By‐products formation in catalytic combustion of aromatic compounds over a pt‐based catalyst

By‐products formation in the catalytic combustion of different aromatic compounds has been experimentally investigated. A commercial Pt‐based catalyst, in the shape of a short monolith, has been employed. Toluene, styrene, o‐xylene and cumene have been tested at low concentrations for conversions in the range 5–50%. The results confirm the formation of benzene in the combustion of toluene and styrene, as previously observed by other researchers, but in a very small amount; testing cumene, significant amounts of acetone have been found in the outlet flow. Some hypothesis about the reaction mechanism are put forward.     

单片机网络在智能化小区中的设计和应用

随着控制技术的发展，控制系统越做越复杂，由单片机构建的控制系统已经由一个单片机组成的系统发展到多个单片机组成的多机控制系统和多个单片机组成的网络系统。在工业监控和民用产品中单片机系统使用的越来越多。随着技术的发展和市场竞争的加剧，生产厂家除了考虑到产品的性能也要考虑到产品成本。Microehip公司的PIC16C57是一款性价比较高的单片机。由该单片机建立起来的系统成本大大降低。本文介绍了一种由PIC16C57单片机建立起来的分级总线型网络系统，系统可以用于工业系统监控和民用楼宇监控系统，该网络系统在硬件和软件上都采取了特别的保护措施，系统具有非常好的稳定性和可靠性。     

基于无线通讯的LED大屏幕显示系统的实现与设计

介绍了一种基于无线数字传输芯片和单片机构成的LED大屏幕显示系统的设计,讨论了系统的硬件电路设计和软件设计。该系统分为两大块：发送模块和接收模块。在发送模块中,单片机先通过串口接收上位机发送的数据,再控制无线数字传输芯片把数据发出;在发送模块中,单片机会接收到与无线数字传输芯片地址匹配的无线数据,接着处理数据,然后发送到LED大屏幕进行显示。     

基于PT2262/PT2272的机器人遥控系统的设计

本文通过对PT2262/PT2272工作原理的分析,结合凌阳SPCE061A单片机提出了一种机器人遥控系统.电路易于实现、性价比高,所涉及的电路及参数均经过测试,可广泛使用于从玩具机器人到科学研究机器人中.实际应用表明,本文给出的设计方法合理有效,有效遥控距离长,具有较高的实用价值.     

烤烟房温湿度自动测控系统设计

介绍了基于89C51单片机的烤烟房温湿度测控系统软硬件的设计,整个系统由数据采集、数据调理、单片机和控制部分组成.引入了温度传感器AD590和湿度传感器HS1101在烤烟方面的运用,采用该测控系统准确地检测烤烟房内的温湿度数据,有效地自动控制烤烟房内的温湿度,提高了烤烟房内的控制水平和烟叶的烘烤质量,从而增加了烟农的收入.     

PIC simulation of plasma properties in the discharge channel of a pulsed plasma thruster with flared electrodes

Plasma in the discharge channel of a pulsed plasma thruster (PPT) with flared electrodes is simulated by a self-developed two-dimensional code. The fully particle-in-cell method with Monte Carlo collision is employed to model the particle movement and collisions and investigate the plasma properties and acceleration process. Temporal and spatial variations of the electron density distribution and the ion velocity between electrodes are calculated and analyzed in detail. The computational results of the electron number density, which is in the order of 10²³ m⁻³, show good agreements with experimental results of a PPT named ADD SIMP-LEX. The ion velocity distributions along the center line of the channel lead to a comprehensive understanding of ions accelerated by electromagnetic field. The electron distributions of PPT with discharge voltages varying from 1300 to 2000 V are compared. The diffusion of electrons presents strong dependency on discharge voltage and implies higher degree of ionization for higher voltage.     

Study on the influence of three-grid assembly thermal deformation on breakdown times and an ion extraction process

In order to study the influence of three-grid assembly thermal deformation caused by heat accumulation on breakdown times and an ion extraction process,a hot gap test and a breakdown time test are carried out to obtain thermal deformation of the grids when the thruster is in 5 k W operation mode.Meanwhile,the fluid simulation method and particle-in-cell-Monte Carlo collision(PICMCC) method are adopted to simulate the ion extraction process according to the previous test results.The numerical calculation results are verified by the ion thruster performance test.The results show that after about 1.2 h operation,the hot gap between the screen grid and the accelerator grid reduce to 0.25–0.3 mm,while the hot gap between the accelerator grid and the decelerator grid increase from 1 mm to about 1.4 mm when the grids reach thermal equilibrium,and the hot gap is almost unchanged.In addition,the breakdown times experiment shows that 0.26 mm is the minimal safe hot gap for the grid assembly as the breakdown times improves significantly when the gap is smaller than this value.Fluid simulation results show that the plasma density of the screen grid is in the range 6?×10~(17)–6?×?10~(18) m~(13) and displays a parabolic characteristic,while the electron temperature gradually increases along the axial direction.The PIC-MCC results show that the current falling of an ion beam through a single aperture is significant.Meanwhile,the intercepted current of the accelerator grid and the decelerator grid both increase with the change in the hot gap.The ion beam current has optimal perveance status without thermal deformation,and the intercepted current of the accelerator grid and the decelerator grid are 3.65 m A and 6.26 m A,respectively.Furthermore,under the effect of thermal deformation,the ion beam current has over-perveance status,and the intercepted current of the accelerator grid and the decelerator grid are 10.46 m A and 18.24 m A,respectively.Performance test results indicate that the breakdown times increase obviously.The intercepted current of the accelerator grid and the decelerator grid increases to 13 m A and 16.5 m A,respectively,due to the change in the hot gap after 1.5 h operation.The numerical calculation results are well consistent with performance test results,and the error comes mainly from the test uncertainty of the hot gap.     

一种新的液体粘度在线测量方法

提出一种液体粘度在线测量方法,并介绍了该方法的基本原理,利用自行设计的传感器获得力信号,分析出流体粘度和传感器受力间的关系.在软件设计中采用多传感器卡尔曼滤波技术,软件容错技术,以及分段非线性补偿,实现了在线粘度信号的采集和数据处理.实验结果证实了该方法的可行性.     

单片机的网络应用

主要阐述了单片机用于网络应用时,在确定架构方案时应着重考虑的几个问题,这也是确定系统性价比的重要因素.包括RTOS的使用问题;阻塞或非阻塞调用的问题;采用单线程设计还是采用多线程设计的问题;存储器管理问题;采用何种网络接口的问题.并例举了典型的单片机网络应用系统的软硬件架构.在此架构基础上可进行多种用途的单片机网络应用系统的开发.     

基于PLC接口的智能数码显示表头的设计

本文以用PIC16F877加少量外围电路构成的LED数字显示表头为例,介绍PIC单片机智能表头的硬件电路原理和软件编程方法,并给出了用三菱公司的FX系列PLC编制的单表显示例程和PIC的控制显示流程图.