高硅沸石分子筛ZSM-11用于CH4与N2吸附分离性能的研究

以四丁基氢氧化铵为模板剂,通过调节铝源和硅源的比例合成了两种高硅铝比(n(Si)/n(Al)=100、500)沸石分子筛ZSM-11,采用XRD、TG和N2吸/脱附等方法对ZSM-11分子筛进行了表征分析,测试了样品在500 kPa下对CH₄和N₂的吸附性能。结果表明,ZSM-11-500样品的比表面积和吸附容量略高于ZSM-11-100,两个样品的CH₄/N₂吸附选择性均达到4.0以上,优于商业吸附剂水平。混合气体穿透模拟结果显示,ZSM-11具有良好的CH₄/N₂分离能力,且对于低浓度煤层气中CH₄的富集纯化脱除N₂具有良好的应用前景。     

可调谐二极管激光吸收光谱技术及其在大气质量监测中的应用

可调谐二极管激光吸收光谱(TDLAS)技术是利用二极管激光器的波长调谐特性,获得被选定的待测气体特征吸收线的吸收光谱,从而对污染气体进行定性或者定量分析.在大气痕量气体和气体泄漏的监测中,为了提高探测的灵敏度,一般会根据具体情况对激光器采取不同的调制技术如波长调制、振幅调制、频率或者位相调制等,同时和长光程吸收池相结合使用,并辅之以各种噪声压缩技术.TDLAS不仅精度较高,选择性强而且响应速度快,已经广泛用于大气中多种痕量气体的检测以及地面的痕量气体和气体泄漏的检测.报道了最近研制的一套可调谐二极管激光吸收光谱检测大气中甲烷浓度的实验装置,这套装置具有灵敏度高、检测限低(ppb量级)、易于集成为便携式痕量气体检测仪等优点,若激光器的调谐波长范围能覆盖1.3～1.8 μm或者在光路中装配几台窄范围可调谐激光器实现波长扫描范围覆盖1.3～1.8μm,则可同时实现对大气中诸多重要痕量气体如CO2、CH4、CO、CH2O、H2S、NH3、HCI、C2H2等的同步监测.     

基于32位单片机MC68HC376的高可靠性系统设计

本文介绍了32位高性能单片机MC68HC376的基本特性，提出了一种系统设计方案，并重点论述了系统的可靠性设计。论文针对系统的特点从硬件设计、软件设计以及制板布线等方面讨论了提高系统可靠性的具体实现方法，实际应用装置表明该方案具有较高的可靠性。     

基于CH7004的嵌入式系统VGA接口设计

VGA接口为嵌入式设备提供简单有效的大屏幕图像显示解决方案。介绍嵌入式系统的VGA接口设计方法,充分利用S3C2410内部LCD控制器和视频编码器件CH7004的功能。该方法具有硬件设计及软件实现简单,廉价的特点。详细阐述VGA接口的硬件设计和LCD控制器、CH7004控制寄存器的软件配置。     

Investigation of local flame structures and statistics in partially premixed turbulent jet flames using simultaneous single-shot CH and OH planar laser-induced fluorescence imaging

We report on the application of simultaneous single-shot imaging of CH and OH radicals using planar laser-induced fluorescence (PLIF) to investigate partially premixed turbulent jet flames. Various flames have been stabilized on a coaxial jet flame burner consisting of an outer and an inner tube of diameter 22 and 2.2 mm, respectively. From the outer tube a rich methane/air mixture was supplied at a relatively low flow velocity, while a jet of pure air was introduced from the inner one, resulting in a turbulent jet flame on top of a laminar pilot flame. The turbulence intensity was controlled by varying the inner jet flow speed from 0 up to 120 m/s, corresponding to a maximal Reynolds number of the inner jet airflow of 13,200. The CH/OH PLIF imaging clearly revealed the local structure of the studied flames. In the proximity of the burner, a two-layer reaction zone structure was identified where an inner zone characterized by strong CH signals has a typical structure of rich premixed flames. An outer reaction zone characterized by strong OH signals has a typical structure of a diffusion flame that oxidizes the intermediate fuels formed in the inner rich premixed flame. In the moderate-turbulence flow, the CH layers were very thin closed surfaces in the entire flame, whereas the OH layers were much thicker. In the high-intensity-turbulence flame, the CH layer remained thin until it vanished in the upper part of the flame, showing local extinction and reignition behavior of the flame. The single-shot PLIF images have been utilized to determine the flame surface density (FSD). In low and moderate turbulence intensity cases the FSDs determined from CH and OH agreed with each other, while in the highly turbulent case a locally broken CH layer was observed, leading to a significant difference in the FSD results determined via the OH and CH radicals. Furthermore, the means and the standard deviations of CH and OH radicals were obtained to provide statistical information about the flames that may be used for validation of numerical calculations.     

Recent Progress in Electrocatalytic Methanation of CO2 at Ambient Conditions

Electrochemical CO₂ reduction under ambient conditions is a promising pathway for conversion of CO₂ into value-added products. In recent years, great achievements have been obtained in the understanding the mechanism and development of efficient and selective catalysts for electrochemical CO₂ reduction. However, the electrochemical CO₂ reduction is still far from practical applications. Based on the gap between current research and practical applications, the state-of-the-art of the theoretical and experiment investigations on different electrocatalysts for the electrocatalysis of CO₂ to CH₄ is systematically and constructively reviewed. First of all, strategies for enhancing the catalytic activity and selectivity of electrochemical reduction of CO₂ to CH₄ are also examined in this review. The modulated strategies mainly involve the following aspects: i) tuning the applied potentials, ii) morphology engineering, iii) crystallographic facets engineering, iv) defect engineering, v) alloying. Furthermore, the influence of the electrolyte on the activity and selectivity for electrocatalysis of CO₂ to CH₄ is also reviewed. This review will build a systematic understanding in the electrochemical CO₂ reduction to CH₄ and may help to provide new insight for designing and optimizing the catalysts and/or electrolyte.     

基于USB的家庭远程医疗服务系统的存储扩展

介绍了家庭远程医疗服务系统的硬件结构和工作原理,给出了家庭远程医疗服务系统的USB存储扩展方案的改进设计方法以及USB总线接口芯片CH375的外围电路实现方法,同时给出了系统的硬件和软件设计结构。     

Layered (C6H5CH2NH3)2CuBr4 Perovskite for Multilevel Storage Resistive Switching Memory

Although there have been attempts to use non‐lead based halide perovskite materials as insulating layers for resistive switching memory, the ratio of low resistance state (LRS) to high resistance state (HRS) ( = ON/OFF ratio) and/or endurance is reported to be mostly lower than 10³. Resistive switching memory characteristics of layered (BzA)₂CuBr₄ (BzA = C₆H₅CH₂NH₃) perovskite with high ON/OFF ratio and long endurance are reported here. The X‐ray diffraction (XRD) pattern of the deposited (BzA)₂CuBr₄ layer shows highly oriented (00l) planes perpendicular to a Pt substrate. An Ag/PMMA/(BzA)₂CuBr₄/Pt device shows bipolar switching behavior. A forming step at around +0.5 V is observed before the repeated bipolar switching at the SET voltage of +0.2 V and RESET voltage of ‐0.3 V. The ON/OFF ratio as high as =10⁸ is monitored along with an endurance of ≈2000 cycles and retention time over 1000 s. The high ON/OFF ratio enables multilevel storage characteristics as confirmed by changing the compliance currents. Ohmic conduction at the LRS and Schottky emission at HRS are involved in electrochemical metallization process. The bipolar resistive switching property is retained after storing the device at ambient condition under relative humidity of about 50% for 2 weeks, which indicates that (BzA)₂CuBr₄ is stable memory material.     

基于CH375的U盘MP3播放器设计

介绍一种使用U盘作存储介质的MP3文件播放系统。该系统使用ATmega64L作为主控制器,VS1003作为MP3文件解码芯片,CH375则工作在HOST USB方式下通过USB接口完成对U盘的识别和MP3文件的读取。经过软硬件的测试,该系统能保证大容量U盘中MP3文件的顺畅播放,实现了MP3播放器中播放单元与存储单元的分离,可以方便地将U盘改造成MP3播放器,使MP3播放器更加方便灵活且不受存储容量的限制。     

基于"傻瓜"式芯片CH372的CAN总线适配器系统的设计

介绍了一种基于新型USB接口芯片CH372的CAN总线网络适配器系统的设计,提出了一种使用USB接口实现CAN总线网络与计算机连接的方案。利用芯片CH372可在不了解任何USB协议或固件程序甚至驱动程序的情况下,轻松地将并口或串口产品升级到USB接口。该系统在工业现场较之以往的系统,可以更加灵活,高速,高效地完成大量数据交换,并可应用于多种控制系统之中,具有很大的应用价值。