Quantification of Thickness Effects for Circumferential Through-Wall Cracked Pipe Bend with Un-Uniform Thickness under In-Plane Opening Bending

AbstractAn Elbow is one of the major component that make up the piping system of a nuclear power plant and chemical plant facilities. In general, the elbow is made by welding a straight pipe and bend part. So, periodic welding inspection is required due to the potential defects in weld zone. Recently, the application of induction heating pipe bend is increasing in order to reduce this problem. Pipe bend made by induction heating band is not necessary welding process because it is made by bending a straight pipe but the intrados thickness and the extrados thickness are different. On the other hand, J-integral is widely used to evaluate a structural integrity (to check crack stability) but the J estimation of pipe bend with un-uniform thickness is very difficult because of the thickness differences in each locations.This paper proposes a reference stress based J estimation scheme of circumferential through-wall cracked pipe bend with un-uniform thickness under in-plane opening bending loading condition. The pipe bend with un-uniform thickness is assumed to have different thickness between intrados and extrados and the crack to be located in the entre of the pipe bend, either at the intrados or extrados

Stability Of contact discontinuity for steady Euler System in infinite duct

In this paper, we prove structural stability of contact discontinuities for full Euler system

Room temperature spin coherence in ZnO

Time-resolved optical techniques are used to explore electron spin dynamics in bulk and epilayer samples of n-type ZnO as a function of temperature and magnetic field. The bulk sample yields a spin coherence time T2* of 20 ns at T = 30 K. Epilayer samples, grown by pulsed laser deposition, show a maximum T2* of 2 ns at T = 10 K, with spin precession persisting up to T = 280 K.Comment: 3 pages, 3 figure

Electron affinity of Li: A state-selective measurement

We have investigated the threshold of photodetachment of Li^- leading to the formation of the residual Li atom in the $2p ^2P$ state. The excited residual atom was selectively photoionized via an intermediate Rydberg state and the resulting Li^+ ion was detected. A collinear laser-ion beam geometry enabled both high resolution and sensitivity to be attained. We have demonstrated the potential of this state selective photodetachment spectroscopic method by improving the accuracy of Li electron affinity measurements an order of magnitude. From a fit to the Wigner law in the threshold region, we obtained a Li electron affinity of 0.618 049(20) eV.Comment: 5 pages,6 figures,22 reference

Color Reflection Invariance and Monopole Condensation in QCD

We review the quantum instability of the Savvidy-Nielsen-Olesen (SNO) vacuum of the one-loop effective action of SU(2) QCD, and point out a critical defect in the calculation of the functional determinant of the gluon loop in the SNO effective action. We prove that the gauge invariance, in particular the color reflection invariance, exclude the unstable tachyonic modes from the gluon loop integral. This guarantees the stability of the magnetic condensation in QCD.Comment: 28 pages, 3 figures, JHEP styl

A combinatorial approach to knot recognition

This is a report on our ongoing research on a combinatorial approach to knot recognition, using coloring of knots by certain algebraic objects called quandles. The aim of the paper is to summarize the mathematical theory of knot coloring in a compact, accessible manner, and to show how to use it for computational purposes. In particular, we address how to determine colorability of a knot, and propose to use SAT solving to search for colorings. The computational complexity of the problem, both in theory and in our implementation, is discussed. In the last part, we explain how coloring can be utilized in knot recognition

Deformed Gaussian Orthogonal Ensemble Analysis of the Interacting Boson Model

A Deformed Gaussian Orthogonal Ensemble (DGOE) which interpolates between the Gaussian Orthogonal Ensemble and a Poissonian Ensemble is constructed. This new ensemble is then applied to the analysis of the chaotic properties of the low lying collective states of nuclei described by the Interacting Boson Model (IBM). This model undergoes a transition order-chaos-order from the $SU(3)$ limit to the $O(6)$ limit. Our analysis shows that the quantum fluctuations of the IBM Hamiltonian, both of the spectrum and the eigenvectors, follow the expected behaviour predicted by the DGOE when one goes from one limit to the other.Comment: 10 pages, 4 figures (avaiable upon request), IFUSP/P-1086 Replaced version: in the previous version the name of one of the authors was omitte