消防指示灯智能监控系统三端口网关设计

提出采用两级环形总线网络拓扑、主从通信方式的消防指示灯智能监控系统.设计了用电池提供应急电源的通信网关的总体结构.采用单片机自带的双串口构成两个独立光电隔离的RS-485接口作为下级环形总线主站,实现与智能应急标志灯之间交换数据.利用单片机的SPI接口功能和另一个单片机扩展第三个独立的光电隔离RS-485接口,作为上级环形总线网络的从站,实现与监控主机之间状态和命令信息交换.给出了系统网络拓扑结构和基于Modbus协议的通信软件结构.     

不同气液流量下喷射器内液滴特性分析

单重态氧是氧碘化学激光的能量来源,其反应生成效率直接影响COIL输出的激光功率和光束质量.单重态氧的反应生成效率取决于气液接触面积,喷射式单重态氧生成器的气液接触面积与喷射器内的液滴分布有关.本文利用商业计算流体力学软件.Fluent 6.3,对喷射式单重态氧发生器内不同气液流量情况下的液滴直径、速度分布规律进行模拟.模拟过程主动流体为水,被动流体为氯气和氦气的混合气体,通过模拟得出了不同气液流量情况下,喷射器内液滴的直径、速度分布情况.在液相流率不变的情况下,随气相流率的增大,喷射器内的液滴平均直径减小,平均速度增大,直径方差和速度方差减小,液滴直径和速度分布趋于集中,且变化趋势随气相流率的增大而减缓;当气相流率不变时,随液相流率的增大.液滴平均直径减小,平均速度增大,直径方差和速度方差都增大,液滴直径和速度分布趋于分散.     

AD9707高速DAC的内部寄存器配置

由于高速DAC内部集成度的不断加大,DAC外围电路趋于简单化,用户可以根据自己的需求配置DAC内部寄存器来选择DAC的工作模式。本文在介绍AD9707的工作原理和典型电路的基础上,着重阐述了通过ARM和FPGA两种方式分别配置AD9707内部寄存器的方法,同时给出了两种配置方法基本操作的具体步骤和相应代码。     

ARM与射频芯片TRF796x的SPI通信研究

针对SPI总线接口缺乏标准协议的特点,提出了SPI器件之间通信的一般方法。论文阐述了ARM芯片内置SPI硬件控制器的工作原理和时序,并对射频芯片TRF7960x的工作模式与读写要求进行了分析。在此基础上,根据TRF796x的时序特性和访问要求,采用ARM芯片的硬件SPI方式实现对TRF796x的读写访问与控制,并在RFID门禁系统中验证了通信结果。     

基于蚁群算法的网格资源发现模型研究

本文通过对传统的网格资源发现存在的问题进行分析,针对其不足,引入蚁群算法,提出基于蚁群算法的网格资源发现模型（AA_GRRM）,设计并分析AA_GRRM的体系结构,并对其关键模块分析设计,以提高网格资源发现效率。     

无线镀膜玻璃色差数据实时监测系统的设计

针对玻璃生产线布线困难、电磁干扰强、数据处理效率低的状况,设计了无线镀膜玻璃色差数据实时监测系统;介绍了无线射频收发芯片nRF2401AG的原理及特点,采用了无线通信技术和数据库技术,阐述了将Visual C++6.0作为开发平台,镀膜玻璃色差数据无线收发、实时监测、实时存储、动态显示等实现过程;经实际验证:该系统无线通信稳定可靠、数据处理效率高;满足了工程实际应用需求,具有很好的实用性和推广价值。     

A best method of demodulation algorithm for UNFSK applied in transportation

The frequency shift of the ultra-narrow frequency shift keying (UNFSK) is far less than the ordinary binary frequency shift keying (FSK) method. Because the two frequencies of UNFSK are extremely close, the traditional demodulation method cannot separate them successfully. This study aims to successfully demodulate the UNFSK signals by applying cycle extension and notch filter. The signal processing procedure is as follows: First, the sampling signals have been made cycle extension to enlarge their spectrum difference between signal 0 and 1; secondly, the cycle extension signals have been processed by the notch filter algorithm and finally, we could get the information by sentencing the filtering result. Finally, the method is applied in transportation. The simulation results proved that the algorithm greatly enhanced UNFSK signal demodulation performance, compared to the traditional demodulation method. There can be 2–3 dB improvement in performance, which is very suitable for UNFSK.     

Analysis of the nonlinear dynamic stability for an electrically actuated viscoelastic microbeam

In this article, based on the standard linear solid model, the Euler-Bernoulli hypothesis and the Galerkin method, an analysis of the nonlinear dynamic stability for a clamped-guided viscoelastic microbeam under both a periodic axial force and a symmetric electrostatic load is presented. By using the incremental harmonic balanced method, the boundary of the principal region of instability is got. In the numerical calculation, the effect of the environmental and inner damping, geometric nonlinear, creep quantity and the symmetric electrostatic load on the principal region of instability is discussed.     

A new phase unwrapping method based on region recognition and region expansion

Phase unwrapping is a key step in retrieving digital elevation models (DEMs) from across-track interferometric synthetic aperture radar (InSAR) data. The coherence of synthetic aperture radar (SAR) data set is an effective indicator for the quality of phase unwrapping. However, the coherence of different regions usually distributes unevenly in SAR images monitoring heterogeneous areas. Errors in low-coherence areas are prone to pollute the whole image. In order to mitigate propagation error, a new phase unwrapping algorithm based on region recognition and region expansion is proposed. In the region recognition step, optical images are incorporated to recognize low-coherence regions by virtue of supervised classification technique. Low-coherence regions and the ones that are not of interest for the application are then discarded. In the region expansion step, stable pixels of high coherence are selected as growing seeds, and then phase unwrapping grows from high-quality regions to low-quality ones guided by coherence information and weighted numbers of neighbouring unwrapped pixels. The ambiguity number of a wrapped pixel is estimated from its neighbouring pixels under the criteria of pixel distance and phase gradient. Iterative examination continues until the whole image is unwrapped. Experiments on PALSAR and ASAR data demonstrate its validity and advantages over other classical methods.     

A new approach for image databases design

This paper focuses on the methodologies to organize and structure image databases. Conventional relational database techniques are optimized to deal with textual and numeric data; however, they are not effective to handle image data. Some progresses have been made in developing new approaches to establish and use image databases, but the applications of these approaches are very labor-intensive, error-prone, and impractical to large-scale databases. In this paper, we propose a new approach to develop the structure of a large-scale image automatically. It is an integrated approach from existing technologies for the new application where the management of image data is focused. In addition, we present a solution to data indexing for the image database with different image types.