PATTERNS OF HORSE DEVOLUTION AND TRACTOR DIFFUSION IN ILLINOIS, 1920–1982*

The concern is to extend certain diffusion concepts to devolution. In this example, tractors replaced horses because tractors had advantages over horses. Logistic curves depict well the temporal rate of tractor acceptance and of horse abandonment. Although differing somewhat in time, the spatial patterns of adoption and abandonment are similar. They centered early in east central Illinois, a prosperous agricultural core, and spread outward. Laggard counties as well as persister ones were mainly in southern Illinois, a peripheral area with a relatively impoverished agriculture. Influences on the patterns include farm value, size, and type and land quality.     

Allometry in the pliocene bivalveAstarte omalii: A new look at an old data set

The relationships between ontogeny and phylogeny have been studied for the bivalve Astarte omaliifrom the Lower, Middle, and Upper Pliocene of Belgium using canonical variates analysis, principal components in the form of multivariate allometry, and bivariate power functions or allometric equations. The results indicate that the three samples represent segments of a single evolutionary lineage which is characterized mainly by paedomorphosis where adult descendants are similar to juvenile ancestors. Recapitulation or peramorphosis is only observed for a single parameter. The Lower and Middle Pliocene samples are considered as Astarte omalii omalii,whereas the Upper Pliocene specimens are placed in A. omalii basteroti.The evolutionary trends most likely reflect changes in the living positions of the bivalves.     

GPS定位中对流层折射率随机模型的研究

分析了ＧＰＳ相对定位中对流层折射的特点，概述了目前所采用的几种确定性参数对流层折射估计和随机过程参数对流层折射估计方法。根据实测数据处理结果，分析比较了几种确定性模型和随机过程模型对ＧＰＳ相对定位精度的改善作用。结果表明：对流层折射的多参数确定性模型和随机参数模型对基线分量的重复性，特别是高程分量的重复性有明显改善；在大多数情况下，尤以随机参数模型为佳，其垂直分量的重复性精度较单参数模型可提高一倍左右。     

含裂隙双相各向异性介质中的地震波传播

基于各向异性介质和含裂隙双相介质中的地震波传播理论,导出了具有四阶对称轴的含裂隙双相各向异性介质的本构关系与波传播的运动方程．指出在含裂隙双相各向异性介质中可能传播６种类型的准纵横波,即快纵波ＱＰ１,慢纵波ＱＰ２,两个分裂的快横波ＱＳＶ１,ＱＳＨ１和两个分裂的慢横波ＱＳＶ２,ＱＳＨ２．并以平面波传播为例作了进一步分析     

Stochastic differential dynamic programming for multi-reservoir system control

: As with all dynamic programming formulations, differential dynamic programming (DDP) successfully exploits the sequential decision structure of multi-reservoir optimization problems, overcomes difficulties with the nonconvexity of energy production functions for hydropower systems, and provides optimal feedback release policies. DDP is particularly well suited to optimizing large-scale multi-reservoir systems due to its relative insensitivity to state-space dimensionality. This advantage of DDP encourages expansion of the state vector to include additional multi-lag hydrologic information and/or future inflow forecasts in developing optimal reservoir release policies. Unfortunately, attempts at extending DDP to the stochastic case have not been entirely successful. A modified stochastic DDP algorithm is presented which overcomes difficulties in previous formulations. Application of the algorithm to a four-reservoir hydropower system demonstrates its capabilities as an efficient approach to solving stochastic multi-reservoir optimization problems. The algorithm is also applied to a single reservoir problem with inclusion of multi-lag hydrologic information in the state vector. Results provide evidence of significant benefits in direct inclusion of expanded hydrologic state information in optimal feedback release policies.     

A stochastic model of water-table elevation

A second order stochastic differential equation is used for modeling of water-table elevation. The data were sampled at the Borden Aquifer as a part of a tracer experiment. The purpose of the water-table data collection was to determine presence of a water flow. We argue that the water-table surface is a simple plane oscillating up and down in time according to an equation for a stochastic oscillator. We derive the model, estimate its parameters and provide arguments for goodness-of-fit of the model.     

A stochastic model of water-table elevation

A second order stochastic differential equation is used for modeling of water-table elevation. The data were sampled at the Borden Aquifer as a part of a tracer experiment. The purpose of the water-table data collection was to determine presence of a water flow. We argue that the water-table surface is a simple plane oscillating up and down in time according to an equation for a stochastic oscillator. We derive the model, estimate its parameters and provide arguments for goodness-of-fit of the model.     

湿大气方程组解的渐近性质

研究无穷维Ｈｉｌｂｅｒｔ空间中,湿大气运动系统解的长期行为,在导得了湿大气运动方程是Ｈｉｌｂｅｒｔ空间中一个非常特殊的算子方程之后,利用算子的性质讨论了全局吸收集和全局吸引子的存在性,揭示出系统解的渐近行为表现在吸引子的结构上及系统向非绝热加热的非线性适应过程。最后指出了几个简化方程组与原方程组在解的长期行为上的根本不同,从而给出长期天气或气候研究中简化方程组必须遵循的原则。     

利用地震面波频散反演岩石圈结构的奇异值分解算法

在利用面波频散数据反演介质S波速度结构的过程中,引入奇异值分解方法计算随机逆,利用Wiggins方法对较大奇异值修改和随机逆方法对较小奇异值修改的优点,协调了分辨率和解的关系,改进了随机逆解的精确性和稳定性．模型试算表明,该方法反演所得结果较Harkrider的程序反演结果精确,分辨率更高．     

具有随机地震应力积累速率的地震发生概率模型

时间可预测模型和滑动可预测模型是两个典型的地震可预测模型,它们均假定了不变的地震应力积累速率作为一种改进,假设地震应力积累速率是个随机变量,在不同的孕震时期具有不同的地震应力积累速率假设地震应力积累上限是不变的,就引出了“随机地震应力积累速率的极大应力水平模型”以鲜水河断裂带为例,运用改进模型进行了实例计算,结果表明：道李、康定、乾宁在30年内发生6级以上地震的概率分别是：0．67－0．85,0．45－0.50,0．23－0．26．