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排序方式: 共有240条查询结果,搜索用时 15 毫秒
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Polypentafluorostyrene (PPFS), polymethylacrylate (PMA), and poly(pentafluorostyrene-co-methylacrylate), poly(PFS-co-MA) were prepared and the wetting characteristics of polymer blends of PPFS and PMA were compared with that of poly(PFS-co-MA) via contact angle measurements. The critical surface tension of polypentafluorostyrene was found to be 22.6 dyne/cm, which is comparable to the value reported for polytrifluoroethylene (22 dyne/cm). The critical surface tension of poly(PFS-co-MA) is not linearly related to its composition. The polymer blends of PPFS and PMA exhibit significant surface enrichment of the fluoropolymer. The harmonic-mean method1 was employed to determine surface tensions of these polymers and many known polymers. It is found that the method produces useful surface tension data provided the contact angle values are derived from testing liquids of dissimilar polarity. 相似文献
4.
M. Taniewski K. Skutil R. Lachowicz A. Lachowicz B. Dudek D. Czechowicz 《Catalysis Today》1992,13(4):529-536
Catalytic oxidative coupling of methane with pyrolysis of C2 H6 in a heated post-catalytic zone /PCZ/ has been carried out in a stainless steel pilot scale convertor. The mechanism of transformations of C2H6, C2H4, CO2, CO, H2O, H2 in PCZ have been studied and the routes of their decay and formation established. A strong catalytic wall effect has been demonstrated in several cases. The inevitability of some C2H4 losses in PCZ has been indicated. 相似文献
5.
Z. Surowiak J. Dudek Yu. I. Goltzov I. A. Bugajan V. E. Yurkevich 《Journal of Materials Science》1991,26(16):4407-4410
A PZT ceramic modified by 0.4Pb-(1–x)(B2O3)–x(GeO2) glass, and glass-ceramics modified by V2O5, have been obtained. The influence of the chemical composition of the glasses on the mechanical strength and dielectric parameters of these ceramics is investigated. The mechanical and electrical parameters of PZT ceramics are considerably improved by small additions of glass ( 1 mass %) of suitable composition. During heat treatment, the mobility of the domain walls may be changed as a result of the interaction of smelt glass with the surface layer of the crystallites (resulting from a change of V
Pb
t"
vacancy concentration in grains and decreased mechanical tension on the grain boundaries). By introducing the glass, we can decrease the porosity of the ceramics and thus decrease the attenuation of surface acoustic waves in piezoelectric filters. The origin of the liquid phase during sintering of the PZT glass-ceramics prevents PbO evaporation. This determines the preservation of the solution's stoichiometry. The glass addition leads to a decrease in the sintering temperature of PZT, which simplifies the technological process. The glass ceramics are obtained by common ceramic technology which is used for commercial piezoceramic production. The main technological problem is choosing the chemical composition and concentration of the glass and thermal process parameters. 相似文献
6.
M. A. Dudek R. S. Sidhu N. Chawla 《JOM Journal of the Minerals, Metals and Materials Society》2006,58(6):57-62
Severallead-free material systems are availableas replacements for traditional lead-based solders in microelectronic packaging,
including near-eutectic combinations oftin-rich alloys. Although these materials have superior mechanical properties as compared
to the Pb-Sn system, much work remains in developing these materials for electronic packaging. Small additions of rare-earth
elements have been shown to refine the microstructure of several lead-free solder systems, thus improving their mechanical
properties. This study investigated the effect of the addition of lanthanum on the melting behavior, microstructure, and shear
strength of an Sn-3.9Ag-0.7Cu alloy. The influence of LaSn3 intermetallics on microstructural refinement and damage evolution in these novel solders is discussed. 相似文献
7.
In this article we present a method for automatically recovering complete and dense depth maps of an indoor environment by
fusing incomplete data for the 3D environment modeling problem. The geometry of indoor environments is usually extracted by
acquiring a huge amount of range data and registering it. By acquiring a small set of intensity images and a very limited
amount of range data, the acquisition process is considerably simplified, saving time and energy consumption. In our method,
the intensity and partial range data are registered first by using an image-based registration algorithm. Then, the missing
geometric structures are inferred using a statistical learning method that integrates and analyzes the statistical relationships
between the visual data and the available depth on terms of small patches. Experiments on real-world data on a variety of
sampling strategies demonstrate the feasibility of our method.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献
8.
Spinel growth is studied by analytical electron microscopy in the fibre-matrix interface of as-processed and in thermal treated -Al2O3 fibre reinforced AlSi12CuMgNi alloys. In the as-processed composites a few nanometer large spinel crystals are observed in the fibre-matrix interface. They are interpreted as the reaction product of remnants of the SiO2 binder, with magnesium segregating in the interface. In the thermally treated material, large spinel crystals of a few tenths of a micrometer grow on the fibre, preferentially at positions where -Al2O3 crystals reach the fibre surface. The spinel grows into the aluminium grain of the matrix, as well as into -Al2O3 of the fibre. The orientational relationship of the spinel and the alumina is studied and the results are discussed in relation to the fibre wetting, adhesion and fibre-matrix reaction. 相似文献
9.
This paper presents a novel approach to modeling curiosity in a mobile robot, which is useful for monitoring and adaptive data collection tasks, especially in the context of long term autonomous missions where pre-programmed missions are likely to have limited utility. We use a realtime topic modeling technique to build a semantic perception model of the environment, using which, we plan a path through the locations in the world with high semantic information content. The life-long learning behavior of the proposed perception model makes it suitable for long-term exploration missions. We validate the approach using simulated exploration experiments using aerial and underwater data, and demonstrate an implementation on the Aqua underwater robot in a variety of scenarios. We find that the proposed exploration paths that are biased towards locations with high topic perplexity, produce better terrain models with high discriminative power. Moreover, we show that the proposed algorithm implemented on Aqua robot is able to do tasks such as coral reef inspection, diver following, and sea floor exploration, without any prior training or preparation. 相似文献
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