聚合物熔体三维等温流动的罚有限元分析

本文针对幂律流体和非线性粘弹性PTT流体,采用罚有限元法,形成了求解聚合物熔体三维等温流动速度场和粘弹性应力场的有限元模型．对非线性粘弹性PTT流体,为了降低模拟计算对计算机硬件的要求,并使模拟计算更加稳定,采用了去耦算法,包括拟体力方法和动量方程的椭圆类方程转化方法等。文中还给出了总体有限元方程组的形成和求解过程。     

Highly stretchable self-sensing actuator based on conductive photothermally-responsive hydrogel

Soft robots built with active soft materials have been increasingly attractive. Despite tremendous efforts in soft sensors and actuators, it remains extremely challenging to construct intelligent soft materials that simultaneously actuate and sense their own motions, resembling living organisms’ neuromuscular behaviors. This work presents a soft robotic strategy that couples actuation and strain-sensing into a single homogeneous material, composed of an interpenetrating double-network of a nanostructured thermo-responsive hydrogel poly(N-isopropylacrylamide) (PNIPAAm) and a light-absorbing, electrically conductive polymer polypyrrole (PPy). This design grants the material both photo/thermal-responsiveness and piezoresistive-responsiveness, enabling remotely-triggered actuation and local strain-sensing. This self-sensing actuating soft material demonstrated ultra-high stretchability (210%) and large volume shrinkage (70%) rapidly upon irradiation or heating (13%/°C, 6-time faster than conventional PNIPAAm). The significant deswelling of the hydrogel network induces densification of percolation in the PPy network, leading to a drastic conductivity change upon locomotion with a gauge factor of 1.0. The material demonstrated a variety of precise and remotely-driven photo-responsive locomotion such as signal-tracking, bending, weightlifting, object grasping and transporting, while simultaneously monitoring these motions itself via real-time resistance change. The multifunctional sensory actuatable materials may lead to the next-generation soft robots of higher levels of autonomy and complexity with self-diagnostic feedback control.     

Polymer electrolytes and interfaces in solid-state lithium metal batteries

The polymer electrolyte based solid-state lithium metal batteries are the promising candidate for the high-energy electrochemical energy storage with high safety and stability. Moreover, the intrinsic properties of polymer electrolytes and interface contact between electrolyte and electrodes have played critical roles for determining the comprehensive performances of solid-state lithium metal batteries. In this review, the development of polymer electrolytes with the design strategies by functional units adjustments are firstly discussed. Then the interfaces between polymer electrolyte and cathode/anode, including the interface issues, remedy strategies for stabilizing the interface contact and reducing resistances, and the in-situ polymerization method for enhancing the compatibilities and assembling the batteries with favorable performances, have been introduced. Lastly, the perspectives on developing polymer electrolytes by functional units adjustment, and improving interface contact and stability by effective strategies for solid-state lithium metal batteries have been provided.     

Influences of the inner diameter of the solid shielding tube on the characteristics of the radio-frequency cold atmospheric plasma jet

Active control of the local environment of the cold atmospheric plasma (CAP) jet is of great importance in actual applications since the CAP operates in an open atmosphere with the inevitable entrainment of the surrounding cold air. In this paper, the solid shielding effects of the cylindrical quartz tubes with different inner diameters on the characteristics of the CAP jets driven by a radio-frequency (RF) power supply are studied experimentally. The experimental results show that the total length of the shielded plasma jet can be increased significantly by an appropriate combination of the quartz tube inner diameter and that of the plasma generator nozzle exit with other parameters being unchanged. This phenomenon may be qualitatively attributed to the loss of diffusion of the charged particles in the radial direction under different inner diameters of the quartz tubes. Compared with the plasma free jet, the plasma shielding jet is produced with optimized parameters including longer plasma jet length, higher concentrations of chemically reactive species, higher rotational, vibrational, and electron excitation temperatures when the inner diameters of the solid shielding tube and the generator nozzle exit are the same. A maximum plasma jet length of 52.0 cm is obtained in contrast to that of 5.0 cm of the plasma free jet in this study. The experimental results indicate that the solid shielding effect provides a new method for the active control of the local environment of the RF-CAP jet operating in an open atmosphere.     

水性聚氨酯-聚二甲基硅氧烷共混体系固态聚合物电解质的光谱学研究

以水性聚氨酯(WPU)-聚二甲基硅氧烷(PDMS)共混体系为聚合物基体,通过添加不同质量分数的高氯酸锂(LiClO4)得到一系列固态聚合物电解质.交流阻抗测试结果显示,当LiClO4质量分数为15 %时体系电导率最高,并且温度与电导率关系基本符合Arrhenius方程.采用傅立叶红外光谱(FT-IR)对聚合物电解质中锂离子与羟基及醚氧基之间的相互作用分析显示,当LiClO4质量分数为15%时,锂离子与羰基及醚氧基的配位作用均达到饱和状态.拉曼光谱(Raman)研究结果表明,该聚合物体系对盐具有较好的溶解能力,增加盐浓度后,可使体系中有效离子的相对比例增加,有利于离子传输.     

面向数据挖掘的静态电源综合故障诊断研究

静态电源是机场桥载设备最重要的组成部件之一,应用非常广泛。然而,其产生的频发故障会造成设备利用率低、修复率时长和经济损失等问题,在基于桥载设备的安监系统上,提出了静态电源综合故障诊断方法,通过数据挖掘软件,建立了静态电源故障诊断预测模型。通过在线数据库测试结果表明得到了综合故障诊断方法在预测静态电源故障上显现的特点,得到了静态电源的未来状态,实现了对静态电源的实时故障进行预测,进而为解决故障提供方向和目标,最终达到降低经济损失最大化的目的。     

径向磁液轴承定子温升及热变形研究

提出一种新型的磁液轴承,以电磁悬浮支承为主、静压支承为辅,实现双重支承,并可以实时调控。通过建立磁液轴承的有限元分析模型,对其进行流-固-热耦合求解,得到轴承的流场、温度、应力及应变分布云图。通过调整轴承系统的结构参数（进油孔直径和线圈匝数）及运行参数（输入电流、进油流量、转子转速）分别进行有限元建模,利用ANSYS软件进行仿真分析,求解不同参数对轴承温升及定子热变形的影响规律。结果表明：流体造成的压力在进油孔内最高为1 MPa,流体在油膜处流速最高为0.8 m/s;轴承定子温度分布对称,有利于散热。研究结果为磁液轴承系统的优化设计提供理论依据。     

不同基质食品中乌洛托品残留量的检测方法研究

目的 建立适用于猪肉、豆干、豆腐、腐竹基质中乌洛托品的分析检测方法.方法 比较提取方式、浓缩温度、固相萃取柱、微孔滤膜等关键因素测定样品中乌洛托品,样品用乙腈超声提取,35℃旋蒸浓缩,经cleanert PCX固相萃取柱及0.22μm亲水PTFE微孔滤膜净化,高效液相色谱串联质谱仪进行检测.结果 乌洛托品在5～500μ...     

脂肪醇嵌段聚醚丙烯酸酯与丙烯酰胺共聚物及其水溶液特性的研究

本文合成了脂肪醇嵌段聚醚丙烯酸酯单体 ,并与丙烯酰胺共聚 ,得到共聚物PEPO PAM。芘荧光光谱分析表明 ,该聚合物在水溶液中依靠分子链上的疏水基团形成一定的缔合作用。PEPO PAM相对于部分水解聚丙烯酰胺 (HPAM )具有更好的增粘性。通过调整分子的组成 ,可使该聚合物不仅具有较强的增粘性 ,同时具有良好的水溶性。     

固体Ti(SO4)2催化合成苯甲酸甲酯

以固体Ti(SO4) 2 为催化剂、苯甲酸和甲醇为原料合成了苯甲酸甲酯。考察了催化剂用量、反应时间、醇酸比对酯产率的影响。实验结果表明 ,最佳实验条件为 :在 6 5～ 75℃下 ,催化剂用量为 8% (占苯甲酸质量分数 )、反应时间为 3h、甲醇与苯甲酸用量比为 10∶1,所得到的酯产率达 93 0 %。