[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
Data deduplication, as a compression method, has been widely used in most backup systems to improve bandwidth and space efficiency. As data exploded to be backed up, two main challenges in data deduplication are the C...Data deduplication, as a compression method, has been widely used in most backup systems to improve bandwidth and space efficiency. As data exploded to be backed up, two main challenges in data deduplication are the CPU-intensive chunking and hashing works and the I/0 intensive disk-index access latency. However, CPU-intensive works have been vastly parallelized and speeded up by multi-core and many-core processors; the I/0 latency is likely becoming the bottleneck in data deduplication. To alleviate the challenge of I/0 latency in multi-core systems, multi-threaded deduplication （Multi-Dedup） architecture was proposed. The main idea of Multi-Dedup was using parallel deduplication threads to hide the I/0 latency. A prefix based concurrent index was designed to maintain the internal consistency of the deduplication index with low synchronization overhead. On the other hand, a collisionless cache array was also designed to preserve locality and similarity within the parallel threads. In various real-world datasets experiments, Multi-Dedup achieves 3-5 times performance improvements incorporating with locality-based ChunkStash and local-similarity based SiLo methods. In addition, Multi-Dedup has dramatically decreased the synchronization overhead and achieves 1.5-2 times performance improvements comparing to traditional lock-based synchronization methods.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
There has been increasing research in developing offline web applications. This paper concentrates on developing a new methodology for the online assessment web applications that could be used while offline. It is imp...There has been increasing research in developing offline web applications. This paper concentrates on developing a new methodology for the online assessment web applications that could be used while offline. It is important to retrieve the critical data collected during an examination without a provision of a backup mechanism. There is a need for an assessment system that can adapt to work uninterruptedly and without loss of critical data while there is intermittent intemet discontinuity. This paper describes architecture and implementation of online assessment system with offline capabilities. Online assessment system with offline capabilities will not interrupt examinee＇s experience while appearing for an assessment test if intemet connection is not available. A development methodology is designed and a compliant framework is implemented to enhance online assessment system with offline capabilities.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
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Project(IRT0725)supported by the Changjiang Innovative Group of Ministry of Education,China
文摘Data deduplication, as a compression method, has been widely used in most backup systems to improve bandwidth and space efficiency. As data exploded to be backed up, two main challenges in data deduplication are the CPU-intensive chunking and hashing works and the I/0 intensive disk-index access latency. However, CPU-intensive works have been vastly parallelized and speeded up by multi-core and many-core processors; the I/0 latency is likely becoming the bottleneck in data deduplication. To alleviate the challenge of I/0 latency in multi-core systems, multi-threaded deduplication （Multi-Dedup） architecture was proposed. The main idea of Multi-Dedup was using parallel deduplication threads to hide the I/0 latency. A prefix based concurrent index was designed to maintain the internal consistency of the deduplication index with low synchronization overhead. On the other hand, a collisionless cache array was also designed to preserve locality and similarity within the parallel threads. In various real-world datasets experiments, Multi-Dedup achieves 3-5 times performance improvements incorporating with locality-based ChunkStash and local-similarity based SiLo methods. In addition, Multi-Dedup has dramatically decreased the synchronization overhead and achieves 1.5-2 times performance improvements comparing to traditional lock-based synchronization methods.
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There has been increasing research in developing offline web applications. This paper concentrates on developing a new methodology for the online assessment web applications that could be used while offline. It is important to retrieve the critical data collected during an examination without a provision of a backup mechanism. There is a need for an assessment system that can adapt to work uninterruptedly and without loss of critical data while there is intermittent intemet discontinuity. This paper describes architecture and implementation of online assessment system with offline capabilities. Online assessment system with offline capabilities will not interrupt examinee＇s experience while appearing for an assessment test if intemet connection is not available. A development methodology is designed and a compliant framework is implemented to enhance online assessment system with offline capabilities.
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.
