【正文】 基于食品供應(yīng)鏈的跟蹤能幫助企業(yè)縮短確認和清理有問題食品的時w 間，為此，國外許多企業(yè)將相關(guān)標(biāo)識信息揭示在食品包裝上，以便利消費者的識別和認定。許多企業(yè)已利用食品供應(yīng)鏈跟蹤系統(tǒng)，來最大限度地減少食品安全體系缺陷可能造成的潛在損失。因此，對農(nóng)產(chǎn)品和食品的安全質(zhì)量和品質(zhì)進行細分，是差別化營銷的必要前提。有些農(nóng)產(chǎn)品和食品的質(zhì)量可能容易判別，而另一些則不容易直接判別，甚至在消費之后也不能馬上發(fā)現(xiàn)其質(zhì)量問題。通過那些細小的或不能直接發(fā)現(xiàn)的食品質(zhì)量安全的特性，可區(qū)別不同類型的農(nóng)產(chǎn)品和食品。而分析這些差異，他們又發(fā)現(xiàn)三種農(nóng)產(chǎn)品食品供應(yīng)鏈管理的共性，即存在三種驅(qū)動力。農(nóng)產(chǎn)品和食品質(zhì)量安全的跟蹤離不開食品供應(yīng)鏈管理，因此基于質(zhì)量安全的食品供應(yīng)鏈跟蹤成了食品供應(yīng)鏈管理的重點和難點。這種食品供應(yīng)鏈更關(guān)注消費者的滿意度，通過加工中心來對市場需求作出快速反應(yīng)，并實時對農(nóng)產(chǎn)品和食品進行“量身定制”和深度加工，以實現(xiàn)不同于精益物流的靈捷物流戰(zhàn)略。隨著上游供應(yīng)商實力和優(yōu)勢的增強，加工中心的部分功能，如清洗、分類和深度加工等環(huán)節(jié)又向供應(yīng)商回流，使得加工中心的重點放在處理和不斷擴大的農(nóng)產(chǎn)品數(shù)量和種類業(yè)務(wù)上。大型超市為了適應(yīng)消費需求的顯著變化，將原先由獨立企業(yè)從事的專業(yè)化生產(chǎn)的增值環(huán)節(jié)進行“內(nèi)部化”，專門建立大型加工及配送中心，對農(nóng)產(chǎn)品進行清洗、分類、深度加工、包裝和配送等增值業(yè)務(wù)，同時通過在大型加工中心實施HACCP和GMP加工質(zhì)量和衛(wèi)生安全認證，來保證食品和農(nóng)產(chǎn)品的品質(zhì)安全。據(jù)有關(guān)統(tǒng)計表明，美國2002未加工和加工蔬菜的比例為15%和85%；水果為30%和70%。隨著上游農(nóng)產(chǎn)品供應(yīng)商數(shù)目的銳減和超市連鎖店的不斷擴張，這種食品供應(yīng)鏈的上游供應(yīng)商與下游超市連鎖店的數(shù)目呈現(xiàn)對稱增長之態(tài)勢。這些大型超市為了滿足市場對農(nóng)產(chǎn)品品質(zhì)一致性和供應(yīng)穩(wěn)定性的要求，對供應(yīng)商進行了嚴格的篩選。隨著新興銷售業(yè)態(tài)的出現(xiàn),銷售渠道日益被大型專業(yè)市場和超市所壟斷,農(nóng)產(chǎn)品和食品的傳統(tǒng)銷售形式也被超市所取代,而且這種趨勢越來越明顯,同時由于技術(shù)水平的提高,農(nóng)產(chǎn)品生產(chǎn)也趨向于由少數(shù)種植商集約經(jīng)營。因此T型食品供應(yīng)鏈由于中間環(huán)節(jié)缺位和低水平的物流運作，易出現(xiàn)上游農(nóng)戶盲目生產(chǎn)而下游農(nóng)產(chǎn)品銷售困難的現(xiàn)象。與啞鈴型食品供應(yīng)鏈相比,它的鏈條較長,食品和農(nóng)產(chǎn)品的銷售表現(xiàn)為間接性和增值服務(wù)性。這種類型的供應(yīng)鏈，上游聚w 集了較多的農(nóng)產(chǎn)品生產(chǎn)者,而在中游環(huán)節(jié)對產(chǎn)地生產(chǎn)情況比較了解,又在銷售地占有一定渠道優(yōu)勢的銷售商卻較少。這種類型的食品供應(yīng)鏈一般適用于食品和農(nóng)產(chǎn)品的生產(chǎn)地和銷售地相距較遠，消費需求差異較大的情況。在發(fā)展中國家,特別是靠近城鎮(zhèn)地區(qū)的蔬菜供應(yīng),一般都采用這種類型的供應(yīng)鏈。它的特點是供應(yīng)鏈較短,連接位于兩端的交易主體很多,而中間鏈節(jié)少且交易主體也較少，呈現(xiàn)為啞鈴型。二．食品供應(yīng)鏈生產(chǎn)物流系統(tǒng)食品供應(yīng)鏈的形成是與其物流系統(tǒng)的內(nèi)容不斷變化密切相關(guān)的,特別是在食品和農(nóng)產(chǎn)品生產(chǎn)物流系統(tǒng)不斷演變的情況下,為人們創(chuàng)建高效率的食品供應(yīng)鏈管理范式提供了基礎(chǔ)。例如，歐盟管理法規(guī)第178號規(guī)定，從2004年起在歐盟范圍內(nèi)銷售的所有食品，都要實行食品供應(yīng)鏈跟蹤與追溯；同樣在美國，食品與藥品管理局規(guī)定，在美國國內(nèi)外從事食品生產(chǎn)、加工和包裝等的部門以及相關(guān)組織，在2003年12月12日前要向食品與藥品管理局進行登記，以便進行食品安全跟蹤與追溯，未登記者就不許從事食品生產(chǎn)和銷售。因此，企業(yè)有必要在生產(chǎn)過程的各個環(huán)節(jié)對產(chǎn)品進行檢驗和檢測并及時向消費者披露這些信息。為了滿足消費者對食品和農(nóng)產(chǎn)品在種類和數(shù)量上的要求，企業(yè)不斷尋求和研發(fā)新技術(shù)，而新技術(shù)和新方法的過度使用(如殺蟲劑、激素、抗生素和轉(zhuǎn)w 基因技術(shù)等)，在滿足了消費者需求的同時，也不可避免地對人體產(chǎn)生了危害從而引起食品質(zhì)量安全問題。(2)消費者對食品和農(nóng)產(chǎn)品的質(zhì)量要求也越來越高，迫使食品生產(chǎn)企業(yè)實行食品供應(yīng)鏈管理，以保證穩(wěn)定的上游原料供應(yīng)和下游的銷售渠道暢通。一．食品供應(yīng)鏈管理的產(chǎn)生原因近年來，食品供應(yīng)鏈的產(chǎn)生和發(fā)展是人們對食品消費的要求不斷提高的必然結(jié)果。對食品供應(yīng)鏈管理的研究大致經(jīng)歷了三個階段：第一階段為商流管理階段，研究范圍包括農(nóng)產(chǎn)品和食品加工企業(yè)的產(chǎn)出到消費者消費前的商流階段，其研究內(nèi)容通常被包含在營銷范疇內(nèi)；第二階段為集成物流管理階段，農(nóng)產(chǎn)品的物流管理從市場營銷中分離出來，且向上游擴展到農(nóng)產(chǎn)品和食品生產(chǎn)企業(yè)的生產(chǎn)加工過程，強調(diào)生產(chǎn)應(yīng)以市場需求為導(dǎo)向和對整個物流環(huán)節(jié)的成本控制；第三階段為供應(yīng)鏈一體化管理階段，研究范圍進一步向上游延伸到農(nóng)產(chǎn)品的最上游企業(yè)(如種子供應(yīng)商等)，延伸的目的是為了跟蹤和追溯農(nóng)產(chǎn)品食品質(zhì)量安全問題，以便快速和有效地發(fā)現(xiàn)并解決問題。1996年,Zuurbier等學(xué)者在一般供應(yīng)鏈的基礎(chǔ)上，首次提出了食品供應(yīng)鏈概念，并認為食品供應(yīng)鏈管理是農(nóng)產(chǎn)品和食品生產(chǎn)銷售等組織,為了降低食品和農(nóng)產(chǎn)品物流成本、提高其質(zhì)量安全和物流服務(wù)水平而進行的垂直一體化運作模式。‐5‐ 畢業(yè)設(shè)計（論文）英文翻譯 Kino Frequency Acoustic WaveMeasurement in Airquot in Proceedings of IEEE 1983 Ultrasonic Symposium October 312November 1983 Atlanta GA Abreu Freire Ranging: Envelope AnalysisGives Improved Accuracyquot Sensor Review 1992 Fritsch Signal Processing Techniques for HighAccuracy Ultrasonic Range Measurementsquot IEEE Transactions: Instrumentation andMeasurement August 1991 Taron TemperatureCompensated Ultrasonic Sensor Operating in Air for Distance and ProximityMeasurementquot IEEE Transaction on Industry Electronics 1982 .‐6‐ 畢業(yè)設(shè)計（論文）英文翻譯 Ultrasonic ranging system design Publicationtitle: Sensor : ：Ultrasonic ranging technology has wide using worth in many fields，such as the industriallocale，vehicle navigation and sonar engineering．Now it has been used in level measurement，selfguided autonomous vehicles fieldwork robots automotive navigation，air and underwater targetdetection，identification，location and so on．So there is an important practicing meaning to learn theranging theory and ways improve the precision of the ultrasonic ranging system in hand，satisfy the request of the engineering personnel for the ranging precision，the bound and the usage，aportable ultrasonic ranging system based on the single chip processor was developed．Keywords：Ultrasound r，Ranging System，Single Chip With the development of science and technology the improvement of peoplesstandard of living speeding up the development and construction of the system have greatly developed their situation is constantly to historical reasons many unpredictable factors in the synthesis of her time the citydrainage particular drainage system often lags behind urban there are often good building excavation has been building facilities to upgradethe drainage system brought to the city sewage and it is clear to the citysewage and drainage culvert in the sewage treatment is very important topeoples robots designed to clear the drainage culvert and the automaticcontrol system Free sewage culvert clear guarantee robot the robot is designed to clear theculvert sewage to the System is the core ponent of the development ofultrasonic range it is very important to design a good ultrasonic principle of ultrasonic distance measurement ‐7‐ 畢業(yè)設(shè)計（論文） The principle of piezoelectric ultrasonic generator Piezoelectric ultrasonic generator is the use of piezoelectric crystal resonators to generator the internal structure as shown it has two piezoelectric chip and aresonance its two plus pulse signal the frequency equal to the intrinsicpiezoelectric oscillation frequency chip the chip will happen piezoelectric resonance andpromote the development of plate vibration resonance ultrasound is the two are not interelectrode voltage when the board received ultrasonic resonance itwill be for vibration suppression of piezoelectric chip the mechanical energy is convertedto electrical signals then it bees the ultrasonic traditional way to determine the moment of the echos arrival is based onthresholding the received signal with a fixed threshold is chosen well abovethe noise level whereas the moment of arrival of an echo is defined as the first moment theecho signal surpasses that intensity of an echo reflecting from an objectstrongly depends on the objects nature size and distance from the the timeinterval from the echos starting point to the moment when it surpasses the thresholdchanges with the intensity of the a consequence a considerable error may occurEven two echoes with different intensities arriving exactly at the same time will surpass thethreshold at different stronger one will surpass the threshold earlier than theweaker so it will be considered as belonging to a nearer principle of ultrasonic distance measurement Ultrasonic transmitter in a direction to launch ultrasound in the moment to launch thebeginning of time at the same time the spread of ultrasound i