1,419 research outputs found
Monte Carlo Investigation of Lattice Models of Polymer Collapse in Five Dimensions
Monte Carlo simulations, using the PERM algorithm, of interacting
self-avoiding walks (ISAW) and interacting self-avoiding trails (ISAT) in five
dimensions are presented which locate the collapse phase transition in those
models. It is argued that the appearance of a transition (at least) as strong
as a pseudo-first-order transition occurs in both models. The values of various
theoretically conjectured dimension-dependent exponents are shown to be
consistent with the data obtained. Indeed the first-order nature of the
transition is even stronger in five dimensions than four. The agreement with
the theory is better for ISAW than ISAT and it cannot be ruled out that ISAT
have a true first-order transition in dimension five. This latter difference
would be intriguing if true. On the other hand, since simulations are more
difficult for ISAT than ISAW at this transition in high dimensions, any
discrepancy may well be due to the inability of the simulations to reach the
true asymptotic regime.Comment: LaTeX file, 16 pages incl. 7 figure
630-mV open circuit voltage, 12% efficient n-Si liquid junction
We report the first experimental observation of a semiconductor/liquid junction whose open circuit voltage Voc is controlled by bulk diffusion/recombination processes. Variation in temperature, minority-carrier diffusion length, and/or in majority-carrier concentration produces changes in the Voc of the n-Si/CH3OH interface in accord with bulk recombination/diffusion theory. Under AM2 irradiation conditions, the extrapolated intercept at 0 K of Voc vs T plots yields activation energies for the dominant recombination process of 1.1–1.2 eV, in accord with the 1.12-eV band gap of Si. A crucial factor in achieving optimum performance of the n-Si/CH3OH interface is assigned to photoelectrochemical oxide formation, which passivates surface recombination sites at the n-Si/CH3OH interface and minimizes deleterious effects of pinning of the Fermi level at the Si/CH3OH junction. Controlled Si oxide growth, combined with optimization of bulk crystal parameters in accord with diffusion theory, is found to yield improved photoelectrode output parameters, with 12.0±1.5% AM2 efficiencies and AM1 Voc values of 632–640 mV for 0.2-Ω cm Si materials
Theoretical study of space plasmas Final report, 16 Feb. 1964 - 15 Mar. 1965
Interchange stability of Van Allen belt - Effect of resonant magnetic moment violation on trapped particles - Exact solution of universal instabilit
An improved perturbation approach to the 2D Edwards polymer -- corrections to scaling
We present the results of a new perturbation calculation in polymer
statistics which starts from a ground state that already correctly predicts the
long chain length behaviour of the mean square end--to--end distance , namely the solution to the 2~dimensional~(2D) Edwards model.
The thus calculated is shown to be convergent in ,
the number of steps in the chain, in contrast to previous methods which start
from the free random walk solution. This allows us to calculate a new value for
the leading correction--to--scaling exponent~. Writing , where in 2D,
our result shows that . This value is also supported by an
analysis of 2D self--avoiding walks on the {\em continuum}.Comment: 17 Pages of Revtex. No figures. Submitted to J. Phys.
Theoretical studies of space plasmas Summary report, 3 May 1965 - 1 May 1966
Synchrotron radiation, ionospheric currents, auroral bombardment, and plasma instabilitie
Nonlinear structures: explosive, soliton and shock in a quantum electron-positron-ion magnetoplasma
Theoretical and numerical studies are performed for the nonlinear structures
(explosive, solitons and shock) in quantum electron-positron-ion
magnetoplasmas. For this purpose, the reductive perturbation method is employed
to the quantum hydrodynamical equations and the Poisson equation, obtaining
extended quantum Zakharov-Kuznetsov equation. The latter has been solved using
the generalized expansion method to obtain a set of analytical solutions, which
reflect the possibility of the propagation of various nonlinear structures. The
relevance of the present investigation to the white dwarfs is highlighted.Comment: 7 figure
Differential Form of the Collision Integral for a Relativistic Plasma
The differential formulation of the Landau-Fokker-Planck collision integral
is developed for the case of relativistic electromagnetic interactions.Comment: Plain TeX, 5 page
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