行程问题是初中应用题中的一大难点,又是历届中考考查的主要内容之一。因此必须深刻理解、熟练掌握好这类问题的各种类型及其解法。一、画出示意图或列表分析行程问题揭示问题的实质在解行程问题时,要紧紧抓住速度、时间及路程间的数量...行程问题是初中应用题中的一大难点,又是历届中考考查的主要内容之一。因此必须深刻理解、熟练掌握好这类问题的各种类型及其解法。一、画出示意图或列表分析行程问题揭示问题的实质在解行程问题时,要紧紧抓住速度、时间及路程间的数量关系,并善于画出示意图或列表分析题意,这将有助于我们弄清题意,揭示问题的实质,找出等量关系,因此要学会画图和列表分析行程问题。例1:甲乙两车装运粮食从产地开往仓库,甲的速度是50公里/小时,开出半小时后,乙也从产地开出,它的速度是40公里/小时,结果乙比甲晚到1小时,求产地和仓库间的距离。分析:采用直接设元,设产地和仓库间为 x 公里,用列表法分析。(解答略)展开更多
In order to improve the data transmission reliability of mobile ad hoc network, a routing scheme called integrated forward error correction multipath routing protocol was proposed, which integrates the techniques of p...In order to improve the data transmission reliability of mobile ad hoc network, a routing scheme called integrated forward error correction multipath routing protocol was proposed, which integrates the techniques of packet fragmenting and forward error correction encoding into multipath routing. The scheme works as follows: adding a certain redundancy into the original packets; fragmenting the resulting packets into exclusive blocks of the same size; encoding with the forward error correction technique, and then sending them to the destination node. When the receiving end receives a certain amount of information blocks, the original information will be recovered even with partial loss. The performance of the scheme was evaluated using OPNET modeler. The experimental results show that with the method the average transmission delay is decreased by 20% and the transmission reliability is increased by 30%.展开更多
文摘行程问题是初中应用题中的一大难点,又是历届中考考查的主要内容之一。因此必须深刻理解、熟练掌握好这类问题的各种类型及其解法。一、画出示意图或列表分析行程问题揭示问题的实质在解行程问题时,要紧紧抓住速度、时间及路程间的数量关系,并善于画出示意图或列表分析题意,这将有助于我们弄清题意,揭示问题的实质,找出等量关系,因此要学会画图和列表分析行程问题。例1:甲乙两车装运粮食从产地开往仓库,甲的速度是50公里/小时,开出半小时后,乙也从产地开出,它的速度是40公里/小时,结果乙比甲晚到1小时,求产地和仓库间的距离。分析:采用直接设元,设产地和仓库间为 x 公里,用列表法分析。(解答略)
基金Projects(2003CB314802) supported by the State Key Fundamental Research and Development Programof China project(90104001) supported by the National Natural Science Foundation of China
文摘In order to improve the data transmission reliability of mobile ad hoc network, a routing scheme called integrated forward error correction multipath routing protocol was proposed, which integrates the techniques of packet fragmenting and forward error correction encoding into multipath routing. The scheme works as follows: adding a certain redundancy into the original packets; fragmenting the resulting packets into exclusive blocks of the same size; encoding with the forward error correction technique, and then sending them to the destination node. When the receiving end receives a certain amount of information blocks, the original information will be recovered even with partial loss. The performance of the scheme was evaluated using OPNET modeler. The experimental results show that with the method the average transmission delay is decreased by 20% and the transmission reliability is increased by 30%.
