The nonlinear mechanics of a flexible elastic rod constrained at its edges by a pair of sliding sleeves is analyzed. The planar equilibrium configurations of this variable-length elastica are found to have shape defined only by the inclination of the two constraints, while their distance is responsible only for scaling the size. By extending the theoretical stability criterion available for systems under isoperimetric constraints to the case of variable domains, the existence of no more than one stable equilibrium solution is revealed. The set of sliding sleeves' inclination pairs for which the stability is lost are identified. Such critical conditions allow the indefinite ejection of the flexible rod from the sliding sleeves, thus realizing an elastica sling. Finally, the theoretical findings are validated by experiments on a physical prototype. The present results lead to a novel actuation principle that may find application as a mechanism in energy harvesting, wave mitigation devices, and soft robotic locomotion.
{"title":"The elastica sling","authors":"Alessandro Cazzolli, Francesco Dal Corso","doi":"arxiv-2409.12075","DOIUrl":"https://doi.org/arxiv-2409.12075","url":null,"abstract":"The nonlinear mechanics of a flexible elastic rod constrained at its edges by\u0000a pair of sliding sleeves is analyzed. The planar equilibrium configurations of\u0000this variable-length elastica are found to have shape defined only by the\u0000inclination of the two constraints, while their distance is responsible only\u0000for scaling the size. By extending the theoretical stability criterion\u0000available for systems under isoperimetric constraints to the case of variable\u0000domains, the existence of no more than one stable equilibrium solution is\u0000revealed. The set of sliding sleeves' inclination pairs for which the stability\u0000is lost are identified. Such critical conditions allow the indefinite ejection\u0000of the flexible rod from the sliding sleeves, thus realizing an elastica sling.\u0000Finally, the theoretical findings are validated by experiments on a physical\u0000prototype. The present results lead to a novel actuation principle that may\u0000find application as a mechanism in energy harvesting, wave mitigation devices,\u0000and soft robotic locomotion.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We studied an interesting experiment that showed a half-buried chopstick lifting a full bottle of granules off the table. In Janssen theory, the friction force provided by the container wall helps alleviate the weight of the granules. How can a thin rod with a much less contact area support the full weight plus that of the container? Insights are gained by allowing the friction on the wall to change direction before solving the Janssen equation. We obtained the analytic expression for the critical depth of granules that enables a successful lift off. In addition, we established that the stick and slip phenomenon exists during a failed lift off by analyzing the frequency of fluctuations in the pull force. Finally, a photoelasticity experiment was employed to directly visualize the stress field sensitive to the pull force, and verify the directional change of friction force from the wall.
{"title":"Lifting a granular box by a half-buried rod","authors":"Ting-Heng Hsieh, Tzay-Ming Hong","doi":"arxiv-2409.11957","DOIUrl":"https://doi.org/arxiv-2409.11957","url":null,"abstract":"We studied an interesting experiment that showed a half-buried chopstick\u0000lifting a full bottle of granules off the table. In Janssen theory, the\u0000friction force provided by the container wall helps alleviate the weight of the\u0000granules. How can a thin rod with a much less contact area support the full\u0000weight plus that of the container? Insights are gained by allowing the friction\u0000on the wall to change direction before solving the Janssen equation. We\u0000obtained the analytic expression for the critical depth of granules that\u0000enables a successful lift off. In addition, we established that the stick and\u0000slip phenomenon exists during a failed lift off by analyzing the frequency of\u0000fluctuations in the pull force. Finally, a photoelasticity experiment was\u0000employed to directly visualize the stress field sensitive to the pull force,\u0000and verify the directional change of friction force from the wall.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"78 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Self-avoiding walk (SAW) represents linear polymer chain on a large scale, neglecting its chemical details and emphasizing the role of its conformational statistics. The role of the latter is important in formation of agglomerates and complexes involving polymers and organic or inorganic particles, such as polymer-stabilized colloidal suspensions, microemulsions, or micellar solutions. When such particles can be adsorbed on a polymer of considerably larger dimensions than themselves, this setup may represent chelation of heavy metal ions by polymeric chelants. We consider the SAW of the length $N$ on a cubic lattice ridden by randomly distributed obstacles of the concentration $p$ interpreted as ions. The SAW monomers can bind to the obstacles with variable binding energy $varepsilon$ mimicking formation of the chelation bond. Pruned-enriched Rosenbluth method (PERM) Monte Carlo (MC) algorithm is applied to simulate system behaviour. We focus on several relevant properties related to the chelation efficiency and strength, as functions of the variables set ${p,N,varepsilon}$. The results are interpreted in terms of conformational freedom, excluded volume effects and loop formation for the SAW, and the tendencies being predicted are in agreement with some experimental data.
{"title":"Mapping self-avoiding walk on obstacle-ridden lattice onto chelation of heavy metal ions: Monte Carlo study","authors":"V. Blavatska, Ja. Ilnytskyi, E. Lähderanta","doi":"arxiv-2409.10974","DOIUrl":"https://doi.org/arxiv-2409.10974","url":null,"abstract":"Self-avoiding walk (SAW) represents linear polymer chain on a large scale,\u0000neglecting its chemical details and emphasizing the role of its conformational\u0000statistics. The role of the latter is important in formation of agglomerates\u0000and complexes involving polymers and organic or inorganic particles, such as\u0000polymer-stabilized colloidal suspensions, microemulsions, or micellar\u0000solutions. When such particles can be adsorbed on a polymer of considerably\u0000larger dimensions than themselves, this setup may represent chelation of heavy\u0000metal ions by polymeric chelants. We consider the SAW of the length $N$ on a\u0000cubic lattice ridden by randomly distributed obstacles of the concentration $p$\u0000interpreted as ions. The SAW monomers can bind to the obstacles with variable\u0000binding energy $varepsilon$ mimicking formation of the chelation bond.\u0000Pruned-enriched Rosenbluth method (PERM) Monte Carlo (MC) algorithm is applied\u0000to simulate system behaviour. We focus on several relevant properties related\u0000to the chelation efficiency and strength, as functions of the variables set\u0000${p,N,varepsilon}$. The results are interpreted in terms of conformational\u0000freedom, excluded volume effects and loop formation for the SAW, and the\u0000tendencies being predicted are in agreement with some experimental data.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"188 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The elusive presence of an anomalously increasing screening length at high ionic concentrations hampers a complete picture of interactions in electrolytes. Theories which extend the diluted Debye-Huckel framework to higher concentrations predict, in addition to the expected decreasing Debye length, an increasing significant scale of the order of at most a few ionic diameters. More recent surface force balance experiments with different materials succeeded in measuring increasing length scales which, however, turn out to extend over tenths or even hundreds of ionic diameters. While simulation work has managed to characterize the former, the latter still avoid detection, generating doubts about its true origin. Here we provide a step forward in the clarification of such a conundrum. We have studied by extensive Molecular Dynamics simulation the properties of a generic model of electrolyte, lithium tetrafluoroborate dissolved in ethylene-carbonate, in a vast range of salt concentrations continuously joining the Debye non-interacting limit to the opposite over-charged ionic liquid-like states. On one side, we have accurately determined the macroscopic concentration-induced structural, dielectric and transport modifications, on the other we have quantified the resulting nano-scale ions organization. Based only on the simulation data, without resorting to any uncontrolled hypothesis or phenomenological parameter, we identify a convincing candidate for the measured anomalously increasing length, whose origin has been possibly misinterpreted.
{"title":"Length scales in electrolytes","authors":"Ioannis Skarmoutsos, Stefano Mossa","doi":"arxiv-2409.11179","DOIUrl":"https://doi.org/arxiv-2409.11179","url":null,"abstract":"The elusive presence of an anomalously increasing screening length at high\u0000ionic concentrations hampers a complete picture of interactions in\u0000electrolytes. Theories which extend the diluted Debye-Huckel framework to\u0000higher concentrations predict, in addition to the expected decreasing Debye\u0000length, an increasing significant scale of the order of at most a few ionic\u0000diameters. More recent surface force balance experiments with different\u0000materials succeeded in measuring increasing length scales which, however, turn\u0000out to extend over tenths or even hundreds of ionic diameters. While simulation\u0000work has managed to characterize the former, the latter still avoid detection,\u0000generating doubts about its true origin. Here we provide a step forward in the\u0000clarification of such a conundrum. We have studied by extensive Molecular\u0000Dynamics simulation the properties of a generic model of electrolyte, lithium\u0000tetrafluoroborate dissolved in ethylene-carbonate, in a vast range of salt\u0000concentrations continuously joining the Debye non-interacting limit to the\u0000opposite over-charged ionic liquid-like states. On one side, we have accurately\u0000determined the macroscopic concentration-induced structural, dielectric and\u0000transport modifications, on the other we have quantified the resulting\u0000nano-scale ions organization. Based only on the simulation data, without\u0000resorting to any uncontrolled hypothesis or phenomenological parameter, we\u0000identify a convincing candidate for the measured anomalously increasing length,\u0000whose origin has been possibly misinterpreted.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The absence of a well-defined equilibrium reference configuration and the inevitable frequent atomic rearrangements have long obstructed the achievement of a complete atomic-level understanding of liquid dynamics and properties, a challenge that continues to be unresolved. The instantaneous normal mode (INM) approach, based on the diagonalization of the potential energy Hessian matrix in instantaneous liquid configurations, has been shown to be a promising starting point to predict thermodynamic and dynamical properties of liquids but presents several conceptual difficulties that remain to be addressed. More in general, due to the inability of capturing anharmonic effects, what INMs can tell us about liquid dynamics remains an open question. In this work, we provide a general set of ``experimental facts'' by performing a comprehensive INM analysis of several simulated systems, including Ar, Xe, N$_2$, CS$_2$, Ga and Pb, in a large range of temperatures from the solid to the gas phase. We first study the INM density of states (DOS) and compare it to the density of state function obtained from the velocity auto-correlation function. Secondly, we analyze the temperature dependence of the fraction of unstable modes and of the low-frequency slope of the INM DOS, in search of possible universal behaviors. We then explore the connection between INMs and other properties of liquids including the liquid-like to gas-like dynamical crossover and the momentum gap of collective shear waves. Moreover, we investigate the INM spectrum at low temperature upon approaching the solid phase, revealing the existence of a large fraction of unstable modes also in crystalline solids. Finally, we verify the existence of a recently discussed cusp-like singularity in the INM eigenvalue spectrum and reveal its complex behavior upon dialing temperature that challenges the existing theoretical models.
{"title":"Revisiting the question of what instantaneous normal modes tell us about liquid dynamics","authors":"Sha Jin, Xue Fan, Matteo Baggioli","doi":"arxiv-2409.09965","DOIUrl":"https://doi.org/arxiv-2409.09965","url":null,"abstract":"The absence of a well-defined equilibrium reference configuration and the\u0000inevitable frequent atomic rearrangements have long obstructed the achievement\u0000of a complete atomic-level understanding of liquid dynamics and properties, a\u0000challenge that continues to be unresolved. The instantaneous normal mode (INM)\u0000approach, based on the diagonalization of the potential energy Hessian matrix\u0000in instantaneous liquid configurations, has been shown to be a promising\u0000starting point to predict thermodynamic and dynamical properties of liquids but\u0000presents several conceptual difficulties that remain to be addressed. More in\u0000general, due to the inability of capturing anharmonic effects, what INMs can\u0000tell us about liquid dynamics remains an open question. In this work, we\u0000provide a general set of ``experimental facts'' by performing a comprehensive\u0000INM analysis of several simulated systems, including Ar, Xe, N$_2$, CS$_2$, Ga\u0000and Pb, in a large range of temperatures from the solid to the gas phase. We\u0000first study the INM density of states (DOS) and compare it to the density of\u0000state function obtained from the velocity auto-correlation function. Secondly,\u0000we analyze the temperature dependence of the fraction of unstable modes and of\u0000the low-frequency slope of the INM DOS, in search of possible universal\u0000behaviors. We then explore the connection between INMs and other properties of\u0000liquids including the liquid-like to gas-like dynamical crossover and the\u0000momentum gap of collective shear waves. Moreover, we investigate the INM\u0000spectrum at low temperature upon approaching the solid phase, revealing the\u0000existence of a large fraction of unstable modes also in crystalline solids.\u0000Finally, we verify the existence of a recently discussed cusp-like singularity\u0000in the INM eigenvalue spectrum and reveal its complex behavior upon dialing\u0000temperature that challenges the existing theoretical models.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"43 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dry friction has been proposed as a rectifying mechanism allowing mass transport over a vibrating surface, even when vibrations are horizontal and unbiased. It has been suggested that the drift velocity will always saturate when the energy of the input oscillation increases, leading to a vanishing efficiency that would hinder the applicability of this phenomenon. Contrary to this conjecture, in this work we experimentally demonstrate that, by carefully controlling the forcing oscillations, this system can maintain a finite transport efficiency for any input energy. A minimal friction model explains the observed dependencies of the drift velocity on the signal parameters in the case of biharmonic base oscillations, which can be extended to obtain efficiency estimates for any periodic excitation.
{"title":"Efficient transport controlled by biharmonic frictional driving","authors":"Martin Maza-Cuello, Diego Maza","doi":"arxiv-2409.10285","DOIUrl":"https://doi.org/arxiv-2409.10285","url":null,"abstract":"Dry friction has been proposed as a rectifying mechanism allowing mass\u0000transport over a vibrating surface, even when vibrations are horizontal and\u0000unbiased. It has been suggested that the drift velocity will always saturate\u0000when the energy of the input oscillation increases, leading to a vanishing\u0000efficiency that would hinder the applicability of this phenomenon. Contrary to\u0000this conjecture, in this work we experimentally demonstrate that, by carefully\u0000controlling the forcing oscillations, this system can maintain a finite\u0000transport efficiency for any input energy. A minimal friction model explains\u0000the observed dependencies of the drift velocity on the signal parameters in the\u0000case of biharmonic base oscillations, which can be extended to obtain\u0000efficiency estimates for any periodic excitation.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sakineh Mizani, Martin Oettel, Péter Gurin, Szabolcs Varga
We study equilibrium states and phases of a quasi-one-dimensional system of hard superdisks (anisotropic particles interpolating between disks and squares) where the centers of the particles are constrained to move on a line. A continuous change from a quasi-isotropic to a tetratic phase is found upon increasing the density. Somewhat unexpected, for isobaric states, systems with larger and more anisotropic particles in the tetratic phase are denser than systems with smaller and less anisotropic particles in a quasi-isotropic phase. Close packing behaviour is characterised by exponents describing the behaviour of the pressure, the angular fluctuations and the angular correlation length. We obtain two universal, shape-independent relations between them.
{"title":"Universality of the close packing properties and markers of isotropic-to-tetratic phase change in quasi-one-dimensional superdisk fluid","authors":"Sakineh Mizani, Martin Oettel, Péter Gurin, Szabolcs Varga","doi":"arxiv-2409.10742","DOIUrl":"https://doi.org/arxiv-2409.10742","url":null,"abstract":"We study equilibrium states and phases of a quasi-one-dimensional system of\u0000hard superdisks (anisotropic particles interpolating between disks and squares)\u0000where the centers of the particles are constrained to move on a line. A\u0000continuous change from a quasi-isotropic to a tetratic phase is found upon\u0000increasing the density. Somewhat unexpected, for isobaric states, systems with\u0000larger and more anisotropic particles in the tetratic phase are denser than\u0000systems with smaller and less anisotropic particles in a quasi-isotropic phase.\u0000Close packing behaviour is characterised by exponents describing the behaviour\u0000of the pressure, the angular fluctuations and the angular correlation length.\u0000We obtain two universal, shape-independent relations between them.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"54 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The recent experimental discovery of ferroelectric and splay nematic phases has sparked interest in comprehending the crucial molecular features necessary to stabilize these innovative structures. This study advances the ongoing discourse by investigating the significance of both molecular elongation and the distribution of molecular dipoles along the main molecular axis. Using Density Functional Theory, we have established that a molecular shape characterized by cylindrical symmetry and the presence of strong parallel dipoles along the symmetry axis can lead to the self-assembly of a ferroelectric nematic, which is more stable than the conventional uniaxial nematic phase. Additionally, we provide criteria for achieving an optimal dipole distribution along the molecular axis.
{"title":"Ferroelectric nematic phase in the system of perfectly aligned cyllindrically symmetric rods","authors":"Agnieszka Chrzanowska, Lech Longa","doi":"arxiv-2409.09851","DOIUrl":"https://doi.org/arxiv-2409.09851","url":null,"abstract":"The recent experimental discovery of ferroelectric and splay nematic phases\u0000has sparked interest in comprehending the crucial molecular features necessary\u0000to stabilize these innovative structures. This study advances the ongoing\u0000discourse by investigating the significance of both molecular elongation and\u0000the distribution of molecular dipoles along the main molecular axis. Using\u0000Density Functional Theory, we have established that a molecular shape\u0000characterized by cylindrical symmetry and the presence of strong parallel\u0000dipoles along the symmetry axis can lead to the self-assembly of a\u0000ferroelectric nematic, which is more stable than the conventional uniaxial\u0000nematic phase. Additionally, we provide criteria for achieving an optimal\u0000dipole distribution along the molecular axis.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Israrul H. Hashmi, Himanshu, Rahul Karmakar, Tarak K Patra
Machine learning models have been progressively used for predicting materials properties. These models can be built using pre-existing data and are useful for rapidly screening the physicochemical space of a material, which is astronomically large. However, ML models are inherently interpolative, and their efficacy for searching candidates outside a material's known range of property is unresolved. Moreover, the performance of an ML model is intricately connected to its learning strategy and the volume of training data. Here, we determine the relationship between the extrapolation ability of an ML model, the size and range of its training dataset, and its learning approach. We focus on a canonical problem of predicting the properties of a copolymer as a function of the sequence of its monomers. Tree search algorithms, which learn the similarity between polymer structures, are found to be inefficient for extrapolation. Conversely, the extrapolation capability of neural networks and XGBoost models, which attempt to learn the underlying functional correlation between the structure and property of polymers, show strong correlations with the volume and range of training data. These findings have important implications on ML-based new material development.
机器学习模型已逐渐被用于预测材料特性。这些模型可以利用已有数据建立，可用于快速筛选材料的物理化学空间，而这一空间在经济上是巨大的。然而，ML 模型本质上是内插模型，其在材料已知性能范围之外搜索候选材料的功效尚未得到解决。此外，ML 模型的性能与其学习策略和训练数据量密切相关。在此，我们将确定 ML 模型的外推能力、训练数据集的大小和范围与其学习方法之间的关系。我们将重点放在一个典型问题上，即根据单体序列预测共聚物的性质。树状搜索算法可以学习聚合物结构之间的相似性，但外推法的效率很低。相反，神经网络和 XGBoost 模型的外推能力与训练数据的数量和范围有很强的相关性。这些发现对基于 ML 的新材料开发具有重要意义。
{"title":"Extrapolative ML Models for Copolymers","authors":"Israrul H. Hashmi, Himanshu, Rahul Karmakar, Tarak K Patra","doi":"arxiv-2409.09691","DOIUrl":"https://doi.org/arxiv-2409.09691","url":null,"abstract":"Machine learning models have been progressively used for predicting materials\u0000properties. These models can be built using pre-existing data and are useful\u0000for rapidly screening the physicochemical space of a material, which is\u0000astronomically large. However, ML models are inherently interpolative, and\u0000their efficacy for searching candidates outside a material's known range of\u0000property is unresolved. Moreover, the performance of an ML model is intricately\u0000connected to its learning strategy and the volume of training data. Here, we\u0000determine the relationship between the extrapolation ability of an ML model,\u0000the size and range of its training dataset, and its learning approach. We focus\u0000on a canonical problem of predicting the properties of a copolymer as a\u0000function of the sequence of its monomers. Tree search algorithms, which learn\u0000the similarity between polymer structures, are found to be inefficient for\u0000extrapolation. Conversely, the extrapolation capability of neural networks and\u0000XGBoost models, which attempt to learn the underlying functional correlation\u0000between the structure and property of polymers, show strong correlations with\u0000the volume and range of training data. These findings have important\u0000implications on ML-based new material development.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Guilherme N. C. Amaral, Hanqing Zhao, Mahmoud Sedahmed, Tomás Campante, Ivan I. Smalyukh, Mykola Tasinkevych, Margarida M. Telo da Gama, Rodrigo C. V. Coelho
Three-dimensional (3D) simulations of the structure of liquid crystal (LC) torons, topologically protected distortions of the LC director field, under material flows are rare but essential in microfluidic applications. Here, we show that torons adopt a steady-state configuration at low flow velocity before disintegrating at higher velocities, in line with experimental results. Furthermore, we show that under partial slip conditions at the boundaries, the flow induces a reversible elongation of the torons, also consistent with the experimental observations. These results are in contrast with previous simulation results for 2D skyrmions under similar flow conditions, highlighting the need for a 3D description of this LC soliton in relation to its coupling to the material flow. These findings pave the way for future studies of other topological solitons, like hopfions and heliknotons, in flowing soft matter systems.
{"title":"Liquid crystal torons in Poiseuille-like flows","authors":"Guilherme N. C. Amaral, Hanqing Zhao, Mahmoud Sedahmed, Tomás Campante, Ivan I. Smalyukh, Mykola Tasinkevych, Margarida M. Telo da Gama, Rodrigo C. V. Coelho","doi":"arxiv-2409.09486","DOIUrl":"https://doi.org/arxiv-2409.09486","url":null,"abstract":"Three-dimensional (3D) simulations of the structure of liquid crystal (LC)\u0000torons, topologically protected distortions of the LC director field, under\u0000material flows are rare but essential in microfluidic applications. Here, we\u0000show that torons adopt a steady-state configuration at low flow velocity before\u0000disintegrating at higher velocities, in line with experimental results.\u0000Furthermore, we show that under partial slip conditions at the boundaries, the\u0000flow induces a reversible elongation of the torons, also consistent with the\u0000experimental observations. These results are in contrast with previous\u0000simulation results for 2D skyrmions under similar flow conditions, highlighting\u0000the need for a 3D description of this LC soliton in relation to its coupling to\u0000the material flow. These findings pave the way for future studies of other\u0000topological solitons, like hopfions and heliknotons, in flowing soft matter\u0000systems.","PeriodicalId":501146,"journal":{"name":"arXiv - PHYS - Soft Condensed Matter","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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