星载计算机系统高优先级恢复容错调度算法

为了在星载异构容错计算机上调度星载任务，在给出了星载计算机系统的容错调度模型的基础上，提出了一种星载计算机系统高优先级恢复容错调度算法（OHFSA），该算法通过引进可靠性代价量化了容错系统在维护容错调度时所需要的开销，并在调度过程中充分考虑了容错调度的实时性和低可靠性代价．同时，采用高优先级恢复机制可及时响应紧急时限下的恢复任务，从而提高了星载任务的整体实时性能．实验验证表明，OHFSA随着计算时间的增加，其所需的可靠性代价也相应增大．仿真结果表明，在任务负载不断增加的情况下，OHFSA的执行时间比目前算法减少20%～30%，特别是在恢复任务优先级比其主任务提高1个级别时，响应时间可减少近8．7%．     

基于双优先级队列的异构分布式控制系统容错调度算法

在对分布式控制系统进行分析的基础上,给出了任务模型和处理器模型.为了调度多种实时性的任务,提出了双优先级队列调度算法,用于调度每个处理器上的任务.该算法设置2个优先级队列,其中高优先级队列用于调度实时任务,低优先级队列用于调度非实时任务,高优先级队列中的任务可抢占低优先级队列中的任务.在此基础上,采用版本复制技术使系统具有容错能力,并分析了任务的容错可调度条件.基于此,采用首次适应的启发式任务分配策略,将任务分配到各个处理器上,在确保任务容错可调度的条件下使处理器负载均衡.仿真结果表明所提出的算法是有效的.     

嵌入式系统动态策略任务调度算法

针对嵌入式实时系统任务调度问题,讨论综合截止期和关键度两种特征参数的任务调度策略。引入动态策略的概念,采用任务分组优先级分段的方式,通过判断函数的判断动态选择调度策略,利用可达截止期优先降低任务错失率,关键保证重要任务的调度成功率,提出一种动态截止期-关键度调度算法。理论分析和仿真实验表明,在非过载的情况下该算法可以达到与可达截止期优先相当的调度性能;在过载的情况下,相比截止期优先和固定优先级算法具有更好的调度性能,能够有效地保证关键实时任务的成功调度。     

分布式实时系统的组资格成员算法

从满足分布实时系统容错要求的角度出发 ,基于 TDM广播网 ,提出了分布式实时系统中的一个处理机组资格成员算法 ;只要系统中故障处理机数目不超过半数 ,该算法就能在其发生周期之后最多不到 2个周期的时间内检测出系统中的处理机故障 ,并维持一个正确的处理机状态视图 ;对算法的正确性给予了证明 .     

一种新的多处理器系统实时容错算法

实时多处理器容错算法是实时系统研究领域的一个重要课题.提出了一个动态处理非周期实时任务的容错算法.提出了对待实时任务的基、副版本采用不同的处理器分配策略.对于基版本,尽量提前任务的开始时间;对于副版本,尽量延迟任务的开始时间.通过实验模拟研究了算法的性能.实验表明,算法调度的成功率跟处理器个数、任务数以及任务计算时间有关.与采用单一处理器分配策略相比,具有较高的调度成功率.     

支持优先级约束任务的容错调度算法

为了解决异构分布式系统中可靠调度问题,提出一种考虑处理机链路通信竞争的,支持优先级约束任务的容错调度(FSPCT)算法。该算法使用通信竞争模型描述处理机之间通信,在备份成本最小化和备份任务最早完成之间寻求平衡点。对主副版本任务的最早开始时间进行分析,并限定了所执行的处理机,在处理机出现故障后任务可以顺利执行。实验结果表明FSPCT算法的综合性能优于现有一些算法。     

WebitOS中动态优先级调度机制及EDF算法的实现

在实时系统中,相对于静态优先级调度机制而言,动态优先级调度机制因其可以为每个任务的各个作业设置不同的绝对时限而更好地反映了实时系统对于所调度的各个任务的时限要求.基于最早时限优先(earliest-deadline-first EDF)算法的高可调度利用率,在WebitOS实时操作系统中设计并实现了动态优先级调度机制,并且提出了一种早期丢弃规则.实验结果表明,该规则提高了EDF算法在超载情况下的整体调度性能.     

多处理机系统的高效实时容错调度算法

在容错调度算法副版本后调度算法的基础上,提出一种高效实时容错调度算法。对于具有容错需求的实时任务而言,由实进容错调度算法所产生的调度可保证在多处理机实时系统中一个处理机失效时,实时任务仍然可在截止时限内完成。在ＥＢＫＣＬ算法中,如何两个实时任务的基版本分配在不同的处理机Ｐｉ和Ｐｊ上,且这两个实时任务的副版本被调度到同一个处理机Ｐ’上,则两个副版本之间允许有时间上的重叠。     

基于桶排序的EDF调度算法优化

EDF调度算法在系统过载的情况下,就不能有效地实时调度系统中的所有任务,使任务的截止期错失率非常高.利用桶排序算法,将实时系统中任务按不同优先级等级分组排序,使得高优先级等级任务组中的任务优先被调度执行;对于其他低优先级等级任务组中的任务,根据资源利用率动态调整它们的优先级等级,从而降低实时系统的任务截止期错失率.仿真实验表明,优化后的EDF调度算法的截止期错失率,明显比优化前低,说明基于桶排序的EDF调度算法的实时任务截止期错失率比EDF调度算法低.     

无线网络中的动态数据复制算法研究

数据复制是实现容错的一种重要方法。介绍了有线网络中的静态与动态数据复制算法。提出了无线网络中的动态数据复制算法。该算法能根据用户信息，动态调整数据复制的数目及放置位置。实验结果表明，新的算法在读取成功率与平均响应时间方面有明显的提高.     

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.     

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)

正~~     

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).     

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.     

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.