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Issue 4 ， 2008
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XPS study of Ge1-x Cx thin film prepared by RLVIP technique
Abstract：Ge1-xCx thin films are deposited on germanium substrate by Reaction Low Voltage Ion Plating (RLVIP) technique. Germanium is evaporated by e-gun, and methane is ionized as reactive gas. Ge1-xCx thin films, with carbon content ( x ) raging from 0.23 to 0.78 at different depositing rate are fabricated at the same condition. X-ray Diffraction (XRD) tests indicate the films are amorphous. Chemical bonding properties are systematically investigated by X-ray photoelectron spectroscopy (XPS). It is observed that chemical bonding with different hybridization which depends on C concentrations. As x higher than 0.78, carbon bonds to hydrogen; x is in the range of 0.53 to 0.62, bonding property is carbon-carbon tetrahedrally and/or graphitic; x is lower than 0.47, the component can be related to Ge-C bond.Keywords：Ge1-xCx thin film;RLVIP;XPS;Ion assisted- 32
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Published：2020-08-12 -
Optimization of S-curve intensity control model for laser direct writing
Abstract：An optimization method for S-curve intensity control model is proposed for further improvement of joint quality during direct writing closed line. The relationship between joint quality and S-curve parameters is established first, then the radian θ and radius R used in the control function is optimized, and finally the model of joint length after optimization is established. The joint length after optimization can be determined by the radian θ. Experimental results indicate that the proposed optimization method can further increase the valid transition area length and reduce the exposure dose distribution variation rate at the joint area. And the joint length using the proposed optimization method is just 2 times of joint length using slope-line control method. Therefore we can conclude that the proposed method improves the line quality with guarantee of writing efficiency.Keywords：laser direct writing;S-curve intensity control method;joint quality;exposure dose distribution- 48
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Published：2020-08-12 -
Tomographic imaging of tissue using confocal endoscope
Abstract：In order to obtain tomographic image of tissue, a confocal endscopic imaging system is established, its axial and lateral resolution has been measured and analyzed, and its application in pig skin has been investigated. First, based on the requirement of system, principles and configuration of system are presented. Then the theoretical values of spatial resolution are shown in confcoal endoscope. Finally, the system is tested, and the reason for difference between measuring date and theoretical value is illuminated. Experimental results indicate that its axial and lateral resolution is respectively 10 and 1.9 , and it can be used to obtained tomographic image in pig skin.- 22
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Published：2020-08-12 -
Error analysis of tracking mirror for laser tracker system
Abstract：Laser tracker system (LTS) is one of the latest portable three dimensional large size coordinate measuring machines (CMMs). It can measure moving object coordinates with the advantages of broad range, high speed and high accuracy. However, its measuring accuracy is highly dominated by the geometric errors of the tracking mirror mechanism. Proper modeling and error analysis of LTS is essential prior to use it for metrology. The kinematics model and tracking mirror center offset model of LTS have been developed, based on the research on the structure and working principle of LTS, These models can describe not only the motion but also the geometric variations of LTS. The error of LTS base point position, tracking mirror tracking target retro-reflector and tracking mirror reflective surface out of vertical to laser beam is deeply analyzed. Theoretical analyses have demonstrated that the gimbals axis misalignment, tracking mirror center offset, base point position variation and laser beam reflected point non-coincidence with base point are the key contributors to measuring errors of LTS. In order to ensure the laser beam reflected point position coinciding with base point and the position unchanged in the course of LTS tracking the target retro-reflector, the distance between the tracking mirror surface and rotation point should be minimized in the structure design of tracking mirror.Keywords：laser tracker system;error analysis;tracking mirror;modeling- 35
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Published：2020-08-12 -
Research on a Compact Digital X-ray Imaging System
Abstract：Digital X-ray imaging inspection technology is the developing trend of X-ray inspection, the compact digital X-ray imaging system，which adopts X-ray sensitive CCD as detective device, has the characteristics of small volumn, high resolution, good real-time character. This paper introduces the development of the compact digital X-ray imaging system based on X-ray sensitive CCD, describes the working principle of X-ray sensitive CCD. According to the selected CCD, dirver, A/D, data acquistion and communication curcuits are designed and manufactured. The system communicates with computer through USB2.0 interface, which supplies power for the system, no additional power supply makes it have simple constructions. The resolution testing results instruct that the resolution of this imaging system is higer than 10lp/mm.Keywords：X-ray imaging;X-ray sensitive CCD;resolution;Radiographic dosage- 23
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Published：2020-08-12 -
Error compensation based on RBF in optical encoders
Abstract：A new method to the correction and compensation of dynamic error of the optical encoder was presented, to which the neural network and the digital signal process technology were both applied. In the paper ,the modeling method based on the Radial Basis Function（RBF）was set up, in which the output was test value of the high precision instrument and the input was angle value of sample points. According to the inhibit condition between the test value and the output of the network, adjusting power factor formula and the center and width of the radial basis function to make the model have a good learning ability and generalization ability, the error curve was recovered. The relationship between the sampled angles and the errors can be determined by training the neural network. After the sampled angles were measured, the unknown error of the encoder can be calculated via a trained neural network even if the error was nonlinear. The characteristic of this method was that，it only use the test data and there were no needs for knowledge of the reason for the error and the experience about the error form. Because the model was set up with too many parameters and lots of operation, the high-speed controller was needed. The TMS320LF2407 was chosen in the design. The device offers the enhanced architectural design of the CPU for low-cost, low-power, and high-performance processing capabilities. Also it offers increased processing performance (30 MIPS) and a higher level of peripheral integration More than that, the LF2407 incorporates one 32K 16-bit Flash EEPROM module in program space .The LF2407 Flash does not require a dedicated state machine, because the algorithms for programming and erasing the Flash are executed by the DSP core. The parameters of the model can be reserved on time by using the advantage of “in-target” reprogram ability of the flash, and the error correction for the system can be achieved without disassembling the system. Flash makes the update of program，system maintenance and upgrade easier as well. The testing results show that the precision of system error by this method is enhanced 3-5 times even advanced by roughly an order of magnitude. And not only the error of each network point but also the interpolated network point can be corrected automatically .The practical application proves that the precision of measuring system is improved greatly by using the RBF model as error compensation, and the nonlinear effect on the system is reduced.Keywords：optical encoder;neural network;DSP;error compensation- 43
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Published：2020-08-12 -
Simulation and experimental investigation of laser bending of silicon sheet
Abstract：A new method in pulsed laser bending of single-crystal silicon was presented in this paper. An analytical model was developed to describe the spatial-time characteristics of pulsed laser. In order to simulate the laser bending of process, the FEM software ANSYS was used, and the temperature field was predicted with stress-strain field in the bending process. The periodic transformation of temperature field and stress-strain distribution during pulsed laser scanning silicon sheet was analyzed, and the research results indicate that the mechanism of pulsed laser bending silicon is a hybrid mechanism, rather than a simplex mechanism of TM or BM. This paper also gets silicon sheet bended by scanning 6 times with pulsed laser, and the final bending angle is 6.5º, in which the simulation reaches well agreement with the experiments.Keywords：silicon wafer;pulsed laser;laser bending- 48
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Published：2020-08-12 -
Development of CCD Laser Displacement Sensor for High-Speed Measurement
Abstract：A new type of CCD laser displacement sensor for high-speed measurement is introduced, which can be used to measure the displacement of moving object or high-speed vibration by the mode of High-speed and real-time. The sensor system is composed of optical system, linear CCD with 7500 image elements, high-speed analog-to-digital converter (ADC) that converts at sampling rates up to 40 mega samples per second (MSPS), high-speed First-In,First-Out (FIFO) memories with clocked read and write controls, comparator selecting circuit and digital signal processor(DSP). Because the self-adapting control method is adopted, the light intensity of laser is modulated by setting external resistors to adjust separately the oscillation frequency and output current of laser, so that make suitable to various specific use or situation. Additionally, storage data from high-speed A/D converter and read data from high-speed FIFO can be controlled by the comparator selecting circuit that is specially designed, then only useful signal of image elements outputted by CCD is memorized by FIFO. Therefore, the burden of DSP is alleviated, and both data acquisition and process for CCD sensor signal can be carried out synchronously. This system can be used in the field of high-speed measurement of displacement. The results of experiment show that the velocity of data acquisition can reach to 40M and the minimum sampling interval is 0.1ms.Keywords：laser;Linear CCD;sensor;DSP;high-speed data acquisition- 64
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Published：2020-08-12 -
Structured Light System Model and Calibration Using Off-the-shelf Components
Abstract：Based on projection geometry matrix model and trigonometry analytical model, utility structured light system mathematical model was established, according to characteristics of off-the-shelf digital camera and projector such as high precision of inner structure parameter and steady operation. A calibration scheme for projector was presented that corresponding relation between DMD elementary points and space standard points was established in the presence of digital camera that endue projector with vision function and orthogonal Gray code patterns projected to calibration board. As base of above mathematical model, correction board based on colineation characteristic was designed, and camera lens distortion parameter separated from system parameters was calibrated separately by image method. Mathematical model, calibration formula and correction board are presented. Finally calibration and measurement experiments were done. Feasibility of above scheme was certified by simulation system. Measurement relative error of simulation system is above 0.2% and that of real system is less than 0.7%. Complex surfaces reconstructed by real system have good visual effect.- 34
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Published：2020-08-12 -
Round-hole orientation error analysis based on the structured light stripe vision sensor
Abstract：Binocular stereo vision measurement model is used to inspect the spacial position of round hole or similar round hole based on the stereo image-pair. The stereo vision sensor does not meet the need of some particular visual inspection system, especially for the flexible visual inspection system based on the industrial robot platform, because of the limits of the cost, volume, weight and so on. Based on the structured light stripe vision sensor composed with one camera, the two-step method to inspect the hole center coordinates is presented, and the x, y, z coordinates orientation error is analyzed exhaustively. According to the error analysis, the z coordinates measurement precision excels ±0.25mm, x and y coordinates measurement precision excels ±0.006mm respectively for the practical inspection application system. It shows that the method is valid by experiment and greatly expands the actual appliance of the structured light stripe visual inspection system.Keywords：structured light stripe vision sensor;round hole or similar round hole;orientation;error analysis- 35
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Published：2020-08-12 -
A novel compliant linear guiding mechanism and analysis of kinetic precision
Abstract：The Roberts approximate straight-line mechanism can be use to design new compliant linear guiding mechanism with large stroke and high precision. It is suitable for one-piece (monolithic) manufacturing due to there are no crossing parts in such a mechanism. A Roberts mechanism can be determined by four geometric parameters, and the location of the tracer P is the most important one. By analyzing the pseudo-rigid-body model of a Roberts mechanism, the location can be optimized to maximize the straight-line distance. A method based on the contour map of linearity is proposed to estimate the optimal value, then the finite element analysis is used for little adjustment. A linear guiding mechanism can be constructed by two Roberts mechanisms in parallel. Such a guiding mechanism is designed and fabricated. The finite element analysis and experimental results show that while its stroke is large than 1mm, the axis-offset can be limit within 1umKeywords：Roberts mechanism;compliant mechanism;linear guiding mechanism;linearity- 64
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Published：2020-08-12 -
Fabrication process analysis for nano-positioning stage based on silicon bulk micromachining
Abstract：The fabrication process of a nano-positioning stage with a high aspect ratio and big dimension is presented in this paper, which is based on bulk micromachining. The effect of deep reactive ion etching and the technology of protecting the backside for the etching silicon on the structure are analyzed. Some factors causing nano-position stage failure are identified, and advices are provided for avoidance of these failure. Moreover, an effective technique of fabricating vertical sidewall piezoresistor in plane is proposed and used to fabricate piezoresistor in this nano-positioning stage. With adjusting DRIE parameters method a high aspect ratio and big dimension backside windows for releasing the structure and electrostatics comb structure of 2.5μm wide and 50μm thickness were successfully released. A high aspect ratio nano-positioning stage integrating displacement sensor has been developed.Keywords：silicon bulk micromachining;DRIE;paste silicon technology;sidewall piezoresistor in plane;nano-positioning stage- 34
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Published：2020-08-12 -
Study on Generalized Minimum Variance - Fuzzy PID Control Method for Giant Magnetostrictive Actuator
Abstract：Abstract: Objetive: In order to overcome the significant impact of hysteresis on positioning precision when giant magnetostrictive material actuator applied for fine positioning, under the condition of the hysteresis compensation, adaptive PID control method is studied and a fuzzy PID control method based on generalized minimum variance （GMV）principle （GMV-Fuzzy PID） is established. Method : First, the main idea of generalized minimum variance principle is introduced and the relation between parameters of PID controller and plant parameters is derived. Then, according to above relationship, fuzzy rules, with error E and error variation EC as input and the parameter of k in above relation as output, is setup. Finally, combining the real-time identification of plant parameters in adaptive mechanism with the output of GMV-Fuzzy controller, PID parameters are reached to fulfill displacement control for GMA. Result: Experimental results indicate that GMV-Fuzzy PID controller can shorten the consuming time of each execution step by 0.0154 s, and RMS of tracking error only reduce 0.036μm, comparing with fuzzy PID controller. Conclusion: It can overcome the impact of inaccurate hysteresis and system modeling or disturbance, improve real-time ability without the expense of precision.Keywords：giant magnetostrictive actuator;generalized minimum variance;Fuzzy control- 45
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Published：2020-08-12 -
Non-valve piezoelectric fountain micro-pump by sound control circuit
Abstract：Abstract: The article presented a kind of non-valve piezoelectric fountain micro-pump by sound control circuit. The sound control circuit controlled the non-valve piezoelectric pump to open, close and fountain state. Without the signal generating device, the sound control circuit could drive directly the piezoelectric pump to work. The article expounded the working principle and design structure about the sound control circuit. The sound control oscillating and switching circuit board is designed and manufactured. It combined with the non-valve piezoelectric fountain pump to carry on the system debugging. The experimental result indicated that the fountain state of piezoelectric pump changed along with the outside sound frequency and oscillation amplitude. When the frequency and the oscillation amplitude were higher, the non-valve piezoelectric pump cascaded to increase on the height and the output flow rate. The piezoelectric pump attained the best spraying result when the sound frequency and the basic frequency of piezoelectric pump created a resonance.- 51
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Published：2020-08-12 -
Research on exoskeleton multi-fingers measurement robot
Abstract：A novel exoskeleton multi-fingers robot to measure the Extravehicular activity spacesuit glove (EVA glove) joint’s mechanical characteristics is presented. The exoskeleton finger based on planar four-bar parallelogram mechanism has enough stiffness and can exert forces in two directions, finger joint can rotate about a fixed center that avoid disturbance between finger and glove. The length of phalange of manipulator can be regulated for adapting to gloves. According to finger special mechanical structure, a kinematic model is given. Based on the dynamical model of exoskeleton robot finger the μ-synthesis robust controller is presented. System uncertainties are analyzed. The load dynamics are represented by a feedback uncertainty model. The proper control model is built. The trajectory tracking experimental results show that μ-controller can suppress the influence of disturbances and control system has robust stability and robust performance. The measurement results demonstrate that the robot system works well and reliable , the measuring principles and method are correct.Keywords：exoskeleton multi-fingers robot;EVA glove;robust control;μ-synthesis- 37
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Published：2020-08-12 -
Simulative and experimental analysis of the valveless piezoelectric pump with Y-shape tubes
Abstract：In order to know more about the characteristics of the valveless piezoelectric pump with Y-shape tubes, and make it meet well with the needs of transporting blood and fluid, simulative and experimental analysis are applied on the pump to explore its pump flow rate and the fluid flowing state in the pump. The commercial finite element software CFX is employed to simulate the fluid flowing state in the pump firstly, and the simulative results reveal that the pressure in the pump chamber varies mildly, and vortex that exists in the pump chamber hardly do harm to the results of transporting living cells and long-chain-marcomolecule cells. Then the valveless piezoelectric pump was made, and by changing the geometrical dimensions of the Y-shape tubes, the variational principle of pressure drop between the outlet and the inlet of the pump is explored. The experimental results show that the pressure drop decreases when the angle between two branches increases, and reaches minimum when the sum of the width of two branches is close to that of the main tube, and when the branch angle is 5°, and the width of the branches is 1.2mm, the pressure drop reaches a maximal value of 74mm.Keywords：Y-shape tube;piezoelectric;Pump;FEM- 64
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Published：2020-08-12 -
RESEARCH ON THE MOVEMENT CHARACTERISTICS OF MICRO-DISPLACEMENT MECHANISM WITH VARIABLE FRICTION BASED ON THE PRINCIPLE OF THE INERTIAL IMPACT
Abstract：Focused on the disability of the micro-displacement mechanism driven by sine wave-a kind of symmetrical wave based on the principle of the converse piezoelectric effect, using sine wave to drive the piezoelectric cantilever bimorphs is proposed. Micro-displacement is realized driven by the inertial impact force. The mathematical model of the mechanism movement is constructed. The mechanism with bevel is designed. Vertical force to the mechanism is produced by the periodical inertial force, which changes the friction by changing vertical pressure. The moving condition QUKeywords：vibration;Impact drive;friction;Micro-displacement mechanism;piezoelectric cantilever bimorphs;Sine wave- 24
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Published：2020-08-12 -
Research on the Micro-cantilever Thermal Infrared Detector with Carbon Nanotubes
Abstract：The thermal deflection theoretical model of a pizeoresistive composite micro-cantilever for thermal Infrared detector is studied. A novel tri-layer Si-based micro-cantilever thermal infrared detector with carbon nanometer tube film is fabricated using standard integrated circuit and micro-mechanical process technology. It is based on the characteristics that the composite micro-cantilever bend in response to incident IR thermal radiation due to the bi-material effect by different thermal expansion coefficient of Al and Si. The bending of micro-cantilever is piezoresistively detected. Furthermore, a new infrared absorbing layer material—carbon nanotubes (CNTs) is coated in order to enhance infrared radiation absorbing characteristic. The input-output characteristic of the piezoresistive micro-cantilever IR thermal detector with carbon nanometer tube film is studied by experiment. The experimental result shows that carbon nanotubes as the absorbing layer of a micro-mechanical cantilever could achieve higher sensitivity. The power resolution is increased twice.Keywords：infrared detector;micro-cantilever;Micro-machining technology;carbon nanotubes- 78
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Published：2020-08-12 -
Analysis of the effect of the retaining ring on the contact pressure distribution and macro-profile of wafer surface in chemical mechanical polishing
Abstract：Abstract：In order to obtain the effects of retaining ring to the contact pressure distributions in the chemical mechanical polishing（CMP）of silicon wafer , based on the practices of CMP with a retaining ring, the mechanism model and boundary conditions on CMP processes are set up. Then the contact pressure distribution are calculated and analyzed by the use of ANSYS, and are investigated by polishing experiments. At last, the contact pressure distributions between silicon wafer and polishing pad and the effects of the retaining ring on it are obtained, .In conclusion, in CMP, the contact pressure distribution is non-uniform and the pressure in the outside borderline of silicon wafer is the maximal, which generate the flatness errors and the subsiding of the outside edge of wafer. When the geometrical sizes and the load ratio of the retaining ring to silicon wafer are chosen properly, the uniformity of the contact pressure distribution can be improved and the available region flatness of wafer surface will become better.Keywords：Chemical Mechanical Polishing（CMP）;Silicon Wafer;Contact Pressure Distribution;Flatness Errors- 25
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Published：2020-08-12 -
Face description and recognition using multi-scale LBP feature
Abstract：In order to promote the accuracy and robustness of face recognition, a face description and recognition method based on multi-scale LBP feature is proposed in this paper. First, the original face image is decomposed into two levels by utilizing wavelet analysis. Then the LBP operator is respectively applied on two approximate images to extract LBP feature maps. The two maps are respectively divided into several regions from which the LBP feature distributions are extracted and concatenated into an enhanced feature vector which is the proposed multi-scale LBP feature. Finally, the multi-scale LBP feature is used as the face descriptor for classification and recognition. Experimental results on ORL face database show that the proposed method can achieve high face recognition rate which is up to 99%. This work demonstrates that the multi-scale LBP feature is highly discriminable with good performance in face feature expression and is robust to face expression and position variations.Keywords：face recognition;multi-scale analysis;LBP operator;histogram- 48
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Published：2020-08-12 -
Image Quality Measure Based on Visual Masking Effect and Singular Value Decomposition
Abstract：Image quality measure is one of the important parts of the video and image engineering. The objective quality assessment methods had experienced three phases. The first phase was characterized as MSE (mean square error) and PSNR (peak signal noise ratio) and so on. Their main theory was based on the by-pixel difference accounting, whose result could be sensible to the difference between two images. But sometime it was too sensible to have well correlation with the subjective one. The second phase was characterized as the PQS[1] and JDM[5] and so on. Their main theory was based on the simulation of the human visual system. But its model always too complicated to realize. Now it was more popular to measure the image quality by detecting the characteristic feature of an image. The singular value could always be the most important information of an image. It had well stability to some extent quality distortion such as noise, scale variety, rotation, clipping and so on. So it was suitable for singular value of an image to be used as the feature parameter. In this paper we combined the visual masking effect and singular value decomposition together and designed a model for objective quality measure of an image. The original and the distorted image were first pre-processed according to visual masking effect and then their image matrixes were transformed into vectors by singular value decomposition. By comparing the angle between singular vectors of them, the quality of an image can be measured. It could improve the sensibility of the traditional SVD method by taking the human visual system properties into account and its result had closer correlation with the subjective one.Keywords：image quality;singular value decomposition;Visual masking;Objective assessment- 28
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Published：2020-08-12 -
SELF-ADAPTIVE NON-UNIFORMITY CORRECTION ALGORITHM FOR IRFPA WITH NONLINEAR RESPONSE
Abstract：Aiming at the non-uniformity slow change with time and environment conditions and the correction error caused by the nonlinearity response of every detector in infrared focal plane arrays (IRFPA) in engineering using, a self-adaptive non-uniformity correction algorithm for IRFPA with nonlinear response is proposed. The algorithm based on nonlinear response of detector and least mean-square error criteria of correction error can self-adaptively eliminate temperature drift of response parameters. The initial values are optimized to achieve the quicker constringency ratio and the higher precision of algorithm. According to the principle of algorithm, the mathematical model is established and experimental results are given out. The results show the superiority of algorithm.Keywords：Nonlinear response;IRFPA;Self-adapting correction;Corresponding parameters;temperature drift- 31
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Published：2020-08-12 -
A Novel Real Time Image Collection System for Point-of-care Test
Abstract：This article designs a real time imaging collection system based on CMOS+FPGA devices embedded with digital processing model, and illustrates the hardware and software design of this imaging system. Experiments show that the produced sample succeeds in displaying 1.3 mega-pixel, up to 15 frames per second (FPS) video in real time on the TFT screen of the system. The system can be utilized for collection and processing in the area of biomedical analysis, and supplies a new hardware platform for POCT devices. Experiments combined with biochemical analysis support that image inspection in biochemical analysis can be done after obtaining high definition colorful image data from this system.- 43
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Published：2020-08-12 -
Changing hardware parameters to improve the measuring accuracy of CCD laser autocollimator
Abstract：A novel CCD laser autocollimator was discussed. In order to improve test accuracy and real-time performance of the measuring system, a method based on hardware parameters study was proposed to meliorate the quality of spot image. The computation of image processing can be simplified and the processing time was saved also the measuring precision was improved especially. Size of small aperture, CCD integral time, focal length of objective, brightness and contrast parameters of image data acquisition card were adjusted respectively to optimize the autocollimator. In the end, experiments of contrasting the accuracy of system before and after optimizing were carried out. The experimental results show that the measuring accuracy has been achieved from 5.0 arc-seconds to 1.0 arc-second in 0.417s.Keywords：CCD laser autocollimator;hardware parameters;image quality;Precision- 39
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Published：2020-08-12 -
3-D Microscopical Image Restoration based on anisotropic markov random field in Wavelet Domain
Abstract：An algorithm based on anisotropic markov random field(MRF) model for 3-Dimensional microscopical image restoration was proposed in this paper. Wavelet is a research hotspot nowadays, it has prominent ability to describe the edges of images. To preserve the edges of restored images, the following three aspects were studied. Firstly, since the wavelet coefficients in different subbands have different orientational characteristics, a priori probability constraint based on anisotropic markov random field was introduced as a priori penalized term in the regularization process. Secondly, the regularization coefficients were adaptively updated according to the restored results during each iteration. So that the regularization parameter decreased step by step while the estimated images became close to the real ones. Thirdly, taking the effects of noise into consideration, an auxiliary step to alleviate it was introduced in the iteration process. Experiments showed that the new algorithm could preserve the detail information effectively. In the meanwhile, it could also reduce the interruption between layers of 3-Dimensional slices and the effects of noise both satisfactorily.Keywords：image restoration;edge preservation;anisotropic markov random field;wavelet transform- 74
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Published：2020-08-12 -
An OCT Image Denoising Method Based on Multi-scale Wiener Filtering
Abstract：In order to realize OCT (Optical Coherence Tomography) image denoising, an image denoising method is proposed and its applied algorithms such as Wiener filtering and contrast enhancement. First, analyzed the OCT image noise, then proposed an multi-scale Wiener filtering algorithm based on character of noise in the image. The method denoises OCT image gradually by different Wiener filter template. Finally, the contrast enhancement based on the character of the different areas is used to strengthen the image information. Experiment results demonstrate that the algorithm enhances OCT image the value of the signal to noise ratio with the background variance (BV) of the processed image was higher 3-7 times than the original image, and the value of DV/BV was higher 3-6 times, It can get the conclusion that the method denoised OCT image with good visual effect, and it is a effective image processing method.Keywords：Optical Coherence Tomography (OCT);Muliti-scale wiener Filtering;Denoising;Contrast Enhancement- 42
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Published：2020-08-12 -
Unscented particle filtering algorithm based on minimal skew sampling
Abstract：Aiming at the degeneracy problem of general particle filter,an improved unscented kalman filter algorithm was proposed.First,a new sampling strategy called minimal skew sampling was proposed. The proposed sampling strategy was used in the UKF algorithm by which a proposal distribution is generated and draws samples from it. By doing this, problems such as particle degeneracy problem which were caused by the general particle filter using transition prior density function as proposal distribution were solved. Secondly, a new resampling method which incorporated multinomial resampling and stratified resampling was proposed , which efficiently solved the degeneracy problem of particle filtering .Finally, a simulation example about a nonlinear time series was given. The theory analysis and simulation results demonstrate that the improved UPF algorithm improves stability and accuracy of filtering, and has a great improvement in operating efficiency.Keywords：Partilce filtering;Unscented transformation;Unscented kalman particle filtering;Sampling strategy- 28
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Published：2020-08-12 -
Hyperspectral Image Compression Algorithm Based on Band Prediction and Rate Pre-Allocation
Abstract：In order to find a solution to transmission and storage problem of huge hyperspectral image data, this paper proposes a hyperspectral image compression algorithm based on prediction between bands to remove spectral redundancy and rate pre-allocation. Since the allocated rate for each predicted band determines the definition of that band, which will be the predicting band of the next band and determines the definition of the next band and its subsequent band as well, it is important to propose an algorithm to allocate the rate of each band reasonably. At first, the standard error of residual image of each band is computed by DPCM, and then the rate for SPIHT coding of each band is allocated by the value of the standard error. At last, each band is linear predicted based on minimal square error, and coded via SPIHT algorithm according to the pre-allocated rate. This algorithm uses the optimal linear prediction, so it can remove the correlation between bands efficiently. Meanwhile, the rate pre-allocation algorithm is reasonable for its taking advantage of both the account of information of each band and the correlation between neighboring bands. Experiments show the average PSNR of this algorithm is 0.9～2.5db higher than 3D-SPIHT algorithm. It is suitable for hyperspectral image lossy compression.Keywords：Hyperspectral image compression;SPIHT algorithm;prediction between bands;rate pre-allocation- 24
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Published：2020-08-12
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