Hydrogen impurities in oxides and halides

The effect of H-impurity on the properties of vitreous SiO₂ is presented. Thermogravimetric analyses of the volatility of pure ZrF₄ using two different carriers, N₂ and CO, show that outgas H₂O should be taken into account. Consequently, it is shown that the intrinsic hydrolyzed state of pure ZrF₄ is significant. It is proposed that the stronger hydrogen bonded fluoride glasses will have generally a higher content of H-impurity than the oxide (SiO₂) counterpart.     

真空热处理、可控气氛热处理在钢丝生产中的应用

真空热处理有４大作用，使处理的钢丝具有光亮的表面；多种的可控气氛热处理可保护钢丝，防止钢丝表面发生化学反应。合理选用热处理方式将确保产品的高质量。     

An evaluation of satellite aerosol products against sunphotometer measurements

Because atmospheric aerosols scatter sunlight back to space, reflectance measurements from spaceborne radiometers can be used to estimate the aerosol load and its optical properties. Several aerosol products have been generated in a systematic way, and are available for further studies. In this paper, we evaluate the accuracy of such aerosol products derived from the measurements of POLDER, MODIS, MERIS, SEVIRI and CALIOP, through a statistical comparison with Aerosol Optical Depth (AOD) measurements from the AERONET sunphotometer network. Although this method is commonly used, this study is, to our knowledge, among the most extensive of its type since it compares the performance of the products from 5 different sensors using up to five years of data for each of them at global scale. The choice of these satellite aerosol datasets was based on their availability at the ICARE Data and Service Centre (www.icare.univ-lille1.fr).We distinguish between retrievals over land and ocean and between estimates of total and fine mode AOD. Over the oceans, POLDER and MODIS retrievals are of similar quality, with RMS difference lower than 0.1 and a correlation with AERONET of around 0.9. The POLDER estimates suffer from a small positive bias for clean atmospheres, which weakens its statistics. The other aerosol products are of lesser quality, although the SEVIRI products may be of interest for some applications that require a high temporal resolution. The MERIS product shows a very high bias. Over land, only the MODIS product offers a reliable estimate of the total AOD. On the other hand, the polarization-based retrieval using POLDER data allows a better fine mode estimate than that from MODIS. These results suggest the need for a product combining POLDER and MODIS products over land.The paper also analyses how the statistics change with the spatial and temporal thresholds that are used. Spatio-temporal averaging improves the statistics only slightly, which indicates that random errors are not dominant in the error budget. The paper includes various statistical indicators at global scale, and detailed results at individual ground stations can be obtained on request from the authors.     

自适应编码调制技术在大气激光通信中的应用研究

在大气激光通信中,采用固定编码调制方式的传输方案不能充分利用信道的时变特性,频带利用率较低。将自适应编码调制技术应用于大气激光通信中,针对当前的信道状态,选取合适的MCS,使系统的整体传输性能达到最优,满足高效可靠传输的目的。详细阐述了不同目标误包率下的信噪比门限值计算方法,仿真给出4种MCS下的自适应设计方案。结果表明:AMC技术可以在保证系统可靠传输的同时提高系统的频谱利用率;且随着目标误包率的降低,系统的平均频谱利用率降低。     

浪漫与理性交融的岭南书院——华南师范大学南海学院的规划与建筑创作

在华南师范大学南海学院的规划与建筑设计中,我们抓住大学校园空间环境的本质和地域特色,将自由浪漫的自然环境和整体理性的教育理念相结合,体现人与自然和谐共处、融于山水的特色,营造一个适应现代教育要求和充满岭南书院气息的大学校园.     

Impacts of Water Table Management on N<Subscript>2</Subscript>O and N<Subscript>2</Subscript> from a Sandy Loam Soil in Southwestern Quebec,Canada

Nitrous oxide (N₂O) is primarily produced as intermediate in denitrification and, to a lesser extent, through nitrification processes. Nitrous oxide emission and, consequently, its atmospheric impacts depend on the extent to which N₂O is reduced to dinitrogen gas (N₂) by denitrifiers. Field experiments were conducted from 1998 through 2000 growing seasons at St. Emmanuel, Quebec, Canada, to investigate the combined impact of water table management (WTM) and N fertilization rate on the soil denitrification (N₂O + N₂) rate, rate of N₂O production, and the N₂O:N₂O + N₂ ratio. Water table treatments included subirrigation (SI) with a target water table depth of 0.6 m and free drainage (FD) with open drains. The tile drains (75 mm diameter) were laid at a 1.0 m depth from the soil surface. Nitrogen fertilizer was applied at two rates:120 and 200 kg N ha⁻¹ as ammonium nitrate (34-0-0). The N₂O + N₂ evolution rates were greater in SI (12.9 kg N ha⁻¹) than in FD (5.8 kg N ha⁻¹) plots. The percentages of N₂O relative to overall N₂O + N₂ evolution were 35 and 11% for 1998, 29 and 8% for 1999, and 37 and 20% for 2000, under FD and SI, respectively. The reduced N₂O production under SI was due to a greater reduction of N₂O to N₂. Results indicate that greater N₂O + N₂ evolution under shallow water tables are not necessarily accompanied by higher N₂O emissions.     

关于建设优秀企业团队的实践与思考

当前,市场竞争日趋激烈,加强团队建设,造就一支有着共同奋斗目标、具备过硬业务素养、具有较强凝聚力的优秀团队,已成为现代企业管理的一项重要内容.近年来,中国石化江汉油田分公司江汉采油厂(以下简称江汉采油厂)在团队建设上做了积极的探索性工作,打造了一支素质优良、业务熟练、能征善战的江采团队,提升了夺油创效的实力和企业的经营管理水平,推动了企业又好又快发展.     

等离子喷涂 Cr2O3-TiO2/YSZ 高效热防护涂层 微观结构及性能研究

本文以 Cr2O3、TiO2 和 NiO 为原材料,通过喷雾造粒和烧结获得了由尖晶石结构 NiCr2O4 和钙钛矿结构TiCrO3 组成的 Cr2O3-TiO2 复合粉末。采用大气等离子喷涂技术在镍基高温合金表面制备 Cr2O3-TiO2/nano-YSZ 复合涂层,分析测试了复合涂层的微观结构、抗拉结合强度、抗烧蚀性能和高温热辐射性能。结果表明,Cr2O3-TiO2/nano-YSZ 复合涂层孔隙率较低,抗拉结合强度达到 29.2 MPa;经 1.5 MW/m2、600 s 氧乙炔火焰烧蚀后,Cr2O3-TiO2/nano-YSZ 复合涂层表面有轻微点状剥落,涂层内部结构完整,未发生失效。在烧蚀过程中,Cr2O3-TiO2/nano-YSZ 复合涂层隔热能力达到 426 ℃,比单一纳米 YSZ 涂层隔温能力高 146 ℃,基体温度比纳米 YSZ涂层低 335 ℃;Cr2O3-TiO2/nano-YSZ 复合涂层在 400 ℃和 750 ℃在 2~15 μm 波段内的法向发射率分别为 0.91 和0.89。     

低氢气氛在不锈钢带光亮退火中的应用

所指低Ｈ２，是２５％Ｈ２和７５％Ｎ２的混合气，由氨分解气和工业Ｎ２以１：２混合后经净化制得。用以替代氨分解气，作不锈带钢连 续光亮退火的保护气氛。在现有生产设备条件下，低Ｈ２气氛可以适用于不锈钢带的连续光亮退火。     

智能模糊测量系统在监测大气质量中的应用

综合考虑影响大气环境质量的有毒气体、温湿度以及其它相关状态参量，采用多信息融合技术解决了各影响因子间的冗余性。在此基础上，构造了智能模糊神经网络检测系统，应用于检测大气质量。实验仿真结果表明该方法行之有效。