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Estimating Subdivision Depth of Catmull-Clark Surfaces

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Journal of Computer Science & Technology 2004年第5期19卷 657-664页

作者： Hua-WeiWang kai-HuaiQin DepartmentofComputerScienceandTechnology TsinghuaUniversityBeijing100083P.R.China

In this paper, both general and exponential bounds of the distance between a uniform Catmull-Clark surface and its control polyhedron are derived. The exponential bound is independent of the process of subdivision and can be evaluated without recursive subdivision. Based on the exponential bound, we can predict the depth of subdivision within a user-specified error tolerance. This is quite useful and important for pre-computing the subdivision depth of subdivision surfaces in many engineering applications such as surface/surface intersection, mesh generation, numerical control machining and surface rendering.

关键词： Catmull-Clark surface subdivision depth control polyhedron approximation error

Evolvable dialogue state tracking for statistical dialogue management

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Frontiers of Computer Science 2016年第2期10卷 201-215页

作者： kai YU Lu CHEN kai SUN Qizhe XIE Su ZHU Key Laboratory of Shanghai Education Commission for Intelligent Interaction and Cognitive EngineeringSpeechLab Department of Computer Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China Department of Computer Science Cornell University Ithaca NY 14853 USA

Statistical dialogue management is the core of cognitive spoken dialogue systems （SDS） and has attracted great research interest. In recent years, SDS with the ability of evolution is of particular interest and becomes the cuttingedge of SDS research. Dialogue state tracking （DST） is a process to estimate the distribution of the dialogue states at each dialogue turn, given the previous interaction history. It plays an important role in statistical dialogue management. To provide a common testbed for advancing the research of DST, international DST challenges （DSTC） have been organised and well-attended by major SDS groups in the world. This paper reviews recent progresses on rule-based and statistical approaches during the challenges. In particular, this paper is focused on evolvable DST approaches for dialogue domain extension. The two primary aspects for evolution, semantic parsing and tracker, are discussed. Semantic enhancement and a DST framework which bridges rule-based and statistical models are introduced in detail. By effectively incorporating prior knowledge of dialogue state transition and the ability of being data-driven, the new framework supports reliable domain extension with little data and can continuously improve with more data available. This makes it excellent candidate for DST evolution. Experiments show that the evolvable DST approaches can achieve the state-of-the-art performance and outperform all previously submitted trackers in the third DSTC.

关键词： dialogue management domain extension,evolvable dialogue state tracking parser tracker

Concise review of relaxations and approximation algorithms for nonidentical parallel-machine scheduling to minimize total weighted completion times

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Journal of Systems Engineering and Electronics 2008年第4期19卷 827-834页

作者： Li kai Yang Shanlin School of Management Hefei Univ. of Technology Hefei 230009 P. R. China

A class of nonidentical parallel machine scheduling problems are considered in which the goal is to minimize the total weighted completion time. Models and relaxations are collected. Most of these problems are NP-hard, in the strong sense, or open problems, therefore approximation algorithms are studied. The review reveals that there exist some potential areas worthy of further research.

关键词： parallel machine scheduling review total weighted completion time relaxation algorithm

Optimization of SVC settings to improve post-fault voltage recovery and angular stability

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Journal of Modern Power Systems and Clean Energy 2019年第3期7卷 491-499页

作者： Weihong HUANG kai SUN The Department of Electrical Engineering and Computer Science The University of Tennessee

In this paper, controller parameters of static var compensators(SVCs) at planned locations are optimized to mitigate fault-induced delayed voltage recovery issues and improve angular stability of a multi-machine power system. The problem is formulated as a nonlinear optimization problem involving constraints on post-fault trajectories of voltages and frequencies. This paper proposes a mesh adaptive direct search based algorithm interfaced with a power system simulator for the optimization of SVC controllerparameters. The proposed method is tested on an NPCC140-bus system to optimize controller parameters for three SVCs. Simulations on critical contingencies verify that post-fault transient voltages and generator speeds can both quickly recover and transient stability of the system is improved.

关键词： Static var compensator (SVC) Fault-induced delayed voltage recover issue(FIDVR) Angular stability Mesh adaptive direct search(MADS) algorithm

Drag Effects of Solute and Second Phase Distributions on the Grain Growth Kinetics of Pre-Extruded Mg-6Zn Alloy

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Journal of Materials Science & Technology 2016年第12期32卷 1260-1266页

作者： Zhaoyang Jin Donghua Yu Xintong Wu kai Yin kai Yan College of Mechanical Engineering Yangzhou University

In order to control the grain size during hot forming,grain growth behavior of a pre-extruded Mg-6Zn magnesium alloy and its correlation with solute and second phase distribution were *** annealing was conducted on a Gleeble-1500 thermo-mechanical *** mean grain size Dg of each annealed specimen was measured by the quantitative metallography *** grain growth kinetics of the Mg-6Zn alloy annealed at 473-623 K was obtained as Dg^4- Dg0^4=2.25 ×10^11 exp（-95450）by the least square linear regression *** deviation of grain growth exponent n = 4 from the theoretical value of 2 may be attributed to the presence of solute zinc and second phases which will retard the boundary *** observations show that the non-uniform distribution of grain size for samples pre-extruded or annealed at low temperatures is closely related to the non-uniform distribution of fine and dispersed second phases but not to the non-uniform distribution of solute *** indicates that second phase pinning effect plays an important role in microstructure refinement.

关键词： Grain growth kinetics Second phase distribution Solute dragging Magnesium alloys

Fuzzy Clustering with the Structural α-Entropy

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Chinese Journal of Electronics 2018年第6期27卷 1118-1125页

作者： LI kai GAO Yan School of Cyber Security and Computer Hebei University

We study fuzzy clustering with the structural α-entropy and present a unified framework for fuzzy clustering with fuzzy entropy, which can be regarded fuzzy clustering with fuzzy entropy as its special case. Then,aiming at weighting exponent m equal to the structuralα-entropy index α in the presented unified framework, we obtain the fuzzy membership degrees and cluster centers using Lagrange method. Further, we propose the Structural α-entropy based fuzzy c-means(SEFCM) ***, to solve clustering of the complicated data, we also present the Structural α-entropy based kernel fuzzy c-means(SEKFCM) algorithm. In experiment, some University of California Irvine(UCI) data sets and synthetic data sets are used to test the performance of the presented algorithms and the role of the structural α-entropy. The experimental results show that the presented algorithms obtain better clustering result.

关键词： Structural α-entropy Unified framework Kernel function Fuzzy clustering Structural α-entropy based fuzzy c-means(SEFCM) algorithm Structural α-entropy based kernel fuzzy c-means(SEKFCM) algorithm

Oxidation behaviour of electron beam physical vapour deposition β-NiAlHf coatings at 1100℃ in dry and humid atmospheres

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Rare Metals 2016年第7期35卷 513-519页

作者： kai Yan Hong-Bo Guo Hui Peng Sheng-kai Gong School of Materials Science and Engineering Beihang University Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology Beihang University

NiA1 intermetallic compounds attract increas- ing attention for high-temperature applications due to their combination of excellent properties, especially as metallic protective coatings on superalloys or as bond coats in thermal barrier coatings （TBCs）. Oxidation behaviour of the β-NiA1Hf coatings prepared by electron beam physical vapour deposition （EB-PVD） was investigated at 1100 ℃ for short time and 100h in 20% 02＋Ar and 15 % H20 ＋ Ar, respectively. The results of mass changes re- veal that the addition of minor reactive element Hf sig- nificantly improves the cyclic oxidation resistance of the 13- NiA1 coatings in both dry and humid atmospheres. During the initial oxidation stage, water vapour retards the phase transformation from 0-A1203 to a-A1203. Moreover, com- pared with the case in dry atmosphere, water vapour sig- nificantly reduces the surface roughness of the oxide scales formed on EB-PVD β-NiA1Hf coatings after 100 h cyclic oxidation, which corresponds with the difference of surface morphologies of the oxide scales.

关键词： β-NiA1Hf coatings Water vapour Oxidation Phase transformation Roughness

RFID-based Production Data Analysis in an IoT-enabled Smart Job-shop

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IEEE/CAA Journal of Automatica Sinica 2018年第1期5卷 128-138页

作者： kai Ding Pingyu Jiang state key laboratory for manufacturing systems engineering xi’an jiaotong university Xi'an 710054 China

Under industry 4.0, internet of things(IoT), especially radio frequency identification(RFID) technology, has been widely applied in manufacturing environment. This technology can bring convenience to production control and production transparency. Meanwhile, it generates increasing production data that are sometimes discrete, uncorrelated, and hard-to-use. Thus,an efficient analysis method is needed to utilize the invaluable data. This work provides an RFID-based production data analysis method for production control in Io T-enabled smart *** physical configuration and operation logic of Io T-enabled smart job-shop production are firstly described. Based on that,an RFID-based production data model is built to formalize and correlate the heterogeneous production data. Then, an eventdriven RFID-based production data analysis method is proposed to construct the RFID events and judge the process command execution. Furthermore, a near big data approach is used to excavate hidden information and knowledge from the historical production data. A demonstrative case is studied to verify the feasibility of the proposed model and methods. It is expected that our work will provide a different insight into the RFIDbased production data analysis.

关键词： Data analysis internet of things(IoT) production control radio frequency identification(RFID) smart jobshop

Simulated annealing algorithm for detecting graph isomorphism

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Journal of Systems Engineering and Electronics 2008年第5期19卷 1047-1052页

作者： Geng Xiutang Zhang kai Dept. of Control Science and Engineering Huazhong Univ. of Science and Technology Wuhan 430074 P. R. China

Evolutionary computation techniques have mostly been used to solve various optimization problems, and it is well known that graph isomorphism problem （GIP） is a nondeterministic polynomial problem. A simulated annealing （SA） algorithm for detecting graph isomorphism is proposed, and the proposed SA algorithm is well suited to deal with random graphs with large size. To verify the validity of the proposed SA algorithm, simulations are performed on three pairs of small graphs and four pairs of large random graphs with edge densities 0.5, 0.1, and 0.01, respectively. The simulation results show that the proposed SA algorithm can detect graph isomorphism with a high probability.

关键词： graph isomorphism problem simulated annealing algorithm nondeterministic polynomial problem,local search.