双足机器人行走稳定性研究

双足机器人行走的稳定性是双足行走最为重要的衡量指标之一.针对传统的基于零力矩点（ZMP）步态稳定性判据方法,分析了ZMP、COP的相互关系,表明在双足机器人与水平地面无粘性力和无吸附力作用下,其ZMP即为压力中心点COP.基于具有足趾关节的双足机器人足底支撑面多种变化,提出对多点接触时支撑多边形区域描述.结合ZMP/COP、COG的在支撑面内相对位置,提出了基于ZMP/COP、COG的综合稳定性判据.经仿真分析,与传统单一的ZMP稳定性判据相比,该综合稳定性判据能够更为准确地反映步态的稳定性.     

红外与可见光复合寻的制导中的快速图像配准方法

对现有多传感器图像配准方法在红外与可见光复合寻的制导应用中存在的计算量大等不足,提出了一种基于部分Hausdorff距离的快速方法和一种两集合相似度的定义,从而实现了有效减小误匹配特征点对的红外与可见光图像快速配准方法.此算法通过分别提取两幅图像边缘上显著特征点,再根据提出的快速方法和两集合相似度定义,粗略估计出图像间的旋转角度、平移量;然后依据此估计值,缩小特征点匹配时匹配特征点搜索范围,求得一致特征点对;最后用最小二乘法求解最优变换参数.实验结果表明了该方法的有效性、快速性.     

具有收获率的HollingⅢ类功能性反应捕食模型的定性分析

研究了在线性收获率条件下两种群都具有密度制约项的HollingⅢ类功能性反应的捕食模型,利用微分方程定性分析理论,对模型进行了定性分析.讨论了模型的食饵等倾线和捕食者等倾线的性质,并且根据它们的位置关系给出了模型唯一正平衡点存在的充要条件,研究了模型各个平衡点的性态,得到了模型的一切解是正向有界的,同时通过构造Dulac函数,由Dulac判断定理得到了模型不存在极限环的条件,并给出了唯一正平衡点全局渐近稳定的充分条件.     

Thermal analysis of montmorillonites modified with quaternary phosphonium and ammonium surfactants

The thermal stability of seven organically modified montmorillonites (‘organoclays’) has been investigated using differential thermal analysis, differential scanning calorimetry, and thermogravimetry in conjunction with X-ray diffractometry. Six organoclays were synthesised by replacing the interlayer inorganic cations, initially present, with quaternary phosphonium and ammonium surfactant cations. The samples modified with tetrabutylphosphonium (TBP), and butyltriphenylphosphonium (BTPP) ions have an appreciably higher thermal stability than the octadecyltrimethylammonium (ODTMA)-modified clays. Thus, in the case of TBP- and BTPP-modified montmorillonites, the onset temperature of decomposition is close to 300 °C. Samples modified with hexadecyltributylphosphonium (HDTBP) ions have a lower onset temperature of decomposition of 225 °C. In comparison, the onset temperature for ODTMA-montmorillonites (obtained at different concentrations of ODTMA-bromide) ranges from 158 to 222 °C, being highest where the concentration of intercalated surfactant is lowest. The onset temperature for a commercial alkylsilane-treated quaternary ammonium-modified organoclay (S-BEN N-400FP) is 207 °C. The basal spacing of the TBP- and BTPP-modified clays is 1.7–1.8 nm, indicating a monolayer arrangement of quaternary phosphonium ions in the interlayer space, while the value of 2.5 nm for HDTBP-montmorillonite indicates a more open structure. The ODTMA-modified samples have basal spacings ranging from 1.9 to 2.1 nm, indicative of a bilayer to pseudo-trilayer arrangement. The exceptionally high basal spacing of 3.4 nm for the S-BEN N-400FP organoclay might be due to interlayer penetration of organosilane hydrolysis products during synthesis. The thermal properties of organoclays are apparently related to the nature of the surfactants and their arrangement in the interlayer space of montmorillonite.     

An analytical model for freeboard and in-bed limestone sulfation in fluidized-bed coal combustors

A new model, which combines in-bed and freeboard sulfation, significantly improves the ability to predict sulfur capture by limestone sorbents in fluidized-bed coal combustors. In this model, the in-bed hydrodynamics are described in terms of a bubble phase and an emulsion phase while the freeboard region has only a diluted emulsion phase. The solids, which are in the emulsion phases, are considered to be completely back-mixed; the gaseous bubble phase travels in plug-flow but exchanges with the emulsion phase. The sulfation reaction occurs principally in the emulsion phase and the reaction rate is a direct function of the sulfur dioxide concentration, the extent of the calcium oxide conversion (as measured by a thermogravimetric analyzer), and the amount of limestone present in the bed and in the freeboard. The amount present, or holdup, in the free-board is calculated from empirical correlations for elutriation and from particle-time trajectories as predicted from equations of motion.The model indicates that a significant amount of sulfur capture can occur in the freeboard region, especially with high superficial gas velocities and small particle sizes, both of which lead to increased freeboard holdup. For an overall sulfur retention of 90%, approximately 9% of the sulfur is predicted to be captured within the freeboard above a combustor bed 1.8 m by 1.8 m by 1.2 m high of 1200 μm diameter limestone particles that are fluidized at 2.4 m/s. The model also predicts that the sulfur captured by the entrained particles is negligible. These predictions compare favorably with the actual sulfur retentions experienced in similar sized pilot-scale combustors.     

Dynamic buffering performance of the honeycomb paperboard filled with polyurethane

A new kind of composite buffering material was made by filling the voids of honeycomb paperboard with polyurethane. Drop tests were performed to evaluate the dynamic energy absorption capacity of the material. Based on the tests results, we analyzed the mechanical behaviors of the material under different conditions and obtained the inherent influencing laws of some factors on the material＇s dynamic buffering performance. It was shown that the dynamic buffering performance varied directly with impact velocity, and inversely with the void diameter, thickness and buffeting area of the composite material.     

基于解析解的四阶PDE曲面裁剪方法

该文提出了一种可以广泛应用于四阶PDE曲面的裁剪方法。利用PDE的参数域内的曲线在曲面上投影,得到所求裁剪曲面的边界曲线,然后通过边界曲线的导矢与曲面在边界曲线处的法向量得到边界曲线处的跨界导矢,最后以求得的裁剪曲面的边界曲线以及裁剪曲面在边界曲线处的跨界导矢为PDE曲面的边界条件,用四阶的PDE曲面方程求得PDE裁剪曲面。     

“顶岗置换”模式培养高师准幼儿教师的探讨

＂顶岗置换＂模式不仅促进了一线学前教师的职后培训,更有利于高师准幼儿教师的培养;同时,＂顶岗置换＂对高师准幼儿教师的培养提出了相应的挑战：顶岗对学生的高要求——能否从学生变为教师,顶岗对学生的低回报——能否从教中学。提出相应策略,促进＂顶岗置换＂模式下准幼儿教师的培养。     

南通进入“GDP 5000亿元城市俱乐部”后的思考

理性地看待2013年南通实现的地区生产总值超5 000亿元和人均GDP超1万美元的“双跨越”,分析南通市经济社会发展存在的不足,确定今后南通的发展道路.通过对比分析全国27个地区生产总值超5 000亿元城市的经济社会发展基本情况,重点研究南通市与27市,尤其是其中7个地级市之间经济社会发展的差距,并提出发展对策措施.     

Immobilizing chromium in stainless steel slags with MnO addition

This work investigates the stabilizing impact of MnO on the leaching behavior of hazardous Cr-containing CaO-SiO₂-Al₂O₃-Cr₂O₃-MnO stainless steel slags after equilibrating at various elevated temperatures and evaluates the potential immobilization of Cr into a MnCr₂O₄ spinel phase from the existing Cr₂O₃ phase. The MnCr₂O₄ spinel phase was found to be an excellent Cr-stabilizer in stainless steel slags, where the leaching tendency of potentially hazardous Cr-related ions decreased with higher MnO content and lower equilibration temperatures within the range of 0 to 15 mass pct. and 1500 to 1300°C, respectively. Thermodynamic calculations by conducting the phase stability diagram also showed that the MnCr₂O₄ spinel phase was relatively stable and the Ca₃Si₂O₇ (Ca_3-xMn_xSi₂O₇) phase was relatively unstable compared with other crystal phases in acid extractant with pH value of 3.2. Combined with the scanning electron microscopy and X-ray powder diffraction results along with the thermodynamic calculations, the leached Cr-related ions was predominantly originating from the unstable amorphous glass phase.