球形封闭容器内一个简单的煤粉燃烧爆炸模型

在分析了大量球形封闭容器内煤粉燃烧爆炸实验数据基础上，考虑了煤粉燃烧爆炸机理所涉及的湍流燃烧、相变、各种化学反应动力学过程等复杂因素，并且对球形封闭容器内由于煤粉混合不均匀造成的燃烧不充分给予了考虑，得到了球形封闭容器内煤粉燃烧爆炸特征的数值计算结果，计算的压力－时间曲线与实验结果符合较好。     

Determination of polycyclic aromatic hydrocarbons from ambient air particulate matter using a cold fiber solid phase microextraction gas chromatography-mass spectrometry method

Polycyclic aromatic hydrocarbons (PAH) from ambient air particulate matter (PM) were analyzed by a new method that utilized direct immersion (DI) and cold fiber (CF) SPME-GC/MS. Experimental design was used to optimize the conditions of extraction by DI-CF-SPME with a 100μm polydimethylsiloxane (PDMS) fiber. The optimal conditions included a 5min equilibration at 70°C time in an ultrasonic bath with an extraction time of 60min. The optimized method was validated by the analysis of a NIST standard reference material (SRM), 1649b urban dust. The results obtained were in good agreement with certified values. PAH recoveries for reference materials were between 88 and 98%, with a relative standard deviation ranging from 5 to 17%. Detection limits (LOD) varied from 0.02 to 1.16ng and the quantification limits (LOQ) varied from 0.05 to 3.86ng. The optimized and validated method was applied to the determination of PAH from real particulate matter (PM10) and total suspended particulate (TPS) samples collected on quartz fiber filters with high volume samplers.     

模拟酸雨条件下浙江省金华市城市灰尘重金属的解析状况探究

通过网格采样法,采集了金华市一环线以内地区的20个城市灰尘样品,然后利用原子吸收分光光度计测定了城市灰尘重金属Zn、Cu、Cr和Pb在不同pH的模拟酸雨溶液浸提下的析出值,并采用地积累指数法对各重金属有效性的状况做出了评价。结果表明,研究区域内,城市灰尘重金属Zn、Vu、Cr和Pb在酸雨背景下的析出值分别处于清洁水平、轻污染水平、中等污染水平和偏中等污染水平,该区城市灰尘有效Cr和有效Pb的污染程度较高,值得关注与采取措施进行预防与整治。     

矿尘影响下生态系统脆弱性级联传播模型分析

为了解决矿尘连续排放并迁移对地表生态系统造成的脆弱性问题,提出了基于函数地理Petri网的脆弱性级联传播模型。综合考虑污染物迁移方向和生态环境在地理空间上的关联关系,直观地构造了基于级联传播的污染Petri网。在此基础上,定义了基于VCPM的脆弱度和阈值的概念,利用两者的关系进行脆弱性级联传播分析,从而明确级联传播的三种状态。最后,以神府煤田矿尘迁移作为污染物连续排放的污染源,通过模型方法的模拟仿真分析,对生态环境系统在级联传播下的脆弱性进行了深入探讨。已有的研究方法和结果不仅在生态环境脆弱性研究领域做出了新的贡献,而且为环境的修复和重建提供了参考价值。     

Plasma Parameters around a Chain-Like Structure of Dust Particles in an External Electric Field

The formation of a 1D chain-like structure of dust particles in a low-temperature argon plasma was studied. A new numerical model for calculation of the self-consistent spatial distribution of plasma parameters around a chain of dust particles was presented. The model described the motion of positively charged ions in the electric potential of several negatively charged dust particles, taking into account the action of an external electric field. The main advantage of the model was that the charges of the dust particles and the interparticle distances were determined self-consistently. As a result of numerical simulations, the dependencies of the spatial distributions of the plasma parameters (the densities of electrons and ions and the self-consistent electric potential) near the dust particles chain on the strength of the external electric field, an external force acted on the last particle, and the mean free path of the ions was determined. The obtained results made it possible to describe the process of the formation of chain-like structures of dust particles in discharge plasma.     

两种带电尘埃颗粒的等离子体鞘层玻姆判据

采用流体方程和尘埃充电自洽模型研究了鞘边含有两种尘埃颗粒的等离子体玻姆判据. 通过拟牛顿法数值模拟了鞘边两种尘埃颗粒的存在对尘埃自身充电以及离子马赫数的影响. 两种尘埃颗粒中含量较少的尘埃颗粒数密度的增加, 导致两种尘埃颗粒表面悬浮势一个降低, 一个升高. 含量较少的尘埃颗粒的数密度越多和半径越小, 都会导致离子马赫数增大. 另外鞘边无论何种尘埃颗粒的速度增加, 鞘边离子马赫数都将减小. 关键词： 等离子体鞘层 尘埃颗粒 玻姆判据     

关于自相似集的Hausdorff测度的一个判据及其应用

讨论了满足开集条件的自相似集。对于此类分形，用自然覆盖类估计它的Hausdorff测度只能得到一个上限，因而如何判断某一个上限就是它的Hausdorff测度的准确值是一个重要的问题。本文给出了一个判据。作为应用，统一处理了一类自相似集，得到了平面上的一个Cantor集－Cantor尘的Hausdorff测度的准确值，并重新计算了直线上的Cantor集以及一个Sierpinski地毯的Hausdorff测度。     

Reductive opening of glycal derived highly functionalized 2,3-epoxy-1-iodides with zinc dust: an efficient method for the synthesis of acyclic long chain polyhydroxylated terminal alkenic alcohols

The synthesis of densely functionalized acyclic long chain terminal alkenic alcohols was achieved by reductive opening of glycal derived 2,3-epoxy-1-iodides, with commercial zinc dust alone in a short reaction time with excellent yields involving a simple reaction procedure and easy work-up. A mechanism involving an organometallic intermediate is proposed.     

Origin of microspherules in Paleozoic-Mesozoic bedded chert as estimated from its morphology

Summary In a previous study, we gave the PIXE analysis results of magnetic spherules collected from Paleozoic-Mesozoic bedded chert compared with carbonaceous chondrite and supposed the origin of microspherules to be interstellar in origin, similar to carbonaceous chondrite, rather than interplanetary. The previous suggestion was again confirmed from observation of the internal texture of microspherules.