
For the harm of corona discharge to power system is great,it is necessary to detect the corona.As we all know,the ultraviolet wavelength which corona discharge emits is 200~400nm.In order to locate corona discharge accurately,a solar blind ultraviolet imaging system was designed by using the sun-blind band from 240 to 280nm.The high resolution lens,narrow band solar blind filter with the center wavelength of 254nm and external acquisition box were used to realize the function of image acquisition,image fusion and image output.An imaging experiment was went through to shoot high voltage equipment and the target far away from 10 meters on sunny day with 25℃.The background images,UV images and fusion images were acquired clearly.Likewise,another test was put forward to simulate corona discharge by the use of needle tip discharge in the lab,fusing collected corona and visible images.The experimental results indicate validity of the system.
The signal from photoconductive antenna of the Terahertz Time-domain Spectroscopy technology (THz-TDS)is so small compared with the background noise that need amplification by the lock-in amplifier.According to the basic principle of the lock-in amplifier and the characteristics of the THz-TDS,the programmable lock-in amplifier system for THz-TDS based on the AD630 is put forward,which be able to update the chopping frequency and bandwidth according to different samples or working states.The curve between outputs for the programmable band-pass filter controlled by the analog switches on different chopping frequencies and bandwidth can be got by the experiments.And the system’s weak signal detection ability is got by the simulation experiments.At last,in the case of the time-delay line moving speed to 1500 μm/s and continuous scanning,the SNR of THz signal is about 50 dB.The result shows that the system has the advantages of adjustable chopping frequency and bandwidth,good lock-in effect,small volume and easy to be integrated.
Most polarized light navigation sensors are designed according to the POL-neuron model.The main error sources are gain difference between channels and the relative angle error.To improve the measurement precision of polarization compass information,we propose an independent channel measurement method of polarization compass information.The atmospheric polarization information is measured by using three independent polarization measurement channels to obtain heading-angle information for navigation.We further design an independent channel polarized light navigation sensor via integrating the time division multiplexing technology,and propose the calibration method and error compensation algorithm.The experimental results show that the independent channel polarized light navigation sensor significantly reduces measurement error of polarization compass information (within ±0.05° after compensation).
Linear CCD has been widely used in low light detection,but it’s easy to operate the device into the nonlinear region if set incorrectly.Two factors of optical response-light intensity and integration time were analyzed in the article,and experiments were conducted to test and verify CCD nonlinear effects.Because of its flux-current response,LED light was researched to determine the relationship between the output and the light intensity.Relationship between CCD output and the integration time was also researched through changing integration time.Observing the two experiment results,transistor model was used to analyze CCD optical response and linear region together with nonlinear region was compared.The results show that CCD nonlinear effects are apparent and its excellent linear region should be made full use of in application.
In order to improve the performance of estimation in radar-photoelectric system,we proposed a track fusion algorithm with Unbiased Converted Measurements (UCM) of velocity.First,with the information of radial velocity provided by radar and angle velocity supplied by photoelectric system,we obtained the UCM of velocity in Cartesian coordinate and analyzed the statistical properties of UCM errors.By using the information of velocity,we provided a synergistic fusion algorithm based on sequential filtering.Simulations show that the algorithm with UCM of velocity provides a better performance of tracking and improves the convergence rate of velocity estimation.Moreover,the results also offer some beneficial references for track initiator and primary assessment of threat.
For the influence of some complex sea states such as coastal scenery and surface ripple in sea images,target detection based on the visible light image is a technical difficult problem of the current.This paper presents a method of structured random forests for target detection in sea images.The method first constructs random decision forest based on image block,applies structured learning strategy to the forecast output spatial of the constructed random decision forest,and then trains the random decision forest in the sample space,and finally classifies the testing image blocks as the target region and the background region through random decision forest.The experimental results show that compared with the Canny operator,the Threshold-Segment operator,and the Salience~~ROI operator,the method of this paper has significant advantages in the aspects of sea image target detection and uses low computation cost.
The motion parameters of aircraft and its external store can be obtained by photoelectric theodolite in flight test,but due to large distance measured or target blocked,it’s difficult to capture target very fast.After adding GPS receiver on the aircraft,we can get geodetic coordinate in real time.After the real-time acquisition data coded thought the telemetry channel,the ground machine can demodulate coordinate of the aircraft .The PCM data Stream can be received from the airborne transmission stream through the PCM telemetry receiving channel which is integrated on photoelectric theodolite.At the same time,the geodetic coordinate of aircraft can be demodulated from the data stream in real time.By this way,the external guide for photoelectric theodolite can be achieved after the data processed and transmitted to the control system of photoelectric theodolite.Application results show that the guided precision has good performance in the remote target capture and good results in practical application of this technique for photoelectric theodolite.
Most algorithms based on Constant False Alarm Rate (CFAR) which are used to detect ship targets often produce problems such as time waste,lower efficiency,missing detection and so on.To solve the problems caused by slipping windows,an algorithm based on CFAR and adaptive windows is proposed.Firstly,global saliency is measured to find the target potential regions.According to adaptive windows setting condition,target regions are divided into inside regions and edge regions: background parameters after getting rid of target pixels are used to detect inside regions;targets detected and global background parameters are united to detect edge regions.Final result is achieved by getting the two parts together to subsequent processing.The experiments show that the algorithm proposed in this paper can locate regions of targets fast and truly,depict the shape of the regions accurately and perform well for ship detection.
Due to decline problem of tracking accuracy caused by acceleration estimation inaccuracy in Hybrid Grid Multiple Model (HGMM) algorithm,a new HGMM algorithm based on Current Statistics (CS) model is proposed,since the current acceleration mean in CS model can reflect true target motion model more accurately.Grid partition is performed by estimation of the acceleration mean in CS model,and possible model set of the target is generated online.Then,interactive multiple model algorithm is adopted to track target.The proposed algorithm performance is tested and compared in general and strong maneuvering scenarios,and simulation results demonstrate that the proposed algorithm not only improves the accuracy for maneuvering target tracking,but also can be applied to most of the tracking scenarios.
The Surface Plasmon Resonance (SPR) sensor is widely applied in the immune reaction detection of biomolecules.For the self-developed angle scanning surface plasmon resonance sensor,the kinetics detection and kinetics data analysis software system were developed according to Langumair model,and the data processing method of polynomial fitting combined with centroid method was proposed.The established method could effectively inhibit the interference on SPR resonance angle detection by noise,ambient temperature and mechanical vibration in the process of detection.The immune reaction kinetics of mice antigen and antibody was detected.Its association rate constant ka≈2.05×104 M-s- and issociation rate constant kd≈0.005 s-.The feasibility of the established device and data processing method was confirmed.This method could effectively improve the accuracy and capacity of resisting disturbance of angle scanning surface plasmon resonance sensor,and it is worthy to be applied and promoted.
For the non-uniformity of wide field line CCD image,a uniform method based on image pixel gray value compensation is introduced.The radiation luminosity of line CCD is calculated,which is developed by the micro-area of different coordinate in the line object.Then the relation between pixel values of the center place and the other place is induced.In order to accomplish the uniform of large field line CCD image,the model of gray value compensation is built.A plenty of pavement images captured by large field line CCD are processed by the proposed method.The results show that the method is of great flexibility,robustness and applicability.
Aiming at the needs for calibration device of mine fire smoke sensor,verification method of mining smoke sensor is proposed.According to Lambert-beer's law and the shading rate of the measuring beam,the shading rate at which laser beam passes through one meter thickness smoke is calculated.Based on the principle of laser scattering measurement,the aim for high sensitivity measurement of low concentration smoke is achieved.Utilizing high speed synchronous trigger calibration scheme of smoke sensor and external optical power meter,the difficulty of lack of standard material is solved when calibrating.With characteristics of fast response,high measuring precision and high sensitivity,a set of device has be realized and mainly composed of a smoke generator,the laser measuring unit and the processing circuit.The device is also applicable to factory calibration of ground fire smoke sensor of particle type.
A crucial parameter for the successes of stereo matching algorithms is the disparity search range estimation.It is necessary to estimate the disparity search range between stereo pairs automatically in real time systems.A dual-mode camera which can be used to take stereo images or depth maps is developed in our work.Under the constraint of the depth map with the same spatial resolution as the stereo pairs,expected disparity of each pixel is limited within a narrow search range.For images captured in our lab,the process of stereo matching is sped up more than 3 times and the error percentage is reduced by 2% compared with the method that estimates the minimal and maximal disparity between stereo pairs.
In order to overcome the shortages of detection of quartz crystal specific rotary power measurement by rotate polarizer method,these shortages are big error,low precision and poor practicability etc.Put forward a measurement for quartz crystal specific rotary power measurement based on liquid crystal variable retarder (LCVR).Change the driving voltage of liquid crystal variable retarder,accurately control the liquid crystal phase retardation,and modulate the polarized light.By measuring the Stokes parameters according to polarization modulation method,real-time and accurate measurement for quartz crystal specific rotary power is done.Detection of polarized light signal using PIN photodiode,after the photoelectric conversion,signal conditioning circuit is used to achieve signal processing,signal collection etc.Process collected data and display.The experimental results show that the method measurement accuracy is 0.57%.
In recent years,as China's car ownership increasing,vehicle body size measurement has become an important part of the car running safety testing.Traditional manual measurement operates with low accuracy and efficiency.Taking advantage of the image information on cars' surface and combining with the image edge detection,connected component labeling,image registration and fusion and edge localization,a visual measurement algorithm of vehicle length is presented now.Experiment results of the vehicle length measurement show that the proposed algorithm can achieve a relative accuracy of 1%,and its time consumption is less than 3 second.Cars' body size measurement can be achieved with a high accuracy and little time consumption,which offers as an effective supplement for comprehensive performance testing of vehicles and intelligent transport system.
To improve the optical measurement accuracy of exo-atmosphere spacecraft’s miss distance,a processing algorithm based on the same frame film data of multi-devices was presented.Firstly,the basic principle of miss distance measurement by optical method was put forward.Secondly,the influence on exo-atmosphere spacecraft’s miss distance by the angle measurement data errors was analyzed.Then,the sparse parameter algorithm based on the same frame film data of multi-devices was set up,and the precision of miss distance influenced by measurement errors was analyzed.Finally,the simulation results in typical cases were supplied.The simulation results show that the CCD exposure time error and the focal length error must be corrected in the optical measurement of exo-atmosphere spacecraft’s miss distance,and the precision of miss distance can be improved by using the redundant same frame film data of multi-devices.