Multistable corrugated shells

2008 ◽  
Vol 464 (2095) ◽  
pp. 1653-1672 ◽  
Author(s):  
A.D Norman ◽  
K.A Seffen ◽  
S.D Guest
Keyword(s):  
Symmetry Breaking ◽  
Isotropic Material ◽  
Global Scale ◽  
Local Scale ◽  
Shell Structures ◽  
Elastic Model ◽  
Anisotropic Properties ◽  
Corrugated Shell ◽  
Flat Sheet ◽  
Corrugated Shells

We have been constructing and investigating multistable corrugated shell structures. The multistability arises from the interaction between internal prestresses created during forming and nonlinear geometrical changes during deformation. Using a simplified analytical elastic model, we homogenize the properties of the shells through simultaneously considering the material on two scales: the ‘local’ scale of the isotropic material; and the ‘global’ scale of the corrugated sheet, which is then modelled as an equivalent flat sheet with anisotropic properties. This model is applied to simulate two modes of bistability observed in prototypes: first, prestressed corrugated shells that, when buckled, can coil up into a tube repeatably and reversibly; and second, corrugated sheets with a symmetry-breaking ‘twisting’ curvature. The model gives an intuitive understanding of the behaviour, and has enabled us to understand forming processes that give the behaviour we wish, including tristable shells that combine both bistable modes.

scholarly journals Global‐ and Local‐Scale High‐Resolution Event Catalogs for Algorithm Testing

2019 ◽  
Author(s):  
Lisa Linville ◽  
Ronald Chip Brogan ◽  
Christopher Young ◽  
Katherine Anderson Aur
Keyword(s):  
Global Scale ◽  
Local Scale ◽  
Algorithm Performance ◽  
Directional Information ◽  
Event Sequences ◽  
University Of Utah ◽  
International Monitoring ◽  
Using Data ◽  
The University ◽  
Global And Local

ABSTRACT During the development of new seismic data processing methods, the verification of potential events and associated signals can present a nontrivial obstacle to the assessment of algorithm performance, especially as detection thresholds are lowered, resulting in the inclusion of significantly more anthropogenic signals. Here, we present two 14 day seismic event catalogs, a local‐scale catalog developed using data from the University of Utah Seismograph Stations network, and a global‐scale catalog developed using data from the International Monitoring System. Each catalog was built manually to comprehensively identify events from all sources that were locatable using phase arrival timing and directional information from seismic network stations, resulting in significant increases compared to existing catalogs. The new catalogs additionally contain challenging event sequences (prolific aftershocks and small events at the detection and location threshold) and novel event types and sources (e.g., infrasound only events and long‐wall mining events) that make them useful for algorithm testing and development, as well as valuable for the unique tectonic and anthropogenic event sequences they contain.

Two-measure theory with third-rank antisymmetric tensor for local scale symmetry breaking

2017 ◽  
Vol 95 (6) ◽  
Author(s):  
Eduardo Guendelman ◽  
Hitoshi Nishino ◽  
Subhash Rajpoot
Keyword(s):  
Symmetry Breaking ◽  
Measure Theory ◽  
Local Scale ◽  
Antisymmetric Tensor

Networks of Photos, Landmarks, and People

Leonardo ◽  
2011 ◽  
Vol 44 (3) ◽  
pp. 240-243 ◽  
Author(s):  
David Crandall ◽  
Noah Snavely
Keyword(s):  
Recent Work ◽  
Human Behavior ◽  
Visual Representations ◽  
3D Models ◽  
Global Scale ◽  
Local Scale ◽  
Photo Sharing ◽  
The World ◽  
Vantage Points ◽  
Combining Information

Social photo-sharing sites like Flickr contain vast amounts of latent information about the world and human behavior. The authors describe their recent work in building automatic algorithms that analyze large collections of imagery in order to extract some of this information. At a global scale, geo-tagged photographs can be used to identify the most photographed places on Earth, as well as to infer the names and visual representations of these places. At a local scale, the authors build detailed 3D models of a scene by combining information from thousands of 2D photographs taken by different people and from different vantage points.

Autonomous Light Assessment Drone for Dark Skies Studies

2020 ◽  
Author(s):  
Matthew N. Goodell ◽  
Takara E. Truong ◽  
Stephanie R. Marston ◽  
Brett J. Smiley ◽  
Elliot R. Befus ◽  
...  
Keyword(s):  
Low Cost ◽  
Field Tests ◽  
Global Scale ◽  
Local Scale ◽  
Light Pollution ◽  
Artificial Light ◽  
Remote Site ◽  
Improper Use ◽  
Initial Results

Abstract The improper use of artificial light causing skyglow is detrimental to many types of wildlife and can potentially cause irregular human sleeping patterns. Studies have been performed to analyze light pollution on a global scale. However, light pollution data on a local scale is not of ten available and the effects at local scale have rarely been studied. Herein, a new custom-designed autonomous light assessment drone (ALAD) is described for evaluating light pollution at local scale. The ALAD is designed and equipped with a sky quality meter (SQM) to measure skyglow and a low-cost illuminance sensor to measure light from artificial sources. Outdoor field tests are performed at a remote site in central Utah and the measured results are validated against data from lightpollution-map.info. The SQM measurements are in agreement with the estimates from the light pollution map, and the initial results demonstrate feasibility of the ALAD for local-scale skyglow assessment.

Hydrodynamic Analysis of Macroalgae Local Model Using Computational Fluid Dynamics

2020 ◽  
Author(s):  
Ming Chen ◽  
Solomon C. Yim ◽  
Daniel Cox ◽  
Zhaoqing Yang ◽  
Thomas Mumford
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Current Model ◽  
Global Scale ◽  
Local Scale ◽  
Constant Current ◽  
Scale Model ◽  
Effective Diameter ◽  
Hydrodynamic Coefficients

Abstract In this article, a local scale, fully nonlinear coupled fluid-structural interaction (FSI) sugar kelp model has been developed using a computational fluid dynamics (CFD) method. In this model, to be consistent with available experimental data, the sugar kelp is approximated as elongated rectangles with smoothed isosceles triangles at the ends and a single kelp model with one end fixed in a channel with constant current model is developed. Several different current speeds are simulated, and the resulting drag forces and calculated drag coefficients are validated by comparison with experimental data from the literature. In a previous study, a global scale model was developed using a computational structural dynamics (CSD) method to simulate macroalgae farming system and guide the system configuration design. In the global scale model, the hydrodynamic forces are calculated using Morison’s equation and the kinematics and dynamics of the sugar kelp are simplified and the group of kelps attached to the long line is modeled as a slender structure with the same length and an effective diameter such that the volumes are consistent with the real physical system. This simplified model matches the weight and buoyancy but adjusting the hydrodynamic properties when the general hydrodynamic coefficients are employed. Therefore, optimal hydrodynamic coefficients used in global scale model were determined to obtain the hydrodynamic force more accurately. The validated local scale model is then be applied to determine the hydrodynamic coefficients of the simplified sugar kelp model for global dynamic analysis.

scholarly journals Sexual networks: measuring sexual selection in structured, polyandrous populations

2013 ◽  
Vol 368 (1613) ◽  
pp. 20120356 ◽  
Author(s):  
Grant C. McDonald ◽  
Richard James ◽  
Jens Krause ◽  
Tommaso Pizzari
Keyword(s):  
Sexual Selection ◽  
Temporal Structure ◽  
Natural Populations ◽  
Population Level ◽  
Global Scale ◽  
Local Scale ◽  
Emergent Property ◽  
Sexual Competition ◽  
Fine Grained ◽  
Multi Level

Sexual selection is traditionally measured at the population level, assuming that populations lack structure. However, increasing evidence undermines this approach, indicating that intrasexual competition in natural populations often displays complex patterns of spatial and temporal structure. This complexity is due in part to the degree and mechanisms of polyandry within a population, which can influence the intensity and scale of both pre- and post-copulatory sexual competition. Attempts to measure selection at the local and global scale have been made through multi-level selection approaches. However, definitions of local scale are often based on physical proximity, providing a rather coarse measure of local competition, particularly in polyandrous populations where the local scale of pre- and post-copulatory competition may differ drastically from each other. These limitations can be solved by social network analysis, which allows us to define a unique sexual environment for each member of a population: ‘local scale’ competition, therefore, becomes an emergent property of a sexual network. Here, we first propose a novel quantitative approach to measure pre- and post-copulatory sexual selection, which integrates multi-level selection with information on local scale competition derived as an emergent property of networks of sexual interactions. We then use simple simulations to illustrate the ways in which polyandry can impact estimates of sexual selection. We show that for intermediate levels of polyandry, the proposed network-based approach provides substantially more accurate measures of sexual selection than the more traditional population-level approach. We argue that the increasing availability of fine-grained behavioural datasets provides exciting new opportunities to develop network approaches to study sexual selection in complex societies.

A Multi-Scale Scheme for Modelling Fracture under Dynamic Loading Conditions

2014 ◽  
Vol 627 ◽  
pp. 37-40
Author(s):  
A. Karamnejad ◽  
L.J. Sluys
Keyword(s):  
Dynamic Loading ◽  
Static Problem ◽  
Global Scale ◽  
Local Scale ◽  
Material Point ◽  
Computational Homogenization ◽  
Scale Model ◽  
Multi Scale ◽  
Damaged Zone ◽  
Scale Scheme

Fracture in heterogeneous materials under dynamic loading is modelled using a multi-scale method. Computational homogenization is considered, in which the overall properties at the global-scale are obtained by solving a boundary value problem for a representative volume element (RVE) assigned to each material point of the global-scale model. In order to overcome the problems with upscaling of localized deformations, a non-standard failure zone averaging scheme is used. Discontinuous cohesive macro-cracking is modelled using the XFEM and a gradient-enhanced damage model is used to model diffuse damage at the local-scale. A continuous-discontinuous computational homogenization method is employed to obtain the traction-separation law for macro-cracks using averaged properties calculated over the damaged zone in the RVE. In the multi-scale model, a dynamic analysis is performed for the global-scale model and the local-scale model is solved as a quasi-static problem. Dispersion effects are then captured by accounting for the inertia forces at the local-scale model via a so-called dispersion tensor which depends on the heterogeneity of the RVE. Numerical examples are presented and the multi-scale model results are compared to direct numerical simulation results. Objectivity of the multi-scale scheme with respect to the RVE size is examined.

scholarly journals Scaling Biodiversity Conservation Efforts: An Examination of the Relationship Between Global Biodiversity Targets and Local Plans

2021 ◽  
Vol 2 ◽  
Author(s):  
Jennifer Rae Pierce ◽  
Sabrina Drill ◽  
Michael D. Halder ◽  
Mika Mei Jia Tan ◽  
Anushri Tiwari ◽  
...  
Keyword(s):  
Biodiversity Conservation ◽  
Biological Diversity ◽  
Critical Role ◽  
Well Being ◽  
Global Scale ◽  
Local Scale ◽  
Convention On Biological Diversity ◽  
Spheres Of Influence ◽  
Global Biodiversity ◽  
The Relationship

Cities have a critical role to play in meeting global-scale biodiversity targets. Urban socio-ecological systems connect human and ecological well-being. The outsized impact of cities reaches well-beyond their geographic borders through cultural, ecological, and economic interactions. Although cities account for just 2% of the earth's surface, they host over half of the human population and are responsible for 75% of consumption. The Parties to the Convention on Biological Diversity (CBD) and others have acknowledged the important role cities can play in achieving global targets. In response, at least 110 cities have produced plans focused on biodiversity, but we do not know the extent to which these city plans align with global targets or what role they play in achieving these targets. Here, we explore the relationship between global biodiversity conservation targets and local biodiversity plans to identify how elements at the two scales align or diverge. We compared the CBD Strategic Plan 2011–2020 (Aichi Targets) with 44 local biodiversity plans (often called LBSAPs) from cities around the world. We analyzed more than 2,800 actions from the local plans to measure the relationship with these global targets. Our results show how local approaches to biodiversity conservation can inform post-2020 global frameworks to improve coordination between global and local scale processes. We identify actions particular to the local scale that are critical to conserve global biodiversity and suggest a framework for improved coordination between actors at different scales that address their respective roles and spheres of influence.

scholarly journals Global gradients in intertidal species richness and functional groups

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Jakob Thyrring ◽  
Lloyd S Peck
Keyword(s):  
Functional Groups ◽  
Global Scale ◽  
Local Scale ◽  
Rocky Intertidal ◽  
Marine Biodiversity ◽  
Diversity Patterns ◽  
The North ◽  
Discernible Effect ◽  
Diversity Gradients ◽  
Α Diversity

Whether global latitudinal diversity gradients exist in rocky intertidal a-diversity and across functional groups remains unknown. Using literature data from 433 intertidal sites, we investigated α-diversity patterns across 155° of latitude, and whether local-scale or global-scale structuring processes control α-diversity. We, furthermore, investigated how the relative composition of functional groups changes with latitude. α-diversity differed among hemispheres with a mid-latitudinal peak in the north, and a non-significant unimodal pattern in the south, but there was no support for a tropical-to-polar decrease in α-diversity. Although global-scale drivers had no discernible effect, the local-scale drivers significantly affected α-diversity, and our results reveal that latitudinal diversity gradients are outweighed by local-processes. In contrast to α-diversity patterns, three functional groups: predators, grazers and suspension-feeders diversity declined with latitude, coinciding with an inverse gradient in algae. Polar and tropical intertidal data were sparse, and more sampling is required to improve knowledge of marine biodiversity.

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