辐射干扰下通信接收系统的阻塞性能研究

本文主要在通信接收系统抗阻塞干扰性能方面做分析研究。根据阻塞干扰的原理,分析系统线性度指标,通过建立通信接收系统行为级仿真模型实现阻塞干扰对通信系统的影响,并提出了若干避免和解决阻塞干扰的方法措施。该研究对辐射干扰下通信接收系统的设计和性能分析具有很好的理论指导意义。     

土壤中砷的污染控制技术研究

土壤砷污染修复是世界性的难题,日益受到人们的密切关注。本文阐述了土壤砷污染的现状、危害及其来源,探讨土壤砷污染的传统物理化学和生物修复技术的研究现状及特点的同时,重点阐述了纳米材料修复技术,尤其是纳米铁技术,并对土壤砷污染修复研究方向进行了展望。     

改性纳米铁/炭填充PRB去除地下水硝态氮研究

采用鼠李糖脂对纳米铁进行改性后负载在活性炭上制备出改性纳米铁/炭,将其作为PRB填充材料,并采用有机玻璃柱模拟连续墙式PRB来进行水中硝态氮地去除研究.结果表明：经过改性后的纳米铁能够有效负载在活性炭上,悬浮稳定性得到明显提高;改性纳米铁/炭粒径远大于纳米铁,将其作为填充材料可有效缓解PRB堵塞问题;当纳米铁与活性炭质量比为5：2时,PRB运行效果最佳;pH值越小,污染液硝态氮浓度越低,水流速度越小均有利于硝态氮地去除.     

基于有限元分析的X80高钢级管道剩余强度计算公式构建

为了更加精确地计算X80高钢级管道剩余强度,以有限元分析理论基础为依据,采用ANSYS WORKBENCH软件对含腐蚀缺陷的X80高钢级管道进行仿真模拟。基于X80高钢级管道有限元模型计算结果,选用1stOpt软件,用拟合的方法构建出以腐蚀缺陷长度、腐蚀缺陷深度、管径、壁厚等因素为变量的X80高钢级管道剩余强度计算公式,将拟合公式与PCORRC,DNV RP-F101和LPC-1等3种评价方法的准确性进行对比、验证和分析。结果表明:拟合公式的误差较小,具有较好的适用性。研究结果对改进现有评价方法具有参考作用。     

四川省地震灾情快速上报接收处理系统

地震灾情信息的快速获取是地震应急救援工作的关键。介绍了四川省地震灾情快速上报接收处理系统的建设目标、总体架构和系统建设内容。在2013年芦山7.0级强烈地震实战考验中,四川省地震灾情快速上报接收处理系统发挥了重要作用,有效缩短了灾情"黑箱期"。     

纳米颗粒尺寸定义可能不适用于评估其环境影响

<正>2014年4月17日来源:《环境科学与技术》常常用于定义纳米颗粒的100nm粒度上限可能"不合适"用于评估环境影响,由美国和中国科学家组成的一个研究小组表示。这些科学家在《环境科学与技术》学报上发表的一篇观点文章中写道,100nm的基准"未反映与纳米颗粒的生态学相互作用的复杂性"。有研究报告,超过阙值粒度的纳米颗粒具有不同的物理化学性质。这些发现显示,可能存在产生环境影响的     

Enhanced adsorption of phosphate by loading nanosized ferric oxyhydroxide on anion resin

Ferric oxyhydroxide loaded anion exchanger （FOAE） hybrid adsorbent was prepared by loading nanosized ferric oxyhydroxide （FO） on anion exchanger resin for the removal of phosphate from wastewater. TEM and XRD analysis confirmed the existence of FO on FOAE. After FO loading, the adsorption capacity of the hybrid adsorbent increased from 38.70 to 51.52mg.g-1. Adsorption processes for both FOAE and anion resin were better fit to the pseudo first order model. Batch adsorption experiments revealed that higher temperature （313K）, higher initial phosphate concentration （50 mg.L-1） and lower solution pH （pH value of 2） would be more propitious to phosphate adsorption. Competition effect of coexisting anions on phosphate removal can be concluded as sulfate 〉 nitrate 〉 chloride. Freundlich isotherm model can describe the adsorption of phosphate on FOAE more accurately, which indicated the heterogeneous adsorption occurred on the inner-surface of FOAE.     

Cation exchange resin supported nanoscale zero-valent iron for removal of phosphorus in rainwater runoff

Self-made cation exchange resin supported nanoscale zero-valent iron （R-nZVI） was used to remove phosphorus in rainwater runoff. 80% of phosphorus in rainwater runoff from grassland was removed with an initial concentration of 0.72 mg. L-1 phosphorus when the dosage of R-nZVl is 8 g per liter rainwater, while only 26% of phosphorus was removed when using cation exchange resin without supported nanoscale zero-valent iron under the same condition. The adsorption capacity of R-nZVI increased up to 185 times of that of the cation exchange resin at a saturated equilibrium phosphorous concentration of 0.42 mg. L-1. Various techniques were implemented to characterize the R-nZVI and explore the mechanism of its removal of phosphate. Scanning electron microscopy （SEM） indicated that new crystal had been formed on the surface of R-nZVI. The result from inductive coupled plasma （ICP） indicated that 2.1% of nZVI was loaded on the support material. The specific surface area was increased after the load of nanoscale zero-valent iron （nZVI）, according to the measurement of BET-N2 method. The result of specific surface area analysis also proved that phosphorus was removed mainly through chemical adsorption process. X-ray photoelectron spectroscopy （XPS） analysis showed that the new product obtained from chemical reaction between phosphate and iron was ferrous phosphate.     

Benzene removal by nano magnetic particles under continuous condition from aqueous solutions

Benzene removal evaluated using Fe304 nano continuous condition. A 44 initial benzene concentration, from aqueous solutions was magnetic particles （NM） in factorial design including NM dose, contact time and pH was investigated in 16 experiments （Taguchi OA design）. The results indicated that all factors were significant and the optimum condition was： pH 8, NM dose of 2000 mg.L-1, benzene concentrations of 100 mg.L-1 and contact time of 14min. The maximum benzene uptake and distribution ratio in the optimum situation were 49.4mg.g-1 and 38.4L.g-1, respectively. The nano particles were shown to capture 98.7% of the benzene in optimum batch condition and 94.5% in continuous condition. The isotherm data proved that the Bmnauer-Emmett-Teller model fit more closely and produced an isotherm constant （b） less than one, indicating favorable adsorption. Regeneration studies verified that the benzene adsorbed by the NM could be easily desorbed by temperature, and thereby, NM can be employed repeatedly in water and wastewater management.     

Novel synthetic approaches and TWC catalytic performance of flower-like Pt/CeO2

A novel Ultrasonic Assisted Membrane Reduction （UAMR）-hydrothermal method was used to prepare flower-like Pt/CeO2 catalysts. The texture, physical/chemical properties, and reducibility of the flower-like Pt/CeO2 catalysts were characterized by X-Ray Diffraction （XRD）, Scanning Electron Microscope （SEM）, Transmission Electron Microscope （TEM）, N2 adsorption, and hydrogen temperature programmed reduction （HE-TPR） techniques. The catalytic performance of the catalysts for treating automobile emission was studied relative to samples prepared by the conventional wetness impregnation method. The Pt/CeO2 catalysts fabricated by this novel method showed high specific surface area and metal dispersion, excellent three-way catalytic activity, and good thermal stability. The strong interaction between the Pt nanoparticles and CeO2 improved the thermal stability. The Ce4＋ ions were incorporated into the surfactant chains and the Pt nanoparticles were stabilized through an exchange reaction of the surface hydroxyl groups. The SEM results demonstrated that the Pt/CeO2 catalysts had a typical three-dimensional （3D） hierarchical porous struc- ture, which was favorable for surface reaction and enhanced the exposure degree of the Pt nanoparticles. In brief, the flower-like Pt/CeO2 catalysts prepared by UAMR-hydrothermal method exhibited a higher Pt metal dispersion, smaller particle size, better three-way catalytic activity, and improved thermal stability versus conven- tional materials.