Iterative detection/decoding for two-track partial response channels

In this letter, we investigate the iterative detection/decoding algorithms for two-track partial response channels. We first describe the iterative algorithm as an iterative message-passing/processing algorithm over a high-level normal graph and then propose two trellis-based detection algorithms. The natural one is based on a joint trellis, which can be implemented for low-order channels. For moderate-order channels, we propose a separated detection, which is based on two single-track trellises. Compared with the joint detection, the separated detection is simpler in most cases. Simulation results show that, for two-track EPR4 channels with minor intertrack interferences, the separated detection causes only marginal degradation in performance.     

CHAOTIC HYDRODYNAMICS IN HORIZONTAL GAS-LIQUID BUBBLY FLOW

ＮＯＭＥＮＣＬＡＴＵＲＥｄ———ｅｍｂｅｄｄｉｎｇｄｉｍｅｎｓｉｏｎ ,ｄｉｍｅｎｓｉｏｎｌｅｓｓＣｄ(ｒ)———ｃｏｒｒｅｌａｔｉｏｎｓｕｍ ,ｄｉｍｅｎｓｉｏｎｌｅｓｓＮ———ｎｕｍｂｅｒｏｆｐａｉｒｓｏｆｐｏｉｎｔｓｏｎｔｈｅｒｅｃｏｎ ｓｔｒｕｃｔｅｄａｔｔｒａｃｔｏｒ,ｄｉｍｅｎｓｉｏｎｌｅｓｓｒ———ｓｃａｌｉｎｇｄｉｓｔａｎｃｅ ,ｄｉｍｅｎｓｉｏｎｌｅｓｓＤｃ ———ｃｏｒｒｅｌａｔｉｏｎｄｉｍｅｎｓｉｏｎ ,ｄｉｍｅｎｓｉｏｎｌｅｓｓＫ———Ｋｏｌｍｏｇｏｒｏｖｅｎｔｒｏｐｙ ,ｂｉｔｓ/ｓＲ…     

新型的芯片间互连用CMOS/BiCMOS驱动器

从改善不同类型 IC芯片之间的电平匹配和驱动能力出发 ,设计了几例芯片间接口 (互连 )用 CMOS/Bi CMOS驱动电路 ,并提出了采用 0 .5 μm Bi CMOS工艺 ,制备所设计驱动器的技术要点和元器件参数。实验结果表明所设计驱动器既具有双极型电路快速、大电流驱动能力的特点 ,又具备 CMOS电路低压、低功耗的长处 ,因而它们特别适用于低电源电压、低功耗高速数字通信电路和信息处理系统。     

黄河龙口水利枢纽坝基岩体钙质充填夹层地质分析与试验研究

龙口水利枢纽坝基岩体主要由奥陶系中统马家沟组(O2m2)灰岩组成,其中发育有多层软弱夹层。作为其中之一的钙质充填夹层,强度虽不很低,但由于处于坝基下的持力层内,间距不大,发育密集,产状平缓,是坝基浅层抗滑稳定的主要控制因素,因此,在大坝抗滑稳定分析时,应进行分析和研究。     

西北低煤阶盆地生物成因煤层气成藏模拟研究

在美国粉河、澳大利亚苏拉特等低煤阶盆地煤层气勘探取得突破以前,一直认为具有商业价值的煤层气资源主要存在于中煤阶的煤层中,煤阶太低,一般含气量不高,不具有勘探价值。但是近几年来的发现证实,低煤阶盆地煤层厚度大,渗透率高,资源丰度大,含气饱和度高,同样可获得商业性气流,而且从其气体的成因来看,其中有很大一部分是生物成因的煤层气。利用煤层气成藏模拟装置对低煤阶含煤盆地的煤岩样品开展成藏模拟,从实验角度证明了中国西北地区虽然煤层煤阶较低,热成因气较少,但是却存在着具有商业价值的二次生物成因的甲烷气,再加上含煤层系众多,煤层厚度大,资源丰度极高,仍具有巨大的勘探潜力。      

可拆装高架火炬的应用

结合工程实例,介绍了我国第一座可拆装高架火炬的基本原理及组成,并对可拆装高架火炬与普通高架火炬在安全、技术、安装、维修、占地面积、投资等方面进行了比较,还分析了高架火炬未来的发展趋势.     

井下电视检测系统在水井施工中的应用

简要介绍了井下电视在大港油田水源井水井结构检测、井管故障检测、指导落物打捞、水源井验收、地层结构检测及水源井地层受力分析等方面的应用情况，及应用井下电视检测所取得的经济效益和社会效益。     

VLF相位周期滑移现象的观测与分析

分析了新乡观测到的VLF相位周期滑移现象,研究了产生相位周期滑移的原因,揭示了相位周期滑移的实质:VLF传播相位周期滑移是发生在日出或日落过渡期间一种特殊的多模干涉现象,它是由传播路径昼夜分界处的低电离层不连续性所引起的模转换干涉所造成的.     

Packet Design and Signal Processing for OFDM-Based Mobile Broadband Wireless Communication Systems

We consider improving the performance of orthogonal frequency-division multiplexing (OFDM)-based mobile broadband wireless communication (MBWC) systems. We show that a recently approved packet-based MBWC standard can cause the resulting systems to suffer from severe performance degradations for time-varying channels due to the lack of a mechanism for tracking the time-varying channels needed for coherent detection. We consider both packet design and signal processing to deal with time-varying channels. For the packet design, we segment an entire packet into multiple subpackets—with each subpacket having zero tail bits to reset the convolutional channel encoder—so that the detection/decoding result of each subpacket can be used to update the channel response for this subpacket. For signal processing, we use weighted polynomial fitting and prediction at the receiver to improve the channel tracking accuracy. Simulation results show that the coherent detection based on our new scheme can significantly outperform the commonly suggested differential modulation/detection methods.     

Comments on "An efficient PML implementation for the ADI-FDTD method"

For original paper see Wang and Teixeira (IEEE Microwave Wireless Comp. Lett., vol.13, p.72-4, 2003 February). In this paper, a more precise way to evaluate the actual performance of the perfectly matched layer (PML) used for the alternating direction implicit finite-difference time-domain (ADI-FDTD) method is presented. It is shown that the intrinsic numerical dispersion error of the ADI-FDTD method must be taken into account when the actual performance of the ADI-PML (as well as the ADI-FDTD method) is evaluated. Most importantly, it is demonstrated that the ADI-PMLs implemented with either the traditional manner or the way proposed in have almost the same level of accuracy when the performance of the ADI-PML is correctly evaluated.