基于Retinex理论与概率非局部均值的红外图像增强方法

针对传统红外图像增强算法中细节模糊及过度增强的问题,提出了一种基于Retinex理论与概率非局部均值相结合的红外图像增强方法.首先通过单尺度Retinex方法调整图像中过暗与过亮部分的灰度级;然后利用概率非局部均值对图像进行分解处理得到基本层与细节层,对基本层采用直方图均衡化拉伸对比度,对细节层采用非线性函数进行增强;最后,将不同层次的结果融合得到对比度与细节增强的红外图像.用该方法对多组不同场景的红外图像进行仿真实验,并将其与多种增强方法进行主、客观对比分析,结果表明所提方法在红外图像的细节及对比度增强方面都获得了更好的效果.     

Bio-safety assessment of carbon quantum dots,N-doped and folic acid modified carbon quantum dots: A systemic comparison

The carbon quantum dots(CQDs) and their functionalized materials are promising in biomedical field because of their unique properties;meanwhile,a growing concern has been raised about the potential toxicity of these modified materials in biosystem.In this study,we synthesized original CQDs and two common functionalized CQDs including N-doped CQDs(NCQDs) and folic acid-modified CQDs(FACQDs),and compared the toxicity and biocompatibility with each other in vitro and in vivo.L929,C6 and normal cell MDCK were selected to detect the adverse reaction of these materials in vitro.No acute toxicity or obvious changes were noted from in vitro cytotoxicity studies with the dose of these CQD materials increasing to a high concentration at 1 mg/mL.Among these materials,the FA-CQDs show a much lower toxicity.Moreover,in vivo toxicity studies were performed on the nude mice for 15 days.The experimental animals in 10 or 15 mg/kg groups were similar with animals treated by phosphate buffer solution(PBS) after 15 days.The results of the multifa rious biochemical parameters also suggest that the functionalized products of CQDs do not influence the biological indicators at feasible concentration.Our findings in vitro and in vivo through toxicity tests demonstrate that CQDs and their modified materials are safe for future biological applications.     

Time-resolved photoluminescence study of excited states in nanostructured melanin

Abstract

Time resolved emission spectra (TRES), 3D maps of photoluminescence excitation-emission (PLE maps), 3D maps of TRES, and kinetics of photoluminescence (PL) spectra of natural and synthetic melanin, as well as melanin composites with surfactant, sodium dodecyl benzenesulfonate, have been studied. The kinetics of PL and TRES for the melanin and the composites were investigated at low temperatures that allowed to discuss melanin’s intermolecular complexation, nano-aggregation and formation of charge transfer states. Particularly, the radiation of Frenkel excitons from fragments of different degrees of conjugation that are the parts of molecular nanodisks of melanin is observed. Furthermore, charge transfer excitons (CT-excitons) can be formed and observed at both room and helium temperatures. Some bands in the PL spectra of melanin, depending on temperature, behave like excimer radiation. The studies are aiming to understand the electronic properties of various melanins, particularly natural ones.     

新组合模型在光电功率预测中的应用

为提高光伏预测要求的精准性,文章提出一种新算法将神经网络和ARMA算法改进组合,构成NEW ARMA-BP模型算法.以某30兆瓦的光伏电站采集的输出功率为输入样本,基于ARMA和BP神经网络算法在Matlab环境下依次搭建了相应的预测模型,预估光伏短期输出量.采用"误差正态检验图"判断基于两种不同算法的误差水平,依据两种单模型预测误差,运用所提出的新方法计算权值并获得新的预测值.基于Matlab的仿真结论验证了组合预测在光伏输出预测领域的适用性.     

Combined Spectroscopic and TD-DFT Analysis to Elucidate Substituent and Acidochromic Effects in Organic Dyes: A Case Study on Amino- versus Nitro-Substituted 2,4-Diphenylquinolines

A combined spectroscopic and TD-DFT case study was performed, to identify a robust method to calculate the complex near UV/Vis absorption spectra of various amino- vs. nitro-substituted 2,4-diphenylquinolines, which vary strongly under neutral and successively acidic conditions. For this, different DFT functionals were tested for geometry optimization and the TD part to calculate the neutral and different protonated species in a fast screening approach, i. e. using single point calculations in an implicit solvent. Offset-corrected M06HF, hitherto only applied to polymers, was identified as a suitable method to reproduce the absorption spectra in a reasonable fashion for all different substitution pattern and all different protonated species at different pH values; moreover, the method properly predicts the energetic ordering of low-lying n-π* and ππ* transitions, which is decisive for the non-/emissive nature of the different compounds. In all, this might provide a valuable tool for computer-aided design of related classes of compounds.     

Energy conditions of the f(T,B) gravity dark energy model with the validity of thermodynamics

In this article, the analysis of Tsallis holographic dark energy(which turns into holographic dark energy for a particular choice of positive non-additivity parameter δ) in modified f(T, B) gravity with the validity of thermodynamics and energy conditions for a homogeneous and isotropic FLRW Universe has been studied. The enlightenment of the field equation towards f(T,B)=αT~m+βB~n, made possible by the fact that the model is purely accelerating,corresponds to q=-0.54(Mamon and Das 2017 Eur. Phys.J.C 77 49). The generalized second law of thermodynamics is valid not only for the same temperature inside the horizon, but also for the apparent horizon for a change in temperature. The essential inspiration driving this article is to exhibit the applicability that the holographic dark energy achieved from standard Tsallis holographic dark energy and the components acquired from f(T, B) gravity are identical for the specific bounty of constants. The analysis of energy conditions confirms that the weak energy condition and the null energy condition are fulfilled throughout the expansion, while violation of the strong energy condition validates the accelerated expansion of the Universe.With the expansion, the model becomes a quintessence dominated model. The dominant energy condition is not observed initially when the model is filled with genuine baryonic matter,whereas it appears when the model is in the quintessence dominated era.     

Unidimensional continuous-variable quantum key distribution with discrete modulation

In this paper, we proposed an unidimensional continuous-variable quantum key distribution (CV-QKD) protocol with discrete modulation, which waives the necessity in one of the quadrature modulations and further simplified the implementation of the CV-QKD protocol. On the basis of the Heisenberg uncertainty relation, we analyze the boundary between the unphysical and physical region. Besides, we utilize a novel proof approach to achieve a lower bound valid of transmission distance. This scheme shows an available method to further simplified the implementation of the QKD.     

Emergence of a non-Fowler-Nordheim-type behavior for a general planar tunneling barrier

In this work we investigate a generalized tunneling barrier for planar emitters at zero-temperature. We present the evidence of the emergence of a non-Fowler-Nordheim-type general behavior for the field emission current density in the case that the Fermi energy (μ) is comparable with or smaller that the decay width ($d_F$). Therefore, for some non-metals or materials that have very small Fermi energy the standard Fowler-Nordheim-type theory may require a correction. In the opposite regime, i.e., for μ much larger that $d_F$, we confirm that the conventional theory is suitable for metals.     

Wettability and surface energy of parylene F deposited on PDMS

For the first time, the wettability and surface energy of parylene F were investigated. The results showed that parylene F had a hydrophobic surface with an eigen water contact angle of 104.7 ± 0.6°. We found that 3.5 μl probe liquid was an optimal value for the contact angle measurement of parylene F. Moreover, we found that the Lifshitz–van der Waals/acid–base approach was unsuitable for determining the surface energy of parylene F, whereas the Owens–Wendt–Kaelble approach and the limitless liquid–solid interface wetting system were compatible. The surface energy of parylene F was estimated to be 27.06 mJ/m² (Owens–Wendt–Kaelble) and 40.41 mJ/m² (Limitless liquid-solid interface wetting system). Furthermore, this investigation also provided a reference for the applications of empirical and physics-based semi-empirical approaches for the estimation of surface energy.     

窄线宽光纤激光器在1030 nm波段实现3 kW近衍射极限输出

基于大模场面积掺镱光纤搭建了全光纤1030 nm高功率窄线宽光纤激光主振荡功率放大系统,实现了3004 W的最高功率输出,斜率效率69.27%,是目前报道的输出功率最高的1030 nm波段近衍射极限光纤激光器。最高输出功率时,x,y方向的光束质量因子分别为1.169,1.174,3 dB光谱宽度为0.18 nm,放大自发辐射抑制比达到37 dB。