The structure change of dynamically fatigued unfilled natural rubber vulcanizates

The submicrostructure of dynamically fatigued unfilled natural rubber vulcanizates was investigated by using scanning electron microscope (SEM) and atomic force microscope (AFM). AFM photographs showed the sample surface roughness became worse after tensile fatigue and the largest surface undulation was as twice that of the unfatigued sample. SEM photographs showed that many micropores of 10¹–10² nm, a sort of defect, occurred on the cross section of samples after tensile fatigue. The surface roughness became weaker and the size of the micropore was reduced to a few to dozens of nanometers with the addition of antiaging agent N‐(1,3‐dimethyl butyl butyl)‐N′‐phenyl‐p‐phenylene diamine (4020); furthermore, the mechanical properties and dynamic viscoelastic properties in the later period of fatigue changed much. E′ decreased greatly and tan δ increased obviously with the extension of fatigue. It indicated that 4020 was only effective in the early period of tensile fatigue.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

New Binuclear Complexes with Mixed Ligands and μ<Subscript>2</Subscript>-Phenol Oxygen Bridges: Synthesis Crystal Structures and Magnetism

Two new complexes, [M₂(L)₂(bpy)₂](ClO₄)₂ [L = methyl salicylate, bpy = 2,2′-bipyridine, M = Cu (1) and Zn (2)] have been synthesized and structurally characterized by X-ray structure analyses. The centrosymmetric dimeric structure consists of a binuclear unit, in which M (M = Cu or Zn) atoms are bridged by two phenol oxygen atoms as a μ ₂-bridged. The neighboring binuclear units interact with each other by two kinds of weak contacts: one kind is π–π stacking by π–σ attraction with an edge-to-face C–H···π interaction, and the second type is a H-bonding interaction, which extends the binuclear unit into a 3D network. Magnetic measurements confirm that 1 presents a very strong intradinuclear ferromagnetic coupling between the copper(II) ions.     

Molecular motion and detrapping behavior of trapped space charges in polyvinyl pyrrolidone: a thermally stimulated depolarization current study

The discharging process of polyvinyl pyrrolidone electret under two different heating rates 3.5 and 2 °C/min has been investigated by the measurement of thermally stimulated depolarization current (TSDC) in the temperature range from 30 to 250 °C. The TSDC spectra of PVP shows three peaks located at 70 ± 10, 150 ± 10, and 230 ± 10 °C, respectively. When explaining the TSDC spectra, this thesis deduced that the first peak, β peak, originates from side group relaxation; the second peak, α peak, corresponds to the relaxation of the frozen dipoles on the molecule chain segments during glass transition; the third peak, ρ peak, is attributed to the detrapping of the trapped space charge under thermal stimulation. The current of the ρ peak is remarkably strong due to the fact that PVP molecules’ side groups—the pyrrolidone rings containing lactam structure—are strong polar groups which cause the great increase in the number of bulk traps, trapped space charge, as well as detrapped space charge under thermal stimulation.     

Hydrothermal synthesis of nitrogen-doped graphene as lightweight and high-efficient electromagnetic wave absorbers

Journal of Materials Science: Materials in Electronics - Exploring lightweight electromagnetic wave absorption materials is urgently needed to satisfy the miniaturization and integration of...     

Design, modeling, and hardware correlation of a 3.2Gb/s/pair memory channel

With the rapid advance of silicon process technology, it is now possible to design input/output (I/O) circuits that operate at multigigabit data rates. As a result, accurate modeling and analysis of high-speed interconnect systems is essential to optimize the performance of the overall system. This paper describes the interconnect design, modeling, simulation, and characterization methodologies that are essential to achieve multigigabit data rates. It focuses on the physical layer verification and hardware correlation of functional systems and silicon to ensure robust system operation over 3.2Gb/s data rate using conventional low-cost packaging and printed circuit board (PCB) technologies. In order to capture conductor and dielectric losses, as well as other high-frequency effects of three-dimensional structures, accurate measurement-based simulation techniques that directly incorporate frequency-domain parameters from measurement or electromagnetic solver parameters into circuit simulation tools using fast Fourier transform (FFT) and bandlimiting windowing techniques are developed. Finally, simulation waveforms are correlated with prototypes at both component and system levels in both time and frequency domains.     

脉冲雷达杂波模拟器

简要介绍了针对脉冲雷达体制的一种杂波模拟器设计方法，该方法采用波形存储和重放技术，具有一定的实用意义。     

LTE终端语音解决方案现状及下一步演进

LTE时代终极终端语音解决方案VoLTE是目前业界研究的重点.对现有LTE终端的多种语音解决方案进行了详细的技术分析和比较,重点从终端角度探讨了承载在纯分组交换系统和IMS的VoLTE的技术优势和待解决问题,呈现了VoLTE技术作为LTE终端语音解决方案的技术特点和下一步演进趋势.     

用改进的AHP法及模糊综合评判理论优选过水围堰堰型

本文在考虑影响水围堰堰型选择的主要因素的基础上，应用改进的ＡＨＰ法及模糊综合评判原理，为水利电力工程的施工导流设计，提供了一个合理选择过水围堰堰型的综合评判决策方法。