基于3G和VPN的温室远程监控系统的设计与实现

根据温室环境的特点提出一种基于3G无线通信技术和VPN（Virtual Private Network）虚拟专网技术的温室远程监控系统。该系统在温室现场设备和中心服务器之间建立无线的虚拟专网,采用Linux操作系统、ARM9处理器作为软硬件平台,能够对温室环境因子数据的进行自动采集、远程传输、存储管理、网络发布、分析处理,同时实现对温室辅助控制设备的远程控制。试验结果表明：该系统设计方案合理、可靠,能满足各种环境因子的数据采集及多种温室辅助设备的远程控制。鉴于设计方案中采用了通用型技术构架,本系统已经扩展应用于其他农业领域中,如农情监测、气象灾害监测预警等,应用前景非常广阔。     

PDA Based Virtual Instrument

Test and Measurement task can be done without limit of time and space by PDA with virtual instrument technology. The structure of PDA based virtual instrument is described firstly. Then PMDS(PDA Measurement Develop System) which can construct virtual instruments efficiently using component technology is introduced, it can enhance quality and efficiency of instruments. Finally, portable spectrum analyzer and mobile temperature monitor is built with PMDS to illuminate the usage of PMDS.     

Great Capacity of Data Logger Based on Virtual Instrument Technology

The Data Logger is an important secondary-instrument,which can be applied to automatic monitor and control system,and high speed local data acquisition for later analysis.The Virtual Great Capacity of Data Logger based on virtual instrument technology is a new instrument which has more advantages than the traditional Data Logger.The design method has been introduced from three ways,which includes system principle, hardware configuration and programming design, and an application example is given.This Data Logger is low cost,easy to take,also easy to operate.It can be widely used in many of actual applications.     

Virtual FFT Spectrum Analyzer Based on DSP Technology

Virtual Instrument has become an important direction of instrument development, now it has been widely used in many fields. FFT analysis is a widely used method in mechanical engineering, fault detection and many other fields. However, the traditional FFT analyzer is expensive and is not easy to upgraded. The birth of virtual FFT Spectrum Analyzer gets rid of the limit of traditional FFT analyzer, and paves the way for the application of FFT analyzer. The uses of DSP technology make the future broadened of Virtual Instrument. This article ,based on the deep study of DSP system, designs a virtual FFT Spectrum analyzer based on DSP technology. The design is new and of great practicality, which indicates the important role of Virtual Instrument in the development of instruments.     

Application on Extracting Feature in State Monitoring and Fault Diagnosis

With the development and application of information and internet and virtual instrument technology ,the virtual globular company based on internet arises .To study remote state monitoring, remote fault detection and diagnosis about large scale, complicated and integrative equipment become very important. In the whole fault diagnosis system , the detecting ,data acquisition is original ,processing; transform and extracting features with the signal detected is a key factor. The theories and methods used in mechanical fault diagnosis is stated. The application of signal process and its feature extracting methods is introduced which are time domain, frequency domain and time frequency domain analysis, in state monitoring and fault diagnosis with its signal analysis. The processing method of random time variant special signal is given also.     

Design and Implement of Site for Virtual Instrument Stream

With the abundance and development ,the transmission of virtual instrument on Internet become the exigent need in the field of instrument .The paper summarizes the building method of running flat to the stream of virtual instrument .The authors can complete remote test,exchange the testing data,so much as establish a dynamic league for test mission through the flat . For this flat ,they bring forward own opinion of systemic framework and running environment as well as local area network building . Furthermore, the anthors set forth the realization of function of accessing to database of virtual instrument.,the layout of site homepage. Finally,they introduce how to configure the site server ,what operating system to be selected for the site server and how to deploy the whole site .     

Digit Weight and Development of a Virtual Noise Analyzer

Traditional noise octave analyzers consist of filter network and weight network based on hardware. In order to realize a noise octave analysis by software, a digit weight method based on FFT is proposed. Using the method, digit weight and digit system error modification for virtual noise octave analyzer can be realized. Because of digit weight and digit system error modification, precision and stability of the instrument can be improved greatly. As an application, which combines the method of digit weight with the technique of digit system error modification, a low cost and high precision virtual real time noise octave analyzer is developed.     

Virtual Instrument Technology and Its Application in Humidity Testing

In recent years,Virtual Instrument technology has been concerned in the arena of information technology and instrument manufacture.The authors propose the Virtual Instrument's concept,characteristics and configuration of both hardware and software.They apply Virtual Instrument to the humidity testing and brings forward the method to solute the problem,which traditional dry-humid balls humidity-testing instrument can not test several objects.By putting the emphasis on data acquisition,data processing,data storage and data display,the software design of virtual humidity test is discussed.     

基于L-System模型的Web三维果园构建方法研究

网络技术和虚拟现实技术的发展为农作物生境的展示提供了多样化的方式。笔者研究在 L-System植物模型的基础上,提出一种简单、快速的在线三维果园构建技术方案：采用Xfrog软件构建果树三维模型,运用Unity3D引擎设计果园三维场景并实现人工交互,以热带水果——莲雾作为应用范例,构建Web三维莲雾园模型,模型具有真实感强、交互功能丰富、操作简单等特点。该方案为果树生长研究、农业景观规划和乡村旅游推广等应用提供三维可视化的展示方式。     

Applying of the DSP Technology in the Virtual Instrument System

The hardware architecture and instruction set of the digital signal processor leads to its high speed and precision in processing data. Aiming at the virtual instrument's deficiency in speed and precision resulting from the limit of the computers' development, the author brings forward a method to promote the performance of the virtual instruments using the DSP technology. Implementing the complex algorithms in DSP and using the principal and subordinate DSP structure or DMA technology in the data acquisition card of the virtual instrument can promote the virtual instrument's real-time characteristic greatly. Several key technologies are introduced in realizing the data acquisition and processing card. The experiment shows that the digital signal processors have higher speed and precision than the computers when implementing complex algorithms, and that using the DSP to implement the algorithms is an effective method to promote the virtual instrument's performance.     

Development of Virtual Sweep Signal Source

A new kind of virtual sweep signal source which can be used to output specific sweep signal according to(users') configuration and can be widely applied to frequency characteristics measurement in the field of mechanics,electrics and electronics,is developed by using Dot Net software engineering technique,C/S architecture and general data acquisition platform.The virtual instruments not only make up the intrinsic defect of traditional instruments based on hardware components in high performance,remote control and data processing,but also indicate the powerful life and nice future of virtual instrument technologies.     

Design of Virtual Instrument for Automobile Based on PC/104

The design of virtual instrument for automobile based on PC/104 has been presented by comparing with the traditional auto meter. The paper focuses on the development environment, system construction and operation principle. The data of the virtual instrument is transported by CAN bus, and this system can monitor in real-time, display in digit and fire the alarm to the super-speed, save the record.     

Research on Cooperative Design Network Security Based on IP-VPN

As the important method and instrument of agile manufacture,the technology of distributed collaborative design and manufacturing has become the hotspot of manufacturing. The basic concept and key technologies of IP_VPN are introduced in this paper,and a collaborative design network model based on IP_VPN is presented. Distributed collaborative design is a multi_user,multitask involved system, which is consisted of lots of collaborative processs,so the network security is the key of distributed collaborative design. We research on the security of collaborative design network based on IP_VPN, hence get a conclusion:we can construct an economical?practical and secure collaborative design network system by the application of data encryption,user authentication and access control based on the role,etc.     

Flowmeter Based Virtual Instrument

The flowmeter based virtual instrument is a new test instrument, which has more advantages than the traditional flowmeter. This flowmeter is based on Qin's model. Apply to the flowrate measurement realm the virtual instrument technique. The design method has been introduced from hardware, software and panel, modelize the different flowrate measure way, with the virtual instrument's figural calculation and show to replace the traditional flowrate measurement, realize multi-threading long-distance flowrate measure easily.     

Design of Testing System for ABS Test-bed

This paper discusses the structure, design and key techniques of testing system, and expounds the design and development of hardware and software based on virtual instrument technology. The design of hardware includes signal conditioning module and data acquisition module. The design of software includes interface program and upper layer program. Combining the hardware and software effectively, a testing system for ABS test-bed is set up, which has multifunctions of developing, debugging, inspecting and performance valuing to ABS. Having crucial meaning in engineering, the development of this testing system will make ABS tested in the lab mainly, thus improve the security and make the test more economical.     

Design of Data Acquisition System for Vehicle Based on CAN Bus

To the question that a meter is correspond with a set of lead and a sensor,this paper presents a design of data acquisition system for vehicle based on CAN bus.In this way,the combinatorial instrument is only connected by a bus unit.Author introduces the data acquisition structure chart and the CAN interface,analyzes the software by program flow chart,and shows it's application for vehicle virtual instrument.A method of calculating vehicle speed,engine rotate speed and the course of development mileage are also given.     

A Virtual Wavelet Transform Analyzer for the Signal Analysis Based on the Direct Algorithm

A virtual wavelet transform analyzer for the signal analysis based on the direct algorithm is introduced so that the discrete wavelet transform and continuous wavelet transform is maken to signal in the direct algorithm. The authors first introduce the direct algorithm of the WT, which is numerical algorithm obtained from the original formula of the wavelet transform by directly numericalizing. Then some conclusions are drawn on the direct algorithm. The examples are the sampling principle and technology for the wavelets, the limitation of the scale range of the wavelets and the measures to solve the edge phenomenal in the direct algorithm of the discrete wavelet transform, and some conclusions in the direct algorithm of the continuous wavelet transform. The virtual wavelet transform analyzer for the signal analysis based on the direct algorithm explored based on these studies and combined with virtual instrument technique can make the discrete wavelet transform and continuous wavelet transform to signal with any basic wavelet. It can be applied in studying the property of any basic wavelet and learning the theory on the wavelet transform, and also in making some engineering signal analysis. In the end, the authors give some typical examples for the application of the virtual analyzer. These examples show that the analyzer can be applied in many situations.     

Application of WebGIS Based on Component Technology

This paper discusses the basic theory and notation how component technology is applied to the WebGIS, and gives an overall introduction to the prevailing developing method of component WebGIS. Based on a given WebGIS' component platform and an Object Related Database System (Oracle Spatial), the paper develops a successful WebGIS application,and analyses the shortcomings and merits of component technology applying to the WebGIS.It is put forward that component technology is a new developing method and more effective,flexible and powerful compared with the present or traditional developing technology. Moreover, it provides more flexible choice for integrated development. With ASP(Active Server Page),components are integrated to web page, program developed is tested applicable in the intranet.     

基于BP神经网络的农业电子商务网站评价研究

提出了适合农业电子商务网站的评价指标体系。建立农业电子商务网站的BP神经网络评价模型,通过BP神经网络对数据进行训练、测试,对提出的评价指标体系进行了验证。通过对结果的分析发现,建立的基于BP神经网络的评价模型在农业电子商务网站评价中具有可行性,在网站建设方面具有较强的参考价值。