怎么还不出
我一个一个回复，为等下做准备，呵呵
有下来的没有？？
有下来的没有？？
顶~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
还没出？怎么回事呀
占一个位置~~~~~~~
占一个位置~~~~~~~
问题答：设计一个环岛
许多城市和社区的交通圈，从大企业与许多车道的圆圈内（如在凯旋门和巴黎在曼谷胜利纪念碑） ，以小的一个或两个车道的圆圈。其中有些交通界的立场或停止的迹象，收益率上签署每个传入道路交通优先考虑已在循环;一些立场的迹象，收益率的圆圈在每个传入道路优先考虑传入流量;和一些定位红绿灯对每个传入道（无右转上允许红灯） 。其他设计也可能是可能的。
的目标，这个问题是使用一种模式，以确定如何最好地控制交通流量，周围，出于一个圆圈。国家明确的目标（县）您使用的模式，使您的最佳选择，以及各种因素影响这种选择。包括技术综述不超过两双倍行距网页，说明交通工程师如何使用您的模型，以帮助选择适当的流量控制方法的任何具体的交通循环。也就是说，总结了在何种条件下每种类型的交通管制方法应使用。当交通灯的建议，解释的一种方法，以确定有多少秒每个轻应保持绿色（可根据不同的时间和其他因素） 。说明你的模型与具体的例子。
PROBLEM A: Designing a Traffic Circle
Many cities and communities have traffic circles—from large ones with many lanes in the circle (such as at the Arc de Triomphe in Paris and the Victory Monument in Bangkok) to small ones with one or two lanes in the circle. Some of these traffic circles position a stop sign or a yield sign on every incoming road that gives priority to traffic already in the circle; some position a yield sign in the circle at each incoming road to give priority to incoming traffic; and some position a traffic light on each incoming road (with no right turn allowed on a red light). Other designs may also be possible.
The goal of this problem is to use a model to determine how best to control traffic flow in, around, and out of a circle. State clearly the objective(s) you use in your model for making the optimal choice as well as the factors that affect this choice. Include a Technical Summary of not more than two double-spaced pages that explains to a Traffic Engineer how to use your model to help choose the appropriate flow-control method for any specific traffic circle. That is, summarize the conditions under which each type of traffic-control method should be used. When traffic lights are recommended, explain a method for determining how many seconds each light should remain green (which may vary according to the time of day and other factors). Illustrate how your model works with specific examples.