In data stream management systems (DSMSs), how to maintain the quality of queries is a difficult problem because both the processing cost and data arrival rates are highly unpredictable. When the system is overloaded,...In data stream management systems (DSMSs), how to maintain the quality of queries is a difficult problem because both the processing cost and data arrival rates are highly unpredictable. When the system is overloaded, quality degrades significantly and thus load shedding becomes necessary. Unlike processing overloading in the general way which is only by a feedback control (FB) loop to obtain a good and stable performance over data streams, a feedback plus feed-forward control (FFC) strategy is introduced in DSMSs, which have a good quality of service (QoS) in the aspects of miss ratio and processing delay. In this paper, a quality adaptation framework is proposed, in which the control-theory-based techniques are leveraged to adjust the application behavior with the considerations of the current system status. Compared to previous solutions, the FFC strategy achieves a good quality with a waste of fewer resources.展开更多
Many database applications require efficient processing of data streams with value variations and fluctuant sampling frequency. The variations typically imply fundamental features of the stream and important domain kn...Many database applications require efficient processing of data streams with value variations and fluctuant sampling frequency. The variations typically imply fundamental features of the stream and important domain knowledge of underlying objects. In some data streams, successive events seem to recur in a certain time interval, but the data indeed evolves with tiny differences as time elapses. This feature, so called pseudo periodicity, poses a new challenge to stream variation management. This study focuses on the online management for variations over such streams. The idea can be applied to many scenarios such as patient vital signal monitoring in medical applications. This paper proposes a new method named Pattern Growth Graph （PGG） to detect and manage variations over evolving streams with following features： 1） adopts the wave-pattern to capture the major information of data evolution and represent them compactly; 2） detects the variations in a single pass over the stream with the help of wave-pattern matching algorithm; 3） only stores different segments of the pattern for incoming stream, and hence substantially compresses the data without losing important information; 4） distinguishes meaningful data changes from noise and reconstructs the stream with acceptable accuracy. Extensive experiments on real datasets containing millions of data items, as well as a prototype system, are carried out to demonstrate the feasibility and effectiveness of the proposed scheme.展开更多
从可靠性和实用性角度出发,对工程机械远程监控系统信息流各环节的数据管理与规划进行了研究:在信号特性分类的基础上,采用数字信号处理器(DSP)/基本输入输出系统(BIOS)实时内核、多线程技术研究了现场信息面向对象采集处理,以提高现场...从可靠性和实用性角度出发,对工程机械远程监控系统信息流各环节的数据管理与规划进行了研究:在信号特性分类的基础上,采用数字信号处理器(DSP)/基本输入输出系统(BIOS)实时内核、多线程技术研究了现场信息面向对象采集处理,以提高现场信息采集处理的实时性;针对 CAN 总线多主机发送机制及各参数的不同发送周期,提出了一种数据编码方法,以提高数据传输效率;针对多用户及多设备的大量信息数据管理,采用 ER 模型建立了工程机械远程监控数据的管理结构,以提高系统的健壮性及可维护性。基于上述研究,采用 Asp.Net 技术建立了履带起重机远程监控应用实例,应用结果验证了对远程监控系统各环节数据实施规划、管理的有效性。展开更多
基金Supported by the National Key R&D Program of China(2016YFC1401900)the National Science Foundation of China(61173029,61672144)
文摘In data stream management systems (DSMSs), how to maintain the quality of queries is a difficult problem because both the processing cost and data arrival rates are highly unpredictable. When the system is overloaded, quality degrades significantly and thus load shedding becomes necessary. Unlike processing overloading in the general way which is only by a feedback control (FB) loop to obtain a good and stable performance over data streams, a feedback plus feed-forward control (FFC) strategy is introduced in DSMSs, which have a good quality of service (QoS) in the aspects of miss ratio and processing delay. In this paper, a quality adaptation framework is proposed, in which the control-theory-based techniques are leveraged to adjust the application behavior with the considerations of the current system status. Compared to previous solutions, the FFC strategy achieves a good quality with a waste of fewer resources.
基金National Natural Science Foundation of China under Grant No.60673113.FUJITSU.
文摘Many database applications require efficient processing of data streams with value variations and fluctuant sampling frequency. The variations typically imply fundamental features of the stream and important domain knowledge of underlying objects. In some data streams, successive events seem to recur in a certain time interval, but the data indeed evolves with tiny differences as time elapses. This feature, so called pseudo periodicity, poses a new challenge to stream variation management. This study focuses on the online management for variations over such streams. The idea can be applied to many scenarios such as patient vital signal monitoring in medical applications. This paper proposes a new method named Pattern Growth Graph （PGG） to detect and manage variations over evolving streams with following features： 1） adopts the wave-pattern to capture the major information of data evolution and represent them compactly; 2） detects the variations in a single pass over the stream with the help of wave-pattern matching algorithm; 3） only stores different segments of the pattern for incoming stream, and hence substantially compresses the data without losing important information; 4） distinguishes meaningful data changes from noise and reconstructs the stream with acceptable accuracy. Extensive experiments on real datasets containing millions of data items, as well as a prototype system, are carried out to demonstrate the feasibility and effectiveness of the proposed scheme.
文摘从可靠性和实用性角度出发,对工程机械远程监控系统信息流各环节的数据管理与规划进行了研究:在信号特性分类的基础上,采用数字信号处理器(DSP)/基本输入输出系统(BIOS)实时内核、多线程技术研究了现场信息面向对象采集处理,以提高现场信息采集处理的实时性;针对 CAN 总线多主机发送机制及各参数的不同发送周期,提出了一种数据编码方法,以提高数据传输效率;针对多用户及多设备的大量信息数据管理,采用 ER 模型建立了工程机械远程监控数据的管理结构,以提高系统的健壮性及可维护性。基于上述研究,采用 Asp.Net 技术建立了履带起重机远程监控应用实例,应用结果验证了对远程监控系统各环节数据实施规划、管理的有效性。
