基于贝叶斯推断的时变流场下污染源反演

对5个不同位置的污染源分别做污染物扩散数值模拟,将其计算结果作为测量浓度;利用伴随方程计算时变流场下传感器的模拟浓度。通过测量浓度和模拟浓度构造似然函数,基于贝叶斯推断计算了在时变流场下污染源参数的后验概率。结果表明：污染源参数反演的误差取决于测量浓度与模拟浓度之间的误差。当污染源与传感器的距离较远时,污染源参数的后验概率呈较宽的分布,反演结果具有较大的不确定性;当污染源与传感器距离较近时,反演结果的不确定性得到了显著的降低。此外,还讨论了反演污染源参数时,利用污染物扩散不同阶段的测量数据对反演效果的影响。发现利用扩散初始阶段的测量浓度反演源位置,可以得到比利用稳定阶段数据时更小的反演误差和后验概率标准差,但效果没有得到显著提升。     

基于MCMC方法的城区有毒气体扩散源反演

城区中有毒气体突发性泄漏时,需要快速对泄漏源进行定位和识别,以便科学预测气体的蔓延及其影响范围。利用基于Bayes推断理论的MCMC(Markov chain Monte Carlo)抽样方法,根据城市中分布的传感器测量信息和气体扩散数值计算模型,构造似然函数,对泄漏源的位置、强度进行反演。计算了这些参数和空间各点浓度的相关统计量,表明反演结果与泄漏源的真实参数十分吻合。此外,还讨论了传感器测量误差的概率分布对结果的影响。结果表明,误差概率会显著影响计算效果,概率分布越平坦,泄漏源反演信息的不确定度越大。     

基于MCMC方法的城区有毒气体扩散源反演

城区中有毒气体突发性泄漏时,需要快速对泄漏源进行定位和识别,以便科学预测气体的蔓延及其影响范围。利用基于Bayes推断理论的MCMC(Markov chain Monte Carlo)抽样方法,根据城市中分布的传感器测量信息,和气体扩散数值计算模型,构造似然函数,对泄漏源的位置、强度进行反演。通过计算这些参数和空间各点浓度的相关统计量,表明反演结果与泄漏源的真实参数十分吻合。此外,还讨论了传感器测量误差的概率分布对结果的影响。结果表明,误差概率会显著影响计算效果,概率分布越平坦,泄漏源反演信息的不确定度越大。     

基于伴随方程和MCMC方法的室内污染源反演模型研究

研究了室内污染物扩散后的源反演方法.通过数值求解浓度场的伴随方程,并结合传感器测量信息,构造似然函数;利用基于贝叶斯推断理论的MarkovChainMonte Carlo(MCMC)抽样方法,对污染源的位置、强度的后验概率进行计算,反演结果与污染源的真实参数吻合.该方法与传统的室内污染物反演方法相比,极大地降低了计算量.此外,还讨论了传感器性能对结果的影响,研究表明传感器误差概率分布越平坦,污染源反演信息的不确定度越大;而过低的测量灵敏度,则会导致反演结果呈现多个局部极值点的特性.     

盾构隧道收敛变形倾角感知布设优化研究

为了实现采用倾角感知盾构隧道的水平收敛,通过传感器的优化布设,构建运营期盾构隧道收敛变形实时监测系统.考虑隧道拱顶埋深、接头抗弯刚度比、地层抗力系数、地层侧压力系数及地面超载等参数的作用,针对管片变形和管片接头的影响,采用解析方法提出基于倾角传感隧道收敛的计算方法,并利用误差反演算法得到该算法下最优安装位置.建立单环盾构隧道结构三维精细化数值模型,采用正交实验法得到25组工况的最优布设点,与解析方法结果进行对比验证.基于现场168天连续的监测实测数据,采用二乘法比较不同方法计算的水平收敛变化值与激光监测结果的差值平方和,进行现场验证.结果表明:对于软土地区盾构隧道典型断面,最优布设点在120°附近(以拱顶为0°),当地层信息缺失时,可选用120°位置布设倾角传感器,典型地层条件下,解析解得到的误差不超过4%,数值解分析误差不超过10%,现场监测计算误差小于10%.在现场安装条件受限情况下,给出不同地层工况条件的安装位置偏移方案及其误差修正方法.最后,分析倾角和激光监测对应的71组现场数据,相比于其他3种方法,提出的隧道水平收敛计算方法得到的结果最接近激光测量值,其差值平方和最小,稳定性最优,可作为现场监测有效手段.     

密闭空间内的传感器最佳放置位置研究

提出了监测密闭容器内的气体浓度的两个最佳传感器放置位置标准,分别以气体浓度达到给定值的时间最短和在给定时间内气体浓度最大为目标建立了模型,并研究了其优化算法,优化算法运用有限元算法计算得出密闭空间内各点的气体浓度,根据记录的气体浓度值利用查找算法和排序算法进行优化计算,得出最佳传感器放置位置,最后给出了一个仿真应用实例,计算结果表明了这两个最佳传感器放置位置标准的合理性以及优化算法的准确性。     

一种基于泰勒级数多元变量展开模型定位算法

为了提高无线传感器网络节点定位精度,构建了增加未知节点与未知节点间的距离信息的泰勒级数多元变量展开定位模型.在对该算法的求解过程中,首先利用最大似然估计法得到未知节点的初始位置,再运用加权最小二乘法计算其最优值作为未知节点的估计位置.仿真测试了不同距离测量误差和已知节点数目对定位误差的影响,以及算法的累计分布函数.结果表明,该算法能够有效提高节点定位精度.     

有效监测时间和范围的一氧化碳传感器优化布置

为确定易自燃煤矿一氧化碳传感器的合理数量和位置,采用Dijkstra算法,求得任意两个节点间的最短路径,建立了邻接节点路径矩阵和邻接节点时间矩阵.规定一个有效监测时间,把邻接节点时间矩阵化为有效监测矩阵,从而得到各节点的有效监测分支集合.利用极小边支配集原理提出了最少全覆盖布点法,给出了一氧化碳传感器的优化布置方案.研究结果表明:有效监测时间不同,布点的数量、位置以及分支覆盖度也不同.     

关于严平稳过程的上穿过与最大值的几点注记

设ξ(t)(t≥0)是一严平稳过程,具有连续的样本函数,且ξ(t)的分布函数是连续的.令N_u(T)记对于水平u>0,在(0,T)内ξ(t)上穿过的数目.本文讨论E(N_u(T))的公式以及(?)P(M(T)≤u_n_T(x)),其中M(T)=sup{ξ(t)|0≤t≤T},而u_n_T(x)是单增函数.     

轮式移动机器人预定时间轨迹跟踪控制

在现有的轨迹跟踪控制中,跟踪误差的收敛时间通常与误差初始值有关,且关于非完整系统预定时间轨迹跟踪的控制方法很少.针对上述问题提出了一种使非完整轮式移动机器人系统可在预定时间跟踪上参考轨迹的控制方法.首先,通过坐标变换,将跟踪误差系统转变为一个由角度误差构成的一阶子系统和一个由位置误差构成的二阶子系统;然后,分别针对角度误差系统和位置误差系统设计机器人的角速度输入和速度输入,使得角度误差和位置误差在预定时间内收敛到零;最后,利用Lyapunov方法证明了所设计控制律的有效性.试验结果表明,提出的控制方法可使机器人在预定时间跟踪上参考信号,且实际收敛时间与理论计算时间相同,比现有的控制方法更加精确.     

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-