跳频信号的归一化多普勒频差最大似然估计

针对双站定位涉及的跳频信号多普勒频差估计问题，提出了归一化的频差最大似然估计算法，利用两个定位站接收到的跳频脉冲串信号，构建一个关于基准跳频频率多普勒频差的似然函数，通过网格搜索得到使似然函数最大的多普勒频差估计，既解决了跳频信号在不同跳频频率上多普勒频差不一致的问题，又充分利用在不同频率的脉冲串信号提高了多普勒频差估计精度。通过仿真对算法的性能进行了评估，结果表明，与基于子空间的算法比较，在脉冲数达到240个时，所提算法执行效率提升30%以上。     

甘孜州农牧区县域发展水平综合评价与特征分析

[目的]对甘孜州各县市的发展状况进行研究探讨,为区域可持续发展策略的制定实施提供科学依据,对提升县域发展水平和发展质量具有重要意义。[方法]建立涵盖经济、社会、资源环境三大模块共计24项指标的评价体系,选取发展较快的2007—2014年为研究时段,运用极差法、改进熵值法、耦合协调度模型与GIS工具,对甘孜州各县市的发展水平进行综合评价与分析。[结果](1)全州综合发展水平指数平均值为0. 500 8,发展水平整体较低,其中康定市得分最高,石渠县最低,县市之间呈现两级分化。(2) 2007—2014年全州综合发展指数平均增幅0. 262 6,年均增速13. 77%,所有县市均处于上升过程,但县市之间增速不一,发展差距逐步扩大。(3)全州发展协调度平均值为0. 390 5,协调度较低,各县市均处于轻度失调或濒临失调水平。(4)发展水平、活力、协调度较高县市均集聚于州东部和南部,尤以东路片区最为典型。[结论]下一阶段需依据各县市实际,立足优势,制定实施合理的发展规划,缩小区域差异,提升综合发展水平。     

一种基于预测值量测转换的卡尔曼滤波跟踪算法

在雷达目标跟踪中，系统量测信息通常在球坐标系下获得。为了采用经典卡尔曼滤波算法实现有效目标跟踪，通常采用量测转换方法将非线性量测信息转换到直角坐标系中。针对传统量测转换方法基于量测值计算转换误差统计特性而导致的估计结果有偏问题，提出了一种基于预测值的量测转换方法，并将其与卡尔曼滤波算法相结合，获得了一种基于预测值量测转换的卡尔曼滤波跟踪算法。仿真结果表明，与现有的基于量测转换的卡尔曼滤波算法相比，该算法能在不提高运算量的情况下有效改善目标跟踪效果，跟踪精度提升约20%。     

利用频移动态特征的辐射源目标盲分选

利用辐射源目标的频移动态特征进行盲分选时，针对已有的分选方法不能很好解决非合作接收数据非周期、间断、交叠的问题，提出了一种改进的逻辑回归分选算法,将信号分选转化为轨迹分类的问题来处理。首先，借鉴多目标航迹起始模型中的M/N逻辑法的框架，设计新的数据关联门限，以建立目标起始曲线；其次，采用最小二乘拟合方法替代卡尔曼滤波，设计新的外推规则，建立载频变化预测曲线；分析新的接收数据与预测曲线的关联性，不断迭代回归或形成新的分支，最后获得目标分选结果。仿真与实测试验表明，利用逻辑回归分选算法，对不同运动目标搭载的同频辐射源可进行自动分选，4个仿真目标与2个真实目标的分选正确率达到100%。同时，该方法拓展了辐射源目标盲分选中的动态频移特征应用，为辐射源个体识别提供了新的支持。     

重大公共危机中科研协同团队识别研究——以诊断试剂为例

遴选合适的科研机构以整合成科研协同力量对于应对重大公共危机，尤其是对于防治和遏制新型冠状病毒肺炎等重大紧急疫情至关重要。首先，构建科研力量协同整合潜在对象识别理论模型，并在此基础上构建识别方法。以突发重大公共危机中的诊断试剂科研攻关为研究对象，以诊断试剂领域科研力量协同整合作为案例进行实证研究。最终识别出7个协同合作群组及29个关键核心机构，而且可将其整合为针对不同科研攻关需求的科研力量。结果还表明，在整合诊断试剂领域科研力量时，高校是与其它机构衔接的主要核心纽带，来自国家层面的科研院所及军队系统机构可以提供有力支持，而高新技术企业也是不可忽视的重要力量。     

苯醚甲环唑在猕猴桃中的残留动态及安全性评价

为摸清猕猴桃中有毒有害物质的残留动态,确保出口产品质量安全符合主要贸易国官方要求,本文采用气相色谱-质谱法,测定施药后不同时期苯醚甲环唑在猕猴桃果实中的残留量,并依据残留消解动态,按照欧盟和日本食品安全卫生标准,对10%苯醚甲环唑水分散粒剂的使用安全性进行评价。结果表明,苯醚甲环唑在猕猴桃中的残留量随着时间的推移逐渐下降,动态曲线符合一级动力学方程C_t=0.5359e^-0.184t,半衰期为3.767 d,属易消解农药;按照欧盟和日本猕猴桃农药最大残留限量要求,10%苯醚甲环唑水分散粒剂按照推荐剂量单次施药,10天后采摘食用是安全的。     

Labor migration and the decoupling of the crop-livestock system in a rural mountainous area: Evidence from Chongqing,China

Massive out-migration of rural labor force brings both challenges and opportunities to crop-livestock integrated production system (crop-livestock system) in smallholder economy. Compared with previous researches that have paid major attention to the effect of labor migration on either crop production or livestock husbandry, this study considers the mediating role of crop production in predicting the effect of labor migration on livestock raising. Our econometric estimation based on a 2012 survey of 974 rural households in Chongqing, a mountainous region of China, showed the following. (1) The massive migration of rural labor force had led to significant increase in farmland abandonment and considerable changes in the pattern of livestock raising. (2) The livestock raising number per household began to differentiate, with the livestock system separating from the traditional crop-livestock system and becoming a specialized business. (3) In terms of the pathways through which rural labor migration exerts impact on livestock raising number, though the increased opportunity costs of rural labor greatly reduced farmers’ willingness to raise livestock, the decoupling of the crop-livestock system partly alleviated the declining trend in the livestock raising number because of the availability of household labor force freed from cropping via farmland abandonment. These findings have important policy implications for rural development and agricultural restructuring in mountainous areas of China, and provide references for other developing countries.     

印度小额信贷的发展及启示

印度小额信贷的发展主要是以自助团体为基础的联系银行计划(LBP)所推动。小额信贷联系银行计划(LBP)的运作关键在于组建自助团体,建立自助团体与银行的联系。经过十多年的发展,印度拥有了发展中国家最大和成长最快的小额信贷项目。中国与印度都是发展中的人口大国,剖析印度小额信贷的经验可以为我国小额信贷的发展提供重要启示。     

Analyzing passenger behavior in airport terminals based on activity preferences

Airport terminals are facilities that provide a variety of activities related to both the preparation of the passengers for their air trip (aeronautical) and their free time inside the terminal (non-aeronautical). In the last years, the number of non-aeronautical activities has substantially increased and significantly diversified both before and after the security checkpoint. The established role of non-aeronautical activities forces planners and managers to better understand passenger behavior. The potential of discrete choice models for the exploration of passenger behavior is analyzed in this paper. For the demonstration of the methodology, Lisbon Humberto Delgado International airport is used as a case study. Data is collected through a revealed and stated preference survey inside the terminal at the area before the security checkpoint. Activity-choice models are developed to identify the factors that affect the choices of the passengers over the area where they conduct non-aeronautical activities. Forecasts show that when increasing the percentage of passengers who conduct the check-in online and have planned their activities before arriving at the airport, the passengers’ preferences to conduct non-aeronautical activities only after the security checkpoint increase. This paper shows the contribution of developing discrete choice models in the better comprehension of passenger decisions over the activities they perform in an airport terminal.     

广甘高速公路边坡安全监测实践与思考

本文结合四川广甘高速公路边坡安全监测实践,对边坡安全监测技术的发展过程与前景进行了认真的思考与分析。