一种改进的理想滤波器方位模糊抑制方法

合成孔径雷达(SAR)图像的方位模糊问题是由于方位向欠采样引起的,其严重影响判读人员对SAR图像的解译.阐述了方位模糊的来源及其建模,进一步总结了利用理想滤波器进行方位模糊抑制的方法及其局限性,针对该方法的参数失配问题,从主像和模糊像在方位向和距离向上的偏移距离的角度出发,提出并明确分块处理大区域方位模糊抑制的思路及分...     

带宽管理与资源预留汇聚方案的研究与改进

为了在互联网中为多媒体应用提供服务质量的保证，根据端到端Intserv传输流的需要，提出了在Diffserv网络区内资源管理的两种方案——带宽管理与资源预留汇聚，并从3个方面对两种方案做了分析与比较，得出RSVP汇聚方案更具发展前途，同时提出了基于主动网络的RSVP汇聚的方案，对RSVP汇聚方案进行了改进，使得网络具有较强的自适应和动态部署的能力。     

Carrier‐sense‐assisted adaptive learning MAC protocols for distributed wireless LANs

A Carrier‐sense‐assisted adaptive learning MAC protocol for wireless LANs, capable of operating efficiently in bursty traffic wireless networks with unreliable channel feedback, is introduced. According to the proposed protocol, the mobile station that is granted permission to transmit is selected by means of learning automata. At each station, the learning automaton takes into account the network feedback information in order to update the choice probability of each mobile station. The proposed protocol utilizes carrier sensing in order to reduce the collisions that are caused by different decisions at the various mobile stations due to the unreliable channel feedback. Simulation results show satisfactory performance of the proposed protocol compared to similar MAC protocols. Copyright © 2005 John Wiley & Sons, Ltd.     

H robust stabilizability

In this paper, we improve on the results of robust stabilizability obtained by Kimura. We do this in a constructive way by using an H^∞-approach, and exhibit an upper bound for the order of robust controllers.     

高分辨率单脉冲测量雷达接收机的设计

根据某些测量雷达提出的较高分辨率的要求，详细介绍高分辨率单脉冲测量雷达接收系统的理论分析和方案论证，并给出具体的实施方案。     

费用非对称通信网络上的群播路由算法

文中考虑了费用非对称通信网络上的群播路由问题,提出了一种接近最小成本的启发式算法--NEW-GM算法.该算法以FMPH(Fast Minimum Path Cost HouriStic)为基础,可以有效的降低成本.数值实验表明:这种算法是有效的,且所获得问题解的总费用几乎总是小于或等于由GTM算法所获得的解的总费用.NEW-GM算法的时间复杂度与GTM算法的相同,为O(p3n2).     

Unified routing protocol based on passive bandwidth measurement in heterogeneous WMNs

The past few years have witnessed a surge of wireless mesh networks (WMNs)‐based applications and heterogeneous WMNs are taking advantage of multiple radio interfaces to improve network performance. Although many routing protocols have been proposed for heterogeneous WMNs, most of them mainly relied on hierarchical or cluster techniques, which result in high routing overhead and performance degradation due to low utilization of wireless links. This is because only gateway nodes are aware of all the network resources. In contrast, a unified routing protocol (e.g., optimal link state routing (OLSR)), which treats the nodes and links equally, can avoid the performance bottleneck incurred by gateway nodes. However, OLSR has to pay the price for unification, that is, OLSR introduces a great amount of routing overhead for broadcasting routing message on every interface. In this paper, we propose unified routing protocol (URP), which is based on passive bandwidth measurement for heterogeneous WMNs. Firstly, we use the available bandwidth as a metric of the unification and propose a low‐cost passive available bandwidth estimation method to calculate expected transmission time that can capture the dynamics of wireless link more accurately. Secondly, based on the estimated available bandwidth, we propose a multipoint relays selection algorithm to achieve higher transmission ability and to help accelerate the routing message diffusion. Finally, instead of broadcasting routing message on all channels, nodes running URP transmit routing message on a set of selected high bandwidth channels. Results from extensive simulations show that URP helps improve the network throughput and to reduce the routing overhead compared with OLSR and hierarchical routing. Copyright © 2016 John Wiley & Sons, Ltd.     

A novel wideband and circularly polarized cross‐dipole antenna

In this paper, we present a novel wideband circularly polarized (CP) composite, called cavity‐backed crossed dipole antenna for 2.45 GHz industrial, scientific, and medical (ISM) band wireless communication. To excite the CP radiation effectively, a curved‐delay line providing an orthogonal phase difference among the cross‐dipole elements is attached at corners of the sequentially rotated elements. By choosing a proper radius of the curved‐delay line, a wide input impedance of the antenna can be realized. Unlike conventional cross‐dipole antennas, the proposed cross‐dipole antenna is designed with an open stub added to the radiating arms of the dipole so that both impedance and axial ratio bandwidths are enhanced. The antenna is center‐fed by a 50‐Ω coaxial cable and is placed above a cavity‐backed reflector to obtain a directional CP radiation pattern. With the advantage of being center‐fed, a symmetric CP radiation pattern can be achieved across the entire operating bandwidth. To further improve the directivity and the radiation pattern, a rectangular cavity‐backed reflector is used. Simulated and measured results confirm that the proposed antenna has good CP characteristics. The proposed antenna obtains a broad 3‐dB axial ratio bandwidth of 49% (1.20 GHz, 1.96–3.16 GHz) and an impedance bandwidth of 67.7% (1.66 GHz, 1.69–3.35 GHz) for reflection coefficient (S₁₁) ≦ −10 dB. It also yields an average CP gain of 9.2 dBic across the operating bandwidth and a peak CP gain of 10 dBic. Copyright © 2016 John Wiley & Sons, Ltd.     

应用于电子乐器的不平衡——平衡转换器

利用公共交流电源为用电器供电是我们日常工作以及生活中必然的选择,由于不是完全各自独立的供电系统,这样用电器之间由于相互耦合的作用必然形成交流声和噪声环路。在此设计的这款＂不平衡——平衡转换器＂可以解决这个问题。该转换器电路中的省电电路系统也具有典型性。当然该转换器略加修改也可用于别的需要电气隔离的用电环境。     

非编网络的管理维护

非线性编辑技术,从非编单机到非编网络,现在已经发展到兼有高清功能的数字非线性编辑网络技术。阐述了电视非编网络的系统结构、技术要求,对电视台在非编网络建设和使用过程中的设备选型、系统架构及管理维护方面的问题做一些讨论。