The authors present a basic multivariate framework for assessing the interactions between human activities and environmental processes that illustrates the range of potential nonlinearities, feedbacks, and synergisms ...
详细信息
The authors present a basic multivariate framework for assessing the interactions between human activities and environmental processes that illustrates the range of potential nonlinearities, feedbacks, and synergisms and some of the possible analytic complexities. They suggest that as the scientific community is increasingly called on not just to diagnose specific environmental problems but also to explore policy options and other management issues, much greater emphasis will be placed on quantitative assessment of the larger question of management of the global environment. It is in this relatively unexplored arena that the authors foresee many opportunities for multidisciplinary, multivariate assessments that would undoubtedly benefit from advances in supercomputing technologies.< >
We discuss an alternative technique to the lattice-gas automata for the study of hydrodynamic properties, namely, we propose to model the lattice gas with a Boltzmann equation. This approach completely eliminates the ...
We discuss an alternative technique to the lattice-gas automata for the study of hydrodynamic properties, namely, we propose to model the lattice gas with a Boltzmann equation. This approach completely eliminates the statistical noise that plagues the usual lattice-gas simulations and therefore permits simulations that demand much less computer time. It is estimated to be more efficient than the lattice-gas automata for intermediate to low Reynolds number R≲100.
Modular scintillation cameras are gamma cameras with relatively small crystal faces, a small number of photomultiplier tubes (PMTs), and independent processing electronics. Our prototypical module has a 10 cm square c...
详细信息
Direct numerical simulation techniques are used to study the effect of spontaneous symmetry breaking leading to the phenomenon of large‐scale secondary flow generation by anisotropic small‐scale flow. It is shown th...
Direct numerical simulation techniques are used to study the effect of spontaneous symmetry breaking leading to the phenomenon of large‐scale secondary flow generation by anisotropic small‐scale flow. It is shown that anisotropy is a major factor that determines the ability of the small‐scale flow to generate the inverse energy cascade, that the large‐scale secondary flow is strongly anisotropic—almost unidirectional, and that the helical property of the primary flow is irrelevent. The pairing instability and long‐wave modulation of the subharmonic are important in the process of generation of the large‐scale structure.
This paper addresses the possible connections between chaos, the unpredictable behavior of solutions of finite dimensional systems of ordinary differential and difference equations and turbulence, the unpredictable be...
This paper addresses the possible connections between chaos, the unpredictable behavior of solutions of finite dimensional systems of ordinary differential and difference equations and turbulence, the unpredictable behavior of solutions of partial differential equations. It is dedicated to Martin Kruskal on the occasion of his 60th birthday.
A field-theoretic approach, analogous to Kraichnan’s direct-interaction approximation, to the stability theory of complex three-dimensional flows is developed. The long-wavelength stability of a class of Beltrami flo...
A field-theoretic approach, analogous to Kraichnan’s direct-interaction approximation, to the stability theory of complex three-dimensional flows is developed. The long-wavelength stability of a class of Beltrami flows in an unbounded, viscous fluid is considered. We examine two flows in detail, to illustrate the effects of strong isotropy versus strong anisotropy in the basic flow. The effect of the small-scale flow on the long-wavelength perturbations may be interpreted as an effective viscosity. Using diagrammatic techniques, we construct the first-order smoothing and direct-interaction approximations for the perturbation dynamics. It is argued that the effective viscosity for the isotropic flow is always positive, and approaches a value independent of the molecular viscosity in the high-Reynolds-number limit; this flow is thus stable to long-wavelength disturbances. The anisotropic flow has negative effective viscosity for some orientations of the disturbance, and is therefore unstable, when its Reynolds number exceeds √2 .
作者：
Haseman, J.K.Wlnbush, J.S.Statistics and Biomathematics Branch
Biometry and Risk Assessment Program National Institute of Environmental Health Sciences North Carolina 27709 P.O. Box 12233 Research Triangle Park United States Division of Mathematics
Center for Food Safety and Applied Nutrition Food and Drug Administration Washington D.C 20204 United States
Use of Dual Control Groups to Estimate False Positive Rates in Laboratory Animal Carcinogenicity Studies. HASEMAN, J.K., WINBUSH, J.S., AND O'DONNELL, M.W., JR. (1986). Fun-dam. Appl. Toxicol. 7, 573-584. Tumor in...
A theory is presented for Pierrehumbert's three-dimensional short-wave inviscid instability of the simple two-dimensional elliptical flow with velocity field u(x,y,z)=Ω(−Ey,E−1x,0). The fundamental modes, which a...
A theory is presented for Pierrehumbert's three-dimensional short-wave inviscid instability of the simple two-dimensional elliptical flow with velocity field u(x,y,z)=Ω(−Ey,E−1x,0). The fundamental modes, which are also exact solutions of the nonlinear equations, are plane waves whose wave vector rotates elliptically around the z axis with period 2πΩ. The growth rates are the exponents of a matrix Floquet problem, and agree with those calculated by Pierrehumbert.
暂无评论