12,342 research outputs found
Study of mechanical response in embossing of ceramic green substrate by micro-indentation
Micro-indentation test with a micro flat-end cone indenter was employed to
simulate micro embossing process and investigate the thermo-mechanical response
of ceramic green substrates. The laminated low temperature co-fired ceramic
green tapes were used as the testing material ; the correlations of indentation
depth versus applied force and applied stress at the temperatures of 25 degrees
C and 75degrees C were studied. The results showed that permanent indentation
cavities could be formed at temperatures ranging from 25 degrees C to 75
degrees C, and the depth of cavities created was applied force, temperature and
dwell time dependent. Creep occurred and made a larger contribution to the
plastic deformation at elevated temperatures and high peak loads. There was
instantaneous recovery during the unloading and retarded recovery in the first
day after indentation. There was no significant pile-up due to material flow
observed under compression at the temperature up to 75 degrees C. The plastic
deformation was the main cause for formation of cavity on the ceramic green
substrate under compression. The results can be used as a guideline for
embossing ceramic green substrates.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/handle/2042/16838
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Lattice Boltzmann in micro- and nano- flow simulations
This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.One of the fundamental difficulties in micro- and nano-flow simulations is that the
validity’s of the continuum assumption and the hydro-dynamic equations start to become questionable in this flow regime. The lower-level kinetic/molecular alternatives are often either prohibitively expensive for practical purposes or poorly justified from a fundamental perspective. The lattice
Boltzmann (LB) method, which originated from a simplistic Boolean kinetic model, is recently shown to converge asymptotically to the continuum Boltzmann-BGK equation and therefore offers a theoretically sound and computationally effective approach for micro- and nano-flow simulations. In addition, its kinetic nature allows certain microscopic physics to be modeled at the macroscopic level, leading to a highly efficient model for multiphase flows with phase transitions. With the inherent computational advantages of a lattice model, e.g., the algorithm simplicity and parallelizability, the
ease of handling complex geometry and so on, the LB method has found many applications in various areas of Computational Fluid Dynamics (CFD) and matured to the extend of commercial applications. In this talk, I shall give an introduction to the LB method with the emphasis given to the theoretical
justifications for its applications in micro- and nano-flow simulations. Some recent examples will also be reported
A Distinct Mechanism to Achieve Efficient Signal Recognition Particle (SRP)-SRP Receptor Interaction by the Chloroplast SRP Pathway
Cotranslational protein targeting by the signal recognition particle (SRP) requires the SRP RNA, which accelerates the interaction between the SRP and SRP receptor 200-fold. This otherwise universally conserved SRP RNA is missing in the chloroplast SRP (cpSRP) pathway. Instead, the cpSRP and cpSRP receptor (cpFtsY) by themselves can interact 200-fold faster than their bacterial homologues. Here, cross-complementation analyses revealed the molecular origin underlying their efficient interaction. We found that cpFtsY is 5- to 10-fold more efficient than Escherichia coli FtsY at interacting with the GTPase domain of SRP from both chloroplast and bacteria, suggesting that cpFtsY is preorganized into a conformation more conducive to complex formation. Furthermore, the cargo-binding M-domain of cpSRP provides an additional 100-fold acceleration for the interaction between the chloroplast GTPases, functionally mimicking the effect of the SRP RNA in the cotranslational targeting pathway. The stimulatory effect of the SRP RNA or the M-domain of cpSRP is specific to the homologous SRP receptor in each pathway. These results strongly suggest that the M-domain of SRP actively communicates with the SRP and SR GTPases and that the cytosolic and chloroplast SRP pathways have evolved distinct molecular mechanisms (RNA vs. protein) to mediate this communication
Entanglement dynamics of two-qubit system in different types of noisy channels
In this paper, we study entanglement dynamics of a two-qubit extended
Werner-like state locally interacting with independent noisy channels, i.e.,
amplitude damping, phase damping and depolarizing channels. We show that the
purity of initial entangled state has direct impacts on the entanglement
robustness in each noisy channel. That is, if the initial entangled state is
prepared in mixed instead of pure form, the state may exhibit entanglement
sudden death (ESD) and/or be decreased for the critical probability at which
the entanglement disappear.Comment: 11 pages, 6 figure
Robust Preparation of GHZ and W States of Three Distant Atoms
Schemes to generate Greenberger-Horne-Zeilinger(GHZ) and W states of three
distant atoms are proposed in this paper. The schemes use the effects of
quantum statistics of indistinguishable photons emitted by the atoms inside
optical cavities. The advantages of the schemes are their robustness against
detection inefficiency and asynchronous emission of the photons. Moreover, in
Lamb-Dicke limit, the schemes do not require simultaneous click of the
detectors, this makes the schemes more realizable in experiments.Comment: 5 pages, 1 fiure. Phys. Rev. A 75, 044301 (2007
Quantum correlation measure in arbitrary bipartite systems
A definition of quantum correlation is presented for an arbitrary bipartite
quantum state based on the skew information. This definition not only inherits
the good properties of skew information such as the contractivity and so on,
but also is effective and almost analytically calculated for any bipartite
quantum states. We also reveal the relation between our measure and quantum
metrology. As applications, we give the exact expressions of quantum
correlation for many states, which provides a direct support for our result.Comment: 6 pages, 2 figures. Comments are welcom
Concurrence of superposition
The bounds on concurrence of the superposition state in terms of those of the
states being superposed are studied in this paper. The bounds on concurrence
are quite different from those on the entanglement measure based on von Neumann
entropy (Phys. Rev. Lett. 97, 100502 (2006)). In particular, a nonzero lower
bound can be provided if the states being superposed are properly constrained.Comment: 4 page
Diffusion in a multi-component Lattice Boltzmann Equation model
Diffusion phenomena in a multiple component lattice Boltzmann Equation (LBE)
model are discussed in detail. The mass fluxes associated with different
mechanical driving forces are obtained using a Chapman-Enskog analysis. This
model is found to have correct diffusion behavior and the multiple diffusion
coefficients are obtained analytically. The analytical results are further
confirmed by numerical simulations in a few solvable limiting cases. The LBE
model is established as a useful computational tool for the simulation of mass
transfer in fluid systems with external forces.Comment: To appear in Aug 1 issue of PR
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