Mobility, interactions, and order in active granular systems

非技术摘要：凝聚态物理从细菌到昆虫、鱼类、鸟类和迁徙的哺乳动物等生物的运动中获得灵感，创造了活性材料的新领域。与原子或分子不同，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，许多生物通过消耗能量沿着首选的身体轴移动，导致不寻常的集体行为，如群居、成群和成群。在这项研究中，将启动实验，在实验室系统中模拟其中的一些现象，这些系统由毫米尺寸的颗粒通过振动提供能量。除了生物动机，研究团队将创造出以设计的方式移动的颗粒，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的各种技术和前沿领域，并被介绍给与工业相关的问题。这位少年派继续在马萨诸塞州大学阿默斯特分校组织一年一度的名为软固体和复杂流体的暑期班，为大学以外的研究生教育做出贡献。PI还为初中和高中教师举办了一个名为Patterns About US的年度项目。技术摘要：活性物质是非平衡统计力学的一个新领域，其灵感来自于从细菌到昆虫、鱼类、鸟类和迁徙的哺乳动物等运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，明确抛开生物设计的限制和意图，创造出能够赋予颗粒组装新的材料功能和响应的“活性”颗粒。特别的目标是认识和利用这样一个事实，即单个单位的运动对称性可以完全不同于与其他单位相互作用的对称性。该团队建议开展实验，研究振动颗粒的集体机制，这种集体机制可以纠正噪音，产生定向运动。他们有相同的目标：(I)探索活动物质统计物理中的新问题，(Ii)发展操纵和组装宏观物质的方法。这一提议的主要目标是对几类活性粒子的相图进行全面的实验研究，以便揭示活动如何促进或破坏特定类型的有序性。通过这项研究，研究生和本科生都将接触到软凝聚态物理的各种技术和前沿领域，并被介绍给与工业相关的问题。这位少年派继续在马萨诸塞州大学阿默斯特分校组织一年一度的名为软固体和复杂流体的暑期班，为大学以外的研究生教育做出贡献。这个奖项反映了NSF的法定使命，通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为是值得支持的。

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.