超高频锁相调频设计研究

本文从减小剩余调频出发,对两种锁相调频方案进行了深入的比较研究.文中还讨论了环路设计方法、实践经验和测试结果.     

关于同余交换的带

每一个元素都是幂等元的半群称为带。本文证明,若S是带且S的任意两个同佘可交换,则|S|≤13。     

超低硫钢生产工艺的实践

在济钢生产X80、X100管线钢为平台的超低硫钢的工艺基础上,对LF深脱硫控制技术进行了分析研究,结果表明LF深脱硫主要取决于精炼渣系配比、钢包底吹氩工艺、钢水温度和钢水中[Als]含量。通过工艺调整,使生产X80、X100管线钢时LF炉终点w[S]可稳定控制在15ppm以内,平均控制在10ppm。     

Enhancement of the thermo-mechanical properties and efficacy of mixing technique in the preparation of graphene/PVC nanocomposites compared to carbon nanotubes/PVC

Thin films of poly vinyl chloride(PVC)/multiwalled carbon nanotubes(MWCNT) and PVC/graphene(GN) nanocomposites were prepared by mixing in the presence of different quantities of nanoparticles. Film casting was performed using tetrahydrofuran as a solvent. The as-prepared PVC/MWCNT and PVC/GN nanocomposites were characterized by scanning electron microscopy, Raman spectroscopy, X-ray diffraction,thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and diffused reflectance spectroscopy. Only the PVC/GN nanocomposite films were evaluated further for detailed mechanical analysis because of the poor dispersion of MWCNTs in PVC. The PVC/GN nanocomposite films were thermo-mechanically more stable than the PVC films. These nanocomposites have potential as a replacement material for PVC and PVC/MWCNT owing to their better dispersion and high stability.     

Effects of spectral sampling rate and range of CO2 absorption bands on XCO2 retrieval from TanSat hyperspectral spectrometer

The spectral sampling rate and range of CO2 absorption bands are critical for the optimal design of hyperspectral instrument for CO2 observation satellite. Undersampling of spectra in space-based spectrometer significantly contaminates signals measured in the CO2 1.61 ktm-band. The CO2 dry-air column （XCO2） error due to spectral undersampling can be up to ,1 ppm, which is the target precision of the Chinese Carbon Satellite （TanSat） for a single sounding. Undersampling error depends on surface albedo, solar zenith angle, and scattering properties in the atmosphere. The spectral sampling rate is recommended to be greater than 2.0 pixels per full width at half maximum to avoid undersampling. Reduction of spectral resolution and the use of narrower spectral regions can improve spectral sampling with little changes in CO2 retrieval sensitivity without losing much information. The full-band approach provides direct constraints on the wavelength-dependent surface albedo and particle scattering from the measurements. To keep a broader band, we recommend reduction of the spectral resolution by a factor of two.     

论英言小说中隐含作者的构建——《丰乳肥臀》的解读

美国小说理论家布斯认为,小说隐含作者的建构在很大程度上依靠读者对作品的理解,而作品的叙述角度是理解作品的重要环节。唯有把握了叙述角度,读者才有可能对隐含作者的意图、立场、观点、态度甚至价值观进行正确的推断。通过小说《丰乳肥臀》的叙述角度,论证其在建构小说的隐含作者过程中所起到的关键作用。     

EoC在县级HFC网络建设下一代广播电视(NGB)综合业务承载网的应用

本文介绍对广电网双向改造的认识,通过实际工作和对业务技术的学习,提出了几点问题,并对广电网络EPON系统进行了探讨。     

R-C干式过电压吸收器在高压真空断路器中的应用

探讨了 R- C干式过电压吸收器在限制真空开关操作过电压中应用的可行性 ,简介了 R- C干式过电压吸收器的工作原理、主要参数并举例计算