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.     

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.     

有机酸指纹图谱结合化学计量学分析鉴定黄酒的方法研究

目的 建立不同黄酒的高效液相有机酸指纹图谱,并结合化学计量学分析对黄酒进行鉴别研究。方法 采用Diamonsil Plus C18(150mm×4.6mm,5μm)色谱柱,以磷酸(0.1%)-甲醇(98∶2,v/v)为流动相,流速0.55 mL/min等度洗脱,30℃,检测波长200nm及210nm 检测不同黄酒中的有机酸;采用ChemPattern先进化学计量学系统解决方案软件对有机酸图谱进行多元统计分析及相似度阈值分析,建立模式识别,最终完成对不同黄酒的鉴别。结果 4种不同类型黄酒有机酸指纹图谱共有模式包含36个峰,其中8个色谱峰进行了鉴别,并初步对确认的峰进行了含量测定。结果显示,多种分析方法的分类结果准确一致,可有效对共有模式下的黄酒进行鉴别及初步质量评价。结论 该方法简便易行、准确可靠,适用于共有模式内黄酒的鉴别评价。     

电镀锌钢材表面物理气相沉积Zn-Mg合金镀层的电化学性能(英文)

锌合金镀层由于具有较强的耐腐蚀性能而得到广泛的关注,特别是Zn-Mg合金镀层,其耐腐蚀性能能得到显著提高。采用气相沉积方法制备不同镁含量的Zn-Mg合金镀层,研究Zn-Mg合金镀层中镁含量对其耐腐蚀性能的影响。在3%NaCl溶液中进行浸泡试验、动电位测试和电偶腐蚀试验,研究不同Mg含量镀层的耐腐蚀性能。结果表明,Zn-Mg合金镀层的耐腐蚀性能与Mg含量显著相关,镀层的腐蚀电位随着Mg含量的增加而降低,但是腐蚀电流密度却升高,直至15%Mg含量;在Zn-Mg合金镀层中存在钝化区。