微型低速短波数据终端的研制

短波信道是一种变参信道,存在严重的衰落和干扰。本文讨论了信道对数据信号传输的影响,并详细叙述了用于中短距离数据通信的微型短波数据终端的设计思想,最后还提供了该终端的硬件系统框图及信道实验结果。     

风洞风表检定仪8031系统研制

本文是在笔者最近研制的ＦＢＹ－１型风洞风表检定仪８０３１系统的基础上整理而成的，主要介绍了这个简单而实用系统的基本组成、软件设计以及针对现场实际问题所采用的有效措施     

VM—1邻频电视调制器电路原理分析

分析了一种射频处理邻频电视调制器的电路原理，阐述了为满足邻频电视信号传输要求而采取的带外寄生分量抑制技术及ＳＡＷＦ的应用。     

论县城在农村城镇化中的主渠道作用

城镇化包括农业人口转变为城镇人口和农村地区转变为城镇地区两个过程.我国农村城镇化既要尊重世界城镇化的一般规律,又要符合我国国情.我国农业剩余劳动力的空间转移应以县城吸纳为主,这对城镇的合理发展、农村工业化的顺利进行等都具有重要意义.     

Game Theory Study on Distributors＇ Alliance to Gain Competitive Advantage in Marketing Channel

Using the Cournot Game Model, this paper has analyzed the motivation of the distributors＇ alliance to gain competitive advantage in marketing channel. At first, this paper separately analyzed the advantage of alliance in the situation of one- short game and infinitely repeated game, then, based on the analysis of distributors＇ betrayal of the alliance under infinitely repeated game, the conditions to maintain the distributors alliance are put forward and discussed.     

Bicuculline and picrotoxin block γ-aminobutryic acid-gated Cl− conductance by different mechanisms

Summary Using isolated, internally perfused bullfrog dorsal root ganglion cells we have studied the dose-response curves for -aminobutyric acid (GABA) in the presence of internally or externally applied GABA antagonists. With external application of antagonists the inhibition of the GABA current by bicuculline was competitive and that by picrotoxin was noncompetitive. Picrotoxin but not bicuculline blocked when internally perfused.To whom reprint requests should be addressed.Acknowledgments. We thank Drs S. Minakami and S. Yasui for helpful discussions and comments.     

Earthshaker: A mobile rescue robot for emergencies and disasters through teleoperation and autonomous navigation

To deal with emergencies and disasters without rescue workers being exposed to dangerous environments, this paper presents a mobile rescue robot, Earthshaker. As a combination of a tracked chassis and a six-degree-of-freedom robotic arm, as well as miscellaneous sensors and controllers, Earthshaker is capable of traversing diverse terrains and fulfilling dexterous manipulation. Specifically, Earthshaker has a unique swing arm—dozer blade structure that can help clear up cumbersome obstacles and stabilize the robot on stairs, a multimodal teleoperation system that can adapt to different transmission conditions, a depth camera-aided robotic arm and gripper that can realize semiautonomous manipulation and a LiDAR aided base that can achieve autonomous navigation in unknown areas. It was these special systems that supported Earthshaker to win the first Advanced Technology & Engineering Challenge (A-TEC) championships, standing out of 40 robots from the world and showing the efficacy of system integration and the advanced control philosophy behind it.     

基于变换域注意力机制的压缩伪影去除的方法

图像有损压缩过程往往会导致图像质量退化,使图像出现压缩伪影。针对现有基于深度学习的方法缺乏对联合图像专家组(Joint Photographic Experts Group,JPEG)压缩算法先验信息的利用,提出一种基于变换域注意力机制的去伪影方法。该方法利用卷积神经网络在像素域和离散余弦变换(discrete cosine transform,DCT)域分别提取特征,再将双域学习的特征信息进行融合。利用量化表设计了DCT注意力机制,该模块根据DCT系数的损失程度给予各频率系数不同的权值,使网络自适应补偿量化引起的误差。于此基础上,在像素域引入通道注意力机制,从而更好地利用量化表的先验信息。在主要数据集上,提出的去伪影方法以固定的模型参数对多种质量因子的压缩图像进行伪影去除实验。实验结果表明,所提出的方法在各评价指标和主观视觉上取得较好的效果。     

等衰落轨道角动量索引调制系统的信道容量性能分析

射频轨道角动量(orbital angular momentum,OAM)提供了一种可以在同一载波频率物理信道上复用一组正交模式以提高信道容量的方法。现有研究大多专注于信道容量提升,对系统复杂度的研究相对较少。在基于均匀圆形阵列(uniform circular array,UCA)的OAM通信系统中,发射机需要完成大量调制运算以生成OAM信号。于是,提出了一种等衰落轨道角动量索引调制(equal fading orbital angular momentum index modulation,EOAM-IM)方案,其中,IM有效降低了OAM调制运算复杂度,且等衰落发射机也保证了不同模式OAM子信道传输增益。此外,还详细推导了所提EOAM-IM方案的系统信道容量。仿真结果表明,所提EOAM-IM方案能以更低的调制复杂度获得比传统OAM方案更高的信道容量。     

基于卡诺机的大规模MIMO通信容量建模及性能分析

信息本质上以能量和熵的形式在通信系统中流动,类似于传统热机中的能量流动过程。结合热力学卡诺机模型和经典香农信息论理论,建立了一个广义的热力学(multiple input multiple output, MIMO)通信系统模型,对大规模天线通信场景下使用前向纠错码的信道容量进行分析。利用通信系统中存在的自由度和熵的概念,推导了热力学模型下的广义信道容量,并对信道容量与噪声自由度及编码开销的关系进行验证仿真。仿真结果表明,所提出的热力学信道容量与香农信道容量是一致的。