電大機(jī)電控制工程基礎(chǔ)期末復(fù)習(xí)考試題庫參考資料小抄(存儲版)
【正文】 。 錯誤 7．下圖中網(wǎng)絡(luò)是一個無源滯后校正網(wǎng)絡(luò)。s public security bureau shows some 100 foreign visitors enjoyed the 72hour policy by the end of March, most of them from the United States, the United Kingdom and Germany. Chengdu also reported robust growth in its overall tourist industry last year. Official statistics show that it received some 150 million tourists last year, an increase of 28 percent from 2021. Around million came from abroad, an increase of 12 percent. Total revenue from tourism surpassed 133 billion yuan ($). During his visit to Kazakhstan in September, Chinese President Xi Jinping proposed that China and Central Asia join hands to build a Silk Road economic belt to boost cooperation. The idea has been widely echoed in Central Asian countries, being an encouraging blueprint for Chinese areas along the Silk Road that has linked Asia and Europe for more than 2,000 years. In the next three weeks, China Daily reporters will travel through the belt in China and in Kazakhstan, Uzbekistan and Turkey. They will show the progress and expectations of the countries, businesses and peoples on the route. Shaanxi the start of the ancient Silk Road has positioned itself as the new starting point for the development of the Silk Road Economic Belt, which will strengthen China39。s ancient indigenous religion, while Du jiang yan is considered to be the oldest functioning watercontrol project in the world. Chengdu ranked third in tourist facilities, management and services among 60 Chinese cities in a custo mer satisfaction survey released last year. But, Li added that efforts are still needed to develop more tourism products, improve English services and provide accurate translation of traffic signs and scenic billboards. Zhao Yun, chairwoman of British Chamber of Commerce Southwest China, told China Daily that his colleagues found the policy very convenient. A British client once flew here and stayed for just one day to check her ordered goods, she said. Zhao was born in Shanxi province, but she has lived in Chengdu for more than 10 years. My life was like a running race moving from place to place. I also lived in Beijing and Shanghai before, she said. But Chengdu is a place that you never want to leave once settling down. It is now my second hometown, she said. If the environment is further improved, the city will attract more people to visit and live, with the 72hour visafree policy and pelling conditions in transportation, culture, climate and cuisine, he said. Foreigners also gave positive feedback on the policy. A spokesman from Dell Inc said the pany has a global hub of operation in Chengdu, so the threeday visa has an immediate and positive influence on the pany39。 正確 5．相位超前校正裝置的傳遞函數(shù)為 TsaTssGc ??? 11)(，系數(shù) a大于 1。 正確 14．凡是在 s 左半平面上沒有極、零點(diǎn)的系統(tǒng)，稱為最小相位系統(tǒng)， 錯誤 15．若系統(tǒng)的開環(huán)穩(wěn)定，且在 L(?)＞ 0 的所有頻率范圍內(nèi)，相頻 ?(?)＞ 1800，則其閉環(huán)狀態(tài)是穩(wěn)定的。 正確 第五章習(xí)題答案 一、 判斷 2. 系統(tǒng)的頻率特性是由 )(?jG 描述的， )( ?jG 稱為系統(tǒng)的幅頻特性； )(?jG? 稱為系統(tǒng)的相頻特性。起點(diǎn)數(shù) n就是根軌跡曲線的條數(shù)。 ξ＝ ω n＝ 10 σ％＝ ％ ts（ 5％）＝ （ s） 七、 系統(tǒng)的特征方程為 05432 2345 ?????? sssss 試用勞斯判據(jù)判斷系統(tǒng)的穩(wěn)定性。 正確 19．對穩(wěn)定的系統(tǒng)研究穩(wěn)態(tài)誤差才有意義，所以計算穩(wěn)態(tài)誤差應(yīng) 19。正確 12. te?2 的拉氏變換為 12?s 。 正確 6. 某二階系統(tǒng)的特征根為兩個具有負(fù)實部的共軛復(fù)根，則該系統(tǒng)
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