Stability of a class of switched stochastic nonlinear systems under asynchronous switching

The stability of a class of switched stochastic nonlinear retarded systems with asynchronous switching controller is investigated. By constructing a virtual switching signal and using the average dwell time approach incorporated with Razumikhin-type theorem, the sufficient criteria for pth moment exponential stability and global asymptotic stability in probability are given. It is shown that the stability of the asynchronous stochastic systems can be guaranteed provided that the average dwell time is sufficiently large and the mismatched time between the controller and the systems is sufficiently small. This result is then applied to a class of switched stochastic nonlinear delay systems where the controller is designed with both state and switching delays. A numerical example illustrates the effectiveness of the obtained results.     

一种笔形无线鼠标的设计

介绍一种利于书写、绘画的笔形无线鼠标的设计。该笔形无线鼠标不仅具有传统无线鼠标的所有功能,还在外形结构及定位方式上有了人性化的改进。首先将传统鼠标形状改为笔形设计更利于书写、绘画时使用,其次将光学定位改用加速度传感器定位设计,使其可以脱离桌面悬空使用。调查表明,笔形无线鼠标具有广泛的应用领域。     

核电厂辅助电源系统铁磁谐振分析及处理

某核电厂中压电气系统为6.6kV中性点不接地系统,以该电厂实际发生的一起辅助电源系统铁磁谐振实例出发,通过建模计算,剖析在外部因素的激发下电压互感器发生铁磁谐振的根本原因,并制定相应的预防措施,为核电厂安全可靠运行提供有力的外电源保障.     

还原氧化石墨烯气凝胶/二十烷相变材料的制备及性能

以氧化石墨烯(GO)为原料,采用胶体团聚法制备了还原氧化石墨烯气凝胶,再通过自扩散获得了还原氧化石墨烯气凝胶/二十烷(r-GO aerogel/eicosane)复合相变材料,研究了复合材料结构与性能的关系.采用热重分析仪(TGA)和差示扫描量热仪(DSC)测试了二十烷和复合材料的热性能,确认了二十烷质量分数与复合材料焓值的关系,探讨了相变循环次数对材料稳定性的影响.结果表明,复合材料的焓值与二十烷的质量分数成正比;经过50次相变循环后,二十烷的理论质量分数为95％的样品(PCM4)的储能性能仍然保持稳定.热导性能分析表明,还原氧化石墨烯气凝胶可以改善二十烷的热导率.此外,通过太阳光模拟测试计算出复合材料的光热转换效率为55％.     

Synthesized K2O·11Al2O3 as sagger matrix for the preparation of Li-ion battery cathode materials at high temperatures

Refractory materials such as mullite, andalusite, forsterite, and cordierite are generally used to prepare saggers for the calcination of Li-ion battery Li(Ni_xCo_yMn_z)O₂ (LNCM) cathode material. However, these compounds are prone to be attacked by the LNCM materials, thereby leading to short life spans and contamination of the Li-ion battery cathode materials. To improve the corrosion resistance of refractory sagger materials, the most clear cut-way is enhancing the corrosion resistance of matrix using a new refractory component. Potassium aluminate (K₂O·11Al₂O₃, KA₁₁) with an excellent corrosion resistance against alkaline oxide was synthesized via solid-state method using potassium carbonate (K₂CO₃) and industrial alumina powder (Al₂O₃). Interactions between KA₁₁ and LNCM cathode materials at 800°C–1100°C were characterized by refractory-LNCM precursor laboratory-scale tests to understand the corrosion behavior of KA₁₁. The microstructure and phase composition of synthesized KA₁₁ and the calcined KA₁₁-LNCM mixture cylinders were analyzed with SEM and XRD. The observations reveal that KA₁₁ shows a better corrosion resistance to LNCM materials compared with mullite, cordierite, and forsterite. The addition of synthesized KA₁₁ also favors the thermal shock resistances of mullite-based sagger materials.     

无机盐对新疆油田三元复合驱界面性能影响研究

界面性能对复合驱提高采收率有重大的影响,界面张力越低,洗油效率越高;Zeta电位越高,油水乳状液越稳定。研究了各类无机盐对新疆油田复合驱界面性能的影响。结果显示,Zeta电位的绝对值随着无机盐浓度的增高而增大;无机碱中,碳酸根离子降低界面张力效果最好,氢氧根次之,碳酸氢根最差;阳离子中,钾离子降低界面张力效果最好,其次是钠离子,镁离子会略微提高界面张力,钙离子则会大幅度提高界面张力;阴离子中,与硫酸根相比,氯离子能更好地降低界面张力。通过以上研究,确定了Q站污水处理站外排水更适合三元复合驱配液。     

含砷氰化尾矿回填利用污染控制技术试验研究

针对某黄金生产企业含砷氰化尾矿污染特征,开展了搅拌洗涤法、臭氧氧化法、酸化溶砷法、铁盐固砷法等多种无害化方法联合处理试验研究,旨在将该含砷氰化尾矿处理至满足氰渣规范回填利用污染控制要求。结果表明：该含砷氰化尾矿回填利用污染控制技术工艺为压滤调浆搅拌洗涤+臭氧氧化+酸化溶砷+铁盐固砷,最佳参数为原矿浆压滤后加水调浆,矿浆浓度40%,臭氧投加量0.66 g/L,酸化溶砷pH值3、曝气量0.1 m³/h、反应时间2 h,铁盐固砷七水合硫酸亚铁投加量20.0 g/L、反应时间1 h。研究结果为该黄金生产企业含砷氰化尾矿回填利用提供了技术支撑。     

缩进式管子-管板焊接工艺

管子-管板焊接是换热器生产的关键工序,通过对缩进式管子-管板焊接技术进行的试验和分析,确定了最佳的焊接参数,供换热器制造厂有关技术人员参考.     

铸件缺陷修补方法

简述了铸件缺陷的谷种修补方法及工艺，指出液膜溶解扩散焊是一种比较先进的焊补方法。     

PZT／Terfenol-D／PVDF层状复合磁电材料谐振特性

采用热压法制备出二层锆钛酸铅(PZT)／聚偏氟乙烯(PVDF)与1层Tb0.28Dy0.72Fe2(Terfenol-D)／PVDF叠层结构的三元复合磁电材料，研究了不同PVDF含量，以及不同层厚比tp／L对样品的介电常数、介电损耗、电阻率、谐振频率以及磁电转换系数αE33，αE31的影响规律，结果显示PVDF的含量和层厚比都存在最佳值(最佳值出现在产0．5，tp／L=2／7)，并且在这个最佳值处，磁电转换系数达到最大。