A nonsmooth optimization approach for hemivariational inequalities with applications to contact mechanics

In this paper we introduce an abstract nonsmooth optimization problem and prove existence and uniqueness of its solution. We present a numerical scheme to approximate this solution. The theory is later applied to a sample static contact problem describing an elastic body in frictional contact with a foundation. This contact is governed by a nonmonotone friction law with dependence on normal and tangential components of displacement. Finally, computational simulations are performed to illustrate obtained results

Particle simulation of granular flows in electrostatic separation processes

In waste processing technology, the recent Corona Electrostatic Separation (CES) method is used to separate conductive from non-conductive particles in recycling streams. This paper proposes an innovative simulation approach based on non-smooth dynamics. In this context, a differential-variational formulation is used to implement a scalable and efficient time integrator that allows the large-scale simulation of trajectories of particles with different properties under the effect of particle-particle interactions and frictional contacts. Issues related to performance optimization, fast collision detection and parallelization of the code are discussed

Numerical Methods for Nonsmooth Dynamical Systems: Applications in Mechanics and Electronics

International audienceThis book concerns the numerical simulation of dynamical systems whose trajectories may not be differentiable everywhere. They are named nonsmooth dynamical systems. They make an important class of systems, firstly because of the many applications in which nonsmooth models are useful, secondly because they give rise to new problems in various fields of science. Usually nonsmooth dynamical systems are represented as differential inclusions, complementarity systems, evolution variational inequalities, each of these classes being itself split into several subclasses. With detailed examples of multibody systems with contact, impact and friction and electrical circuits with piecewise linear and ideal components, the book is is mainly intended for researchers in Mechanics and Electrical Engineering, but it will be attractive to researchers from other scientific communities like Systems and Control, Robotics, Physics of Granular Media, Civil Engineering, Virtual Reality, Haptic Systems, Computer Graphics, etc

Hypergrammar-based parallel multi-frontal solver for grids with point singularities

This paper describes the application of hypergraph grammars to drive linear computationalcost solver for grids with point singularities. Such graph grammar productions are the rstmathematical formalism used to describe solver algorithm and each of them indicates thesmallest atomic task that can be executed in parallel, which is very useful in case of parallelexecution. In particular the partial order of execution of graph grammar productions can befound, and the sets of independent graph grammar productions can be localized. They canbe scheduled set by set into shared memory parallel machine. The graph grammar basedsolver has been implemented with NIVIDIA CUDA for GPU. Graph grammar productionsare accompanied by numerical results for 2D case. We show that our graph grammar basedsolver with GPU accelerator is order of magnitude faster than state of the art MUMPSsolver

Innovation and Growth with Financial, and Other, Frictions

The generation and implementation of ideas, or knowledge, is crucial for economic performance. We study this process in a model of endogenous growth with frictions. Productivity increases with knowledge, which advances via innovation, and with the exchange of ideas from those who generate them to those best able to implement them (technology transfer). But frictions in this market, including search, bargaining, and commitment problems, impede exchange and thus slow growth. We characterize optimal policies to subsidize research and trade in ideas, given both knowledge and search externalities. We discuss the roles of liquidity and financial institutions, and show two ways in which intermediation can enhance efficiency and innovation. First, intermediation allows us to finance more transactions with fewer assets. Second, it ameliorates certain bargaining problems, by allowing entrepreneurs to undo otherwise sunk investments in liquidity. We also discuss some evidence, suggesting that technology transfer is a significant source of innovation and showing how it is affected by credit considerations.Economic models; Potential output; Productivity