REAL-TIME NETWORK DECOMPOSITION AND SUBNETWORK INTERFACING
REAL-TIME NETWORK DECOMPOSITION AND SUBNETWORK INTERFACING
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发表时间：
1971
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通讯作者：
R. Walinchus
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作者：
R. Walinchus
分解网络和连接由此产生的子网的新方法正在开发中，作为持续研究和开发工作的一部分，以改善实时城市交通控制。本文介绍了基本概念和备选方案。当网络几何形状不均匀和/或区域内的流量特性不均匀时，可能需要进行网络分解。除非完成两项任务，否则分解不会成功：(a)根据某些标准确定子网，(b)将各个子网连接起来。定义子网的两种常用方法是固定子网定义和实时子网定义。固定子网是根据几何和其他考虑来定义的。实时子网定义是基于流量动态的。要成功地实时定义子网，必须具备两个要素：(a)确定一个交集是作为单独子网的一部分考虑的“候选”的标准；(b)将这些候选交集分组到一个可行的子网中的程序。候选标准是偏移误差——可实现偏移量和理想偏移量之间的差异。在分组过程中有两种真正实时的方法（矩形子集和连通集）和一种伪实时的方法。连接子网可能是一项艰巨的任务。在两个区域具有相同信号周期的特殊情况下，通过“增量偏移”实现接口。这个增量偏移量是跨接口所需偏移量变化的体积加权平均值。对于不相等的周期，可以采用匹配和重新同步技术，或者可以通过一个过渡区来完成接口，其中信号是交通驱动的，而不是在任何特定的周期上操作。/作者/
NEW METHODS OF DECOMPOSING NETWORKS AND INTERFACING THE RESULTING SUBNETWORKS ARE BEING DEVELOPED AS PART OF THE CONTINUING RESEARCH AND DEVELOPMENT EFFORT TO IMPROVE REAL- TIME URBAN TRAFFIC CONTROL. THE BASIC CONCEPTS AND ALTERNATIVES ARE INTRODUCED IN THIS PAPER. NETWORK DECOMPOSITION MAY BE REQUIRED WHEN THE NETWORK GEOMETRY IS NOT UNIFORM AND/OR WHEN THE TRAFFIC CHARACTERISTICS WITHIN AN AREA ARE NOT UNIFORM. DECOMPOSITION IS NOT SUCCESSFUL UNLESS TWO TASKS ARE ACCOMPLISHED: (A) SUBNETWORK DETERMINATION ACCORDING TO CERTAIN CRITERIA AND (B) INTERFACING THE VARIOUS SUBNETWORKS. THE TWO GENERAL WAYS IN WHICH SUBNETWORKS MAY BE DEFINED ARE FIXED DEFINITION AND REAL-TIME SUBNETWORK DEFINITION. FIXED SUBNETWORKS ARE DEFINED FROM GEOMETRICAL AND OTHER CONSIDERATIONS. REAL-TIME SUBNETWORK DEFINITION IS BASED ON TRAFFIC DYNAMICS. TO DEFINE SUCCESSFULLY SUBNETWORKS IN REAL TIME, TWO ELEMENTS MUST BE PRESENT: (A) A CRITERION BY WHICH IT CAN BE DETERMINED THAT AN INTERSECTION IS A "CANDIDATE" FOR CONSIDERATION AS PART OF A SEPARATE SUBNETWORK AND (B) A PROCEDURE BY WHICH THESE CANDIDATE INTERSECTIONS CAN BE GROUPED INTO A WORKABLE SUBNETWORK. THE PROPOSED CRITERION FOR CANDIDACY IS OFFSET ERROR -THE DIFFERENCE BETWEEN A REALIZABLE AND AN IDEALIZED OFFSET. AMONG THE GROUPING PROCEDURES ARE TWO GENUINELY REAL-TIME METHODS (RECTANGULAR SUBSET AND CONNECTIBLE SET) AND ONE PSEUDO REAL-TIME METHOD. INTERFACING SUBNETWORKS CAN BE A DIFFICULT TASK. IN THE SPECIAL CASE WHERE THE TWO AREAS HAVE THE SAME SIGNAL CYCLE, INTERFACING IS ACCOMPLISHED VIA A "DELTA OFFSET." THIS DELTA OFFSET IS A VOLUME-WEIGHTED AVERAGE OF THE OFFSET CHANGES DESIRED ACROSS THE INTERFACE. WITH UNEQUAL CYCCLES, A MATCHING AND RESYNCHRONIZATION TECHNIQUE MIGHT BE EMPLOYED, OR INTERFACING CAN BE ACCOMPLISHED THROUGH A TRANSITION ZONE WHERE THE SIGNALS ARE TRAFFIC-ACTUATED RATHER THAN OPERATED ON ANY SPECIFIC CYCLE. /AUTHOR/