Automatic substepping integration of the subloading tij model with stress path dependent hardening

This paper discusses the numerical integration of the subloading tij model. This is an elastoplastic model with stress path dependent hardening, which can predict the behaviour of normally consolidated clays or loose sands, as well as of over-consolidated clays or dense sands, with a small number of material parameters. Three features distinguish the subloading tij model from the conventional ones: (a) the use of a modified stress space given by tensor t_ij; (b) the split of the plastic strain increments in two components leading to a stress path dependent hardening; and (c) the use of two yield surfaces (subloading yield surface and normal yield surface). This last feature is based on the concept of sub-yielding stress states and adds an extra internal strain-like hardening variable, related to the relative density state, which demands its own evolution law. The three characteristics above greatly improve the prediction capabilities of the model, with respect to those of the well-known Cam clay model, at the cost of only two additional parameters. Nonetheless, the numerical integration of the constitutive equations of subloading tij model is a bit challenging, mainly due to the stress path dependent hardening. In order to integrate the equations of subloading tij model in the same way as for any conventional model, the authors reformulated its equations in a simpler and direct manner. Here, these equations are integrated using multi-step explicit schemes, such as modified-Euler and Runge–Kutta–Dormand–Price, with automatic error control. Simple forward-Euler scheme is also used for the sake of comparison. The results show that the modified-Euler scheme is more accurate as well as faster than the other schemes analysed over a wide range of error tolerance. Besides, the automatic feature of these schemes is a great convenience for the users of numerical codes.     

自动激光雨滴谱仪在雷达降水估测中的应用

利用Parsivel激光降水粒子谱与地面雨量计对2008年9月9号山西的一次混合降水天气过程进行分析,根据汾阳、介休两站的雨滴谱资料,利用最小二乘法拟合出反射率因子Z与雨强I的关系Zott=159Iott1.5,利用最优化关系法计算出地面雨量计与雷达反射率因子的关系Zrad=200Irain1.2,WSR_88D中默认的关系ZDef=300I1.4,然后分别利用3种Z-I关系对此次降水过程进行估测,计算过程累计雨量,并将估测降水结果与地面雨量计实测结果进行对比.结果表明:利用雨滴谱关系的估测降水效果最好,利用雨量计关系的估测降水结果次之,默认关系计算结果最差;第一者相对第二者提高4％左右,相对第三者则提高近18％左右.     

区域化探资料研究基础地质问题

区域化探资料不仅可以用于矿产勘查,而且,在基础地质研究中也可发挥重要作用.文中探讨了应用区域化探资料划分和圈定侵入岩体,进行地层对比和划分,识别各种区域地质构造,甚至板块分界线的问题,初步归纳出反映各种区域地质特征的区域地球化学分布模式.     

Determination of organic carbon in soils and sediments in an automatic method

Our automatic digestion device is applied in determining the quantity of organic carbon in the soils/sediments. Its operation process is simple. The reaction conditions are optimized; the complex pretreatments are automated; and a great number of samples can be analyzed at the same time. Comparison shows that the experiment using the device is safer and easier. The correlation coefficiency is greater than 0.999, indicating a good linear relationship. The relative standard deviations of three different concentrations are less than 5%. Standard addition recoveries of high and low concentration range between 94.7% and 100% and between 91.7% and 105% respectively. Method determination limitation (MDL) of this method meets the practical requirements. The device in this paper supports a compositive SOC determination method. Its advantages include improved time and labor efficiency, and accuracy. The device is widely used in the studies of agricultural science, carbon cycle, climate change and environmental protection.     

自动气象站常见的异常问题及解决方法

对自动气象站常见的异常问题进行分析，并对这些异常问题提出解决方法。     

中尺度自动站数据处理系统

为了解决中尺度自动气象站建设后探测数据的应用和共享问题，利用数据库等计算机技术，开发一套自动数据处理系统。实现了数据的处理储存、灾害天气预警和数据在不同部门之间共享。     

乡级自动雨量站与自动气象站雨量资料的融合

分析了乡级自动雨量站与自动气象站雨量资料融合的必要性,介绍了资料融合的思路与方法。通过这种方法,实现了商丘市两种雨量资料的完全共享。     

自动位移计在树坪滑坡中的应用

用自动位移计对长江干流的树坪滑坡进行了近一年的连续性观测,数据结果显示树坪滑坡体变形的控制因素为降雨和库水波动,滑坡目前变形速率较小,不会失稳。自动位移计通过连续记录数据,对树坪滑坡体的变形特征给予了准确的反映,且数据采集方便,值得在三峡库区边坡监测中推广应用。     

位移和最大相关距离在ECMWF集合预报产品中的应用

文章提出了一种对集合预报产品进行自动划分的新方法, 即位移和最大相关距离。 其基本假定是集合预报成员在一定程度上代表了未来可能发生的某类天气形势, 为此引入了天气类型的概念, 并以法国中期预报员总结出的影响法国的 5 类天气形势为基础, 对欧洲中期天气预报中心(以下简称 ECM WF)的集合预报产品进行了划分。结果表明, 大气的可预报性与预报时效、预报的天气有关。 该文提出的新方法简洁直观, 便于使用, 在天气类型和实际天气之间建立了最直接的联系, 大大压缩了集合预报产品的信息量。 ECM WF 的集合预报产品对影响法国的平直型、热阻塞型、冷阻塞型、扰动型等天气形势预报效果比较好, 而对波动型则效果稍差。     

AW11型自动气象站的原理及应用

本文介绍一种新型的自动气象站，它是针对小机场、直升机场和无人值守的飞机跑道而设计的独立天气观测和报告系统，可以测量全部标准的航空天气参数和生成精确实时的天气报告。