文字未出現前 的英文怎麼說

中文拼音 [wénzìwèichūxiànqián]
文字未出現前 英文
preliterate
  • 文 : Ⅰ名詞1 （字） character; script; writing 2 （文字） language 3 （文章） literary composition; wri...
  • 字 : Ⅰ名詞1 （文字） character; word 2 （字音） pronunciation 3 （字體） form of a written or printed ...
  • 未 : Ⅰ副詞1 （沒） did not; have not 2 （不） not Ⅱ名詞1 （地支的第八位） the eighth of the twelve ear...
  • 現 : Ⅰ名詞1 （現在; 此刻） present; now; current; existing 2 （現款） cash; ready money Ⅱ副詞（臨時; ...
  • 前 : Ⅰ名詞1 （在正面的） front 2 （次序在先的） first; top 3 （過去的; 較早的） ago; before; preceding...
  • 文字 : 1 （書寫符號） characters; script; writing 2 （語言的書面形式） written language 3 （文章形式） w...
  1. Aim at the dtc ' s blemish mentioned above and the direction of dtc technique development, the dissertation put great emphasis on the work as follows, with an eye to exalt dtc system function : ( 1 ) a new speed - flux observer of an induction motor is proposed to enhance the accuracy of flux observing, which is an adaptive closed - loop flux observer and different from the traditions. a new adaptive speed - observation - way is deduced out according to the popov ' s stability theories ; ( 2 ) to improve the performance of dtc at low speed operation, we have to exalt the accuracy of the stator flux estimation and a new way of bp neural network based on extended pidbp algorithm is given to estimate and tune the stator resistance of an induction motor to increase the accuracy of the stator flux estimation ; ( 3 ) digital signal processor is adopted to realize digital control. an device of direct torque control system is designed for experiment using tms320lf2407 chip produced by ti company ; ( 4 ) bring up a distributed direct torque control system based on sercos bus, sercos stand for serial real time communication system agreement which is most in keeping with synchronous with moderate motor control ; ( 5 ) the basic design frame of the hardware and software of the whole control system is given here and some concrete problem in the experiments is described here in detail

    針對上面提到的直接轉矩控制的缺陷和未來直接轉矩控制技術發展方向，本論文重點做了以下幾個方面的工作，目的在於提高dtc系統的綜合性能： （ 1 ）提出一種新型的速度磁鏈觀測器，新型的速度磁鏈觀測器採用自適應閉環磁鏈觀測器代替傳統的積分器從而提高磁鏈觀測的精度，並且根據popov超穩定性理論推導出轉速的新型自適應收斂律； （ 2 ）改善系統的低速運行性能，主要從提高低速時對定子磁鏈的估計精度入手，提出了一種提高定子磁鏈觀測精度的新思路? ?利用基於bp網路增廣pidbp學習演算法來實時在線地修正定子電阻參數； （ 3 ）採用數字信號處理器dsp實現系統全數字化硬體控制，結合ti公司生產的tms320lf2407晶元，設計了直接轉矩控制系統的實驗裝置； （ 4 ）提出了基於sercos總線網路化分散式的直接轉矩控制系統， sercos （ serialrealtimecommunicationsystem ）是目前最適合同步和協調控制的串列實時通信協議； （ 5 ）基本勾勒出整個控制系統的硬體和軟體設計基本框架，詳細描述一些實驗中的具體的細節問題。
  2. The embedded bw also successfully survives cropping, filtering, noise and multi - watermarking etc. the new ideas the thesis proposed are : first, frequency - based watermarking idea using toral automorphisms is really a novel one, although, in the literature, there are some waterniarking schemes using toral autpmorphisms, all of which are based on space ; second, some improvements of the quantization function contribute to the algorithm ' s performances to some degree

    另外該演算法對圖象裁剪、濾波、噪聲和多重水印處理等都具有較強的魯棒性。本文提出了兩個新思想：第一，雖然現有文獻已經提出了利用環形自同構映射的數字水印處理演算法，但這種演算法是基於空域的，而利用環形自同構映射基於頻域的水印處理演算法，目前文獻上未見報道。
  3. In the third chapter, through doing some research on present situation of zigong city ’ s tourism development, author gives some problems encountered by zigong city ’ s tourism industry. in the forth chapter, the history of zigong city ’ s salt industry is divided into six periods. employing the theories mentioned in the chapter two and comparing the map of qing dynasty with the present one, the author finds the salt industry had significant impact on city ’ s structure

    第三章通過實地考察、資料搜集，採用圖表結合文字的方式直觀的提出了自貢市的旅遊開發現狀及目前所存在的問題:城市旅遊未將自貢最具特色性、唯一性的井鹽文化作為城市主體特色來挖掘並展示;旅遊資源整合度嚴重不足。
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