Journal articles: 'Bend loss'

1

Pile, David. "No bend loss." Nature Photonics 7, no. 12 (November 28, 2013): 938. http://dx.doi.org/10.1038/nphoton.2013.329.

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Shabani, Saman, Amir Abass Abedini, and Ali Mohammadtabar. "The Effect of the Pipe Bending Angle on the Pressure Losses Vane Elbow Pipes." Asian Review of Civil Engineering 8, no. 1 (May 5, 2019): 1–8. http://dx.doi.org/10.51983/tarce-2019.8.1.2287.

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Pressure loss is one of the significant parameters in designing pipe bends. In this paper, the pressure distribution and pressure losses induced by turbulent ﬂows in a circular cross-sectioned piping elbow with or without guide vane were simulated. The flow distribution in the piping elbow was simulated by the k- model using control volume method. The main objective of this study is to characterize the effect of changing the angle of pipe bend and Reynolds number on the flow separation of single-phase turbulent flow through numerical simulation. Results were validated by other experimental results and then loss coefficient was calculated in different angles from 45 to 135-degree pipe bend in various radius ratios with or without guide vane. Despite the fact that increasing pipe angle increased the pipe bend loss coefficient, using guide vane in the pipe elbow decreased this coefficient. In the radius ratio 1.5 with one guide vane, the loss coefficient of the pipe bends decreased by 50 percent in all degrees. Results revealed that the use of two vanes in pipe bend is more effective on the reduction of elbow pressure losses. Moreover, two guide vanes can decrease loss coefficient more than 50 percent. Also, the results indicated that loss coefficient decreased by increasing Reynolds number.

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Yao, Lei, T. A. Birks, and J. C. Knight. "Low bend loss in tightly-bent fibers through adiabatic bend transitions." Optics Express 17, no. 4 (February 12, 2009): 2962. http://dx.doi.org/10.1364/oe.17.002962.

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Waddington, D. C., and D. J. Oldham. "Noise Generation in Ventilation Systems by the Interaction of Airflow with Duct Discontinuities: Part 1 Bends." Building Acoustics 14, no. 3 (September 2007): 179–202. http://dx.doi.org/10.1260/135101007781998956.

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Discontinuities in air duct systems give rise to turbulence and some of this turbulence results in airflow generated noise. One potential source of flow generated noise in ducts is the presence of a bend. Various strategies are employed to reduce turbulence by smoothing the flow around a bend, such as the use of turning vanes, large radius of curvature and the associated use of splitters, and these will also affect the noise generated. Recent work on the prediction of airflow generated noise in ducts based upon pressure loss characteristics is applied to a range of bends including mitred bends, with and without turning vanes, and radiussed bends, with and without splitters. The effect of bends with different aspect ratios is also examined. An excellent collapse of measured data onto a single characteristic curve is reported for each configuration based upon standard values of pressure loss coefficients. It is suggested that these characteristic curves might form the basis for a practical prediction method.

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Sun, Tianyu, and Mingjun Xia. "Low loss modified Bezier bend waveguide." Optics Express 30, no. 7 (March 14, 2022): 10293. http://dx.doi.org/10.1364/oe.452580.

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Nakajima, Kazuhide, Kotaro Saito, Yusuke Yamada, Kenji Kurokawa, Tomoya Shimizu, Chisato Fukai, and Takashi Matsui. "Holey fibers for low bend loss." Nanophotonics 2, no. 5-6 (December 16, 2013): 341–53. http://dx.doi.org/10.1515/nanoph-2013-0030.

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AbstractBending-loss insensitive fiber (BIF) has proved an essential medium for constructing the current fiber to the home (FTTH) network. By contrast, the progress that has been made on holey fiber (HF) technologies provides us with novel possibilities including non-telecom applications. In this paper, we review recent progress on hole-assisted type BIF. A simple design consideration is overviewed. We then describe some of the properties of HAF including its mechanical reliability. Finally, we introduce some applications of HAF including to high power transmission. We show that HAF with a low bending loss has the potential for use in various future optical technologies as well as in the optical communication network.

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7

Faustini, L., and G. Martini. "Bend loss in single-mode fibers." Journal of Lightwave Technology 15, no. 4 (April 1997): 671–79. http://dx.doi.org/10.1109/50.566689.

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Volkov, Valentyn S., Sergey I. Bozhevolnyi, Eloise Devaux, and Thomas W. Ebbesen. "Bend loss for channel plasmon polaritons." Applied Physics Letters 89, no. 14 (October 2, 2006): 143108. http://dx.doi.org/10.1063/1.2358953.

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Martelli, Cicero, John Canning, Brant Gibson, and Shane Huntington. "Bend loss in structured optical fibres." Optics Express 15, no. 26 (2007): 17639. http://dx.doi.org/10.1364/oe.15.017639.

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Argyros, Alexander, Richard Lwin, and Maryanne C. J. Large. "Bend loss in highly multimode fibres." Optics Express 16, no. 23 (October 27, 2008): 18590. http://dx.doi.org/10.1364/oe.16.018590.

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11

Ni, Ruo Dan, Xue Song, Li Juan Qian, Si Hui Wang, and Ben Buryar. "Experimental Research on Spiral Macrobend Loss of Multimode Fibers." Applied Mechanics and Materials 423-426 (September 2013): 2321–29. http://dx.doi.org/10.4028/www.scientific.net/amm.423-426.2321.

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Spiral macrobend losses of silica multimode fibers were investigated experimentally with LED light source having a central wavelength of 890 nm. It is indicated that the bend loss vary acutely with change of real curvature radius of fiber axis when the latter is less than about 3 cm. The bend loss oscillation phenomenon caused by the whispering-gallery mode has been observed when the real curvature radii are in the range of 1.77-1.87 cm. The real curvature radius and the number of spirals are the main factors affecting bend loss and there is an approximate linear relation between bend loss and the product of the square of real curvature and the number of spirals. The modified forms of the Marcuse formula or the Petermann formula of bend loss by a multiplication factor called as winding circle density, i.e. the number of spirals on unit length of curved part of optical fiber, can fit the experimental data better.

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Alaruri, Sami D. "Study of Wavelength-Dependent Bend Loss in Step-Index Multimode Fiber-Optic Microbend Displacement Sensor." International Journal of Measurement Technologies and Instrumentation Engineering 6, no. 1 (January 2017): 13–21. http://dx.doi.org/10.4018/ijmtie.2017010102.

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In this article, the wavelength dependence of bend loss in a step-index multimode optical fiber (100 µm core diameter; fused silica) was investigated for fiber bend radii ranging between 2.0 and 4.5 mm using six excitation wavelengths, namely, 337.1, 470, 590, 632.8, 750 and 810 nm. The results obtained from fitting the bend loss measurements to Kao's model and utilizing MATLAB indicate that bend loss is wavelength dependent and transmission loss in multimode optical fibers increases with the decrease in the fiber bend radius. Furthermore, the response of a microbend fiber optic displacement sensor was characterized at 337.1, 470, 632.8, 750 and 810 nm. Measurements obtained from the microbend sensor indicate that the sensor output power is linear with the applied displacement and the sensor output is wavelength dependent.

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13

Shiina, Toru, Kazuo Shiraishi, and Shojiro Kawakami. "Waveguide-bend configuration with low-loss characteristics." Optics Letters 11, no. 11 (November 1, 1986): 736. http://dx.doi.org/10.1364/ol.11.000736.

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Birks, T. A., F. Luan, G. J. Pearce, A. Wang, J. C. Knight, and D. M. Bird. "Bend loss in all-solid bandgap fibres." Optics Express 14, no. 12 (2006): 5688. http://dx.doi.org/10.1364/oe.14.005688.

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15

Swift, C. I., and A. J. Harris. "Bend loss in neodymium-doped fiber lasers." Journal of Lightwave Technology 16, no. 3 (March 1998): 428–32. http://dx.doi.org/10.1109/50.661371.

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16

Tomljenovic-Hanic, Snjezana, Douglas A. P. Bulla, Adrian Ankiewicz, John D. Love, and Ron Bailey. "Multiple-cladding fibers with reduced bend loss." Journal of the Optical Society of America A 24, no. 4 (March 14, 2007): 1172. http://dx.doi.org/10.1364/josaa.24.001172.

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17

TAKAHASHI, Jun, Masato NOMURA, Hiroshi TSUDA, Kiyoshi KEMMOCHI, and Hiroshi FUKUDA. "Bend Loss Property for Fiber Optic Sensor." Transactions of the Japan Society of Mechanical Engineers Series A 65, no. 629 (1999): 106–12. http://dx.doi.org/10.1299/kikaia.65.106.

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18

Carriere, James T. A., Jesse A. Frantz, Brian R. West, Seppo Honkanen, and Raymond K. Kostuk. "Bend loss effects in diffused, buried waveguides." Applied Optics 44, no. 9 (March 20, 2005): 1698. http://dx.doi.org/10.1364/ao.44.001698.

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19

Barankov, R. A., K. Wei, B. Samson, and S. Ramachandran. "Resonant bend loss in leakage channel fibers." Optics Letters 37, no. 15 (July 26, 2012): 3147. http://dx.doi.org/10.1364/ol.37.003147.

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20

Singh, Jatinder Pal, Satish Kumar, and SK Mohapatra. "An experimental study on head loss characteristics of pipe bends for flow of coal–water slurry at high solid concentration." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 233, no. 5 (May 3, 2019): 1151–61. http://dx.doi.org/10.1177/0954408919844928.

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Bending of pipes is a major problem facing the engineers during the construction of a long pipeline for transporting coal–water slurry. However, the use of 90° bends in slurry transportation is restricted because it causes high head loss, and so very high pumping power is required to overcome this resistance. In this context, the present study is carried out to reduce the head loss for the flow of coal–water suspension across 90° pipe bends by varying bend geometry. Rheological experiments were performed to study flow characteristics of coal–water suspension with/without the additive. Coal–water slurry exhibits Newtonian behavior at a solid concentration of 30 wt% and pseudoplastic flow nature at concentration above 30%. Head loss experiments were carried out on a pilot plant test loop for a solid concentration of 30.27–61.56% with flow velocity ranging from 2 to 5 m/s. The r/ D ratio for the pipe bend varied within the range of 1.5–2.5. The present study reveals that the head loss across pipe bends increased as solid concentration and flow velocity was increased. The optimum r/ D ratio value for a minimum head loss was found to be 2.0. Also, significant decreases in apparent viscosity and head loss were perceived with the addition of a small amount of sulfonic acid. Power required to pump coal–water slurry was decreased by 15.93% with the use of an additive. A correlation for the head loss in terms of solid concentration, flow velocity, and r/ D ratio was also developed.

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21

Benchaita, Mohamed T. "Erosion of a Two-Dimensional Channel Bend by a Solid-Liquid Stream." Transactions of the Canadian Society for Mechanical Engineering 9, no. 2 (June 1985): 98–104. http://dx.doi.org/10.1139/tcsme-1985-0014.

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A theoretical study on “Erosion of a two-dimensional channel bend by a solid/liquid stream” is presented. The problem of erosion involves two interdependent phenomena: the fluid mechanics of the solid/liquid phase and the wear of materials by collisions and friction of solids on the metallic surface. By combining the theories of fluid mechanics of suspended particles in a liquid stream and a simple model of material weight loss by a single abrasive, one can determine the rate of erosion depth along the two-dimensional channel bend. The influence of erosion parameters such as abrasive size and stream velocity (at the bend inlet) is discussed. The generalized model could then be used to evaluate erosion rates in industrial equipment such as pipe-bends, tees and elbows, catalytic cracking of oil, and oil-well casing.

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22

Zhang, Zhekang, Yuchen Shi, Bo Shao, Taotao Zhou, Fan Luo, and Yin Xu. "Design of Compact, Broadband, and Low-Loss Silicon Waveguide Bends with Radius under 500 nm." Photonics 9, no. 9 (August 30, 2022): 616. http://dx.doi.org/10.3390/photonics9090616.

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Waveguide bend is an indispensable component in the on-chip compact photonic integrated circuits (PICs) and the minimum bend size greatly limits the increase of integration density of PICs. Here, we propose broadband and low-loss silicon waveguide bend schemes using air trenches on both sides and embedded germanium arc in the inner side of waveguide bend. Using these ways, the silicon waveguide bending radius can be greatly reduced to less than 500 nm and the obtained insertion loss (IL) can be as low as 0.12 dB compared with IL = 1.73 dB obtained by direct silicon waveguide bend under the same bending radius. Meanwhile, the working bandwidth can be extended over 500 nm covering the whole optical communication band by keeping IL < 0.5 dB. Therefore, the proposed device schemes could push the development of on-chip PICs toward higher integration density.

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23

Lin, Ding-Bing, Mei-Hui Wang, and Yong-Lun Huang. "Smooth Bend Structures Using Hybrid Compensation for Common-Mode Noise Reduction." Applied Sciences 12, no. 13 (June 26, 2022): 6479. http://dx.doi.org/10.3390/app12136479.

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The proposed smooth bend structure was implemented with a 150-degree bend to reduce the asymmetrical part of the differential bend and thus prevent mode conversion loss and common-mode noise. The smooth bend structure maintained the differential signal integrity. In addition, we proposed several hybrid compensation methods to enhance common-mode noise suppression and concluded that a smooth bend using the “L-C-L” compensation method offered the best performance. The frequency-domain analysis, from direct current (DC) to 6 GHz, was suppressed below 17.3 dB for the differential to common-mode conversion loss (Scd21) and maintained a differential insertion loss (Sdd21) above 2.18 dB. Furthermore, the 150-degree bend, using the “L-C-L” compensation method, reduced common-mode noise by 48.9% compared with a 150-degree bend structure in the time-domain analysis. The significant advantage of the proposed structure is that it can be easily fabricated using the printed circuit board (PCB) manufacturing process, reducing costs. The measurement results of the proposed design showed good consistency with the simulations. The proposed hybrid compensation structure successfully reduced the undesirable effects caused by asymmetry; as a result, mode conversion suppression was improved, and common-mode noise was reduced.

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24

Oh, J. M., A. Engeda, and M. K. Chung. "A Numerical Study of the U-Turn Bend in Return Channel Systems for Multistage Centrifugal Compressors." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 219, no. 8 (August 1, 2005): 749–56. http://dx.doi.org/10.1243/095440605x31760.

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A qualitative numerical study of the flow in the U-turn bend of return channel systems for multistage centrifugal compressors is presented. Calculations have been carried out using the flow analysis program FLUENT. The flow in the U-turn bend is highly three-dimensional and complex. The main cause for this is the circumferential variation of the velocity profile at the inlet of the bend. The circumferential variation of the velocity profile is an unavoidable result from the wake/jet flow at the exit of the impeller. In this article, first the effect of the wake/jet flow coming into the U-turn bend is studied. It is shown that the wake/jet flow develops to form the secondary flow in the U-turn bend. The secondary flow, with the high streamline curvature of the flow in the bend, makes the flow inside the bend highly complex. This complex flow is hard to predict with conventional turbulence models that have been developed on the basis of near homogeneity of flows. Comparing the present result with a study that successfully predicted the loss and flow behaviour in the bend, a discussion is presented on the turbulence and the turbulence models. Also, the loss mechanisms in the U-turn bend are discussed in detail.

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IMAO, Shigeki, Yasuaki KOZATO, and Junpei Yamada. "Bend Loss Coefficient of Drag-Reducing Surfactant Solution." Proceedings of the Fluids engineering conference 2003 (2003): 150. http://dx.doi.org/10.1299/jsmefed.2003.150.

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26

Veldhuis, G. J., L. E. W. van der Veen, and P. V. Lambeck. "Integrated optical refractometer based on waveguide bend loss." Journal of Lightwave Technology 17, no. 5 (May 1999): 857–64. http://dx.doi.org/10.1109/50.762904.

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27

Yanfeng Li, David M. Bird, and Tim A. Birks. "Bend Loss in All-Solid Bandgap Fibers Revisited." Journal of Lightwave Technology 28, no. 9 (May 2010): 1368–72. http://dx.doi.org/10.1109/jlt.2010.2045638.

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Birri, Anthony, Kelly McCary, Brandon A. Wilson, and Thomas E. Blue. "Thermally Induced Bend Loss of Silica Optical Fiber." IEEE Sensors Journal 18, no. 15 (August 1, 2018): 6181–87. http://dx.doi.org/10.1109/jsen.2018.2846522.

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29

Wang, Pengfei, Yuliya Semenova, Qiang Wu, and Gerald Farrell. "A bend loss-based singlemode fiber microdisplacement sensor." Microwave and Optical Technology Letters 52, no. 10 (July 14, 2010): 2231–35. http://dx.doi.org/10.1002/mop.25446.

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30

Eti, N., Z. Çetin, and H. S. Sözüer. "Fully three-dimensional analysis of a photonic crystal assisted silicon on insulator waveguide bend." International Journal of Modern Physics B 32, no. 31 (December 20, 2018): 1850344. http://dx.doi.org/10.1142/s0217979218503447.

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A detailed numerical study of low-loss silicon on insulator (SOI) waveguide bend is presented using the fully three-dimensional (3D) finite-difference time-domain (FDTD) method. The geometrical parameters are optimized to minimize the bending loss over a range of frequencies. Transmission results for the conventional single bend and photonic crystal assisted SOI waveguide bend are compared. Calculations are performed for the transmission values of TE-like modes where the electric field is strongly transverse to the direction of propagation. The best obtained transmission is over 95% for TE-like modes.

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31

Wang, Pengfei, Yuliya Semenova, and Gerald Farrell. "Temperature dependence of macrobending loss in all-fiber bend loss edge filter." Optics Communications 281, no. 17 (September 2008): 4312–16. http://dx.doi.org/10.1016/j.optcom.2008.04.050.

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32

Jing, Ning. "Liquid level measurement based on multi-S-bend plastic optical fiber." Sensor Review 39, no. 4 (July 15, 2019): 522–24. http://dx.doi.org/10.1108/sr-08-2018-0199.

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Purpose This paper aims to propose a liquid level sensor with a multi-S-bend plastic optical fiber. Design/methodology/approach The principle of liquid sensing used is based on the leakage of higher modes out of the fiber and repeated regeneration in the following bend sections. Therefore, a propagation loss was introduced in every bend section of the fiber with the loss depending on the refractive index of the environment. Findings Therefore, a continue shift in the liquid level can be detected by observing changes in the propagation loss of the fiber. The sensor features compactness and a flexible resolution. Originality/value Compared with the exited ones, the sensor has capability of continue liquid measurement and a greater measurement range.

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33

Debnath, Suman, Anirban Banik, Tarun Kanti Bandyopadhyay, and Apu Kumar Saha. "CFD and Optimization Study of Frictional Pressure Drop Through Bends." Recent Patents on Biotechnology 13, no. 1 (February 1, 2019): 74–86. http://dx.doi.org/10.2174/1872208312666180820153706.

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Background: The non-Newtonian pseudoplastic liquid flow through different types of the bend is more complicated compared to the simple straight pipe as the bends are associated with various curve geometry. Bends have wide application in bioengineering, biotechnology and biomedical such as study biofluids, blood rheology study, the design of medical equipment like equipment measuring the cholesterol etc. Method: The papers deal with the estimation of loss coefficient and frictional pressure drop of Newtonian and non-Newtonian pseudoplastic fluid flow through the different bend of 0.0127 m diameter pipe geometry using commercially available CFD software fluent 6.3. We revised all patents relating to the pipe flow through different types of bend. The present study also deals with the efficient application of Genetic Algorithm (GA) for optimization of frictional pressure drop. Laminar Non-Newtonian Power law model is used for Sodium Carboxy Methyl Cellulose (SCMC) solution to solve the continuity and the momentum equations numerically. Generalized input-output correlation has been developed by Gene Expression Programming (GEP) using Matlab. Results: The above-mentioned algorithm is used to predict and optimize the pressure drop. It has been found that, the process exhibit the minimum pressure drop across the bend under optimum condition (Angle = 133.160, Concentration = 0.2 Kg/m3 and velocity = 0.53 m/s). The effect of flow rate, bend angle, fluid behaviour on static pressure and pressure drop has also been investigated. Conclusion: From the study, it can be concluded that the developed GA model has a good agreement with the CFD model. The software predicted data might be used to solve various industrial problems and also to design different equipment.

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SAMI SÖZÜER, H., and H. DUYGU ŞENGÜN. "PHOTONIC CRYSTAL ASSISTED 90° WAVEGUIDE BEND." International Journal of Modern Physics B 25, no. 16 (June 30, 2011): 2167–82. http://dx.doi.org/10.1142/s0217979211100072.

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The 90° waveguide bend is an important component of optical circuit applications. We propose several models for such a bend, some of them assisted by a two-dimensional photonic crystal with a bandgap in the desired range of operating frequencies. We show that a photonic crystal assisted bend reduces bending loss by several orders of magnitude for transverse electric modes.

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35

Brik, Fatima, S. Harize, A. Fares, and K. Saouchi. "Offset effect on the S-Bend structure losses and optimization of its size for integrated optics." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 4 (August 1, 2020): 4162. http://dx.doi.org/10.11591/ijece.v10i4.pp4162-4167.

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The S-Bend structures are heavily exploited to join optical components. Reducing the power loss caused by the curve is the main objective in the design step of these components. However integrated optical circuits require S-Bend waveguide to be low loss and compact sized. In this paper, we present a contribution to link the curved structure to the straight waveguide by using the simulated bend function available in the Beam propagation tool of the Rsoft commercial software package. Simulation results confirm that this approach allows a reduction of the size of the curved structure with offset with relatively minimum of losses for photonic field.

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Gattass, Rafael R., Frederic H. Kung, Lynda E. Busse, L. Brandon Shaw, and Jasbinder S. Sanghera. "Bend loss in multimode chalcogenide fiber at infrared wavelengths." Optical Engineering 53, no. 1 (January 13, 2014): 010502. http://dx.doi.org/10.1117/1.oe.53.1.010502.

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Ng, S., S. Abdalla, P. Barrios, A. Dela^ge, S. Janz, R. McKinnon, and B. Syrett. "Bend loss attenuator by carrier injection in InGaAsP∕InP." Electronics Letters 41, no. 24 (2005): 1348. http://dx.doi.org/10.1049/el:20053357.

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38

Tangonan, G. L., H. P. Hsu, V. Jones, and J. Pikulski. "Bend loss measurements for small mode field diameter fibres." Electronics Letters 25, no. 2 (1989): 142. http://dx.doi.org/10.1049/el:19890103.

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39

Bozhevolnyi, Sergey I., Valentyn S. Volkov, Kristjan Leosson, and Alexandra Boltasseva. "Bend loss in surface plasmon polariton band-gap structures." Applied Physics Letters 79, no. 8 (August 20, 2001): 1076–78. http://dx.doi.org/10.1063/1.1389507.

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40

Schulze, Christian, Adrian Lorenz, Daniel Flamm, Alexander Hartung, Siegmund Schröter, Hartmut Bartelt, and Michael Duparré. "Mode resolved bend loss in few-mode optical fibers." Optics Express 21, no. 3 (February 1, 2013): 3170. http://dx.doi.org/10.1364/oe.21.003170.

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41

Mace, Georgina M., Mike Barrett, Neil D. Burgess, Sarah E. Cornell, Robin Freeman, Monique Grooten, and Andy Purvis. "Aiming higher to bend the curve of biodiversity loss." Nature Sustainability 1, no. 9 (September 2018): 448–51. http://dx.doi.org/10.1038/s41893-018-0130-0.

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42

Azzi, A., and L. Friedel. "Two-phase upward flow 90� bend pressure loss model." Forschung im Ingenieurwesen 69, no. 2 (March 2005): 120–30. http://dx.doi.org/10.1007/s10010-004-0147-6.

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43

Zhu, Rui, Chunsheng Luo, Xin Li, and Fei Yan. "Experimental Quantification of Local Pressure Loss at a 90° Bend in Low-Pressure Dilute-Phase Pneumatic Conveying of Coarse Particles." International Journal of Chemical Engineering 2019 (April 1, 2019): 1–9. http://dx.doi.org/10.1155/2019/6454958.

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Focusing on the insufficient estimation of the local pressure loss at a 90° horizontal-vertical bend in low-pressure pneumatic conveying of coarse particles, experiments are conducted in a 80 mm inner diameter test bend by using polyethylene particles having an equivalent spherical diameter of 4.00 mm. The influences of the local pressure loss versus the gas flow Reynolds number, the solid-gas ratio, and the bending radius ratio are investigated. Based on the additional pressure theory of Barth, an empirical formula estimating the local pressure loss is obtained using dimensional and nonlinear regression analysis. Summarizing the experiments and literature, the results expound on the local gas flow pressure loss coefficient decreases with increasing Reynolds number, and first decreases and then increases with increasing bending radius ratios from 0.5 to 7. The additional solid flow pressure loss coefficient decreases with the increasing Reynolds number and bending radius ratio in the dilute phase, and linearly increases with increasing solid-gas ratio. Compared with the estimated values with the experimental values, the calculated standard deviation is below 4.11%, indicating that the empirical formula can be used to predict local pressure loss at the bend in the low-pressure dilute-phase pneumatic conveying.

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Voisin, A., and R. D. Townsend. "Model testing of submerged vanes in strongly curved narrow channel bends." Canadian Journal of Civil Engineering 29, no. 1 (February 1, 2002): 37–49. http://dx.doi.org/10.1139/l01-078.

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This paper reports on a laboratory study that examines the effectiveness of submerged vanes for the control of erosion in strongly curved narrow channel bends. All previous researches on submerged vanes were performed in either straight or weakly curved channels that were hydraulically "wide". Submerged vanes are thin rectangular-shaped low-profile foils, typically set at small angles to the main current and arranged in either single or multiple parallel arrays in the longitudinal direction. When installed in a channel bend they induce a helicoidal vortex that interacts with and weakens the centrifugally induced secondary current. The latter effect leads to reduced local erosion near the bend's outer bank. Physical model testing was performed to determine the effects of several parameters affecting submerged vane performance, including submerged vane height H, length L, angle to main flow direction α, vane streamwise spacing δs, vane transverse spacing from outer bank δn, and bend angle φ. Submerged vanes effectively stabilize channel bend erosion by reducing the scour depth at the outer bank, generating positive transverse bed slope at the outer bank, and by reducing the net sediment loss through the channel. In general, an increase in vane height tends to shift the thalweg away from the outer bank; an increase in vane length tends to reduce the general erosion through the channel.Key words: submerged vanes, riverbank stabilization, bottom vanes, narrow channels, bank protection, bank stabilization, channel bends.

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Zhang, Jianyi, Dongrui Wang, Weiwei Wang, and Zuchao Zhu. "Numerical Investigation and Optimization of the Flow Characteristics of Bend Pipe with Different Bending Angles." Processes 10, no. 8 (August 1, 2022): 1510. http://dx.doi.org/10.3390/pr10081510.

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The bend pipe with a circular section, which is widely used in hydropower, chemical industry and other fields, is a common form in pipeline systems. However, secondary flow occurs when the fluid flows through the bend pipe, thereby affecting the stability of the pipeline system. Different bending angles have various effects. Therefore, this paper establishes 3D models of a circular bend pipe with different bending angles. The influence of bending angle on flow field distribution and downstream flow is analyzed numerically. The larger the bending angle is, the more obvious the flow distribution and even the unevenness at the elbow will be, hence resulting in poor stability. The distance required to restore flow uniformity also increases. The pressure energy loss of the bend pipe with different bending angles is investigated. Results show that with the increase in bending angle, the global pressure loss presents a trend of “increase-decrease-increase.” The closer the bending angle is to 90°, the greater the influence of centrifugal force is on the flow, and the more obvious the secondary flow phenomenon will be. Aiming at the nonuniformity phenomenon, the structure optimization of a 90° bend pipe with the greatest influence is conducted. The improvement of the flow characteristics of bend pipe with different thick-diameter ratio and length-diameter ratio is compared. The deflector with a certain thickness can enhance the uniformity, safety and useful life of the bend pipe. The sharp-end length can improve the velocity uniformity to a certain extent but has minimal influence on flow characteristics compared with the thick-diameter ratio. This paper aims to study and improve the flow performance of a multi-structure bend pipe to make it suitable for more complex conditions.

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Zhang, Lanlan, Binghan Xue, and Yueke Wang. "Mode Conversion of the Edge Modes in the Graphene Double-Ribbon Bend." Materials 12, no. 23 (December 3, 2019): 4008. http://dx.doi.org/10.3390/ma12234008.

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In this paper, a new kind of graphene double-ribbon bend structure, which can support two edge graphene surface plasmons (EGSPs) modes, is proposed. In this double-ribbon bend, one edge mode can be partly converted into another one. We attribute the mode conversion mechanism to the interference between the two edge plasmonic modes. Based on the finite element method (FEM), we calculate the transmission and loss of EGSPs propagating along this graphene double-ribbon bend in the mid-infrared range under different parameters.

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Rao, D. V. Ratna, Chakka Sarat Babu, and S. V. Prabhu. "Effect of Turn Region Treatments on the Pressure Loss Distribution in a Smooth Square Channel with Sharp 180° Bend." International Journal of Rotating Machinery 10, no. 6 (2004): 459–68. http://dx.doi.org/10.1155/s1023621x04000454.

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An experimental investigation is carried out to study the effect of several turn treatments like single guide vane (short and long) and multiple guide vanes on the pressure drop distribution in a square cross-sectioned smooth channel with a sharp 180° bend. The sharp 180° turn is obtained by dividing a rectangular passage into two square channels using a divider wall with a rounded tip at the location where the flow negotiates the turn. The study is carried out for a divider wall thickness to hydraulic diameter(W/D)of 0.2 for Reynolds numbers of 13,500 and 17,000. The pressure drop distribution normalized with the mainstream fluid dynamic pressure head is presented for the outer surfaces. The results indicate that the shape and position of the guide vanes significantly affect the pressure losses associated with coolant flows through a sharp 180° bend. Properly shaped 180° vanes located in the center of the bend decrease the overall pressure drop by as much as 40–45% compared to the no guide vane within the bend.

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Ryu, Jin Hwa, Hoesung Yang, Soyoung Park, Soocheol Kim, Kyuwon Han, Hyunseok Kim, Kwangsoo Cho, and Kang Bok Lee. "PLC-Based Integrated Refractive Index Sensor Probe with Partially Exposed Waveguide." Sensors 22, no. 15 (July 29, 2022): 5672. http://dx.doi.org/10.3390/s22155672.

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This paper proposes a simple, high-efficiency refractive index (RI) sensor, with a structure based on the planar lightwave circuit (PLC) probe type. The optical sensor has a 1 × 2 splitter structure with reference and sensing channels, each consisting of a U-shaped waveguide structure that is configured by connecting C bends. This design allows for the sensor device to have a probe structure wherein the surface interconnected with activity devices (i.e., an optical source and optical detector) is placed on one side. The reference channel is bent with a minimum optical loss, and the sensing channel has a bent structure, involving a C-bend waveguide with a maximum loss. The C-bend waveguide with a maximum loss is conformally aligned to have a trench structure with the same bending radius, designed to selectively expose the sidewall of the core layer. The local index contrast varies depending on the material in contact with the trench, resulting in a change in the optical output power of the waveguide. The sensitivity of the proposed sensor was 0 and 2070 μW/refractive index unit (RIU) for the reference and sensing channels, respectively, as the RI changed from 1.385 to 1.445 at a 1550 nm wavelength. These results suggest that the proposed structure enables efficient RI measurement through the use of a simple dip-type method.

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Ma, Guanguo, Hui Ma, and Zhenjiao Sun. "Simulation of Two-Phase Flow of Shotcrete in a Bent Pipe Based on a CFD–DEM Coupling Model." Applied Sciences 12, no. 7 (March 30, 2022): 3530. http://dx.doi.org/10.3390/app12073530.

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To solve the problems in determining the interactions among particles and between particles and pipe walls in pneumatic conveying systems in field tests, this article studied the two-phase flow motion characteristics of shotcrete in pipes based on a CFD–DEM coupling model and field measurement. The movement of the shotcrete, which is affected by the gas phase in the pipe, was simulated for different bend angles, and the velocity of the shotcrete material and pressure distribution within the pipeline were determined. The simulation results show that at the ideal wind pressure, the inelastic collisions among the particles and between the particles and pipe wall cause the accumulation of shotcrete material in the outside area of the bent pipe section, which may block the pipe; nevertheless, the blockage is prevented by the turbulent and secondary flows, which disperse the particles to different degrees. In addition, the wear amounts caused by particles in pipes with different bend angles were quantified. With increasing bend angle, the wear points gradually diffuse radially toward the outside wall of the bent pipe. Additionally, the wear loss decreases and then increases with increasing bend angle. The particle velocity exhibits the minimal loss at a bend angle of 90°. It was concluded that the energy loss of the aggregate particles in the elbow of the pipe is approximately 30 times that in a horizontal, straight pipe. The results of this study can provide guidance in the construction field and for numerical simulations of the pneumatic conveying process of shotcrete.

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Osama, Ahmed, Khairy Elsayed, and Mohamed El-Telbany. "Pressure Loss Reduction in U-Bend Using the Adjoint Method." Journal of Engineering Science and Military Technologies 17, no. 17th International Conference (April 1, 2017): 1–15. http://dx.doi.org/10.21608/ejmtc.2017.21130.

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Journal articles on the topic 'Bend loss'

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