一种基于SVM的网页层次分类算法

设计了一种基于统计的多层次分类算法:在一个树状的层次分类体系中,对文档进行自动分类时,首先从根结点开始找到对应的大类,然后递归往下直到找到对应的最底层子类.每一层中使用支持向量机作为分类模型,并使用类别均衡的方法解决数据稀疏的问题,在经过大规模网页语料训练后取得了很好的分类效果.     

Equivalent Model, Error Analysis, and Design Steps of AGC Loop for MM-Wave Receiver

Automatic Gain Controlled (AGC) Loops are used in MM-Wave receiver in wide-ranging. In this paper, the equivalent model and loop equation of AGC Loop are built, the loop errors are analyzed and then the design steps of AGC Loop are given out.     

降水“阈值”对黄土高原全新世以来C4/C3植物相对丰度的控制（英文）

黄土高原地区C4/C3植物相对丰度变化的主要驱动因素曾被广泛地争论,主要是由于对该区域现代C4/C3植被分布的空间特征及其驱动因素缺乏深入认识.本文总结了前人对黄土高原中部和东南部剖面的δ13Csom研究结果,并增加2个西北部剖面的δ13Csom结果,结合现代气象数据和表土δ13Csom变化特征,从空间变化讨论黄土高原地区C4/C3植被分布特征及驱动因素.末次冰期以来,西北部的古浪和靖远剖面主要发育C3植被,而中部和东南部的剖面则为C3-C4植被混合的特征,且C4植被含量从东南向西北递减.我们认为晚冰期以来,黄土高原地区的温度逐渐升高并达到C4植被生长的温度"阈值",同时大气CO2浓度也处在适宜C4植被生产的低浓度范畴,则夏季降水的梯度变化应该是控制全新世和现代黄土高原东西部植被类型变化的主要因素,并同样存在一个影响C4植被生长的降水"阈值",进一步通过现代夏季降水量对全新世C4植被扩张时期的夏季降水量进行定量恢复,我们发现,无论在全新世还是现代,当夏季降水超过360 mm时,C4植被会发生明显的扩张,而现代的360 mm降水线较全新世向东南方向偏移.     

Study of LMDS Videoconferencing System

LMDS is one kind of fixed broadband wireless access network. It uses radio spectrum between 10GHz and 40GHz to transmit voice, video, and data signals within small cell 3-10 miles in diameter. This paper proposes some key technical scenarios to support videoconferencing services transported on LMDS. Firstly, two kinds of typical LMDS lower layer standards made by DAVIC and 802.16 separately are discussed from the angle of supporting video conferencing services. Then, H.323 is studied and recommended as the standard of LMDS video conferencing system. And some strategies are proposed to support H.323 services on LMDS. After that, IP multicast technology, the key supporting technology of H.323, is studied from the angle of running on LMDS. Scenarios for IGMP, RMTP protocol running on LMDS are suggested and analyzed with Markov network queuing theory. The technical scenarios proposed by this paper make use of the transporting property of LMDS to support LMDS videoconferencing system more effectively.     

Dynamical behaviors of Hopfield neural network with multilevel activation functions

When the activation function possesses multilevel property, the Hopfield neural network has some novel dynamical behaviors, and it is worthwhile to study. First, some properties about the activation function are obtained, on this foundation, some theoretical analysis about the quasi-equilibrium points has been made. From local and global view, some theorems about the boundedness are presented. Finally, two theorems about the first derivative of trajectory with respect to time are found, the first theorem indicates that the trajectory cannot keep increasing or decreasing for time t > t₀, the second theorem is about the complete stability of the trajectory.     

嵌入式ADC电磁敏感度的温度效应分析与实验

模数转换器(ADC)在测控系统中应用广泛,针对嵌入式ADC复杂环境下的电磁敏感性问题,通过理论分析和实验测量研究了环境温度对其电磁敏感度的影响。结合ADC结构与特性,分析了射频信号对ADC的干扰机制,指出了环境温度对干扰信号作用下的金属氧化物半导体(MOS)漏电流的影响。在不同温度下,测量、分析了电磁干扰下各部分电路参数的变化情况。并在10 MHz~1 GHz频率范围、-10~80 ℃温度范围内测量了ADC电磁敏感度的温度效应。结果表明,变化的环境温度会通过影响MOS晶体管的迁移率,改变其在电磁干扰下的响应,造成ADC电磁敏感度随环境温度变化发生显著漂移。     

毛细管柱气相色谱法同时测定白酒中的醇、酯

采用HP-INNOWax石英毛细管柱直接进样,氢火焰离子化检测器检测,内标法定量,建立了毛细管气相色谱同时测定白酒中的甲醇和杂醇油、乙酸乙酯和己酸乙酯的分析方法。方法的平均回收率为83．4％-100．8％,RSD为0.39％-3．07％（n=6）。该方法适用于白酒中甲醇和杂醇油、乙酸乙酯和己酸乙酯的同时分析测定。     

Multiquantum vibrational excitation of NO scattered from Au(111): quantitative comparison of benchmark data to ab initio theories of nonadiabatic molecule-surface interactions

Surface phenomena: measurements of absolute probabilities are reported for the vibrational excitation of NO(v=0→1,2) molecules scattered from a Au(111) surface. These measurements were quantitatively compared to calculations based on ab?initio theoretical approaches to electronically nonadiabatic molecule-surface interactions. Good agreement was found between theory and experiment (see picture; T(s) =surface temperature, P=excitation probability, and E=incidence energy of translation).     

基于有机/无机杂化钙钛矿有序结构的异质结及其光伏性能的研究

研究了一种新型的有机/无机杂化钙钛矿材料(3-BrC₃H₆NH₃)₂CuBr₄薄膜的聚集态形貌和良好的微观有序性特征, 霍尔迁移率测试结果表明该材料为p型半导体, 空穴迁移率为0.0025 cm²•V^－1•s^－1. 利用其在紫外-可见光谱范围内与C₆₀薄膜具有良好的光吸收互补性, 制备并研究了(3-BrC₃H₆NH₃)₂CuBr₄/C₆₀层状异质结结构中的暗态传输和光伏性能. 对不同退火温度下杂化钙钛矿薄膜的聚集态特性和器件性能之间的联系进行了探讨, 结果表明在低温退火条件下, 由于钙钛矿结构材料中有机组分排列更加有序, 器件显示更好的性能.