Bending of an elastoplastic strip with isotropic and kinematic hardening

Summary  We propose an exact analysis for finite bending of a compressible elastoplastic strip with combined hardening at a given stretch normal to the bending plane. We apply the self-consistent eulerian rate-type elastoplastic model based on the logarithmic rate, in conjunction with a Tresca-type loading function. Utilizing the maximum circumferential stretch at the outer surface as an independent parameter, we derive exact analytic expressions for the bending angle, the bending moment, the outer and inner radii, the radii of the two elastic-plastic interfaces and the circumferential stretches at these two interfaces, as well as the stress distributions in every current cross section. In particular, we establish an explicit relation between the two circumferential stretches at the two elastic-plastic interfaces, and we show that this relation is universal for all cases of hardening. We show also that the maximum and minimum circumferential stretches at the outer and inner surfaces obey a reciprocal relation in the course of both elastic and elastic-plastic deformations. Received 4 June 2002; accepted for publication 14 November 2002 This research was carried out under financial support from the German Science Foundation (DFG) (Contract No.: Br. 580/26-2) and from Alexander von Humboldt Foundation. We wish to express our sincere gratitude to these Foundations.     

The quark gluon plasma: Lattice computations put to experimental test

I describe how lattice computations are being used to extract experimentally relevant features of the quark gluon plasma. I deal specifically with relaxation times, photon emissivity, strangeness yields, event-by-event fluctuations of conserved quantities and hydrodynamic flow. Finally I give evidence that the plasma is rather liquid-like in some ways.     

Frequency chirp in W-band pulsed IMPATT oscillators

An analytical device-circuit interaction model to compute the frequency chirp bandwidth in W-band pulsed DDR IMPATT diodes is presented. The measured chirp agrees reasonably well with the calculated values.     

Embeddings on a boolean cube

In this paper, we characterize a class of graphs which can be embedded on a boolean cube. Some of the graphs in this class are identified with the well known graphs such asmulti-dimensional mesh of trees, tree of meshes, etc. We suggest (i) an embedding of anr-dimensional mesh of trees ofn ^r (r+1)–rn ^r–1 nodes on a boolean cube of (2n) ^r nodes, and (ii) an embedding of a tree of meshes with 2n ² logn+n ² nodes on a boolean cube withn ² exp₂ (log (2 logn+1)]) nodes.     

On the general solution for a class of charged fluid spheres

We have derived all the charged fluid spheres described by a space-time with its hypersurfaces t = const. as spheroids subject to a particular form of electric field intensity. Only one out of the four solutions so obtained is reducible to its uncharged counterpart in the absence of the charge.     

Quark number susceptibilities and the Wróblewski parameter

The Wróblewski parameter is a convenient indicator of strangeness production and can be employed to monitor a signal of quark-gluon plasma production : enhancement of strangeness production. It has been shown to be about a factor two higher in heavy ion collisions than in hadronic collisions. Using a method proposed by us earlier, we obtained lattice QCD results for the Wróblewski parameter from our simulations of QCD with two light quarks both below and above the chiral transition. Our first principles based and parameter free result compare well with the A-A data from SPS and RHIC.Arrival of the final proofs: 24 March 2005PACS: 12.38.Mh, 12.38.GcR.V. Gavai: Alexander von Humboldt Fellow on leave from TIFR, Mumbai and speaker at the conference.     

Superconductivity and possible overdoping in Lu1−x Ca x Ba2Cu3O7−δ

Structural and superconducting properties of the system Lu_1?x Ca _x Ba₂ Cu₃O_7?δ, both in bulk as well as thin film form, have been investigated. Presence of large Ca-ions at the Lu-sites is responsible for phase stability (in 1–2–3 phase) in bulk. In argon annealed tetragonal samples (δ:1) superconductivity is reinstated as in these samples, presence of Ca-ions lead to the generation of holes in the Cu?O planes. In oxygen annealed bulk samples and thin films, there is a large depression ofT _c due to divalent Ca-ions present in concentrationx<0.2. Our data indicate that this depression ofT _c is likely due to overdoping effect.     

Minimizing flow time in a flow-line manufacturing cell with family setup times

This paper considers the problem of scheduling part families and jobs within each part family in a flowline manufacturing cell with independent family setup times where parts (jobs) in each family are processed together. The objective is to minimize total flow time. A branch-and-bound algorithm capable of solving moderate sized problems is developed. Several heuristic algorithms are proposed and empirically evaluated as to their effectiveness and efficiency in finding optimal permutation schedules. These results show that several heuristic algorithms generate solutions that are better than those generated by an existing genetic algorithm.     

Kinetic energy oscillations in annular regions of ultracold neutral plasmas

A study of ion equilibration in annular regions of ultracold strontium plasmas is reported. Plasmas are formed by photoionizing laser-cooled atoms with a pulsed dye laser. The experimental probe is spatially-resolved absorption spectroscopy using the ²S_1/2-²P_1/2 transition of the Sr⁺ ion. The kinetic energy of the ions is calculated from the Doppler broadening of the spectrum, and it displays clear oscillations during the first microsecond after plasma formation. The oscillations, which are a characteristic of strong coulomb coupling, are fit with a simple phenomenological model incorporating damping and density variation in the plasma.