PC机与多单片机组成串行通信的新尝试

以实际应用的小型集散变频调速系统为例 ,介绍一种PC机与多AT89C2 0 51单片机之间串行通信的接口电路 ,并提出一种新的通信方法 ,即采用QBASIC语言提供通信语句来编写多机通信程序。该方法硬件紧凑 ,软件编程简单可靠。     

单苯环氯取代指数法预测二噁类化合物PCDDs的正辛醇/水分配系数

采用单苯环氯取代指数作为氯代二苯并二口恶口英类化合物 (PCDDs)的分子结构描述符 ,通过正向逐步线性回归方法建立了PCDDs的logKow与分子结构描述符之间的定量关系模型。与文献报道的MOD模型相比 ,该模型不仅具有显著的相关性 (n =43,Radj=0 898,SE =0 195 ,在α =0 0 5时 ,F =2 0 45 5 ,p =0 0 0 0 0 ) ,而且对于分子结构具有更好的区分能力。利用建立的模型 ,对没有logKow文献值的其他 33种PCDDs化合物给出了预测值     

应用MODIS资料对城乡地表热通量的估算

为了揭示城市热岛形成机制,基于MODIS资料,结合自动气象站实测的气象资料,利用地表能量参数化方法估算了地表热通量,分析了城乡地表热通量的空间分布及变化特征.结果表明城乡地气热交换差异明显,与相关文献对比证明该方法是可行、有效的.     

单通道TD-SCDMA射频拉远单元

该文设计了一种单通道TD-SCDMA射频拉远单元。首先根据系统要达到的性能指标要求,设计了系统拓扑结构,接着从该系统拓扑结构出发,分析了整个系统的设计思路及实现方案,选择相应的电路模块。测试结果表明设计的系统达到了预期的指标,临近通道功率比小于-40.64 dBc和误差向量幅度为5.08%rms。     

Performance of Sewage Sludge Treatment and Electricity Generation by Different Configuration Microbial Fuel Cells

This paper compared the degradation efficiency of sludge organic matters and electric-production by two typical microbial fuel cells——dual-chamber microbial fuel cell(DMFC)and single chamber air cathode microbial fuel cell(SAMFC),and the variations of sludge protein,polysaccharide and ammonia nitrogen within the systems were also investigated.The results showed that the concentration of sludge soluble chemical oxygen demand,protein and carbohydrate of DMFC are higher than these of SAMFC during the systems operation,while DMFC can achieve a better ammonia nitrogen removal than SAMFC.Under the same operation condition,the stable voltage output of DMFC and SAMFC is 0.61 V and 0.37 V;the maximum power density of DMFC and SAMFC is 2.79 W/m3and 1.25 W/m3;TCOD removal efficiency of DMFC and SAMFC is 34.14%and 28.63%for 12 d,respectively.Meanwhile,DMFC has a higher coulomb efficiency than SAMFC,but both are less than5%.The results showed that DMFC present a better performance on sludge degradation and electric-production.     

Fat bloom formation and characterization in milk chocolate observed by atomic force microscopy

The surface microstructure and polymorphic behavior of milk chocolate subjected to multiple thermal cycles between 20 and 32, 33, or 34°C were examined using atomic force microscopy (AFM) and powder X-ray diffraction (XRD). The surface of unbloomed milk chocolate was smooth (surface roughness of 278 nm) and consisted of small, evenly distributed crystals. XRD results indicated the presence of mostly form V crystals and little or no form VI crystals. Cycling between 20 and 32°C resulted in little bloom formation and change in polymorphic behavior. Gradual bloom formation occurred as a result of cycling between 20 and 33°C, and was accompanied by the nascence of form VI crystals. Surface roughness increased gradually from 417 nm after one cycle to 476 and 521 nm after two and three cycles, respectively. Extensive bloom arose from cycling between 20 and 34°C. Surface roughness increased from 373 nm after one cycle to 603 and 736 nm after two and three cycles, respectively. This heavily bloomed chocolate consisted of jutting crystals and large raised, yet smooth areas that were haphazardly located within the chocolate matrix. In summary, a new perspective on the development of surface bloom due to thermal cycling is provided.     

一种用单片机制作的高频正弦波逆变器

本文介绍一种简单廉价的单片机AT89C2051实现正弦波脉宽调制、保护的逆变器电路，以及逆变器的整体设计和工作原理，为小型正弦波逆变器的设计制作提供了一种较新的思路。     

静态随机存储器单粒子翻转效应的二维数值模拟

采用MEDICI二维模拟软件对静态存储器SRAM的单粒子翻转(SEU)现象进行了计算。对MOSFET漏区模拟得到的结果与电荷漏斗模型相吻合,表明所建立的物理模型的正确性。通过输入不同粒子的线性能量传输LET值,得到了某一结构器件的收集电荷与LET值的关系曲线,并给出临界电荷7 73×10-14C。     

Expansion of Plasma of Electrically Exploding Single Copper Wire Under 4.5kA～9.5kA/Wire

Abstract The experimental system for electrically exploding single metal wire has been de-signed and manufactured. Expansion of the dense plasma column formed from an electricallyexploding Cu wire of diameter 30 μm has been studied with a high-speed photographer to obtainthe time-dependent radius (R-t) curve. The experimental results demonstrate that the mean ex-pansion rate of the dense plasma column is 1.94 μm/ns, 2.6 μm/ns and 3.75 μm/ns according tothe peak pulse current 4.5 kA, 7 kA and 9.5 kA respectively. The results can be beneficial to givinga profound understanding of the early stage of wire-array Z-pinch physics and to improvement ontheir design.     

基于AT89C2051的有线电视可寻址控制系统

介绍了用AT89C2 0 5 1实现有线电视可寻址控制系统的原理 ,软件流程及硬件电路