Elastic model scale and material for underwater structure of cross-sea bridge

With the bridge construction gradually from inland to coast and offshore, underwater structure of cross-sea bridge can encounter more complex hydrodynamic action. When elastic model is used to simulate the hydrodynamic response of underwater structure, the model scale and model material is the first problem must be solved. Based on principle of similitude, elastic model should meet the geometric similarity, kinematic similarity and mechanical similarity. Formula derivation gives the scale conditions for elastic model are as follows, geometric scale (Lr) equals elastic modulus scale (Er) and density scale (??r) equals 1. Then, how to find a material with same density and the elastic modulus is 1/ Lr of prototype is the key to make a model

Influence of substrate heating on hole geometry and spatter area in femtosecond laser drilling of silicon

The objective of this research is to evaluate the effects of the hole geometry and the spatter area around the drilled hole by femtosecond laser deep drilling on silicon with various temperatures. Deep through holes were produced on single crystal silicon wafer femtosecond laser at elevated temperatures ranging from 300K to 873K in a step of 100K. The laser drilling efficiency is increased by 56% when the temperature is elevated from 300K to 873K. The spatter area is found to continuously decrease with increasing substrate temperature. The reason for such changes is discussed based on the enhanced laser energy absorption at the elevated temperature.open0

Influence of stator and rotor pole number combinations on the electromagnetic performance of stator slot-opening PM hybrid-excited machine

A new type of three-phase stator hybrid excited machine with permanent magnets (PMs) located at the slot openings of field winding slots is presented in this paper. It has the advantage of good flux regulation capability due to the field excitation. The machines with different stator/rotor pole combinations, i.e., 6-stator pole and 7-/8-/10-/11-/13-/14-rotor poles, have been comparatively investigated in terms of the open-circuit and on-load characteristics, as well as the influence of dc current and the unbalanced magnetic forces. The 2-D finite element analysis (FEA) has been employed for analysis and optimization of the machines together with experimental validation

The role of robotics in computer controlled polishing of large and small optics

Following formal acceptance by ESO of three 1.4m hexagonal off-axis prototype mirror segments, one circular segment, and certification of our optical test facility, we turn our attention to the challenge of segment mass-production. In this paper, we focus on the role of industrial robots, highlighting complementarity with Zeeko CNC polishing machines, and presenting results using robots to provide intermediate processing between CNC grinding and polishing. We also describe the marriage of robots and Zeeko machines to automate currently manual operations; steps towards our ultimate vision of fully autonomous manufacturing cells, with impact throughout the optical manufacturing community and beyond

Influence of magnetic saturation and rotor eccentricity on back EMF of novel hybrid-excited stator slot opening permanent magnet machine

This paper introduces a novel hybrid-excited stator slot opening permanent magnet (PM) machine (HSSPMM). The operation principle of the machine is described and the effects of rotor eccentricity and magnetic saturation due to PMs on electromagnetic performance, with particular emphasis on back electromotive force (EMF), are analyzed by finite element method (FEM). It shows that different from the conventional PM machines, the open-circuit back EMF in this novel HSSPMM should be zero but may become non-zero if significant magnetic saturation exists, and furthermore, the rotor eccentricity has a detrimental effect on the waveforms, amplitudes, and symmetries of three-phase back EMFs, as confirmed by FEM and tests

The aminobisphosphonate pamidronate controls influenza pathogenesis by expanding a γδ T cell population in humanized mice

As shown in humanized mice, a population of Vγ9Vδ2 T cells can reduce the severity and mortality of disease caused by infection with human and avian influenza viruses

The transition form factors for semi-leptonic weak decays of J/ψJ/\psi in QCD sum rules

Within the Standard Model, we investigate the semi-leptonic weak decays of $J/\psi$. The various form factors of $J/\psi$ transiting to a single charmed meson ($D^{(*)}_{(d,s)}$) are studied in the framework of the QCD sum rules. These form factors fully determine the rates of the weak semi-leptonic decays of $J/\psi$ and provide valuable information about the non-perturbative QCD effects. Our results indicate that the decay rate of the semi-leptonic weak decay mode $J/\psi \to D^{(*)-}_{s}+e^{+}+\nu_{e}$ is at order of $10^{-10}$.Comment: 28 pages, 6 figures, revised version to be published in Eur.Phys.J.