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971.
972.
A new mathematical algorithm is proposed to address the essential details of vertical distributions of horizontal velocity for one‐dimensional steady open‐channel flow. This new algorithm comprises a system of weighted averaged equations developed from corresponding Reynolds equations by performing weighted average operations instead of conventional depth average operations. It is the system of weighted averaged equations, instead of the vertical grids, that allows for more hydraulic coefficients identifiable. It can be thought of as an extension of the St. Venant equations to address the vertical distributions of horizontal velocities, as well as the water surface profiles. To avoid the difficult expansion of governing partial differential equations in high order, an indirect scheme is proposed to solve hydraulic variables through their weighted average values. The governing partial differential equations are generated by using a variety of weight functions, and the weighted averages of relevant hydraulic variables are taken as the unknown independent variables to be solved first. Then, on the basis of the values and polynomial expansions of these weighted averaged velocities, a system of linear algebraic equations is generated and the unknown hydraulic variables or their coefficients are easily solved. Note that the new model is not proposed to compete with any three‐dimensional models in modeling accuracy or accommodation ability to all conditions. It just provides a valuable option to study the vertical structure of flow in open channels where only essential detail and reasonable accuracy of vertical distributions are required, and the data availability and other conditions limit the application of fully three‐dimensional models. The performance of the model is evaluated with experimental data of flows in two different flumes. It is shown that the model well predicted the velocity profiles of sections along the centerlines of these flumes with reasonable accuracy and essential details of vertical distributions of horizontal velocity. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
973.
974.
Wei Feng Yunzhou Li Shidong Zhou Jing Wang Minghua Xia 《AEUE-International Journal of Electronics and Communications》2010,64(2):168-172
This letter focuses on the simplified sum capacity evaluation for the uplink of a generalized multi-user distributed antenna system (DAS). Based on system scale-up, we derive a good approximation of the sum capacity by generalizing the results from random matrix theory. An iterative method is presented to calculate the unknown parameters in the approximation. The approximation is illustrated to be quite accurate and the iterative method is demonstrated to be quite efficient by Monte Carlo simulations. 相似文献
975.
976.
The mixture of cesium hydroxide and terminal alkynes in dry DMF in the presence of 4(A°), molecular sieves was stirred for 3.0 h at room temperature under N2, then aryltellurenyl bromide in THF was added, and the reaction mixture was stirred for 2.0 h. Alkynyl tellurides were obtained in about 90% yields by flash chromatography. 相似文献
977.
A series of four novel hydrazine-modified diamine conjugates (7a-b, 8a-b) were synthesized and evaluated for cytotoxicity against Melanoma B 16, α-difluoromethylornithine (DFMO)-treated B 16, spermidine (SPD)-treated B 16, Mouse leukemia L 1210 and Hela cell lines. Both the DFMO-B 16 and SPD-B 16 experiments indicated that conjugates 7a-b and 8a-b could recognize the polyamine transporter (PAT) and enter the cells in part or in whole via PAT, although they were not as efficient as the reference, 9- anthracenemethyl homospermidine (1). 2007 Chao Jie Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. 相似文献
978.
We characterize monoids over which all S-acts are CC-injective and find conditions under which CC-injectivity of all acts implies that all acts are C-injective.
Research of X. Zhang supported by the China Scholarship Council No. 2006101056.
Research of Y. Chen supported by the NNSF of China (No. 10771077) and the NSF of Guangdong Province (No. 06025062). 相似文献
979.
Xia Li Min Lu Qi Wu De‐shui Lv Xian‐Fu Lin 《Journal of polymer science. Part A, Polymer chemistry》2008,46(1):117-126
To develop designed polymer–drug conjugates, where the rate of drug liberation and hepatoma cell targeting function could be rationally and widely controlled, we facilely synthesized a series of novel, galactose‐functionalized polymer–acyclovir conjugates with different linkers and first reported the effect of the linker structure including the type of acyclovir‐linked bond (an ester bond or an amide bond) and relative length of the linker between acyclovir and the polymer main chain on release rate and targeting ability of conjugates. In vitro release studies showed that the cumulative released acyclovir from these polymer–acyclovir conjugates was between 24 and 65% in pH 1.2 glycine solution after 7 days. The ester bond more easily underwent hydrolysis than the amide bond. The longer the relative linker length was, the faster the acyclovir was released. The cell recognition experiments visualized using confocal laser scanning microscopy exhibited that the resultant galactose‐functionalized polymer–acyclovir conjugates had evident targeting to hepG2 cells, and targeting ability was also in connection with the relative length of linker. By choosing appropriate linker, cellular internalization of acyclovir could be well achieved. We consider these results to be helpful for the design of multifunctional polymeric prodrugs, in which the required release rate and targeting ability could be rationally controlled by predetermined molecular architecture. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 117–126, 2008 相似文献
980.
We have built a complete Raman detection system for multi-trace-gas diagnosis, which is suitable for analyzing the dissolved gases in electric power system. In the system, a high-sensitivity CCD device connected to a spectrometer is used as the detection unit of the Raman system. A near-confocal cavity is used for improving the detection sensitivity of the system. In the effective spectral range of about 570–710 nm, Raman spectra of eight typical gases are achieved by using this Raman system. The detection limits for different gases have been obtained: 126 ppm for CO2, 21 ppm for CH4, 63 ppm for C2H4, 42 ppm for C2H2, 96.6 ppm for H2. The detectability of the system satisfies the requirements of gas diagnosis in power transformer. 相似文献