一种应用于5G的紧凑型阵列天线设计

提出一种应用于5G的紧凑型阵列天线,由4个天线单元相互正交放置,通过在天线单元之间的上下两个平面分别添加4个二分之一波长的微带线,提高了天线单元间的隔离度。利用高频电磁仿真软件,对所提天线单元及阵列结构进行分析。实验结果表明,阵列天线的工作频段分别为2.72~3.92 GHz和4.74~5.42 GHz,在工作频段内各天线单元间的隔离度均低于-20 dB,完全覆盖5G所需的3.3~3.6 GHz和4.8~5.0 GHz两个工作频段。该阵列天线结构紧凑,体积仅为68.5 mm×68.5 mm×1.524 mm,能够被5G的小型化便携设备所应用。     

基于计数布鲁姆过滤器的集合调和算法

提出了一种基于计数布鲁姆过滤器的集合调和方法,该方法将远程节点A和B上的数据集合SA和SB分别用计数布鲁姆过滤器表示,设为CBF(SA)和CBF(SB),节点A将CBF(SA)发送给节点B,节点B进行计数布鲁姆过滤器减运算,得到差过滤器CBF(SB)CBF(SA),然后利用CBF(SB)CBF(SA)查询并获得集合SB中的差集元素SB SA,并返回SB SA给节点A,最后节点A用差集SB SA和自身集合SA进行集合并运算,完成集合调和。由于计数布鲁姆过滤器支持集合元素的删除操作,因此,该方法非常适合应用于数据集合更新频繁的分布式系统。理论分析和仿真实验结果表明,该方法既具有精确集合调和,能得到全部SB SA元素的优点,也具有近似集合调和仅需单轮消息交换的优点。     

基于随机机会约束模型的时差定位最优布站算法

针对无源定位站点部署研究存在的局限,从误差准则、截获准则和协同准则出发,建立了无源定位系统布站优化的随机机会约束模型。对三站定位问题进行了仿真,利用混合智能算法得到了不同情况下的最优布站策略。     

Nucleoside Triphosphates as Promoters to Enhance Nanoceria Enzyme‐like Activity and for Single‐Nucleotide Polymorphism Typing

Nucleoside triphosphates (NTPs) can improve the oxidase‐like activity of nanoceria and the enhancement is correlated with the type of NTP. This effect is demonstrated to be as a result of the coupling of the oxidative reaction with the NTP hydrolysis reactions, as the nanoceria has both oxidase‐like and phosphatase‐like activities. The differences reflect the different dephosphorylation catalytic activities of nanoceria to the NTP used. Furthermore, based on the NTP‐promoted oxidase‐like activity of nanoceria and the differences among the different types of NTPs, series effective and high‐throughput colorimetric assays for single‐nucleotide polymorphism (SNP) typing are developed.     

基于ASIFT的图像拼接技术在监控系统中的应用

提出了一种基于改进仿射-尺度不变特征转换(ASIFT)特征的监控图像拼接算法,ASIFT特征比传统的尺度不变特征变换(SIFT)算法具有完全的仿射不变性,在低重叠图像匹配上,ASIFT算法能够检测到更多准确的特征点,满足拼接要求。实验结果表明,该算法在视频监控系统中具有很强的实用性。     

基于高性能编码调制映射的联合解调译码方法

对于功率受限的加性高斯白噪声（Additive White Gaussian Noise,AWGN）信道,当具有高斯分布的信号作为信道输入时,信息传输性能接近信道容量.为了传输性能接近容量限,本文采用优化的非均匀排布APSK（Amplitude Phase Shift Keying）星座取代传统的多维QAM（Quadrature Amplitude Modulation）调制星座图,利用二进制交换算法（Binary Switching Algorithm,BSA）进行星座图的反馈后哈姆尼克均值优化,设计了一种新型的"4+12F-APSK"非均匀排布的星座映射方案,并与BICM-ID（Bit Interleaved Coded Modulation-Iterative Decoding）解调译码相结合,提出了基于高性能编码调制映射的联合解调译码方法,有效地解决了接近信道容量限的联合解调译码的难题.实验结果表明,在瑞利衰落信道误比特率在10的-5次方量级时,该方法比传统的MSEW（Maximum Squared Euclidean Weight）,GRAY,SP（Set Partitioning）三种矩形QAM调制方案的译码性能至少改善0.6dB;在AWGN信道误比特率在10的-3次方量级时,该方法比传统的MSEW和GRAY映射至少改善0.3dB.同时,与其他16APSK映射方案相比,该方法无论是在瑞丽衰落信道还是在AWGN信道条件下,在相同的误比特率量级上,都具有1dB~2dB的译码性能增益,有效地逼近了传输容量限.该方法在移动通信和电视广播通信等资源有限网络中具有广泛的应用前景.     

基于曲率的透视不变性分割

曲线的透视不变性分割在基于二次曲线的三维重建中非常重要。首先给出了连续曲线零曲率点和角点的提取法，在数字图像中曲经是不连续的，曲率的变化受噪声的干扰很大。在这种情况下为了检测出零曲率点和角点，对曲线采用了高斯滤波然后再提到零曲率点和角点。实验证明这种方法效果优于直接求曲率法。     

Static Stiffness Analysis of a New Type 6-DOF Micro-manipulation Robot

A 6-DOF micro-manipulation robot based on a 3-PPTTRS mechanism is proposed in this paper. Its static stiffness is an important index to evaluate load capacity and positioning accuracy. However, it is insufficient to consider the static stiffness only when the robot is in its initial pose. The stiffness in different positions and poses in its work space must be analyzed also. Thus a method to analyze the relationship between static stiffness and poses in the whole work space is presented. A static stiffness model is proposed first, and the relationship between structural parameters and static stiffness in different poses is discussed. The static stiffness analysis provides foundation for structural parameter design.     

Ultrabroadband and Reconfigurable Transmissive Acoustic Metascreen

Passive acoustic wave manipulations are severely constrained by the narrow frequency bandwidth of acoustic metastructures. In this research, an unprecedented type of reconfigurable acoustic metascreen is proposed for broadband manipulations of transmitted acoustic waves. The conceived structure is composed of uniquely designed unit cells producing the modulation of the transmitted phase shift within the full 2π range with an excellent impedance matching with the background medium. By rationally arranging the reconfigurable elements within the metascreen based on the corresponding parameter profile, different phenomena and functionalities can be easily realized. As examples, acoustic focusing and acoustic bending are presented to showcase the performance of the proposed metascreen. We indeed numerically and experimentally demonstrate the ultra-broadband and reconfigurable features of our concept over an astonishing frequency range extending from 3 to 17 kHz, which covers the majority spectrum of the audible range of human hearing. Our work provides a unique and remarkable conceptual design of acoustic metascreen opening a promising and pragmatic route to conceive compact broadband acoustic devices, where wavefront manipulations on broadband sound signals or pulsed signals are required.     

Sectoral trends in global energy use and greenhouse gas emissions

Integrated assessment models have been used to project both baseline and mitigation greenhouse gas emissions scenarios. Results of these scenarios are typically presented for a number of world regions and end-use sectors, such as industry, transport, and buildings. Analysts interested in particular technologies and policies, however, require more detailed information to understand specific mitigation options in relation to business-as-usual trends. This paper presents sectoral trend for two of the scenarios produced by the Intergovernmental Panel on Climate Change's Special Report on Emissions Scenarios. Global and regional historical trends in energy use and carbon dioxide emissions over the past 30 years are examined and contrasted with projections over the next 30 years. Macro-activity indicators are analyzed as well as trends in sectoral energy and carbon demand. This paper also describes a methodology to calculate primary energy and carbon dioxide emissions at the sector level, accounting for the full energy and emissions due to sectoral activities.