【正文】 （ ） （ 5）紋波抑制比 Srip Srip 定義為輸入電壓交流紋波峰峰值與輸出電壓交流紋波峰峰值之比的分貝數(shù)。 （ ） 圖 324整流濾波電路與穩(wěn)壓電路 4 超聲檢測的軟件設(shè)計 因為系統(tǒng)要完成測量泄漏超聲的聲壓級、估算泄漏量以及完成顯示功能 ,所以 系統(tǒng)軟件部分主要是 由信號采集子程序、濾波子程序、 FFT 變換程序、泄漏估算子程序、 LCD 顯示子程序、鍵盤服務(wù)子程序 六大模塊組成，因為 C語言編寫的軟件易于實現(xiàn)模塊化，生成的機(jī)器代碼質(zhì)量高、可讀性強(qiáng)、移植好，所以本系統(tǒng)的軟件采用 C 語言編寫 。 本文所介紹的超聲波泄漏檢測系統(tǒng)具有精度高、體積小、便于攜帶和具有很好的人機(jī)交互界面等特點(diǎn)。 下面根據(jù) 圖 41 主程序流程圖 介紹軟件的具體設(shè)計 （ 1）首先將單片機(jī)系統(tǒng)、 LCD、 A/D 轉(zhuǎn)換、濾波器系數(shù)、 FFT 旋轉(zhuǎn)因子初始化； （ 2） 鍵盤掃描子程序 由于機(jī)械觸點(diǎn)的彈性作用，在鍵被按下或彈起時會出現(xiàn)電壓抖動，從最初按下到接觸穩(wěn)定要經(jīng)過數(shù)毫秒的彈跳時間，如 錯誤！未找到引用源。為保證鍵識別的準(zhǔn)確，必須進(jìn)行去抖動處理，去抖動有硬件和軟件兩種方法。 顯示子程序完成符號、數(shù)值的顯示輸出。 （ 4） FIR 濾波子程序 濾波算法的設(shè)計： 這里主要采用了算術(shù)平均值濾波法的方法， 一般在設(shè)計平均值濾波程序是，要考慮消除較為明顯的脈沖干擾，即將遠(yuǎn)離真實值的采樣值剔除，不參加平均值計算，從而使平均值更接近真實值。為使平均濾波方便， N2最好取， 16，這樣的除法實際上執(zhí)行右移指令即可完成。對于慢變參數(shù)，可一邊采樣，一邊處理，而不必在 RAM 中開辟數(shù)據(jù)暫存區(qū)。 圖 41 主程序流程圖 5 電路的調(diào)試過程 電路調(diào)試過程的步驟如下 （ 1）首先檢查穩(wěn)壓電源，其中正負(fù) 12 伏電壓供給功放電路，正負(fù) 5伏提供給單單片機(jī)系統(tǒng)初始化 LCD初始化 A/D轉(zhuǎn)換初始化 濾波器系數(shù)初始化 FFT旋轉(zhuǎn)因子初始化 開 始 鍵盤掃描子程序 A/D采樣子程序 FIR濾波子程序 FFT變換子程序 聲強(qiáng)計算及泄漏量估算子程序 顯示子程序 片機(jī)電路； （ 2）其次檢查各芯片管腳的電壓是否滿足工作電壓，包括單片機(jī)， NE555， NE5532芯片等； （ 3）接著在前兩步認(rèn)真完成的基礎(chǔ)上，進(jìn)入整體電路的調(diào)試，該電路包括兩路調(diào)試； （ 4）第一線路的測試：輸 入 5 毫伏，頻率為 40K 的正弦波，用示波器測量該信號的波形，信號通過超聲探頭到達(dá)前置放大電路，其中包含了兩級放大，第一級放大 100 倍，第二級放大 10 倍，它們是用電容耦合而成的。 （ 8） 第二線路的測試：由本振電路產(chǎn)生頻率為 37K 的多諧振蕩波； （ 9） 在端口 1輸入頻率為 3842K的正弦波并與 37K的多諧振蕩波進(jìn)行混頻，混頻后 進(jìn)入低通濾波器后，得到頻率 03K 的信號； （ 10） 最后信號進(jìn)入音頻功放電路，喇叭口處產(chǎn)生響聲，此完成整個調(diào)試過程。 通過概述使大家充分了解了該檢測系統(tǒng)的原理與功能。第一章介紹了氣體泄漏檢測方案的選擇和論證，從絕對壓力法、壓差法、超聲波檢測法相比較中，選出最佳方法；第二章介紹泄漏檢測 的設(shè)計原理，從對氣體泄漏產(chǎn)生一定頻率的聲波現(xiàn)象中發(fā)現(xiàn)了存在有超聲波，通過對超聲波的檢測來判斷泄漏的確切位置，并且從數(shù)學(xué)的角度分析了聲壓與泄漏量的關(guān)系；第三章詳細(xì)介紹超聲檢測電路設(shè)計原理與各單元電路的設(shè)計，從系統(tǒng)原理的角度得出系統(tǒng)分為模擬和數(shù)字兩部分；第四、五章介紹了軟件設(shè)計與電路調(diào)試過程。 本電路雖然已完成實際制作，并且符合要求，但也存在許多需要完善的地方，由于本人 水平有限，因此對其中的原理和實際操作方法有待深入的學(xué)習(xí)研究和提高。 謝 辭 本文是在導(dǎo)師晉良念老師悉心指導(dǎo)和鼓勵下完成的。晉良念老師淵博的知識，嚴(yán)謹(jǐn)?shù)闹螌W(xué)態(tài)度和一絲不茍的工作作風(fēng)給我留下了深深的印象，使我受益匪淺。在此向晉良念老師表示衷心的感謝和崇高的敬禮。衷心感謝在百忙中抽空參加論文評審的各位老師，感謝他們?yōu)楸疚母冻龅男燎趧趧印? 參考文獻(xiàn) [1] 王化祥，張淑英 .傳感器原理及應(yīng)用 [M].天津：天津大學(xué)出版社， . [2]于亞非 .用超聲波傳感器檢測氣體泄漏 [J].儀器與未來， 1992(8). [3]李光海，王勇等 .基于聲發(fā)射技術(shù)的管道泄漏檢測系統(tǒng) [J].自動化儀表， [4]李群芳 .單片微型計算機(jī)與接口技術(shù) [M].北京：電子工業(yè)出版社， 2021. [5]李進(jìn)，陳會倉等 .氣體泄漏超聲波檢測裝置 [J]. 工業(yè)儀表與自動化裝置， 1996， (5). [6]龔其春，葉騫 .新型氣體泄漏超聲檢測系統(tǒng)的研究與設(shè)計 [J].電子技術(shù)應(yīng)用， 2021， 3 [7] 袁易全 ,黃建人 . 高靈敏超聲檢漏儀的研究 [M].東南大學(xué)學(xué)報 ， 1989 [8] 李建藩 .氣壓傳動系統(tǒng)動力學(xué)廣州 [M].華南理工大學(xué)出版社 ， 1991 [9]ATMEL Microcontroller with 8K Bytes Flash AT89C52. [10]Donald Circuit Analysis and Design(Second edition). Published by the McGrawHill panies,2021. And what numberless and powerful causes tend to destroy these rare natures! What causes? In the first place there are their own virtues, their courage, temperance, and the rest of them, every one of which praise w orthy qualities (and this is a most singular circumstance) destroys and distracts from philosophy the soul which is the possessor of them. That is very singular, he replied. Then there are all the ordinary goods of life beauty, wealth, strength, rank, and great connections in the State you understand the sort of things these also have a corrupting and distracting effect. I understand。 you will then have no difficulty in apprehending the preceding remarks, and they will no longer appear strange to you. And how am I to do so? he asked. Why, I said, we know that all germs or seeds, whether vegetable or animal, when they fail to meet with proper nutriment or cl imate or soil, in proportion to their vigour, are all the more sensitive to the want of a suitable environment, for evil is a greater enemy to what is good than what is not. Very true. There is reason in supposing that the finest natures, when under alien conditions, receive more injury than the inferior, because the contrast is greater. Certainly. And may we not say, Adeimantus, that the most gifted minds, when they are illeducated, bee preeminently bad? Do not great crimes and the spirit of pure evil spring out of a fulness of nature ruined by education rather than from any inferiority, whereas weak natures are scarcely capable of any very great good or very great evil? There I think that you are right. And our philosopher follows the same analogy he is like a plant which, having proper nurture, must necessarily grow and mature into all virtue, but, if sown and planted in an alien soil, be es the most noxious of all weeds, unless he be preserved by some divine power. Do you really think, as people so often say, tha t our youth are corrupted by Sophists, or tha t private teachers of the art corrupt them in any degree worth speaking of ? Are not the public who say these things the greatest of all Sophists? And do they not educate to pe rfection young and old, men and women alike, and fashion them after their own hearts? When is this acplished? he said. When they meet together, and the world sits down at an assembly, or in a court of law, or a theatre, or a camp, or in any other popular resort, and there is a great uproar, and they praise some things which are being said or done, and blame other things, equally exaggerating both, shouting and clapping their hands, and the echo of the roc ks and the place in which they are assembled redoubles the sound of the praise or blame at such a time will not a young man39。 necessity will pel him. And yet, I said, there is a still greater necessity, which has not been mentioned. What is that? The gentle force of attainder or confiscation or death which, as you are aware, these new Sophists and educators who are the public, apply when their words are powerless. Indeed they do。 there neither is, nor has been, nor is ever likely to be, any different type of character which has had no other training in virtue but that which is supplied by public opinion I speak, my friend, of human virtue on