Comparison between Eulerian and Lagrangian semi-analytical models to simulate the pollutant dispersion in the PBL

In this work we display a numerical comparison, under statistical and computational point of view, between semi-analytical Eulerian and Lagrangian dispersion models to simulate the ground-level concentration values of a passive pollutant released from a low height source. The Eulerian approach is based on the solution of the advection–diffusion equation by the Laplace transform technique. The Lagrangian approach is based on solution of the Langevin equation through the Picard’s Iterative Method. Turbulence inputs are calculated according to a parameterization capable of generating continuous values in all stability conditions and in all heights of the Planetary Boundary Layer (PBL). Numerical simulations and comparisons show a good agreement between predicted and observed concentrations values. The comparison reveals the main advantages and disadvantages between the models.     

Advanced on-board processing for user oriented communication systems

The continuing improvement of RF components, particularly in the field of spot-beam antennas, combined with the steady progress in digital technology, leads us to consider the advantages of a satellite system able to provide full connectivity to ground stations operating at different data rates. For low data rates, two different access methods: continuous TDM and Multi-carrier TDMA, are compared for earth-stations operating at 2Mb/s. The two methods are compared from the point of view of efficiency and adaptability in a non-uniform load environment. Some control criteria are proposed for the Multi-carrier system. Both methods are particularly suited for small users.     

航天产品多源可靠性信息的收集与整理--建立可靠性信息数据库

航天产品可靠性信息的来源多样，可靠性信息的时间性、随机性、有价性、时效性和可追溯性等特征，决定了可靠性数据收集应满足真实性、连续性、完整性等基本要求。同时，对多源信息的收集应遵循先进行需求分析，再确定数据收集点并制定数据收集表格的程度进行。给出了信息的适用性准则和信息分类的三维模型。最后结合具体型号航天产品的可靠性工作的要求，给出了可靠性信息数据库系统的整体方案设计。     

关于企业经济效益综合评价模型的再讨论——利用费歇判别值进行排序的质疑

本文从理论上讨论了费歇判别与回归模型的等价，指出了利用费歇判别值对企业的综合经济效益进行排序是不合理的，并提出了改进的综合评价方法     

Calorimetric analysis of the ethanolysis of 1,2-epoxybutane

Polyethers, which are produced by alcoholysis of oxiranes, are often used as solvents in chemical plants. The spectra of the products can be influenced by the choice of the catalyst (acid or base). The results of the base-catalyzed ethanolysis of 1,2-epoxybutane are displayed. The reaction was investigated calorimetrically by varying the molar ratio between ethanol and 1,2-epoxybutane, the starting temperature and the concentration of the catalyst sodium hydroxide. Additionally, the influence of the used alcohol will be shown in one example. To determine the activation parameters, the experiments were evaluated by the nonlinear software package TA-kin v3.3.     

柯伐镀金盖板电化学腐蚀的剖析及其防腐措施

对半导体器件封装的气密性失效进行了研究。发现，柯伐镀金盖板遭致电化学腐蚀是导致气密性失效的主要原因。对电解液的形成和电化学腐蚀机理进行了深入的分析。提出了防止腐蚀，提高器件气密可靠性的思路和方法。     

用模糊综合评价值作为单纯形优化指标

本文介绍了一个模糊综合评价方法,讨论了模糊运算方法对运算结果即综合评价值的影响,并将模糊综合评价值用作单纯形优化指标。     

Re-Evaluation of the Activity Coefficients of Aqueous Hydrochloric Acid Solutions up to a Molality of 2.0 Using Two-Parameter Hückel and Pitzer Equations. Part I. Results at 25°C

Simple two-parameter Hückel and Pitzer equations were used for the calculation of the activity coefficients of aqueous hydrochloric acid at 25°C up to a molality of 2.0 mol-kg^–1. The data obtained by Harned and Ehlers^(12,13) from galvanic cells without liquid junction were used in the analysis and the parameters obtained were compared to those obtained from all reliable data presented in the literature for HCl at this temperature. A good agreement between the parameters was always observed. The activity coefficients obtained by the new equations were compared to those suggested by Robinson and Stokes,⁽⁸⁾ Hamer and Wu,⁽¹⁾ and Pitzer and Mayorga,⁽⁹⁾ and good agreement was also found. The data from the most important literature data sets for HCl were also predicted using the new activity coefficient equations, and the magnitude of the resulting errors was close to the precision of the measurements, the errors forming an almost random pattern for all data sets.     

土壤中总汞测量不确定度的评定

依据JJF1059-1999,对GB/T17136-1997冷原子吸收分光光度法测定土壤中总汞含量进行了不确定度评定。建立了数学模型,对各不确定度分量进行分析和量化。计算出土壤中总汞含量测量结果的相对合成标准不确定度为0.0215,扩展不确定度为0.163mg/kg。在土壤总汞含量测量过程中,求试液中汞含量贡献的不确定度最大。     

二元酸茄呢醇乳糖和麦芽糖酯合成及生是活性测试研究

七个二元酸茄呢基单酯分别与溴代乙酰乳糖和溴代乙酰麦芽糖在四丁基溴化铵 催化下反应生成对应的糖酯，制得的十四个化合物均为新化合物，其结构经过了元 素分析、IR，~1H NMR和MS确证。并对六个化合物做了KB（人口腔上皮癌细胞）、 Bel-7402（人肝癌细胞）、HCT-8（人结肠癌细胞）三种癌细胞初步生理活性测试。