Search

The numerical simulation method is used to analyze the process of gas purification with ceramic filters. The gas /solid two-phase flow field in the ceramic filter vessel was simulated using the Eulerian two-fluid model provided by FLUENT code. The variations of the pressure distribution in the filter cavity were analyzed. The distribution of the dust cake density along the under cleaning filter length was studied.

A series of chalcohalide glasses based on the composition of 0.9(Ge 30 Ga 5 Se 65 )-0.1CsI with different Tm 3+ /Dy 3+ -codoped ions concentrations were synthesized by melt-quenching technique. The absorption spectra and 2.9μm mid-infrared fluorescence spectra of glass samples under 800 nm laser excitation were measured. The results showed that Tm 3+ was an efficient sensitizer, which could enhance the Dy 3+ :2.9 μm fluorescence intensity significantly. The effective energy transfer between the two rare-earth ions were mainly attributed to the resonance energy transfer from Tm 3+ : 3 F 4 to Dy 3+ : 6 H 11/2 level. Emission cross section of 2.9 μm mid-infrared luminescence was also investigated according to Judd-Ofelt theory, σ e =2.51×10 −20 cm 2 .

The application of rigid ceramic filter for gas filtration on an industrial scale has shown unstable operation over periods of days. The behavior of the ceramic filtration in further application can be predict by measuring properties of a variety of dust and filtration operation condition. The aim of the experimental investigation is to analysis the pressure distribution inside and outside the ceramic filter along the filter length, and to analyze the pressure drop across the filter along the filter length. Ceramic filter filtration system composes multi-pipe filters for gas clean up is introduced. The operation parameters can be measured by this test system, such as the pressure in the filter cavity and outside the filter surface, velocity outside the filter, gas temperature and humidity, flow rate, dust particle size concentration before gad entering the filter tank and after the gas leaving the filer tank, the pulse cleaning pressure.

To solve the conflict between separation space and magnetic field intensity, an original magnetic circuit structure system of permanent magnet magnetic filter is designed by utilizing multi-dimensional magnet extrusion technologies, with multi-block NdFeB magnets of different structures and magnetization directions. The inside diameter of the ring magnets and ring soft iron is taken as separating space. To inspect the distribution of the magnetic field characteristics of magnetic circuit system, mathematical model is established, and the designed magnetic circuit system is simulated, taking advantage of the electromagnetic software Magnet. The simulation results show that a larger separating space and higher background magnetic density can be achieved simultaneously by means of the organic magnetic circuit system design, when the thickness of ring soft iron is 4mm and the diameter ratio (outside diameter to the diameter) of ring magnets is 10/3. The highest magnetic induction intensity of 29.2 mm separating space is 1.5T, which provides the basis for permanent magnet magnetic circuit design.

Er3+/Yb3+-codoped TeO2 -ZnO-BaO-La2O3 tellurite glass fiber was fabricated by rotation and rod-in-tube technologies. The thermal stability and optical refractive index of the core and cladding glasses were determined by DTA and optical coupler, respectively. The average background loss of tellurite glass fiber was 1.8 dB/m at 1310 nm. Optical microscopy and field emission scanning electron microscope (FESEM) were used to study structural characteristics of preforms and optical fibers. The main loss of tellurite glass fiber could be attributed to scatter centre due to core-cladding interface defects. The amplifier performance of tellurite glass fiber was investigated by pumping with 980 nm laser diode (LD). The gain coefficient and maximum signal gain were 0.21 dB/mW and 10 dB, respectively, for a pumping power of 120 mW. Gains exceeding 5 dB were obtained over 30 nm bandwidth from 1535 to 1565 nm. The minimum noise figure was 4.8 dB at 1557 nm.

The total load on a crank bearing was calculated by performing a load analysis of the crank connecting rod mechanism. The Reynolds equation for hydrodynamic lubrication of the crank bearing was established at the Reynolds boundary condition and was then solved using the Holland method. From this the regular track of the bearing axis was obtained. As the crank bearing gradually wears the eccentricity ratio corresponding to the minimum oil film thickness increases gradually. The oil-bound film eventually breaks down, which allows friction and collision between the metal surfaces of the crank pin and the bearing. The rigid impact leads to excitation of high frequency vibrations at the natural frequencies of the connecting rod. The experiments show that the wear condition of the crank bearing can be identified correctly through the vibration signature at the natural frequencies of the connecting rod. The degree of wear can be predicted accurately through the energy content of the high frequency bands.

We investigate optical near-field distributions of the unconventional C-apertures and the conventional square apertures in preliminary experiment with an aperture scanning near-field optical microscope. These nano-apertures are fabricated in Au film on a glass substrate with focused ion beam technology. The experimental results indicate the uptrend of output light intensity that a C-aperture enables the intensity maximum to increase at least 10 times more than a square aperture with same unit length. The measured near-field light spot sizes of C-aperture and square aperture with 200-nm unit length are 439 nm × 500 nm and 245 nm × 216 nm, respectively.

Evanescent wave interference is studied theoretically and experimentally. The interference patterns were directly measured with a scanning near-field optical microscope. The acquired image of the interference pattern is clear and has better contrast than that previously acquired with a photon-scanning tunnelling microscope or laser-trapped particles. The spatial period of the interference fringes is 180 nm, which agrees with the theoretical value. The results indicate that the probe of the scanning near-field optical microscope has a resolution beyond 100 nm. The relation between the evanescent field intensity and the distance is also measured. When the separation between the probe and the interface is up to 180 nm, the intensity can decrease to 1/e of the maximum.

In power systems, there are 40% to 50% capacitor-type devices in it. Capacitor performance has a direct relationship to the normal operation of the grid. This article describes several common power system equipments of high voltage capacitor structures and its equivalent circuits. Analyze the current capacitive dielectric loss online monitoring equipment of various methods and principles. And do a detailed comparison of various methods; introduce the advantages and disadvantages of these methods. Summarize several other current on-line monitoring methods. Then point out the sampling signal location of the capacitor-type devices.

Serials of chalcogenide glasses based on composition of 72GeS(2)-18Ga(2)S(3)-10CsI (in mol%) and doped with high Tm3+ content (up to 10,000 ppm) were prepared, and their luminescence properties were investigated under excitation with 800 nm laser. The influences of doping concentration on Judd-Ofelt intensity parameter Omega(i) spontaneous transition probability A, fluorescence branching ratio beta, and radiative lifetime tau(rad) of Tm3+ in the samples were studied. Four infrared emission bands observed were centered at 1.48, 1.8, 2.3, and 3.8 mu m, corresponding to optical transitions H-3(4) -> F-3(4), F-3(4) -> H-3(6), H-3(4) -> H-3(5) and H-3(5) -> F-3(4), respectively. For 1.0 wt.% Tm3+: doped sample, no concentration quenching was observed and its emission cross-sections at 2.3 and 3.8 mu m calculated by using Fuchtbauer-Ladenburg equation were 6.85 x 10(-21) and 7.66 x 10(-21) cm(-2), respectively. (C) 2010 Elsevier B.V. All rights reserved.

A series of Er 3+ /Yb 3+ co-doped (85- x ) TeO 2 -15B 2 O 3 - x SiO 2 (TBS x =0,5,10,15,20 mol%) glasses have been prepared. The thermal stability, absorption and emission spectra, lifetime of Er 3+ : 4 I 13/2 level and infrared transmit spectra were measured and discussed. The emission spectra of Er 3+ : 4 I 13/2 → 4 I 15/2 transition was analyzed using a peak-fit routine, and an equivalent four-level system was proposed to estimate the Stark splitting for the 4 I 15/2 and 4 I 13/2 levels of Er 3+ ions. It was found that the thermal stability of these glasses was improved by introducing SiO 2 . The difference between the glass transition temperature ( T g ) and the crystallization onset temperature ( T x ), Δ T = T x - T g , have came to 178℃ when SiO 2 was 20 mol%, indicating that they were suitable for fiber drawing. The fluorescence full width at half maximum (FWHM) and peak of emission cross-section ( σ peak e ) of Er 3+ ions in different glass hosts have been compared. The results indicate that these new TBS glasses are promising host material for broadband amplifiers.TeO 2 -B 2 O 3 -SiO 2 , thermal stability, G

Two types of interrogating schemes based on an waveguide grating for fiber Bragg grating sensors are reviewed. A method of extending the wavelength measuring range is proposed. And experiment results match well with the theory.

We have rigorously solved the standard BCS gap equation with the density of states of Van Hove type. The result shows that the enhancement ofTc is not as effective as previously estimated. It seems unlikely that Van Hove singularity inN(E) can be theTc-enhancement mechanism for the high-Tc Cu oxides.

The tapping temperature and the cooling rate are the key parameters during the development process of chalcogenide glass. Based on the theory of heat conduction equation, a model for calculating the temperature distribution of cylindrical chalcogenide glass is established using the least square fitting method in this paper. The tapping temperature, the temperature distribution and the cooling rate are simulated by using the model. The simulation results are compared with experimental data. The results show that the glass temperature stays in a non-steady non-uniform distribution, the surface cooling is the fastest, and the temperature decreases exponentially with time when the glass is tapped off from the furnace; the temperature of glass rod from the center to the edge is approximately of parabola distribution; the crystallization is the most difficult when the glass is tapped off at 50100 ℃ higher than crystallization temperature and a surface heat exchange coefficient of 180 W m-2K-1. Under the guidance of the theoretical model the uniform and transparent chalcogenide glass with a diameter of 110 mm and height of 80 mm is obtained. The glass transmission spectrum range is 0.817 m. The 2 mm thick flat sheet has the average transmittance higher than 65% in a 812 m range.

A series of chalcogenide glasses based on Ge 25 Ga 10 Se 65 system co-doped with Ho 3+ /Pr 3+ ions of different ratios were synthesized by melt-quenching technique. The absorption spectra,mid-infrared fluorescence and lifetime of glass samples under 908 nm laser excitation were measured. The emission cross section of Ho 3+ : 5 I 7 → 5 I 8 and absorption cross section of Pr 3+ : 3 H 4 → 3 F 2 were calculated. The energy transfer efficiency between Ho 3+ and Pr 3+ ions with different Pr 3+ ion concentrations have been discussed. Through fitting the 2.0 μm fluorescence decay curves of Ho 3+ ions,the energy transfer regime was judged. The results prove thatTm 3+ is an efficient sensitizer which enhances the Ho 3+ : 2.9 μm fluorescence intensity significantly.

Er 3+ /Yb 3+ co-doped tungsten-tellurite glasses, 65TeO 2 -25WO 3 -10R m O n (R m O n = PbO,BaO), (65+x) TeO 2 -(25-x)WO 3 - 10La 2 O 3 (x=0,5,10),(60+x)TeO 2 -(30-x)WO 3 -10Bi 2 O 3 (x=0,5,10) have been prepared. The thermal stability and spectral properties, such as absorption spec tra, emission spectra and lifetimes of the 4 I 13/2 level of Er 3+ were investigated. Results obtained show that tungsten-telluri te glasses have good thermal stability. All the glass samples except the Bi 2 O 3 -containing g lasses show no onset temperature of crystallization (T x ), indicating that they are stable for fiber drawing. Three intensity parameters Ω t (t= 2,4, 6) were calculated by Judd-Ofelt theory. It is shown that Ω 2 is domi nated b y the covalency between the Er 3+ and O 2- , the effect of as ymmetry in the local structures around the Er 3+ ions on Ω 2 can be neglected. The full width at half maximum (FWHM=71—77 nm) of the 4 I 13/2 → 4 I 15/2 emission and lifetimes of 4 I 13/2 level(τ m = 3—3.4 ms) of Er 3+ ions were measured. The emission cross-section ( σ peak =068—103×10 -20 cm 2 ) of the 4 I 13/2 → 4 I 15/2 transitio n of Er 3+ ions were calculated according to the McCum ber the ory. The FWHM and emission cross-section of Er 3+ ions at 1.5 μm ba nd in d ifferent glass hosts were compared. The results show that tungsten-tellurite gla ss will be the promising host material for 1.5 μm broadband amplification.