Materialized view is a useful tool to cache data in data warehouse, data replication, data visualization and etc. However, view maintenance in peer data management systems (PDMSs) has received very little attention. In this paper, we propose a strategy to effectively maintain views in PDMSs. First, we present a hybrid peer architecture, in which peers prefer peer-to-peer architecture to super-peer based architecture. Then, we extend the definition of view and propose the peer view, local view and global view according to the requirements of applications. So a global view maintenance is became the maintenance of all related local views if join operations are confined in each local PDMS. Furthermore, we extend Mork's rules governing the use of updategrams and boosters and provide a push-based algorithm for view maintenance. Finally, we do extensive simulation experiments in our SPDMS. The simulation results show that the proposed view maintenance strategy has better performance than that of Mork's.
In recent years, China has adjusted the taxation policy on liquors several times, in a bid to support the outstanding and large-scale enterprises and limit the bad and small ones. However, this move has increased the tax bearing of liquor making enterprises. Therefore, it is of obvious significance to reinforce the taxation planning for liquor making enterprises. This paper describes the taxation planning for production and operation of liquors in various aspects to help those enterprises to reduce the cost of tax payment and increased their income from tax saving.
This paper explores the performance of Chinese small and medium sized enterprises (SMEs) on Business-to-Business (B2B) electronic marketplaces (EMs). Based on a content analysis of 155 cases of high performing online Chinese vendors, this paper explains the success of SME online B2B vendors within a Motivation-Capability framework. This first generation of SME B2B online vendors proved highly motivated to increase sales and developed a set of Internet leveraged organizational capabilities to compete online, including capabilities for online marketing, product innovation, eCommerce management, etc. This study differs from traditional wisdom that online marketplaces will render Guanxi (a Chinese cultural phenomenon defined as close and pervasive interpersonal relationships, Yang, 1994) irrelevant since online marketplaces are perceived to be impersonal. In fact, Guanxi still matters online, but it takes new forms. This research offers important managerial implications for B2B SME online vendors on how to leverage EMs for higher performance.
To simulate the nonlinear dynamical response of ship denfensive structure under explosions,the antiexplosion capacity of the multi-layer grillage structure was studied using the numerical method.Adopting the ALE algorithm of LS-DYNAt,he numerical method of multi-coupled surfaces was presented,which could be used to solve the problem of multi-cabin and multi-medium under explosions.Thent,he simulation of the nonlinear dynamical response process of the multi-layer defensive structure subjected to underwater contact explosions was conducted.The deformation of the model of three layers and two layers vacant cabins,one layer liquid cabin and with the changed water level was analyzed and compared with each other.The crevasse radius of plate as well as effective stresst,he pressure and deformation were described also.It reveals that the existence of liquid cabin improves the antiexplosion capacity of multi-layer plate-shell structure,and the proper reduction of the water in liquid cabin will not affect the antiexplosion capacity of ship defensive structure.
The damage of structure subjected to explosions is a very complex process with nonlinear character.Adopting the ALE algorithm of LS-DYNA,the numerical simulation of the dynamical response process of plate-shell structure subjected to two attacks was conducted.The deforming of three models where the distance of two dynamites was different subjected to two attacks simultaneously and successively was analyzed and the bulk of crevasse,the maximal effective stress and deformation were described.The two results were compared with each other.It was revealed that the longer the distance of two dynamites,the greater the destruction of the structure subjected to attacks simultaneously and successively.
Synthetic ropes are increasingly favored for use in offshore systems. Accurate predictions of the coupled hydrodynamic performance and structural response of offshore structures depends on a thorough understanding of the nonlinear characteristics of fiber materials. The objective of this study is to experimentally characterize the stiffness of a polyester mooring rope for a cylindrical floating production storage and offloading system. The quasi-static stiffness of the ropes and aged ropes after installation and the dynamic stiffness in various loading conditions were computed based on sub-rope tests following the guidelines from the American Bureau of Shipping. The quasi-static stiffness curves exhibited a linear decrease in values as the logarithm of the loading period (in minutes) increased. The dynamic stiffness was, in general, much higher than the quasi-static stiffness. The dynamic stiffness under various loading conditions revealed the complexities of the mechanical properties of polyester rope. Parameters such as the mean load, load amplitude, loading period, and loading cycles all had a notable impact. More tests are required to have a better understanding of their effects.
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