Determining the approach speed envelope of carrier aircraft

Many factors, such as deck motion and air wave, influence the determination of the approach speed which has an important effect on landing safety. Until recently, there are no design criteria about approach speed of carrier aircraft in the current standards and available publications. Therefore, the requirements of stall margin, longitudinal acceleration ability, altitude correction and field-of-view on approach speed were researched. Based on the flight dynamics model, the flight simulations were conducted to study the effect of the response time of en- gine, wave off requirements, elevator efficiency and deflection rate on the approach speed. The results presented that the approach longitudinal acceleration and altitude correction ability had crucial influence on the approach speed envelope of the aircraft. The limitations of the control requirements, field-of-view requirements and gear were also given through the simulation and analysis. Based on the above results, the approach speed envelope were determined.     

建设工程造价控制存在问题与解决策略

随着我国经济的高速发展,基础建设项目迅猛增多,但建设工程造价控制未得到应有的重视,隐患很大,特别是全过程造价控制存在以下现象：投资估算随意决策,缺乏科学手段;项目设计标准偏高,技术性和经济性脱节;清单及控制价编制质量低劣,影响项目顺利实施;不平衡报价放大招标文件缺陷,损害招标人利益;结算审价机制不健全,容易形成内外勾结。这此现象严重影响造价控制的科学性,进而影响工程质量。为解决这些问题,必须从健全决策机制,科学投资估算;强化工程设计管理,控制限额设计标准;落实造价咨询成果质量终身责任制,提升造价咨询服务能力;优化评标办法,加强不平衡报价监控;健全结算审价机制,提高审价人员专业能力等方面入手采取有效措施。