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Journal articles on the topic 'Air-silica structured fibre'
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1
Canning, John, Nathaniel Groothoff, Kevin Cook, Cicero Martelli, Alexandre Pohl, John Holdsworth, Somnath Bandyopadhyay, and Michael Stevenson. "Gratings in Structured Optical Fibres." Laser Chemistry 2008 (December 1, 2008): 1–19. http://dx.doi.org/10.1155/2008/239417.
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Grating writing in structured optical fibres and their properties and applications are reviewed. To date, most gratings have been written in a straightforward manner into structured fibres containing a photosensitive germanosilicate step-index core. However, gratings have also been written directly into single material, structured silica fibres and into air-clad cores using two and higher-photon processes with both UV and near IR pulsed (nanosecond-femtosecond) light. Given the intrinsic-added functionality possible within a structured optical fibre, structured fibre gratings offer further capabilities for sensors, diagnostics, lasers, and devices.
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Canning, J., E. Buckley, K. Lyttikainen, and T. Ryan. "Wavelength dependent leakage in a Fresnel-based air–silica structured optical fibre." Optics Communications 205, no. 1-3 (April 2002): 95–99. http://dx.doi.org/10.1016/s0030-4018(02)01305-6.
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Ahmadov, Nizami, and Irade Shirinzade. "Development of effective fiber-reinforced concrete compositions used in transportation structures." Eastern-European Journal of Enterprise Technologies 2, no. 1 (110) (April 20, 2021): 6–11. http://dx.doi.org/10.15587/1729-4061.2021.227139.
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The possibility of producing fiber-reinforced concrete with high deformation properties by regulating the microstructure and using it in the design of transport structures was considered. It was found that to create high-performance transport structures, it is necessary to modify fiber mixtures with complex additives, i. e. increase the strength of fiber-reinforced concrete at the micro-level. To obtain a denser structure of the concrete matrix, complex additives were used – ultrafine additive (silica fume) and Master Air 200 B air-entraining additive. It was experimentally proved that using such additives reduces the water-cement ratio and further strengthens the concrete matrix structure. The design of the unloading structure on the railway line constructed from the Karadag station (Republic of Azerbaijan) to the SOCAR oil and gas processing and petrochemical complex using fiber-reinforced concrete modified with complex additives was made. The results of designing the fiber-reinforced concrete unloading structure were analyzed and the results of designing the fiber-reinforced concrete unloading structure and the regular concrete unloading structure were compared. As a result of the comparison, it was found that using fiber-reinforced concrete decreases the cross-section diameter of the effective reinforcement of the slab – the cross-section diameter of the effective reinforcement of the pavement slab decreases from Æ2×32 mm to Æ32 mm in the upper and Æ25 mm in the lower row, respectively. Crack resistance is also increased compared to regular concrete. Thus, in order to create structures with high transport and operational parameters, it is necessary to modify fiber-reinforced concrete mixtures with complex additives
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Canning, J., M. A. van Eijkelenborg, T. Ryan, M. Kristensen, and K. Lyytikainen. "Complex mode coupling within air–silica structured optical fibres and applications." Optics Communications 185, no. 4-6 (November 2000): 321–24. http://dx.doi.org/10.1016/s0030-4018(00)01022-1.
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Vo, Thi Minh Ngoc, Dinh Quang Ho, Tung Thanh Le, Thi Gai Le, Canh Trung Le, Van Lanh Chu, Thi Thuy Nguyen, Van Thuy Hoang, Thanh Danh Nguyen, and Hieu Van Le. "Numerical simulation of all-normal dispersion visible to near-infrared supercontinuum generation in photonic crystal fibers with core filled chloroform." Hue University Journal of Science: Natural Science 130, no. 1B (June 29, 2021): 43–51. http://dx.doi.org/10.26459/hueunijns.v130i1b.6243.
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This study proposes a photonic crystal fiber made of fused silica glass, with the core infiltrated with chloroform as a new source of supercontinuum (SC) spectrum. We numerically study the guiding properties of the fiber structure in terms of characteristic dispersion and mode area of the fundamental mode. Based on the results, we optimized the structural geometries of the CHCl3-core photonic crystal fiber to support the broadband SC generations. The fiber structure with a lattice constant of 1 μm, a filling factor of 0.8, and the diameter of the first-ring air holes equaling 0.5 μm operates in all-normal dispersion. The SC with a broadened spectral bandwidth of 0.64 to 1.80 μm is formed by using a pump pulse with a wavelength of 850 nm, 120 fs duration, and power of 0.833 kW. That fiber would be a good candidate for all-fiber SC sources as cost-effective alternative to glass core fibers.
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Gowre, Sanjaykumar, Sudipta Mahapatra, and P. K. Sahu. "A Modified Structure for All-Glass Photonic Bandgap Fibers: Dispersion Characteristics and Confinement Loss Analysis." ISRN Optics 2013 (September 22, 2013): 1–5. http://dx.doi.org/10.1155/2013/416537.
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This paper investigates a modified structure for all-glass photonic bandgap fiber (AGPBF) having up-doped silica rods in the cladding region instead of air holes using plane wave expansion (PWE) and finite difference time domain (FDTD) methods. The proposed AGPBF structure exhibits tunable dispersion properties and improved confinement loss. It is observed that the confinement loss can be reduced simply by using a higher doping concentration in silica rods in the cladding. Also, it is possible to achieve flattened dispersion of the order of 1 ps/nm/km over a wide wavelength range.
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Zhang, Pengfei, Chao Wang, Liuwei Wan, Qianqian Zhang, Zidan Gong, Zixiong Qin, and Chi Chiu Chan. "Opto-Microfluidic Fabry-Perot Sensor with Extended Air Cavity and Enhanced Pressure Sensitivity." Micromachines 13, no. 1 (December 24, 2021): 19. http://dx.doi.org/10.3390/mi13010019.
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An opto-microfluidic static pressure sensor based on a fiber Fabry-Perot Interferometer (FPI) with extended air cavity for enhancing the measuring sensitivity is proposed. The FPI is constructed in a microfluidic channel by the combination of the fixed fiber-end reflection and floating liquid surface reflection faces. A change of the aquatic pressure will cause a drift of the liquid surface and the pressure can be measured by detecting the shift of the FPI spectrum. Sensitivity of the sensor structure can be enhanced significantly by extending the air region of the FPI. The structure is manufactured by using a common single-mode optical fiber, and a silica capillary with the inner wall coated with a hydrophobic film. A sample with 3500 μm air cavity length has demonstrated the pressure sensitivity of about 32.4 μm/kPa, and the temperature cross-sensitivity of about 0.33 kPa/K.
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Hieu. "INFLUENCE OF STRUCTURE PARAMETERS ON THE SUPERCONTINUUM GENERATION OF PHOTONIC CRYSTAL FIBER." Journal of Military Science and Technology, no. 67 (June 12, 2020): 161–68. http://dx.doi.org/10.54939/1859-1043.j.mst.67.2020.161-168.
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In this paper, we report a numerical calculation of the influence of structural parameters on the supercontinuum generation of photonic crystal fibers. A photonic crystal fiber based on the fused silica glass, eight rings of air holes ordered in a hexagonal lattice, is proposed. Guiding properties in terms of dispersion and confinement loss of the fundamental mode are also studied numerically. As a result, the broadband width of the supercontinuum spectrum will increase when the lattice pitch decreases or the diameter of air hole in the cladding increases. However, the coherence of SC will become worse.
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Rana, Sohel, Austin Fleming, Nirmala Kandadai, and Harish Subbaraman. "Active Compensation of Radiation Effects on Optical Fibers for Sensing Applications." Sensors 21, no. 24 (December 8, 2021): 8193. http://dx.doi.org/10.3390/s21248193.
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Neutron and gamma irradiation is known to compact silica, resulting in macroscopic changes in refractive index (RI) and geometric structure. The change in RI and linear compaction in a radiation environment is caused by three well-known mechanisms: (i) radiation-induced attenuation (RIA), (ii) radiation-induced compaction (RIC), and (iii) radiation-induced emission (RIE). These macroscopic changes induce errors in monitoring physical parameters such as temperature, pressure, and strain in optical fiber-based sensors, which limit their application in radiation environments. We present a cascaded Fabry–Perot interferometer (FPI) technique to measure macroscopic properties, such as radiation-induced change in RI and length compaction in real time to actively account for sensor drift. The proposed cascaded FPI consists of two cavities: the first cavity is an air cavity, and the second is a silica cavity. The length compaction from the air cavity is used to deduce the RI change within the silica cavity. We utilize fast Fourier transform (FFT) algorithm and two bandpass filters for the signal extraction of each cavity. Inclusion of such a simple cascaded FPI structure will enable accurate determination of physical parameters under the test.
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Sanjuán, Miguel Ángel, and Carmen Andrade. "Reactive Powder Concrete: Durability and Applications." Applied Sciences 11, no. 12 (June 18, 2021): 5629. http://dx.doi.org/10.3390/app11125629.
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Reactive powder concrete (RPC) is an ultra-high-performance concrete (UHPC) developed years ago by Bouygues, with the aim to build strong, durable, and sustainable structures. Some differences can be underlined between the RPC and high-performance concrete (HPC); that is to say, RPC exhibits higher compressive and flexural strength, higher toughness, lower porosity, and lower permeability compared to HPC. Microstructural observations confirm that silica fume enhances the fiber–matrix interfacial characteristics, particularly in fiber pullout energy. This paper reviews the reported literature on RPC, and it offers a comparison between RPC and HPC. Therefore, some RPC potential applications may be inferred. For instance, some examples of footbridges and structural repair applications are given. Experimental measurements on air permeability, porosity, water absorption, carbonation rate, corrosion rate, and resistivity are evidence of the better performance of RPC over HPC. When these ultra-high-performance concretes are reinforced with discontinuous, short fibers, they exhibit better tensile strain-hardening performance.
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Journal, Baghdad Science. "Dispersion in a Gas Filled Hollow Core Photonic Crystal Fiber." Baghdad Science Journal 11, no. 3 (September 7, 2014): 1250–56. http://dx.doi.org/10.21123/bsj.11.3.1250-1256.
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Hollow core photonic bandgap fibers provide a new geometry for the realization and enhancement of many nonlinear optical effects. Such fibers offer novel guidance and dispersion properties that provide an advantage over conventional fibers for various applications. Dispersion, which expresses the variation with wavelength of the guided-mode group velocity, is one of the most important properties of optical fibers. Photonic crystal fibers (PCFs) offer much larger flexibility than conventional fibers with respect to tailoring of the dispersion curve. This is partly due to the large refractive-index contrast available in the silica/air microstructures, and partly due to the possibility of making complex refractive-index structure over the fiber cross section. In this paper the fundamental physical mechanism has been discussed determining the dispersion properties of PCFs, and the dispersion in a gas filled hollow core photonic crystal fiber has been calculated. We calculate the dispersion of air filled hollow core photonic crystal fiber, also calculate the dispersion of N2 gas filled hollow core photonic crystal fiber and finally we calculate the dispersion of He gas filled hollow core photonic crystal fiber.
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POPESCU, V. A. "A VERY HIGH AMPLITUDE SENSITIVITY OF A NEW MULTI-CORE HOLEY FIBER-BASED PLASMONIC SENSOR." Modern Physics Letters B 27, no. 06 (February 6, 2013): 1350038. http://dx.doi.org/10.1142/s0217984913500383.
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The propagation characteristics in a new multi-core holey fiber-based plasmonic sensor are investigated using a finite element method. The fiber is made by a silica core with a small air hole in the center of the structure, surrounded by six air holes placed at the vertices of a hexagon, two layers of air holes arranged in a hexagonal way that are inserted in the SiO 2 core which is surrounded by a gold layer and a very thick distilled water layer. The structure is designed to have high amplitude sensitivity near the phase matching point corresponding to the maximum of the power fraction for a core guided supermode in the water and gold layers. The maximum of the imaginary part of the group refractive index is located to the same wavelength as the maximum of the amplitude sensitivity. The advantages of our design are a small value of FWHM parameter, a high value of the signal-to-noise ratio, a high value of the amplitude sensitivity (4040.9 RIU-1), a sensor resolution better than 2.5 × 10-6 RIU and a strong transmission loss of a core guided supermode at the resonant coupling due to efficient interaction with a plasmon mode.
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Moayed, Seyed Hossein, Mojtaba Sadeghi, and Zahra Adelpour. "Design of new infrared nano sensor based on surface plasmon resonance photonic crystal fibers." Laser Physics 32, no. 10 (August 19, 2022): 105101. http://dx.doi.org/10.1088/1555-6611/ac87f5.
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Abstract In this paper, five different surface plasmon resonance photonic crystal fiber (SPR-PCF) structures are proposed and evaluated by numerical modeling. The structures are based on photonic crystal fibers with defects rods of air, Au, and TiN in the background of silica. In the fourth and fifth designs, two grooves coated with gold layers are considered to improve the functionality of the structures and help the analyte to become closer to the fiber core. The effects of geometrical parameters like radius, thickness, and width on the loss spectrum are also investigated, and the results are presented. Finally, a double D-shaped SPR-PCF sensor with ITO belts and U-shaped grooves covered with gold is proposed. The proposed sensor can detect a low RI change from 1.4 to 1.6 with a maximal sensitivity factor around 6000 (nm/RIU). The proposed SPR-PCF sensor can be an appropriate candidate in nano-optical integrated circuits (for different applications) due to its compact size and high sensitivity factor.
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Mei, Chao, Yuan Wu, Jinhui Yuan, Shi Qiu, and Xian Zhou. "Design of Compact and Broadband Polarization Beam Splitters Based on Surface Plasmonic Resonance in Photonic Crystal Fibers." Micromachines 13, no. 10 (October 3, 2022): 1663. http://dx.doi.org/10.3390/mi13101663.
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In this work, a polarization beam splitter (PBS) based on surface plasmonic resonance is proposed and realized in a designed photonic crystal fiber (PCF). The PCF consists of two kinds of air holes with different diameters. Two solid silica cores near the center of the PCF are established by removing the cladding air holes. A gold film is plated at the external surface of the central air hole of the PCF to excite the surface plasmonic resonance. In order to minimize the length and improve the operation bandwidth of the PBS, the influences of the transversal structural parameters of the PCF are investigated in the context of both X and Y polarization beams. It was found that a 123.6-μm-long PBS with an operation bandwidth of 314 nm could be realized after the global optimization of five structural parameters. The proposed PBS may have potential applications in micro-/nano-optical systems for sensing and communications.
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Drljača, Branko, Svetislav Savović, Milan S. Kovačević, Ana Simović, Ljubica Kuzmanović, Alexandar Djordjevich, and Rui Min. "Theoretical Investigation of Bandwidth in Multimode Step-Index Silica Photonic Crystal Fibers." Photonics 9, no. 4 (March 23, 2022): 214. http://dx.doi.org/10.3390/photonics9040214.
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Solving the time-dependent power flow equation (PFE) provides a useful method to study the transmission bandwidth of step-index silica photonic crystal fibers (SI SPCFs). The transmission bandwidth of these kinds of fibers is determined for different air-hole structures (different numerical apertures (NAs)) and different distribution widths of the Gaussian launch beam. The results indicate that the lower the NA of SI SPCFs, the higher the bandwidth (for example, for a lower NA of SI SPCFs, a bandwidth that is eight times larger is obtained at a fiber length of 3500 m). The narrower launch beam at short fiber lengths results in a wider bandwidth. The longer the fiber (>300 m), the much less the effect of the launch beam width on the bandwidth. The bandwidth becomes independent of the width of the launch beam distribution at the fiber length at which a steady-state distribution (SSD) is reached. These results are useful for some potential applications, such as high capacity transmission optical fiber systems.
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Xia, Ping, Yuegang Tan, Caixia Yang, Zude Zhou, and Kang Yun. "A Composite Fabry-Perot Interferometric Sensor with the Dual-Cavity Structure for Simultaneous Measurement of High Temperature and Strain." Sensors 21, no. 15 (July 22, 2021): 4989. http://dx.doi.org/10.3390/s21154989.
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In this paper, an optical fiber composite Fabry-Perot interferometric (CFPI) sensor capable of simultaneous measurement of high temperature and strain is presented. The CFPI sensor consists of a silica-cavity intrinsic Fabry-Perot interferometer (IFPI) cascading an air-cavity extrinsic Fabry-Perot interferometer (EFPI). The IFPI is constructed at the end of the transmission single-mode fiber (SMF) by splicing a short piece of photonic crystal fiber (PCF) to SMF and then the IFPI is inserted into a quartz capillary with a reflective surface to form a single-ended sliding EFPI. In such a configuration, the IFPI is only sensitive to temperature and the EFPI is sensitive to strain, which allows the achieving of temperature-compensated strain measurement. The experimental results show that the proposed sensor has good high-temperature resistance up to 1000 °C. Strain measurement under high temperatures is demonstrated for high-temperature suitability and stable strain response. Featuring intrinsic safety, compact structure and small size, the proposed CFPI sensor may find important applications in the high-temperature harsh environment.
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Wang, Guan Jun, Zhi Bin Wang, You Hua Chen, Yuan Yuan Chen, Yong Quan An, Shi Wei Li, Min Juan Zhang, and Jin Hua Li. "Polarization-Insensitive Holey Fiber with Ultra-Small Mode Areas Using a Cross-Slot-Structure Core." Key Engineering Materials 609-610 (April 2014): 775–78. http://dx.doi.org/10.4028/www.scientific.net/kem.609-610.775.
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A high nonlinear, dispersion flattened hybrid nanofiber with a silicon/silica cross-slot-structure nanocore is firstly proposed and analyzed, which is insensitive to polarization for implementing quasi-TE and quasi-TM fundamental modes transmission due to cross slot effect. Simulation results show that fundamental mode of ultra-small mode effective areas and high nonlinearity at TE and TM polarizations, which are confined in the narrow cross slot by four silicon ribs, can be achieved via this cross sot structure core. Moreover, the cladding of four large-air-holes promotes tailoring the group velocity dispersion (GVD) and enhancing nonlinearity furthermore. Our results indicate that ultra-small Aeff of 0.098μm2 and flat anomalous GVD with less than 13.5 ps.km-1.nm-1 dispersion ripple at C-band are realizable.
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Sultanov, R. M., R. R. Zinatullin, and S. A. Imamutdinov. "Modifying of air-mechanical foams using organosilicone compounds." IOP Conference Series: Earth and Environmental Science 981, no. 3 (February 1, 2022): 032062. http://dx.doi.org/10.1088/1755-1315/981/3/032062.
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Abstract The results of studying the fire foams’ modification using organosilicone compounds are presented in this article. The results of comparative fighting flammable liquid fires (diesel fuel) using non-modified foam and modified foam are also studied. It is shown that fire fighting using foam, modified with organosilicone compounds is much more effective, because of the increasing isolating capacity of such foam due to high-solidifying formation of foam which prevent the liquid vapors from getting in the area of chemical reactions and also isolate the flammable liquid from the oxygen of the air. Such a result is possible due to the presence of the mixture of solutions of foaming agent and the organosilicone modifying compound in the structure of the foam – tethraethyl silicate (TES). The results of the study confirm the perspective of using the organic compounds of the silica for improvement the fire extinguishing properties of the foam and its further applying for the fighting with flammable liquid fire.
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Fu, Yueqiao, Graham T. T. Gibson, Christine McGregor, and Richard D. Oleschuk. "Fabrication of a polymer nozzle array in a microstructured fibre as a nanoelectrospray emitter for mass spectrometry." Canadian Journal of Chemistry 93, no. 4 (April 2015): 477–84. http://dx.doi.org/10.1139/cjc-2014-0578.
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We report a modified silica microstructured fibre (MSF) as a multiple electrospray (MES) emitter, with dimensional compatibility with conventional liquid chromatography and mass spectrometry equipment, to generate stable electrospray from a wide range of applied potentials and flow rates. An array of polymer nozzles is fabricated in the MSF by a procedure involving templated polymerization of microtubes and wet chemical etching of the silica at the tip. The structure of the emitting end of the MSF was optimized with respect to the etching process, and the morphology of the polymer nozzles was optimized with respect to polymerization conditions. The mechanisms of the etching and of the templated polymerization of the microtubes were explored. Optimization experiments were performed using commercially available MSF having 126 tubular air channels arranged in a hexagonal pattern with channel diameter of ∼5.6 μm. However, the flexibility and versatility in the pattern, shape, and size of channels in MSFs allowed a custom-designed MSF to be fabricated and tested for MES. In the new design, six channels were evenly spaced in a radial pattern, and when polymer nozzles were made, six stable electrosprays were observed over a wide range of electrospray conditions. Using these MES emitters, the spray current is enhanced by a factor related to the number of nozzles.
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Cui, Mingjie, Zhuo Wang, and Changyuan Yu. "Refractive Index Sensing Using Helical Broken-Circular-Symmetry Core Microstructured Optical Fiber." Sensors 22, no. 23 (December 6, 2022): 9523. http://dx.doi.org/10.3390/s22239523.
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Helical twist provides an additional degree of freedom for controlling light in optical waveguides, expanding their applications in sensing. In this paper, we propose a helical broken-circular-symmetry core microstructured optical fiber for refractive index sensing. The proposed fiber consists of pure silica and its noncircular helical core is formed by a broken air ring. By using finite element modeling combined with transformation optics, the modal characteristics of the fiber are investigated in detail. The results show that for the core located at the fiber center, the confinement loss of fundamental core modes increases with twist rate, whereas for a sufficiently large core offset the modes can be well confined owing to the twist-induced light guidance mechanism, showing decreases with rising twist rate in the loss spectra. Moreover, we have found that for large twist rates and core offsets, resonant peaks occur at different twist rates due to the couplings between the fundamental core modes and the highly leaky modes created by the helical structure. The refractive index sensing performance is also studied and the obtained results show that the proposed fiber has great potential in fiber sensing.
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Zatar, Wael, and Tu Nguyen. "Mixture Design Study of Fiber-Reinforced Self-Compacting Concrete for Prefabricated Street Light Post Structures." Advances in Civil Engineering 2020 (June 15, 2020): 1–7. http://dx.doi.org/10.1155/2020/8852320.
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In recent years, there has been an increasing demand to produce strong precast street light posts that are aesthetically pleasing. This study presents experimental results of a considerable number of mixture designs for fabricating precast street light posts where fiber-reinforced self-compacting concrete (FRSCC) was employed. The performance of many FRSCC mixtures was evaluated in terms of their structural properties and aesthetic characteristics. A trial-and-error procedure was performed for a series of FRSCC mixtures where silica fume, fly ash, and fibers were used. Slump flow and air content tests were conducted to determine the fresh FRSCC properties, and specimens were cast to evaluate their aesthetic. Three-day and seven-day compression tests were performed to examine the FRSCC hardened properties. The amount of cement in all batches was kept constant, whereas the distributions of fine and coarse aggregates, water, and other admixtures were adjusted. The largest slump flow of 73.7 cm (29 in) was recorded, and the maximum three-day compressive strength was 43 MPa (6209 psi). Further refinement of the mixtures, which displayed the best strength and aesthetic attributes, was performed. Test results of the selected FRSCC mixtures indicated an excellent slump flow, air content, and compression values while achieving advantageous aesthetic qualities. Seven-day compressive strength of 39 MPa (5686 psi) with the air content of 4.8 percent and the slump flow of 66 cm (26 in) was recorded. The study results and the developed FRSCC mixes can be used for mass production of precast concrete street light posts in precast plants.
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Yu, Chengbing, Kaiqin Shi, Jinyan Ning, Zhe Zheng, Hualong Yu, Zhenxuan Yang, and Jun Liu. "Preparation and Application of Fluorine-Free Finishing Agent with Excellent Water Repellency for Cotton Fabric." Polymers 13, no. 17 (September 2, 2021): 2980. http://dx.doi.org/10.3390/polym13172980.
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Water repellent is an important functional finish for cotton fabric. However, cotton fabrics often have poor washing resistance and other performances after actual finishing. In this study, based on the structural characteristics of cotton fiber and durability of water repellent, a cross-linked amino long-chain alkyl polysiloxane (CAHPS) was first prepared, and then reacted with modified silica. Finally, a chemically bonded organic–inorganic nanohybrid cross-linked polysiloxane (rSiO2–CAHPS) was fabricated. Furthermore, the rSiO2–CAHPS was emulsified to obtain a durable fluorine-free water repellent. The water repellent finishing for cotton fabric was carried out by the pad–dry–cure process. After finishing, the cotton fabric had good resistance to conventional liquids and excellent washing resistance, and still maintained good water repellency after 30 rounds of soaping. Moreover, properties including air permeability, mechanical property and whiteness are hardly affected after finishing. SEM and XPS characterization show that a layer of dense silicon film is formed on the surface of cotton fabric by rSiO2–CAHPS water repellent. The existence of nanosilica can improve the surface roughness of cotton fibers. The synergistic effect of fiber matrix, nanoparticles and CAHPS endows the fabric with a micro/nano-multi-scale micro-rough structure, which improves the water repellency of cotton fabric after water repellent finishing.
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Al-Zahrani, Fahad Ahmed, and Md Anowar Kabir. "Ring-Core Photonic Crystal Fiber of Terahertz Orbital Angular Momentum Modes with Excellence Guiding Properties in Optical Fiber Communication." Photonics 8, no. 4 (April 14, 2021): 122. http://dx.doi.org/10.3390/photonics8040122.
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The orbital angular momentum (OAM) of light is used for increasing the optical communication capacity in the mode division multiplexing (MDM) technique. A novel and simple structure of ring-core photonic crystal fiber (RC-PCF) is proposed in this paper. The ring core is doped by the Schott sulfur difluoride material and the cladding region is composed of fused silica with one layer of well-patterned air-holes. The guiding of Terahertz (THz) OAM beams with 58 OAM modes over 0.70 THz (0.20 THz–0.90 THz) frequency is supported by this proposed RC-PCF. The OAM modes are well-separated for their large refractive index difference above 10−4. The dispersion profile of each mode is varied in the range of 0.23–7.77 ps/THz/cm. The ultra-low confinement loss around 10−9 dB/cm and better mode purity up to 0.932 is achieved by this RC-PCF. For these good properties, the proposed fiber is a promising candidate to be applied in the THz OAM transmission systems with high feasibility and high capacity.
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Baselt, Tobias, Bryan Nelsen, Andrés Fabián Lasagni, and Peter Hartmann. "Supercontinuum Generation in the Cladding Modes of an Endlessly Single-Mode Fiber." Applied Sciences 9, no. 20 (October 18, 2019): 4428. http://dx.doi.org/10.3390/app9204428.
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In photonic crystal fibers, light guidance can be achieved by a central defect of a periodic structure of air holes in a silica glass matrix and the dispersion can be adjusted over a wide spectral range to enhance nonlinear effects. By coupling short pulse laser radiation into the core with tight confinement and utilizing the nonlinear properties of glass, this radiation can be converted to a broad spectral distribution. The tight confinement puts limits on the maximum pulse fluence propagating in the core due to the damage threshold of the glass. Therefore, when higher power spectral densities are desired, it is favorable to spread the generation of light over a much larger area to prevent fiber damage. We present here a method for generating a supercontinuum using the cladding modes of an endlessly single-mode fiber. These modes generate a supercontinuum utilizing a multimodal quasi-continuum of states, for which dispersion is governed by the guiding properties of the material between the air-filled holes in the cladding. The system also provides experimental access to unique phenomena in nonlinear optics. Simulations of the propagation properties of the core mode and cladding modes were compared with measurements of the group-velocity dispersion in a modified white-light Mach–Zehnder interferometer. The coupling of similar laser parameters into the cladding of the photonic crystal fiber enables a significant increase in conversion efficiency in the visible spectral range compared with the core-pumped case.
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Chen, Zhuoran, Shaodi Zhang, Mengyi Ding, Mingzhi Wang, and Xing Xu. "Construction of a Phytic Acid–Silica System in Wood for Highly Efficient Flame Retardancy and Smoke Suppression." Materials 14, no. 15 (July 27, 2021): 4164. http://dx.doi.org/10.3390/ma14154164.
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The intrinsic flammability of wood restricts its application in various fields. In this study, we constructed a phytic acid (PA)–silica hybrid system in wood by a vacuum-pressure impregnation process to improve its flame retardancy and smoke suppression. The system was derived from a simple mixture of PA and silica sol. Fourier transform infrared spectroscopy (FTIR) indicated an incorporation of the PA molecules into the silica network. Thermogravimetric (TG) analysis showed that the system greatly enhanced the char yield of wood from 1.5% to 32.1% (in air) and the thermal degradation rates were decreased. The limiting oxygen index (LOI) of the PA/silica-nanosol-treated wood was 47.3%. Cone calorimetry test (CCT) was conducted, which revealed large reductions in the heat release rate and smoke production rate. The appearance of the second heat release peak was delayed, indicating the enhanced thermal stability of the char residue. The mechanism underlying flame retardancy was analyzed by field-emission scanning electron microscope coupled with energy-dispersive spectroscopy (SEM-EDS), FTIR, and TG-FTIR. The improved flame retardancy and smoke-suppression property of the wood are mainly attributed to the formation of an intact and coherent char residue with crosslinked structures, which can protect against the transfer of heat and mass (flammable gases, smoke) during burning. Moreover, the hybrid system did not significantly alter the mechanical properties of wood, such as compressive strength and hardness. This approach can be extended to fabricate other phosphorus and silicon materials for enhancing the fire safety of wood.
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Amin, Ruhul, Lway Faisal Abdulrazak, Shaymaa R. Tahhan, Noor Mohammadd, Kawsar Ahmed, Francis M. Bui, and Sobhy M. Ibrahim. "Tellurite glass based optical fiber for the investigation of supercontinuum generation and nonlinear properties." Physica Scripta 97, no. 3 (February 21, 2022): 030007. http://dx.doi.org/10.1088/1402-4896/ac5359.
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Abstract This manuscript introduces a unique tellurite core-based photonic crystal fiber (PCF) with silica clad and circular air holes, which manifests highly birefringent and non-linear characteristics. Several optical features, such as birefringence (Br), nonlinear coefficients (NLC), dispersion (D), confinement loss (CL), material loss, etc are thoroughly analyzed and explored by applying the finite element method (FEM). The simulated outcomes validate that by optimizing the formation of the cladding region, a large NLC of 7650 W − 1 Km − 1 , as well as an ultra-high Br of 11.2810 − 2 and zero-dispersion can be accomplished in the offered PCF design at 1.56 μm wavelength. Moreover, the evaluated findings indicate that the stated fiber structure is capable of generating a wide supercontinuum spectrum spanning from 943 to 8038 nm when augmented with a 4.5 kW input power and a pulse duration of 20 f s . Calculations and analyses have been carried out on the effects of higher-order dispersion co-efficients, pulse length and input power on spectrum broadening. The advanced PCF design will be a suitable candidate for practical applications in numerous fields, including bio photonics, biomedical imaging, biosensing, spectroscopy and ultra-broadband signal amplification, etc.
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Budykina, T. A., and E. B. Anosova. "Study of the Behavior of the Fire-Retardant Seals Under Thermal Exposure." Occupational Safety in Industry, no. 8 (August 2021): 52–57. http://dx.doi.org/10.24000/0409-2961-2021-8-52-57.
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The results are presented concerning the experimental studies of the behavior of fire-retardant seals produced by the Ogneza group of companies under thermal exposure up to 1000 °C, obtained by the method of synchronous thermal analysis (thermogravimetry together with the differential scanning calorimetry). Incombustible properties of the M-СORE (NG) seal were confirmed, which showed a decrease in the mass of the material when heated to 1000 °C by 11%, which is due to the mineral composition of the sample (a silica-based material). High thermal stability was shown by the fire-fighting seal M-CORE, the decrease in the mass of the sample of which, after reaching a temperature of 555 °C, stops at 37 %, which indicates the formation of an ash residue. Thermal sealing tape LTU, as a result of the temperature heating starting from a mark of 192 °C, uniformly was losing mass up to a total value of 82 %. The experiment established the sealant swelling. According to the experimental data obtained, the samples M-CORE (NG) confirmed the fire-retardant properties declared by the manufacturer. For the selection of heat-resistant materials that can withstand significant temperature loads during the operation of units and mechanisms, for electrical and thermal insulation, for fire protection of air ducts, equipment, structures, the advantages, and reliability of these seals are obvious. The results of the study (the temperature of the beginning of an intensive decrease in mass, the temperature of the onset of thermal effects accompanying a decrease in mass, the behavior of materials under thermal exposure) can be considered when designing heat and electrical insulation, fire protection of production processes, as well as when determining the level of fire risk of the production facilities.
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Pereira, Tiago Augusto Rodrigues, Tuane Santos de Oliveira, Luzimar Campos da Silva, and Aristéa Alves Azevedo. "Comparative leaf anatomy of four species of Bromelioideae (Bromeliaceae) occurring in the Atlantic Forest, Brazil." Botany 89, no. 4 (April 2011): 243–53. http://dx.doi.org/10.1139/b11-011.
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Bromeliaceae, comprising 3172 species, is one of the most important families of the Brazilian Atlantic Forest owing to its high degree of endemism and occurrence in different habitats. The subfamily Bromelioideae is the most representative of Bromeliaceae and the best represented in the state of Minas Gerais, Brazil, with 120 species. The objective of this study is to compare the leaf anatomy of four species found in two areas of the Atlantic Forest: Serra do Brigadeiro State Park, Minas Gerais, Brazil ( Quesnelia strobilispica Wawra and Wittrockia gigantea (Baker) Leme) and a forest fragment located within Bom Sucesso Farm, Viçosa, Minas Gerais, Brazil ( Billbergia euphemiae E. Morren and Bromelia antiacantha Bertol.), relating environmental characteristics to the habit. Leaf samples were studied using light and scanning electron microscopy and histochemical tests with Sudan, phloroglucinol, and ruthenium red stains. Leaves of B. euphemiae and W. gigantea showed several adaptations to the epiphytic habit, including scales on both surfaces, thickened epidermal cell walls, presence of silica bodies, hypodermis with sclerified cells, water-storing tissue (hydrenchyma), and air channels formed by stellate cells in the chlorenchyma. The epiphytic species B. euphemiae and the terrestrial species Q. strobilispica have similar overall structure, including a well-developed parenchyma and extravascular fiber groups. Leaves of the terrestrial species Bromelia antiacantha and the epiphytic species W. gigantea also show structural similarities, such as lack of extravascular fibers and less developed parenchyma. Similar characteristics in species from different habitats may either reflect microclimatic conditions under which these species occur or genetically fixed characteristics.
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A., Kobelev, Naganovsky Yu., Kruglov E., and Aseeva R. "PHYSICOCHEMICAL CHANGES OF HYBRID POLYURETHANE INORGANIC THERMAL INSULATION WHEN HEATING IN AIR AND IN AN INERT ATMOSPHERE." Fire and emergencies: prevention, elimination 4 (2021): 22–29. http://dx.doi.org/10.25257/fe.2021.4.22-29.
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Purpose. The article presents the results of a study of physicochemical processes occurring when a hybrid polyurethane inorganic thermal insulation is heated under dynamic conditions up to 800 °C in different atmospheric environments. The object of the study was an industrial sample of thermal insulation “FoamTech 1 550” made in South Korea. Methods. In the course of the work thermo-gravimetric analysis and IR-Fourier spectrometry were used. Samples for spectrometric analysis were prepared in the process of thermogravimetric tests by suspending the experiment. Findings. As the result of the combined studying hybrid thermal insulation material by thermogravimetry and IR-Fourier spectrometry methods, the following was established: – polyisocyanate used for obtaining the material is aliphatic in nature; – the hybrid thermal insulation sample contains about 40 % inorganics, presumably aerogel silica; – there are three main stages of hybrid thermal insulation decomposition, both in air and in an inert atmosphere; – analysis of the changes in IR spectra when heating the hybrid sample showed that at the first stage of decomposition, regardless of the atmospheric environment, the condensation reaction of silanol groups of silica aerogel takes place with the water release; – at the second stage, thickening of the inorganic framework continues, chemical polyurethane bonds with the inorganic are destroyed, and polyurethane component carbonization begins. Research application field. The results give the idea of material decomposition process in a fire. Differences in behavior in oxidizing and inert environments are shown. This is important for comparing a new group of materials with the already known types of polymer thermal insulation in terms of their fire hazard and possible application in building construction. Conclusions. The paper studies the chemical structure and physicochemical changes when heating the new group of materials, namely hybrid organic-inorganic thermal insulation materials. The article is a continuation of a team of authors’ systematic study of a thermal behavior of modern types of polymer thermal insulation.
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Sun, Yu, and Yuguo Sun. "Strong and Thermostable Boron-Containing Phenolic Resin-Derived Carbon Modified Three-Dimensional Needled Carbon Fiber Reinforced Silicon Oxycarbide Composites with Tunable High-Performance Microwave Absorption Properties." Applied Sciences 10, no. 6 (March 11, 2020): 1924. http://dx.doi.org/10.3390/app10061924.
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This paper focuses on the preparation of boron-containing phenolic resin (BPR)-derived carbon modified three-dimensional (3D) needled carbon fiber reinforced silicon oxycarbide (SiOC) composites through a simple precursor infiltration and pyrolysis process (PIP), and the influence of PIP cycle numbers on the microstructure, mechanical, high-temperature oxidation resistance. The electromagnetic wave (EMW) absorption properties of the composites were investigated for the first time. The pyrolysis temperature played an important role in the structural evolution of the SiOC precursor, as temperatures above 1400 °C would cause phase separation of the SiOC and the formation of silicon carbide (SiC), silica (SiO2), and carbon. The density and compressive strength of the composites increased as the PIP cycle number increased: the value for the sample with 3 PIP cycles was 0.77 g/cm3, 7.18 ± 1.92 MPa in XY direction and 9.01 ± 1.25 MPa in Z direction, respectively. This composite presented excellent high-temperature oxidation resistance and thermal stability properties with weight retention above 95% up to 1000 °C both under air and Ar atmosphere. The minimal reflection loss (RLmin) value and the widest effective absorption bandwidth (EAB) value of as-prepared composites was −24.31 dB and 4.9 GHz under the optimization condition for the sample with 3 PIP cycles. The above results indicate that our BPR-derived carbon modified 3D needled carbon fiber reinforced SiOC composites could be considered as a promising material for practical applications.
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Giustetto, Roberto, Loredana Macaluso, Gloria Berlier, Yadolah Ganjkhanlou, and Luca Barale. "Characterisation and possible hazard of an atypical asbestiform sepiolite associated with aliphatic hydrocarbons from Sassello, Ligurian Apennines, Italy." Mineralogical Magazine 83, no. 02 (October 8, 2018): 209–22. http://dx.doi.org/10.1180/mgm.2018.159.
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AbstractAn unusual occurrence of asbestiform sepiolite, filling veins in the antigorite serpentinites of the Voltri Unit exposed in a borrow pit (now reclaimed) in the Deiva forest, near Sassello, NW Italy, was investigated with an in-depth analytical approach aimed at studying its crystal-chemistry and structure and evaluating its possible hazards for human health. Optical microscopy and scanning electron microscopy (energy-dispersive spectroscopy mode) proved that these sepiolite fibres, apparently up to several cm long, are made up of bundles of thinner fibrils (or laths: average length > 100 µm; thickness ≈ 80 nm), with a composition consistent to that reported in the literature. The dehydration process was monitored through thermo-gravimetric analyses and Fourier-transform infrared spectroscopy, performed at increasing T; the latter, in particular, showed the presence of moderate amounts of aliphatic hydrocarbons – not yet identified thoroughly – associated with the sample. The crystal structure refinement with the Rietveld method showed no relevant difference from the literature models, although a peculiar distribution of zeolitic H2O molecules was observed. The geological context suggests that the Sassello sepiolite precipitated from hydrothermal fluids, which were saturated in Mg and silica by the interaction of the host serpentinites. The same setting favoured formation of abiotic hydrocarbons, by means of the Fischer–Tropsch reaction. The extremely long and flexible fibrils (length/width aspect ratio >> 3) of this sepiolite specimen could represent a serious hazard for human health if air dispersed and inhaled; also, its atypical association with hydrocarbons (only reported once previously) might even favour further fragmentation in thinner units.
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Hasegawa, Takemi, Eisuke Sasaoka, Masashi Onishi, Masayuki Nishimura, Yasuhide Tsuji, and Masanori Koshiba. "Hole-Assisted Lightguide Fiber - A Practical Derivative of Photonic Crystal Fiber." MRS Proceedings 722 (2002). http://dx.doi.org/10.1557/proc-722-l4.2.
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AbstractUsage of air holes in optical fibers has become a hot subject in fiber optics because of the possibilities for novel transmission properties. Although photonic crystal fibers based on photonic bandgap guidance are the most drastic innovation in this subject, optical fibers containing air holes but not having photonic crystal structures are also being intensively studied. Such air-silica microstructured fibers are more practical than the photonic bandgap fibers because the lack of photonic crystal structure makes the fabrication far easier. Even without the photonic bandgap, the microstructured fibers can exhibit valuable properties in terms of group velocity dispersion and nonlinearity, because the index contrast between air and silica is 10 or more times as large as that of the conventional optical fibers based on doped silica glasses. However, one of the major challenges for practical applications of the air-silica microstructured fibers has been their high transmission losses, which have been several tens to hundreds times higher than those of the conventional fibers. As a solution to this problem, we have proposed a more practical structure called hole-assisted lightguide fiber (HALF). In addition to the air holes for realizing novel optical properties, this structure has a material index profile for waveguiding, and hence is closer to the conventional fibers than the other microstructured fibers are. As a result, novel optical properties can be realized without severe degradation in transmission loss. In experiments, an anomalous group velocity dispersion as large as +35 ps/nm/km at 1550 nm wavelength, which would be unattainable in the conventional fibers, has been realized with a loss of 0.41 dB/km, which is comparable to those of the conventional fibers. Analyses of the losses of the fabricated HALFs suggest that the loss should be lowered by mitigating the effect of the drawing tension and minimizing the power fraction in the holes. It is also shown that the full-vector finite element method realizes accurate modeling of the properties such as dispersion and macrobend loss.
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Mondal, Kajal. "Structural dependence of transmission characteristics for photonic crystal fiber with circularly distributed air-holes." Journal of Optical Communications, June 8, 2020. http://dx.doi.org/10.1515/joc-2020-0032.
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AbstractIn this study, design and transmission characteristics of a special type of photonic crystal fiber (PCF) geometry namely, circular-lattice photonic crystal fiber (C-PCF) structure are presented. The cladding of the structure consists by a cylindrically symmetrical distribution of air-holes in the silica background and the core is created by omitting one air-hole at the center. The structure provides high degree of flexibility in the fiber design and hence tailorable modal properties. Structural dependence of transmission characteristics of the geometry is numerically investigated by using finite difference mode convergence algorithm. The wavelength responses of fiber parameters, such as effective refractive index, chromatic dispersion, mode-effective area, and nonlinear coefficient of the structure are systematically investigated. Besides, effective V-parameter and single-mode operation of the fiber are also evaluated and discussed. The simulation results show the possibility of large negative dispersion and dispersion flattened nature of the geometry.
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Amiri, IS, Ahmed Nabih Zaki Rashed, Kaushik Sarker, Bikash Kumar Paul, and Kawsar Ahmed. "Chirped Large Mode Area Photonic Crystal Modal Fibers and its Resonance Modes Based on Finite Element Technique." Journal of Optical Communications, July 23, 2019. http://dx.doi.org/10.1515/joc-2019-0146.
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AbstractThe study has outlined the finite element technique used for the fiber modal analysis of photonic crystal fiber (PCF) structure with a hexagonal/circular air holes arrangement on the cladding of pure fiber-optic silica. The used fibers that are namely highly nonlinear fiber (HNLF), single model silica fiber (SMSF) are combined with PCFs with different dopants concentration. Leakage loss, number of guided resonant modes, fiber birefringence, effective refractive index and cross-section areas and nonlinear coefficient parameters are measured inaccurate estimation. The optimum resonant guided modes are also estimated for different lattice infrastructure in circular PCFs.
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Sutrsino, Himawan Hadi. "The Active Fire Protection Prototype for Household-Scale Kitchen Based on Silica Gel from Rice Husk Ash." International Journal of Integrated Engineering 14, no. 3 (June 20, 2022). http://dx.doi.org/10.30880/ijie.2022.14.03.005.
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This study aims to create a fire protection design in the kitchen with technology that is easily applied along with inexpensive extinguishing media using silica gel from rice husk ash. By using an experimental method, the active design of fire protection in the kitchen area uses compartmentalization equipped with a gas stove, kitchen equipment, as well as specially designed fire equipment components. The composition of the air in the compartment is calculated based on the volume of the compartment so that it can represent the coverage of oxygen and fuel in accordance with the conditions of free air, while the silica used as an extinguishing media from the extraction of rice husk ash using KOH 0,5M solvent. From the results of this study, the design of fire protection for silica gel-based kitchens made from rice husk ash is effectively used and easy to install in the kitchen area.
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Sakr, Hesham, Yong Chen, Gregory T. Jasion, Thomas D. Bradley, John R. Hayes, Hans Christian H. Mulvad, Ian A. Davidson, Eric Numkam Fokoua, and Francesco Poletti. "Hollow core optical fibres with comparable attenuation to silica fibres between 600 and 1100 nm." Nature Communications 11, no. 1 (November 27, 2020). http://dx.doi.org/10.1038/s41467-020-19910-7.
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AbstractFor over 50 years, pure or doped silica glass optical fibres have been an unrivalled platform for the transmission of laser light and optical data at wavelengths from the visible to the near infra-red. Rayleigh scattering, arising from frozen-in density fluctuations in the glass, fundamentally limits the minimum attenuation of these fibres and hence restricts their application, especially at shorter wavelengths. Guiding light in hollow (air) core fibres offers a potential way to overcome this insurmountable attenuation limit set by the glass’s scattering, but requires reduction of all the other loss-inducing mechanisms. Here we report hollow core fibres, of nested antiresonant design, with losses comparable or lower than achievable in solid glass fibres around technologically relevant wavelengths of 660, 850, and 1060 nm. Their lower than Rayleigh scattering loss in an air-guiding structure offers the potential for advances in quantum communications, data transmission, and laser power delivery.
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Roldán-Varona, Pablo, Rosa Ana Pérez-Herrera, Luis Rodríguez-Cobo, Luis Reyes-González, Manuel López-Amo, and José Miguel López-Higuera. "Liquid level sensor based on dynamic Fabry–Perot interferometers in processed capillary fiber." Scientific Reports 11, no. 1 (February 4, 2021). http://dx.doi.org/10.1038/s41598-021-82193-5.
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AbstractIn this work, a novel optical fiber sensor capable of measuring both the liquid level and its refractive index is designed, manufactured and demonstrated through simulations and experimentally. For this, a silica capillary hollow-core fiber is used. The fiber, with a sensing length of 1.55 mm, has been processed with a femtosecond laser, so that it incorporates four holes in its structure. In this way, the liquid enters the air core, and it is possible to perform the sensing through the Fabry–Perot cavities that the liquid generates. The detection mode is in reflection. With a resolution of 4 μm (liquid level), it is in the state of the art of this type of sensor. The system is designed so that in the future it will be capable of measuring the level of immiscible liquids, that is, liquids that form stratified layers. It can be useful to determine the presence of impurities in tanks.
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Altay, Pelin. "The effect of silica aerogel on thermal and sound absorption insulation properties of epoxy plate and glass fiber fabric epoxy composite." Journal of Elastomers & Plastics, December 21, 2022, 009524432211470. http://dx.doi.org/10.1177/00952443221147041.
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Silica aerogel (SA) is used as an additive in composite production to improve their thermal–mechanical properties, owing to their excellent properties such as high porosity, low density, and low thermal conductivity. All these unique properties make it attractive to be used for improving sound absorption and thermal insulation properties of composite materials. However, there are very limited studies on both improvement of sound and thermal insulation properties of glass fiber fabric epoxy composite by adding silica aerogel. With this aim, this study investigates the effect of incorporation of SA as a filler in glass fiber fabric epoxy composite (GFEC) and epoxy plate used in a wide variety of structural and engineering applications such as buildings, constructions, communication, aerospace and transportation, on sound absorption and thermal insulation. Results indicate that SA addition decreased the thermal conductivity coefficient from 0.55 to 0.48 W/mK for GFEC, and from 0.25 to 0.23 W/mK for epoxy plate, providing improvement on thermal insulation. Silica aerogel increased the maximum sound absorption coefficient (SAC) from 0.27 to 0.65, shifting the frequency from 4000 to 400 Hz for GFEC. The maximum SAC value increased from 0.28 to 0.41 at 800 Hz and decreased from 0.54 to 0.47 at 2000 Hz in SA incorporated-epoxy plate with 1 cm air gap thickness. The results reveal that SA has an improvement effect on low-frequency sound absorption for both GFEC and epoxy plate.
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Lægsgaard, J., S. E. Barkou Libori, K. Hougaard, J. Riishede, T. T. Larsen, T. Sørensen, T. P. Hansen, et al. "Dispersion Properties of Photonic Crystal Fibers - Issues and Opportunities." MRS Proceedings 797 (2003). http://dx.doi.org/10.1557/proc-797-w7.1.
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ABSTRACTThe dispersion, which expresses the variation with wavelength of the guided-mode group velocity, is one of the most important properties of optical fibers. Photonic crystal fibers (PCFs) offer much larger flexibility than conventional fibers with respect to tailoring of the dispersion curve. This is partly due to the large refractive-index contrast available in silica/air microstructures, and partly due to the possibility of making complex refractive-index structures over the fiber cross section. We discuss the fundamental physical mechanisms determining the dispersion properties of PCFs guiding by either total internal reflection or photonic bandgap effects, and use these insights to outline design principles and generic behaviours of various types of PCFs. A number of examples from recent modeling and experimental work serve to illustrate our general conclusions.
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Dong, Qian, Hyungdae Bae, Zhijian Zhang, Yongyao Chen, Zhongshan Wen, Douglas A. Olson, Miao Yu, and Haijun Liu. "Miniature Fiber Optic Acoustic Pressure Sensors With Air-Backed Graphene Diaphragms." Journal of Vibration and Acoustics 141, no. 4 (March 25, 2019). http://dx.doi.org/10.1115/1.4042929.
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Graphene has been known to possess exceptional mechanical properties, including its extremely high Young’s modulus and atomic layer thickness. Although there are several reported fiber optic pressure sensors using graphene film, a key question that is not well understood is how the suspended graphene film interacts with the backing air cavity and affects the sensor performance. Based on our previous analytical model, we will show that the sensor performance suffers due to the significantly reduced mechanical sensitivity by the backing cavity. To remedy this limitation, we will, through experimental and numerical methods, investigate two approaches to enhance the sensitivity of fiber optic acoustic pressure sensors using graphene film. First, a graphene–silver composite diaphragm is used to enhance the optical sensitivity by increasing the reflectivity. Compared with a sensor with pure graphene diaphragm, graphene–silver composite can enhance the sensitivity by threefold, while the mechanical sensitivity is largely unchanged. Second, a fiber optic sensor is developed with enlarged backing air volume through the gap between an optical fiber and a silica capillary tube. Experimental results show that the mechanical sensitivity is increased by 10× from the case where the gap side space is filled. For both approaches, signal-to-noise ratio (SNR) is improved due to the enhanced sensitivity, and comsol Thermoviscous acoustics simulation compares well with the experimental results. This study is expected to not only enhance the understanding of fluid–structural interaction in sensor design but also benefit various applications requiring high-performance miniature acoustic sensors.
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Harrat, Assia Ahlem, Mohammed Debbal, and Mohammed Chamse-Eddine Ouadah. "1 × 2 power splitter based on photonics crystals fibers." Journal of Optical Communications, January 30, 2023. http://dx.doi.org/10.1515/joc-2022-0273.
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Abstract In this regard, we directed a theoretical study with numerical simulations. This study allowed us to illustrate how a photonic crystal fiber (PCF) structure could divide an optical signal. One of the most fundamental components used to construct photonic integrated circuits (PIC) is the splitter, which is using light coupling between the cores as a control until the output ports by using pure silica to replace some air-hole zones along the PCF axis and split the single signal on two ports with almost equal intensity in each port. Optical interconnects are one of the most basic components of integrated optics, and splitters for photonic power are a key element of a connected family. With the least amount of loss, a competent photonic splitter can guide light input of a certain wavelength to several ports at various intensities.
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Skutnik, Bolesh J., and M. R. Trumbull. "Strength and Fatigue of Modified Sol-Gel Clad Optical Fibers." MRS Proceedings 531 (1998). http://dx.doi.org/10.1557/proc-531-169.
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AbstractDynamic and static fatigue results are presented for the first time for a new type of optical fiber, whose modified sol-gel cladding is a fenestrated (micro porous) form of silica. Unjacketed fibers have mean Weibull strengths in bending of 6.5 to 7.6 GPa with Weibull slopes in the 40 to 60 range. The strength decrease with decreasing strain rate is similar for both jacketed and unjacketed fibers. Even the unjacketed fibers tested in ambient water or in boiling water retain a majority of their mean strength, 7.6 GPa (ambient air) versus 6.5 GPa (ambient water) versus 5.5 GPa (boiling water). Exposure to boiling water for 1 hour has no measurable affect on the strength of these fibers. Exposure to boiling water for 8 hours, however, does significantly broaden the low strength end for the unjacketed fiber. The dynamic fatigue and static fatigue parameters in ambient water are substantially the same, ND = 22±2 and Ns 21±4, for the jacketed and unjacketed fibers. Possible mechanisms are discussed to explain the strength and fatigue behavior of these fibers in light of their unique structure.
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Singh, Maninder, Babita Saini, and H. D. Chalak. "Influence of Stone Processing Waste on Mechanical, Durability, and Ecological Performance of Hybrid Fiber-Reinforced Engineered Cementitious Composite." Transportation Research Record: Journal of the Transportation Research Board, November 9, 2022, 036119812211300. http://dx.doi.org/10.1177/03611981221130027.
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The current study is focused on the characteristics of sustainable engineered cementitious composites (ECCs) with the inclusion of various types of fibers (PVA, PET, and MSE) in hybridization, silica sand (SS), river sand (RS), and stone processing waste (SPW). SPW is termed as hazardous material because of the presence of finer particles and inorganic substances which contribute to leaching problems, and cause adverse effects on aquatic life and human health. The objective of this study was to introduce new kind of cost-effective, sustainable, and greener ECC to encourage its use in diversified applications. The characteristics of different ECC mixtures were assessed by observing the slump flow, compressive, tensile, flexural, ultrasonic pulse velocity, air permeability, electrical resistivity (ER), sorptivity, ecological behavior, and cost analysis. Experimental results revealed that the combination of micro-fibers enhanced the overall performance of ECC with reduction in the matrix cost. The addition of SPW in place of aggregates enhanced the flowability, strength, and durability characteristics, and contributed to reducing the carbon dioxide emissions. This study confirms that the combined use of PVA, PET, and MSE fibers with SPW inclusion is a promising alternative over the fully PVA blended ECC with SS.
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Punde, Shirish S., and Bruce J. Tatarchuk. "Microfibrous Entrapped Catalysts for Low Temperature CO Oxidation." MRS Proceedings 1217 (2009). http://dx.doi.org/10.1557/proc-1217-y03-29.
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AbstractLow temperature CO oxidation is characterized by slow reaction kinetics and CO self-poisoning of the catalyst, which compete with each other. A platinum catalyst with ceria as a promoter supported on a high surface area silica support has been developed. The catalyst has a significant activity for CO oxidation even in the presence of moisture. The catalyst showed a significant increase in activity with decreasing particle size (η<0.95, even at 100μm), indicating a clear transport limitation.In case of larger catalyst particles the diffusional resistances affect the reaction kinetics, leading to greater rates of CO self-poisoning causing deactivation of the catalysts. However, conventional packed bed of smaller particles poses problems such as high pressure drop, packing issues, bed channeling, flow maldistributions, and dead zones in the reactor bed, which result in poor inter-phase heat and mass transfer rates. Most of these problems are related to poor packaging of smaller particles, strongly suggesting the need for immobilization of small particles. A new class of micro-structured materials consisting of sorbents/catalysts entrapped in metal, ceramic, or polymer microfibers (MFES/MFEC) has been developed at Auburn University. These materials immobilize the small particles by sinter-locking them in fiber mesh. The immobilization of particles results in better heterogeneous contacting efficiency. Additional studies have shown that the high voidages and structural uniformity of the MFES lowered the flow maldistributions, eliminated the peaking flows between particles, and helped achieve better radial dispersion. Thus MFEC/MFES improved inter-phase transport rates.The Pt-CeO2/SiO2 catalyst entrapped in metal microfibers demonstrated a significant improvement in CO conversion compared to a conventional packed bed configuration while maintaining a lower pressure drop. Further catalyst entrapment in metal microfibers minimized cold spots in the reactor bed due to better intra-phase heat transfer rate. Higher effective thermal conductivity of MFEC improved the activity of the catalyst, which was particularly visible at high CO concentration wherein the CO inhibition kinetics takes over. For example, MFEC with 1/3 rd of catalyst loading as that of packed bed of same particle size, outperformed packed bed configuration.The catalysts were prepared by incipient wet impregnation. Surface characterization of catalysts was carried out using CO, H2, O2 chemisorption, O2 – H2 titration, N2 physisorption, powder XRD, and was correlated with catalytic activity.This microfibrous entrapped catalyst demonstrated a great potential for low temperature CO oxidation. These MFEC can be used in air purification, emergency escape products, and as a cathode air filter for PEM fuel cells.