scholarly journals Compressible helical turbulence: Fastened-structure geometry and statistics

2021 ◽  
Vol 28 (3) ◽  
pp. 032302
Author(s):  
Jian-Zhou Zhu
Keyword(s):  
Helical Turbulence ◽  
Structure Geometry

Consistency Management System Between Product Design and the Lifecycle

2013 ◽  
Author(s):  
Shinichi Fukushige ◽  
Yuki Matsuyama ◽  
Eisuke Kunii ◽  
Yasushi Umeda
Keyword(s):  
Manufacturing Industry ◽  
Product Lifecycle Management ◽  
Product Lifecycle ◽  
Consistency Management ◽  
Management Scheme ◽  
Data Architecture ◽  
Structure Geometry ◽  
Resource Circulation ◽  
Lifecycle Management ◽  
Lifecycle Design

Within the framework of sustainability in manufacturing industry, product lifecycle design is a key approach for constructing resource circulation systems of industrial products that drastically reduce environmental loads, resource consumption and waste generation. In such design, designers should consider both a product and its lifecycle from a holistic viewpoint, because the product’s structure, geometry, and other attributes are closely coupled with the characteristics of the lifecycle. Although product lifecycle management (PLM) systems integrate product data during its lifecycle into one data architecture, they do not focus on support for lifecycle design process. In other words, PLM does not provide explicit models for designing product lifecycles. This paper proposes an integrated model of a product and its lifecycle and a method for managing consistency between the two. For the consistency management, three levels of consistency (i.e., topological, geometric, and semantic) are defined. Based on this management scheme, the product lifecycle model allows designers to evaluate environmental, economic, and other performance of the designed lifecycle using lifecycle simulation.

scholarly journals Polarized Cosmological Gravitational Waves from Primordial Helical Turbulence

2005 ◽  
Vol 95 (15) ◽  
Author(s):  
Tina Kahniashvili ◽  
Grigol Gogoberidze ◽  
Bharat Ratra
Keyword(s):  
Gravitational Waves ◽  
Helical Turbulence

Lagrangian velocity covariance in helical turbulence

1977 ◽  
Vol 81 (2) ◽  
pp. 385-398 ◽  
Author(s):  
Robert H. Kraichnan
Keyword(s):  
Correlation Time ◽  
Perturbation Expansion ◽  
Direct Interaction ◽  
Helical Turbulence ◽  
Quantitative Accuracy ◽  
Lagrangian Velocity ◽  
Thin Spherical Shell ◽  
Direct Interaction Approximation ◽  
Interaction Approximation ◽  
Substantial Factor

The effect of helicity on the Lagrangian velocity covarianceUL(t) in isotropic, normally distributed turbulence is examined by computer simulation and by a renormalized perturbation expansion forUL(t). The first term of the latter represents Corrsin's (1959) conjecture (extrapolated to allt), which relatesUL(t) to the Eulerian covariance and the distributionG(x, t) of fluid-element displacement. Truncation of the expansion at the first term yields the direct-interaction approximation forG(x, t). The expansion suggests that with or without helicity Corrsin's conjecture is valid ast→ ∞ and that in either caseUL(t) behaves asymptotically like$t^{-(r+\frac{3}{2})}$if the spectrum of the Eulerian field varies likekr+2at small wavenumbers. Corrsin's conjecture breaks down at small and moderatetif there is strong helicity while remaining accurate at alltin the mirror-symmetric case. Computer simulations for a frozen Eulerian field with spectrum confined to a thin spherical shell inkspace indicate that strong helicity induces an increase in the Lagrangian correlation time by a factor of approximately three. Direct-interaction equations are constructed for the Lagrangian space-time covariance and the resulting prediction forUL(t) is compared with the simulations. The effect of helicity is well represented quantitatively by the direct-interaction equations for small and moderatetbut not for larget. These frozen-field results imply good quantitative accuracy at alltin time-varying turbulence whose Eulerian correlation time is of the order of the eddy-circulation time. In turbulence with weak helicity, the directinteraction equations imply that the Lagrangian correlation of vorticity with initial velocity is more persistent thanUL(t), by a substantial factor.

Protein structure: geometry, topology and classification

2001 ◽  
Vol 64 (4) ◽  
pp. 517-590 ◽  
Author(s):  
William R Taylor ◽  
Alex C W May ◽  
Nigel P Brown ◽  
András Aszódi
Keyword(s):  
Protein Structure ◽  
Structure Geometry
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