Web仓储中的单视图一致性

Web仓储系统使用物化视图的方法管理和维护Web数据,它可以给用户的查询和分析带来更快的效率,特别适合联机分析处理(OLAP)和决策支持。Web环境中数据更新非常频繁,为保持系统的时新性(freshness),需要不断刷新物化视图,在Web视图刷新的过程中,必须保持物化视图与基础数据之间的一致性(称为单视图一致性,SVC),否则系统中的数据就会产生错误,进而影响用户的正确使用,围绕这种单视图一致性,针对Web环境的特性,给出了相关保持算法,这些算法具有良好的Web环境适应性和伸缩性。     

Thermally induced mechanical and permeability changes around a nuclear waste repository—a far-field study based on equivalent properties determined by a discrete approach

A numerical investigation is conducted on the impacts of the thermal loading history on the evolution of mechanical response and permeability field of a fractured rock mass containing a hypothetical nuclear waste repository. The geological data are extracted from the site investigation results at Sellafield, England.A combined methodology of discrete and continuum approaches is presented. The results of a series of simulations based on the DFN–DEM (discrete fracture network–distinct element method) approach provide the mechanical and hydraulic properties of fractured rock masses, and their stress-dependencies. These properties are calculated on a representative scale that depends on fracture network characteristics and constitutive models of intact rock and fractures. In the present study, data indicate that the large scale domain can be divided into four regions with different property sets corresponding to the depth. The results derived by the DFN–DEM approach are then passed on to a large-scale analysis of the far-field problem for the equivalent continuum analysis.The large-scale far-field analysis is conducted using a FEM code, ROCMAS for coupled thermo-mechanical process. The results show that the thermal stresses of fractured rock masses vary significantly with mechanical properties determined at the representative scale. Vertical heaving and horizontal tensile displacement are observed above the repository. Observed stress and displacement fields also shows significant dependency on how the mechanical properties are characterized. The permeability changes induced by the thermal loading show that it generally decreases close to the repository. However, change of permeability is small, i.e., a factor of two, and thermally induced dilation of fracture was not observed. Note that the repository excavation effects were not considered in the study.The work presented in this paper is the result of efforts on a benchmark test (BMT2) within the international co-operative projects DECOVALEX III and BENCHPAR.     

Impact on Geologic Repository Usage from Limited Actinide Recycle in Pressurized Light Water Reactors

A project has been conducted as part of the U.S. Department of Energy Advanced Fuel Cycle Initiative to evaluate the impact of limited actinide recycling in light water reactors on the utilization of a geologic repository where loading of the repository is constrained by the decay heat of the emplaced materials. In this study, it was assumed that spent PWR fuel was processed, removing the uranium, plutonium, americium, and neptunium, along with the fission products cesium and strontium. Previous work had demonstrated that these elements were responsible for limiting loading in the repository based on thermal constraints. The plutonium, americium, and neptunium were recycled in a PWR, with process waste and spent recycled fuel being sent to the repository. The cesium and strontium were placed in separate storage for 100–300 years to allow for decay prior to disposal. The study examined the effect of single and mutliple recycles of the recovered plutonium, americium, and neptunium, as well as different processing delay times. The potential benefit to the repository was measured by the increase in utilization of repository space as indicated by the allowable linear loading in the repository drifts (tunnels). The results showed that limited recycling would provide only a small fraction of the benefit that could be achieved with repeated processing and recycling, as is possible in fast neutron reactors.     

高校机构知识库元数据质量控制问题研究

纵观国内外研究现状,专家们还未制定出比较系统的、普遍适用的质量控制机制。机构知识库中的元数据的质量控制,对于提高整个知识库的质量有着重要意义。提出通过引入OAI—PMH元数据收割协议和DC元数据来保证元数据的规范性,并分析挖掘元数据之间的内在关系,以实现元数据的提交智能化,通过丰富机构中基础数据的建设和加强平台控制功能,从而实现对元数据的质量控制。根据以上提出的元数据质量控制方法,针对高校机构知识库中元数据的特点,提出了具体的质量控制方案,验证了所提方法的可行性。     

基于BP的库存管理系统设计

企业过程(BP)是人与系统在业务领域的交互和协作,以完成特定的任务或功能。该文根据企业过程(BP)的建模方法,探讨了该建模方法在库存管理系统的应用,从而深刻的揭示了这类系统的内部组织单元的动态交互性,并为相应系统的设计提供了理论基础。     

Fuzzy-based nuclear analysis segregation model for distinguishing the properties of repository liquids and gas in gas storage

The geophysical well logging analysis is a major task of petroleum research and development, where petroleum oil (gas), transition petroleum layers, water layers, and dry-layer segments are precisely distinguished from each other. The resistivity of the particular oil and gas layers in developing countries is below or close to the water layers. As electrical properties show, the particular oil and gas layer of water layers is not legitimately recognizable. The features of oil and gas strata and their strong components are different in the investigative field from those of different petroleum fields. In this way, various techniques and thoughts ought to be utilized to comprehend the particular issues in the examination zone. A nuclear analysis–based segregation model for distinguishing the properties of repository liquids is worked by utilizing the crude pipeline and distilled unit of oil (gas) layers, transitional oil water layers, water layers, and dry layers using dynamic nonlinear fuzzy clustering model. With directly complex transformation models, reservoir fluids can be separated. The outcomes are analyzed with various model, and the proposed method shows promising outcomes.     

Preliminary and Scoping Analysis for Uncertainty of HLW Geologic Repository Performance with Multiple Canister Repository Model by Earth Simulator

An uncertainty analysis of repository performance has been made by the VR code, which incorporates interference effects of multiple canisters in a repository. A problem of the previous study with the VR code is that the number of connected canisters was determined arbitrarily. In this study, first, the probability distribution functions for the number of canisters connected by the flow-bearing fracture clusters have been determined by the FFDF code, and then uncertainty associated with the peak fractional release rate of ²³⁷Np to the far field resulting from uncertainties with the buffer sorption coefficient, solubility, and the number of connected canisters has been numerically evaluated by the Latin-Hypercube Sampling method. The effects of uncertainty with the total number of connected canisters become less important as the number increases because the radionuclide concentration saturates in downstream compartments. Uncertainty with the buffer sorption and solubility shows an important contribution to that with the nuclide release rate.     

Coupled hydro-mechanical analysis of expansive soils:Parametric identification and calibration

A methodology for identifying and calibrating the material parameters for a coupled hydro-mechanical problem is presented in this pape r.For validation purpose,a laboratory-based water infiltration test was numerically simulated using finite element method(FEM).The test was conducted using a self-designed column-type experimental device,which mimicked the wetting process of a candidate backfill material in a nuclear waste repository.The real-time measurements of key state variables(e.g.water content,relative humidity,temperature,and total stresses) were performed with the monitoring sensors along the height of cylindrical soil sample.For numerical simulation,the modified Barcelona Basic Model(BBM) along with soil-water retention model for compacted bentonite was used.It shows that the identified model parameters successfully captured the moisture migration process under an applied hydraulic gradient in a bentonite-based compacted soil sample.A comparison between the measured and predicted values of total stresses both in axial and lateral directions along with other state variables revealed that heterogeneous moisture content was distributed along the hydration-path,resulting in non-uniform stress-deformation characteristics of soil.     

A flexible content repository to enable a peer‐to‐peer‐based wiki

Wikis—being major applications of the Web 2.0—are used for a large number of purposes, such as encyclopedias, project documentation, and coordination, both in open communities and in enterprises. At the application level, users are targeted as both consumers and producers of dynamic content. Yet, this kind of peer‐to‐peer (P2P) principle is not used at the technical level being still dominated by traditional client–server architectures. What lacks is a generic platform that combines the scalability of the P2P approach with, for example, a wiki's requirements for consistent content management in a highly concurrent environment. This paper presents a flexible content repository system that is intended to close the gap by using a hybrid P2P overlay to support scalable, fault‐tolerant, consistent, and efficient data operations for the dynamic content of wikis. On the one hand, this paper introduces the generic, overall architecture of the content repository. On the other hand, it describes the major building blocks to enable P2P data management at the system's persistent storage layer, and how these may be used to implement a P2P‐based wiki application: (i) a P2P back‐end administrates a wiki's actual content resources. (ii) On top, P2P service groups act as indexing groups to implement a wiki's search index. Copyright © 2009 John Wiley & Sons, Ltd.     

Safety implication for an unsaturated zone nuclear waste repository

In this paper we shed some light on the safety of unsaturated zone nuclear geological repositories in the long run by examining the effect of physical and chemical processes that take place inside a partially failed nuclear waste container. Our analysis addresses the safety of the proposed nuclear repository at Yucca Mountain, which is intended to store high-level nuclear waste. Our study is independent of the US Department of Energy (DOE) analysis, which involves a number of complex computer codes and assumptions, and relies on the performance of an engineered barrier system. Our safety analysis could be applied in general to any geological repository designed to be in an unsaturated zone, since it is based on the geology, unsaturated zone location, and a key characteristic of the waste, heat production. This analysis shows that the radionuclide release from a partially failed waste container, stored in an unsaturated zone geological repository, is likely to be gradual and long delayed.