Chinese Version Light学术出版中心
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Issue 6 ， 2006
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Effect of direct current apodization on fiber Bragg gratings
Abstract：The effect of Direct Current (DC) apodization on the Fiber Bragg Gratings (FBG) was investigated with mode-coupling theory and experiment, and the relationship of the DC apodization and the grating chirp was given. Both of the uniform FBG’s and chirped FBG’s (CFBG) group delays were changed after linear DC apodization. A uniform period FBG with a linear dispersion -2 126 ps/nm was fabricated using a uniform phase mask,also the CFBGs with dispersion values of -1 599.362 71 ps/nm,-1 250.4 ps/nm and -2 011.4 ps/nm were fabricated with the same chirped phase mask, respectively,which shows the experimental results agree well with those theories reported in literatures.Keywords：Fiber Bragg Grating(FBG);DC apodization;chirp- 54
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Published：2020-08-12 -
Experimental investigation on a laser-produced plasma source with liquid aerosol spray target
Abstract：Xenon is a promising target material in Extreme Ultraviolet Lithography(EUVL) for its high EUV intensity in 13~14 nm and no condensation on multilayer mirror surfaces due to chemical inert,and therefore a Laser Produced Plasms (LPP) source with liquid aerosol spray target is designed and developed in this paper. The spectral radiation characteristics,laser-to-EUV conversion efficiency at 13.4 nm and debris production by target material erosion or deposition of the liquid Xe aerosol spray target are studied in detail. Experimental results show that the maximum conversion efficiencey of Xe is 0.75%/2π sr/2%bw at 13.4 nm,and pulse-pulse sability is ±4%(1σ) at 0.5 mm laser-nozzle diatance,the results also show that liquid Xe aerosol spray target LPP source can almost eliminate debris after 105 laser shots.Keywords：Xe liquid aerosol spray target;Laser-produced Plasma(LPP) source;Extreme Ultraviolet Lithography(EUVL)- 52
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Published：2020-08-12 -
DSP and FPGA -based multi-channel fiber-optic spectrometer
Abstract：By using eight linear array CCDs as the photo detector,a new type of multi-channel fiber-optic spectrometer was presented to measuring eight channel spectra simultaneously and swiftly. In the system, a FPGA was acted as the controlling unit to generate time sequence and the spectral data were processed by the DSP, it communicated with the PC by its inner USB module. This paper introduces the structure of the whole system and the method of the optical system design,also describes the process of spectral data collecting under the control of the DSP and FPGA. A specific FPGA programming technique is brought forward to settle the capacitance effect inside the IC chip to prevent signal interference between two adjacent channels. The results show that the system has a good long-term stability, a large signal dynamic range and a higher SNR. The spectrometer can be used to measure spectrum or related parameters in various situations.Keywords：fiber-optic spectrometer;multi-channel;real-time spectral measurement- 44
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Published：2020-08-12 -
Equivalent refractive index model on shielding effectiveness analysis of high transparency metallic mesh
Abstract：A novel equivalent refractive index model of high transparency metallic mesh was proposed to calculate its shielding effectiveness accurately. Based on Ulrich’s empirical method, LZ’s equivalent reactance model and Kohin’s equivalent film method, the model accurately established the relation among mesh equivalent refractive index, structural parameters and dielectric boundary refractive indexes so that it is easy to calculate the mesh shielding effectiveness under various incident angles and to prevent the invalidation of Chen’s formulas about oblique incidence on high transparency. To identify the new model’s validity, two kinds of metallic meshes in period of 160 μm, line width of 5.5 μm and period of 320 μm, line width of 4.5 μm were fabricated using UV-lithography, and the shielding effectiveness were measured by microwave network analyzer at 12~18 GHz. Experiment and analysis show that the new model’s theoretical calculation error is less than 2 dB, more accurately than 4 dB of Ulrich’s model and 8 dB of Chen’s and LZ’s models.Keywords：electromagnetic shielding;equivalent refractive index model;high transparency;metallic mesh- 58
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Published：2020-08-12 -
Optical system design of multi-finger fingerprint scanner
Abstract：Multi-finger fingerprint scanner is a high-resolution fingerprint capture device with big Field of View(FOV), it represents the developing trend of the biometric identification area.For the key technology of this device, the optical system design, this paper presents three types of optical design methods, they are separate lens, two group telecentric system and one singlelet with separate lens system, the advantages and disadvantages of each design are discussed and compared, it is found that the MTF of singlelet with separate lens system is larger than 0.6 in 150 lp/mm,also prototype of this design obtains a image in good quality.Keywords：multi-finger fingerprint scanner;optical system design;biometric identification- 70
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Published：2020-08-12 -
System design of spatial heterodyne spectrometer
Abstract：This paper analyses and studies the parameter design of a Spatial Heterodyne Spectrometer(SHS). The basic concept and structure of SHS is described and the dependence of resolution limit, power of resolution and spectral range on some critical parameters of optical components including grating parameters, pixels of detector, image lens and so on is introduced. By taking an integrated system design for example, the simulated result is presented. SHS system built and tested in the laboratory,the basic concepts and performance characteristics of the technique have been verified. Experimental results show that the achieved resolving power of the SHS system is 17 700 at 591 nm, and the spectral range is 574~591 nm. These results are coincident with the theoretical results well.Keywords：Spatial Heterodyne Spectrometer(SHS);system design;parameter design;Fourier-transform spectroscopy- 60
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Published：2020-08-12 -
Analysis on dispersion characteristics of group-phase-controllable optical delay line
Abstract：The dispersion characteristics of optical coherence tomography (OCT) system were particularly analyzed. It is found that the dispersion is proportion to the defocus distance of a galvanometer, with negative in the focus length, dispersion, and with possive dispersion out the focus length. A OCT with spatial resolution of 8 μm is designed. The dispersion of 77 fs2 is measured in this OCT system when the galvanometer is 0.5 mm far away from the focal length of Fourier lens. The relation between dispersion and the distance away from focus is experimentally validated, and the experimental results are agreed with theory well.Keywords：Optical Coherence Tomography(OCT);dispersion;coherence;optical delay line- 49
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Published：2020-08-12 -
Testing system for performance of EUV solar telescope
Abstract：In order to simulate the outer space's vacuum conditions, and to test the performance of a Extreme-Ultraviolet (EUV) solar telescope,a collimator system working in wavelength of 17~30 nm is presented, which consists of a laser produced plasma source, a Newton type collimator, a back illuminating CCD camera and a high vacuum system. The method and result of the physical design, optical system and vacuum system are described in detail. The test result shows the vacuum grade of the system is 5×10-4 Pa after 80 min, and it can meet the test demands of the EUV solar telescope .Keywords：EUV solar telescope;performance test;system design- 42
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Published：2020-08-12 -
Tradeoff optimization design of optical configuration on imaging spectrometer
Abstract：Using the tradeoff optimization of the application requirement and the available technology, an optimized optical system was introduced to design a new type of imaging spectrometer consisting of a three -mirror-off-axis anastigmat (TMA), a dispersive prism and an asphere mirror collimating and imaging system. This kind of imaging spectrometer works over the spectral region of 0.4~2.5 μm and the focal length is 800 mm, FN=4.5, FOV=1.43°,the MTF can reach 0.44~0.62, spectrum resolution is about 3~23 nm, and the total mass is about 70 kg. While the FN must be within 3 and the total mass will reach 100 kg if uses the type of imaging spectrometer of grating or interference Fourier transform spectrometer at the condition of the same properties of focal plane elements and SNR. It is showed that the system has an optimum configuration in high resolutions of ground and spectrum,short integral time and low accepted radiant energy, it can be used in selecting the optical configuration especially.Keywords：satellite remote sensing;tradeoff optimization;telescope;imaging spectrometer- 50
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Published：2020-08-12 -
Measuring methods of ultraprecision involute tooth profile
Abstract：A double-disc mode instrument for measuring involute tooth profile is analyzed, which has some advantages, such as simple structure, no Abbe error caused by the stylus, etc. The instrument adopts an intersect coach spring structure as the error transfer lever, which has high sensitivity and no gap. After compensating major measurement error sources, the double-disc mode instrument's uncertainty of measurement (U95) is less than ±0.5 μm, which can meet measurement specification of the involute tooth profile of level 1 gear. Comparing with CNC instruments for measuring gear tooth profile, the double-disc instrument's automation and multifunction performance are insufficient, but it has advantages in accuracy of measurement and manufacturing economical efficiency, etc. The result shows that the double-disc mode is an ideal method for measuring ultraprecision involute tooth profile.Keywords：precision gear;involute tooth profile;measuring principle;double-disc mode instrument- 38
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Published：2020-08-12 -
Determination of groove density for bending gratings
Abstract：Primary researches on the groove density variations of bending grating were experimented. Firstly, highly varied line-spacing gratings (nearly 9.2 line/mm) were fabricated. Meanwhile thin glasses with the thickness 0.16 mm were chosen as their substrates. Consequently, the long trace profiler was used to test the curved substrates precisely and the groove density of the gratings were measured by diffractive method. Experimental result shows that the error is 0.41 line/mm rms between experimental and theoretical values.Keywords：bending grating;groove density;optical metrology- 41
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Published：2020-08-12 -
Micro-spectrophotometer based on MEMS technology
Abstract：A new mini-spectrophotometer was developed by adopting micro-silicon-slit and micro-silicon- fixer, which are based on MEMS technology. Both the micro-silicon-slit and the micro-silicon-fixer have such feature as small volume, high precision, which are laid out and analyzed later. Meantime, by analysis of the sample cell’s optical characteristics which have some impact on the linearity of the spectrophotometer, a relation equation is put forward which is about the impact of the refractive index of the sample cell and the tested medium on the variety of the transmitted light intensity and the absorbency. When the water and the air are taken as referenced medium, the experiments demonstrate that the effect of different refractive of references doesn't influence the correlation coefficient r and the slope of the Absorbency-Concentration curve. The final results show that the new mini-spectrophotometer with micro-silicon-slit and micro-silicon- fixer is worked out, its correlation coefficient r>0.999 and it's refractive index resolving power is better than 0.01.Keywords：micro-silicon-fixer;micro-silicon-slit;micro-spectrophotometer;mini-fiber-spectrometer;MOEMS- 39
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Published：2020-08-12 -
Micro electrodes on-line measurement in micro EDM
Abstract：An on-line measurement system was proposed. It is composed of a halogen type light source, a zoom lens, a CCD camera and a bracket that has 6-degree of freedom. It has a resolution of 1.61 μm and a magnification of 113~729. Based on the Linux operating system, an image capturing program was developed with the V4L2 API, in which the image data was acquired with the method of mmap() memory map. The conversion between the data structure of IplImage and the class of QImage was implemented. Therefore the image could be processed by using OpenCV, as well as showed with Qt. The contour of micro electrodes can be extracted by means of the Canny edge detector. Furthermore, the G code for on-line measurement was also developed. The experiment of block electrodes Electrical Discharge Machining (EDM) grinding was carried out. It shows that the relative error between the on-line measurement system (OMS) and the scanning electron microscope (SEM) is less than 5%. It also shows that the system can be used to deal with the difficulties in micro electrodes on-line fabrication and measurement in micro EMD.Keywords：micro EDM;electrode;on-line measurement- 57
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Published：2020-08-12 -
Effect on material removal of magnetorheological jet polishing by several parameters
Abstract：The effects on material removal of MJP(Magnetorheological Jet Polishing) by several parameters were given.Firstly, the mechanism and experiment set-up of MJP were introduced. Then the material removal of MJP was investigated in the experiment. A series of spot polishing experiments were conducted using the standard magnetorheological fluid. The effects of impact angle, stand-off distance, jet velocity and magnetic intensity on polishing were mainly studied. And the relation curve between each parameter and the amount of removal was obtained. The mechanism of material removal was analyzed by computational fluid dynamics. The experiment results lay a foundation for further research of best parameter matching for MJP, and for the implementation of numerical control of MJP.Keywords：Magnetorheological Jet Polishing;jet stabilization;Polishing spot;removal mechanism- 34
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Published：2020-08-12 -
Effects of inertia parameters of moving platform on the dynamic characteristic of flexible parallel mechanism and optimal design
Abstract：The effects of the inertia parameters of moving platform on the dynamic response, dynamic stress and natural frequency of flexible parallel mechanisms were studied. The mechanism total mass function is combined with elastic deformation energy function by using linear weighted method to derive the multiple objective function, and the boundary condition of inertia parameters, motion errors, natural frequency, dynamic stresses and driving moments are considered as constraint equations to perform the optimal design. The optimal inertia parameters of moving platform are determined based on the optimal design. The effects of the inertia parameters are well illustrated through the numerical simulation of a planar 3- R RR parallel mechanism. The inertia parameters of moving platform are demonstrated to have significant impact on the dynamic response, dynamic stress and natural frequency of flexible parallel mechanisms, and they should be important parameters for the analysis and design of the flexible parallel mechanisms.Keywords：moving platform;inertia parameter;dynamic response;natural frequency;dynamic stress;optimal design- 45
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Published：2020-08-12 -
Design and analysis of a novel 3-DOF nanopositioning stage
Abstract：A novel three-degree-of-freedom (3-DOF) nanopositioning stage was developed. The stage utilizes three piezoelectric actuators (PZTs) arranged in an equilateral triangle shape and ring plate hinges to realize nanopositioning for assuring smoothness of movement, negligible friction, negligible backlash and high precision. The simplified modeling of the nanopositioning stage was discussed. The translational stiffness along z direction and rotational stiffness along x and y direction, and three natural frequencies of the nanopositioning stage are deduced in terms of the theory of structural mechanics. Theoretical analysis and finite element analysis on static and dynamic behavior of the nanopositioning stage are performed. The comparative results of the theoretical analysis, finite element analysis (FEA) and experiments show the accuracy of theory model and the validity of FEA. FEA also indicates that the stiffness, the natural frequency and the driving force will increase with decreasing hinge radius and increasing hinge thickness despite the maximum stress increasing of the stage. By modificating the dimensions of a ring plane hinge it can control and optimize natural frequency, displacement, stresses, and driving force to achieve the desired response of the nanopositioning system. Finally,this paper gives a simple procedure to select the proper dimensions of a nanopositioning stage.Keywords：ring plate hinge;Nanopositioning;FEA;stiffness;natural frequency- 41
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Published：2020-08-12 -
Research on novel parallel robot coordinate measuring machine simulation modeling
Abstract：In order to verify design scheme and theoretical model of a novel 5-Degrees of Freedom(DOF) parallel robot coordinate measuring machine(PRCMM), shorten the period of the PRCMM development, decrease the development costs, and enhance the ratio of its successful design, the virtual prototype technology was applied to the course of the PRCMM design and development. The virtual prototype of this PRCMM is established by mechanical design software－SolidWorks. Motion simulation and measure simulation are realized by applying OLE technology, and dynamics simulation are realized by mechanical simulation software-ADAMS. Moreover, the resolvents of key problems generated in the process of development are discussed in detail. The results of computer simulation prove that the theoretical model is correct. Furthermore, the design structure is reasonable and credible. These provide not only the theoretic foundation and main parameters for the machine design and NC design, but also an effective method for the engineering design of PRCMM on computer.Keywords：parallel robot;coordinate measuring machine;virtual prototype;simulation modeling- 41
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Published：2020-08-12 -
Inverse control algorithm to compensate the hysteresis and creep effect of piezoceramic
Abstract：The high-precision positioning with scanners in Scanning Probe Microscopes applications, particularly in atomic force microscopes (AFM), was studied. The piezoceramic actuators are usually used in this kind of scanner, which obviously exhibits the hysteresis and creep between the input voltages and the output displacements during the uncompensated open-loop operation. The hysteresis and creep reduce the positioning precision and produce a distortion in scanning images. A novel hysteresis and creep model was proposed, and the method that can on-line identify parameters was also provided. Furthermore, the model-based inverse control algorithm was used to compensate the hysteresis and creep effect of piezoceramic during AFM scanning. In the analysis, the Preisach hysteresis model and logarithmic creep model were used to characterize the nonlinear behavior of the piezoceramic actuator. This method is easy-to-use because it does not need set parameters in control procedure. Moreover, it has high resolution as it is an open-loop control scheme. Closed-loop operation can offer better hysteresis and creep compensation, but it can reduce image resolution for small scans/sample features due to limited dynamic range of sensors at higher bandwidth. Simulation results of tracking triangular wave trajectories show tracking error is on the magnitude of the sensor noise level, which demonstrate the validity of the method.Keywords：Atomic Force Microscope(AFM);piezoceramic;hysteresis;creep- 25
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Published：2020-08-12 -
Effect of equidistant surface errors on parabolic shape accuracy
Abstract：In machining a parabolic shape workpiece, equidistant surface errors will be produced on the machined workpiece surface. This paper analyses and calculates this error. The minimal distance of theoretical curve is gained by the three-point method, and the mathematical model of all points of the lapping tool’s surface is established by the two-point method, which can be applied in calculating equidistance-curve error of all the conic of lapping tool. The simulation results indicate that equidistance-curve error of lapping tool changes from 0 to 0.7 μm, which can satisfy surface precision requirement of the most components. The maximal error of beginnings and ends of lapping tool is 0.624 14 μm, and the equidistant surface error increases with tool wearing and abrasives tool wearing and curvature of parabolid increasing. The results show the validity of this method.Keywords：equidistant surface errors;paraboloid;shape accuracy- 46
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Published：2020-08-12 -
Circuit noise effects on star sensor position accuracy
Abstract：A method to measure image noise caused by circuit module was introduced. Firstly, many background star maps were taken at laboratory and calculated statistically, and max gray difference of the same pixel was taken for image noise caused by circuit module. The statistical data show that circuit module noise was accorded with normal probability density distribution. Secondly, based on the energy distribution model of ideal star point, a gray matrix of an ideal star of visual magnitude ~ 6 was calculated. Then star point with circuit image noise was produced with adding random noise matrix of normal distribution to ideal star point. Finally, based on subpixel centroid arithmetic and simulation data, star position error was calculated. The results show that circuit module can bring image noise of normal distribution; For 6 Mv stars at laboratory, this noise can achieve the accuracy level of 1/200 pixel. Compared with the accuracy level 1/25 pixel of actual star position measurement, circuit noise can not be neglected.Keywords：star sensor;Accuracy;circuit noise;DC/DCconverter- 34
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Published：2020-08-12 -
A adaptive digital watermarking algorithm combining spatial and DWT domain
Abstract：A novel effective adaptive digital watermarking algorithm was proposed without using the traditional method of combining spatial and DWT domain based on the features of human visual system (HVS). The loaded image was divided into several blocks and calculated their variances. A pseudo random sequence was produced after comparing these variances with the variance of the whole loaded image. Then a spread spectrum watermark sequence was created after combining original watermark and pseudo random sequence, and the robustness was accordingly enhanced by utilizing the spread spectrum codes. The loaded image was decomposed by DWT (Discrete Wavelet Transform) into 2-level sub-band images. The watermark sequence was embedded into the high-frequency coefficients of the loaded image. An innovative quantization method was proposed. To improve the security of the watermark system, the cryptography technology was used in the embedding procedure. A long periodic pseudo random m-sequence was created to choose the location of watermark to be embedded in. Each bit watermark that used to embed in load image needs to mark choice every time. The traditional quantization methods usually use the constant quantized interval and the scheme proposed in this paper is called odd-even adjudegment rule. The scheme could adaptively adjust the quantized interval by calculating the adjacert symbols' mean value of the wavelet coefficients which is selected to embed the watermark. The top-left, top and left coefficients were selected as the adjacent symbols of embedded wavelet coefficient's neighboring symbols. The fidelity of the watermarked image and the invisibility of the watermark have been enhanced by this method. The main idea of odd-even adjudgement rule is to quantize the coefficients into the most adjacent odd quantization mark or even quantization mark according to the watermark's value. The blind extraction could be realized by using this rule. Experimental results show that the watermark proposed in this paper is invisible (the PSNR is higher than 41) and is robust in the case of against some normal attacks such as JPEG compression, additive noise and filtering, etc. (the similarity between the original watermark and extracted watermark is almost above 0.85).Keywords：digital water marking;spread spectrum waterwark;neighboring symbols’ mean value;odd-even adjudgement rule- 49
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Published：2020-08-12 -
A wavelet-based focus measure and 3-D autofocusing for microscope images
Abstract：A new wavelet-based focus measure was proposed. High NA (Numerical Aperture) and low NA microscope image sequences were used to compare the performance of this focus measure with the classic and popular focus measures Normalized Variance, Entropy, Energy Laplace and other two Wavelet-based High Frequency focus measures. The robustness of these focus measures was also compared using image sequence corrupted by Gaussian white noise with that of standard deviations 25. Experimental results show that the proposed focus measure can provide significantly better depth resolution and accuracy than the comparing ones, and exhibit comparatively good robustness with Normalized Variance. A selective focusing technique for autofocusing on the three dimension microscale objects in different depth was developed. The results also show that this focus measure and selective autofocusing techniques can be widely applied to automated micromanipulation; and that autofocusing is of fundamental importance to automated micromanipulation, and focus measures are the key techniques.Keywords：autofocusing;focus measure;wavelet transform;3-D autofocusing- 45
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Published：2020-08-12 -
Effects of Y loop element FSS structure parameter on frequency response
Abstract：Effects of the parameteristics of Y loop element on the frequency response characteristics of frequency selective surface (FSS) were studied by spectral domain method, especially in the thickness and permittivity of the loading dielectric. With filming technology and lithography, the corresponding FSS was produced. And the tests of it in the microwave darkroom were given. The agreement between the calculated and measured is good. The results show that, the arm length mainly influences the center frequency, which increases from 3.8 mm to 4.7 mm, the center frequency decreases from 11.9 GHz to 8.9 GHz. The space between the elements mainly influences the bandwidth, which increases from 0.3 wavelength to 0.5 wavelength, the bandwidth decreases from 3.2 GHz to 1.0 GHz. The arm width and the slot width influence the center frequency as well as the bandwidth. The center frequency of FSS decreases along with the dielectric loading, but it does not decrease at all times. The center frequency is influenced by the dielectric thickness and dielectric permittivity, but the latter does much more. The dielectric loading can also influence the transmission power at the center frequency, the appropriate dielectric thickness and dielectric permittivity can stabilize the FSS transmission characteristics as the angle of incidence and the polarization are varied, and it can improve the transmission characteristics of FSS.Keywords：frequency selective surface;center frequency;bandwidth- 33
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Published：2020-08-12 -
Research on location compute method of object
Abstract：The location compute equipment of object is an effective means to acquire object's location quickly and accurately, target distance parameter is offered by laser range finder, and geodetic position of observation point is obtained by GPS, azimuth and pitch angle are offered by azimuth compass. In the process of location compute of object, local coordinate system of object is established, and according geocentric coordinate system is established in terms of earth's ellipsoidal model. Conversion matrix between object's local coordinate system and geocentric coordinate system is solved to compute geodetic coordinate parameters which object in air or on earth to geocentric coordinate system. By testing the fixed targets on earth with known coordinate value in WGS-84 coordinate system, within the range of 30 kilometre, the required location accuracy of less than 1% is achieved.Keywords：location compute;GPS;geocentric coordinate system- 68
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Published：2020-08-12 -
Performance analysis of an optical coherence tomography system with special coating beam splitter
Abstract：OCT Monte-Carlo simulation model based on confocal mode is used to study the reflectivity of back-scattering light from high scattering tissue in OCT system, the simulation result shows that the intensity of useful back-scattering light for OCT imaging is about 10-8~10-10 of incidence light. The weak but useful signal limits the OCT imaging speed, detection sensitivity, signal-to-noise ratio and image contrast. Therefore, a new special coating beam splitter was devised. As a result, firstly by enhancing the output power of lamp-house to a large possible degree while being assure that tissues are not scathed, the new coating beam splitter causes the intensity of referential light to be reduced by four orders, and the output power of electrophotonic detector can not easily reach saturation. Secondly, the intensity gap between referential and signal beam is largely reduced, and image intervening contrast is increased by two orders. In spite of imaging at high speed, OCT system yet has qualified images. Thirdly, specially designed system renders sample arm with most intensive light and lessens the loss of back-scattering light to the least degree, therefore, signal-to-noise ratio improves by 6 dB and detection sensitivity of the system increases to 43 dB by actual sample test.Keywords：special coating beam splitter;signal-to-noise ratio;detection sensitivity;image contrast- 85
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Published：2020-08-12 -
Denoising and baseline correction of spectrum by wavelet transform
Abstract：A denoising and baseline correction method based on wavelet transform and their parameters choosing method were developed to remove noise and correct baseline in the spectrum effectively. Baseline wander was removed by setting approximation coefficients to zero, and noise was removed by the method of threshold detail coefficients of higher-frequency period in wavelet filed, and with simulated signals of pure spectrum and familiar baseline and noise, the parameters such as wavelet basis, decomposed level, threshold selection rule and so on were chosen by the evaluation coefficient η which considered approaches of integral signal and every characteristic peak simultaneously. The simulated experiment shows that it is more suitable that the simulated signal is decomposed at level 5 on the wavelet basis of sym5、db5、db9 and so on, and then the approximation coefficients are set to zero and threshold detail coefficients by hard threshold with single layer Heursure threshold selection rule. Further experiment shows that this method provides a novel and to correct effective way to remove noise and to correct baseline in the real spectrum.Keywords：infrared spectrum;denoising;baseline correction;period of time;period of frequency- 47
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Published：2020-08-12 -
Principle component representations for machine noise monitoring
Abstract：The extraction and application of principle component representations were studied for machine noise monitoring. On the base of the time- and frequency-domain statistical features extracted from the machine noise signal, the principle component representations of machine noise pattern were explored, the ability of principle component representations to represent the characteristic of machine condition by introducing the idea of correlation was analyzed, and the machine noise monitoring scheme using the effective low-dimensional principle component representations was proposed. Through previously designing four wearing faults on the connecting rod bearing of EQ6100 model gasoline engine, experimental analysis shows that the low-dimensional principle component representations of engine noise can be conveniently and effectively used for representing the machine conditions. Finally, the excellent result with the accuracy of 100% was obtained by monitoring the conditions of the testing samples, which demonstrates the availability of principle component representations for machine noise monitoring.Keywords：machine noise;condition monitoring;principle component analysis;connecting rod bearing;wearing- 39
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Published：2020-08-12 -
Mosaic of medical ultrasound image based on adaptive simulated annealing and multiresolution searching
Abstract：In order to improve the performance of image mosaic, an automated image mosaic approach was proposed based on adaptive simulated annealing and multiresolution strategy. In the first step of the algorithm, the registration region is adaptively chosen. Then,the parameters of image translation and rotation are optimized based on mutual information with a hybrid method of adaptive simulated annealing for global searching and a multiresolution approach as a local search strategy, and the process of image mosaic is finally achieved. With conducting 24 times of simulated mosaic experiments on both noisy digital images and medical ultrasound images, this algorithm is proved to be a precise, fast and robust mosaic approach compared with the traditional multiresolution direct-search method. Since this improved algorithm inherits the features of high precision from simulated annealing and high efficiency from the multiresolution method, the mosaic performance is improved by 12.5% in terms of success rate while maintaining acceptable speed.- 68
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Published：2020-08-12
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