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111.
Very large-scale matrix problems currently arise in the context of accurately computing the coordinates of points on the surface of the earth. Here geodesists adjust the approximate values of these coordinates by computing least-squares solutions to large sparse systems of equations which result from relating the coordinates to certain observations such as distances or angles between points. The purpose of this paper is to suggest an alternative to the formation and solution of the normal equations for these least-squares adjustment problems. In particular, it is shown how a block-orthogonal decomposition method can be used in conjunction with a nested dissection scheme to produce an algorithm for solving such problems which combines efficient data management with numerical stability. The approach given here parallels somewhat the development of the natural factor formulation, by Argyris et al., for the use of orthogonal decomposition procedures in the finite-element analysis of structures. As an indication of the magnitude that these least-squares adjustment problems can sometimes attain, the forthcoming readjustment of the North American Datum in 1983 by the National Geodetic Survey is discussed. Here it becomes necessary to linearize and solve an overdetermined system of approximately 6,000,000 equations in 400,000 unknowns—a truly large scale matrix problem. 相似文献
112.
Several diatomic metal halides, BaBr, BaCl, BiBr, BiCl, CuBr, CuCl, PbBr, and PbCl, were produced by reacting metal vapor with Br2 or Cl2. Molecules were identified from chemiluminescence and laser induced photoluminescence. Using a pulsed, tunable dye laser, the radiative lifetimes of the C2 II state of BaBr and BaCl were found to be 8 and 22 nsec, respectively. 相似文献
113.
Gene Barnett 《International journal of quantum chemistry》1977,12(2):427-429
A comparison of experimental and theoretical values for Δα = α e - α g, assuming no sigma-electron contribution, shows a great distortion by π-electron calculations. We analyze existing electrochromic data, using this assumption, and report Δα values of 44 Å3 for coronene and 43 Å3 for triphenylene. Some general properties of Δα are discussed in terms of potential energy curves which suggest interesting calculations to relate excited matrix elements with experimental measurements. 相似文献
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Linear least squares solutions by householder transformations 总被引:1,自引:0,他引:1
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Tetrakis(diethylamido)zirconium reacts with 2‐(dimethylamino)methyl pyrrole (DMAMP) and 2,5‐[bis(dimethylamino)methyl]pyrrole (BDMAMP) to give Zr(NEt)2(DMAMP)2 1 and Zr(NEt)3(BDMAMP) 2 , respectively. Both 1 and 2 have been characterized by 1H and 13C NMR spectroscopies and 1 has also been characterized by X‐ray crystallography. Complex 1 shows an agostic interaction between Zr and H(21A) in solid state that is not sustained in solution. Reacting 1 with 2 equivalents of trimethylsilyl chloride in toluene yields ZrCl2(DMAMP)2 3 in 75% yield which was characterized by 1H and 13C NMR spectroscopies. 相似文献
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The First Heteropentanuclear Extended Metal‐Atom Chain: [Ni+Ru25+Ni2+Ni2+(tripyridyldiamido)4(NCS)2]
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Dr. Min‐Jie Huang Dr. Shao‐An Hua Dr. Ming‐Dung Fu Dr. Gin‐Chen Huang Prof. Caixia Yin Chih‐Hung Ko Dr. Ching‐Kuo Kuo Chia‐Hung Hsu Dr. Gene‐Hsiang Lee Kuan‐Yi Ho Dr. Chia‐Hsin Wang Prof. Yaw‐Wen Yang Prof. I‐Chia Chen Prof. Shie‐Ming Peng Prof. Chun‐hsien Chen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(16):4526-4531
This study develops the first heteropentametal extended metal atom chain (EMAC) in which a string of nickel cores is incorporated with a diruthenium unit to tune the molecular properties. Spectroscopic, crystallographic, and magnetic characterizations show the formation of a fully delocalized Ru25+ unit. This [Ru2]‐containing EMAC exhibits single‐molecule conductance four‐fold superior to that of the pentanickel complex and results in features of negative differential resistance (NDR), which are unobserved in analogues of pentanickel and pentaruthenium EMACs. A plausible mechanism for the NDR behavior is proposed for this diruthenium‐modulated EMAC. 相似文献