Improving signal-to-noise ratio performance of compressive imaging based on spatial correlation

In this paper, compressive imaging based on spatial correlation (CISC), which uses second-order correlation with the measurement matrix, is introduced to improve the signal-to-noise ratio performance of compressive imaging (CI). Numerical simulations and experiments are performed as well. Referred to the results, it can be seen that CISC performs much better than CI in three common noise environments. This provides the great opportunity to pave the way for real applications.     

Cantor-type cylindrical-coordinate method for differential equations with local fractional derivatives

In this Letter, we propose to use the Cantor-type cylindrical-coordinate method in order to investigate a family of local fractional differential operators on Cantor sets. Some testing examples are given to illustrate the capability of the proposed method for the heat-conduction equation on a Cantor set and the damped wave equation in fractal strings. It is seen to be a powerful tool to convert differential equations on Cantor sets from Cantorian-coordinate systems to Cantor-type cylindrical-coordinate systems.     

IPDA激光雷达数据反演快速精确优化算法

研究了积分路径差分吸收(IPDA)激光雷达中采用洛伦兹线型代替伏格特线型对机载平台探测CO₂柱浓度精度的影响。建立仿真模型，讨论两种线型在数据反演中对温度和气压的敏感性，以及探测相对误差变化随飞行高度的变化。结果表明：伏格特和洛伦兹线型得到的吸收截面，温度和气压敏感性，相对随机误差分别为0.860%，-0.703%和0.224%，基本没有差别，但是洛伦兹线型可以有效地提高光谱参数计算效率。机载IPDA激光雷达采用洛伦兹线型可以快速高精度反演飞行路径上CO₂柱浓度，降低了对系统计算能力的要求，有助于实现在飞期间数据实时反演和分析，以及实施针对突发事件的飞行规划，同时也有助于进一步实现机载激光雷达系统的小型化和集成化。     

Spatiotemporal soliton clusters in strongly nonlocal media with variable potential coefficients

We study analytically and numerically spatiotemporal solitons in three-dimensional strongly nonlocal nonlinear media. A broad class of exact self-similar solutions to the strongly nonlocal Schrödinger equation with variable potential coefficients has been obtained. We find robust soliton cluster solutions of the accessible type, constructed with the help of Kummer and Hermite functions. They are characterized by the set of three quantum numbers. Dynamical features of these spatiotemporal accessible solitons are discussed. The validity of the analytical solutions and their stability is verified by means of direct numerical simulations.     

Solvent replacement to thermo‐responsive nanoparticles from long‐subchain hyperbranched PSt grafted with PNIPAM for encapsulation

Long‐subchain hyperbranched polystyrene (lsc‐hp PSt) with uniform subchain length was obtained through copper‐catalyzed azide‐alkyne cycloaddition click chemistry from seesaw macromonomer of PSt having one alkynyl group anchored at the chain centre and two azido group attached to both chain ends [alkynyl‐(PSt‐N₃)₂]. After precipitation fraction, different portions of lsc‐hp PSt having narrow overall molecular weight distribution were obtained for further grafting with alkynyl‐capped poly(N‐isopropylacrylamide) (alkynyl‐PNIPAM), which was obtained via single‐electron transfer living radical polymerization of NIPAM with propargyl 2‐bromoisobutyrate as the initiator and grafted onto the peripheral azido groups of lsc‐hp PSt via click chemistry. Thus, amphiphilic lsc‐hp PSt grafted with PNIPAM chains (lsc‐hp PSt‐g‐PNIPAM) was obtained and would have star‐like conformation in tetrahydrofuran (THF). By replacing THF with water, lsc‐hp PSt‐g‐PNIPAM was dissolved at molecular level in aqueous solution due to the hydrophilicity of PNIPAM and exhibited thermal induced shrinkage of PNIPAM arms. The water‐insoluble lsc‐hp PSt would collapse densely and could be served as a reservoir to absorb hydrophobic chemicals in aqueous solution. The influence of overall molecular weight of lsc‐hp PSt on the absorption of pyrene was studied. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Laser-induced circular dichroism by a resonant circularly polarized pump optical field

The paper presents and discusses a generalization of the equations of laser-induced circular dichroism (LICD) derived for linear molecules. LICD for freely rotating molecules by a resonant circularly-polarized pump field is an optical analogue of the Faraday effect in isotropic media. Its fundamental formulae and existent conditions have been deduced using the density matrix theory with a two-level model and time-reversal arguments. The antisymmetric rotational polarizability and LICD of symmetric and asymmetric top molecules are studied concretely using perturbation theory and angular momentum algebra. The order of magnitude of LICD and the physical phenomena closely related with it have been discussed. The results show that the LICD effect is exhibited by all freely rotating molecules and may provide useful information on optical activity and antisymmetric polarizability.     

Study on alpha cup technique for monitoring of soil radon levels

Determination of radon concentrations in soil usually requires the accumulation of many measurements over a large area. In this study, an alpha cup technique that provides a cumulative result for adsorption of radon progeny over time was investigated. In addition, the performance of measurements were evaluated. To avoid the impacts of temperature and humidity, a new arithmetic correction was explored. Finally, we also investigated the effect of burial time of the alpha cup on soil radon measurements. Experiments showed that the alpha cup technique can satisfy the demands of soil radon measurements in efficiency, accuracy, reliability, and stability.