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Learning a graph-based classifier for fault localization

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Science China(Information Sciences) 2020年第6期63卷 195-216页

作者： Hao zhong Hong MEI Department of Computer Science and Engineering Shanghai Jiao Tong University

Because software emerged, locating software faults has been intensively researched, culminating in various approaches and tools that have been applied in real development. Despite the success of these developments, improved tools are still demanded by programmers. Meanwhile, some programmers are reluctant to use any tools when locating faults in their development. The state-of-the-art situation can be naturally improved by learning how programmers locate faults. The rapid development of open-source software has accumulated many bug fixes. A bug fix is a specific type of comments containing a set of buggy files and their corresponding fixed files, which reveal how programmers repair bugs. Feasibly, an automatic model can learn fault locations from bug fixes, but prior attempts to achieve this vision have been prevented by various technical challenges. For example, most bug fixes are not compilable after checking out, which hinders analyzing bug fixes by most advanced static/dynamic tools. This paper proposes an approach called ClaFa that trains a graph-based fault classifier from bug fixes. ClaFa is built on a recent partial-code tool called Grapa, which enables the analysis of partial programs by the complete code tool called WALA. Once Grapa has built a program dependency graph from a bug fix, ClaFa compares the graph from the buggy code with the graph from the fixed code, locates the buggy nodes, and extracts the various graph features of the buggy and clean nodes. Based on the extraction result, ClaFa trains a classifier that combines Adaboost and decision tree learning. The trained ClaFa can predict whether a node of a program dependency graph is buggy or *** evaluate ClaFa on thousands of buggy files collected from four open-source projects: Aries, Mahout,Derby, and Cassandra. The f-scores of ClaFa achieves are approximately 80% on all projects.

关键词： fault classifier partial code analysis bug fix analysis

Transition characteristics for a small tail-sitter unmanned aerial vehicle

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Chinese Journal of Aeronautics 2021年第10期34卷 220-236页

作者： Jingyang zhong Chen WANG School of Construction Machinery Chang'an UniversityXi'an 710061China

Research on the transition phase of tail-sitter Unmanned Aerial Vehicles(UAVs)is crucial for trajectory planning and performance *** study focuses on the analysis of the transition characteristics and path of a small dual-rotor tail-sitter UAV,including static and dynamic *** system input time delay and actuator dynamics are specifically considered during the dynamic analysis,and these actual physical properties ensure that the computation results are reliable and *** UAV steady-state limit is obtained through static analysis,which is also adopted to verify the correctness of the dynamic *** regard to the dynamic analysis,several typical transition approaches are computed based on different initial states and optimization objective functions,and the different computations are applicable under specific task *** off-line dynamic results of the transition path and actuator output sequence could also be adopted as reference values for the transition process during real flight.A comparison of the static and dynamic results illustrates the necessity of combining these two methods for UAV transition characteristic ***,the UAV conceptual parameters related to the transition path are also studied,and the obtained quantitative characteristics provide feedback for the UAV conceptual design.

关键词： Actuator dynamics Tail-sitter Time delay Transition analysis UAV

Iterative Learning Disturbance Observer Based Attitude Stabilization of Flexible Spacecraft Subject to Complex Disturbances and Measurement Noises

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IEEE/CAA Journal of Automatica Sinica 2021年第9期8卷 1576-1587页

作者： Tongfu He zhong Wu School of Instrumentation and Optoelectronics Engineering Beihang UniversityBeijing 100191China

To realize high-precision attitude stabilization of a flexible spacecraft in the presence of complex disturbances and measurement noises,an iterative learning disturbance observer(ILDO)is presented in this ***,a dynamic model of disturbance is built by augmenting the integral of the lumped disturbance as a *** on it,ILDO is designed by introducing iterative learning ***,comparative analyses of ILDO and traditional disturbance observers are carried out in frequency *** demonstrates that ILDO combines the advantages of high accuracy in disturbance estimation and favorable robustness to measurement *** that,an ILDO based composite controller is designed to stabilize the spacecraft ***,the effectiveness of the proposed control scheme is verified by simulations.

关键词： Disturbance observer iterative learning measure-ment noise spacecraft attitude control

Cavitation-induced damage model of soft materials in exposure to high-intensity focused ultrasound

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Acta Mechanica Sinica 2020年第5期36卷 1058-1064,I0002页

作者： Qinyi Huang Zheng zhong School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092China School of Science Harbin Institute of TechnologyShenzhen 518055China

High-intensity focused ultrasound can drive cavitation bubbles that damage soft materials.A cavitation-induced damage model is developed to study the mechanical damage of soft materials by high-intensity focused *** on the thermodynamics framework with the acoustic radiation stress theory and the nonlinear elasticity theory,an internal variable which reflects the mechanical damage caused by cavitation bubbles is incorporated into the Helmholtz free *** evolution of material damages for tissue-mimicking gel is established,which is related to the cavitation process and the mechanical dissipation from a macroscopic *** theoretical model is then applied to analyze the material damaged area observed in the experiment and the theoretical prediction is found in agreement with the existing experimental results,which shows that the damage induced by cavitation bubbles develops rapidly,then slow down and finally reaches a plateau.

关键词： Acoustomechanics Thermodynamics Cavitation damage Energy dissipation Tissue-mimicking gel

Modeling and Simulation of Lithium Vacuum Evaporation Process Using COMSOL Multiphysics

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Journal of Thermal Science 2024年第1期33卷 86-100页

作者： LIAN Xuexin zhong Dawen Beijing Key Laboratory of Passive Nuclear Power Safety and Technology North China Electric Power UniversityBeijing 102206China

Based on the COMSOL Multiphysics simulation software,this study carried out modeling and numerical simulation for the evaporation process of liquid metal lithium in the vacuum free molecular flow *** motion of lithium atoms in the evaporation process was analyzed through a succession of *** on the available experimental values of the saturated vapor pressure of liquid metal lithium,the relationship between saturated vapor pressure and temperature of liquid lithium in the range of 600 K-900 K was obtained.A two-dimensional symmetric model(3.5 mm×20 mm) was established to simulate the transient evaporation process of liquid lithium at wall temperatures of 750 K,780 K,800 K,810 K,825 K,and 850 K,*** effects of temperature,the evaporation coefficient,back pressure,and length-to-diameter ratio on the evaporation process were studied;the variation trends and reasons of the molecular flux and the pressure during the evaporation process were *** the same time,the evaporation process under variable wall temperature conditions was *** research made the evaporation process of liquid lithium in vacuum molecular flow clearer,and provided theoretical support for the space reactor and nuclear fusion related fields.

关键词： free molecular flow saturated vapor pressure vacuum evaporation liquid lithium metal

The capillary pressure curves from upscaling interfacial and unsaturated flows in porous layers with vertical heterogeneity

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Theoretical & Applied Mechanics Letters 2023年第4期13卷 287-290页

作者： zhong Zheng State Key Laboratory of Ocean Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China MOE Key Laboratory of Hydrodynamics School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

We provide the capillary pressure curves p_(c)(s)as a function of the effective saturation s based on the theoretical framework of upscaling unsaturated flows in vertically heterogeneous porous layers proposed recently(***,Journal of Fluid Mechanics,950,A17,2022).Based on the assumption of vertical gravitational-capillary equilibrium,the saturation distribution and profile shape of the invading fluid can be obtained by solving a nonlinear integral-differential *** capillary pressure curves p_(c)(s)can then be constructed by systematically varying the injection *** with the relative permeability curves k_(rn)(s)that are already *** can now provide quick estimates on the overall behaviours of interfacial and unsaturated flows in vertically-heterogeneous porous layers.

关键词： Flow upscaling Interfacial and unsaturated flow Wetting and capillary effects Porous layer Heterogeneity

Two-dimensional face stability analysis in rock masses governed by the Hoek-Brown strength criterion with a new multi-horn mechanism

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International Journal of Mining Science and Technology 2023年第8期33卷 963-976页

作者： Junhao zhong Xiaoli Yang School of Civil Engineering Central South UniversityChangsha 410075China

The face stability problem is a major concern for tunnels excavated in rock masses governed by the Hoek-Brown strength *** provide an accurate prediction for the theoretical solution of the critical face pressure,this study adopts the piecewise linear method(PLM)to account for the nonlinearity of the strength envelope and proposes a new multi-horn rotational mechanism based on the Hoek-Brown strength criterion and the associative flow *** analytical solution of critical support pressure is derived from the energy-work balance equation in the framework of the plastic limit theorem;it is formulated as a multivariable nonlinear optimization problem relying on 2m dependent variables(m is the number of segments).Meanwhile,two classic linearized measures,the generalized tangential technique(GTT)and equivalent Mohr-Coulomb parameters method(EMM),are incorporated into the analysis for ***,the parametric study indicates a significant improvement in support pressure by up to 13%compared with the GTT,and as expected,the stability of the tunnel face is greatly influenced by the rock strength *** stress distribution on the rupture surface is calculated to gain an intuitive understanding of the failure at the limit *** the limit analysis is incapable of calculating the true stress distribution in rock masses,a rough approximation of the stress vector on the rupture surface is *** the end,sets of normalized face pressure are provided in the form of charts for a quick assessment of face stability in rock masses.

关键词： Face stability Piecewise linear method Hoek-Brown strength criterion Multi-horn rotational mechanism Limit analysis

An Ensemble Tree Classifier for Highly Imbalanced Data Classification

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Journal of Systems Science & Complexity 2021年第6期34卷 2250-2266页

作者： SHI Peibei WANG zhong School of Computer Science and Technology Hefei Normal UniversityHefei 230601China

The performance of traditional imbalanced classification algorithms is degraded when dealing with highly imbalanced *** to deal with highly imbalanced data is a difficult *** this paper,the authors propose an ensemble tree classifier for highly imbalanced data *** ensemble tree classifier is constructed with a complete binary tree structure.A mathematical model is established based on the features and classification performance of the classifier,and it is proven that the model parameters of the ensemble classifier can be solved by ***,the AdaBoost method is used as the benchmark classifier to construct the tree structure ***,the classification cost of the model is calculated,and the quantitative mathematical description between the cost and features of the ensemble tree classifier model is ***,the cost of the classification model is transformed into an optimization problem,and the parameters of the integrated tree classifier are given through theoretical *** approach is tested on several highly imbalanced datasets in different fields and takes the AUC(area under the curve)and F-measure as evaluation *** with the traditional imbalanced classification algorithm,the ensemble tree classifier has better classification performance.

关键词： Ensemble learning F-measure imbalanced classification mathematical model

Simple and Ultrahigh Efficient Superhydrophilic Polydopamine-coated TiO_(2) Cotton for Oil-water Separation

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Journal of Bionic Engineering 2023年第3期20卷 900-909页

作者： Xin zhong Zhiguang Guo Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials Hubei UniversityWuhan430062China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou730000China

Oil–water mixing has brought many problems to a society, and it is of great significance to develop a simple, convenient, efficient, and durable separation material to solve the problem of oil–water mixing. In this paper, modified cottons were successfully prepared using polydopamine as the in situ mineralization site of TiO_(2) nanoparticles combined with synergistic crosslinking with KH550. A large number of hydrophilic groups endowed the cotton with superhydrophilic ability, which greatly shortened its water spreading time. The prepared modified cotton could be successfully separated from oil and water, and still had a separation efficiency of 99.999% after 50 cycles. In addition, after 24 h immersion in 1 M HCl, NaOH, and NaCl solutions and 50 abrasion experiments, the modified cotton showed excellent oil–water separation ability, and the separation efficiency was above 99.990%. Successfully provided a simple preparation method to prepare high-efficiency and clean cottons for oil–water separation.

关键词： Oil-water separation Superhydrophilicity Cotton Polydopamine