Angle-resolved photoemission in doped charge-transfer Mott insulators

A theory of angle-resolved photoemission (ARPES) in doped cuprates and other charge-transfer Mott insulators is developed taking into account the realistic (LDA+U) band structure, (bi)polaron formation due to the strong electron-phonon interaction, and a random field potential. In most of these materials the first band to be doped is the oxygen band inside the Mott-Hubbard gap. We derive the coherent part of the ARPES spectra with the oxygen hole spectral function calculated in the non-crossing (ladder) approximation and with the exact spectral function of a one-dimensional hole in a random potential. Some unusual features of ARPES including the polarisation dependence and spectral shape in YBa2Cu3O7 and YBa2Cu4O8 are described without any Fermi-surface, large or small. The theory is compatible with the doping dependence of kinetic and thermodynamic properties of cuprates as well as with the d-wave symmetry of the superconducting order parameter.Comment: 8 pages (RevTeX), 10 figures, submitted to Phys. Rev.

Parity-violating Electron Deuteron Scattering and the Proton's Neutral Weak Axial Vector Form Factor

We report on a new measurement of the parity-violating asymmetry in quasielastic electron scattering from the deuteron at backward angles at Q2= 0.038 (GeV/c)2. This quantity provides a determination of the neutral weak axial vector form factor of the nucleon, which can potentially receive large electroweak corrections. The measured asymmetry A=-3.51 +/- 0.57(stat) +/- 0.58(sys)ppm is consistent with theoretical predictions. We also report on updated results of the previous experiment at Q2=0.091 (GeV/c)2, which are also consistent with theoretical predictions.Comment: 4 pages, 2 figures, submitted to Phys. Rev. Let

Experimental Study on Cutter Deflection in Multi-axis NC Machining

In five-axis sculptured surface machining, the effect of cutter deflection on tool orientation planning is important. This paper studied themethod for online measurement of cutter deflections along two axes simulation.The measurement equipment was designed and implemented to acquire the displacements of cutter under cutting force online. Acquired data were processed to static values and then compensated by geometric analysis. The cutter deflection conditions were analyzed and divided into different types. The corresponding geometrical equations of the relationship of deflections of measured values and actual values were built. The inter-coupling values were decoupled by solving the geometrical equations. The changing regulations of cutter deflection with tool orientations were analyzed, which could provide support for the study of tool orientation planning. The effectiveness of measurement error compensation was verified by the difference between measured values and actual values of cutter deflections under various tool workpiece inclination angles. This work could be further employed to optimize tool orientations for suppressing the surface errors due to cutter deflections and achieving higher machining accuracy

Classification of the strain and growth phase of cyanobacteria in potable water using an electronic nose system

An electronic nose comprising an array of six commercial odour sensors has been used to monitor not only different strains, but also the growth phase, of cyanobacteria which is normally called blue green algal. A series of experiments were carried out to analyse the nature of two closely related strains of cyanobacteria, Microcystis aeruginosa PCC 7806 that produces a toxin and PCC 7941 that does not. The authors have constructed a measurement system for the testing of the cyanobacteria in water over a period of up to 40 days. After some pre-processing to remove the variation associated with running the electronic nose in ambient air, the two different strains, and their growth phase, were classified with principal components analysis, multilayer perceptron (MLP), learning vector quantisation (LVQ), and fuzzy ARTMAP. The optimal MLP network was found to classify correctly 97.1% of unknown non-toxic and 100% of unknown toxic cyanobacteria. The optimal LVQ and fuzzy ARTMAP algorithms were able to classify 100% of both strains of cyanobacteria. The accuracy of MLP, LVQ and fuzzy ARTMAP algorithms with the four different growth phases of toxic cyanobacteria was 92.3%, 95.1% and 92.3%, respectively