Local CIP stabilization for composite finite elements

We propose a continuous interior penalty (CIP) method for the pure transport problem and for the viscosity dependent "Stokes-Brinkman" problem where the gradient jump penalty is localized to faces in the interior of subdomains. Special focus is given to the case where the subdomains are so-called composite finite elements, e.g., quadrilateral, hexahedral or prismatic elements which are composed by simplices such that the arising global simplicial mesh is regular. The advantage of this local CIP is that it allows for static condensation in contrast to the classical CIP method. If the degrees of freedom in the interior of the composite finite elements are eliminated using static condensation then the resulting couplings of the skeleton degrees of freedom are comparable to those for classical conforming finite element methods which leads to a substantially smaller matrix stencil than for the standard global CIP method. Optimal stability and error estimates are proved and numerical tests are presented. For the Stokes-Brinkman model, our error bound does not increase if the viscosity parameter tends to zero which is mainly achieved by adding a penalty term for the divergence of the velocity in the discretization. Moreover, the reduction effect of the static condensation is much stronger for this model since, beside the elimination of all velocity degrees of freedom in the interior of each composite cell, all pressure degrees of freedom except for the cellwise constants can be eliminated

Finite element pressure stabilizations for incompressible flow problems

Discretizations of incompressible flow problems with pairs of finite element spaces that do not satisfy a discrete inf-sup condition require a so-called pressure stabilization. This paper gives an overview and systematic assessment of stabilized methods, including the respective error analysis

Information flow properties for cyber-physical systems

In cyber-physical systems, which are the integrations of computational and physical processes, security properties are difficult to enforce. Fundamentally, physically observable behavior leads to violations of confidentiality. This work analyzes certain noninterference based security properties to ensure that interactions between the cyber and physical processes preserve confidentiality. A considerable barrier to this analysis is the representation of physical system interactions at the cyber-level. This thesis presents encoding of these physical system properties into a discrete event system and represents the cyber-physical system using Security Process Algebra (SPA). The model checker, Checker of Persistent Security (CoPS) shows Bisimulation based NonDeducibility on Compositions (BNDC) properties, which are a variant of noninterference properties, to check the system\u27s security against all potential high-level interactions. This work considers a model problem of invariant pipeline flow to examine the BNDC properties and their applicability for cyber-physical systems--Abstract, page iii

Proceedings of the Fifth NASA/NSF/DOD Workshop on Aerospace Computational Control

The Fifth Annual Workshop on Aerospace Computational Control was one in a series of workshops sponsored by NASA, NSF, and the DOD. The purpose of these workshops is to address computational issues in the analysis, design, and testing of flexible multibody control systems for aerospace applications. The intention in holding these workshops is to bring together users, researchers, and developers of computational tools in aerospace systems (spacecraft, space robotics, aerospace transportation vehicles, etc.) for the purpose of exchanging ideas on the state of the art in computational tools and techniques

Magnetic Hybrid-Materials

Externally tunable properties allow for new applications of suspensions of micro- and nanoparticles in sensors and actuators in technical and medical applications. By means of easy to generate and control magnetic fields, fluids inside of matrices are studied. This monnograph delivers the latest insigths into multi-scale modelling, manufacturing and application of those magnetic hybrid materials

Supplementary Cementitious Materials in Concrete

The articles featured in this Special Issue cover different aspects of the design, testing, and application of various types of supplementary cementitious materials in concrete. The results of the research, conducted by over 50 international universities and scientific centers, prove the great interest in the SCM topic