Friction-induced vibration considering multiple types of nonlinearities

Nonlinear Dynamics - The friction-induced vibration of a novel 5-DoF (degree-of-freedom) mass-on-oscillating-belt model considering multiple types of nonlinearities is studied. The first type of...     

含烷氧磺酸锂盐及对称星形醚的聚环氧乙烷基聚合物电解质的制备及电化学性能

合成了低聚度烷氧磺酸锂盐（LiSA(EO)n)和对称星形醚（STEO）增塑剂,并制备了聚环氧乙烷（PEO）基聚合物电解质。 研究了PEO16+LiSA(EO)n体系的锂离子迁移数和电导率与锂盐结构的关系,实验结果表明,LiSA(EO)n代替LiClO4作为锂盐时,其电导率得到提高,而且聚合物电解质的锂离子迁移数随着烷氧磺酸锂盐阴离子体积的增大而增加,并且其中PEO16+LiSA(EO)2体系的锂离子迁移数达到0.35。 STEO可明显地提高PEO16-LiSAEO-STEO体系的电导率,PEO16-LiSAEO-20%STEO室温电导率可达到0.5×10-4 S/cm。 通过DSC实验结果表明,STEO的加入,可有效降低聚合物电解质体系的熔融温度和结晶度,PEO16-LiSAEO-20%STEO电化学稳定窗口在4.4 V以上,可满足锂电池的应用要求。     

聚4-(2-吡啶偶氮)间苯二酚膜修饰玻碳电极测定过氧化氢

利用循环伏安法（-0.5～2.2 V）将4-(2-吡啶偶氮)间苯二酚(PAR)电聚合修饰到玻碳电极表面,制备了聚PAR膜过氧化氢（H2O2）传感器。 并采用循环伏安法和计时安培法研究了修饰电极的电化学性质和对H2O2的响应特性。 结果表明,PAR膜修饰电极在低的电位下对H2O2具有优异的电催化还原效应。 在磷酸盐缓冲溶液中(pH=8.0)用计时安培法对H2O2进行了测定（工作电位0.45 V）,响应电流与其浓度在2×10-5～1.76×10-3 mol/L范围内呈良好的线性关系,线性相关系数r=-0.999 83,检测限(S/N=3)为3 μmol/L。该修饰电极灵敏度高、稳定性好、制备简单,在H2O2的测定中对抗坏血酸、尿酸和葡萄糖有较好的抗干扰性。     

磁性隧道结自旋极化电子的隧穿特性

铁磁金属间通过中间层的自旋极化电子隧穿产生的磁性耦合,在自旋电子器件中有许多潜在的应用.考虑由一平面磁性势垒层隔开的两铁磁性金属电极构成的磁性隧道结,针对中间层形成的矩形势垒,在近自由电子模型的基础上,计算零偏压下的隧穿电导、自旋极化率和隧穿磁阻比率,分析势垒层特性、分子场强弱、分子场相对取向等对隧道结自旋极化电子隧穿特性的影响.计算结果对自旋电子器件的设计具有一定的指导意义.     

The optical near-field speckles and their first order statistics on the basis of the integral equations of electromagnetic field

Speckle fields are the random light wave distributions produced when the light fields are scattered from random surfaces or a random medium. They appear in many optical phenomena that are related to light propagations[1,2] and have found wide appli-cations in a variety of scientific and technical fields. The examples of the recent impor-tant applications of speckles include the analysis of the movement of the granules[3], the three-dimensional imaging for the microstructures of metal nanocryst…     

Suppression of friction-induced-vibration in MDoF systems using tangential harmonic excitation

Meccanica - This paper investigates the effects of tangential harmonic excitation on the friction-induced-vibration in multi-degree-of-freedom systems that are coupled in the tangential and normal...     

Friction-induced vibration of a slider on an elastic disc spinning at variable speeds

Nonlinear Dynamics - The friction-induced vibration of a mass–slider with in-plane and transverse springs and dampers in sliding contact with a spinning elastic disc in three different...     

Lithium-ion-conductive polyethylene oxide based polymer electrolytes containing tris(pentafluorophyenyl)borane

For enhancement of lithium-ion transference number, lithium-ion-conductive polymer electrolytes have been prepared from polyethylene oxide (PEO), lithium salt of LiCF₃SO₃ or LiF, plasticizer of polyethylene glycol dimethylether (PEGDME), and anion receptor of tris(pentafluorophenyl)borane (TPFB). Transport properties of the resultant polymer electrolytes have been studied by AC impedance spectroscopy. As a result, lithium-ion transference number increased with increasing TPFB due to the restriction of anion conduction by the interaction between anion and anion receptor. Effects of anion receptor on transport properties are discussed.     

The gated integration technique for the accurate measurement of the autocorrelation function of speckle intensities scattered from random phase screens

A new approach based on the gated integration technique is proposed for the accurate measurement of the autocorrelation function of speckle intensities scattered from a random phase screen. The Boxcar used for this technique in the acquisition of the speckle intensity data integrates the photoelectric signal during its sampling gate open, and it repeats the sampling by a preset number, m. The average analog of the m samplings output by the Boxcar enhances the signal-to-noise ratio by , because the repeated sampling and the average make the useful speckle signals stable, while the randomly varied photoelectric noise is suppressed by . In the experiment, we use an analog-to-digital converter module to synchronize all the actions such as the stepped movement of the phase screen, the repeated sampling, the readout of the averaged output of the Boxcar, etc. The experimental results show that speckle signals are better recovered from contaminated signals, and the autocorrelation function with the secondary maximum is obtained, indicating that the accuracy of the measurement of the autocorrelation function is greatly improved by the gated integration technique.     

Facile fabrication of mesoporous manganese oxides as advanced electrode materials for supercapacitors

Mesoporous manganese oxides (MnO₂) were synthesized via a facile chemical deposition strategy. Three kinds of basic precipitants including sodium carbonate (Na₂CO₃), sodium bicarbonate (NaHCO₃), and sodium hydroxide (NaOH) were employed to adjust the microstructures and surface morphologies of MnO₂ materials. The obtained MnO₂ materials display different microstructures. Great differences are observed in their specific surface area and porosity properties. The microstructures and surface morphologies characteristics of MnO₂ materials largely determine their pseudocapacitive behavior for supercapacitors. The MnO₂ prepared with Na₂CO₃ precipitant exhibits the optimal microstructures and surface morphologies compared with the other two samples, contributing to their best electrochemical performances for supercapacitors when conducted either in the single electrode tests or in the capacitor measurements. The optimal MnO₂ electrode exhibits a high specific capacitance (173 F g^–1 at 0.25 A g^?1), high-rate capability (123 F g^?1 at 4 A g^?1), and excellent cyclic stability (no capacitance loss after 5,000 cycles at 1 A g^?1). The optimal activated carbon//MnO₂ hybrid capacitor exhibits a wide working voltage (1.8 V), high-power and high-energy densities (1,734 W kg^?1 and 20.9 Wh kg^?1), and excellent cycling behavior (93.8 % capacitance retention after 10,000 cycles at 1 A g^?1), indicating the promising applications of the easily fabricated mesoporous MnO₂ for supercapacitors.