Chinese Version Light学术出版中心
Latest Issue
Issue 2 ， 2004
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A way of extracting observed stars for star image simulation
Abstract：A highly efficient and adaptive way of extracting observed starts from the sky is proposed according to the characteristics of celestial coordinates for real-time computer simulation of star images. By calculating the vertical FOV span to ameliorate the zoning method, an improved zoning method is proposed for identification of nodes in the zone of celestial sphere. Measures to improve its efficiency further, such as shortening span of zone, coordinate transformation, and two-step extraction, are discussed as well. Analyses indicate that the method proposed is highly efficient and adaptive, and suitable for real-time simulation of star images, and its logic description is simple to program.Keywords：star sensor;star image simulation;observed stars extraction- 45
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Published：2020-08-12 -
Application of quaternion matrix in resolution of aerospace camera image plane position
Abstract：An improved quaternion transformation matrix with function equal to that of corresponding uniform rotation linear coordinate transformation matrix is proposed, and the equation of the corresponding ground scenery position in image plane is derived using the quaternion transformation method and the uniform linear coordinate transformation method and the real-time resolution method for corresponding ground scenery position in image position is derived using real-time resolution method for quaternion. Computer simulations made for the two solution methods proves that the solution speed of improved quaternion matrix arithmetic is faster than that of the coordinate transformation arithmetic.Keywords：aerospace camera;quaternion;image motion compensation;coordinate transformation- 59
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Published：2020-08-12 -
Design and accuracy analysis for drift adjusting rotary axes of space camera
Abstract：The drift adjusting rotary axes of space camera mainly provides the angular motion control of the camera in the horizontal direction, and performs the real-time control of azimuthal drift to realize the image motion compensation in the photo-taking process. The drift adjusting rotary axes determine to a large extent the photo-taking accuracy and the drift control accuracy of a camera. For the utilization of the plane of highly rigid external pedestal as the orbital plane of the thrust bearing, and the adoption of composite enclosed design in both radial and axial directions, the structure of rotary axes features light mass, free rotation and high rotational accuracy. A number of factors having effect on the accuracy of rotary axes, such as radial runout and angular swing, are discussed, and a quantitative analysis has also been made for the axial shaking error resulting from the form and position errors of the rotary axis components. The measured shaking error of the rotary axes indicated that the accuracy of the axes selected is 3.8", and satisfies the general technical specification of being within 5".Keywords：space camera;rotary axial series;error analysis- 51
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Published：2020-08-12 -
GPS/INS integrated navigation system
Abstract：Through the discussions on the advantages and disadvantages of inertial navigation system(INS)and global positioning system(GPS)for aircraft, and the application of Kalman filtering method in the integrated positioning system, GPS/INS integrated navigation system, a data fusion method based on neural network is proposed. The neural network framework of the integrated navigation system is a single hidden layer three-layered neural network with 4 input/output neurons, and the number of hidden layer neurons based on 256 training samples and obtained using empiric formula is 8, and mathematical models have been established for inertial navigation system and data fusion. Training and simulation were made with this neural network using the neural network training program compiled with MATLAB, and experimental results indicate that the integrated navigation system has a longitude error of 9 m, and a latitude error of 8 m, and in comparison with separate GPS and INS, the accuracy of integrated GPS/INS has been improved.Keywords：inertial navigation system;global positioning system;neural network;data fusion- 57
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Published：2020-08-12 -
Optical fiber positioning unit with two electromotors
Abstract：In the LAMOST(Large Area Multi-Object Fiber Spectroscope Telescope)project, 4 000 optical fibers are mounted on a focal plane of 1.75 m in diameter, the position precision is less than 40 microns, and the positioning time is less than 30 minutes. By analyzing the typical method of positioning optical fibers for astronomic observation and taking into consideration the structural characteristics and the operating requirements of LAMOST, a new plan has been brought forward for positioning of optical fibers in a local plane divided into many unit zones. The unit turns round through 360°, and the locomotive block moves in a linear guide in every unit zone. So the optical fiber can reach everywhere in the focal plane. Experiment results show that the standard deviation of repeat error and positioning error are 22.17 μm and 30.71 μm rms, respectively, and the positioning precision of this system can meet the demand.Keywords：optical fiber positioning;two-electromotor unit;Detection- 51
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Published：2020-08-12 -
Structure of water cooling double-crystal monochromator
Abstract：The thermal load on the first crystal of a synchrotron radiation double-crystal monochromator is discussed, the cause for the thermal distortion is analyzed, and attempts were made to calculate the energy distribution over the first crystal using SHADOW software. Simulation analyses were made using finite element method to analyze two types of water cooling structures. Simulation results indicate that the structure of plot style with curved surface can be used to achieve better results, and it can be applied to a power density of about 1.0 W/mm2.Keywords：double-crystal monochromator;synchrotron radiation;water cooling structure- 49
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Published：2020-08-12 -
Measurement of aerial point target distance using dual-band infrared imaging system
Abstract：By establishing a model based on the law of infrared radiation transmission in atmosphere and the characteristics of infrared imaging system for the apparent contrast between the target and the background, and analyzing the model over two wavebands to formulate the distance measuring formula and the distance resolving power formula, a passive distance measurement method is proposed for aerial point target distance measurement. The relationship between the distance resolving power and the distance is calculated for different weather conditions. The calculation results indicate that the method proposed is suitable for engineering application.Keywords：infrared imaging system;apparent contrast;extinction coefficient;Distance measurement;distance-resolving power- 95
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Published：2020-08-12 -
SNR limitation of high-speed visual image system detection distance
Abstract：Whether a high-speed visual image system can do high-speed photography to satisfy the recording need is a hot topic for researchers in the range test field. This involves several issues, such as image field, detection distance, and information acquisition capability, and detection distance is the core issue for necessary consideration. It is concluded from the analyses of the factors having effect on detection distance in the two systems that, in a high-speed and high resolution visual image system, there is a contradiction between frame rate, resolution, and SNR. SNR decreases as frame rate and resolution increase, and SNR is the primary factor which limits the system detection distance, and therefore, a high-speed visual image system can not reach the same distance as a high-speed photography system.Keywords：high-speed visual imaging system;high-speed photography;detection distance;SNR- 64
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Published：2020-08-12 -
Tracking mobile target by composed Kalman leap prediction method
Abstract：By using the input matrix of state equation G(k) to make up the acceleration term of the constant angular velocity model, establishing the deviation ratio of state noise and test noise Q/R and optimizing the ratio Q/R for theodolite following the principle of least standard deviation of Kalman predication curve from practical curve, composed Kalman leap prediction method is proposed for application to a theodolite for tracking mobile targets. Simulation research was conducted for tracking mobile targets at different target beacon velocities with predictions of 1, 2 and 3 leaps made. Simulation results showed that composed Kalman leap prediction method can be applied to a theodolite for tracking mobile targets.Keywords：target tracking;Kalman prediction;Tracking;mobile target;simulation- 45
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Published：2020-08-12 -
Comparison of grazing incidence and grazing emission X-ray fluorescence analysis technologies
Abstract：The grazing emission X-ray fluorescence(GEXRF)technology is compared with the grazing incidence X-ray fluorescence(GI-XRF)technology in terms of experimental set-up detection limit,range of elements accessible,matrix effect and accuracy.The results of comparison demonstrate that while it has the disadvantages of higher detection limitation and thinner critical thickness,GEXRF has the advantages of lower requirements for experimental set-up,more sensitivity to light elements(4Keywords：X-ray fluorescence analysis;grazing emission;grazing incidence- 42
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Published：2020-08-12 -
Image encryption based on discrete chaotic maps
Abstract：Discrete chaos is used to generate cipher systems because it is easy to create, sensitive to initial value and similar to white noise of statistical nature. A "quasi-Feistel network" algorithm is designed using discrete chaotic maps for image encryption/decryption. All secret keys of the algorithm are generated by different chaotic maps, and this improves difficulty of decryption. Permutation and substitution consist of SP networks with good cipher performance. Permutation is also controlled by cipher to improve algorithm complexity. Safety is enhanced by the output of encryption which strongly depends on nonlinear coupled secret keys. All of white text is encrypted during each iteration of "quasi-Feistel network", and this improves the encryption efficiency. Finally, a simulation test is conducted by taking the image Pout in Matlab as an example, and the simulation results show that the algorithm proposed possesses perfect safety and efficiency.Keywords：image encryption;discrete chaotic maps;SP network- 48
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Published：2020-08-12 -
Implementation of integer wavelet transform basedon lifting scheme on DSP
Abstract：Integer wavelet transform based on lifting scheme and its implementation on hardware are discussed in theory, and IWT of filters LEGall(5,3)and Sweldens(13,7)usually used in image coding are implemented on TI TMS320c6000DSP, and then the discrete wavelet transform based on filter bank scheme is implemented on DSP. The comparison of IWT with DWT in hardware operating time shows that IWT is always faster than DWT. The results reported on the graphs can be used to estimate the number of images processed by these algorithms per second and to assess the performance of DSP in fulfilling image coding tasks. So the IWT based on lifting scheme is an algorithm with higher execution speed and it is easier to implement on hardware, and it can be used to achieve compression of image without loss.Keywords：image processing;lifting scheme;integer wavelet transform;DSP- 47
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Published：2020-08-12 -
Laser radar image acquisition and display integrated system based on DSP and CPLD
Abstract：A laser radar image acquisition system based on DSP and CPLD, its operating principle, makeup, hardware and software design are discussed with TMS320C5402DSP used as the controlling and image processing core in the system, the laser radar image data is acquired and stored by a DUALRAM, and their address signals are generated by CPLD according to four image synchronization signals: FRAME, LINE, COL and WRITE. Finally, the original image and processed image are both displayed on the color TFT-LCD. In addition, by USB interface this system can communicate with PC and implement image storage, redisplay. Generally, this system provide a powerful analysis and testing tool for the study of Laser range imaging radar and range image.Keywords：image acquisition;laser radar;DSP;CPLD;color TFT-LCD- 61
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Published：2020-08-12 -
Establishment and application of artificial stereovision simulation system
Abstract：In order to validate the artificial stereovision modules, an artificial stereovision simulation system is established using the open graphics library OpenGL as the tool, setting up virtual cameras, placing virtual objects, taking virtual images, collecting information from the images, and reconstructing the virtual objects according to the interrelation among data collected, and finally comparing the reconstructed object with the original object, thereby checking the whole system or a particular test module for accuracy. Application results show that the simulation system can be used for stereovision research testing and simulation.Keywords：artificial vision;stereoscopic vision;vision simulation;3D reconstruction- 59
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Published：2020-08-12 -
Real-time correction of infrared image nonuniformity
Abstract：The nonuniformity of IR focal plane array, which causes image faint, greatly limited some industrial applications so that the nonuniformity must be corrected prior to the application of infrared imaging technique. A multi-point correction method, which makes use of the powerful computational capability and good programmability of TMS320C6201 DSP hardware, is therefore proposed to do automatically the real-time correction of infrared image nonuniformity. Experimental results showed that the infrared image nonuniformity real-time correction system based on DSP can do the correction in a simple way with satisfactory results.Keywords：infrared image;DSP;nonuniformity;real-time correction- 94
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Published：2020-08-12 -
Wavelet transform characteristics and compression coding of remote sensing images
Abstract：The statistical characteristics of remote sensing image are studied by using wavelet transform and presented definition of similarity for wavelet coefficient. The general distribution rule of wavelet transform coefficient and basic characteristics of remote sensing images, such as lesser similarity, complicated and abundant texture, lesser redundancy degree, are indicated by experiments, which are not beneficial to compression in high fidelity. The wavelet transform coefficient of remote sensing image has stronger local similarity, hereby a version of combining of DPCM with SPIHT is presented. The experimental results show that the new compression scheme performs better than SPIHT arithmetic in terms of image reconstruction quality and encoding/decoding speed.Keywords：remote sensing image;wavelet transform;sub-band similiarity;DPCM;SPIHT- 42
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Published：2020-08-12 -
Image processing for measurement of rocket's initial trajectory parameters
Abstract：Using the application of high-speed photography for measurement of rocket′s initial trajectory parameters, the measurement principle of rockets' initial trajectory parameters is introduced, several image processing methods, such as inter-frame-correlation, correlation filter, axes auto-detection are proposed for engineering applications. Practical use shows that rough positioning by inter-frame-correlation and edge tracking + positioning in small zone by correlation filter can reduce computation work and reach a positioning accuracy of 0.2 pixel, and the use of edge detection for axes auto-detect may keep the attitude angle measurement accuracy better than 0.5°.Keywords：image processing;axes auto-detection;rocket;initial trajectory parameter- 38
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Published：2020-08-12 -
Correction of CCD pixel nonuniformity
Abstract：The causes for CCD dark current and photoelectric response are theoretically analyzed. An algorithm based on the photoelectric signal is proposed for correction of CCD photoelectric response nonuniformity, and a coefficient is given for calculation of electronic quantity to be corrected as well. The interference is eliminated by varying the wavelength according to the effect of actual interference light. Simulation results indicate that the algorithm proposed can be used to effectively reduce the image noise resulting from CCD pixel photoelectric response nonuniformity.Keywords：charge-coupled device;nonuniformity;dark current;photoelectric response;correction algorithm- 72
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Published：2020-08-12 -
Calculation of field-emission for miniature X-ray source with finite element method
Abstract：An effective 3-D finite element model was constructed for the field emission array to analyse the field emission current over a single tip. Considering the periodicity of field emission array and the axial symmetry of the single tip model, only 1/4 of the single tip model was analyzed. The electric field intensity distribution over the tip surface was established through calculation with appropriate voltage boundary condition applied, and it was found that the electric field intensity was the strongest at the apex of the tip, and the field emission current was also the strongest there. The field emission current density distribution over the tip surface was established using Fowler-Nordheim function, and the emission current over the single tip established by integrating the current density all over the single tip surface was 7 μA. Field emission currents were calculated for different apex radii at the gate voltage of 100V, and the results indicated that the field emission largely depends on the apex radius. Total field emission currents were calculated for 100 tips with an apex radius of 8 nm at different gate voltages, and the results indicated that both emission currents and opening voltages were in very good agreement with actual measurements.Keywords：field emission cathod;finite element;Fowler-Nordheim function;spindt cathod- 89
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Published：2020-08-12 -
Etching of multiplayer grating using a narrow spectral band X-ray
Abstract：Theories and technologies of extreme ultraviolet, soft X-ray and X-ray regions have made great progress since 1970s, and multilayer mirrors have found wide applications in astronomy, microscopy, material science, synchrotron radiation applications, and plasma diagnostics for their high-reflectivity and good stability, however, they have a poor spectral resolution for X-ray fluorescent measurement and synchrotron radiation monochromator. The spectral resolution of the multilayer must be improved for some high spectral resolution measurements. The spectral resolution can be improved by etching the multilayer into a multilayer grating at different etching ratios by the average density calculation method. W/C multilayers were fabricated by magnetron sputtering and the multilayer gratings were made by normal optical lithography. The results measured by grazing-angle X-ray diffraction show that the multilayer structure in an etched multilayer grating has not been destroyed and the spectral resolution has been improved, which demonstrates that methods proposed for making etched multilayer gratings are suitable for further research.Keywords：Multilayer;grating;spectral band;etching;spectral resolution;etched ratio- 74
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Published：2020-08-12 -
Relationship between average etching velocity and laser pulse energy density during excimer laser direct etching
Abstract：In order to search for an economical high depth-width ratio micro-fabrication method and build up an excimer laser direct etching system, the relationship between average etching velocity and laser pulse energy density during excimer laser direct etching was investigated by using KrF excimer laser with a wavelength of 248 nm to ablate and etch glass material accurately located with a high-precision micro-motion controlling system. Experimental results showed that all the yielded grooves are V-grooves; the single laser pulse etching velocity decreases as the number of laser pulses increases; the depth of the yielded grooves becomes constant when the laser pulses add up to a definite number, there is an upper limit threshold for excimer laser pulse energy density in the etching process; and rectangular deep grooves or cylindrical deep holes can be produced by using parallel laser beams or dynamic control of etching process.- 54
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Published：2020-08-12 -
Design and simulation study of fuzzy parameter self-tuning PID controller
Abstract：The selection of PID parameters has direct effect on the controller performance and the man-work tuning needs much experience and skills, and plenty of time as well. In order to realize the PID parameter self-tuning, a fuzzy self-tuning PID controller which follows the PID parameters optimizing laws, and uses fuzzy logics to do automatic on-line tuning of PID parameters was designed for the temperature control system of a molecular sieve activating device based on PID control and fuzzy control. In comparison with conventional PID temperature control system, this temperature control system features high control precision, good adaptability, simple structure and less computation. The simulation shows its validity and practicability.Keywords：temperature control;PID control;Fuzzy control;parameter self-tuning;system simulation- 38
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Published：2020-08-12 -
Design of combustion optimization control system for powerplant boilers
Abstract：The incorporation of a boiler combustion optimization control system based on the artificial neural networks PID into the existing DCS control system makes it possible to use the advanced software to optimize the boiler parameters collected using the existing PCS control system. Experiments were made with a 300 MKW coal-burning power generator at four load points of 150 MK, 220 MK, 259 MK and 300 MK covering the normal operating range. Experimental results show that the boiler combustion efficiency can be increased by 1 percent.Keywords：boiler;burning control;forecast control of model- 56
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Published：2020-08-12
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