基于接收信号强度的非视距检测与修正算法

为了减少非视距（NLOS）误差对基于到达时间（TOA）的无线定位系统性能的影响,本文提出一种采用接收信号强度（RSS）与TOA测量值相结合的方法对含有NLOS误差的TOA测量值进行检测并修正。在视距（LOS）传播的TOA与RSS之间关系已知的前提下,利用定位基站得到的TOA与RSS测量值,计算TOA测量值中含有NLOS误差的可能性,并利用该可能性对TOA测量值进行修正。该方法在不增加通信次数的情况下,大大提高了定位精度。本文最后在一个无线定位系统上实现了该算法,并进行了对比实验。实验结果表明,该算法不需对多次定位结果进行统计,即可有效降低NLOS误差对系统性能的影响,适用于对功耗要求苛刻的场合。     

用除尘灰分离炭粉制备活性炭及其改性研究

以除尘灰分离炭粉为原料，确定了制备颗粒活性炭的最佳工艺，并对制备的颗粒活性炭进行不同的改性处理和对不同有机蒸气的吸附实验。利用X—光电子能谱仪分析了改性处理后的表面化学性质。吸附实验证明，活性炭的比表面积、表面化学性质和有机物的性质对吸附过程产生影响。     

Viscoelastic, Thermal and Mechanical Properties of Dicyclopentadiene Bisphenol Diyanate Ester / Epoxy Co-polymers

Summary Dicyanate ester containing dicyclopentadiene cycles and epoxy co-polymers were prepared by copolymerization between epoxy and dicyclopentadiene bisphenol cyanate esters (DCPDCE). Viscoelastic properties of the co-polymers were characterized by the technique of dynamic mechanical analysis (DMA), which indicated that the introduction of E51 in the co-polymers would effectively improve the toughness of DCPDCE, while the thermal dimensional stability would be weakened. Results from thermogravimetric analysis (TGA) are in good accordance with the T_g values from DMA curves. Mechanical testing of the cured co-polymers shows that E51 can improve the mechanical properties of the co-polymers while its usage is controlled among 5% to 15%.     

The influence of F doping on the activity of PbO2 film electrodes in oxygen evolution reaction

The PbO₂ and F⁻-doped PbO₂ (F-PbO₂) film electrodes have been prepared by an electrodeposition process onto platinum substrate. The changes of their electrochemical activity for oxygen evolution (OE) reaction with accelerated electrolysis time have been studied. The results show that the activity of the electrodes decreases with increasing electrolysis time. This can be attributed to the conductivity variations, which are caused by the decrease of the oxygen vacancy concentration in PbO₂ films during OE. The mechanism of the decrease of the oxygen vacancies has been investigated. For F-PbO₂ film electrodes, though its electrochemical activity is somewhat lower than that of undoped one, its activity stability is much higher in comparison with that of PbO₂. The influence of F⁻ doping on the activity of PbO₂ film electrodes has been also discussed.     

改性胶粉/SBR共混胶料的结构性能研究

研究了硫黄、促进剂、改性胶粉用量对胶粉／ＳＢＲ共混胶料性能的影响。结果表明；改性胶粉用量在１０－３５份的范围内．对共混胶料的静态力学性能影响不大：在１０－２２份的范围内对动态压缩疲劳生热影响不大．适当调整基质胶中硫黄、促进剂的用量．有利于降低胶料的动态压缩疲劳生热。扫描电子能谱微区分析的研究表明：由于硫黄的迁移形成了具有特殊结构的界面过渡层．该过渡层是降低动态压缩疲劳生热的关键。     

水体中苯胺类化合物测定方法的改进

本文分别利用活性炭吸附、三氯甲烷萃取和前两种方法联用对显色剂 N-(1 -萘基 )乙二胺进行了提纯 ,从而使水体中苯胺类化合物测定方法的显色时间由 1 2 0 min(未提纯法 )缩短至 90 min(经三种方法提纯 ) ,显色剂溶液的稳定性有了明显的提高 ,测定方法的精密度得到了显著的改善 ,同时检出限也由 0 .3 0 mg/L (未提纯法 )分别降至 0 .0 48mg/L (活性炭吸附提纯法 )、0 .0 59mg/L(三氯甲烷萃取提纯法 )和 0 .0 3 1 mg/L(两种方法联用提纯法 ) ,用经三种方法提纯后的显色剂溶液测定水样中的苯胺 ,测定结果均令人满意     

Rapid pyrolysis of brown coal and oil shale

A brown coal, peat and oil shale were subjected to a rapid pyrolysis process and medium-heat-value gases together with tar were collected. The char residue was of high activity and suitable for gasification to create a two-stage gasification system. The coal-tar is used for manufacturing liquid fuels and chemicals.     

Integrated UV-based photo microreactor-distillation technology toward process intensification of continuous ultra-high-purity electronic-grade silicon tetrachloride manufacture

Ultra-high-purity silicon tetrachloride (SiCl₄) is demanded as an electronic-grade chemical to meet the stringent requirements of the rapidly developing semiconductor industry. The high requirement for ultra-high-purity SiCl₄ has created the need for a high-efficient process for reducing energy consumption as well as satisfying product quality. In this paper, a mass of production technology of ultra-high-purity SiCl₄ was successfully developed through chlorination reaction in the ultraviolet (UV)-based photo microreactor coupled with the distillation process. The influences of key operational parameters, including temperature, pressure, UV wavelength and light intensity on the product quality, especially for hydrogen-containing impurities, were quantified by the infrared transmittance of Fourier transform infrared spectroscopy (FT-IR) at 2185 cm^-1 and 2160 cm^-1 indicating that characteristic vibrational modes of Si—H bonds, as well as the operating conditions of distillation were also investigated as key factors for metal impurities removing. The advanced intensification of SiCl₄ manufactured by the integration of photo microreactor and distillation achieves the products with superior specifications higher than the standard commercial products.     

CAE软件操作小百科（23）

正1 RecurDyn如何在仿真之前检查模型的各种设置是否正确?在动力学分析之前,若要检验样机,可以先进行运动学分析,且在施加作用力之前确定各种约束是否正确.在RecurDyn中,还提供模型预分析功能,在simulation type中有预分析功能(pre analysis),检查模型自由度、是否有冗余约束及其相关信息.2 RecurDyn怎样解决有冗余约束的问题?当模型存在冗余约束时,软件在求解过程中会     

Preparation and catalytic performance of Co3O4 catalysts for low-temperature CO oxidation

Without use of any surfactant or oxidant, a series of Co₃O₄ catalysts have been prepared from cobalt nitrate aqueous solution via a very simple liquid-precipitation method with ammonium acid carbonate followed by calcination at various temperatures. The catalytic performance of the Co₃O₄ for CO oxidation has been studied with a continuous flowing laboratory microreactor system. The results show that the CO conversion of all the samples can reach 100% at ambient temperature. The catalyst calcined at 300 °C is able to maintain its activity for CO complete oxidation more than 500 min at 25 °C and about 240 min even at −78 °C. High reaction temperature results in a high catalytic stability, while the catalytic stability decreases with further increasing the reaction temperature. Characterizations with X-ray powder diffraction and transmission electron microscopy suggest that all the samples exist as a pure Co₃O₄ phase with the spinel structure, the samples are apt to aggregate and the specific surface area gradually decreases with increasing the calcination temperature, which directly leads to the decrease of catalytic stability. Furthermore, the amount of active oxygen species measured by CO titration experiments appears to be critical for catalytic performance.