The effect of pre-pattern on the morphology and growth speed of TiO2 nanotube

In this work, we presented a new method which directly acts on the surface of the Ti sheet by mechanical micro-etching using a grating ruling engine. The effect of the pre-pattern on the morphology and growth speed of TiO₂ nanostructure formed on the Ti sheet with the traditional anodization method was investigated. A novel wall structure was observed and the growth speed of TiO₂ nanotube (NT) was greatly affected by the pre-pattern. The wall structure increases the surface-to-volume ratio of the nanotube arrays. The new method provided the possibility of further optimization of fast growth of TiO₂ nanostructure and improving the efficiency of dye-sensitized solar cell (DSSC) and photocatalysis.     

Operators on the orthogonal complement of the Dirichlet space(Ⅱ)

In this paper we first prove that a dual Hankel operator R φ on the orthogonal complement of the Dirichlet space is compact for φ∈ W 1,∞(D),and then that a semicommutator of two Toeplitz operators on the Dirichlet space or two dual Toeplitz operators on the orthogonal complement of the Dirichlet space in Sobolev space is compact.We also prove that a dual Hankel operator R φ with φ∈ W 1,∞(D) is of finite rank if and only if B φ is orthogonal to the Dirichlet space for some finite Blaschke product B,and give ...     

高考（北京卷）物理命题特色与趋势——面向新课程高考改革探索（下篇）

4 面向新课程改革物理试题的发展趋势 "创新是一个民族的灵魂".培养能力、激发研究和创新意识是物理教育的根本,也是新课标的要求,现阶段深化高考考试内容改革有利于培养学生的创新意识和实践能力,有利于选拔创新型人才,有利于学生的全面健康发展.     

Globally solving a nonlinear UAV task assignment problem by stochastic and deterministic optimization approaches

In this paper, we consider a task allocation model that consists of assigning a set of m unmanned aerial vehicles (UAVs) to a set of n tasks in an optimal way. The optimality is quantified by target scores. The mission is to maximize the target score while satisfying capacity constraints of both the UAVs and the tasks. This problem is known to be NP-hard. Existing algorithms are not suitable for the large scale setting. Scalability and robustness are recognized as two main issues. We deal with these issues by two optimization approaches. The first approach is the Cross-Entropy (CE) method, a generic and practical tool of stochastic optimization for solving NP-hard problem. The second one is Branch and Bound algorithm, an efficient classical tool of global deterministic optimization. The numerical results show the efficiency of our approaches, in particular the CE method for very large scale setting.     

Global convergence of proximal iteratively reweighted algorithm

In this paper, we investigate the convergence of the proximal iteratively reweighted algorithm for a class of nonconvex and nonsmooth problems. Such problems actually include numerous models in the area of signal processing and machine learning research. Two extensions of the algorithm are also studied. We provide a unified scheme for these three algorithms. With the Kurdyka–?ojasiewicz property, we prove that the unified algorithm globally converges to a critical point of the objective function.     

Diastereoselective Coupling of Chiral Acetonide Trisubstituted Radicals with Alkenes

The stereochemical outcome of reactions of chiral nucleophilic trisubstituted acetonide radicals with electron‐deficient alkenes is dictated by a delicate balance between destabilizing non‐bonding interactions and stabilizing hydrogen‐bonding between substituents on the α and β carbons.     

Study of a narrowband reflection filter with multi-channels

Reflection filters have various applications in optical communication and other systems.In this letter,we propose a narrowband high-reflection filter composed of dielectric and metallic layers,in which an optimized filter combined with an admittance-matching layer with broad stop band is achieved.The structure can be expressed as Sub ｜ （HL）13H2L（HL）313Cr0.84H ｜ air,with full-width at half-maximum （FWHM） bandwidth of 2.5 nm.Based on this structure,reflection filters with multi-peaks are presented,and the law of distribution of peak positions is drawn.     

变频空调制冷系统流量调节性能分析和实验研究

通过实验分析不同膨胀阀开度和压缩机频率下系统性能。过热度在‘0’点及前后情况下,制冷系统性能及回油状况随膨胀阀开度调节,会出现较大变化。且在过热度为‘0’时系统制冷量和能效比最高。同时对不同频率下系统性能参数变化规律尤其是换热器效率影响进行分析。给出膨胀阀开度和压缩机变转速联合调节在系统性能最优状态下调节策略。