Fiber Position Research Articles

Few-mode fiber true time delay lines for distributed radiofrequency signal processing.

We report, for the first time to our knowledge, distributed radiofrequency signal processing built upon true time delay operation on a step-index few-mode fiber. Two 3-sample configurations with different time delay properties are implemented over the same 60-meter 4-LP-mode fiber link. The inscription of a long period grating at a specific fiber position converts part of the LP01 mode into the LP02, permitting sample time delay engineering. Delay line performance is experimentally demonstrated when applied to radiofrequency signal filtering, example of fiber-distributed processing functionality exhibiting one order or magnitude gain in terms of compactness.

CFD simulations of fiber-fiber interaction in a hollow fiber membrane bundle: Fiber distance and position matters

This CFD study aims to simulate the impact of fiber distance and position on fiber-fiber interaction within a bundle. In order to display the filtration performance of fibers at different positions, a hollow fiber membrane filtration setup based on nine fibers arranged in a 3 × 3 square array was constructed. A CFD porous media model approach was employed using the liquid phase as the main phase. The numerical simulation of multiphase flow on the average velocity of each fiber is validated by the experimental results. The presence of “bundle resistance” and “permeate competition” among fibers was confirmed by the axial liquid velocity simulation. When fiber distance was less than the fiber diameter, the interaction between fibers became notable due to “permeate competition”. When fiber distance was equal to fiber diameter, the “permeate competition” effect disappeared, while the “bundle resistance” became dominant within the bundle. When the fiber distance was larger than the fiber diameter, both “permeate competition” and “bundle resistance” could be neglected. The variations of fiber flux at different positions along the fiber height also proved the distribution of axial liquid velocity and sludge density in the bundle. These results highlight the difference between fiber distance and position in the bundle that ensured the fouling deposition.

3-D Measurement of Rollable Fiber Ribbons in 1000-Fiber Cable and Calculated Fiber Reliability

We propose a technique for the 3-D measurement of fiber position to allow the experimental evaluation of the fiber reliability of 1000-fiber high-density cables. We acquire the fiber positions from the position of peaks in a cross-sectional X-ray computed tomography image. We can evaluate the cable reliability by calculating the fiber strain imposed by bending and twisting from the fiber positions. To calculate the fiber strain, we also propose the models of the deformation of rollable optical fiber ribbon in a cable. The measured fiber positions coincide well with the deformation models that we proposed and revealed in which the calculated cable strains are almost the same as or lower than those that we estimated theoretically. Consequently, the equivalent strain is less than the allowable value needed for maintaining reliability when the other strain factors are the same as those of the conventional high-density cable.

Definition and quantification of drapeability through the measurement of constituent effects

Although considerable work has been carried out in the field of drapeability research, both the definition of what drapeability comprises as well as the tools to measure and quantify it must be further developed. This paper presents a definition of drapeability that is meant to broaden its scope to include not only the important effects of shearing and wrinkling, but all constituent effects such as gap formation, undulations, loops (tow buckling) and fabric anisotropy. This definition is completed by an experimental test device to measure and quantify all of these effects in a single, standardized setup (available as the Textechno Drapetest).The Drapetest utilizes optic measurement technology coupled with digital image analysis software to detect and measure fibre positions and orientation, and fabric topology. For each of the defined drapeability effects characteristic values were generated from this optical data that can describe the intensity, distribution and extent of the effect in question. The device and methodology was empirically validated using a set of 72 specially manufactured glass fibre NCF. The interdependencies between textile design, process parameters and drapeability effects as well as a semi-analytical equation for them are shown. A method to use these semi-analytical equations in the composite design process is introduced [1].

Effects of silkworm fiber position on flexural and compressive properties of silk fiber-reinforced composites

Background: Fiber-reinforced composites represent a combination of fiber-reinforced composite materials. The availability of fiber within dentistry in Indonesia is limited and, therefore, requires lengthy advance ordering. The increasing use of fiber derived from natural materials, such as silk, is of greater concern due to its considerable mechanical strength, biocompatibility and wider availability. The application of fiber will increase the mechanical strength of fiber-reinforced composites, including both flexural and compression strength. One factor affecting the mechanical strength of fiber is the laying of fiber or fiber position. Purpose: The purpose of this research is to establish the influence of silkworm fiber position on both the flexural and compression strength of silk fiber-reinforced composites. Methods: Flexural strength and compression strength tests using a universal testing machine involved the division of the research population into three treatment groups: compression side, neutral side and tension side. Results: The results of data analysis indicated that the tension side group possessed the highest flexural strength (121.42 MPa), while the compression side group demonstrated the highest compression strength (337.65 MPa). A one-way ANOVA analysis test produced a significant result of p = 0.000 (<0.05) both for silkworm fiber position effect and compression strength of silk fiber reinforced composites. Conclusion: The position of silkworm fiber will affect its flexural strength as well as that of the compression of silk fiber-reinforced composites.

Effect of Fiber Orientation and Position of Circular Hole on Torsional Natural Frequency of Laminated Composite Beam

Effect of Fiber Orientation and Position of Circular Hole on Torsional Natural Frequency of Laminated Composite Beam

A review on the assessment and prediction of the orientation and distribution of fibres for concrete

Fibres that cross the fracture surface govern the performance of fibre reinforced concrete (FRC), playing a major role in fracture results used to evaluate the structural competence of the composite material. Thus, FRC post-cracking behaviour is related to the number of fibres acting in the cracked surface and their forming angle. Both orientation and distribution of the fibres have been evaluated with several experimental techniques, while various models have assessed the prediction of such fibre positioning by using the orientation factor. This study aims to review the existing models found in the literature and improve their use to predict fibre positioning. Early models showed that the stereographical model could serve as a powerful tool as regards rigid fibres, whereas recent ones have assessed macro-synthetic fibre orientation and distribution. In addition, several external regular and standardised conditions that have been shown to affect the positioning of fibres are considered. The main sources of anisotropy are addressed: fresh-state properties of the concrete, pouring methods, compaction procedures, wall-effects and formwork geometries. In this review, practical tools and information extracted from the models are supplied that provide an interesting overview about predicting the orientation factor.

Preliminary research on focal plane calibration method in LAMOST based on flexible planar target

In the large sky area multiobject optical fiber spectroscopy telescope project, to capture the spectrum of a particular object, the optical fiber positioner must position the optical fiber end face to a specified location on the focal plane. The accuracy of the optical fiber positioner is guaranteed by feedback from photogrammetry. Photogrammetry accuracy is based on accurate calibration. However, given the complexities in the optical fiber focal plane and the optical fiber positioner, the accurate standard point is considerably difficult to obtain, which results in insufficient calibration accuracy. To solve this problem, a convenient calibration method based on the combination of small, planar targets is proposed. In this method, each optical fiber positioner positions the optical fiber to several designed locations, which are relatively accurate. These points form a high-precision, two-dimensional point array that can be used as the planar target. In this manner, each optical fiber positioner can be regarded as a small, high-precision planar target. All small, high-precision planar targets are assembled to form the flexible planar target, which is used for calibration. The experimental result indicates that this method is highly accurate and can be applied in focal plane calibration.

JUICES OF PRICKLY PEAR FRUITS (OPUNTIA SPP.) AS FUNCTIONAL FOODS

The prickly pear, (Opuntia spp.) is consumed mainly as fresh fruit. We characterized and quantified secondary metabolites, their antioxidant capacity in vitro in juice of ten Opuntia spp. variants. Gallic acid was abundant in most variants. Catechin and epicatechin isomers, and procyanidins B1 and B2 were present in most variants. Ascorbic acid content was higher than 84 mg. Betacyanins stand out in red-colored juices, betaxanthins in the yellow ones; this caused lack of relationship between antioxidant capacity and total phenolic content. The content of soluble fiber, sugars, betalains and ascorbic acid content position this juice as a functional food.

Heat insulation characteristics of multi-layer nonwovens

PurposeThis paper aims to deal with the thermal resistance of multilayer nonwovens. The effect of fibre denier, cross-sectional shape and positioning within the layers were analysed with respect to the thermal resistance. Moreover, effect of compression on thermal resistance of the multilayer nonwoven structure have also be studied.Design/methodology/approachThe study involves multiple layering of thermal bonded nonwoven webs and the effect of fibre denier and positioning of different nonwovens from the hot plate. To avoid the increase in thermal resistance because of the air gaps between layers, the nonwovens were enclosed within an acrylic frame to compress them to a thickness of 12 mm. Compressional behaviour of the nonwovens were tested at a rate of 5 mm/min with peak compressive load of 50 N. Multilayer nonwoven assemblies were tested for thermal resistance with compressive pressure of 3.5 gf/cm2 and compared with that tested at zero pressure.FindingsIn the study, three-layered nonwoven structure, provided better thermal resistance than their single component counterparts. The structural characteristic of the multilayer nonwovens affected the conductive, convective and the radiative heat transfer. In a multi-layer nonwoven, the top most layer should have the finest fibre as possible. Second preference may be given to the middle and followed by bottom layers in terms of fibre fineness. However, fine solid fibres performed poorly in terms of compression and recovery resulting in poor thermal resistance under compressive load.Originality/valueThe experimental approach of controlling thickness while evaluating the thermal resistance will help in nullify the effect of air gaps between the layer interface, thus focussing on the effect of fibre denier and the positioning of nonwovens. This paper also discusses the unique properties of fine solid fibre and hollow fibres and their role in providing better thermal insulation for extreme cold weather applications.

Draw Spinning of Wafer‐Scale Oxide Fibers for Electronic Devices

AbstractThe fabrication of functionalized 1D oxide fibers with accurate control of orientation, location, and number is highly demanded and challengeable based on current techniques, which hinder their practical application in opto/electronic devices. Herein, a rapid and simple method is developed to directly draw the oxide fibers from its polymer solution over large area. The draw‐spinning method enables the accurate positioning of individual fiber and the construction of complex patterns, holding great potentials in fiber‐based electronics. The assembled field‐effect transistors (FETs) based on single indium oxide (In2O3) fiber exhibit excellent current modulation capability with a high on/off current ratio of 106. Adjusting the number of fibers within the channel, the device performance can be modulated. Moreover, the draw‐spinning technique is applied to fabricate highly aligned fiber arrays by using brush pen. The FETs based on aligned In2O3 fiber arrays exhibit superior current‐driven capability compared with the devices with limited number of fibers. Their further integrations on high‐permittivity dielectric layer show improved device performance at an operating voltage of 4 V. This method is scalable and can be implemented easily to fabricate various functional fibers in both laboratory and industrial manufacturing.

Fiber motion and the accelerated point distribution in roller drafting

In this study, the tracer fiber method was used to determine the accelerated point distribution in both the break draft and main drafting zone of the drawing frame with varying different draft parameters. Viscose, cotton, and polyester slivers were used respectively. For the different parameters, the tracer fibers of known length were embedded in the single sliver strand, and measurements of their positions before and after drafting were taken. These measurements of the positions of tracer fibers before and after drafting were then used to deduce the nature of the fiber movement, thus determining the distribution of the accelerated points. The accelerated point distribution under different parameters was obtained. Gauss distribution was found to suitably describe the accelerated point distribution curve under different parameters used in this study. The pressure bar to some degree imparts a significant control of floating fibers within the drafting zone. The relationship between the sliver unevenness and the accelerated point variance (CV) was also discussed.

V03-05 TREATMENT OF LARGE KIDNEY STONES BY USING ROBOTIC ASSISTED FLEXIBLE URETEROSCOPY

You have accessJournal of UrologyUrolithiasis & Endourology1 Apr 2018V03-05 TREATMENT OF LARGE KIDNEY STONES BY USING ROBOTIC ASSISTED FLEXIBLE URETEROSCOPY Remzi Saglam, Anup Patel, Jens Rassweiler, Jan Klein, Yasser Farahat, Abdulqadir Al Zarooni, Selahattin Bedir, Ahmet Müslümanoglu, Zafer Tokatli, and Kemal Sarica Remzi SaglamRemzi Saglam More articles by this author , Anup PatelAnup Patel More articles by this author , Jens RassweilerJens Rassweiler More articles by this author , Jan KleinJan Klein More articles by this author , Yasser FarahatYasser Farahat More articles by this author , Abdulqadir Al ZarooniAbdulqadir Al Zarooni More articles by this author , Selahattin BedirSelahattin Bedir More articles by this author , Ahmet MüslümanogluAhmet Müslümanoglu More articles by this author , Zafer TokatliZafer Tokatli More articles by this author , and Kemal SaricaKemal Sarica More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.830AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES International guidelines universally recommend PCNL as the treatment of choice for large renal stones. In the past decade, many centers have reported on classical retrograde intra-renal surgery for large renal stones. Recently Robotic Assisted Retrograde Intrarenal Surgery provides better stone free rates with some more advantages for the patient, user and the endoscopic device. METHODS This video demonstrates the step-by-step technique and advantages of Avicenna Roboflex robotic assisted retrograde intra-renal surgery (RA-RIRS), the latest iteration of master-slave robotics in this field. Due to reduced invasiveness, the patient, a 50 year old Iraqi general surgeon, preferred this approach over PCNL. Non-contrast CT showed a large (2941.5mm3) left renal stone, with 1076 bone window Hounsfield units. Our previous studies have shown: a) an upper stone volume limit of 4000mm3 with HU of 1000 for RA-RIRS, yielding 89% single-session stone free rate; b) that ureteral access sheath size >11/13Fr allows 35 ml/min. irrigation without raising intra-renal pressure >25 cm water, optimizing safety and vision, while allowing irrigant and dust efflux compared to smaller sheaths. RESULTS The RA-RIRS procedure was uncomplicated. Optimized efficiency led to single stage complete stone fragmentation (stone dusting time 74 minutes, fragmentation efficiency 32 mm3/min). RA-RIRS benefits to the surgeon included improved comfort + ergonomics, touch-screen adjustable endoscope motion scaling, laser fiber positioning, control of respiratory excursion + irrigation flow and less fatigue (no lead protection required). CONCLUSIONS The Avicenna Roboflex allows safe, efficient single stage treatment of renal stones larger than is recommended by current international guidelines. Key design features optimize patient safety and instrument longevity significantly compared to manual operation and by reducing surgeon fatigue, optimizes potential for efficiency. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e323 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Remzi Saglam More articles by this author Anup Patel More articles by this author Jens Rassweiler More articles by this author Jan Klein More articles by this author Yasser Farahat More articles by this author Abdulqadir Al Zarooni More articles by this author Selahattin Bedir More articles by this author Ahmet Müslümanoglu More articles by this author Zafer Tokatli More articles by this author Kemal Sarica More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Experimental and numerical characterization of thin woven composites used in printed circuit boards for high frequency applications

The elastic orthotropic behavior of thin woven composites is studied combining a numerical and experimental strategy. For thin materials, in-plane properties are measured by classical tensile tests and digital image correlation. The out-of-plane properties are derived performing finite element simulations at the level of the internal structure of the laminate. Indeed, the glass fiber arrangement in the yarn and the weaving pattern are defined based on microtomography and SEM observations. So a representative unit cell is found. A statistical approach is further proposed to derive the behavior of the warp and fill yarns, since the fiber position may fluctuate between yarns. For the considered laminate, the matrix (resin and ceramic inclusion) behavior is unknown and difficult to measure. Therefore an inverse method is proposed. By comparing with measured in-plane elastic moduli, behaviors of the matrix, of yarns and of the laminate are defined. The present homogenization strategy is exemplified by laminates used in printed circuit boards for high frequency applications. This approach has also been applied to investigate the evolution of the elastic moduli of the laminate with temperature. Those information, usually not available in the literature, are important when dealing with reliability of printed circuit boards during thermal cycles.

An anisotropic friction model in non-bonded flexible risers

The present paper addresses small scale friction tests and an anisotropic friction model to predict friction for the interface between the anti-wear tape and tensile armors in non-bonded flexible risers. Small scale friction tests were carried out to study the static and dynamic friction behavior, measuring the transition distance between static and dynamic friction and the associated friction coefficients under variable contact pressure. In addition, the anti-wear tape shear modulus was measured to validate the analytical solution of shear interaction stick stiffness, K0, applied in previously proposed friction models. As grooves in the anti-wear tape surface were observed in the full scale test pipe, an anisotropic friction model was formulated and implemented into a computer code. Since the slip behavior will be influenced by the friction scaling factors, the K0 and the sliding direction, numerical studies were carried out to investigated their effects on the friction forces and the axial stress ranges at the outermost fiber position. This was followed by a sensitivity study with respect to the effect of applying 1D (loxodromic) and 2D (geodesic) friction models on the axial stress range at the same position. At last, the effect of applying measured transition behavior in the static friction model was investigated.

Experimental exploratory study of failure modes in models of wooden rectangular beams of Hymenae spp

According to the study of mechanical properties, wood is an elastic or elastoplastic material that presents different structural behaviour when tensioned or compressed. From the viewpoint of elasticity, wood is con-sidered anisotropic, or rather it is a material with elastic properties that vary with the direction considered. During tree growth, the internal structure of the solid material consisting of the wood becomes highly orient-ed and therefore anisotropic. To study the failure modes of wooden parts and to observe their anisotropy in this process, we performed a series of exploratory tests on models of beams, taking into account the different positions of fibers and growth rings and the different relationships between height and length for a specific specie of wood, in other words, a test with tangent, radial and inclined load applied to the fibers. The pieces were made of dicotyledonous wood that was first category and free of defects, making a total of nine samples in three groups. Failure by shearing and normal stresses was observed and was well characterized in terms of records left in the samples. In addition, when describing the failure modes, the results are discussed with the presentation of images and graphics for each case. Keywords: Anisotropy, Failure modes, Beams, Wood, Experimental exploration.

ProtoDESI: First On-Sky Technology Demonstration for the Dark Energy Spectroscopic Instrument

The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the universe using the baryon acoustic oscillations technique. The spectra of 35 million galaxies and quasars over 14,000 square degrees will be measured during a 5-year survey. A new prime focus corrector for the Mayall telescope at Kitt Peak National Observatory will deliver light to 5,000 individually targeted fiber-fed robotic positioners. The fibers in turn feed ten broadband multi-object spectrographs. We describe the ProtoDESI experiment, that was installed and commissioned on the 4-m Mayall telescope from 2016 August 14 to September 30. ProtoDESI was an on-sky technology demonstration with the goal to reduce technical risks associated with aligning optical fibers with targets using robotic fiber positioners and maintaining the stability required to operate DESI. The ProtoDESI prime focus instrument, consisting of three fiber positioners, illuminated fiducials, and a guide camera, was installed behind the existing Mosaic corrector on the Mayall telescope. A fiber view camera was mounted in the Cassegrain cage of the telescope and provided feedback metrology for positioning the fibers. ProtoDESI also provided a platform for early integration of hardware with the DESI Instrument Control System that controls the subsystems, provides communication with the Telescope Control System, and collects instrument telemetry data. Lacking a spectrograph, ProtoDESI monitored the output of the fibers using a fiber photometry camera mounted on the prime focus instrument. ProtoDESI was successful in acquiring targets with the robotically positioned fibers and demonstrated that the DESI guiding requirements can be met.

Mechanical Properties of Continuous Kevlar Fiber Reinforced Composites Fabricated by Fused Deposition Modeling Process

Additive Manufacturing (AM) is a promising technology because of the capability of fabricating complex freeform structures. Due to the rapid developing of AM techniques, the applications of AM are no longer limited to rapid prototyping. Functional parts can be directly fabricated by AM to satisfy given design requirements. Fused Deposition Modeling (FDM), one of the most widely used AM technique, has recently been modified to print continuous fiber reinforced thermoplastic materials. This research conducted experiments to understand the tensile property of 3D printed fiber reinforced composite materials. The fiber orientation, the volume fraction, and the position of fibers are considered in this study. The elastic modulus, yield strength, and the ultimate tensile strength have been calculated based on experimental results. Design guidelines for 3d printed continuous fibers are presented in this paper for designers to develop innovative products. Furthermore, some limitations of current FDM process in the fabrication of fiber reinforced composites are also discussed.

Integrated Lloyd's mirror on planar waveguide facet as a spectrometer.

A low-cost and simple Fourier transform spectrometer based on the Lloyd's mirror configuration is proposed in order to have a very stable interferogram. A planar waveguide coupled to a fiber injection is used to spatially disperse the optical beam. A second beam superposed to the previous one is obtained by a total reflection of the incident beam on a vertical glass face integrated in the chip by dicing with a specific circular precision saw. The interferogram at the waveguide output is imaged on a near-infrared camera with an objective lens. The contrast and the fringe period are thus dependent on the type and the fiber position and can be optimized to the pixel size and the length of the camera. Spectral resolution close to λ/Δλ=80 is reached with a camera with 320 pixels of 25μm width in a wavelength range from O to L bands.

Model-based image analysis of a tethered Brownian fibre for shear stress sensing.

The measurement of fluid dynamic shear stress acting on a biologically relevant surface is a challenging problem, particularly in the complex environment of, for example, the vasculature. While an experimental method for the direct detection of wall shear stress via the imaging of a synthetic biology nanorod has recently been developed, the data interpretation so far has been limited to phenomenological random walk modelling, small-angle approximation, and image analysis techniques which do not take into account the production of an image from a three-dimensional subject. In this report, we develop a mathematical and statistical framework to estimate shear stress from rapid imaging sequences based firstly on stochastic modelling of the dynamics of a tethered Brownian fibre in shear flow, and secondly on a novel model-based image analysis, which reconstructs fibre positions by solving the inverse problem of image formation. This framework is tested on experimental data, providing the first mechanistically rational analysis of the novel assay. What follows further develops the established theory for an untethered particle in a semi-dilute suspension, which is of relevance to, for example, the study of Brownian nanowires without flow, and presents new ideas in the field of multi-disciplinary image analysis.