<div style="text-align:justify;"> We propose a novel scheme, based on digital-heterodyne optical phase-locked loop with whole-fiber circuit, to dynamically measure the free-spectral-range of a fiber re...<div style="text-align:justify;"> We propose a novel scheme, based on digital-heterodyne optical phase-locked loop with whole-fiber circuit, to dynamically measure the free-spectral-range of a fiber resonator. The optical phase-locked loop is established with a differential frequency-modulation module consists of a pair of acousto-optic modulators. The resonance-tracking loop is derived with the Pound-Drever-Hall technique for locking the heterodyne frequency of the OPLL on the frequency difference between adjacent resonance modes. A stable locking accuracy of about 7 × 10<sup>?9</sup> and a dynamic locking accuracy of about 5 × 10<sup>?8</sup> are achieved with the FSR of 8.155 MHz, indicating a bias stability of the resonator fiber optic gyro of about 0.1?/h with 10 Hz bandwidth. In addition, the thermal drift coefficient of the FSR is measured as 0.1 Hz/?C. This shows remarkable potential for realizing advanced optical measurement systems, such as the resonant fiber optic gyro, and so on. </div>展开更多
In order to improve the mechanical properties of SiO_2 aerogel-glass fiber composites, effects of different solvents(cyclohexane, n-hexane, ethanol, acetone) and different dispersing modes(planetary ball milling, ultr...In order to improve the mechanical properties of SiO_2 aerogel-glass fiber composites, effects of different solvents(cyclohexane, n-hexane, ethanol, acetone) and different dispersing modes(planetary ball milling, ultrasonic dispersion and mechanical stirring) and dispersing duration(10-40 min) on the dispersion of chopped alkali-free glass fiber bundles were studied to determine the best dispersion process. On this basis, the materials were batched according to the mass fraction of SiO_2 aerogel powder to chopped alkali free glass fiber bundles of 90:10, and a certain amount of zinc oxide light-screening agent and phenolic resin binder were added. SiO_2 aerogel glass fiber composite specimens were prepared by direct adding chopped alkali free glass fiber bundles and pre-dispersed chopped alkali free glass fiber bundles, respectively. The cold crushing strength and the thermal conductivity at different surface temperatures(300, 400, 500 and 600 ℃, respectively)of the specimens were measured. The results show that:(1) the optimum dispersion process of chopped alkali-free glass fiber bundles is using ethanol as solvent and mechanical stirring for 30 min;(2) pre-dispersion of chopped alkali-free glass fiber bundles has little effect on the thermal conductivity of SiO_2 aerogel-glass fiber composites but can improve the cold crushing strength.展开更多
Based on the mechanical system of free-end fibers and the analysis of pulling free-end fibers out of the spun yarn during spinning,a low-fiber hollow spindle is designed and the air distribution of fluent field is sim...Based on the mechanical system of free-end fibers and the analysis of pulling free-end fibers out of the spun yarn during spinning,a low-fiber hollow spindle is designed and the air distribution of fluent field is simulated numerically. The negative pressure effect is much bigger at the top of low-fiber hollow spindle than that in Murata No.861,which is more conducive for single fiber to get into the channel of hollow spindle. The tangential velocity in 0-3 mm at the top of hollow spindle increases and the fluctuation of radial velocity is much stronger,which enhance the wrapping effect. In the addition,the distribution of axial velocity remains the same.展开更多
Positron lifetime measurements have been made in natural polymer-Nistari silk fibers as a function of isochronalannealing temperature in the range of 27℃ to 280℃. The variations in the positron results indicate the ...Positron lifetime measurements have been made in natural polymer-Nistari silk fibers as a function of isochronalannealing temperature in the range of 27℃ to 280℃. The variations in the positron results indicate the structural changesoccurring in the Nistari silk fibers and determine the glass transition temperature as 170℃. Activation energies weremeasured separately for the crystalline and amorphous regions indicating the versatility of the technique. These values areclose to the N--H bond dissociation energy, suggesting N--H bond dissociation as the most probable process occurringduring thermal treatment As an extension of the positron results, the molecular weight of the Nistari silk fibers wasdetermined to be 10.7×10~5 based on free volume, which lies within the range suggested for the silk fibers. There seems to bean indication that cross-linking changes the spiral structure of cotton fibers to network type. However, this needs to be validated by other techniques.展开更多
Fiber-optic DNA biosensors are a kind of ana-lytic setups, which convert the Waston-Crick base pairs matching duplex or Hoogsteen’s tri-plex (T/A-T, C/G-C) formation into a readable analytical signals when functional...Fiber-optic DNA biosensors are a kind of ana-lytic setups, which convert the Waston-Crick base pairs matching duplex or Hoogsteen’s tri-plex (T/A-T, C/G-C) formation into a readable analytical signals when functionalized single- strands DNA (ssDNA) or double-strands DNA (dsDNA) of interest are immobilized on the sur-face of fiber-optic hybrids with target DNA or interacts with ligands. This review will provide the information about the fiber-optic DNA bio-sensors classified into two categories depend-ing on the end fiber and side fiber with or with-out the labels—label-free fiber-optic DNA bio-sensors and labeled fiber-optic DNA biosensor in recent years. Both are dissertated, and em-phasis is on the label-free fiber-optic DNA bio-sensors. Fiber-optic DNA biosensors had got great progresses because fiber-optic has more advantages over the other transducers and are easily processed by nanotechnology. So fiber- optic DNA biosensors have increasingly at-tracted more attention to research and develop the new fiber-optic DNA biosensors that inte-grated with the “nano-bio-info” technology for in vivo test, single molecular detection and on-line medical diagnosis. Finally, future pros-pects to the fiber-optic DNA biosensors are predicted.展开更多
The surface properties of glass fiber were quantificationally analyzed by inverse gas chromatography （IGC）. Five n-alkanes （C6, C7, C8, C9, and C10） were chosen as apolar probes to characterize the dispersive comp...The surface properties of glass fiber were quantificationally analyzed by inverse gas chromatography （IGC）. Five n-alkanes （C6, C7, C8, C9, and C10） were chosen as apolar probes to characterize the dispersive component of surface free energy. Trichloromethane （CHCl3）, acetone, and tetrahydrofuran （THF） were chosen as polar probes to detect the Lewis acid-base parameters. It is found that the dispersive components of free energy are 32.3, 30.5, 27.5, and 26.9 mJ/m^2 at 70, 80, 90, and 100 ℃. respectively. The Lewis acidic number Ka of the glass fiber is 0.512 4, and the basic number Kb is 2.862. The results mean the glass fiber is a Lewis basic material.展开更多
A unique SiC whisker wheel was invented,in which the whiskers were aligned normally to the grinding wheel surface.In this paper,grindabilities of the SiC whisker wheel are investigated and compared with those of other...A unique SiC whisker wheel was invented,in which the whiskers were aligned normally to the grinding wheel surface.In this paper,grindabilities of the SiC whisker wheel are investigated and compared with those of other wheels of SiC grains,Al2O3 grains,as well as Al2O3 long and short fibres which were also aligned normally to the grinding wheel surface,respectively.The main research contents concern grinding characteristics of a directionally aligned SiC whisker wheel such as material-removal volume,wheel-wear rates,integrity of the ground surfaces,grinding ratios and grinding efficiency.Furthermore,grinding wheels of whiskers and fibres have a common disadvantage:they tend to load easily.The authors have proposed a simple method of loading-free grinding to overcome this propensity and investigate some related grinding characteristics under loading-free grinding conditions.展开更多
文摘<div style="text-align:justify;"> We propose a novel scheme, based on digital-heterodyne optical phase-locked loop with whole-fiber circuit, to dynamically measure the free-spectral-range of a fiber resonator. The optical phase-locked loop is established with a differential frequency-modulation module consists of a pair of acousto-optic modulators. The resonance-tracking loop is derived with the Pound-Drever-Hall technique for locking the heterodyne frequency of the OPLL on the frequency difference between adjacent resonance modes. A stable locking accuracy of about 7 × 10<sup>?9</sup> and a dynamic locking accuracy of about 5 × 10<sup>?8</sup> are achieved with the FSR of 8.155 MHz, indicating a bias stability of the resonator fiber optic gyro of about 0.1?/h with 10 Hz bandwidth. In addition, the thermal drift coefficient of the FSR is measured as 0.1 Hz/?C. This shows remarkable potential for realizing advanced optical measurement systems, such as the resonant fiber optic gyro, and so on. </div>
基金financial supports from the National Key R&D Program of China (2016YFB0601301 and 2018YFB0605904)The National Natural Science Foundation of China (51672256)Henan Science and Technology Research Program (162102210343)
文摘In order to improve the mechanical properties of SiO_2 aerogel-glass fiber composites, effects of different solvents(cyclohexane, n-hexane, ethanol, acetone) and different dispersing modes(planetary ball milling, ultrasonic dispersion and mechanical stirring) and dispersing duration(10-40 min) on the dispersion of chopped alkali-free glass fiber bundles were studied to determine the best dispersion process. On this basis, the materials were batched according to the mass fraction of SiO_2 aerogel powder to chopped alkali free glass fiber bundles of 90:10, and a certain amount of zinc oxide light-screening agent and phenolic resin binder were added. SiO_2 aerogel glass fiber composite specimens were prepared by direct adding chopped alkali free glass fiber bundles and pre-dispersed chopped alkali free glass fiber bundles, respectively. The cold crushing strength and the thermal conductivity at different surface temperatures(300, 400, 500 and 600 ℃, respectively)of the specimens were measured. The results show that:(1) the optimum dispersion process of chopped alkali-free glass fiber bundles is using ethanol as solvent and mechanical stirring for 30 min;(2) pre-dispersion of chopped alkali-free glass fiber bundles has little effect on the thermal conductivity of SiO_2 aerogel-glass fiber composites but can improve the cold crushing strength.
基金Program for Changjiang Scholars and Innovative Research Team in University,China(No.IRT1220)Shanghai Natural Science Foundation,China(No.13ZR1400900)Keygrant Project of Chinese Ministry of Education(No.113027A)
文摘Based on the mechanical system of free-end fibers and the analysis of pulling free-end fibers out of the spun yarn during spinning,a low-fiber hollow spindle is designed and the air distribution of fluent field is simulated numerically. The negative pressure effect is much bigger at the top of low-fiber hollow spindle than that in Murata No.861,which is more conducive for single fiber to get into the channel of hollow spindle. The tangential velocity in 0-3 mm at the top of hollow spindle increases and the fluctuation of radial velocity is much stronger,which enhance the wrapping effect. In the addition,the distribution of axial velocity remains the same.
文摘Positron lifetime measurements have been made in natural polymer-Nistari silk fibers as a function of isochronalannealing temperature in the range of 27℃ to 280℃. The variations in the positron results indicate the structural changesoccurring in the Nistari silk fibers and determine the glass transition temperature as 170℃. Activation energies weremeasured separately for the crystalline and amorphous regions indicating the versatility of the technique. These values areclose to the N--H bond dissociation energy, suggesting N--H bond dissociation as the most probable process occurringduring thermal treatment As an extension of the positron results, the molecular weight of the Nistari silk fibers wasdetermined to be 10.7×10~5 based on free volume, which lies within the range suggested for the silk fibers. There seems to bean indication that cross-linking changes the spiral structure of cotton fibers to network type. However, this needs to be validated by other techniques.
文摘Fiber-optic DNA biosensors are a kind of ana-lytic setups, which convert the Waston-Crick base pairs matching duplex or Hoogsteen’s tri-plex (T/A-T, C/G-C) formation into a readable analytical signals when functionalized single- strands DNA (ssDNA) or double-strands DNA (dsDNA) of interest are immobilized on the sur-face of fiber-optic hybrids with target DNA or interacts with ligands. This review will provide the information about the fiber-optic DNA bio-sensors classified into two categories depend-ing on the end fiber and side fiber with or with-out the labels—label-free fiber-optic DNA bio-sensors and labeled fiber-optic DNA biosensor in recent years. Both are dissertated, and em-phasis is on the label-free fiber-optic DNA bio-sensors. Fiber-optic DNA biosensors had got great progresses because fiber-optic has more advantages over the other transducers and are easily processed by nanotechnology. So fiber- optic DNA biosensors have increasingly at-tracted more attention to research and develop the new fiber-optic DNA biosensors that inte-grated with the “nano-bio-info” technology for in vivo test, single molecular detection and on-line medical diagnosis. Finally, future pros-pects to the fiber-optic DNA biosensors are predicted.
基金the Key Technologies R&D Programme of Heilongjiang Province (No. GB03A203)Innovative Plan for the Fetched in Talent of NEFU of China.
文摘The surface properties of glass fiber were quantificationally analyzed by inverse gas chromatography （IGC）. Five n-alkanes （C6, C7, C8, C9, and C10） were chosen as apolar probes to characterize the dispersive component of surface free energy. Trichloromethane （CHCl3）, acetone, and tetrahydrofuran （THF） were chosen as polar probes to detect the Lewis acid-base parameters. It is found that the dispersive components of free energy are 32.3, 30.5, 27.5, and 26.9 mJ/m^2 at 70, 80, 90, and 100 ℃. respectively. The Lewis acidic number Ka of the glass fiber is 0.512 4, and the basic number Kb is 2.862. The results mean the glass fiber is a Lewis basic material.
文摘A unique SiC whisker wheel was invented,in which the whiskers were aligned normally to the grinding wheel surface.In this paper,grindabilities of the SiC whisker wheel are investigated and compared with those of other wheels of SiC grains,Al2O3 grains,as well as Al2O3 long and short fibres which were also aligned normally to the grinding wheel surface,respectively.The main research contents concern grinding characteristics of a directionally aligned SiC whisker wheel such as material-removal volume,wheel-wear rates,integrity of the ground surfaces,grinding ratios and grinding efficiency.Furthermore,grinding wheels of whiskers and fibres have a common disadvantage:they tend to load easily.The authors have proposed a simple method of loading-free grinding to overcome this propensity and investigate some related grinding characteristics under loading-free grinding conditions.
