发光二极管负电容与角频率的关系

利用正向交流(AC)小信号方法对发光二极管(LED)的电容-电压特性进行测量,可以观察到发光二极管中的负电容现象.提出了测量到的负电容现象是表象,不存在负电容;发光二极管p-n结的结电容在特定的正向电压范围内等效于可变电容.分析可变电容对交流小信号响应得到:特定参数的可变电容使电流的相位移相π,使得在测量中表现为负电容;得到了发光二极管负电容与角频率的关系表达式.     

基于海杂波FRFT谱多尺度Hurst指数的目标检测方法

本文主要研究海杂波分数阶Fourier变换（FRFT ）谱的扩展自相似特性及FRFT域多尺度Hurst指数在海杂波目标检测中的应用。鉴于扩展自相似过程的描述参数---多尺度Hurst指数可以描述分形信号在各尺度下的细节信息,本文基于实测雷达数据研究海杂波FRFT谱的扩展自相似性以及影响参数,并利用最优FRFT域尺度下多尺度Hurst指数对目标较敏感的特点设计海杂波中目标的恒虚警检测方法。经实测数据验证,海杂波FRFT谱的多尺度Hurst指数比时域单一Hurst指数、时域多尺度Hurst指数具有更好的海杂波与目标区分能力,并且由于FRFT可以很好地积累匀加速类目标回波的能量,有效提升信杂比,因此该检测方法具有检测海杂波中微弱运动目标的潜力。     

Modeling single chain elasticity of single-stranded DNA: A comparison of three models

The dominant models of polymers, i.e., the freely jointed chain (FJC) model, the wormlike chain (WLC) model and the freely rotating chain (FRC) model are modified by integrating the inherent single-molecule elasticity obtained from quantum mechanics (QM) ab-initio calculations. The QM modified models have been utilized to generate fitting curves for single-stranded DNA obtained in organic solvent. The analyses on the deviation between the fitting curve and the experimental force curve demonstrate that the QM-FRC and QM-FJC model are suitable for ssDNA, but not the QM-WLC model. We also find that one repeating unit of ssDNA is corresponding to a Kuhn segment in QM-FJC model or two rotating units in QM-FRC. Having close correlation to the inherent elasticity and real molecular structure of the polymer, QM-FJC and QM-FRC are emerging as structure relevant models.     

Solid polymerization and supramolecular chirality formation of azobenzene substituted diacetylene Langmuir–Blodgett films

An azobenzene mesogen-substituted diacetylene (NADA) monolayer has been transferred onto the solid substrate by the traditional Langmuir–Blodgett (LB) method. Solid-state polymerization of NADA LB films can be sensitized in visible light region. In situ UV–vis absorption measurement enables us to study polymerization kinetics of NADA LB films. The polymerization process can be described as a first order rate equation and polymerization rate constants are characterized in detail. Furthermore, achiral NADA molecules can form chiral LB films through overcrowded packing of the azobenzene moiety.     

某住宅楼桩基工程事故分析与处理

通过分析某住宅楼桩基承载力未达到设计要求的原因 ,提出了桩基施工时注意事项。     

Separation of nickel, cobalt and copper by solvent extraction with P204

Separation of nickel, cobalt and copper by solvent extraction with P204@钱东 @王开毅 @潘春跃 @唐有根 @蔡春林 @蒋金枝~~Project ( 99JJY2 0 0 10 )supportedbytheNaturalScienceFoundationofHunanProvince     

福州软土固结状态初步分析

利用卡氏作图法可求取土层的前期固结压力Pc,结合计算出的土层自重压力Po,可获得土层的超固结比OCR.在收集有关资料的基础上,对福州软土的前期固结压力和超固结比进行数理统计和对比分析,进而对各层软土的固结状态作出评价和分析.     

基于Video Charger视频点播系统的设计与实现

探讨了VideoChagrger的逻辑组成、交互与配置方式，及详细的资源需求分析，给出了据此建立VOD系统的系列解决方案。     

国产200 MW机组改汽动给水泵热经济性对比分析

下花园发电厂对国产２００ＭＷ汽轮机组和汽动给水泵必需 国内尚属首次。该项目应用普遍，涉及面广，具有重要的经济意义，结果值得借鉴。为此，根据下花园发电厂１９９８年７月进行的汽动泵与电动泵的工业性对比试验结果，该项目进行了热经济性分析和对比性研究。     

连续包覆型腔内应变分布的三维光塑性实验研究

以聚碳酸酯为模型材料, 首次采用三维光塑性方法对连续包覆型腔内金属流动过程进行了模拟实验研究,给出了稳态变形阶段型腔内的三维应变分布。分析了型腔内应变分布的特点,给出了金属在型腔内的流动规律