Novel ultra‐compact two‐dimensional waveguide‐based metasurface for electromagnetic coupling reduction of microstrip antenna array

A novel ultracompact two‐dimensional (2D) waveguide‐based metasurface is proposed herein and applied for the first time to reduce mutual coupling in antenna array for multiple‐input multiple‐output applications. The unit cell of the proposed 2D waveguide‐based metasurface is ultracompact (8.6 mm × 4.8 mm, equal to λ₀/14.2 × λ₀/25.5) mainly due to the symmetrical spiral lines etched on the ground. The metasurface exhibits a bandgap with two transmission zeros attributing to the negative permeability in the vicinity of magnetic resonance and the negative permittivity in the vicinity of electric resonance. Taking advantage of these two features, a microstrip antenna array is then designed, fabricated, and measured by embedding an 8 × 1 array of the well‐engineered 2D waveguide‐based metasurface elements between two closely spaced (9.2 mm, equal to λ₀/13.3) H‐plane coupled rectangular patches. There is good agreement between the simulated and measured results, indicating that the metasurface effectively reduces antenna mutual coupling by more than 11.18 dB and improves forward gain. The proposed compact structure has one of the highest reported decoupling efficiencies among similar periodic structures with comparable dimensions. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:789–794, 2015.     

考虑桩顶水平反力的水平受荷单桩弹塑性解析解

基于线性地基反力法和土体的弹塑性本构关系,对桩顶水平反力系数不为零时的水平受荷桩进行了研究,给出了桩顶土屈服临界荷载（水平力、弯矩）的耦合关系式。研究结果表明,当荷载大于临界荷载时,桩顶土发生塑性屈服,其塑性屈服深度随荷载的增加而增加,但其塑性区扩展速率随桩顶荷载的增加而逐渐减小。给出了弹性区与塑性区桩内力耦合的矩阵方程及其迭代求解格式;利用曲面拟合软件给出了塑性区换算深的计算公式。通过工程算例验证,证明该方法可靠快捷,便于手算,值得推广。      

Networked Estimation of Multi‐Agent Systems Subject to Faults and Unreliable Information

In this paper, a novel framework for networked estimation of multi‐agent systems subject to presence of actuator faults is proposed. This framework is developed based on the notion of sub‐observers where within a group of sub‐observers each sub‐observer estimates certain states that are conditioned on a given input, output, and other state information. We model the overall estimation process by a weighted estimation (WE) digraph. By selecting an appropriate path in the WE digraph, an assigned supervisor can select and configure a set of sub‐observers to successfully estimate all the system states. In the presence of large intermittent disturbances, noise, and faults certain sub‐observers may become invalid, and consequently the supervisor reconfigures the set of sub‐observers by selecting a new path in the estimation digraph such that the impacts of these uncertainties are confined to only the local estimators. This will prevent the propagation of uncertainties on the estimation performance of the entire multi‐agent system. Simulation results provided for a five satellite formation flight system in deep space confirm the validity and applicability of our proposed analytical work.     

基于磁耦合谐振的无线电能传输系统负载特性研究

为研究负载对无线电能传输系统传输性能的影响,建立了基于磁耦合谐振的无线电能传输系统的电路模型,利用电路耦合理论推导出在不同距离上为抑制频率分裂现象所需的最小负载以及当接收功率最大时的最佳匹配负载计算模型,且最佳匹配负载总是大于最小负载。仿真结果表明,对于不同的耦合系数,增大负载可以抑制频率分裂现象的出现;当接收功率达到最大值时,最佳匹配负载会因耦合系数的不同而改变,且总会有一个最佳匹配负载与之对应。这一结论为无线电能传输系统的负载选择提供了理论指导。     

应用虚拟仪器技术的超高频 RFID 读写器设计*

射频识别技术在资产管理领域中逐渐受到青睐,针对现有识别技术开发周期长、测试速度慢的弊端,论文提出采用虚拟仪器和数字信号处理技术,结合自定义超高频协议,研究了一种新的读写器系统。该系统用软件代替硬件实现超高频射频识别,能对超高频RFID标签自动测试,能够实现电子标签从物理层到应用层的一致性测试,能对多种宏观参数测量和分析。实验结果表明,该系统在单标签及多标签的情况下能克服单一标准的限制,很好地模拟读写器调制、解调、编码、解码、循环冗余校验、逻辑控制等基本功能,具有成本低、集成度高和扩展性好等优势。     

Twenty years of artificial life art

This essay begins with discussion of four relatively recent works which are representative of major themes and preoccupations in Artificial Life Art: ‘Propagaciones’ by Leo Nuñez; ‘Sniff’ by Karolina Sobecka and Jim George; ‘Universal Whistling Machine’ by Marc Boehlen; and ‘Performative Ecologies’ by Ruari Glynn. This essay is an attempt to contextualise these works by providing an overview of the history and forms of Artificial Life Art as it has developed over two decades, along with some background in the ideas of the Artificial Life movement of the late 1980s and 1990s.1 A more extensive study of the theoretical history of Artificial Life can be found in my paper ‘Artificial Life Art—A Primer’, in the Proceedings of DAC09 and also at http://www.ace.uci.edu/Penny. Excerpts from that essay are included here.      

TYPHOON PROCESS AND ITS IMPACT ON THE SURFACE CIRCULATION IN THE NORTHERN SOUTH CHINA SEA

A severe typhoon Utor,occurring between July 3 and 8,2001,brought heavy rainfall,strong wind and storm surge.Utor was responsible for tremendous destruction and economic losses in Philippines,Taiwan and Guangdong.An air-sea model system (MM5 and Princeton Ocean Model(POM))was built to simulate meteorological dynamics and ocean circulation in the South China Sea(SCS).In the POM the output of MM5 was used as the input data.With an increased number of vertical levels,a high-resolution planetary boundary layer scheme and updated landuse/vegetation data,the accuracy of computing wind,temperature and other meteorological fields are improved in near surface and upper levels in MM5 simulations.The simulated trajectory and wind speed of Utor are close to the observed results.The simulated distribution of rainfall is accorded well with measured data in the Pearl River Delta(PRD)area.At different meteorological stations in Hong Kong,the wind,temperature and sea surface pressure are well simulated.The simulated ocean surface current and surface temperature fields have an obvious rightward-biased response to the typhoon Utor,and the maximum velocity and the lowest temperature region appear in the 30 km of the right side of the typhoon track.The typhoon Utor could make the water 50m under the surface ocean unwell to surface and the ocean surface temperature decrease by about 2°C.     

单向耦合Lorenz-R(o)ssler系统的多参数分岔

深入研究了单向耦合Lorenz-R(o)ssler系统的动力学行为,首先定性地分析了该系统,找出了该系统所有平衡点及平衡点存在和稳定的条件.再对该系统的分岔行为做了理论分析,得到该系统发生fold和Hopf 分岔的条件.最后利用分岔软件对前面的理论进行验证,而且针对三个单向耦合参数的不同取值情况,从数值的角度研究了该系统的多参数分岔,结果表明不同的耦合强度对于系统的动力学行为有较大的影响.     

基于认知主导决策模型的陆军合同战术指挥员Agent建模策略

作战模拟系统中陆军指挥员模型建模十分重要,其决策不确定性强,功能实现复杂。针对这一问题,提出了基于认知主导决策模型的建模思想,并针对其计算机实现面临的决策者经验态势结构化描述、经验态势与当前态势自动匹配以及指挥员行为建模等重点难点问题提出了解决策略。     

Bounded Consensus Algorithms for Multi‐Agent Systems in Directed Networks

In this paper, the consensus problem is investigated via bounded controls for the multi‐agent systems with or without communication. Based on the nested saturation method, the saturated control laws are designed to solve the consensus problem. Under the designed saturated control laws, the transient performance of the closed‐loop system can be improved by tuning the saturation level. First of all, asymptotical consensus algorithms with bounded control inputs are proposed for the multi‐agent systems with or without communication delays. Under these consensus algorithms, the states’ consensus can be achieved asymptotically. Then, based on a kind of novel nonlinear saturation functions, bounded finite‐time consensus algorithms are further developed. It is shown that the states’ consensus can be achieved in finite time. Finally, two examples are given to verify the efficiency of the proposed methods.