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簡(jiǎn)介:中文中文13500字出處出處CHUIH,RANGARAJANAANEWPOINTMATCHINGALGORITHMFORNONRIGIDREGISTRATIONJCOMPUTERVISIONIMAGEUNDERSTANDING,2003,892–3114141一種用于非剛性點(diǎn)定位的新匹配算法一種用于非剛性點(diǎn)定位的新匹配算法CHUIH,RANGARAJANA美國(guó)加利福尼亞州森尼維爾市R2科技區(qū),郵編94087美國(guó)佛羅里達(dá)大學(xué)計(jì)算機(jī)與信息科學(xué)與工程系蓋恩斯維爾實(shí)驗(yàn)室,電話326116122002年3月5日收到;2002年10月15日收錄摘要摘要基于特征的非剛性定位方法經(jīng)常遇到匹配問(wèn)題。無(wú)論使用的是點(diǎn),線,曲線還是表面參數(shù)化,基于特征的非剛性匹配都需要我們自動(dòng)求解兩組特征之間的匹配關(guān)系。此外,可能有許多特征只存在于一組內(nèi),而另一組沒(méi)有對(duì)應(yīng)的特征。這個(gè)暴露出的問(wèn)題使這個(gè)已經(jīng)很困難的匹配問(wèn)題更加復(fù)雜化。我們考慮把這種基于特征的非剛性定位看作一個(gè)非剛性點(diǎn)匹配問(wèn)題。仔細(xì)審查了這個(gè)問(wèn)題,并深入了解了以前為剛性點(diǎn)匹配(RPM)設(shè)計(jì)的兩種方法,我們?yōu)榉莿傂渣c(diǎn)匹配提出了一種新的框架。我們認(rèn)為它是一種普遍適用的框架,因?yàn)樗灰蕾囉谌魏翁囟ㄐ问降目臻g分布。我們還開發(fā)了一種算法TPSRPM算法。TPSRPM算法使用薄板樣條(TPS)進(jìn)行非剛性空間分布的參數(shù)化和對(duì)準(zhǔn)的軟分配。在一系列精心設(shè)計(jì)的合成實(shí)驗(yàn)中,TPSRPM算法的性能得到充分證明和驗(yàn)證。在每個(gè)實(shí)驗(yàn)中,還提供了與流行的迭代最近點(diǎn)(ICP)算法的比較。最后,將算法應(yīng)用于大腦映射中所需的皮質(zhì)解剖結(jié)構(gòu)的非剛性匹配問(wèn)題。在有了一些初步成果的同時(shí),它們清楚地表明了我們提供的方法在現(xiàn)實(shí)生活里涉及基于特征的非剛性定位的適用性。11介紹介紹在計(jì)算機(jī)視覺(jué)和醫(yī)學(xué)影像領(lǐng)域經(jīng)常出現(xiàn)基于特征的定位問(wèn)題。由于兩個(gè)圖像中的顯著結(jié)構(gòu)表現(xiàn)為緊湊的幾何實(shí)體(例如,點(diǎn),曲線和曲面),所以定位問(wèn)題是在兩組特征之間找出最佳的或次優(yōu)空間變換/映射。位置特征是點(diǎn)特征中最簡(jiǎn)單的形式。它通常作為其他更復(fù)雜圖形(如曲線,曲面)的基礎(chǔ)。在這個(gè)角度上,它也被認(rèn)為是所有特征中最基本的形式。然而,單獨(dú)使用基于點(diǎn)特征的定位可能是相當(dāng)不利的。一個(gè)常見(jiàn)的因素是來(lái)自圖像采集和特征提取過(guò)程中產(chǎn)生的噪聲。噪聲的存在意味著所得到的特征點(diǎn)不能精確匹配。另一個(gè)因素是異常值的存在-許多點(diǎn)特征可能只存在于一個(gè)點(diǎn)集合中,而不存在于另一個(gè)點(diǎn)集合中(同源性),因此需要在匹配過(guò)程中被濾除。最后,地理變換可能需要引入高維非剛性映射,以便考慮點(diǎn)集的變化。因此,一種綜合點(diǎn)特征定位算法需要解決所有這些問(wèn)題。它需要能夠解決兩個(gè)點(diǎn)集之間的匹配關(guān)系,濾除異常值,并確定一種比較好的非剛性變換,使得一個(gè)點(diǎn)集能夠映射到另一個(gè)點(diǎn)集上。在現(xiàn)實(shí)世界中,許多場(chǎng)合都會(huì)應(yīng)用到非剛性點(diǎn)定位。例如OCR中的手寫字符的模板匹配,卡通動(dòng)畫中的關(guān)鍵幀之間整體平滑中間插值框架,跟蹤運(yùn)動(dòng)中的人體運(yùn)動(dòng),恢復(fù)動(dòng)態(tài)心臟的圖像分析并定位人腦MRI腦圖中的圖像,所有這些涉及緊密相關(guān)但不同物體或形狀之間的最佳變換。這是一個(gè)普遍存在的問(wèn)溢出。必須采取一些措施來(lái)修改空間匹配關(guān)系的搜索?,F(xiàn)有三種主要的方法來(lái)實(shí)現(xiàn)這個(gè)目標(biāo)。第一種是基于密集特征的方法,嘗試將特征點(diǎn)分組到更高級(jí)別的結(jié)構(gòu)中,例如線,曲線或曲面,使得對(duì)象參數(shù)化。然后,對(duì)象可以變形到指定的形式28,33。換句話說(shuō),曲線或曲面是最先從圖像中提取的特征14,28,40,41。在配置步驟中經(jīng)常使用參數(shù)化坐標(biāo)幀,從而降低匹配問(wèn)題的難度。在曲線匹配案例中可以清楚地看到該方法的優(yōu)點(diǎn)和缺點(diǎn)。利用現(xiàn)有的額外的曲線排序信息,可以大幅減少匹配空間,使得匹配問(wèn)題變得更加容易。另一方面來(lái)說(shuō),對(duì)這些額外信息的要求限制了這些方法的使用。這些方法只有在要匹配的曲線相當(dāng)平滑的情況下才能有效。此外,在匹配之前的曲線擬合步驟預(yù)先優(yōu)化了特征提取。當(dāng)數(shù)據(jù)有噪聲或者解決復(fù)雜圖形時(shí),曲線擬合和特征提取都會(huì)變得相當(dāng)困難。這些方法大多數(shù)都不能處理復(fù)雜曲線或局部閉塞的曲線。第二種類型的方法適用于更加稀疏分布的點(diǎn)集?;舅枷胧?,當(dāng)特定形狀的點(diǎn)集是非剛性形變時(shí),在不同位置的不同點(diǎn)可以根據(jù)其運(yùn)動(dòng)方式被賦予不同的屬性。這些運(yùn)動(dòng)屬性用于區(qū)分這些點(diǎn)并確定它們的匹配關(guān)系。在12,34,35之后,33中的模態(tài)匹配方法使用從高斯集合中的其他點(diǎn)集中的點(diǎn)特征之間的距離構(gòu)建的質(zhì)量和剛度矩陣。獲得的模態(tài)形狀向量作為用上述矩陣定義的解耦動(dòng)態(tài)平衡方程的特征向量。通過(guò)比較每個(gè)點(diǎn)在本征模式中的相對(duì)參與來(lái)計(jì)算匹配程度。這些算法的一個(gè)主要限制是它們不能容忍異常值。異常值可能會(huì)嚴(yán)重影響變形模式,從而使計(jì)算出的匹配關(guān)系無(wú)效。只通過(guò)比較本征模式可獲得的匹配關(guān)系的準(zhǔn)確性也可能受到限制。第三種方法將點(diǎn)匹配重鑄為不精確的加權(quán)匹配36。其中每組中的點(diǎn)之間的空間關(guān)系用于限制對(duì)匹配關(guān)系的查詢。在13中,通過(guò)DELAUNAY三角測(cè)量建立圖表,考慮了這些點(diǎn)之間的相互關(guān)系。使用期望最大化(EM)算法來(lái)解決圖像匹配優(yōu)化問(wèn)題。然而,空間映射僅限用于仿射或投影。正如我們將看到的,我們?cè)谶@項(xiàng)工作中的做法與13有很多相似之處。在1中,可分解圖都是為可變形模板匹配,手工設(shè)計(jì)的,并通過(guò)動(dòng)態(tài)編程最簡(jiǎn)化。在27中,使用最大集團(tuán)方法來(lái)匹配相對(duì)的SULCAL圖。在其他情況下,可變形模型和圖形之間沒(méi)有直接的關(guān)系。圖形定義同樣是一個(gè)常見(jiàn)的問(wèn)題,因?yàn)橄嗷リP(guān)系,屬性和鏈接類型信息可能是非常脆弱并緊密相關(guān)的。事實(shí)上,1,27中的圖形是手工設(shè)計(jì)的。2323同時(shí)解決通信和轉(zhuǎn)換問(wèn)題的方法同時(shí)解決通信和轉(zhuǎn)換問(wèn)題的方法如果可以的情況下,單獨(dú)解決匹配關(guān)系或形變似乎就已經(jīng)相當(dāng)困難了。注意到,在給出匹配關(guān)系的情況下估計(jì)非剛性變換要容易得多。另一方面,合理的空間變革的相關(guān)知識(shí)在尋找匹配關(guān)系方面也有相當(dāng)大的幫助。這個(gè)發(fā)現(xiàn)指出了解決點(diǎn)匹配問(wèn)題的另一種方式匹配和轉(zhuǎn)換的交替估計(jì)。迭代最近點(diǎn)(ICP)算法5是這些方法中最簡(jiǎn)單的。利用最鄰近關(guān)系置換為在每一步分配一個(gè)二進(jìn)制匹配關(guān)系。然后將這種匹配關(guān)系的估計(jì)用于細(xì)化變換,反之亦然。這是一個(gè)非常簡(jiǎn)單和快速的算法,保證收斂到局部最小值。假設(shè)有足夠的初始數(shù)據(jù),它可以用作剛性轉(zhuǎn)換的全局匹配工具。不幸的是,這種假設(shè)在非剛性變換的情況下不再有效,特別是當(dāng)變形較大時(shí)。ICP粗略的分配函數(shù)會(huì)產(chǎn)生大量的本地最小值,通常不保證匹配關(guān)系是一對(duì)一的。它的運(yùn)行會(huì)快速生成一些異常值,甚至?xí)砑右恍敯艨刂?,31。認(rèn)識(shí)到將匹配關(guān)系視為嚴(yán)格二進(jìn)制變量會(huì)產(chǎn)生這些缺點(diǎn),其他方法放寬了這一限制,并引入了“模糊”匹配關(guān)系的概念。主要有兩種方法。在
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簡(jiǎn)介:中文中文5395字出處出處INTERNATIONALJOURNALOFSCIENTIFICENGINEERINGRESEARCH,2012,3516本科生畢業(yè)設(shè)計(jì)(論文)外文翻譯外文題目PERFORMANCEANALYSISOFZSOURCEINVERTERFEDINDUCTIONMOTORDRIVE譯文題目Z源逆變器的驅(qū)動(dòng)性能分析學(xué)生姓名專業(yè)電氣工程及其自動(dòng)化指導(dǎo)教師姓名評(píng)閱日期圖1顯示了傳統(tǒng)三相電壓源逆變器一個(gè)大電容并聯(lián)在輸入側(cè)的直流電壓源上,在電容器兩端產(chǎn)生的電壓作為三相橋的激勵(lì),直流輸入可以是電池或燃料電池堆或二極管整流器,也可以是電容。三相橋式逆變電路含六個(gè)開關(guān),每一個(gè)開關(guān)由一個(gè)功率晶體管和一個(gè)反向并聯(lián)的二極管提供雙向電流流通和反向電壓阻斷能力。圖2為傳統(tǒng)電流源逆變器一個(gè)大電感在電源激勵(lì)下的響應(yīng)作為直流電流源。電源可以是電池,燃料電池堆,二極管整流器或變頻器等。電壓源逆變器的三相橋式逆變電路由六個(gè)開關(guān)組成,每個(gè)開關(guān)都是一個(gè)有反向阻斷能力的開關(guān)器件例如門極關(guān)斷晶閘管和可控硅或串聯(lián)二極管的功率晶體管來(lái)實(shí)現(xiàn)單向電流流動(dòng)和雙向電壓阻斷。電壓源型逆變器和電流源型逆變器的開關(guān)器件的開關(guān)時(shí)間是通過(guò)向控制終端(例如柵極)施加控制電壓而進(jìn)行控制的。圖2傳統(tǒng)電流源逆變器傳統(tǒng)上,大多數(shù)行業(yè)的電壓源型逆變器和電流源逆變器都是用來(lái)進(jìn)行可調(diào)速驅(qū)動(dòng),但是這些傳統(tǒng)逆變器有諸多局限。如下1)它們要么作為降壓變頻器要么作為升壓變頻器而不能即可升壓又可降壓,就是說(shuō)不能使輸出電壓可以任意大于或小于輸入電壓。電壓源逆變器的輸出電壓總是小于輸入電壓,被稱為降壓逆變器,因此該逆變器需要加入額外的升壓電路。而電流輸出電壓總是大于輸入電壓源逆變器,被稱為升壓逆變器,因此需要附加額外的電壓調(diào)節(jié)電路。這樣就增加了額外的成本2)電壓源逆變器和電流源逆變器的主要橋逆變電路不能互換。換句話說(shuō),電壓源逆變器主電路不能用于電流源逆變器,反之亦然。3)由電磁干擾造成的電壓源逆變器中的直通問(wèn)題和電流源逆變器的開路問(wèn)題降低了逆變器的可靠性。電壓源逆變器上下兩個(gè)晶體管不應(yīng)同時(shí)接通,否則會(huì)造成擊穿,可能會(huì)由于電流過(guò)大而損壞逆變電路。因此,需要加入死區(qū)時(shí)間來(lái)阻斷電壓源逆變器的上下開關(guān),而此舉會(huì)造成波形失真。4)電流源逆變器在上下兩個(gè)晶體管的情況下不應(yīng)同時(shí)關(guān)閉,否則會(huì)引起橋臂開路,由開路引起的電壓跌落可能會(huì)導(dǎo)致逆變電路損壞。因此在上下設(shè)備同時(shí)工
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簡(jiǎn)介:1中文中文53255325字一種對(duì)指紋預(yù)處理和特征提取的高效算法摘要摘要在實(shí)踐中,對(duì)于指紋掃描認(rèn)證的定位并沒(méi)有得到最大的重視,尤其是在注冊(cè)登記和對(duì)于拒絕正版用戶的結(jié)果的應(yīng)用上。此外,用戶行為和環(huán)境條件降低了對(duì)于指紋認(rèn)證的真正接受率。為了克服這些局限,一種有效的預(yù)處理算法被提了出來(lái),以獲得指紋認(rèn)證與分析的核心點(diǎn)周圍的垂直方向和高峰值曲率區(qū)域。這一算法的應(yīng)用分為兩個(gè)階段。獲得指紋垂直方向的過(guò)程是第一步執(zhí)行的。緊接著便是對(duì)指紋核心點(diǎn)的檢測(cè)。核心點(diǎn)的檢測(cè)可以識(shí)別任何類型的指紋。這種發(fā)達(dá)的算法是通過(guò)使用具有較大的內(nèi)部數(shù)據(jù)庫(kù)的基于行的特征提取算法和指紋識(shí)別競(jìng)賽樣品來(lái)測(cè)試的。要是沒(méi)有低質(zhì)量的圖像,那些導(dǎo)致存在于細(xì)節(jié)點(diǎn)中的差異的受損的峰值會(huì)被識(shí)別出來(lái)。提出了這一算法之后,94的受檢測(cè)的圖像會(huì)被垂直方向,它的真實(shí)性通過(guò)比較同一樣本中已定位和未定位的圖像中的詳細(xì)細(xì)節(jié)來(lái)驗(yàn)證的。關(guān)鍵詞關(guān)鍵詞垂直方向,高峰值曲率區(qū)域,核心點(diǎn)檢測(cè),特征提取。11引言引言指紋是指尖表面的脊和溝的圖案。在良好的或狹小的水平下,山谷和山脊的特征被稱為細(xì)節(jié)。事實(shí)上,指紋并沒(méi)有被精確地垂直方向,并且可能會(huì)產(chǎn)生相對(duì)于假定垂直方向±45°的偏離。在本論文中,指紋圖像旋轉(zhuǎn)被很好地執(zhí)行在對(duì)于高曲率區(qū)域圍繞核心點(diǎn)提取過(guò)程中的圖像增強(qiáng)之前。所以,一個(gè)好的定位模式可以提供一個(gè)樣本的綜合性狀,這一3在現(xiàn)實(shí)生活中,數(shù)據(jù)庫(kù)錄入的指紋并沒(méi)有完全垂直取向,并且可能取代尖瘦地遠(yuǎn)離垂直方向。AKJAIN等人表明圖像的旋轉(zhuǎn)通過(guò)在匹配階段對(duì)循環(huán)的特征值的特征編碼被部分處理。在將來(lái),圖像的旋轉(zhuǎn)將會(huì)通過(guò)從圖像數(shù)據(jù)中自動(dòng)確定指紋被正確處理。方向場(chǎng)通過(guò)采用基于神經(jīng)網(wǎng)絡(luò),基于梯度和基于過(guò)濾器的方法被可靠地估計(jì)出來(lái)。由于過(guò)濾器數(shù)量是有限的,基于過(guò)濾器的方法不如基于梯度的方法準(zhǔn)確。HONG等人提出一種以從一組已得的濾波后的圖像中估計(jì)方向場(chǎng)的分解方法,通過(guò)將一組GABOR濾波器應(yīng)用在輸入的指紋圖像上。雖然這種算法可以獲得更為可靠的方向估計(jì)即使是損壞的圖像,但是它繁雜的計(jì)算使得它不適用于在線驗(yàn)證系統(tǒng)。新提出的算法用來(lái)準(zhǔn)確跟蹤角位移,豎直翻轉(zhuǎn)圖片不會(huì)影響畫面質(zhì)量。當(dāng)非線性邊界曲線變得更高時(shí),很難準(zhǔn)確地檢測(cè)指紋核心。線性逼近的方法用來(lái)產(chǎn)生近似直線的段邊界曲線。曲率計(jì)數(shù)方向已經(jīng)被應(yīng)用于粗糙的核心點(diǎn)檢測(cè),與此同時(shí),區(qū)域技術(shù)幾何被應(yīng)用于精細(xì)的核心點(diǎn)檢測(cè)。然而這種算法不能定位指紋弧形結(jié)構(gòu)的核心點(diǎn)。已提出的一般的關(guān)系圖只有定向段之間的相鄰關(guān)系。擴(kuò)展關(guān)系圖有另外的介于段和每一段的方向邊界信息。核心檢測(cè)作為第二階段進(jìn)行?,F(xiàn)在的算法大多是基于龐加萊的計(jì)算指數(shù)的,利用的是計(jì)算的指紋的方向場(chǎng)。基于龐加萊指數(shù)的方法的缺點(diǎn)是傾向于回歸于奇異點(diǎn)的假陽(yáng)性檢測(cè),特別是質(zhì)量退化的指紋。擴(kuò)展關(guān)系圖包含了額外的介于段與每段方向的邊界信息。在所提出的方法中,方向被從細(xì)化的圖像然后是為核心點(diǎn)挑選候選像素的差角中計(jì)算出來(lái)。
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簡(jiǎn)介:中文中文4300字畢業(yè)設(shè)計(jì)論文外文資料翻譯學(xué)院電子工程與光電技術(shù)學(xué)院專業(yè)電子科學(xué)與技術(shù)姓名學(xué)號(hào)外文出處用外文寫附件1外文資料翻譯譯文;2外文原文。對(duì)NEA表面的影響是很大的。在本研究中,我們使用低能量電子顯微鏡(LEEM)檢測(cè)在不同的NEA制備方法,NEA表面降解,及熱加工中的NEA表面的變化情況。CS/O比采用AES監(jiān)測(cè)。在這些結(jié)論中,O和真空勢(shì)壘的影響也將被討論。二.實(shí)驗(yàn)LEEM儀器用來(lái)監(jiān)測(cè)兩個(gè)參數(shù)的依屬和時(shí)間演變過(guò)程(相對(duì)QE值和光電陰極的功函數(shù))通過(guò)LEEM光電子的投影柱強(qiáng)度來(lái)檢測(cè)相對(duì)QE值,也就是說(shuō),用電子顯微鏡(PEEM)模式。于功函數(shù)的測(cè)量,陰極連續(xù)發(fā)射電子束(LEEM模式),電子反射率的取決于樣品光電陰極之間的電壓差,同時(shí)記錄電子源(啟動(dòng)電壓)。測(cè)量時(shí),啟動(dòng)電壓比功函數(shù)小,電子反射率是100%(鏡面電子顯微鏡,MEM),啟動(dòng)電壓增加了電子注入的閾值而隨后反射率急劇下降。去卷積程序能非常精確的測(cè)量的功函數(shù)的變化這里,我們使用的交點(diǎn)嵌合于該反射的上方和下方的切線電子注入閾值(參照?qǐng)D1)。圖1反射率與啟動(dòng)電壓為砷化鎵清洗后(藍(lán)線)和NEA制備后(紅線)。功函數(shù)改變通過(guò)測(cè)量切線嵌合于該反射下車的交點(diǎn)上述注射閾值(虛線)確定。工業(yè)制作的光陰極P型(001)的GAAS體晶片,用ZN的摻雜劑濃度為1019CM3,GAA芯片的洗滌通過(guò)15千伏氬離子濺射和500℃退火,表面純度通過(guò)AES測(cè)量證
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簡(jiǎn)介:中文中文2742字ALOWCOST,SMARTCAPACITIVEPOSITIONSENSORABSTRACTANEWHIGHPERFORMANCE,LOWCOST,CAPACITIVEPOSITIONMEASURINGSYSTEMISDESCRIBEDBYUSINGAHIGHLYLINEAROSCILLATOR,SHIELDINGANDATHREESIGNALAPPROACH,MOSTOFTHEERRORSAREELIMINATEDTHEACCURACYAMOUNTSTO1ΜMOVERA1MMRANGESINCETHEOUTPUTOFTHEOSCILLATORCANDIRECTLYBECONNECTEDTOAMICROCONTROLLER,ANA/DCONVERTERISNOTNEEDEDIINTRODUCTIONTHISPAPERDESCRIBESANOVELHIGHPERFORMANCE,LOWCOST,CAPACITIVEDISPLACEMENTMEASURINGSYSTEMFEATURING1MMMEASURINGRANGE,1ΜMACCURACY,01STOTALMEASURINGTIMETRANSLATEDTOTHECAPACITIVEDOMAIN,THESPECIFICATIONSCORRESPONDTOAPOSSIBLERANGEOF1PFONLY50FFOFTHISRANGEISUSEDFORTHEDISPLACEMENTTRANSDUCER50AFABSOLUTECAPACITANCEMEASURINGINACCURACYMEIJERANDSCHRIERLANDMORERECENTLYVANDRECHT,MEIJER,ANDDEJONG2HAVEPROPOSEDADISPLACEMENTMEASURINGSYSTEM,USINGAPSDPOSITIONSENSITIVEDETECTORASSENSINGELEMENTSOMEDISADVANTAGESOFUSINGAPSDARETHEHIGHERCOSTSANDTHEHIGHERPOWERCONSUMPTIONOFTHEPSDANDLEDLIGHTEMITTINGDIODEASCOMPAREDTOTHECAPACITIVESENSORELEMENTSDESCRIBEDINTHISPAPERⅡTHEELECTRODESTRUCTURETHEBASICSENSINGELEMENTCONSISTSOFTWOSIMPLEELECTRODESWITHCAPACITANCECX,FIG2THESMALLERONEE2ISSURROUNDEDBYAGUARDELECTRODETHANKSTOTHEUSEOFTHEGUARDELECTRODE,THECAPACITANCECXBETWEENTHETWOELECTRODESISINDEPENDENTOFMOVEMENTSLATERALDISPLACEMENTSASWELLASROTATIONSPARALLELTOTHEELECTRODESURFACETHEINFLUENCEOFTHEPARASITICCAPACITANCESCPWILLBEELIMINATEDASWILLBEDISCUSSEDINSECTIONⅢACCORDINGTOHEERENS3,THERELATIVEDEVIATIONINTHECAPACITANCECXBETWEENTHETWOELECTRODESCAUSEDBYTHEFINITEGUARDELECTRODESIZEISSMALLERTHANΔEΠX/D1WHEREXISTHEWIDTHOFTHEGUARDANDDTHEDISTANCEBETWEENTHEELECTRODESTHISDEVIATIONINTRODUCESANONLINEARITYTHEREFOREWEREQUIRETHATΔISLESSTHAN100PPMALSOTHEGAPBETWEENTHESMALLELECTRODEANDTHESURROUNDINGGUARDCAUSESADEVIATIONΔEΠD/S2WITHSTHEWIDTHOFTHEGAPTHISDEVIATIONISNEGLIGIBLECOMPAREDTOL,WHENTHEGAPWIDTHISLESSTHAN1/3OFTHEDISTANCEBETWEENTHEELECTRODESANOTHERCAUSEOFERRORSORIGINATESFROMAPOSSIBLEFINITESKEWANGLEΑBETWEENTHETWOELECTRODESFIG3ASSUMINGTHEFOLLOWINGCONDITIONSTHEPOTENTIALSONTHESMALLELECTRODEANDTHEGUARDELECTRODEAREEQUALTO0V,THEPOTENTIALONTHELARGEELECTRODEISEQUALTOVVOLT,THEGUARDELECTRODEISLARGEENOUGH,ITCANBESEENTHATTHEELECTRICFIELDWILLBECONCENTRIC
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簡(jiǎn)介:第88頁(yè)中文中文5100字出處出處COMPUTERSININDUSTRY562005442–456附錄ACAD/CAE/CAM在提高快速成形系統(tǒng)中的綜合應(yīng)用在提高快速成形系統(tǒng)中的綜合應(yīng)用YOUMINHUANG,HSIANGYAOLAN摘要摘要立體打印是一種利用光敏聚合物為原材料制作產(chǎn)品原型的快速成形(RP)技術(shù)。光敏聚合體快速成型工藝?yán)眉す饣騽e的光源選擇性地?zé)Y(jié)液態(tài)樹脂。樹脂吸收的能量產(chǎn)生光聚作用使液態(tài)樹脂固化,加工過(guò)的部分在膨脹的同時(shí)會(huì)產(chǎn)生收縮。光聚合加工中被加工部分樹脂的收縮和卷曲變形是這種快速成型技術(shù)精度較低的主要原因,特別是當(dāng)工件是中空的時(shí)候,此時(shí)由于彎曲應(yīng)力不能被補(bǔ)償而會(huì)導(dǎo)致嚴(yán)重的彎曲變形。通常情況下,設(shè)計(jì)者會(huì)設(shè)計(jì)一個(gè)支撐來(lái)限制原型的更大的彎曲和變形。但是,當(dāng)支撐從原型內(nèi)移除的時(shí)候,原型的幾何表面很容易被破壞而變形,所以時(shí)間會(huì)有浪費(fèi)。這項(xiàng)研究最初使用動(dòng)態(tài)的有限元仿真編碼模擬光聚作用,測(cè)定工件外表面的扭曲變形以降低變形量。由此提出一個(gè)反向變形的修正方法用于工件外表面的變形。人們制造了一種新的變形補(bǔ)償CAD模型并把它載入快速成型機(jī)中用于實(shí)際原型工藝,以提高工藝的精度。最終,“H4”診斷單元成為檢驗(yàn)此項(xiàng)實(shí)驗(yàn)的原例。修正補(bǔ)償后的仿真和試驗(yàn)結(jié)果被證明是正確的。關(guān)鍵詞關(guān)鍵詞計(jì)算機(jī)輔助設(shè)計(jì)立體印刷快速成型有限元法卷曲變形11概述概述工業(yè)競(jìng)爭(zhēng)加速了快速成型系統(tǒng)的發(fā)展。快速成型系統(tǒng)的使用可以促進(jìn)R粘性壓力Σ(T)是時(shí)間T的函數(shù)。{ΕT}是熱應(yīng)變率,能夠表示為{ΑΤ};{ΕΓ}是由凝固收縮引起的應(yīng)變,{ΕP}是塑膠應(yīng)變率,在光聚過(guò)程中塑性應(yīng)變很小且能被忽略。在這種情況里,{Σ}等于DE{Ε},{Ε}等于B{U},代入上面的關(guān)系和∫VBTDV到等式(1),產(chǎn)生了下面的等式∫VBTDEB{U}-BT{Σ}-BT(3K){ΑΤΔΒI}DV02因此,立體圖形工藝的動(dòng)態(tài)有限元分析中構(gòu)建的公式能表示為K{U}-{F}03這里K∫VBTDEBDV4{F}∫VBT{Σ}BT(3K){ΑΤΔΒI}DV5在上面的公式當(dāng)中,K是剛度矩陣;{U}是節(jié)替代增量;{F}是有效節(jié)點(diǎn)力的增量;B代表應(yīng)變率速率矩陣;BT是轉(zhuǎn)置矩陣;DE是壓力應(yīng)變矩陣;V是作用區(qū)的體積;{Σ}是節(jié)點(diǎn)粘性壓力且是時(shí)間的函數(shù);K是體積系數(shù);Α是線性膨脹系數(shù);T是溫度增量,ΔΒI作為與凝固收縮相關(guān)的應(yīng)變,是光強(qiáng)I與流逝時(shí)間T的函數(shù)22掩膜型樣機(jī)的能量分配當(dāng)光穿過(guò)掩膜到樹脂表面時(shí),在表面上能量擴(kuò)散的分布狀態(tài)和均勻性影響固化層的厚度。因此,穿過(guò)掩膜的光的能量和投射到樹脂表面的能量必須使用一個(gè)數(shù)學(xué)模型來(lái)計(jì)算決定掩膜的能量。邊長(zhǎng)為A的正方形作為例子,光源能量的強(qiáng)度是I0正方形掩膜中心點(diǎn)定義為X0和Y0,帶有示意圖2中所描述的能量。在光穿過(guò)掩膜后,在正方形外形輪廓上任意一點(diǎn)的強(qiáng)度由以下公式給出ID1/4I0CX2CY2CX2SY2SX2CY2SX2SY26相關(guān)的系數(shù),C和S,如下定義這里
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簡(jiǎn)介:1中文中文58005800字出處出處INTERNATIONALJOURNALOFFATIGUE,2013,5617TP347H奧氏體不銹鋼在550℃低循環(huán)疲勞下的動(dòng)態(tài)應(yīng)變時(shí)效對(duì)應(yīng)變幅度的影響HONGWEIZHOU,YIZHUHE,MIANCUI,YUWANCEN,JIANQINGJIANGASCHOOLOFMATERIALSSCIENCEANDENGINEERING,JIANGSUKEYLABOFADVANCEDMETALLICMATERIALS,SOUTHEASTUNIVERSITY,NANJING,211189JIANGSHU,PRCHINABSCHOOLOFMATERIALSSCIENCEANDENGINEERING,ANHUIKEYLABOFMATERIALSSCIENCEANDPROCESSING,ANHUIUNIVERSITYOFTECHNOLOGY,MAANSHAN,243002ANHUI,PRCHINACSCHOOLOFMECHANICALENGINEERING,ANHUIUNIVERSITYOFTECHNOLOGY,MAANSHAN,243002ANHUI,PRCHINAARTICLEINFOARTICLEHISTORYRECEIVED1MARCH2013RECEIVEDINREVISEDFORM4JULY2013ACCEPTED6JULY2013AVAILABLEONLINE27JULY20133溫下,在交變應(yīng)力和單調(diào)拉伸載荷作用時(shí),DSA通常對(duì)應(yīng)激反應(yīng),LCF的發(fā)生,ASS的微觀結(jié)構(gòu)2和8有顯著影響。據(jù)報(bào)道,在LCF負(fù)載下DSA機(jī)制與在拉伸載荷下的DSA機(jī)制一致10。DSA表現(xiàn)形式為應(yīng)力應(yīng)變曲線上鋸齒狀,環(huán)狀峰值應(yīng)力和軟化比率與溫度負(fù)相關(guān)9。盡管認(rèn)為鋸齒狀突起是DSA的表現(xiàn)形式之一,但最近的研究已經(jīng)發(fā)現(xiàn),對(duì)316L(N)的循環(huán)加載,DSA則發(fā)生在鋸齒狀之前2和10。在DSA機(jī)制下,循環(huán)變形位錯(cuò)的結(jié)構(gòu)和無(wú)DSA機(jī)制時(shí)不同,這是由于位錯(cuò)和雜質(zhì)原子(如C或N在250450℃,鉻在450650℃)時(shí)的相互作用2,11和12。與無(wú)DSA機(jī)制的晶粒相比,DSA機(jī)制下的平面結(jié)構(gòu)能造成位錯(cuò)結(jié)構(gòu)改變。一般來(lái)說(shuō),在DSA機(jī)制下可以觀察到兩種類型的平面結(jié)構(gòu),即平面的滑移帶8,9,13和14和燈芯絨結(jié)構(gòu),其中燈芯絨結(jié)構(gòu)已在250450℃的真空中投入研究15,并且最近有研究發(fā)現(xiàn)了300℃空氣中循環(huán)載荷作用下的燈芯絨結(jié)構(gòu)16。在250至450℃介質(zhì)溫度范圍內(nèi),溶質(zhì)原子的鈴木氣團(tuán)11和16,或SNOEK氣團(tuán)用短程順序(SRO)的特性限制了位錯(cuò)的交叉滑移17,從而產(chǎn)生位錯(cuò)結(jié)構(gòu)的多個(gè)平面特征。固溶CR原子氣團(tuán)在低氮ASS或CRNSRO13和18或高氮316ASS中,在500650℃的溫度范圍內(nèi)能有效固定位錯(cuò),這造成位錯(cuò)在特定平面滑移,表現(xiàn)為平面結(jié)構(gòu)。溶質(zhì)原子氣團(tuán)可以有效固定位錯(cuò),從而獲得更高的固定位錯(cuò)密度。由于溶質(zhì)的固定,LCF期間,在平面滑移帶之間緩慢移動(dòng)的位錯(cuò)提高變形的不均勻程度。由于DSA,微觀平面在主要應(yīng)激反應(yīng)階段和二次循環(huán)硬化的最后階段造成循環(huán)硬化。據(jù)報(bào)道,DSA降低LCF的壽命,這是由于DSA誘發(fā)循環(huán)硬化,從而加速裂紋產(chǎn)生和擴(kuò)展7,9和14。根據(jù)這些研究7,9和14,可以看出簡(jiǎn)單的位錯(cuò)結(jié)構(gòu)的發(fā)展就是平面結(jié)構(gòu)在晶粒有DSA機(jī)制和無(wú)DSA機(jī)制下的發(fā)展。眾所周知,位錯(cuò)的結(jié)構(gòu)依賴于LCF在RT下的應(yīng)變幅度19。我們發(fā)現(xiàn)在循環(huán)應(yīng)力應(yīng)變曲線中的位錯(cuò)結(jié)構(gòu)設(shè)在APΕ(塑性應(yīng)變幅度001%時(shí))產(chǎn)生平面狀位錯(cuò),則不完整的脈狀結(jié)構(gòu)與持久滑移帶的APΕ在001%和01%之間,并且晶粒結(jié)構(gòu)%01ΕAP?。
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簡(jiǎn)介:中文中文51005100字出處出處THEINTERNATIONALJOURNALOFADVANCEDMANUFACTURINGTECHNOLOGY,2009,42788138213軸并聯(lián)銑床的功能模擬裝置軸并聯(lián)銑床的功能模擬裝置摘要摘要并聯(lián)機(jī)床是很多實(shí)驗(yàn)室的研發(fā)對(duì)象,但不幸的是它們中的許多連一臺(tái)并聯(lián)機(jī)床也沒(méi)有。因此,使用低成本的3軸并聯(lián)銑床的功能模擬裝置被認(rèn)為有助于獲得并聯(lián)機(jī)床領(lǐng)域的基本經(jīng)驗(yàn)。這個(gè)想法是基于模擬裝置能被常規(guī)的3軸數(shù)控機(jī)床(CNC)驅(qū)動(dòng)控制的可能性。本文介紹了一個(gè)模擬裝置的開發(fā)過(guò)程,包括一個(gè)相應(yīng)的并聯(lián)機(jī)構(gòu)的選擇、運(yùn)動(dòng)學(xué)建模和算法編程。在完整的運(yùn)行條件下,一些軟質(zhì)材料的標(biāo)準(zhǔn)試件的成功制造已經(jīng)驗(yàn)證了功能模擬裝置的想法。關(guān)鍵詞關(guān)鍵詞并聯(lián)機(jī)床功能模擬裝置;建模與測(cè)試11引言引言在世界各地,教育和培訓(xùn)的戰(zhàn)略重要性,尤其在技術(shù)和科學(xué)學(xué)科,正在不斷增加。這也適用于并聯(lián)機(jī)床(PKMS),這是當(dāng)今世界研發(fā)(RD)和教育的課題之一。與并聯(lián)機(jī)床有關(guān)的多方面的基本知識(shí)已經(jīng)出版1。許多不同的具有36個(gè)自由度的并聯(lián)拓?fù)浣Y(jié)構(gòu)已經(jīng)使用,其中包括3平移正交并聯(lián)機(jī)構(gòu)15。不幸的是,今天絕大多數(shù)科研院所、高校實(shí)驗(yàn)室和公司都沒(méi)有并聯(lián)機(jī)床。很明顯,究其原因,是因?yàn)榕嘤?xùn)一項(xiàng)新技術(shù)的成本高,例如并聯(lián)機(jī)床。為了有助于獲得并聯(lián)機(jī)床的建模、設(shè)計(jì)、控制、編程和使用的實(shí)際經(jīng)驗(yàn),一個(gè)低成本的能模擬3軸并聯(lián)銑床的功能模擬裝置被提出2。這個(gè)想法是基于模擬裝置能被常規(guī)的3軸數(shù)控機(jī)床(CNC)驅(qū)動(dòng)控制的可能性。由于常規(guī)的3軸數(shù)控機(jī)床的軸是相互正交的,不同的由正交平移運(yùn)動(dòng)副構(gòu)成的3自由度的空間并聯(lián)機(jī)構(gòu)可能被用來(lái)構(gòu)建模擬裝置2,7。2由于立式和臥式的3軸數(shù)控串聯(lián)機(jī)床的軸是正交的,同時(shí)又是驅(qū)動(dòng)模擬裝置的軸,如果3自由度空間并聯(lián)模擬裝置的機(jī)構(gòu)也具有正交的平移運(yùn)動(dòng)副,那將是最好不過(guò)了。由于串聯(lián)數(shù)控機(jī)床的軸是耦合的,所以在一般情況下,至少有一個(gè)2自由度的從動(dòng)串聯(lián)機(jī)構(gòu)來(lái)為它們解耦是必要的。與模擬裝置最配套的圖1功能模擬裝置結(jié)構(gòu)數(shù)控機(jī)床是那些具有可移動(dòng)的刀架和工作臺(tái)的機(jī)床。在這樣的結(jié)構(gòu)中,三個(gè)軸中有兩個(gè)是耦合的,因此,需要用一個(gè)2自由度的從動(dòng)串聯(lián)機(jī)構(gòu)來(lái)為它們解耦并驅(qū)動(dòng)模擬裝置。臥式和立式3軸數(shù)控機(jī)床的運(yùn)動(dòng)結(jié)構(gòu)并沒(méi)有分類,一些具有正交平移運(yùn)動(dòng)副的3自由度空間并聯(lián)機(jī)構(gòu)已經(jīng)被考慮并在模擬裝置中使用,這些實(shí)例如圖2所示。它們的工作空間的形狀也被展示在圖2中。上述類似的機(jī)構(gòu)實(shí)例是圖1所示的基本結(jié)構(gòu)的正逆運(yùn)動(dòng)學(xué)問(wèn)題的解決方案不同的結(jié)果。
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簡(jiǎn)介:1中文中文9200字出處出處JKOGOV?EK,MREM?KAR,MKALINLUBRICATIONOFDLCCOATEDSURFACESWITHMOS2,NANOTUBESINALLLUBRICATIONREGIMESSURFACEROUGHNESSANDRUNNINGINEFFECTSJWEAR,2013,3031–2361370LUBRICATION的DLC涂層表面MOS2納米管的潤(rùn)滑機(jī)制表面粗糙度和磨合效果摘要二硫化鉬和WS2納米粒子,一方面,與DLC涂層相結(jié)合,另一方面,正受到越來(lái)越多的摩擦學(xué)應(yīng)用的關(guān)注。然而,調(diào)查研究表明將納米粒子DLC涂層和潤(rùn)滑兩個(gè)概念聯(lián)系在一起是非常少的,并且這方面的研究成果也非常有限。在這項(xiàng)工作中,我們通過(guò)研究表面粗糙度的影響,來(lái)認(rèn)識(shí)潤(rùn)滑系統(tǒng),并在所有潤(rùn)滑機(jī)制下研究DLC涂層。我們還提出了一種有關(guān)表面粗糙度如何影響二硫化鉬納米管潤(rùn)滑效果的模型。該模型是基于2D,11工程尺度的投影,包括粗糙度,納米粒子和薄膜厚度,是一種獨(dú)立的接觸材料。眾所周知,通過(guò)添加納米管到基礎(chǔ)油中來(lái)降低摩擦系數(shù),DLC的添加量達(dá)到50%以上時(shí)表面會(huì)平滑,類金剛石涂層的表面和相,要高達(dá)40%DLC涂覆才會(huì)使表面光滑。在邊界光滑的條件下,納米顆粒是最有效的,并且對(duì)EHL機(jī)制的影響可以忽略。表面粗糙度具有明顯雙重效果當(dāng)摩擦較低的表面比較粗糙時(shí),與類金剛石涂層的表面對(duì)比,粗糙表面是能夠在工件運(yùn)用期間更好地保留納米粒子。(與2013愛(ài)思唯爾BV保留所有權(quán)利。)關(guān)鍵詞納米粒子,DLC,二硫化鉬納米管,表面粗糙度,油,潤(rùn)滑油添劑3果,2維簡(jiǎn)稱AE,表面輪廓實(shí)際是11投影比例,納米顆粒,膜和薄膜厚度也同樣。
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簡(jiǎn)介:外文文獻(xiàn)原文24中文中文48404840字外文文獻(xiàn)原文外文文獻(xiàn)原文RAPIDMIMOOFDMSOFTWAREDEFINEDRADIOSYSTEMPROTOTYPINGAMITGUPTA,ANTONIOFORENZA,ANDROBERTWHEATHJRWIRELESSNETWORKINGANDCOMMUNICATIONSGROUPDEPARTMENTOFELECTRICALANDCOMPUTERENGINEERING,THEUNIVERSITYOFTEXASATAUSTIN1UNIVERSITYSTATIONC0803,AUSTIN,TX787120240USAPHONE15122322014,FAX15124716512{AGUPTA,FORENZA,RHEATH}ECEUTEXASEDUABSTRACTMULTIPLEINPUTMULTIPLEOUTPUTMIMOISANATTRACTIVETECHNOLOGYFORFUTUREWIRELESSSYSTEMSMIMOCOMMUNICATION,ENABLEDBYTHEUSEOFMULTIPLETRANSMITANDMULTIPLERECEIVEANTENNAS,ISKNOWNFORITSHIGHSPECTRALEFFICIENCYASWELLASITSROBUSTNESSAGAINSTFADINGANDINTERFERENCECOMBININGMIMOWITHORTHOGONALFREQUENCYDIVISIONMULTIPLEXINGOFDM,ITISPOSSIBLETOSIGNIFICANTLYREDUCERECEIVERCOMPLEXITYASOFDMGREATLYSIMPLIFIESEQUALIZATIONATTHERECEIVERMIMOOFDMISCURRENTLYBEINGCONSIDEREDFORANUMBEROFDEVELOPINGWIRELESSSTANDARDSCONSEQUENTLY,THESTUDYOFMIMOOFDMINREALISTICENVIRONMENTSISOFGREATIMPORTANCETHISPAPERDESCRIBESANAPPROACHFORPROTOTYPINGAMIMOOFDMSYSTEMUSINGAFLEXIBLESOFTWAREDEFINEDRADIOSDRSYSTEMARCHITECTUREINCONJUNCTIONWITHCOMMERCIALLYAVAILABLEHARDWAREANEMPHASISONSOFTWAREPERMITSAFOCUSONALGORITHMANDSYSTEMDESIGNISSUESRATHERTHANIMPLEMENTATIONANDHARDWARECONFIGURATIONTHEPENALTYOFTHISFLEXIBILITY,HOWEVER,ISTHATTHEEASEOFUSECOMESATTHEEXPENSEOFOVERALLTHROUGHPUTTOILLUSTRATETHEBENEFITSOFTHEPROPOSEDARCHITECTURE,APPLICATIONSTOMIMOOFDMSYSTEMPROTOTYPINGANDPRELIMINARYMIMOCHANNELMEASUREMENTSAREPRESENTEDADETAILEDDESCRIPTIONOFTHEHARDWAREISPROVIDEDALONGWITHDOWNLOADABLESOFTWARETOREPRODUCETHESYSTEMIINTRODUCTIONMULTIPLEINPUTMULTIPLEOUTPUTMIMOWIRELESSSYSTEMSUSEMULTIPLETRANSMITANDMULTIPLERECEIVEANTENNASTOINCREASECAPACITYANDPROVIDEROBUSTNESSTOFADING1TOOBTAINTHESEBENEFITSINBROADBANDCHANNELSWITHEXTENSIVEFREQUENCYSELECTIVITY,MIMOCOMMUNICATIONLINKSREQUIRECOMPLEXSPACETIMEEQUALIZERSTHECOMPLEXITYOFMIMOSYSTEMSCANBEREDUCED,HOWEVER,THROUGHORTHOGONALFREQUENCYDIVISIONMULTIPLEXINGOFDMOFDMISANATTRACTIVEDIGITALMODULATIONTECHNIQUETHATPERMITSGREATLYSIMPLIFIEDEQUALIZATIONATTHERECEIVERWITHOFDM,THEMODULATEDSIGNALISEFFECTIVELYTRANSMITTEDINPARALLELOVERNORTHOGONALFREQUENCYTONESTHISCONVERTSAWIDEBANDFREQUENCYSELECTIVECHANNELINTONNARROWBANDFLATFADINGCHANNELSCURRENTLYOFDMISUSEDINMANYWIRELESSDIGITALCOMMUNICATIONSYSTEMS,SUCHASTHEIEEE80211A/G2,3STANDARDSFORWIRELESSLOCALAREANETWORKSWLANSMIMOOFDMTECHNOLOGYISINTHEPROCESSOFBEINGSTANDARDIZEDBYTHEIEEETECHNICALGROUP80211N4AND外文文獻(xiàn)原文26CHANNELMEASUREMENTSININDOORENVIRONMENTSIIMIMOOFDMIMPLEMENTATIONINTHISSECTIONWEREVIEWTHEMIMOOFDMSIGNALMODELANDTHENDESCRIBEOURSPECIFICMIMOOFDMSYSTEMIMPLEMENTATIONAMIMOOFDMSIGNALMODELINAMIMOOFDMSYSTEMSEE8ANDTHEREFERENCESTHEREINMIMOSPACETIMECODESARECOMBINEDWITHOFDMMODULATIONATTHETRANSMITTERWHILECOMPLICATEDSPACETIMEFREQUENCYPROCESSINGISEMPLOYEDATTHERECEIVERFORSIMPLICITYOFEXPLANATION,WECONSIDERSPATIALMULTIPLEXINGASILLUSTRATEDINFIG1THOUGHITWILLBEAPPARENTTHATOTHERTRANSMISSIONTECHNIQUESCANBEIMPLEMENTEDINTHEPROPOSEDARCHITECTUREINAMIMOOFDMSYSTEMWITHMTTRANSMITANTENNASANDMRRECEIVEANTENNAS,THESAMPLEDSIGNALATTHERECEIVERAFTERTHEFFTANDREMOVINGTHECYCLICPREFIXOFASPATIALMULTIPLEXINGMIMOSYSTEMFOROFDMSYMBOLPERIODNANDTONEKCANBEEXPRESSEDBYTHEFOLLOWINGEQUATIONASSUMINGPERFECTLINEARITY,TIMING,ANDSYNCHRONIZATION11,,,,NKNKNKNKYHSW??THEEQUALIZATIONINMIMOOFDMSYSTEMSMAYBEENABLEDTHROUGHDIFFERENTPROCEDURESSUCHASZEROFORCINGEQUALIZER,MINIMUMMEANSQUAREDERROREQUALIZER,VBLASTSUCCESSIVECANCELLINGEQUALIZER,SPHEREDECODER,ANDMAXIMUMLIKELIHOODDECODERSEE1FORANOVERVIEWINOURPROTOTYPEWECURRENTLYIMPLEMENTTHEZEROFORCINGEQUALIZERTHEFLEXIBILITYOFTHEPROPOSEDARCHITECTURETHOUGHALLOWSUSTOPROTOTYPEMORESOPHISTICATEDEQUALIZATIONSTRATEGIESBSYSTEMIMPLEMENTATIONANDSPECIFICATIONSTHEFIRSTIMPLEMENTATIONFEATURESSPATIALMULTIPLEXINGWITHTWOTRANSMITANDTWORECEIVEANTENNAS,ASILLUSTRATEDINFIG1OTHERMIMOSCHEMESAREALREADYAVAILABLEINTHELABVIEWMIMOTOOLKIT14,ANDWEAREPLANNINGTOUSETHISTOIMPLEMENTOTHERSPACEFREQUENCYCODESINTHEFUTURETHESPECIFICATIONSOFTHESYSTEMARELISTEDINTABLEIINOURMIMOOFDMIMPLEMENTATION,OFDMWITH64TONESISEMPLOYEDOVERA16MHZBANDWIDTHTHECYCLICPREFIXIS16SAMPLESLONGTHISCORRESPONDSTOANOFDMSYMBOLDURATIONOF5ΜS,WITHAGUARDINTERVALOF1ΜSANDADATAPORTIONOF4ΜSWETRANSMITOUROFDMSYMBOLSIN200MSDATAPACKETSTHIS200MSWASDETERMINEDBYOURHARDWAREASMEMORYCONSTRAINTSATTHERECEIVERPREVENTEDLONGERACQUISITIONPERIODSTHESYSTEMISEQUIPPEDWITHANADJUSTABLECARRIERFREQUENCYWECHOSETORUNOURSYSTEMAT24GHZ,WHICHISTHECARRIERFREQUENCYUSEDFORWLANS2,3VARIOUSMODULATIONSCHEMESAREPOSSIBLEBPSK,QPSK,16QAM,64QAMALONGWITHOPTIONALCONVOLUTIONALCODINGCHANNELESTIMATIONISCARRIEDOUTBYPERIODICALLYTRANSMITTINGANOFDMTRAININGSYMBOLTHEFREQUENCYATWHICHTRAININGSYMBOLSARESENTCANBEPROGRAMMATICALLYCHANGEDINTHESOFTWAREANDDEPENDSONTHEEXPECTEDVARIATIONOFTHECHANNELTHEESTIMATIONATTHERECEIVERISENABLEDBYTHEPILOTSYMBOLS,SENTOUTOVERORTHOGONALTONESACROSSTHETRANSMITANTENNASWETHENUSEALINEARINTERPOLATIONACROSSTHETONESTOESTIMATETHECHANNEL’SFULLFREQUENCYRESPONSEONCEWEHAVEACHANNELESTIMATE,THEDATAIS
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簡(jiǎn)介:高斯消去法是穩(wěn)定的反對(duì)角占優(yōu)矩陣高斯消去法是穩(wěn)定的反對(duì)角占優(yōu)矩陣阿蘭喬治和KHAKIMDIKRAMOV摘要假設(shè)B∈MNC是一個(gè)行對(duì)角占優(yōu)矩陣,即,,N,,1I,BBNIJ1JIJIII???????當(dāng)0≤<1,I1,,N,且,我們的分析表明,當(dāng)高斯消去法被應(yīng)用于???NI1MAX??I?時(shí),沒(méi)有旋轉(zhuǎn)是必要的。此外,增長(zhǎng)因子A不會(huì)超過(guò)同樣的結(jié)果顯示行對(duì)角1??BA??1優(yōu)勢(shì)的確會(huì)被列對(duì)角優(yōu)勢(shì)所取代1引言引言我們開始了一個(gè)報(bào)價(jià)從N海厄姆的論文1當(dāng)計(jì)算一LU因式分解時(shí),主要有三類矩陣是已知的沒(méi)有安全軸的矩陣對(duì)角占優(yōu)的行或列,厄米正定矩陣,和完全非負(fù)矩陣?!弊髡呃^續(xù)說(shuō)道“確定另一類矩陣非??扇〉膶傩詮?fù)雜對(duì)稱矩陣的實(shí)部和虛部都是正定的?!北疚奈覀償U(kuò)展的矩陣具有此屬性包括矩陣的逆矩陣對(duì)角占優(yōu)的行或列,由此我們得出,生長(zhǎng)因子等矩陣的。讀者會(huì)在3節(jié)發(fā)現(xiàn)證明,在2節(jié)發(fā)現(xiàn)初步證明所需材料。2初步證實(shí)令A(yù)∈MNC,一套復(fù)雜的NN矩陣索引集,我們的主要矩??N,,1???陣表示A位于行和列索引以及A并且與其互補(bǔ)的主矩陣為A接下來(lái)最??A重要是引理3。引理引理1令A(yù)∈MNC是一個(gè)非奇異矩陣,并且B令是的一個(gè)1A???N,,1?子集不等式如下1DETDETDET/???AAA?一個(gè)積極的標(biāo)量反之,如果類似的不等式?2DETDETDET/???BBB?則通過(guò)矩陣B證明,不等式2只不過(guò)是不等式1的另外一種形式這可以由以是指數(shù)集7不等式如下9IJJIKIJKJINAAA,,,MAXMAX?)?A被稱為生長(zhǎng)因子。DD矩陣的性質(zhì)和高斯消去法是廣為人知的。我們將會(huì)在第三節(jié)陳述以下我們需要的引理引理引理4令B∈MNC是一個(gè)DD矩陣且具有航優(yōu)勢(shì)因子I?見(jiàn)3然后我們可以得出1高斯消去法在任何對(duì)角旋轉(zhuǎn)規(guī)則下適用于B。2對(duì)角占優(yōu)矩陣具有積極的遺傳屬性。換句話說(shuō),每個(gè)SCHUR補(bǔ)B/B同樣?是一個(gè)DD矩陣此外,對(duì)每一個(gè)I來(lái)說(shuō),行優(yōu)勢(shì)因子是超越不了B/B的。I??這個(gè)相應(yīng)的因子也是超越不了B的假設(shè)原始行指數(shù)B在行B/B留下I??了”ATTACHED“3主要結(jié)果現(xiàn)在我們開始證明定理定理1令A(yù)∈MNC是一個(gè)非奇異矩陣,比如說(shuō)B是一個(gè)具有行優(yōu)勢(shì)因1A子看4的DD矩陣。然后我們可以得出?10????1N)(A證明由引理2可以得出,A11是在第一列最大的模數(shù)記錄。于是可以得出,A11可以作為最關(guān)鍵的第一步消除。設(shè)定,我們可以從8看到A/A與???1???DD矩陣B互逆因此我們可以得出,在A/A中和第一列最大的模數(shù)記‘????)(122A錄一致并且可以作為重要的第二步消去。重復(fù)上述步驟,我們可以得出以下結(jié)論在A中,沒(méi)有有排列需要執(zhí)行高斯消去法而且高斯消去法應(yīng)用于A時(shí)的旋轉(zhuǎn)不完全和A的部分旋轉(zhuǎn)相同。事實(shí)上,關(guān)系6的真正意思是在所有的矩陣A中,這項(xiàng)最大模數(shù)是主對(duì)角線這個(gè)結(jié)論在SCHUR補(bǔ)A/A中同樣成立。由此可見(jiàn),在之下我們不得不在???NA(?對(duì)角項(xiàng)的排除過(guò)程中只檢查這種行為。由此我們假定,,MAXTRETSRAM?在RSITK的情況下實(shí)現(xiàn)。我們規(guī)定??,,,1K????,I????
下載積分: 10 賞幣
上傳時(shí)間:2024-03-12
頁(yè)數(shù): 11
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簡(jiǎn)介:ENVIRONMENTALLIFECYCLEASSESSMENTOFBRIDGESJOHANNEHAMMERVOLD1MARTEREENAAS2ANDHELGEBRATTEB?3ABSTRACTTHISPAPERPRESENTSADETAILEDCOMPARATIVEENVIRONMENTALLIFECYCLEASSESSMENTLCACASESTUDYOFTHREEBUILTBRIDGESINNORWAYTOENCOMPASSAWIDESCALEOFBRIDGEDESIGNS,THEANALYSISDEALTWITHASTEELBOXGIRDERBRIDGE,ACONCRETEBOXGIRDERBRIDGE,ANDAWOODENARCHBRIDGETHISSTUDYPRESENTSTHEFIRSTLCAOFROADBRIDGESUSINGASTANDARDIZEDBRIDGECLASSIFICATIONTHELCAINCLUDESAWIDERANGEOFPOLLUTANTSANDAHIGHLEVELOFDETAILINLIFECYCLEMATERIALANDENERGYCONSUMPTIONFINDINGSHEREANDFROMEARLIERLCASONBRIDGESARETOGETHERUSEDASBASESFORGENERALRECOMMENDATIONSONCONDUCTINGLCASONBRIDGESTHESTUDYSHOWSTHATITISTHEPRODUCTIONOFMATERIALSFORTHEMAINLOADCARRYINGSYSTEMSIE,THEBRIDGESUPERSTRUCTUREANDTHEABUTMENTSTHATACCOUNTSFORTHEMAINSHAREOFTHEENVIRONMENTALIMPACTS,ASTHESEPARTSREQUIRELARGEQUANTITIESOFMATERIALS,WITHALIMITEDNUMBEROFMATERIALSBEINGTHEIMPORTANTONESTHECONSTRUCTIONPHASEACCOUNTSFORRELATIVELYFEWERIMPACTSTHEUSEPHASECONTRIBUTESMORESIGNIFICANTLY,MAINLYBECAUSEOFRESURFACINGWITHASPHALTUSEOFBUILDINGEQUIPMENTANDTRANSPORTOFPERSONNELINALLTHELIFECYCLEPHASESAREOFMINORIMPORTANCE,ASARETHEUSEOFFORMWORK,MASTIC,BLASTING,ANDTHEENDOFLIFEINCINERATIONOFWOODTHEENVIRONMENTALISSUESOFGLOBALWARMING,ABIOTICDEPLETION,ANDACIDIFICATIONAREFOUNDTOBETHEMOSTIMPORTANTGIVENTHEASSUMPTIONSMADEINTHISSTUDYACOMPARISONOFTHETHREEBRIDGESSHOWSTHATTHECONCRETEBRIDGEALTERNATIVEPERFORMSBESTENVIRONMENTALLYONTHEWHOLE,BUTWHENITCOMESTOGLOBALWARMING,THEWOODENBRIDGEISBETTERTHANTHEOTHERTWOTHERESULTSSUPPORTTHEIDEATHATITISPOSSIBLETODECIDEUPONENVIRONMENTALLYEFFECTIVEDESIGNALTERNATIVES,ATAFAIRLEVELOFACCURACY,ATDIFFERENTSTAGESOFTHEBRIDGEDESIGNPROCESS,ATARGETTHATISNOWBECOMINGMOREANDMOREEMPHASIZEDINTHEBRIDGEENGINEERINGSECTORDOI101061/ASCEBE194355920000328?2013AMERICANSOCIETYOFCIVILENGINEERSCEDATABASESUBJECTHEADINGSBRIDGESCONSTRUCTIONLIFECYCLESENVIRONMENTALISSUESDECISIONMAKINGAUTHORKEYWORDSBRIDGECONSTRUCTIONBRIDGEMANAGEMENTLIFECYCLEASSESSMENTENVIRONMENTALIMPACTDECISIONMAKINGSUPPORTINTRODUCTIONAFINNISH,SWEDISH,ANDNORWEGIANRESEARCHCOLLABORATION,THEETSIPROJECTSALOKANGAS2010,WASLAUNCHEDIN2006ANDALSOINCLUDEDDENMARKFROM2009ONWARDSTHISPROJECTAIMSATBRIDGELIFECYCLEOPTIMIZATIONANDINCLUDESECONOMIC,ENVIRONMENTAL,ANDAESTHETICISSUESSPANNINGTHEENTIRELIFETIMEOFTHEBRIDGETHENORWEGIANGROUPHASBEENWORKINGONTHEENVIRONMENTALISSUESANDHASDEVELOPEDATOOLFORENVIRONMENTALLIFECYCLEASSESSMENTLCAOFBRIDGES,CALLEDBRIDGELCABRATTEB?ETAL2009THISTOOLALLOWSFORDETAILEDLCASOFBRIDGES,REVEALINGWHATMATERIALSANDPARTSCAUSEIMPACTSANDATWHATSTAGEINTHELIFETIMEOFTHEBRIDGETHESEIMPACTSOCCURTHISARTICLEPRESENTSACASESTUDYOFTHREEBRIDGESANDGIVESRECOMMENDATIONSABOUTPARTICULARLYIMPORTANTPARAMETERSFORTHEENVIRONMENTALPERFORMANCEOFTHESETHREETYPESOFBRIDGESEARLIERLCASTUDIESONBRIDGESHAVEBEENREVIEWED,ANDTHEMAINFINDINGSFROMTHESESTUDIESAREPRESENTEDINTHISPAPERFEWLCASTUDIESONBRIDGESHAVEBEENCARRIEDOUT,ANDTHECASESTUDIESPRESENTEDHERECANBEREGARDEDASASYSTEMATICANDDETAILEDEXTENSIONTOTHEEARLIERSTUDIESINTHEIDENTIFICATIONOFTHEMOSTIMPORTANTPARAMETERSREGARDINGTHEENVIRONMENTALPERFORMANCEOFBRIDGESWEBELIEVETHATTHISISINDEEDIMPORTANTINTHECURRENTPROCESSOFIMPROVEDENVIRONMENTALDESIGNAMONGBRIDGEENGINEERS,PARTICULARLYINTHEEARLYPHASESOFTHEDESIGNPROCESS,WHERELITTLEINFORMATIONMIGHTBEAVAILABLEANDYETTHEREMAYBEGOODOPPORTUNITIESTOINFLUENCEAGOODDESIGNSTRATEGYTHETHREEBRIDGESANALYZEDINTHISPAPERASTEELBOXGIRDERBRIDGE,ACONCRETEBOXGIRDERBRIDGE,ANDAWOODENARCHBRIDGEAREALREADYBUILTANDINUSEINWESTERNNORWAYTHISMEANSTHATONECOULDALSOGETAHOLDOFDETAILEDFACTSABOUTTHECONSUMPTIONOFVARIOUSTYPESOFRESOURCESINTHEPRODUCTIONANDCONSTRUCTIONPHASESOFTHEBRIDGESMOSTOFTHEENERGYANDMATERIALCONSUMPTIONTHROUGHOUTTHELIFECYCLESOFTHEBRIDGESISACCOUNTEDFOR,ANDSEVERALENVIRONMENTALIMPACTCATEGORIESAREINCLUDEDTHEBRIDGESHAVEBEENANALYZEDONTHEBASISOFTHECONTRIBUTIONSOFMATERIALS,BRIDGECOMPONENTS,ANDLIFECYCLEPHASESTOENVIRONMENTALIMPACTSLITERATURECOMPARISONOFDIFFERENTBRIDGEALTERNATIVESAPRESTRESSEDCONCRETEBOXGIRDERBRIDGEANDASTEELCONCRETECOMPOSITEIGIRDERBRIDGEWERECOMPAREDINGERVáSIOANDDASILVA2008THEEMISSIONSCONSIDEREDARECARBONDIOXIDECO2,SULFURDIOXIDESO2,NITROGENOXIDESNOX,VOLATILEORGANICCOMPOUNDSVOC,CARBONMONOXIDECO,METHANECH4,AND1PHDSTUDENT,DEPTOFHYDRAULICANDENVIRONMENTALENGINEERING,INDUSTRIALECOLOGYPROGRAMME,THENORWEGIANUNIVOFSCIENCEANDTECHNOLOGY,N7491TRONDHEIM,NORWAYCORRESPONDINGAUTHOREMAILJOHANNEHAMMERVOLDNTNUNO2PHDSTUDENT,DEPTOFHYDRAULICANDENVIRONMENTALENGINEERING,INDUSTRIALECOLOGYPROGRAMME,THENORWEGIANUNIVOFSCIENCEANDTECHNOLOGY,N7491TRONDHEIM,NORWAY3PROFESSOR,DEPTOFHYDRAULICANDENVIRONMENTALENGINEERING,INDUSTRIALECOLOGYPROGRAMME,THENORWEGIANUNIVOFSCIENCEANDTECHNOLOGY,N7491TRONDHEIM,NORWAYNOTETHISMANUSCRIPTWASSUBMITTEDONFEBRUARY2,2011APPROVEDONOCTOBER20,2011PUBLISHEDONLINEONOCTOBER24,2011DISCUSSIONPERIODOPENUNTILJULY1,2013SEPARATEDISCUSSIONSMUSTBESUBMITTEDFORINDIVIDUALPAPERSTHISPAPERISPARTOFTHEJOURNALOFBRIDGEENGINEERING,VOL18,NO2,FEBRUARY1,2013?ASCE,ISSN10840702/2013/2153E161/2500JOURNALOFBRIDGEENGINEERING?ASCE/FEBRUARY2013/153JBRIDGEENG201318153161DOWNLOADEDFROMASCELIBRARYORGBYCHANGSHAUNIVERSI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AINLYCONS
下載積分: 10 賞幣
上傳時(shí)間:2024-03-13
頁(yè)數(shù): 9
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簡(jiǎn)介:IEEETRANSACTIONSONCONTROLSYSTEMSTECHNOLOGY,VOL11,NO6,NOVEMBER2003799GAINSCHEDULEDWHEELSLIPCONTROLINAUTOMOTIVEBRAKESYSTEMSTORAJOHANSEN,SENIORMEMBER,IEEE,IDARPETERSEN,JENSKALKKUHL,ANDJENSLüDEMANNABSTRACTAWHEELSLIPCONTROLLERISDEVELOPEDANDEXPERIMENTALLYTESTEDINACAREQUIPPEDWITHELECTROMECHANICALBRAKEACTUATORSANDABRAKEBYWIRESYSTEMAGAINSCHEDULINGAPPROACHISTAKEN,WHERETHEVEHICLESPEEDISVIEWEDASASLOWLYTIMEVARYINGPARAMETERANDTHEMODELISLINEARIZEDABOUTTHENOMINALWHEELSLIPGAINMATRICESFORTHEDIFFERENTOPERATINGCONDITIONSAREDESIGNEDUSINGANLQRAPPROACHTHESTABILITYANDROBUSTNESSOFTHECONTROLLERARESTUDIEDVIALYAPUNOVTHEORY,FREQUENCYANALYSIS,ANDEXPERIMENTSUSINGATESTVEHICLEINDEXTERMSANTILOCKBRAKING,AUTOMOTIVECONTROL,GAINSCHEDULING,NONLINEARCONTROL,OPTIMALCONTROLIINTRODUCTIONANANTILOCKBRAKESYSTEMABSCONTROLSTHESLIPOFEACHWHEELOFAVEHICLETOPREVENTITFROMLOCKINGSUCHTHATAHIGHFRICTIONISACHIEVEDANDSTEERABILITYISMAINTAINEDABSBRAKESARECHARACTERIZEDBYROBUSTADAPTIVEBEHAVIORWITHRESPECTTOHIGHLYUNCERTAINTIRECHARACTERISTICSANDFASTCHANGINGROADSURFACEPROPERTIESANDTHEYHAVEBEENCOMMERCIALLYAVAILABLEINCARSFORMORETHAN20YEARS1,2THEINTRODUCTIONOFADVANCEDFUNCTIONALITYSUCHASELECTRONICSTABILITYPROGRAMESP,DRIVEBYWIRE,ANDMORESOPHISTICATEDACTUATORSANDSENSORSOFFERBOTHNEWOPPORTUNITIESANDREQUIREMENTSFORMOREACCURATEANDFLEXIBLECONTROLINAUTOMOTIVEBRAKESYSTEMSTHEBRAKESYSTEMISNOLONGERASTANDALONESYSTEMWHOSEONLYPURPOSEISTOGENERATESTABLEANDEFFICIENTBRAKING,BUTISSEENASASUBSYSTEMWHEREEACHWHEELCANRECEIVEINDIVIDUALBRAKECOMMANDSFROMHIGHERLEVELCONTROLSYSTEMSFOREXAMPLE,THEESPSYSTEMMAYACHIEVELATERALSTABILIZATIONBYCOMMANDINGBRAKETORQUEORTARGETSLIPTOTHEABSTHETARGETSLIPMAYALSOBEBASEDONAUTOMATICMONITORINGOFTHEROADCONDITIONS,EG,3THISMAKESWHEELSLIPCONTROLANINTERESTINGALTERNATIVETOCONVENTIONALABSS,WHERETHECONTROLLOGICUSUALLYDOESNOTINCLUDEANEXPLICITWHEELSLIPCONTROLLER2,4,5THECONTRIBUTIONOFTHISPAPERISASTUDYOFAMODELBASEDDESIGNOFWHEELSLIPCONTROL,EXTENDINGTHEPRELIMINARYRESULTSDESCRIBEDIN6,7WECONSIDERELECTROMECHANICALACTUATORS,8,MANUSCRIPTRECEIVEDJUNE12,2002MANUSCRIPTRECEIVEDINFINALFORMMARCH3,2003RECOMMENDEDBYASSOCIATEEDITORASTEFANOPOULOUTHISWORKWASSUPPORTEDBYTHEEUROPEANCOMMISSIONUNDERTHEESPRITLTRPROJECT28104HCTAJOHANSENISWITHSINTEFELECTRONICSANDCYBERNETICS,N7465TRONDHEIM,NORWAY,ANDALSOWITHTHEDEPARTMENTOFENGINEERINGCYBERNETICS,NORWEGIANUNIVERSITYOFSCIENCEANDTECHNOLOGY,N7491TRONDHEIM,NORWAYIPETERSENISWITHSINTEFELECTRONICSANDCYBERNETICS,N7465TRONDHEIM,NORWAYJKALKKUHLANDJLüDEMANNAREWITHDAIMLERCHRYSLER,RESEARCHANDTECHNOLOGY,D10559BERLIN,GERMANYDIGITALOBJECTIDENTIFIER101109/TCST20038156079,RATHERTHANCONVENTIONALHYDRAULICACTUATORS,WHICHALLOWACCURATECONTINUOUSADJUSTMENTOFTHECLAMPINGFORCEDESPITETHEFACTTHATTHEWHEELSLIPDYNAMICSAREHIGHLYNONLINEAR,OURCONTROLDESIGNRELIESONLOCALLINEARIZATIONANDGAINSCHEDULINGINORDERTOANALYZETHEEFFECTSOFTHISSIMPLIFICATION,WEDEVELOPASOMEWHATIDEALIZEDLYAPUNOVBASEDNONLINEARSTABILITYANDROBUSTNESSANALYSIS,TAKINGINTOACCOUNTUNCERTAINTIREFRICTIONNONLINEARITIESINORDERTOALSOINVESTIGATETHEEFFECTSOFSAMPLING,COMMUNICATIONSDELAYS,ACTUATORDYNAMICS,ANDTHEFUNDAMENTALLIMITATIONSINPERFORMANCE,THISANALYSISISCOMPLEMENTEDBYACLASSICALFREQUENCYANALYSISEXPERIMENTSUSINGATESTVEHICLEAREINCLUDEDOTHERCONTRIBUTIONSTOMODELBASEDWHEELSLIPCONTROLFORABSCANBEFOUNDINTHELITERATUREANADAPTIVECONTROLLYAPUNOVAPPROACHISSUGGESTEDIN10,ANDSIMILARIDEASAREPURSUEDIN11,12THEUSEOFSONTAG’SFORMULAISAPPLIEDINTHEADAPTIVECONTROLLYAPUNOVAPPROACHIN13,WHICHINCLUDESGAINSCHEDULINGONVEHICLESPEEDANDEXPERIMENTALTESTINGFEEDBACKLINEARIZATIONINCOMBINATIONWITHGAINSCHEDULINGISSUGGESTEDIN14INCONTRAST,OURCONTROLLERCONTAINSNOEXPLICITFRICTIONMODELANDRELIESONINTEGRALACTIONRATHERTHANADAPTATIONINORDERTOELIMINATESTEADYSTATEUNCERTAINTYTHISSIMPLIFIESTHEDESIGNANDMAYPOTENTIALLYIMPROVEROBUSTNESSASTHEFRICTIONISDIFFICULTTOMODELACCURATELYFORAWIDERANGEOFTIRESANDSURFACESPIDTYPEAPPROACHESTOWHEELSLIPCONTROLARECONSIDEREDIN15–19OURWORKISBASEDONAGAINSCHEDULEDLQCONTROLDESIGNAPPROACHWITHASSOCIATEDANALYSIS,AND,EXCEPT13AND19,ISTHEONLYONETHATCONTAINSDETAILEDEXPERIMENTALEVALUATIONUSINGATESTVEHICLEIN20,ANOPTIMUMSEEKINGAPPROACHISTAKENTODETERMINETHEMAXIMUMFRICTION,USINGSLIDINGMODESSLIDINGMODECONTROLISALSOCONSIDEREDIN21AND22IIMODELINGINTHISSECTION,WEREVIEWAMATHEMATICALMODELOFTHEWHEELSLIPDYNAMICS,SEEALSO1,10,AND20THEPROBLEMOFWHEELSLIPCONTROLISBESTEXPLAINEDBYLOOKINGATAQUARTERCARMODELASSHOWNINFIG1THEMODELCONSISTSOFASINGLEWHEELATTACHEDTOAMASSASTHEWHEELROTATES,DRIVENBYTHEINERTIAOFTHEMASSINTHEDIRECTIONOFTHEVELOCITY,ATIREREACTIONFORCEISGENERATEDBYTHEFRICTIONBETWEENTHETIRESURFACEANDTHEROADSURFACETHETIREREACTIONFORCEWILLGENERATEATORQUETHATRESULTSINAROLLINGMOTIONOFTHEWHEELCAUSINGANANGULARVELOCITYABRAKETORQUEAPPLIEDTOTHEWHEELWILLACTAGAINSTTHESPINNINGOFTHEWHEELCAUSINGANEGATIVEANGULARACCELERATIONTHEEQUATIONSOFMOTIONOFTHEQUARTERCARARE110636536/031700?2003IEEEJOHANSENETALGAINSCHEDULEDWHEELSLIPCONTROL801DURINGBRAKINGACHIEVINGTHISBYMANUALCONTROLISDIFFICULTBECAUSETHESLIPDYNAMICSAREFASTANDOPENLOOPUNSTABLEWHENOPERATINGATWHEELSLIPVALUESTOTHERIGHTOFANYPEAKOFTHEFRICTIONCURVEWEOBSERVETHATAREASONABLETRADEOFFBETWEENHIGHLONGITUDINALFRICTIONANDLATERALFRICTIONISACHIEVEDUNDERALLROADCONDITIONSFORLONGITUDINALSLIPCLOSETOITSPEAKVALUEONTHELONGITUDINALSLIPCURVEHEREAFTER,FORSIMPLIFICATIONPURPOSESUNLESSOTHERWISESTATED,THESIDESLIPANGLEWILLBECONSIDEREDTOBEZEROWITHUSING1–4,FORANDWEGETTHEWHEELSLIPDYNAMICS56NOTICETHATWHEN,THEOPENLOOPSLIPDYNAMICS5BECOMESINFINITELYFASTWITHINFINITEHIGHFREQUENCYGAINHENCE,THESLIPCONTROLLERISSWITCHEDOFFFORSMALLDURINGBRAKINGITISCLEARTHATAND,SEEALSO6THEDYNAMICSOFTHEWHEELANDCARBODYAREGIVENBY5AND6,RESPECTIVELYDUETOLARGEDIFFERENCESININERTIA,THEWHEELDYNAMICSANDCARBODYDYNAMICSWILLEVOLVEONSIGNIFICANTLYDIFFERENTTIMESCALESTHESPEEDWILLCHANGEMUCHMORESLOWLYTHANTHEWHEELSLIP,ANDISTHEREFOREANATURALCANDIDATEFORGAINSCHEDULINGTHUS,FORTHECONTROLDESIGN,WECONSIDERONLY5ANDREGARDASASLOWTIMEVARYINGPARAMETERAGAINSCHEDULEDCONTROLDESIGNREQUIRESASETOFNOMINALLINEARIZEDMODELSFORDESIGNLETBEANEQUILIBRIUMPOINTFOR5DEFINEDBYSOMENOMINALVALUES,ANDTHESPEEDDEPENDENTNOMINALLINEARIZEDSLIPDYNAMICSAREGIVENBY7WHEREHOTDENOTESHIGHERORDERTERMS,ANDANDARELINEARIZATIONCONSTANTSGIVENBY89NOTICETHATFORNOMINALWHEELSLIPVALUESTOTHERIGHTOFANYPEAKOFTHEFRICTIONCURVEWEGETSUCHTHATTHEOPENLOOPDYNAMICSAREOPENLOOPUNSTABLEFORNOMINALSLIPVALUESSLIGHTLYTOTHELEFTOFANYPEAK,NOTICETHATTHELASTTERMIN8ISGENERALLYSMALLANDTHEDYNAMICSAREOPENLOOPSTABLEASSUMINGARBITRARYVALUESOFAND,THEWHEELSLIPDYNAMICS5CANBEWRITTENINTHEFORM10WHEREANDISTHETARGETSLIPSETPOINTFURTHERMORE,WEHAVEDEFINED11AND12ITCANBESEENTHAT10HASANEQUILIBRIUMPOINTGIVENBY,SINCETHELINEARIZEDSLIPMODEL7WITHAPERTURBATIONTERMISWRITTENASFOLLOWS13WHEREEQUATION13WILLBEUSEDLATERONFORCONTROLDESIGNANDANALYSISIIICONTROLDESIGNANDANALYSISACONTROLPROBLEMTHEACTUALCONTROLINPUTISTHECLAMPINGFORCETHATISRELATEDTOTHEBRAKETORQUEAS,WHERETHECONSTANTDEPENDSONTHEFRICTIONBETWEENTHEBRAKEPADSANDTHEBRAKEDISCTHEREARELIMITATIONSONTHECLAMPINGFORCETHATCANBEAPPLIEDTOTHEBRAKEPADSBYTHEACTUATORDURINGBRAKINGTHESMALLMINIMUMFORCEISTOENSURETHATTHEBRAKEPADSAREPOSITIONEDCLOSETOTHEBRAKEDISKWITHNOAIRGAPDURINGBRAKINGTHEMAXIMUMFORCEISWHATTHEACTUATORISCAPABLEOFTHEREISALSOARATELIMITATHOWFASTTHETORQUECANBECHANGEDBYTHEACTUATORTHECONTROLPROBLEMISTOREGULATETHEVALUEOFTHELONGITUDINALSLIPTOAGIVENSETPOINTTHATISEITHERCONSTANTORCOMMANDEDFROMAHIGHERLEVELCONTROLSYSTEMTHECONTROLLERMUSTBEROBUSTWITHRESPECTTOUNCERTAINTIESINTHETIRECHARACTERISTIC,BRAKEPADS/DISCS,VARIATIONSINTHEROADSURFACECONDITIONS,LOADONTHEVEHICLEETCINTEGRALACTIONORADAPTATIONMUSTBEINCORPORATEDTOREMOVESTEADYSTATEERRORDUETOMODELINACCURACIES,INPARTICULARTHEUNKNOWNMAXIMUMFRICTIONCOEFFICIENTBWHEELSLIPCONTROLWITHINTEGRALACTIONLETTHESYSTEMDYNAMICS13BEAUGMENTEDWITHASLIPERRORINTEGRATORSUCHTHAT14WHERE15THESTEADYSTATEBRAKETORQUEDEPENDSONROADANDTIREPROPERTIESSUCHASANDMUSTTHEREFOREBEASSUMEDUNKNOWN
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簡(jiǎn)介:CHINACHEMICALREPORTERSEPTEMBER21ST,201018WWWCCRCOMCNFINEANDSPECIALTYCHINASTEXTILEAUXILIARYINDUSTRYNEEDSTECHNOLOGICALINNOVATIONNEARLY100CATEGORIESANDABOUT15000VARIETIESOFTEXTILEAUXILIARIESAREPRODUCEDINTHEWORLDTODAYREPORTEDLY,THEIRGLOBALANNUALSALESVOLUMEIS28MILLIONTONS,WITHASALESVALUEEXCEEDINGUS16BILLIONINTERNATIONALLY,100KGOFFIBERCONSUMES7KGTEXTILEAUXILIARIESONAVERAGE,BUTINCHINA,100KGFIBERCONSUMESONLY4KGOFTEXTILEAUXILIARIESINRECENTYEARS,ASTHEEUROPEANUNIONEU,THEUNITEDSTATESANDJAPANCONSTANTLYTRANSFERTHEIRTEXTILEPLANTSTOSOUTHEASTASIA,THEDEMANDFORTEXTILEAUXILIARIESINSOUTHEASTASIAHASINCREASEDRAPIDLY,EXCEEDINGNORTHAMERICA,WESTERNEUROPEANDJAPANANDRANKINGFIRSTINTHEWORLDHOWEVER,THELEADINGPRODUCERSOFTEXTILEAUXILIARIESARESTILLINEUROPEANDJAPANCHINASOUTPUTOFPRINTEDANDDYEDCLOTHHASGROWNATANAVERAGEANNUALRATEOFMORETHAN10INRECENTYEARS,MAKINGCHINATHEWORLDSLARGESTPRODUCERTODAYWITHTHEDEVELOPMENTOFCHINASTEXTILEINDUSTRY,THEDEMANDFORTEXTILEAUXILIARIESGROWSRAPIDLYINTHEFUTURE,CHINASTEXTILEAUXILIARYINDUSTRYWILLHAVEAHUGEDEVELOPMENTPOTENTIALANDABROADMARKETPROSPECTTEXTILEAUXILIARIESAREANIMPORTANTCLASSOFTEXTILECHEMICALSWITHTHECANCELLATIONOFINTERNATIONALTEXTILEANDGARMENTEXPORTQUOTAS,THEINTERNATIONALMARKETISSETTINGEVENGREATERTECHNICALBARRIERSANDTRADEBARRIERS,ESPECIALLYGREENBARRIERS,ONTEXTILESANDGARMENTSASWELLASONTEXTILEDYESTHESEGREENBARRIERSLEADTOUNPRECEDENTEDBANSANDRESTRICTIONSONUSESOFTEXTILEAUXILIARIESAMONGTHEM,ONEOFTHETWOSTRICTESTBARRIERSISTHENEWSTANDARDTHATTHEEUMADEIN2002,WHICHBANSANDRESTRICTSTHEUSEOF17CATEGORIESOFTEXTILEAUXILIARIES,ANDTHEOTHERISTHEEUSREACHREGULATIONTHESEBARRIERSWILLSIGNIFICANTLYINCREASETHEEXPORTCOSTSOFCHINAMADETEXTILESANDTEXTILECHEMICALS,GREATLYENHANCETHEINNOVATIONCOSTSOFNEWTEXTILESANDTEXTILECHEMICALS,ANDDRAMATICALLYRESTRICTTHEDEVELOPMENTOFCHINASTEXTILESANDTEXTILECHEMICALSCURRENTLY,THEDEVELOPMENTOFTHEWORLDSTEXTILEAUXILIARYTECHNOLOGYSHOWSTHEFOLLOWINGFOURMAJORTRENDSFIRST,COMPLEXTECHNOLOGYISUSEDTOREALIZETHEMULTIFUNCTIONALITYANDHIGHFUNCTIONALITYOFTEXTILEAUXILIARIESSECOND,SUITABLEAUXILIARIESAREDEVELOPEDFORNEWFIBERSTHIRD,HIGHTECHPRODUCTSAREUSEDTOCOMPLEMENTANDEVENREPLACETRADITIONALTEXTILEAUXILIARIESACCORDINGTOMARKETREQUIREMENTSANDFOURTH,ENVIRONMENTFRIENDLYADDITIVESAREINCREASINGLYPREFERREDINRECENTYEARS,CHINASOUTPUTOFPRINTEDANDDYEDCLOTHISBOOMINGCHINASTEXTILEAUXILIARYINDUSTRYHASTHEFOLLOWINGCHARACTERISTICSFIRST,ITREQUIRESLOWFIXEDINVESTMENTBUTPRODUCESAHIGHADDEDVALUE,LEADINGTOAHIGHPROFITMARGIN,SOITATTRACTSMANYINVESTORS,ANDTHECOMPETITIONAMONGTEXTILEAUXILIARYPRODUCERSISVERYINTENSEANDCHAOTICSECOND,ITMAKESEXTENSIVEUSEOFCOMPLEXTECHNOLOGY,ANDTHERESEARCHOFTHEFORMULATIONISVERYCRITICALTHIRD,ITFEATURESSMALLBATCHANDINTERMITTENTPRODUCTION,ANDPRODUCTIONEQUIPMENTISVERSATILEFOURTH,ITHASHIGHREQUIREMENTSONAPPLICATIONRESEARCH,TECHNICALSERVICESANDLOGISTICSHOWEVER,DUETOHISTORICALCONDITIONS,THEDEVELOPMENTOFCHINASTEXTILEAUXILIARYINDUSTRYSTILLHASSOMELIMITATIONSANDMANYPROBLEMSASFOLLOWS1CHINASTEXTILEAUXILIARYPRODUCERSSELDOMPUBLISHTHECOMPOSITIONSOFTHEIRPRODUCTS,ANDTHEIRPRODUCTSLACKINHERENTCHARACTERISTICSDATAINHERENTCHARACTERISTICSDATAHASNOTBEENCREATEDFORAROUND3/4OFCHINASTEXTILEAUXILIARIESDUETOTHISLACKOFINFORMATION,THEIMPURITIESINTHETEXTILEAUXILIARIESAREUNKNOWN,ANDTHETOXICOLOGICALINDEXESANDECOLOGICALTOXICOLOGICALINDEXESFORTHEMCANNOTBEESTABLISHEDTHISCANINCREASETHEREGISTRATIONCOSTOFCHINASTEXTILEAUXILIARIESINACCORDANCEWITHTHEREQUIREMENTSOFTHEEUSREACHREGULATIONSANDAFFECTTHEPRODUCTMIXOFCHINASTEXTILEAUXILIARYPRODUCERS2CHINASCURRENTTEXTILEAUXILIARYSTANDARDSAREBACKWARDATPRESENT,THEQUALITYINDEXESOFMOSTDOMESTICTEXTILEAUXILIARIESHAVEREGULARANDGENERALINDEXESONLYBUTLACKCHARACTERISTICSINDEXES,ANDTHEREARENODETECTIONTECHNOLOGIESANDMETHODSFORTHEIRPHYSICALINDEXESCHINASTEXTILEAUXILIARYINDUSTRYISVERYBACKWARDINAREASRANGINGFROMDETECTIONMETHODSTANDARDSTOPRODUCTINDEXSTANDARDS3CHINALACKSSERIALIZEDANDHIGHPERFORMANCETEXTILEAUXILIARIES,ESPECIALLYSPECIALTEXTILEAUXILIARIESBLENDEDSPINNINGPRODUCTSOFNATURALFIBERSANDSYNTHETICFIBERSWITHCOMPLEMENTARYPROPERTIESAREBECOMINGMOREANDMOREPOPULARANDBLENDEDPRODUCTSOFSEVERALTYPESOFFIBERSNEEDHIGHQUALITYANDLOWFLOWPRETREATMENTANDDYEING,PRINTINGANDFINISHINGPROCESSESANDASSOCIATEDAUXILIARIESCHINACANHARDLYPRODUCESERIALIZEDANDHIGHQUALITYADDITIVESFORTHISAREANEWDYEINGANDFINISHINGTECHNOLOGIESAPPLICABLETOMANYNEWFABRICSNEEDNEWSPECIALADDITIVESBUTTILLNOW,THISISSUEHASNOTYETBEENADDRESSEDINCHINAFOREXAMPLE,THENEWLYDEVELOPEDULTRAFINEFIBERS,HETERODENIERFIBERS,HETEROSHRINKAGEFIBERS,HETEROCROSSSECTIONFIBERS,HETEROMATERIALFIBERS,ELASTICFIBERS,NEWCELLULOSEFIBERSSUCHASTENCEL,MODAL,LYOCEU,ETC,COMPOSITEFIBERSANDFUNCTIONALFIBERSNEEDSPECIALAUXILIARIESFOREXAMPLETENCELFIBERANDSOYBEANPROTEINFIBERNEEDBATHLUBRICANTSANDENZYMESINTHEIRPRODUCTIONANDPROCESSINGTHENUMBEROFTEXTILEAUXILIARYVARIETIESTHATCHINAHASDEVELOPEDANDPRODUCEDACCOUNTSFORONLY8OFTHEWORLDSTOTALNUMBERTHEPROPORTIONOFTHESPECIALANDHIGHGRADETEXTILEAUXILIARIESNOWINUSETHATCHINACANPRODUCEISEVENSMALLER,SOSUCHCHEMICALSHAVETOBEIMPORTEDFOREXAMPLE,ALMOSTALLTHEORGANICFLUORINEANTIOILAGENTSUSEDINCHINAAREIMPORTED4CHINASTEXTILEINDUSTRYISRELATIVELYCHINACHEMICALREPORTERSEPTEMBER21ST,201020WWWCCRCOMCNFINEANDSPECIALTYPRODUCERS,THEPROPORTIONOFTHEIRPRODUCTSTHATARESOLDDOMESTICALLYHASINCREASEDFROM67IN2000TO77NOWFROMTHEVIEWOFCLOTHINGCONSUMPTION,CHINASPERCAPITACONSUMPTIONOFTEXTILEPRODUCTSHASGROWNFROM75KGIN2000TOABOUT16KGIN2007,BUTTHISLEVELISMUCHLOWERTHANTHEPERCAPITAFIBERCONSUMPTION30TO40KGOFDEVELOPEDCOUNTRIESFROMTHEVIEWOFHOMETEXTILES,WITHTHEINCREASINGNUMBEROFNEWHOMESANDTHEENHANCEMENTOFPEOPLESCONSUMPTIONLEVEL,THEAVERAGEHOUSEHOLDHASATEXTILECONSUMPTIONOF1020KGATPRESENT,ESPECIALLYINRURALCHINA,TEXTILEANDAPPARELCONSUMPTIONREMAINSVERYLOWALLTHESEINDICATETHATCHINASDOMESTICTEXTILEANDCLOTHINGMARKETSTILLHASAHUGEDEVELOPMENTSPACEANDPOTENTIALCHINASDOMESTICTEXTILEMARKETSTILLHASMANYNEWGROWTHPOINTSFOREXAMPLE,INRIESINASIAISGROWINGRAPIDLYANDISEXPECTEDTOREACH136MILLIONTONSIN2011ATPRESENT,CHINASTEXTILEAUXILIARYOUTPUTONLYACCOUNTSFORABOUT10OFTHEGLOBALTOTALTHISISNOTCOMMENSURATEWITHTHESHARE,ABOUT60,THATCHINASDYESTUFFOUTPUTACCOUNTSFORINTHEGLOBALDYESTUFFOUTPUTTHISYEAR,ASTHEWORLDECONOMYRECOVERS,CHINESECOMPANIESWILLEXPORTMORETEXTILEAUXILIARIESCHINAISTHEWORLDSLARGESTTEXTILEPRODUCERANDPROCESSORASTEXTILEAUXILIARIESDEVELOPFURTHERTOWARDMULTIPLEFUNCTIONS,HIGHPERFORMANCEANDENVIRONMENTALFRIENDLINESS,DEVELOPINGANDPRODUCINGFAST,EFFICIENT,ENVIRONMENTALLYFRIENDLYANDENERGYEFFICIENTTEXTILEAUXILIARIESANDPRINTINGANDDYEINGPROCESSESISANIMPERATIVERESPONSIBILITYOFTHETEXTILEAUXILIARYINDUSTRYDUSTRIALTEXTILEPRODUCTSAREWIDELYUSEDININFRASTRUCTURALCONSTRUCTIONANDHEALTHANDMEDICALFIELDSCURRENTLY,THETEXTILECONSUMPTIONINTHESEFIELDSONLYACCOUNTSFOR15OFCHINASTOTALTEXTILECONSUMPTIONASCHINAGRADUALLYSTRENGTHENSITSINFRASTRUCTURALCONSTRUCTION,ITISEXPECTEDTHATTHEINDUSTRIALTEXTILEMARKETWILLGROWFASTERANDHASABROADMARKETPROSPECTATPRESENT,WITHTHESTABILIZATIONOFDOMESTICEMPLOYMENT,CHINASDOMESTICDEMANDCANBEEXPECTEDTOGROWSTEADILYEXPERTSPREDICTTHATBY2012,CHINASOUTPUTOFTEXTILEAUXILIARIESWILLREACH116MILLIONTONS,WITHASALESVALUEOFRMB2329BILLIONASTHEUNITEDSTATESANDWESTERNEUROPEANCOUNTRIESGRADUALLYSHIFTTHEIRTEXTILEPRODUCTIONTOSOUTHEASTASIA,ASIAHASALSOBEGUNTOBECOMETHEGLOBALCENTEROFTEXTILEAUXILIARIESTHEDEMANDFORTEXTILEAUXILIACHINASPLASTICADDITIVESINDUSTRYNEEDSINDEPENDENTINNOVATIONANDENVIRONMENTALPROTECTIONASANIMPORTANTPARTOFTHESPECIALTYCHEMICALSFIELD,CHINASPLASTICSADDITIVESINDUSTRYHASDEVELOPEDGREATLYINRECENTYEARS,BUTCERTAINREFORMSREMAINURGENTHEATSTABILIZERSATPRESENT,HEATSTABILIZERSHAVEDEVELOPEDINTOTHESECONDLARGESTCATEGORYOFPLASTICADDITIVES,JUSTAFTERPLASTICIZERSIN2009,CHINASTOTALCAPACITYTOMAKEHEATSTABILIZERSWASABOUT480000T/A,CONTRIBUTEDBYNEARLY1000HEATSTABILIZERMANUFACTURERSTHEYCANBASICALLYPRODUCEALLVARIETIESOFHEATSTABILIZERSNEEDEDBYTHEDOWNSTREAMINDUSTRIESACCORDINGTOTHEESTIMATESOFCHINESEPLASTICSINDUSTRY,CHINASDEMANDFORHEATSTABILIZERSWILLREACHMORETHAN300000TONSTHISYEARCHINASHEATSTABILIZERSECTORSTILLHASMANYPLACESTOIMPROVE,FOREXAMPLE,MOREVARIETIESTHEWORLDMAKESMORETHAN1000TYPESOFORGANICTINBASEDPVCHEATSTABILIZERS,BUTCHINACANCOMMERCIALLYPRODUCEONLY40TYPESMEANWHILE,HIGHLYTOXIC,HIGHPOLLUTIONANDLOWENDLEADSALTSTABILIZERSSTILLABSOLUTELYDOMINATECHINASHEATSTABILIZERMARKET,ANDTHEMARKETSHAREOFORGANICTINPRODUCTSINTHEDOMESTICMARKETISFARLOWERTHANINADVANCEDCOUNTRIESTHEREAREMANYSMALLHEATSTABILIZERPRODUCERSINCHINATHEYOFTENSERIOUSLYPOLLUTETHEENVIRONMENTTHEIRPRODUCTSCONTAINALOTOFIMPURITIESANDWATERBUTAREVERYCHEAPSOTHEYHAVEASERIOUSIMPACTONTHEPRODUCTIONANDMARKETINGOFHIGHQUALITYHEATSTABILIZERSASARESULTOFINSUFFICIENTINVESTMENTINRD,THEPRODUCTIONANDAPPLICATIONOFNEWTYPESOFHEATSTABILIZERSCANNOTSATISFYTHEDEVELOPMENTNEEDSOFCHINASPVCINDUSTRYTHEMAJORITYOFCHINASUSERSOFHIGHGRADEHEATSTABILIZERSSTILLMAINLYRELYONTHEPRODUCTIONANDUSEOFPLASTICSTRADITIONALTOXICHEATSTABILIZERSCONTAINCD,PB,SBORBAANDWILLBEELIMINATEDFROMTHEMARKETINTHEFUTURE,GIVINGNEWDEVELOPMENTOPPORTUNITIESTOENVIRONMENTFRIENDLYORGANICTINBASED,ORGANICZINCBASEDANDORGANICCHEMICALSBASEDHEATSTABILIZERSITCANBEEXPECTEDTHATORGANICHEATSTABILIZERSTHATARECOMPLETELYFREEOFHEAVYMETALSWILLREPRESENTTHEDEVELOPMENTDIRECTIONOFPVCHEATSTABILIZERSBUTTHECOMPREHENSIVEPERFORMANCEOFEXISTINGORGANICCHEMICALSBASEDHEATSTABILIZERPRODUCTSCONTAININGNOMETALISHARDLYCOMPARABLETOTHATOFORGANICTINBASEDANDORGANICZINCBASEDHEATSTABILIZERSTHUS,ATIMPORTSINRECENTYEARS,MANYCOUNTRIESHAVEMADEANDIMPLEMENTEDENVIRONMENTALREGULATIONSTOCONTROLTHENEGATIVEIMPACTSONHUMANSANDTHEENVIRONMENTBROUGHTBYCHINASPRODUCTIONANDEXPORTOFMAINANTIOXIDANTSIN2009THOUSANDTONSVARIETYPRODUCTIONEXPORTHINDEREDPHENOLANTIOXIDANTS356PHOSPHITEANTIOXIDANTS305SULFURCONTAININGANTIOXIDANTS415TOTAL69125SOURCECNCIC?????
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