【正文】 rban 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(jì)（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 in the air obstacles on his wayto return immediately the ultrasonic reflected wave received by the receiver immediatelystop the in the air as the propagation velocity of 340m / s according tothe timer records the time t we can calculate the distance between the launch distancebarrier s that is: s 340t / Ranging System for the Second Circuit Design ‐8‐ 畢業(yè)設(shè)計(jì)（論文）英文翻譯 System is characterized by singlechip microputer to control the use of ultrasonictransmitter and ultrasonic receiver since the launch from time to time singlechip selectionof 8751 economictouse and the chip has 4K of ROM to facilitate diagram shown in Figure 1 circuit principle diagram ‐9‐ 畢業(yè)設(shè)計(jì)（論文） 40 kHz ultrasonic pulse generated with the launch Ranging system using the ultrasonic sensor of piezoelectric ceramic sensors UCM40its operating voltage of the pulse signal is 40kHz which by the singlechip implementationof the following procedures to : mov 14h 12h ultrasonic firing continued 200mshere: cpl output 40kHz square wave nop nop nop djnz 14h here ret Ranging in front of singlechip termination circuit input port single chipimplementation of the above procedure the port in a 40kHz pulse output signal afteramplification transistor T the drive to launch the first ultrasonic UCM40T issued 40kHzultrasonic pulse and the continued launch of the right and the left side ofthe circuit respectively then input port and the working principle and circuit infront of the same Reception and processing of ultrasonic Used to receive the first launch of the first pair UCM40R the ultrasonic pulsemodulation signal into an alternating voltage the opamp amplification IC1A and afterpolarization IC1B to is locked loop with audio decoder chip LM567 internalvoltagecontrolled oscillator center frequency of f0 1/ capacitor C4 determinetheir target in the launch of the carrier frequency on theLM567 input signal is greater than 25mV the output from the high jump 8 feet into alowlevel as interrupt request signals to the singlechip in front of singlechip termination circuit output port INT0 interrupt thehighest priority right or left location of the output circuit with output gate IC3A accessINT1 port singlechip while singlechip and received input IC3A interrupted ‐10‐ 畢業(yè)設(shè)計(jì)（論文）英文翻譯by the process to identify the source of inquiry to deal with interrupt priority level for thefirst left right of the source code is as follows:receive1: push psw push acc clr ex1 related external interrupt 1 jnb right pin to 0 ranging from right to interrupt serviceroutine circuit jnb left pin to 0 to the left ranging circuit interruptservice routinereturn: SETB EX1 open external interrupt 1 pop acc pop psw retiright:...right location entrance circuit interrupt service routine Ajmp Returnleft:...left Ranging entrance circuit interrupt service routine Ajmp The calculation of ultrasonic propagation time When you start firing at the same time start the singlechip circuitry within the timerT0 the use of timer counting function records the time and the launch of ultrasonicreflected wave received you receive the ultrasonic reflected wave the receivercircuit outputs a negative jump in the end of INT0 or INT1 interrupt request generates asignal singlechip microputer in response to external interrupt request theimplementation of the external interrupt service subroutine read the time differencecalculating the of its source code is as follows:RECEIVE0: PUSH PSW PUSH ACC CLR EX0 related external interrupt 0.第三篇：食品安全外文文獻(xiàn)翻譯(適用于畢業(yè)論文外文翻譯+中英文對(duì)照)w 論食品供應(yīng)鏈管理和食品質(zhì)量安全上世紀(jì)90年代以來,供應(yīng)鏈管理已成為學(xué)術(shù)界和實(shí)業(yè)界關(guān)注的熱門話題,特別是供應(yīng)鏈管理成功地應(yīng)用于IBM、Pamp。第二步：根據(jù)公式改變回波放大器的獲得量直到回?fù)鼙粰z測(cè)到。進(jìn)一步說，從脈沖起始點(diǎn)到剛好超過界限之間的時(shí)間段隨著脈沖的強(qiáng)度而改變。因此，深入研究超聲的測(cè)距理論和方法具有重要的實(shí)踐意義。中國(guó)鋼產(chǎn)量的 25 ％是由廢鋼鐵生產(chǎn)的。綠色設(shè)計(jì)著眼于人與自然的生態(tài)平衡關(guān)系，在設(shè)計(jì)過程的每一個(gè)決策