具有内悬臂的环板在两种不同荷载共同作用下的塑性极限分析

针对承受两种不同荷载的具有内悬臂环板的塑性极限分析问题，应用奇异函数给出一种分析方法。文中给出一些算例，由此显示出本文方法的简单方便性。     

水蒸汽在水平三维微肋管内的凝结换热及阻力特性

本文以水蒸汽为工质对水平三维微肋管内凝结换热及阻力特性进行了实验研究．与光管和二维管相比，在相同条件下，实验中效果最好的T3管全长平均凝结换热系数分别提高了113％～410％和20％～65％，同时，与二维管相比流动阻力增加较小，最大值不超过6．3％．比较另两种管型（T1，T2管）也证明三维管以较小的流阻增加为代价换取了明显的强化效果．     

多级穿廊结构坑道口部内爆炸冲击波传播规律的实验研究

对坑道口部的内爆炸效应进行了系统的实验研究,探讨了端部不同开闭工况下多级穿廊结构内的冲击波传播规律、作用在防护门上的荷载规律及门后次生冲击波的发展与变化规律,给出了多级穿廊结构坑道内各分段之间冲击波超压衰减变化的量值关系.实验结果表明,多级穿廊结构不仅能显著衰减冲击波峰值压力,而且与单一的直坑道相比,在同样的冲击波衰减...     

Bifurcations of nontwisted heteroclinic loop

Bifurcations of nontwisted and fine heteroclinic loops are studied for higher dimensional systems. The existence and its associated existing regions are given for the 1-hom orbit and the 1-per orbit, respectively, and bifurcation surfaces of the two-fold periodic orbit are also obtained. At last, these bifurcation results are applied to the fine heteroclinic loop for the planar system, which leads to some new and interesting results.     

Experimental studies of bubble dynamics inside a corner

The dynamics of a bubble near a corner formed by two flat rigid boundaries (walls), is studied experimentally using a spark-generated bubble. The expansion, collapse, rebound, re-collapse and migration of the bubble, along with jetting and protrusion, are captured using a high-speed camera. Our experimental observations reveal the behaviour of the bubble in terms of the corner angle and the dimensionless standoff distances to the near and far walls in terms of the maximum bubble radius. The bubble remains approximately spherical during expansion except for its surface becoming flattened when in close proximity to a wall. When a bubble is initiated at the bisector of the two walls, the bubble becomes oblate along the bisector during the late stages of collapse. A jet forms towards the end of collapse, pointing to the corner. The closer the bubble to the two walls, the more oblate along the bisector the bubble becomes, and the wider the jet. A bubble initiated near one of the two walls is mainly influenced by the nearer wall. The jet formed is pointing to the near wall but inclined towards the corner. After the jet penetrates through the bubble surface, the bubble becomes a bubble ring, and a bubble protrusion forms following the jet. The bubble ring collapses and subsequently disappears, while the protrusion firstly expands, and then collapses and migrates to the corner.     

Dead volume–free flow splitting in capillary electrophoresis

In recent years, several dual detection concepts (DDCs) for CE were developed, which consisted of at least one nondestructive detector. For these DDCs, a linear detector arrangement could be used, which is not possible when both detectors are destructive. To overcome this problem, we developed a concept for the splitting of the CE stream utilizing commercially available flow splitters (FSs) that allow the parallel positioning of two destructive detectors. In this proof-of-concept study, T- and Y-shaped FSs were characterized regarding their suitability for DDCs. To keep it simple, a UV detector (UV) and a C⁴D were used for the characterization. The model system consisted of an acetonitrile-based background electrolyte and the two model substances, (ferrocenylmethyl)trimethylammonium iodide and caffeine. CE hyphenated to a UV detector (CE-UV) measurements revealed that the split ratio was about 50% for both FSs. CE-C⁴D was used to evaluate the peak shape in front of and behind the FSs. These measurements showed that there was no significant peak broadening introduced by the FSs. Additionally, there were no changes in the LODs in front of and behind the FSs. Furthermore, the flexibility of the new FS approach allowed the usage of capillaries with different ids (25–75 µm) for injection and detection.     

Inserts providing complete sample evaporation above the column entrance in vaporizing GC injectors

Completeness of sample evaporation in conventional vaporizing injection is a problem for many samples and calls for measures to arrest the sample liquid in the space between the needle exit and the column entrance. A visual testing procedure reveals that a small plug of loose glass or quartz wool ensures complete evaporation in all instances. Obstacles built into the liner also stop liquid, provided they force the sample to pass through narrow channels. Other important design characteristics concern access to the narrow channel. Evaporation in a packed insert usually occurs from a surface, whereas the sample hardly touches surfaces in the instance of an insert with obstacles. Evaporation from a packing is, in fact, more reliable, but creates more problems concerning inertness.     

Solubilisation and binding characteristics of a recombinant beta2-adrenergic receptor expressed in the membrane of Escherichia coli for the multianalyte detection of beta-agonists and antagonists residues in food-producing animals

The on-line incorporation of cloud point extraction (CPE) to flow injection analysis (FIA) was previously based on the use of a cotton-packed column to entrap the analyte-containing surfactant aggregates after salt-induced CPE, and then the preconcentrated analyte was eluted into a separate detection cell for subsequent chemiluminescence (CL) detection (via the peroxyoxalate CL reaction). In the work, the on-line CPE/FIA technique was improved by the following: (1) sample preconcentration and CL detection were both carried out directly inside the collection column, thus avoiding the decrease in detection sensitivity due to sample dispersion and dilution, and (2) CL detection was performed through the reaction between nitrite and hydrogen peroxide, which is compatible with aqueous samples and should allow for chemical excitation to occur more efficiently inside the collection column. In addition to more effective sample preconcentration, the CL detection of the entrapped analytes directly inside the collection column, i.e., a unique heterogeneous microenvironment in which analyte-containing surfactant aggregates were embedded within the densely packed filtering material, may also contribute to the overall increase in CL intensity (e.g., a CL enhancement factor of ca. 1000). Under optimum experimental conditions, the calibration curve was found to be linear for the CL detection of bilirubin (5 to 120 μg L⁻¹), the limit of detection (S/N = 3) was 1.8 μg L⁻¹, and the R.S.D. was ca. 2.6% (n = 30) for 20 μg L⁻¹ bilirubin. Good agreements were obtained for the determination of total bilirubin in certified reference human serum samples between the present approach and an established clinical method.     

Q235碳钢缝隙腐蚀的电化学噪声研究

应用电化学噪声和电化学阻抗技术研究Q235碳钢在NaHCO3+NaCl溶液中的缝隙腐蚀行为.结果显示,缝隙腐蚀过程可以被清楚地划分为3个阶段:孕育期、快速转换期和稳定发展期.电化学噪声的特征和噪声电阻在各阶段有着显著的变化.缝隙外、内表面积比(r)对缝隙腐蚀的孕育和发展有着十分重要的影响:r越大,孕育期越长.但是,在缝隙腐蚀稳定发展期,r较小时,缝隙外电极表面处于活性溶解状态,缝隙内外电位差很小,缝隙内腐蚀速率较小;倘如r很大时,则缝隙外电极表面处于钝态,缝隙内外电位差大,最终将导致严重的缝隙腐蚀.     

一个描述合作网络顶点度分布的模型

讨论一类社会合作网络以及一些与其拓扑结构相似的技术网络的度分布.建议一个最简化模型，通过解析的方法说明这些网络演化的共同动力学机理，而且说明顶点的度分布和项目度分布之间具有密切的一致关系，而项目所含的顶点数分布对度分布的影响较小；对模型的更一般情况进行数值模拟，说明上述结论具有一定的普遍性.这个模型显示这类广义的合作网络一般具有处于幂函数和指数函数这两种极端情况之间的度分布.简要介绍对一些实际合作网络做统计研究的结果，说明本模型的合理性. 关键词： 合作网络 度分布 项目度分布 项目含顶点数