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Computing large deviation prefactors of stochastic dynamical systems based on machine learning
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作者 李扬 袁胜兰 +1 位作者 陆凌宏志 刘先斌 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第4期364-373,共10页
We present a large deviation theory that characterizes the exponential estimate for rare events in stochastic dynamical systems in the limit of weak noise.We aim to consider a next-to-leading-order approximation for m... We present a large deviation theory that characterizes the exponential estimate for rare events in stochastic dynamical systems in the limit of weak noise.We aim to consider a next-to-leading-order approximation for more accurate calculation of the mean exit time by computing large deviation prefactors with the aid of machine learning.More specifically,we design a neural network framework to compute quasipotential,most probable paths and prefactors based on the orthogonal decomposition of a vector field.We corroborate the higher effectiveness and accuracy of our algorithm with two toy models.Numerical experiments demonstrate its powerful functionality in exploring the internal mechanism of rare events triggered by weak random fluctuations. 展开更多
关键词 machine learning large deviation prefactors stochastic dynamical systems rare events
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IMPROVED FOURIER ALGORITHM FOR CORRECTING POWER SYSTEM FREQUENCY DEVIATION 被引量:1
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作者 姜惠兰 杨维 +2 位作者 徐建强 刘梅 仇晓锋 《Transactions of Tianjin University》 EI CAS 2001年第3期192-196,共5页
On the basis of high precision requirement for input signals in the power system protection and control system,this paper,only for the influence of power system frequency deviation on extracting fundamental harmonic,s... On the basis of high precision requirement for input signals in the power system protection and control system,this paper,only for the influence of power system frequency deviation on extracting fundamental harmonic,studies the amplitude error of Fourier algorithm,presents a method of correcting frequency deviation,and further derives the formulas of improved Fourier algorithm.The simulation results verified the effectiveness of the algorithm,it not only can greatly weaken the influence of frequency deviation,but also increase the precision of the power system protection and control.As a result the study in this paper has practical application value. 展开更多
关键词 power system protection and control frequency deviation Fourier algorithm
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A novel method for eliminating rotation deviation in sequential images mosaic
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作者 陈芳 陈恺 +1 位作者 赵斌文 史金飞 《Journal of Southeast University(English Edition)》 EI CAS 2012年第4期434-437,共4页
To eliminate rotation deviation of sequential images mosaic when measuring linear dimensions of large scale parts with computer vision, a novel algorithm based on the chain code searching method is proposed. After ima... To eliminate rotation deviation of sequential images mosaic when measuring linear dimensions of large scale parts with computer vision, a novel algorithm based on the chain code searching method is proposed. After image preprocessing, including image filtering, image segmentation, and edge detection, the chain code length of the contour line can be searched out by the proposed method. Then, the angle from the contour line to the coordinate axis is computed with the length of the contour line. After that, the sequence is rotated in the opposite direction and the rotation deviation is eliminated. It is prepared for the next mosaic of sequences in eliminating shifting deviation. Experiments are carried out on parts with a linear profile rotating angle from 0° to 9°. The results show that compared with the commonly used Hough transform, the new method has higher precision and faster speed, which is important in realizing online high precision measurements of large scale parts with a linear profile. 展开更多
关键词 sequential images mosaic linear profile chain code rotation deviation
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Precise large deviation result for heavy-tailed random sums and applications to risk theory
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作者 杨洋 林金官 《Journal of Southeast University(English Edition)》 EI CAS 2010年第3期498-501,共4页
The differences between two sequences of nonnegative independent and identically distributed random variables with sub-exponential tails and the random index are studied. The random index is a strictly stationary rene... The differences between two sequences of nonnegative independent and identically distributed random variables with sub-exponential tails and the random index are studied. The random index is a strictly stationary renewal counting process generated by some negatively associated random variables. Using a revised large deviation result of partial sums, the elementary renewal theorem and the central limit theorem of negatively associated random variables, a precise large deviation result is derived for the random sums. The result is applied to the customer-arrival-based insurance risk model. Some uniform asymptotics for the ruin probabilities of an insurance company are obtained as the number of customers or the time tends to infinity. 展开更多
关键词 precise large deviation random sum sub-exponential distribution renewal counting process customer-arrival-based insurance risk model
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Deviation in Advertising English from a Stylistic Perspective
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作者 罗敏 《英语广场(学术研究)》 2012年第10期15-17,共3页
Advertising English is viewed as an English style with such functional factors as attention value, readability, memorability, selling power. Commercial advertisements are the major concern of this paper. Deviation, na... Advertising English is viewed as an English style with such functional factors as attention value, readability, memorability, selling power. Commercial advertisements are the major concern of this paper. Deviation, namely the violation to the norms of a language, frequently appears in advertisements and can meet requirements of the style of advertising English. Due to limited space, this paper focuses on deviation on the phonological, graphological, lexical, grammatical, and semantic level. Analyzing deviation in advertising English can promote readers' aesthetic and appreciative ability and encourage advertisers to create advertisements with more efficiency, novelty, innovation in more effective language. 展开更多
关键词 advertising English deviation STYLISTIC VIOLATION NORM
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Stylistic Analysis of Rossetti's Song with the Technique of Deviation
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作者 胡争艳 《海外英语》 2013年第4X期167-168,199,共3页
Song is one of Christina Georgina Rossetti's most outstanding death poems,dealing with the main themes that she concerns:death,love and religion.This paper tries to use the technique of deviation that refers to vi... Song is one of Christina Georgina Rossetti's most outstanding death poems,dealing with the main themes that she concerns:death,love and religion.This paper tries to use the technique of deviation that refers to violations to the standard language and readers'expectations to interpret this poem's stylistic features from the aspects of grammar,phonology,image,theme and narrative point of view.Through the stylistic analysis with the method of deviation,its solemn theme is exposed clearly. 展开更多
关键词 STYLISTIC analysis deviation LOVE DEATH
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Edge detection in the potential field using the correlation coefficients of multidirectional standard deviations 被引量:5
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作者 徐梦龙 杨长保 +2 位作者 吴燕冈 陈竞一 郇恒飞 《Applied Geophysics》 SCIE CSCD 2015年第1期23-34,120,121,共14页
Most edge-detection methods rely on calculating gradient derivatives of the potential field, a process that is easily affected by noise and is therefore of low stability. We propose a new edge-detection method named c... Most edge-detection methods rely on calculating gradient derivatives of the potential field, a process that is easily affected by noise and is therefore of low stability. We propose a new edge-detection method named correlation coefficient of multidirectional standard deviations(CCMS) that is solely based on statistics. First, we prove the reliability of the proposed method using a single model and then a combination of models. The proposed method is evaluated by comparing the results with those obtained by other edge-detection methods. The CCMS method offers outstanding recognition, retains the sharpness of details, and has low sensitivity to noise. We also applied the CCMS method to Bouguer anomaly data of a potash deposit in Laos. The applicability of the CCMS method is shown by comparing the inferred tectonic framework to that inferred from remote sensing(RS) data. 展开更多
关键词 Edge detection Correlation coefficient multidirectional standard deviation Bouguer anomaly
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Deviation Theories and Applications in Poetry Analysis
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作者 肖蓉 《科技信息》 2011年第8期I0142-I0142,共1页
Poetry is prominent for its stylistic characteristics since texts themselves are the carrier of meaning,an analysis of the stylistic features of poems is conducive to the understanding and interpretation of them.It is... Poetry is prominent for its stylistic characteristics since texts themselves are the carrier of meaning,an analysis of the stylistic features of poems is conducive to the understanding and interpretation of them.It is of great significance to learn something about stylistics if we want to explore the meaning of poetry,this kind of method can also be used to analyze other literary works. 展开更多
关键词 诗歌 英语 文学作品 分析方法
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LARGE DEVIATIONS AND MODERATE DEVIATIONS FOR m-NEGATIVELY ASSOCIATED RANDOM VARIABLES 被引量:8
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作者 胡亦钧 明瑞星 杨文权 《Acta Mathematica Scientia》 SCIE CSCD 2007年第4期886-896,共11页
M-negatively associated random variables, which generalizes the classical one of negatively associated random variables and includes m-dependent sequences as its particular case, are introduced and studied. Large devi... M-negatively associated random variables, which generalizes the classical one of negatively associated random variables and includes m-dependent sequences as its particular case, are introduced and studied. Large deviation principles and moderate deviation upper bounds for stationary m-negatively associated random variables are proved. Kolmogorov-type and Marcinkiewicz-type strong laws of large numbers as well as the three series theorem for m-negatively associated random variables are also given. 展开更多
关键词 negatively associated random variables stationary sequence strong law of large numbers large deviations moderate deviations
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MODERATE DEVIATIONS AND LARGEDE VIATIONS FOR A TEST OF SYMMETRY BASED ON KERNEL DENSITY ESTIMATOR 被引量:5
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作者 何晓霞 高付清 《Acta Mathematica Scientia》 SCIE CSCD 2008年第3期665-674,共10页
Let fn be a non-parametric kernel density estimator based on a kernel function K. and a sequence of independent and identically distributed random variables taking values in R. The goal of this article is to prove mod... Let fn be a non-parametric kernel density estimator based on a kernel function K. and a sequence of independent and identically distributed random variables taking values in R. The goal of this article is to prove moderate deviations and large deviations for the statistic sup |fn(x) - fn(-x) |. 展开更多
关键词 Symmetry test kernel estimator moderate deviations large deviations
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基于医疗服务半径的中医类医疗机构空间配置及优化研究:以广州市增城区为例
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作者 李成程 周尚成 +4 位作者 贺凯玥 刘爱玲 梁珊珊 高婧 钟艾霖 《中国全科医学》 CAS 北大核心 2025年第2期234-241,共8页
背景随着中国传统医学纳入国际疾病分类第十一次修订本(ICD-11)编码,基层中医医疗资源的合理配置是推动中西医融合和优质医疗资源全民覆盖的保障。基层医疗机构布局和服务能力不均衡,导致城市乡镇地区普遍存在医疗资源供需错位问题。目... 背景随着中国传统医学纳入国际疾病分类第十一次修订本(ICD-11)编码,基层中医医疗资源的合理配置是推动中西医融合和优质医疗资源全民覆盖的保障。基层医疗机构布局和服务能力不均衡,导致城市乡镇地区普遍存在医疗资源供需错位问题。目的了解我国乡镇中医药服务开展状况,科学评价基层中医药诊疗的覆盖范围和服务可及性,为优化基层中医药服务空间资源配置提供新思路并据此提出优化策略。方法基于第七次全国人口普查数据和点状地理空间数据,引入医疗服务半径概念来计算步行模式下不同层级中医类医疗机构的诊疗范围。采用空间核密度指数、空间标准差椭圆等方法揭示中医类医疗服务供需能力的空间公平性。基于以上结果提出中医类医疗资源布局优化类型及措施。结果截至2022年增城区共计医疗机构699家,其中带有床位的中医类医疗机构18家,不同乡镇、街道的中医类医疗机构床位分布呈现出较大的差异。中滩镇千人口床位数为14.31张,在所有街道中排在第一位。永宁街道千人口床位数排在末位,仅为0.89张。增城区中医类医疗机构呈现出明显的双中心格局,中新镇中部、派潭镇北部和石滩镇西南部居民的中医药服务可获得性较弱。不同乡镇的中医药服务供给能力差别较大,中医类医疗机构空间分布同城镇居民的整体空间聚集程度还存在一定程度的不吻合,不同乡镇间的中医药服务半径存在差异。结论中医药发展战略实施以来,中国传统医学得到了保护和发展。应当采取更为科学的策略将中医药服务同城市发展和居民需求紧密结合,积极采取增加设施点、资源转移和下沉相结合、跨区域的中医药信息化联合诊疗的差异化策略,逐步实现真正意义上的全覆盖和中西医并重的战略。 展开更多
关键词 中医医疗机构 医疗服务半径 基层中医药服务 空间标准差椭圆 空间优化
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青少年特发性脊柱侧凸患者步态参数、肌肉参数与影像学的相关性
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作者 刘静 徐纯鑫 +4 位作者 陆洋阳 瞿沁泉 朱琪 郭玉兰 沈敏 《中国组织工程研究》 CAS 北大核心 2025年第21期4477-4485,共9页
背景:步态分析作为一种没有辐射的动态评估方法,可以辅助影像学检查对脊柱侧凸患者进行评估,从而减少辐射暴露。目的:分析青少年特发性脊柱侧凸患者步态参数与影像学参数的相关性,并通过OpenSim仿真建模初步探索潜在机制。方法:选取Cobb... 背景:步态分析作为一种没有辐射的动态评估方法,可以辅助影像学检查对脊柱侧凸患者进行评估,从而减少辐射暴露。目的:分析青少年特发性脊柱侧凸患者步态参数与影像学参数的相关性,并通过OpenSim仿真建模初步探索潜在机制。方法:选取Cobb角10°-45°、年龄10-18岁的青少年特发性脊柱侧弯患者20例为青少年特发性脊柱侧凸组;对照组是同年龄阶段,且相同体质量指数区间的正常儿童,共计纳入40例受试者。比较两组受试者步行时空参数、运动学参数、动力学参数及步态偏差指数的差异,探索病理步态与冠状面平衡的相关性,并对相关机制进行初步研究。结果与结论:(1)步态参数组间比较结果表明,青少年特发性脊柱侧凸组患者左侧支撑相、左侧双支撑相占整个步态周期的百分比增加,同时左侧摆动相占整个步态周期的百分比减少(P <0.05);青少年特发性脊柱侧凸组患者左侧髋关节最大内收角度大于对照组,双侧髋关节最大外展角度明显小于对照组(P <0.05);两组双侧足跟初始着地时踝关节角度相比差异有显著性意义(P <0.05);青少年特发性脊柱侧凸患者蹬离地面时右侧髋关节屈曲肌群峰值功率显著变小(P <0.05);(2)相关性研究结果显示,右侧髋关节最大外展角度与Cobb角呈显著正相关(r=0.552,P=0.012),右侧髋关节屈曲肌群峰值功率和C7侧方偏移呈显著负相关(r=-0.475,P=0.034),左侧足跟着地时踝关节角度与冠状面骨盆倾斜度呈显著正相关(r=0.476,P=0.034);(3)肌肉长度模拟计算结果表明,青少年特发性脊柱侧凸患者臀中肌肌纤维长度变化显著减少(P <0.05),双侧腹内斜肌肌纤维长度变化显著减少(P <0.05);比较两组受试者在足跟着地时的肌纤维长度发现,青少年特发性脊柱侧凸患者足跟初始着地时腓肠肌内外侧头和比目鱼肌的肌纤维长度均变短(P <0.05);(4)结果发现,青少年特发性脊柱侧凸患者躯干的姿势稳定性控制下降,表现为步频变慢、支撑相双支撑相百分比增加及摆动相百分比减少;普遍存在低足跟着地模式,是由双侧跟腱紧张引起的;青少年特发性脊柱侧凸患者存在髋屈曲肌群做功能力下降,可能与关节角速度及主弯方向相关。 展开更多
关键词 青少年特发性脊柱侧凸 步态参数 步态偏差指数 冠状面平衡 OpenSim 肌肉参数 影像学 三维步态分析
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An Analysis of the Linguistic Deviation in Chapter X of Oliver Twist 被引量:3
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作者 刘聪 《海外英语》 2013年第19期239-241,277,共4页
Charles Dickens is one of the greatest critical realist writers of the Victorian Age.In language,he is often compared with William Shakespeare for his adeptness with the vernacular and large vocabulary.Charles Dickens... Charles Dickens is one of the greatest critical realist writers of the Victorian Age.In language,he is often compared with William Shakespeare for his adeptness with the vernacular and large vocabulary.Charles Dickens achieved a recognizable place among English writers through the use of the stylistic features in his fictional language.Oliver Twist is the best representative of Charles Dickens’style,which makes it the most appropriate choice for the present stylistic study on Charles Dickens.No one who has ever read the dehumanizing workhouse scenes of Oliver Twist and the dark,criminal underworld life can forget them.This thesis attempts to investigate Oliver Twist through the approach of modern stylistics,particularly the theory of linguistic devia tion.This thesis consists of an introduction,the main body and a conclusion.The introduction offers a brief summary of the com ments on Charles Dickens and Chapter X of Oliver Twist,introduces the newly rising linguistic deviation theories,and brings about the theories on which this thesis settles.The main body explores the deviation effects produced from four aspects:lexical deviation,grammatical deviation,graphological deviation,and semantic deviation.It endeavors to show Dickens’manipulating language and the effects achieved through this manipulation.The conclusion mainly sums up the previous analysis,and reveals the theme of the novel,positive effect of linguistic deviation and significance of deviation application. 展开更多
关键词 deviation LEXICAL GRAMMATICAL graphological semant
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MODERATE DEVIATIONS FOR PARAMETER ESTIMATORS IN FRACTIONAL ORNSTEIN-UHLENBECK PROCESS 被引量:4
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作者 高付清 蒋辉 汪宝彬 《Acta Mathematica Scientia》 SCIE CSCD 2010年第4期1125-1133,共9页
We study moderate deviations for estimators of the drift parameter of the fractional Ornstein-Uhlenbeck process. Two moderate deviation principles are obtained.
关键词 Large deviations moderate deviations Ornstein-Uhlenbeck process
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Welding deviation detection method based on weld pool image contour features 被引量:6
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作者 Zhu Yanjun Wu Zhisheng +1 位作者 Li Ke Yang Peixin 《China Welding》 EI CAS 2019年第2期35-44,共10页
Automatic on-line detection of welding deviation based on machine vision is one of the key technologies of arc welding robot tracking welding,in which obtaining high quality weld pool image and accurate welding deviat... Automatic on-line detection of welding deviation based on machine vision is one of the key technologies of arc welding robot tracking welding,in which obtaining high quality weld pool image and accurate welding deviation detection algorithm are two important steps of tracking welding.Through the research and analysis of the weld pool image of gas metal arc welding(GMAW),it was found that the weld pool contains abundant welding information.First,the average gray value of the weld pool image can reflect the interference degree of arc to weld pool image and the heat input of welding process.Secondly,the tip of the weld pool image contour can reflect the center of the groove gap.Finally,the horizontal distance between the center coordinate of the wire contour and the tip coordinate of the weld pool image contour can reflect the welding deviation.On the basis of analyzing the characteristics of weld pool image,this paper proposes a new method of weld seam deviation detection,which includes the collection of weld pool image,image preprocessing,contour extraction and deviation calculation.The results of the tests and analyses showed that the maximum error of the on-line welding deviation obtained was about 2 pixels(0.17 mm)when the welding speed was≤60 cm/min,and the algorithm was stable enough to meet the requirements of real-time deviation detection for I-groove butt welding.The method can be applied to the on-line automatic welding deviation detection of arc welding robot. 展开更多
关键词 I-groove WELD POOL IMAGE deviation detection ALGORITHM
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RELATIVE ENTROPY AND LARGE DEVIATIONS UNDER SUBLINEAR EXPECTATIONS 被引量:6
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作者 高付清 徐明周 《Acta Mathematica Scientia》 SCIE CSCD 2012年第5期1826-1834,共9页
We give a definition of relative entropy with respect to a sublinear expectation and establish large deviation principle for the empirical measures for independent random variables under the sublinear expectation.
关键词 sublinear expectation relative entropy large deviation empirical measure
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Using the Method of Maximizing Deviation to Make Decision for M ultiindices 被引量:11
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作者 Wang Yingming Department of Automation, Xiamen University, 361005, P. R. China 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 1997年第3期21-26,共6页
This paper takes the synthesizing evaluation about industrial economic benefits by examples and proposes a new method named maximizing deviation method for multiindices decision. The new method can automatically deter... This paper takes the synthesizing evaluation about industrial economic benefits by examples and proposes a new method named maximizing deviation method for multiindices decision. The new method can automatically determine the weight coefficients among the multiindices and also can obtain the exact and reliable evaluation results without subjectivity. 展开更多
关键词 Multiindices decision Multiindices ranking Economic benefits evaluation Maximizing deviation method.
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LARGE DEVIATIONS FOR SOME DEPENDENT SEQUENCES 被引量:6
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作者 胡舒合 王学军 《Acta Mathematica Scientia》 SCIE CSCD 2008年第2期295-300,共6页
Let (Xi) be a martingale difference sequence and Sn=∑^ni=1Xi Suppose (Xi) i=1 is bounded in L^p. In the case p ≥2, Lesigne and Volny (Stochastic Process. Appl. 96 (2001) 143) obtained the estimation μ(Sn ... Let (Xi) be a martingale difference sequence and Sn=∑^ni=1Xi Suppose (Xi) i=1 is bounded in L^p. In the case p ≥2, Lesigne and Volny (Stochastic Process. Appl. 96 (2001) 143) obtained the estimation μ(Sn 〉 n) ≤ cn^-p/2, Yulin Li (Statist. Probab. Lett. 62 (2003) 317) generalized the result to the case when p ∈ (1,2] and obtained μ(Sn 〉 n) ≤ cn^l-p, these are optimal in a certain sense. In this article, the authors study the large deviation of Sn for some dependent sequences and obtain the same order optimal upper bounds for μ(Sn 〉 n) as those for martingale difference sequence. 展开更多
关键词 Large deviation φ-mixing sequence NA sequence linear process
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Welding Deviation Detection Algorithm Based on Extremum of Molten Pool Image Contour 被引量:12
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作者 ZOU Yong JIANG Lipei +3 位作者 LI Yunhua XUE Long HUANG Junfen HUANG Jiqiang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2016年第1期74-83,共10页
The welding deviation detection is the basis of robotic tracking welding, but the on-line real-time measurement of welding deviation is still not well solved by the existing methods. There is plenty of information in ... The welding deviation detection is the basis of robotic tracking welding, but the on-line real-time measurement of welding deviation is still not well solved by the existing methods. There is plenty of information in the gas metal arc welding(GMAW) molten pool images that is very important for the control of welding seam tracking. The physical meaning for the curvature extremum of molten pool contour is revealed by researching the molten pool images, that is, the deviation information points of welding wire center and the molten tip center are the maxima and the local maxima of the contour curvature, and the horizontal welding deviation is the position difference of these two extremum points. A new method of weld deviation detection is presented, including the process of preprocessing molten pool images, extracting and segmenting the contours, obtaining the contour extremum points, and calculating the welding deviation, etc. Extracting the contours is the premise, segmenting the contour lines is the foundation, and obtaining the contour extremum points is the key. The contour images can be extracted with the method of discrete dyadic wavelet transform, which is divided into two sub contours including welding wire and molten tip separately. The curvature value of each point of the two sub contour lines is calculated based on the approximate curvature formula of multi-points for plane curve, and the two points of the curvature extremum are the characteristics needed for the welding deviation calculation. The results of the tests and analyses show that the maximum error of the obtained on-line welding deviation is 2 pixels(0.16 ram), and the algorithm is stable enough to meet the requirements of the pipeline in real-time control at a speed of less than 500 mm/min. The method can be applied to the on-line automatic welding deviation detection. 展开更多
关键词 welding deviation welding seam tracking molten pool contour curvature extremum gas metal arc welding(GMAW)
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Efficient Deviation Detection Between a Process Model and Event Logs 被引量:4
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作者 Lu Wang Yuyue Du Liang Qi 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2019年第6期1352-1364,共13页
Business processes described by formal or semi-formal models are realized via information systems.Event logs generated from these systems are probably not consistent with the existing models due to insufficient design... Business processes described by formal or semi-formal models are realized via information systems.Event logs generated from these systems are probably not consistent with the existing models due to insufficient design of the information system or the system upgrade.By comparing an existing process model with event logs,we can detect inconsistencies called deviations,verify and extend the business process model,and accordingly improve the business process.In this paper,some abnormal activities in business processes are formally defined based on Petri nets.An efficient approach to detect deviations between the process model and event logs is proposed.Then,business process models are revised when abnormal activities exist.A clinical process in a healthcare information system is used as a case study to illustrate our work.Experimental results show the effectiveness and efficiency of the proposed approach. 展开更多
关键词 DETECT deviationS event LOG MODEL repair PETRI net process MODEL
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