Application of Hierarchical Matrix Techniques To The Homogenization of Composite Materials

In this paper, we study numerical homogenization methods based on integral equations. Our work is motivated by materials such as concrete, modeled as composites structured as randomly distributed inclusions imbedded in a matrix. We investigate two integral reformulations of the corrector problem to be solved, namely the equivalent inclusion method based on the Lippmann-Schwinger equation, and a method based on boundary integral equations. The fully populated matrices obtained by the discretization of the integral operators are successfully dealt with using the H-matrix format

An Automatic Speed Control for Wind Tunnels

Described here is an automatic control that has been used in several forms in wind tunnels at the Washington Navy Yard. The form now in use with the 8-foot tunnel at the Navy Yard is considered here. Details of the design and operation of the automatic control system are given. Leads from a Pitot tube are joined to an inverted cup manometer located above a rheostat. When the sliding weight of this instrument is set to a given notch, say for 40 m.p.h, the beam tip vibrates between two electric contacts that feed the little motor. Thus, when the wind is too strong or too weak, the motor automatically throws the rheostat slide forward and backward. If it failed to function well, the operator would notice the effect on his meniscus, and would operate the hand control by merely pressing the switch

Flow and Force Equations for a Body Revolving in a Fluid

A general method for finding the steady flow velocity relative to a body in plane curvilinear motion, whence the pressure is found by Bernoulli's energy principle is described. Integration of the pressure supplies basic formulas for the zonal forces and moments on the revolving body. The application of the steady flow method for calculating the velocity and pressure at all points of the flow inside and outside an ellipsoid and some of its limiting forms is presented and graphs those quantities for the latter forms. In some useful cases experimental pressures are plotted for comparison with theoretical. The pressure, and thence the zonal force and moment, on hulls in plane curvilinear flight are calculated. General equations for the resultant fluid forces and moments on trisymmetrical bodies moving through a perfect fluid are derived. Formulas for potential coefficients and inertia coefficients for an ellipsoid and its limiting forms are presented

Flow and Drag Formulas for Simple Quadrics

The pressure distribution and resistance found by theory and experiment for simple quadrics fixed in an infinite uniform stream of practically incompressible fluid are calculated. The experimental values pertain to air and some liquids, especially water; the theoretical refer sometimes to perfect, again to viscid fluids. Formulas for the velocity at all points of the flow field are given. Pressure and pressure drag are discussed for a sphere, a round cylinder, the elliptic cylinder, the prolate and oblate spheroid, and the circular disk. The velocity and pressure in an oblique flow are examined

A tensor approximation method based on ideal minimal residual formulations for the solution of high-dimensional problems

In this paper, we propose a method for the approximation of the solution of high-dimensional weakly coercive problems formulated in tensor spaces using low-rank approximation formats. The method can be seen as a perturbation of a minimal residual method with residual norm corresponding to the error in a specified solution norm. We introduce and analyze an iterative algorithm that is able to provide a controlled approximation of the optimal approximation of the solution in a given low-rank subset, without any a priori information on this solution. We also introduce a weak greedy algorithm which uses this perturbed minimal residual method for the computation of successive greedy corrections in small tensor subsets. We prove its convergence under some conditions on the parameters of the algorithm. The residual norm can be designed such that the resulting low-rank approximations are quasi-optimal with respect to particular norms of interest, thus yielding to goal-oriented order reduction strategies for the approximation of high-dimensional problems. The proposed numerical method is applied to the solution of a stochastic partial differential equation which is discretized using standard Galerkin methods in tensor product spaces

Der Ausschuss für Sicherheit und Gesundheitsschutz auf Baustellen – Praxiserfahrungen bei der Überwachung der Baustellenverordnung aus der Sicht der sächsischen Arbeitsschutzverwaltung

Der Ausschuss für Sicherheit und Gesundheitsschutz auf Baustellen; Praxiserfahrungen bei der Überwachung der Baustellenverordnung aus der Sicht der sächsischen Arbeitsschutzverwaltun

Sweat v. Eighth Judicial Dist. Court, 133 Nev. Adv. Op. 76 (October 5, 2017)

The Double Jeopardy Clause does not protect a defendant from prosecution of any original charges when the defendant accepts a plea agreement for a lesser-included offense and then fails to comply with all the terms of the agreement. The Court ultimately determined that a defendant waives his double jeopardy rights when he pleads guilty and fails to comply with the remaining terms of the agreement

From Experimental Studies to Coarse-Grained Modeling: Characterization of Surface Area to Volume Ratio Effects on the Swelling of Poly (Ethylene Glycol) Dimethacrylate Hydrogels

Understanding the performance of widely applied nanoscale hydrogel biomaterials is an unmet need within the biomedical field. The objective of this master’s thesis project was to evaluate the effects size and surface area has on the in vivo behavior of nanoscale hydrogels. The hypothesis tested was that at the nanoscale, the increased surface area to volume effects of nanoscale hydrogels play and important role in the overall swelling of hydrogels, such that nanoscale hydrogels swell to a greater degree than their bulk counterparts. To investigate this, the bulk swelling behavior of a series of neutral poly (ethylene glycol) di-methacrylate (PEGDMA) hydrogels was experimentally tested. Along with experimental studies, a computational model based on the experimental findings was developed to serve as a means of predicting nanoscale swelling and subsequent drug release behavior. The computational hydrogel model was validated with the experimental densities and swelling ratios calculated. The surfaces of swollen hydrogels had a density gradient until reaching a stabilized, core density. As the size of the hydrogel decreases, the surface area to volume ratio increases, which enhances surface effects for micro- and nanoscale hydrogels. This conclusion helps to confirm the hypothesis that the increased surface area to volume ratio of nanoscale hydrogels affects the overall swelling ratio in comparison to their bulk counter parts. Particle size should be considered when characterizing nanoscale hydrogels. In this thesis, a computational hydrogel model capable of simulating hydrogel swelling for hydrogels with a dry state diameter of 40 nm was created. In the future, this model would ideally be able to simulate hydrogels with a dry state diameter ≥ 100 nm to test the full range of nanoscale size effects on hydrogel swelling