Mobility, interactions, and order in active granular systems

非技术摘要：凝聚态物理学从细菌、昆虫、鱼类、鸟类和迁徙哺乳动物等生物的运动中汲取灵感，创造了活性材料的新领域。与原子或分子从热源获得能量以随机、无方向的方式四处移动不同，许多生物消耗能量以沿着一个优选的身体轴移动，导致不寻常的集体行为，如集群、群集和群集。在这项研究中，将在由振动激发的毫米级颗粒组成的实验室系统中进行实验，以模拟其中的一些现象。超越生物学动机，研究小组将创造出以设计方式移动的颗粒，以操纵和组装材料。 通过这项研究，研究生和本科生都将接触到软凝聚态物理学的各种技术和前沿领域，并被介绍给具有工业相关性的问题。 PI通过继续在马萨诸塞大学阿默斯特分校组织题为“软固体和复杂流体”的年度暑期学校，为大学以外的研究生教育做出贡献。 PI还有助于运行一个名为Patterns Around Us.Technical Abstract的初中和高中教师年度计划：活性物质是一个新的非平衡统计力学竞技场，灵感来自于从细菌到昆虫，鱼类，鸟类和迁徙哺乳动物的能动系统中观察到的集体行为。在这个项目中，研究团队将超越仿生动机，明确地抛开生物设计的限制和意图，创造出“活性”颗粒，可以赋予新的材料功能和对颗粒组装体的反应。具体的目标是认识和利用这样一个事实，即单个单元的运动对称性可以完全不同于与其他单元相互作用的对称性。该团队建议开展实验，研究振动颗粒的集体力学，这些颗粒纠正噪音以产生定向运动。他们有两个平行的目标：（i）探索活动物质统计物理学中的新问题，（ii）开发操纵和组装宏观物质的方法。这项计划的主要目标是对许多类活性粒子的相图进行全面的实验研究，以便阐明活性如何促进或破坏特定种类的有序。通过这项研究，研究生和本科生都将接触到软凝聚态物理学的各种技术和前沿领域，并被介绍给具有工业相关性的问题。 PI通过继续在马萨诸塞大学阿默斯特分校组织题为“软固体和复杂流体”的年度暑期学校，为大学以外的研究生教育做出贡献。 PI还为运行名为“我们周围的模式”的初中和高中教师年度计划做出贡献。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical Abstract:Condensed matter physics has drawn inspiration from the motions of creatures ranging from bacteria to insects, fish, birds and migrating mammals to create the new field of active materials. Unlike atoms or molecules, which derive their energy from a heat source to move around in a random, undirected manner, many living creatures expend their energy to move along a preferred body axis, leading to unusual collective behaviors such as schooling, flocking and swarming. In this research, experiments will be launched to mimic some of these phenomena in laboratory systems made up of millimeter-sized grains energized by vibrations. Going beyond the biological motivation, the research team will create grains that move in designed ways to manipulate and assemble materials. Through this research, both graduate and undergraduate students will gain exposure to a variety of techniques and frontier areas in soft-condensed matter physics and be introduced to problems which have industrial relevance. The PI contributes to graduate education beyond his university by continuing to organize an annual summer school at UMass Amherst entitled Soft Solids and Complex Fluids. The PI also contributes to running an annual program for middle- and high-school teachers entitled Patterns Around Us.Technical Abstract:Active matter is a new arena for non-equilibrium statistical mechanics, inspired by observed collective behavior in motile systems from bacteria to insects, fish, birds and migrating mammals. In this project, the research team will go beyond biomimetic motivations, and explicitly set aside the constraints and intents of biological design to create "active" granular particles that can give new material function and response to granular assemblies. The particular goal is to recognize and exploit the fact the symmetry of motion of individual units can be entirely different from the symmetry of interaction with other units. The team proposes to launch experiments to study the collective mechanics of vibrated grains which rectify noise to generate directed motion. They have parallel goals of (i) exploring new issues in the statistical physics of active matter, and (ii) developing methods of manipulating and assembling macroscopic matter. The major goal of this proposal is a comprehensive experimental study of the phase diagram of a number of classes of active particles, so that light may be shed on how activity can promote or disrupt specific kinds of ordering. Through this research, both graduate and undergraduate students will gain exposure to a variety of techniques and frontier areas in soft-condensed matter physics and be introduced to problems which have industrial relevance. The PI contributes to graduate education beyond his university by continuing to organize an annual summer school at UMass Amherst entitled Soft Solids and Complex Fluids. The PI also contributes to running an annual program for middle- and high-school teachers entitled Patterns Around Us.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.