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Issue 1 ， 2010
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The Use of OLCR Technology for Fiber Bragg grating sensing of distributed non-uniform strains
Abstract：The reflectivity spectrum of a fiber Bragg grating (FBG) is out of shape under non-uniform strain loading, so the strain can not be deduced from the shift of Bragg wavelength. The optical low coherence reflectometry (OLCR) technology is supposed to be a reliable method for measuring the non-uniform strain of FBGs. Based on a Michelson interferometer, OLCR system is set to interrogate the time domain pulse response of FBG structure, from which the frequency domain reflection response of FBG is converted by Fourier transform. Then the spatial response of FBG, relevant to Bragg wavelength is reconstructed from lay peeling technology. Thus, the non-uniform strain distribution is calculated from the sensing model of FBG. With an effective OLCR system, the OLCR technology is illustrated in detail. An experiment of composite delamination in modeⅠis conducted, and the non-uniform strain distribution is botained with reliability. The OLCR system demostrates an excellent performance in demodulating the FBG non-uniform strain sensing, having a promising application prospect.Keywords：OLCR;FBG;non-uniform strain;delamination- 50
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Published：2020-08-12 -
Design and characterization of harmonic diffractive microlens arrays with continuous relief for maskless lithography
Abstract：A new maskless lithography method based on harmonic diffractive microlens arrays with continuous relief is proposed. The method takes the harmonic diffractive microlens arrays with continuous relief as maskless lithography objective array to integrate the defocus-detecting array into the writing array by taking both the writing resolution and diffraction efficiency into consideration, and design the array with deep relief to make the fabrication of arrays easy. To verify its validity, continuous-relief harmonic diffractive microlens arrays with F/7.5 and a design wavelength of 441.6nm are designed, fabricated and characterized for maskless lithography. Experimental results indicate that the array developed can be used to synchronously focus the writing laser and the autofocusing laser into the same spots, and can achieve diffraction efficiency of over 70% for both writing wavelength and defocus-detecting wavelength.- 52
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Published：2020-08-12 -
Thermal wave detection and defect depth measurement based on Lock in thermography-1
Abstract：Lock-in Thermography is an active infrared thermography technology which is based on thermal wave processing. It is especially used for the nondestructive evaluation of subsurface defects of composite materials and compound structure component, and has been widely applied on aerospace, aircraft structure, machine, and electronics fields. The principle of Lock in thermography for non destructive test and evaluation and defect depth measurement are deeply researched, and the honeycomb structure materials and welding bearing are detected by Lock in thermography for NDT. The finite difference method is used to compute the temperature history on the surface of sample under the law of sine modulated heat flux, and the Lock in method is applied to obtain the amplitude and phase differences between defect region and non defect one, the result is similar to the experiment. The thermal-electronic equivalence modeling is developed between the fundamental laws of heat and electricity, the simulation of Lock in thermography is researched used in this modeling, the relation between phase difference of both incident and reflected thermal waves and defect depth is reached, and the computation results is close to the experiment. The Lock in thermography is applied on the modeling defect of honeycomb structure sample and welding bearing for non destructive test and evaluation. The defect size and position can be soon and exactly detected by Lock in thermography, and it has more advantages for curve surface of structure.Keywords：Lock in thermography;Thermal wave detection;Finite difference method;Thermal-electronic equivalence modeling- 53
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Published：2020-08-12 -
Numerical simulation and analysis for SX-700 monochromator grating sine mechanism
Abstract：SX-700 monochromator is the key part of the Shanghai Synchrotron Radiation Facility soft X-ray spectromicroscopy beam-line，whose important subassembly is the grating sine mechanism. Difficulty is that the angle repeatability of the grating sine mechanism must be less than 0.43”. To prove the design of the grating sine mechanism could meet the requirement, the error sources that affect the precision of the wavelength scan are construed; and the numerical simulation for the sin-bar and drive rod of the sine mechanism are done by using the finite element software ANSYS。The error analysis for the rotation-angle-accuracy of the grating sine mechanism is done according to the results of the numerical simulation, and the rotation-angle-accuracy is 0.28”. The angle repeatability of the grating sine mechanism is measured with an autocollimator system designed by us, and the angle repeatability is 0.15”. The result reveals that the structural design of the grating sine mechanism fulfills the design requirement of the angle repeatability.Keywords：monochromator;sine mechanism;numerical simulation- 38
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Published：2020-08-12 -
Effects of optical element errors on birefringent filter
Abstract：Objective: For solar magnetic field telescope with birefringent filter, the quality of filter directly affects the transmission band, and then the measurement of solar magnetic field. The transmission band will shift and its outline will change when the incident ray is oblique or the optical elements are not ideal. The quality of filter can be improved by reducing the errors effectively after analyzing the effects of error terms on the birefringent filter. Method: Based on the ray tracing method, the trace of the ray can be simulated completely by using computer program. Ultimately the variation of transmission band with different errors can be obtained accurately. Result: The primary error terms were given which cause the band shift, the band broadening, and the changes of maximum and minimum. This paper provides a reference on the development of birefringent filter.Keywords：solar observation;error effect;ray tracing method;briefringent filter- 51
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Published：2020-08-12 -
Measurement of super-smooth surface by grazing X-ray scattering method
Abstract：The paper introduces the principle of measurement of super-smooth surface by grazing X-ray scattering method and the experimental facility based on an improved X-ray diffraction. The scattering diagrams measured on ZERODUR, Sapphire and three wafers with different roughness are treated by first-order vector perturbation theory. The results indicate that the calculated PSD all are in a good agreement with the results obtained from Atomic force microscope (AFM). We also analyze the effects of the slit width of detector and the divergence of incidence X-ray. With other idea experimental conditions, when slit width of 0.02mm and 43" incidence divergence, errors are both lower than 2% while the range of spatial frequency is higher than 0.03μm-1. We could conclude that the error decrease quickly as reducing the slit width and incidence divergence. The PSD error also decreases quickly as increasing the spatial frequency.Keywords：grazing-incidence X-ray scattering;perturbation theory;PSD;AFM;systematic error- 29
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Published：2020-08-12 -
Aspheric Surface Measurement by Infrared Interferometer
Abstract：The principle and the method of aspheric surface measurement by infrared interferometer is introduced. The axial deviation between aspheric surface and standard fit spherical surface is calculated, and the relationship between this deviation and the wavefront aberration is deduced. The aspheric surfaces with large asphericity can be measured by the use of infrared interferometer with the advantage of long working wavelength (λ=10.6μm). The wavefront aberrations of the tested aspheric surface and the standard fit spherical surface are measured, then the measured wavefront aberration and the calculated wavefront aberration are compared, and the surface quality of aspheric surface is obtained. The result shows the surface deviation is 1.20μm(PV). The method has advanges of easy operation, low cost, and good generality.Keywords：optical measurement;aspheric surface;infrared interferometer;wavefront aberration- 43
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Published：2020-08-12 -
A novel relative radius of curvature metrology for spherical segmented mirrors
Abstract：The biggest challenge in fabricating the segmented mirror is match each segment, that is match the radius of each segment, so they can equal to a single, continuous surface. For spherical segmented mirror, the radius of each segment must be the same. We put forward a new method which utilizes Shack-Hartmann sensor and a high precision spherometer to measure the relative radius of each spherical segment; also, we setup an experiment system. The method first use the co-focus technique to co-focus each segment; then use the S-H sensor to measure the defocus in the optical axis direction and employ the PZT actuator behind the segments to make the defocus near zero; after another co-focus process, the relative radius of each segments can be measured by high precision spherometer. In the experiment, the segmented mirror consists of three spherical hexagonal segments which are 300mm side by side, and the designed radius of curvature is 2000mm. The analysis and experiment show that the precision of the method is about , and the method is suitable for the measurement of relative radius of curvature of large spherical segmented mirrors.Keywords：segmented mirror;relative radius of curvature;Shack-Hartmann sensor;Spherometer- 61
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Published：2020-08-12 -
A fluoride sensitive optical probe based on Sol-gel matrix modified microstructured optical fibre
Abstract：In this article, we fabricated an optical fluoride probe based on microstructured polymer optical fibers (MPOFs) which is modified with morin-Al complex doped silica gel film. The structure of this probe is based on microstructured polymer optical fiber. There are microholes in the optical fiber. These microholes could be used as the substrate of sensing materials and minor reaction pool. The deposition of sensing layer was realized by sol-gel process. When the sol doped with morin-Al was inhaled into the optical fiber, sensing layer formed on the inner wall. Trace liquid could be hold in the MPOF, and the process of sensing are carried out in the microholes of MPOF. The sensing process was based on fluorescence process. Fluoride quenched the fluorescence of morin-Al in gel matrix when it reacted with it. Then the sensing probe showed different fluorescence intensity to different fluoride ion concentrations in the aqueous solution. The range of response was 5-50 mmol/L, under the condition of pH=4.6.- 61
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Published：2020-08-12 -
Design and tolerance analysis of Offner compensator for high order aspheric surface null testing
Abstract：90nm nodal point lithography projecting lens requires high surface accuracy. This literature presents a kind of the Offner compensator using three pieces of the lenses. Equal quantity of the spherical error was introduced to compensate all orders of aspheric coefficient. Certain quantity axial spherical aberration was introduced to compensate the normal direction deviation of aspheric surface. The results indicate that: primary and high order aberrations were balanced well enough. The design wavelength is 632.8nm. MTF exceeds diffraction limit, mean square wave front error <λ/1250,The F-number can achieve F/1.64. At last, a loosen distribution of the tolerance was presented based on the accuracy of measuring apparatus.Keywords：aspheric surface null testing;Offner compensator;tolerance analysis- 52
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Published：2020-08-12 -
Vacuum-ultraviolet Blazed Silicon Grating Anisotropically Etched in KOH Solution
Abstract：Abstract: Combined with the technigue of holographic interference and the ashing of photoresist, a straight and clean mask of phtoresist with small line-to-period can be fabricated on off-cut silicon (111) wafers. We present a simple and convenient method of controlling the profile of a blazed grating that consists of using patterned native oxide layer as the mask of anisotropic etching to obtain near-ideal grooves of sawtooth. With the blazed grating profile well controlled by this technique, a 1200 g/mm blazed grating was fabricated, which had a blaze angle of 5.0° and smooth blaze facets of about 0.2 nm rms. The grating was measured to blaze at the wavelength of 135 nm. It is believed that high-groove-efficiency blazed gratings used in the wavelengths of extreme ultraviolet and soft x-ray can be easily fabricated by this method at normal or near normal incidence.Keywords：blazed grating;anisotropically etching;vacuum ultraviolet- 62
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Published：2020-08-12 -
Research on roll stable control and rudder technology targets of Axisymmetric aircraft
Abstract：Combined with strapdown inertial navigation technology, the effect of rudder technical targets on roll autopilot performance was studied systematically. According to the roll-loop characteristics, the basic relationship between the roll-loop cut-off frequency and bandwidth of rudder was analyzed; Applying the method of frequency domain analysis, on the base of comparing simplified low-order model with the high-order model, the effect of rudder bandwidth and phase angle on the roll-loop performance was Studied. In the form of second-order system step response,, the maximum angular velocity of the rudder was determined contacted with the downwash torque and the rolling steady-state torque command, the roll autopilot working on the area of linearity under the condition of maneuvering flight was ensured; furthermore, Considering the restrictions on angular velocity and angle of the second-order system rudder model and the maximum disturbing torque under different total angle of attack, the roll-loop commands and the response state of roll in Saturated non-linear zone was examined ,the stability of roll-loop was proved. The results showed that, for the missile time constant was , rudder surface moment efficiency was , the bandwidth of the roll autopilot needed to be more than , the bandwidth of rudder should be no less than , damping ratio of 0.6 or more. A basic method to determine the rudder technical targets when designing the roll autopilot was provided.Keywords：roll autopilot;rudder;stability;saturated non-linear- 76
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Published：2020-08-12 -
Design and analysis of laser scanning optical system for computed radiography
Abstract：To meet the requirements of a Computed Radiography (CR) and to implement its functions, a new high-performance laser scanning optical system was designed. In view of difference in performances of scanning methods, a scanning arm is designed which is composed by pentagonal prism and scanning object lens. Scanning arm is used to replace the Fθ lens. To cooperate with scanning arm, a circular imaging plate transport mechanism is designed. Scanning arm can receive stimulation luminescence as a receiving device too. The system designed by this method has simple structure and good performance. In order to testify the effect of spot size on resolution, an experiment has been performed. Many factors that have effect on the spot size are analyzed in this system. Regarding the influence factors of system, dynamic performance of scanning arm is simulated by using the finite element method in high speed rotating, the influence of incident light out of vertical to incident flat of pentagonal prism and pentagonal prism’s displacement errors to the spot size are calculated. The calculation reveals that the system easily adaptive to the error and can be used widely. Experiments were carried out to verity the performance of laser scanner, the results indicate that the images have good visual effect and can meet requirements of industrial inspection.Keywords：laser scanning optical system;finite element analysis;pentagonal prism;scanning arm- 31
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Published：2020-08-12 -
Research on rehabilitation hand exoskeleton system for injured fingers
Abstract：Based on the biological characteristic analysis of human hand, a novel exoskeleton mechanical hand is presented for the rehabilitation of injured fingers after operation. The exoskeleton hand which is developed based on modular design technology could be regulated for adapting to hands with different sizes and drive fingers do flexion and Abduction/adduction motion independently. The device can real-time feedback information of the finger joints during the rehabilitation. It can also provide for a force that is applied perpendicular to the bone of the finger under therapy. This, in turn, causes minimum tissue irritation of the soft tissue surrounding the bone of the finger. The one DOF and two DOF structure type of the driving mechanism were analyzed. A kinematical model for the hand exoskeleton is built. Kinematics and dynamics of the hand exoskeleton are analyzed, and their equations are built. A controller architecture using an ARM processor as the kernel is built based on SPI bus. Finally, dynamics simulation of the hand exoskeleton and flexion rehabilitation experiment of the index finger are done. The results demonstrate that the hand exoskeleton system works reliable and the rehabilitation principles are correct, and the exoskeleton system can satisfy the rehabilitation requirements of the injured fingers.Keywords：rehabilitation;hand exoskeleton;Kinematics;dynamics- 39
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Published：2020-08-12 -
Design on Open-Loop Liquid Crystal Adaptive Optical System for 1200mm Telescope
Abstract：In astronomical observation and space object detection,larger-aperture telescopes are used widely.Liquid crystal adaptive optics imaging technology has been used in correction of the aberration caused by atmospheric turbulence.In order to verify the validity of the technology and maximize energy utilization，Zemax is used to design the liquid crystal adaptive optical system,and the characteristic of the system is evaluated.Obtained modulation transfer function(MTF) of the liquid crystal adaptive optical system is almost the same as the diffraction limited.MTF 0.4@50 lp/mm.The limited resolution of the CCD is 31 lp/mm,we could see that the resources of CCD has been used effectively.The focal length of the whole optical system is 19.9m and the F number is 16.The peak-valve(PV) value is 0.0314λ.Keywords：adaptive optics;optical system;telescope;off-axis parabolic reflective mirror;Zemax software- 72
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Published：2020-08-12 -
Application of modeling methods of RTV adhesive in reflective mirror structure dynamical analysis
Abstract：Making research on modeling methods for RTV adhesive in reflective mirror structure. The methods of node-connection(ignoring RTV adhesive)）,isotropy（three elements and one element） and anisotropy materials are detailed introduced respectively. The FEA model of lens sets was created and the mode analysis was made. At same time, the mode test equipment was setup and the mode parameters were tested for lens sets. The results show that error between the first free mode frequency got from the modeling method of anisotropy and the first free mode frequency got from test was only 0.3%, and the errors of the method of isotropy three elements and one element and node connecting are 1.8％, 1.2％ and 13.9%. From analysis and test, we can conclude that the RTV adhesive can not be ignored in FEA, The method of isotropy for one element can not only reduce the quantity of model number, but satisfy engineering requirementKeywords：RTV;FEA;Modal analysis;modal test- 38
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Published：2020-08-12 -
Large dimension industrial measurement system based on stereo vision
Abstract：In order to realize rapid measurement on large dimension object in industrial fields, a new measurement system based on Stereo Vision was proposed and implemented. The system employing several CCD as vision sensors obtains pictures of the object from deferent viewing positions, finds out 2D coordinates of the points in each pictures ,then calculates their 3D coordinates based on the method of intersection. Global reference points are inspected by Multi-View Stereo Vision system: a high-resolution CCD camera is used to take a group of pictures surrounding the object, after analyzing the obtained 2D parallax pictures, the measurement software carries out 3D reconstruction of the global references points. Local area dense points is inspected by Binocular Stereo System:, after focusing the measurement head to given area object, projecting the coded stripe on the surface, meanwhile capture pictures from the left and right CCD camera synchronously, the measurement software automatic carry out the stereo matching, reconstruction, result in local area dense points clouds. Also, software transforms the local dense points clouds to the global reference points coordinates system, according to the relation between local reference points and global reference points. Experiment show that the new system is capable of meeting precision and efficiency demand of large dimension measurement.Keywords：stereo vision;Reference points detect;stereo matching;Reconstruction;Points cloud alignment- 57
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Published：2020-08-12 -
Eccentricity Parameter Identification of Angle Sensors for Articulated Arm CMMs
Abstract：An articulated arm coordinate measuring machine (AACMM) is a type of nonorthogonal coordinate measuring system, whose probe coordinate values are transformed from joint angle values which are measured by angle sensors, such as circular gratings. As a result, the installation accuracy of angle sensors is an important factor relating to the measuring precision of an AACMM. The coordinate system of an AACMM was established and a compensation expression for angle measuring error was obtained from analyzing off-center installed error of circular gratings of an AACMM. Theoretical analysis showed that a little eccentricity could cause major error, so that angle data of circular gratings should be corrected in practical applications. A method of using single-point repeatability as the objective function to identify eccentricity parameters of an AACMM based on a simulated annealing algorithm was introduced and applied to identify the twelve eccentricity parameters of an AACMM. The result demonstrated that the repeatability of an AACMM was improved about 11.3%.Keywords：articulated arm coordinate measuring machines;angle sensors;eccentricity error;parameter identification;error compensation- 38
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Published：2020-08-12 -
Research on Connecting-rod Initial Splitting Notch Based on Nd: YAG Solid Laser
Abstract：As the key technology and core process of connecting-rod fracture-splitting, the design and processing of the splitting slot influence the fracture-splitting quality of the connecting-rod. In order to improve the quality of connecting-rod splitting notch, the author tested splitting notch laser processing on two kinds of connecting rod by applying Nd：YAG solid laser and analyzed the influence of different cutting parameters on quality as well as optimizing the cutting parameters of laser. The result showed that laser peak value power, clearance between focus and plate, cutting speed, impulse frequency, assistant air pressure, angle of laser incidence had great influence on processing quality of splitting notch. The peak power of laser as the main factor influences the depth of splitting slot. The ratio between cutting speed and impulse frequency is 1:3 and in the condition of minus clearance between focus and plate, splitting notch processed does good to splitting of connecting rod.Keywords：connecting-rod;fracture-splitting;splitting slot;laser notching- 55
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Published：2020-08-12 -
Variable structure changing integration rate control and implement for Flywheels
Abstract：In order to balance responsibility and steady performance of flywheels, a combination of constant switching variable structure control and changing integration rate control was established on the basis of analysis of constant switching variable structure control and changing integration rate control. Constant switching variable structure control with switching characteristics, fast response, but there are buffeting. Changing integration rate PI can change the accumulation of integration speed, corresponding with the size of the deviation, with high stable precision. The advantages of changing integration rate can make up shortcomings of constant switching variable structure control. So method of variable-structure changing integration rate control is put forward. The experimental results indicate that the system dynamic performance and steady performance have been greatly improved. Under sine orders of offset 1000rpm, amplitude 100rpm, cycle 0.01Hz, the tracking error is 2rpmKeywords：Satellite attitude control flywheel;PI control;Variable structure control;changing integration rate PI;Speed tracking- 33
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Published：2020-08-12 -
EXPERIMENTAL RESEARCH ON ASYMMETRICAL ROTATED PIEZOELECTRIC ACTUATOR BASED ON THE PRINCIPLE OF INERTIAL IMPACT
Abstract：The asymmetrical rotated piezoelectric actuator is mainly driven by sawtooth wave- a kind of asymmetrical wave. Focused on the disability of symmetrical wave drive, a new kind of asymmetrical gripper mechanism is designed, which is used to fix the piezoelectric cantilever bimorphs. Based on the principle of the converse piezoelectric effect, using symmetrical wave to drive the piezoelectric cantilever bimorphs is proposed. The piezoelectric cantilever bimorphs get inertial impact force on which symmetrical wave acts, by which the rotated actuator is driven. The dynamic model of the rotated actuator is constructed, whose movement principle is analyzed, too. Experiment testing system is built and the rotated actuator’s velocity characteristics under different frequencies and voltages are tested. The results show that the asymmetrical rotated piezoelectric actuator realizes stable and forward direction movement. When the voltage is 20V and the frequency is 2Hz square wave, its average step is up to 12μrad and the rotation velocity is up to 24μrad/s. The rotated actuator’s maximum stroke is 360°, carrying capacity reaches to 300g, resolving capability is 5µrad, and rotation velocity achieves 4000µrad/s.Keywords：Asymmetry;Impact drive;piezoelectric cantilever bimorphs;Rotated actuator- 36
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Published：2020-08-12 -
Study on the novel process of reducing subsurface damage in grinding by Magnetorheological Finishing
Abstract：Based on the low subsurface damage in Magnetorheological Finishing (MRF) process, a novel optical machining process is introduced to continue with grinding by MRF rather than lapping. Experimental research on this novel process, reducing subsurface damage caused by grinding by MRF, is finished with KDMRF-1000F polishing machine and KDMRW-2 water based MR fluids. One K9 flat (100mm in diameter) is rough polished (depth 50um, 156min) and surface roughness Ra is 0.926nm. Then, it is finishing polished (depth 200nm, 17.5min) to remove the ripples caused by rough polish and final surface roughness Ra is 0.575nm. The result shows that MRF is a low subsurface damage deterministic process, which results in high surface roughness (below 1nm), low subsurface damage and high machining efficiency.- 47
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Published：2020-08-12 -
Design of spinning superconducting rotor drive device and analysis of driving force
Abstract：A spin drive device of superconducting rotor was designed based on Meissner effect. The electromagnetic field generated by the stator coils engenders rotating torque on the superconducting rotor through the windows on its inner wall. The driving force was calculated using finite element analysis and the results show that the driving torque is approximately in proportional to the square of drive current. Rotation experiments were performed at 4.2 K, 30 Pa. Rotation speed of 8512 r/min was achieved with 30 A drive current. The experimental results will be good references for the further improvement of operating parameters and rotation stability of superconducting rotor.Keywords：cryogenic environment;superconducting rotor;electromagnetic force;FEA- 32
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Published：2020-08-12 -
Design and analysis of a novel 3D precision displacement system
Abstract：A novel 3D precision displacement system of large travel, nanometer level and displacement measurement by itself has been developed. The precision displacement system is designed with modular structure. The driving mechanisms of three directions are adopted with identical design structure and called as X direction, Y direction and Z direction one-dimensional worktable respectively. The dual-stage actuators of coarse and fine driving have been applied in the precision displacement system in X, Y and Z directions and three sets of metrology gratings are installed in X, Y and Z directions respectively. In this system, the driving mechanisms of X direction and Y direction are placed horizontally with upper and lower stacked structure, the driving mechanism of Z direction is placed vertically. In every direction, AC servomotor coordinating with precision lead screw and linear guide actuate the coarse driving, piezoelectric micro-displacement actuator coordinating with flexure hinge actuate the fine driving, a set of metrology grating is used for the displacement measurement of the coarse driving and fine driving. Therefore the need of large travel, nanometer level and displacement measurement by itself of the displacement system can be satisfied. The structure design of the displacement system is introduced. The displacement resolution, the metrology principle and the motion performance of this displacement system are also analyzed in details. Thereby the theoretical basis for displacement system design is provided.Keywords：3D;precision displacement system;structure design;coarse and fine driving;metrology principle- 66
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Published：2020-08-12 -
Helical Sweep System for Volumetric 3D Imaging
Abstract：One of the important roles of real-time, high-resolution volumetric three-dimensional imaging is a projection space, which is steady and unique, so a novel system of double-helical sweep screen was proposed, which rotating together with the shaft was droved by motor, after characteristics of projection spaces created by swepte volume and static volume techniques were compared and analyzed. The design scheme of screen structure used high strength photosensitive translucent resin material, supporting wall, rapid prototyping and direct digital manufacturing. The three dimension model of helical sweep screen is made by SolidWorks software and the dynamic testing by the COSMOSWorks module. The simulation results showed that the maximum displacement of screen rotating at 600rpm is 0.013mm which is far less than visual resolution range for realistic image synthesis, so projection space based on helical sweep screen could match imaging requirements. Finally, the system platform was built on the base of the existing engineering and technological level. Experience results showed that the platform could produce a steady projection space (25cm×Ф50cm), and supply excellent volumetric three-dimensional images.Keywords：Projection screen;imaging system;image quality;Three dimensional model;Screen displacement- 51
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Published：2020-08-12 -
Preload and precompact analysis and calculation of two-piece outer ring self-aligning ball bearing
Abstract：Preload is an effective way to ensure the bearing having the high working stiffness and accuracy. The analysis and calculation of preload and precompact of a kind of bearing is given in this paper. This bearing is a combo of double row angular contact ball bearing and double row self-aligning ball bearing. The main feature of double row contact angular bearing is that it can be preloaded during the integration. The direct result is that the working stiffness of the rotator, supported by the double row contact angular bearings, can be improved greatly. For the double row self-aligning ball bearing, just as its name states that its main feature is that it can compensate the misalignment of the shaft supporting bases. So, the main features of the combo are: preloaded to enhance stiffness and self-aligning to compensate the misalignment. We call this bearing two-piece outer ring double row self-aligning ball bearing. In order to be preloaded properly, the outer ring is consisted of two spherical inner face raceways, which form a spherical surface whose center is common to the bearing center, and a in-between spacer. Controlling the thickness of spacer is a way to control the bearing preload. The inner ring has two raceways. The steel balls, cage and inner ring can rotate freely at a certain angle. The allowable misalignment angle of this bearing is about 3 °. The relationship between preload and bearing supporting load is analysed and formulated with the help of mechanics theory. Meanwhile, based on the Hertz contact theory, the formular to determine the spacer thickness is given in this paper.This kind of bearing was adopted in China national key scientific project LAMOST telescope focal rotating axis and got perfect performance: the radial runout is less than 0.02mm and axial runout is less than 0.03mm of a φ1100mm bearing at arbitrary 50°angle（working range）. The tracking accuracy of focal rotation axis is better than 0.3″supportted by this kind of bearings.- 43
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Published：2020-08-12 -
System-level Simulation of Complex MEMS Based on Nadal Analysis Method
Abstract：System-level simulation plays an important rule in design and development of MEMS products. In this paper, a brief introduction to the two uniform modeling and simulation approaches, i.e, using Analog/Mixed Signal Hardware Description Languages(VHDL-AMS, Verilog-A, etc.), and equivalent electrical representation, is presented at first. Then, based on the Nodal Analysis Method of MEMS, a new approach to establish equivalent circuit model of complex MEMS is mainly discussed, which is different in essence from the conventional method based on signal-flow principle. Combined with the analysis and design of a typical integrated Microsystem, viz., a comb-shaped electrostatic feedback micro-accelerometer, the approach is specifically illustrated and validated. Finally, aiming at their principles，features and applications, the two simulation approaches are further summarized and comparatively discussed.- 43
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Published：2020-08-12 -
The Hysteretic Modeling for WTYD Type Piezoceramic Micro-Actuators
Abstract：In order to model the hysteretic curve between the displacement and applied voltage from and to the WTYD type piezoceramic micro-actuators, the Bouc-Wen model to characterize the hysteretic relationship between the displacement and applied voltage from and to the piezoceramic micro-actuators is put forward through using the Bouc-Wen hysteretic operator to mimic the hysteretic component and a corresponding parameter identification method is established. In order to evaluate the effectiveness of the developed model and parameter identification method, the corresponding experimental setup is established and the model validation is carried out. The research results show that the proposed Bouc-Wen model for the WTYD type piezoceramic micro-actuators and the parameter identification method can portray the hysteretic characteristics of the WTYD type piezoceramic micro-actuators.Keywords：piezoceramic micro-actuator;hysteresis;Bouc-Wen hysteretic operator;parameter identification- 38
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Published：2020-08-12 -
On the star calibrates the integral ball standard source - stationary stream source driver's development
Abstract：To each kind of standard source's request is the luminous intensity stability and the accuracy, and the life is long, this is decided by lamps and lanterns' careful manufacture and power source's stability, the operating current stability and the voltage surge is very big to the standard lamp's stability and the life influence. On the star calibrates the integral ball system is requests the guarantee to calibrate for the star on with the halogen tungsten lamp provides the standard the stationary stream power source, its stability request achieves 0.16%. This article introduced from the practical application angle has the soft start characteristic standard lamp stationary stream to actuate power source's principle of work and the application electric circuit, and increases through the adjustment third-level tube the method adjusts the soft start the time. Connects the high precision resistor through the electric circuit, gatheRS in its voltage computer circuit the electric current method to obtain 0.037% electric current stability, because each time starts the power source to be able to have the duplicated erroRS, converts into may achieve 0.043% electric current stability to the entire electric circuit. The experimental result indicated that 0.043% electric current lasting accuracy already definitely might satisfy the integral ball system light the change not to surpass 1% requests.Keywords：Standard lamp;standard source;stationary stream;source soft start characteristic- 62
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Published：2020-08-12 -
Design of active disturbance rejection controller for electro-optical tracking servo system
Abstract：In order to track maneuvering targets fast and accurately, an active disturbance rejection controller for electro-optical tracking servo system is presented and its work principle is investigated. Based on structure analysis of a certain system, the target velocity is contributed to exterior unknown disturbance and the system parameter change is looked as interior unknown disturbance. The extend state observer and tracking differentiator are used to estimate the disturbance accurately with the input and output information of system response, then the controller can compensate the disturbance furthest. Experimental results indicate that the system can fast track maneuvering targets at maximal 40mrad/s angular velocity and maximal 8mrad/s2 angular acceleration while the maximal tracking error less than 0.1mrad and the maximum overshoot less than 10%, and it has good robust performance. Without useing the sensor to measure the target state, it can satisfy the system requirements with a simple structure.Keywords：electro-optical tracking;servo system;Active disturbance rejection controller- 35
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Published：2020-08-12 -
Online Speaker Clustering Based On Decision Tree
Abstract：Speaker clustering is a key component in many speech processing applications. This paper addresses the problem of the clustering speakers when no information is available. When performing online speaker clustering, it is common to make clustering decision as soon as an audio segment is received. When the wrong decision is made, the error can propagate the posterior clustering. This paper describes an improved online speaker clustering algorithm which based a decision tree. Unlike typical online clustering approaches, the proposed method constructs a decision tree when an audio segment is received. A pruning strategy for candidate-elimination is also applied. Experiments indicate that the algorithm achieves good performance on both precision and speed. By using the method, average speaker purity is improved by 0.9%, and average cluster purity is improved by 1.1%, and the elapsed-time is reduced by 57%. Experiments also show that this method is effective at improving the performance of the unsupervised adaptation even comparing with the true speaker-condition.- 44
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Published：2020-08-12 -
Robust object tracking based on improved mean-shift algorithm
Abstract：Traditional Mean-shift algorithm for object tracking has some disadvantages, such as the localization drift caused by the background pixels and the tracking failure when the object undergoes occlusion. In order to overcome the above mentioned 2 shortcomings, improved Mean-shift algorithm is proposed. Firstly, according to the difference of color distribution between the object and the background in the initial frame, log-likelihood image is set up to select the discriminative color features for object modeling. The candidate modeling is done the same way. Secondly, the whole candidate region is separated into several overlapped fragments. Mean-shift iteration is done to every fragment and the target localization is reset by the location of the fragment in the candidate region that matches most to the corresponding fragment in the object region. The fragment based Mean-shift is very robust to partial occlusion. When object is severely occluded, linear prediction is used to estimate probable location of the object in the next frame. Experimental results prove that tracking using the improved Mean-shift algorithm has good localization precision and is robust to partial and severe occlusion.Keywords：object tracking;Mean-shift;Log-likelihood image;Occlusion- 57
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Published：2020-08-12 -
Multi-node Cooperative JPEG2000 Image Compression Method Based on Neighbor Clusters in WSNs
Abstract：The main characteristic of Wireless Multimedia Sensor Networks (WMSNs) is nodes with limited energy, memory and computational power. Motivated by this, the concept of in-network processing has been proposed which greatly inspires the study of compression and transmission of big size and high resolution images in WMSNs. Based on the characteristic of JPEG2000 and the network architecture of WSNs, the paper proposes a multi-node cooperative JPEG2000 image compression method based on neighbor clusters. Firstly, the images captured by the camera node are partitioned into tiles. Then the tiles are sent to the neighbor clusters and compressed by multiple nodes cooperatively. Simulation results show that the proposed image compression method not only makes the JPEG2000 compression of big size images a reality in the WSNs, but also greatly lightens the energy consumption burden on the camera node which leads to a longer network lifetime.Keywords：Wireless sensor networks;image compression algorithm;JPEG2000;multi-node cooperation- 33
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Published：2020-08-12 -
A Novel Adaptive Assembly Strategy for OBS Network
Abstract：Objective: In order to improve the assembly performance of Optical Burst Switching (OBS) network, by analyzing the shortcomings of existing assembly strategies, the novel adaptive assembly strategy for the edge node of OBS was presented in this paper. Method: By means of introducing the cross counter, the strategy proposed in this paper adopt a dynamic threshold system, which was different from former assembly strategy that could be considered as a fixed threshold system. The novel strategy measured the network traffic flow and chose a suitable assembly threshold dynamically according to the cross counter, moreover, the value of assembly threshold modified by the step length according to the similarities and differences type of assembly threshold with former one. Result: Simulation results show that the novel strategy can reduce the burst loss probability by 69.07% and 38.89% compared with the existing assembly strategy. Conclusion: Therefore, the novel strategy not only can adjust the assembly threshold according to the traffic flow, but also can have lower burst loss probability under strong self-similar case that be demonstrated adapt to burst traffic.Keywords：optical burst switching;Assembly strategy;Self-tuning adjust;Self-similar traffic;ON/OFF source- 33
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Published：2020-08-12 -
Monocular measurement in a binocular measurement system with instantaneous random illumination
Abstract：For the characteristics of binocular stereo measurement system based on random pattern projection, a novel method for measurement was presented, where each monocular measurement system was composed of single camera and the projector. First, a simple and effective calibration algorithm was proposed to reconstruct the ray, which every point of the random pattern plate projected through projector lens. The calibration was done by just taking several images (called calibrated images) of the common white board with random illumination in different orientations. It is unnecessary to calibrate the distortion of projector lens, and its precision can tolerate the effect of the distortion of projector lens. Then, the object’s image captured in random illumination was matched with the calibrated image at sub-pixel location, and the 3D point cloud data of the target object were obtained by triangulation principle. Finally, a standard plane was measured to verify the measuring accuracy of monocular method, and several measurement examples were concretely provided. Experimental results indicate that the precision of flat measurement is 0.0175mm, and the uncertainty is 0.05mm(3σ). Since a space point does not need to be observed by both cameras in monocular measurement system, it avoids losing 3D data resulted from local highlight and self occlusion, and effectively makes up for the lack of binocular measurement system.Keywords：binocular stereo measurement;camera-projector;calibration;random illumination;3D measurement- 22
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Published：2020-08-12 -
Implementation of Eliminate Cloud and Mist Noise from Remote Sensing Images
Abstract：Objetive: In order to eliminate the cloud and mist from remote sensing images, a new non-local means algorithm is proposed to process the cloud and mist noise from remote sensing images. Method: First, based on the gradient feature under the shadow of cloud and mist in the remote sensing images, it finds that the intensity declines obviously while the gradient only has a little change, so it couples gradient information when compute the weight. Then, computing new weights uses redundant information in image sequences. Finally, restoring the image sequence using the new weight. Result: The proposed algorithm can restore remote sensing images without the motion estimation of the cloud and camera as well as the noise model. Two remote sensing image sequences were carried out by UltraCamD in Xinjiang and Shanxi area in China, and results show that relative to traditional algorithms, the quality of restored image improves significantly by this algorithm, and PSNR improves more than 9dB. Conclusion: It shows that this algorithm can restore images that coverd by thin cloud and mist effectively.Keywords：non-local means;gradient;image sequences;eliminate cloud and mist- 48
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Published：2020-08-12 -
Design of a real-time color video capture system for area array CCD
Abstract：In order to realize color video capture using area array CCD, a real-time color video capture system is established. This paper presents the hardware and software design of a color video capture system of area array CCD ICX424AQ from Sony company, which can be used in color video capture system. The paper made a detailed analysis on the structure parameters of area-array CCD and the color video gathering principle. On that basis, the design realizes the CCD control sequence and the timing logic of the whole capture system. The noises of the video signal (KTC noise and 1/f noise) are filtered by using the Correlated Double Sampling (CDS) technique, and the signal-to-noise ratio of the system is enhanced. The area array CCD image sensor is covered by Bayer color filter array (CFA). Each pixel has only one component of three primary colors. In order to obtain full chromaticity at every pixel, the paper adopts an enhanced bilinear algorithm. The algorithm compute green components first using bilinear interpolation algorithm, then make interpolation of Red components and Blue components according to distributing of green components. The algorithm made a compromise solution between the complex of hardware implementation and image quality through interpolating. The CCD is working under progressive scan mode. All pixel signals are read out simultaneously at the exposing time of 0.32ms. The whole system is controlled by FPGA, the pixel data readout is interpolated and then transmits by transmitting chip SiI1162. At last, the design realizes the real-time video display on TFT-LCD.Keywords：Area array CCD;Video capture;FPGA;correlated double sampling (CDS);Demosaicing- 36
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Published：2020-08-12
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