, to avoid the sucker rod string breaks due to the overload, the use of tapered sucker rod beam string is suggested in this research.« less

Polymer taper bridge for silicon waveguide to single mode waveguide coupling

NASA Astrophysics Data System (ADS)

Kruse, Kevin; Middlebrook, Christopher T.

2016-03-01

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

A comparison of experimental and theoretical results for leakage, pressure gradients, and rotordynamic coefficients for tapered annular gas seal

NASA Technical Reports Server (NTRS)

Elrod, D. A.; Childs, D. W.

1986-01-01

A brief review of current annular seal theory and a discussion of the predicted effect on stiffness of tapering the seal stator are presented. An outline of Nelson's analytical-computational method for determining rotordynamic coefficients for annular compressible-flow seals is included. Modifications to increase the maximum rotor speed of an existing air-seal test apparatus at Texas A&M University are described. Experimental results, including leakage, entrance-loss coefficients, pressure distributions, and normalized rotordynamic coefficients, are presented for four convergent-tapered, smooth-rotor, smooth-stator seals. A comparison of the test results shows that an inlet-to-exit clearance ratio of 1.5 to 2.0 provides the maximum direct stiffness, a clearance ratio of 2.5 provides the greatest stability, and a clearance ratio of 1.0 provides the least stability. The experimental results are compared to theoretical results from Nelson's analysis with good agreement. Test results for cross-coupled stiffness show less sensitivity of fluid prerotation than predicted.

Effect of anode shape on correlation of neutron emission with pinch energy for a 2.7 kJ Mather-type plasma focus device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hussain, S. S.; Murtaza, Ghulam; Zakaullah, M.

Correlation of neutron emission with pinch energy for a Mather-type plasma focus energized by a single capacitor 12.5 muF, 21 kV (2.7 kJ) is investigated by employing time resolved and time integrated detectors for two different anode shapes. The maximum average neutron yield of about 1.3x10{sup 8} per shot is recorded with cylindrical anode, that increases to 1.6x10{sup 8} per shot for tapered anode. At optimum pressure the input energy converted to pinch energy is about 24% for cylindrical anode as compared to 36% for tapered anode. It is found that the tapered anode enhances neutron flux about 25+-5% bothmore » in axial and radial directions and also broadens the pressure range for neutron emission as well as pinch energy. The neutron yield and optimum gas filling pressures are found strongly dependent on the anode shape.« less

5 CFR 353.303 - Restoration rights of TAPER employees.

Code of Federal Regulations, 2010 CFR

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... she left or an equivalent one in the same commuting area. ...

Merging taper lengths for short duration lane closure : final report, December 2009.

DOT National Transportation Integrated Search

2009-12-01

The Utility Industry has requested that the Florida Department of Transportation provide for the use of merging taper lengths that are significantly shorter than the lengths computed using the taper length equations published in the MUTCD Section 6C....

Red-green-blue (RGB) light generator using tapered fiber pumped with a frequency-doubled Yb-fiber laser.

PubMed

Rusu, M; Kivistö, Samuli; Gawith, C; Okhotnikov, O

2005-10-17

We report on successful realization of a picosecond visible-continuum source embedding a single mode fiber taper. The output of ytterbium mode-locked fiber laser was frequency doubled in a periodically-polled lithium niobate (PPLN) crystal to produce green pump light. Spectral brightness of the white light generated in the tapered fiber was improved by limiting the broadening just to the visible wavelengths. The influence of taper parameters, particularly the dispersion, on white light spectrum has been studied.

Red-green-blue (RGB) light generator using tapered fiber pumped with a frequency-doubled Yb-fiber laser

NASA Astrophysics Data System (ADS)

Rusu, M.; Kivistö, Samuli; Gawith, C. B. E.; Okhotnikov, O. G.

2005-10-01

We report on successful realization of a picosecond visible-continuum source embedding a single mode fiber taper. The output of ytterbium mode-locked fiber laser was frequency doubled in a periodically-polled lithium niobate (PPLN) crystal to produce green pump light. Spectral brightness of the white light generated in the tapered fiber was improved by limiting the broadening just to the visible wavelengths. The influence of taper parameters, particularly the dispersion, on white light spectrum has been studied.

Experimental design rules for implementing biconically tapered single mode optical fibre displacement sensors

NASA Astrophysics Data System (ADS)

Arregui, Francisco J.; Matias, Ignacio R.; Bariain, Candido; Lopez-Amo, Manuel

1998-06-01

Tapered optical fibers are used to design couplers, wavelength division multiplexers, near field scanning optical microscopy, just to mention a few. Moreover, and due to its strong transmission dependence to external medium the tapered fiber may also be used to sense distinct parameters such as temperature, humidity, PH, etc. In this work bending effects in tapers are exploited to achieved displacement sensors and to present design rules for implementing these sensors according to the desired both range and sensitivity.

Fabrication of longitudinally arbitrary shaped fiber tapers

NASA Astrophysics Data System (ADS)

Nold, J.; Plötner, M.; Böhme, S.; Sattler, B.; deVries, O.; Schreiber, T.; Eberhardt, R.; Tünnermann, A.

2018-02-01

We present our current results on the fabrication of arbitrary shaped fiber tapers on our tapering rig using a CO2-laser as heat source. Single mode excitation of multimode fibers as well as changing the fiber geometry in an LPG-like fashion is presented. It is shown that this setup allows for reproducible fabrication of single-mode excitation tapers to extract the fundamental mode (M2 < 1.1) from a 30 μm core having an NA of 0.09.

Tapered undulator for SASE FELs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fawley, William M.; Huang, Zhirong; Kim, Kwang-Je

We discuss the use of tapered undulators to enhance the performance of free-electron lasers (FELs) based upon self-amplified spontaneous emission (SASE), where the radiation tends to have a relatively broad bandwidth, limited temporal phase coherence, and large amplitude fluctuations. Using the polychromatic FEL simulation code GINGER, we numerically demonstrate the effectiveness of a tapered undulator for parameters corresponding to the existing Argonne low-energy undulator test line (LEUTL) FEL. We also study possible tapering options for proposed x-ray FELs such as the Linac Coherent Light Source (LCLS).

Early Experience with a Short, Tapered Titanium Porous Plasma Sprayed Stem with Updated Design.

PubMed

Lombardi, Adolph V; Manocchio, Antonio G; Berend, Keith R; Morris, Michael J; Adams, Joanne B

2018-06-01

Short stem femoral components in primary total hip arthroplasty (THA) have increased in popularity since the advent of minimally invasive surgical techniques. The concept of a short stem is particularly compatible with tapered designs where the goal is to offload forces proximally in the femur. The purpose of this retrospective review was to review our early experience with a short, tapered titanium femoral component with updated design features. Beginning in November 2011 through February 2012, 92 consented patients (93 hips), at a single center, were treated with primary cementless THA using a short stem, tapered femoral component (Taperloc® Complete Microplasty; Zimmer Biomet, Warsaw, Indiana) and were available for review with a minimum two-year follow-up. Mean patient age at surgery was 63.2 years and body mass index (BMI) was 30.8 kg/m2. Mean stem length used was 110.3mm (range, 95-125). Mean follow-up was 4.5 years (2-6). Harris hip scores improved from 52.5 preoperatively to 84.7 at most recent. One stem was revised the same day for periprosthetic fracture. One patient with early infection was treated with single-stage exchange followed by recurrence that was treated successfully with two-stage exchange. A non-healing wound in one patient was treated with incision and debridement. Radiographic assessment demonstrated no evidence of loosening, osteolysis, distal hypertrophy, or pedestal formation in any hip, and all components appeared well fixed and in appropriate alignment. In this series of patients treated with primary THA using a short, tapered titanium porous plasma-sprayed femoral component with updated design features, good results were achieved with a low incidence of complications and revision. No aseptic loosening or osteolysis has occurred. Radiographic assessment was excellent for all patients.

A short tapered stem reduces intraoperative complications in primary total hip arthroplasty.

PubMed

Molli, Ryan G; Lombardi, Adolph V; Berend, Keith R; Adams, Joanne B; Sneller, Michael A

2012-02-01

While short-stem design is not a new concept, interest has surged with increasing utilization of less invasive techniques. Short stems are easier to insert through small incisions. Reliable long-term results including functional improvement, pain relief, and implant survival have been reported with standard tapered stems, but will a short taper perform as well? We compared short, flat-wedge, tapered, broach-only femoral stems to standard-length, double-tapered, ream and broach femoral stems in terms of intraoperative complications, short-term survivorship, and pain and function scores. We retrospectively reviewed the records of 606 patients who had 658 THAs using a less invasive direct lateral approach from January 2006 to March 2008. Three hundred sixty patients (389 hips) had standard-length stems and 246 (269 hips) had short stems. Age averaged 63 years, and body mass index averaged 30.7 kg/m(2). We recorded complications and pain and function scores and computed short-term survival. Minimum followup was 0.8 months (mean, 29.2 months; range, 0.8-62.2 months). We observed a higher rate of intraoperative complications with the standard-length stems (3.1%; three trochanteric avulsions, nine femoral fractures) compared with the shorter stems (0.4%; one femoral fracture) and managed all complications with application of one or more cerclage cables. There were no differences in implant survival, Harris hip score, and Lower Extremity Activity Scale score between groups. Fewer intraoperative complications occurred with the short stems, attesting to the easier insertion of these devices. While longer followup is required, our early results suggest shortened stems can be used with low complication rates and do not compromise the survival and functional outcome of cementless THA. Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Design charts for predicting downwash angles and wake characteristics behind plain and flapped wings

NASA Technical Reports Server (NTRS)

Silverstein, Abe; Katzoff, S

1939-01-01

Equations and design charts are given for predicting the downwash angles and the wake characteristics for power-off conditions behind plain and flapped wings of the types used in modern design practice. The downwash charts cover the cases of elliptical wings and wings of taper ratios 1, 2, 3, and 5, with aspect ratios of 6, 9, and 12, having flaps covering 0, 40, 70, and 100 percent of the span. Curves of the span load distributions for all these cases are included. Data on the lift and the drag of flapped airfoil sections and curves for finding the contribution of the flap to the total wing lift for different types of flap and for the entire range of flap spans are also included. The wake width and the distribution of dynamic pressure across the wake are given in terms of the profile-drag coefficient and the distance behind the wing. A method of estimating the wake position is also given. The equations and charts are based on theory that has been shown in a previous report to be in agreement with experiment.

Effect of Instrumentation Techniques and Preparation Taper on Apical Extrusion of Bacteria.

PubMed

Aksel, Hacer; Küçükkaya Eren, Selen; Çakar, Aslı; Serper, Ahmet; Özkuyumcu, Cumhur; Azim, Adham A

2017-06-01

The aim of this in vitro study was to evaluate the effects of different root canal instrumentation techniques and preparation tapers on the amount of apically extruded bacteria. The root canals of 98 extracted human mandibular incisors were contaminated with Enterococcus faecalis suspension. After incubation at 37°C for 24 hours, the root canals were instrumented with K3 rotary files in a crown-down (CD) or full-length linear instrumentation technique (FL) by using 3 different root canal tapers (0.02, 0.04, and 0.06). During instrumentation, apically extruded bacteria were collected into vials containing saline solution. The microbiological samples were taken from the vials and incubated in brain-heart agar medium for 24 hours, and the numbers of colony-forming units (CFUs) were determined. The obtained results were analyzed with t test and one-way analysis of variance for the comparisons between the instrumentation techniques (CD and FL) and the preparation tapers (0.02, 0.04, and 0.06), respectively. Tukey honestly significant difference test was used for pairwise comparisons. The preparation taper had no effect on the number of CFUs when a FL instrumentation technique was used (P > .05). There was a statistically significant difference in the CFUs between FL and CD techniques when the preparation taper was 0.02 (P < .05). There was no statistically significant difference between the 0.04 and 0.06 preparation tapers in any of the instrumentation techniques (P > .05). Using a 0.02 taper in a CD manner results in the least amount of bacterial extrusion. The instrumentation technique did not seem to affect the amount of bacterial extrusion when 0.04 and 0.06 taper instruments were used for cleaning and shaping the root canal space. Published by Elsevier Inc.

Energy partitioning and impulse dispersion in the decorated, tapered, strongly nonlinear granular alignment: A system with many potential applications

NASA Astrophysics Data System (ADS)

Doney, Robert L.; Agui, Juan H.; Sen, Surajit

2009-09-01

Rapid absorption of impulses using light-weight, small, reusable systems is a challenging problem. An axially aligned set of progressively shrinking elastic spheres, a "tapered chain," has been shown to be a versatile and scalable shock absorber in earlier simulational, theoretical, and experimental works by several authors. We have recently shown (see R. L. Doney and S. Sen, Phys. Rev. Lett. 97, 155502 (2006)) that the shock absorption ability of a tapered chain can be dramatically enhanced by placing small interstitial grains between the regular grains in the tapered chain systems. Here we focus on a detailed study of the problem introduced in the above mentioned letter, present extensive dynamical simulations using parameters for a titanium-aluminum-vanadium alloy Ti6Al4V, derive attendant hard-sphere analyses based formulae to describe energy dispersion, and finally discuss some preliminary experimental results using systems with chrome spheres and small Nitinol interstitial grains to present the underlying nonlinear dynamics of this so-called decorated tapered granular alignment. We are specifically interested in small systems, comprised of several grains. This is because in real applications, mass and volume occupied must inevitably be minimized. Our conclusion is that the decorated tapered chain offers enhanced energy dispersion by locking in much of the input energy in the grains of the tapered chain rather than in the small interstitial grains. Thus, the present study offers insights into how the shock absorption capabilities of these systems can be pushed even further by improving energy absorption capabilities of the larger grains in the tapered chains. We envision that these scalable, decorated tapered chains may be used as shock absorbing components in body armor, armored vehicles, building applications and in perhaps even in applications in rehabilitation science.

Chirped self-similar optical pulses in tapered centrosymmetric nonlinear waveguides doped with resonant impurities

NASA Astrophysics Data System (ADS)

He, J. R.; Xu, S. L.; Xue, L.

2017-11-01

Exact chirped self-similar optical pulses propagating in tapered centrosymmetric nonlinear waveguides doped with resonant impurities are reported. The propagation behaviors of the pulses are studied by tailoring of the tapering function. Numerical simulations and stability analysis reveal that the tapering can be used to postpone the wave dispersion and the addition of a small cubic self-focusing term to the governing equation could stabilize the chirped bright pulses. An example of possible experimental protocol that may generate the pulses in realistic waveguides is given. The obtained chirped self-similar optical pulses are particularly useful in the design of amplifying or attenuating pulse compressors for chirped solitary waves in tapered centrosymmetric nonlinear waveguides doped with resonant impurities.

Adiabatic tapered optical fiber fabrication in two step etching

NASA Astrophysics Data System (ADS)

Chenari, Z.; Latifi, H.; Ghamari, S.; Hashemi, R. S.; Doroodmand, F.

2016-01-01

A two-step etching method using HF acid and Buffered HF is proposed to fabricate adiabatic biconical optical fiber tapers. Due to the fact that the etching rate in second step is almost 3 times slower than the previous droplet etching method, terminating the fabrication process is controllable enough to achieve a desirable fiber diameter. By monitoring transmitted spectrum, final diameter and adiabaticity of tapers are deduced. Tapers with losses about 0.3 dB in air and 4.2 dB in water are produced. The biconical fiber taper fabricated using this method is used to excite whispering gallery modes (WGMs) on a microsphere surface in an aquatic environment. So that they are suitable to be used in applications like WGM biosensors.

Tapered fluorotellurite microstructured fibers for broadband supercontinuum generation.

PubMed

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

2016-02-01

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

Tapered fiber based high power random laser.

PubMed

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

2016-04-18

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

Tabulated Pressure Data for a Series of Controls on a 40 Deg Sweptback Wing at Mach Numbers of 1.61 and 2.01

NASA Technical Reports Server (NTRS)

Lord, D. R.

1957-01-01

An investigation has been made at Mach numbers of 1.61 and 2.01 and Reynolds numbers of 1.7 x l0(exp 6) and 3.6 x l0(exp 6) to determine the pressure distributions over a swept wing with a series of 14 control configurations. The wing had 40 deg of sweep of the quarter-chord line, an aspect ratio of 3.1, and a taper ratio of 0.4. Measurements were made at angles of attack from 0 deg to +/- 15 deg for control deflections from -60 deg to 60 deg. This report contains tabulated pressure data for the complete range of test conditions.

Calculated spanwise lift distributions, influence functions, and influence coefficients for unswept wings in subsonic flow

NASA Technical Reports Server (NTRS)

Diederich, Franklin W; Zlotnick, Martin

1955-01-01

Spanwise lift distributions have been calculated for nineteen unswept wings with various aspect ratios and taper ratios and with a variety of angle-of-attack or twist distributions, including flap and aileron deflections, by means of the Weissinger method with eight control points on the semispan. Also calculated were aerodynamic influence coefficients which pertain to a certain definite set of stations along the span, and several methods are presented for calculating aerodynamic influence functions and coefficients for stations other than those stipulated. The information presented in this report can be used in the analysis of untwisted wings or wings with known twist distributions, as well as in aeroelastic calculations involving initially unknown twist distributions.

Development of Cone Wedge Ring Expansion Test to Evaluate Mechanical Properties of Clad Tubing Structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jy-An John

To determine the hoop tensile properties of irradiated fuel cladding in a hot cell, a cone wedge ring expansion test method was developed. A four-piece wedge insert was designed with tapered angles matched to the cone shape of a loading piston. The ring specimen was expanded in the radial direction by the lateral expansion of the wedges under the downward movement of the piston. The advantages of the proposed method are that implementation of the test setup in a hot cell is simple and easy, and that it enables a direct strain measurement of the test specimen from the piston’smore » vertical displacement soon after the wedge-clad contact resistance is initiated.« less

Micro-Computed Tomography Evaluation of ProTaper Next and BioRace Shaping Outcomes in Maxillary First Molar Curved Canals.

PubMed

Pasqualini, Damiano; Alovisi, Mario; Cemenasco, Andrea; Mancini, Lucia; Paolino, Davide Salvatore; Bianchi, Caterina Chiara; Roggia, Andrea; Scotti, Nicola; Berutti, Elio

2015-10-01

The aim of this micro-computed tomography study was to describe the shaping properties of ProGlider/ProTaper Next (PG/PTN) and ScoutRace/BioRace (SR/BR) nickel-titanium rotary systems. Thirty maxillary first permanent molars were selected. Mesiobuccal canals were randomly assigned (n = 15) to PG/PTN or SR/BR groups. Irrigation was performed with 5% NaOCl and 10% EDTA. Specimens were scanned (voxel size, 9.1 μm) for matching volumes and surface areas and post-treatment analyses. Root canal centering ability, canal geometry enlargement, and thickness of dentinal wall at inner curvature were assessed at apical level and point of maximum curvature. Results were analyzed with 4 one-way analyses of variance. Canal centering ability was superior in PG/PTN (P = .006 at apical level, P = .025 at point of maximum curvature). PG/PTN demonstrated a more conservative increase of canal areas (P = .027 at apical level, P = .038 at point of maximum curvature). Centrifugal increase in canal diameters did not significantly differ between groups (P = .65 at apical level, P = .61 at point of maximum curvature). Inner dentinal wall thickness was less reduced with PG/PTN compared with SR/BR, with no statistical differences (P = .23 at point of maximum curvature, P = .89 at apical level). PG/PTN shaping taper ranged between 6% and 7%. Neither system produced significant shaping errors in curved canals. PG/PTN system showed better preservation of canal anatomy. PTN offset section did not influence final preparation taper. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Axial displacement of abutments into implants and implant replicas, with the tapered cone-screw internal connection, as a function of tightening torque.

PubMed

Dailey, Bruno; Jordan, Laurence; Blind, Olivier; Tavernier, Bruno

2009-01-01

The passive fit of a superstructure on implant abutments is essential to success. One source of error when using a tapered cone-screw internal connection may be the difference between the tightening torque level applied to the abutments by the laboratory technician compared to that applied by the treating clinician. The purpose of this study was to measure the axial displacement of tapered cone-screw abutments into implants and their replicas as a function of the tightening torque level. Twenty tapered cone-screw abutments were selected. Two groups were created: 10 abutments were secured into 10 implants, and 10 abutments were secured into 10 corresponding implant replicas. Each abutment was tightened in increasing increments of 5 Ncm, from 0 Ncm to 45 Ncm, with a torque controller. The length of each sample was measured repeatedly with an Electronic Digital Micrometer. The mean axial displacement for the implant group and the replica group was calculated. The data were analyzed by the Mann-Whitney and Spearman tests. For both groups, there was always an axial displacement of the abutment upon each incremental application of torque. The mean axial displacement values varied between 7 and 12 microm for the implant group and between 6 and 21 microm for the replica group at each 5-Ncm increment. From 0 to 45 Ncm, the total mean axial displacement values were 89 microm for the implant group and 122 microm for the replica group. There was a continuous axial displacement of the abutments into implants and implant replicas when the applied torque was raised from 0 to 45 Ncm. Torque applied above the level recommended by the manufacturer increased the difference in displacement between the two groups.

Comparative analysis of torsional and bending behavior through finite-element models of 5 Ni-Ti endodontic instruments.

PubMed

Arbab-Chirani, Reza; Chevalier, Valérie; Arbab-Chirani, Shabnam; Calloch, Sylvain

2011-01-01

The objectives of this study were to compare numerically the bending and torsional mechanical behavior of 5 endodontic rotary Ni-Ti instruments with equivalent size and various designs for tapers, pitch, and cutting blades.First, the geometries of Hero (20/0.06), HeroShaper (20/0.06), ProFile (20/0.06), Mtwo (20/0.06), and ProTaper F1 were generated by finite element code. Then, the 2 most representative clinical loadings, i.e., bending and torsion, were studied with an ad hoc model for the superelasticity of Ni-Ti. Bending was generated by tip deflection and torsion by a constant twist-angle of the tip. Mechanical behavior of these 5 endodontic rotary Ni-Ti instruments could be evaluated and compared. Protaper F1 presented the greatest level of bending stress and torque. Hero and HeroShaper were more rigid than ProFile and Mtwo. This numerical comparison evaluated the effects of the geometrical parameters on the instrumental mechanical behavior. The 5 endodontic instruments, investigated in the present study, do not have the same bending and torsional mechanical behavior. Each clinician must be aware of these behavior differences so as to use the adequate file according to the clinical situation and to the manufacturer's recommendations. Copyright © 2011 Mosby, Inc. All rights reserved.

Quantitative evaluation of apically extruded debris during root canal instrumentation with ProTaper Universal, ProTaper Next, WaveOne, and self-adjusting file systems

PubMed Central

Ozsu, Damla; Karatas, Ertugrul; Arslan, Hakan; Topcu, Meltem C.

2014-01-01

Objectives: The aim of this study was to compare the amount of apically extruded debris during preparation with ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Next (Dentsply Maillefer), a reciprocating single-file (WaveOne; VDW GmbH, Munich, Germany), and a self-adjusting file (SAF; ReDent Nova, Ra’anna, Israel). Materials and Methods: Fifty-six intact mandibular premolar teeth were randomly assigned to four groups. The root canals were prepared according to the manufacturers’ instructions using the ProTaper Universal, ProTaper Next, WaveOne, and SAF. Apically extruded debris was collected in preweighted Eppendorf tubes during instrumentation. The net weight of the apically extruded debris was determined by subtracting the preweights and postweights of the tubes. The data were statistically analyzed using the one-way analysis of variance and the least significant difference tests at a significance level of P < 0.05. Results: A measurable amount of debris was apically extruded in all groups, and the amounts of debris extrusion in the groups were statistically significant (P < 0.001). The ProTaper Next and WaveOne groups resulted in less debris extrusion than the ProTaper Universal group (P < 0.05), and the SAF group resulted in the least debris extrusion. Conclusions: Within the limitations of the present study, it can be concluded that all systems extruded debris beyond the apical foramen. PMID:25512732

Effect of blade planform variation on the forward-flight performance of small-scale rotors

NASA Technical Reports Server (NTRS)

Noonan, Kevin W.; Althoff, Susan L.; Samak, Dhananjay K.; Green, Michael D.

1992-01-01

An investigation was conducted in the Glenn L. Martin Wind Tunnel to determine the effect of blade planform variation on the forward-flight performance of four small-scale rotors. The rotors were 5.417 ft in diameter and differed only in blade planform geometry. The four planforms were: (1) rectangular; (2) 3:1 linear taper starting at 94 percent radius; (3) 3:1 linear taper starting at 75 percent radius; and (4) 3:1 linear taper starting at 50 percent radius. Each planform had a thrust-weighted solidity of 0.098. The investigation included forward-flight simulation at advance ratios from 0.14 to 0.43 for a range of rotor lift and drag coefficients. Among the four rotors, the rectangular rotor required the highest torque for the entire range of rotor drag coefficients attained at advanced ratios greater than 0.14 for rotor lift coefficients C sub L from 0.004 to 0.007. Among the rotors with tapered blades and for C sub L = 0.004 to 0.007, either the 75 percent tapered rotor or the 50 percent tapered rotor required the least amount of torque for the full range of rotor drag coefficients attained at each advance ratio. The performance of the 94 percent tapered rotor was generally between that of the rectangular rotor and the 75 and 50 percent tapered rotors at each advance ratio for this range of rotor lift coefficients.

Supercompensation Kinetics of Physical Qualities During a Taper in Team-Sport Athletes.

PubMed

Marrier, Bruno; Robineau, Julien; Piscione, Julien; Lacome, Mathieu; Peeters, Alexis; Hausswirth, Christophe; Morin, Jean-Benoît; Le Meur, Yann

2017-10-01

Peaking for major competition is considered critical for maximizing team-sport performance. However, there is little scientific information available to guide coaches in prescribing efficient tapering strategies for team-sport players. To monitor the changes in physical performance in elite team-sport players during a 3-wk taper after a preseason training camp. Ten male international rugby sevens players were tested before (Pre) and after (Post) a 4-wk preseason training camp focusing on high-intensity training and strength training with moderate loads and once each week during a subsequent 3-wk taper. During each testing session, midthigh-pull maximal strength, sprint-acceleration mechanical outputs, and performance, as well as repeated-sprint ability (RSA), were assessed. At Post, no single peak performance was observed for maximal lower-limb force output and sprint performance, while RSA peaked for only 1 athlete. During the taper, 30-m-sprint time decreased almost certainly (-3.1% ± 0.9%, large), while maximal lower-limb strength and RSA, respectively, improved very likely (+7.7% ± 5.3%, small) and almost certainly (+9.0% ± 2.6%, moderate). Of the peak performances, 70%, 80%, and 80% occurred within the first 2 wk of taper for RSA, maximal force output, and sprint performance, respectively. These results show the sensitivity of physical qualities to tapering in rugby sevens players and suggest that an ~1- to 2-wk tapering time frame appears optimal to maximize the overall physical-performance response.

Catalog of Window Taper Functions for Sidelobe Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doerry, Armin W.

Window taper functions of finite apertures are well-known to control undesirable sidelobes, albeit with performance trades. A plethora of various taper functions have been developed over the years to achieve various optimizations. We herein catalog a number of window functions, and com pare principal characteristics.

Experimental Aerodynamic Characteristics of an Oblique Wing for the F-8 OWRA

NASA Technical Reports Server (NTRS)

Kennelly, Robert A., Jr.; Carmichael, Ralph L.; Smith, Stephen C.; Strong, James M.; Kroo, Ilan M.

1999-01-01

An experimental investigation was conducted during June-July 1987 in the NASA Ames 11-Foot Transonic Wind Tunnel to study the aerodynamic performance and stability and control characteristics of a 0.087-scale model of an F-8 airplane fitted with an oblique wing. This effort was part of the Oblique Wing Research Aircraft (OWRA) program performed in conjunction with Rockwell International. The Ames-designed, aspect ratio 10.47, tapered wing used specially designed supercritical airfoils with 0.14 thickness/chord ratio at the root and 0.12 at the 85% span location. The wing was tested at two different mounting heights above the fuselage. Performance and longitudinal stability data were obtained at sweep angles of 0deg, 30deg, 45deg, 60deg, and 65deg at Mach numbers ranging from 0.30 to 1.40. Reynolds number varied from 3.1 x 10(exp 6)to 5.2 x 10(exp 6), based on the reference chord length. Angle of attack was varied from -5deg to 18deg. The performance of this wing is compared with that of another oblique wing, designed by Rockwell International, which was tested as part of the same development program. Lateral-directional stability data were obtained for a limited combination of sweep angles and Mach numbers. Sideslip angle was varied from -5deg to +5deg. Landing flap performance was studied, as were the effects of cruise flap deflections to achieve roll trim and tailor wing camber for various flight conditions. Roll-control authority of the flaps and ailerons was measured. A novel, deflected wing tip was evaluated for roll-control authority at high sweep angles.

Spacing of Imbricated Thrust Faults and the Strength of Thrust-Belts and Accretionary Wedges

NASA Astrophysics Data System (ADS)

Ito, G.; Regensburger, P. V.; Moore, G. F.

2017-12-01

The pattern of imbricated thrust blocks is a prominent characteristic of the large-scale structure of thrust-belts and accretionary wedges around the world. Mechanical models of these systems have a rich history from laboratory analogs, and more recently from computational simulations, most of which, qualitatively reproduce the regular patterns of imbricated thrusts seen in nature. Despite the prevalence of these patterns in nature and in models, our knowledge of what controls the spacing of the thrusts remains immature at best. We tackle this problem using a finite difference, particle-in-cell method that simulates visco-elastic-plastic deformation with a Mohr-Coulomb brittle failure criterion. The model simulates a horizontal base that moves toward a rigid vertical backstop, carrying with it an overlying layer of crust. The crustal layer has a greater frictional strength than the base, is cohesive, and is initially uniform in thickness. As the layer contracts, a series of thrust blocks immerge sequentially and form a wedge having a mean taper consistent with that predicted by a noncohesive, critical Coulomb wedge. The widths of the thrust blocks (or spacing between adjacent thrusts) are greatest at the front of the wedge, tend to decrease with continued contraction, and then tend toward a pseudo-steady, minimum width. Numerous experiments show that the characteristic spacing of thrusts increases with the brittle strength of the wedge material (cohesion + friction) and decreases with increasing basal friction for low (<8°) taper angles. These relations are consistent with predictions of the elastic stresses forward of the frontal thrust and at what distance the differential stress exceeds the brittle threshold to form a new frontal thrust. Hence the characteristic spacing of the thrusts across the whole wedge is largely inherited at the very front of the wedge. Our aim is to develop scaling laws that will illuminate the basic physical processes controlling systems, as well as allow researchers to use observations of thrust spacing as an independent constraint on the brittle strength of wedges as well as their bases.

Apical extrusion of debris by supplementary files used for retreatment: An ex vivo comparative study

PubMed Central

Pawar, Ajinkya M.; Pawar, Mansing; Metzger, Zvi; Thakur, Bhagyashree

2016-01-01

Aim: This study evaluated whether using supplementary files for removing root canal filling residues after ProTaper Universal Retreatment files (RFs) increased the debris extrusion apically. Materials and Methods: Eighty mandibular premolars with single root and canal were instrumented with ProTaper Universal rotary system (SX-F3) and obturated. The samples were divided randomly into four groups (n = 20). Group 1 served as a control; only ProTaper Universal RFs D1–D3 were used, and the extruded debris was weighed. Groups 2, 3, and 4 were the experimental groups, receiving a twofold retreatment protocol: Removal of the bulk, followed by the use of supplementary files. The bulk was removed by RFs, followed by the use of ProTaper NEXT (PTN), WaveOne (WO), and Self-Adjusting File (SAF) for removal of the remaining root filling residues. Debris extruded apically were weighed and compared to the control group. Statistical analysis was performed using one-way analysis of variance (ANOVA) and post hoc Tukey's test. Results: All the three experimental groups presented significant difference (P < .01). The post hoc Tukey's test confirmed that Group 4 (SAF) exhibited significantly less (P < .01) debris extrusion between the three groups tested. Conclusion: SAF results in less extrusion of debris when used as supplementary file to remove root-filling residues, compared to WO and PTN. PMID:27099416

Measurement and optimization of the light collection uniformity in strongly tapered PWO crystals of the PANDA detector

NASA Astrophysics Data System (ADS)

Diehl, Stefan; Bremer, Daniel; Brinkmann, Kai-Thomas; Dormenev, Valery; Eissner, Tobias; Novotny, Rainer W.; Rosenbaum, Christoph; Zaunick, Hans-Georg; PANDA Collaboration

2017-06-01

The uniformity of the light collection is a crucial parameter for detectors based on inorganic scintillation crystals to guarantee a response proportional to the deposited energy. Especially in case of tapered crystals, like they are widely used to realize a 4π geometry of electromagnetic calorimeters (EMC) in high energy physics experiments, a strong non-uniformity is introduced by an additional focusing of the scintillation light due to the tapered geometry. The paper will discuss the determination and the reduction of the non-uniformity in strongly tapered lead tungstate crystals as used for the construction of the electromagnetic calorimeter of the PANDA detector at the future Facility for Antiproton and Ion Research (FAIR). Among different concepts for an uniformization a single de-polished lateral side face provided the optimum result with a remaining non-uniformity below 5% in good agreement with similar studies for the CMS ECAL at LHC. The impact on the achievable energy resolution in the energy regime of photons below 800 MeV is discussed in detail in comparison to GEANT4 simulations. The comparison of the response of two arrays with polished and de-polished crystals, respectively, shows in the latter case a significant improvement of the constant term of the parametrization of the energy resolution down to 0.5% accompanied by only very slight increase of the statistical term.

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

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-29

... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-344 (Third Review)] Tapered Roller Bearings From China; Scheduling of a Full Five- Year Review AGENCY: United States International Trade... whether revocation of the antidumping duty order on tapered roller bearings from China would be likely to...

77 FR 45587 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, from the People's Republic of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-01

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-601] Tapered Roller Bearings and... new shipper review (``NSR'') of the antidumping duty order on tapered roller bearings (``TRBs'') from... from Zhejiang Zhengda Bearing Co., Ltd. (``Zhejiang Zhengda''). Zhejiang Zhengda's request was made in...

Polymer optical fiber tapering using hot water

NASA Astrophysics Data System (ADS)

Mizuno, Yosuke; Ujihara, Hiroki; Lee, Heeyoung; Hayashi, Neisei; Nakamura, Kentaro

2017-06-01

We perform a pilot trial of highly convenient taper fabrication for polymer optical fibers (POFs) using hot water. A ∼380-mm-long POF taper is successfully fabricated, and its ∼150-mm-long waist has a uniform outer diameter of ∼230 µm. The shape is in good agreement with the theoretical prediction. The optical loss dependence on the strain applied to the waist shows an interesting behavior exhibiting three regimes, the origins of which are inferred by microscopic observations. We then discuss the controllability of the taper length.

CORROSION RESISTANT JACKETED METAL BODY

DOEpatents

Brugmann, E.W.

1958-08-26

Jacketed metal bodies of the type used as fuel elements for nuclear reactors, which contain an internal elongated body of fissionable material jacketed in a corrosion resistant metal are described. The ends of the internal bodies are provided with screw threads having a tapered outer end. The jacket material overlaps the ends and extends into the tapered section of the screw threaded opening. Screw caps with a mating tapered section are screwed into the ends of the body to compress the jacket material in the tapered sections to provtde an effective seal against corrosive gases and liquids.

Racetrack resonator as a loss measurement platform for photonic components.

PubMed

Jones, Adam M; DeRose, Christopher T; Lentine, Anthony L; Starbuck, Andrew; Pomerene, Andrew T S; Norwood, Robert A

2015-11-02

This work represents the first complete analysis of the use of a racetrack resonator to measure the insertion loss of efficient, compact photonic components. Beginning with an in-depth analysis of potential error sources and a discussion of the calibration procedure, the technique is used to estimate the insertion loss of waveguide width tapers of varying geometry with a resulting 95% confidence interval of 0.007 dB. The work concludes with a performance comparison of the analyzed tapers with results presented for four taper profiles and three taper lengths.

Non-lead hollow point bullet

DOEpatents

Vaughn, Norman L.; Lowden, Richard A.

2003-04-15

The non-lead hollow point bullet of the instant invention comprises a mixed construction slug further comprising, a monolithic metal insert having a tapered (preferred conical) hollow point tip and a tapered (preferred conical) tail protrusion, and an unsintered powdered metal composite core in tandem alignment with the insert. The core has a hollow tapered (preferred conical) cavity tip portion coupled with the tapered (preferred conical) tail protrusion on the insert. An open tip jacket envelops at least a portion of the insert and the core. The jacket is swaged at the open tip.

Twist-induced tuning in tapered fiber couplers.

PubMed

Birks, T A

1989-10-01

The power-splitting ratio of fused tapered single-mode fiber couplers can be reversibly tuned by axial twisting without affecting loss. The twist-tuning behavior of a range of different tapered couplers is described. A simple expression for twist-tuning can be derived by representing the effects of twist by a change in the refractive index profile. Good agreement between this expression and experimental results is demonstrated. Repeated tuning over tens of thousands of cycles is found not to degrade coupler performance, and a number of practical applications, including a freely tunable tapered coupler, are described.

Racetrack resonator as a loss measurement platform for photonic components

DOE PAGES

Jones, Adam M.; Univ. of Arizona, Tucson, AZ; DeRose, Christopher T.; ...

2015-10-27

This work represents the first complete analysis of the use of a racetrack resonator to measure the insertion loss of efficient, compact photonic components. Beginning with an in-depth analysis of potential error sources and a discussion of the calibration procedure, the technique is used to estimate the insertion loss of waveguide width tapers of varying geometry with a resulting 95% confidence interval of 0.007 dB. Furthermore, the work concludes with a performance comparison of the analyzed tapers with results presented for four taper profiles and three taper lengths.

Single and low order mode interrogation of a multimode sapphire fibre Bragg grating sensor with tapered fibres

NASA Astrophysics Data System (ADS)

Grobnic, D.; Mihailov, S. J.; Ding, H.; Bilodeau, F.; Smelser, C. W.

2006-05-01

Multimode sapphire fibre Bragg gratings (SFBG) made with an ultrafast Ti:sapphire 800 nm laser and a phase mask were probed using a tapered single mode fibre of different taper diameters to produce single and low order mode reflection/transmission responses. A configuration made of an input single mode tapered fibre and multimode silica fibre used for output coupling was also tested and has delivered a filtered multimode transmission spectrum. The tapered coupling improved the spectral resolution of the SFBG. Such improvements facilitate the utilization of the SFBG as a high temperature sensor. Wavelength shifts of the single mode response were monitored as a function of temperature up to 1500 °C with no detectable degradation in the grating strength or hysteresis in the Bragg resonance.

Buckling analysis of non-prismatic columns based on modified vibration modes

NASA Astrophysics Data System (ADS)

Rahai, A. R.; Kazemi, S.

2008-10-01

In this paper, a new procedure is formulated for the buckling analysis of tapered column members. The calculation of the buckling loads was carried out by using modified vibrational mode shape (MVM) and energy method. The change of stiffness within a column is characterized by introducing a tapering index. It is shown that, the changes in the vibrational mode shapes of a tapered column can be represented by considering a linear combination of various modes of uniform-section columns. As a result, by making use of these modified mode shapes (MVM) and applying the principle of stationary total potential energy, the buckling load of tapered columns can be obtained. Several numerical examples on tapered columns demonstrate the accuracy and efficiency of the proposed analytical method.

Implementation of rectangular slit-inserted ultra-wideband tapered slot antenna.

PubMed

Kim, Sun-Woong; Choi, Dong-You

2016-01-01

In this paper, a tapered slot antenna capable of ultra-wideband communication was designed. In the proposed antenna, rectangular slits were inserted to enhance the bandwidth and reduce the area of the antenna. The rectangular slit-inserted tapered slot antenna operated at a bandwidth of 8.45 GHz, and the bandwidth improved upon the basic tapered slot antenna by 4.72 GHz. The radiation pattern of the antenna was suitable for location recognition in a certain direction owing to an appropriate 3 dB beam width. The antenna gain was analyzed within the proposed bandwidth, and the highest gain characteristic at 7.55 dBi was exhibited at a 5-GHz band. The simulation and measurement results of the proposed tapered slot antenna were similar.

Tapered fiber Mach-Zehnder interferometers for vibration and elasticity sensing applications.

PubMed

Chen, Nan-Kuang; Hsieh, Yu-Hsin; Lee, Yi-Kun

2013-05-06

We demonstrate the optical measurements of heart-beat pulse rate and also elasticity of a polymeric tube, using a tapered fiber Mach-Zehnder interferometer. This device has two abrupt tapers in the Er/Yb codoped fiber and thus fractional amount of core mode is converted into cladding modes at the first abrupt taper. The core and cladding modes propagate through different optical paths and meet again at the second abrupt taper to produce interferences. The mechanical vibration signals generated by the blood vessels and by an inflated polymeric tube can perturb the optical paths of resonant modes to move around the resonant wavelengths. Thus, the cw laser signal is modulated to become pulses to reflect the heart-beat pulse rate and the elasticity of a polymeric tube, respectively.

Plasmonic structure: fiber grating formed by gold nanorods on a tapered fiber.

PubMed

Trevisanutto, J O; Linhananta, A; Das, G

2016-12-15

The authors demonstrated the fabrication of a fiber Bragg grating-like plasmonic nanostructure on the surface of a tapered optical fiber using gold nanorods (GNRs). A multimode optical fiber with core and cladding diameters of 105 and 125 μm, respectively, was used to make a tapered fiber using a dynamic etching process. The tip diameter was ∼100  nm. Light from a laser was coupled to the untapered end of the fiber, which produced a strong evanescent field around the tapered section of the fiber. The gradient force due to the evanescent field trapped the GNRs on the surface of the tapered fiber. The authors explored possible causes of the GNR distribution. The plasmonic structure will be a good candidate for sensing based on surface enhanced Raman scattering.

CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Novel Route to Fabrication of Metal-Sandwiched Nanoscale Tapered Structures

NASA Astrophysics Data System (ADS)

Zhang, Yang; Yu, Da-Peng

2009-08-01

Tapered dielectric structures in metal have exhibited extraordinary performance in both surface plasmon polariton (SPP) waveguiding and SPP focusing. This is crucial to plasmonic 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 10 nm to 1000 nm. 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.

Micro-computed tomographic comparison of nickel-titanium rotary versus traditional instruments in C-shaped root canal system.

PubMed

Yin, Xingzhe; Cheung, Gary Shun-Pan; Zhang, Chengfei; Masuda, Yoshiko Murakami; Kimura, Yuichi; Matsumoto, Koukichi

2010-04-01

The purpose of this study was to assess the efficacy of instrumentation of C-shaped canals with ProTaper rotary system and traditional instruments by using micro-computed tomography (micro-CT). Twenty-four mandibular molars with C-shaped canals were selected in pairs and sorted equally into 2 groups, which were assigned for instrumentation by ProTaper rotary system (ProTaper group) or by K-files and Gates-Glidden burs (Hand Instrument group). Three-dimensional images were constructed by micro-CT. The volume of dentin removed, uninstrumented canal area, time taken for instrumentation, and iatrogenic error of instrumentation were investigated. Hand Instrument group showed greater amount of volumetric dentin removal and left less uninstrumented canal area than ProTaper group (P < .01). The time needed for instrumentation was shorter for ProTaper group than for Hand Instrument group (P < .05). No instrument breakage occurred in both groups, but more conspicuous procedural errors were detected in Hand Instrument group than for ProTaper group. It was concluded that ProTaper rotary system maintained the canal curvature with speediness and few procedural errors, whereas traditional instrumentation can clean more canal surface. Copyright (c) 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Apical extrusion of debris in primary molar root canals using mechanical and manual systems.

PubMed

Buldur, B; Hascizmeci, C; Aksoy, S; Nur Aydin, M; Guvendi, O N

2018-03-01

Apical extrusion of debris in primary root canal treatment has not been well elucidated. The purpose of this study is to compare the amount of apically extruded debris during the preparation of primary molar root canals using ProTaper, ProTaper Next, Self-adjusting File (SAF) and hand files. One hundred sixty extracted primary mandibular molar teeth were assigned to 2 groups: Group 1: Resorbed (n=80) and Group 2: Non-resorbed (n=80) and randomly to four subgroups (n=20 teeth for each subgroup) according to the instruments used, ProTaper, ProTaper Next, SAF, and hand file. The apically extruded debris was collected and dried in preweighed Eppendof tubes. The dry weight was calculated by subtracting the preoperative weight from the postoperative weight. Data were analysed statistically using the ANOVA and the Bonferroni post hoc t-test. The amount of apically extruded debris was significantly less for the non-resorbed group compared to the resorbed group (P<0.05). Regardless of the resorption groups, ProTaper Next and SAF extruded significantly less debris than did the ProTaper and hand files (P<0.05), while no statistically significant difference was found between ProTaper Next and SAF (P>0.05). All instruments caused apically extruded debris in primary teeth.

Guided-Mode-Leaky-Mode-Guided-Mode Fiber Interferometer and Its High Sensitivity Refractive Index Sensing Technology

PubMed Central

Wang, Qi; Li, Chunyue; Zhao, Chengwu; Li, Weizheng

2016-01-01

A cascaded symmetrical dual-taper Mach-Zehnder interferometer structure based on guided-mode and leaky-mode interference is proposed in this paper. Firstly, the interference spectrum characteristics of interferometer has been analyzed by the Finite Difference-Beam Propagation Method (FD-BPM). When the diameter of taper waist is 20 μm–30 μm, dual-taper length is 1 mm and taper distance is 4 cm–6 cm, the spectral contrast is higher, which is suitable for sensing. Secondly, experimental research on refractive index sensitivity is carried out. A refractive index sensitivity of 62.78 nm/RIU (refractive index unit) can achieved in the RI range of 1.3333–1.3792 (0%~25% NaCl solution), when the sensor structure parameters meet the following conditions: diameter of taper waist is 24 μm, dual-taper length is 837 μm and taper distance is 5.5 cm. The spectrum contrast is 0.8 and measurement resolution is 1.6 × 10−5 RIU. The simulation analysis is highly consistent with experimental results. Research shows that the sensor has promising application in low RI fields where high-precision measurement is required due to its high sensitivity and stability. PMID:27258281

Bidirectional optical coupler for plastic optical fibers.

PubMed

Sugita, Tatsuya; Abe, Tomiya; Hirano, Kouki; Itoh, Yuzo

2005-05-20

We have developed a low-loss bidirectional optical coupler for high-speed optical communication with plastic optical fibers (POFs). The coupler, which is fabricated by an injection molding method that uses poly (methyl methacrylate), has an antisymmetric tapered shape. We show that the coupler has low insertion and branching losses. The tapered shape of the receiving branch reduces beam diameter and increases detection efficiency coupling to a photodetector, whose area is smaller than that of the plastic optical fiber. The possibility of more than 15-m bidirectional transmission with a signaling bit rate up to 500 Mbits/s for simplex step-index POFs is demonstrated.

Opioid Tapering in Fibromyalgia Patients: Experience from an Interdisciplinary Pain Rehabilitation Program.

PubMed

Cunningham, Julie L; Evans, Michele M; King, Susan M; Gehin, Jessica M; Loukianova, Larissa L

2016-09-01

Despite current guideline recommendations against the use of opioids for the treatment of fibromyalgia pain, opioid use is reported in approximately 30% of the patient population. There is a lack of information describing the process and results of tapering of chronic opioids. The purpose of this study is to describe opioid tapering and withdrawal symptoms in fibromyalgia patients on opioids. This retrospective research study included a baseline analysis of 159 patients consecutively admitted to the Mayo Clinic Pain Rehabilitation Center from 2006 through 2012 with a pain diagnosis of fibromyalgia completing a 3-week outpatient interdisciplinary pain rehabilitation program. Opioid tapering analysis included 55 (35%) patients using daily opioids. Opioid tapering was individualized to each patient based on interdisciplinary pain rehabilitation team determination. Opioid withdrawal symptoms were assessed daily, utilizing the Clinical Opioid Withdrawal Scale. Patients taking daily opioids had a morphine equivalent mean dose of 99 mg/day. Patients on < 100 mg/day were tapered off over a mean of 10 days compared with patients on > 200 mg/day over a mean of 28 days (P < 0.001). Differences in peak withdrawal symptoms were not statistically significant based on the mean equivalent dose (P = 22). Patients taking opioids for <2 years did not differ in length of tapering (P =0.63) or peak COWS score (P =0.80) compared with >2 years duration. Patients had significant improvements in pain-related measures including numeric pain scores, depression catastrophizing, health perception, interference with life, and perceived life control at program completion. Fibromyalgia patients on higher doses of opioids were tapered off over a longer period of time but no differences in withdrawal symptoms were seen based on opioid dose. Duration of opioid use did not affect the time to complete opioid taper or withdrawal symptoms. Despite opioid tapering, pain-related measures improved at the completion of the rehabilitation program. © 2016 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The impact of hospital-wide use of a tapered-cuff endotracheal tube on the incidence of ventilator-associated pneumonia.

PubMed

Bowton, David L; Hite, R Duncan; Martin, R Shayn; Sherertz, Robert

2013-10-01

Aspiration of colonized oropharyngeal secretions is a major factor in the pathogenesis of ventilator-associated pneumonia (VAP). A tapered-cuff endotracheal tube (ETT) has been demonstrated to reduce aspiration around the cuff. Whether these properties are efficacious in reducing VAP is not known. This 2-period, investigator-initiated observational study was designed to assess the efficacy of a tapered-cuff ETT to reduce the VAP rate. All intubated, mechanically ventilated patients over the age of 18 were included. During the baseline period a standard, barrel-shaped-cuff ETT (Mallinckrodt Hi-Lo) was used. All ETTs throughout the hospital were then replaced with a tapered-cuff ETT (TaperGuard). The primary outcome variable was the incidence of VAP per 1,000 ventilator days. We included 2,849 subjects, encompassing 15,250 ventilator days. The mean ± SD monthly VAP rate was 3.29 ± 1.79/1,000 ventilator days in the standard-cuff group and 2.77 ± 2.00/1,000 ventilator days in the tapered-cuff group (P = .65). While adherence to the VAP prevention bundle was high throughout the study, bundle adherence was significantly higher during the standard-cuff period (96.5 ± 2.7%) than in the tapered-cuff period (90.3 ± 3.5%, P = .01). In the setting of a VAP rate very near the average of ICUs in the United States, and where there was high adherence to a VAP prevention bundle, the use of a tapered-cuff ETT was not associated with a reduction in the VAP rate.

The Cervical Spinal Canal Tapers Differently in Patients with Chiari I with and without Syringomyelia.

PubMed

Thompson, A; Madan, N; Hesselink, J R; Weinstein, G; Munoz del Rio, A; Haughton, V

2016-04-01

The cause of syringomyelia in patients with Chiari I remains uncertain. Cervical spine anatomy modifies CSF velocities, flow patterns, and pressure gradients, which may affect the spinal cord. We tested the hypothesis that cervical spinal anatomy differs between Chiari I patients with and without syringomyelia. We identified consecutive patients with Chiari I at 3 institutions and divided them into groups with and without syringomyelia. Five readers measured anteroposterior cervical spinal diameters, tonsillar herniation, and syrinx dimensions on cervical MR images. Taper ratios for C1-C7, C1-C4, and C4-C7 spinal segments were calculated by linear least squares fitting to the appropriate spinal canal diameters. Mean taper ratios and tonsillar herniation for groups were compared and tested for statistical significance with a Kruskal-Wallis test. Inter- and intrareader agreement and correlations in the data were measured. One hundred fifty patients were included, of which 49 had syringomyelia. C1-C7 taper ratios were smaller and C4-C7 taper ratios greater for patients with syringomyelia than for those without it. C1-C4 taper ratios did not differ significantly between groups. Patients with syringomyelia had, on average, greater tonsillar herniation than those without a syrinx. However, C4-C7 taper ratios were steeper, for all degrees of tonsil herniation, in patients with syringomyelia. Differences among readers did not exceed differences among patient groups. The tapering of the lower cervical spine may contribute to the development of syringomyelia in patients with Chiari I. © 2016 by American Journal of Neuroradiology.

Tapering Practices of Strongman Athletes: Test-Retest Reliability Study

PubMed Central

Pritchard, Hayden J; Keogh, Justin WL

2017-01-01

Background Little is currently known about the tapering practices of strongman athletes. We have developed an Internet-based comprehensive self-report questionnaire examining the training and tapering practices of strongman athletes. Objective The objective of this study was to document the test-retest reliability of questions associated with the Internet-based comprehensive self-report questionnaire on the tapering practices of strongman athletes. The information will provide insight on the reliability and usefulness of the online questionnaire for use with strongman athletes. Methods Invitations to complete an Internet questionnaire were sent via Facebook Messenger to identified strongman athletes. The survey consisted of four main areas of inquiry, including demographics and background information, training practices, tapering, and tapering practices. Of the 454 athletes that completed the survey over the 8-week period, 130 athletes responded on Facebook Messenger indicating that they intended to complete, or had completed, the survey. These participants were asked if they could complete the online questionnaire a second time for a test-retest reliability analysis. Sixty-four athletes (mean age 33.3 years, standard deviation [SD] 7.7; mean height 178.2 cm, SD 11.0; mean body mass 103.7 kg, SD 24.8) accepted this invitation and completed the survey for the second time after a minimum 7-day period from the date of their first completion. Agreement between athlete responses was measured using intraclass correlation coefficients (ICCs) and kappa statistics. Confidence intervals (at 95%) were reported for all measures and significance was set at P<.05. Results Test-retest reliability for demographic and training practices items were significant (P<.001) and showed excellent (ICC range=.84 to .98) and fair to almost perfect agreement (κ range=.37-.85). Moderate to excellent agreements (ICC range=.56-.84; P<.01) were observed for all tapering practice measures except for the number of days athletes started their usual taper before a strongman competition (ICC=.30). When the number of days were categorized with additional analyses, moderate reliability was observed (κ=.43; P<.001). Fair to substantial agreement was observed for the majority of tapering practices measures (κrange=.38-.73; P<.001) except for how training frequency (κ=.26) and the percentage and type of resistance training performed, which changed in the taper (κ=.20). Good to excellent agreement (ICC=.62-.93; P<.05) was observed for items relating to strongman events and traditional exercises performed during the taper. Only the time at which the Farmer’s Walk was last performed before competition showed poor reliability (ICC=.27). Conclusions We have developed a low cost, self-reported, online retrospective questionnaire, which provided stable and reliable answers for most of the demographic, training, and tapering practice questions. The results of this study support the inferences drawn from the Tapering Practices of Strongman Athletes Study. PMID:29089292

76 FR 72213 - Tapered Roller Bearings From China; Notice of Commission determination To Conduct a Full Five...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-22

... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-344 (Third Review)] Tapered Roller Bearings From China; Notice of Commission determination To Conduct a Full Five-Year Review AGENCY: United...(c)(5)) to determine whether revocation of the antidumping duty order on tapered roller bearings from...

78 FR 45912 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the People's Republic of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-30

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-601] Tapered Roller Bearings and... Bearing Co., Ltd.'s (Tainai's) request for a new shipper review (NSR) of the antidumping duty order on tapered roller bearings and parts thereof, finished and unfinished (TRBs), from the People's Republic of...