基于改进马尔可夫决策过程模型的多机协同航路规划研究

该文针对多无人机在复杂环境下执行作战任务易受环境威胁影响的问题,提出一种基于改进马尔可夫决策过程模型的多无人机航路规划算法。利用离散化雷达威胁信息,设计多无人机作战环境与状态空间数目;将目标点方位空间离散化,进而合理分配状态转移概率;将雷达威胁与马尔可夫决策过程模型相结合,在无模型均匀结构的报酬函数基础上引入非均匀结构雷达威胁模型,建立改进马尔可夫决策过程模型执行策略搜索,为多无人机进行飞行航路规划。仿真结果表明,该方法不仅能为多无人机快速规划出合理有效的飞行路径,还使得多无人机航路威胁代价和综合代价降低了25%,保障在复杂战场态势下无人机高效执行任务的安全性。     

基于马尔科夫生存模型与粒子群算法 的动态航路规划

针对未知情况下航路规划问题,采用动态规划策略保证飞机可以实时规划未来路径,并引入基于马尔科夫的生存模型来获取飞机的生存状态概率,从而评估生存代价,再综合任务、油耗、飞机机动性等作为粒子群算法的目标函数与约束条件,同时为了缓解生存与任务之间的矛盾,引入目标函数权重自适应策略.仿真实验证明,提出的动态航路规划策略是可行的,自适应权重也在一定程度上缓解了生存与任务之间的矛盾,同时将基于马尔科夫的生存模型应用于动态航路搜索中,能够更加直观地掌握每一时刻飞机的生存代价以及各状态的概率.     

基于蚁群算法的无人机航路规划

为了提高无人机(UAV)作战任务的成功率，在执行敌方防御区域内攻击任务前必需规划设计出高效的无人机飞行航路，保证无人机能够以最小的被发现概率及可接受的航程到达目标点。针对这一问题，对新近发展的蚁群算法进行了讨论，提出适用于航路规划的优化方法，并对无人机的攻击任务航路进行了仿真计算。仿真结果表明该方法是一种有效的航路规划方法。     

无人机航路规划问题初步研究

本文通过对无人机航路规划的研究,概括和总结了无人机航路规划问题的几个重要方面,构建了航路规划的基本框架。文章重点介绍了航路规划的约束条件、威胁模型的建立以及航路规划的算法,并对今后无人机航路规划的发展提出了展望。     

元胞蚁群算法的城市楼宇间无人机航路规划

近年来,城市环境中小型无人机越来越多,然而传统的航路规划算法通常将威胁简化,并不能很好地解决无人机在城市环境的航路规划问题。因此引入"元胞"定义飞行区间,对"数字元胞地图"以及"航路罚函数"进行定义,并利用蚁群算法进行航路规划,使其可以对任意不规则威胁进行规避。仿真对比实验表明,所提的基于元胞蚁群的算法可以在不对障碍模型进行简化的情况下进行合理规避,为无人机在城市环境中规划出一条安全可飞的航路。     

基于自适应遗传算法的无人机航路规划

在规划区域内随机产生一系列威胁点和相应威胁半径来量化无人机(UAV)任务环境,通过纵向剖分目标区,将航路点的表示由二维缩减到一维,采用实值编码以提高运算精度.针对遗传算法(GA)早收敛和收敛慢的问题,在交叉和变异中设计了自适应算子.计算仿真表明该控制算法能使无人机在复杂环境中回避威胁,快速选择最短路径,提高了规划效率.     

基于空间综合威胁体的无人机航迹规划方法研究

传统规划多数在平面中模拟威胁,难以真实表达威胁对无人机的影响范围,为了提高无人机飞行中的安全性和稳定性,在航迹规划中尽量规避周围环境的威胁,本文提出了一种基于空间综合威胁体的航迹规划方法,在目标区域内建立空间综合威胁体模型并进行分析及计算,最后进行航迹规划.空间综合威胁体的限制可有效减少待扩展节点的数量,提高航迹规划计算的效率.     

基于气象威胁场的无人机三维航迹规划

针对无人机航迹规划中气象威胁要素模糊性强、不确定性高等特点,提出了改进的BP神经网络的气象威胁度评估方法,对区域内气象威胁要素进行评估以建立表征气象威胁的气象威胁场。在所建立的气象威胁场上采用改进稀疏A*算法进行三维航迹规划,改进稀疏A*算法通过引入自适应操作提高了收敛速度以及效率。仿真结果表明,这种威胁评估方法可较为准确地评估区域内的气象威胁,改进稀疏A*算法能够准确、快速地在三维气象威胁场上寻找到最优航迹,具有一定的应用价值。     

基于改进双向A星和向量场直方图算法的无人机航路规划

现代无人机的行驶环境复杂多变,对无人机的航路规划不仅要求路径最短,同时还要满足实时性以应对突发威胁。提出一种离线规划和在线避障结合的航路规划方法。首先利用改进的双向A*算法对已知环境进行离线规划,并提出基于碰撞检测的动态步长和双向去除冗余点方法,在不影响路径精度的同时,缩短离线规划时间和路径。在无人机按照离线路径行驶过程中,当规划路径中出现突发威胁,利用VFH算法进行实时避障;对避障算法设置子目标,使无人机完成避障后能迅速回到离线轨迹,不影响全局路径的最优性.仿真实验表明,所提方法规划的路径长度短、耗时少,并能有效避开突发威胁,充分结合了双向A*算法路径最优和VFH算法的快速实时避障性的优点。     

基于并行粒子群和RL的无人机航路规划算法设计

设计了一种基于并行粒子群和RL(reinforcement learning,RL)的无人机航路规划方法.首先,定义了引入转角角度约束的航路规划的代价模型,然后,提出了一种基于RL中的Q-Learning算法的初始航路规划方法,将其作为粒子的初始位置,将粒子群划分为多个种群进行并行寻优,得到所有种群局部最优解,计算其最优值获取全局最优解;最后设计了基于并行粒子群和RL的无人机航路规划算法.仿真实验表明文中方法能实现复杂威胁情况下UCAC航路规划,具有较高的规划效率,且与其他方法相比,具有收敛速度快和全局寻优能力强的优点,具有较强的可行性和实用性.     

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.