模型理论

Also the problems of stochastic controllability, observability and stability of the filter are studied, a simple observability criterion for the time-invariant systems is set up, error band of the filtering is given theoretically, and the filtering stability results are proved under more general conditions; besides, the filtering error caused by uncorrect mathematical models is analysed.

本文还研究了随机能控能观性及滤波的稳定性问题，建立了结构简单的平稳定常系统的能观性判据，在理论上给出了滤波算法的误差范围，在更一般的条件下证明了最优滤波算法的稳定性；并从理论上分析了模型误差对滤波产生的影响。

The estimative reliability model involving the residual life of the high temperature boiler pipe of steam-generator has been established by using of reliability theory and fraction criterion of life loss.

利用可靠性理论和寿命损耗分数准则，建立了蒸汽发生器高温炉管的剩余寿命可靠性预测模型，并应用实例对不同模型进行了对比分析，确定了蒸汽发生器高温炉管剩余寿命可靠性预测的准确方法，可为蒸汽发生器高温炉管的管理和使用提供参考依据。

In this thesis, a two-dimensional sediment transport model in estuary and coastal areas is developed.

本文在现有河口海岸动力学理论、泥沙运动理论和数值计算方法的基础上，建立了适用于河口、海岸区域的平面二维水流泥沙输移数学模型。

It anlysises the connotation and the cause of the ecological risk. Based the research about ecological risk theory, the model of EVR has been established with use of VaR which is a very popular risk man agement model in international market.

系统探讨了生态风险的成因、内涵；结合当前国际上流行的VaR风险管理模型，在生态风险理论有关研究的基础上，建立了一类新颖而实用的区域生态系统风险管理模型－EVR。

In order to find out completely the soil-wheat contaiminated by heavy metals in Tianjin sewage farm, we collect samples on the dry land and examinate contents of heavy metals in soil-wheat system. Firstly, the anthor evaluates that soil irrigated by sewage that has been contaminated slightly, the main polluting factors are Cd and Zn, and then the anthor evaluates soil according to different regions, soil types and irrigating water. Secondly, the anthor analyzes content and enrichment ability of heavy metals in different part of wheat, evaluates wheat is contaiminated by Cd widespreadly, only few samples polluted by Zn.Finally the anthor put up correlative analysis about heavy metal contents in the soil-wheat system, as well as plant enrichment coefficient and some physico-chemical properties of soil, and establishes a prognostic model about heavy metal content among wheat spike, soil, soil types, PH, organic matter and salinity with the quantifying theory.The prognostic accuracy of primarily contaminative factors is the best with compound correlative coefficient examining, the model can be founded.With improvement of living level, people need cleaner food.

为全面了解天津市污灌区农产品生产地土壤和旱地作物小麦的重金属污染状况，我们于2004～2005年对全市污灌区的土壤和小麦进行了采样，在对该区土壤—小麦系统中六种重金属元素(Cd、Cu、Pb、Zn、Cr和Ni)的含量进行检测的基础上，本文首先分析评价了污灌区农田土壤的环境质量总体已达到了轻度污染水平，主要的污染因子是Cd和Zn，同时对污灌区农田土壤分区县、土壤类型和不同灌水类型进行了评价；然后分析了重金属在小麦不同部位的含量与富集能力，评价了污灌区旱地作物小麦普遍遭受了Cd的污染，只有个别样点遭受了Zn的污染；最后对土壤—小麦系统重金属含量间以及植物富集系数与土壤部分理化性质间进行了相关分析，由于土壤类型是定性变量，本论文以数量化理论建立了小麦穗实中重金属含量与土壤中重金属全量、土壤类型、PH值、有机质和全盐量间的预测模型，经复相关系数检验，污灌区主要的污染因子Cd和Zn的预测精度最高，模型可以成立。

This paper presents a mathematical model for describing the variations of the condenser temperature and pressure with the exhaust steam heat load ,frontal air speed and the inlet air temperature of an .

通过理论分析，建立了空冷凝汽器温度和压力随汽轮机排汽热负荷、凝汽器迎风面风速以及进口空气温度变化的理论模型。

Also, we show the existence conditions and economic interpretation of the optimal solution.

本文从理论上证明了模型最优解与用户均衡的一致性，给出了模型最优解的存在条件和最优解的经济解释。

Based on expansion of ODF in series of Generalized Spherical Harmonics by Bunge, we design programming in Orientation Distribution Function for polycrystal which contained five thousands crystals based on increment arithmetic of Voronoi. Geometrical data information, ODF of every crystal in polycrysal are imported to Open Graphics Library to draw, that means we implement visualization of ODF for every crystal in polycrystal.

主要针对具有立方结构的多晶体材料，采用Bunge级数展开法模型计算取向分布函数的理论模型，利用C语言在VC++环境下对ODF值进行了计算，并以Voronoi增量算法为基础生成包含有5000个晶粒的多晶体材料各晶粒的几何数据信息，与计算得到的ODF值一起导入OpenGL进行可视化处理，直观显示了多晶体材料中ODF值在各晶粒内的分布。

In this paper the structure principle of GM(1, 1) was analyzed and the defect was pointed out that the traditional model only adapt to the data with exponential law, and only can fit for the monotonic data. The prediction is defected when there are two consecutive data unchanged, and 'a' is equal to 0.5 in prediction formula.

从传统GM(1，1)预测模型构造原理出发分析其存在的理论缺陷，此模型适用于具有较强指数规律的序列，只能描述单调变化过程，而且预测数据序列中出现连续两个相等值时将使得a等于0，会使预测数列发散致使预测失效。

In traditional measurement model, remuneration distribution that has thick tail phenomenon cannot effective to appear, because of it based on normal distribution supposition, then developing the extreme value theory which is non-regular distribution. Although, extreme value theory has an advantage can get risk degree in moment, but it cannot fully explain long term influence.

在传统的计量模型上，对於报酬具有后尾的现象无法有效的显现，因其建构基础皆架构在常态分配假设之下；而后发展出非固定分配假说的极值理论；虽然极值理论有非特定分配的优点，可以捕捉到瞬间的风险状况，但对长期的影响依然无法获得充分的诠释。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失