Landing gear lower drag stay is a key component which connects fuselage and landing gear and directly effects the safety and performance of aircraft takeoff and landing. To effectively design the lower drag stay and r...Landing gear lower drag stay is a key component which connects fuselage and landing gear and directly effects the safety and performance of aircraft takeoff and landing. To effectively design the lower drag stay and reduce the weight of landing gear, Global/local Linked Driven Optimization Strategy(GLDOS) was developed to conduct the overall process design of lower drag stay in respect of optimization thought. The whole-process optimization involves two stages of structural conceptual design and detailed design. In the structural conceptual design, the landing gear lower drag stay was globally topologically optimized by adopting multiple starting points algorithm. In the detailed design, the local size and shape of landing gear lower drag stay were globally optimized by the gradient optimization strategy. The GLDOS method adopts different optimization strategies for different optimization stages to acquire the optimum design effect. Through the experimental validation, the weight of the optimized lower dray stay with the developed GLDOS is reduced by 16.79% while keeping enough strength and stiffness, which satisfies the requirements of engineering design under the typical loading conditions. The proposed GLDOS is validated to be accurate and efficient in optimization scheme and design cycles. The efforts of this paper provide a whole-process optimization approach regarding different optimization technologies in different design phases, which is significant in reducing structural weight and enhance design tp wid 1 precision for complex structures in aircrafts.展开更多
为明确中哈边境迁飞蝗虫降落过程的气象背景,选择中哈边境塔城地区蝗虫迁飞为害最严重的1999年为例,基于当年迁飞蝗虫降落时间、地点及为害程度等数据,利用中尺度气象预报与研究(weather research and forecasting,WRF)模式模拟塔城地...为明确中哈边境迁飞蝗虫降落过程的气象背景,选择中哈边境塔城地区蝗虫迁飞为害最严重的1999年为例,基于当年迁飞蝗虫降落时间、地点及为害程度等数据,利用中尺度气象预报与研究(weather research and forecasting,WRF)模式模拟塔城地区迁飞蝗虫降落的天气变化。结果表明,垂直速度达到0.22 m/s的下沉气流、风速为3 m/s以上的东南风向、降雨和低于19℃的温度胁迫是影响1999年7月10日中哈边境迁飞蝗虫降落的主要气象因素;统计当年迁入蝗虫降落事件,发现下沉气流、风向切变、降雨和低温在蝗虫降落过程中出现的频次占总迁入蝗虫降落事件的70%、50%、30%和10%,其中下沉气流和风向切变是影响蝗虫降落的主导因子。表明利用WRF模式可准确预测迁飞蝗虫跨境为害降落区域的天气过程。展开更多
Background:Online peer-to-peer lending(P2P lending)is booming as the popularity of e-finance.To develop a conceptual model for the P2P lending process is great valuable for managers to tack the issues of marketing,man...Background:Online peer-to-peer lending(P2P lending)is booming as the popularity of e-finance.To develop a conceptual model for the P2P lending process is great valuable for managers to tack the issues of marketing,management and operation.Methods:In this paper,we focus on the P2P lending process model and provide a comparative analysis comparing with traditional bank loan process.Results:Firstly,our model shows that the information flow in P2P lending is more frequent and transparent.Secondly,the model reveals that P2P lending uses a quite different credit audition method,which relies on information and the decision model in the P2P systems.Thirdly,the loan management is not complete normally in P2P lending,because most P2P companies do not have the post-loan records of borrowers.Conclusions:These findings inspire future studies and practices on P2P lending process and key technologies.展开更多
基于系统理论,把飞机进近着陆阶段不安全事件发生当作系统的涌现特性,将其安全问题当作控制问题,本文采用系统理论过程分析（system theoretic process analysis, STPA）方法进行进近着陆阶段的安全性分析,明确了这一阶段的不安全控制行...基于系统理论,把飞机进近着陆阶段不安全事件发生当作系统的涌现特性,将其安全问题当作控制问题,本文采用系统理论过程分析（system theoretic process analysis, STPA）方法进行进近着陆阶段的安全性分析,明确了这一阶段的不安全控制行为,剖析了产生不安全控制行为的主动控制致因因素和反馈致因因素.以飞行员提供不正确的进近着陆高度,速度,下滑角的不安全控制行为（UCA1）为例,剖析其具体的致因因素;最后,在构建飞机进近着陆过程简化的运动学计算框架基础上,对进近着陆过程进行运动学计算分析.对不安全控制行为1 （UCA1）作具体解算和分析,开展了基于STPA的定量安全性分析,表明STPA方法在进近着陆阶段安全性分析是有效的.展开更多
基金co-supported by National Natural Science Foundation of China (Nos. 51975124 and 51675179)Aerospace Science and Technology Fund of China (No.AERO201937)Research Start-up Funding of Fudan University (No. FDU38341)。
文摘Landing gear lower drag stay is a key component which connects fuselage and landing gear and directly effects the safety and performance of aircraft takeoff and landing. To effectively design the lower drag stay and reduce the weight of landing gear, Global/local Linked Driven Optimization Strategy(GLDOS) was developed to conduct the overall process design of lower drag stay in respect of optimization thought. The whole-process optimization involves two stages of structural conceptual design and detailed design. In the structural conceptual design, the landing gear lower drag stay was globally topologically optimized by adopting multiple starting points algorithm. In the detailed design, the local size and shape of landing gear lower drag stay were globally optimized by the gradient optimization strategy. The GLDOS method adopts different optimization strategies for different optimization stages to acquire the optimum design effect. Through the experimental validation, the weight of the optimized lower dray stay with the developed GLDOS is reduced by 16.79% while keeping enough strength and stiffness, which satisfies the requirements of engineering design under the typical loading conditions. The proposed GLDOS is validated to be accurate and efficient in optimization scheme and design cycles. The efforts of this paper provide a whole-process optimization approach regarding different optimization technologies in different design phases, which is significant in reducing structural weight and enhance design tp wid 1 precision for complex structures in aircrafts.
文摘为明确中哈边境迁飞蝗虫降落过程的气象背景,选择中哈边境塔城地区蝗虫迁飞为害最严重的1999年为例,基于当年迁飞蝗虫降落时间、地点及为害程度等数据,利用中尺度气象预报与研究(weather research and forecasting,WRF)模式模拟塔城地区迁飞蝗虫降落的天气变化。结果表明,垂直速度达到0.22 m/s的下沉气流、风速为3 m/s以上的东南风向、降雨和低于19℃的温度胁迫是影响1999年7月10日中哈边境迁飞蝗虫降落的主要气象因素;统计当年迁入蝗虫降落事件,发现下沉气流、风向切变、降雨和低温在蝗虫降落过程中出现的频次占总迁入蝗虫降落事件的70%、50%、30%和10%,其中下沉气流和风向切变是影响蝗虫降落的主导因子。表明利用WRF模式可准确预测迁飞蝗虫跨境为害降落区域的天气过程。
基金supported by a grant from the Shenzhen Municipal Science and Technology R&D Funding—Basic Research Program(Project No.JCYJ20140417105742712).
文摘Background:Online peer-to-peer lending(P2P lending)is booming as the popularity of e-finance.To develop a conceptual model for the P2P lending process is great valuable for managers to tack the issues of marketing,management and operation.Methods:In this paper,we focus on the P2P lending process model and provide a comparative analysis comparing with traditional bank loan process.Results:Firstly,our model shows that the information flow in P2P lending is more frequent and transparent.Secondly,the model reveals that P2P lending uses a quite different credit audition method,which relies on information and the decision model in the P2P systems.Thirdly,the loan management is not complete normally in P2P lending,because most P2P companies do not have the post-loan records of borrowers.Conclusions:These findings inspire future studies and practices on P2P lending process and key technologies.
