一种二次型忆阻器四阶混沌电路

由HP实验室研制的无源忆阻器得到的荷控二次型忆阻器模型,与有源磁控分段线性和三次光滑忆阻器模型相比,更符合实际.利用此模型并基于蔡氏混沌电路演化而来的拓扑对偶结构设计了一种新型忆阻器四阶混沌电路.理论分析、仿真及电路实现表明,该电路具有依赖于忆阻器初始状态的复杂动力学行为,也会产生随时间和系统参数变化的状态转移等非线性动力学现象,在相轨图中出现"涡眼"和"环眼".     

随机利率下两全保险最佳年限的确定模型

寿险模型中利率的随机性问题是近几年来保险精算学中研究的热点和重点问题。本文从降低保险公司所面临风险的角度出发,在随机利率条件下给出确定两全保险的最佳年限模型。     

Morphology effects on the biofunctionalization of nanostructured ZnO

A stepwise surface functionalization methodology was applied to nanostructured ZnO films grown by metal organic chemical vapor deposition (MOCVD) having three different surface morphologies (i.e., nanorod layers (ZnO films-N), rough surface films (ZnO films-R), and planar surface films (ZnO films-P). The films were grown on glass substrates and on the sensing area of a quartz crystal microbalance (nano-QCM). 16-(2-Pyridyldithiol)-hexadecanoic acid (PDHA) was bound to ZnO films-N, -R, and -P through the carboxylic acid unit, followed by a nucleophilic displacement of the 2-pyridyldithiol moiety by single-stranded DNA capped with a thiol group (SH-ssDNA). The resulting ssDNA-functionalized films were hybridized with complementary ssDNA tagged with fluorescein (ssDNA-Fl). In a selectivity control experiment, no hybridization occurred upon treatment with non complementary DNA. The ZnO films' surface functionalization, characterized by FT-IR-ATR and fluorescence spectroscopy and detected on the nano-QCM, was successful on films-N and -R but was barely detectable on the planar surface of films-P.     

High-power ultraviolet 278 nm laser from fourth-harmonic generation of a Nd:YAG laser in CsB3O5

We demonstrate a high-power UV 278 nm laser by fourth-harmonic generation (FHG) of a 1112 nm Nd:YAG laser in a nonlinear optical (NLO) crystal CsB3O5 (CBO) for the first time, to our best knowledge. A 30 W level diode-pumped Q-switched Nd:YAG laser at 1112 nm with beam quality factor M2=1.2 was used as the fundamental light source at a pulse width of 500 ns. With an LiB3O5 crystal, the 1112 nm laser was first frequency-doubled to 556 nm with an average output power of 13.5 W. It was then frequency doubled again in a CBO crystal to obtain the FHG output at 278 nm. The maximum average output power of the 278 nm laser is up to 1.5 W. The results demonstrated that CBO crystal is a promising NLO material for UV high-power lasers below 300 nm.     

ChemInform Abstract: Synthesis,Structure, and Electronic Structure of CsAgGa2Se4.

The new title compound is prepared from a mixture of AgGaSe₂ (obtained from the elements at 900 °C, 2 d) and CsI in the molar ratio 1:2 (silica tube, Ar, 800 °C, 48 h).     

高中学生提问能力差的调查报告

当今知识经济初显端倪,是否具有创新能力已成为一个民族是否具有竞争力的关键。而提问能力一定程度上说就是创新能力的前提和基础。     

Flux growth of BPO4 crystals

Single crystals of BPO₄ with sizes up to 15×10×12 mm³ were grown by top-seeded solution growth method using Li₂O–Li₄P₂O₇ as fluxes. The components volatilized from the melt were characterized by the method of X-ray powder diffraction. The defects of grown crystals have also been investigated. The measured ultraviolet cutoff edge of BPO₄ was about 130 nm. Its density was 2.82 g/cm³ determined using drainage method.     

Li7Cd4.5Ge4Se16 and Li6.4Cd4.8Sn4Se16: Strong Nonlinear Optical Response in Quaternary Diamond‐Like Selenide Networks

Two new selenides with diamond‐like structures, Li₇Cd_4.5Ge₄Se₁₆ and Li_6.4Cd_4.8Sn₄Se₁₆, were synthesized by using a conventional high‐temperature solid‐state reaction method. They crystallize in the space group Pna2₁ (no. 33) of the orthorhombic system. Their three‐dimensional frameworks consist of corner‐sharing LiSe₄, CdSe₄, and MSe₄ (M=Ge, Sn) tetrahedra. These two compounds exhibit strong powder second‐harmonic generation responses that are about 1.2 and 2.5 times that of the benchmark AgGaS₂ at a laser wavelength of λ=2.09 μm, and also demonstrate type I phase‐matchable behavior. The optical bandgaps were determined to be 2.18 and 1.95 eV for Li₇Cd_4.5Ge₄Se₁₆ and Li_6.4Cd_4.8Sn₄Se₁₆, respectively. Furthermore, these two materials exhibit congruent melting behavior at rather low temperatures of 985 and 1060 K, respectively, which makes bulk single crystal growth by using the Bridgman–Stockbarger method possible. Our study indicates that these two materials show advantages over the traditional IR NLO material CdSe and are promising for practical applications.     

Flocking of Multi-particle Swarm with Group Coupling Structure and Measurement Delay

We investigate the flocking conditions of a group coupling system with time delays, in which the communication between particles includes inter-group and intra-group interactions, and the time delay comes from the theory of moving object observation. As an effective model, we introduce a system of nonlinear functional differential equations to describe its dynamic evolution mechanism. By constructing two differential inequalities on velocity and velocity fluctuation from a continuity argument, and using the Lyapunov functional approach, we present some sufficient conditions for the existence of asymptotic flocking solutions to the coupling system, in which an upper bound of the delay allowed by the system is quantitatively given to ensure the emergence of flocking behavior. All results are novel and can be illustrated by using some specific numerical simulations.     

Prelithiation design for suppressing delamination in lithium-ion battery electrodes

Applied Mathematics and Mechanics - Prelithiation has been intensively investigated in high-capacity lithium-ion batteries (LIBs). However, the optimization of prelithiation degrees for long...