建构主义理论背景下廊坊市大学生信息素养教育改革路径

文章阐述廊坊市大学生信息素养教育存在的问题,并针对当前存在的教学问题提出建构主义理论背景下大学生信息素养教育改革的具体路径:一是树立以学生为中心,教师为主导的信息素养教学理念;二是应用建构主义学习理论鼓励和引导大学生挖掘和评估信息的能力;三是建设以"师生信息素养能力提升"为前提的队伍建设机制;四是强化个体的自我培育,注重信息道德素养的自主提升。     

Adaptive fuzzy neural network control for a space manipulator in the presence of output constraints and input nonlinearities

Space manipulator is considered as one of the most promising technologies for future space activities owing to its important role in various on-orbit serving missions. In this paper, a novel adaptive fuzzy neural network (FNN) control scheme is proposed for the trajectory tracking control of an attitude-controlled free-flying space manipulator in the presence of output constraints and input nonlinearities. The parametric uncertainties and external disturbances are also taken into the consideration. First, a model-based controller is designed by using the barrier Lyapunov function (BLF) to prevent the position tracking errors from violating the predefined output constraints. Then, an adaptive FNN controller is designed by using two FNNs to compensate for the lumped uncertainties and input nonlinearities, respectively. Rigorous theoretical analysis for the semiglobal uniform ultimate boundedness of the whole closed-loop system is provided. The proposed adaptive FNN controller can guarantee the position and velocity tracking errors converge to the small neighborhoods about zero, while ensuring the position tracking errors within the output constraints even in the presence of input nonlinearities. To the best of the authors’ knowledge, there are relatively few existing controllers can achieve such excellent control performance in the same conditions. Numerical simulations illustrate the effectiveness and superiority of the proposed control scheme.     

Application of hybrid regularization method for tomographic reconstruction of midlatitude ionospheric electron density

Reconstructing ionospheric electron density (IED) is an ill-posed inverse problem, with classical Tikhonov regularization tending to smooth IED structures. By contrast, total variation (TV) regularization effectively resists noise and preserves discontinuities of the IED. In this paper, we regularize the inverse problem by incorporating both Tikhonov and TV regularization. A specific formulation of the proposed method, called hybrid regularization, is introduced and investigated. The method is then tested using simulated data for the actual positions of the GPS satellites and ground receivers, and also applied to the analysis of real observation data under quiescent and disturbed ionospheric conditions. Experiments demonstrate the effectiveness, and illustrate the validity and reliability of the proposed method.     

复合材料层合板凹坑损伤目视检测影响因素分析

飞机复合材料结构设计中必须确定凹坑损伤的目视检测门槛值及其影响因素.采用3种直径的冲头,通过准静态方法对平板表面引入随机分布的凹坑损伤.考察板的角度、颜色以及检测人员水平3种因素对详细目视检测结果的影响.基于累积对数正态分布模型分析对比了不同因素条件下的检出概率.结果表明,蓝色板的凹坑损伤更容易被检出;接近垂直检测角度...     

Latitudinal features of Total Electron Content over the African and European longitude sector following the St. Patrick’s day storm of 2015

GNSS TEC values have been obtained from 18 stations distributed from the magnetic equator to nearly 80°N magnetic dip in the African and west-European longitude sector corresponding to the March 17–18, 2015 geomagnetic storm. Significantly depleted ionosphere have been observed at stations north of 50°N geographic on March 18, 2015 following the above storm over a longitude swath 11.9°–21°E covering the Eastern Africa and Western European longitude sector. High ROTI values were noted on March 17^th at locations around 80°N magnetic dip. Two prominent peaks in PCN were noted around 09:00 UT and 14:00 UT on March 17, 2015 and around 15:00 UT on March 18, 2015. Daytime thermospheric (O/N₂) ratio was markedly less on March 18th at latitudes above 60°N geographic which is suggested to be the major driver behind depleted high latitude ionosphere during the recovery phase of the storm on March 18, 2015.     

航空发动机脉动式装配生产线工艺仿真关键技术研究

面向国内民用航空发动机总装批产能力建设的需求,对标国内外先进脉动式装配生产线的研发进度和实施状态,在建设规划阶段,提出了脉动式总装生产线的工艺仿真方案。阐述了脉动式总装生产线工艺仿真的主要技术内容和关键技术方向,重点对关键技术的解决方案和实施途径进行规划,包括装配网络图建模及优化、车间工艺布局及生产仿真、基于二三维关联集成仿真的虚拟产品制造,最后对脉动式生产线数字孪生体进行了展望。     

基于YOLOv5的红外目标检测算法

针对红外图像的特点,提出了一种YOLOv5-IF算法,使用了基于残差机制的特征提取网络,实现了不同特征层之间信息的高效交互,能够得到更丰富的目标语义信息。通过改进YOLOv5的检测方案,增加更大尺度的检测头,有效提升了红外图像中小目标的检测概率。针对计算平台资源有限、算法实时性等问题,设计了Detection Block模块,并由此构建了特征整合网络,该模块不仅能提升算法检测精度,还有效缩减了模型参数量。在FLIR红外自动驾驶数据集上,本文算法的平均准确率（mAP）为74%,参数量仅19.5MB,优于现有的算法。     

精密“光机—光电”位移传感器的研究与设计

提出了一种在普通扭簧比较仪上增加光学传动元件和新颖光电传感元件的精密“光机光电”位移传感器的设计新思路。这种传感器具有很高的灵敏度和分辨力，有较高的线性度和示值稳定性。