All‐carbon hybrids for high performance supercapacitors

A hybrid nanostructure with partially reduced graphene oxide (rGO) and carbon nanofibers (CNFs) was fabricated and used as supercapacitor electrodes. A straightforward, environmentally friendly, and low‐cost microwave‐assisted reduction process was developed for the synthesis of rGO/CNF hybrid structures. The fabricated supercapacitor devices showed a specific capacitance of 95.3 F g^?1 and a superior long‐term cycling stability. A capacitance retention of more than 97% after 11 000 galvanostatic charge discharge cycles was obtained. These and other results reported in this paper indicate that high‐rate, all‐carbon, rGO/CNF hybrid nanostructures are highly promising supercapacitor electrode materials.     

Engineering MIL-88B crystallites for enhanced H2 uptake capacity: The role of ultramicropores

In this study, a strategy that optimizes the pore size to enhance the adsorbed H₂ amount (at 298 K) is investigated. Pore size and ultramicropore fraction (ultramicropore volume/total pore volume) were controlled by Fe:TPA ratio. The highest H₂ adsorption capacity of 0.47 wt% (298 K and 7.6 bar) belongs to MIL-88B-3, which is higher than those of reported metal-organic frameworks (MOFs) (MIL-100, MIL-101 [Cr], HKUST-1, MOF-5, and ZIF-8). The enhanced H₂ sorption capacity (1.96 times) is a consequence of the high fraction (89%) and volume (0.22 cm³/g) of ultramicropores with pore diameters of 0.6 nm. Our results demonstrate that pore size, fraction, and volume of ultramicropores control the amount of H₂ adsorbed also at 298 K. With the use of perturbation assisted nanofusion synthesis strategy that introduces textural pores to the pore structure, a Brunauer-Emmett-Teller (BET) surface area higher than those of reported MIL-88Bs has been achieved, and a strategy to synthesize MOFs with enhanced H₂ sorption capacities is suggested.     

正交各向异性叠层板的非线性主共振分析

研究了在四边简支的边界条件下,正交各向异性矩形叠层板在横向简谐激励作用下的非线性主共振及其稳定性问题．在给出了正交各向异性叠层板的振动微分方程的基础上,利用伽辽金法导出了相应的达芬型非线性强迫振动方程．应用平均法对主共振问题进行求解,得到了系统在稳态运动下的幅频响应方程．基于李雅普诺夫稳定性理论,得到了解的稳定性判定条件．作为算例,分别给出了不同条件下,系统运动的幅频响应曲线图、振幅-激励幅值响应曲线图和动相平面图,并对解的稳定性进行了分析,讨论了各参数对系统非线性振动特性的影响．     

Depolymerization of Turkish lignites. 2. Effect of phenol concentration in a closed system

A lignite (C, 66.9 wt%) was depolymerized, using sulphuric acid as a catalyst, in a closed system in which the phenol/coal ratio was varied from 1.5 to 10. The products were separated by solvent extraction and silica gel chromatography. The i.r. and n.m.r. spectra, and the molecular weight of the products were measured. In the experiments with a phenol/coal ration of 10, complete depolymerization of the coal was seen provided the temperature of depolymerization was at least 210 °C. The products generally contained disubstituted aromatic structures connected by methylene bridges, it was found that as the phenol/coal ratio was increased there was a decrease in the number of methylene bridges connecting the aromatic structures. The molecular weights of the straight-chain pentane and benzene-soluble material were lower than the molecular weights of similar fractions in depolymerization experiments carried out in open systems. A method for the structural analysis of straight-chain pentane and benzene-soluble material based on i.r., ¹H n.m.r. and molecular weight measurements is suggested.     

可再生能源EMS标准研究与制定

根据GB/T17626,IEC 61000-4以及UL1741-2005等国内外关于电子信息产品电磁抗干扰(EMS)的标准,分别研究了其关于静电放电试验、电快速瞬变脉冲群试验和雷击浪涌试验的原理、试验方法以及严酷度等级的要求,并据此提出了相应的可再生能源电能转换装置EMS标准.     

额外HCl和氮化对HVPE GaN生长的影响

在氢化物气相外延(HVPE)生长Ga N过程中,发现了一种在成核阶段向生长区添加额外HCl来改善Ga N外延薄膜质量的方法,并且讨论了额外HCl和氮化对Ga N形貌和质量的影响.两种方法都可以大幅度地改善Ga N的晶体质量和性质,但机理不同.氮化是通过在衬底表面形成Al N小岛,促进了衬底表面的成核和薄膜的融合;而添加额外HCl则被认为是通过改变生长表面的过饱和度引起快速成核从而促进薄膜的生长而改善晶体质量和性质的     

一种基于非下采样Contourlet变换的自适应阈值去噪方法

文章提出了一种基于非下采样Contourlet变换的自适应图像去噪方法。首先对噪声图像进行非下采样Contourlet变换,得到各个尺度各个方向子带的系数,再根据该系数的能量自适应地调整Bayes去噪阈值。实验结果表明：与小波阈值去噪方法对比,非下采样Contourlet自适应阈值去噪算法在保留图像边缘细节的同时,不仅能明显提高图像的SNR值,而且还减少了Gibbs现象。     

Nuclear magnetic resonance spectra of two reductively ethylated fuels

A lignite (67.2% C daf) and a coal (89.0% C daf) have been reductively ethylated by Sternberg's procedure⁴ and the spectra, in particular the ¹H and ¹³C n.m.r. spectra, of the products have been obtained. The distribution of hydrogen atoms and, in less detail, of carbon atoms in the reductively ethylated fuels has been determined. It is emphasized that both reductively ethylated fuels contained a variety of structures. The carbon aromaticities of the reductively ethylated lignite and the reductively ethylated coal were 0.41 ± 0.08 and 0.40 ? 0.54 respectively. The aromatic nuclei of the reductively ethylated coal were more highly substituted than those of the reductively ethylated lignite. The ¹H n.m.r. spectra indicate that the reductively ethylated coal and lignite possessed ≈3.5 and ≈2.5 substituents per benzene ring respectively. Resolved absorption in the ¹³C n.m.r. spectra suggests lower figures than these and it was evident that some of the benzene rings in both materials but especially in the reductively ethylated lignite were lightly substituted. The ¹³C n.m.r. spectra show that both materials contained branched and unbranched paraffin chains. Much of the ¹³C n.m.r. spectra however consisted of unresolved absorptions and the ¹³C n.m.r. measurements suggest that the reductively ethylated materials consisted of rigid, relatively immobile molecules of moderate molecular weight. ¹³C n.m.r. absorption by carbon atoms adjacent to aromatic rings was amongst that which was not resolved — though the rings themselves gave resolved absorptions — and this suggests that the aromatic rings were on the periphery of a rigid, perhaps alicyclic, structure.