Parallel Gap Welding

Requirements of parallel gap welding in microelectronic

Characteristics of the polymer transport in ratchet systems

Molecules with complex internal structure in time-dependent periodic potentials are studied by using short Rubinstein-Duke model polymers as an example. We extend our earlier work on transport in stochastically varying potentials to cover also deterministic potential switching mechanisms, energetic efficiency and non-uniform charge distributions. We also use currents in the non-equilibrium steady state to identify the dominating mechanisms that lead to polymer transportation and analyze the evolution of the macroscopic state (e.g., total and head-to-head lengths) of the polymers. Several numerical methods are used to solve the master equations and nonlinear optimization problems. The dominating transport mechanisms are found via graph optimization methods. The results show that small changes in the molecule structure and the environment variables can lead to large increases of the drift. The drift and the coherence can be amplified by using deterministic flashing potentials and customized polymer charge distributions. Identifying the dominating transport mechanism by graph analysis tools is found to give insight in how the molecule is transported by the ratchet effect.Comment: 35 pages, 17 figures, to appear in Phys. Rev.

Vulnerable warriors: the atmospheric marketing of military and policing equipment before and after 9/11

In this article, we analyse changes in the circulation of advertisements of policing products at security expos between 1995 and 2013. While the initial aim of the research was to evidence shifts in terrorist frames in the marketing of policing equipment before and after 9/11, our findings instead suggested that what we are seeing is the rise of marketing to police as “vulnerable warriors”, law enforcement officers in need of military weapons both for their offensive capabilities and for the protection they can offer to a police force that is always under threat

A neutron diffuse scattering study of PbZrO₃ and Zr-rich PbZr_1-xTi_xO₃

A combined neutron diffuse scattering study and model analysis of the antiferroelectric crystal PbZrO3is described. Following on from earlier X-ray diffuse scattering studies, supporting evidence for disordering of oxygen octahedral tilts and Pb displacements is shown in the high-temperature cubic phase. Excess diffuse scattering intensity is found at theMandRpoints in the Brillouin zone. A shell-model molecular dynamics simulation closely reproduces the neutron diffuse scattering pattern. Both in-phase and antiphase tilts are found in the structural model, with in-phase tilts predominating. The transition between disordered and ordered structure is discussed and compared with that seen in Zr-rich PbZr1−xTixO3.</jats:p

Mathematical Modeling, Numerical Techniques, and Computer Simulation of Flows and Transport in Porous Media

this paper we present a variety of models in groundwater hydrology that have been used in computer simulation for design of remediation and clean-up technologies. We also discuss the important question of the choice of the approximation method for the corresponding mathematical problem. In fluid reservoirs (aquifer and petroleum reservoirs) there are two imperative practical requirements: the method should conserve the mass locally and should produce accurate velocities (fluxes) even for highly nonhomogeneous media with large jumps in the physical properties. This is the reason that the finite volume method with harmonic averaging of the coefficients has been very popular and successful in computer simulation of flows in porous media. However, when the problem requires accurate description of the topography and the hydrological structure, a more general technique based on the finite element approximation is needed. The mixed finite element method has these properties. Since its introduction by Raviart and Thomas [23] and its implementation by Ewing and Wheeler [17] for flow problems, it has become a standard way of deriving highorder conservative approximations. It should be noted that the lowest-order mixed method realized on rectangles (or parallelepipeds) with certain numerical integration produces cell-centered finite differences with harmonic averaging. In Section 5 we describe briefly the mixed finite element method for the linearized pressure equation using Raviart-Thomas finite elements. This will lead to a symmetric but indefinite system for the unknown pressure and velocity (flux). Next, we discuss briefly the algorithms involved in the solution of this saddle point type problem and introduce a variant of the classical Uzawa method. This variant was studied re..