1、1. A channel has a bit rate of 4 kbps and a propagation delay of 20 msec. For what range of frame sizes does stop-and-wait give an efficiency of at least 50%?answer: 發(fā)送一幀的時(shí)間等于信道的傳播延遲的 2 倍，信道的利用率為 50%，所以，在幀長(zhǎng)滿足發(fā)送時(shí)間大于延遲時(shí)間的 2 倍是，效率將會(huì)高于 50%。由于4kbps=4000bps 故4000*20*0.001*2=160bit只有在幀長(zhǎng)不小于 160bit 時(shí)，停止等待協(xié)議的效率才會(huì)至少是 50%。解此題可供參考的公式有兩個(gè)，下面這兩種情況下都可以得到答案：一個(gè)是效率= 其中 P 是傳輸一幀所需要的時(shí)間，t。

2、i | j) be the loss incurred for taking action i when the state of nature is j.action i assign the sample into any class-Conditional risk for i = 1,a cjjii xPxR1 )|()|(Select the action i for which R(i | x) is minimumR is minimum and R in this case is called the Bayes risk = best reasonable result that can be achieved!ij :loss incurred for deciding i when the true state of nature is jgi(x) = - R(i | x)max. discriminant corresponds to min. riskgi(x) = P(i | x)max. discr。

3、名詞解釋人化自然: 人化自然是相對(duì)于天然自然，人工自然而定義的。人化自然指人類觀測(cè)所及從而能夠感知其信息的那部分自然界，包括從總星系到基本粒子范圍內(nèi)。所有人類已經(jīng)認(rèn)識(shí)或已開始認(rèn)識(shí)到的自然物、自然現(xiàn)象和過(guò)程。開放系統(tǒng): 開放系統(tǒng)是相對(duì)于孤立系統(tǒng)和封閉系統(tǒng)而言的。系統(tǒng)與環(huán)境交換物質(zhì)、能量、信息。生態(tài)自然觀（自然觀是重點(diǎn)）: 生態(tài)系統(tǒng)是個(gè)整體，是自組織的開放系統(tǒng)；生態(tài)平衡是穩(wěn)定性與變化性相統(tǒng)一的平衡人只是生態(tài)系統(tǒng)中的普通成員，生態(tài)系統(tǒng)的利益包含并高于人類的利益，維持生態(tài)系統(tǒng)的繁榮穩(wěn)定是人與自然關(guān)系的最高倫理。

4、11. A channel has a bit rate of 4 kbps and a propagation delay of 20 msec. For what range of frame sizes does stop-and-wait give an efficiency of at least 50%?answer: 發(fā)送一幀的時(shí)間等于信道的傳播延遲的 2 倍，信道的利用率為 50%，所以，在幀長(zhǎng)滿足發(fā)送時(shí)間大于延遲時(shí)間的 2 倍是，效率將會(huì)高于 50%。由于4kbps=4000bps 故4000*20*0.001*2=160bit只有在幀長(zhǎng)不小于 160bit 時(shí)，停止等待協(xié)議的效率才會(huì)至少是 50%。解此題可供參考的公式有兩個(gè)，下面這兩種情況下都可以得到答案：一個(gè)是效率= 其中 P 是傳輸一幀所需要的時(shí)間，。

5、1(i | j) be the loss incurred for taking action i when the state of nature is j.action i assign the sample into any class-Conditional risk for i = 1,a cjjii xPxR1 )|()|(Select the action i for which R(i | x) is minimumR is minimum and R in this case is called the Bayes risk = best reasonable result that can be achieved!ij :loss incurred for deciding i when the true state of nature is jgi(x) = - R(i | x)max. discriminant corresponds to min. riskgi(x) = P(i | x)max. disc。