BP神经网络预测河湾最大冲刷深度

影响河湾凹岸最大冲刷深度的因素众多，而且这些因素的关系是非线性的．实现河湾最大冲刷深度预测的实质是建立一个非线性映射．实现这种映射的传统途径是在室内试验的基础上，采用量纲分析和多元回归的方式建立经验公式．根据BP（前馈）神经网络模型能逼近任何闭区间的连续函数的性质，在室内试验的基础上，尝试采用人工神经网络模型对河湾冲刷深度进行预测，并与经验公式的计算结果进行了比较．结果显示，BP神经网络能够更为准确地对河湾最大冲刷深度做出预测。     

基于ALE方法的射流冲刷砂土和黏土的数值计算

疏浚工程中常采用射流冲刷的方式辅助切削土壤,但面对不同土质时其效果差异较大。针对疏浚中常见的砂土和黏土两种土质,采用ALE(Arbitrary Lagrangian-Eulerian)方法对其射流冲刷过程进行了数值计算,通过实验验证了计算结果的有效性,比较了两种土质在射流冲刷下的坑深发展、冲坑形态和冲刷能耗。结果表明:两种土质的冲刷坑深在初始阶段均线性增长,相同冲刷速度下黏土的发展速度较慢;两种土质的冲刷坑形均具有相似性,冲刷黏土获得的坑形更为陡峭;随着目标坑深的增长,两种土质所需冲刷速度线性增加,获得相同冲坑深度时,黏土(剪切强度17 kPa)所需能耗达砂土的十多倍。     

基于ALE方法的射流冲刷砂土和粘土的数值计算

疏浚工程中常采用射流冲刷的方式辅助切削土壤,但面对不同土质时其效果差异较大。本文针对疏浚中常见的砂土和粘土两种土质,采用ALE（Arbitrary Lagrangian-Eulerian）方法对其射流冲刷过程进行了数值计算,通过实验验证了计算结果的有效性,比较了两种土质在射流冲刷下的坑深发展、冲坑形态和冲刷能耗。结果表明：两种土质的冲刷坑深在初始阶段均线性增长,相同冲刷速度下粘土的发展速度较慢;两种土质的冲刷坑形均具有相似性,冲刷粘土获得的坑形更为陡峭;随着目标坑深的增长,两种土质所需冲刷速度线性增加,获得相同冲坑深度时,粘土（剪切强度17kPa）所需能耗达砂土的十多倍。     

遗传算法BP神经网络在变形监测中的研究

介绍了BP神经网络和遗传算法的概念和基本理论,详细阐述了遗传算法优化的BP神经网络和BP神经网络这两种神经网络模型,深入分析了两种模型在基坑水平位移监测的数据预报,指出了遗传算法优化的BP神经网络模型具有更好的预测效果.     

小波变换集遗传算法神经网络的径流预测建模

为获得更精确的径流预报结果,利用dmey小波变换对径流时间序列分解为高频信号和低频信号,再使用遗传算法优化的BP神经网络分别对其进行预测,最后利用dmey小波逆变进行重构,以此建立径流总量预测模型。通过对柳江径流总量进行实例分析,并与遗传算法优化的神经网络模型、BP神经网络模型及传统的时间序列分析方法对比,该方法获得更准确的预测结果。研究结果表明该模型能充分反映径流时间序列趋势,预报稳定性好,预报准确率高,为径流时间序列预测提供一个有效建模方法。     

基岩冲刷的模型相似问题

对散粒体方法进行基岩冲刷模型并作了某些改进，利用冲刷坑深度与冲坑基岩粒径相关的公式对冲坑进行了模拟，结果表明模型材料的粒径可以用几何比尺换算，也可以用公式推导出的比尺进行选择，这样在选用模型材料粒径时，可放宽一些限制，使试验方便些，对冲刷坑下游的堆积体的高度进行了探讨，提出了相应的计算方法。     

某靶距下射流垂直冲刷坑深的实验研究

射流冲刷作为常用的清淤手段被广泛应用于疏浚等方面的工程实践。针对粗沙沙床条件下某靶距二维垂向淹没射流冲坑深度进行研究,观测动态冲坑深度随时间的发展,尤其关注动态冲坑深度在很短时间内发展规律,并探索射流速度对动态沙坑深度的影响,得出冲坑深度的经验公式。     

基于遗传算法的BP神经网络气液两相流持液率预测模型优化

基于遗传算法(Genetic Algorithm,GA)对BP(Back Propagation)神经网络模型的初始阈值及权值进行优化,弥补了单一BP网络模型预测气液两相流持液率时收敛速度慢随机性大等问题。为了对优化后的BP网络模型进行可行性验证,以倾斜管道为研究对象,对倾斜管道内气液两相流的持液率进行预测,并与前人获得的预测结果进行对比。结果显示:基于GA优化后的BP神经网络模型预测倾斜管道内气液两相流的持液率精度较高,且收敛速度较快。通过与倾斜管道气液两相流持液率的实际值对比得出,与传统的持液率预测公式相比,优化后的BP神经网络模型预测结果与实际值偏差较小,验证了本文优化模型的准确性及可行性。     

人工神经网络在潮汐短期预测中的研究

本文介绍了运用Matlab神经网络工具箱进行BP神经网络设计的基本方法与过程,并将BP网络模型引入到海洋潮汐预测领域,根据黄海海域某短期验潮站观测数值,构建并选用合适的BP神经网络建立了海洋潮汐短期预测的神经网络预报模型。计算结果表明,BP模型应用于潮汐预报具有较高的预测精度和良好的泛化能力,它为海洋潮汐预报工作提供了一种全新的思路和方法。     

应用改进BP神经网络进行用水量预测

针对工业用水量的特点，建立了改进的BP神经网络用水量预测模型，采用遗传算法对BP神经网络权系进行优化改进，改进的BP神经网络算法预测结果好于灰色理论预测和BP算法预测。以本溪市某供水厂用水量数据对改进的BP神经网络模型进行训练并预测，将其预测结果与灰色理论预测和BP神经网络预测结果进行比较分析，得出该方法用于供水系统用水量预测误差较小，同时克服了其他两种算法的缺陷。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-