You can create a data flow task that has no data flow , but the task executes only if it includes at least one data flow 可以创建无数据流的数据流任务，但任务只有在其包含至少一个数据流时才执行。
To achieve fast acquisition with only a few symbols , a joint structure for clock and carrier synchronization with non - data aided ( nda ) mode is presented 摘要为了实现解调中的快速同步，本文给出了一种联合结构下无数据辅助载波同步和符号同步的方法。
Because of the safety ' s request of the super - speed station ' s application , the super - speed station should hold the radio silence state when it has n ' t the task of data communication , therefore when the super - speed station is working it has two kinds of statuses : communication state and radio silence state 由于高速电台应用安全的要求，需要高速电台在无数据通信任务的时候保持无线电静默，因此高速电台工作时有两种状态：数传状态和静默状态。
The thesis uses sql server 6 . 0 database , standard sql access interface , and oriented - object program language vc + + to implement our electric network dispatching message management system . the system can operate like this : automaticly check if having data files come ; discriminate file type ; automaticly read data into database ; rapidly give out the precise analysis results , including waveform display , fault component calculating ; select fault phase ; distinguish fault type ; precisely fault allocate ; run all kinds of database administration , like antomatic add - on , automatic deletion , amendment , inquiry by different conditions ; print all kinds of outcome and keep them into database ; share data resource by web technique ; deal with complex faults . the whole system i finished will be powerful technic support for dispatching operation 本文采用标准的sqlserver6 . 0数据库，标准sql访问接口和面向对象编程工具vc + +进行编程,实现了集数据库、分析计算、图形化界面、网络通讯于一体的电网故障录波信息管理及故障诊断系统，该系统能够在每次故障后自动查询有无数据文件的到来;能够对传送到调度端的数据文件分析其类型;能够按comtrade格式自动地将大量数据信息完整地填入数据库中;能够进行故障选相,故障类型判别和故障精确定位;能够快速地对故障做出精确的分析,计算各次谐波分量,有无功和视在功率,功角,序分量等;能够对数据库进行各项管理,如浏览,自动添加和删除,修改和按各种不同条件进行查询;能够将计算结果,各种表格图形打印出来和保存进数据库中;能够将计算分析结果通过web技术为其他部门提供共享数据资源
