Trade-offs in Computer-aided Biomimetics

Biomimetics, the application of mechanisms observed in nature to inform technical solutions, is inherently cross-disciplinary. For the most part, however, practitioners are only expert in one domain, e.g., engineering. Being a layman in the other domain, biology, can make it hard and time-consuming to find and understand relevant information. Computer-Aided Biomimetics (CAB) involves the development of computational tools to overcome this domain-expertise mismatch. Finding a bridge between engineering and biology has been challenging. Although a plethora of methodological approaches have been proposed to bridge the engineering and biology domains, Biomimetics remains adventitious and research intensive. We give an overview of previous research efforts in CAB and motivate our approach that revolves around the resolution of biological trade-offs. This is a unique approach, as previous work has always aimed to extract engineering functions from biological texts. We describe our novel CAB system that extracts trade-offs, a within-domain concept to indicate a dialectical relation between two or more biological traits. We provide a description of our dataset for the extraction of trade-offs from biology research papers, as well as our state-of-the-art Relation Extraction system. The dataset consists of over 1.5k sentences taken from biology research papers, describing a trade-off or similar high-level relation between two or more concepts. Furthermore, we provide an in-depth analysis of the information extracted by our CAB system from a corpus of 10k biology research papers. We show in a qualitative analysis that our system extracts key concepts and relations from biology research papers that are relevant to Biomimetics. Unique to our approach is that our system makes it feasible to collect a comprehensive list of the system parameters and solution principles used in biology. This enables statistical analysis, such as finding the distribution of fundamental principles among the resolution of various trade-offs. Notably, the solutions to trade-offs differ little over various hierarchical levels of biology. This makes our finding relevant to any research that aims to find desired, but underutilized, properties observed in nature

Anisotropy in mechanical properties and fracture behavior of an oxide dispersion Fe20Cr5Al alloy

Anisotropy of fracture toughness and fracture behavior of Fe20Cr5Al oxide dispersion-strengthened alloy has been investigated by means of compression tests, hardness tests, and wedge splitting test. The results show a small effect of the compression direction on yield strength (YS) and strain hardening. The YS is minimum for longitudinal direction and maximum for the tangential direction. The transverse plastic strain ratio is similar for tangential and longitudinal directions but very different from that in normal direction. Hardness depends on the indentation plane; it is lower for any plane parallel to the L-T plane and of similar magnitude for the other orthogonal planes, i.e., the L-S and T-S planes. Macroscopically, two failure modes have been observed after wedge-splitting tests, those of LS and TS specimens in which fracture deviates along one or two branches normal to the notch plane, and those of LT, TL, SL, and ST specimens in which fracture propagates along the notch plane. Besides LT and TL specimens present delaminations parallel to L-T plane. Both, the fracture surface of branching cracks and that of the delaminations, show an intergranular brittle fracture appearance. It is proposed that the main cause of the delamination and crack branching is the alignment in the mesoscopic scale of the ultrafine grains structure which is enhanced by the 〈110〉- texture of the material and by the presence in the grain boundaries of both yttria dispersoids and impurity contaminations. An elastoplastic finite element analysis was performed to study what stress state is the cause of the branches and delaminations. It is concluded that the normal to the crack branches and/or the shear stress components could determine the crack bifurcation mechanism, whereas the delamination it seems that it is controlled by the magnitude of the stress component normal to the delamination plane. © The Minerals, Metals & Materials Society and ASM International 2014.Peer Reviewe

Strawberry fruit resistance to simulated handling

Harvest operations are currently the main source of mechanical injury of strawberry (Fragaria x ananassa Duch.). Experiments were designed to simulate conditions encountered during commercial handling. Individual fruits were subjected to impact or compression forces with similar energy to determine the sensitivity to mechanical injury. Bruise volume was used as the measurement of injury. Bruise severity increased as a function of impact energy for both impact types. However, dropped fruits had larger bruise volume than fruits submitted to pendulum impactor at the same energy level. Doubling the impact energy (0.040 to 0.083 J) increased bruise volume by 7 times (13 to 91 mm³). Fruits dropped from 380 mm (0.075 J) showed 71% greater bruise volume than those dropped from either 130 mm (0.025 J) or 200 mm (0.040 J). Compressed fruits showed higher bruise volume than other tests. Some cultivars are more susceptible to compression forces than others. 'Sweet Charlie' berries showed bruise volume 40% higher than the others cultivars when subjected to compression. Fruits subjected to impact showed bruise volume lower than the compressed fruits, indicating the possibility to be handled and graded in a packing line.A etapa de colheita é a principal fonte de danos físicos ao morango (Fragaria x ananassa Duch.). Experimentos foram realizados para simular condições encontradas durante manuseio. Frutos foram submetidos individualmente às forças de impacto e compressão em energias similares para determinar sensibilidade dos frutos a danos físicos. Volume da injúria física foi utilizado para mensurar a incidência do dano físico ocorrido. Severidade da lesão aumenta, com incremento da energia, tanto para força de impacto como para compressão. Todavia, frutos submetidos à queda livre demonstraram maiores volumes de danos físicos do que frutos submetidos a danos ocasionados por pendulo no mesmo nível de energia. Dobrando a energia de impacto (0,040 para 0,083 J) ocorreu aumento no volume da injúria em sete vezes (13 para 91 mm³). Frutos submetidos à queda de 380 mm (0,075 J) demonstraram volumes de danos físicos 71% superiores do que aqueles ocasionados em queda de 130 mm (0,025 J) ou 200 mm (0,040 J). Frutos em teste de compressão mostraram maiores volumes de injúrias físicas do que outros testes. Alguns cultivares são mais sensíveis à força de compressão do que outros. Frutos cultivar 'Sweet Charlie' apresentaram volume de injúria 40% superiores do que outros quando submetidos à força de compressão. Morangos submetidos à força de impacto demonstraram volume de injúria inferior do que aqueles comprimidos, indicando a possibilidade dos morangos serem classificados e manuseados em uma linha de beneficiamento

Mechanical properties of mussel byssus threads

The byssus threads of the common mussel, Mytilus edulis L., have been tested mechanically and the results from the tests related to the ecology of the animal. The threads are mechanically similar to other crystalline polymers such as polyethylene having a modulus of about 108N m−2 and a long relaxation time. Resilience of 60% is similar to tendon; ultimate strain is about five times that of tendon at 0.44. The thread is laid down with a prestrain of 10% and so guys the mussel in position. Calculation shows that a mussel with 50 byssus threads would be able to resist all but severe winter storms

The "Click" mechanism in dipteran flight: if it exists then what effect does it have?

This paper is concerned with the flight mechanism of diptera. For many years it was thought that the flight mechanism incorporated a "click". In recent years, however, doubt has been cast as to whether this exists, or whether it is an artifact of experimental procedure. The aim of this paper is to contribute to this debate by presenting an investigation into the advantages or disadvantages of such a mechanism by conducting a dynamic analysis of a simplified model of such a mechanism. It is shown that, provided the mechanism is driven well below its resonance frequency and it is well-damped, i.e., it does a lot of work, then the flight mechanism with a "click" has distinct advantages over a system that does not have a "click" but is driven at its resonant frequency