伪可变体系的几何构造分析

伪可变体系几何可变性的研究，对轻型结构的设计分析已变得十分重要。本文先分析能量与平衡之间的普遍关系，进而得出判定体系可变性的能量准则。通过拉格朗日乘子的引入，建立能量泛函，得出判定极值的二次型。然后证明了乘积力法与能量法的一致性，并讨论了宜于计算机分析实现的矩阵表示方法。结果表明，若二次型确定，则体系伪可变；当半确定时，体系部分伪可变部分可变；否则体系含二阶以上的无穷小机构。     

Highly specific capture and direct MALDI-MS analysis of phosphorylated peptides using novel multifunctional chitosan-GMA-IDA-Fe (III) nanosphere

In this study, we describe a method for highly specific enrichment of phosphopeptides with multifunctional chitosan–glycidyl methacrylate (GMA)–iminodiacetic acid (IDA)–Fe (III) nanospheres for direct analysis by matrix-assisted laser desorption–ionization mass spectrometry (MALDI-MS). This is the first time that chitosan has been used to create nanospheres support material for selective enrichment of phosphopeptides by modification with GMA, derivatization with IDA, and loading with Fe (III) ions. Chitosan-GMA-IDA-Fe (III) nanospheres with a diameter of 20 to 100 nm have multifunctional chemical moieties which confer unique properties, good dispersibility in highly acidic binding buffers, as well as good biocompatibility and chemical stability which improves their specific interaction with phosphopeptides using various types of acid binding buffers. The process of enrichment is very simple, quick, efficient, and specific. Its high specificity and efficiency for purification of phosphopeptides is reflected in the very low and substoichiometric amounts of phosphopeptides which can be detected, in quantities as low as 1:3,000 M ratios. Compared with other state-of the-art technologies such as the use of conventional Fe³⁺-IMAC and TiO₂, these chitosan nanosphere techniques show superior specificity and sensitivity. Moreover, the resultant chitosan-GMA-IDA-Fe³⁺ nanosphere-absorbed phosphopeptides can be either directly analyzed by MALDI-TOF MS analysis or eluted and further analyzed by nano-LC-MS/MS.     

New method for resolving the enantiomeric composition of 2-methyltetrols in atmospheric organic aerosols

In order to facilitate the determination of the primary and secondary origin of atmospheric organic aerosols, a novel method involving chiral capillary gas chromatography coupled with mass spectrometry has been developed and validated. The method was focused on the analysis of 2-methylerythritol and 2-methylthreitol, considered to be tracers of secondary organic aerosols from the oxidation of atmospheric isoprene. The method was validated by performing various tests using authentic standards, including pure enantiomeric standards. The result showed that the analytical method itself does not affect the enantiomeric composition of the samples analyzed. The method was applied on atmospheric aerosols from a boreal forest collected in Aspvreten, Sweden and on laboratory samples obtained from liquid phase oxidation of isoprene and smog chamber experiments. Aerosol samples contained one enantiomer of 2-methylerythritol in significantly larger quantities than the others. In contrast, the liquid-phase oxidation of isoprene and its gas-phase oxidation in the smog chamber produced all enantiomers in equal quantities. The results obtained where the enantiomer fraction, EF, is larger than 0.50 suggest that 2-methyltetrols in atmospheric aerosols may also have biological origin. Information about the differences between enantiomer fractions obtained using this method brings new insights in the area of atmospheric aerosols.     

严格电磁场波导方法的三维厚胶光刻工艺仿真（英）

无论是在微机电系统（MEMS）还是集成电路（IC）领域,SU-8厚胶光刻已经成为制造高深宽比结构的主流工艺。为了取代昂贵而耗时的光刻实验,一套能够良好预测显影形貌,从而为优化光刻制造提供有效帮助的光刻仿真软件就成为必要而有价值的工具。基于严格电磁场波导法的理论,给出一种针对SU-8光刻胶在紫外光下的三维光刻仿真模型。利用该模型,能很好地预测显影后的光刻胶内光强分布和立体形貌。并完成了一系列仿真和实验结果来验证模型的有效性。仿真结果给出横截面光强分布图和显影立体形貌模拟图形,并与相应的实验结果进行对照。结果验证了本文提出的仿真模型的正确性,并且表明三维混合模型在保证精确性的前提下,较之其他仿真算法运算速度更快。     

A new method and instrument for accurately measuring interval between ultrashort pulses

Using second-order autocorrelation conception, a novel method and instrument for accurately measuring interval between two linearly polarized ultrashort pulses with real time were presented. The experiment demonstrated that the measuring method and instrument were simple and accurate (the measurement error ＜ 5 fs). During measuring, there was no moving element resulting in dynamic measurement error.     

Microstructure and magnetic properties of Fe72.5Cu1M2V2Si13.5B9 (M=Nb, Mo, (NbMo), (MoW)) nanocrystalline alloys

The microstructure and magnetic properties of Finemet-type Fe_72.5Cu₁M₂V₂Si_13.5B₉ (M=Nb, Mo, (NbMo), (MoW)) alloys have been systematically studied. Results show that the nanocrystalline alloy with M=NbMo has the smallest grain size of about 8 nm. The order of the effect of Nb, Mo and W additions in decreasing the α-Fe grain size in nanocrystalline alloys is Nb>Mo>W. The best DC soft magnetic properties are obtained in the alloy with M=Nb. In the case of AC soft magnetic properties, the Nb alloy also exhibits a very low core loss comparing with typical Finemet alloy. Therefore, the Nb alloy is suitable for use as a transformer core material. In addition, it is shown that a narrow grain size distribution and a uniform dispersion of α-Fe grains in the amorphous matrix are very crucial for the development of new Finemet-type nanocrystalline alloys with good soft magnetic properties.     

Microwave-assisted,rapid synthesis of 2-vinylquinolines and evaluation of their antimalarial activity

A rapid and efficient synthesis of 2-vinylquinolines via trifluoromethanesulfonamide-mediated olefination of 2-methylquinoline and aldehyde under microwave irradiation is reported. Biological evaluation of these scaffolds demonstrates that 2-vinylquinolines 3x-3z possess excellent antimalarial activities against chloroquine-resistant Dd2 strain of Plasmodium falciparum (IC₅₀ < 100 nM).     

四角点简支双稳态层合板振动特性研究

双稳态层合板作为一种柔性可变体结构,为实现振动状态下的构型调控,将对其开展固有振动特性的研究.本文以四角点简支约束的矩形非对称铺设双稳态板作为研究对象,运用最小势能原理、一阶剪切变形理论、以及冯卡门几何非线性位移应变关系,得到双稳态板的两种稳态构型.首次给出了适合于四点简支的6参数构型函数与17参数构型函数,研究对比发现对于稳态构型采用17参数的构型函数结果相对更精确;对于应用线性位移应变关系的基于任一稳态构型下振动固有特性而言,这两种构型函数得到的结果基频相差2%,其它阶次频率相差也不大.随后采用6参数构型函数得到的稳态构型研究了几何尺寸、铺层数分别对两种稳态构型固有振动特性的影响.本研究对于进一步研究该类结构动态跳变机理具有重要意义.     

钨球对高硬度钢斜侵彻效应

为研究高硬度钢板抗不同着角钨球的侵彻性能及破坏模式,通过弹道枪进行了?8 mm、?11 mm钨合金球形破片以0°、20°、40°着角撞击厚度为6 mm、8 mm的高硬度钢板试验,得到了极限贯穿速度v₅₀;分析了钨球轴向径向变形及靶板失效模式与撞击速度的关系,发现高硬度钢板失效模式主要为压缩开坑破坏和沿厚度方向剪切破坏。采用有限元方法对试验进行了模拟,验证了数值模型及参数的合理性,并运用数值模拟方法研究了撞击着角对靶板吸能模式影响,结合试验数据,修正已有极限贯穿速度计算公式。结果表明:随侵彻着角增大,极限贯穿速度提高,且着角越大,极限贯穿速度增长越快;随着角增大,靶板吸能模式逐渐由压缩开坑向剪切冲塞过渡,且着角大于50°时,剪切冲塞耗能将超过压缩开坑耗能;修正后极限贯穿速度计算公式适用范围更广、精度更高,具有较好工程应用价值。     

Dynamics of an Elastic Four Bar Linkage Mechanism with Geometric Nonlinearities

The geometric nonlinearity due to the large elastic deformations of three flexible links is considered in setting up the dynamic equation of elastic linkages. It is shown that both the quadratic nonlinear terms and the cubic nonlinear terms are included in the model. The analyses with the method of multiple scales demonstrate that the superharmonic resonances caused by the quadratic and cubic nonlinearities, as well as the multi-frequency nature of the inertial force are the reasons causing the critical speed to take place. They also demonstrate that the combination resonances caused by the combined effects of internal resonance in the form of ₂ 2₁, the cubic nonlinearity and the multi-frequency nature of the inertial forces is the reason causing the production of the nonsynchronism of the lower order harmonic resonances of elastic linkages. Meanwhile, the influences of important system parameters on the resonances are investigated.