在垂直和任意方向磁场中的六角形超导网络相边界

给出了在垂直外磁场和任意方向外磁场中的七节点六角形超导网络相边的精确解析表达式,由此表达式求出了两种情况下的六角形网络的相边界,得到了在任意方向外磁场中的网络相边界Ｔｃ（Ｈ）是以敏感和复杂的方式依赖于磁场大小和方向,并对相边界Ｔｃ（Ｈ）这些特性的某些应用给予了讨论。     

无人机自主控制关键技术新进展

 无人机在军用、民用领域具备巨大的应用潜力,当前世界各国正在大力推进无人机的研发工作,而无人机自主控制是无人机研发中极富挑战性的关键问题。本文介绍了无人机的分类和系统框架;根据无人机实际应用的要求,提炼出无人机自主控制进程中的几个关键性技术问题,包括感知与规避、故障诊断与容错控制、协同控制及这3 项关键技术有机综合的新问题与新方法--容错协同控制等,并重点阐述了这些关键技术的机理和较有代表性的成果及新进展;以目前无人机重要应用领域--空中加油过程及森林资源与火情监测为例,简述了以上技术在实际应用中的具体体现及其新进展;最后对无人机自主控制技术进行了展望,并给出各项关键技术存在的挑战及可能的解决思路。     

A Composite Adaptive Fault-Tolerant Attitude Control for a Quadrotor UAV with Multiple Uncertainties

In this paper, a composite adaptive fault-tolerant control strategy is proposed for a quadrotor unmanned aerial vehicle(UAV) to simultaneously compensate actuator faults, model uncertainties and external disturbances. By assuming knowledge of the bounds on external disturbances, a baseline sliding mode control is first designed to achieve the desired system tracking performance and retain insensitive to disturbances. Then, regarding actuator faults and model uncertainties of the quadrotor UAV, n...     

Fault-Tolerant Control for a Class of Uncertain Systems with Actuator Faults

The problem of fault-tolerant controller design for a class of polytopic uncertain systems with actuator faults is studied in this paper. The actuator faults are presented as a more general and practical continuous fault model. Based on the affine quadratic stability (AQS), the stability of the polytopic uncertain system is replaced by the stability at all corners of the polytope. For a wide range of problems including H∞ and mixed H 2 /H∞ controller design, sufficient conditions are derived to guarantee the robust stability and performance of the closed-loop system in both normal and fault cases. In the framework of the linear matrix inequality (LMI) method, an iterative algorithm is developed to reduce conservativeness of the design procedure. The effectiveness of the proposed design is shown through a flight control example.     

Cooperative localization against GPS signal loss in multiple UAVs flight

Based on multiple unmanned aerial vehicles(UAVs) flight at a constant altitude,a fault-tolerant cooperative localization algorithm against global positioning system(GPS) signal loss due to GPS receiver malfunction is proposed.Contrast to the traditional means with single UAV,the proposed method is based on the use of inter-UAV relative range measurements against GPS signal loss and more suitable for the small-size and low-cost UAV applications.Firstly,for re-localizing an UAV with a malfunction in its GPS receiver,an algorithm which makes use of any other three healthy UAVs in the cooperative flight as the reference points for re-localization is proposed.Secondly,by using the relative ranges from the faulty UAV to the other three UAVs,its horizontal location can be determined after the GPS signal is lost.In order to improve an accuracy of the localization,a Kalman filter is further exploited to provide the estimated location of the UAV with the GPS signal loss.The Kalman filter calculates the variance of observations in terms of horizontal dilution of positioning(HDOP) automatically.Then,during each discrete computing time step,the best reference points are selected adaptively by minimizing the HDOP.Finally,two simulation examples in Matlab/Simulink environment with five UAVs in cooperative flight are shown to evaluate the effectiveness of the proposed method.     

低温降解秸秆木霉菌的筛选、鉴定及功能评价

中国北方冬季气温低,秸秆直接还田后腐解效率低,易造成病原菌积累。为促进秸秆原位腐解,降低病原菌积累,采用低温培养结合纤维素酶、半纤维素酶、漆酶活性筛选,获得一株低温降解秸秆的木霉菌株C47-3;该菌在秸秆液体培养基中于15℃条件下培养15 d时,对秸秆的降解率为22.28%;该菌株经形态学观察和分子生物学鉴定为近深绿木霉Trichoderma paratroviride;木霉菌株C47-3及其挥发性物质对供试的葡萄座腔菌、禾谷丝核菌、灰葡萄孢等8种病原菌均具有抑制效果,对假禾谷镰孢菌的抑制率可达60%以上。筛选得到的木霉菌株C47-3在提高低温条件下秸秆腐解效率的同时具有一定的生防潜能,为我国北方冬季玉米秸秆还田后高效利用及土传病害的生物防治提供了菌种资源。     

类胰岛素生长因子-1何以折叠成2种高级结构的分子基础

胰岛素和IGF-1属于同一超家族,具有共同的结构模体和非常类似的三维结构,但两者的折叠行为却迥然不同。胰岛素和单链胰岛素（PIP）折叠成唯一的热力学稳定的三维结构,而IGF-1则折叠成两种热力学稳定的三维结构。即是说：IGF-1的同一序列编码两种折叠信息。是序列中的什么部位决定胰岛素／PIP和IGF-1具有不同的折叠行为？这是一个极为有趣且长期为人们所困惑的问题。本实验室在PIP和mini—IGF-1工作的基础上,用蛋白质工程技术先后设计表达了一系列胰岛素和IGF-1的杂交分子,阐明了胰岛素和IGF-1不同折叠行为的分子基础。此外,还研究了文昌鱼胰岛素类似肽（aILP）的体外再折叠,结果提示胰岛素和IGF-1的不同折叠行为是由它们的祖先分子aILP分支进化而来的。     

惰性原子吸附单层的固液相变

本文以Ｌｅｎｎａｒｄ－Ｊｏｎｅｓ势描述惰性原子间的相互作用，将融化的统计几何理论应用到物理吸附在石墨表面的惰性原子单层的固液相变。由相变方程进行严格数值计算所得熔化曲线与计算机模拟实验结果相当接近，所得三相点约化温度为Ｔｔ＝０．４３８，与吸附在石墨表面的惰性原子层实验测量结果和计算机模拟实验的结果也都有相当好的符合。     

滑阀稳态液动力补偿新技术及其应用

作用在滑阀上的稳态液动力的消除补偿技术对于改善某些液压元件的性能有着十分重要的意义。本文介绍了一种用环形槽补偿作用在滑阀阀芯上的稳态液动力新技术;理论分析及试验结果都表明,在滑阀阀芯上加工一个简单的环形槽,能补偿80％左右的稳态液动力;将这项新技术应用于直动式溢流阀上,大幅度地改善了溢流阀的启闭特性。     

基于行为的思维分析和DSS中信息组织方式的研究

一般非结构化的决策问题及其支持方式是近年国内外DSS发展面临的主要热点之一。本文从基于行为的思维分析角度为管理决策及计算机信息组织的改进, 提出了一套具有一定普适性的思路和实现途径, 通过将思维的行为因素和行为原则引入DSS系统, 把人这一重要而复杂的系统因素引入DSS系统设计, 为一般决策、群体决策、多原则决策等非结构化问题的决策支持提供一定的理论基础和实现手段。此外, 将矛盾作为系统运行的激励因素引入DSS系统, 这对于传统DSS设计中回避人的矛盾冲突的思想是一种新的突破。