In the resistance spot-welding (RSW) of galvanized complex phase (CP) steel, liquid metal embrittlement (LME) may occur, deteriorating the welded joint’s performance. Based on the Auto/Steel Partnership (A/SP) standard, the joints of galvanized CP steel welded with a welding current from 7.0 kA to 14.5 kA were evaluated. When the welding current increased to 11.0 kA, LME cracks began to appear. The longest type A crack was 336.1 μm, yet the longest type D crack was 108.5 μm, and did not exceed 10% of the plate thickness, which met the limitation of the A/SP standard. In light of the microstructural observation and element distribution, it was found that there existed an internal oxide layer adjacent to the surface of galvanized CP steel matrix, with the depth of about 4.1 μm. In addition, the simulation results show that the CP steel was under tensile stress throughout the RSW process, but the internal oxide layer could successfully lead to the low LME susceptibility of the Zn-coated CP steel.
This paper introduces a high precision thermal analysis system based on PC Bus, and discusses its hardware、 software and application. It can be used in controlling the quality of aluminium alloy.
After analyzing noise and disturbance in FBG temperature sensing network, three different kinds of statistical methods are processed in experiment as pretreatment to deal with inaccuracy of data fusion results caused by outliers. After replacing outliers with statistical estimated value of three methods respectively, weight minimum mean square error (WMMSE) algorithm is operated to fuse majorized data. Pretreatment makes full use of sensors’ data, meanwhile, accuracy and robustness of measurement system are enhanced. Variances of the fusion results indicate that pretreatment can improve fusion results significantly. Fusion variance without pretreatment is 2.9762, larger than mean value method’ variance 1.9525, median method’s 1.3341 and trimmed mean method’s 1.6016.
Aiming at resistance spot welding joint of hot galvanized dual-phase(DP590GA) steel,the rule of cross-tensile strength and tensile-shear strength of the joint changing with welding current are researched,and compared with the spot-welding test result of common dual-phase plate(DP590).Meanwhile,combining facts of spot-welding nugget diameter changing with welding current and zinc residue in fusion zone by SEM spectrum analysis,main reasons that affect the strength of spot-welding joint of hot galvanized steel are analyzed.The results show that when other welding parameters are fixed,the trends of spot-welding joint strength and nugget diameter of DP590GA and DP590 changing with welding current differ at each current stage.And zinc residue in fusion zone increases with decreased welding current.It indicates three factors affect the strength of spot-welding joints differently at each stage.They are less nugget diameter caused by less contact resistance of spot-welding zone and welding current density because of zinc coating,increase of zinc residue in fusion zone,and zinc coating can cause splash in spot welding more easily.
The paper presents a theorem for designing the robustness template parameters of cellular neural/nonlinear network (CNN) for extracting inner corners of objects in gray-scale images. The theorem provides parameter inequalities for determining parameter intervals for implementing the corresponding tasks. The designed CNN has a linear A-template and a nonlinear B-template with two thresholds. A first numerical simulation example shows that the CNN designed via our method successfully detects the inner corners of objects in gray-scale images. A second one implies that the inner corner detection CNN may extract inner corners of objects in gray-scale images with Gaussian noise if suitable thresholds of the CNN are chosen.
In order to effectively detect and gather the fluorescence signals of the dental pulp of the tooth,the technology of laser induced fluorescence is used.The gather and display circuit of the fluorescence signals are designed,the ADS7804 converters and the AT89C51 are used as the core of the system,TFT-LCD is used as the display terminal,a fluorescence signal gathering system basea on the single-chip is designed.With the algorithm idea of sampling data mapping coordi- nate,dental pulp fluorescence signals are processed,display terminal is controlled through the single-chip microcomputer communication interface,in order to finish display of fluorescence signals.The gather and display of fluorescence signals of the dental pulp of the tooth is finished by system.
An improved algorithm used in gray image mosaic is presented in this paper,and these four images used are taken by a camera with translation.Firstly,we use the image sharpening algorithm to deal with these images which have overlapped area,then search a best matching point in another image based on gray relativity,finally merge overlapped image area data by using smooth factors and then get the whole image without patchlines.A lot of experiments show that this algorithm is more effective and exact for most overlapped images.
Based on the analysis of architecture of android and Loongson-based platform,some key techniques of porting Android system are studied.The Android source code has been modified according to the architecture and property of Loongson,then an Android Gingerbread system for Loongson-based is implemented.The performance of the optimized Dalvik virtual machine of the system is tested and verified.This work is valuable to other Android version transplant to Loongson-based platform.
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