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101.
We propose a complete superradiant and subradiant states that can be manipulated and prepared in a three-dimensional atomic array. These subradiant states can be realized by absorbing a single photon and imprinting the spatially-dependent phases on the atomic system. We find that the collective decay rates and associated cooperative Lamb shifts are highly dependent on the phases we manage to imprint, and the subradiant state of long lifetime can be found for various lattice spacings and atom numbers. We also investigate both optically thin and thick atomic arrays, which can serve for systematic studies of super- and sub-radiance. Our proposal offers an alternative scheme for quantum memory of light in a three-dimensional array of two-level atoms, which is applicable and potentially advantageous in quantum information processing. 相似文献
102.
In this paper we study the locally optimal geodesic ball packings with equal balls to the S 2 × R space groups having rotation point groups and their generators are screw motions. We determine and visualize the densest simply transitive geodesic ball arrangements for the above space groups; moreover, we compute their optimal densities and radii. The densest packing is derived from the S 2 × R space group 3qe. I. 3 with packing density ≈0.7278. E. Molnár has shown in [9] that the Thurston geometries have an unified interpretation in the real projective 3-sphere \({\mathcal{PS}^3}\). In our work we shall use this projective model of S 2 × R geometry. 相似文献
103.
Time-reversed speech has been known to effectively mask information for speech privacy applications. However, the annoyance and distraction caused by the time-reversed speech-like masking sound is higher than other masking sound. This study investigates the effects of adding artificial reverberation to the time-reversed speech. Subjective listening tests have been conducted to measure the intelligibility of target speech, annoyance and distraction caused by the masking sound. The experimental results suggest that adding artificial reverberation to a speech-like masking sound has a significant effect to reduce the annoyance level while maintaining the masking effectiveness of the original masking sound. A trend was also observed that the addition of artificial reverberation could reduce the level of distraction caused by the masking sound. 相似文献
104.
A new cloud vapor zone (CVZ)-based headspace solid-phase microextraction (HS-SPME) technique has been demonstrated with the
capability of heating the sample matrix and simultaneously cooling the sampling zone. A bi-temperature-controlled (BTC) system,
allowing 10 mL of test sample heating and headspace external-cooling, was employed for the CVZ formation around the SPME-fiber
sampling area. In the CVZ procedure, the heated headspace vapor undergoes a sudden cooling near the SPME to form a dense cloud
of analyte–water vapor, which is helpful for adsorption or absorption of the analyte. The device was evaluated for the quantitative
analysis of aqueous chlorothalonil. Parameters influencing sampling efficiency, e.g., SPME fiber coating, SPME sampling temperature
and time, solution modifier, addition of salt, sample pH, and temperature, were investigated and optimized thoroughly. The
proposed BTC-HS-SPME method afforded a best extraction efficiency of above 94% accuracy (less than 4.1% RSD, n = 7) by using the PDMS fiber to collect chlorothalonil in the headspace at 5 °C under the optimized condition, i.e., heating
sample solution (added as 10% ethylene glycol and 30% NaCl, at pH 7.0) at 130 °C for 15 min. The detection was linear from
0.01 to 80 μg L−1 with a regression coefficient of 0.9998 and had a detection limit of 3.0 ng L−1 based on S/N = 3. Practical application was demonstrated by analyzing chlorothalonil in farm water samples with promising
results and recoveries. The approach provided a very simple, fast, sensitive, and solvent-free procedure to collect analytes
from aqueous solution. The approach can provide a new platform for other sensitive HS-SPME assays. 相似文献
105.
Sample preparation is the critical step in analysis of residues in biological samples. The development of a ragged method is time-consuming, because a huge number of parameters must be checked. To reduce the number of experiments Taguchi's method was applied in the sample preparation of metabolites of albendazole. During the experiments 11 controllable and 7 noise factors were investigated. From the influence of controllable and noise factors on recovery and standard deviation, conditions for the sample preparation and recovery could be concluded with high accuracy and reliability. 相似文献
106.
Xuezhong Jiang Greg Philan Brenden Carlson Sen Liu Larry Dalton Alex K-Y. Jen 《Macromolecular Symposia》2002,186(1):171-176
Pure and efficient red light-emitting diodes based on novel europium (Eu) and osmium (Os) complexes were demonstrated. The Eu complex, with dendron substituted diketone ligands, exhibits high photoluminescence efficiency of 45%. When a copolymer containing carbazole and 1,3,4-oxadiazole groups was used as the host, narrow electroluminescence at 617 nm was achieved, with a full width at half maximum of 4 nm and a maximum external quantum efficiency (η) of 0.80%. The Os complex shows pure red emission peaking at 650 nm. The Commission Internationale de l'Eclairage (CIE) chromaticity coordinates (x, y) are (0.65, 0.33). Maximum η and brightness achieved were 0.82% and 590 cd/m2, respectively. 相似文献
107.
Wu‐Jang Huang Feng‐Chih Chang Peter Po‐Jen Chu 《Journal of Polymer Science.Polymer Physics》2000,38(19):2554-2563
In this article, we have applied solid‐state 13C NMR techniques, cross‐polarization/magic‐angle spinning (CP/MAS), and single‐pulse 13C NMR to characterize the NB conformation of the cyclo‐olefin copolymer. The copolymers containing higher NB contents produce more NB blocks according to 13C CP/MAS spectral analysis. In addition, NB‐dyad‐based conformations are able to induce peak splitting in the region of 49–52 ppm. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2554–2563, 2000 相似文献
108.
109.
A method of automatic grid generation for complex boundaries in Cartesian co-ordinates is proposed in this paper. In addition to the Cartesian grid lines the diagonal segments are used for the approximations of complex geometries in Cartesian co-ordinates. A structured Cartesian grid is employed for the sake of the numerical simplicity and the potential of automatic grid generation. The automatic grid generation is achieved by this diagonal Cartesian method and the accuracy estimations of geometry approximations are given. The approximations of a few complex geometries, such as the multibody system in porous media, lake banks, grooved channels and spheres are shown and analyzed. The proposed method is verified by the numerical solutions of a rotated cavity flow. It is shown that the diagonal Cartesian method improves both the accuracy of geometry approximations and the numerical solution of a rotated cavity flow, comparing with the traditional saw-tooth method in which only Cartesian grid lines are utilized for geometry approximations. The stability and convergence of the proposed method is demonstrated. Finally, the application of the diagonal Cartesian method for the prediction of a grooved channel flow is presented. © 1998 John Wiley & Sons, Ltd. 相似文献
110.
Larry R. Dalton Aaron W. Harper Shajing Sun William H. Steier Robert V. Mustacich Alex K-Y. Jen 《Macromolecular Symposia》1997,116(1):135-142
The synthesis and processing of second order nonlinear optical polymeric materials for application in electro-optic devices is described with particular emphasis on (1) the synthesis and incorporation into hardened polymer lattices of chromophores characterized by large μβ (where μ is the dipole moment and β is the molecular first hyperpolarizability) values; (2) the synthesis and incorporation into hardened polymer lattices of chromophores which are capable of undergoing photo-induced conformational changes and which can be processed by new multi-color photolithography techniques into buried channel active waveguides; and (3) the processing of polymeric nonlinear optical materials appropriate for the realization of full integration with very large scale integration (VLSI) drive electronics and with silica fiber optic transmission lines. Prototype modulators have been fabricated and shown to be suitable for broadband operation from 0 to 113 GHz. Optical losses associated with waveguide wall roughness and with mode mismatch in transitioning between silica and polymeric waveguides are reduced by control of the conditions of reactive ion etching and by use of the new technique of multi-color photochemical lithography. 相似文献