Showing papers in "Instrument Technique and Sensor in 2004"

Optimization of Addressing Code of Digital Temperature Sensor Bass the 1-wire Bus at Measuring Multiple Temperatures

Abstract: It is critical technology to encode the digital sensor DS18X20,while measure multiple temperatures with the 1-wire bus.It is easy to practice for project engineering that addressing code is used decimal code instead of 48-bit serial number.By the structure of DS18X20 and the table of addressing code with serial number,introduce three modes to realize it.These are manual mode table,successive approximation mode table and embedded inteligence table.A comparison between the three modes in the performability and availability is also drawn.As focal point,analyze the third mode.It is because that is efficiency.In the mode,make two or three BCD instead of the 6 bytes of serial number on DS18X20 and write the BCD into register TH/TL.Then,describe the design of encoder and application method,which have simple interface,good reliability and practical value.

Application of Adopting Fuzzy Neural Network Adaptive Control in VAV Temperature Control System Based on Wavelet Neural Network

Abstract: Aiming at the great inertia,heavy to lag behind,non-linear characteristic of temperature control,proposed a design plan of central air condition room temperature controller through adopting fuzzy neural network adaptive control way using wavelet neural network as identifierBecause the wavelet neural network have the better ability to approximate non-linear functions,the identifier can identify more preciselyMoreover,the controller can alter its rules online along with the change of system dynamic characters to control objectively and accuratelyOn the base of comparison with general fuzzy controller,the result from simulation shows the validity of the system design

Methods for Design of Linear CCD Driving Circuit

Abstract: Design of driving circuit is the key technology for applications of CCDFour schemes for design of linear CCD driving circuit were discussed in detail,in which EPROM,IC,Monolithic Microcomputer and PLD were used to drive CCD respectivelyThen their advantages and disadvantages were comparedBased on program logic device,a practical design of TCD1208APP driving circuit and its waveform of time order simulation were given

Theory and Application of Anisotropic Magnetoresistive Sensor

Abstract: The physical mechanism and basic theory of the anisotropic magnetoresistive sensor were introduced.The main characteristics of one of this kind of sensor HMC1002,the measuring mechanism and its circuit were described.The result of weak magnetic field measure was given and analyzed.The application of attitude measure with the sensor and clinometers was studied.Another application of relativity detecting was discussed and the circuit diagram was given.The foreground was predicted with the analysis of merits of AMR.

Optical Fiber Frustrated-total-internal-reflection Based on High Accuracy Liquid Level Sensor

Abstract: Combining the features of high sensitivity of the optical fiber frustrated-total-internal-reflection based sensor and high positioning accuracy of the single chip computer controlled stepping motor driving system,a novel fiber-optic level sensor system has been developed.The sensor head is made from standard multi-mode communication silica fiber with a taper tip.There is sensitive response of the reflected light signal from the fiber taper when the refraction index of its surrounding medium changes.As the fiber taper is attached to the single chip computer controlled stepping motor driving device,the liquid level can be tracked and displayed continuously.The system is able to measure the level of diesel oil,gasoline and other chemical liquid with a resolution of 0.1 mm and long term accuracy of ±0.4 mm in a full scale of 2 m.

Design of Microwave Velocity and Distance Monitor System

Abstract: Measuring velocity and distance between vehicles is a crucial technology in automotive collision prevention system.It had analysed the system scheme and had studied the principle of the measuring system of FMCW radar.The design method of chief circuits had been given.This system can monitor forward vehicle in a foggy day or at night.Furthermore,it can give the alarm when the velocity and the distance between vehicles reach the edge of security,so some traffic accidents will be avoided.

Meter Based on Ultrasonic to Measure the Liquid-level

Abstract: The theory,the circuit,and the program were introduced using LM567 as the component to detect the ultrasonic and using the MCU 89C51 as the main control componentThe advantages of keeping clear of the medium which is detected,being likely to detect low temperature medium,no movable component,longevity and so on can be obtained when using the ultrasonic to detect the liquid-levelThe system's price can be reduced and the ability to catch the ultrasonic can be improved with LM567 as the detecting component of the ultrasonicThe more intelligent can be obtained when using the MCU to control the emission and receive and to calculate the liquid-levelThe causes by the ultrasonic velocity's variety and the delay of the LM567's output to bring the measuring errors were analyzd in detail and the method to reduce it is by hieghtening the precision when adjusting the ultrasonic velocity and the delay was also put forwardThis meter has a highly accuracy,credibility and by the experiment,and it can be used widely in many aspects

Technique Problems in Marine Geoelectrical Field Prospecting

Abstract: Compared with land exploration,marine exploration is confronted with such technical challenges as acquiring geoelectrical signals in liquid environment,setting the prospecting device automatically in the ocean and picking the instrument up safely from the sea.Several solutions to these problems were working out,that is,geoelectrical field sensor and flexible measure arms which were suitable for marine environment and the acoustic control system which controls remotely the sink and float of the instrument.Primary marine prospecting experiments show that these solutions are effective and reliable.

Portable Near Infrared Spectroscopy System for Mineral Analysis

Abstract: A designed scheme of portable near infrared spectroscopy system for mineral analysis and the key technique were introclucedThe instrument which used to measure the reflected radiation from the surface of sample was applied in mineral analyzerThe tested spectral range is 1 200～2 500 nmThe repeatability of the instrument is better than 1 nm,the optical precise is better than 2 nm When the lamp is 20 W,the average rate of signal to noise is better than 1 500

Development of Thermally Excited Si Resonant Pressure Sensor

Abstract: Using porous silicon as a sacrificial layer,a thermally excited Si-based resonant pressure sensor with integrated Si3N4 resonant beam and Si reflecting membrane is fabricated successfully through surface micromachining processes.Open loop test is executed in vacuum.The sensitivity of the sensor is 54.89 Hz/kPa with a linear correlation coefficient of 0.999 7 over a range of 0～300 kPa,and the Q factor is bigger than 20 000.

Design of Temperature Controller Based on MAX6675

Abstract: The circuits of temperature controllers which are based on thermocouple and other analog devices are often complicated and can't be adjusted easily,because there are so many parts such as cold-junction compensation,A/D converter and D/A converter.Now,having designed a circuit for the temperature controller which consists of new type of digital devices.It has simple structure and enough accuracy.The circuit parameters concerned have been tested in practice.Taking the stove of two kilowatts as the controlled object and the K-thermocouple as the temperature sensor.Introduced the structure,hardware principle and software manner for the temperature controller based on MAX6675.Emphasized the using method and interface with the measuring element MAX6675 and the controlling element MOC3083.

Real-time Single Neuron Adaptive Control System Based on Matlab Environment

Abstract: Real-time level process control system was devised on the basis of xPC Target software environment of Matlab.Meanwhile an adaptive PID controller were designed by means of neuron model and self-learning algorithm.The architecture and algorithm of the single neuron adaptive PID controller were discussed.The rapid prototyping process which created block diagrams in Simulink using simple drag and drop operations was introduced in detail.The real-time control system adopted adaptive PID controller was created through Simulink model with xPC Target.In order to verify the performance of two approaches,the PID algorithm was also used to control the level system.The results indicate that the proposed method can overcome the shortcoming of the traditional PID controller and achieve satisfactory stability.

Continuous-wave Ultrasonic Doppler Method for Pipe-flow Measurements

Abstract: Introduced a system for pipe-flow measurements based on continuous-wave(CW)ultrasonic Doppler method.To process the CW Doppler signal,intermediate-frequency(IF) demodulation,zoom FFT (Fast Fourier Transform)and weighted average algorithm for frequency evaluation were implemented in a single digital-signal-processing device.Thus we solved problems in conventional ultrasonic Doppler flowmeters such as hard to measure low velocity flow and decide the flow direction.

Design of Driver for Serial Communication in Net Formed by Intellectual Flow Totalizers Based on MCGS

Abstract: Introduced a stream monitor system based on generated software MCGS (monitor and control generated system)that formed with the self-developed intellectual flow totalizer instruments.The field digital data transmission was realized in the network.A serial of advanced functions for data processing were possessed.At the same time,cost and time for developing were saved largely.On the basis of analyses to the method interface and serial port access functions provided in the sample The key for programming of the device driver was given and also putting for ward a scheme with interrupt mode of serial communication according with the protocol in the totalizer.

Differential Absorption Optical Fiber NO_2 Gas Sensor

Abstract: Nitrogen dioxide is a poisonous gas harmful to people.It is increasing so fast,and real-time measurement of nitrogen dioxide is very important for environment and people's healthy.Based on the principles of nitrogen dioxide molecules' absorption spectra,an optical fiber gas sensor was designed to the pollution of enviroment.Two wavelength differential absorption measurement was used to eliminate the interference owing to verious disturbances,such as light power,optical fibre,sensor head changing,thus the sensitivity is improved.The sensing part can be put into the environment that the concentration of the nitrogen dioxide is very high.So measurement can be realized on real-time,economically and safely and avoid the harm when people come into the abominable environment.

Research on New Lifting Moment Limiter

Abstract: Lifting moment limiter can avoid the accident caused by overloading and make the operation of the crane more reliable and safer.described the working theory of the lifting moment limiter and devised a new kind of system based on MCU 78E516 and LCD MGL-240128,which supports Chinese character interface and is more reliable and powerful.

Temperature Compensatory Methods of Optical Current Transformer

Abstract: The main factors on temperature stability of optical current transformer were analyzed.The research progress of the two compensation methods(polarization analysis of incident light and the nonreciprocity of Faraday effect)was briefly summarized.Comparative measurement using permanent magnet as reference source applied in Optical Current Transformer was proposed to overcome the deficiency of the above ways.The influence of material's Verdet constant and linear birefringence caused by varying environmental factors could to compensated.Theory analysis of the method and related experiment results have proven its feasibility.

Electric Power Remote Monitoring and Management System Based on VB and LabView

Abstract: The management of electric power remote monitoring is the key techology to implement electric power automatization.Puts forward and develops a new fashioned electric power remote monitoring system on the basis of VB and LabView.Moreover,the structure of the system and the flow of master station software on the basis of VB and LabView are introduced.Virtual measurement results processing and the key technology of sharing information between VB and LabView is systematically expounded.

Design of Multi-channel Temperature Control System Based on DSP

Abstract: Describes the design of the multi-channel temperature control system based on DSPBoth the hardware modules and software modules were providedDSP uses TMS320VC5402Using Analog Multiplexers and A/D to realize the input of eight channel temperature samplesUsing D/A and power amplifier to realize the control of heaterThe system control the heater by a certain PID algorithmThe result of Experiments indicate that the system is fast in control speed and accurate in control precision

Way to Locate Image Point on CCD with Centroid Algorithm

Abstract: Centroid algorithm is a high accuracy method of locate the image point on CCD.But large amount of data need handling,which makes it difficulty to meet the demand of high respondency and real-time.When designed the data acquistion and processing system of a high accuracy photoelectricity on-line measurement system,high speed A/D and DSP were used to design the hardware circuit of on-line thickness gauging system.The particular hardware processing circuit and software design methods were introduced,which made the subdivision and centroid algorithm come true with hardware circuit,and resolved the high sampling speed and real-time problem which the normal system can not do.The measurement accuracy and real-time ability of system were highly increased.

Intelligent System to Measure Liquid Height by Ultrasonic Based on Single-chip Microcomputer

Abstract: The principles and the frame of the system to measure liquid height by ultrasonic is presented.The circuit of exciting ultrasonic and sampling environmental temperature is detailed.The sightless area and the time measure error are removed basically by an effective method of transforming received signal.Firstly,the received signal is magnified by the method of STC(Sensitivity Time Control).Secondly,a linear encircling demodulation is used on the magnified signal.Finally,the desired signal is attained by the method of differential circuit and zero-cross demodulation.At the same time,temperature error is compensated.Adopt modular programming and develop successfully this system on a single-chip microcomputer.The measure results show that the system can obtain higher precision and better adaptability.

Research of On-line Testing Method for Transformers Iron Loss and Copper Loss

Abstract: The theory of the transformers loss is first introduced.By the comparison with the traditional testing method of transformers loss,one new method of testing for transformers iron loss and copper loss based on the sum of current and voltage is presented.And the realizable theory of online testing for transformers iron loss and copper loss is discussed in detail.Three-phase autotransformer with pure resistor load is chosed for the simulation experiments.Take one phase for example,the figure of circuit for simulation experiments is showed.The online testing data of the iron loss and the copper loss are obtained,and the error of the data is analyzed.The correctness of the theory of online testing for transformers iron loss and copper loss is confirmed.

Design of Portable Vibration Analyzer Based on ARM Processor

Abstract: Introduced the design idea of embeded equipment based on ARM system structure processor. Adopted ARM7TDMI processor to be the development groupware in the kernel, used GCC software developing equipment of GNU, design and realize a kind of portable instrument which applied in vibration measure analyse field,contraposed the weak point of the old instrument,put forward the idea of improvement on the software and hardware design,the function was improved notably.Another characteristic of this equipment is a friendly figure interface,can present kinds of spectral picture. This product can also be used in open air monitor field,carried it conveniently.

Unified Modeling Language and Its Application for Modeling

Abstract: Introduced the main concepts and contents of UML(Unified Modeling Language)briefly.In order to show a clue to the application of the UML,a simple model for the Multi-elevator system was given by the UML.

Design of Discharge Circuit for ESD Simulator

Abstract: Due to the effect of distributed parameters,it is difficult for the electrostatic discharge(ESD)simulator consisting of lumped parameter to generate the current that is prescribed in the IEC61000-4-2 standard.By analyzing the electrostatic discharge current waveform and given parameters,have designed a kind of discharge circuit called human body/metal model.By means of simulation,all parameters of the circuit have been made certain.Aimed at the effect of distributed parameters,have offered a group of design curve that is the relative error sensitivity of the lumped parameter to every parameter of discharge current.By means of the cluster of curve,designer will be able to adjust the lumped parameters until the simulator generate the discharge current being up to the standard.

Recognition of Gas-solid Two-phase Flow Regime Based on LQV Neural Network

Abstract: The flow regime,as one of significant parameters characterizing the gas-solid two-phase flow,not only affects strongly its performances on pressure loss,heat transfer,mass transfer and so on,but also affects the measurement accuracy of other parameters (such as flux,phase holdup,etc.)as well as the operating performance of flowing system.The application of traditional measurement methods is limited in industry because they have some difficulties in really reflecting real-time and local distribution information of flow regime in the section of pipe.As a result,based on optical tomography,presented a method to recognize the gas-solid two-phase flow regime by means of LQV neural network whose structure,learning algorithm,training sample collections and so on were described in detail.The simulating results show that this method can preferably recognize the eight flow regimes of gas-solid two-phase flow.So a novel method is provided to measure the parameters of two-phase flow.

Lmproving SWNT Gas Sensors by Doping Atoms

Abstract: Single-walled carbon nanotube(SWNT)gas sensor is much more advanced than the traditional metal-oxide sensor in terms of sensitivity,selectivity,maneuverability,and so on.But only a few kind of gases can be detected by SWNT sensor because of the limited adsorption ablity of intrinsic carbon nanotubes(CNTS).Currently,Shu Peng and his coworkers have found that CNTs doped with B and N atoms are able to detect H_2O and CO molecules,respectively.The Theory of Semiconductor Impurities along with an ion-pair model is used to explain this new experiment phenomenon,based on detailed discussion of the mechanism of SWNT sensors.Doping CNTs with impurity atoms maybe a key method for solving the problem of SWNT sensors.

Design of Vibration Measurement Virtual Instrument

Abstract: Described a vibration measurement virtual instrument.Firstly,the general hardware platform was built by note-book PC and USB2008DAQ,and then the VI's functions were defined by software programming,and its exact design process was full discussed by taking signal analysis function for example.The instrument has a friendly interface,it can achieve signal generation,signal collection,signal analysis and mode analysis,etc.Some measurement tests were taken and the VI's result full accorded with theory result.That proves the function of the vibration measurement virtual instrument is achieved and the analysis results of the instrument is right.

Design of Intelligent Sensing System for Car Tire Safety

Abstract: Introduced a new kind design scheme of sensing system for car tire safety.The stress sensor and RF emitter was installed in car tire.It was transmited for receiver installed in car by wireless after gas stress data gathered which was processed.It sensed in time stress status by receiver and processor,so that driver adopted corresponding countermeasure.The key technologies such as the method of controlling RF emitter power,wireless communication and the anti-interference measures were emphasized.It has been proved by experiment that the system is able to obtain the required accuracy.

Embedded Industrial Devices Gateway Based on Internet

Abstract: Embedded industrial devices gateway is a new network interface to implement interconnecting between field devices and Ethernet,which is fit for rebuilding current fieldbus network.The embedded industrial devices gateway realized not only the integration with Internet,but also the direct communication between field devices and Internet without abandoning actual fieldbus network.Brought forward an effective solution used to rebuild current fieldbus,based on the analysis of the new requirement of the industrial remote monitoring and control,the limitation of the field bus,and the developing trend between fieldbus and Internet.Furthermore,proposed the protocol-transform-model between typical fieldbus network and TCP/IP network.Finally,the expounded the application method in industrial automation,and pointsed out the application foreground and future tendency of embedded industrial devices gateway.