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Learning Human-Written Commit Messages to Document Code Changes

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Journal of Computer Science & Technology 2020年第6期35卷 1258-1277页

作者： Yuan Huang Nan Jia Hao-Jie Zhou Xiang-Ping Chen Zi-Bin Zheng Ming-Dong Tang National Engineering Research Center of Digital Life School of Data and Computer ScienceSun Yat-sen University Guangzhou 510006China School of Information Engineering Hebei GEO UniversityShijiazhuang 050031China guangdong key laboratory for big data analysis and simulation of public opinion School of Communication and DesignSun Yat-sen UniversityGuangzhou 510006China School of Information Science and Technology Guangdong University of Foreign StudiesGuangzhou 510006China guangdong key laboratory of big data analysis and Processing Guangzhou 510006China

Commit messages are important complementary information used in understanding code changes. To address message scarcity, some work is proposed for automatically generating commit messages. However, most of these approaches focus on generating summary of the changed software entities at the superficial level, without considering the intent behind the code changes (e.g., the existing approaches cannot generate such message:"fixing 'null' pointer exception"). Considering developers often describe the intent behind the code change when writing the messages, we propose ChangeDoc, an approach to reuse existing messages in version control systems for automatical commit message generation. Our approach includes syntax, semantic, pre-syntax, and pre-semantic similarities. For a given commit without messages, it is able to discover its most similar past commit from a large commit repository, and recommend its message as the message of the given commit. Our repository contains half a million commits that were collected from SourceForge. We evaluate our approach on the commits from 10 projects. The results show that 21.5% of the recommended messages by ChangeDoc can be directly used without modification, and 62.8% require minor modifications. In order to evaluate the quality of the commit messages recommended by ChangeDoc, we performed two empirical studies involving a total of 40 participants (10 professional developers and 30 students). The results indicate that the recommended messages are very good approximations of the ones written by developers and often include important intent information that is not included in the messages generated by other tools.

关键词： commit message recommendation code syntax similarity code semantic similarity code change comprehension

Characterizing and Detecting Gas-Inefficient Patterns in Smart Contracts

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Journal of Computer Science & Technology 2022年第1期37卷 67-82页

作者： Que-Ping Kong Zi-Yan Wang Yuan Huang Xiang-Ping Chen Xiao-Cong Zhou Zi-Bin Zheng Gang Huang School of Computer Science and Engineering Sun Yat-sen UniversityGuangzhou 510006China School of Software Engineering Sun Yat-sen UniversityZhuhai 519082China guangdong key laboratory for big data analysis and simulation of public opinion School of Communication and DesignSun Yat-sen UniversityGuangzhou 510006China Peking University Shenzhen Graduate School Shenzhen 518000China

Ethereum blockchain is a new internetware with tens of millions of smart contracts running on *** from general programs,smart contracts are decentralized,tamper-resistant and permanently ***,to avoid resource abuse,Ethereum charges users for deploying and invoking smart contracts according to the size of contract and the operations executed by *** is necessary to optimize smart contracts to save ***,since developers are not familiar with the operating environment of smart contracts(i.e.,Ethereum virtual machine)or do not pay attention to resource consumption during development,there are many optimization opportunities for smart *** fill this gap,this paper defines six gas-inefficient patterns from more than 25,000 posts and proposes an optimization approach at the source code level to let users know clearly where the contract is *** evaluate the prevalence and economic benefits of gas-inefficient patterns,this paper conducts an empirical study on more than 160,000 real smart *** promising experimental results demonstrate that 52.75%of contracts contain at least one gas-inefficient pattern proposed in this *** these patterns are removed from the contract,at least 0.30 can be saved per contract.

关键词： smart contract anti-pattern detection optimization empirical study

Example-based web page recoloring method

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Frontiers of Computer Science 2020年第5期14卷 229-231页

作者： Yonghao Long Zhihao Zang Xiangping Chen Fan Zhou Xiaonan Luo School of data and Computer Science National Engineering Research Center of Digital LifeSun Yat-sen UniversityGuangzhou510006China guangdong key laboratory for big data analysis and simulation of public opinion The School of Communication and DesignSun Yat-sen UniversityGuangzhou510006China School of Computer Science and Information Security Guilin University of Electronic TechnologyGuilin541004China

1 Introduction The user interface(UI)is very important for a software product,and a well-designed UI will attract users and make a good *** has been shown that color plays an important role in invoking emotional reactions[1],influencing usability[2],forming first impressions[3],and affecting the energy cost of the UI[4].Generating satisfying color schemes has high requirements for experience,aesthetic,and creative inspiration of designers[5].

关键词： web coloring satisfying

Test-Driven Feature Extraction of Web Components

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Journal of Computer Science & Technology 2022年第2期37卷 389-404页

作者： Yong-Hao Long Yan-Cheng Chen Xiang-Ping Chen Xiao-Hong Shi Fan Zhou School of Computer Science and Engineering National Engineering Research Center of Digital Life Sun Yat-sen UniversityGuangzhou 510006China School of Design The Hong Kong Polytechnic UniversityHong KongChina guangdong key laboratory for big data analysis and simulation of public opinion The School of Communication and DesignSun Yat-sen UniversityGuangzhou 510006China School of Information Technology and Engineering Guangzhou College of CommerceGuangzhou 511363China

With the growing requirements of web applications,web components are developed to package the implementation of commonly-used features for *** some cases,the developer may want to reuse some features which cannot be customized by the component’s ***/she has to extract the implementation by *** is labor-intensive and *** the widely-used test cases which can be useful to specify the software features,a test-driven approach is proposed to extract the implementation of the desired features in web *** satisfaction of the user^requirements is transformed into the passing rate of user-specified test *** this way,the quality of the extraction result can be evaluated ***,a record/replay-based GUI test generation method is proposed to ensure that the extraction result has the correct GUI *** extract the feature implementation,a hierarchical genetic algorithm is proposed to find the code snippet that can pass all the tests and has the approximate smallest *** compare our method with two existing feature extraction *** result shows that our method can extract the correct implementation with the minimum size.A human-subject study is conducted to show the effectiveness and weaknesses of our method in helping users extract the features.

关键词： feature extraction genetic algorithm graphical user interface software reuse

Mining hourly population dynamics by activity type based on decomposition of sequential snapshot data

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International Journal of Digital Earth 2022年第1期15卷 1395-1416页

作者： Qingli Shi Li Zhuo Haiyan Tao Qiuping Li guangdong Provincial key laboratory of Urbanization and Geo-simulation School of Geography and PlanningSun Yat-sen UniversityGuangzhouPeople’s Republic of China guangdong Provincial Engineering Research Centre for public Security and Disaster GuangzhouPeople’s Republic of China Southern Marine Science and Engineering guangdong laboratory (Zhuhai) ZhuhaiPeople’s Republic of China

The dynamic population distributions by activity type(***,shopping or in-home)are vital for resource allocation,urban planning and epidemic *** studies have incorporated individual-level human mobility data to map population distribution by activity type,access to such data is hindered due to privacy issues and they rely on auxiliary data to provide priori activity *** paper presents a method for generating the population dynamics by activity *** first introduce more readily available sequential snapshot data to construct the population mixture model,then decompose the population mixture,and finally estimate the dynamic population size for each *** test the method in the central districts of Guangzhou city,China,based on real-time Tencent user density *** analysis and accuracy assessment prove that our method can accurately estimate hourly distributions for populations engaging in working,stay-at-home,and socializing *** temporal distribution of the working population reproduces the regular work scenarios and socializing population displays complex spatial *** also find that there is an underlying relationship between a region’s function and its dynamic population *** presented method has great potential for application and could provide new insight for studying urban dynamic functions.

关键词： Hourly population dynamics activity type population mixture model real-time Tencent user density data

Geography of Talent in China During 2000-2015:An Eigenvector Spatial Filtering Negative Binomial Approach

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Chinese Geographical Science 2021年第2期31卷 297-312页

作者： GU Hengyu Francisco ROWE LIU Ye SHEN Tiyan School of Government Peking UniversityBeijing 100871China Geographic data Science Lab Department of Geography and PlanningUniversity of LiverpoolLiverpool L69United Kingdom School of Geography and Planning Sun Yat-sen UniversityGuangzhou 510275China guangdong key laboratory for Urbanization and Geo-simulation Sun Yat-sen UniversityGuangzhou 510275China

The increase in China’s skilled labor force has drawn much attention from policymakers,national and international firms and *** how educated talent locates and re-locates across the country can guide future policy discussions of equality,firm localization and service *** studies have tended to adopt a static cross-national approach providing valuable insights into the relative importance of economic and amenity differentials driving the distribution of talent in ***,few adopt longitudinal analysis to examine the temporal dynamics in the stregnth of existing *** released official statistical data now enables space-time analysis of the geographic distribution of talent and its determinants in *** four-year city-level data from national population censuses and 1%population sample surveys conducted every five years between 2000 and 2015,we examine the spatial patterns of talent across Chinese cities and their underpinning drivers evolve over *** reveal that the spatial distribution of talent in China is persistently unequal and spatially concentrated between 2000 and *** also shows gradually strengthened and significantly positive spatial autocorrelation in the distribution of *** eigenvector spatial filtering negative binomial panel is employed to model the spatial determinants of talent *** indicate the influences of both economic opportunities and urban amenities,particularly urban public services and greening rate,on the distribution of *** results highlight that urban economic-and amenity-related factors have simultaneously driven China’s talent’s settlement patterns over the first fifteen years of the 21st century.

关键词： talent distribution determinants eigenvector spatial filtering panel data analysis China

A cellular automata downscaling based 1 km global land use datasets (2010–2100)

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Science Bulletin 2016年第21期61卷 1651-1661页

作者：李雪草俞乐徐伊迪杨军宫鹏 Terry Sohl Nicholas Clinton Wenyu Li Zhiliang Zhu Xiaoping Liu Ministry of Education key laboratory for Earth System Modeling Center for Earth System Science Tsinghua University Joint Center for Global Change Studies U.S. Geological Survey Earth Resources Observation and Science (EROS) Center U.S. Geological Survey School of Geography and Planning and Guangdong Key Laboratory for Urbanization and Geo-simulation Sun Yat-sen University

Global climate and environmental change studies require detailed land-use and land-cover （LULC） information about the past, present, and future. In this paper, we discuss a methodology for downscaling coarse-resolution （i.e., half-degree） future land use scenarios to finer （i.e., 1 km） resolutions at the global scale using a grid-based spatially explicit cellular automata （CA） model. We account for spatial heterogeneity from topography, climate, soils, and socioeconomic variables. The model uses a global 30 m land cover map （2010） as the base input, a variety of biogeographic and socioeconomic variables, and an empirical analysis to downscale coarse-resolution land use information （specifically urban, crop and pasture）. The output of this model offers the most current and finest-scale future LULC dynamics from 2010 to 2100 （with four representative concentration pathway （RCP） scenarios--RCP 2.6, RCP 4.5, RCP 6.0, and RCP 8.5） at a 1 km resolution within a globally consistent framework. The data are freely available for download, and will enable researchers to study the impacts of LULC change at the local scale.

关键词： LULC modeling Spatial downscaling RCP scenarios Urban expansion

SENSITIVITY OF MESOSCALE CONVECTIVE SYSTEMS AND ASSOCIATED HEAVY RAINFALL TO SOIL MOISTURE OVER SOUTH CHINA

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Journal of Tropical Meteorology 2017年第1期23卷 91-102页

作者：蒙伟光张艳霞李江南戴光丰李昊睿黄燕燕 Guangzhou Institute of Tropical and Marine Meteorology/guangdong Provincial key laboratory of Regional Numerical Weather Prediction CMA State key laboratory of Severe Weather Chinese Academy of Meteorological Sciences School of Environmental Science and Engineering Sun Yat-sen University

The impacts of soil moisture(SM) on heavy rainfall and the development of Mesoscale Convection Systems(MCSs) are investigated through 24-h numerical simulations of two heavy rainfall events that occurred respectively on28 March 2009(Case 1) and 6 May 2010(Case 2) over southern China. The numerical simulations were carried out with WRF and its coupled Noah LSM(Land Surface Model). First, comparative experiments were driven by two different SM data sources from NCEP-FNL and NASA-GLDAS. Secondary, with the run driven by NASA-GLDAS data as a control one, a series of sensitivity tests with different degree of(20%, 60%) increase or decrease in the initial SM were performed to examine the impact of SM on the simulations. Comparative experiment results show that the 24-h simulated cumulative rainfall distributions are not substantially affected by the application of the two different SM data,while the precipitation intensity is changed to some extent. Forecast skill scores show that simulation with NASA-GLDAS SM data can lead to some improvement, especially in the heavy rain(芏50 mm) forecast, where there is up to 5% increase in the TS score. Sensitivity test analysis found that a predominantly positive feedback of SM on precipitation existed in these two heavy rain events but not with completely the same features. Organization of the heavy rainfall-producing MCS seems to have an impact on the feedback process between SM and precipitation. For Case 1, the MCS was poorly organized and occurred locally in late afternoon, and the increase of SM only caused a slight enhancement of precipitation. Drier soil was found to result in an apparent decrease of rainfall intensity,indicating that precipitation is more sensitive to SM reduction. For Case 2, as the heavy rain was caused by a well-organized MCS with sustained precipitation, the rainfall is more sensitive to SM increase, which brings more rainfall. Additionally, distinctive feedback effects were identified from different stag

关键词： soil moisture Southern China heavy rainfall Mesoscale Convection System numerical simulation

Development of an integrated policy making tool for assessing air quality and human health benefits of air pollution control

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Frontiers of Environmental Science & Engineering 2015年第6期9卷 1056-1065页

作者： Xuezhen QIU Yun ZHU Carey JANG Che-Jen LIN Shuxiao WANG Joshua FU Junping XIE Jiandong WANG Dian DING Shicheng LONG guangdong Provincial key laboratory of Atmospheric Environment and Pollution Control College of Environment and Energy South China University of Technology Guangzhou Higher Education Mega Center Guangzhou 510006 China USEPA/Office of Air Quality Planning & Standards RTP NC 27711 USA Department of Civil Engineering Lamar University Beaumont TX 77710-0024 USA State key Joint laboratory of Environment simulation and Pollution Control School of Environment Tsinghua University Beijing 100084 China Department of Civil & Environmental Engineering University of Tennessee Knoxville TN 37996-2010 USA

Efficient air quality management is critical to protect public health from the adverse impacts of air pollution. To evaluate the effectiveness of air pollution control strategies, the US Environmental Protection Agency （US EPA） has developed the Software for Model Attainment Test-Community Edition （SMAT-CE） to assess the air quality attainment of emission reductions, and the Environmental Benefits Mapping and analysis Program- Community Edition （BenMAP-CE） to evaluate the health and economic benefits of air quality improvement respectively. Since scientific decision-making requires timely and coherent information, developing the linkage between SMAT-CE and BenMAP-CE into an integrated assessment platform is desirable. To address this need, a new module linking SMAT-CE to BenMAP-CE has been developed and tested. The new module streamlines the assessment of air quality and human health benefits for a proposed air pollution control strategy. It also implements an optimized data gridding algorithm which significantly enhances the computational efficiency without compro- mising accuracy. The performance of the integrated software package is demonstrated through a case study that evaluates the air quality and associated economic benefits of a national-level control strategy of PM2.5. The results of the case study show that the proposed emission reduction reduces the number of nonattainment sites from 379 to 25 based on the US National Ambient Air Quality Standards, leading to more than USS334billion ofeconomic benefits annually from improved public health. The integration of the science-based software tools in this study enhances the efficiency of developing effective and optimized emission control strategies for policy makers.

关键词： air quality assessment human health benefit,economic benefit air quality attainment assessment airpollution control strategy decision support system