Showing papers on "Bend radius published in 2011"

Ultra-low-loss high-aspect-ratio Si3N4 waveguides.

Abstract: We characterize an approach to make ultra-low-loss waveguides using stable and reproducible stoichiometric Si3N4 deposited with low-pressure chemical vapor deposition. Using a high-aspect-ratio core geometry, record low losses of 8-9 dB/m for a 0.5 mm bend radius down to 3 dB/m for a 2 mm bend radius are measured with ring resonator and optical frequency domain reflectometry techniques. From a waveguide loss model that agrees well with experimental results, we project that 0.1 dB/m total propagation loss is achievable at a 7 mm bend radius with this approach.

Planar waveguides with less than 0.1 dB/m propagation loss fabricated with wafer bonding.

Abstract: We demonstrate a wafer-bonded silica-on-silicon planar waveguide platform with record low total propagation loss of (0.045 ± 0.04) dB/m near the free space wavelength of 1580 nm. Using coherent optical frequency domain reflectometry, we characterize the group index, fiber-to-chip coupling loss, critical bend radius, and propagation loss of these waveguides.

Encapsulation for Flexible Electronic Devices

Abstract: Flexible electronic devices are influenced by mechanical impacts or bending. This mechanical stress can damage brittle inorganic thin-film layers. One way to improve the stability of such devices is to encapsulate them. For this reason, we encapsulate brittle inorganic materials in our thin-film transistors (TFTs) on flexible polyimide (Kapton) substrates by gluing a second patterned flexible polyimide substrate on top. The developed encapsulation method has the advantages of low process temperatures and micrometer alignment between features on the two substrates and does not damage any thin-film device layer. We are able to bend encapsulated TFTs down to a radius of 125 μm without loss of functionality. At this bending radius, the saturation mobility decreases by 3%, and the threshold voltage shifts by 0.2 V. Compared with nonencapsulated TFTs, we decrease the bending radius before the devices fail by an order of magnitude.

Optical waveguide, optical waveguide module and method for forming optical waveguide

Abstract: An optical waveguide comprising a core and a clad characterized in that a desired part is heated and transited to machining strain release state, the part transited to the machining strain release state is curved with a specified bending radius and transited to machining strain state. That part of the optical waveguide is heated to a temperature within a range between the bending point and softening point and transited to machining strain state. The optical waveguide is an optical fiber having the outer diameter not shorter than 50 μm. The optical waveguide has the outer diameter not shorter than ten times of the mode field diameter of the optical waveguide. The optical waveguide has a bending radius of 5.0 mm or less and difference equivalent of refractive index Δ1 between the core and clad falls within a range of 0.8-3.5%.

Large mode area optical fibers with bend compensation

Abstract: A LMA, single-mode optical fiber comprises a core region, an inner cladding region surrounding the core region, and an outer cladding region surrounding the inner cladding region. The inner cladding region is configured to provide bend compensation. In one embodiment the index profile of the inner cladding region is graded with a slope of γn core /R b , where n core is the refractive index of the core region, R b is the bend radius, and γ= 0.6-1.2. In addition, the inner cladding is annular and the ratio of its outer radius to its inner radius is greater than 2. In a preferred embodiment this ratio is greater than 3. The overall index profile may be symmetric or asymmetric.

Variable stiffness steering mechanism for catheters

Abstract: A catheter assembly including a tapered steering spine having a varying stiffness along an axial length. The tapered steering spine is tailored to provide increasing flexibility from proximal to distal in a way that makes the bend radius more uniform along the length of the steering section. In one embodiment, the tapered steering spine includes structures on adjacent rings that engage with each other when the steering section is flexed to limit the minimum bend radius to a predetermined minimum and which enhances the torsional rigidity of the steering section regardless of the degree of flexure of the steering section. The limited bend radius can prevent excessive bending of components such as fiber optics. The enhanced torsional rigidity can negate the need for torque braid in the section of the catheter shaft that surrounds the tapered steering spine.

Strength of composite angle brackets with multiple geometries and nanofiber-enhanced resins

Abstract: The purpose of this study was to investigate the change in strength and failure mode of composite angle brackets due to changes in both the angle bend radius and laminate thickness, as well as the addition of vapor-grown carbon nanofiber to the epoxy resin matrix. The brackets explored within this study each contained a 90° bend and was subjected to four-point bend loading. Such angle brackets exhibit weakness around the radius due to the excessive through-the-thickness tensile stresses which can lead to delamination. Composite brackets of 8- and 16-plies were examined, with bend radii of 3.175 and 6.35 mm. The composites consisted of Hexcel AS4 carbon fiber, five-harness satin weave, and Epon 862/Epikure W epoxy resin. Specimens were fabricated with and without ASI PR-24 vapor-grown carbon nanofiber in the epoxy matrix. A servo-hydraulic load frame was used to perform a four-point-bend test as per American Society for Testing and Materials International D6415 for measuring the curved beam strength (CBS) ...

Limitation on Effective Area of Bent Large-Mode-Area Leakage Channel Fibers

Abstract: We investigate the bending characteristics of leakage channel fibers (LCFs) to achieve large mode area (LMA) and effectively single-mode operation with a practically allowable bending radius for compact Yb-doped fiber applications. Through numerical simulations, carried by the full-vectorial finite-element method, we present the limitations on the effective area of LCFs under bent condition and compare their limits with that of conventional step-index LMA fibers. Due to a better controllability of the low numerical aperture and a large value of the differential bending loss (~20 dB/m) between the fundamental and higher order modes in LCFs, the LMA of ~500 μm2 (core diameter of ~36 μm) at 1064 nm can be achieved when the optimized LCF is bent into a 10 cm bending radius.

Testing of flexible InGaZnO-based thin-film transistors under mechanical strain

Abstract: Thin-film transistors (TFTs) fabricated on flexible plastic substrates are an integral part of future flexible large-area electronic devices like displays and smart textiles. Devices for such applications require stable electrical performance under electrical stress and also during applied mechanical stress induced by bending of the flexible substrate. Mechanical stress can be tensile or compressive strain depending on whether the TFT is located outside or inside of the bending plane. Especially the impact of compressive bending on TFT performance is hard to measure, because the device is covered with the substrate in this case. We present a method which allows us to continuously measure the electrical performance parameters of amorphous Indium-Gallium-Zinc Oxide (a-IGZO) based TFTs exposed to arbitrary compressive and tensile bending radii. To measure the influence of strain on a TFT it is attached and electrically connected to a flexible carrier foil, which afterwards is fastened to two plates in our bending tester. The bending radius can be adjusted by changing the distance between these plates. Thus it is possible to apply bending radii in the range between a totally flat substrate and ≈1 mm, corresponding to a strain of ≈3.5%. The tested bottom-gate TFTs are especially designed for use with our bending tester and fabricated on 50 μm thick flexible Kapton® E polyimide substrates. To show the different application areas of our bending method we characterized our TFTs while they are bent to different tensile and compressive bending radii. These measurements show that the field effect mobilities and threshold voltages of the tested a-IGZO TFTs are nearly, but not absolutely, stable under applied strain, compared to the initial values the mobilities shift by ≈3.5% in the tensile case and ≈−1.5% in the compressive one, at a bending radius of 8 mm. We also measured the influence of repeated bending (2500 cycles over ≈70 h), where a shift of the performance parameters can be observed, too. The saturation mobility of the flat device decreases by 4.5%, and the threshold voltage raises 0.1 V. These results show that it is possible to characterize the influence of different kinds of bending on flexible thin-film devices in a very reliable way with one experimental setup.

Fabrication and testing of Rutherford-type cables for react and wind accelerator magnets

Abstract: LBNL#45189 SC-MAG 708 Fabrication and Testing of Rutherford-type Cables for React and Wind Accelerator Magnets P. Bauer, G. Ambrosio, N. Andreev, E. Barzi, D. Dietderich, K. Ewald, M. Fratini, A.K. Ghosh, H.C. Higley, S.W. Kim, G. Miller, J. Miller, J. Ozelis, R.M. Scanlan Abslract- A common coil design for a high-field accelerator dipole magnet using a Nb~n cable with the React-aDd-Wind approach is pursued by a collaboration between Fermilab and LBNL. The design requirements for the cable include a high operating current so that a field of 10-11 T can be produced, together with a low critical current degradation due to bending around a 90 mm radius. A program, using ITER strands of the internal tin type, was launched to develop the optimal cable design for React-aDd-Wind common coil magnets. Three prototype cable designs, all 15 mill wide, were fabric. ltcd: a 41- strand cable with 0.7 mm diameter strands; a 57~stralld cable with 0.5 mm diameter strands; and a 259~strand multi·level cable with a 6·around-l sub-element using 0.3 mm diameter wire. Two versions of these cables were fabricated: one with no core and one with a stainless steel core. Additionally, the possibility of a wide (22 rom) cable made from 0.7 mOl strand was explored. This paper describes the first results of the cable program including reports on cable fabrication and reaction, first winding tests and first results of the measurement of the critical current degradation due to cabling and bending. magnets is the cable, which must be designed to bend around a 90 mm radius with a low degradation of tile critical current «15%). If the wire is reacted on a spool with twice tile minimum coil bending radius, the maximum bending strain in the conductor will be equal in the straight section and in the ends of the magnet. The bending strain depends on the strand diameter used for the cable. In addition, the bending strain can be smaller or larger, depending on whether the layers of strands in the cable stick together or slide during cable bending. A R&D program [4] was launched to develop the optimal cable design for a react and wind common coil dipole. The strand chosen for the program was left-over ITER type wire manufactured by IOC. To keep bending strain below acceptable levels the strand diameter was restricted to '.5.0,7 mm. The material was drawn to the nominal wire sizes and sent to LBNL for cabling. Witi, tile high current requirement for the magnet (15-20 kA) ·a high aspect ratio cable design was pursued. The cables produced for the test program are described next. II. PROTOTYPE CABLE FABRICA nON AND REACTION Index Terms-Accelerator, superconducting cable, Nb 3 Sn. superconducting magnet, l. INTRODUCTION ECENlLY, a number of Nb,Sn dipole magnets have been built and tested in order to demonstrate the feasibility of using a brittle superconductor with a cosine theta winding approach [I]. The small bending diameters associated with the poles of cosine theta cross section dipoles require that the cable be wound in the unreacted condition in order to prevent damage to the Nb,Sn superconductor. An alternative design concept, the common coil design [2], utilizes flat pancake coils with large bending radii, and allows tile consideration of a react and wind technique for fabrication of coils [rom Nb,Sn or other brittle superconductors. Several designs for II T common coil dipoles were developed at FNAL in the past year [3]. All designs utilize Nb,Sn wire, with a J, (12 T, 4.2 K)=2000 Almm'. The key feature of these R Three cables with width 15 mm were chosen [or evaluation: (I) a 41 strand cable with 0.7 mm diameter strands, (2) a 57 strand cable with 0.5 mm strands, and (3) a 259 strand cable with 0.3 mm strands. The 259 strand cable is made in two steps--a first stage 6-around-1 cable and a seeond stage conSisting of 37 first stage elements cabled into the standard flat Rutherford-type cable (Fig. I). Manuscript received Sept 17, 2000. This work was supported by the U.S. Department of Energy. - -' P. Bauer, G. Ambrosio, N. Andreev E. Bani, K. Ewald, M. Fratini, S.W. Kim are with Fennilab, Batavia, IL 60510 USA (telephone: 630-840-5409, e-mail: pbauer@fnal.gov). D. Dietderich, H. C Higley, R. Scanlan are with Lawrence Berkeley Lab, Berkeley, CA 94720 USA. G. Miller, J. Miller are wi th the National High Magnetic Field L1.b, Tallahassee, FL 323 10 USA. A.K. Ghosh is with Brookhav

Prediction of wrinkling in thin-walled tube push-bending process using artificial neural network and finite element method:

Abstract: The tube push bending process is a method that is mainly used to bend thin-walled tubes with a small bending radius. In this paper, artificial neural networks (ANNs) are used to predict the creation of wrinkling in a tube during the bending process. Since training the neural network involves many datasets and all of these data are difficult to generate using experiments, a credible finite element (FE) model is developed. The results obtained from the FE model are validated by conducting experimental tests. The results of the FE simulations are used to train, test, and validate the ANN models. Backpropagation neural networks based on the Levenberg–Marquardt algorithm are constructed using five design parameters including: relative bending radius; relative tube diameter; friction between die and tube; friction between tube and mandrel; and pressure as the network inputs and the maximum wrinkling height (MWH) as the single output. Two different ANN models are trained for two types of tube materials: brass an...

Optimum design of pipe bending based on high-frequency induction heating using dynamic reverse moment

Abstract: Pipe bending by high-frequency local induction heating is an advanced technique used to bend pipes having a small bending radius and a large diameter Although pipe bending is a widely used engineering process, the optimum process parameters are decided on the basis of a trial and error method by highly experienced field engineers Hence, it is necessary to develop an integrated methodology for the optimum design of the pipe bending process During hot-pipe bending using induction heating, the thickness of the outer wall of the pipe decreases because of tensile stress, but the thickness is not allowed to decrease by more than 125% The use of the DOE method and a dynamic reverse moment is proposed for maintaining the thickness reduction ratio to within 125%, when D/t is high The results of the proposed approach are found to be in good agreement with those of FEA

Crash sensor for motor car, has deformable hose with cavity and pressure sensor for acquisition of pressure change in cavity of hose, where crash is resilient, and hose is made of cross linked silicone material

Abstract: The sensor has a deformable hose (3) with a cavity and a pressure sensor for acquisition of pressure change in a cavity of the hose. The crash is resilient, and the hose is made of cross linked silicone material. The silicone material has shore hardness of 40-80. The hose has internal diameter of 2.5-6mm and outer diameter of about 12mm. The hose has length (3L) of about 2.3m and bending radius of less than 25mm.

Fixing device for high-voltage cable joint

Abstract: The utility model relates to a fixing device for a high-voltage cable joint, comprising at least two groups of pipe clamp seats Each group of pipe clamp seats comprises a bracket, and an upper pipe clamp and a lower pipe clamp which are respectively semicircular, are arranged oppositely to form a cylinder shape, and are movably connected, wherein the bracket is shaped like an inverted T; the upper part of the bracket is connected with the lower pipe clamp, and two sides of the lower part of the bracket are provided with installing holes; and the brackets of all the groups of pipe clamp seats are connected by connecting boards The fixing device has the characteristics that the structure is simple, the application is convenient, the fixing of the cable joint is firm, an outer sheath of a cable is protected, and proper curve bending radius is formed and the like

The use of a bent singlemode-multimode-singlemode (SMS) fiber structure for vibration sensing

Abstract: A bent singlemode-multimode-singlemode (SMS) fiber structure based vibration sensor is proposed and developed. This sensor configuration is very simple and employs a bent SMS fiber structure and a narrow band optical source such as a laser. The vibration applied to the bent SMS fiber structure will change the bend radius and hence the intensity of the transmitted optical power will also vary. Experimental results show that the sensor can detect vibration frequencies over a broad range with good sensitivity, from hertz to a few kHz.

Bending and horizontal type reshaping method of high-pressure bend

Abstract: The invention relates to a bending and horizontal type reshaping method of a high-pressure bend, mainly comprising the following steps of: 1, feeding a tube blank with the outer diameter of D(1+delta) and same wall thickness as that of the bend; 2, heating a straight tube blank into a austenite structure, and then placing on a concave mould of a bending mould preheated to 200-300 DEG C, wherein aconvex mould downwards moves with a cross beam positioned on a press till the convex mould and the concave mould are closed for pressing bending deformation, after the bending mould is closed, the section of a cavity perpendicular to an axial line is in the shape of an ellipse, a long axis of the ellipse is 1.2 times of the nominal diameter of the bend, a short axis of the ellipse is 0.8 times ofthe nominal diameter of the bend, and the bending radius of the middle of the convex mould is set to be 1.5-2.0 times of the radius of the bend to prevent the contact area of the middle of the tube blank and the convex mould from collapses so that the tube blank is integrally bent and the section of the tube blank is changed into the shape of the ellipse at the same time; 3, horizontally placing the tube blank which is initially formed after being bent in a concave mould cavity of a reshaping mould preheated to 200-300 DEG C, wherein the motion direction of the long axis of the sectional ellipse of the tube blank is the same as that of a reshaping convex mould, the reshaping mould is combined vertically so that the tube blank undergoes circumferential compression, and the elliptical section of the tube blank is reshaped into a circular section. According to the invention, the production efficiency is greatly enhanced, and the designing and processing periods of a mould are shortened; in addition, the bending and the reshaping moulds are simple and are easy to operate, so that vast manpower and material resources are saved.

A General Scaling Rule for Matched Bend Waveguides

Abstract: A scaling rule is introduced for reducing the dimensions of a matched waveguide bend without inducing additional transition loss and applied to photonic integrated circuits employing high index contrast waveguides. Mathematical expressions describing the wave propagation in the bend are obtained via a combination of analytical analysis and numerical calculations. These expressions show that if the bend radius R shrinks discretely by n=(m1/m2)3 times, where m1 and m2 are the integer number of beat lengths in the original and scaled matched bends, respectively, and the effective width of the waveguide is reduced also by n1/3 times, then the loss of the matched bend (straight-curved-straight waveguide) transition will remain constant.

Method and system for monitoring bend and torque forces on a drill pipe

Abstract: A system and method for monitoring bend radius and torque force exerted on a drill string. A sensor system is supported within a pipe section of the drill string and has a light source supported within the pipe section to emit a light beam within the pipe section. An optical sensing device is supported within the pipe section and spaced apart from the light source. The optical sensing device transmits a detection signal indicative of the position of the light beam on a surface of the optical sensing device to a processor that determines the bend radius and torque force exerted on the pipe section.

Method for mounting electrical cable and cable protection apparatus to support

Abstract: A method of mounting an electrical cable (28) to a support structure (2) of an offshore electricity generating apparatus is disclosed. The method comprises mounting a cable protection apparatus (30) to an external surface of the support structure, wherein the cable protection apparatus comprises a plurality of first elements interconnected to define a channel for receiving the cable, wherein each first element is prevented from pivoting through more than a predetermined angle relative to a further first element attached thereto. The cable protection apparatus is mounted to the electrical cable such that the cable protection apparatus prevents the cable being bent around a bend radius smaller than a predetermined minimum bend radius and the cable protrudes from a lower end of the cable protection apparatus when mounted to the support structure.

Composite optical waveguide, variable-wavelength laser, and method of oscillating laser

Abstract: A composite optical waveguide 1 includes a first optical waveguide 9 comprising a silica-based core and a second optical waveguide 11 comprising an Si-based core. The second optical waveguide 11 is joined to the first optical waveguide 9 . The length of the first optical waveguide 9 corresponds to a permissible propagation loss of the second optical waveguide 11 . The second optical waveguide 11 includes a sharply curved portion 13 having a radius smaller than the minimum bend radius of the first optical waveguide 9.

Holey single-mode optical fiber and optical transmission system using same

Abstract: Provided is a holey single-mode optical fiber including a core not having holes, and a clad having holes extending in a longitudinal direction, in which a refraction index of the core is larger than that of a portion of the clad other than the holes, a radius r1 of the core is within a range of 2.2 to 3.2 μm, a relative refraction index difference Δ of the core to the clad is within a range of 0.3 to 0.56%, a distance Rin between a center of the core and an inner edge of the holes is 2.0 to 3.5 times the radius r1 of the core, an air-filling fraction F is within a range of 30 to 50%, a cable cut-off wavelength is 1.0 μm or less, a zero-dispersion wavelength is within a range of 1260 to 1460 nm, and a bending loss characteristic at a bending radius of 10 mm is 10 dB/m or less.

Zero power consumption visual curvature sensor by flexible interferometer

Abstract: A visual curvature sensor by using multilayer Fabry-Perot color interferometer and printing process was proposed and realized. Owing to the pure mechanical distortion of the interferometer by external force, the remotely visible color change, the enhancement of color contrast, and pattern contouring by automatic analytical systems, the curvature sensor provided high sensitivity with bending radius as large as 107.2 mm without any power consumption. This curvature sensor is designed especially suitable for monitoring applications such as in the vacuum or toxic environment. The simple printing process and structure design also made the curvature sensor eligible for mass low-cost production with variable sizes. The design concepts, process detail, and performance evaluations are introduced and discussed in this article.

Optical usb cable with controlled fiber positioning

Abstract: Methods of controlling the position of an optical fiber having a minimum bend radius within an optical fiber channel in a fiber optic cable having a small footprint are disclosed. The position of the optical fibers is controlled so that the fiber is not bent at a radius below its minimum bend radius.

Manufacturing method of creeping-resisting aluminium alloy conductor interlocking armoring optical-fiber composite low-voltage cable

Abstract: The invention relates to a manufacturing method of a creeping-resisting aluminium alloy conductor interlocking armoring optical-fiber composite low-voltage cable, comprising the following steps: (1) manufacturing an aluminium alloy rod; (2) manufacturing a round single wire; (3) drawing a heterotypic single aluminium wire; (4) carrying out thermal refining to obtain a heterotypic soft aluminium single wire; (5) carrying out twisting to finish a conductive wire core; (6) extruding an insulating wire core; (7) carrying out cable laying; (8) carrying out interlocking armoring; and (9) carrying out extrusion to form a sheath. The manufacturing method has the advantages that: (1) the electric conductivity can reach 61 percent or above IACS (international annealed copper standard); (2) the filling coefficient of the conductor can be increased to 0.95; (3) S-shaped interlocking armoring is adopted, the armored cable has high flexibility and strength, the minimum bending radius is 7D, the pipe penetrating and bridging of the cable can be greatly reduced, and more than 20 percent of construction expense can be saved in common building projects; (4) the processing technique for insulation and sheathing is optimized and is easy to control, and good processing size can be obtained; (5) the design and selection of a common mould and a cable laying twisting pitch are optimized, and an optical unit can be completely ensured to be in a controllable range; and (6) aramid fiber armoring is adopted to the optical unit, and the mechanical strength of the optical unit is improved.

Super flexible low-loss stable-phase radio-frequency cable

Abstract: The utility model relates to the technical field of communication cables, and aims to provide a super flexible low-loss stable-phase radio-frequency cable meeting the higher and more comprehensive operating requirements of microwave communication systems and the like. The radio-frequency cable comprises an inner conductor (1), an insulating layer (2), an outer conductor (3) and a sheathing layer (6), and is characterized in that a fastening layer (4) and a protecting layer (5) are arranged between the outer conductor (3) and the sheathing layer (6); the fastening layer (4) is formed by tightly packing a flexible polymer material; and the protecting layer (5) adopts a silver-plated copper thread braid layer or a silver-plated alloy thread braid layer. The utility model has the advantages of higher use frequency, extremely low reduction and voltage standing wave ratio, high phase stability, excellent shielding performance, high-low temperature resistance, electron radiation resistance, high flexibility, small size and the like, and has the characteristics of extremely small bending radius, stable phase during a bending process, stable electrical performance after thousands of times of bending, and the like.