Pressure-sensitive-paint force transducers

In this work, the performance of direct-load-measuring transducers of the recent “pressure-sensitivepaint” variety is critically analyzed. The characteristics of laboratory-prepared and commercial load cells incorporating this paint are studied. For the transducers tested, the conclusion reached was that these cells are unreliable in their load-indicating properties. The application of pressure-sensitive paints of this type in the measurement of other quantities such as pressure, strain and acceleration would appear unjustified because of the poor results obtained in the measurement of simple, direct loads.     

Auto-aerodynamic drag-force analysis

This paper describes an inexpensive experimental method of evaluating the aerodynamic drag forces encountered by automobiles under actual roadtraveling conditions. The data are directly applicable to stress, power and efficiency analyses. The procedure consists of applying Newton's second law,F=Ma, to a freely decelerating vehicle to obtain the opposing force-velocity relationship. By greatly increasing tire-inflation pressure, the rolling resistance is made constant. The remaining aerodynamic drag force is found to vary directly with the square of velocity, allowing the theoretical drag coefficients to be calculated. An illustrated auto-aerodynamic drag study of a recent production vehicle indicates that significant improvements in efficiency can be achieved by simple streamlining of the leading body surfaces.     

Global rigidity of higher rank abelian Anosov algebraic actions

We show that all \(C^\infty \) Anosov \(\mathbb {Z}^r\) -actions on tori and nilmanifolds without rank-one factor actions are, up to \(C^\infty \) conjugacy, actions by automorphisms.     

Analytical Standards and Methods for the Determination of Polynuclear Aromatic Hydrocarbons in Environmental Samplest

Abstract

Standard reference materials (SRM's) have been produced, certified, and issued by the United States National Bureau of Standards (NBS) since 1905. NBS currently issues more than 1000 SRM's of various types, including nuclear materials, rubber, clinical and environmental trace metal standards. The most recent addition to this group is a series of environmental trace organic materials with certified concentrations of selected polynuclear aromatic hydrocarbons (PAH), phenols, and N-heterocyclic compounds. Until recently, trace organic SRM's were non-existent due to the lack of analytical methodology necessary for certification. Details concerning the analytical methods developed and used for certification of the concentrations of several PAH in SRM's 1580 (Organics in Shale Oil), 1644 (Generator Columns for PAH in water), 1647 (PAH in Acetonitrile), and 1649 (Urban Particulate Matter) are given along with some suggested uses for these SRM's.     

Über die statistische Mechanik der Raumgesamtheit und den Begriff der Komplexion

Ohne ZusammenfassungEine kürzere, übrigens später verfaßte, Darstellung über diesen Gegenstand erschien in den Göttinger Nachrichten 1912.     

Ants can colour graphs

In the last few years researchers have shown how insect colonies can be seen as a natural model of collective problem solving. The analogy between the behaviour of ants looking for food and the well known travelling salesman problem has recently given rise to promising solution methods. We present in this paper an evolutionary search procedure for tackling assignment type problems. The algorithm repeatedly constructs feasible solutions of the problem under study by taking account of two complementary notions, namely the trace factor and the desirability factor. The use of such search principles will be illustrated for graph colouring problems. The results obtained have proven satisfactory when compared with those existing in the literature.