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排序方式: 共有314条查询结果,搜索用时 31 毫秒
51.
在大量的彩色图像处理工作中,已研究和发展了许多方法和技术对光谱颜色进行定量的控制、变换。无论失真彩色复现,还是假彩色合成,均能做到颜色的定量描述。本论文阐述用彩色光谱的三维属性进行编码演算,在浩瀚的颜色空间中进行线性和非线性的颜色参量映射变换,形成难以辨认和难以破解的密码图,对文本、图像的传递实现加密,是一个创新的技术。 相似文献
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53.
S. Ignat P. Sallamand A. Nichici A. B. Vannes D. Grevey E. Cical 《Optics & Laser Technology》2001,33(7)
There are very strong interests in developing low density advanced material systems for service at temperatures up to 1300°C. These materials should mainly have moderate fracture toughness at low and intermediate temperatures and should exhibit oxidation resistant behaviour. The intermetallic compound, MoSi2 has been considered to be an attractive candidate due to its melting point (2030°C) and excellent oxidation resistance at high temperatures. In this paper, we compare the results obtained with two different techniques for laser cladding, one using an online combination between Mo and Si powders, the second using direct injection of the MoSi2 powder. 相似文献
54.
S. Echeverría-Villagómez Y. Mitani-Nakanishi H. Nava-Jaimes 《Accreditation and quality assurance》2001,6(2):80-84
The Centro Nacional de Metrología (CENAM) has developed the MESURA Interinstitutional Network in collaboration with other research and development institutes
in Mexico. This network has the aim of providing integral metrological services to industry throughout the country, with uniform
standards of quality and consistency. The fulfillment of this aim has been possible because of a number of factors that have
made the MESURA Program an attractor for the integration of metrological services. Among these factors are: an unswerving
focus on the customer needs, an integral and logical problem solving approach to consultancy, adequate modular classification
of the consultants functions, clear-cut definition of the functions of each member of interdisciplinary groups, and a uniform
code of communication among the members of the network. The next stage of the strategy is to strengthen the link between metrology
and its industrial applications forming a new type of consultant with the technical experts from R&D Centers. These will be
consultants with general knowledge and experience in metrology, specialized in certain type of industrial processes and products.
The strategy will be initiated in the year 2000 and with it the MESURA Network is expected to make a strong contribution to
fostering the optimum use of metrology in industry and to act as a channel for the integration of other technologies in which
the participating Centers have expertise. 相似文献
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Teng Bao Jie Jin Mekdimu Mezemir Damtie Ke Wu Zhi Ming Yu Lie Wang Jun Chen Yong Zhang Ray L. Frost 《Journal of Saudi Chemical Society》2019,23(7):864-878
A zero-valent iron/rectorite nanocomposite (NZVI/rectorite) was developed as a heterogeneous H2O2 catalyst for P-chlorophenol degradation. The physicochemical properties of NZVI/rectorite were characterized by various techniques including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive spectrometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller analysis. Results showed that NZVI sphere nanoparticles were successfully loaded on the rectorite surface with less aggregation and good dispersion. Moreover, compared with acid-leached rectorite (30.91 m2/g), the NZVI/rectorite appeared to have larger surface area (50.75 m2/g). In addition, the effects of pH, reaction time, initial P-chlorophenol concentration, catalyst amount, and H2O2 dosage on the P-chlorophenol degradation were systematically investigated. Results showed that NZVI/rectorite presents better properties for the degradation and mineralization of P-chlorophenol compared with pristine NZVI due to the large surface area, low aggregation, and good dispersion of the former. The degradation mechanisms of P-chlorophenol by NZVI/rectorite were adsorption and reduction coupled with a Fenton-like reaction. Four successive runs of the stability and regeneration study also showed that the NZVI/rectorite were unchanged even after 100% of P-chlorophenol degradation ratio. This study has extended the application of NZVI/rectorite as environment function material for the removal of P-chlorophenol from the environment. 相似文献
57.
The coordination numbers of rigid spheres were simulated on a computer to obtain an improved empirical equation when surrounding spheres are of uniform size. In the case of two different species of surrounding spheres, the coordination numbers vary as a function of local composition and radius ratios. By fitting simulation results, correlations were proposed, which are expected to be of practical use in thermodynamic of real solutions. 相似文献
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59.
Ramesh B. Reddy Premansh Dudhe Priyanka Chauhan Sagnik Sengupta Venkatesh Chelvam 《Tetrahedron》2018,74(48):6946-6953
An efficient synthesis of N-Boc-tubuphenylalanine benzyl ester (N-Boc-Tup-OBn, 1a) and N-Boc-epi-tubuphenylalanine benzyl ester (N-Boc-epi-Tup-OBn, 1b) is reported herein. Regioselective aziridine 4 ring opening with carbon nucleophiles followed by hydroboration of 1,1-substituted aminoalkene 3 using 9-BBN and subsequent oxidation in an alkaline medium are used as the key steps to provide N-tosyl 1,4-aminoalcohols. The 1,4-aminoalcohols are successfully transformed into the desired products with an overall yield of 23% for 1a and 11% for 1b over 8 consecutive steps separately. 相似文献
60.
A very close triple resonance is observed in the Q-branch region of the C-H stretching fundamental transition in CF3H. The vibrational perturbations are analysed in terms of the rotational structure and of the vibrational zero-order spectrum of totally symmetric states. The relationship to time-dependent intramolecular processes is discussed. 相似文献