空间信息传输中的多天线技术综述

近年来，空间信息传输中的多天线技术得到了广泛关注和大量研究。首先介绍了多天线技术的信息论基础和演进过程；然后综述了多天线通信和雷达技术的研究进展，包括多输入多输出(Multiple-Input Multiple-Output,MIMO)卫星通信技术、深空天线组阵技术、空间多维协同传输理论与技术、MIMO雷达技术和分布式孔径相参合成雷达技术，分析了其中的关键技术及未来可研究的方向；最后，总结了多天线技术在航天测控领域应用的优势，展望了基于多天线的测控技术。     

基于车辆数据的k近邻联合概率数据关联算法

在交通场景中采用一些预警措施能够有效地减少交通事故发生。例如，对车辆轨迹进行跟踪并预测车辆的驾驶行为，就是一个常用的预警方法。在对车辆进行跟踪的过程中，数据关联是很重要的部分，它可以对车辆的观测点和轨迹进行关联，从而更新车辆的轨迹，完成跟踪过程。在此背景下，提出了一种新的数据关联算法，即k近邻联合概率数据关联算法(k Nearest Neighbor-Joint Probability Data Association,kNN-JPDA)。实验结果表明，该算法能够较好地解决在交通场景下车辆数据的数据关联问题，在精度以及运行效率方面都有所提高。     

通用飞机航空电子系统架构研究综述

当前我国通用飞机产业迎来了巨大的发展机遇，开展通用飞机航电系统架构的研究具有重要意义。通过分析通用飞机航空电子系统的典型需求，包括功能需求、安全性需求、适航需求、经济性与维护保障需求等，分高、中、低三类分别讨论了国外代表性的通用飞机航电系统架构的主要特点，揭示了通用飞机航电系统架构设计的一般规律，并结合应用需求提出了未来通用飞机航电系统的发展趋势，可以为相关研究提供有益的参考。     

一种基于微波雷达回波信号的车型分类方法

车辆类型识别方法是智能交通系统的关键技术之一。利用深度学习的高维特征泛化学习能力，将改进的LeNet-5卷积神经网络用于基于交通微波雷达的大小车型分类识别。首先，以雷达触发前的N帧信号为基础，对雷达的回波信号进行分析并构建数据集；然后，分析LeNet-5卷积神经网络的特点；最后提出一种改进的LeNet-5卷积神经网络。实验结果表明，与传统的支持向量机方法相比，所提方法能够智能学习大小车的雷达时频信号特征，大小车型识别准确率达到97%以上，可为交通场景下的车型识别研究提供新的技术途径。     

基于卷积神经网络自编码器结构的空时分组传输方案

为提高现有端到端通信系统的泛化能力和可靠性，提出了一种基于卷积神经网络的空时分组码（Space-Time Block Coding，STBC）多输入多输出通信系统物理层方案。该方案将通信系统物理层表述、调制和解调过程联合起来形成端到端自编码器系统，引入多层一维卷积层，分别构建发射机和接收机，并扩展为多天线模式。为进一步提高系统可靠性，合理规划网络结构和参数，联合信号的调制和编码方案，优化了系统模型。仿真实验表明，针对瑞利相关衰落下多输入多输出（Multiple-Input Multiple-Output，MIMO）信道应用场景，训练模型可以实现传统STBC系统的误码性能，两发两收系统在发送端相关系数为0和0.9时分别优于传统系统0.5 dB和1 dB。此外，经过优化后的系统可获得采用卷积编码的性能改善效果，其两发两收不同工作方式优于传统1/2码率卷积编码STBC系统1~3 dB。     

提高党对全面深化改革的领导能力

改革开放以来,我党对于改革的认识持续深化,改革经验日益丰富,逐渐熟悉并把握了改革方略,奠定了继续领导和驾驭改革全局的理论基础。习总书记多次强调党“必然要依靠学习走向未来”。在党的领导能力内涵上,习总书记的讲话涉及三大实践能力和五大思维能力,即“思想政治能力、动员组织能力、驾驭复杂矛盾能力”以及战略思维、历史思维、辩证思维、创新思维与底线思维。这些重要精神和论述,值得进一步学习和研究。     

Spatial and temporal analyses of potential land use conflict under the constraints of water resources in the middle reaches of the Heihe River

With the rapid urbanization in China, land resources are becoming increasingly scarce. Identifying and resolving land use conflict is essential for reasonably using land resources and achieving land sustainability. Taking the middle reaches of the Heihe River as an example, we included the constraints of local water resources to construct a multi-criteria evaluation system for assessing land use competitiveness in 2000 and 2015 based on land use, socio-economic, and nighttime light data. By comparing the competitiveness of cultivated land, construction land and ecological land, we then derived the spatiotemporal patterns of potential land use conflicts. Actual land use changes supported the hypothesis that land use tended to convert into the type with higher competitiveness at areas with intense conflict, which better indicated that our assessment model was effective. The results showed that the potential land use conflict was more acute in the central and northwest but weak in the southeast and northeast, and its pattern showed a significantly positive spatial autocorrelation. The conflict between cultivated land and construction land was most prominent and mainly occurred in the transitional zone from urban to rural areas. Rapid urban development and water shortage were the main causes of the potential land use conflict. Assessing land use multi-functions and making a tradeoff among ecological, economic, and social services will be an effective way to guide future land use to solve land use conflict. Our research provides scientific evidence for sustainable land use planning and management in the arid areas.     

内蒙古黄河干流跨盟市水权试点研究

为了全面总结内蒙古自治区水权试点工作,介绍了内蒙古黄河干流跨盟市水权试点过程中强化行业监管方面的一些做法,总结了试点过程中坚持问题导向、坚持两手发力、强化节水管理、创新体制机制的一些重要经验。     

Effects of consumer cohorts and age on meat expenditures in the United States

Meat demand is likely influenced by the birth cohort and age of the individual. In this study, we examine the demand for beef, pork, poultry, and other meat in the United States using the 1984–2012 Consumer Expenditure Survey and the almost ideal demand system with the incorporation of age, period, and cohort (APC) effects. We find that the model with APC effects performs better than the models without APC effects. The results indicate that cohorts born in earlier time periods are expected to purchase significantly less poultry compared to cohorts born in later time periods, when they are measured at the same age. Over the life cycle, purchase of poultry is expected to increase with age while the opposite is true for red meat. We also find that the own-price elasticity for beef is highest among the products examined, while the own-price elasticity for other meat is lowest and the inclusion of APC effects increases the absolute value of the own-price elasticities for beef, pork, and poultry, but reduces the own-price elasticity for other meat. Our forecasts indicate that the aggregate poultry purchase will continue to increase until 2022, while the aggregate purchase of red meat will slightly increase until 2017, but will either decrease or stay at same level from year 2017 to 2022.     

汇水系统绿地雨洪调蓄研究——以武汉港西汇水系统为例

绿地有一定的雨洪调蓄功能，雨洪状况下，如何在汇水系统尺度利用和保护绿地亟待研究。选取95处位于武汉港西汇水系统的地块，调研地块性质，利用ArcGIS提取不透水比例及平均坡度，并进行SWMM水文模型演算。通过实验性模拟结果的对比，得出汇水系统的绿地雨洪调蓄效率(λ＝0.13m3/m2)、汇水系统(g＝36%)和各类用地(g＝18%～47%)基于雨水调蓄理念下的最低绿地率，使汇水系统水文状况达到海绵城市建设标准。讨论了不同重现期下汇水系统的绿地雨洪调蓄效能，旨在完善绿地雨洪调蓄的研究方法、指标体系及利用与保护策略，为相关研究与实践提供借鉴。