Energy deposition by auroral electrons in the atmosphere
Spatial distribution of energy deposited by auroral electrons in upper atmosphere, using Monte Carlo method
Berger, M. J.↗
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A preliminary Monte-Carlo analysis of the reflection of an imploding hemispherical shock wave similar to that generated in the UTIAS implosion driven hypervelocity launcher or shock tube
Cold wall and multibody collision effects on reflection of imploding shock waves using Monte Carlo method and molecular dynamics
Macpherson, A. K.↗
Study of the modulatory effects of the solar wind on galactic cosmic rays
Mathematical model using Monte Carlo method for modulation of galactic protons by solar wind
Moss, T. A.↗
Implications of regolith thickness in the Apollo 16 landing site
Determining thickness of regolith in Apollo 16 landing site by Monte Carlo method
Oberbeck, V. R.↗
Probable solar flare doses encountered on an interplanetary mission as calculated by the MCFLARE code
Probable solar flare doses on interplanetary mission calculated by MCFLARE computer program using Monte Carlo methods
Karp, I. M.↗
Diffuse reflection from clouds with horizontal inhomogeneities
Diffuse reflection from clouds with horizontal surface striations, using Monte Carlo method to follow photons through simplified models
Van Blerkom, D. J.↗
The modulation of galactic protons by the solar wind - A Monte Carlo approach
Solar wind modulation effects on galactic protons and cosmic rays, using radial magnetic field mathematical model and Monte Carlo method
Giuli, R. T.↗
Probable solar flare doses encountered on an interplanetary mission as calculated by the MCFLARE code
The computer program, MCFLARE, uses Monte Carlo methods to simulate solar flare occurrences during an interplanetary space voyage. The total biological dose inside a shielded crew compartment due to the flares encountered during the voyage is determined. The computer program evaluates the doses obtained on a large number of trips having identical trajectories. From these results, a dose D sub p having a probability p of not being exceeded during the voyage can be determined as a function of p for any shield material configuration. To illustrate the use of the code, a trip to Mars and return is calculated, and estimated doses behind several thicknesses of aluminum shield and water shield are presented.
Lahti, G. P.↗
Nuclear radiation environment analysis for thermoelectric outer planet spacecraft
Neutron and gamma ray transport calculations were performed using Monte Carlo methods and a three-dimensional geometric model of the spacecraft. The results are compared with similar calculations performed for an earlier design.
Davis, H. S.↗
Degree and plane of polarization of multiple scattered light. 1: Homogeneous cloud layers
The degree of polarization and the direction of the plane of polarization are calculated by a Monte Carlo method for homogeneous layers. Two solar zenith angles and a range of optical thicknesses up to 10 are considered. The results are compared with calculations for single scattered photons. For a given pair of incident and scattered directions, there are only two possible values for the direction of the plane of polarization differing by 90 deg for single scattering from spherical aerosols. The choice between these two values depends only on the sign of the element M(-) in the first row and second column of the scattering matrix in the I, Q, U, V representation. In most cases there is little change in the direction of the plane of polarization when multiple scattering is taken into account, so that this quantity can usually be predicted from a very simple trigonometric relationship to good accuracy. Measurements of the direction of the plane of polarization at appropriately chosen angles provides information about the size distribution of the scattering centers.
Kattawar, G. W.↗
Degree and plane of polarization of multiple scattered light. 2: Earth's atmosphere with aerosols
The degree of polarization, as well as the direction of the plane of polarization, were calculated by a Monte Carlo method for the reflected and transmitted photons from the earth's atmosphere. The solar photons were observed during multiple collisions with aerosols and the Rayleigh scattering centers in the atmosphere. The aerosol number density, as well as the ratio of aerosol to Rayleigh scattering, varies with height. The proportion of aerosol to Rayleigh scattering was appropriately chosen at each wavelength 0.4 microns and 0.7 microns; ozone absorption was included where appropriate. Three different aerosol number densities were used to study the effects of aerosol variations. Results are given for a solar zenith angle of 81.37 deg and a surface albedo of zero. The polarization of the reflected and transmitted photons was found to be sensitive to the amount of aerosols in the atmosphere at certain angles of observation.
Plass, G. N.↗
Variance reduction in Monte Carlo analysis of rarefied gas diffusion
The present analysis uses the Monte Carlo method to solve the problem of rarefied diffusion between parallel walls. The diffusing molecules are evaporated or emitted from one of two parallel walls and diffused through another molecular species. The analysis treats the diffusing molecule as undergoing a Markov random walk and the local macroscopic properties are found as the expected value of the random variable, the random walk payoff. By biasing the transition probabilities and changing the collision payoffs the expected Markov walk payoff is retained but its variance is reduced so that the M. C. result has a much smaller error.
Perlmutter, M.↗
Adaptive control of stochastic linear systems with unknown parameters
The problem of optimal control of linear discrete-time stochastic dynamical system with unknown and, possibly, stochastically varying parameters is considered on the basis of noisy measurements. It is desired to minimize the expected value of a quadratic cost functional. Since the simultaneous estimation of the state and plant parameters is a nonlinear filtering problem, the extended Kalman filter algorithm is used. Several qualitative and asymptotic properties of the open loop feedback optimal control and the enforced separation scheme are discussed. Simulation results via Monte Carlo method show that, in terms of the performance measure, for stable systems the open loop feedback optimal control system is slightly better than the enforced separation scheme, while for unstable systems the latter scheme is far better.
Ku, R. T.↗
The earth and the moon /Harold Jeffreys Lecture/.
The internal structures of the earth and the moon are compared in the light of the latest extensive data on the earth structure, mobility of the earth outer layers, and the properties of lunar crust. The Monte Carlo method is applied to develop an earth model by a stepwise process beginning with a random distribution of two elastic velocities and the density as a function of de pth. Lunar seismic, magnetic, and rock analysis data are used to infer the properties of the moon. The marked planetological contrast between the earth and the moon is shown to consist in that the earth is highly differentiated and still undergoes a large-scale differentiation, while the moon has lost its volatiles in its early history and has a cold dynamically inactive shell which has been without basic changes for three billion years.
Press, F.↗
Geometrical factor and directional response of single and multi-element particle telescopes.
After a general treatment of the gathering power of particle telescopes, exact formulae are presented for the geometrical factor and directional response of multielement cylindrically symmetric telescopes with circular or rectangular cross sections. Some useful approximations to these formulae are given. For the gathering power in arbitrary geometries, there is a discussion of applicable digital computer techniques focusing particularly on a Monte Carlo method.
Sullivan, J. D.↗
Calculation of the lunar photon albedo from galactic and solar proton bombardment.
The lunar photon albedo due to cosmogenic and primordial photon sources has been calculated. The individual photon leakage spectra from prompt photons produced by galactic cosmic ray (GCR) and solar cosmic ray (SCR) induced nuclear interactions, from the decay of GCR- and SCR-induced radionuclides, and from the decay of naturally occurring radionuclides are given. An approximate estimate of the leakage from the photon-electron cascade initiated by the decay of neutral pions is also given. Monte Carlo methods have been used to determine the nucleon-meson cascade, and discrete-ordinates methods were used for the photon and low-energy neutron transport.
Armstrong, T. W.↗
Transfer of resonance-line radiation in differentially expanding atmospheres. I - General considerations and Monte Carlo calculations.
A Monte Carlo method is given for analyzing the transfer of resonance radiation in a rapidly and differentially expanding nebula. Coherence in the frame of the atom is shown to lead to interesting modifications of the emergent radiation field, as compared with the other more usual assumptions of coherence or redistribution in the fluid frame. Results are presented in tabular form suitable for further use. Sample line profiles produced by pure scattering out of the continuum are generated, and it is shown that an arbitrarily high peak can be obtained. This conclusion is independent of the coherence assumption used. The distribution of the number of scatterings is found in all cases. An analytic solution is presented for the case of coherence in the fluid frame.
Caroff, L. J.↗
Degree and direction of polarization of multiple scattered light. I - Homogeneous cloud layers.
It is shown that the Monte Carlo method can provide useful information on the polarization and its direction for homogeneous layers corresponding to the haze C, nimbostratus, and ice crystals models. Results for various optical thicknesses and two solar zenith angles show the variation with these parameters. In most cases the direction of polarization with respect to the meridian plane (which contains the outgoing photon) does not change appreciably with the optical thickness of the scattering layer, so that the conclusion that the direction of polarization is determined mainly by the direction of the incident and scattered photons, obtained for single scattering, should apply approximately when multiple scattering is taken into account.
Kattawar, G. W.↗