基于ALTERA CPLD的单稳态脉冲展宽电路

主要介绍了CPLD设计单稳态窄脉冲展宽电路的详细过程和这种单稳态窄脉冲展宽电路的特点,给出了相应的时序仿真波形和计数器的VHDL语言设计。     

遥感在确定水质参数中的应用进展

论述了应用遥感技术确定水质参数的原理和方法 ,阐述了悬浮颗粒物、叶绿素等几种水质参数的遥感监测方法与现状 ,提出了遥感监测水质的发展方向与展望     

应力法剪切模具CAD和动态仿真系统的设计

基于应力法剪切技术的理论及CAD和仿真技术原理 ,提出了一种在微机上开发的基于Windows98/NT的剪切模具的CAD和动态仿真系统的平台 .着重介绍了本平台的总体设计思路、体系结构和功能模块 ,实现了剪切模具结构的计算、设计、有限元分析、仿真及装配图一体化集成技术     

煤粉炉内扩散火焰关于大尺度涡的“砂轮”效应初探

以110MW、四角切向喷射的煤粉动力锅炉为对象,借助CFX4.2软件,在α-250工作站对该型锅炉的燃烧过程开展了数据模拟研究,研究发现：在该型炉膛内存在某种由准强制涡和准自由涡所组成的涡结果,这些涡均属于大尺度涡（非亚格子涡）;在这些准强制涡和准自由涡即大尺度涡之间以及某些涡与固壁或涡与喷射气流之间因扩散燃烧及强剪切而导致局部火焰增强现象即所谓“砂轮”效应,从Zeldovich转换和广义Reynolds比拟及粘性耗散的角度,定性地分析了这一效应。     

出口企业的具有状态非独立效用的套期决策

探讨了由于汇率的随机波动而面临着收益风险的风险厌恶竞争性出口企业的行为,这类企业可进入无偏差的外汇无期市场,在那里对外汇风险进行无成本套期保值。通过引入状态依赖效用拓展了标准方法并考察了众所周知的分离理论和全套期理论在这种一般化框架中是否仍然成立。     

煤粉锅炉燃烧工况的数值模拟及其优化研究

以110MW 、四角切向喷射的煤粉动力锅炉为对象,借助CFX4．2软件,在α－250工作站对该型锅炉的均等配风、正宝塔配风及腰鼓配风等三种燃烧工况开展了数据模拟研究。研究发现：正宝塔配风及腰鼓配风工况较均等配风工况更易着火,但均等配风工况较之正宝搭配风及腰鼓配风工况可获得略高的烟气温度;在（煤粉锅炉的）浓相一次风（口）附近,炉膛1^#角、3^#角上着火距离略小于炉膛2^#角、4^#角处的着火距离。     

Chain‐Length Dependence of the Electrochemical Properties of Conjugated Oligofluorenes

Summary: Electrochemical properties of monodisperse oligofluorenes ( OF n , n = 2 to 7) and corresponding polyfluorene were studied by cyclic and differential pulse voltammetry. In combination with data of UV‐vis absorption spectra, a series of linear relations such as the band gap, the oxidation potential, the ionization potential, and the electron affinity with the reciprocal number of the fluorene units (1/n) were deduced. When a chain length of ca. 14 repeat units is reached, a stable structure of about one positive charge per 3.5 repeat units is obtained.

     

Effect of Turbulent Flow on Coil‐Globule Transition of λ‐DNA

Summary: The addition of spermidine (SPD) into turbulent flow as a condensing agent showed the abrupt change of turbulent drag reducing (DR) efficiency of λ‐DNA in turbulent flow for the first time. The resultant asymptote DR efficiency explains the origin of those changes, which can be conclusively verified via the electrophoresis experiment. Despite the different fluid conditions, with and without condensing agent, all λ‐DNA molecules possessed the same half‐cut dimension, implying that the discrete change of DNA conformation can dramatically alter the flow characteristics.

Coil‐globule transition of DNA by spermidine.     

Laser-induced fluorescence studies of polycyclic aromatic hydrocarbons (PAH) vapors at high temperatures.

In this work, we present the fluorescence spectra of anthracene and pyrene vapors at different elevated temperatures (from 150 to 650 degrees C) excited with the 337 nm line of a nitrogen laser. We describe the high temperature effects on the resulting spectral properties including spectral intensity, spectral bandwidth and spectral shift. We found that the PAH fluorescence spectral bandwidths become very broad as the temperature increases. The broadening is mainly due to thermal vibrational sequence congestion. We also have found that the fluorescence intensity of pyrene vapor increases with increasing temperature, which results from the increase of the pyrene vapor absorption cross section at 337 nm.