Although extensive analyses of road segments and intersections located in urban road networks have examined the role of many factors that contribute to the frequency and severity of crashes, the explicit relationship ...Although extensive analyses of road segments and intersections located in urban road networks have examined the role of many factors that contribute to the frequency and severity of crashes, the explicit relationship between street pattern characteristics and traffic safety remains underexplored. Based on a zone-based Hong Kong database, the Space Syntax was used to quantify the topological characteristics of street patterns and investigate the role of street patterns and zone-related factors in zone-based traffic safety analysis. A joint probability model was adopted to analyze crash frequency and severity in an integrated modeling framework and the maximum likelihood estimation method was used to estimate the parameters. In addition to the characteristics of street patterns, speed, road geometry, land-use patterns, and temporal factors were considered. The vehicle hours was also included as an exposure proxy in the model to make crash frequency predictions. The results indicate that the joint probability model can reveal the relationship between zone-based traffic safety and various other factors, and that street pattern characteristics play an important role in crash frequency prediction.展开更多
Complex conditional statement is one of the bad code smells,which affects the quality of the code and design of software.In the proposed approach,two commonly-used design patterns for handling complex conditional stat...Complex conditional statement is one of the bad code smells,which affects the quality of the code and design of software.In the proposed approach,two commonly-used design patterns for handling complex conditional statements are selected,and they are the factory method pattern and the strategy pattern.Two pattern-directed refactoring approaches based on the two design patterns are proposed.Each approach contains a refactoring opportunities identification algorithm and an automated refactoring algorithm.After parsing the abstract syntax tree generated from source code,the refactoring opportunities are identified effectively and automatically.Then,for candidate code,refactoring algorithms are executed automatically,which are used to simplify or remove complex conditional statements.By empirical analysis and quality assessment,the code after refactoring has better maintainability and extensibility,and the proposed approach for automated pattern-directed refactoring succeeds to reduce code size and complexity of classes.展开更多
基金Project(71301083)supported by the National Natural Science Foundation of ChinaProject(2012AA112305)supported by the National High-Tech Research and Development Program of China+1 种基金Project(2012CB725405)supported by the National Basic Research Program of ChinaProject(17208614)supported by the Research Grants Council of the Hong Kong Special Administrative Region,China
文摘Although extensive analyses of road segments and intersections located in urban road networks have examined the role of many factors that contribute to the frequency and severity of crashes, the explicit relationship between street pattern characteristics and traffic safety remains underexplored. Based on a zone-based Hong Kong database, the Space Syntax was used to quantify the topological characteristics of street patterns and investigate the role of street patterns and zone-related factors in zone-based traffic safety analysis. A joint probability model was adopted to analyze crash frequency and severity in an integrated modeling framework and the maximum likelihood estimation method was used to estimate the parameters. In addition to the characteristics of street patterns, speed, road geometry, land-use patterns, and temporal factors were considered. The vehicle hours was also included as an exposure proxy in the model to make crash frequency predictions. The results indicate that the joint probability model can reveal the relationship between zone-based traffic safety and various other factors, and that street pattern characteristics play an important role in crash frequency prediction.
文摘Complex conditional statement is one of the bad code smells,which affects the quality of the code and design of software.In the proposed approach,two commonly-used design patterns for handling complex conditional statements are selected,and they are the factory method pattern and the strategy pattern.Two pattern-directed refactoring approaches based on the two design patterns are proposed.Each approach contains a refactoring opportunities identification algorithm and an automated refactoring algorithm.After parsing the abstract syntax tree generated from source code,the refactoring opportunities are identified effectively and automatically.Then,for candidate code,refactoring algorithms are executed automatically,which are used to simplify or remove complex conditional statements.By empirical analysis and quality assessment,the code after refactoring has better maintainability and extensibility,and the proposed approach for automated pattern-directed refactoring succeeds to reduce code size and complexity of classes.
