Datasonics声学系统输出信号与悬浮物浓度的关系及计算     

周明 《海洋技术学报》1991,10(3):37-43

Datasonics声学探测系统的主要功能之一是实时探测水体中悬浮颗粒物浓度的时空分布。本文论述了该系统输出信号与悬浮物浓度的关系,分析了关系式中各项的意义,给出了Data-sonics系统悬浮物浓度的计算实例:并对声学系统参数的确定及其在计算中的应用进行了讨论。对于不同的声学系统,可根据各自的系统参数依此方法进行声学信号与悬浮物浓度的标定及计算。  相似文献   

一类非线性二阶常微分方程解的多重性     

朴大雄  贺佳 《中国海洋大学学报(自然科学版)》2007,37(6):1039-1044

考虑一类二阶非线性常微分方程的边值问题（p（t）u′）′＋h（t）f（u）=0，0＜t＜1和u（0）=u（1）=0。通过引入f（s）／s在∞与0处的极限值，并运用打靶法和相应的Sturm比较定理得到解的多重性定理，推广有关文献中的许多重要结果。  相似文献   

回顾与展望     

《山东海洋学院学报》1984,14(1):28-30

数学系创建于1977年。在完成全院各专业的数学教学任务的同时，积极开展了科学研究。在常微分方程、随机微分方程、偏微分方程、生物数学等基础数学和应用数学分支中取得了一批成果，并结合海浪、海流、潮汐、海洋工程、海洋气象、海洋地质、海洋生物及水产科学的研究获得了一些具有实用价值的成果。  相似文献   

Nonlinear Static Finite Element Stress Analysis of Pipe-in-Pipe Risers   总被引：4，自引：1，他引：4  

周宏杰  闫澍旺崔溦 《中国海洋工程》2005,19(1):155-166

Owing to the complexity of the pipe-in-pipe (PIP) riser system in structure, load and restraint, many problems arise in the structural analysis of the system. This paper presents a new method for nonlinear static finite element stress analysis of the PIP riser system. The finite element (FE) model of the PIP riser system is built via software AutoPIPE 6.1. According to the specialties of a variety of components in the PIP riser system, different elements are used so as to model the system accurately. Allowing for the complication in modeling the effects of seabed restraint, a technique based on the bilinear spring concept is developed to calculate the soil properties. Then, based on a pipeline project, the entire procedure of stress analysis is discussed in detail, including creation of an FE model, processing of input data and analysis of results. A wide range of loading schemes is investigated to ascertain that the stresses remain within the acceptable range of the pipe material strength. Finally, the effects of the location of flanges, the thermal expansion of submarine pipelines and the seabed restraint on stress distribution in the riser and expansion loop are studied, which are valuable for pipeline designers.  相似文献   

基于强跟踪性能的QEKF组合导航自适应滤波研究     

夏琳琳  赵琳  程建华 《测绘学报》2008,37(4):410-417

以低成本陆用航姿参考系统（AHRS）/GPS紧耦合系统为研究对象,建立了基于伪距、伪距率、航向角的组合观测数学模型。引入强跟踪滤波（STF）算法,利用渐消因子的作用,增强滤波器对状态快速变化的跟踪能力。同时,针对微惯性器件漂移过大的缺点,采用二阶EKF（QEKF）方法,通过对Hessian矩阵的求解,补偿系统观测方程线性化的二阶截断误差。仿真表明：STQEKF方法可高速准确地逼近系统非线性模型,实现陆地载体导航控制,在传感器精度有限的情况下,使姿态和位置的控制效果较标准EKF分别提高了约8.9%-38.2%和48.7%-54.4%  相似文献   

ET0计算公式的最新进展与普适性评估   总被引：5，自引：3，他引：2       下载免费PDF全文

苏春宏  陈亚新  徐冰 《水科学进展》2008,19(1)

通过对ET0计算公式研究进展的总结,分析了在世界上三个时期比较有代表性的计算蒸发腾发量(ET0)的主要公式:修正Penman(MP)公式、Penman-Monteith(PM)公式及标准ASCE-PM公式;以20世纪90年代末期和21世纪初期世界上最新的19个用Lysimeter实验值率定ET0计算值的实验成果为基础,对于不同气候条件下ET0计算方法的普适性分析评估认为:虽PM公式应用效果较好的地区较多,但也有不少地区效果欠佳,MP等公式在一部分地区较好,PM与MP公式并非普适性的,要特别关注标准ASCE-PM公式,总之,这类半理论(半经验)公式均有一定的地区性.仅通过MP、PM公式的计算比较,不能简单地评定哪种公式最优或哪种公式计算ET0值大(或值小),应针对不同地理及气候条件,要经Lysimeter的实验结果才能进行率定比较.文中也对今后研究提出相应建议,有助于ET0计算公式学科的深入研究.  相似文献   

基于非线性测度函数的改进属性识别模型在水质综合评价中的应用   总被引：2，自引：0，他引：2       下载免费PDF全文

张礼兵  金菊良  程吉林  王硕 《水科学进展》2008,19(3):422-427

线性测度函数的传统属性识别模型,对水质评价标准随机抽样的评价结果存在较大误差。为增加其对实测样本评价的可信度,提出了基于非线性属性测度函数的改进属性识别模型。均匀随机和正交设计两种抽样的评价试验显示,改进属性识别模型评价结果准确度明显好于传统模型,说明指标的属性测度函数对属性识别模型的综合评价结果有重要影响。太原市地下水水质的综合评价实例说明,由于非线性测度函数比线性测度函数能更好地描述评价指标的实际隶属度,故改进的属性识别模型具有更高的评价可信度,在水质综合评价中具有更广泛的适用性。  相似文献   

基于非等间距模型的建筑物沉降预测方法研究   总被引：6，自引：0，他引：6  

吴清海 《测绘科学》2008,33(3):59-61

该文基于实测资料进行建筑物沉降预测。在灰色模型和泊松曲线模型理论的基础上,引入对非等间距数列进行变换处理的方法,从而建立了非等间距预测模型。结合建筑物沉降监测资料进行分析比较,结果表明,两种预测方法均能较好地反映建筑物的沉降趋势。  相似文献   

Effect of Multipoint Heterogeneity on Nonlinear Transformations for Geological Modeling： Porosity-Permeability Relations Revisited     

J A Vargas-Guzmán 《中国地质大学学报(英文版)》2008,19(1):85-92

An analysis of statistical expected values for transformations is performed in this study to quantify the effect of heterogeneity on spatial geological modeling and evaluations. Algebraic transformations are frequently applied to data from logging to allow for the modeling of geological properties. Transformations may be powers, products, and exponential operations which are commonly used in well-known relations (e.g., porosity-permeability transforms). The results of this study show that correct computations must account for residual transformation terms which arise due to lack of independence among heterogeneous geological properties. In the case of an exponential porosity-permeability transform, the values may be positive. This proves that a simple exponential model back-transformed from linear regression underestimates permeability. In the case of transformations involving two or more properties, residual terms may represent the contribution of heterogeneous components which occur when properties vary together, regardless of a pair-wise linear independence. A consequence of power- and product-transform models is that regression equationswithin those transformations need corrections via residual cumulants. A generalization of this result isthat transformations of multivariate spatial attributes require multiple-point random variable relations. This analysis provides practical solutions leading to a methodology for nonlinear modeling using correct back transformations in geology.  相似文献   

Monotone Regression and Correction for Order Relation Deviations in Indicator Kriging     

韩燕  杨毅恒 《中国地质大学学报(英文版)》2008,19(1):93-96

The indicator kriging (IK) is one of the most efficient nonparametric methods in geo-statistics. The order relation problem in the conditional cumulative distribution values obtained by IK is the most severe drawback of it. The correction of order relation deviations is an essential and important part of IK approach. A monotone regression was proposed as a new correction method which could minimize the deviation from original quintiles value, although, ensuring all order relations.  相似文献