Stratifiable Families of Extremals and Sufficient Conditions for Optimality in Optimal Control Problems

It is shown that, if a parametrized fämily of extremals F can be stratified in a way compatible with the flow map generated by F, then those trajectories of the family which realize the minimal values of the cost in F are indeed optimal in comparison with all trajectories which lie in the region R covered by the trajectories of F. It is not assumed that F is a field covering the state space injectively. As illustration, an optimal synthesis is constructed for a system where the flow of extremals exhibits a simple cusp singularity.     

Unusual current‐voltage characteristics of single crystalline and bicrystalline La0.7Ca0.3MnO3 films

The current‐voltage characteristics of single crystalline and bicrystalline La_0.7Ca_0.3MnO₃ films were measured and analyzed. Several epitaxial films, as well as 45° [001]‐tilt grain boundaries, display current‐voltage characteristics which are asymmetric with respect to polarity reversal of the bias current. One epitaxial film has a polarity dependent resistance of ～340kΩ and of ～670kΩ in forward and in reverse direction, respectively.     

三羟甲基甲胺、季戊四醇及其二元体系固-固相变的变温红外光谱研究

利用傅里叶变温红外光谱仪分别测定了三羟甲基甲胺（TAM）、季戊四醇（PE）及其二元体系变温红外谱。实验表明，多元醇分子中羟基吸收峰随温度升高耐发生位移向高波数移动，此结果既能反映多元醇及其二体系固－固相变的温度区间，又与转变热相对应，从而揭示了多元醇及其二元体系固－固相变贮热的机理。     

应变Si1-xGex层中p型杂质电离常温和低温特性

本文采用解析的方法计算了应变Si1-xGex层中p型杂质电离度与Ge组分x、温度T以及掺杂浓度N的关系.发现常温时,在同一Ge组分下,随着掺杂浓度的升高,杂质的电离度的先变小,而后又迅速上升到1.在同一掺杂浓度下,轻掺杂时,杂质的电离度随Ge组分的增加先变大,而后几乎不变;重掺杂时,杂质电离能变为0后,杂质电离度为1.低温下,轻掺杂时,载流子低温冻析效应较为明显,杂质的电离度普遍较小,当掺杂浓度大于Mott转换点时,载流子冻析效应不再明显,电离率迅速上升到1.在同一Ge组分下,随着掺杂浓度的升高,杂质的电离度先变小,后变大,而后又迅速上升到1.在同一掺杂浓度下,轻掺杂时,杂质的电离度随Ge组分的增加变大;重掺杂时,杂质电离能变为0后,杂质电离度为1.     

Vlasov辐射器反射特性研究

 利用矩量法导出Vlasov辐射器端口处各种模式模系数（振幅）的计算方法，并利用此方法通过数值计算研究了斜切形Vlasov辐射器的反射特性，得到了辐射器端口反射系数和斜切角度及直径波长比之间的关系。结果表明斜切形辐射器具有很小的反射系数，并从反射特性上为辐射器结构参数的选择提供了依据。     

Stability of solutions to the Cauchy problem for a plane hyperbolic system with time-periodic coefficients

Considering a plane hyperbolic system with time-periodic coefficients, we construct a version of the direct Lyapunov method with the condition on the derivative of the Lyapunov functional along the trajectories of the system which is weakened by use of periodicity of the coefficients. We exhibit an illustrative example.     

正丁基苝四羧酸二酰亚胺的晶型和性能研究

文章合成了N,N'-二正丁基苝四羧酸二酰亚胺,并纯化、调晶,进行了IR、元素分析、X射线等测定.分析该化合物在DMF中的紫外光谱(最大吸收波长524.80 nm)、荧光光谱(最大发射波长539.0 nm)、Stokes位移(数值15 nm)等光谱性质.在400～700 nm范围内,α晶型薄膜紫外-可见吸收出现很强的吸收峰,且由β型变为α型,最大吸收波长有明显的红移(545 nm变为580 nm).X射线粉末衍射也反映出α晶型的2θ在26.0°处衍射峰CPS为2 508,β型在25.2°为1 891.α,β晶型作为电荷产生材料制得的功能分离型有机光导体,在光源滤波波长λ=532 nm曝光下,测得含α,β感光体达到饱和电位的时间分别为46,93.98 s,光衰电位(5.3千伏电压负充电电晕,1～2 s后的表面电位)分别为727和525 V,半衰曝光量分别为4.32,4.34μJ·cm-2,残余电位分别为30和45 V等光导性能数值.     

环境光对PE塑料薄膜近红外激光拉曼光谱的影响

探讨了环境光自然光和室内荧光灯光的存在,对PE透明塑料薄膜的近红外激光拉曼光谱的影响.研究表明不同的环境光,会对近红外拉曼光谱产生不同的明显特征峰.自然光干扰产生的是以倒峰群形式为主,而室内荧光灯光造成的干扰主要以尖锐的脉冲峰形式.虽干扰表现形式不同,但都有严重地影响,在测定时一定要引起重视,不能忽略.建议在进行透明塑料近红外拉曼光谱检测时,须在暗室或暗罩遮光保护中进行,以完全隔离环境光的影响.     

Evaluation of PLE exhaustiveness for the extraction of PCBs from sediments and the influence of sediment characteristics

Pressurized liquid extractions were performed on eight sediments in order to investigate if a modified US EPA method (100 °C, 100 bar, n-heptane/acetone (1:1), 2 × 5 min) provided exhaustive extractions of polychlorinated biphenyls (PCBs) from sediment, and to study if the extractability of PCBs from the different sediments was affected by characteristics of the sediment. The recovery from the eight native sediments, contaminated in nature, was between 96.4% and 98.9%, as an average of the recoveries from 10 PCB congeners. Hundred percent recovery was defined as the sum of two consecutive extractions (2 × 5 min each) at the stated conditions. The recoveries of the individual congeners were above 94%, except for one congener in one sediment, which had a recovery of 92%. When the recoveries and different characteristics of the sediments were compared, no correlation appeared between recoveries and sediment PCB concentration, total organic carbon (TOC), soot carbon (SC) or amorphous carbon (AC). The fact that carbon did not influence the extractions was somewhat surprising, since previous experiments have indicated a connection. Instead, statistically significant (p < 0.05) correlations were observed for water content and carbon/nitrogen (C/N) ratio. The decrease in recoveries with decreased water content was attributed to less access of the solvent to the analytes due to less matrix swelling. The lowered recoveries with increased C/N ratio can indicate that a difference in structure of the organic matter exists, which influences the binding strength between the analytes and the matrix. The difference in structure can possibly be explained by different origin of the organic matter or by aging effects. Overall the method was found to be exhaustive and the excellent recoveries show that sediment characteristics do not influence the extractions markedly.     

显像管调制特性的测量与分析

测试了显象管调制特性曲线，并分析了特性曲线与显像管工作原理．