时间分辨原子发射光谱诊断脉冲放电气体束等离子体

建成了一套脉冲放电气体束和原子发射光谱等离子体诊断实验装置,利用这套实验装置测量了不同放电条件下等离子体的时间分辨发射光谱,并采用玻尔兹曼作图法和Hα谱线斯塔克展宽法研究了等离子体的原子温度、离子温度和自由电子密度等参数的演化。实验结果表明,脉冲放电的总电量对等离子体参数的演化有较大影响;脉冲放电气体束等离子体中的离子温度远高于原子温度,自由电子密度相对较低,等离子体处于非局域热平衡状态。A special designed pulsed discharge nozzle (PDN) ion source and a plasma diagnostics system based on the atomic emission spectroscopy were constructed. The time-resolved emission spectra of Argon atoms and ions in the region of 300-800 nm were observed and analyzed. The plasma temperatures, including atomic and ionic temperatures, were simulated by Boltzmann plot method, and the free electron density was simulated through the Stark broadening of Hα line. The evolution of these plasma parameters were investigated by high-resolution time-resolved emission spectra. The results show that the total energy struck on the pulsed gas beam is the most important factor which determines the plasma properties and its evolution. The plasma in PDN is concluded into non-local thermodynamic equilibrium (non-LTE) during the evaluation because of the low electron density and the big difference between the temperatures of Argon atoms and ions in all discharge conditions.     

初始空间有序分布下超冷等离子体的演化模拟

超冷等离子体是一种极低温的强耦合等离子体.无序诱导加热过程是制约其达到高耦合强度的主要因素.我们使用德拜势场单体系等离子体模型的分子动力学方法模拟超冷等离子体的演化过程,研究初始空间分布对无序诱导加热过程的影响.在周期性边界条件下,我们研究了不同初始空间下超冷等离子体的演化过程,证明了有序初始空间分布能够有效提高等离子体的最终耦合强度,其结果与近期的理论计算相符合.进一步我们在演化模拟中考虑了有限体积下超冷等离子的膨胀过程,发现其在有序初始分布下会引发无序过程显著加热超冷等离子体,导致了耦合强度的逐渐降低.     

基于暗通道先验的单幅图像快速去雾方法

为了提高雾天图像的去雾效果,针对暗通道先验法则中存在的不足,提出一种单幅图像快速去雾方法.该方法以暗通道先验法则为基础,采用四叉树搜索算法对大气光值进行估计,并通过白平衡对大气散射模型进行简化.然后,利用暗通道先验知识得到介质传输率粗略估计,并通过引导滤波和双阈值判断方法对介质传输率中边缘和天空区域进行优化.最后,通过简化大气散射模型和色调调整得到去雾图像.与几种典型的图像去雾方法相比,该方法运算速度较快,能有效提高去雾图像的清新度,并获得较好的图像颜色.     

Infinitely Multiple Eigenvalues of The Dirichlet Problem for Quasilinear Elliptic Equations

In this paper, We consider the following Dirichlet problem for quasilinearelliptic equation ( /x_i)F_i(x,Du)=-λu-p(x,u) x∈Ω(1) u| Ω=0     

Crystal Structures,Thermal Behaviors and Biological Activities of Acylhydrazone Compounds Containing Pyrazine Rings and Halogen Atoms

Three new kinds of acylhydrazone compounds(C_(12)H_(10)FN_5O·H_2O,1;C_(12)H_(10)Cl N_5O·2CH_3COOH,2;C_(12)H_(10)Br N_5O,3)were synthesized by the reaction of 2-amino-3-pyrazinecarbohydrazide(C_5H_7N_5O)with halogenated benzaldehyde(C_7H_5OX,X=F,Cl,Br).The structures of the three compounds were characterized by elemental analysis,~1H NMR,IR and X-ray diffraction.X-ray single-crystal diffraction presents that the three compounds all belong to triclinic system,P1 space group.Thermal gravity analyses show that three compounds have excellent thermal stabilities and all the thermal decomposition temperature of maximum weight loss was around 300°C.The interactions of the compounds with CT-DNA were investigated by UV-Vis spectrum,fluorescence spectrum and viscosity measurement.All the results suggest that three compounds could bind with CT-DNA through intercalation.The fluorescence spectrum was also used to study the interactions of three compounds with BSA.It was proved that all the compounds could quench the intrinsic fluorescence of BSA via a static quenching process.Compound 2 displays the strongest binding ability both in the reaction with CT-DNA or BSA.Antimicrobial test was carried on Escherichia coli,Staphylococcus aureus and Salmonella,and 2 is more effective against S.aureus.But in MTT assay,1 shows better cytotoxity activity against A549cells.     

超冷等离子体演化早期的离子温度与库仑耦合强度

利用开发的磁光阱-离子速度成像装置,实验测量超冷等离子体的离子温度与库仑耦合参数。同时利用带电粒子追踪数值方法模拟超冷等离子体的早期演化过程。实验和模拟结果表明：在超冷等离子体演化早期,无序诱导加热机制导致离子温度快速上升,而库仑耦合强度下降至2.5。进一步研究还发现：在离子非平衡演化阶段,等离子体膨胀速度会快速接近并超过离子热速度,因此离子达到局域热平衡之后的库仑耦合参数会高于测量值。     

基于模糊邻域相对依赖互信息的特征选择方法

模糊粗糙集作为处理不确定性信息的有效工具,已广泛应用于特征选择中。然而当数据分布密度差别较大时,传统模糊粗糙近似不能有效度量样本的隶属度,且大多特征评价函数仅从代数或信息单一视角构造。针对以上问题,提出了一种基于模糊邻域相对依赖互信息的特征选择方法。首先,为克服传统模糊粗糙近似对数据分布敏感的缺陷,引入相对距离计算模糊相似关系,同时考虑模糊邻域粒度结构,提出了模糊邻域相对依赖度,从代数观度量数据的不确定性。然后,基于相对粒度结构提出了模糊邻域相对互信息,并与模糊邻域相对依赖度结合构造出一种新的特征评价函数——模糊邻域相对依赖互信息,将代数观和信息观结合进行特征评价。最后,设计了一种基于模糊邻域相对依赖互信息的特征选择算法(FNRDI)。通过与其他算法在9个公共数据集上进行实验对比分析,结果表明所提算法可有效消除冗余特征且提高数据的分类精度。     

Polyamides containing thiadiazole units: Synthesis and optical properties

Highly refractive and transparent polyamides containing thiadiazole units have been developed.These polymers were prepared by a polycondensation reaction of 4,4'-(1,3,4-thiadiazole-2,5-thio) bis(methylene) dibenzoyl chloride(TDTBM-DC) and diamine which contained thioether(―S―) and sulfone units.They showed good thermal stabilities such as a relatively high glass transition temperature of 206-233 °C and a 5% weight-loss temperature(T5%) of 376-395 °C.The optical transmittance of the polymer at 450 nm is higher than 83%.The heterocycle units and plural ―S― linkages provide the polymer with a high refractive index of 1.716-1.725 at 633 nm and a low birefringence of 0.003-0.004.Also they showed improved solubility in polar aprotic solvents and could form moderate strength films with tensile strength of 72.8-83.1 MPa and storage modulus of 1.0-1.8 GPa(at 200 °C).     

六西格玛约束磁力计在线校准方法

传统磁力计在线校准需要惯性传感器辅助,计算复杂且精度不稳定。为此,提出一种六西格玛约束磁力计在线校准方法,重新对磁力计误差进行分类,构建精确的磁力计误差模型。使用六西格玛（SS）对磁力计校准模型进行管理,实现磁力计误差分类。提出了六西格玛约束扩展卡尔曼滤波（SEKF）方法,对磁力计误差校准。实验结果表明,在航向修正方面,采用所提出的磁力计在线校准方法的航向均方根误差相较于采用陀螺仪辅助（GA）法和扩展卡尔曼滤波校准（EKF）法分别降低了32%和12%以上。实现了一种无惯性传感器辅助的高精度磁力计在线自校准方法。     

抗癌核苷类似物

综述了近年来核苷类抗癌药物的最新研究进展，分别介绍了具有抗癌活性的核 苷类似物的作用机制和药物代谢机理、各种核苷类似物抗癌剂的分类、次黄嘌呤核 苷酸脱氢酶（IMPDH）抑制剂以及核苷氨基磷酸酯前药的结构与抗癌活性关系。