Littérature scientifique sur le sujet « Tool-use and plasticity »
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Articles de revues sur le sujet "Tool-use and plasticity"
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Miller, Luke E., Matthew R. Longo et Ayse P. Saygin. « Tool Use Modulates Somatosensory Cortical Processing in Humans ». Journal of Cognitive Neuroscience 31, no 12 (décembre 2019) : 1782–95. http://dx.doi.org/10.1162/jocn_a_01452.
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Tool use leads to plastic changes in sensorimotor body representations underlying tactile perception. The neural correlates of this tool-induced plasticity in humans have not been adequately characterized. This study used ERPs to investigate the stage of sensory processing modulated by tool use. Somatosensory evoked potentials, elicited by median nerve stimulation, were recorded before and after two forms of object interaction: tool use and hand use. Compared with baseline, tool use—but not use of the hand alone—modulated the amplitude of the P100. The P100 is a mid-latency component that indexes the construction of multisensory models of the body and has generators in secondary somatosensory and posterior parietal cortices. These results mark one of the first demonstrations of the neural correlates of tool-induced plasticity in humans and suggest that tool use modulates relatively late stages of somatosensory processing outside primary somatosensory cortex. This finding is consistent with what has been observed in tool-trained monkeys and suggests that the mechanisms underlying tool-induced plasticity have been preserved across primate evolution.
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Longo, Matthew R., et Andrea Serino. « Tool use induces complex and flexible plasticity of human body representations ». Behavioral and Brain Sciences 35, no 4 (15 juin 2012) : 229–30. http://dx.doi.org/10.1017/s0140525x11001907.
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AbstractPlasticity of body representation fundamentally underpins human tool use. Recent studies have demonstrated remarkably complex plasticity of body representation in humans, showing that such plasticity (1) occurs flexibly across multiple time scales and (2) involves multiple body representations responding differently to tool use. Such findings reveal remarkable sophistication of body plasticity in humans, suggesting that Vaesen may overestimate the similarity of such mechanisms in humans and non-human primates.
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Ferrara, Antonella, Mariachiara Rapuano et Gennaro Ruggiero. « Social Context and Tool Use Can Modulate Interpersonal Comfort Space ». Journal of Clinical Medicine 12, no 4 (18 février 2023) : 1647. http://dx.doi.org/10.3390/jcm12041647.
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Recent research has investigated whether the representation of space around the body, in terms of reach–action (imagining of reaching another person) and comfort–social (tolerance of the other’s proximity) spaces, may reflect a shared sensorimotor basis. Some studies exploiting motor plasticity induced by tool use have not observed sensorimotor identity (i.e., the same mechanisms that underlie, based on sensory information, the representation of proximal space in terms of action possibilities, goal-directed motor actions, and anticipation of the sensorimotor consequences), whereas evidence to the contrary has also emerged. Since the data are not fully convergent, here we wondered whether or not the combination of motor plasticity induced by tool use and the processing of the role of social context might reflect a similar modulation in both spaces. To this end, we conducted a randomized control trial with three groups of participants (N = 62) in which reaching and comfort distances were measured in Pre- and Post-tool-use sessions. The tool-use sessions were conducted under different conditions: (i) in the presence of a social stimulus (determining the social context) (Tool plus Mannequin group); (ii) without any stimulus (Only Tool group); (iii) in the presence of a box (Tool plus Object group) as a control condition. Results showed an extension of comfort distance in the Post-tool session of the Tool plus Mannequin group compared with the other conditions. Conversely, the reaching distance was larger after tool use than at the Pre-tool-use session, independently of the experimental conditions. Our findings suggest that motor plasticity impacts reaching and comfort spaces to different degrees; while reaching space is markedly sensitive to motor plasticity, comfort space needs qualification of social context information.
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Schaefer, Michael, Yvonne Rothemund, Hans-Jochen Heinze et Michael Rotte. « Short-term plasticity of the primary somatosensory cortex during tool use ». NeuroReport 15, no 8 (juin 2004) : 1293–97. http://dx.doi.org/10.1097/01.wnr.0000129573.36301.db.
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Martel, Marie, Lucilla Cardinali, Alice C. Roy et Alessandro Farnè. « Tool-use : An open window into body representation and its plasticity ». Cognitive Neuropsychology 33, no 1-2 (17 février 2016) : 82–101. http://dx.doi.org/10.1080/02643294.2016.1167678.
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Vaesen, Krist. « The cognitive bases of human tool use ». Behavioral and Brain Sciences 35, no 4 (15 juin 2012) : 203–18. http://dx.doi.org/10.1017/s0140525x11001452.
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AbstractThis article has two goals. The first is to assess, in the face of accruing reports on the ingenuity of great ape tool use, whether and in what sense human tool use still evidences unique, higher cognitive ability. To that effect, I offer a systematic comparison between humans and nonhuman primates with respect to nine cognitive capacities deemed crucial to tool use: enhanced hand-eye coordination, body schema plasticity, causal reasoning, function representation, executive control, social learning, teaching, social intelligence, and language. Since striking differences between humans and great apes stand firm in eight out of nine of these domains, I conclude that human tool use still marks a major cognitive discontinuity between us and our closest relatives. As a second goal of the paper, I address the evolution of human technologies. In particular, I show how the cognitive traits reviewed help to explain why technological accumulation evolved so markedly in humans, and so modestly in apes.
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Wang, Liyu, Luzius Brodbeck et Fumiya Iida. « Mechanics and energetics in tool manufacture and use : a synthetic approach ». Journal of The Royal Society Interface 11, no 100 (6 novembre 2014) : 20140827. http://dx.doi.org/10.1098/rsif.2014.0827.
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Tool manufacture and use are observed not only in humans but also in other animals such as mammals, birds and insects. Manufactured tools are used for biomechanical functions such as effective control of fluids and small solid objects and extension of reaching. These tools are passive and used with gravity and the animal users' own energy. From the perspective of evolutionary biology, manufactured tools are extended phenotypes of the genes of the animal and exhibit phenotypic plasticity. This incurs energetic cost of manufacture as compared to the case with a fixed tool. This paper studies mechanics and energetics aspects of tool manufacture and use in non-human beings. Firstly, it investigates possible mechanical mechanisms of the use of passive manufactured tools. Secondly, it formulates the energetic cost of manufacture and analyses when phenotypic plasticity benefits an animal tool maker and user. We take a synthetic approach and use a controlled physical model, i.e. a robot arm. The robot is capable of additively manufacturing scoop and gripper structures from thermoplastic adhesives to pick and place fluid and solid objects, mimicking primates and birds manufacturing tools for a similar function. We evaluate the effectiveness of tool use in pick-and-place and explain the mechanism for gripper tools picking up solid objects with a solid-mechanics model. We propose a way to formulate the energetic cost of tool manufacture that includes modes of addition and reshaping, and use it to analyse the case of scoop tools. Experiment results show that with a single motor trajectory, the robot was able to effectively pick and place water, rice grains, a pebble and a plastic box with a scoop tool or gripper tools that were manufactured by itself. They also show that by changing the dimension of scoop tools, the energetic cost of tool manufacture and use could be reduced. The work should also be interesting for engineers to design adaptive machines.
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Ferroni, Francesca, Vittorio Gallese, Agata Marta Soccini, Nunzio Langiulli, Francesca Rastelli, Donato Ferri, Francesco Bianchi et Martina Ardizzi. « The Remapping of Peripersonal Space in a Real but Not in a Virtual Environment ». Brain Sciences 12, no 9 (24 août 2022) : 1125. http://dx.doi.org/10.3390/brainsci12091125.
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One of the most surprising features of our brain is the fact that it is extremely plastic. Among the various plastic processes supported by our brain, there is the neural representation of the space surrounding our body, the peripersonal space (PPS). The effects of real-world tool use on the PPS are well known in cognitive neuroscience, but little is still known whether similar mechanisms also govern virtual tool use. To this purpose, the present study investigated the plasticity of the PPS before and after a real (Experiment 1) or virtual motor training with a tool (Experiment 2). The results show the expansion of the PPS only following real-world tool use but not virtual use, highlighting how the two types of training potentially rely on different processes. This study enriches the current state of the art on the plasticity of PPS in real and virtual environments. We discuss our data with respect to the relevance for the development of effective immersive environment for trainings, learning and rehabilitation.
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Sposito, Ambra, Nadia Bolognini, Giuseppe Vallar et Angelo Maravita. « Extension of perceived arm length following tool-use : Clues to plasticity of body metrics ». Neuropsychologia 50, no 9 (juillet 2012) : 2187–94. http://dx.doi.org/10.1016/j.neuropsychologia.2012.05.022.
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Galceran, M., A. Albou, K. Renard, M. Coulombier, P. J. Jacques et S. Godet. « Automatic Crystallographic Characterization in a Transmission Electron Microscope : Applications to Twinning Induced Plasticity Steels and Al Thin Films ». Microscopy and Microanalysis 19, no 3 (3 mai 2013) : 693–97. http://dx.doi.org/10.1017/s1431927613000445.
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AbstractA new automated crystallographic orientation mapping tool in a transmission electron microscope technique, which is based on pattern matching between every acquired electron diffraction pattern and precalculated templates, has been used for the microstructural characterization of nondeformed and deformed aluminum thin films and twinning-induced plasticity steels. The increased spatial resolution and the use of electron diffraction patterns rather than Kikuchi lines make this tool very appropriate to characterize fine grained and deformed microstructures.
Thèses sur le sujet "Tool-use and plasticity"
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Cardinali, Lucilla. « Body schema plasticity after tool-use ». Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00868427.
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We all have a body : our own body and just one body. Through it, we move, we interact with the world and other persons, we perceive, basically we live. It's a unique essential object. If it is true that we have only one physical body, we also have many representations of it in the brain. There is little agreement about the exact number of body representations in the brain, but not on the fact that we have more than one. The multi-componential models of body representation are based on the notion, supported by scientific evidence that different activities demand and rely on specifically adapted representations. In my thesis, I studied one particular body representation that is used and involved in action planning and execution, i.e. the Body Schema. I have been able to describe and measure the plasticity of the Body Schema and its level of specificity in healthy individuals. In particular, using a tool-use paradigm, I showed that the Body Schema is quickly and efficiently updated once a change in the body configuration occurs. With a series of kinematic studies, I contributed unveiling the ingredients that rule the plasticity of the BS and the sensory information that is used to this purpose. As a result of my thesis, I suggest that a clearer definition and operational description of the Body Schema, as an action-devoted repertoire of effectors representations, is possible, particularly thanks to its plastic features
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James, Andy Robert. « The use of pH-sensitive flourescent proteins to monitor real-time AMPA receptor trafficking : a potential tool for the visualisation of synaptic plasticity in the cerebellum ». Thesis, University College London (University of London), 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428011.
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SPOSITO, AMBRA VALENTINA. « The spatial metric representation of body parts : behavioural and neuropsychological evidence ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2011. http://hdl.handle.net/10281/20101.
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The mental representation of the body is being a subject of intensive research from different perspectives starting from the 20th Century. Indeed, the body is a peculiar object for the brain, being at the same time a physical, space-occupying object and the critical mean for perception and action in the world around us. The present doctoral work focussed on the spatial representation of the body; in particular it was investigated whether the body holds a specific metric representation, which is supposed to be useful for action programming and interaction with the environment, as introduced in Chapter 1. To this aim Experimental Part 1 (Chapter 2 and 3) investigated the stable properties of the body metrics, while Experimental Part 2 (Chapter 4) focussed on its plastic and dynamic features. Chapter 2 discusses the differences between the spatial metric representation of body parts and non bodily three-dimensional objects. In particular, Experiment 1 investigated the possibility that Unilateral Spatial Neglect (USN) may affect to a different extent the spatial analysis of body parts relative to extrapersonal three-dimensional objects. Participants were required to bisect their left forearm and a length-matched cylinder with their right index finger. Both USN patients and neurologically unimpaired participants showed a significantly more accurate estimation of the subjective midpoint of the forearm, relative to the solid object. Besides the main pattern of an advantage in the forearm bisection, a further analysis suggested the possibility of a double dissociation, with two patients exhibiting the opposite advantage in the solid bisection. Experiment 2, asking unimpaired volunteers to perform the same bisection task in three different conditions (Forearm, Fake Forearm, Cylinder), showed a similar kind of spatial analysis for stimuli displaying bodily features, either real or fake, relative to non-corporeal objects. Thus, it can be suggested that the spatial processing of body parts critically depends upon their prototypical visuo-spatial shape and that the spatial metrics of body parts, relatively to noncorporeal objects, is also more resistant to the disruption of spatial processing and representation brought about by USN. Chapter 3, starting from recent evidence showing how the body can be used as an intrinsic metric system for the representation of near space, illustrates how the length of extrapersonal objects can be scaled using the metric representation of body parts, and to what extent a higher-order metric representation of the body relays upon the somatosensory system. Experiment 3 showed, by means of a bisection task, that the spatial encoding of an extracorporeal object (i.e., a cylinder) may be facilitated by the presence of the forearm in that space –i.e. when the forearm was placed inside the cylinder- as if participants can unconsciously rely on its well known metric representation in order to better estimate the length of the cylinder. In Experiment 4 the same task was administered to a group of right-brain damaged patients, with or without somatosensory and proprioceptive defict, and to a matched control group. The results showed that the spatial metric representation of body parts might be distorted, or even not available, when the somatosensory sensitivity is altered by a cerebral lesion. Data about the plasticity of the metric representation of body parts are presented in Chapter 4. In this last group of experiments, blindfolded participants were required to perform a radial proprioceptive bisection of their forearm before and after a training with a tool, which allowed an extension of the action space in the far space. The results of Experiment 5 supported the working hypothesis that the arm metric representation can be changed by tool-use. In this experiment participants performed a radial bisection of their arm and indicated the subjective midpoint of their arm more distally after the training, suggesting that the perceived length of their own arm was increased. Interestingly, no effect was obtained following a training with a shorter tool (i.e., 20 cm long). Experiment 6 further supported this interpretation by showing, through a proprioceptive control task, that the dynamic lengthening induced in the metric representation of the arm was not due to a mere illusory distal drift of the whole arm. Furthermore, it demonstrated that the spatial metric representations of the dominant and the non-dominant arms share similar plastic features, being both equally prone to be modified by tool use. In conclusion this doctoral work showed that body size holds a mental representation that is very stable (even more than that of extrapersonal objects), but also characterized by flexible functional plasticity.
Chapitres de livres sur le sujet "Tool-use and plasticity"
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Romano, Daniele, et Angelo Maravita. « Plasticity and tool use in the body schema ». Dans Body Schema and Body Image, 117–32. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198851721.003.0008.
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The ability of humans to manufacture objects and represent physical causality makes them the master species in the use of tools. What is the impact of such a specific skill on the processing of bodily body-related spatial information? To what extent does the skilful manipulation of tools require specific embodiment of the device into one’s body representation? The present chapter reviews the effect of tool use on the representation of the body and space surrounding it, by analysing the cognitive effects of tool use and its neural representations. Studies on animals, healthy humans, and neuropsychological patients suggest that multisensory integration of stimuli far from the body is enhanced when a tool can reach those stimuli. Such a spatial remapping indicates that the body schema may adapt to include the device into one’s body representation. Notably, tool use-related changes are not limited to spatial processing, but also to the processing of body-related sensory-motor information. Understanding the cognitive mechanisms underlying tool use and the effect of tool use in the representation of the space around us is a paramount challenge to the understanding of body representation, especially considering that modern and more sophisticated technological tools, such as functional prostheses, robotic interfaces, and virtual reality devices, continually shape the central role of the body in human–environment interactions.
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Rubing, Anders. « Textile geographies, plasticity as protest ». Dans Protest Camps in International context. Policy Press, 2017. http://dx.doi.org/10.1332/policypress/9781447329411.003.0003.
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This chapter examines textile as a political tool and the architecture that facilitates this tool in protest camps by focusing on the use of textile rather than the form of protest. The author focuses on textile as a geopolitical agent and begins to compile a list of textile qualities as well as their spatial and geopolitical importance. The chapters draws from existing research on historic protest camps and the author’s empirical research from camps in Oslo, Norway and Silwan, East Jerusalem, Israel/Palestine. The author introduces Eyal Weizman’s term `political plastic´ as a framework to understand how architecture can create geopolitics. By combining Judith Butler’s argument of bodies creating politics in public spaces with Weizman’s theories, the chapter aims to create a new perspective for understanding the geopolitics of the protest camp.
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O’regan, J. Kevin. « Rewired Animals and Sensory Substitution : The Cause Is Not Cortical Plasticity ». Dans Sensory Substitution and Augmentation, sous la direction de Fiona Macpherson, 167–73. British Academy, 2018. http://dx.doi.org/10.5871/bacad/9780197266441.003.0010.
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Cortical plasticity is often invoked to explain changes in the quality or location of experience observed in rewired animals, in sensory substitution, in extension of the body through tool use, and in the rubber hand illusion. However this appeal to cortical plasticity may be misleading, because it suggests that the cortical areas that are plastic are themselves the loci of generation of experience. This would be an error, I claim, since cortical areas do not generate experience. Cortical areas participate in enabling the interaction of an agent with its environment, and the quality of this interaction constitutes the quality of experience. Thus it is not plasticity in itself, but the change in modes of interaction which plasticity allows, which gives rise to the change of experience observed in these studies.
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« Beyond the Boundaries of the Hand : Plasticity of Body–Space Interactions Following Tool Use ». Dans The Hand, an Organ of the Mind. The MIT Press, 2013. http://dx.doi.org/10.7551/mitpress/9083.003.0009.
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Keefer, Robert F. « Engineering Aspects of Soils ». Dans Handbook of Soils for Landscape Architects. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780195121025.003.0020.
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Although most landscape architects use soils primarily for growing plants, sometimes they need to know how engineers look at soils. Engineers are not concerned about soil properties that relate to growing plants. Engineers consider soil as a support for building foundations, use in earthworks, a place for burying pipes that carry electricity, water, gas or oil, and as a tool for disposing of hazardous, municipal, industrial, and household wastes. Soil properties that engineers consider important are hydraulic conductivity (permeability), compressive strength, shear strength, and lateral pressures. Soil mechanics deals with stress/strain/time relationships. Some engineering properties of a soil that describe the relation of clays to water content were studied by a Swedish scientist, Atterberg, in 1911. Soil clays based on water content were categorized into solid, semi-solid, plastic, and liquid. The dividing lines between each of these four states are known as the “Atterberg limits,” that is, shrinkage limit (from solid to semisolid), plastic limit (from semi-solid to plastic), and liquid limit (from plastic to liquid). These points can be measured for individual clays. The Atterberg limits are used by engineers to classify soils based on their moisture properties. These limits are particularly useful for evaluating soil compressibility, permeability, and strength. The plasticity of a clay soil depends on the type and amount of clay mineral and organic materials present. Plasticity is the reaction a soil has to being deformed without cracking or crumbling. The “liquid limit” is a term indicating the amount of water in a soil between the liquid state and the plastic state. Soils are first divided into two categories of coarse-grained and fine-grained. Coarse-grained soils are those in which more than half of the material is larger than a no. 200 sieve. Fine-grained soils are those in which more than half of the material is smaller than a no. 200 sieve. Coarse-grained soils are further divided into two categories of gravels and sands. Gravels are those with more than half of the coarse material larger than a no. 4 sieve. Sands are those with more than half of the coarse material smaller than a no. 4 sieve.
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Liu, Yu. « Resemioticization of Periodicity : A Social Semiotic Perspective ». Dans Mendeleev to Oganesson. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190668532.003.0012.
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Chemical periodicity is arguably one of the most important ideas in science, and it has profoundly influenced the development of both modern chemistry and physics (Scerri 1997, 229). While the definition of periodicity has remained largely stable in the past 150 years, the periodic system has been visualized in a wide range of forms including (to name just a few) tables, spirals, and zigzags. Furthermore, information technology makes it much easier, and offers innovative ways, to produce new versions of periodic depictions (e.g., WebElements (Winter 1993)). The multitude of periodic visualizations arouses growing interest among scholars with different academic backgrounds. For instance, educational researchers and practitioners (e.g., Waldrip et al. 2010) wrestle with the question of which visual representation will most effectively help students master the subject content of periodicity. Likewise, philosophers tend to identify the ultimate display of the periodic system, which they use as evidence to support a realistic view of periodicity (Scerri 2007, 21). Other researchers, however, take a different attitude toward the stunning diversity of periodic depictions. In a seminal paper, Marchese (2013) examines the visualization of periodicity at different stages of history from the perspectives of tabular, cartographic, and hypermedia design. His analysis illuminates the periodic table’s plasticity and endeavors to justify the constant transformation of the periodic displays as a necessary means to meet scientists’ changing needs. While all these studies generally emphasize the importance of periodic depictions in scientific research and education, they tend to give primacy to the notion of “periodic system.” By contrast, the periodic table seems to play a secondary role, which either passively reflects the chemical law or responds to the evolving knowledge of chemical elements. Such a view runs the risk of underestimating the significant function of the periodic table as a productive research tool, one which enabled Mendeleev to successfully predict the existence and the properties of undiscovered elements such as germanium in 1869 (Kibler 2007, 222). It is important to note that science and technology are “both material and semiotic practices” (Halliday 1998, 228, italics in original).
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Perry, Mary Jane. « Measurements of Phytoplankton Absorption Other Than Per Unit of Chlorophyll a ». Dans Ocean Optics. Oxford University Press, 1994. http://dx.doi.org/10.1093/oso/9780195068436.003.0010.
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Phytoplankton plays a critical role in determining light fields of the world’s oceans, primarily through absorption of light by photosynthetic pigments (see Chapters 1 to 5). Consequently there has been considerable interest from optical researchers in determining phytoplankton absorption. Conversely, from the biological point of view, this absorption assumes paramount importance because it is the sole source of energy for photosynthesis and thus should be central to direct estimates of primary production. There are two logical parts in determining this effect of phytoplankton and in estimating primary production. One is the estimation of abundance, and the other is estimation of specific effect or specific production rate. The earliest estimates of phytoplankton abundance were based on cell counts. From the time of Francis A. Richards’ Ph.D. dissertation, however, measurement of chlorophyll a concentration per unit of water volume, because of its relative ease, has assumed a central role in abundance estimation. Physiological studies and technological advances in optical instrumentation over the last decade lead me to question whether the continued use of chlorophyll a concentration to estimate phytoplankton abundance was wise either from the viewpoint of narrowing confidence intervals on estimates of absorption and production or from the viewpoint of mechanistic understanding of the processes involved. The measurement of chlorophyll a has become such a routine tool of biological oceanography, however, that the reasons for my heresy require elaboration. Some of the reasons are not too subtle. Chlorophyll a exists with other photosynthetic pigments in organized arrays associated with photosynthetic membranes. The function of these arrays is to harvest photons and transfer their energy to the specialized reaction center complexes that mediate photochemistry (see Chapter 9). The size of the arrays or packages and the ratio of chlorophyll a molecules to other light-harvesting pigments within the packages vary with phytoplankton cell size, total irradiance and its spectral distribution, as well as with other environmental parameters. It is well known that dark-adapted (= light-limited) cells increase their complements of photopigments. This plasticity in pigment packaging is evidenced in the variability of chlorophyll a-specific absorption coefficients. Simple optical models based only on chlorophyll a concentrations cannot be accurate or precise unless the effects of pigment packaging are considered.
Actes de conférences sur le sujet "Tool-use and plasticity"
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Gupta, Deepika, Anirudh Udupa et Koushik Viswanathan. « Some Quantitative Analogies Between Large-Strain Plasticity and Rectilinear Fluid Flow ». Dans ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8276.
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Abstract The mechanics of chip formation involves a complex interplay between surface plastic flow, material microstructure and tool-chip interface dynamics. At the continuum scale, this process has often been approximated as being one of pure shear along a very narrow zone — the shear plane. The primary assumption behind this approximation is that of steady or time-independent plastic flow. This approximation addresses the exception rather than the rule, since most metal cutting processes involve unsteady time-dependent plastic flows. In this work, we attempt to develop parallels with an analogous problem in fluid mechanics — flow past a rigid fixed body — to quantify the unsteady nature of plastic flow. Here the role of the body is played by the tool, and the flow field corresponds to the plastically deforming material. The prerequisite for fully exploiting this kinematic analogy is full-field material flow measurements. This is provided by digital image correlation (DIC), a family of techniques that use in situ imaging of the cutting process to obtain instantaneous full-field material displacements. Given this kinematic flow information, we show how one can describe the cutting process more accurately using the fluid flow analogy, and without having to resort to specific preconceived models. For steady flows, the analogy is more than merely cosmetic — the pathlines, streamlines and streaklines, all determined kinematically, coincide exactly. The analogy also allows consideration of time-dependent unsteady plastic flows that are usually beyond the purview of theoretical analyses. One can, for instance, ask the question of whether the transition from steady to unsteady plastic flow observed in metal cutting can be described by a dimensionless parameter, analogous to the Reynolds number for fluids. We show that in the case of unsteady flows, the actual deformation field is far removed from that described by conventional shear plane or slip line field models. Now the streaklines develop undulations or folds for the same boundary conditions as for the steady case (cutting velocity, depth of cut). Of the three flow lines, we attempt to extract information from streaklines, since they contain information about both spatial and temporal gradient. We present analyses of these streakline curvature features using simple geometric techniques that reflect both the spatial and temporal flow evolution. Our results shed light on the importance of considering unsteady flows in chip formation and machining. Borrowing ideas from fluids to describe these flows appears to hold significant promise for quantifying unsteady flows and their consequences for practical machining operations.
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Welo, Torgeir. « Design for Dimensional Accuracy in Bending Operations : Introducing the Concept of Flatness Limit Curves ». Dans ASME 2014 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/detc2014-34740.
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Eliciting knowledge about dimensional variability and influential parameters is crucial in competitive manufacturing. Moreover, this knowledge needs to be generalized and transferred into a practical tool box that design engineers can use as a decision basis in the early phases of product development processes when design flexibility is high and the ‘cost of learning’ is low. This paper introduces Flatness Limit Curves, a new Design For Manufacturing (DFM) tool, which is aimed at assessing cross-sectional distortions relative to dimensional tolerance requirements in bending operation. Analytical relationships are derived from the theoretical basis of continuum mechanics, applying the deformation theory of plasticity to plane stress sheet metal problems. The theoretical results are compared with experimental results obtained for hollow AA7xxx extrusions, which were formed in an industry-like rotary stretch bender in a controlled laboratory environment. The solutions are then structured and organized into a set of limit curves for assessing nominal flatness of the exterior of the cross section after bending. The associated variability may also be estimated by varying key input parameters to the tool (dimensional accuracy and material quality) within the capability ranges of the upstream process.
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Kim, Gap-Yong, Muammer Koc et Jun Ni. « Modeling of Size Effects on the Flow Stress of Type 304 Stainless Steel and Application in Coining Process ». Dans ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41971.
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Application of microforming in various research areas has received much attention due to the increased demand for miniature metallic parts that require mass production. For the accurate analysis and design of microforming process, proper modeling of material behavior at the micro/meso-scale is necessary by considering the size effects. Two size effects are known to exist in metallic materials. One is the “grain size” effect, and the other is the “feature/specimen size” effect. This study investigated the “feature/specimen size” effect and introduced a scaling model which combined both feature/specimen and grain size effects. Predicted size effects were compared with experiments obtained from previous research and showed a very good agreement. The model was also applied to forming of micro-features by coining. A flow stress model for Type 304 stainless steel taking into consideration the effect of the grain and feature size was developed and implemented into a finite element simulation tool for an accurate numerical analysis. The scaling model offered a simple way to model the size effect down to length scales of a couple of grains and extended the use of continuum plasticity theories to micro/meso-length scales.
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Londono, Juan G., Mostafa E. Mobasher et Pawel Woelke. « A Fracture Characterization Framework for Large-Scale Marine Metal Structures ». Dans ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-18952.
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Abstract Prediction of large-scale marine structures under extreme loading conditions (e.g. impact, fire) requires the use of computational tools that are both accurate and efficient. To resolve models at this scale, engineers normally use shell elements in which two of the (in-plane) dimensions are much larger than the third (thickness) one. Herein, we propose a consistent characterization framework for shell-element models commonly used in metal marine structures. The underlying model is based on a three stress-invariant plasticity model that accounts for the effects of stress triaxiality and shear-dominated stress states and accounts for the micromechanical void growth and coalescence that leads to fracture. This framework serves as both a constitutive model as well as a back-end calibration engine which outputs material cards that can be readily used with commercial finite element solvers like LS-DYNA and Abaqus. The calibration framework supports data-driven constitutive models that require engineers to prescribe the Fracture Locus (FL) and Instability Curves (IC) from experimental data, such as the Johnson-Cook model. Moreover, the calibration framework uses the underlying physics based model to computationally generate additional surrogate data that compliments the experimental testing. Thus, it allows the analyst to calibrate a material model based on limited experimental data, hence, reducing the costs associated with data acquisition and processing. A standalone calibration tool (VistaCal) that highlights the benefits of this characterization framework is also presented.
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Lortz, Wolfgang, et Radu Pavel. « Advanced Modeling of Drilling – Realistic Process Mechanics Leading to Helical Chip Formation ». Dans ASME 2021 16th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/msec2021-63790.
Texte intégralRésumé :
Abstract There is considerable interest in the “Industry 4.0 project”. Industry hopes that a general solution of the metal removal problem will be found through the use of highly automated manufacturing data. Scientists hope that the computer will provide better models based on artificial intelligence and machine learning. Initial attempts leveraging existing models did not result in satisfactory results yet — largely because of mathematical, physical and metallurgical reasons. This paper presents a new mathematical-physical model to describe the total process mechanics from volume conservation, to friction, to metal plasticity with self-hardening or softening effects and dynamic phenomena during metal plastic flow. The softening effects are created by high energy corresponding to high strain-rate resulting in high temperatures. Furthermore, the developed equations for strain-rate discontinuities as well as yield shear stress with body forces have an interdependent relationship and lead to plastic deformation with dynamic behavior in the total chip formation zone. This plastic deformation is the only parameter that will not disappear after completing the process. This leads to the opportunity to check the theoretically developed grid deformation and compare it with practical results of the same area. In this publication this new theory will be used to analyze the complex contact and friction conditions between the chip and tool edge of a twist drill during operation. It will be shown that the existing conditions are leading to high wear at the corner edge and flank wear at the tool cutting edge. In addition, the existing temperatures can be estimated and compared with practical measurements, and all these complex and difficult conditions create a helical spiral chip, which could be developed as it will be presented in this paper.
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Hartl, Darren, Tyler Zimmerman, Matthew Dilligan, James Mabe et Frederick Calkins. « Analysis of Shape Memory Alloy Components Using Beam, Shell, and Continuum Finite Elements ». Dans ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2010. http://dx.doi.org/10.1115/smasis2010-3833.
Texte intégralRésumé :
This work discusses the increased capabilities of a three-dimensional analysis tool for shape memory alloy engineering components. As the number and complexity of proposed SMA applications increases, engineers and designers must seek out or develop more capable predictive methods. Three-dimensional models implemented in a continuum finite element analysis (FEA) framework can be applied to most SMA component geometries. However, such methods may require fine meshes in 3-D space, resulting in many degrees of freedom and potentially long analysis times. On the other hand, constitutive models implemented in one dimension can be simple and fast, but are restricted to a limited class of problems for which such reductions are appropriate (e.g., rods and beams). More recently, engineers have begun investigating more complex SMA bending components for which 2-D shell elements might provide a computationally efficient FEA discretization. Here we consider a single modeling tool (a material subroutine) that combines 1-D, 2-D, and 3-D implementations for use in a general FEA framework. As an example analysis case, we consider an SMA bending element that has been adhesively bonded to a carbon fiber-reinforced polymer (CFRP) laminate and is subjected to thermally-induced actuation. The active SMA and passive composite components are bonded in a pre-stressed configuration such that the elastic laminate provides a variable restoring force to the SMA during transformation, resulting in repeatable actuation cycles. This two-part bonded configuration is analyzed using different types of finite elements (1-D beam, 2-D shell, and full 3-D continuum elements). The constitutive behavior of the shape memory alloy is defined using an established three-dimensional model based on continuum thermodynamics and motivated by the methods of classical plasticity. A user material subroutine (UMAT) in an Abaqus Unified FEA framework is used to implement the model. The methodology for capturing 1-D, 2-D, and 3-D thermomechanical response in a single such UMAT is described. The run times of the various analyses are compared, and the relative accuracies of the results are discussed.
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Youssef, Bassem S., Mark J. Cassidy et Yinghui Tian. « Probabilistic Model Application in the Integrated Stability Analysis of Offshore On-Bottom Pipeline ». Dans ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-50047.
Texte intégralRésumé :
Offshore pipelines provide the main link between offshore oil and gas fields and hydrocarbon development onshore. Due to their economical installation, untrenched pipelines laid “on-bottom” are finding increased popularity over other types of offshore pipelines. However, the stability of untrenched pipeline design remains the subject of criticism. In many cases around the world, severe loading conditions, such as those during hurricanes, result in severe pipeline damage and disruption of oil and gas supply. In on-bottom pipeline stability analysis, hydrodynamic loads are applied to the pipe structure. The pipe passes these loads onto the supporting soil along its length. A variety of parameters need to be defined to model this loading scenario and to reflect the complicated interaction between the hydrodynamic load, pipe structure and the supporting soil. Moreover, there are uncertainties regarding the input values of these parameters, as any difference in these parameter values will result in a considerable difference in the final pipeline stability result (though the sensitivity to any differences is not well studied). In this study of the offshore pipeline stability, the hydrodynamic loads are estimated using Fourier analysis, which is currently the best practice in hydrodynamic modeling. The pipe-soil interaction is simulated with a force-resultant model, which is derived from a plasticity framework and is based on the results of centrifuge test calibration. The pipeline is modeled using an integrated numerical modeling tool developed by implementing the hydrodynamic load model and force-resultant model codes in the finite element package ABAQUS. Use of the integrated modeling tool allows for the coupling effect of the hydrodynamic-pipe-soil interaction to be accounted for, with the added ability to modify the applied hydrodynamic loads due to pipe movements during the analysis. The main aims of this paper are to demonstrate methods to estimate the probability of exceeding pipeline stability and quantify the importance of the on-bottom pipeline statistical analysis and the sensitivity of the parameters included in the pipeline stability design. After first describing the integrated model and providing an illustrative example of its use these aims are achieved by i) performing probabilistic analysis for a typical pipeline case and investigating the probability of exceeding pipeline stability under different maximum pipeline displacement values; and ii) developing a sensitivity analysis of the input parameters included in the on-bottom pipeline stability and ranking these parameters according to their sensitivity to the pipeline stability design.