基于ZigBee技术的水域污染远程智能监测系统设计

针对所监测水域范围较大实时监测能力不强,水质污染程度监测不准确等问题,提出构建基于基于ZigBee无线通信技术的智能水域污染程度监测系统,利用ZigBee无线通信技术与Internet网络将水质检测数据发送到远程水质监控中心进行汇总处理,监控中心的服务器可获取到所监控水域范围内所有水域的水质污染程度数据、污染发展趋势、主要污染物等信息。本文对水质检测传感器模块、ZigBee无线通信模块、单片机外围电路、模数转换电路等硬件进行了设计;系统软件设计了远程参数设置、驱动程序等内容。通过系统测试结果表明,该系统对于水质污染程度的检测准确率可达到98%以上,通信成功率达到100%,水质检测终端工作稳定可靠,通信速率满足实时监测要求,适用于各种水域环境的水质污染程度的监测需求。     

基于无线传感器网络及GPRS的水质监测系统设计

提出了一种基于ZigBee无线传感器网络和GPRS技术的多参数远程实时水质监测系统。无线传感器网络以CC2430通信模块为核心。传感器节点采集到的数据经路由节点汇总至协调器节点,通过GPRS模块及时远传至监控中心。设计信号调理电路,将传感器电极输出的微弱电信号进行放大、滤波。采用时间同步机制实现网络节点的同步唤醒,大幅提高网络的稳定性。对系统进行了多天连续测试。通信距离为100米时,网络的平均丢包率低于1%。pH值、溶氧度的平均相对偏差低于1%。测试结果表明,系统具有灵活、实时性好、准确性高、稳定可靠等优点,具有很强的实用价值。     

龙芯3A体系架构下WiFi模块的设计与实现

为提高军用国产计算机的移动计算能力,提出一种在龙芯3A体系架构下WiFi模块的软硬件设计方法;在硬件设计部分,该WiFi模块围绕AR9285芯片展开设计,通过PCI-E总线与北桥进行连接;在软件设计部分,通过在PMON中添加WiFi模块驱动,实现初始化、数据发送和接收等功能;验证结果表明,移动计算机能够通过WiFi模块远程加载操作系统内核,无线网络数据响应时间约为1.5 ms。     

基于GPRS的下水道气体远程监测系统设计

为了提高城市下水道气体监测的实时性和可靠性,本文设计了基于GPRS的下水道气体远程监测系统。该系统主要包括前端气体采集模块、GPRS数据无线传输模块、数据接收模块及监控中心;气体采集模块由气体传感器和数据采集单片机组成;单片机实时采集气体传感器中的数据,并将采集到的数据通过GPRS无线传输模块进行实时上传;数据接收模块把接收到的数据传送至监控中心服务器,由服务器对数据进行处理、显示、存储和统计等。通过对18个监测点的监测实验效果表明,该系统运行稳定可靠,能实现对下水道气体远程采集、无线传输和实时监测的目的。     

一种自适应无线传感器网络监控系统网关设计

针对无线传感器网络网关通信方式单一、灵活性差的问题,设计并实现了一种自适应WSN监控系统网关,网关能够根据工作环境选择以太网、WiFi、GPRS通信方式中的一种来转发无线传感器网络的数据;基于STM32F107微处理器完成了网关的硬件开发和软件设计,实现了数据汇集、通信方式的选择、远程通信等功能;基于VC++完成了监控中心软件的开发,实现了数据接收、图形化显示、存储、查询等功能;搭建校园温湿度监控系统对网关性能进行测试,测试结果表明,该网关有扩展灵活、可靠性高、使用方便等特点。     

基于iOS的手机虚拟仪器浏览器的设计

为了动态调整手机端虚拟仪器的功能,提出了一种基于iOS平台的手机虚拟仪器浏览器的设计方法。其主要原理是通过往浏览器中加载不同的虚拟仪器脚本,将浏览器变成不同的虚拟仪器。虚拟仪器的基本组成模块是拥有多个输入和输出接口的控件,控件之间采用KVO模式进行组装和通讯,并采用脚本描述组装。所有控件类都继承自UIView类,需要调用和重写UIView的部分函数。信号发生显示器的例子证明了虚拟仪器浏览器的可行性。     

VXI总线多通道压力传感器仿真模块设计与实现

某型发动机系统主要由综控器、传感器、电机泵、电磁阀等部件组成,综控器是整个系统的核心控制部件,为测试综控器的性能是否符合要求,需要为综控器提供各种工况下的传感器（主要为压力传感器）数据进行仿真试验。采用真实的压力传感器开展上述工作,一方面需要构建复杂的工作环境,难度大、数据精确度难以保证,另一方面地面环境下的传感器信号变化难以实时调整,难以满足数据快速变化的需要。基于以上因素考虑,给出了一种基于VXI总线的多通道压力传感器仿真模块的设计方法,模块共有24路压力传感器电路,每路独立配置输出。模块以“VXI总线接口电路 VXI总线功能电路”的结构进行布局,VXI总线接口电路主要包括“CPLD 双口RAM”,对VXI总线指令进行解释、译码;VXI总线功能电路主要包括“96系列单片机 DA输出电路 两线压力传感器电路”,完成对真实传感器输出信号的电气特性仿真模拟。模块的驱动程序在Lab Windows/CVI6.0的环境下编制,供用户进行程序调用和快速操作使用。该模块已在VXI总线测试系统中得到应用,实际情况表明,模块的输出精度高、信号调整方便、响应快,满足了综控器仿真深度测试的要求。     

基于虚拟仪器的RLC谐振电路实验系统研究

基于虚拟仪器技术,在HLD-RLC-Ⅲ型号的RLC综合实验仪基础上,利用数据采集卡将实验仪输出的模拟信号转换为计算机能够处理的数字信号,配合LabView编制的虚拟仪器程序,实现测量RLC串联谐振电路特性的实验系统的设计与搭建。与传统的实验方案相比,其数据采集、信号处理、数据显示等功能都是虚拟仪器程序实现的,这些功能可根据实验内容重新设计,因此该系统在实验内容方面具有灵活的拓展性,利用该系统不仅能够完成测量RLC串联电路基本特性的基础实验教学,同时还能够对学生开展设计性实验训练,以此调动学生的积极性和创造性,提高学生的实践动手能力。     

智能燃气表缴费系统设计

为了解决传统燃气缴费系统在缴费方式上的不灵活、不方便等问题,提出了一种基于WiFi无线网络及Android技术的燃气缴费系统设计;给出了系统的整体框架及其组成,重点阐述了智能燃气表缴费系统的硬件及软件设计思路,定制了燃气表和客户端的通信协议;系统实现了内嵌WiFi模块的智能燃气表的电路设计,基于Android系统的手机客户端软件设计,以及燃气公司服务端的设计,并通过WiFi和GPRS网络建立三者之间的无线通信系统;通过测试,系统能够快速建立通信网络,具有传输数据快、可靠性高的优点。     

基于μC/OS-Ⅱ的数据采集模块设计

针对车载装备上传感器数据采集模块的体积小、可靠性高、实时性好等需求,设计了基于嵌入式实时操作系统μC/OS-Ⅱ的数据采集模块,选用集成了ADC与CAN通信功能等多种外设的Cortex-M3内核芯片STM32F107VCT6,移植嵌入式操作系统以简化软件设计,提高实时性和可靠性;数据采集模块将采集到的数据通过CAN总线实时地发送到主控计算机,同时也通过FatFs文件系统存储在SD卡中,便于计算机读取其中数据,进行离线分析;电路优化设计和数字滤波算法,提高了数据采集模块抗干扰能力和采样精度;通过实验验证,该数据采集模块可以准确、及时地获取和发送传感器数据,具有较高的可靠性和实时性。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.