Table of Content

28 May 2014, Volume 48 Issue 05 Previous Issue    Next Issue

Metallography and Metallurgical Technology

Select

Normal Tracking Algorithm for Avoiding Interference in NC Profile Grinding XIE Bin,XU Liming,YANG Ziqi,HU Dejin 2014, 48 (05):  589-593.  Abstract ( 754 )   Save An novel algorithm was presented in regard to the avoidance of interference in normal tracing grinding. The mathematic model of the algorithm was established based on the geometric characteristic and the kinematic relationship between the wheel and the workpiece. The algorithm was simulated and applied in the NC profile grinding. The simulation and experiment both show that the algorithm is effective in avoiding interference in normal tracking grinding. The interfering points on the workpiece could be examined and the optimum approximated normal tracking angle could be calculated based on  this algorithm. References | Related Articles | Metrics

Select

Wear Characteristics on Tools in U-shaped Stretch-Bending of Dual-Phase Steel Sheet DP780 YUE Dong,SUN Li,YU Zhongqi 2014, 48 (05):  594-599.  Abstract ( 878 )   Save Finding the most suitable tool material is the main way to reduce the wear on the surface of parts and enhance the life of tools in the advanced high strength steel stamping. This paper investigated the wear resistance and characteristics of different tool materials—V4E(TD), DC53(TD) and DC53(vacuum heat treatment) in U-stretching-bending experiment using DP780.The result shows that the V4E(TD) and DC53(TD) have a good performance on wear resistance, while the DC53 by vacuum heat treatment does not perform well. For the first two inserts, wear mainly occurs in the area of 0°-15°on the die radius. While on the DC53 (vacuum heat treatment), serious wear occurs on both the die radius and flange.   References | Related Articles | Metrics

Select

Three-Dimensional Reconstruction of Plasma Image in CO2 Laser Welding WANG Yonggui,SUN Dawei,CAI Yan,ZHU Junjie,WU Yixiong 2014, 48 (05):  600-604.  Abstract ( 92 )   Save A set of high-speed cameras were used to obtain the plasma image in different directions in the process of CO2 laser welding. The centroid projecting principle was employed to adjust the plasma images in different directions. The projection relationship between the 3D plasma and 2D images were achieved by camera calibration and calculation of projection weighting factors. Finally, the 3D radiation distribution of plasma was obtained based on algebraic reconstruction technology (ART). The result shows that the 3D reconstruction of laserinduced plasma has a high reconstruction accuracy. And compared with 2D plasma image, the 3D reconstructed data reflects the dimensional characteristics and inner information of the plasma much more accurately.   References | Related Articles | Metrics

Select

Strain Hardening Effect of QSTE700 Cold-Formed High Strength Steel Square Tube CHAO Can1,ZHAO Yixi1,KANG Wen1,YAN Peijie2,MA Yuefeng2 2014, 48 (05):  605-609.  Abstract ( 183 )   Save Serial tensile tests were conducted to investigate the mechanical properties of different parts for QSTE700 square tube. It shows that the strength is improved by 10% at welded portion while the strength of flat portion remained unchanged. The strength of corner portion is 17.78% higher than that of the original steel but still lower than that of the traditional carbon steel square tube. The real fillet plays an important role in yield strength improvement. The square tube in the FE model was divided into two parts with different material properties based the test data. The simulation result indicates that the model with different material properties is much closer to the real situation.   References | Related Articles | Metrics

Select

Effect of High-Pressure Hydrogen Gas on Fracture Toughness of Metals WANG Yanfei,GONG Jianming 2014, 48 (05):  610-613.  Abstract ( 133 )   Save Fracture toughness is an important property to characterize the resistance of metals against crack initiation and growth. It has been found that hydrogen gas has a detrimental effect on fracture toughness of many metals. It is a very difficult and dangerous task to measure experimentally the fracture toughness of metals in hydrogen gas, particularly in high-pressure hydrogen gas. In this paper, a model was developed to quantify the effect of hydrogen on the fracture toughness of metals based on the theories of stressinduced hydrogen diffusion, hydrogen enhanced decohesion and fracture mechanics. Experimental data in some literatures were used to verify the model, and a good agreement was obtained. The model can be used to predict fracture toughness of metals in hydrogen gas, or to extrapolate the fracture toughness of steels in the high pressure hydrogen gas based on the fracture toughness obtained experimentally in the low pressure hydrogen gas.   References | Related Articles | Metrics

Select

Bayesian Reliability Assessment for Numerically Controlled Machine Tools with Imperfect Repair WANG Zhiming1,YANG Jianguo2 2014, 48 (05):  614-617.  Abstract ( 68 )   Save A Bayesian reliability assessment method of small sample failure data for numerically controlled machine tools with imperfect repair was proposed. The selection of prior and posterior distributions for virtual age model of generalized renewal process was discussed. Bayesian point and interval estimates of model parameters and reliability indices including cumulative failure number, failure intensity and reliability etc. were obtained via Markov chain Monte Carlo (MCMC) sampling. A real example was analyzed, whose results show that Bayesian reliability analysis method has a higher accuracy than maximum likelihood estimate because of its incorporating prior information.   References | Related Articles | Metrics

Select

Microstructural Study of Advanced High Strength Dual-Phase Steels Sheet Under Stretch-Bending Forming Process HE Chunfeng,ZHAO Yixi,HUANG Sheng 2014, 48 (05):  618-623.  Abstract ( 85 )   Save Stretchbending is a typical method for sheet stamping forming. Different fracture failure modes occur on advanced high strength dual phase steel based on different stress state. For example, shear fracture occurs under tight radius stretchbending condition. In this paper, a stretchbending ratio α was introduced to indicate different stress states to determine the failure mode: necking or shear fracture. Stretchbending experiments of DP steels were conducted and fracture morphology was observed. The results show that shear fracture still belongs to ductile fracture, and tighter punch radius or higher DP strength leads to shear fracture much more easily. Key words： References | Related Articles | Metrics

Select

Controlling Method for Edge Wave in Flexible Roll Forming WANG Zhenxiao,ZHAO Yixi,KONG Qingshuai,YU Zhongqi 2014, 48 (05):  624-628.  Abstract ( 140 )   Save A novel flexible roll forming method, which is a complex process of repetitive loading, was proposed for manufacturing large curved and thinwalled metal plates. Edge wave is one of the significant defects in flexible roll forming due to its complex forming variables. A finite element model was established to analyze the effect of main forming variables, such as forming path, the number of forming stations and the distance between stations, on edge wave in flexible roll forming. The simulation results show that forming path has a great influence on edge wave. The increase of the number of roll stations and the distance between roll stations could result in reducing edge wave.   References | Related Articles | Metrics

Select

A Data Compression Algorithm Based on  G2 Continuous  Bézier Curves for Tool Paths ZHAO Sheng1,BI Qingzhen1,WANG Yuhan1,SHI Jing1，LIU Gang2 2014, 48 (05):  629-635.  Abstract ( 135 )   Save The machining of continuous short blocks is a hot and difficult point for CNC machining. In this paper, a data compression algorithm based on the Bézier curve was proposed. First, the areas suitable for compression were screened out based on the geometric characteristics of continuous short blocks. Then, G01 points in each area were converted to special 3 order Bézier curves. To decrease the fluctuation of curvature and increase the compression ratio, the least square method was chosen to fit points. By adjusting the control points and inserting transition curves, the machining path was made G2 continuous. The fitting error was estimated by 2-order Taylor formula. Without iteration, the algorithm was realtime. The experiment proved that the compression ratio was high. The errors estimated by Taylor formula was extremely close to the real ones, indicating that the fitting accuracy could be controlled effectively.   References | Related Articles | Metrics

Select

Measurement of Welding Formation Size Based on Laser Line Scanning   ZHANG Pengxian,LI Ming,DAI Dunsan 2014, 48 (05):  636-640.  Abstract ( 141 )   Save A method for visual measurement was proposed to acquire welding formation sizes based on laser line scanning. A visual system for detecting welding formation was developed and simultaneously calibrated, based on which, images of welding formation and laser stripe which were cast on the surface of weld were captured in real time. And extracting and thinning of laser stripes in the image were accomplished by means of a series of image preprocessing methods, such as median filtering, threshold segmentation, skeletonization and morphological processing. The laser stripe being made as information source, the outline of weld forming was revealed exactly, based on which, a series of algorithms for realtime detection of the width and length of weld were established. The measured results show that visual measurement method aided by laser stripe can acquire the width and length of weld automatically, and the measured width and length of weld can meet the demand of weld formation evaluation.   References | Related Articles | Metrics

Automation Technique, Computer Technology

Select

Online Modeling of Kernel Extreme Learning Machine Based on Fast Leave-One-Out CrossValidation ZHANG Yingtang,MA Chao,LI Zhining,FAN Hongbo 2014, 48 (05):  647-652.  Abstract ( 208 )   Save A novel algorithm based on fast leave-one-out cross-validation was proposed, named as online kernel extreme learning machine (OKELM). Online modeling was accomplished by importing the latest training sample and discarding the oldest training sample. An adaptive FLOO-CV prediction error-based threshold without any manual work was used to enhance the sparsity and generalization ability of the model by only introducing the samples with larger predictive error. The output weights of the OKELM were determined recursively based on Hermitian formula. Thus, the online storage space and calculation time was reduced. Numerical experiments on chaotic time series prediction and identification of a continuous stirred tank reactor show that the OKELM has faster calculation speed and higher learning accuracy in comparison with off-line kernel extreme learning machine, unsparsity online kernel extreme learning machine and on-line sequential extreme learning machine.   References | Related Articles | Metrics

Select

High-Dimensional Data Stream Outlier Detection Algorithm Based on Angle Distribution PIAO Changhao1,HUANG Zhi1,SU Ling2,LU Sheng1 2014, 48 (05):  647-652.  Abstract ( 154 )   Save To improve outlier detection in high-dimensional data stream, a novel high-dimensional data stream outlier detection (DSOD) algorithm based on angle distribution was proposed. To identify the normal point, border point and outlier accurately, the method of angle distribution-based outlier detection algorithm was employed. To reduce the computational complexity, a smallscale calculation set of data stream was established, which is composed of normal set, border set. To solve the problem of concept drift, an updated mechanism for the normal set and border set was developed. The experimental results on real data sets demonstrate that DSOD is more efficient than Simple variance of angles (Simple VOA) and angel-based outlier detection (ABOD) and is very suitable for the outlier detection of large data streams.   References | Related Articles | Metrics

Select

Region of Interest Based Texture Image Retrieval Using Curvelet Correlogram SU Fu 2014, 48 (05):  653-657.  Abstract ( 152 )   Save A novel algorithm based on region of interest was presented for texture image retrieval. The proposed method was based on a combination of Curvelet multiresolution image decomposition and colour correlation histogram. First, Curvelet transform was applied for texture image multi-scale decomposition. Then, the region of interest was extracted based on the distribution of the energy of different scales, and a quantization step was used before computing autocorrelograms of the region of interest Curvelet coefficients. Finally, index vectors were constructed for similarity comparison. Experiments based on Brodatz benchmark database show that the algorithm is more effective compared to other retrieval methods based on Curvelet in texture image retrieval. Key words： References | Related Articles | Metrics

Metallography and Metallurgical Technology

Select

A Fast Convex Hull Algorithm for Ring-Distributed Planar Point Sets CHEN Ming,ZHANG Feng,DU Zhenhong,LIU Renyi 2014, 48 (05):  658-662.  Abstract ( 105 )   Save Aimed at the problem that the gridaided algorithm does not perform well in constructing convex hull of a ring-distributed point set, a gridreprocessing algorithm was proposed. By comparing the spatial relationship between related cells, the proposed algorithm eliminated most of the points never proved to be vertices of the convex hull twice. As a result, the number of points to be Grahamscanned was greatly reduced and the computational efficiency improved. The experimental results show that the grid-reprocessing algorithm significantly improves the efficiency of handling ring-distributed point sets and is more efficient, to a certain extent, than the grid-aided algorithm when dealing with evenly distributed point sets. References | Related Articles | Metrics

Automation Technique, Computer Technology

Select

Time-Optimized Generation of Two-Qubit Entanglement States HUANG Zexia1a,2，HUANG Decai1b，YU Youhong1c 2014, 48 (05):  663-667.  Abstract ( 112 )   Save A time-optimized method to control the unitary time evolution in a quantum unitary gate was proposed using the Heisenberg model. For two classes of states |00〉，|11〉 and |01〉，|10〉, the time-optimized generation of any target entangled state under a uniform magnetic field was analyzed, and a novel strategy based on the time-optimized method to generate two qubit entangled states was suggested. The effectiveness of the proposed strategy was theoretically verified by simulations.   References | Related Articles | Metrics

Metallography and Metallurgical Technology

Select

A Video Shot Segmentation Method Based on a Two-Stage Support Vector Machine Classifier YU Lu1,2,QIAO Ruiping2,HU Yuping2,ZHAO Jing1,2 2014, 48 (05):  668-673.  Abstract ( 129 )   Save A video shot segmentation method based on a two-stage support vector machine (SVM) classifier was proposed. In the first stage，the feature vectors were generated by using the segmented video histogram distance, combining the sliding window with the trap method. Then, the subsegments containing shot boundaries were filtered out by using the SVM classifier. In the second stage，the feature vectors were obtained by histogram distance between different spacing of the frames and time window. The shot detection was implemented by binary tree SVM classification strategy. Experimental results show that the detection results can be improved on both abrupt and gradual shot boundary significantly by the proposed method.   References | Related Articles | Metrics

Automation Technique, Computer Technology

Select

Intestinal Biopsy Endoscopic Robot System   CHEN Wenwen,YAN Guozheng,WANG Zhiwu,LIU Hua,JIANG Pingping 2014, 48 (05):  674-678.  Abstract ( 170 )   Save Based on intestinal biopsy diagnosis demand, the gasbag anchoring mechanism and biospy mechanism were designed. The intestinal capsule endoscopy robot was developed which could move autonomously in the intestine and conduct video examination and biopsy. Experimental results show that the petals airbags can effectively increase the clamping force to 1.56 N, while reducing the volum. The shear force of biopsy forceps is greater than 10 N, which meets the requirements of visualization, and the biopsy motion is repeatable. With wireless power system, the system is stable and reliable.   References | Related Articles | Metrics

Radiao Electronics, Telecommunication Technology

Select

Linear Servo Robust Tracking Control Based on ZPET-FF and Extended State Observer CHEN Xinglin,LIU Chuan,ZHOU Naixin,WANG Bin 2014, 48 (05):  679-684.  Abstract ( 147 )   Save An nmlevel positioning precision and high-speed were required by using macro movement of long stroke linear motor and high-precision micro movement of planar motor in the wafer stage of lithography. In order to reduce the movement scope and acceleration of planar motor, the tracking precision of linear motor must be improved. Therefore, this paper presented a combined repetitive control strategy based on the combination of zero phase error tracking-feed-forward (ZPETFF) controller and the disturbance observer (ESO). The ZPET-FF was used as the feed-forward controller, which used the real-time compensation of the controller according to the tracking error of the system, so that the influence of parametric variation of the system and the dynamic tracking error of the system could be reduced, while ESO reduced the influences of the uncertainties, suppressed the system noise and improved the antiinterference ability of the system effectively. The experiment shows that the proposed control method not only improves the dynamic tracking performance of the system, but also reduces the tracking error of the system. References | Related Articles | Metrics

Select

Self-Adjusting Underwater Acoustic Channel Estimation and Communication Algorithms Based on Decision Feedback Equalizer LUO Yasong1，XU Jianghu1，LIU Zhong1，XIAO Jinshi1,WU Shiye2 2014, 48 (05):  685-692.  Abstract ( 136 )   Save Based on analysis of the LS-series channel estimation algorithms, the matching pursuit (MP) algorithm with small computation amount was improved by importing both a threshold adjusting mechanism which could effectively avoid false paths and an iterative correction method to increase the estimation precision for important coefficients of the sparse underwater acoustic channel. In order to overcome the dependence on the information of channel’s length, a novel channel estimation algorithm which could adapt to real channel’s length was proposed. Decision feedback equalizer (DFE) coefficients were computed recurring to the real-time channel estimation results while the evaluation of channel estimation’s quality which could be fed back to adjust channel estimation algorithm was given using DFE’s output signals. The novel algorithm could effectively implement estimations for unknown underwater acoustic environments which also benefited reliable underwater acoustic communications. The proposed method was validated by simulations and experiments. References | Related Articles | Metrics

General Industrial Technology

Select

A Method for Bending and Strain Measurement of Micro-Cantilever Based on Digital Image Correlation with Initialization Optimization LIU Hongtao,LIANG Zhenning,HU Wen,MO Jinqiu,WANG Shigang 2014, 48 (05):  693-701.  Abstract ( 157 )   Save A method for bending and strain analysis of micro-cantilever with initialization optimization by digital image correlation was proposed. Feature points were detected and matched in the scale space based on the image context obtained under microscope. First, the transformation parameters were calculated by digital image correlation with high order in the feature points. Then, the initial transformation parameters of every pixel of the cantilever were obtained by the interpolation in twodimension which could be used as the initial value for the iterative spatial domain cross correlation algorithm (NewtonRaphson method). Finally, the refined displacement and strain information at some special grid  were calculated. While the algorithm parameters were optimized in the experiment of the simulated bended images, the performance of the proposed method was verified through the strain comparison with the finite element method.   References | Related Articles | Metrics

Select

Lifetime Prediction Method for Missile Electrical Connector Synthesizing Degradation Data and Lifetime Data WANG Haoweia，XU Tingxuea，ZHOU Weib 2014, 48 (05):  702-706.  Abstract ( 126 )   Save To improve the prediction accuracy of the lifetime of a certain type of missile connector, a prediction method synthesizing degradation data and lifetime data was proposed. By modeling the degradation data with Wiener process, modeling a small amount of lifetime data with inverse Gaussian distribution, establishing the reaction rate model with the generalized Eyring model, a comprehensive reliability model was established. Furthermore, the point estimates of the model parameters were obtained through the Markov Chain Monte Carlo simulation method, and the interval estimates were obtained through a bootstrap method. By comparing the prediction results, it was concluded that the approach synthesizing degradation data and lifetime data could improve the prediction accuracy. Key words： References | Related Articles | Metrics

Mechanical instrumentation engineering

Select

Adaptive Robust Control for Mechatronic Servo System with State Constraints   WU Yuefei1，HU Zhiqi2,MA Dawei1，YAO Jianyong1，LE Guigao1 2014, 48 (05):  707-712.  Abstract ( 112 )   Save A nonlinear adaptive robust tracking strategy based on high-gain observer was designed for the servo system with state constraint for actuator dynamics and state measurement noise. A high-gain observer based on the value of the position measurement system was introduced, which consisted of a series of filters to eliminate the noise on the accuracy of the observer and the gain was estimated to ensure the observer robustness. A novel barrier Lyapunov function was proposed for tracking desired guidance commands. In the process of the design, requirements on system states could be satisfied by limiting the magnitude of the virtual control signals. The entire uniform bounded stability of the closed-loop system was proved by Lyapunov method. The system test shows the method suggested in this paper can estimate the speed and position of the load. Compared with the traditional control method, it has the advantages of strong anti-jamming capability, good robustness and rapid speed.   References | Related Articles | Metrics

Select

Adaptive Configuration Method of Friction Compensation Pulse Characteristic Parameters   FENG Bina,MEI Xuesonga,b,YANG Juna,HUANG Xiaoyonga 2014, 48 (05):  713-718.  Abstract ( 95 )   Save A novel adaptive configuration method of friction compensation pulse characteristic parameters was proposed. The friction compensation pulse characteristic parameters were accurately calculated by the dynamic iterative process based on trajectory parameters, friction torque, the desired performance value, dynamic information and servo control parameters. This method was adopted to compensate for the friction error on the precision motion worktable. The experiment results show that the proposed method has a better performance and the deviation peak of tracking error is less than  1 μm under different working conditions and trajectories. References | Related Articles | Metrics

Others

Select

Service Composition Method Based on Collaboration Network and Task Circumstance PENG Yanbin1,ZHENG Zhijun1,LI Jiming2,SU Xianchuang3,YU Chengbo4 2014, 48 (05):  719-724.  Abstract ( 152 )   Save The basic concept of service mapping repository, collaboration network and service task circumstance was introduced. An approach based on collaboration network and task circumstance to compose services automatically was proposed. First, this method built a complete collaboration network for every output; next, the collaboration networks were combined into a composite service to meet the needs of users; finally, best composite service was returned to the user based on compatibility of synthetical task circumstance. The experimental results show that the method proposed can improve the success rate and efficiency of service composition. References | Related Articles | Metrics

Select

Location Model and Its Solution Considering the Failure of Facilities and  Reassignment Algorithm of Customers   ZHOU Na1，ZHU Wei2，MI Weijian1 2014, 48 (05):  725-729.  Abstract ( 126 )   Save Based on the classic uncapacitated fixed charge model, and considering simultaneously the system operation cost and reliability, this paper proposed a nonlinear mixed integer programming model taking into account the failure probability and the customer multilevel redistribution. The linear processing model was solved by using the optimized Lagrangian relaxation algorithm. The data case shows that Lagrangian relaxation algorithm is more effective for midsize network location problem, and relative to multi-level reassignment of customers, the failure probability  of facilities has more influence on it.   References | Related Articles | Metrics

Select

Variation of Nano-Mechanical Property During the Repair of Microdamage WANG Gang 1, 2,YU Zhifeng1 2014, 48 (05):  730-734.  Abstract ( 116 )   Save The replacement of artificial joints, the internal fixation of fracture and other orthopedic implants will cause microdamage in the bone around the implant. Microdamage will reduce the bone quality around the implant, and affect the bonding strength within the interface between the implant and the bone, thus influencing the longterm stability of the implant. In this paper, the production and repair of proximal and distal mechanical microdamage after the implantation of screws, as well as variations in the micromechanical property and composition elements of bone tissue were compared during the process of microdamage repair. It is found that with the repair of microdamage, there is a decrease both in the hardness and elastic modulus of local bones. With the final repair of microdamage, the micromechanical properties are restored. References | Related Articles | Metrics

Others

Select

Robust Control of Line-of-Sight Attitudes of a Two-Axis Gimbaled Seeker WANG Xianfang1,MIAO Jun2,ZHAN Shitao2,3,QIAO Zhiyuan2,4,WANG Suihua1 2014, 48 (05):  735-740.  Abstract ( 133 )   Save A robust design approach was proposed to address the line-of-sight (LOS) control problem for a gimbaled seeker with yaw-pitch configuration. Differential equations on LOS dynamics were deduced via the moment balance of each gimbal. The different modes in which the major disturbances, including disturbance torque, system nonlinearity and platform angular motion, influence the system dynamics were analyzed. Based on the unstructured uncertainty descriptions of the system, a H∞ controller was synthesized to realize servo control on the LOS attitudes. Simulation results demonstrate that the proposed approach supplies strong robustness against system uncertainties, disturbance torques and nonlinearities. Key words： References | Related Articles | Metrics