Water-stable Mn-based MOF nanosheet as robust visible-light-responsive photocatalyst in aqueous solution

Science China Chemistry - Development of visible-light-responsive metal-organic frameworks (MOFs) for promising solar energy conversion has inspired continuous interest, but it still suffers from...     

Radar studies of ionospheric dusty plasma phenomena

We discuss the influence of charged dust on radar observations in the Earth ionosphere. This region in the upper Earth atmosphere can be described as a partially ionized, low‐temperature plasma. Plasma parameters vary by orders of magnitude spatially and in time. Dust particles influence the charge balance, in some cases dusty plasma condition is met. The polar mesospheric echoes are an example of dust plasma interactions observed with radar. The mesosphere is a region where atmospheric temperature decreases with altitude and can reach frost point temperature. The formation of the polar mesospheric radar echoes involves neutral atmosphere dynamics, which is latitude dependent and it involves charged dust particles, especially icy dust that forms in the polar summer mesosphere. Charged dust can also influence incoherent scatter that results from electromagnetic waves scattering off electrons, where the electrons are coupled to other charged components. Observers rarely report charged dust signatures in the incoherent scatter spectra; we show that there is a good chance for doing so with improved observations. The incoherent scatter can possibly also be used to estimate the amount of charged dust in the direct vicinity of a meteor, as we show based on the order of magnitude considerations. This prospect of new observational results makes theoretical investigations of radio‐wave scattering in the presence of charged dust with size distributions worthwhile.     

公路隧道新型衬砌结构双孔开挖与支护方案的研究

论文以公路隧道为研究对象,取Ⅳ级围岩,利用有限元程序对台阶开挖法和环形开挖法进行了数值模拟,分析了其支护后衬砌结构的应力和变形特征.在此基础上,针对目前隧道衬砌结构在修建和运营过程中的不足,提出一种双孔支护方案,并进行了较系统的数值模拟.研究结果表明:环形开挖法的最大应力和位移明显小于台阶开挖法,双孔支护方案能很好地减小衬砌的受力和变形,为隧道的设计和施工提供一种新的思路.     

结合面静摩擦因数分形模型的建立与仿真

提出一个确定分形维数和分形粗糙度参数(G')的分形函数,并用分形函数逼近结合面的表面粗糙度.根据分形理论和改进后的尺寸分布,推导了静摩擦因数f的解析解.数字仿真结果表明,f随量纲为一的总法向载荷(P')增加而增加.当D较小或较大时,f与(P')之间存在不同的微凸和微凹弧非线性关系,D=1.2时f与(P')的关系基本上是线性的;当D较小时,f随D增加而增加;当D较大时,f随D增加而减小;f随分形粗糙度参数(G')增加而减小,随相关系数K增加而增加,随材料特性(φ)增加而增加.     

Theoretical Study on the Reaction of PCl_3/H_2 on Silicon Substrate Surface

The reaction mechanism of PCl3/H2 on silicon substrate surface （simulated by Si4 cluster） was investigated with Density Functional Theory （DFT） at the B3LYP/6-311G^＊＊ level. On silicon substrate, PCl3 firstly undergoes dissociative adsorption, and then the adsorption product reacts with H2 via a four-step multi-channel mode to give the final product PSi4 cluster. The geometries at each stationary point were fully optimized. The possible transition states were determined by vibrational mode analysis and IRC verification. And finally, the main reaction channel was given.     

氯乙醇法制备氧化铝超微粒的形态及其粒径分布

本文报道用透射电子显微镜(TEM)进行氯乙醇法制备氧化铝超微粒形态与粒径分布的研究。从实验数据和分布曲线近似得出了理论分布曲线。并分析和讨论了实验曲线和理论曲线偏离的原因以及本试样的微粒形态和粒径分布的关系。     

A complexity perspective to deploy artistic exhibits

The design for the deployment of artistic statues in an exhibition area comes from the designer's experience, and whether such a design is adequate having no simple applicable criterion. The proposed model, deploying statues (DSs) model, not only applies the fractal dimension to measure the spatial complexity as its objective but also considers the traffic flow zone, the number of DSs, the average diameter of the statue, and the minimum allowable distance of adjacent artistic statues to arrange the spatial configuration in an exhibition area. The minimal complexity (fractal dimension) is mainly focused on because exhibiting designers deem that the spatial simplicity of an exhibition area leads to comfortable vision for a visitor. Indeed, this paper describes an applicable aspect of fractals. A computational intelligence written in Fortran Program to perform the spatial arrangement of artistic statues in an exhibition area is provided, and its adaptability has been explored by pilot tests of benchmark cases. Then, a case study through visual reality deployment for the Hosanna Museum at Chiayi Taiwan is followed. This study indeed provides a valuable tool in conducting the pre-stage of thinking process for exhibiting designers in deploying exhibits.     

A least-squares finite element method for solving the polygonal-line arc-scattering problem

This paper is concerned with the scattering problem of a polygonal-line arc. We solve this polygonal-line arc-scattering problem by a least-squares finite element method. In the method, Fourier–Bessel functions is used to capture the singularities around tips and corners. A combination of fundamental solutions is used to represent the scattered field towards infinity. We also analyse the convergence and give an error estimate of the method. Numerical experiments are also presented to show the effectiveness of our method.     

Multiple parents crossover operators: A new approach removes the overlapping solutions for sequencing problems

Maintaining population diversity throughout generations of Genetic Algorithms (GAs) is key to avoid premature convergence. Redundant solutions is one cause for the decreasing population diversity. To prevent the negative effect of redundant solutions, we propose a framework that is based on the multi-parents crossover (MPX) operator embedded in GAs. Because MPX generates diversified chromosomes with good solution quality, when a pair of redundant solutions is found, we would generate a new offspring by using the MPX to replace the redundant chromosome. Three schemes of MPX will be examined and will be compared against some algorithms in literature when we solve the permutation flowshop scheduling problems, which is a strong NP-Hard sequencing problem. The results indicate that our approach significantly improves the solution quality. This study is useful for researchers who are trying to avoid premature convergence of evolutionary algorithms by solving the sequencing problems.