47,808 research outputs found
The solution of special squeeze film gas bearing problems by an improved numerical technique
Computer program for solving squeeze film gas bearing problem
Quantum interference in dirty d-wave superconductors
The local differential tunneling conductance on a Zn impurity in a disordered
d-wave superconductors is studied. Quantum interference between many impurities
leads to definitive quasiparticle spectra. We suggest that an elaborate
analysis on impurity-induced spectra with quantum interference effect included
may be able to pin down the sign and strength of the scattering potential of a
Zn impurity in low density limit. Numerical simulations calculated with
appropriately determined impurity parameters are in satisfactory agreement with
the observations from scanning tunneling microscopy (STM) experiments even in
subtle details
In situ correction of liquid meniscus in cell culture imaging system based on parallel Fourier ptychographic microscopy (96 Eyes)
We collaborated with Amgen and spent five years in designing and fabricating next generation multi-well plate imagers based on Fourier ptychographic microscopy (FPM). A 6-well imager (Emsight) and a low-cost parallel microscopic system (96 Eyes) based on parallel FPM were reported in our previous work. However, the effect of liquid meniscus on the image quality is much stronger than anticipated, introducing obvious wavevector misalignment and additional image aberration. To this end, an adaptive wavevector correction (AWC-FPM) algorithm and a pupil recovery improvement strategy are presented to solve these challenges in situ. In addition, dual-channel fluorescence excitation is added to obtain structural information for microbiologists. Experiments are demonstrated to verify their performances. The accuracy of angular resolution with our algorithm is within 0.003 rad. Our algorithms would make the FPM algorithm more robust and practical and can be extended to other FPM-based applications to overcome similar challenges
The induced representations of Brauer algebra and the Clebsch-Gordan coefficients of SO(n)
Induced representations of Brauer algebra from with are discussed. The induction coefficients
(IDCs) or the outer-product reduction coefficients (ORCs) of with up to a normalization factor are
derived by using the linear equation method. Weyl tableaus for the
corresponding Gel'fand basis of SO(n) are defined. The assimilation method for
obtaining CG coefficients of SO(n) in the Gel'fand basis for no modification
rule involved couplings from IDCs of Brauer algebra are proposed. Some
isoscalar factors of for the resulting irrep
with
$\sum\limits_{i=1}^{4}\lambda_{i}\leq .Comment: 48 pages latex, submitted to Journal of Phys.
Upper-critical dimension in a quantum impurity model: Critical theory of the asymmetric pseudogap Kondo problem
Impurity moments coupled to fermions with a pseudogap density of states
display a quantum phase transition between a screened and a free moment phase
upon variation of the Kondo coupling. We describe the universal theory of this
transition for the experimentally relevant case of particle-hole asymmetry. The
theory takes the form of a crossing between effective singlet and doublet
levels, interacting with low-energy fermions. Depending on the pseudogap
exponent, this interaction is either relevant or irrelevant under
renormalization group transformations, establishing the existence of an
upper-critical "dimension" in this impurity problem. Using perturbative
renormalization group techniques we compute various critical properties and
compare with numerical results.Comment: 4 pages, 2 figs, (v2) title changed, log corrections for r=1 adde
Spherical squeeze-film hybrid bearing with small steady-state radial displacement
Spherical squeeze-film hybrid bearing with small steady-state radial displacement analysi
Josephson Effect in Pb/I/NbSe2 Scanning Tunneling Microscope Junctions
We have developed a method for the reproducible fabrication of
superconducting scanning tunneling microscope (STM) tips. We use these tips to
form superconductor/insulator/superconductor tunnel junctions with the STM tip
as one of the electrodes. We show that such junctions exhibit fluctuation
dominated Josephson effects, and describe how the Josephson product IcRn can be
inferred from the junctions' tunneling characteristics in this regime. This is
first demonstrated for tunneling into Pb films, and then applied in studies of
single crystals of NbSe2. We find that in NbSe2, IcRn is lower than expected,
which could be attributed to the interplay between superconductivity and the
coexisting charge density wave in this material.Comment: 3 pages, 2 figures. Presented at the New3SC-4 meeting, San Diego,
Jan. 16-21 200
- …