Soft particles at liquid interfaces: From molecular particle architecture to collective phase behavior

Soft particles such as microgels and core-shell particles can undergo significant and anisotropic deformations when adsorbed to a liquid interface. This, in turn, leads to a complex phase behavior upon compression. Here we develop a multiscale framework to rationally link the molecular particle architecture to the resulting interfacial morphology and, ultimately, to the collective interfacial phase behavior, enabling us to identify the key single-particle properties underlying two-dimensional continuous, heterostructural, and isostructural solid-solid transitions. Our approach resolves existing discrepancies between experiments and simulations and thus provides a unifying framework to describe phase transitions in interfacial soft-particle systems. We establish proof-of-principle for our rational approach by synthesizing three different poly(N-isopropylacrylamide) soft-particle architectures, each of which corresponds to a different targeted phase behavior. In parallel, we introduce a versatile and highly efficient coarse-grained simulation method that adequately captures the qualitative key features of each soft-particle system; the novel ingredient in our simulation model is the use of auxiliary degrees of freedom to explicitly account for the swelling and collapse of the particles as a function of surface pressure. Notably, these combined efforts allow us to establish the first experimental demonstration of a heterostructural transition to a chain phase in a single-component system, as well as the first accurate in silico account of the two-dimensional isostructural transition. Overall, our multiscale framework provides a bridge between physicochemical soft-particle characteristics at the molecular- and nanoscale and the collective self-assembly phenomenology at the macroscale, paving the way towards novel materials with on-demand interfacial behavior

Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: ● Formulations and Numerical Methods ● Efficient Methods and Real-Time Applications ● Flexible Multibody Dynamics ● Contact Dynamics and Constraints ● Multiphysics and Coupled Problems ● Control and Optimization ● Software Development and Computer Technology ● Aerospace and Maritime Applications ● Biomechanics ● Railroad Vehicle Dynamics ● Road Vehicle Dynamics ● Robotics ● Benchmark ProblemsPostprint (published version

Structural basis of phosphatidylinositol 3-kinase C2α function

Phosphatidylinositol 3-kinase type 2α (PI3KC2α) is an essential member of the structurally unresolved class II PI3K family with crucial functions in lipid signaling, endocytosis, angiogenesis, viral replication, platelet formation and a role in mitosis. The molecular basis of these activities of PI3KC2α is poorly understood. Here, we report high-resolution crystal structures as well as a 4.4-Å cryogenic-electron microscopic (cryo-EM) structure of PI3KC2α in active and inactive conformations. We unravel a coincident mechanism of lipid-induced activation of PI3KC2α at membranes that involves large-scale repositioning of its Ras-binding and lipid-binding distal Phox-homology and C-C2 domains, and can serve as a model for the entire class II PI3K family. Moreover, we describe a PI3KC2α-specific helical bundle domain that underlies its scaffolding function at the mitotic spindle. Our results advance our understanding of PI3K biology and pave the way for the development of specific inhibitors of class II PI3K function with wide applications in biomedicine

Dynamic balance and walking control of biped mechanisms

The research presented here focuses on the development of a feedback control systems for locomotion of two and three dimensional, dynamically balanced, biped mechanisms. The main areas to be discussed are: development of equations of motion for multibody systems, balancing control, walking cycle generation, and interactive computer graphics. Additional topics include: optimization, interface devices, manual control methods, and ground contact force generation;Planar (2D) and spatial (3D) multibody system models are developed in this thesis to handle all allowable ground support conditions without system reconfiguration. All models consist of lower body segments only; head and arm segments are not included. Model parameters for segment length, mass, and moments of inertia are adjustable. A ground contact foot model simulates compression compliance and allows for non-uniform surfaces. In addition to flat surfaces with variable friction coefficients, the systems can adapt to inclines and steps;Control techniques are developed that range from manual torque input to automatic control for several types of balancing, walking, and transitioning modes. Balancing mode control algorithms can deal with several types of initial conditions which include falling and jumping onto various types of surfaces. Walking control state machines allow selection of steady-state velocity, step size, and/or step frequency;The real-time interactive simulation software developed during this project allows the user to operate the biped systems within a 3D virtual environment. In addition to presenting algorithms for interactive biped locomotion control, insights can also be drawn from this work into the levels of required user effort for tasks involving systems controlled by simultaneous user inputs;Position and ground reaction force data obtained from human walking studies are compared to walking data generated by one of the more complex biped models developed for this project

The d'Alembert–Lagrange principal equations and applications to floating flexible systems

This paper addresses the dynamics and quasi‐statics of floating flexible structures as well as extensions to unconstrained substructures and partitions of coupled mechanical systems. The principal solution is defined as the state of self‐equilibrated forces obtained as the particular solution of the rigid motion and interface equilibrium equations. This solution is independent of the stress–strain constitutive properties as well as of the compatibility equations. For statically determinate systems, the principal solution is the final force solution. For statically indeterminate systems, the correction due to flexibility and compatibility is orthogonal to the principal solution. The formulation is done in the context of d'Alembert's principle, which supplies the d 'Alembert–Lagrange principal equations for floating bodies. These are obtained by summation of virtually working forces and moments acting on the floating systems. Applications of this approach are demonstrated on a set of dynamic and quasi‐static example problems of increasing generality. Linkage to variational principles with an interface potential is eventually discussed as providing the theoretical foundation for handling interacting semi‐discrete subsystems linked by node‐collocated Lagrange multipliers

Energy management system for biological 3D printing by the refinement of manifold model morphing in flexible grasping space

The use of 3D printing, or additive manufacturing, has gained significant attention in recent years due to its potential for revolutionizing traditional manufacturing processes. One key challenge in 3D printing is managing energy consumption, as it directly impacts the cost, efficiency, and sustainability of the process. In this paper, we propose an energy management system that leverages the refinement of manifold model morphing in a flexible grasping space, to reduce costs for biological 3D printing. The manifold model is a mathematical representation of the 3D object to be printed, and the refinement process involves optimizing the morphing parameters of the manifold model to achieve desired printing outcomes. To enable flexibility in the grasping space, we incorporate data-driven approaches, such as machine learning and data augmentation techniques, to enhance the accuracy and robustness of the energy management system. Our proposed system addresses the challenges of limited sample data and complex morphologies of manifold models in layered additive manufacturing. Our method is more applicable for soft robotics and biomechanisms. We evaluate the performance of our system through extensive experiments and demonstrate its effectiveness in predicting and managing energy consumption in 3D printing processes. The results highlight the importance of refining manifold model morphing in the flexible grasping space for achieving energy-efficient 3D printing, contributing to the advancement of green and sustainable manufacturing practices.Comment: 33 pages, 10 figures, Journa

Design synthesis & prototype implementation of parallel orientation manipulators for optomechatronic applications

This thesis documents a research endeavor undertaken to develop high-performing designs for parallel orientation manipulators (POM) capable of delivering the speed and the accuracy requirements of a typical optomechatronic application. In the course of the research, the state of the art was reviewed, and the areas in the existing design methodologies that can be potentially improved were identified, which included actuator design, dimensional synthesis of POMs, control system design, and kinematic calibration. The gaps in the current art of designing each of these POM system components were addressed individually. The outcomes of the corresponding development activities include a novel design of a highly integrated voice coil actuator (VCA) possessing the speed, the size, and the accuracy requirements of small-scale parallel robotics. Furthermore, a method for synthesizing the geometric dimensions of a POM was developed by adopting response surface methodology (RSM) as the optimization tool. It was also experimentally shown how conveniently RSM can be utilized to develop an empirical quantification of the actual kinematic structure of a POM prototype. In addition, a motion controller was formulated by adopting the active disturbance rejection control (ADRC) technology. The classic formulation of the ADRC algorithm was modified to develop a resource-optimized implementation on control hardware based on field programmable gate arrays (FPGA). The practicality and the effectiveness of the synthesized designs were ultimately demonstrated by performance benchmarking experiments conducted on POM prototypes constructed from these components. In specific terms, it was experimentally shown that the moving platforms of the prototyped manipulators can achieve highspeed motions that can exceed 2000 degrees/s in angular velocity, and 5×105 degrees/s2 in angular acceleration