BTO/PDMS/C柔性复合薄膜的制备及压电性能研究

针对压电陶瓷在实现微纳运动中普遍存在的不确定非线性因素,提出了一种新型的非线性鲁棒控制器。该控制器利用非奇异终端滑模控制实现了控制器的鲁棒性,采用时延估计技术实现了对未知项的实时补偿和无模型控制,有利于工程应用,并用鲁棒精密微分器实现对全状态的估计。运用Lyapunov稳定性理论证明了系统的闭环稳定性。半物理仿真实验表明,该控制器能够控制压电陶瓷实现亚微米精度的运动控制。理论分析和实践证明,提出的控制策略具有无模型、高精度和鲁棒性强的控制效果,工程应用性强,能有效应用于压电陶瓷驱动的微纳操作系统中。     

物质平衡-拟压力近似条件法确定气藏储量

物质平衡法作为一种有效的手段被广泛应用于气藏储量或井控储量的确定。为简便准确地确定气藏储量，笔者从物质平衡原理出发导出了"物质平衡条件"，求解气体渗流数学模型，得到了"拟压力近似条件"。将二者结合，提出了"物质平衡-拟压力近似条件法"（MB-QAC方法）。利用该方法，通过边界控制流阶段（产量波动相较于边界作用可忽略）的生产数据便可准确地计算气藏储量。定产量、定流压以及复杂生产计划条件下的数值模拟数据以及气藏实例验证了其有效性。在生产数据记录可靠的条件下，储量计算误差一般小于5%。同时，数值模拟结果表明，动态物质平衡方程是一种近似关系，拟压力近似条件对于模拟的各种情形均成立。由于考虑了岩石和束缚水的压缩性、气井产量的波动和气体性质的变化，MB-QAC方法具有一定的理论基础，对于异常高压和正常压力系统的气藏均适用，但不适用于水体活跃的气藏。     

超声洁牙器换能器的研究

本文简要叙述了超声洁牙用换能器的结构设计与工作原理,并提出了适用于换能器的压电陶瓷材料的性能要求。最后列出了这样的洁牙器的系列试验,包括临床应用的结果情况。     

Effect of sintering and poling conditions on the properties of [Pb,Sr][(Zr,Ti)(Zn,Nb)(Mg,Nb)]O3 piezoelectric ceramics system

The (Pb,Sr)[(Zr,Ti)(Zn,Nb)(Mg,Nb)]O₃ piezoelectric ceramic system with compositions close to the morphotropic phase boundary (MPB) was studied. The dielectric and piezoelectric properties of the system Pb_0.96Sr_0.04[(Zr_1-yTi_y)_0.74(Zn_1/3Nb_2/3)_0.06(Mg_1/3Nb_2/3)_0.20]O₃ were investigated, where the compositions of 0.44 ≤y ≤ 0.60 were selected. From the results of XRD and piezoelectric measurement, it was supposed that the composition withy = 0.50 - 0.51 corresponded to MPB between tetragonal and pseudocubic phase. By the way of the variation of the fabrication process, the influence of sintering and poling processes on the properties of the ceramic were studied, and we expected to find the optimal conditions of these processes. Some developed phenomena or models were introduced. After the optimal choice of the process conditions, the planar coupling factor close to 0.73 and the dielectric constant close to 3000 can be approached simultaneously in this multicomponent system.     

各向异性压电陶瓷材料

本工作制备了添有少量Pb(Zn_(1/3) Nb_(2/3))O_3,Bi(Zn_(1/2) Ti_(1/2))O_3和MnO_2的高电阻率,高密度的改性(PbCa)TiO_3压电陶瓷。这种陶瓷在150℃和施加40—50kV/cm电场条件下极化之后显示出大的各向异性压电特性。它具有高的厚度扩张模式机电藕合系数Kt,高的机械品质因素Qm低的介电常数,而平面耦合系数Kp值极小。于是,这种新的压电材料适于制作高频陶瓷滤波器超声换能器,金属探伤检测器,以及声表面波器件等。     

Comparisons with high viscosity additive effects on base and modified asphalt

In this research, three types of high viscosity additives with different volumes were added to both 70# base asphalt and SBS modified asphalt, the dynamic viscosity and high temperature performance tests were conducted. The results show that with the same volume and type of the additive, SBS modified asphalt has a much higher dynamic viscosity and high temperature grade than those of the base asphalt. When the volume of each additive type increases from 0% to 12%, the dynamic viscosity would increase in a different trend, which could be described as three stages with different increasing speeds, and the variability and the demarcation point of the adjacent two stages depend on the asphalt modification, additive type and the volume. With regard to the high temperature grade, it was found that the effect of different additive types on high temperature performance should be separated from asphalt modification.     

二氧化钛/碳纤维多孔薄膜的制备及其催化性能

以聚乙二醇(PEG)为制孔剂,通过溶胶凝胶浸渍涂覆法和烧结法将二氧化钛(TiO2)负载于经表面修饰的碳纤维(CF)上,制备多孔TiO2/CF光催化材料.采用场发射扫描电子显微镜(FE-SEM)、X射线衍射仪(XRD)表征材料的形貌和晶型结构,研究TiO2/CF光催化材料对甲基橙溶液的吸附性能,并以质量浓度为80 mg/...     

氟金云母陶瓷车削参数对刀具磨损的影响

对氟金云母可加工陶瓷进行车削加工试验,分析了切削中的刀具磨损特性,讨论了影响刀具磨损率的因素。以单因素实验法分别考察了刀具材料、冷却条件、切削深度、进给速度等对刀具磨损的影响规律。结果表明:刀具磨损过程可划分为三个阶段,自来水冷却可降低刀具磨损率,高速钢刀具不能满足加工需要,陶瓷刀具相对较好;切削深度对刀具磨损率的影响曲线为一抛物线段,进给速度对刀具磨损的影响曲线为一余弦线段;车削氟金云母陶瓷对刀具磨损过程与切削金属相似。     

NATURAL CONVECTIVE HEAT AND MASS TRANSFER BY THE COUPLING OF TEMPERATURE CRADIENT AND CONCENTRATION GRADIENT IN A POROUS MEDIUM

ＮＡＴＵＲＡＬＣＯＮＶＥＣＴＩＶＥＨＥＡＴＡＮＤＭＡＳＳＴＲＡＮＳＦＥＲＢＹＴＨＥＣＯＵＰＬＩＮＧＯＦＴＥＭＰＥＲＡＴＵＲＥＣＲＡＤＩＥＮＴ　ＡＮＤＣＯＮＣＥＮＴＲＡＴＩＯＮＧＲＡＤＩＥＮＴＩＮＡＰＯＲＯＵＳＭＥＤＩＵＭ￥ＣｈｅｎＢａＯ－Ｍｉｎｇ；Ｆ...     

整装式液体随行装药关键技术研究

介绍了在随行装药技术上的一个新思路，即采用多孔介质整装式液体随行装药方案。利用密闭爆发器模拟火炮膛的内工况，系统研究了随行装药的三项关键技术，即点火延迟，随行药燃速可控和携带可靠、附加重量轻，试验结果表明，该方案原理可行，能够用于火包试验。