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Issue 12 ， 2013
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Gelcasting process of 1.5 m SiC ceramic green body
Abstract：A Φ1.5 m silicon carbide(SiC) ceramic green body with a lightweight structure was prepared by gel casting method. The effects of Particle Size Distribution （PSD）, solid loading and milling time on the SiC suspension were studied systematically. Then the microstructure and bending strength of the SiC green body, and the mechanical and thermal properties of Reaction Bonded SiC(RBSiC) were measured. The results show that the 65% solid loading SiC slurry with good flow properties is prepared by optimum PSD in a stable dispersion condition. The slurry viscosity of SiC increases rapidly with the solid loading.However, the apparent viscosity of SiC slurry reduces and then increases with the milling time. Moreover,the SiC slurry was injected into a mould, and a Φ1.5 m SiC ceramic green body was obtained.The ceramic green body after degreasing has a uniform interior structure and a bending strength of 24.6 MPa.Keywords：gel casting;SiC;ceramic green body- 59
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Published：2020-08-12 -
Automatic mode-lock circuit applied on NPR passive mode-locked fiber laser
Abstract：As passively modelocked fiber lasers based on Nonlinear Polarization Rotation(NPR) have the problem of low stability and difficulty to selfstart into a modelocking state during operation, an online automatic modelock circuit was designed to adjust the laser in real time to get a stable modelocked output. In the design, the signal from NPR passively modelocked laser was transformed to an electrical pulse signal with a high speed photoelectric detector, and it was amplified and shaped linearly to be received by the Micro Computer Unit(MCU) to count. Then the MCU distinguished the state of the laser based on quick modelock judge algorithm and adjusted the electric controlled polarization controller (PC) on the fiber laser automatically. The experiment results show that for the NPR modelocked fiber laser with a repetition rate of 6.238 MHz ,the automatic modelock circuit can distinguish the losing lock in 6 ms, and can find and get into the modelock state in 10.24 s automatically. For NPR passive modelocked fiber lasers with repetition rate lower than 16 MHz, this automatic modelock circuit can get into a stable modelocked state quickly or restart immediately if the modelock state is lost for some reasons，which reaches the design requirements and shows advantages of simple structures, low costs, low powers, and high reliability.Keywords：fiber laser;passive mode-locked;electronic polarization controller;automatic mode-lock circuit;nonlinear polarization rotation- 56
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Published：2020-08-12 -
Influence of polarization direction nonorthogonality on precision of polarization phase shifting interferometry
Abstract：The influence of polarization direction orthogonality on Polarization Phase Shifting Interferometry(PPSI) was analyzed to improve its measurement precision. Based on the analysis of PPSI principle, it points out that the measurement error is a function of Optical Path Difference(OPD) and the PV of measurement error is proportional to the nonorthogonality and the ratio of amplitudes of test beam to reference beam. The polarization nonorthogonality can be introduced by the reflection or refraction on a surface. Then several approaches were recommended to depress the nonorthogonality, such as proper coatings, incident angles and polarization directions. A configuration of SkipFlat test with incident angle of 45° was set up. It shows that the distribution of measurement error is coincident with that of OPD. Moreover,the measurement error is 0.174 1λ (PV), which is in agreement with that of the theoretical analysis.Finally, the paper suggests that it is necessary to analyze individually each of the component under the test for making sure the measurement precision.Keywords：optical testing;Polarization phase shifting interferometry;Polarization Orthogonality;Optical Path Difference(OPD);Skip-Flat testing- 62
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Published：2020-08-12 -
Measurement of dynamic damaged materials by white light axial chromatic aberration
Abstract：The feasibility of morphologic measurement for Dynamic Damaged Materials by the white light axial chromatic aberration method was explored, and the internal dynamic damage of materials was characterized and quantized precisely. First, the surface profile measurement technique based on white light axial chromatic aberration was used to measure the crosssection of samples recovered softly from dynamic impact experiments. Then, the crosssection image and 3D surface topography were obtained by reconstruction of the test data. Finally, based on the test data, a new method to calculate the damage of samples was established and the damage curve of the samples was calculated. The results indicate that the axial chromatic aberration measurement can measure a wide range crosssection of the sample(6.9 mm×9.999 mm) without disconnection and can receive a clearly threedimensional morphology of the sample crosssection. The resolution of the damage curve can be improved to 3 m. It means that the white light axial chromatic aberration method used to measure the dynamic damage sample is effectively. It can implement a continuous measurements with largescale and highprecision and show its characteristics in smaller operation, simpler calculation and higher resolution.Keywords：White light interferometry;suface profile measurement;Axial Chromatic Aberration;Dynamic Material Damage;quantitative analysis- 68
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Published：2020-08-12 -
Computer-controlled chemical mechanical polishing of silicon modification layer on aspheric silicon carbide surface
Abstract：A computercontrolled Chemical Mechanical Polishing(CMP) technology was presented to polish a silicon modification layer on the aspheric silicon carbide(SiC) surface in high precise and efficiency to achieve a high quality aspheric SiC mirror. The polishing theory of CMP for the silicon modification layer on aspheric SiC surface was studied. Then, the principle of computercontrolled CMP for manufacturing a surface modification aspheric SiC mirror was described. With comparing the computercontrolled CMP and ordinary computercontrolled polishing, the superiority of computercontrolled CMP was explained. Furthermore, on the basis of experiments, the material removal function of computercontrolled CMP was studied. Finally, a Ф120 mm surface modification aspheric silicon carbide mirror was polished by computercontrolled CMP technology according to the material removal function. The initial figure error of the mirror is 0.253λ(RMS)（λ=0.632 8 μm）. After about ten polishing iterations, the final figure error and roughness of the mirror are 0.014λ (RMS) and 0.538 7nm (RMS), respectively, which can satisfy the desired optical performance．Keywords：optical fabrication;surface modification silicon carbide;chemical mechanical polishing;computer-controlled polishing;material removal function- 63
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Published：2020-08-12 -
Characterization and modeling of static compound speckle in laser projection display
Abstract：The optical system which produces speckles in a laser projection display system was simplified. By combining theories and practices, the simplified system was used to analyze the formation mechanism of a compound speckle and its effective characterization. Based on the speckle contrast analysis method, four important factors affecting the contrast of the compound speckles were analyzed by the experiments, namely, the spot diameter of an incident light beam, the distance between diffuser and screen, the coarse speckle granule on the screen and the fine speckle granule above the screen. Then, the contrasts of the compound speckles as a function of these parameters were determined by the experimental data. After researching the constitute of the compound speckle, a relational model based on contribution of the coarse granule and the fine granule on the compound speckle was presented by statistical analysis method and confirmed by an experiment. Obtained results provide an effective experimental basis for the speckle suppression in the laser projection display.Keywords：Laser projection;laser display;laser speckle;compound speckle;speckle characterization- 69
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Published：2020-08-12 -
Selection of system compensators for small scale projected objective
Abstract：As the small scale model optical system for a projected objective of lithography has so many optical elements, it is impossible to use a traditional method that each compensator only compensates the corresponding misalignment. Therefore, this paper proposes a sensitive matrix to solve this problem. Firstly, the internal relations between the decenter disalignments and the tip/tilt ones were found out based on a sensitive matrix to reduce the range of selection compensators. Then, according to the analysis of the disalignment sensitivity, a method for selecting system compensators was proposed. With the method, only selected four compensators could allow the imaging quality of compensated optical system to achieve the design index and the alignment difficulty to be reduced. Finally, the macro command modes were proposed to complete the massive simulation calculation to prove the correctness of the sensitive analysis. After the original assembling, a prealigning procedure of optical system was achieved to ensure the feasibility of the aligning scheme. The test results show that the wave front errors (RMS) have reduced to 25.9 nm from 50.9 nm after compensation, which is better than the requirements of qualifications. The results prove that the proposed methods are right and effective.Keywords：Projection objective;complex system alignment;compensators selection;sensitivity matrix;macro command mode- 72
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Published：2020-08-12 -
Application of differential optical absorption spectroscopy to geological logging
Abstract：As traditional gas logging based on vapour phase chromatography has a longer analysis period, lots of aided equipment and difficult to be maintained， this paper studies the online detection of alkane during oil exploration in series. An infrared spectral logging equipment independently based on the theory of Differential Optical Absorption Spectroscopy (DOAS) was designed. In the equipment, the PC104 was used as the main control unit, and the MFC as the software framework. A variety of techniques, such as the least square method, polynomial fitting, multithreaded programming technology were employed in the software. The equipment implemented the spectral acquisition, display, and saving. Moreover, the concentration inversion of the alkane gas and the realtime transmission by the serial port also were realized. Finally, the equipment was analyzed with a standard gas, and the error is less than 3%. The result shows that the equipment can analyze the realtime concentration of alkane gases and satisfy the factual needs of the logging industry for its stability and reliability.Keywords：Spectral detection;Differential optical absorption spectroscopy;Spectral logging;least square method;alkane gas- 74
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Published：2020-08-12 -
Development of diagnostic imaging spectrometer for tumor on-line operation
Abstract：On the basis of characteristics of imaging spectrometer with imagingspectral information at the same time, a portable PrismGratingPrism(PGP) imaging spectrometer was developed for clinical monitoring and intraoperative navigation. The design principle of the optical system was introduced and analyzed according to the requirements. Then, the principal parameters including spectral resolution, spectral smile, and keystone were tested. The actual spectral resolution was up to 5 nm, which satisfies the needs of clinical application. After combing the imaging spectrometer and an operation microscopy, this paper diagnoses the brain tumors of rats online, and acquires lots of imaging spectral data of brain glioma. By analyzing the spectral data, the position and the size of the tumor is obtained precisely. Obtained results demonstrate that imaging spectrometer developed is characterized by its high resolution and smaller volume and can diagnose tumors in the operation on line for its common interface with a microscopy.Keywords：imaging spectrometer;prism-grating-prism;tumor;clinic diagnosis- 66
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Published：2020-08-12 -
Synthesis conditions and electric properties of Lu2Ti2O7 thin films prepared by the sol–gel technique
Abstract：The structures, fabrication and properties of Lu2Ti2O7 thin films were explored. Depending upon solgel fabrication technique, the influence of the spinning parameters, such as annealing temperature, holding time, rotating speed and the number of coating layers on the microstructure including surface roughness was investigated systematically. Then the electrical properties of the Lu2Ti2O7 films deposited on Si substrates were researched to optimize the parameters for the growth of Lu2Ti2O7 films. The investigation reveals that the annealing temperature no less than 750 ℃ is necessary to obtain an optimal thin film containing less amount of Lu2TiO5, which is formed at temperature arranging from 650 ℃ to 1 050 ℃. Meanwhile, the studies also indicate that the calcination temperature shows a great influence on the surface roughness. Further analysis on electric properties suggests that the holding time is benefit to both the low temperature phase transition of Lu2Ti2O7 and the formation of Lu2TiO5 phase, but it has little effect on the electrical properties of the film. With Lu(NO3)3 and TiO2 as precursors, high densified Lu2Ti2O7 film containing less amounts of Lu2TiO5 phase can be prepared successfully via solgel route, and the less amounts of Lu2TiO5 phase can be eliminated by increasing the calcination temperature, prolonging the holding time or adjusting the ratio of Lu(NO3)3 to TiO.Keywords：Lu2Ti2O7 thin films;Sol-gel method;electron microscopy;Electric property;surface roughness- 61
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Published：2020-08-12 -
Flow-induced-vibration MEMS energy harvesting unit based on AlN film in silicon
Abstract：A flow-inducedvibration Micro-electronicmechanic System(MEMS) energy harvesting unit based on an Aluminum nitride( AlN) film on the silicon was presented. The AlN film with crystal orientation(002) was prepared by DC pulse magnetron sputtering and its performance was characterized by the X-ray Diffraction(XRD) and the Scanning Electron Microscopy(SEM). The results show that the crystal orientation and performance of the AlN film are depended on the seed layer materials, gas flow ratio and the substrate temperature, its crystal orientation is (002), and its intensity and Full Width at Half Maximum(FWHM) are 105 counts and 2.7°, respectively. The prototype of the flowinducedvibration MEMS energy harvesting unit was presented after optimizing process flow. The wind tunnel experiments show that the maximum power output of the flowinducedvibration MEMS energy harvesting unit is about 1.6 μW when the wind speed is 15.9 m/s. The optimization process also can be used to fabricate other MEMS devices based on the AlN film.Keywords：Flow-induced-vibration;MEMS energy harvesting;diffraction intensity;AlN film in silicon;Rocking curve- 42
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Published：2020-08-12 -
Reflection Photoelectric Encoder
Abstract：A reflective photoelectric encoder was developed. The grating self-imaging principle was introduced, the production process of a high-density reference grating was improved and a 32768 line grating and a highly integrated optical reading head were prepared. Then, the high-precision reflective optical encoder was completed. By using multi reference points, the encoder could confirm the absolute position easyly and quickly, and its standard zero point was determined by the most initialize rotate angle of 5.625°. The angle measuring accuracy of the encoder was measured by a self collimating light tube and a 23 surface prism.The measuring results indicate that the Mean Square Root Error for single reading head is 1.11″ and that for double reading head is 0.75″. The gap between reflection grating and reading head is about 2.0 mm,which is ten times larger than that of tradition type encoders. The results demonstrate that the high-precision reflective optical encoder developed has simple structures and its reading head shows high quality photoelectric signals. It can provide a solution scheme for high precision angle measurement.Keywords：high precision encoder;reflection encoder;grating self-imaging;high-density reference grating- 57
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Published：2020-08-12 -
Complex rapid omnibearing north seeking of pendulous gyroscope
Abstract：The pendulous gyro north seeker is difficult to complete the rapid omnibearing north seeking, for it is limited by initial erection azimuth seriously. In this paper, a complex rapid omnibearing north seeking method was put forward and the technological points involved such as the motion of pendulous gyro in a large azimuth, rapid omnibearing pre-direction, and fast coarse and precise north seeking in a small azimuth were investigated. Firstly, the motion equations of pendulous gyro in the large azimuth were established based on principles of rigid dynamics and its approximate analytic solution was gained by using the numerical analysis and curve fitting method. On the basis of the approximate analytic solution, the north seeking time and results of 1/2 period and 1/4 period step-measuring method were carefully studied and the step strategy was optimized. Then, a fast step coarse seeking and limiting method was proposed based on the analysis of curve fitting fast coarse north seeking and step fast limiting methods. Finally, a complex omnibearing method was designed with the combination of rapid omnibearing rough north seeking, fast coarse north seeking and limiting and the photoelectric integral method. Simulation results show that the basic shaft of the gyro can be stepped to the position of ±300′ from north within 190 s by optimized step strategy, the coarse north seeking and limiting can be achieved within 95 s, and the total time cost of the complex method is less than 11 min. With the complex method proposed, the azimuth angle in any direction can be determined accurately in a short time.Keywords：pendulous gyroscope;Omnibearing north-seeking;Complex north seeking;Step-measuring method;curve fitting- 76
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Published：2020-08-12 -
Output displacement calculation and experiment for inclined beam-type electrothermal microactuator
Abstract：To calculate the displacement of an inclined beam-type electrothermal microactuator, a multiphysics coupling model was established based on the electro-thermal and thermo-mechanical analysis. The thermal structure was analyzed, and the output displacement formula was obtained using the force method. For the purpose of proving the accuracy of the model, a comparison was performed. The comparison shows that the theoretical results of temperature profile and output displacement are in agreement well with the results of Finite Element Analysis(FEA) and experimental measurements. Finally, the output displacement repeatability and reproducibility were measured and the main factors influencing the output displacement of the microactuator were analyzed. Obtained results indicate that the ratio of length to width and the angle of the inclined beam are main influence factors on the output displacement and the different MEMS processes have obviously effects on the output displacement of the microactuator. Experimental results also show that the maximal displacement of the microactuator is 0.85 μm and 2.3 μm under the voltage of 18 V and 9 V,which means the relative errors with the results of theoretical calculation are 2.2% and 12.8% respectively. The above analysis indicates that the theoretic calculation values are coincident well with the measured values and the formulas deduced from the inclined beam-type electrothermal microactuator are logical, which can provide theoretical supports for the design and calculation of electrothermal microactuators.Keywords：Electrothermal microactuator;Electro-thermo-mechanical model;Output displacement;Micro-electro-mechanical Systems (MEMS)- 54
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Published：2020-08-12 -
Design and calibration of 3D Micro Tactile Probe based on MEMS Capacitance Sensor
Abstract：It is difficult to measure large size components in higher precision and a 3D mode in the micro-nano geometrical measurement. Therefore, a high resolution, small sized capacitance sensor was fabricated based on non-silicon Micro-electronic-mechanical system(MEMS) technology. By designing the packaging and weak-capacitance acquisition system of the sensor, a capacitance-based micro tactile probe was developed to measure the 3D dimensions in micro/nano scale. Then, a 3D micro displacement platform was designed to test and calibrate the probe. The macro-micro combination drive mode was used to design the stage and its moving range is 25 mm×25 mm×10 mm and the uniaxial resolution in 12 μm range is 1 nm. Finally, the range, linearity, hysteresis and resolution of the probe were tested. Results show that the axial range is 4.5 μm, the lateral range is greater than 5 μm, the axial resolution and the lateral resolution of the probe are less than 10 nm and 25 nm,respectively. The experiments show that the probe has a good linearity and its advantages are simple structure, high resolution, small volume and low costs. The probe developed can be integrated to the nano measuring and positioning machine (NMM) to complete required measurement tasks in large ranges and sub-micrometer or nanometer level accuracy.Keywords：Micro tactile probe;Micro capacitance sensor;Micro-electro-mechanical Systems (MEMS);Calibration device;Nano measuring machine- 49
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Published：2020-08-12 -
Ion mobility spectrometer using pulse corona discharge ion source
Abstract：The pulse corona discharge was employed as the ion source of an Ion Mobility Spectrometer (IMS) to replace the radioactive ion source to simplify the structure of the IMS. The features of pulse corona discharge was researched and the Number of positive Ions(Ni) in a single pulse corona discharge were measured. Then the relationships between the Ni and the high voltage pulse, the Ni and the electrode spacing, and the variation of NIs with high voltage pulse under different tip curvature radii were tested. After determing the electrode parameters of pulse corona discharge ion source, the pulse corona discharge ion source and the corresponding main structure of IMS were designed. Finally, the mobility spectrum of reactant ion H+(H2O)n in the air was detected by using the IMS built in our lab. The obtained results show that the time corresponding to the peak of IMS is 47.5 ms, and the peak half-width is 7.5 ms. Therefore, the spectrum resolution of IMS for reactant ion H+(H2O)n detection is 6.33. The experiments demonstrate it is feasible that pulse corona discharge is used as the ion source of IMS. Because the structure of pulse corona discharge can be easily realized using Micro-electronic-mechanic System(MEMS) technology, and its corresponding mobility pipe removes ion gate, the structure of IMS is simplified.Keywords：Ion mobility spectrometer;ion source;Pulse corona discharge;Micro-electro-mechanical Systems (MEMS)- 42
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Published：2020-08-12 -
Accuracy analysis for digital boresighting of aircraft gun
Abstract：To improve the accuracy and efficiency of setting an aircraft gun, a digital boresighting measurement method based on the laser tracker was proposed. Some topics on the establishment of the measuring precision field and the calculation method of installation deviation were discussed. Firstly, a local coordinate system built by common points was taken as the measuring basis and the actual gun aiming axis was extracted by a Cannon measurement instrument. Then the body axis of symmetry was got by reference points to calculate the actual position of the aiming point and installation deviation according to the assembly requirements. Furthermore, the measurement instrument design and error compensation method of a reflector holder were described in detail. Finally, the position accuracy of measure points was analyzed by the uncertainty ellipsoid, and an uncertainty model based on the theory of stochastic process was introduced to describe the position error of the bore axis. Experimental results indicate that the repeatability precision of the installation deviation is ±4.813 mm and the position accuracy of aiming point is about ±3 mm, which meets the assembly requirements of aircraft guns in real time, high-precision, high-speed and stabilization.Keywords：digital assembly;aircraft gun;calibration;laser tracker;boresighting;measurement uncertainty- 55
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Published：2020-08-12 -
Design of supporting structure for primary mirror of large aperture theodolite
Abstract：In consideration of the effect of support structure for the primary mirror of a large aperture theodolite on the surface figure precision of the primary mirror, the support structure of a Φ1 000 mm primary mirror was explored. The disadvantages of existing axial and radial supporting structures were analyzed and a new axial and radial complex supporting structure for large aperture primary mirror was presented. Then, the performing principle and the advantages of the supporting structure were discussed. A parameter model of primary mirror was built based on the finite element analysis software, the axial and the radial supporting positions were optimized and the surface figure errors of the optical axis for the mirror in vertical and in level orientations were analyzed. Obtained results show that the surface figure precisions are 2.52 nm and 4.33 nm in RMS values as the mirror's optical axis in vertical and level orientations, respectively. After alignment, the primary mirror is tested in its optical axis is in level orientation by an optical interferometer, and the mirror's RMS value is 19.87 nm in the measurement. The results fully satisfy the precision requirement of RMS value less than λ/30 (λ=632.8nm), which proves the feasibility of the axial and radial supporting structure mentioned above.Keywords：large aperture theodolite;primary mirror;supporting structure;surface figure precision- 73
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Published：2020-08-12 -
Temperature Compensation of Monitoring Circuit for Silicon MEMS Gyroscope
Abstract：A temperature compensation method was proposed based on the periphery circuit of a Micro-electronic-mechanical System(MEMS) gyroscope. The structure of SHH17# MEMS gyroscope developed by ourselves was introduced, the effect of temperature changes on the gyroscope was analyzed, and the resonant frequency, quality factor, scale factor and the null bias of driving and sensing modes were tested. The dynamic equation and test circuits of the gyroscope were analyzed, then it points out that the scale factor is in direct proportion to driving amplitude and the gain of sense loop, and is in indirect proportion to the frequency gap between two modes. A thermal resistant was taken as the compensation element to compensate the scale factor in a secondary amplifier, then the temperature coefficients and output values of the null bias were compensated by superposing a reference voltage within the low pass filter in an output module. Furthermore, the circuits of the two compensation points were expanded and the parameter’s configuration details were introduced. Experiments indicate that the temperature coefficients of scale factor and null bias have reduced from 393×10·℃-6 and 75(°)·h-1·℃-1 to 73×10-6·℃-1 and 20(°)·h-1·℃-1 respectively(reduce by 80% and 73% )and the null bias values have decreased from 89.95 mV to 7.33 mV.These results demonstrate that the proposed method is feasibility and correction.Keywords：Silicon Micro-electronic-mechanical System(MEMS) vibratory gyroscope;monitoring temperature circuit;temperature compensation;scale factor;Bias;Thermal resistant- 70
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Published：2020-08-12 -
Structure control of micrometer/nanometer scale reverse transformation austenite
Abstract：To control the micrometer/nanometer scale reverse transformation austenite structure, the effects of cold deformation and annealing parameters on the microstructural development and mechanical properties of the 316 L austenite were investigated. First, the cold deformation was performed for the specimens, and then the specimens with different deformations were annealed. The microstructural evolutions of the specimens were analyzed by using a optical microscope and a scanning electron microscopy, the composed phases of the specimens were researched by a magnetic measurement and X-ray diffraction and their mechanical properties were determined by Vickers hardness method and tensile tests. The results show that the stain-induced martensite is almost 71.72% at 90% cold deformation, and the hardness value increases from 193.10 Hv to 475.77 Hv. The resultant micrometer/nanometer grained steel can be obtained after annealing at 820-870 ℃ for 60 s and austenite grains with a size greater than 0.5 μm (70.4%)and less than 500 nm(29.6%) can be obtained after annealing at 850 ℃ for 60 s. Moreover, the specimens are completely reversed to austenite (100%). The resultant micrometer/nanometer grained steel not only exhibits a high strength level about 959.24 MPa, but also a desirable elongation of about 44.6%.Keywords：Austennitic stainless steel;Strain-induced martensite;Reversion;Grain refinement- 52
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Published：2020-08-12 -
Error analysis of target automatic positioning technology for airborne photo-electricity measuring device
Abstract：To improve the accuracy of a photo-electric measuring device, an automatic positioning system for airborne photo-electric reconnaissance equipment was established. Firstly, the positioning equation and error equation of the target automatic positioning technology were constructed based on homogeneous coordinate conversion, and the Monte Carlo analysis method was used to analyze the error of the target automatic positioning technology. Then, the wavelet analysis theory was brought to optimize the positioning error to improve the position accuracy. By analyzing experimental data and flight test data, it shows that optimizing the target automatic positioning technology by wavelet analysis theory can substantially improve the target automatic positioning precision by 70%. These results verify the feasibility and superiority of the target automatic positioning technology. The analysis method is also applies to surface tracking and measuring platforms and the ship-based tracking and measuring equipment.Keywords：airborne photo-electric measuring device;Target automatic positioning;coordinate conversion;error analysis;wavelet analysis- 89
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Published：2020-08-12 -
System Level Design of Microfluidics
Abstract：It is important to design microfluidic technologies for improving the efficiency of microfluidics and reducing the costs of research and development. However, system level design, modeling and simulation are significant methods for rapid design, optimization，and verification of the microfluidics. This paper introduces the principles and methods of microfluidic design, firstly. Then, it focuses on two main system level design methods, nodal analysis method and equivalent circuit method. After a brief discussion of microfluidic design technology, it introduces the modeling and simulation processes of the two methods, and overviews their research status and development trends in the last ten years at home and abroad. Finally, it summarizes merits and demerits of the two methods and discusses their development prospects. It points out that the system level design and modeling will be great superiority for design a microfluidic system with large-scale, complexity and multi-function.Keywords：Microfluidics;System level design;modeling;simulation- 63
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Published：2020-08-12 -
Ultra-High Pressure Sensor with Autofrettaged Cylinder Structure
Abstract：An ultra-high pressure sensor based on autofrettage technology and piezoresistive effect is developed to remove the residual stress in packaging and to ensure a high sensitive output in pressure measurement with a large range. The elastic element is made of high strength spring steel with cylinder structure, and the sensitive element is silicon flat chip with an inverted cup structure. When the pressure is applied to the metal elastic element, the axial deformation of the metal elastic element is occurred and passed to the chip via a pass rod, then the chip's resistive signal is proportional to the axial deformation based on the piezoresistive effect. The pressure measurement is accomplished by measuring the resistive signal. In the study of working ability of the elastic element, the load bearing strength of the elastic element is researched by combining the theory and simulation, and the autofrettage technology is used to improve the loading ability of the elastic element. Finally, the static performance experiments in 250 MPa and 1 000 MPa ranges are carried out for a packaged sensor respectively. The experiments show that the comprehensive accuracy of the sensor is 2.3%, the linearity is 0.7% in 250 MPa and 0.52% in 1 000 MPa . The simulative and experimental results both indicate that the metal elastic element with autofrettaged cylinder structure is able to endure ultra-high pressure beyond 1 000 MPa, and the developed sensor can meet the measuring demand of the contemporary industry.Keywords：ultra-high pressure sensor;autofrettage technology;piezoresistive effect;Micro-electro-mechanical Systems (MEMS);cylinder structure- 81
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Published：2020-08-12 -
Elite particle swarm optimization algorithm and its application in robot path planning
Abstract：To overcome the shortcomings of standard Particle Swarm Optimization (PSO) algorithm that is easy to trapp into a local optimum, the improved PSO was proposed based on the standard PSO. By inducing the renewal functions and a best selecting strategy, the improved algorithm could keep the fast convergence speed and reduce the possibility of trapping into a local optimum. As compared the standard PSO, the improved algorithm not only enlarges the searing space but also shows lower complexity. Obtained results prove that the algorithm is easy to be induced and has a higher global searching ability in high efficiency and better robustness. The improved algorithm was applied to solving the robot path planning problem. The simulation experiments show that the improved algorithm can get more accurate path in the robot path planning and its calculation time can reduced by 15% as compared with that of traditional methods. These results prove the feasibility and efficiency of the improved algorithm.Keywords：particle swarm optimization;robot path planning;benchmark function- 61
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Published：2020-08-12 -
Temperature adaptation of large aperture mirror assembly
Abstract：As the temperature adaptation effects the design process of a large aperture mirror assembly seriously, this paper researches the influence mechanism of temperature on the large aperture mirror assembly and discusses the necessity of temperature adaptation analysis and test. With the design flow of the large aperture mirror assembly given, the temperature adaptation analysis method is summarized. The physical calculation model of the large aperture mirror assembly is constructed by Finite Element Method(FEM). The final design status is confirmed after structural-thermal optimization. The temperature adaptation of the optimal design is analyzed in the orbit environment and on the ground environment. The results indicate that the temperature adaptation in the orbit environment is at the range of ±4 ℃ and the temperature distribution demands are 5 ℃ ,4 ℃ and 7 ℃ in X,Y, Z directions, respectively. Moreover, the temperature adaptation on the ground environment is at the range of ±3 ℃, and the temperature distribution demands are 4 ℃, 3 ℃ and 4 ℃ in X, Y, Z directions, respectively. The temperature adaptation test of temperature uniform change for the assemblies is performed, and compared with the test results of the corresponding analysis results. It shows that the PV value error is in 4% and the RMS value error is in 7% within a ±5 ℃ temperature range.Keywords：space camera;large aperture mirror;Thermal-elastic theory;Temperature adaptation- 76
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Published：2020-08-12 -
Mechanism on Dielectric Electro Active Polymer Generator
Abstract：To promote the industrialization of Dielectric Electro Active Polymer (DEAP) Generator, the stress-strain and the constitutive model were analyzed respectively based on the large strain electroluminescence characteristics of DEAP materials.Then, allowable effective work-states were analyzed, the mechanisms of electromechanical coupling and energy transformation for the DEAP in a static electric field were explored and its generation mechanism was studied. Finally, the energy conversion efficiency and the relation between stress and strain for the DEAP were simulated and researched. According to the process of energy cycle, an energy collection model with constant charge was put forward. Furthermore， a generating platform was constructed on the silicon resin elastic material and the generating mechanism was verified by simulation and experiments. The simulation results indicate when the DEAP stress is 25% with a 1.3 kV charge voltage, modeled energy generated per cm3 of DEAP is almost 5.8 mJ/cm3. The experimental results show that the more strain is got ,the more energy will be harvested from DEAP generator, meanwhile the experimental data will be more fitted the theoretical calculation.Keywords：Dielectric Electro Active Polymer (DEAP);energy transformation;constant charge;electric generation mechanism- 53
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Published：2020-08-12 -
“Black Soil Land” recognition at Maduo County in source region of Yellow River based on quantitative remote sensing
Abstract：The Multiple Endmember Spectral Mixture Analysis（ＭＥＳＭＡ）was used to extract the information to identify the “Black Soil Land” in a remote sensing image.Based on the MESMA proposed by Robert, the surface features in Maduo were analyzed while the endmembers were extracted. In consideration of the insufficient in applying MESMA to this research area, the decomposition strategy and its mechanism were optimized, then along with the formation mechanism of “black soil land”, modified MESMA was applied to extraction of the “black soil land” information. Identified results of “black soil land” was verified by the measured data, which shows the identifying accuracy is 82.81%, significantly higher than the accuracy of 71.09% from the MESMA and proves that the improved MESMA can identify the “Black Soil Land” effectively. On the basis of the improved MESMA , it indicates that the “black soil land” accounts for 1.592×103 km2 in Maduo County, and it mainly distributes in the northern Maduo County.In conclusion,the extracting efficiency for “Black Soil Land” has improved significantly as compared to that of visual interpretation method in guaranteeing the extraction accuracy. Preliminary analysis demonstrates that this method can also be applied to the extraction of surface composition information in other complex environments.- 46
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Published：2020-08-12 -
Object tracking based on sparse representation of gradient feature
Abstract：As traditional compressive sensing tracking algorithm will produce tracking errors in circumastances when illumination has dramatic change or there exists a object similar to the target in background, this paper proposes a sparse representation object tracking algorithm by taking the histogram of gradient feature to replace the generalized Haar feature. The algorithm uses the histogram of gradient feature as an original feature firstly, and gets the sparse representation of object feature subspace by using compressive sensing theory. In the subsequent frames, the naive Bayes classifier is used to search the target location and the classifier is online updated finally. As the histogram of gradient feature can represent the target more stably, this algorithm is more robust than original compressive tracking algorithm. Furthermore, the integral histogram is adapted to effectively reduce computational load when the gradient feature is computed. Experiments on different videos show that the tracking algorithm can reach the tracking rate of 10 frames per second in an experimental environment of Intel Core2 2.93 GHz, matlab R2010a, image size 320×240, and it achieves stable tracking in some special conditions as mentioned above.Keywords：object tracking;Histogram of gradient feature;Sparsity representation;compressive sensing- 49
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Published：2020-08-12 -
License Plate Recognition Based on Fractal and Hidden Markov Feature
Abstract：Because existing license plate recognition algorithm has lower efficiency in the binarization and character recognition, a license plate recognition algorithm based on fractal dimension and hidden Markov features was proposed. The algorithm is based on fractal dimension and hidden Markov features, and uses the joint classification of OC_SVM and MC_SVM to recognize license plates. In experiments, the fractal dimension was used complement the binarization of the license plate, the hidden Markov features were taken to extract character features and a multi-classifier was utilized to recognize the character. 800 Chinese character images, 800 English letter images and 1600 Arabic numeral images were recognized, obtained results show that the recognition rates of Chinese characters, English letters and Arabic numerals are 98%, 98.5% and 98.9%,respectively, the average recognition rate of license plates is more than 90.60%.It concludes that the method has higher efficiency, better accuracy and stronger robustness, and it can provide a guarantee for license plate recognition.Keywords：license plate recognition;binarization;Character Recognition;fractal dimension;Hidden Markov feature;joint classifier- 64
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Published：2020-08-12 -
Detection probability of infrared and visible image fusion system
Abstract：A method to calculate the target detection probability quantitatively for a infrared and visible image fusion system was proposed and a corresponding calculation model was established. First, the main factors affecting on the target detection probability were analyzed, and they were the spectral contrast of target and background, the characteristics of infrared and visible light detector, environmental illumination conditions, the integration of image quality, and the target size and distance. Then, five mathematical models on the effect factors mentioned above was constructed. On this basis, a calculation model for the detection probability based on infrared and visible image fusion system was completed. Finally, the experiments for two practical missions were performed. The first experiment show its results as follows: target detection probability of trees for a single detection system pvis is 0.294 8,pIR is 0.136 0, but the detection probability for the fusion detection system is 0.414 2, much higher than that of single detector, which verifies the validity of the calculation method of fusion system for target detection probability. It proves that the fusion image quality and the spectral characteristics of goal itself play important roles for target detection probability. Moreover, the experiment results of the model is accord with the human visual characteristics as well.Keywords：infrared image;visible image;image fusion;detection probability;Target detection- 58
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Published：2020-08-12 -
Computation of PID stabilizing region with stabilized margins
Abstract：On research of the stabilizing region of a PID controller,the control system is required a stabilized margin to compensate the uncertainty of plant modeling and the parameter deviation of PID controller. This paper defines four types of stability margins for the plant under PID controller to extend the conventional definition of stability margins (gain margin and phase margin). Based on the presences of Right Half Plane(RHP) poles or not, the closed-loop systems are classified into two categories and their necessary stabilized margins are stated. A method of constructing PID stabilizing regions by using the generalized Hermite-Biehler theorems is proposed for the PID controlled closed-loop system to meet the prescribed performance of stability margins. Then, two examples are employed to test the validity of the method proposed. Obtained results demonstrate that the PID stabilizing regions with stabilized margins can really be gotten by the proposed method for both cases.Keywords：PID controller;PID stabilizing region;gain margin;phase margin;generalized Hermite-Biehler theorem- 35
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Published：2020-08-12 -
Time to Voltage Converter Based on Time Amplifiers
Abstract：To overcome the shortcomings like temperature nonlinearity and long-dead time for measuring echo flight-time in traditional analogy interpolation method, a new time voltage converter based on time amplification technology was proposed. The circuit structure and influences of different configurations of capacitive parameters on the performance of the convertor were discussed in detail. A prototype circuit of the time voltage convertor using discrete components was designed and a test platform was constructed to test the performance of the convertor. The results show that the designed time voltage convertor can reduce measurement dead time and eliminate the influence caused by clock jitter and PVT (Process, Voltage and Temperature) parameter variations. In the valid input range, the differential and integral nonlinearity errors are less than 0.45 LSB and 0.6 LSB,respectively,which meets the needs of echo flight-time measurement for high-precision and real-time .Keywords：time-voltage converter;time amplification;parameter configuration;differential nonlinearity;integral nonlinearity.- 34
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Published：2020-08-12 -
Optimization time synchronization in cross-layer service for WSNs
Abstract：The current time synchronization algorithms for Wireless Sensor Networks(WSNs) are dependent on the collected time data strongly. Therefore, an optimization time synchronization technology for cross-layer service was presented to work out related issues. Firstly, frame header fragmentation in a MAC layer was used for the fragment and reassembly of packets. By zoning techniques,superframe structure of the MAC layer was adjusted,and then the hidden node problem was solved through the slot backoff algorithm.Then,a timestamp was added into the frame structure of the broadcast message to record the time data of received messages, and all received error data were filtered through clustering techniques. Also the synchronous clock drift was compensated. The simulation results indicate that the time synchronization accuracy is improved by 8 μs, the convergence time is reduced by 10% and the energy consumption is less than 150 mW compared with those of other traditional algorithms.These results prove that the technology ensures the accuracy,and simultaneously reduces the convergence time and the energy consumption of the network.Keywords：Wireless sensor networks;Time Synchronization;cross-lay service;MAC layer- 52
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Published：2020-08-12 -
Detection and recognition of cyclic coded targets
Abstract：On the requests of coded targets in the close-range photogrammetry for precision position and decode recognition, an algorithm to automatically detect and recognize the cyclic coded targets was proposed. Firstly, the canny edge detection was used to process images, not only the noises but also the non-coded target were filtered by means of calculating the centroids of closed contours and a series of criteria. Then the least square ellipse fitting was taken to locate the coded target, and each coded target contour could be segmented and filled when the fitting error was satisfied. Finally, a transformation method named Affine LOG Polar Coordinate (ALPC)that has the property of transforming local concentric ellipses into parallel straight lines was proposed to transform each coded target for decoding. Experimental results show that the algorithm presented in this paper can locate the coded targets to a sub-pixel level, and the average recognition accuracy rate can reach 98.8% when the angle between the camera optical axis and the normal of coded target is less than 60° . Furthermore, the recognition accuracy rate can still reach 90.2% when the angle is 70°, and the recognition accuracy rate can reach 96.46% under the complex background. In conclusion, the algorithm proposed can fully satisfy the precision and accuracy requirements of coded target location and recognition in the close-range photogrammetry.Keywords：close-range photogrammetry;Coded Target Detection;Coded Target Recognition;Canny Edge Detection;Affine LOG Polar Coodinate(ALPC) Method;Decode- 86
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Published：2020-08-12 -
Segmented gray scale modulation of LED display and optimal scan clock access
Abstract：构建了一种发光二极管（LED）显示屏灰度等级调制模型以实现其灰度调制并获取优选扫描时钟。根据脉宽调制的特点，将灰度调制过程分为基本灰度等级调制和扩充灰度等级调制来构建灰度等级的调制模型。通过分析模型各参数关系，提出一种优选扫描时钟的选取方法和扫描时钟富裕系数的概念，并在此基础上总结了LED显示屏显示控制优化途径。最后，通过硬件平台验证并实现了该灰度等级模型。实验结果表明：对于4扫的LED显示屏，选取最小响应脉宽小于等于40 ns的驱动芯片可使刷新率为300 Hz、移存长度为128个像素点、灰度等级为14 bit的优选扫描时钟为10 MHz，同时其亮度利用率达到90%，最大扫描时钟富裕系数达到3.5。采用该模型实现灰度等级调制，可以满足LED显示屏的显示要求，可应用于实际工程项目。Keywords：Light Emitting Diode(LED) display;control system;driving system;Display control;scanning;Gray modulation- 59
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Published：2020-08-12 -
Eye location based on adaptive image segmentation and curve blending
Abstract：Traditional projection algorithms for eye location have a bad adaptation to face edge, expression and illumination, and they are affected by eyebrows, bangs and eye wrinkles easily. Aiming at the above problems, an algorithm of eye location based on Adaptive Image Segmentation and Curve Blending (AISCB) was proposed. Firstly, the specialty of eye gray distribution was analyzed, and an adaptive image segmentation method was defined by using the direction selectivity of gradient operators and certain expansion elements to overcome the influence of edge and illumination. Then, according to the concept of hybrid integral projection and the characteristics of both eye gray changes and gray mean value, the adaptive weight projection curve blending method was used to enhance algorithm's robustness. Finally, the division of face region and the accurate location of eyes were realized through analyzing the characteristics of fused curves. The experiments on YaleB and JAFFE face data libraries show that AISCB algorithm has a good adaptation to complex illumination and face edges, and it is not sensitive to eyebrows, bangs and other head sections. The correct rate of mean location can reach 98.92% when the evaluation criterion is less than 0.25.Keywords：Eye location;image segmentation;curve fitting;gray projection- 73
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Published：2020-08-12 -
Application of improved SURF algorithm to feature matching
Abstract：A new improved method, Speed Up Robust Features(SURF) matching by image partition, is propoed, which is defined as Modified-SURF(M-SURF). The method uses the feature matching adopting an image integral based on SURF to speed up the computing speed, meanwhile,it takes the second-order feature descriptors derived by the second-order multi-scale gauge to improve the feature matching robustness. The paper firstly deduces the formula of the second-order multi-scale gauge. Then, it introduces the image partition algorithm to resolve the inconsistency between the computing speed and the precision of matching. With an experiment,it obtains the optimal parameters of image partition matching. At last, it weighs the quality of matching by the algorithm of the ratio of the shortest distance and shorter distance in Euclid space, and improves the matching precision by eliminating the false matching dot with the LMedS. The result shows that the computing speed of M-SURF has raised more than 28％ and the matching precision of M-SURF increases by 3％ as comparing with those of SURF and Scale Invariance Feature Transfer(SIFT) by matching tests for several series of images. This algorithm can achieve a better matching of feature points and has a practical value.Keywords：stereo matching;Euclid space;feature descriptor;feature matching;scale space- 64
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Published：2020-08-12 -
Infrared image enhancement based on generalized linear operation and bilateral filter
Abstract：As classical infrared image enhancement methods based on Unsharp Masking（UM） suffer from terrible noise interference and halo effect, a new approach based on generalized linear operation and Bilateral Filtering (BF) was proposed here. Firstly, the elemental part of the image was extracted by using the BF and then operation models based on generalized linear operation were designed for the following enhancement. In the new operation scheme, the image details were nonlinearly segmented, denoised and amplified and the dynamic range of the elemental part was compressed while the detailed part was enhanced adaptively. Finally, the enhanced image was obtained by adding the processed elemental and detailed parts together nonlinearly. Furthermore, an assessment method for image quality was presented. Unlike the classical metric which only considers the average contrast enhancement, the modified one involves both local and general average contrast enhancements. Both the comparison experiments and measurement index indicate that the proposed method can compress the dynamic range of infrared images, amplify their details, and suppress the noise interference and halo effect. This technique has a significant contribution to the posterior image processing of thermal infrared cameras.Keywords：infrared image;image enhancement;generalized linear operation;bilateral filter- 57
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Published：2020-08-12 -
Level Coarse Brain Vessel Segmentation Based on Global LBF Model
Abstract：To solve the problem that human brain vessels are difficult to be segmented, a level coarse brain vessel segmentation based on the global Local Binary Fitting(LBF) model was presented in the paper. First, the Directional Weight Median(DWM） filtering and the anisotropic diffusion model were used to reduce the noise and to enhance the vessel edges of brain images. Then, the Local Intensity Gradient Maximum(LIGM) algorithm was implemented based on a multi-scale space. The information of intensity and gradient was used to get the vessel candidate set and remove the influence of gray matter in the brain. At the same time, the improved global LBF level set model was used to segment the Maximum Intensity Projection(MIP) image. The vessel voxels were extracted with the conformation information. The results of these two steps were fused together to get the minimal covering set of the brain vessel. The experimental results show that all most the vessel voxels directly segmented by the double Gauss model can be reserved and most uncorrelated voxels can be removed. This research is based on the Time of Flight Magnetic Resonance Angiography(TOF MRA) and it is easy to expand to the similar system.Keywords：3D reconstruction of brain vessel;level segmentation;Local Intensity Gradient Maximmu(LIGM) algorithm;Local Binary Fitting(LBF) model;image fusion- 36
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Published：2020-08-12 -
Variable universe fuzzy control of train lateral semi-active suspension system
Abstract：A variable universe fuzzy controller was designed for the lateral semi-active suspension system of a train. The convergence condition of variable universe fuzzy was given more widely, which was confirmed to be suitable for the suspension system of train. Then, the lateral model of a 17-DOF vehicle was built by Simulink software based on the theory of dynamics. Finally, a potentially-inherited variable universe fuzzy controller was designed by taking the lateral acceleration and velocity of the suspension as the input variables of controller and the damper current as the output variable of controller. A simulation experiment was carried out at the same time, the max value, root mean square and power spectrum density function's max value of the lateral acceleration were calculated, and the results obtained from the variable universe fuzzy controller, traditional controller and the passive suspension were compared. The simulation results show that those data mentioned above have been decreased, which means that the control results by variable universe fuzzy control are better than those of conventional fuzzy control and passive suspension.Keywords：train;lateral semi-active suspension;Passive suspension;Variable universe fuzzy control;root mean square of acceleration;power spectrum density function- 31
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Published：2020-08-12 -
Path planning based on ant colony and genetic fusion algorithm for communication supporting spacecraft
Abstract：To implement the orbit maneuvering of a communication supporting spacecraft in a large area, the path planning of the communication supporting spacecraft was proposed based on the fusion of ant colony and genetic algorithms. Firstly, the orbit dynamic model of spacecraft was established, and the fusion scheme of the genetic and ant colony algorithms was studied. On the basis of the fast convergence of genetic algorithm and the higher efficiency of colony algorithm, the genetic and ant colony algorithms were redesigned respectively under a fusion framework, and the operation process was presented. Finally, the path planning was simulated. The simulation results show that the fusion algorithm can reach the stabilization after 100 iterations, and the average safety path length is 4.055 3×104 m. These results prove that the convergence speed of maneuvering orbit planning based on genetic and ant colony fusion is fast, and the flight path to a fault of spacecraft can be obtained in a shorter time, which raises the efficiency of orbit planning remarkably. Key words: path planning; genetic algorithm; ant colony algorithm; orbital maneuvering; communication supporting spacecraftKeywords：path planning;genetic algorithm;ant colony algorithm;Orbital maneuvering;communication security spacecraft- 68
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Published：2020-08-12
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