A novel preparation method for NiCo2O4 electrodes stacked with hexagonal nanosheets for water electrolysis

In this paper, we describe the preparation of a porous nanosheet-stacked NiCo₂O₄ composite electrode using a novel electrophoretic deposition (EPD) calcination method. The effects of the deposition time and voltage, and of the calcination temperature have been investigated. The microstructure of the deposited films in the electrodes before and after calcination has also been investigated. The electrocatalytic properties of the electrodes have been investigated using cyclic voltammetry and polarization curves. The electrode films produced using this new technique have a porous structure composed of stacked hexagonal NiCo₂O₄ nanosheets. The resulting electrodes exhibit good electrocatalytic properties for water electrolysis.     

Toughened electrospun nanofibers from crosslinked elastomer‐thermoplastic blends

A crosslink‐able elastomeric polyester urethane (PEU) was blended with a thermoplastic, polyacrylonitrile (PAN), and electrospun into nanofibers. The effects of the PEU/PAN ratio and the crosslinking reaction on the morphology and the tensile properties of the as‐spun fiber mats were investigated. With the same overall polymer concentration (9 wt %), the nanofiber containing higher composition of PEU shows a slight decrease in the average fiber diameter, but the tensile strength, the elongation at break and tensile modulus of the nanofiber mats are all improved. These tensile properties are further enhanced by slight crosslinking of the PEU component within the nanofibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

SVD‐Based Accurate Identification and Compensation of the Coupling Hysteresis and Creep Dynamics in Piezoelectric Actuators

In this paper, the coupling hysteresis and creep in piezoelectric actuators are identified and compensated for accurate tracking. First, we present the coupling hysteresis and creep model in smart actuators. Next, a complete identification strategy is designed according to the properties of the Preisach model. Then, an approach for parameter updating of the coupling model is provided. With the identified hysteresis and creep, the model‐based inversion compensation is designed. Finally, we apply the model identification and compensation to a piezoelectric stage to demonstrate the effectiveness of the proposed approaches. Significant reduction of the tracking error is achieved with the model‐based inversion feedforward compensator in which the relative errors at 10 Hz and 50 Hz are reduced to 1.85% and 4.53%, respectively. In addition, the model‐based feedforward is augmented with an integral feedback controller. With the composite controller, the relative errors at 10 Hz and 50 Hz are reduced to 0.42% and 3.04%, respectively.     

火电厂发电机组常见的电气故障与维修研究

发动机组是火电厂各生产环节中重要的组成部分,其运行效率不但决定了生产效率,还关系着各类生产资源应用的有效性,对实现节能降耗具有重要意义,所以,必须加强对其运行稳定性的管理。分析了火电厂发动机组常见电气故障,并提出了相应的解决措施。     

通信用片式介质陶瓷双工器的设计与制作

介绍了通信用介质陶瓷双工器的设计方法和制作过程。该双工器是由接收滤波器和发射滤波器组成的。每种滤波器是由一块高介电常数、高Q值和接近零温度系数的介质陶瓷块制成的。这个陶瓷块上包含两个四分之一波长同轴谐振腔、输入及输出电极和耦合装置,并且输入及输出电极在陶瓷块的同一侧面上,因此滤波器具有体积小巧,结构稳定和安装方便的特点。采用介电常数为90的陶瓷材料制作了中心频率分别为903MHz和927MHz的接收和发射滤波器,经网络分析仪测试,各项技术指标满足设计要求。     

Effect of randomization on the oxidative stability of corn oil

Randomized corn oil TAG oxidized much faster than natural oil, but after purification with alumina, they oxidized at the same rate. We showed that this effect could not be attributed to a difference, in total tocopherols in the randomized and natural oils. Polar material recovered from the alumina treatment was fractionated by TLC, and a pro-oxidant effect was found in the fractions containing MAG and DAG. However, MAG and DAG, although mild pro-oxidant could not account for the pro-oxidant effect generated by randomization. No other compounds could be detected in the MAG fraction by MS. The pro-oxidant effect of randomized oil disappeared when EDTA or citric acid was added in sufficient amounts. The pro-oxidant effect of randomized corn oil was increased by the incorporation of additional copper or iron at a concentration that did not catalyze oxidation of the purified oil. Treatment of corn oil with ascorbic acid, ascorbyl-6-palmitate, ethyl acetoacetate, ethyl diacetoacetate, and acetylacetone did not reproduce the effect of the unknown pro-oxidant. Although the identity of the pro-oxidant is still unknown, we have confirmed that it is produced during randomization; it does not have pro-oxidant activity alone, but it facilitates the catalytic activity of the transition metal ions.     

Robust state estimation for uncertain linear systems with deterministic input signals

In this paper, we investigate state estimations of a dynamical system in which not only process and measurement noise, but also parameter uncertainties and deterministic input signals are involved. The sensitivity penalization based robust state estimation is extended to uncertain linear systems with deterministic input signals and parametric uncertainties which may nonlinearly affect a state-space plant model. The form of the derived robust estimator is similar to that of the well-known Kalman filter with a comparable computational complexity. Under a few weak assumptions, it is proved that though the derived state estimator is biased, the bound of estimation errors is finite and the covariance matrix of estimation errors is bounded. Numerical simulations show that the obtained robust filter has relatively nice estimation performances.     

Photopolymerization of methyl methacrylate initiated by benzophenone/aromatic tertiary amines

Summary The photopolymerization of methyl methacrylate initiated by benzophenone-tertiary aromatic amines was studied under irradiation at 365 nm. The initiating amino radicals were investigated with combined ESR and spin-trapping method. The rate of polymerization for different amines was found in the sequence of p-hydroxymethyl-N,N-dimethylaniline>N,N-dimmethyltoluidine>N,N-dimethylaniline>p-methyl-N,N-dihydroxyethylaniline. The influence of diphenylmethanol on the polymerization reveals the incapacity of the benzophenone ketyl radical to initiate, while the amino end-group was detected in the polymers. This end-group can interact with benzophenone again, leading to initiate further polymerization to give a copolymer.     

工业循环冷却水用BC－653杀生剂的抗菌性能测定

本文对ＢＣ－６５３杀生剂进行了室内抗菌实验，着重阐述了投药量对杀菌率的影响。结果显示该杀生剂与国外同类产品杀菌力基本一致。     

聚硅氧硅氮烷改性烯丙基酚醛杂化树脂的研究

采用二苯基硅二醇与含乙烯基的聚硅氮烷（SiN08）反应，合成了三种含二苯基硅氧链节的聚硅氧硅氮炕MPSZ-1、MPSZ-2、MPSZ-3；并用于烯丙基酚醛（AP）树脂的改性。与纯AP树脂相比，聚硅氧硅氮烷改性烯丙基酚醛树脂（MPSZ／AP）的热分解温度和高温残余质量分数都有较大提高。在N2气氛中，AP的质量损失率为5％时的温度为383℃，900℃残余质量分数为33．0％；MPSZ-1／AP的质量损失率为5％时的温度为465℃，900℃残余质量分数为74．4％。在空气气氛中，AP的900℃残余质量分数仅1．5％，MPSZ-1／AP的900℃残余质量分数为33．8％。MPSZ-1／AP体系的热分解温度和高温残余质量分数与SiN08／AP体系相当，而其固化质量损失率较低，仅为4．4％，适合采用树脂传递模塑（RTM）成形工艺制成复合材料。对聚硅氮烷／AP树脂固化过程的初步研究表明，Si—N键在固化过程中起主要作用。