Chinese Version Light学术出版中心
Latest Issue
Issue 12 ， 2009
-
Large accept angle、lateral splitting sunlight、non-imaging concentrator
Abstract：Although the traditional concentrators can reduce the amount of solar cell, they need high accurately tracking system. On the other hand, the spectrum of solar is very wide, while the absorbing spectrum of photovoltaic is narrow. So a lot of energy will be lost. In order to overcome these drawbacks, the later non-imaging optical system was studied. The concentrators with large accept angle and splitting characteristic was designed. This kind of concentrators can form high efficiency, non-tracing and portable PV modules, combined with solar cell. They can used as power of some special devices such as portable computer, imaging and measuring system, and so on.Keywords：Concentrator Photovoltaics;non-imaging condenser;edge ray principle- 43
- |
- 9
- |
- 6
Published：2020-08-13 -
Diaphragm based miniature F-P cavity fiber optic pressure sensor
Abstract：Miniature fiber optic pressure sensor based on Fabry-Perot (F-P) interferometric principle is described. A piece of hollow fiber with 175 μm out diameter is fused directly onto a fiber tip to form an air gap for the F-P cavity. The essential pressure sensing element is a thin diaphragm which is fused onto the other end of the hollow fiber. First, an entire quartz structure miniature fiber optic pressure sensor is fabricated by cleaving, fused splicing and etching. The pressure response of the sensor has been tested, showing a sensitivity of 41.09nm/MPa in the full pressure scale of 0-3.1MPa. The system resolution of 681Pa has been reached for the pressure measurement. The temperature sensitivity of the sensor has also been tested under atmospheric pressure, exhibiting a weak temperature dependence of 1.07KPa/℃ in the test temperature range from 20 to140℃. Since it is hard to further decrease the thickness of the quartzose diaphragm，A polymer（PSQ） diaphragm is used instead to increase the sensitivity of the sensor. The pressure response of the PSQ diaphragm based sensor has also been tested under room temperature, showing a sensitivity of 1 886.85nm/MPa, in the full pressure scale of 0.1-2.1MPa, with a system resolution of 53Pa.- 86
- |
- 11
- |
- 14
Published：2020-08-13 -
Optical Measuring Method and Apparatus Study On Hemoglobin Concentration in Whole Blood
Abstract：Hemoglobin concentration measurement is one of the most widely used Clinic analysis project, It is necessary to research a hemoglobin measurement apparatus applied to blood collection and healthy care domain with the advantage of no contaminate, portable and accurate. Secondary absorb measurement mechanism is designed based on the absorb spectrum chart of Azide methemoglobin, and the concentration equation is derived, an instrument based on above method which could detect hemoglobin within 30 to 60 seconds was developed. Testing principle, measuring mechanism, control system and parameters calibration are all introduced in the paper in detail. As the clinical trials show: compared with cyaniding methemoglobin (Fe3+), the pertinence of the result of the measurement can be 0.9836, the veracity can be 96.32%. Because of the portability and the characteristic of quick-testing online, the instrument can be widely used in moving blood collecting stations, judging the function of the athletes and family health care, and it is important to them.Keywords：hemoglobin;concentration;spectrum;measurement;apparatus- 39
- |
- 7
- |
- 1
Published：2020-08-13 -
Accuracy and optimization of control matrix in liquid crystal adaptive optical system
Abstract：In order to improve the correction accuracy of liquid crystal adaptive optical system(LCAOS), a new method of measuring the response matrix for the purpose of getting accurate control matrix by changing the modulated wavelength is proposed. First, the actual phase modulation lines of first 35 Zernike modes are measured under a series of modulated wavelengths. Then, the phase modulation lines of each modulated wavelength referenced to the origin point are calculated, and one of the phase modulation line can be found whose slope is closest to the actual phase modulation line and whose corresponding modulated wavelength is the one that must be applied on the liquid crystal wavefront corrector when measuring response matrix. With this method, 35 modulated wavelengths can be gained corresponding to 35 Zernike modes. Finally, the normalization of each column of response matrix by modulated wavelength is conducted, and the accurate control matrix is obtained. Experimental results indicate that，with the new method, the correction accuracy of the system improved from 73% to 95%. The residual compensated error is only 1/5 of that with the normal method, and the coefficient is not related to the maximum compensated phase. It is shown that the new method greatly improves the correction accuracy of the LCAOS.- 36
- |
- 10
- |
- 3
Published：2020-08-13 -
A miniaturized high-power light-emitting diode- induced fluorescence detector for microchips analysis
Abstract：A novel miniaturized fluorescence detector which using a blue high-power light-emitting diode(LED) as an excitation light source for microfluidic chips analysis was developed and evaluated. LED was driven by the current between source and drain, which was invariable when MOSFET was worked in saturated zone. LED generated stable light with the constant current. Special optical structure was designed and manufactured to focalize the divergent light which was emitted by LED into linear beam of light. The size of the beam of light was about 3.5mm×0.3mm. This linear beam of light could easily calibrate itself to microchannel of microfluidic chips. Then it could reduce complexity of detector and miniaturize the detector. And the bulk of the optical system was about 9.5cm×4cm×17cm. NBD C6-ceramide and high density lipoprotein were used to evaluate performance of the detector. The results indicated that LED excitation light source was stable, the detector had good reproducibility and the detector could be used in the microchips capillary electrophoresis analysis. The LED-induced fluorescence detector was miniaturized.Keywords：light-emitting diode;fluorescence detection;linear beam of light;miniaturization;microfluidic chips analysis- 35
- |
- 6
- |
- 6
Published：2020-08-13 -
Application of Phase Retrieval Technology in Evaluation of Optical Imaging System
Abstract：It is difficult to evaluate the large and multi-wave band optical imaging system performance in general testing ways. The wave front of optical system is the one of import parameters which represents imaging quality. The fundamental theories of information optics and phase retrieval have been applied. The point image of optical imaging system ( intensity point separate function ) was analyzed and computed. The wave font of optical system has been retrieved by the Fourier transform and an iterative approach. The related theory is discussed and algorithm model is presented. The compute software of phase retrieval has been made. The validity of compute software is proved by the computer imitation. The phase retrieval error is estimated and is less than 5% . The way which would reduce the phase retrieval error has been suggested when the technology is applied. Through detecting and analyzing the PSF imaging of optical system in the lab, the experimental results indicate that the computer software of phase retrieval is efficacious. So it is shown that the novel method is suited to retrieve wave front of optical systems.Keywords：theory of information optics;Fourier transform;intensity point separate function;phase retrieval;iterative approach;wavefront- 55
- |
- 8
- |
- 6
Published：2020-08-13 -
Propagation of constant-axial-intensity SGB beams in turbulent atmosphere
Abstract：Ideal non-diffracting beams require an infinite amount of energy for generation and therefore not physically realizable. In experiments only their approximations as the pseudo-nondiffracting beam can be obtained. Super-Gaussian-Bessel (SGB) beams as pseudo-nondiffracting beam having finite energy are physically realizable. The constant-axial-intensity SGB beams have good non-diffracting characteristics over a certain propagation distance, their central region of transverse intensity distribution keep their intensity and size constant. In this paper, it was proved that constant-axial-intensity SGB beams still maintain the non-diffracting characteristics in the range of medium intensity of atmospheric turbulence by means of numeric simulation. The propagation of constant-axial-intensity SGB beams are hardly affected by atmospheric turbulenceKeywords：non-diffracting beams;Super-Gaussian-Bessel (SGB) beams;turbulent atmosphere;the extended Huygens-Fresnel principle- 42
- |
- 7
- |
- 2
Published：2020-08-13 -
Study on Total Dose Effects of TDI-CCD and Corresponding Test Methods
Abstract：A space camera uses TDI-CCD devices as its imaging sensor. In order to evaluate the influence which is caused by space radiation environment on TDI-CCD, starting with the circuit structure of the devices, the total dose effects (TDEs) and the primary capability index of the devices are analyzed. Then the test equipment and the test methods of the devices for 60Co γ irradiation experiment are studied. In irradiation experiment, the photoelectric response capability and the contrast transfer function (CTF) are tested. By analyzing the experiment results, the following aspects have been concluded that the change of the relative responsibility, dark signal, dynamic range, SNR and CTF of TDI-CCD are below 5% when the irradiation dose is 20 kRad(Si). The TDI-CCD can satisfy the use of the space camera.Keywords：TDI-CCD;Total dose effects(TDEs);Test methods;photoelectric response capability;Contrast transfer function(CTF)- 39
- |
- 9
- |
- 5
Published：2020-08-13 -
Temperature Field Characteristic of Laser Rod with Anisotropic Thermal Conductivity by Diode-laser End-pumped
Abstract：In order to solve thermal effect of thermal conductive anisotropic laser medium by LD end-pumped, a thermal model of Nd:YVO4 crystal with adiabatic end faces and cooling circumference was established. Considering that the Nd:YVO4 crystal is a thermal conductive anisotropic material and the output beam of LD coupled by fiber has the characteristic of super-Gaussian distribution, a general analytical temperature field expression of thermal conductive anisotropic laser medium end-pumped by the super-Gaussian beam was obtained by the methods of eigen-function and constant variation. Meanwhile, the temperature field influences of the super-Gaussian beam with different orders, spot radius and powers on the Nd:YVO4 crystal were quantitatively analyzed. The new method for solving heat conductive equation of anisotropic medium has the specialties of smaller calculation amount and higher accuracy. The results show that when the output power of LD is 10W, the transmission efficiency of optical focusing coupler is 82%，the end-face of neodymium doped yttrium orthovanadate crystal with 0.5% neodymium ion doped mass fraction end-pumped by the forth order super-Gaussian beam get a maximum temperature rise of 528.95C. The results can be applied to the design of thermally stabilized cavity of all-solid-state laser with thermal conductive anisotropic laser medium by LD end-pumped, and will play theoretically instructive effects at improving the performance of lasers.Keywords：solid-state laser;heat conductive equation of anisotropic medium;Nd:YVO4 crystal;super-Gaussian beam;temperature distribution- 34
- |
- 5
- |
- 3
Published：2020-08-13 -
A novel universal tracking error correction model for photoelectric theodolites
Abstract：The existing tracking error correction formula is derived from coordinate transformation compared with spherical trigonometry, which suitable conditions are proposed. A new tracking error correction model is deduced without its optical axis paralleling the collimating axis, and the coordinates of camera projection center in measuring coordinate system are calculated without regard to coincidence between the optical center and the theodolite rotation center. The approach breaks through the limitation of existing model, and which is suitable for multi-sensor imaging system theodoliteKeywords：photoelectric theodolite;tracking error;correction model;coordinate transformation- 58
- |
- 7
- |
- 5
Published：2020-08-13 -
Influence of Different Base Pressure on SiC/Mg EUV Multilayer Mirror’s Performance
Abstract：To improve the optical performance of EUV multilayer mirror working at 30.4nm wavelength, a series of SiC/Mg multilayer mirrors were fabricated with DC magnetron sputtering at different base pressure before depositing. The measured results of x-ray diffraction (XRD) shows that the multilayers fabricated at different base pressure differ from each other. The reflectivities of these multilayer mirrors were measured by synchrotron radiation light. The measured reflectivity of the multilayer prepared at the base pressure of 6.0E-5Pa is as high as 43%, but, for the multilayer prepared at the base pressure of 5.0E-4Pa, the reflectivity in only 30%. By analyzing the reflectance curve and scattering curve measured in the synchrotron radiation, the decrease of reflectivity of SiC/Mg multilayer was relative to the content of magnesium oxide in the layers.Keywords：Extreme ultraviolet optics;base pressure;Multilayer;Reflectance;magnetron sputtering- 43
- |
- 12
- |
- 5
Published：2020-08-13 -
Surface Modification Influence of SiC Mirrors on Signal Noise Ratio of TMC Optical System
Abstract：Signal noise ratio of TMC optical system is significantly influenced by the intrinsic defects of SiC (Silicon Carbide) mirror. After applying surface modification technique, Wyko profilometer indicates the roughness of a SiC mirror is reduced from 10.42nm (Ra) to 0.95nm (Ra). Then silver coating and enhanced coating have been coated on primary mirror, secondary mirror, tertiary mirror and fold mirror. Reflectivity is higher than 98% of each mirror between 0.5μm-0.8μm wavelength. Calculation results indicate that signal noise ratio has improved 5% after surface modification.Keywords：surface modification;SiC mirror;Signal noise ratio;TMC- 41
- |
- 6
- |
- 4
Published：2020-08-13 -
Research on space intersection angle measurement for three-line mapping camera in thermal-optical test
Abstract：Making research on space intersection angle measurement system for three-line mapping camera in thermal-optical test. Designing the test system and making research on the test method for intersection angle. The method for quantitative measurement is put forward. The requirement of thermovacuum test equipment and optical measurement field is interpreted in detail, especially the collimator and special reticle. At the same time, the needed preparation is issued before thermal-optical test. The measurement software system is made with Labview software. The three–line mapping camera intersection angle is tested with quantitative measurement. The results show that the change of intersection angle is below when the temperature operating condition is changed. In a word, quantitative measurement method can get the accurate change of intersection angle. The measurement data can benefit to the analysis on earth.Keywords：mapping camera;space intersection angle;gray value;image element- 38
- |
- 6
- |
- 2
Published：2020-08-13 -
Post Launch Site Calibration of the Visible and Near-Infrared Channels of FY-3A Visible and Infrared Radiometer in 2008
Abstract：After the launching of FY-3A in May, 2008, calibrating the payload in orbit turned important. The first post launch site calibration experiment of FY-3A visible and infrared radiometer (VIRR) was held in 2008’s site calibration experiment in Dunhuang remote satellite radiometric calibration site, Gansu province, China. Because of the bidirectional reflectance anisotropies of the land surface, the precision of the visible and near-infrared channels’ post launch site calibration was disturbed obviously. Getting a correct directional reflectance through the observing view angle and at the right time payload passing over is an important work. The vertical reflectance of 11 synchronization points in Dunhuang site was measured by ASD FR spectral meter and standard reference board during the period 1 hour fore-and-aft the satellite passing over. With a new reflectance correction method the calibration precision was improved: the directional reflectance at the moment the platform passing by was calculated by the algorithm for modeling bidirectional reflectance anisotropies of the land surface (AMBRALS) invented by TERRA/MODIS land group and multiplied by the correction coefficients. The correction coefficients were gotten by dividing each vertical reflectance measured by ASD of 11 synchronization points by the one calculated by AMBRALS and averaging them. Results showed that in some bands, the difference between measured one and calculated one reached about 10%. It showed the efficiency and importance of the new correction method. The aerosol optical depth (AOD) was measured by 10 bands sun photometer CE318 placed near the synchronization region. The AOD of 550nm is calculated according to Junge distribution. The layer water content was calculated by the sounding data measured by Dunhuang national climatic station (No. 52418). The vapor pressure was calculated by the Wexler’s formulas. The apparent reflectance was calculated by the use of 6S model and was corrected by the sun zenith cosine and sun-earth distance. Totally 3 days’ (2008/09/06, 2008/09/10, 2008/09/11) calibration slopes and intercepts of FY-3A/VIRR were gotten. The relative standard deviation(RSD) of them was below 2.6%. In order to validating the post launch calibration’s veracity, 23 targets’ apparent reflectances were compared by FY-3A/VIRR and TERRA/MODIS, they matched well. The results showed the stability and veracity of the calibration arithmetic except for the water vapor absorption bands. In vapor absorption bands, the 3 days’ slopes varied obviously. Compared to the pre launch calibration, the post launch calibration changed about 7.73%~21.52% in different bands, showed the imperative of post launch calibration right after the satellite launching. Now the pre launch calibration slopes and intercepts had been substituted by the post launch ones.Keywords：space optics;Post Launch Site Calibration;AMBRALS;FY-3A/VIRR- 43
- |
- 10
- |
- 9
Published：2020-08-13 -
Aberrations of plane-symmetric optical systems(Part I-Extension of aberration theory)
Abstract：The aberration theory of plane-symmetric grating systems are extended to be applicable to the aberration analysis of refractive plane-symmetric systems. As a result, the aberrations for plane-symmetric reflective and refractive optical systems are expressed in a unified set of formulae. They can be validated by the analytical formulae of ray-tracing spot diagram based on the Fermat’s principle. It is described how to use our wave-aberration coefficients to derive the Seidel aberration in the case of axially symmetric refractive systems. Moreover, the modification of wave and ray aberrations is studied when the entrance pupil is displaced from the optical surface.Keywords：XUV optics;wave aberration;plane-symmetric optical system;Seidel aberration- 33
- |
- 9
- |
- 2
Published：2020-08-13 -
Group design of shutter and focus neutron guide of neutron reflectomrter
Abstract：To improve the intensity of the front beam of neutron horizontal geometry scattering reflectometer,we try to find out the optimized combination of beam shutter and focus neutron guide by numercal calculation method. According to the distinctness of entrance and exit section of channel and supermirror index, the combinatorial design model is divided into different groups. Select a optimized combination design model combine with the horizontal scattering geometry neutron reflectometer after calculation..The result shows that the optimized design of focusing neutron guide is that only focus on the horizontal walls of the guide with supermirror index 3 and supermirror index of the vertical wall is 2 with channel width of 10mm,and the supermirror index of shutter is 2. After analysis of many groups of combinations,we got the optimized parameters of the shutter and the focus guide and set up a theoretical foundation for the conceptual design of the neutron reflectometer.Keywords：Shutter;Focus neutron guide;Supermirror index;Combination optimize- 45
- |
- 6
- |
- 1
Published：2020-08-13 -
Global calibration of line-structured-light measurement system using multi-CCD based on an LCD target
Abstract：In order to realize the global calibration in line-structured-light measurement system using multiple CCDs, an approach to calibrate multiple CCDs based on an LCD target is investigated. First, a LCD target is arranged at the position of light section, and characteristic points are shown on the target one by one, which are captured by cameras at the same time. Then the relationship between the target coordinate and the image coordinate is established in a non-linear model through synchronizing pulses. Finally, the model is optimized by the shape restraints of a calibrating part to get the mapping between the light sectioning plane and the image plane. Measurements of free surface show that the data from different CCDs are well spliced in the light sectioning plane, and measurements of the calibrating part are accurate with an error less than 0.2mm in distance and 0.2°in angle. This method is easy to use, and has been successfully applied in a multi-CCD 3D measurement system.Keywords：Multi-CCD;Line-structured-light;LCD target;global calibration;optimization- 23
- |
- 5
- |
- 2
Published：2020-08-13 -
Development of a New High Integration Drive Modular for Scanning Mirror
Abstract：A new kind of high integration drive modular for scanning mirror was developed. The modular can be used for a dynamical system of scanning mirror of space optics remote sensor. Based on the idea of integration of optics, mechanics and electronics, a right stepper motor, a harmonic reducer and 16 bit encoder were made up of the compact drive modular. Then the shafting precision, position precision and speed precision of the modular were analyzed and tested. According to the testing result, the shafting radial error was less than 3μm; the shafting end error was less than 1μm; position precision was less than 40"; the relative speed precision was 19% when the speed was 0.1°/s and the relative speed precision was 6.8% when the speed was 5°/s. The testing result proved that the drive modular was light, powerful, precise and satisfied for the scanning mirror.Keywords：stepper motor;harmonic transmission;drive modular;precision analysis- 33
- |
- 4
- |
- 5
Published：2020-08-13 -
Mobile Miniature Self-reconfigurable Robot Based on Embedded Vision
Abstract：A novel mobile self-reconfigurable robot is presented. This robot consists of several independent units. Each unit is composed of modular components including ultrasonic sensor, camera, communication, computation, and mobility parts, and is capable of simple self-reconfiguring to enhance its mobility by expanding itself. Several units can link into a train or other shapes autonomously via camera and other sensors to be a united whole robot for obstacle clearing, and disjoin to be separate units under control after missions. To achieve small overall size, compact mechanical structures are adopted in modular components designing, an embedded image processing module based on CMOS digital camera is designed for self-reconfiguration, and a miniature ARM & FPGA-based embedded controller is developed for minimal power consumption and efficient global control. Fully functional unit has been tested, and docking experiment between two units has also been implemented.Keywords：self-reconfigurable robot;modularity;mobility;embedded vision;docking- 31
- |
- 6
- |
- 2
Published：2020-08-13 -
Modal truncation method to vibration analysis of the stator of ultrasonic motor
Abstract：Base on the finite element analysis on the vibration mode of the stator of ultrasonic motor, modal truncation method is used to reduce the dimension of finite element model. The modal parameters are automatically obtained from the results by means of APDL (Ansys Parametric Design Language). The dynamic properties of the structure are simulated and tested, and the results are consistent. It is showed that the reduced model can accurately describe the pertinent dynamics of original system.Keywords：ultrasonic motor;finite element;modal truncation method;equivalent circuit model- 39
- |
- 6
- |
- 4
Published：2020-08-13 -
Auto-focusing technology for the theodolite based on the largest gray’s gradient
Abstract：An auto-focusing method used for the theodolite is proposed in this paper, for the purpose of accurate auto-focusing, the system makes use of CMOS as image sensor, the computer for data processing and controlling driving circuit for the camera’s lens position adjustment. Firstly the least focusing range including principal object is controlled by window selection, this measure not only reduces the load for data processing, but also reduces influence from complex background and enhances legitimacy of auto-focusing; secondly we calculate the edge’s gradients in all possible directions, then compare all of the possible edge’s gradients; at last the system choose the largest gradient as the criterion of auto-focusing system. The experiment result demonstrates that the system has the characteristics such as good unbiased Characteristic, strong single peak feature, high sensitivity, good stability and so on; the system’s measuring precision ranging from 0.01mm to 0.02mm meets with the first focus-depth requirements of the theodolite; and it has the advantage of real-time adjusting and a better foreground of application and value of popularization.Keywords：auto-focus;focusing evaluation function;gray gradient;focus windows- 51
- |
- 9
- |
- 18
Published：2020-08-13 -
Uniformity of Four Shaft Ball Lapping Machine
Abstract：A mechanical model was developed for the four shaft ball lapping machine. The velocity vector of relative machining sphere at one point of the lapping cup was obtained by analyzing the relation between the four lapping cup and machining sphere. The analyzing model for the lapping machine to realize uniform lapping on a ball surface was set up based on Preston equation. And the Matlab software was used to conduct the simulation analysis on unit time deduction.Lapping uniformity was evaluated using variance. When cup turning and reversing is 90°out of phase, the better variance was obtained. In order to obtain lapping uniformity, running direction of four cup must changed.Keywords：lapping;four shaft;uniformity;simulation- 35
- |
- 4
- |
- 4
Published：2020-08-13 -
Global calibration of the visual inspection system based on universal robot
Abstract：An on-line and flexible visual inspection system for car body-in-white (BIW) based on universal robot and two practical global calibration methods were described. A laser tracker and a measuring arm were used in complexity field environment. The method based on measuring posture realized the coordinate transformation between the sensors coordinates to the system reference coordinate by combining the sensors coordinates and the target coordinates through mechanical constraint. The method based on robot kinematics realized global calibration at arbitrary posture in the presence of robot forward kinematics model, base coordinate frame and hand-eye calibration which was independent of kinematics accuracy. Experimental results show that the standard deviations of repeatability for the measurement equipments and the system are 0.07mm and 0.13mm respectively, which indicates that both of the methods can meet the requirement of monitoring the manufacture dimension changes of BIW. At the same time, the coordinate measuring error of the system are ±0.2mm and ±0.8mm for the two methods respectively.Keywords：universal robot;Global calibration;laser tracker;measuring arm;kinematics model- 23
- |
- 4
- |
- 14
Published：2020-08-13 -
An Improved Calibration Method Applied on Magnetic Compass Deviation
Abstract：As a kind of navigation equipment, magnetic compass was widely applied in the navigation systems of flight vehicles, but it was always disturbed by ferromagnetic material to produce the magnetic deviation. The traditional magnetic compass deviation calibration generally adapted the least squares ellipse fitting calibration algorithm, but the coefficient matrix of this algorithm may be singular which caused the algorithm unstable question. By analyzing the singularity of the coefficient matrix, an improved least squares ellipse fitting calibration algorithm was proposed to solve the unstable question of conventional algorithm. Simultaneously this algorithm transformed six dimensional eigenvector's solution to the three dimensional eigenvector's solution, reduced the computation load while keeping the precise. The experimental results shown the rapidity and validity of this algorithm and the magnetic compass precision improved from 0.8° to 0.4°, meeting the requirements of the navigation system after calibration.Keywords：magnetic compass;compass deviation;calibration;the least squares method;ellipse fitting- 63
- |
- 6
- |
- 10
Published：2020-08-13 -
A new method of chatter suppression for precision hole boring based on variable structural stiffness
Abstract：The chatter always occurs in precision hole boring process, which is one of the main abnormal cutting conditions that influences the quality of workpicece. To solve this problem, firstly, the dynamic model of regenerative chatter is established, which is the main type chatter in boring process. Then, the chatter suppression mechanisms of variable speed cutting method and variable structural stiffness method were analyzed. Through comparing, it can be seen that the chatter suppression mechanism of variable speed cutting method is similar to variable structural stiffness method, but the variable structural method is much more suitable for deep hole precision machining. Secondly, the magnetorheological (MR) intelligent boring bar was developed for application of variable structural stiffness method. The dynamic characteristics of MR intelligent boring bar can be adjusted by MR fluid, whose stiffness and damping parameter can be controlled by applied magnetic field. Finally, the experimental setup of MR intelligent boring bar was built on the CA6140 type lathe. A series of experiments were carried out, and the results show that the method can suppress chatter efficiently and surface quality of workpiece can be improved significantly, whose roughness decreased from10μm to 1.5μm.Keywords：precision hole boring;chatter suppression;intelligent boring bar;MR fluid- 46
- |
- 6
- |
- 2
Published：2020-08-13 -
Study of dynamics Simulations and Experiments for Laser Cutting Head Asway Mechanism
Abstract：This paper briefly introduces laser cutting head asway mechanism of fracture splitting notch processing machine, and has achieved a series of dynamics simulations towards it, based on the simulation results, rational hydraulic parameters(optimum hydraulic pressure is 2.5Mpa, throttle valve’s discharge coefficient is 0.2) are determined, physical cutting tests are also carried out, which indicates that asway mechanism works with stability, reliability and good cutting effect under the condition with appropriate cutting processing parameters. Meanwhile, this paper introduces servo electromotor driven asway mechanism, and has accomplished kinematics simulations towards the improved asway mechanism, the simulation results show that the improved asway mechanism works faster, asway angle is more accurate, and adjustment of asway angle is more convenient, which provides reliable theoretic basis for optimizing structure of the laser cutting fracture splitting notch machine.Keywords：Fracture splitting con-rod;Asway mechanism;Dynamics Simulation;ADAMS- 42
- |
- 7
- |
- 3
Published：2020-08-13 -
Research on High-Aspect-Ratio Micro and Small Hole Rapid EDM System
Abstract：Electrical discharge machining (EDM) with its advantages of small working force, good controllability, etc., has become more and more widely used in the field of micro and small hole manufacturing, however, for high-aspect-ratio micro and small hole machining, there are still some technical difficulties such as slow cooling, poor debris flushing, high tool wear and difficult to monitor and control, etc. With analyzing the mechanics and characteristics of EDM, a machine for rapidly EDM micro and small holes is designed and developed. The machine is vertically laid out, applying a rotary-vibrate mechanism with tool rotating and workpiece vibrating for the purpose of rapid cooling and debris flushing in the working process; it adopts industrial PC (IPC) with PCI card and PMAC card plugged to make data acquisition and motion control work well together. In order to solve the problem that discharge states are difficult to detect due to severely distorting sparking signals and unstable sparking states in EDM, a successive mapping detection method of discharge states based on two-stage fuzzy logic is proposed and a double-closed-loop control system is designed as well to achieve rapid response and precise control of the working process. Experiments show that this machine is suitable for rapidly manufacturing high-aspect-ratio micro and small holes and is of stable performance and high reliability.Keywords：electrical discharge machine (EDM);high-aspect-ratio micro and small hole;discharge states acquisition;working process control- 39
- |
- 7
- |
- 3
Published：2020-08-13 -
Method of IR sequence image generation for point target in deep space based on STK
Abstract：To acquire and real time process Space target information for Space-based detection systems is a challenging problem. The simulation for space-based detection systems are much more concerned in recently years. Dynamic IR image sequences generation of space target is one of the key technology. In the previous method, target temperature model is calculated by node network technique, it is high precision but consume computation ,which is not necessary for point target image generation. Because the space target is very long distance from the satellite-based sensors, and the size of target is much smaller than the sensor's spatial resolution. Otherwise, the kinetic error of vehicles , the measuring error of sensors and electronic noise of PFA are not concluded in them. So, the generated images by using the previous method could not assure the validity of the simulation for space-based detection systems. In this paper, A new simulation method of IR sequence image generation for point target in deep space background based on STK and MATLAB is presented. A simple isothermal model is used to calculate the temperature of the space targets, and A model of celestial background based on MSX (Midcourse Space Experiment) IR stellar catalog is presented, Conversion model between the Irradiance of target/background and the image gray is established by calculating the electron numbers that received by the detectors. Disturbance error of satellite, measuring error of sensors and electronics noise of FPA are modeled in the simulation. it makes the generated image almost reflecting the real world. At anytime, any viewpoint and any FOV's IR sequential images from which waveband 4 to 26μm can be simulated using our method. At last of the paper, an IR image sequences of some point target are implemented. The image generation technique that presented in this paper has three merits than the previous method. The first, it is computation efficiency as the reduced target temperature model. Second, the celestial background model that presented extends the LRS stellar catalog included 5425 to the MSX stellar catalog of 177886, and the smaller FOV of sensor can be simulated. which extends the field of application of the simulation for space-based system. the third, the more complete model than previous methods is presented, included the Disturbance error of satellite, measuring error of sensors and electronics noise of FPA. and the simulated images can almost reflect the real world.Keywords：IR sequence image generation;space target;deep space background;IR stellar catalog- 61
- |
- 9
- |
- 3
Published：2020-08-13 -
A new cross-hexagon search algorithm for fast block-matching motion estimation
Abstract：In fast block-matching motion estimation, search patterns have a large impact on searching speed and searching quality. Based on the motion vectors distribution characteristics of real world video sequences, we propose a new cross-hexagon search algorithm (NHEXS): First, a pre-search is performed by using the small cross search pattern to find the Minimum Block Distortion (MBD) point; Second, the MBD point found in first step is used as the center to construct the big cross search pattern to find the new MBD point; Third, the MBD point found in second step is used as the center to construct the hexagon search pattern: big hexagon search is employed firstly, if the MBD point is at the center, then small hexagon search is performed and the found MBD point is the final motion vector; otherwise, the big hexagon search is continued. NHEXS employs halfway stop technique to achieve significant speedup on sequences with stationary and quasi-stationary blocks. NHEXS employs Modified Partial Distortion Criterion (MPDC) which results in less computational complexity with similar distortion. Experimental results indicate that the improvements of NHEXS over Hexagon Search (HEXS) and New Cross Diamond Search (NCDS) can save 32% and 16% of searching points while keep similar PSNR, and NHEXS provides faster searching speed and smaller distortion than other popular fast block-matching motion estimation algorithms.Keywords：motion estimation;block-matching;cross-hexagon search;modified partial distortion criterion- 67
- |
- 6
- |
- 5
Published：2020-08-13 -
Solution of fast failure detection based on BFD for OBS links
Abstract：Objective: Optical burst switching (OBS) network is a promising solution for realizing future all-optical internet. However, common links failure detection mechanisms are hardly used for OBS networks due to the special one-way resource reservation mechanism in OBS. Hence, it is necessary for us to design the suitable links failure detection solution which meets the need of OBS data transmission. Method: The bidirectional forwarding detection (BFD) protocol is adopted in the OBS detection mechanism. Moreover, BFD can adjust both the transmitting period and detection time according to the practical requirements of OBS networks in order to meet the demand of fast failure detection. In the simulation part, the NSFNET is chosen as the simulation network and both OBS traffic generator and node failure generator are realized. Moreover, the performances of links failure detection for BFD are simulated under the single path scenario and network scenario. Result: Simulation results show that the average packets drop rate is lower than 0.001 under the single path scenario. While under the network scenario, the average packets drop rate is nearly 0.1 owing to the restrictions of OBS networks such as resource contention and fixed offset times. Conclusion: As a whole, BFD is a fast links failure detection protocol which is fit for OBS networks.Keywords：bidirectional forwarding detection;optical burst switching;failure detection;network survivability- 47
- |
- 5
- |
- 1
Published：2020-08-13 -
Non-uniformity correction of multi-TDICCD mosaic camera
Abstract：Aim at non-uniformity problem of multi-TDICCD mosaic camera, the synthetically correction algorithms about single TDICCD and multi TDICCDs are studied. First, based on CCD camera characteristic, the principles of TDICCD and non-uniformity are introduced. Then the principle of single and multi TDICCD is analyzed respective, two point correction methods is applied in single TDICCD and ratio average correction method is applied in multi TDICCD .At last, the integrative correction method is discussed. Experimental results indicate that multi-TDICCD mosaic camera is in a condition of 8.4% non-uniformity and it can reach to 2.7% non-uniformity after the correction. This correction method is satisfied the desire of the target of multi-TDICCD camera, and the algorithms has good practicality and efficiency.Keywords：TDICCD;mosaic camera;non-uniformity;image correction- 41
- |
- 6
- |
- 7
Published：2020-08-13 -
3D-FLIT and Its Application of ICT Cubic Data’s Linear Feature Extraction
Abstract：Objective: Linear feature extraction is very important in image processing. In ICT cubic data, line is one of the important features. The lines’ extraction efficiency will directly affect the performance of pattern recognition and classification. Method: Finite line integral transform (FLIT) is a new method based on the concepts of multiscale geometric analysis (MGA). Using a series of fixed templates in different scales, FLIT gets a series of decomposition images containing the original image’s information at different scales and directions. FLIT is invertible and non-wrap, which is very successful in image denoising, line extraction and recognition when applied to images with line singularities. Based on the concept of 2D-FLIT, this paper generalize it to the case of 3D, attaining the formulas of 3D-FLIT and inverse 3D-FLIT. In this paper, in order to extract linear feature of ICT cubic data, the authors present two methods based on FLIT (2D-FLIT or 3D-FLIT), including other image processing, such as image fusion and morphological. The first strategy is the idea of 3D-FLIT applying on the ICT cubic data directly for detecting linear features. The second strategy is the idea of 2D-FLIT applying on each slice in some direction of the ICT cubic data for detecting linear features. Then different directions’ images are fused for obtaining the linear features. Finally morphology image processing is used for extracting useful components of the linear features. Result: Numerical experiment results prove the efficiency of the proposed methods compared with wavelet method. Conclusion: Comparatively speaking, because the first strategy avoids slice dividing and saves the voxel relation between adjacent slices, its extracting linear features’ result is better and full than the second strategy. But, the second strategy is simpler and has less computation time. So, each of the two strategies has its own strong point.Keywords：3D-FLIT;linear feature;cubic data;image fusion;morphology- 32
- |
- 4
- |
- 2
Published：2020-08-13 -
Optimization of MPEG-4 Video Encoder Based on TMS320C6416T
Abstract：A optimized encodering method of MPEG-4 based on TMS320C6416T is presented. In order to satisfy the real-time requirement, according to the characteristics of C64x DSP, some methods of software optimization are proposed, which include allocating memory in reason, adopting two buffers in memory based on the characteristic of EDMA, realizing core code by linear assembly language and C code optimization. Experimental results show the encoder can realize real-time encoding of 768*576, 25 frame/s video images.Keywords：video compression;MPEG-4;TMS320C6416T;software optimization- 32
- |
- 7
- |
- 1
Published：2020-08-13 -
A Camera Calibration Based on Correction of the Asymmetric Circle Center Projection
Abstract：This paper presents a camera calibration method using circular control points whose centers need to correct bias error caused by asymmetric projection. The mathematical formulations of the correction terms are discussed. The perspective transformation matrix is first estimated using DLT (Direct Linear Transformation) method without decomposition. And then the projection of the circle is obtained directly using the elements of perspective transformation matrix. The centers of circle in the image plane are then corrected with the elements of perspective transformation matrix that will be recomputed after correction. The proposed method avoids the transformation between different coordinates. The relationships between bias error and the parameters of the circle are reported through synthetic. The real tests show that the calibration error is 0.19437 pels when the resolution of camera is 780×582 pels and the radius of circle is 20mm. The accuracy is improved after correcting asymmetric projection, and the presented algorithm is feasible and valid.Keywords：DLT;perspective transformation matrix;circular control points;asymmetric projection;bias correction- 37
- |
- 10
- |
- 3
Published：2020-08-13
Article
Loading...
0