Showing papers by "Keigo Watanabe published in 1986"

Elastic scattering of electrons by water molecules over the range 100-1000 eV

Abstract: Relative values of differential cross sections (DCS) are measured by the crossed-beam method. Two cylindrical-mirror energy analysers are employed. One of them is moved to detect scattered electrons at every angle, and the other is fixed at an angle to monitor the elastic scattering events. The effects of target gas distributions in a molecular beam flowing out from a multicapillary array are taken account of to correct the relative values. The DCS are also measured at an angle for water molecules and helium atoms by using gas chamber. On the basis of the absolute DCS for He measured by Jansen et al. (1976), the relative DCS for water molecules are converted into absolute values. In addition, the DCS are calculated by the partial-wave method for the double Yukawa potential. The values of its three adjustable parameters are determined by comparison with the experimental DCS. A spherically symmetric realistic potential is also inferred without adjustable parameters from the charge distribution that was derived from molecular-orbital theory. The DCS calculated for this potential reproduce the experimental values fairly well.

Decentralized two-filter smoothing algorithms in discrete-time systems

Abstract: We develop some decentralized fixed-interval smoothing algorithms which are realized by the two-filter form in linear discrete-time systems, where the decentralized estimation structure consists of a central processor and of two local processors. Two approaches based on local filtering and local smoothing are considered for solving the problems of decentralized smoothing, smoothing update, and real-time smoothing. It is then shown that the notion of decentralized Kalman filtering plays a significant role in the derivation of the algorithms for the former approach, and that the introduction of the Hamiltonian system in discrete-time immediately gives the solutions of the problems in the latter approach. Moreover, some characteristics of the algorithms arising from each approach are also discussed.

Continuous-time decentralized smoothers based on two-filter form: identical local and global models

Abstract: This paper proposes some decentralized smoothing algorithms for a continuous-time linear estimation structure consisting of a central processor and of two local processors, in which the local models are assumed to be identical to the global model. The philosophy of the paper is to solve the problem in terms of the local forward and backward information (or Kalman) filters. The resulting algorithms are somewhat different from those based on the local smoothing estimates which have been studied by some other authors. Smoothing update and real-time smoothing algorithms are also presented, ft is shown that the present algorithms have some advantages: the global filtered estimates can be obtained in the course of computing the decentralized smoothing estimates and the central and local processors can be derived in a completely parallel fashion