大体积进样技术结合同位素稀释法测定地表水中多环芳烃的研究

采用C18固相萃取柱预处理水样,由于固相萃取柱的选择吸附性,净化了样品的基质;同液-液萃取相比,固相萃取柱和硅胶小柱的双重净化,更适合大体积进样。萘、苊、菲、屈艹的氘代化合物作为同位素稀释剂,由于待测分析物与同位素稀释剂物理化学的相似性,其在固相萃取柱的保留行为和色谱运行行为都有基本一致性。同一般内标法相比,同位素稀释法具有较高的回收率。大体积进样由于进样绝对量的增加,降低了检出限。方法检出限0.05～0.1ng/L,回收率范围90%～110%。     

Assessment of nitrogen leaching from arable land in large river basins: Part II: regionalisation using fuzzy rule based modelling

This study deals with fuzzy rule based modelling of nitrogen (N)-leaching from arable land. Main purpose is the elaboration of a method, which allows dynamical regionalisation of results from process-based models for large regions and can be efficiently included in metamodels or decision support systems for rapid integrated assessment of water resources. The paper is the second part of a two-part paper. In the first paper the distributed ecohydrological model SWIM had been applied to calculate and analyse nitrogen dynamics in arable soils for a set of representative natural and management conditions in the Saale River basin (Ecol. Model. (in press)). Here, in the second paper the results from those simulation experiments are used to define, train and validate fuzzy rule systems for the estimation of N-leaching. Nine fuzzy rule systems, specific for nine soil classes, were created from the simulation experiments, representing the conditions for the whole Saale River basin. The fuzzy rule systems operate on monthly time steps and consist of 15 rules and seven input variables each, which are compiled from time series of precipitation, percolation and evapotranspiration as well as from information about fertilizer and crop specific nitrogen uptake. Simulated annealing as a non-linear discrete optimisation method is used for automatic rule assessment. Validation of the fuzzy rule systems, carried out by split sampling of 30-year simulation period, shows satisfactory performance on an annual basis and good performance on the long-term basis with average correlation between SWIM-simulated and fuzzy rule-estimated N-leaching values of 0.78 and 0.94, respectively.     

大型回转窑托轮轴疲劳断裂分析与防治

回转窑由于其支承载荷分配不均 ,托轮轴疲劳断裂现象频繁 ,这就严重影响了生产的正常进行 ,造成重大的经济损失。笔者通过对回转窑的托轮轴进行力学分析 ,导出托轮轴等效对称循环应力幅的计算方法 ;对现场回转窑进行分析计算 ,得出该窑托轮轴危险截面等效应力幅与所受载荷的线性关系 ,从而得到托轮轴疲劳极限对应的载荷值和一些重要结论 ;提出通过轴线检测和调整来控制托轮所受载荷 ,使托轮轴处在疲劳极限下运行 ,从而减少托轮断轴事故带来的重大损失 ,有着较好的经济效益     

A hybrid process for manufacturing surgical-grade knife blade cutting edges from bulk metallic glass

The demand for precision surgical knives is enormous. Currently, diamond knives have been the preferred choice among surgeons for use in precision surgeries, owing to the extreme hardness of diamond and the sharpness that can be achieved in single crystal diamond blades, but material and processing costs are high. Bulk metallic glass (BMG) has the potential to be an economically viable material of similar performance for use in precision surgical knives. To this end, a novel hybrid manufacturing process integrating thermally assisted micro-molding and micro-drawing has been developed for producing BMG surgical-grade knife blade cutting edges with edge radii <50 nm. A hybrid process testbed was designed and used to successfully run tests over a range of the key process variables. Through this testing the deformation of BMG under different strain rates and temperatures was studied in terms of the quality of edge formation. The hybrid process was shown to be capable of producing cutting edges of radius at or below 100 nm.     

Experimental study on the mechanism effect of seepage on microstructure of tailings

The deformation of microstructure of tailings caused by seepage is the main factor that leads the tailings dam to be damaged and lose stability. The effect of seepage on microstructure of tailings has been studied by a self-made observation testing apparatus of micro-mechanics and deformation of tailings, and its mechanism also has been explained in mechanics of particulate matter. The results show that the deformation response to microstructure of tailings is fast under load. The settlement of sample increases stepwise. Firstly, the fine particles crumble, then skeleton particles move, so as to noticeable settlement. Because the loose particles migrate taken by seepage water, the upper pores become bigger and lower pores become smaller. The relation of seepage water and settlement changing with time could be divided into two stages. In each stage, the rates of seepage and settlement reduce with time, and between the two stages, the rate of settlement increases significantly and the rate of seepage reduces with time. The seepage has significant effect on the particle size distribution of tailings in different depths, which has a little effect on the coarse tailings; the proportion of fine tailings increases significantly with the depth increasing; the minimum particle size decreases gradually and median diameter reduces stepwise with the depth increasing.     

大吨位起重机载荷试验的解决方案

本文介绍了国内外试重水袋的发展现状和水袋的结构组成,从试重水袋的安全、经济、节能、环保、高精度等优势进行了论述。提出了大型起重机载荷试验的解决方案,即水袋载荷试验法。     

大型环境监测实验室分析仪器绩效评估指标体系探索

大型环境监测实验室分析仪器是环境监测单位综合实力的集中体现,在环境监测工作中发挥着巨大作用。简述了仪器设备绩效评估研究现状,尝试构建大型环境监测实验室分析仪器绩效评估指标体系,并通过德尔菲法确定各项评价指标的权重值,最终计算绩效评估综合指数。在此基础上,对某省级环境监测机构的部分大型实验室分析仪器进行分析,提出,需合理配置仪器、加强日常维护管理以及开放共享等建议,为提高大型环境监测实验室分析仪器的精细化管理提供了科学依据。     

Cr-Cu触头粉末包套镦粗变形致密化的工艺研究

通过实验研究粉末包套镦粗变形致密化的基本规律,确定出最佳工艺参数,以指导生产.     

变薄拉深的变形力学性质的确定

对单模和多模变薄拉深的径向压应力和轴向拉应力进行比较后对其变形力学性质(属伸长类或压缩类)作了明确的回答.     

大型化肥装置酸气处理的探讨

在分析了大型化肥装置酸气处理的现状和发展趋势后，总结了大型化肥装置酸气的特点，并对两种可供选择的酸气处理方法进行了比较。