MA模型参数求解与幅度谱重构信号问题关系

幅度谱重构信号问题已取得了许多成果,而MA参数模型的求解却比较困难．通过推导．建立了MA模型参数求解与幅度谱重构信号问题之间的关系,从而把这两个问题联系起来．这样,所有幅度谱重构信号问题的理论与算法均可应用于MA模型参数求解当中．     

模型未知非零和博弈问题的策略迭代算法

提出了一种在线积分策略迭代算法,用来求解内部非线性动力模型未知的双人非零和博弈问题.通过在控制策略和干扰策略中引入探测信号,从而避开了系统的模型信息,得到了一个求解非零和博弈的无模型的近似动态规划算法.该算法同步更新值函数、控制策略、扰动策略,并且最终得到收敛的策略权值.在算法实现过程中,使用4个神经网络分别近似两个值函数、控制策略和扰动策略,使用最小二乘法估计神经网络的未知参数.最后仿真结果验证了算法的有效性.     

基于块目标的频率步进连续波探地雷达压缩感知重建算法

压缩感知理论对于解决频率步进连续波探地雷达信号处理过程中存在的采样速率高、存储数据量大、信号处理时间长等问题具有重要意义. 针对雷达探测中块目标物体在探测区域不满足稀疏性的问题,提出一种适合块目标的压缩感知重构模型.利用某些稀疏正交基对块目标进行稀疏化处理使其满足稀疏性,将字典矩阵与稀疏矩阵结合形成适用于块目标物体的新观测矩阵,再通过压缩感知凸优化算法求解稀疏化系数,最后把该系数通过稀疏变换得到块目标的反射系数.通过实验仿真验证该方法的可行性,与未稀疏化处理的压缩感知重构模型相比具有更高的精度和分辨率.     

微生物间歇发酵比生长速率辨识及优化算法

根据微生物间歇发酵甘油生产1,3-丙二醇过程的特征及动态行为,建立了能够更好地描述微生物间歇发酵过程的含控制函数和参数的动力系统,证明了该系统的一些性质.以实验数据和计算值之间误差平方和最小为性能指标,建立了系统辨识模型.根据微生物生长特点,采用离散化方法将系统辨识模型转化为一个参数辨识问题.最后,构造了改进的粒子群算法求解.数值结果表明实验观测值和计算值之间的相对误差比已有研究结果降低了6%~16%,该系统能更好地模拟间歇发酵过程.     

广角X射线散射实验的散射角度修正

在同步辐射小角与广角联用X射线散射实验中由于原位实验设备的引入,探测器所获得的散射角并非真实的散射角,因此需要对探测值进行修正以获得真实的散射角.校正过程需要解决两个问题:一是要建立一个方程来完整描述实验中可能产生角度偏差的各种因素;另一个问题是寻找探测值和真实散射角的对应关系.本文以一维弧形探测器为原型建立了一种通用构造校正方程的方法,首先建立以样品中心为原点的几何模型方程,然后根据精度要求对方程进行泰勒近似,获得了简化的校正方程.通过模拟不同实验条件下的真实散射角与探测值,证实了校正方程的可行性,同时模拟结果也可以应用于解决寻峰的问题,最后选取La B6,Ce O2,Y2O3三种标准样品在不同实验条件下对校正精度进行了验证.根据探测器偏离样品中心的距离可分为三种模式(模式一模式二模式三),模式二、三的校正结果与理论分析相吻合,而模式一由于角度分辨较小以及视差效应等造成校正精度略大于理论预测值.这一方法同样适应于一维线性探测器、二维面形探测器等广角探测器.     

TV-MCP：一种新的脉冲噪音图像恢复方法

对于被脉冲噪音污染的图像恢复问题,广泛使用的TVL1模型会偏离数据获取模型和先验模型,特别是对高水平噪音.针对这个问题,基于MCP函数,提出了一种新的图像恢复模型,称之为TV-MCP模型,并给出了该模型的近似逼近方法,从理论上证明了该算法的全局收敛到TV-MCP模型的稳定点.对于近似逼近子问题的求解,采用交替方向方法求解.通过对多组图像在不同噪音污染水平下的数值仿真实验,验证了本文所提出的模型和方法的有效性.实验结果显示,TV-MCP模型比TVL1模型能够取得更好的恢复效果,尤其是在高噪音污染的图像恢复问题上,TV-MCP恢复图像的SNR值最高可以达到TVL1恢复图像的SNR值的两倍.     

气-液两相流界面迁移现象的数值模拟研究

借助于LevelSet函数,建立了气-液两相的统一控制方程组,并在交错网格中进行离散.用两种格式,即Superbee TVD格式和5阶WENO格式求解LevelSet函数的输运方程,用SIMPLER算法的思想对主流场控制方程的求解方法进行改进.数值实验结果表明,在求解LevelSet的控制方程时,5阶WENO方法比Superbee TVD格式的结果更准确;用改进的数值算法可成功实现对密度比大于1000/1的气-液两相流界面迁移问题的数值模拟.对几种典型大密度比气-液两相流问题的计算结果与实际问题的物理规律完全一致,验证了该方法的有效性和可靠性.     

开放式电阻抗成像建模及其仿真

为克服封闭式电阻抗成像电极位置不确定性引入的图像重构误差,采用固定电极阵列的开放式电阻抗成像(open electrical impedance tomography,OEIT)模型。将求解整个开放场域电磁场边值问题,近似转化为局部的虚拟场域。通过仿真实验选取有效边界参数和电极阵列结构。利用有限元法求解OEIT的正问题,采用一步牛顿法进行图像重构。实验结果表明OEIT能够探测到目标位置、区域以及电导率的变化,重构图像较清晰。OEIT在浅层体表具有较好的分辨率和定位准确度,有一定的临床应用价值。     

修正的迭代近似梯度投影算法在压缩感知中的应用

通过设计一种新的Hessian矩阵的近似,得到函数在当前迭代点的二次近似模型,并利用该模型与延迟策略得出一种新步长.结合新步长,提出一种求解压缩感知中稀疏信号重构问题的修正迭代近似梯度投影算法,并给出收敛性证明.实验结果表明,该算法不仅能较好地恢复原始信号中的非零元素,有效地重构信号,而且与经典算法相比,重构效率较高.     

电磁感应引信探测原理研究

建立了弹目交会时的电路模型,提出基于目标涡流互感和有效阻抗机理的电磁引信的探测原理.通过求解目标模型的边界条件和初始条件下的麦克斯韦方程,导出了目标涡流磁感应探测方程,设计了信号处理电路.实验结果表明,探测器的振荡频率在5.0～6.6 kHz时灵敏度较高,铁磁性金属与非铁磁性金属的目标特性有明显区别.实验结果和理论分析一致,该探测技术不仅能够识别金属目标的属性,而且具有较强的抗干扰能力.     

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.     

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.     

A computer generator for randomly layered structures

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

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.