Holographic and ultrasonic detection of bond flaws in aluminum panels reinforced with boron-epoxy

An experimental investigation was made of the application of holographic interferometry to the nondestructive detection of unbonded areas (flaws) in bonded panels. Flaw detection results were compared with results obtained with an ultrasonic flaw detector. Holography, with panel deformation accomplished by a reduction in ambient pressure, is less sensitive for flaws beneath 5 and 10 plies of boron-epoxy than the ultrasonic method, though it does have its operational advantages. A process for the manufacture of bonded panels which incorporate known unbonded areas was also developed. The unbonded areas were formed without the use of foreign materials, which makes the method suitable for the construction of reference standards for bonded panels whenever needed for the proper setup of ultrasonic flaw-detection instruments

Buckling of cylindrical shell end closures by internal pressure

Buckling of cylindrical shell end closures by internal pressur

Correspondence - August 28, 1969 - Dr. Jones Thurston, Jr.

A correspondence between Hubbard Hamrick and Doc Jones Thurston, Jr. Mentions the book What Made Me a Baptist by Charles Augustus Jenkins, about his conversion from the Episcopal Church to the Baptist.https://digitalcommons.gardner-webb.edu/first-baptist-shelby-charles-augustus-jenkins/1003/thumbnail.jp

Complexes affecting the solubility of calcium carbonate in water—phase II

The water utilities in this country have a tremendous investment in the miles of pipe, valves, and other appurtenances in the water distribution systems. Failure to protect these systems against corrosion and excessive scale formation could necessitate replacement of the distribution systems at an estimated cost of $25 billion. Calculation of the true equilibrium or saturation pH, pH, for calcium carbonate and adjustment of the water to that pH is essential to supply water of high quality and to avoid corrosion and scale formation in these water distribution systems. Experience has shown that in some cases the actual pH must be from 0.6 to 1.0 unit above pHs, as determined from the calcium and alkalinity analyses. Certain complexes may be responsible in part for this fact. The specific objective of this study was to evaluate the dissociation constants of the complexes so that the optimum pH can be more accurately calculated. A titration method was used to measure the effects of complex formation on the pH of reaction mixtures and appropriate computer programs were developed to calculate the dissociation constants. Experimental procedures and results from the determination of dissociation constants for complexes of magnesium, calcium and sodium with carbonate, bicarbonate, hydroxide, and sulfate and a method to utilize these constants in calculating pHs in public water supplies are discussed.U.S. Department of the InteriorU.S. Geological SurveyOpe

Learning SO(3) Equivariant Representations with Spherical CNNs

We address the problem of 3D rotation equivariance in convolutional neural networks. 3D rotations have been a challenging nuisance in 3D classification tasks requiring higher capacity and extended data augmentation in order to tackle it. We model 3D data with multi-valued spherical functions and we propose a novel spherical convolutional network that implements exact convolutions on the sphere by realizing them in the spherical harmonic domain. Resulting filters have local symmetry and are localized by enforcing smooth spectra. We apply a novel pooling on the spectral domain and our operations are independent of the underlying spherical resolution throughout the network. We show that networks with much lower capacity and without requiring data augmentation can exhibit performance comparable to the state of the art in standard retrieval and classification benchmarks.Comment: Camera-ready. Accepted to ECCV'18 as oral presentatio

Comments on Closed Bianchi Models

We show several kinematical properties that are intrinsic to the Bianchi models with compact spatial sections. Especially, with spacelike hypersurfaces being closed, (A) no anisotropic expansion is allowed for Bianchi type V and VII(A\not=0), and (B) type IV and VI(A\not=0,1) does not exist. In order to show them, we put into geometric terms what is meant by spatial homogeneity and employ a mathematical result on 3-manifolds. We make clear the relation between the Bianchi type symmetry of space-time and spatial compactness, some part of which seem to be unnoticed in the literature. Especially, it is shown under what conditions class B Bianchi models do not possess compact spatial sections. Finally we briefly describe how this study is useful in investigating global dynamics in (3+1)-dimensional gravity.Comment: 14 pages with one table, KUCP-5

AF-algebras and topology of mapping tori

A covariant functor from the category of mapping tori to a category of AF-algebras is constructed; the functor takes continuous maps between such manifolds to stable homomorphisms between the corresponding AF-algebras. We use this functor to develop an obstruction theory for the torus bundles of dimension 2, 3 and 4.Comment: to appear Czechoslovak Math.

Fiber Acoustic Waveguide : A Sensor Candidate

Sensor development plays a key role in the field of nondestructive evaluation and process control. The annual fiber optic sensor market alone is a multimillion dollar business (1). Acoustic waves are about five orders of magnitude slower than optical waves and can also be guided in cladded glass fibers, similar to optical fibers, with low loss and low dispersion (2–7). Fiber acoustic waveguides are believed to be a very attractive and basic component for further sensor development (8). In this paper a brief theoretical description of a weakly guiding acoustic fiber (7) is given. The material selection criteria for the core and the cladding of the fiber guide, the properties of single-mode operation, and some sensing mechanisms for temperature and pressure variations are discussed. The acoustic waveguide with a liquid core is also considered

Characteristic Energy of the Coulomb Interactions and the Pileup of States

Tunneling data on $\mathrm{La_{1.28}Sr_{1.72}Mn_2O_7}$ crystals confirm Coulomb interaction effects through the $\sqrt{\mathrm{E}}$ dependence of the density of states. Importantly, the data and analysis at high energy, E, show a pileup of states: most of the states removed from near the Fermi level are found between ~40 and 130 meV, from which we infer the possibility of universal behavior. The agreement of our tunneling data with recent photoemission results further confirms our analysis.Comment: 4 pages, 4 figures, submitted to PR

Potential water resources of Southern Illinois

Bibliography: p. 96-97