水下稳态涡流场声传播特性

基于射线声学理论研究了水下稳态涡流场的声传播特性。首先,根据移动介质中的程函方程,推导了二维稳态涡流场的射线微分方程组,实现了声波通过涡流场的声线轨迹模拟,获取了通过不同涡流场的声信号;然后,基于稳态涡流场的声传播特性,构建了接收声信号相位与涡流场特征参数之间的映射关系,通过数值仿真反演稳态涡流场特征参数,仿真结果与理论值的相对误差在15%以内。仿真结果表明:基于射线理论可以有效模拟声信号通过涡流场的声线轨迹及信号变化,具有直观、计算效率高的优势;随着涡环量增大,涡流对声传播的影响更为明显;利用声信号相位可实现对速度分布、涡核位置、涡环量等涡流场特征参数的估计。     

失调多腔镜型环形谐振腔共轭光轴位置精度分析

为了详细分析由多个反射镜构成的谐振腔内的闭合光轴(共轭光轴)的特性以及存在条件, 首先从光束传输坐标变换的角度, 分析了由多个平面镜所构成的谐振腔的共轭光轴存在条件, 得出了奇数平面镜谐振腔仅当平面镜间具有高精度的相同垂直度时才存在闭合光轴, 而偶数平面镜谐振腔总是存在闭合光轴的结论, 并给出了腔共轭轴随腔镜方向失调而产生的角度变化关系. 然后从矩阵光学的角度分析包含球面镜的谐振腔的共轭光轴在腔镜间传输时的方向变换问题, 具体分析了由两个平面镜和一个球面镜构成的三角形环形谐振腔的闭合共轭光轴存在的问题. 结果表明, 当不同的镜子出现角度偏差时, 腔内仍然存在闭合的共轭光轴, 并给出了对应的腔轴变化以及新谐振面的位置及方向. 由此表明由于球面镜的加入降低了谐振腔共轭轴存在性对平面镜间高精度平行度的要求, 为基于高品质光学无源腔的光谱测量技术的高精度装调工作提供了理论指导.     

珠三角产业转移与广西承接产业转移清单

从产业集聚指数的视角,预测了广州、深圳等珠江三角洲地区的9个城市的产业转移趋势.从产业吸引力指数的视角,计算了广西所属的14个地级市分别承接珠江三角洲9个城市中转移产业的吸引力指数,分析了广西在承接珠江三角洲产业转移中的产业分布范围,确定了承接产业转移清单.产业转移承接地的资源禀赋将影响其承接产业转移的能力.承接产业转移的能力取决于承接地的投资环境、自然资源、交通便捷、技术创新、劳动力成本等方面的因素.对广西的14个地级市的资源禀赋进行了分析,测算了其承接产业转移的能力.     

一类描述肿瘤入侵与具有信号依赖机制的趋化模型有界性与稳定性分析北大核心CSCD

该文将研究如下问题■其中,有界区域Ω■R^(n)(1≦n≦5)具有光滑边界,v表示?Ω的外法向量,且0<γ(v)∈C^(3)[0,∞).在合适的初始条件下,该文分两种情形来研究模型的全局经典解的存在性与有界性:1     

Sulfur-Selective Desulfurization of Dibenzothiophene and Diesel Oil by Newly Isolated Rhodococcus erythropolis NCC-1

A dibenzothiophene （DBT）-desulfurizing bacteria strain was isolated from oil-contaminated soils and identified as Rhodococcus erythropolis NCC-1. Strain NCC-1 was found to convert DBT to hydroxybiphenyl （2-HBP） via the 4S pathway and also be able to use organic sulfur compounds other than DBT as a sole sulfur source. The strain could desulfurize 4,6-dimethyldibenzothiophene （4,6-DMDBT）, which is one of the most recalcitrant dibenzothiophene derivatives to hydrodesulfurization. When two type of oils, a model oil [n-hexadecane （n-C16） containing DBT] and a hydrodesulfurized diesel oil with various organic sulfur compounds, were treated with Rhodococcus erythropolis NCC-1 cells, the total sulfur content significantly decreased, from 150 to 20 mg/L for n-C16 and from 554 to 274 mg/L for diesel oil. The newly isolated strain NCC-1 is considered to have good potential for application in the biodesulfurization of fossil fuels.     

Reaction of Molybdenum Hexa-carbonyl with Mercapto-pyridine （PySH） or Mercapto-pyridine Oxide （PyS→O） and Crystal Structure of [Et4N][Mo2（PyS）3（CO）5]

Introduction Mercapto-pyridine, C5H4NS-(PyS), containing two active atoms, S and N, is a bidentate ligand, which may act as a 3-electron donor or a 5-electron donor and may be a bridging ligand to link two metal atoms to form polynuclear metal clusters or a chelating agent to coor-dinate to a metal atom by S and N atoms. So the mer-capto-pyridine is a very important reagent and its reac-tion with metal compound is very useful for simulating the active center in metal enzymes and syntheses …     

芳氢与配位硫原子之间(sp2C-H…S)的分子内氢键

化合物(Et4N)2[Pd2(mp)2(Hmp)2](1)(H2mp＝2-巯基苯酚)的1H NMR谱中芳氢H16的峰出现在δ 8.79处,与预测值(δ 7.1)相差1.7,这是由于H16与配位硫S2原子之间存在弱相互作用,即新型的sρ2C-H…S之间的氢键作用.原子间距离C16…S2(0.361pm)和H16…S2(0.295pm)分别小于相应原子的范德华半径之和(0.370pm和0.305pm),C16-H16…S2角为128.1°,证明了这种新型氢键的存在.此外,在分子振动光谱中观察到这种氢键的作用使得芳氢υC-H出现在低于3000cm-1处.通过与类似物[Pd2(PPh3)2(Hmp)2Cl2](2)的比较,以及1在DMSO溶剂中仍然保持O-H…O和C-H…S这2种氢键的事实,表明C-H…S之间的作用,对1的配体Hmp中的苯环与Pd2S2平面之间的夹角偏离90°可能是有贡献的.     

Quantum Secure Direct Communication Network with Two-Step Protocol

An efficient quantum secure direct communication network protocol with the two-step scheme is proposed by using the Einstein-Podolsky-Rosen （EPR） pair block as the quantum information carrier. The server, say Alice, prepares and measures the EPR pairs in the quantum communication and the users perform the four local unitary operations to encode their message. Anyone of the legitimate users can communicate another one on the network securely. Since almost all of the instances in this scheme are useful and each EPR pair can carry two bits of information, the efficiency for qubits and the source capacity both approach the maximal values.     

高压容器耐压及气密性试验检测系统的设计

在高压下使用的压力容器、阀门等产品，制成后需进行耐压试验和气密性试验以保证产品在工作压力下不泄漏。为此，研究设计了一套可采取自动和手动两种控制方式，对高压容器等产品安全地进行耐压、气密性试验的充气系统，及可在气密试验压力下检测漏率值的真空检漏系统。     

Exponential synchronization of stochastic impulsive perturbed chaotic Lur''e systems with time-varying delay and parametric uncertainty

This paper is devoted to investigating the scheme of exponential synchronization for uncertain stochastic impulsive perturbed chaotic Lur＇e systems. The parametric uncertainty is assumed to be norm bounded. Based on the Lyapunov function method, time-varying delay feedback control technique and a modified Halanay inequality for stochastic differential equations, several sufficient conditions are presented to guarantee the exponential synchronization in mean square between two identical uncertain chaotic Lur＇e systems with stochastic and impulsive perturbations. These conditions are expressed in terms of linear matrix inequalities （LMIs）, which can easily be checked by utilizing the numerically efficient Matlab LMI toolbox. It is worth pointing out that the approach developed in this paper can provide a more general framework for the synchronization of multi-perturbation chaotic Lur＇e systems, which reflects a more realistic dynamics. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed method.