杭州G20减排措施对大气水溶性离子特征的影响

利用2016年颗粒物及水溶性离子采样数据,研究了杭州G20峰会减排措施对大气中无机水溶性离子特征的影响.结果表明,杭州G20峰会减排措施对大气水溶性离子的质量浓度、组成结构、酸碱性等皆存在明显影响.减排措施实施使大气颗粒物和水溶性离子质量浓度下降,受影响的离子主要是NO₃^-、SO₄^2-、NH₄⁺、NO₂^-,其中NO₃^-、SO₄^2-质量浓度的下降使NH₄⁺、Ca²⁺、Cl^-成为浓度前3位的离子.SO₄^2-、NO₃^-、NH₄⁺、Ca²⁺粒径分布呈单峰型,其中SO₄^2-、NO₃^-、NH₄⁺峰值出现在0.65~1.10mm,Ca²⁺峰值出现在5.80~9.00mm,Na⁺、Cl^-、K⁺呈双峰分布,峰值皆出现在3.30~4.70mm和0.65~1.10mm,Na⁺两峰值相当,K⁺、Cl^-在0.65~1.10mm峰值较高.减排措施实施使大气中主要无机盐从NH₄NO₃、（NH₄）₂SO₄、NH₄Cl转变为NH₄Cl、NaCl、KCl,大气颗粒物碱性总体增强.本文研究成果对采取措施改善空气质量具有指导作用.     

基于TD-SCDMA移动视频监控系统的反向控制

提出了在TD-SCDMA环境下数字视频监控系统的一般应用模型.详述了在此基础上对无线视频监控过程中的反向控制的实现方案和流程,简要说明了实现代码及其后台配置管理,并通过结果论证了反向控制的可行性及未来的发展方向     

基于3G的无线VPDN业务网的设计与实现

介绍了基于3G的无线VPDN业务网组网方案,分析了其系统构成及隧道建立过程。在此基础之上,研究了基于3G的无线VPDN业务网在环保领域的应用,并对其网络架构和安全进行设计与实现。     

化工园区企业危险量计算模型研究

提出化工园区的危险量并探讨其含义。选择基础危险量计算模型及安全评估指标,建立化工园区企业基础危险量计算模型。通过对影响化工园区企业安全的因素进行筛选,建立企业危险量影响因素体系。在此基础上,运用改进G1法和模糊综合评价法确定各因素的权重和隶属度,对化工园区企业基础危险量模型进行改进,提出化工园区企业危险量和园区总体危险量的计算模型。实现了化工园区危险程度的量化,进而辅助化工园区的安全管理和安全规划。     

基于G_1法的飞行疲劳综合评价指标体系研究

为综合控制并评价飞行疲劳风险,通过对疲劳影响因素的深入分析,运用层次分析法(AHP)确定疲劳风险评价指标,依据G1法编制专家调查问卷,采用专家独立调查方法对指标进行判断,根据G1法确定各指标权重,建立飞行疲劳综合评价指标体系,实现对疲劳风险的量化综合评价。结果表明:运用G1法能有效地综合利用影响疲劳的各种信息评价飞行员的疲劳状况,该指标体系与现有控制飞行疲劳风险的影响因素吻合较好,可以作为进一步实现疲劳风险量化的基础。     

污泥活性炭的制备及其对酸性红G的吸附行为

以城市污水处理厂的脱水污泥为原料,用Zn Cl2活化法制备污泥活性炭,并研究其对水中酸性红G的吸附、脱附行为。选取活化剂浓度、固液比、活化温度及活化时间等因素,通过正交实验确定了最佳工艺,即Zn Cl2浓度30%,固液比1∶2,碳化温度500℃,碳化时间1.5 h。吸附实验结果表明,该污泥活性炭对水中酸性红G的吸附量随着温度升高而增加,在15、25和35℃条件下的最大吸附量分别为153.6、165.6和180.4 mg/g,且吸附等温线能较好用Langmuir方程进行模拟。酸性红G在污泥活性炭上的吸附动力学符合准二级反应动力学模型。污泥活性炭对酸性红G的吸附量随着溶液p H的增大而减小,污泥活性炭的最佳投加量为0.26 g/L。吸附饱和的污泥活性炭可通过碱处理和热处理方法进行脱附,脱附后的吸附剂对酸性红G仍具有很强吸附性能。     

Dynamic relationship between precious metals

We use a relatively new approach to endogenously detect the volatility shifts in the returns of four major precious metals (gold, silver, platinum and palladium) from 1999 to 2013. We reveal that the turbulent year of 2008 has no significant effect on volatility levels of gold and silver however causes an upward shift in the volatility levels of palladium and platinum. Using the consistent dynamic conditional correlations, we show that precious metals get strongly correlated with each other in the last decade which reduces the diversification benefits across them and indicates a convergence to a single asset class. We endogenously detect the shifts in these dynamic correlation levels and reveal uni-directional volatility shift contagions among precious metals. The results show that gold has a uni-directional volatility shift contagion effect on all other precious metals and silver has a similar effect on platinum and palladium. However, the latter two do not matter in terms of volatility shift contagion. Thus, investors that hedge with precious metals should, in particular, monitor the volatility levels of gold and silver.     

Quantifying the effect of strong ignition sources on particle preconditioning and distribution in the 20-L chamber

Computational fluid dynamics is used to investigate the preconditioning aspect of overdriving in dust explosion testing. The results show that preconditioning alters both the particle temperature and distribution prior to flame propagation in the 20-L chamber. A parametric study gives the fluid pressure and temperature, and particle temperature and concentration at an assumed flame kernel development time (10 ms) for varying ignitor size and particle diameter. For the 10 kJ ignitor with 50% efficiency, polyethylene particles under 50 μm reach 400 K and may melt prior to flame propagation. Gases from the ignitor detonation displace the dust from the center of the chamber and may increase local particle concentration up to two times the nominal value being tested. These effects have important implications for explosive testing of dusts in the 20-L chamber and comparing to larger 1-m³ testing, where these effects may be negligible.     

Prenatal detection of mosaic isochromosome 20q: a fourth report with abnormal phenotype

We described a new case of mosaic isochromosome 20q revealed by amniocentesis. The propositus presented with craniofacial dysmorphism, clubfeet, and vertebral abnormalities. A 46,XX,i(20)(q10)[14]/46,XX[1] karyotype was confirmed by FISH on cultured cells. The pregnancy was terminated. From review of literature, fetus with mosaic isochromosome 20q identified on amniocentesis are most likely to be phenotypically and cytogenetically normal after birth. So we performed CGH and array-CGH to exclude another possible imbalance. We discuss here the possible relation between this chromosomal abnormality and the abnormal phenotype. Copyright © 2005 John Wiley & Sons, Ltd.