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
This paper considers a time-constrained data collection problem from a network of ground sensors located on uneven terrain by an Unmanned Aerial Vehicle(UAV),a typical Unmanned Aerial System(UAS).The ground sensors ha...This paper considers a time-constrained data collection problem from a network of ground sensors located on uneven terrain by an Unmanned Aerial Vehicle(UAV),a typical Unmanned Aerial System(UAS).The ground sensors harvest renewable energy and are equipped with batteries and data buffers.The ground sensor model takes into account sensor data buffer and battery limitations.An asymptotically globally optimal method of joint UAV 3D trajectory optimization and data transmission schedule is developed.The developed method maximizes the amount of data transmitted to the UAV without losses and too long delays and minimizes the propulsion energy of the UAV.The developed algorithm of optimal trajectory optimization and transmission scheduling is based on dynamic programming.Computer simulations demonstrate the effectiveness of the proposed algorithm.展开更多
[目的/意义]无人智慧农场是智慧农业的重要实践模式。本研究以山东德州“吨半粮”无人智慧农场为实验场所,攻克大田智慧农场建设中的核心技术难题,探索其建设模式与服务机制。[方法]运用物联网技术,研发了智慧农场的立体感知网络,能够...[目的/意义]无人智慧农场是智慧农业的重要实践模式。本研究以山东德州“吨半粮”无人智慧农场为实验场所,攻克大田智慧农场建设中的核心技术难题,探索其建设模式与服务机制。[方法]运用物联网技术,研发了智慧农场的立体感知网络,能够高效采集并汇聚传输环境、作物长势和设备状态等关键数据。借助数据分析挖掘技术,精准提取了小麦的物候期、麦穗特征等关键表型信息。进一步结合智能农机与智能决策技术,研发了集云管控平台、智能化设备及智能农机于一体的智能控制系统。此外,依托多源数据融合、分布式计算和地理信息系统(Geographic Information System, GIS)等技术,构建了农业生产全过程智能管控平台。[结果和讨论]“吨半粮”无人智慧农场感知系统不仅提高了数据传输质量,同时可以完成麦穗、物候期等表型特征的本地分析;智能控制系统可帮助农机提升自主作业精度和灌溉、施药效率、质量,通过农业设备的改造升级实现了农场耕作、种植、管理、收获的全链条智能化管控;大数据智慧服务平台为农户提供了气象预测、灾害预警、最佳播期等农事管理服务,极大地提高了农场管理的数字化、智能化水平。实验结果表明,自组网络数据准确率保持在85%以上,无人机施药可节药55%,灌溉模型可节水20%,“济南17”和“济麦44”分别增产10.18%和7%。[结论]研究结果可为智慧农场建设提供参考和借鉴。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.
基金funding from the Australian Government,via Grant No.AUSMURIB000001 associated with ONR MURI Grant No.N00014-19-1-2571。
文摘This paper considers a time-constrained data collection problem from a network of ground sensors located on uneven terrain by an Unmanned Aerial Vehicle(UAV),a typical Unmanned Aerial System(UAS).The ground sensors harvest renewable energy and are equipped with batteries and data buffers.The ground sensor model takes into account sensor data buffer and battery limitations.An asymptotically globally optimal method of joint UAV 3D trajectory optimization and data transmission schedule is developed.The developed method maximizes the amount of data transmitted to the UAV without losses and too long delays and minimizes the propulsion energy of the UAV.The developed algorithm of optimal trajectory optimization and transmission scheduling is based on dynamic programming.Computer simulations demonstrate the effectiveness of the proposed algorithm.
文摘[目的/意义]无人智慧农场是智慧农业的重要实践模式。本研究以山东德州“吨半粮”无人智慧农场为实验场所,攻克大田智慧农场建设中的核心技术难题,探索其建设模式与服务机制。[方法]运用物联网技术,研发了智慧农场的立体感知网络,能够高效采集并汇聚传输环境、作物长势和设备状态等关键数据。借助数据分析挖掘技术,精准提取了小麦的物候期、麦穗特征等关键表型信息。进一步结合智能农机与智能决策技术,研发了集云管控平台、智能化设备及智能农机于一体的智能控制系统。此外,依托多源数据融合、分布式计算和地理信息系统(Geographic Information System, GIS)等技术,构建了农业生产全过程智能管控平台。[结果和讨论]“吨半粮”无人智慧农场感知系统不仅提高了数据传输质量,同时可以完成麦穗、物候期等表型特征的本地分析;智能控制系统可帮助农机提升自主作业精度和灌溉、施药效率、质量,通过农业设备的改造升级实现了农场耕作、种植、管理、收获的全链条智能化管控;大数据智慧服务平台为农户提供了气象预测、灾害预警、最佳播期等农事管理服务,极大地提高了农场管理的数字化、智能化水平。实验结果表明,自组网络数据准确率保持在85%以上,无人机施药可节药55%,灌溉模型可节水20%,“济南17”和“济麦44”分别增产10.18%和7%。[结论]研究结果可为智慧农场建设提供参考和借鉴。