Taper Configuration Research Articles

Low-Grade Myxofibrosarcoma: CT and MRI Patterns in Recurrent Disease

Low-grade myxofibrosarcoma often relentlessly recurs after surgical resection, with an unusual infiltrative growth pattern and sometimes without a discrete tumor nodule at pathologic examination. This study was undertaken to determine and show patterns of recurrent low-grade myxofibrosarcoma at CT and MRI. Unlike in most other histologic types of low-grade soft-tissue sarcoma, recurrent low-grade myxofibrosarcoma often is infiltrative; shows a tapering, tail-like margin and superficial spreading configuration; and metastasizes to various distant sites, including lungs, pleura, bone, adrenal gland, soft tissue, and mesentery. Knowledge of these unusual characteristics is important in assessing the presence and extent of recurrent low-grade myxofibrosarcoma before surgical reexcision.

Progressive failure and post-buckling response of tapered composite plates under uni-axial compression

Abstract The objective of the present work is to predict the first-ply failure load, the ultimate failure load, the buckling load, the associated maximum transverse displacements, and locations and modes of failure of tapered laminated plates under the action of uni-axial compression. A non-linear finite element formulation is developed based on the first-order shear deformation theory and the geometric non-linearity in the von Karman sense. The tensor polynomial form of the maximum stress criterion is used in conjunction with a progressive failure simulation methodology. A parametric study on tapered composite plates is conducted, considering the influences of different laminate configurations, taper configurations and fiber orientation angles.

Effect of tapered FRP sheets on interlaminar fracture behaviour of FRP–concrete interface

Abstract External bonding of fibre reinforced plastic (FRP) sheets to reinforced concrete beams has been accepted as an effective strengthening method. The use of taper ended FRP sheets can further enhance the strengthening performance, improving both the load carrying capacity and the corresponding deflection beyond those of the beams bonded with FRP sheets of a constant thickness. This paper presents experimental and analytical investigations regarding the influence of tapered FRP sheets on interlaminar fracture resistance between the FRP and concrete. The asymmetric double cantilever beam test was used to measure the interlaminar fracture resistance. The results showed that the taper configuration could significantly affect the interlaminar fracture behaviour in terms of both the load–displacement behaviour and the variation of critical strain energy release rate with crack propagation.

Theoretical and experimental research into optimal edge taper of bonded repair patches subject to fatigue loadings

Finite element (FE) analyses were conducted for double lap, metal-to-metal bonded repair joints with different linear edge taper angles, or optimal taper profiles using the shape optimisation approach. Various adhesive failure criteria were applied and compared. A fracture mechanics approach was also applied in the FE analyses, in which an initial crack was pre-set at the edge of the adhesive bond line. The energy release rates were calculated and the results were used to evaluate the fatigue resistance. FE results predicted that the taper angle should strongly affect the fatigue performance of the repair patch. Compared with the 90° taper case, the peak stresses in the 6° taper case reduced by around 60%, and the stresses in the 3° taper case reduced by around 80%. The optimum design was able to reduce the peak stresses by about 50% compared with the widely used 6° linear taper (i.e. 1:10) with the same taper length. Thus, it appeared to be the best in terms of the fatigue resistance vs. taper region length. The calculated energy release rates also indicated a similar trend for the fatigue resistance as a function of the edge taper configuration. Experimental results agreed well with the numerical predictions. In particular, the predicted crack initiation loads, based on estimated threshold value of mode 1 energy release rate, correlate well with experimental results and the high fatigue resistance of the optimal design was confirmed.

Compact Low-Cross-Polarization Horn Antennas With Serpentine-Shaped Taper

A compact horn with low cross polarization component less than -35 dB over 5% frequency bandwidth has been obtained by optimizing the taper configuration. To reduce the gain loss caused by spherical wavefront in a short length horn with a large flare angle, a serpentine-shaped taper successfully generates five higher-order modes. Such a taper configuration is represented by varying lengths of various uniform waveguides in stepwise approximation, while keeping the dimension of each step discontinuity constant. As a result, the computational time for obtaining the proposed horn is greatly reduced because scattering matrices of the step discontinuities are pre-calculated before the optimization. The verification of its high performance has been performed numerically and experimentally.

Optical fiber probes for fluorescence based oxygen sensing

An optical fiber sensing system, for monitoring oxygen aiming in vivo nuclear magnetic resonance (NMR) applications is presented. Oxygen detection is based on the dynamic quenching of the fluorescence of a ruthenium complex trapped in the porous structure of a sol–gel silica film. Oxygen concentration is determined by phase-modulation fluorometry. Preliminary results concerning the characterization of doped sol–gel thin films deposited by dip coating in glass slides and in optical fiber probes are presented. Four different probe configurations are tested and compared. Best results are obtained with a fiber taper configuration which shows reproducibility and best excitation efficiency. This structure is fully characterized and some considerations regarding optimal fiber optical sensing probes for O2 detection are addressed.

Wave Propagation in Periodic Shells with Tapered Wall Thickness and Changing Material Properties

A theoretical method based on the Transfer Matrix Formulation and Wavelet Transforms is developed in order to effectively investigate the influence of periodicity, variable geometry and material properties on the wave propagation characteristics of axis‐symmetric shells. Several experiments have been conducted to verify the numerical predictions and to demonstrate that the Wavelet Transform is a very powerful tool to uniquely identify and compare the energy distribution both in the time and frequency domain.Thin shells are modeled as two‐dimensional wave‐guides, where the propagation of the longitudinal waves is coupled with the flexural (radial) waves. Variations of the wall thickness, medium radius and element length of the shell can effectively filter out/stop undesirable bands of frequencies from the longitudinal and/or the transverse wave characteristics. The principal parameter that influences the width and location of the stop bands is the ratio between the cross sections at the two ends of the shell element. Sophisticated exponential profiles and simpler linear taper are implemented and compared.Functionally graded materials (FGM) are also investigated as an alternative way to influence the parameters of the stop bands. Combinations of the FGM and geometric taper give the flexibility needed for some very demanding applications. Different types of periodic taper configurations have complementary effects on the wave characteristics. Combinations of these complex geometries (bi-periodic tapered cells) are presented and shown to produce the most effectual energy redistribution.

Evanescent wave fiber optic fluorosensor: effect of tapering configuration on the signal acquisition

A comparative study of the signal acquisition from straight fiber and tapered optical fibers has been analyzed theoretically for the design of an evanescent wave fiber optic immunosensor. It has been shown that tapered optical fibers have higher sensitivity compared to straight fibers. Among the tapered fibers combination tapered fibers were also found to have higher sensitivity than continuous tapered fibers. Theoretical analysis indicates that an increase in signal is a result of three factors, namely, V number matching, an increase in evanescent absorption by the fluorescent medium, and an increase in fluorescence emission coupling into the fiber. Maximum sensitivity is obtained when the radius of the fiber is reduced to the V number matching radius within 1 cm from the start of the taper with rest of the fiber remaining untapered. Also, a higher signal level is obtained when the launching light fills the numerical aperture determined by the tapering ratio of the fiber. © 1998 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(98)04301-3) Subject terms: evanescent wave; fiber-optic immunosensor; tapered fibers.

Tectonic evolution of accretionary prism in the arc-continent collision terrane of Taiwan

The thick sedimentary and meta-sedimentary rocks west of the Eocene-Paleozoic metamorphic basement of Taiwan represent an accretionary prism developed between the Eurasian continent and the Philippine Sea plate. The accretionary prism consists of a subduction wedge in the east and a collision prism in the west. The deep-marine subduction wedge developed during the eastward subduction of the South China Sea oceanic crust since the Early Miocene. In the Central Range, a regional unconformity with mylonite structure occurred between the Miocene deep-marine slates-turbidites and the Paleozoic-Eocene metamorphic basement. The unconformity marks the tectonostratigraphic break between the overlying subduction wedge and the underlying underthrust Eurasian continent. The subduction wedge extends from the western Central Range southwards through the Hengchun Peninsula to the offshore Hengchun Ridge. Subduction of the South China Sea oceanic crust further led to the oblique arc-continent collision starting about 6.5 Ma in northern Taiwan. During the collision, the shallow-marine passive margin and foreland sequences were progressively incorporated to the collision prism by a series of west-vergent thrusts in the Hsüehshan Range and the Western Foothills. The Kaoping Slope west of the subduction wedge of the Hengchun Ridge represents the modern collision prism in the active arc-continent collision zone. The collision prism is juxtaposed against the subduction wedge to the east along the Lishan-Laonung-Hengchun fault, which extends offshore to the 30-km-wide fault zone between the Kaoping Slope and the Hengchun Ridge. Before the onset of the arc-continent collision, the Lishan-Laonung-Hengchun fault developed along the northern part of the proto-Manila trench and acted as the thrust front located to the west of the subduction wedge. At present, the thrust front has migrated southwestward to the west of the collision prism. The arc-continent collision propagated southwards and yielded the time-transgressive deformations from north to south to result a south tapering configuration of Taiwan. This paper is the first to recognize the consistent occurrence of the subduction wedge and collision prism onshore and offshore Taiwan. This allows reconstruction of the tectonic evolution of the accretionary prism during the subduction and collision tectonics of Taiwan.

A Pump Instability Theory Using an Acoustic Feedback Mechanism

A subsynchronous vibration problem with a large water injection pump was solved in 1974 by modifying the discharge piping transition to a long taper configuration. This paper describes a quantitative theory based upon the dynamic modeling of the pump rotor and piping system. The model successfully duplicates the experimental results of the pump instability and reproduces the subsynchronous vibration described in the original paper. The analysis results in a log decrement of the system that is dependent upon the time delay of the acoustic pulsation. It shows that the system can be driven unstable for acoustic path lengths that are much less than the quarter wavelength. The analysis also shows the log decrement is minimized when the time delay is equivalent to exactly that of one eighth wavelength of the resonant frequency of the pump.

Optical fiber-polymer guide coupling by a tapered graded index glass guide

A new four layer tapered coupler (FLTC) has been studied and tested, able to transfer light efficiently from a monomode fiber to a polymer film guide by means of an auxiliary graded index glass waveguide. A simple theory has been developed to calculate the maximum efficiency of these structures. Experiments have been performed, at /spl lambda/=1.321 /spl mu/m, on several FLTC samples, containing K/sup +/-Na/sup +/ ion-exchanged glass waveguides and spin coated poly-3BCMU films. Insertion losses in the range 3-6.5 dB have been measured, depending on the taper configuration. The agreement between theoretical and experimental data is good, provided that a suitable ripple of the taper profile is assumed. The application of the new coupler to future integrated waveguide systems, including passive glass components and polymer based all optical devices, is assessed. >

Magnetic performance of a variable period, fast excitation, wiggler

With the objective of carrying out an Inverse Free Electron Laser (IFEL) electron accelerator experiment, an iron dominated (Vanadium Permandur) fast excitation, laminated (variable period length) planar wiggler, making use of copper field reflectors, has been constructed and has been measured in several period length tapering configurations. This report presents an analysis and experimental results of this wiggler, typically of which the parameters are /spl lambda/(w)=3.7 cm, B(max)=1.8 T. >

The Utility of a Ghost Horizon and Climb/Dive Ladder Tapering on a Head-Up Display

As part of an Air Force effort to standardize HUD symbology, an unusual attitude recovery task was employed to investigate the utility of a cue, the ghost horizon, that indicates the direction of the actual horizon when the climb/dive ladder horizon line is not within the HUD field of view. Six HUD-experienced and 6 non-HUD-experienced military pilot subjects were used to determine whether there was improvement, with the ghost horizon, in ability to recover from nose-down unusual attitudes in a flight simulator. The ghost horizon was evaluated with 3 different climb/dive ladder line configurations (tapered, non-tapered, reverse tapered). In terms of accuracy of the initial stick input, the ghost-horizon configurations resulted in significantly better performance (about 11% better) than did the non-ghost-horizon configurations. The ghost horizon had no effect on initial stick input reaction time or total recovery time. The climb/dive ladder line taper configuration did not affect accuracy, initial stick input reaction time, or total recovery time. Subjective data indicated that the pilots did not have a strong preference for any of the configurations. These findings suggest that the ghost horizon is a useful aid to unusual attitude recovery performance, and may reduce spatial disorientation.

Atrophic Cell Processes of Large Motor Neurons in the Anterior Horn in Amyotrophic Lateral Sclerosis: Observation with Silver Impregnation Method

Investigation of silver-stained lumbar anterior horns in four autopsied cases of sporadic amyotrophic lateral sclerosis (ALS) revealed frequent extremely small cell processes originating from large motor neurons. Their perikarya were usually smaller in size than those of normal-looking ones and almost invariably had central chromatolysis-like changes, suggesting an intimate pathomorphological relationship between the perikarya and their processes. Although it was difficult to determine whether these small processes were atrophic dendrites or shrunken axons, some were recognized as dendrites from their multiple branchings and some were identified as axons from their tapering configuration followed by widening of the distal portion. Aggregates of lipofuscin were almost always present in the perikaryal portion from which an atrophic process arose. In addition, the somewhat argentophilic slender cytoplasm which in normal neurons separates lipofuscin from the cell surface and merges with the proximal part of a process, was prominently attenuated. The small processes were more frequently observed in cases with many spheroids and chromatolytic neurons. The change in the proximal portion of the processes may implicate some disturbance of functional connection between the soma and the cell processes in ALS.

Transmission characteristics of single-mode asymmetric dielectric waveguide Y-junctions

The transmission characteristics of asymmetric Y-junctions with different taper configurations have been investigated by using the beam propagation method. The Y-junctions treated here operate as a beam splitter in the single-mode range. It is found that the power splitting ratio depends strongly on the taper configuration and the junction angle. An oscillatory power splitting always occurs by the coupling between output branches when the junction angle is small. The Y-junction with no taper can be used for coupling out the greater part of power guided in the main waveguide.

Propagating beam analysis of multimode waveguide tapers

We analyze both slowly and rapidly varying tapers with the aid of the propagating beam method. Our results demonstrate that while the optimal longitudinal profile for slowly varying profiles is independent of the taper length, the optimum profile of a taper which varies rapidly with respect to the inverse of the average propagation constant difference of adjacent modes must be determined computationally in each case from the given values of its length and initial and final width parameters. We also analyze the region of validity of local normal mode perturbation theory in representative taper configurations.

Telescope retainers for removable partial dentures

Telescope crowns used in removable partial dentures reduce the destructive horizontal and rotational occlusal forces by directing them more axially an less traumatically than other retainers. These properties are combined with excellent conditions for cross-arch and multiple abutment splinting. If one of the abutment teeth needs extracting, the denture can be repaired with acrylic resin simply by remaking the secondary crown into a pontic. The single copings can be easily cleaned due to the good accessibility around their gingival margins. They also protect the abutment teeth against caries and thermal irritation. Soldering of the primary copings or their connection with accessory bars is not necessary in rigidly constructed telescope crowns, because the secondary crowns incorporated in the superstructure provide sufficient rigidity. In addition, the splinted copings often cause inflammatory gingival hyperplasia because the solder joints are too close to the gingival margins, preventing proper hygiene maintenance. The taper configuration or vertical height of the coping, which determines the amount of load transferred to each abutment, can be planned to suit each tooth's condition and designated function in the restoration. In a fixed restoration, the load is always evenly distributed among all the abutment teeth regardless of their condition, because the crowns are permanently cemented to them. In the telescope denture, the amount of force can be individually regulated by modifying the form and leverage of the retainers, according to their position, bone support, and occlusal conditions.

Efficient power combiner for multiplexing multiple sources to single-fiber optical systems

Efficient combining of optical power from three input optical fibers to a single trunk fiber is demonstrated using fibers of different core/cladding diameters in a biconical taper configuration. The combiners have insertion loss less than 1 dB and optical isolation greater than −50 dB.

Optimization study of anticlastic curvature of cylindrically bent strips with variable thickness

This paper presents a nonlinear extension of a previous investigation. Tapering the edges on the concave side of a longitudinally bent strip according to a power-law is studied aiming to alleviate the anticlastic deformations of the strip. Conjugate gradient method is employed to calculate the specific dimensions of power-law taperings which will reduce the peak-to-trough deflection of the cross-section of a bent strip to a minimum. Optimum tapering width and thickness ratios and thickness variation parameter are presented in graphic and tabular form. The influence of Poisson's ratio on the tapering configuration is discussed. The results show that power-law tapering can reduce the peak-to-trough deflection to less than 1 per cent of the thickness of the strip.