影响蜂窝状钢骨混凝土L形柱性能的参数分析

针对钢骨混凝土L形柱,提出了一种新型的钢骨形式.为了掌握该构件的受力特性,通过ANSYS软件,对腹板开洞率、配钢率、加载角、偏心距等影响因素进行理论分析.结果表明,在相对偏心距较大的情况下构件承载力会急剧下降,而且存在不利荷载角的问题;腹板开洞能有效地减少钢骨与混凝土之间的滑移,但对承载力的削弱有限,并就该构件的最佳配钢率提出建议.     

Stabilization And Tracking Of Underactuated Surface Vessels In Random Waves With Fin Based On Adaptive Hierarchical Sliding Mode Technique

Trajectory tracking and roll stabilization are both vital practices in ship motion control. Trajectory tracking is a kind of low‐frequency control, while roll stabilization by means of fins is a kind of high‐frequency control. However, they have been studied separately previously; most tracking control of underactuated surface vessels in the previous studies do not account for roll stabilization by means of fins. In reality, however, they are an integral system. In this paper, a simple control strategy is proposed to achieve trajectory tracking and fin roll stabilization simultaneously. Four degrees of freedom derived from a six degrees of freedom mathematical model of a surface vessel is considered, including surge, sway, roll and yaw. Surge force, roll moment and yaw moment are considered as control inputs, while position, yaw angle and roll angle are controlled. The number of control inputs is fewer than the outputs to be controlled. Therefore, we are dealing with an underactuated problem. An adaptive hierarchical sliding mode control technique is employed to deal with the underactuation. Stabilization of underactuated surface vessels is studied as a special case. Random waves are applied to test the robustness of the designed controllers. Lyapunov stability theory is used to show the stability of closed‐loop system. The simulation results verify the effectiveness of the proposed strategy.     

Surface analysis and adsorption behavior of caffeine as an environmentally friendly corrosion inhibitor at the copper/aqueous chloride solution interface

Abstract

Corrosion inhibitors based on environmentally friendly and harmless products are currently being studied and developed. The corrosion inhibition properties of caffeine (1,3,7-trimethylxanthine) on copper corrosion in aqueous chloride solution (3.5?wt.% NaCl) are analysed here using stationary and transient electrochemical methods, and a theoretical study based on density functional theory is carried out. Caffeine is a very competitive compared to the chemical inhibitors that are often used for copper protection. Electrochemical and impedance experiments reveal that the protective efficiency of caffeine reaches a value of 96% at a concentration of 10^?2?mol L^?1. Based on these results, the Langmuir model appears to be the best representation of the adsorption of caffeine onto the copper surface. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and X-ray diffraction (XRD) were used to determine the surface morphology and the chemical composition of the copper surface in chloride media, in the absence and presence of caffeine. The results show the development of a mechanism of corrosion inhibition. In order to confirm the correlation between the inhibitory effect and the molecular structure of caffeine, quantum chemical parameters are used to calculate its electronic properties.     

无患子表面活性物及其复配体系的性质研究

对天然植物原料无患子提取物中的表面活性物的性质（临界胶束浓度、表面张力和起泡性能）及其影响因素（温度、pH、水硬度和盐度等）进行了系统的研究，结果表明无患子表面活性物具有很低的cmc和γcmc，且在一定范围内受一些因素的影响也不大，是一种理想的香波原料；同时也研究了无患子活性物与其他温和型的阴离子表面活性剂的复配体系，表明具有明显的协同增效效果。     

外加剂对陶瓷釉面表面性质的影响研究

研究了不同外加剂对陶瓷釉面表面性质的影响。研究表明 ,外加剂的加入可改变陶瓷釉面的表面张力 ,即影响液体对陶瓷釉面的润湿性能。在所选择的外加剂中 ,降低陶瓷釉面表面张力最强的为PbO ,其合适的加入量为 1.5 %。     

Preparation and characterization of trilobal activated carbon fibers

The objective of this research was to evaluate the effectiveness of several different methods for controlling the pore size and pore size distribution in activated carbon fibers. Variables studied included fiber shape, activation time, and the addition of small amounts of silver nitrate. Pure isotropic pitch and the same isotropic pitch containing 1 wt.% silver were melt spun to form fibers with round and trilobal cross sections. These fibers were then stabilized, carbonized, and activated in carbon dioxide. Field emission scanning electron microscopy (FE SEM), electron dispersive spectra (EDS), and wavelength dispersive spectra (WDS) were used to monitor the size and distribution of the silver particles in the fibers before and after activation. Each of these analyses showed that the distribution of silver particles was extremely uniform before and after activation. The fibers were also weighed before and after activation to determine the percent burn-off. The BET specific surface areas of the activated fibers were determined from N₂ adsorption isotherms measured at −196 °C. The results showed that round and trilobal fibers with equivalent cross-sectional areas yielded similar burn-off values and specific surface areas after activation. Also, activation rates were found to be independent of CO₂ flow rate. The porosity of the activated fibers depended on the total time of activation and the cross-sectional area of fibers. The N₂ adsorption measurements showed that the activated fibers had extremely high specific surface areas (greater than 3000 m²/g) and high degrees of meso- and macro-porosity. FE SEM was also used to investigate surface texture and size of pore openings on the surfaces of the activated fibers. The photos showed that silver particles generated surface macro- and mesopores, in agreement with the inferences from N₂ adsorption measurements.     

聚乳酸-聚氨酯微球的合成及其形态的研究

以低相对分子质量生物可降解D，L-聚乳酸(D，L-PLA)二醇和六亚甲基二异氰酸酯(HDI)为原料、1，4-丁二醇(BD)为扩链剂及聚乙烯基吡咯烷酮(PVP)为悬浮剂，通过悬浮聚合法初步合成了一种新型聚氨酯微球(PUMS)。用扫描电子显微镜(SEM)考察了BD的含量对微球表面形态的影响，通过激光粒度分析仪讨论了搅拌速率和PVP浓度对微球粒径及其分布的影响，用傅立叶变换红外光谱(FTIR)粒度分析仪对微球的化学结构进行了表征。结果表明，合成的微球的平均粒径随搅拌速率和PVP浓度的增加而减少，粒径分布变宽；当搅拌速率为400r／min，PVP质量分数为1．5％时。微球的平均粒径约47μm，粒径分布最窄。约在10～90μm；微球表面有孔，但随着BD含量的增加，微球表面变得相对粗糙，孔数减少，孔径减小，直至孔消失。     

经编二元网在双加压法硝酸装置的应用

通过对双加压法硝酸装置铂网使用情况和铂网脱边事故的统计，分析了氧化炉采用平编三元网存在的问题；论述了经编二元网的特性和优点；计算了铂网的生产强度和接触时间，确定了铂网丝径；总结了硝酸装置使用经编二元网的运行效果和经济效益，结果表明，吨酸氨耗降低了2．48kg，铂耗降低了10mg，经编二元网优于平编三元网。     

Effect of zeolite in surface discharge plasma on the decomposition of toluene

Toluene was decomposed in a surface discharge plasma reactor packed with various zeolites. The positioning effect of the zeolite bed was also investigated Reactor-B, in which the zeolite bed was located upstream, performed much better than Reactor-A, in which the zeolite bed was located downstream. Furthermore, the decomposition efficiency in Reactor-B increased with the capacity for toluene adsorption on zeolite, while that in Reactor-A did not. The toluene adsorbed in micropores was not decomposed effectively by direct electron impact, but was decomposed by active oxygen species generated in the plasma zone on the zeolite surface. A good correlation was also observed between toluene decomposition and ozone consumption in the downward-type reactor.     

不确定性R¨ossler 系统的自适应鲁棒跟踪控制

研究具有外部不确定性R¨ossler 混沌系统的鲁棒跟踪控制问题. 基于动态面控制原理设计自适应鲁棒控制器, 给出了系统参数的自适应更新律, 使得被控闭环系统的各误差变量一致有界. 系统输出曲线渐近跟踪任意期望轨道, 且跟踪误差能被控制在任意小的范围内, 而无须知道系统的参数及外部不确定性的界限. 基于稳定理论给出了具体的稳定性分析, 并通过数值仿真验证了该方法的有效性及鲁棒性.