Cutoff rate and outage probability performance comparisons between DVB-T and DMB-T systems under mobile multipath channels

As an effective technique for combating multipath fading and for high-bit-rate transmission over wireless channels, orthogonal frequency-division multiplexing (OFDM) is extensively used in modern terrestrial digital television broadcasting systems to support high performance bandwidth-efficient multimedia services. Cutoff rate and outage probability are two important criteria to evaluate the performance of a practical communication system in radio engineering. In this paper, the cutoff rate and outage probability performance are compared between two important terrestrial digital television broadcasting systems, the cyclic prefix OFDM based DVB-T system and the time domain synchronous OFDM based DMB-T system, under different mobile multipath channel conditions. The DVB-T system and the DMB-T system are summarily introduced. The cutoff rate and outage probability expressions are developed, and simulation results are given for both the DVB-T system and the DMB-T system.     

COLOR VISION SYSTEM FOR RIPENESS INSPECTION OF OIL PALM ELAEIS GUINEENSIS

In checking harvesting discipline and quality control for oil palm fruits, color has presumably been an important guide to whether the oil content has reached a maximum where the fruit bunch is ready for cutting. However, establishing a single and harmonious standard base on color is a very contentious issue in the oil palm industry because of the subjective nature of the human vision of color. This was further complicated due to the lack of information on fruit color upon which to base a definite ripeness criterion. We demonstrated in this paper that this problem can be solved using machine vision technology. Methods used were to treat color in HSI (Hue, Saturation and Intensity) color space and applied multivariate discriminant analysis. These have proven to be highly effective for color evaluation and image processing. The vision system was trained to classify oil palms into four quality grades according to PORIM (Palm Oil Research Institute of Malaysia) inspection standards. These are the unripe, the underripe, the optimally ripe and the overripe classes. Depending upon the quality feature evaluated, misclassification by the vision system varied from 5 to 12% but averaged at about 8%. Machine vision disagreement ranged from 2 to 19%.     

Design of a 3780-point IFFT processor for TDS-OFDM

This correspondence presents a design of 3780-point IFFT processor for TDS-OFDM terrestrial DTV transmitter using FPGA. It demonstrates the algorithm design and error analysis of the processor, which can achieve a throughput of 7.56M complex IFFT operations per second. This design meets the signal-to-quantization noise ratio requirement of the TDS-OFDM system. It consists of two FPGA and one dual-port RAM. The data stream pipeline algorithm is implemented     

比较CypherTM和TaxusTM支架在冠心病合并糖尿病患者中应用的安全性和有效性

背景与裸支架相比,药物洗脱支架可以显著降低冠心病合并糖尿病患者PCI术后再狭窄率和靶病变重建率.但目前尚未见关于直接比较雷帕霉素洗脱支架(CypherTM)和紫杉醇洗脱支架(TaxusTM)在治疗冠心病合并糖尿病患者中安全性和有效性的研究.目的观察和比较两种药物洗脱支架在冠心病合并糖尿病患者中应用的安全性和有效性.方法自2002年6月～2004年2月新加坡国立大学医院心脏中心所有置入Cypher或Taxus支架冠心病合并糖尿病患者,观察:术后6个月的主要不良心脏事件(包括死亡、心肌梗死、靶病变重建).结果     

Effect of bismuth on the growth kinetics of intermetallic compounds in Sn-3.5Ag solder joints: A growth kinetic model

The effect on the growth kinetics of the intermetallic compounds (IMCs) in solder/Cu joints, caused by adding Bi to eutectic Sn-3.5Ag solder alloy, was examined at the aging temperatures of 150°C and 180°C. The Cu₆Sn₅ layer growth was significantly enhanced, but the Cu₃Sn layer growth was slightly retarded by the addition of Bi, resulting in significant growth enhancement of the total (Cu₆Sn₅+Cu₃Sn) IMC layer with increasing Bi addition. The IMC layer growth in the Bi-containing solder joints was accompanied by the accumulation of Bi ahead of the Cu₆Sn₅ layer that resulted in the formation of a liquid layer at the Cu₆Sn₅/solder interface. A kinetic model was developed for the planar growth of the Cu₆Sn₅ and Cu₃Sn layers in the solder joints, accounting for the existence of interfacial reaction barriers. Predictions from the kinetic model showed that the experimental results could be well explained by the hypothesis that the formation of a Bi-rich liquid layer at the Cu₆Sn₅/solder interface reduces the interfacial reaction barrier at the interface.     

受限接收缓存下CMT稳态吞吐量建模与分析

多路径并行传输(CMT)是一个基于流控制传输协议(SCTP)的新传输协议,它使用SCTP协议的多宿特性,在一条端到端偶联中的多条路径上并行地进行数据分发,相对单路径传输具有聚合带宽、可以提高端到端吞吐量的优点.文中针对受限接收缓存下发送窗口是否受接收窗口影响两种情况分别对多路径并行传输进行建模,提出了基于发送窗口和接收窗口关联的CMT吞吐量模型.首先以轮为单位,分别对两种情况下的超时阶段、慢开始阶段和拥塞避免阶段的拥塞窗口进行了分析.其次,综合3个阶段传输情况,得到1个多路径并行传输过程中,稳态吞吐量关于RTT、RTO和丢包率的函数关系,它能够很好地估计多路径并行传输协议在受限接收缓存下稳态吞吐量.最后,通过仿真实验和结果分析验证了多路径并行传输吞吐量模型的有效性和准确度.     

面向多模态函数优化的自适应小生境遗传算法

为了解决小生境遗传算法不能准确识别小生境的缺陷,以及算法无法有效平衡快速收敛和保持种群多样性的冲突问题,提出一种自适应小生境遗传算法.在算法中,设计一种改进的小生境识别方法来确定小生境范围,引入用于度量种群多样性的小生境熵概念,并利用小生境熵自适应调整进化参数的取值.同时,改进选择、交叉策略,在识别的小生境基础上将交叉分为境外交叉和境内交叉,用于提高算法的全局搜索能力和局部收敛速度.实验表明,算法对于解决多模态函数优化问题具有收敛速度快和计算量小等优点,能够有效避免遗传漂移现象.     

General pole restriction controller design

Pole-assignment controller design suffers from the disadvantage that the prescribed pole locations may not be a suitable choice when the dynamics of the process are changing. A general design method that restricts the closed-loop poles to be within a certain desired region specified by engineering judgement, instead of fixing the poles in a prescribed location, is presented. The method can be used for regulating a process with time delay, non-minimum zero-phase behaviour, and open-loop unstable characteristics.