A detector telescope with charge coupled devices for particle dosimetry in space

A telescopic device with charge coupled devices (CCDs) for particle dosimetry in space has been developed. Data on ionization events of energetic particles passing the CCDs are processed in an image analyzing system of a PC. As ‘Charged Particle Telescope’ (CHAPAT), the equipment was flown on the russian space station MIR during the EUROMIR mission in 1995. The response of the CCDs to various charged particles and methods for the discrimination of heavy particles in CCDs are discussed. First results of a correlation of temporal particles fluxes to the actual orbital parameters of MIR clearly identify passages through the South Atlantic Anomaly (SAA).     

Measurement of Solid-gas Two-phase Flow using Optical Fiber Sensor

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镁铁双羟基复合金属氧化物的可控合成及晶面生长特征研究

采用成核 /晶化隔离法合成镁铁双羟基复合金属氧化物MgFe LDH ,考察了Mg∶Fe摩尔比对MgFe LDH晶形的影响 ,探讨了晶化温度及晶化时间对晶面生长选择性及晶粒尺寸的影响规律 .结果表明 ,随Mg∶Fe摩尔比增大 ,层板阳离子排列更为规整 .晶化温度对晶粒尺寸的影响显著大于晶化时间的影响 .晶化温度相同 ,随晶化时间延长 ,MgFe LDH的晶体结构趋于完整 ,晶粒尺寸变化不大 ;晶化时间相同 ,随晶化温度升高 ,晶体结构趋于完整 ,晶粒尺寸明显增大 .所得到的MgFe LDH沿a轴方向的晶粒尺寸对晶化温度变化的敏感程度远大于对晶化时间变化的敏感程度 ,但总是沿a轴方向的晶粒尺寸大于沿c轴方向的尺寸 ,即 [110 ]晶面的生长速率比[0 0 2 ]晶面的生长速率快     

Polynuclear crystal growth in electrocrystallization of silver: Determining the nucleus size via the nucleation theorem

We employ the nucleation theorem for a model-independent determination of the size of the two-dimensional (2D) Ag nucleus with the aid of experimental data for nucleation-mediated electrochemical crystal growth. The growth is investigated of a screw dislocation-free Ag(100) single crystal face in aqueous solution of AgNO₃ at 318 K. The data are for the stationary values of the overpotential during galvanostatic pulses with sufficiently high amplitudes to ensure polynuclear growth mechanism. It is found that the Gibbs-Thomson equation of the classical theory of 2D nucleation describes very well the experimentally obtained overpotential dependence of the size of the 2D Ag nucleus. Published in Russian in Elektrokhimiya, 2008, vol. 44, No. 6, pp. 698–703. The text was submitted by the authors in English.     

Rainfall forecasting by technological machine learning models

Accurate forecasting of rainfall has been one of the most important issues in hydrological research. Due to rainfall forecasting involves a rather complex nonlinear data pattern; there are lots of novel forecasting approaches to improve the forecasting accuracy. Recurrent artificial neural networks (RNNS) have played a crucial role in forecasting rainfall data. Meanwhile, support vector machines (SVMs) have been successfully employed to solve nonlinear regression and time series problems. This investigation elucidates the feasibility of hybrid model of RNNs and SVMs, namely RSVR, to forecast rainfall depth values. Moreover, chaotic particle swarm optimization algorithm (CPSO) is employed to choose the parameters of a SVR model. Subsequently, example of rainfall values during typhoon periods from Northern Taiwan is used to illustrate the proposed RSVRCPSO model. The empirical results reveal that the proposed model yields well forecasting performance, RSVRCPSO model provides a promising alternative for forecasting rainfall values.     

Robust tracking of moving sound source using scaled unscented particle filter

Tracking an active sound source involves the modeling of non-linear non-Gaussian systems. To address this problem, this paper proposed scaled unscented particle filter (SUPF) algorithm for tracking moving sound source. The particle filter part of the SUPF provides the general probabilistic framework to handle non-linear non-Gaussian systems, and the scaled unscented Kalman filter (SUKF) part of the SUPF generates better proposal distributions by taking into account the most recent observation. Meanwhile, models used in SUPF algorithm were also explored for the sound source motion, observation and the likelihood of the sound source location in the light of the Langevin process. Compared with the conventional PF approach, the simulated results demonstrated that the SUPF algorithm had superior tracking performance.     

Modelling gaps between block pavers

This paper investigates factors which affect the resultant gaps between block pavers when these are laid over a large area as part of a civil engineering process to form a trafficable surface. The development of the gaps between the edges of adjacent blocks can be described by a family of two-dimensional difference equations which reflect the physical characteristics of the blocks and the sequence in which the blocks are placed together. Monte Carlo studies of the solutions of these equations have been used to show patterns of development of gaps for specific combinations of parameter values and to investigate the impact of particular variables on gap performance.     

Application of the thermodynamics of curved boundary layers to the scaled particle theory of hard-sphere fluids

The thermodynamics of curved boundary layers, with the assumption that the distance between the surface of a fluid cavity and its surface of tension is a quadratic function of the cavity radius, is applied to the exact thermo-dynamic expression forG, the central function of scaled particle theory. The coefficients in the quadratic representation are determined so as to satisfyall five of the known exact conditions onG valid for cavity radii between one-half and one molecular diameter. The results of the calculation are displayed as the hard-sphere equation of state, the boundary tension associated with the surface of tension, and the distance between the cavity surface and the surface of tension. Although the hard-sphere equation of state obtained by this method using all five conditions onG is more accurate than in the case where only two or three conditions are used, the original scaled particle theory, in whichG itself was represented simply by a quadratic function of inverse powers of cavity radius, still yields the more accurate equation of state. Nevertheless, the present approach limits approximations to the distance between the cavity surface and the surface of tension, a small quantity in itself. The path to a still more improved theory remains well defined, contingent upon the discovery of additional exact conditions, and does not depend, as in the original scaled particle theory, on a form forG arrived at in a somewhat ad hoc manner.Research supported under NSF Grant #GP-12408.     

3He-rich solar flares

A new subgroup of³He rich solar flares is found on reanalysing the global data.³He/H ratio as a function of maximum proton flux at an energy of about 10 MeV shows a break-up of the data into two groups. The first group follows the anticorrelation of³He/H ratio with the proton flux, as expected in the plasma process acceleration models. But the second group has a constant³He/H ratio as a function of maximum proton flux. This is not in conformity with the plasma process models. But this is expected in models where the nuclear spallation reactions are responsible for the production of³He. It is also found that the same break-up into two distinct groups follows if one plots the location of the flares in the solar disc. The first group is more or less confined to the west limb of the Sun, whereas the second group is more widely spread out across the solar disk. Visiting Professor, Tata Institute of Fundamental Research, Bombay, August–September, 1983.     

Circular orbits of an electron around a proton in Schwarzschild geometry

The energy of an electron in circular orbits around a proton in Schwarzschild geometry has been investigated and is found to be red shifted. The electrical dipole moment of such a system is also estimated.