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The global skyline, as an important variant of the skyline, has been widely applied in multi-criteria decision making, business planning and data mining. In this paper, we extend our early work and propose the maintenance methods to process the subspace global skyline (SGS) queries in dynamic databases. In the previous work, we proposed the index structure RB-tree, which can effectively manage the data to accelerate the subspace global skyline calculation. Also, the basic single SGS algorithm based on RB-tree (SSRB) and the optimized single SGS algorithm (OSSRB) were proposed to process a single SGS query. In addition, the multiple SGS algorithm (MSRB) was proposed to calculate multiple SGS queries by sharing the scan spaces of different queries. In this paper, we design some data structures and propose the maintenance approaches of SSRB, OSSRB and MSRB to cope with updates that happen to data sets. Thus our extended algorithms can be adopted for dynamic data sets. Finally, the experimental results show that the proposed algorithms OSSRB and MSRB have good performance to process SGS queries and they can be easily maintained with dynamic datasets. 相似文献
104.
Universal Access in the Information Society - Helping blind people to build cognitive maps of an environment is one of the aims of several assistive systems. In order to evaluate such assistive... 相似文献
105.
Klaus Julisch Christophe Suter Thomas Woitalla Olaf Zimmermann 《Computers & Security》2011,30(6-7):410-426
System and process auditors assure – from an information processing perspective – the correctness and integrity of the data that is aggregated in a company’s financial statements. To do so, they assess whether a company’s business processes and information systems process financial data correctly. The audit process is a complex endeavor that in practice has to rely on simplifying assumptions. These simplifying assumptions mainly result from the need to restrict the audit scope and to focus it on the major risks. This article describes a generalized audit process. According to our experience with this process, there is a risk that material deficiencies remain undiscovered when said simplifying assumptions are not satisfied. To address this risk of deficiencies, the article compiles thirteen control patterns, which – according to our experience – are particularly suited to help information systems satisfy the simplifying assumptions. As such, use of these proven control patterns makes information systems easier to audit and IT architects can use them to build systems that meet audit requirements by design. Additionally, the practices and advice offered in this interdisciplinary article help bridge the gap between the architects and auditors of information systems and show either role how to benefit from an understanding of the other role’s terminology, techniques, and general work approach. 相似文献
106.
German Shegalov Michael Gillmann Gerhard Weikum 《The VLDB Journal The International Journal on Very Large Data Bases》2001,10(1):91-103
Advanced e-services require efficient, flexible, and easy-to-use workflow technology that integrates well with mainstream
Internet technologies such as XML and Web servers. This paper discusses an XML-enabled architecture for distributed workflow
management that is implemented in the latest version of our Mentor-lite prototype system. The key asset of this architecture
is an XML mediator that handles the exchange of business and flow control data between workflow and business-object servers
on the one hand and client activities on the other via XML messages over http. Our implementation of the mediator has made
use of Oracle's XSQL servlet. The major benefit of the advocated architecture is that it provides seamless integration of
client applications into e-service workflows with scalable efficiency and very little explicit coding, in contrast to an earlier,
Java-based, version of our Mentor-lite prototype that required much more code and exhibited potential performance problems.
Received: 30 October 2000 / Accepted: 19 December 2000 Published online: 27 April 2001 相似文献
107.
City councils hold meetings several times a week. There is a need for computer support at certain meetings. This paper examines the potential for group support systems for use in city council meetings and shows in what ways they can be helpful in pre-meeting and post-meeting activities. The study is based on 17 computer-supported city council meetings, carried out in Stuttgart, Kornwestheim and other cities as part of the Cuparla Project between 1996 and 1998. Three of these meetings are described in the paper as brief case studies. Following this, all 17 meeting sequences are evaluated and analysed. Guidelines have been developed from the results of the study for the introduction of group support systems in city council meetings. 相似文献
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109.
Gottfried Zimmermann Gregg Vanderheiden 《Universal Access in the Information Society》2008,7(1-2):117-128
Accessible design principles should permeate virtually all phases of the application development cycle, using existing “best practices of software engineering” for accessibility purposes. This paper proposes a methodology for accessible design and testing that includes proven tools of software engineering, namely use cases and scenarios, to capture functional requirements. Guidelines developed through user testing and heuristics are made real using personas to exemplify accessibility requirements, reflecting a diversity of user capabilities and use contexts. For implementation and testing, test cases containing accessibility checkpoints are generated, based on the guidelines. Complementary to this methodology, expert reviews and user testing should be conducted for evaluation of the developed products and further refinement of the development process. 相似文献
110.
Valves for autonomous capillary systems 总被引:2,自引:1,他引:1
Autonomous capillary systems (CSs) are microfluidic systems inside which liquids move owing to capillary forces. CSs can in
principle bring the high-performances of microfluidic-based analytical devices to near patient and environmental testing applications.
In this paper, we show how wettable capillary valves can enhance CSs with novel functionalities, such as delaying and stopping
liquids in microchannels. The valves employ an abruptly changing geometry of the flow path to delay a moving liquid filling
front in a wettable microchannel. We show how to combine delay valves with capillary pumps, prevent shortcuts of liquid along
the corners of microfluidic channels, stop liquids filling microchannels from a few seconds to over 30 min, trigger valves
using two liquid fronts merging, and time a liquid using parallel microfluidic paths converging to a trigger valve. All together,
these concepts should add functionality to passive microfluidic systems without departing from their initial simplicity of
use.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献