Subpixel accuracy for extracting groove center based on corner detection

Subpixel accuracy for V-groove center in robot welding is researched and a software measure to increase the accuracy of seam tracking by laser is presented. LOG （ Laplacian of Gaussian ） operator is adopted to detect image edge. Vgroove center is extracted by corner detection of extremum curvature. Subpixel position is obtained by Lagarange polynomial interpolation algorithm. Experiment results show that the method is brief and applied, and is sufficient for the real time of robot welding by laser sensors.     

Edge detection of molten pool and weld line for CO2 welding based on B-spline wavelet

Due to the disturbances of spatters, dusts and strong arc light, it is difficult to detect the molten pool edge and the weld line location in CO2 welding processes. The median filtering and self-multiplication was employed to preprocess the image of the CO2 welding in order to detect effectively the edge of molten pool and the location of weld line. The B-spline wavelet algorithm has been investigated, the influence of different scales and thresholds on the results of the edge detection have been cornered and analyzed. The experimental results show that better performance to extract the edge of the molten pool and the location of weld line can be obtained by using the B-spline wavelet transform. The proposed edge detection approach can be further applied to the control of molten depth and the seam tracking.     

Background removal and weld defect detection based on energy distribution of image

The lateral wave in ultrasonic TOFD （time of flight diffraction） image has a tail in transit time, which disturbs the detection and evaluation of shallow weld defect. Meanwhile, the lateral wave and back-wall echo that act as background add redundant data in digital image processing. In order to separate defect wave from lateral wave and prepare the way for following image processing, an algorithm of background removal method named as mean-subtraction is developed. Based on this, an improved method by statistic of the energy distribution in the image is proposed. The results show that by choosing proper threshold value according to the axial energy distribution of the image, the background can be removed automatically and the defect section becomes predominant. Meanwhile, diffractive wave of shallow weld defect can be separated from lateral wave effectively.     

Temperature measurement based on radialization power for micro-hotplate

A novel method to measure the temperature on the surface of micro-hotplate was presented. The tiny fiber probe and the optical power meter were employed to measure the sample radialization power. By means of comparing the relationship between the radialization power and the temperature, sample surface temperature can be discerned accurately. Such an approach has provided more accuracy than traditional temperature measurements. The experimental result based on this method is quite similar to that of simulation by the finite element analysis （FEA） software of Ansys in theory. This measurement is very useful for measuring temperature for these micro samples prone to be untouchable.     

Edge detection of remote sensing image based on nonlinear intensity of curved surface

1　INTRODUCTIONTheedgeofremotesensing (RS)imagereflectsthedifferenceoftheobjectsontheearthsurface .IfwedescribetheRSimageasacurvedsurfaceinthree dimensionalspace ,thedifferentobjectsontheimagechangeinnon linearwayoverthroughspace .Theedgeinformationofimageisveryimportantforscien tisttounderstandtheobjectsontheimage[13] .TherearemanykindsofedgedetectorsusedinRSimageprocesssuchasGradientdetector ,Sobeldetec tor ,Laplacedetector ,CannydetectorandRobertde tector[4 ,5] .Allthesedetectorsa…     

Estimation and accuracy evaluation of variance and covariance components based on more general functional model

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｓｔｕｄｙｏｆｖａｒｉａｎｃｅｅｓｔｉｍａｔｉｏｎｉｓｏｎｅｏｆｔｈｅｍｏｓｔｉｍｐｏｒｔａｎｔｆｉｅｌｄｓｏｎ ｇｅｏｄｅｓｙａｎｄｍａｔｈｅｍａｔｉｃａｌｓｔａｔｉｓｔｉｃｓ.Ｔｈｅｖａｒｉａｎｃｅｃｏｍｐｏｎｅｎｔｅｓｔｉｍａｔｉｏｎｂａｓｅｄｏｎｔｈｅｌｉｋｅｌｉｈｏｏｄｐｒｉｎｃｉｐｌｅａｎｄｍｉｎｉｍｕｍｎｏｒｍｐｒｉｎｃｉ ｐｌｅｈａｓｂｅｅｎｄｅｒｉｖｅｄ ,ｕｓｉｎｇｔｈｅｆｕｎｃｔｉｏｎａｌｍｏｄｅｌｓｏｆｃｏｎｄｉｔｉｏｎａｄｊｕｓｔｍｅｎｔｗｉ…     

Digital controlling for GMA welding machine based on DSP

This paper introduced a welding machine for GMAW using digital controlling method based on DSP (Digital Signal Process ). By means of flexible programming according to welding technologies and experiences the suitable characteristics of welding machine, such as line compensation, welding voltage and current feedback, wire-feed driving, SCR trigging and so on, can be controlled and self-adjnsted using digital signals. Through the designing based on DSP it is put out that the traditional hardware of control circuit is decreased greatly which can enhance the stability and reliability of welding machine. Finally, the welding experiment using CO2 shielding gas proves that the welding process is stable.     

Non-flammable electrolytes based on trimethyl phosphate solvent for lithium-ion batteries

1 INTRODUCTIONLithium-ion rechargeable batteries containelectrolyte solutions composed of Li salts and or-ganic solvents , typically organic carbonates . Al-most all these solutions are flammable and may beignited when hot solvents expelled from the cellscomes in contact with oxygen under abusive condi-tions such as overcharge[1 3]. In extreme case ,abused lithium-ion batteries have been reported tocombust and explode[4 6].Some separators have been used to exhibitshutdown performance to p…     

Ultrasonic image restoration based on support vector machine for surfacing interface testing

In order to restore the degraded ultrasonic C-scan image for testing surfacing inteoface, a method based on support vector regression （SVR） network is proposed. By using the image of a simulating defect, the network is trained and a mapping relationship between the degraded and restored image is founded. The degraded C-scan image of Cu-Steel surfacing inteoface is processed by the trained network and improved image is obtained. The result shows that the method can effectively suppress the noise and deblur the defect edge in the image, and provide technique support for quality and reliability evaluation of the surfacing weld.     

Theoretical analysis based on a modified mixed-film lubrication model for metal forming processes

An analytical model for metal rolling in the mixed lubrication regime was developed based on Wilson and Chang‘s asperity flattening model and Von Mises homogenous deformation model.A more rigorous average Reynolds equation was used to calculate the hydrodynamic pressure.The variations of the yield stress with strain were considered in the model.An efficient iteration procedure was developed to solve the contact area.film thickness and hydrodynamic pressure.The model is more practical with fewer assumption and converges quickly.It is applicable to a wider range of rolling regimes.The calculation results using the model agree well with the literature as well as with measured data from a rolling mill.     

Dynamic character analysis for the arc welding power source based on fuzzy logic

A lot of experimental methods have been brought forth to assess the dynamic character of the arc welding power source, but up to now, this issue has not been solved very well. In this paper, based on the fuzzy logic reasoning method, a dynamic character assessing model for the arc welding power source was established and used to analyze the dynamic character of the welding power source. Three different types of welding machine have been tested, and the characteristic information of the electrical signals such as re-striking arc voltage, low welding current and so on of the welding process were extracted accurately by using a self-developed welding dynamic arc wavelet analyzer. The experimental results indicate that this model can be used as a new assessing method for the dynamic character of the arc welding power source.     

Effects of constitutive parameters on adiabatic shear localization for ductile metal based on JOHNSON-COOK and gradient plasticity models

1Introduction Adiabatic shear band(ASB)is a very narrow zone with a high concentration of shear strain.It is believed that ASB is formed by a process of thermo-mechanical instability.ASB can be observed in the process of dynamic deformation of various fer…     

Backward tracing simulation of precision forging process for blade based on 3D FEM

In order to obtain the desired final shape, the blade precision forging requires a reasonable preformed billet which can be obtained from a given final shape by using backward tracing scheme based on FEM. The key technologies of backward tracing scheme based on 3D rigid-viscoplastic FEM were explored, and some valid algorithms or methods were proposed. A velocity field was generated by combining the direct iterative method with Newton-Raphson iterative method, and then the initial velocity field of backward tracing simulation was achieved by reversing the direction of the velocity field. A new method, namely the tracking-fitting-revising method, was proposed and can be used to determinate the criterion of separating a node from die in the backward tracing simulation. The ceasing criterion of the backward tracing simulation is that all the boundary nodes are detached from dies. Based on the above key technologies, the 3D backward tracing simulation system for the blade precision forging was developed, and its feasibility and reliability were verified by forward loading simulation.     

Predictive model based on artificial neural net for purity of perovskite-type SrTiO3 nanocrystalline

A three-layer structure back-propagation network model based on the non-linear relationship between the purity of the perovskite-type SrTiO3 nano-crystal samples and the technology factors, such as reaction time, reaction temperature, raw material adding amount of NaOH and SrCl2, and the rate of TiCl4/H1, was established. The input variables were pretreated by using the main component analysis firstly. Moreover, the momentum terms were introduced so as to accelerate the converging rate and avoid the non-converging situation. At the same time, the variable learning speed was adopted. The results show that the improved back propagation neural network model is very efficient for the prediction of the perovskite-type SrTiO3 nano-crystal sample purity.     

Optimized constitutive equation of material property based on inverse modeling for aluminum alloy hydroforming simulation

1Introduction Sheet hydroforming has many advantages such as high drawing ratio,good part surface,and can be applied widely in the versatile and low volume production with miscellaneous materials such as aluminum alloys,high-strength steel,stainless steel…     

Temperature distribution in adiabatic shear band for ductile metal based on JOHNSON-COOK and gradient plasticity models

1 Introduction Adiabatic shear localization is one of the most important deformation and failure mechanisms in some titanium alloys subjected to moderate and high shear strain rates. Adiabatic shear band(ASB) can be observed in various applications, such as metal forming, perforation, impact on structures, ballistic impact, machining, torsion, explosive fragmentation, grinding, interfacial friction, powder compaction and granular flow[1?15]. The formation of ASBs is often followed by ductile…     

Development of materials database system for cae system of heat treatment based on data mining technology

Computer simulation for materials processing needs of materials. In order to employ the accumulated large data on a huge database containing a great deal of various physical properties materials heat treatment in the past years, it is significant to develop an intelligent database system. Based on the data mining technology for data analysis, an intelligent database web tool system of computer simulation for heat treatment process named as IndBASEweb-HT was built up. The architecture and the arithmetic of this system as well as its application were introduced.     

A method of initial welding position guiding for arc welding robot based on visual servo control

0　IntroductionCurrentlyintelligentizingweldingrobotisaresearchdirectionthatgreatattractsresearchers.Thereinto ,theapplicationofvisionsensoristhemostattractedoffsetinintelligentizingrobotweldingwithbroadenutilityfield[1] .Themainadvantageofusingvisionisthatitneedn’tdirectcontactwithobject,andeasytosolveproblemwithnaturalandefficientway ,soplantracebe foremovingandfeedbackinformationduringmoving .Itissuitabletotasksinwhichdemandtheabilitytoadaptthechangingenvironments .Thispaperexploredthetas…     

Brazing alloys based on the Ni–Cr–Zr system for brazing creep-resisting nickel alloys

Summary

Offering the advantages of high welding speed and low heat distortion, laser welding is an attractive process for joining thin steel sheet. This paper describes an investigation of the static and fatigue strength of laser-welded lap joints in thin steel sheet with different sheet thicknesses and tensile strengths and compares the results with those obtained for spot-welded joints. To evaluate the static strength of the joints, a method for estimation of the joint strength and fracture mode is established. To evaluate the fatigue strength of the joints, the mixed-mode fracture-mechanics criterion of Erdogan and Sih is used, giving good characterisation of the fatigue strength, including that of the spot-welded joints.     

One component metal oxide sintering additive for β-SiC based on thermodynamic calculation and experimental observations

This paper examines a range of metal oxides, including those containing relatively safe elements under neutron irradiation, such as Cr, Fe, Ta, Ti, V and W, as well as widely used oxides, Al₂O₃, MgO and Y₂O₃, as a sintering additive for β-SiC theoretically and experimentally. After selecting the most probable SiC oxidation reaction at 1973–2123 K, the condition where the metal oxide additive does not decompose SiC was calculated based on the standard Gibbs formation free energies. Thermodynamic calculations revealed that Al₂O₃, MgO and Y₂O₃ could be an effective sintering additive without decomposing SiC under hot pressing conditions, which was demonstrated experimentally. On the other hand, no one component metal oxide that contains a safe element for nuclear reactor applications was found to be an effective sintering additive due to the formation of metal carbides and/or silicides. Overall, the simulation based on thermodynamic calculations was found to be quite useful for selecting effective metal oxide additives.