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11.
Taek‐Joong Kim Baoan Li May‐Britt Hgg 《Journal of Polymer Science.Polymer Physics》2004,42(23):4326-4336
Fixed‐site–carrier membranes were prepared for the facilitated transport of CO2 by casting polyvinylamine (PVAm) on various supports, such as poly(ether sulfone) (PES), polyacrylonitrile (PAN), cellulose acetate (CA), and polysulfone (PSO). The cast PVAm on the support was crosslinked by various methods with glutaraldehyde, hydrochloric acid, sulfuric acid, and ammonium fluoride. Among the membranes tested, the PVAm cast on polysulfone and crosslinked by ammonium fluoride showed the highest selectivity of CO2 over CH4 (>1000). The permeance of CO2 was then measured to be 0.014 m3 (STP)/(m2 bar h) for a 20 μm thick membrane. The effect of the molecular weight of PVAm and feed pressure on the permeance was also investigated. The selectivity increased remarkably with increasing molecular weight and decreased slightly with increased pressure in the range of 1 to 4 bar. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4326–4336, 2004 相似文献
12.
Xiao‐Dong Pan 《Journal of Polymer Science.Polymer Physics》2004,42(13):2467-2478
For properly chosen elastomer compounds, thermorheological characterization is combined with an examination of the variation of the wet sliding friction with temperature. A conceptual argument leads to the assumption that the wet sliding friction should maximize at the energy dissipation peak associated with the dynamic softening transition at a characteristic frequency determined by the sliding speed and the effective smallest surface asperity scale. The dynamic softening transition is characterized with the peak in tan δ/G′n, where tan δ is the loss tangent, G′ is the elastic modulus, and n is a constant between 0 and 1. The William–Landel–Ferry transform is uncritically applied for extrapolating the position of the peak in tan δ/G′n at high frequencies. Even based on the criterion of tan δ, the results obtained on a concrete surface indicate that the effective smallest asperity scale is of order of 100 μm. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2467–2478, 2004 相似文献
13.
I. Peshko G. Galich M. Lopiychuk A. Khizhnyak V. Nakvasuk 《Optics & Laser Technology》1997,29(4):211-215
A laser system containing four CW Nd:YAG double-rod lasers, transforming optics and a fibre with input-output optics has been designed and investigated. It is shown that reduction of the beam parameter product of the non-Gaussian beams in the image space of the lens has made it possible to collect the emission of four lasers to the same fibre. Independent laser operation has provided the output power control in the range of 10–900 W with a stable light spot size on the input end of the fibre. 相似文献
14.
M. I. Pech-Canul F. Ortega-Celaya M. A. Pech-Canul 《Mechanics of Composite Materials》2006,42(3):283-296
The effect of SiO2 in SiCp and the following processing parameters on the microstructure and impact strength of Al/SiCp composites fabricated by pressureless infiltration was investigated: Mg content in the aluminum alloy, SiC particle size,
and holding time. Preforms of SiCp in the form of rectangular bars (10 × 1 × 1 cm) were infiltrated at 1150°C in an argon→nitrogen atmosphere for 45 and 60
min by utilizing two aluminum alloys (Al-6 Mg-11 Si and Al-9 Mg-11 Si, wt.%). The results obtained show that the presence
of SiO2 in SiC affects the microstructure and impact strength of the composites significantly. When Al4C3 is formed, the impact strength decreases. However, a high proportion of SiC to SiO2 limits the formation of the unwanted Al4C3 phase in the composites. Also, a higher content of Mg in the Al alloy lowers the residual porosity and, consequently, increases
the composite strength. The impact strength grows with decrease in SiC particle size and increases considerably when the residual
porosity is less than 1%.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 3, pp. 401–418, May–June, 2006. 相似文献
15.
W. Hufenbach R. Böhm A. Langkamp L. Kroll T. Ritschel 《Mechanics of Composite Materials》2006,42(2):151-162
The basic damage and failure models of multiaxially reinforced composites with a thermoplastic matrix are presented and verified.
Within the framework of continuum damage mechanics, a phenomenological model is introduced, where the damage is defined as
a change in the elasticity tensor. For damage identification, a specific ultrasonic device was developed. A combination of
an immersion set-up and a contact coupling device formed a system for an efficient determination of stiffness-tensor components
from convenient sets of velocity measurements. Linked to a tensile machine, it allowed us to measure the anisotropic damage
of the new materials group caused by tensile loading.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 2, pp. 221–234, March–April, 2006. 相似文献
16.
陈守信 《数学物理学报(A辑)》2003,23(4):419-430
对一阶拟线性双曲方程组一类广义Riemann问题,该文在一定条件下证明了,包含一个接触间断和一个中心波以及包含一个接触间断和一个激波的间断解的整体存在性和唯一性. 相似文献
17.
Othman Belhadj Miled David Grosso Jacques Livage 《Journal of Physics and Chemistry of Solids》2004,65(10):1751-1755
This paper describes the synthesis and optical pH sensing properties of a pH indicator dye activated mesostructured silica coated optical fibre. The pH-sensitive dye bromothymol blue was incorporated into the mesostructure sol precursor and thin films/coatings were used for pH-sensing applications without prior removal of the surfactant. The pH sensitivity range and operating wavelength were analysed by absorption measurements on layer dip-coated on glass slides. The pH sensing properties of coated optical fibre were tested by evanescent wave method. Experiments were carried out by using a series of solutions of known pH. No leaching was observed (except at very high pH) and an excellent reversibility was obtained between pH=2 and 5. 相似文献
18.
A new double pass long wavelength band erbium-doped fiber amplifier with enhanced noise figure characteristics is demonstrated. The noise figure is improved by about 2.6 dB with the incorporation of broadband conventional-band fiber Bragg grating (FBG) in between the two segments of erbium-doped fiber. By incorporating both the pre-amplifier and the FBG, the noise figure is further improved, which varies from 4.0 to 5.0 dB in the flat gain region from 1570 to 1600 nm. The gain varies from 32.0 to 33.4 dB within this region. The new amplifier with high gain and low noise figure can be useful as an inline amplifier in a wavelength division multiplexing transmission system. 相似文献
19.
用气压浸渗工艺制备了体积分数40%~50%Al2O3颗粒增强纯铝基复合材料,使用了4种不同尺寸的Al2O3颗粒,其平均粒径分别为5μm、10μm、30μm和60μm.测定了这些复合材料的静、动态压缩性能,并通过材料压缩前后密度变化的测量定量表征了材料的累计损伤,结果表明,与基体材料相似,这些复合材料表现出明显的应变率敏感性;当增强颗粒平均粒径小于60μm时,材料的累计损伤基本与应变率无关,而主要取决于材料的应变.材料中颗粒的破裂主要是由颗粒间的相互作用引起的.较小尺寸颗粒增强的复合材料具有较高的流动应力和较小的累计损伤,并随着颗粒体积分数的增加,材料的流动应力和损伤率都相应增加. 相似文献
20.
Controlling the gain shape of Er^3+—doped fluorozirconate fibre amplifier by a coherent field 下载免费PDF全文
We proposed a four-level system to explore the quantum interference effects on optical amplification.We found that the gain of the probe.including positions and values of gain peaks,can be adjusted by changing the coherent field and the incoherent pumping.At the same time,we can also modify the absorption profile of electromagnetically induced transparency by the incoherent pump.The results provide a method to flatten the gain of Erbium-doped fibre amplifiers. 相似文献