基于上下文图模型文本表示的文本分类研究

传统的基于“词袋”的文本表示方法假定词的权重只和它本身的出现频率有关，而忽略上下文信息。 本文提出了一种基于上下文的图模型文本表示方法，使用一种类似PageRank的图模型来建立词和词之间的相 互推荐关系，该方法克服了传统文本表示认为词和词之间相互独立，忽略词的上下文环境的缺陷。在复邑中文 文本分类和20newsgroup英文文本分类的语料库上的实验表明，我们的方法可以有效地提升文本分类的性能。

模糊动态抢占调度算法

针对不确定任务特征,提出应用模糊理论进行动态抢占调度.用语言模糊集来描述任务的不确定特征和不同的优先级等级,利用最大隶属度原理确定任务的优先级等级,采用优先调度高优先级等级任务的调度策略提高重要任务的调度成功率,实现具有不确定任务特征的抢占调度.与传统的EDF和LSF算法相比较,仿真表明,所提算法能够提高重要任务的调度成功率,并降低重要任务的截止期错失率;同时,任务间的平均切换次数大大小于LSF的平均切换次数,而与EDF保持相当.该方法可应用于计算机控制系统的控制任务调度,并借鉴于其它具有不确定任务特征或具有有限优先级等级的实时调度问题研究中.

Study on the Dissociation Behavior of Gas Hydrate in Porous Sediment Based on Fractal Theory

The dissociation process of gas hydrate was regarded as a gas-solid reaction without solid production layer when the temperature was above the zero centigrade. Based on the shrinking core model and the fractal theory, a fractional dimension dynamical model for gas hydrate dissociation in porous sediment was established. The new approach of evaluating the fractal dimension of the porous media was also presented. The fractional dimension dynamical model for gas hydrate dissociation was examined with the previous experimental data of methane hydrate and carbon dioxide hydrate dissociations, respectively. The calculated results indicate that the fractal dimensions of porous media acquired with this method agree well with the previous study. With the absolute average deviation (AAD) below 10%, the present model provided satisfactory predictions for the dissociation process of methane hydrate and carbon dioxide hydrate.

Hydrogen production characteristics of the organic fraction of municipal solid wastes by anaerobic mixed culture fermentation

The hydrogen production from the organic fraction of municipal solid waste (OFMSW) by anaerobic mixed culture fermentation was investigated using batch experiments at 37 degrees C. Seven varieties of typical individual components of OFMSW including rice, potato, lettuce, lean meat, oil, fat and banyan leaves were selected to estimate the hydrogen production potential. Experimental results showed that the boiling treated anaerobic sludge was effective mixed inoculum for fermentative hydrogen production from OFMSW. Mechanism of fermentative hydrogen production indicates that, among the OFMSW, carbohydrates is the most optimal substrate for fermentative hydrogen production compared with proteins, lipids and lignocelluloses. This conclusion was also substantiated by experimental results of this study. The hydrogen production potentials of rice, potato and lettuce were 134 mL/g-VS, 106 mL/g-VS, and 50 mL/g-VS respectively. The hydrogen percentages of the total gas produced from rice, potato and lettuce were 57-70%, 41-55% and 37-67%. 2008 International Association for Hydrogen Energy.

高产抗旱优质谷子新品种辐谷7号的选育与推广利

利用400Gy 60Co γ射线处理87070谷子品系干种子,选育出辐谷7号新品种。该品种具有株型紧凑、茎秆矮、高产抗旱优质并且适应种植地区广等特点。2002年2月通过陕西省农作物品种审定委员会审定,截止2008年在黄土高原地区累计推广10.8万hm2。

径流曲线法在黄土区小流域地表径流预测中的初步应用

径流曲线法是目前国际上预测无径流观测资料地区降水地表产流的主要模型,由于气候、水文及下垫面的差异,在黄土高原地区的应用受到限制。利用黄土高原地区3个小流域的303场降雨径流资料,针对黄土高原降雨地表径流特点优化模型中的初损率λ,并提出降雨强度修正函数,将降雨强度因子引入径流曲线法。优化后的模型效率E达到0.812,实测径流深与预测径流深的线性回归决定系数R2达到0.822。改进后的SCS-CN模型可用于黄土区小流域降雨地表产流预报,对黄土高原无资料地区侵蚀产流预报、指导水土保持工程配置和设计具有重要的理论和工程实践意义。

InAs 单量子点精细结构光谱

在5 K下,采用光致发光光谱和时间分辨光谱研究了不同单量子点的精细结构和对应发光光谱的偏振性、单激子/双激子发光光谱和相应发光动力学.给出InAs单量子点发光光谱所对应能级的精细结构及激子本征态的偏振特性.当精细结构能级劈裂为零时, 激子的本征态为简并的圆偏振态.而当精细结构能级劈裂大于零时,一般在几十到几百μeV,激子的本征态为非简并的线偏振态.相对于单激子发光寿命,激子-激子间的散射使单激子的复合发光寿命减小.

基于SOA的交叉增益调制中探测光能量的数值分析

将Connelly提出的SOA稳态模型和Durhuus提出的动态数值方法结合起来,分析了交叉增益调制过程中连续探测光的输入能量对转换信号的影响.模拟结果表明,当连续探测光的输入能量较小时,转换信号的消光比较大,而且半高全宽不变.

准连续5kW叠层激光二极管列阵

报导了5kW GaAs/AlGaAs叠层激光二极管列阵的制作过程和测试结果。通过金属有机物化学气相沉积方法实现分别限制单量子阱结构。1cm激光条的填充密度是70%。采用80个激光条叠层封装，激光条间距是0.5mm，功率密度达1.25kW/cm~2，峰值波长是809.0nm，谱线宽度是4.8nm。

瞬态C-V方法对Al_xGa_(1-x)As中DX中心的研究

于2010-11-23批量导入