5,528 research outputs found
Design and Focused Ion Beam Fabrication of Single Crystal Diamond Nanobeam Cavities
We present the design and fabrication of nanobeam photonic crystal cavities
in single crystal diamond for applications in cavity quantum electrodynamics.
First, we describe three-dimensional finite-difference time-domain simulations
of a high quality factor (Q ~ 10^6) and small mode volume (V ~ 0.5
({\lambda}/n)^3) device whose cavity resonance corresponds to the zero-phonon
transition (637nm) of the Nitrogen-Vacancy (NV) color center in diamond. This
high Q/V structure, which would allow for strong light-matter interaction, is
achieved by gradually tapering the size of the photonic crystal holes between
the defect center and mirror regions of the nanobeam. Next, we demonstrate two
different focused ion beam (FIB) fabrication strategies to generate thin
diamond membranes and nanobeam photonic crystal resonators from a bulk crystal.
These approaches include a diamond crystal "side-milling" procedure as well as
an application of the "lift-off" technique used in TEM sample preparation.
Finally, we discuss certain aspects of the FIB fabrication routine that are a
challenge to the realization of the high-Q/V designs
An improved perturbation approach to the 2D Edwards polymer -- corrections to scaling
We present the results of a new perturbation calculation in polymer
statistics which starts from a ground state that already correctly predicts the
long chain length behaviour of the mean square end--to--end distance , namely the solution to the 2~dimensional~(2D) Edwards model.
The thus calculated is shown to be convergent in ,
the number of steps in the chain, in contrast to previous methods which start
from the free random walk solution. This allows us to calculate a new value for
the leading correction--to--scaling exponent~. Writing , where in 2D,
our result shows that . This value is also supported by an
analysis of 2D self--avoiding walks on the {\em continuum}.Comment: 17 Pages of Revtex. No figures. Submitted to J. Phys.
The Van der Waals interaction of the hydrogen molecule - an exact local energy density functional
We verify that the van der Waals interaction and hence all dispersion
interactions for the hydrogen molecule given by: W"= -{A/R^6}-{B/R^8}-{C/R^10}-
..., in which R is the internuclear separation, are exactly soluble. The
constants A=6.4990267..., B=124.3990835 ... and C=1135.2140398... (in Hartree
units) first obtained approximately by Pauling and Beach (PB) [1] using a
linear variational method, can be shown to be obtainable to any desired
accuracy via our exact solution. In addition we shall show that a local energy
density functional can be obtained, whose variational solution rederives the
exact solution for this problem. This demonstrates explicitly that a static
local density functional theory exists for this system. We conclude with
remarks about generalising the method to other hydrogenic systems and also to
helium.Comment: 11 pages, 13 figures and 28 reference
A nature-derived, flexible and three dimensional (3D) nano-composite for chronic wounds pH monitoring
Current technologies on conductive carbon aerogels are merely for application of super-capacitors, anodes of lithium ion batteries and electrocatalysts. To our best knowledge, carbon nanofibre (CNF) aerogels in biomedical application of chronic wound monitoring have not been reported yet. In this paper, we proposed a chronic wounds pH sensor, which is based on 3D free-standing conductive CNF aerogel derived from pyrolyzed bacterial cellulose (p-BC) as conducting substrate and it is incorporated with flexible and proton-selective PDMS/PANI composite. The resulted p-BC/PDMS/PANI nanocomposite is soft, flexible, and can exhibit near Nernst limit pH sensitivity (~−50.4 mV/pH) in pH buffer solution, and −29 mV/pH in in vitro simulated wound fluid. This renders its applications in flexible bio-sensors and smart wound dressings
Low-energy excitations of the one-dimensional half-filled SU(4) Hubbard model with an attractive on-site interaction: Density-matrix renormalization-group calculations and perturbation theory
We investigate low-energy excitations of the one-dimensional half-filled
SU(4) Hubbard model with an attractive on-site interaction U < 0 using the
density matrix renormalization group method as well as a perturbation theory.
We find that the ground state is a charge density wave state with a long range
order. The ground state is completely incompressible since all the excitations
are gapful. The charge gap which is the same as the four-particle excitation
gap is a non-monotonic function of U, while the spin gap and others increase
with increasing |U| and have linear asymptotic behaviors.Comment: 4 pages, 3 figures, submitte
Vibration signature analysis of multistage gear transmission
An analysis is presented for multistage multimesh gear transmission systems. The analysis predicts the overall system dynamics and the transmissibility to the gear box or the enclosed structure. The modal synthesis approach of the analysis treats the uncoupled lateral/torsional model characteristics of each stage or component independently. The vibration signature analysis evaluates the global dynamics coupling in the system. The method synthesizes the interaction of each modal component or stage with the nonlinear gear mesh dynamics and the modal support geometry characteristics. The analysis simulates transient and steady state vibration events to determine the resulting torque variations, speeds, changes, rotor imbalances, and support gear box motion excitations. A vibration signature analysis examines the overall dynamic characteristics of the system, and the individual model component responses. The gear box vibration analysis also examines the spectral characteristics of the support system
Effect of Sodium Treatment on the Performance of Electrostatic Spray Assisted Vapour Deposited Copper-poor Cu(In,Ga)(S,Se)2 Solar Cells
In our work, eco-friendly, non-vacuum and low cost Electrostatic Spray Assisted Vapour Deposition (ESAVD) method has been used to produce Cu(In,Ga)(S,Se) 2 (CIGS) solar cells. Copper (Cu) deficient (Cu/In + Ga = 0.76) CIGS films were designed to avoid the rather dangerous KCN treatment step for the removal of conductive minor phases of Cu 2 S/Cu 2 Se. A simple sodium (Na) treatment method was used to modify the morphology and electronic properties of the absorber and it clearly improved the solar cell performance. The SEM and XRD results testified a slightly increase of the grain size and (112) crystal orientation in the Na-incorporated CIGS thin films. From the Mott-schottky results, it can be seen that the functions of the Na treatment in our non-vacuum deposited CIGS are mainly used for defect passivation and reduction of charge recombination. Photovoltaic characteristics and j-V curve demonstrated that the dipping of CIGS films in 0.2 M NaCl solution for 20 minutes followed by selenization at 550 °C under selenium vapor resulted in the optimum photovoltaic performance, with j sc , V oc , FF and η of the optimized solar cell of 29.30 mA cm -2 , 0.564 V, 65.59% and 10.83%, respectively
Unsupervised Domain Adaptation for 3D Keypoint Estimation via View Consistency
In this paper, we introduce a novel unsupervised domain adaptation technique
for the task of 3D keypoint prediction from a single depth scan or image. Our
key idea is to utilize the fact that predictions from different views of the
same or similar objects should be consistent with each other. Such view
consistency can provide effective regularization for keypoint prediction on
unlabeled instances. In addition, we introduce a geometric alignment term to
regularize predictions in the target domain. The resulting loss function can be
effectively optimized via alternating minimization. We demonstrate the
effectiveness of our approach on real datasets and present experimental results
showing that our approach is superior to state-of-the-art general-purpose
domain adaptation techniques.Comment: ECCV 201
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