静电屏蔽物理原理

本文从电场强度、电势两方面探讨了静电屏蔽的物理原理以及静电屏蔽的实质。     

Analysis of carbon isotopes in airborne carbonate and implications for aeolian sources

Methods were developed to determine the mass ratios of carbon isotopes in trace amounts of aerosol carbonate. A Finnigan MAT 252 mass spectrometer fitted with an on-line Kiel device was to determine the ^13C/^12C ratio in CO2 produced from the carbonate. A study using these methods was conducted to characterize the carbonate carbon isotopes in aerosol samples collected in Xi‘an on dusty and normal days during March and April 2002. Results of the study demonstrate that insights into the origin of the dust can be deduced from its isotopic composition. That is, the δ^13C ofcarbonate for dust storm samples ranged from -1.4‰ to -4.2‰, and this is consistent with sandy materials in dust source regions upwind. In contrast, for non-dusty days δ^13C ranged from -7.5% to -9.3‰, which is more similar to fine particles emitted from local surface soils. Comparisons of dust storm aerosols with surface soils from source regions and with aerosol samples collected downwind indicate that the δ^13C values did not change appreciably during longrange transport. Therefore, carbon isotopes have the potential for distinguishing among source materials, and this approach provides a powerful new tool for identifying dust provenance.     

线性矩阵不等式F_0＋sum from j＝1 to k of x_j F_

应用矩阵求迹运算“ｔｒ（·）”得到了线性矩阵不等式Ｆ_０＋sum from j=1 to k of ｘ_ｊ Ｆ_ｊ＞０解的充分条件，这些充分条件皆为应用中容易检验的代数不等式．并据此给出了相应的代数解     

Characterization of MASDs of surface soils in north China and its influence on estimating dust emission

Inordertoquantitivelyevaluateeffectsofdustaerosolonradiativeforcing[1],andtounderstandtheprocessofatmosphericchemistryandbiogeochemistry[2,3],modelingthedustemissionfluxisakindoffundamentalwork.TheDPMmodel[4—6]isidealforpredictingdustemission[7—10]becauseitconsiderseffectsofsurfacefea-tures(MASDofsurfacesoil,roughnesslengthandsoilmoisture,etc)andsandblastingprocess.Italsoprovidesanexplicitphysicalmechanismthatisvalidatedbywindtunnelandfieldexperiments[7—10].Themeandiameterofsurfacesoilsi…     

基于PSR和物元可拓模型的跨界河流健康评价 ——以太浦河干流为例

以太浦河为例,基于PSR模型构建针对水体和河岸带的多指标评价体系,运用熵权法计算指标权重,通过PSR模型和物元可拓模型对太浦河进行分段分类分级评价.结果表明:上游江苏吴江段分类结果为"高压力-较好状态-低响应能力"类型;中游浙江嘉善段为"低压力-中等状态-低响应能力"类型;下游上海青浦段为"低压力-中等状态-高响应能力"类型.吴江段河流健康状况评估结果为Ⅲ级(差),嘉善段和青浦段均为Ⅱ级(一般),且倾向于Ⅰ级(好),表明虽然河流目前的健康状态一般,但由于制定的政策在一定程度上有效,可通过进一步加大保护水源地力度逐步实现水源地健康状况恢复.研究结果可为太浦河分区治理和河岸带生态化建设提供决策支持.     

基于WRT方法的港口危化品物流风险评估研究

针对港口危化品物流风险管理中风险因素众多和交互影响的复杂性,构建港口危化品物流的WRT风险评估模型.首先基于物理-事理-人理WSR理论构建港口危化品物流风险评估指标框架,其次通过风险过滤和排序RFRM理论对风险因素进行双重过滤,保留关键风险因素.然后基于TSS情景构建理论从物理、事理和人理三个层面构建港口危化品物流的多维风险情景,通过深入剖析各风险情景下风险因素之间的耦合关系,刻画港口危化品物流中的不同风险状态与风险源最后,基于熵权法和贝叶斯理论对我国7个重要港口进行多维情景风险评估,结果表明天津港和南京港整体风险较大,多数情况下二维情景风险大于三维情景风险,同时从多维风险情景下对物理、事理、人理的耦合风险进行分析,展示了各港口的薄弱环节,最后为港口危化品物流风险管理提出建议.     

稀HCl/硅烷偶联剂处理E-玻璃纤维对BMC的增强

采用稀HCl和硅烷偶联剂KH-570先后处理E-玻璃纤维并用于团状模塑料(BMC)的增强。结果表明:经过1 mol/L稀HCl和质量分数为1.0%硅烷偶联剂KH-570先后处理的玻璃纤维,所制得的BMC抗弯强度为65.87MPa,高于单一改性玻璃纤维制得的BMC的强度。傅立叶变换红外光谱(FT-IR)、扫描电镜(SEM)和力学性能的分析表明:随着稀HCl浓度的增加,玻璃纤维的表面受刻蚀程度增加,表面积增大,—OH基团数量增多,有利于硅烷偶联剂KH-570与玻璃纤维表面结合产生更多的R—Si—O—基团,进而改善玻璃纤维与树脂的结合,提高BMC材料的抗弯强度。     

Validating a dust production model by field experiment in Mu Us Desert, China

It is essential for validation and improvement of a dust production model to perform field observations on dust emissions. The dust production model (DPM model) consists of two physically explicit sub-models, namely saltation model [1, 2] (eq. (1)) and sandblasting model [3] (eqs. (2) and (3)). Fh is saltation flux, E is fraction of erodible surface, C is a dimensional constant, ρa is air density, g is gravitational acceleration, U* is the wind friction velocity, Ut*(Dp) is threshold frict…     

选区激光熔化Al-Mg-Sc系高强铝合金的研究进展

选区激光熔化（Selective laser melting,SLM）技术具有一体化快速制备复杂和高精度零件的能力,在航空航天等工业生产中有巨大的发展潜力。高强铝合金是近年来在增材制造领域发展迅速,可实现结构轻量化的重要材料,其中Al-Mg-Sc系高强铝合金在结构和性能方面具有极大的潜力。本文针对增材制造领域Al-Mg-Sc系高强铝合金的应用与发展,结合增材制造工艺技术,从增材制造高强铝合金合金成分,微观组织和力学性能三个方面,全面总结了增材制造Al-Mg-Sc系高强铝合金的研究现状和进展趋势。在增材制造高强Al-Mg-Sc合金领域内,我们应当重点关注强化元素的多元化、SLM成形合金微观组织调控以及性能特征的多元化研究等方向,作为我们重点关注与发展的方向。     

菊花挥发油主要成分对肿瘤抗性的研究进展

菊花作为药食同源植物,含有多种化学成分,具有多种药理活性。菊花中含有挥发油、黄酮、绿原酸、生物碱、多糖、氨基酸等化学成分,现代药理研究证明菊花具有多种功效,如抗癌、抗氧化、抗炎、抗病毒、抗菌等,并对心血管、免疫系统、神经系统有一定作用。菊花成分中的挥发油,证实能够对多种癌症有抵抗功效,对近几年菊花挥发油中的主要成分β-榄香烯、小白菊内酯及菊花三萜烯二醇和三醇、α-甜没药萜醇、棕榈酸等的抗癌功效研究进行综述,以明确挥发油成分的抗癌潜力。