基于TLS的主动全向声呐浮标目标定位与跟踪

采用最小二乘(LS)拟和法进行主动全向浮标目标定位时容易受测量误差的影响,为此提出一种基于总体最小二乘法(TLS)的定位算法,首先对主动全向浮标的定位方程和测速方程进行变换形成线性的量测方程,然后利用潜艇测距误差和浮标定位误差的随机性,基于总体最小二乘法对量测方程进行递归解算,解算过程根据潜艇运动的物理限制,取运动模型的状态预测值作为递归过程的初值,最终实现了测量误差平滑化和航迹的整体优化。仿真结果显示算法较之最小二乘法具有更好的抑制噪声能力和机动目标跟踪能力。     

宽带随机混沌雷达高速目标速度估计与成像

随机混沌具有真随机性、对初值敏感、易于产生和控制等特点,频率步进信号易于工程实现和处理,结合两者的优势,提出了一种载频随机步进的随机混沌信号(RSCFSCS)模型,用于高速目标的速度估计和距离维高分辨成像。首先,通过非周期函数激励非线性系统,产生不可预测的随机混沌信号(SCS),经频率调制后用作基带子脉冲。同时,将SCS通过映射变换得到跳频编码(FHC),用来决定调频脉冲串的载频步进。RSCFSCS 速度估计包括粗搜索和精搜索,粗搜索采用固定步长,保证速度偏差小于速度分辨单元,而精搜索采用黄金分割搜索算法可得到精确的速度估计。最后,子脉冲经相干合成形成宽带信号,实现高分辨距离成像。数值仿真表明提出的信号模型和处理算法性能良好。     

基于隐性知识管理的高职《印花技术及实训》课程教学改革

通过对《印花技术及实训》课程传统授课情况的分析,结合高职学生具有形象思维的特点,将隐性知识管理融入项目化课程教学改革中,从课程能力目标、课程效果评价、促进教师专业成长以及高职学生的可持续发展等方面阐述了基于隐性知识管理的项目化课程教学改革的可行性,最后提出了本门课程继续努力的方向。     

Learning to Argue with Intermediate Macro Theory: A Semester-Long Team Writing Project

The authors describe their experience with integrating a semester-long economic analysis project into an intermediate macroeconomic theory course. Students work in teams of “economic advisors” to write a series of nested reports that analyze the current state of the economy, and propose and evaluate policies for a decision-maker. The project simulates real-world policy consulting with an emphasis on applying economic theory and models. The authors describe the project setup and how to tailor its theme to current events, explain methods for keeping it manageable in larger classes, discuss student learning outcomes, and document course evaluation results. Besides improving the learning experience, this project prepares economics students to contribute their own views to policy debates and buttress them with tight macroeconomic reasoning.     

基于联合概率加权的高分辨雷达目标点迹处理

针对高分辨雷达在跟踪扩展目标时出现多散射点的问题,提出了一种基于联合概率加权的雷达目标点迹处理方法。首先,对信号检测出的多散射点构建其残差变量,根据判别准则进行目标点迹配对处理,剔除异常散射点;然后,同时考虑散射点位置和回波幅度信息,计算联合概率的权值,目标多散射点经概率加权融合后估计得到散射中心。仿真分析表明,该方法在高分辨雷达扩展目标点迹处理中能有效抑制杂波的干扰,目标点迹精度在距离、方位和俯仰上分别提高了20.63%、47.51%和41.03%,同时具有很好的可靠性,满足工程应用的需求。     

用于高动态目标探测雷达的相位编码脉冲压缩技术

为避免多普勒频移对相位编码信号脉冲压缩处理的影响,提出了利用已知脉冲编码序列对回波信号进行逐符号共轭点乘的脉冲压缩方法,将对齐的回波信号转换为单频信号,并利用傅里叶变换实现信号能量的积累。理论分析与计算机仿真表明,多普勒频移对脉冲压缩性能无影响。该方法适合于应用到对高动态目标进行探测的雷达系统中。     

改进的“当前”统计模型变采样率目标跟踪算法

为满足实际雷达系统对高精度和高实时性的要求,提出了一种改进的“当前”统计模型变采样率机动目标跟踪算法。该算法针对“当前”统计模型必须预设加速度极值和机动频率的问题,提出一种加速度方差和机动频率在线同步自适应方法,建立改进的“当前”统计模型机动目标跟踪算法;针对在线自适应方法计算量大的问题,结合采样周期的大小与目标机动特性的关系,引入变采样率方法。仿真结果表明,与传统“当前”统计模型相比,改进的“当前”统计模型机动目标跟踪算法能显著提高对不同机动强度目标的跟踪精度;变采样率方法通过减少采样点数,节省了系统资源,提高了跟踪实时性;所提算法将两者结合,用传统的“当前”统计模型1.5～2倍的平均采样周期得到了更小的位置均方根误差,实现了用单模型方法同时改善跟踪精度和实时性的目的。     

Credit Crunch and Target Capital Structure: Empirical Studies Based on Natural Experimentin China

Abstract:

Data from China’s credit crunch, which started in 2007, is utilized to establish a natural experiment to investigate the impact of the credit crunch on target capital structures. The sample consists of 1,128 listed companies in China during the period 2000–2011. The interest-bearing debt to total assets ratio is used as a representative indicator for capital structures. The results indicate that the credit crunch was associated with a decrease in the target debt ratios for all listed companies. Small firms, privately owned enterprises, and firms with weak mortgage capabilities responded more sensitively to the credit crunch by showing a substantial decrease in target debt ratios.     

Measuring trend inflation in India

Central to monetary policy is the concept of trend inflation to which actual inflation outcomes are expected to converge after short run fluctuations die out. Accordingly, the inflation target needs to be fixed in alignment with trend inflation to avoid unhinging inflation expectations and flattening the aggregate supply curve or imparting a deflationary bias to the economy. Results from a regime switching model applied to a hybrid New Keynesian Philips curve suggest a steady decline in trend inflation since 2014 to 4.1–4.3 per cent just before COVID-19 struck. This points to maintaining the inflation target at 4 per cent for India.     

“双碳”目标下中国旅游碳排放的文献可视化研究

随着“双谈”目标的提出,旅游业中的碳排放问题逐渐凸显,尤其是旅游交通、大型酒店等行业,在旅游业碳排放中占很大比例。以旅游业碳排放领域为研究范围,采用文献计量和可视化分析方法,对该领域已知的研究成果进行统计分析。结果显示：国内相关研究起步较晚,且发展后劲不足;区域聚合研究较少;技术进步的停滞,导致“旅游+双碳”研究创新力不足。