内燃机噪声测试系统设计

内燃机的开发利用给我们带来巨大便利的同时,也给我们带来烦躁的噪音,文章通过分析内燃机噪声产生原因,提出降噪措施,并通过采用朗德DATaRec 4 DIC24模块采集系统,开发出一套先进的多通道内燃机噪声测试系统,为内燃机降噪提供准确数据。     

民航燃气涡扇发动机启动原理

为了保证航空燃气涡扇发动机能顺利启动,需要有两个相互协调工作的系统:启动系统和点火系统。发动机在地面正常启动时,两个系统必须同时工作;首先由启动系统将发动机转子N带转到一定转速,使适量高温高压空气进入燃烧室并与燃油喷嘴喷出的燃油相混合;其次再由点火系统点燃燃烧室里的油气混合物,释放燃料化学能并转化为热能推动涡轮对外做功。启动过程中两个系统的工作需要相互协调,并在循环开始后,由启动控制电路自动调节两个系统的工作。点火系统还应该能够独立工作,以实现空中再点火以及恶劣天气情况下为防止发动机熄火而进行的常明灯式的持续点火;启动系统也应能单独工作,以实现"干冷转"和"湿冷转",以便于发动机检查及维修后的试车。     

复进机液量气体数字化检测系统研究

LPC2210为核心开展复进机液量气体驶觳庀低车纳杓瓶?首先对检测系统的喜种功能要求进行分析,提出检测系统的总体设计方案,划分各个功能模块;然后根据检测系统设计方案要求完成对检测系统各个电路模块的硬件设计;最后完成对检测系统软件程序的编写,实现检测系统的操作功能要求.在软件程序的设计中,采用了ZLG/GUI图形用户接口,降低了显示设计的难度,提高了显示效果.调试结果显示,检测系统在软硬件方面的设计基本合理可行.     

New query suggestion framework and algorithms: A case study for an educational search engine

Query suggestion is generally an integrated part of web search engines. In this study, we first redefine and reduce the query suggestion problem as “comparison of queries”. We then propose a general modular framework for query suggestion algorithm development. We also develop new query suggestion algorithms which are used in our proposed framework, exploiting query, session and user features. As a case study, we use query logs of a real educational search engine that targets K-12 students in Turkey. We also exploit educational features (course, grade) in our query suggestion algorithms. We test our framework and algorithms over a set of queries by an experiment and demonstrate a 66–90% statistically significant increase in relevance of query suggestions compared to a baseline method.     

Successful test flight of an airship

Researchers with the Balloon Aircraft Research Center (BARC) of the Academy of Opto-electronics, CAS, succeeded in their first test flight of an aeroboat with a flight altitude up to 1,000 meters and an effective payload of 20 kilograms in Shandong on 25 December, 2007. Named as KF-15, the airship is an intermediate achievement scored by a CAS research project to address key technology for building a stratospheric platform. Scientists say the feat marks that their research has entered the stage of practi...     

Successful test flight of an airship

Researchers with the Balloon Aircraft Research Center （BARC） of the Academy of Opto-electronics, CAS, succeeded in their first test flight of an aeroboat with a flight altitude up to 1,000 meters and an effective payload of 20 kilograms in Shandong on 25 December, 2007.     

开放式数控机床控制系统设计

介绍一种低成本易兼容的开放式数控机床的控制设计方法,根据该方法设计的数控机床系统所有的功能部件都采用通用的兼容式的数控部件,能够支持通用的数控设备灵活升级或替换,使得所设计的数控机床系统具有良好的兼容性。