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991.
朱方生 《武汉大学学报(理学版)》1995,(3)
构造了线性二次型最优控制的并行算法,介绍了这个并行算法在武汉大学“WUDP91”并行分布式处理系统上试算的数值应用软件的框图.本软件适用于既定动态系统的平衡问题.对于经济系统,可通过政策控制变量来调节和改善其状态和响应.对于自治系统可找出最优控制使得消耗函数达到最小值.通过对一系列例子进行试算,结果证实,所构造的并行算法和相应的数值软件是有效的,其加速比约为7. 相似文献
992.
In 1991, one of the authors showed the existence of quadratic transformations between the Painlevé VI equations with local monodromy differences (1/2, a, b, ±1/2) and (a, a, b, b). In the present paper we give concise forms of these transformations. They are related to the quadratic transformations obtained by Manin and Ramani–Grammaticos–Tamizhmani via Okamoto transformations. To avoid cumbersome expressions with differentiation, we use contiguous relations instead of the Okamoto transformations. The 1991 transformation is particularly important as it can be realized as a quadratic‐pull back transformation of isomonodromic Fuchsian equations. The new formulas are illustrated by derivation of explicit expressions for several complicated algebraic Painlevé VI functions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
993.
By introducing the conception "relativistic differential Galois group" for the second order polynomial systems, we establish the relation between the conformal relativistic differential Galois group and the subgroup of M(o)bius transformations, and prove that the system is integrable in the sense of Liouville if its conformal relativistic differential Galois group is solvable with a derived length at most 2. Some omissions on the structures of solvable subgroups of M(o)bius transformations at the first author's article published in this journal in 1996 are refreshed in this paper. 相似文献
994.
995.
Measurement of small-signal and large-signal responses of packaged laser modules at high temperature
Ning Hua Zhu Ji Min Wen Hai Peng Song Shang Jian Zhang Liang Xie 《Optical and Quantum Electronics》2006,38(15):1245-1257
In this paper, the pulsed injection method is extended to measure the chip temperature of various packaged laser modules,
such as the DFB laser modules, the FP laser modules, and the EML laser modules. An optimal injection condition is obtained
by investigating the dependence of the lasing wavelength on the width and period of the injection pulse in a relatively wide
temperature range. The small-signal frequency responses and large-signal performances of packaged laser modules at different
chip temperature are measured. The adiabatic small-signal modulation characteristics of packaged LD are first extracted. In
the large-signal measurement, the effects of chip temperature, bias current and driving signal on the performances of the
laser modules are discussed. It has been found that the large-signal performances of the EML modules depend on the different
red-shift speeds of the DFB and EAM sections as chip temperature varying, and the optimal characteristics may be achieved
at higher temperature. 相似文献
996.
Leszek Wachowski Antoni Grodzicki Piotr Piszczek Monika Richert Magdalena Hofman 《Reaction Kinetics and Catalysis Letters》2007,91(1):93-99
Hydrogenation of styrene has been applied as a test reaction to study the catalytic activity of TiO2 deposited by the CVD (chemical vapour deposition) method on the surface of a carbonaceous material enriched in nitrogen (CN). 相似文献
997.
There is a general interest in ranking schemes applied to complex entities described by multiple attributes. Published rankings
for universities are in great demand but are also highly controversial. We compare two classification and ranking schemes
involving universities; one from a published report, ‘Top American Research Universities’ by the University of Florida's TheCenter and the other using DEA. Both approaches use the same data and model. We compare the two methods and discover important equivalences.
We conclude that the critical aspect in classification and ranking is the model. This suggests that DEA is a suitable tool
for these types of studies. 相似文献
998.
多级轴流压气机全工况特性计算 总被引:1,自引:0,他引:1
本文使用三维粘性流动计算软件Fine/Numeca,对某十五级轴流压气机进行了内流流场和全工况特性的数值计算尝试。分析了该压气机在设计工况和非设计工况的性能,同时把整机计算结果和前七级叶片的计算结果进行了比较。计算结果表明,当计算的级数较少时,目前的软件和硬件平台可以比较合理地预测压气机的全工况特性;而当计算的级数较多时,准确的数值模拟仍需要更为准确的多级模型和数值方法。 相似文献
999.
《Electroanalysis》2006,18(22):2218-2224
This article deals with the development of a method for the determination of osmium at a carbon paste electrode (CPE) modified with cationic surfactants of the quaternary ammonium salt type; namely, cetyltrimethylammonium bromide (CTAB) and 1‐(ethoxycarbonyl)‐pentadecyltrimethyl‐ammonium bromide (Septonex); both being added in situ and serving for preconcentration of osmium via its hexachloroosmate(IV) anion. The proper electrochemical detection was performed by cathodic scanning in the differential pulse voltammetric mode. Optimization studies concerning important experimental parameters also included a specially performed potentiometric titration, helping to define the actual stoichiometry for the ion‐pairing process, the main principle and driving force of the accumulation step. In a chloride/acetate buffer based supporting medium and with Septonex as the modifier of choice, the reduction signal for osmium was found to be proportional to the Os(IV) concentration in a range from 5×10?9 to 5×10?7 mol L?1 with a limit of detection close to 5×10?9 mol L?1 (with preconcentration for 60 s). The method capable to determine Os(IV) in the presence of both Pt(IV) and Ir(III) was tested on model solutions as well as with real sample of industrial waste water (spiked with the analyte); both yielding the recovery rates within 88–99%. 相似文献
1000.
Chun‐Hao Huang Sheng‐Hsiung Yang Kuei‐Bai Chen Chain‐Shu Hsu 《Journal of polymer science. Part A, Polymer chemistry》2006,44(1):519-531
Five novel fluorene‐containing polymers, poly[(9,9‐dimethylfluoren‐2‐yl)acetylene] ( PFA1 ), poly[(1‐pentyl‐2‐(9,9‐dimethylfluoren‐2‐yl)acetylene) ( PFA2 ), poly[1‐decyl‐2‐(9,9‐dimethylfluoren‐2‐yl)acetylene] ( PFA3 ), poly[1‐phenyl‐2‐(9,9‐dimethylfluoren‐2‐yl)acetylene] ( PFA4 ), and poly[1‐(3,4‐difluorophenyl)‐2‐(9,9‐dimethylfluoren‐2‐yl)acetylene] ( PFA5 ) were synthesized by the polymerization of the corresponding fluorene‐substituted acetylenic monomers ( M1–M5), using WCl6, MoCl5, and TaCl5 as catalysts and n‐Bu4Sn as a cocatalyst. The synthesized polymers were thermally stable and readily soluble in common organic solvents. The degradation temperatures for a 5% weight loss of the polymers were ∼352–503 °C under nitrogen. PFA1–PFA5 show emission peaks from 402 to 590 nm. Besides, their electroluminescent properties were studied in heterostructure light‐emitting diodes (LEDs), using PFA2–PFA5 as an emitting layer. The PFA5 device revealed an orange‐red emission peak at 602 nm with a maximum luminescence of 923 cd/m2 at 8 V. A device with the ITO/PEDOT/ a mixture of PFA2 (98 wt %) and PFA5 (2 wt %)/Ca/Al showed near white emission. Its maximum luminance and current efficiency are 450 cd/m2 at 15 V and 1.3 cd/A, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 519–531, 2006 相似文献