两条粗糙平行节理表面形貌对应力波能耗的影响研究

基于图形图像学与分形几何交叉学科理论,提出了一种用于描述节理面形貌的新方法—YUV维数法,该方法可替代传统分形维数且有其优势。在此基础上,通过对含两条粗糙平行节理岩石的SHPB试验,探讨了两条节理面形貌（以YUV维数描述）对应力波能耗的影响规律。研究结果表明:YUV维数法是一种新型表面描述方法,相对传统自相似图像维数有其优势;当两条节理YUV维数或节理YUV维数之和增大时,节理能耗值随之增加。出现上述现象的机理是:当节理面YUV维数增大时,岩石节理刚度相应减小,导致应力波穿越节理的能力降低,造成应力波能量耗散值增大。另外,能耗与YUV维数间呈现一种非线性关系,这种非线性关系是由节理的非线性变形所引发。为了工程应用之目的,同时给出了能耗与两条节理YUV维数间的二元函数关系。     

爆炸应力波在层状节理岩体中的传播规律试验研究

为了研究爆炸应力波在岩体中的传播规律,基于相似理论,开展了爆炸应力波在层状节理岩体中衰减的实验研究。研究表明,节理阻碍 应力波的传播且存在各向异性;对于垂直或小角度入射节理的应力波,在垂直方向和纵向的衰减很明显并且幅度较大,在横向衰减不明显;对 于斜入射节理的应力波,横向和垂直方向没有明显的衰减,纵向的衰减很明显并且幅度较大;应力波的合成峰值速度与炮孔密集度之间的关系 密切,当炮孔间距超过一定距离时,实际测得的速度时程为最近药包爆破产生的应力波,并非总药量产生的应力波的叠加。     

Estimating the critical phosphorus loading of shallow lakes with the ecosystem model PCLake: Sensitivity, calibration and uncertainty

There is a vast body of knowledge that eutrophication of lakes may cause algal blooms. Among lakes, shallow lakes are peculiar systems in that they typically can be in one of two contrasting (equilibrium) states that are self-stabilizing: a ‘clear’ state with submerged macrophytes or a ‘turbid’ state dominated by phytoplankton. Eutrophication may cause a switch from the clear to the turbid state, if the P loading exceeds a critical value. The ecological processes governing this switch are covered by the ecosystem model PCLake, a dynamic model of nutrient cycling and the biota in shallow lakes. Here we present an extensive analysis of the model, using a three-step procedure. (1) A sensitivity analysis revealed the key parameters for the model output. (2) These parameters were calibrated on the combined data on total phosphorus, chlorophyll-a, macrophytes cover and Secchi depth in over 40 lakes. This was done by a Bayesian procedure, giving a weight to each parameter setting based on its likelihood. (3) These weights were used for an uncertainty analysis, applied to the switchpoints (critical phosphorus loading levels) calculated by the model. The model was most sensitive to changes in water depth, P and N loading, retention time and lake size as external input factors, and to zooplankton growth rate, settling rates and maximum growth rates of phytoplankton and macrophytes as process parameters. The results for the ‘best run’ showed an acceptable agreement between model and data and classified nearly all lakes to which the model was applied correctly as either ‘clear’ (macrophyte-dominated) or ‘turbid’ (phytoplankton-dominated). The critical loading levels for a standard lake showed about a factor two uncertainty due to the variation in the posterior parameter distribution. This study calculates in one coherent analysis uncertainties in critical phosphorus loading, a parameter that is of great importance to water quality managers.     

A Voronoi diagram based population model for social species of wildlife

A population model is presented that accounts for spatial structure within habitat patches. It is designed for social species of wildlife that form social group home ranges that are much smaller than patch size. The model represents social group home ranges by Voronoi regions that tessellate a patch to form a Voronoi diagram. Neighbouring social groups are linked with habitat-confined shortest paths and form a dispersal network. The model simulates population dynamics and makes use of Voronoi diagrams and dispersal networks as a spatial component. It then produces density maps as outputs. These are maps that show predicted animal densities across the patches of a landscape. A construction procedure for the particular Voronoi diagram type used by the model is described. As a test case, the model is run for the squirrel glider (Petaurus norfolcensis), a small arboreal marsupial native to Australia. A time series of density maps are produced that show squirrel glider density changing across a landscape through time.     

海洋环境腐蚀模拟试验装置的优化设计与研制

本文介绍了基于GB/T 19746—2005/ISO 11130:1999等材料腐蚀性能试验标准的试验装置设计要求以及试验装置的主要组成。重点是添加了温度控制系统,优化了潮差控制系统,模拟了海洋波浪。本试验装置是一种结构简单、能够较真实模拟海洋环境腐蚀的试验装置。该试验装置研制成功,为研究海洋用材料的腐蚀行为与机理提供重要的技术设备支持。     

浅析MDCB电磁波仪器在临震预测中的应用

本文简要分析电磁波的接收及仪器原理,介绍MDCB电磁波法进行地震短临预报的方法,统计了多次预报地震的结果,对这种预报方法进行了研究讨论,并与传统电磁波仪器预报地震的方法进行对比,指出这种预报方法的优点和存在的问题.     

沈阳市大气细菌与真菌粒子的关系

用ＡＮＤＥＲＳＥＮ生物粒子采样器对沈阳市大气细菌和真菌粒子的密度、密度分布、粒度分布及两者关系进行了观察和。结果表明，沈阳市大气年平均密度细菌粒子为７２２８个／ｍ＾３，真菌粒子为１７９７个／ｍ＾３，细菌为真菌的４．１倍。细菌粒子密度和粒度均呈正偏态分布，真菌粒子密度和粒度均呈对数正态分布。〈８．２μｍ的可吸入粒子，细菌为４３２６个／ｍ＾３，占其总数的６１．４％；真菌为１５８３个／ｍ＾３，占其总数的     

基于CFD仿真的炮口制退器性能影响因素研究

目的 在降低火炮后坐力的同时,保证炮手区域超压和温度符合要求。方法 利用流体仿真软件进行炮口流场的数值模拟,对制退器性能影响因素进行仿真分析。根据分析结果,得到改进后的制退器模型,并进行仿真和试验对比。结果 加装侧孔外反射挡板和侧孔倾斜对制退器性能的影响较大,并随角度的变化而变化,加装吹孔能有效降低炮后超压和温度。改进后,制退器的效率提升8.33%,炮后超压值平均降低44.10 kPa,炮后温度值平均降低358.28 K。结论 改进后的制退器具有更高的制退效率以及较低的炮后超压值和温度值。     

主要气象因素对可吸入颗粒物浓度影响规律探讨

简要介绍了上海、南京、苏州和南通市区API污染指数逐月同步走向的一致性,得出环境空气质量保护目标确定条件下,影响大气污染物浓度高低的主要因素是大中尺度天气系统的气象因素以及春、夏、秋、冬和典型冬季寒潮前后,南通市区可吸入颗粒物与气象因素之间的相关变化关系.说明在政府加大力度控制大气污染物排放量并取得阶段性成果时,另一个影响可吸入颗粒物浓度高低变化的重要因素是气象因素.     

苯酚-次氯酸钠示波极谱法测定水中微量氨

在亚硝基铁氰化钾存在下,氨在氢氧化钠介质中与苯酚、次氯酸钠反应,其产物靛酚在滴汞电极上产生一灵敏的吸附波,NH3-N在0.003～0.22mg/L范围内,导数峰电流与其呈良好的线性关系.用于环境水中NH3-N的测定,其相对标准偏差小于3%,回收率在97%～105%之间,方法具有较好的选择性.