A DMVOCC-MVDA （distributed multiversion optimistic concurrency control with multiversion dynamic adjustment） protocol was presented to process mobile distributed real-time transaction in mobile broadcast environment...A DMVOCC-MVDA （distributed multiversion optimistic concurrency control with multiversion dynamic adjustment） protocol was presented to process mobile distributed real-time transaction in mobile broadcast environments. At the mobile hosts, all transactions perform local pre-validation. The local pre-validation process is carried out against the committed transactions at the server in the last broadcast cycle. Transactions that survive in local pre-validation must be submitted to the server for local final validation. The new protocol eliminates conflicts between mobile read-only and mobile update transactions, and resolves data conflicts flexibly by using multiversion dynamic adjustment of serialization order to avoid unnecessary restarts of transactions. Mobile read-only transactions can be committed with no-blocking, and respond time of mobile read-only transactions is greatly shortened. The tolerance of mobile transactions of disconnections from the broadcast channel is increased. In global validation mobile distributed transactions have to do check to ensure distributed serializability in all participants. The simulation results show that the new concurrency control protocol proposed offers better performance than other protocols in terms of miss rate, restart rate, commit rate. Under high work load （think time is ls） the miss rate of DMVOCC-MVDA is only 14.6%, is significantly lower than that of other protocols. The restart rate of DMVOCC-MVDA is only 32.3%, showing that DMVOCC-MVDA can effectively reduce the restart rate of mobile transactions. And the commit rate of DMVOCC-MVDA is up to 61.2%, which is obviously higher than that of other protocols.展开更多
The relation between the implementation time of small reactor and its market was studied if small reactor could be implemented to be utilized as a base load operation. If the small reactors with 100 or 50 MWe could be...The relation between the implementation time of small reactor and its market was studied if small reactor could be implemented to be utilized as a base load operation. If the small reactors with 100 or 50 MWe could be implemented from 2020, the potential countries could be selected from the view point of the estimated total electricity consumption in 2020 and the stability of the electrical grid system. The commercialization of small reactors should be best done early because the market for these power units as a base load operation might be reduced due to the increase of the electricity consumption in the future after 2020. The implementation program of small reactors for the district heating and electricity supply in Mongolia, which is one of the countries having the interests in small reactor, was investigated and the future implementation plan was proposed too. In order to reduce the air pollution by coal fired heating system, there is an urgent need to start the discussion for the utilization of nuclear district heating reactor in Ulaanbaatar.展开更多
基金Project(20030533011)supported by the National Research Foundation for the Doctoral Program of Higher Education of China
文摘A DMVOCC-MVDA （distributed multiversion optimistic concurrency control with multiversion dynamic adjustment） protocol was presented to process mobile distributed real-time transaction in mobile broadcast environments. At the mobile hosts, all transactions perform local pre-validation. The local pre-validation process is carried out against the committed transactions at the server in the last broadcast cycle. Transactions that survive in local pre-validation must be submitted to the server for local final validation. The new protocol eliminates conflicts between mobile read-only and mobile update transactions, and resolves data conflicts flexibly by using multiversion dynamic adjustment of serialization order to avoid unnecessary restarts of transactions. Mobile read-only transactions can be committed with no-blocking, and respond time of mobile read-only transactions is greatly shortened. The tolerance of mobile transactions of disconnections from the broadcast channel is increased. In global validation mobile distributed transactions have to do check to ensure distributed serializability in all participants. The simulation results show that the new concurrency control protocol proposed offers better performance than other protocols in terms of miss rate, restart rate, commit rate. Under high work load （think time is ls） the miss rate of DMVOCC-MVDA is only 14.6%, is significantly lower than that of other protocols. The restart rate of DMVOCC-MVDA is only 32.3%, showing that DMVOCC-MVDA can effectively reduce the restart rate of mobile transactions. And the commit rate of DMVOCC-MVDA is up to 61.2%, which is obviously higher than that of other protocols.
文摘The relation between the implementation time of small reactor and its market was studied if small reactor could be implemented to be utilized as a base load operation. If the small reactors with 100 or 50 MWe could be implemented from 2020, the potential countries could be selected from the view point of the estimated total electricity consumption in 2020 and the stability of the electrical grid system. The commercialization of small reactors should be best done early because the market for these power units as a base load operation might be reduced due to the increase of the electricity consumption in the future after 2020. The implementation program of small reactors for the district heating and electricity supply in Mongolia, which is one of the countries having the interests in small reactor, was investigated and the future implementation plan was proposed too. In order to reduce the air pollution by coal fired heating system, there is an urgent need to start the discussion for the utilization of nuclear district heating reactor in Ulaanbaatar.
