Dual mode wideband band-pass filter with notched band for communication system

This paper presents a planar microstrip wideband dual mode Band-Pass Filter (BPF) from 2 GHz to 3.4 GHz with a notched band at 2.62 GHz. The dual mode band-pass filter consists of a ring resonator with two quarter-wavelength open-circuited stubs at ?? =90° and ?? =0°, respectively. A square perturbation stub has been put at the corner of the ring resonator to increase the narrow stopbands and improve the performance of selectivity. By using a parallel-coupled feed line, a narrow notched band is introduced at the required frequency and its Fractional BandWidth (FBW) is about 5%. The proposed filter has a narrow notched band and a wide pass-band with a sharp cutoff frequency characteristic, the attenuation rate for the sharp cutoff frequency responses is 297.17 dB/GHz (calculated from 1.959 GHz with ?34.43 dB to 2.065 GHz with ?2.93 dB) and 228.10 dB/GHz (calculated from 3.395 GHz with ?2.873 dB to 3.507 GHz with ?28.42 dB). This filter has the advantages of good insertion loss in both operating bands and two rejections of greater than 16 dB in the range of 1.59 GHz to 1.99 GHz and 3.49 GHz to 3.98 GHz. Having been presented in this article, the measurement results agree well with the simulation results, which validates our idea.     

A Stochastic Approximation Approach to the Power-Control Problem

This paper proposes and analyzes a new distributed power-control algorithm based on the theory of stochastic approximation. The power-control problem is first converted into a stochastic approximation problem in which the zero point of a specific function is determined. A distributed power-control algorithm is then derived and its convergence properties are analyzed using standard techniques. In the distributed algorithm, each user iteratively updates its power level by using estimates of the inverse of the signal-to-interference ratio (SIR) of its channel. No knowledge of the channel gains or state information of other users is required. Moreover, the algorithm is robust in the sense that it can handle errors in the bit-error rate estimates, and hence, can be used in practical scenarios. Convergence of the algorithm is analyzed in the almost-sure sense     

灰岩含水饱和度对纵、横波速度变化影响的实验研究

该实验是以灰岩作为试样,用超声岩石参数测定仪测量此试样在不同的含水饱和度下纵、横波传播的速度,获得了纵、横波速度和纵、横波速度比与含水饱和度的关系：①纯灰岩和泥质条带灰岩的纵波速度V_P与含水饱和度S_W之间成正比关系;②横波速度V_S与含水饱和度S_W之间成反比关系;③当灰岩试样饱含水时,V_P/S_S的值均大于2;④当灰岩试样饱含气时,V_P/V_S的值均小于2;⑤在试样含水饱和状态时,纯灰岩(孔隙率小)的V_P/V_S值大于泥质条带灰岩(孔隙率大)的V_P/V_S值。我们利用上述关系,可鉴别地层中的流体含量。对岩石固结程度差的地层,还可用纵、横波速度比与含水饱和度的关系划分出油、气、水层。     

WiMAX MMR网络的军事应用

为进一步提高战术通信网的性能,满足通信保障对网络传输带宽的需求,许多国家的军队使用了3G标准之一的WiMAX技术。WiMAX MMR网络基于IEEE802.16j标准,运用移动多跳接力技术,能有效解决现有WiMAX系统覆盖半径不足、信号传输不佳的问题。介绍WiMAX在军事通信领域的应用情况,结合IEEE802.16j MMR的特点,并就网络安全方面所面临的威胁提出了应对策略。分析表明:WiMAX MMR网络作为一种无线解决方案,具有良好的军事应用前景。     

在基于GMPLS的无源光网络中支持端到端QoS

文章首先对下一代网络技术的发展趋势以及IETF服务质量（QoS）机制进行了简单介绍,然后对现有无源光网络技术对端到端QoS支持的不足进行了总结,提出了基于通用多协议标签交换（GMPLS）的无源光接入网QoS服务模型。通过在接入网中引入GMPLS通用控制和管理平台,建立了统一的QoS服务模型,实现了对端到端QoS的有效支持。     

一种在电路SOC验证接口设计方法研究

SoC已经成为嵌入式系统设计中的关键器件,验证又是SoC设计的关键环节,占用SoC设计过程中60%以上的时间.专用测试设备及JTAG接口等主流SoC验证手段不便于SoC在系统联调时的验证.本文介绍了一种在电路SoC验证接口的设计方法,这种验证方法弥补了主流SoC验证方法在系统验证的不足,提高了SoC验证的效率.     

Electrochemical Oxidation of 5-Hydroxymethylfurfural on CeO2-Modified Co3O4 with Regulated Intermediate Adsorption and Promoted Charge Transfer

Electrocatalytic 5-hydroxymethylfurfural oxidation reaction (HMFOR) can replace the kinetically slow oxygen evolution reaction to yield high value-added chemicals. In this study, interface engineering is constructed by modifying CeO₂ nanoparticles on Co₃O₄ nanowires supported by nickel foam (NF). The construction of the heterointerface can facilitate the structural evolution of catalysts and charge transfer, as a result, the successfully synthesized NF@Co₃O₄/CeO₂ exhibits higher 5-hydroxymethylfurfural conversion (98.0%), 2,5-furandicarboxylic acid (FDCA) yield (94.5%), and Faradaic efficiency (97.5%) at a low electrolysis potential of 1.40 V_RHE compared to NF@Co₃O₄ and NF@CeO₂. Density-functional theory calculations indicate that the establishment of heterointerface can effectively regulate the intermediate adsorption and promote electron transfer, which greatly reduces the activation energy of the dehydrogenation step in 5-formyl-2-furancarboxylic acid (FFCA), and promotes the further oxidation of FFCA to FDCA, thereby improving the performance of HMFOR. In this study, the HMFOR behavior of the Co₃O₄/CeO₂ interface effect is deeply explored, which provides guidance for the future design of heterointerface catalysts with efficient HMFOR performance.     

激光雷达能见度仪数据采集系统的研制

目前的激光雷达能见度仪基本上都是靠通用数据采集卡进行数据采集,使用起来多有不便.针对这一现状,研制了一套适用于激光雷达能见度仪的专用数据采集系统.系统硬件基于FPGA设计,通过硬件逻辑实现计数、触发和数据存储.系统通过USB2.0高速接口与计算机连接,数据传输速度快、连接方便且支持热拔插.采集软件为采用LabWindo...     

高压直流接地极对管道电磁阀的干扰影响研究

针对高压直流输电(HVDC)接地极处于单极大地回路运行工况下,很大的入地杂散电流可能产生电磁阀发生误动作的风险,影响管道正常运行。建立了传导干扰对电磁阀线圈影响的数学模型,研究了直流杂散电流引起电磁阀误动作的机制。采用数值模拟的方法,建立国内某1 100 kV特高压直流输电工程接地极对附近管道干扰的仿真模型,并设计了管地电位实时数据采集系统。仿真及现场测试结果表明,干扰电压以接地极距离管道最近位置为中心,依次向上下游递减;冬季电磁阀受到的直流干扰是夏季的3.43倍;仿真结果和实测结果基本吻合,误差在10%以内;沿管线增设4个和6个绝缘接头后使得管地电位差降低62.1%、71.4%。为可靠预防电磁阀异常工作,在冬季应该加强阀室巡检,并沿管道上下游适当位置安装绝缘接头。     

Extending Anisotropic Perfectly Matched Layer Absorbing Boundary Condition to Biaxial Media

The absorbing boundary condition required for an anisotropic perfectly matched layer for materials that exhibit a uniaxial and biaxial permittivity tensor is investigated. These materials are used in optical and millimeter wave devices and other particular situations such as in the construction of modern aircraft and automobiles. The derivation presented in this paper may be not suitable for all the arbitrary orientations but for many common situations. The effectiveness of the condition is also illustrated with examples by the finite-difference and finite-element method.