scholarly journals A novel rotational inertia damper for heave motion suppression of semisubmersible platform in the shallow sea

2019 ◽  
Vol 26 (7) ◽  
pp. e2368 ◽  
Author(s):  
Ruisheng Ma ◽  
Kaiming Bi ◽  
Hong Hao
Keyword(s):  
Rotational Inertia ◽  
Shallow Sea ◽  
Heave Motion ◽  
Motion Suppression

scholarly journals Heave motion suppression of a Spar with a heave plate

2004 ◽  
Vol 31 (5-6) ◽  
pp. 669-692 ◽  
Author(s):  
Longbin Tao ◽  
Shunqing Cai
Keyword(s):  
Heave Plate ◽  
Heave Motion ◽  
Motion Suppression

Management of the Dutch Waddensea

1984 ◽  
Vol 16 (3-4) ◽  
pp. 485-495 ◽  
Author(s):  
D Vreugdenhil
Keyword(s):  
The Netherlands ◽  
Middle Ages ◽  
Human Activities ◽  
Nature Reserve ◽  
The Other ◽  
Hydrological Processes ◽  
Dutch Government ◽  
Shallow Sea ◽  
Management Objectives ◽  
Late Middle Ages

It was not until the late Middle Ages that the sea penetrated far into the interior of The Netherlands, thus flooding three quarters of a million hectares of land. Since then half a million hectares have been reclaimed from the sea. The Dutch Government chose to preserve the remaining quarter of a million hectares of shallow sea with mudflats of the Waddensea as a nature reserve. The management objectives are at one hand to preserve all characteristic habitats and species with a minimal interference by human activities in geomorphological and hydrological processes, and at the other hand to guarantee the safety against the sea of the inhabitants of the adjacent mainland and islands and to facilitate certain economic and recreational uses of the Waddensea without jeopardizing the natural qualities. These objectives are being elaborated in managementplans.

Unident: Providing Impact Sensations on Handheld Objects via High-Speed Change of the Rotational Inertia

2021 ◽  
Author(s):  
Shuntaro Shimizu ◽  
Takeru Hashimoto ◽  
Shigeo Yoshida ◽  
Reo Matsumura ◽  
Takuji Narumi ◽  
...  
Keyword(s):  
High Speed ◽  
Rotational Inertia ◽  
Speed Change

Dynamic Analysis and Configuration Design of a Two-Component Wave-Energy Absorber

2012 ◽  
Author(s):  
Christophe Cochet ◽  
Ronald W. Yeung
Keyword(s):  
Wave Energy ◽  
Degrees Of Freedom ◽  
Outer Cylinder ◽  
Rigid Body Dynamics ◽  
Contact Forces ◽  
Energy Extraction ◽  
Energy Absorber ◽  
Compound Cylinder ◽  
Motion Study ◽  
Heave Motion

The wave-energy absorber being developed at UC Berkeley is modeled as a moored compound cylinder, with an outer cylinder sliding along a tension-tethered inner cylinder. With rigid-body dynamics, it is first shown that the surge and pitch degrees of freedom are decoupled from the heave motion. The heaving motion of the outer cylinder is analyzed and its geometric proportions (radii and drafts ratios) are optimized for wave-energy extraction. Earlier works of Yeung [1] and Chau and Yeung [2,3] are used in the present heave-motion study. The coupled surge-pitch motion can be solved and can provide the contact forces between the cylinders. The concept of capture width is used to characterize the energy extraction: its maximization leads to optimal energy extraction. The methodology presented provides the optimal geometry in terms of non-dimensional proportions of the device. It is found that a smaller radius and deeper draft for the outer cylinder will lead to a larger capture width and larger resulting motion.

Bioenergetic potentials in terrestrial, shallow-sea and deep-sea hydrothermal systems

2021 ◽  
pp. 120449
Author(s):  
Guang-Sin Lu ◽  
Douglas E. LaRowe ◽  
Jan P. Amend
Keyword(s):  
Deep Sea ◽  
Hydrothermal Systems ◽  
Shallow Sea

scholarly journals Tetrahedra of varying density and their applications

2021 ◽  
Author(s):  
Dennis R. Bukenberger ◽  
Hendrik P. A. Lensch
Keyword(s):  
Tetrahedral Mesh ◽  
Rotational Inertia ◽  
Exact Mass ◽  
Accurate Analysis ◽  
Exact Integration ◽  
Voronoi Cells ◽  
Current State ◽  
Chebyshev Norm ◽  
Exact Calculations ◽  
Vector Matrix

Abstract We propose concepts to utilize basic mathematical principles for computing the exact mass properties of objects with varying densities. For objects given as 3D triangle meshes, the method is analytically accurate and at the same time faster than any established approximation method. Our concept is based on tetrahedra as underlying primitives, which allows for the object’s actual mesh surface to be incorporated in the computation. The density within a tetrahedron is allowed to vary linearly, i.e., arbitrary density fields can be approximated by specifying the density at all vertices of a tetrahedral mesh. Involved integrals are formulated in closed form and can be evaluated by simple, easily parallelized, vector-matrix multiplications. The ability to compute exact masses and centroids for objects of varying density enables novel or more exact solutions to several interesting problems: besides the accurate analysis of objects under given density fields, this includes the synthesis of parameterized density functions for the make-it-stand challenge or manufacturing of objects with controlled rotational inertia. In addition, based on the tetrahedralization of Voronoi cells we introduce a precise method to solve $$L_{2|\infty }$$ L 2 | ∞ Lloyd relaxations by exact integration of the Chebyshev norm. In the context of additive manufacturing research, objects of varying density are a prominent topic. However, current state-of-the-art algorithms are still based on voxelizations, which produce rather crude approximations of masses and mass centers of 3D objects. Many existing frameworks will benefit by replacing approximations with fast and exact calculations. Graphic abstract

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