By using wireless communication technology, when wired network of grassroots station is failure, wireless backup system of meteorological data transmission can automatically switch, and transmit the data at the statio...By using wireless communication technology, when wired network of grassroots station is failure, wireless backup system of meteorological data transmission can automatically switch, and transmit the data at the station with line fault to the destination by short message way. The system has simple operation and low operation cost, and transmission fault of real-time meteorological data due to line problem at the station can be effectively decreased. At present, the system has been tested successfully and put into business operation.展开更多
This paper presents a modeling method by stochastic Petri net for reliability analysis of phased mission system( PMS) with phase backup. The model consisting of petri nets,depicts the system behaviors of unit level,sy...This paper presents a modeling method by stochastic Petri net for reliability analysis of phased mission system( PMS) with phase backup. The model consisting of petri nets,depicts the system behaviors of unit level,system logic level and phase level. Guard functions of petri nets are used to avoid modeling complexity and make the model flexible to different reliability logical structures. It was shown that the time redundancy within phase and from phase backup for PMS can both be described by use of the proposed model.展开更多
This paper proposes a content addres sable storage optimization method, VDeskCAS, for desktop virtualization storage based disaster backup storage system. The method implements a blocklevel storage optimization, by em...This paper proposes a content addres sable storage optimization method, VDeskCAS, for desktop virtualization storage based disaster backup storage system. The method implements a blocklevel storage optimization, by employing the algorithms of chunking image file into blocks, the blockffmger calculation and the block dedup li cation. A File system in Use Space （FUSE） based storage process for VDeskCAS is also introduced which optimizes current direct storage to suit our content addressable storage. An interface level modification makes our system easy to extend. Experiments on virtual desktop image files and normal files verify the effectiveness of our method and above 60% storage volume decrease is a chieved for Red Hat Enterprise Linux image files. Key words： disaster backup; desktop virtualization; storage optimization; content addressable storage展开更多
In wide area backup protection of electric power systems, the prerequisite of protection device's accurate, fast and reliable performance is its corresponding fault type and fault location can be discriminated qui...In wide area backup protection of electric power systems, the prerequisite of protection device's accurate, fast and reliable performance is its corresponding fault type and fault location can be discriminated quickly and defined exactly. In our study, global information will be introduced into the backup protection system. By analyzing and computing real-time PMU measurements, basing on cluster analysis theory, we are using mainly hierarchical cluster analysis to search after the statistical laws of electrical quantities' marked changes. Then we carry out fast and exact detection of fault components and fault sections, and finally accomplish fault isolation. The facts show that the fault detection of fault component (fault section) can be performed successfully by hierarchical cluster analysis and calculation. The results of hierarchical cluster analysis are accurate and reliable, and the dendrograms of hierarchical cluster analysis are in intuition.展开更多
As the computer system has developed much in this highly information-oriented society, database security has become a very important problem and its backup strategies need to be made more efficiently and safety. The i...As the computer system has developed much in this highly information-oriented society, database security has become a very important problem and its backup strategies need to be made more efficiently and safety. The image copy method has been used as the most simple and dependable recovery mechanism for media failure. However, this method spends high overhead costs for massive data transmission and much processing time in the normal operation of the database. To cover such weak points, incremental and full backup methods are adopted before updated trucks reach a predetermined level. Moreover, when the number of full backup files exceeded a predetermined level, we stop incremental and full backups and switch it to the image copy. This paper applies cumulative damage model to backup of files in a database system, by putting damage shock by update, failure shock by database failure and damage by dumped files, and considers the tradeoff among overhead costs of image copy and incremental, full backup methods, and discusses analytically an optimal policy for the image copy backup interval. Finally, numerical examples are given in the case of Poisson process and exponential distributions.展开更多
This paper presents a practical pricing model for backup reserve and wheeling, which attains a balanced strategy that ensures perceived benefits to both the buyer and the seller. The model and the associated computeri...This paper presents a practical pricing model for backup reserve and wheeling, which attains a balanced strategy that ensures perceived benefits to both the buyer and the seller. The model and the associated computerized algorithm deal collectively with diverse issues, including： （1） fulfilling local firm real （and reactive） power demand requirements, （2） fulfilling local power reserve requirements, （3） buying firm real （and reactive） power from the grid, （4） buying reserve power from the grid, （5） exporting firm real （and reactive） power demand to remote load centers via the grid, （6） exporting reserve power via the grid, （7） wheeling of firm power demand to remote owned sites using the grid, and （8） wheeling reserve power to remote owned sites using grid. Practical implementation features of the computerized algorithms are also discussed with an illustrative case example.展开更多
Survivability is used to evaluate the ability of the satellite to complete the mission after failure,while the duration of maintaining performance is often ignored.An effective backup strategy can restore the constell...Survivability is used to evaluate the ability of the satellite to complete the mission after failure,while the duration of maintaining performance is often ignored.An effective backup strategy can restore the constellation performance timely,and maintain good network communication performance in case of satellite failure.From the perspective of network utility,the low Earth orbit(LEO)satellite constellation survivable graphical eva-luation and review technology(GERT)network with backup satel-lites is constructed.A network utility transfer function algorithm based on moment generating function and Mason formula is proposed,the network survivability evaluation models of on-orbit backup strategy and ground backup strategy are established.The survivable GERT model can deduce the expected mainte-nance time of LEO satellite constellation under different fault states and the network utility generated during the state mainte-nance period.The case analysis shows that the proposed surviv-able GERT model can consider the satellite failure rate,backup satellite replacement rate,maneuver control replacement ability and life requirement,and effectively determine the optimal sur-vivable backup strategy for LEO satellite constellation with limi-ted resources according to the expected network utility.展开更多
[Objective] This study was to construct VPDN-based 3G wireless meteorological information transmission system, in order to achieve the backup transmission of real-time meteorological services in all levels of meteorol...[Objective] This study was to construct VPDN-based 3G wireless meteorological information transmission system, in order to achieve the backup transmission of real-time meteorological services in all levels of meteorological stations. [Method] The current situations and business requirements of municipal meteorological networks are analyzed, putting forward the idea of backup routes that using VPDN-based 3G wireless meteorological information transmission system as the ground transmission line. And the network structure, operation mode and the system implementation are described in detail. [Result] VPDN-based 3G wireless meteorological information transmission system realizes the backup of ground line. Compared with the Modem dial-up, it is more stable and with faster transferring speed. With the rapid development of communication technology and computer technology, the information transmission system will be more efficient and stable, and will play a greater role in meteorological information transmission. [Conclusion] With the continuous development of modern meteorology, various types of meteorological data increase, presenting higher demand for the meteorological information transmission system. The established VPND-based 3G wireless meteorological information transmission system of this study provides a solution for backup transmission of real-time meteorological services.展开更多
In the context of real-time fault-tolerant scheduling in multiprocessor systems, Primary-backup scheme plays an important role. A backup copy is always preferred to be executed as passive backup copy whenever possible...In the context of real-time fault-tolerant scheduling in multiprocessor systems, Primary-backup scheme plays an important role. A backup copy is always preferred to be executed as passive backup copy whenever possible because it can take the advantages of backup copy de-allocation technique and overloading technique to improve schedulability. In this paper, we propose a novel efficient fault-tolerant ratemonotonic best-fit algorithm efficient fault-tolerant rate-monotonic best-fit （ERMBF） based on multiprocessors systems to enhance the schedulability. Unlike existing scheduling algorithms that start scheduling tasks with only one processor. ERMBF pre-allocates a certain amount of processors before starting scheduling tasks, which enlarge the searching spaces for tasks. Besides, when a new processor is allocated, we reassign the task copies that have already been assigned to the existing processors in order to find a superior tasks assignment configuration. These two strategies are all aiming at making as many backup copies as possible to be executed as passive status. As a result, ERMBF can use fewer processors to schedule a set of tasks without losing real-time and fault-tolerant capabilities of the system. Simulation results reveal that ERMBF significantly improves the schedulability over existing, comparable algorithms in literature.展开更多
This paper describes a method for building hot snapshot copy based on windows-file system （HSCF）. The architecture and running mechanism of HSCF are discussed after giving a comparison with other on-line backup tecb...This paper describes a method for building hot snapshot copy based on windows-file system （HSCF）. The architecture and running mechanism of HSCF are discussed after giving a comparison with other on-line backup tecbnology. HSCF, based on a file system filter driver, protects computer data and ensures their integrity and consistency with following three steps： access to open files, synchronization and copy on-write. Its strategies for improving system performance are analyzed including priority setting, incremental snapshot and load balance. HSCF is a new kind of snapshot technology to solve the data integrity and consistency problem in online backup, which is different from other storage-level snapshot and Open File Solution.展开更多
On the basis of integrating two-dimensional varying thickness finite elementmethod with hybrid genetic algorithm, a precise model was developed to design ideal backup rollcontour (Varying Contact Backup Roll, in short...On the basis of integrating two-dimensional varying thickness finite elementmethod with hybrid genetic algorithm, a precise model was developed to design ideal backup rollcontour (Varying Contact Backup Roll, in short VCR) in finishing rains of hot rolling rapidly andefficaciously. Additionally, a lot of good actual effects of VCR, such as evident improvement ofprofile and flatness of strip, remarkable decrease of roll consume, excellent maneuverability andmaintenance, and so on, were validated by long-term industrial tests in hot rolling strip plant ofWuhan Iron and Steel Group Corporation (WISCO).展开更多
Service function chains(SFC)mapping takes the responsibility for managing virtual network functions(VNFs).In SFC mapping,existing solutions duplicate VNFs with redundant instances to provide high availability in respo...Service function chains(SFC)mapping takes the responsibility for managing virtual network functions(VNFs).In SFC mapping,existing solutions duplicate VNFs with redundant instances to provide high availability in response to failures.However,as a compromise,these solutions result in high resource consumption due to device maintenance.In this paper,we propose a novel method named dynamic backup sharing(DBS)that allows SFCs to dynamically share backups to reduce resource consumption.DBS formulates the problem of sharing backups among different VNFs as an integer linear programming(ILP).Thereafter,we design a novel online algorithm based on dynamic programming to solve the problem.The experimental results indicate that DBS outperforms state-ofthe-art works by reducing resource consumption and improving the number of accepted requests.展开更多
文摘By using wireless communication technology, when wired network of grassroots station is failure, wireless backup system of meteorological data transmission can automatically switch, and transmit the data at the station with line fault to the destination by short message way. The system has simple operation and low operation cost, and transmission fault of real-time meteorological data due to line problem at the station can be effectively decreased. At present, the system has been tested successfully and put into business operation.
基金Nationd Natural Science Foundation of China(No.71671185)
文摘This paper presents a modeling method by stochastic Petri net for reliability analysis of phased mission system( PMS) with phase backup. The model consisting of petri nets,depicts the system behaviors of unit level,system logic level and phase level. Guard functions of petri nets are used to avoid modeling complexity and make the model flexible to different reliability logical structures. It was shown that the time redundancy within phase and from phase backup for PMS can both be described by use of the proposed model.
基金the Hi-tech Research and Development Program of China，the National Natural Science Foundation of China，the Beijing Natural Science Foundation，the Fundamental Research Funds for the Central Universities，the Fund of the State Key Laboratory of Software Development Environment
文摘This paper proposes a content addres sable storage optimization method, VDeskCAS, for desktop virtualization storage based disaster backup storage system. The method implements a blocklevel storage optimization, by employing the algorithms of chunking image file into blocks, the blockffmger calculation and the block dedup li cation. A File system in Use Space （FUSE） based storage process for VDeskCAS is also introduced which optimizes current direct storage to suit our content addressable storage. An interface level modification makes our system easy to extend. Experiments on virtual desktop image files and normal files verify the effectiveness of our method and above 60% storage volume decrease is a chieved for Red Hat Enterprise Linux image files. Key words： disaster backup; desktop virtualization; storage optimization; content addressable storage
文摘In wide area backup protection of electric power systems, the prerequisite of protection device's accurate, fast and reliable performance is its corresponding fault type and fault location can be discriminated quickly and defined exactly. In our study, global information will be introduced into the backup protection system. By analyzing and computing real-time PMU measurements, basing on cluster analysis theory, we are using mainly hierarchical cluster analysis to search after the statistical laws of electrical quantities' marked changes. Then we carry out fast and exact detection of fault components and fault sections, and finally accomplish fault isolation. The facts show that the fault detection of fault component (fault section) can be performed successfully by hierarchical cluster analysis and calculation. The results of hierarchical cluster analysis are accurate and reliable, and the dendrograms of hierarchical cluster analysis are in intuition.
文摘As the computer system has developed much in this highly information-oriented society, database security has become a very important problem and its backup strategies need to be made more efficiently and safety. The image copy method has been used as the most simple and dependable recovery mechanism for media failure. However, this method spends high overhead costs for massive data transmission and much processing time in the normal operation of the database. To cover such weak points, incremental and full backup methods are adopted before updated trucks reach a predetermined level. Moreover, when the number of full backup files exceeded a predetermined level, we stop incremental and full backups and switch it to the image copy. This paper applies cumulative damage model to backup of files in a database system, by putting damage shock by update, failure shock by database failure and damage by dumped files, and considers the tradeoff among overhead costs of image copy and incremental, full backup methods, and discusses analytically an optimal policy for the image copy backup interval. Finally, numerical examples are given in the case of Poisson process and exponential distributions.
文摘This paper presents a practical pricing model for backup reserve and wheeling, which attains a balanced strategy that ensures perceived benefits to both the buyer and the seller. The model and the associated computerized algorithm deal collectively with diverse issues, including： （1） fulfilling local firm real （and reactive） power demand requirements, （2） fulfilling local power reserve requirements, （3） buying firm real （and reactive） power from the grid, （4） buying reserve power from the grid, （5） exporting firm real （and reactive） power demand to remote load centers via the grid, （6） exporting reserve power via the grid, （7） wheeling of firm power demand to remote owned sites using the grid, and （8） wheeling reserve power to remote owned sites using grid. Practical implementation features of the computerized algorithms are also discussed with an illustrative case example.
基金This work was supported by the National Natural Science Foundation of China(72271124,52232014,72071111,71801127,71671091).
文摘Survivability is used to evaluate the ability of the satellite to complete the mission after failure,while the duration of maintaining performance is often ignored.An effective backup strategy can restore the constellation performance timely,and maintain good network communication performance in case of satellite failure.From the perspective of network utility,the low Earth orbit(LEO)satellite constellation survivable graphical eva-luation and review technology(GERT)network with backup satel-lites is constructed.A network utility transfer function algorithm based on moment generating function and Mason formula is proposed,the network survivability evaluation models of on-orbit backup strategy and ground backup strategy are established.The survivable GERT model can deduce the expected mainte-nance time of LEO satellite constellation under different fault states and the network utility generated during the state mainte-nance period.The case analysis shows that the proposed surviv-able GERT model can consider the satellite failure rate,backup satellite replacement rate,maneuver control replacement ability and life requirement,and effectively determine the optimal sur-vivable backup strategy for LEO satellite constellation with limi-ted resources according to the expected network utility.
文摘[Objective] This study was to construct VPDN-based 3G wireless meteorological information transmission system, in order to achieve the backup transmission of real-time meteorological services in all levels of meteorological stations. [Method] The current situations and business requirements of municipal meteorological networks are analyzed, putting forward the idea of backup routes that using VPDN-based 3G wireless meteorological information transmission system as the ground transmission line. And the network structure, operation mode and the system implementation are described in detail. [Result] VPDN-based 3G wireless meteorological information transmission system realizes the backup of ground line. Compared with the Modem dial-up, it is more stable and with faster transferring speed. With the rapid development of communication technology and computer technology, the information transmission system will be more efficient and stable, and will play a greater role in meteorological information transmission. [Conclusion] With the continuous development of modern meteorology, various types of meteorological data increase, presenting higher demand for the meteorological information transmission system. The established VPND-based 3G wireless meteorological information transmission system of this study provides a solution for backup transmission of real-time meteorological services.
基金Supported by the National Basic Reseach Program of China (973 Program 2004 CB318200)
文摘In the context of real-time fault-tolerant scheduling in multiprocessor systems, Primary-backup scheme plays an important role. A backup copy is always preferred to be executed as passive backup copy whenever possible because it can take the advantages of backup copy de-allocation technique and overloading technique to improve schedulability. In this paper, we propose a novel efficient fault-tolerant ratemonotonic best-fit algorithm efficient fault-tolerant rate-monotonic best-fit （ERMBF） based on multiprocessors systems to enhance the schedulability. Unlike existing scheduling algorithms that start scheduling tasks with only one processor. ERMBF pre-allocates a certain amount of processors before starting scheduling tasks, which enlarge the searching spaces for tasks. Besides, when a new processor is allocated, we reassign the task copies that have already been assigned to the existing processors in order to find a superior tasks assignment configuration. These two strategies are all aiming at making as many backup copies as possible to be executed as passive status. As a result, ERMBF can use fewer processors to schedule a set of tasks without losing real-time and fault-tolerant capabilities of the system. Simulation results reveal that ERMBF significantly improves the schedulability over existing, comparable algorithms in literature.
基金Supported by the National Natural Science Foun-dation of China (60473023) National Innovation Foundation forSmall Technology Based Firms(04C26214201280)
文摘This paper describes a method for building hot snapshot copy based on windows-file system （HSCF）. The architecture and running mechanism of HSCF are discussed after giving a comparison with other on-line backup tecbnology. HSCF, based on a file system filter driver, protects computer data and ensures their integrity and consistency with following three steps： access to open files, synchronization and copy on-write. Its strategies for improving system performance are analyzed including priority setting, incremental snapshot and load balance. HSCF is a new kind of snapshot technology to solve the data integrity and consistency problem in online backup, which is different from other storage-level snapshot and Open File Solution.
基金[The word was financially supported by "973" key foundation of China (No. 95-527-01-02-04). ]
文摘On the basis of integrating two-dimensional varying thickness finite elementmethod with hybrid genetic algorithm, a precise model was developed to design ideal backup rollcontour (Varying Contact Backup Roll, in short VCR) in finishing rains of hot rolling rapidly andefficaciously. Additionally, a lot of good actual effects of VCR, such as evident improvement ofprofile and flatness of strip, remarkable decrease of roll consume, excellent maneuverability andmaintenance, and so on, were validated by long-term industrial tests in hot rolling strip plant ofWuhan Iron and Steel Group Corporation (WISCO).
基金This work is supported by the National Key R&D Program of China(2018YFB1800601)the Key R&D Program of Zhejiang Province(2021C01036,2020C01021)the Fundamental Research Funds for the Central Universities(Zhejiang University NGICS Platform:ZJUNGICS2021021).
文摘Service function chains(SFC)mapping takes the responsibility for managing virtual network functions(VNFs).In SFC mapping,existing solutions duplicate VNFs with redundant instances to provide high availability in response to failures.However,as a compromise,these solutions result in high resource consumption due to device maintenance.In this paper,we propose a novel method named dynamic backup sharing(DBS)that allows SFCs to dynamically share backups to reduce resource consumption.DBS formulates the problem of sharing backups among different VNFs as an integer linear programming(ILP).Thereafter,we design a novel online algorithm based on dynamic programming to solve the problem.The experimental results indicate that DBS outperforms state-ofthe-art works by reducing resource consumption and improving the number of accepted requests.
