Deformation and failure study of surrounding rocks of dynamic pressure roadways in deep mines

In order to understand the change rules of stress-displacement in surrounding rocks of dynamic pressure roadways in deep mines and to obtain a theoretical basis for analyses of roadway stability and designs of support,we established a coupling equation of adjacent rock strength,mining stress and supporting resistance on the basis of an elastic-plastic theory of mechanics.We obtained an analytical solution for stress and displacement distribution of elastic and plastic regions in surrounding rock of dynamic pressure roadway..Based on this theory,we have analyzed the changes in stress-displacement in elastic and plastic regions of surrounding rocks of dynamic pressure roadways in the Haizi Coal Mine.The results show that:1) radial and tangential stress change violently within the first 4 m from the inner surface of a roadway after excavation;radial stress increases while tangential stress decreases within a range of about 6 m from the inner surface of the roadway as a function of q3;2) radial and tangential stress increase with an increase in the mining pressure coefficient k;the increase in the rate of tangential stress is greater than that of radial stress;3) the radial displacement of the inner surface of roadways decreases with an increase in q3,provided that k remains unchanged.     

基于ZMP的双足机器人稳定性分析

引入双足机器人研究中一个重要物理量——零力矩点ZMP（zero Moment Point）,研究其计算和测量方法,利用其分析双足机器人在单腿和双腿支撑时的作用范围,最后在二维和三维平面内对机器人的ZMP计算进行探讨,为稳定步态的设计做了理论铺垫。     

利用Liapanov直接方法判定差分方程稳定性

研究差分方程稳定性的强有力的方法是Liapanov直接方法,这一方法的核心思想是针对所研究的方程,构造出其相应的Liapanov函数,利用它来判定方程的稳定性．     

Investigation on film cooling characteristics from a row of converging slot-holes on flat plate

Experimental and numerical researches were conducted to investigate the cooling performance of a single row of consoles (converging slot-hole) on a large-scale flat-plate model. The results show that the coolant flow from a row of consoles shows good lateral uniformity of adiabatic effectiveness, with regions of slightly enhanced cooling occurring between the consoles. For the console cooling geometry, the interaction between coolant jet from inclined console and the mainstream flow results in reasonable vo...     

色谱顶空法测活度系数及对三元极性体系液液平衡预测

用气相色谱顶空分析法测定 18组部分互溶三元极性体系在完全互溶区的 3个组分活度系数 ,由此拟合出 U NIQU AC过量自由焓模型参数 ,再用 U NIQUAC方程预测液液平衡。这一方法曾很好地用在水-正烷烃 -醇体系。将此法拓展到含醇、酮、酯 ,醚、卤烷烃和水等多种极性组分的三元体系液液平衡的预测 ,其结果与文献的液液平衡数据比较 ,平均均方根误差 1.4 1% ,表明本法对含极性组分的体系仍然可行     

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.     

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.     

Temperature stability and fracture toughness of Nd-Fe-B magnets

Temperature stability and toughness of magnets are very important properties especially for application in motor. In this paper, it is found that temperature stability and toughness of magnets are improved when Fe is substituted with Co andheavy rare earth is substituted for Nd in part and suitable rich B grain-boundary phase is added. In addition, heavy rare earth substitution decreases the remanence temperature coefficient greatly, but has a little effect on Curie temperature of the magnets, which is beneficial to Nd-Fe-B magnets for the application in motor.     

多孔薄壁扁管连续挤压模的研制

介绍了连续挤压模的生产工艺过程 ,模具主要结构及设计参数 ,分析了生产中存在的问题以及采取的措施 ,充分发挥了连续挤压设备的潜力 ,扩大了产品品种     

泡沫塑料表面的磁控溅射镀膜技术研究

对硬质聚氨酯泡沫塑料进行适当的前处理(涂刮不饱和聚酯腻子和喷涂双组份聚氨酯清漆),再采用磁控溅射镀膜技术对其进行紫铜T2镀膜,能够有效地降低泡沫塑料的吸水率,提高尺寸稳定性.