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Issue 5 ， 2000
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Decoding method for RS codes in weakly-dual-basis
Abstract：The design problem of the high-speed RS decoder is discussed. The presentation of the finite-field elements in WDB is studied. And based on the computing method for the optimum WDB, the design for the bit parallel multiplier of finite-field is presented. By selecting the bit-parallel multiplier based on WDB and the modified BM iterative algorithm that can avoid inversion, the widely used RS decoder is constructed. The analysis results indicates: the complexity of the bit-parallel multiplier is low and is suited for VLSI implementation; the modified BM iterative algorithm makes the simple hardware implementation possible and is advantageous to On-The-Fly error correcting. The throughout of the decoder can reach a high value and it is suited for the high speed application.Keywords：weakly-dual-basis;bit-parallel;decoder;RS codes;BM algorithm- 56
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Published：2020-08-12 -
Restrained condition of Mallat algorithem in image processing
Abstract：Some problems were pointed out, which are easy to be confused and make mistakes in image processing using Mallat algorithem, and the correct restrained conditions using Mallat algorithem were also given. Image compressions based on subband coding has been studied by Haar and Daubechies wavelets, and three kinds of schemes for wavelet compression coding scheme were presented in this paper.The simulation experiments based on the restrained conditions were carried out and the results of the experiments can be used to effective schemes for image compression coding, therefore the Mallat algorithem can be applied correctly.Keywords：Mallat algorithem;restrained condition;wavelets transform;image compressions- 83
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Published：2020-08-12 -
Targets detection method for image under nature texture background
Abstract：Based on the energy distribution difference between targets and background and on the information distribution difference in wavelet field after multiscale decomposing, the energy feature is chosen as one of the detection basis. It brings the independence of background texture direction and the invariance of rotation and translation for the changes of targets. In order to restrain the noise of background, improve the edge precision and probability of detection, the fusion method of energy feature and multiscale-based edge feature is proposed. The results of experiments prove that this method has relative adaptability.Keywords：multiscale analysis;energy feature;edge feature;target detection;Image- 44
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Published：2020-08-12 -
Method of in-system programming for TMS320C25 using computer serial port
Abstract：TMS320C25 is a high speed digital signal processor. Because it works at a high speed, the length of the emulator cable should be as short as possible. Sometimes we need modify the program and erase the EPROM frequently, which is very inconvenient, especially while we debug the program on the outside site. This paper introduces a method of in-system programming about TMS320C25. This method is independent of TMS320C25 emulator. It loads code from computer immediately and transfer it to external program memory of TMS320C25 using computer serial port. This avoids erasing and programming EPROM time after time.Keywords：Digital signal processor;TMS320C25;in-system programming- 36
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Published：2020-08-12 -
Removal of random noises for medical CR images using WT
Abstract：Computed Radiography(CR)is being popularly studied in the world recent years. Compared with common X-ray imaging,CR system applies a special kind of digital message carrier, i.e. Imaging Plate(IP), to detect and digitize image data. With the aid of computer, it's possible for CR system to process and reconstruct X-ray image. Because there exists random noises while detecting X-ray image data, what we get finally is noisy signals, which need to be processed. In the paper,Wavelet Transformation(WT), a time-frequency domain analysis theory was introduced into X-ray image data detection and image reconstruction. Based on WT, removal of random noises of CR images has been accomplished in our work.Keywords：CR images;removal of noises;wavelet transformation(WT)- 39
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Published：2020-08-12 -
Application of adaptive antenna arrays in CDMA cellular system
Abstract：The use of adaptive antenna arrays in code division multiple access cellular communication system at base station is presented since the arrays have the ability to suppress the interference of multiple access and increase the capacity of the cellular system. The composition and adaptive algorithms of the arrays are studied. The performance of the proposed system is analyzed. Both theoretical analysis and numerical simulation results demonstrate that using the adaptive antenna arrays at base station, the performance of the system is improved and its capacity is increased comparing with those of the omnidirectional antenna system.Keywords：code division multiple access;multiple access interference;adaptive antenna arrays- 56
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Published：2020-08-12 -
Characteristics of a novel optical-fiber sensor used for curved surface inspection
Abstract：A novel optical-fiber sensor used for inspecting the complex internal contours is presented. Based on the spoke-like arrangement of the fibers, the sensor of this kind can compensate the impacts caused by the variation of the surface reflectivity and the fluctuation of the light source. The characteristics of the sensor used for inspecting the curved surface are analyzed. And the simulation results prove the feasibility of the sensor. It has the performance of compact structure, non-contact measure, antijamming to electromagnetism. The results can provide an essential theoretical basis and design basis for measuring the curved surface and workpiece with reflective optical-fiber sensor.Keywords：internal contour;optical-fiber sensor;noncontact measurement- 30
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Published：2020-08-12 -
Dynamic characteristic analysis of the micropositioning system driven by PZT actuator
Abstract：The dynamic characteristic analysis of the micropositioning system driven by the PZT actuator is very important to design and application. By simplifying parts of the micropositioning system based on linearization, this paper analyzes the dynamic characteristics of the system working below resonance frequency, and its transfer function. Meanwhile, two boundary conditions-the maximum frequency response and preload that should be fed are analyzed.Keywords：PZT actuator;micropositioning system;dynamic characteristic analysis- 46
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Published：2020-08-12 -
Three-dimensional imaging in micro-operation system
Abstract：Micro-operation system for 3D fine manipulation is required to show the real-time information of micro-operation. Based on the analysis by the methods of three-dimension imaging, the method of simulative imaging was selected. Then the software and hardware projects were described. The authors apply the stereomicroscope and two CCD to simulate the eyes of human beings. The stereo video frequency signal was composed through the process of synchronous controller. The experimental result shows that the proposed method is effective.Keywords：micro-operation system;three-dimensional imaging;synchronous controller- 72
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Published：2020-08-12 -
Workshop oriented numerical method for improving the fit rate of accurate mating parts
Abstract：There are some problems in using traditional‘size-limits control method'to control the quality of the mating-parts, the anlaysis of a sample shows that this traditional method may cause a decreasing of the fit-rate when the size distribution of the mating-parts is non-Gaussian distribution. A method combining ‘probability analyzing'and‘point-to-point graphs of tolerance center control'is proposed to solve the existing problems in this paper, which makes statistical analysis for the size of the mating parts, draws distribution curve to instruct the subsequent production and uses ‘point-to-point graphs of tolerance center' to control process quality. And also a workshop-oriented application program is obtained to assist the process of quality control in site.Keywords：fit-rate of mating-parts;probability analyzing;point-to-point graphs of tolerance center control- 33
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Published：2020-08-12 -
Structure and properties of electroless nickel-boron alloy
Abstract：Heat treatment is capable of improving the hardness and wear-resistance of nickel-boron alloy considerably.The as-plated Ni-B alloy coating is noncrystalline.During heat treatment,its structure begins converting to crystalline and nickle crystal is precipitated at 250℃.Ni3B is precipitated at 300℃.Electroless Ni-B alloy coating has significant hardness,superior wear-resistance and excellent electrical properties.It can be used instead of gold or silver in some electrical components.Studies on the technology,structure and properties of electroless Ni-B coatings have been reported in domestic and foreign journals,but some aspects need additional study.This paper discusses the structure and properties of electroless nickel-boron alloy coatings,using sodium borohydride as reducing agent and ASE as stabilizer on brass.The effect of heat treatment temperature on structure and hardness are studied especially.- 36
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Published：2020-08-12 -
Characteristic of laser hardened structures of HT20-40 cast iron
Abstract：Hardening HT20-40 gray cast iron with CO2 laser, the structures characteristics and forming principle of hardened layer were studied. The results reveal that the laser-hardened zone of HT20-40 gray cast iron is consisted of three layers:(1)melting-chilling layer with whitening structure-refined ledeburite;(2)localized melting layer-graphite part is melted, island structure has the characteristics of casting and martensite;(3)solid transformation layer-very fine martensite, the original pattern of lamellar graphite remains basically. Meanwhile, localized melting layer disappears by proper technology control, and there only exists melting-chilling layer and solid transformation layer.Keywords：laser hardening;microscopic structure;cast iron- 50
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Published：2020-08-12 -
Supporting and adjusting for collimator primary mirror with large-aperture and long-focal length
Abstract：Testing large-aperture and long-focal length optical system needs proper large-aperture and long-focal length collimator. The manufacturing of the large collimator with long focal length is different from that of the large collimator with short one. The environmental condition and the mounting method of the mirror influenced the quality of collimator. In order to get a good quality of the collimator, the surface figure of the mirror must be good, and the mechanical construction for adjusting the mirror must be smart. In this paper, we introduced how to support and adjust the large primary mirror and its influence on the surface figure of the mirror. By testing, the method of supporting and adjusting has been proved right. We have already got the collimator with ideal diffraction limit.Keywords：long-focal length;collimator;primary mirror;supporting;adjusting- 57
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Published：2020-08-12 -
Design of automatic ellipsometer applied in LCD industry
Abstract：Fundamentals of ellipsometry and automatic ellipsometers are introduced briefly, and a sample machine of new type automatic null ellipsometer has been designed and constructed. Some techniques that can be used in measurement of LCD thin films are analyzed, then we point out that due to its properties of non-destructive, high-accuracy and high-speed, automatic ellipsometer is very suited for on-line monitoring of LCD thin film system. Owing to its advantages, ellipsometry and automatic ellipsometers can be used in many other fields and will gain good results.Keywords：ellipsometry;automatic ellipsometer;LCD;thin films- 46
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Published：2020-08-12 -
Accurate positioning scheme for close range of multi-optical-fiber
Abstract：LAMOST telescope needs 4000 optical fibers accurately positioned on focal surface of 1750mm diameter. The paper analyzed the strong points and shortcomings of the optical fiber positioning methods home and abroad. According to the principle of magnifying displacement with swing rod, the paper put forward the method of optical fibers positioning with parallel adjusting tables and swing rod, and designed the positioning structure of close range optical fibers in a small space. The analysis results make known, the structure can meet the needs of the every index to the optical fibers positioning for LAMOST telescope, the positioning precision can reach to ?0.04 mm, which supplies the basis of the choosing plan for LAMOST telescope.Keywords：positioning scheme;structure of swing rod;parallel tables- 48
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Published：2020-08-12 -
Phase-unwrapping for interferograms with circle field
Abstract：Phase-unwrapping is a basic problem in many interferometry. The phase unwrapping algorithm using DCT method is one of specially effective and robust ones. However, it is only suitable for rectangle fields. In this paper, it is effectively used for circle fields by introducing weighted and iterative methods. The computer simulation shows that the accuracy can reach to 10-7 rad and important improvement is made. A sample of multiline is measured using phase-stepping interferometry in DOP-2000 digital optical profiler developed by us. Further experimental results indicate that the method is very effective and practical.Keywords：phase-unwrapping;weighted iteration;Interferometry- 96
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Published：2020-08-12 -
Automatic measurement system for axis roundness
Abstract：In order to research a method with simple structure, high precision and low cost for automatically measuring axis roundness, the article redesigns the traditional V-shaped measuring system into automatic measuring system based on the practical application and measuring precision of the traditional V-shaped system. The article introduces the basis principle of V-shaped method, the structure of automatic V-shaped system and selection of its component. The automatic system can realize automatic measurement by following processes:computer controlling, direct current servo motor rotating measured axis, counting encoder calculating the angle of measured axis, measuring head automatically collecting measuring data, computer calculating the data and outputing measuring result. The cost of the whole equipment is less than a hundred thousand Yuan.Keywords：roundness;V-shaped method;automatic V-shaped method- 46
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Published：2020-08-12 -
Improvement of measurement precision of circular raster by photoelectric phase-comparing method for angle positioning
Abstract：Formula is used to explain the factors affecting the measurement precision of score errors of the circular raster by photoelectric phase-comparing method for angle positioning. It is proved that, under the conditions of high stability of the instrument and high turning precision of principal axis, the higher measurement precision can be achieved by using spectroscopic phase-splitting method for reading system, inverted OR gate for phase-discrimination, interpolation method and symmetry relation method.Keywords：circular raster;scoring errors;constant angle- 34
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Published：2020-08-12 -
Direct optical method for calibrating the optical center in vision coordinate measurement
Abstract：The paper introduces the methods for calibrating the optical center in vision coordinate measurement-the method of varying focal length, radial alignment method and direct optical method, and compares their characteristics. It describes the principle and calibrating procedures of direct optical method in details and makes some experiments. The results show that direct optical method has the virtues of high accuracy and good repeatability. The experiments also indicate that the calibrating procedures is feasible.Keywords：Vision coordinate measurement;optical center;calibration- 52
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Published：2020-08-12 -
Theory and implementation method of removing line resistance and junction resistance in low resistance measurement
Abstract：The measurement theory and method of source Wheatstone bridge in low resistance trim were described. The method of removing line resistance and junction resistance in low resistance measurement was proposed, and the measurement precision was analyzed. The method is valuable to the low resistance measurement and control.Keywords：Wheatstone bridge;resistances;measurements- 57
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Published：2020-08-12 -
New type of CMM —— Parallel mechanism coordinate measuring machine
Abstract：According to the theory of spatial mechanics, CMM(Coordinate Measuring Machine)can be classified as two groups, that is the serial-mechanism CMM and the parallel-mechanism CMM. Generally, the parallel-mechanism CMM has higher measuring accuracy and more flexible probe posture than the serial-mechanism CMM. Secondly, the parallel-mechanism CMM is of high technical additional value because its ‘hardware' is simple and the ‘software' is complex. Therefore, theoretical and experimental research for this new kind of CMM has currently become a hot topic for both industry and academia. In this paper, the state-of-the-arts and the drawbacks of Cartesian CMM are discussed and the characteristics of the parallel-mechanism CMM are introduced. Then the theoretical base, the research situation and the trend about the parallel-mechanism CMM around the world are synthesized. Finally, the problems, which should be noticed in researching the new CMM, are discussed.Keywords：coordinate measuring machine;parallel mechanism;serial mechanism;CMM- 33
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Published：2020-08-12 -
Manufacturing large-size grating by mosaic way
Abstract：The large-size diffraction gratings have become the key unit of some major engineering. All of grating experts around the world are searching the way to produce the large size gratings. This paper reviewed the history of grating manufacturing and introduced the trend of grating development, meanwhile, described the principle of the mosaic gratings. By analyzing the way which foreign country made mosaic gratings, we found the diffraction wave front of every grating is out of phase in a large one and there are a lot of things to do for it to be in-phase. But there are many advantages for manufacturing large-size gratings by mosaic way. We come to a dicision, at present, the way of mosaic gratings is a very effective method for manufacturing large-size gratings.Keywords：diffraction gratings;moasic gratings;large-size diffraction gratings- 33
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Published：2020-08-12 -
Transmyocardial revascularization by laser punching
Abstract：Transmyocardial laser revascularization(TMLR)is a third viable alternative to bypass surgery and angioplasty. TMLR has many advantages, such as limited chest open, little blood loss, easy operation, short time, low cost and so on. It has raised hopes for the most dismal extremes of coronary disease to patients who had been ejected from either bypass or angioplasty. Many clinical studies show TMLR can increase heart′s blood reperfusion, render angina free and improve the patients′ life quality. In this paper, based on different clinical results and opinions, the TMLR procedure, parameter selection, after-operation response, future applications and some debated questions are discussed in detail. All of them can be benefit for further studies and trials.Keywords：CO2 laser;myocardium punching;TMLR;heart disease- 46
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Published：2020-08-12
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