數(shù)據(jù)采集外文翻譯

1、<p>　　大連交通大學(xué)信息工程學(xué)院</p><p>　　畢業(yè)設(shè)計(論文)外文翻譯</p><p>　　學(xué)生姓名 1111 專業(yè)班級 自動化0111班 </p><p>　　指導(dǎo)教師 1111 職 稱　 11111 </p><p>　　所在單位 電氣工程系 </p>&l

2、t;p>　　教研室主任 　 </p><p>　　完成日期 1111 年 4 月 13 日</p><p>　　Date Acquisition</p><p>　　Date acquisition systems are used to acquire process operating data

3、and store it on secondary storage devices for later analysis. Many of the data acquisition systems acquire this data at very high speeds and very little computer time is left to carry out any necessary, or desirable, dat

4、a manipulations or reduction. All the data are stored on secondary storage devices and manipulated subsequently to derive the variables of interest. It is very often necessary to design special purpose data acqui</p&g

5、t;<p>　　Powerful mini- and mainframe computers are used to combine the data acquisition with other functions such as comparisons between the actual output and the desirable output values, and to then decide on the

6、 control action which must be taken to ensure that the output variables lie within pre-set limits. The computing power required will depend upon the type of process control system implemented .Software requirements for c

7、arrying out proportional, ratio or three term control of process variables </p><p>　　Microcomputer based data loggers are used to carry out intermediate functions such as data acquisition at comparatively lo

8、w speeds, simple mathematical manipulations of raw data and some forms of data reduction. The first generation of data loggers, without any programmable computing facilities, were used simply for slow speed data acquisit

9、ion from up to one hundred channels. All the acquired data could be punched out on paper tape or printed for subsequent analysis. Such hardwired data loggers </p><p>　　The data acquisition function carried o

10、ut by data loggers varies from one logging system to another. Simple data logging systems acquire data from a few channels while complex systems can receive data from hundreds, or even thousands, of input channels distri

11、buted around one or more processes. The rudimentary data loggers scan select number of channels, connected to sensors or transducers, in a sequential manner and the data are recorded in digital format. A data logger can

12、be dedicated in the s</p><p>　　Microcomputer controlled data acquisition facilitates the scanning of a large number of sensors. The scanning rate depends upon the signal dynamics which means that some channe

13、ls must be scanned at very high speeds in order to avoid aliasing errors while here is very little loss of information by scanning other cannels at slower speeds. In some data logging applications the faster channels req

14、uire sampling at speeds of up to 100 times per second while slow channels can be sampled once every five</p><p>　　The vast majority of the user programmable data loggers can be used to scan up to 1000 analog

15、 and 1000 digital input channels. A small number of data loggers, with a higher degree of sophistication, are suitable for acquiring data from up to 15,000 analog and digital channels. The data from digital channels can

16、be in the form of Transistor-Transistor Logic or contact closure signals. Analog data must be converted into digital format before it is recorded and requires the use of suitable analog t</p><p>　　Most data

17、loggers have a resolution capability of ±0.001% or better. It is also possible to achieve a resolution of 1 micro-volt. The resolution capability, in absolute terms, also depends upon the range of input signals, Sta

18、ndard input signal ranges are 0-1- volt, 0-50 volt and 0-100 volt. The lowest measurable signal varies form 1 u volt to 50 u volt .A higher degree of recording accuracy can be achieved by using modules which accept data

19、in small, selectable rages. An alternative is the auto </p><p>　　The accuracy with which the data are acquired and logged on the appropriate storage device is extremely important. It is therefore necessary t

20、hat the data acquisition module should be able to reject common mode noise and common mode voltage. Typical common mode noise rejection capabilities lie in the range 110 dB to 150dB. A decibel (dB) is a term which define

21、s the ratio of the power levels of two signals. Thus if the reference and actual signals have power levels of Nr and Na respectively, they</p><p>　　n=10 Log 10 (Na /Nr) </p><p>　　Protection agai

22、nst maximum common mode voltages of 200 to 500 volt is available on typical microcomputer based data loggers.</p><p>　　The voltage input to an individual data logger channel is measured, scaled and linearise

23、d before any further data manipulations or comparisons are carried out.</p><p>　　In many situations, it becomes necessary to alter the frequency at which particular channels are sampled depending upon the va

24、lues of data signals received from a particular input sensor. Thus a channel might normal be sampled once every 10 minutes. If, however, the sensor signals approach the alarm limit, then it is obviously desirable to samp

25、le that channel once every minute or even faster so that the operators can be informed, thereby avoiding any catastrophes. Microcomputer controlled intell</p><p>　　The conventional hardwired data loggers, wi

26、thout any programming facilities, simply record the instantaneous values of transducer outputs at a regular sampling interval. This raw data often means very little to the typical user. To be meaningful, this data must b

27、e linearised and scaled, using a calibration curve, in order to determine the real value of the variable in appropriate engineering units. Prior to the availability of programmable data loggers, this function was usually

28、 carried out in t</p><p>　　1. ABSTRACT</p><p>　　The features of the data acquisition and control systems of the NASA Langley Research Centers Jet Noise Laboratory are presented. The Jet Noise La

29、boratory is a facility that simulates realistic mixed ow turbofan jet engine nozzle exhaust systems in simulated ight. The systems capable of acquiring data for a complete take-o_ assessment of noise and nozzle performan

30、ce.This paper describes the development of an integrated system to control and measure the behaviorof model jet nozzles featuring dual</p><p>　　2. INTRODUCTION</p><p>　　The problem of jet noise

31、has been studied for many years. Since sound from jets is generated by a variety of uid mechanical mechanisms including turbulence, reducing jet noise is challenging. The particular part of jet noise studied in the Jet N

32、oise Laboratory (JNL) of the NASA Langley Research Center (LaRC) is the noise generated by the jet exhaust, or plume. Fluid mechanic phenomenon that generate plume noise are turbulent mixing, supersonic eddy Mach wave ra

33、diation,noise generated by turbulen</p><p>　　3. DATA ACQUISITION SYSTEMS</p><p>　　The Dynamic Data Acquisition System (DDAS) is designed to record time data with frequence up to 100 KHz. The JNL

34、 DDAS is based on a SUN SPARC10 VME bus computer with recording capacity of 30 dynamic channels. A VME array processing card is included for performing data analysis (primarily fast Fourier transforms) in conjunction wit

35、h data acquisition. The JNL has a 28 microphone linear array for recording the fareld jet acoustics. Bruel & Kj_r (B&K) Instruments Type 4136 1/4" free _eld response m</p><p>　　These GPIB progr

36、ammable bandpass ampliers provide low and high pass corner frequency selection up to 102.3 KHz, pre-_lter gain of up to 40 dB in 10 dB steps,and post-_lter gain from -9.9 to 30.0 dB by steps of 0.1 dB. Each microphone si

37、gnal is then split into three paths: two dirent analog to digital (A/D) converter types and a custom 32 channel voltmeter.After data is recorded into the TDR memory, the host computer downloads the information over a GPI

38、B IEEE-488 bus interface or over the TDR 16 </p><p>　　The microphone signals recorded by the ICS-110A card are low-passed through a 32 channel VME ampli_er card with 25 KHz _xed corner frequency from Frequen

39、cy Devices Incorporated.</p><p>　　Figure 3.1 Noise Dynamic Data Acquisition System card) controls the ICS A/D card over the VSB bus the writes the data to the SUN hard disks.</p><p>　　Figure 3A

40、shows a block diagram of the complete dynamic data system. Another important part of the DDAS is a custom 32 channel Root-Mean-Square (RMS) voltmeter with a Liquid Crystal Display (LCD) display. The RMS voltmeter uses an

41、 embedded Z80 based single board computer by Z-World that has a 12 bit A/D converter to measure the output of the multiplexed RMS to DC converter circuits. The Z80 computer displays the overall Sound Pressure Level (SPL)

42、 of the microphone array on a 7"x4" LCD screen in </p><p>　　channels, and adjustable data point duration and sampling rate. Both individual samples and the average values over the point duration ca

43、n be saved to disk.</p><p>　　The analog input system is a Ne_ Instrument Corporation System 620 Series 600 which has a 100 KHz sample rate 16 bit A/D converter and can scan up to 512 channels per system. The

44、 JNL Ne_ has 64 channels in one 7" rack mount unit. The Ne_ 620 also supplies ampli_cation and low pass _lters. The force balance load cells are powered through a Ne_ System 620 Series 300 signal conditioner. The lo

45、ad cells are full bridge with built-in temperature compensation. Thermocouples are connected to the Ne_ Ser</p><p>　　4. INTEGRATION OF SYSTEMS</p><p>　　The entire JNL DDAS is comprised of a vari

46、ety of di_erent instruments and computers. The main computer originally was a DEC Micro-VAX computer but has been changed to a SUN UNIX system. Instrumentation connects to this host through the General Purpose Interface

47、Bus (GPIB) or RS-232 serial communications. Most of the original data acquisition software was coded in FORTRAN. The main e_ect of switching from DEC to UNIX was that the software for accessing RS-232 serial ports and GP

48、IB adapter were no</p><p>　　An operating system feature that improves the data acquisition programs is shared memory. Shared memory allows multiple independent programs to communicate with each other very ra

49、pidly.</p><p>　　On UNIX computers, the shared memory region is created by C functions. The address of the region is passed as an argument to a FORTRAN subroutine and the FORTRAN code uses a structure de_niti

50、on to de_ne variables relative to memory locations. This sharing feature was also available under the DEC VMS operating system.Another important mechanism for connecting computers is by using the Ethernet network. The SD

51、AS developed by Wyle Labs included a server program that was based on Berkeley Standard D</p><p>　　Two programs developed for the DDAS combine all of these features and serve as the foundation for testing wi

52、th the DSPM. A real time program called Background is designed to provide information for monitoring the conditions of the facility and model. Background establishes the shared memory region, initializes communication wi

53、th various instruments, connects to the SDAS by sockets and the control system by RS-232. It then enters an endless loop in which it reads the instruments, SDAS, and contro</p><p>　　5. FUTURE IMPROVEMENTS<

54、;/p><p>　　As research requirements change, so do the tools necessary to meet those requirements. Every aspect of the JNL data acquisition and control systems have been modi_ed in some way after entering service

55、. The control system is currently inadequate for closed loop control of both burners simultaneously. Replacing some of the Optomux I/O with a higher speed type is being examined as a way of improving the system for close

56、d loop control. Installing PC I/O cards that would still be controlled by the Pa</p><p>　　The other limitation of the TDR system is the slow download speed. It takes approximately 4.5 minutes to read out the

57、 data and write it to disk on the DDAS computer. The goal for setting the gains and having the data written out to the DDAS disks is a total of 2 minutes. One type of product that is being examined to meet this requireme

58、nt is a VME bus based A/D card with 16 bit A/D converters that can sample at 250 KHz, with a high speed data port connected to an auxiliary processor (AP) like the</p><p>　　6. ACKNOWLEDGMENTS</p><

59、p>　　The author would like to thank the Jet Noise Group of the Aeroacoustic Branch for their support and comments during the development of the systems described in this paper. As with any project of this scope, many p

60、eople were involved in building this entire system. In particular, I would like to recognize NASA engineers Jack Seiner, Michael Ponton, Martha Brown, Henry Haskin, and Robert Grandle, NASA operations support personnel C

61、li_ord Williford, Gregory Hogg, Beverly Jones Anderson, Richard Whi</p><p><b>　　數(shù)據(jù)采集</b></p><p>　　數(shù)據(jù)采集??系統(tǒng)，用于采集運行中的數(shù)據(jù)，并存儲在輔助存儲器上，以供日后分析。許多數(shù)據(jù)采集系統(tǒng)以很高的速度獲得這些數(shù)據(jù)，并且留給電腦很少的時間進(jìn)行任何必要的或可取的數(shù)據(jù)操

62、作或減少。所有數(shù)據(jù)都存儲在輔助存儲設(shè)備上，隨后獲得感興趣的變量。設(shè)計專用的數(shù)據(jù)采集系統(tǒng)和接口來獲得高速過程數(shù)據(jù)是非常必要的。這種特殊目的的設(shè)計可能是個昂貴的主張。</p><p>　　強(qiáng)大的迷你和主機(jī)計算機(jī)被用來將數(shù)據(jù)采集與其他功能,如比較實際輸出和期望的輸出值,然后決定控制行為,在預(yù)先設(shè)定的限制內(nèi)采取措施保證產(chǎn)出變量。其計算能力需要將取決于類型的過程控制系統(tǒng)的實現(xiàn)。針對執(zhí)行比例、比率或過程變量三項控制的軟件需求

63、相對瑣碎,但微型計算機(jī)可用于實現(xiàn)這樣的過程控制系統(tǒng)。它將不可能使用許多現(xiàn)有的微機(jī)的實施高速自適應(yīng)控制系統(tǒng)必須使用合適的過程模型和可觀的在線操作數(shù)據(jù)。</p><p>　　微機(jī)數(shù)據(jù)采集器是用來進(jìn)行中間數(shù)據(jù)采集等功能于一體,在相對較低的速度,簡單的數(shù)學(xué)操作的原始數(shù)據(jù)和一些形式的數(shù)據(jù)歸算的。第一代數(shù)據(jù)采集器沒有任何可編程計算機(jī)設(shè)備,采用慢速從一百個頻道采集了數(shù)據(jù)。所有獲得的數(shù)據(jù)可以在紙帶上穿孔或打印之后的分析。這種硬件

64、連線數(shù)據(jù)采集器被與微機(jī)結(jié)合、并可由用戶編程的新一代數(shù)據(jù)采集器所取代。他們提供了一個極好的過程數(shù)據(jù)收集方法,采用標(biāo)準(zhǔn)化的接口,隨后執(zhí)行必要的操縱向過程操作員提供這有用的信息。獲得的數(shù)據(jù)可用于分析在過程變量與開發(fā)自適應(yīng)和優(yōu)化過程控制必須的數(shù)學(xué)模型之間是否具有差異性。</p><p>　　數(shù)據(jù)采集器執(zhí)行的數(shù)據(jù)采集功能在不同系統(tǒng)之間變化。簡單的數(shù)據(jù)日志系統(tǒng)獲得數(shù)據(jù)從幾個通道而復(fù)雜系統(tǒng)接收數(shù)據(jù)從數(shù)百,甚至數(shù)千輸入通道的分布

65、在一個或多個過程。初步的數(shù)據(jù)采集器用掃描數(shù)來選擇, 用一個順序的方式連接到傳感器或轉(zhuǎn)換器,數(shù)據(jù)記錄用數(shù)字格式。一個數(shù)據(jù)監(jiān)測器在某個意義上說,它只能收集數(shù)據(jù)從特定類型的傳感器及轉(zhuǎn)換器。最好是使用非專用數(shù)據(jù)采集器因為任何傳感器或轉(zhuǎn)換器能被連接到使用適當(dāng)?shù)男盘柼幚砟K。微型計算機(jī)控制的數(shù)據(jù)采集便于大量的傳感器掃描。掃描速率取決于信號動態(tài)，這意味著為了避免錯誤一些通道必須在非常高速掃描,而在較慢的速度掃描其他通道信息會有非常小的損失。在一些數(shù)據(jù)

66、采集應(yīng)用中，快速通道需要可達(dá)每秒100次的采樣速度，而慢速通道可以每隔五分鐘采樣一次。傳統(tǒng)的硬件接線、不可編程的數(shù)據(jù)采集器以一種連續(xù)的方式采樣所有的通道，并且所有通道的采樣頻率都必須是相同。本程序的結(jié)果在積累了大量的數(shù)據(jù),其中一些是不必要的,也減緩了全面有效的采樣頻率。和其它慢速通道相比，基于微機(jī)的數(shù)據(jù)采集器可用在較高頻率下掃描快速通道。</p><p>　　絕大多數(shù)的用戶可編程的數(shù)據(jù)采集器可以用來掃描1000個

67、模擬和1000個數(shù)字輸入通道。少量的數(shù)據(jù)采集器,具有較高的先進(jìn)性,適合從15000模擬和數(shù)字通道獲取數(shù)據(jù)。數(shù)字通道的數(shù)據(jù)可以有以下幾種形式:晶體管-晶體管邏輯或節(jié)點閉合信號。模擬數(shù)據(jù)必須被轉(zhuǎn)換成數(shù)字形式記錄并且必須使用合適的模擬/數(shù)字轉(zhuǎn)換器(ADC)。ADC的特性能定義可實現(xiàn)的分辨率，以及不同通道都可以采樣分析的速率。越來越多的用于提高位分辨率的A/D轉(zhuǎn)換器。逐次逼近型ADC的分辨率比積分型ADC快。許多微型計算機(jī)控制的數(shù)據(jù)采集器一起使

68、用包括設(shè)施規(guī)劃通道掃描率。典型的掃描速率變化從每秒2頻道到每秒10000個通道。</p><p>　　大多數(shù)數(shù)據(jù)采集器具有±0.01%或更好的分辨能力。也有可能達(dá)到1微伏的分辨率。從絕對意義上來說，分辨能力也取決于輸入信號的范圍,標(biāo)準(zhǔn)輸入信號范圍為0-10伏特、0-50伏特和0-100伏特。最低的可測量從1到50伏特的信號變化，使用在較小、可選范圍內(nèi)接收數(shù)據(jù)的模塊可獲得較高的采集精度。另一種是從數(shù)據(jù)采集

69、器里得到的自動測距裝置。</p><p>　　準(zhǔn)確的數(shù)據(jù)獲取、登陸合適的存儲設(shè)備是十分重要的，因此對數(shù)據(jù)采集模塊來說抑制共模噪聲和共模電壓是必要的。典型的共模噪聲抑制能力在110dB-150dB范圍之間，分貝(dB)即為定義為兩種信號功率電平比值，因此,如果參考信號和實際信號的功率電平分別為Nr、Na,它們的比值為n分貝，其中</p><p>　　n = 10 Log10（Na/ Nr)&

70、lt;/p><p>　　防止最大普通模式電壓200至500伏特的典型可在微機(jī)數(shù)據(jù)采集器一起使用。</p><p>　　電壓輸入到一個單獨的數(shù)據(jù)樵夫通道量測、規(guī)?；途€性化任何進(jìn)一步的數(shù)據(jù)操作前或比較執(zhí)行。</p><p>　　在許多情況下,有必要改變從某一特定輸入傳感器收到的數(shù)據(jù)信號所決定的特定通道的采樣頻率，因此，某種通道可能每隔10分鐘采樣一次，但是如果傳感器信號逼

71、近報警門限，很明顯就需要每分鐘、甚至更快的采樣，這樣就能使操作員能夠及時獲知信息,避免任何災(zāi)難的來臨。微型計算機(jī)控制的智能數(shù)據(jù)采集器可編程用于改變基于過程信號值的采樣頻率，包含自掃描模塊的其他數(shù)據(jù)采集器可以主動采樣。</p><p>　　沒有任何編程設(shè)施的傳統(tǒng)硬件接線數(shù)據(jù)采集器,能簡單地在固定采樣間隔內(nèi)記錄傳感元件輸出的瞬時值，這個原始數(shù)據(jù)通常很少與典型用戶相關(guān)。為了使其有意義,該數(shù)據(jù)必須使用校準(zhǔn)曲線進(jìn)行線化和調(diào)

72、節(jié),這樣就能以適當(dāng)?shù)墓こ虇挝淮_定變量的真實值。在可編程數(shù)據(jù)采集器可用之前,該函數(shù)通常是在微型或大型計算機(jī)的離線模式上執(zhí)行。原始數(shù)據(jù)值必須以二進(jìn)制或八進(jìn)制代碼在紙帶上打孔,用于輸入計算機(jī)進(jìn)行隨后的分析目的,并轉(zhuǎn)換為工程單位，紙帶打孔是能降低通道掃描速度的低速機(jī)械裝置，另一種是打印出原始數(shù)據(jù)值,并進(jìn)一步降低數(shù)據(jù)掃描速率的裝置，它不可能進(jìn)行任何限制比較或提供任何報警信息。由數(shù)據(jù)采集器獲取的每一個單值都必須進(jìn)行記錄,即使它可能在以后的分析中不起

73、到任何有用的目的；另外許多數(shù)據(jù)值只需當(dāng)他們處在預(yù)設(shè)低限和高限之外時進(jìn)行記錄。</p><p><b>　　1.摘要</b></p><p>　　美國國家航空和宇宙航行局蘭利研究中心噴氣機(jī)噪音實驗室介紹了數(shù)據(jù)采集和控制系統(tǒng)的特點。噴氣機(jī)噪聲實驗室模擬現(xiàn)實的混合設(shè)備, 建立擁有噴嘴噴氣發(fā)動機(jī)排氣系統(tǒng)。該系統(tǒng)能夠獲得一個完整的噪聲和噴嘴性能評估數(shù)據(jù)。本文闡述了開發(fā)于一體的控

74、制和測量噴氣機(jī)噴嘴具有雙重獨立模型高壓燃燒空氣流與風(fēng)隧道的綜合性系統(tǒng)。</p><p>　　數(shù)據(jù)采集、控制系統(tǒng)能夠同時測量力量、時刻、靜態(tài)和動態(tài)控制模型的壓力和溫度,和噴氣機(jī)的噪聲。為協(xié)調(diào)控制計算機(jī)和多種數(shù)據(jù)采集計算機(jī)和儀器的設(shè)計概念進(jìn)行了討論。對控制系統(tǒng)的設(shè)計與實現(xiàn)進(jìn)行解釋,指出描述的特點,設(shè)備和經(jīng)驗的個人電腦使用主要基于系統(tǒng)。檢查未來的發(fā)展領(lǐng)域。</p><p><b>　　

75、2.引言</b></p><p>　　噴氣機(jī)噪聲的問題已經(jīng)被研究了許多年。自從噴氣機(jī)噪聲產(chǎn)生于多種機(jī)械機(jī)制包括湍流,減少噴氣機(jī)噪聲是有挑戰(zhàn)性的。美國國家航空和宇宙航行局蘭利研究中心(LaRC) 噴氣機(jī)噪聲實驗室(JNL)研究噴氣機(jī)噪聲是由噴射排氣噪聲,或羽毛產(chǎn)生。流體力學(xué)現(xiàn)象產(chǎn)生的羽流噪聲是紊流混合、超音速艾迪馬赫波輻射、噪聲產(chǎn)生的旋渦通過湍流沖擊噪聲寬帶沖擊作為屬性,共振沖擊振動稱為尖叫。為了取得新

76、進(jìn)展的噴氣機(jī)降噪，研究需要試著去了解背后的物理噪聲產(chǎn)生的機(jī)理。仿真模型在射流規(guī)模上取得了巨大的成果。真正噴氣機(jī)的一個重要特征是高溫尾氣燃燒過程和行為溫度對噪聲產(chǎn)生的機(jī)理。在一個不能供熱的環(huán)境下導(dǎo)致噴氣機(jī)的噪音減少,并不總是噴氣機(jī)降噪熱的解決方案。噴氣機(jī)噪音大大降低,需要從一個研究機(jī)構(gòu),可以制作出逼真的溫度、壓力。一個正常的渦扇發(fā)動機(jī)，一般用于亞音速運輸噴氣機(jī)，有一個熱燃燒機(jī)制（核心流）包圍一個冷卻的壓縮機(jī)制（旁路或風(fēng)扇流）。</p

77、><p><b>　　3.數(shù)字采集系統(tǒng)</b></p><p>　　動態(tài)數(shù)據(jù)采集系統(tǒng)(DDAS)是用來記錄時間數(shù)據(jù),高達(dá)100千赫茲的頻率。JNL DDAS是基于SUN SPARC10 VME計算記錄能力為30個動態(tài)通道。一個VME陣列處理卡是包括了執(zhí)行數(shù)據(jù)分析(主要是快速傅里葉變換)和結(jié)合數(shù)據(jù)采集。JNL擁有28個傳音器線性數(shù)組記錄噴氣機(jī)噪音的情況。Br_uel和Kj_

78、r (B&K)儀器4136 1/4型自由響應(yīng)傳音器和2811型多路復(fù)用器電源使用。傳音器帶寬延伸到大約100千赫茲。根據(jù)噴嘴模型、動態(tài)壓力傳感器安裝可以推一個內(nèi)部的部分測量表面壓力噴嘴。通常的傳感器產(chǎn)品模型XCE- 093, 直徑3/32英寸，常規(guī)設(shè)計水冷夾是用來保護(hù)傳感器。精密過濾器B&K2811的直接輸出是改變的。</p><p>　　通過這些GPIB可編程的器件提供低通和高通過拐角頻率選擇1

79、02.3 KHz,壓力以10分貝為階梯增加到40分貝為止,以0.1分貝為階梯從-9.9分貝增加到30.0分貝。每一個話筒信號分成了三個部分:兩個模擬到數(shù)字(A/D) 類型轉(zhuǎn)換器和一個定制的32路的電壓表。數(shù)據(jù)記錄到TDR存儲器,主機(jī)通過一個定制的主計算機(jī)在GPIB IEEE - 488總線接口或者在TDR 16位并行總線接口電路中下載信息。并行總線傳輸速率約為170 KB /秒GPIB接口速率約30 KB/秒。從集成電路與系統(tǒng)有限公司的

80、16位62.5千赫茲ICS-110A VME卡上，以低采樣率獲得另一個數(shù)據(jù)集。</p><p>　　從頻率設(shè)備股份有限公司通過32路拐角頻率25 KHz 的VME卡記錄傳音器信號。</p><p>　　圖3.1是動態(tài)數(shù)據(jù)采集系統(tǒng)噪聲控制ICS A/D卡通過VSB寫數(shù)據(jù)到SUN硬盤。</p><p>　　圖3 A顯示了一個完整的動態(tài)數(shù)據(jù)系統(tǒng)框圖。另一個重要的組成部分,

81、是一個定制的DDAS均方根(RMS)32頻道電壓表和液晶顯示屏(LCD)顯示。電壓表使用的均方根值基于嵌入式Z80單板機(jī)控制,通過Z-World 12位A/D轉(zhuǎn)換器測量輸出有效值電路,多路直流轉(zhuǎn)換器。電腦顯示器整體的Z80聲壓級(SPL)的傳音器陣列在7×4英寸液晶屏幕上顯示一個條形圖的格式(圖3 B)。DDAS讀取電壓值是在TDR信號數(shù)字化前對RMS電壓表進(jìn)行選擇所得。DDAS電腦的中央控制器，并不是唯一的電腦系統(tǒng)。靜態(tài)數(shù)據(jù)

82、采集系統(tǒng)(SDAS)用來記錄不同的信號和計算這些信號時間跨度緩慢的平均值。JNL SDAS是一個開放體系結(jié)構(gòu)的計算機(jī)。這是一個6-U VME總線系統(tǒng)使用在雙摩托羅拉88 K的CPU和REAL/IX 實時UNIX操作系統(tǒng)上。數(shù)據(jù)采集軟件應(yīng)用于美國國家航空和宇宙航行局諾拉懷爾實驗室。它的特性包括一個圖形用戶接口(GUI)、實時圖形顯示，用戶可編程的方程和校準(zhǔn)渠道，可調(diào)數(shù)據(jù)點時間和采樣率。個人樣品對點時間平均值可以保存到磁盤。</p&g

83、t;<p>　　模擬輸入系統(tǒng)是一個儀器公司620系列600型號，其中有一個100千赫采樣率16位A/D轉(zhuǎn)換器,可以掃描每512個通道系統(tǒng)。JNL Ne_ 620的一個機(jī)架安裝單元有64個頻道。Ne_ 620還提供高通和低通。負(fù)載平衡力通過單元提供動力的Ne_620系列300信號調(diào)節(jié)器。負(fù)荷單元全橋內(nèi)置溫度補(bǔ)償。熱偶是連接到Ne_600通過儀器溫度均勻性很好的參考板(UTR)。該零件終端帶鋼一個100歐姆的鉑電阻溫度檢測器(

84、RTD)測量冷端溫度補(bǔ)償導(dǎo)線板改變銅絞線電線。用軟件編程來校正冷端溫度，并進(jìn)行了多項式電壓推導(dǎo)出熱電偶溫度。SDAS另一個主要部分的性能是衡量靜態(tài)壓力。設(shè)置飛機(jī)關(guān)鍵操作條件的總壓力,而上游噴管(稱為充電站)噴嘴也有測壓孔模型沿墻內(nèi)部速度可以使計算進(jìn)行比較的解決方案。其他壓力探針測量使用遠(yuǎn)程定位在實際射流排氣煙羽。JNL運用電子掃描壓力(ESP)系統(tǒng)和壓力系統(tǒng)(PSI)。本產(chǎn)品由傳感器模塊16,32,48或64個人應(yīng)變壓力傳感器模塊(總體

85、規(guī)模大小約2.5X1.5X1.5)。在一個16位A/D轉(zhuǎn)換器以50千赫茲采樣前多路傳感器與每個模塊和其他外部連接。每個模塊已建成了校準(zhǔn)壓力閥,可以用于</p><p><b>　　4.集成系統(tǒng)</b></p><p>　　JNL DDAS是由許多儀表和計算機(jī)組成的。主機(jī)是DEC Micro-VAX，但已經(jīng)換成了一個SUN UNIX系統(tǒng)。儀表連接到該主機(jī)通過通用接口總線

86、(GPIB)或RS—232串行通信。大多數(shù)的原始數(shù)據(jù)采集軟件編碼FORTRAN語言。主要方法從DEC切換到UNIX是軟件來訪問RS - 232串口和通用接口總線適配器，現(xiàn)在是通過C語言。大部分的JNL工程師們只有FORTRAN編程經(jīng)驗,所以一組C函數(shù)是用來簡化訪問C系列、GPIB和FORTRAN語言特征的通用接口總線。幾乎JNL每一個項目的都是C和FORTRAN程序的聯(lián)合作用。最新儀器VME總線系統(tǒng)的卡片,它能夠通過C語言基礎(chǔ)操作系統(tǒng)功

87、能和運行。</p><p>　　共享內(nèi)存提高了一個操作系統(tǒng)的數(shù)據(jù)采集功能。共享內(nèi)存允許多個獨立程序快速的來進(jìn)行彼此的溝通。在UNIX計算機(jī),共享內(nèi)存區(qū)是由C功能建立。區(qū)域的地址被作為一個參數(shù)傳遞到一個FORTRAN程序代碼和FORTRAN語言同樣結(jié)構(gòu)的變量的內(nèi)存位置。這種共享的特征是也可用在DEC VMS操作系統(tǒng)。另一個重要的機(jī)制,是連接計算機(jī)利用以太網(wǎng)網(wǎng)絡(luò)。諾拉·懷爾實驗室開發(fā)的性能包括一個服務(wù)器程序

88、,它是基于美國加州大學(xué)柏克萊分校的標(biāo)準(zhǔn)分布(BSD)接口。服務(wù)器可以送出真正的時間和平均數(shù)據(jù),被觸發(fā)而采取一個數(shù)據(jù)點,接受系統(tǒng)實時處理的數(shù)據(jù)值,并提供性能狀態(tài)信息。</p><p>　　DDAS的兩個項目結(jié)合了所有的這些功能和服務(wù)的基礎(chǔ)與DSPM測試。提出了一種實時節(jié)目背景的目的是提供信息,用于監(jiān)視設(shè)備和條件模型。背景建立共享內(nèi)存區(qū)域,通信和各類儀器設(shè)備初始化,通過插座連接性能并由RS-232控制系統(tǒng)。然后進(jìn)入一

89、個死循環(huán)中,它讀取儀器、性能、以及控制系統(tǒng)的數(shù)值,導(dǎo)出平均壓力和溫度計算值,然后送給SDAS同時控制系統(tǒng)的性能。DDAS其他主要項目獲得傳音器信號后被命名。這是程序,配合SDAS(為了性能和模型氣動數(shù)據(jù))數(shù)據(jù)采集過程性能的分析,以及DDAS(麥克風(fēng)和壓力資料)控制系統(tǒng)。</p><p>　　一系列的菜單提供用戶機(jī)會改變默認(rèn)設(shè)置，例如傳感器記錄的數(shù)量、采樣率、數(shù)據(jù)集的大小,以及頻率。一旦運營商DSPM調(diào)整到所需的試

90、驗條件、數(shù)據(jù)采集經(jīng)營者提供了部分的程序,用相同的RMS-DC儀表和調(diào)整精密過濾器的收益均方根值來實現(xiàn)這個目標(biāo)。當(dāng)DSPM采集數(shù)據(jù)，是在正確的條件和可以接受的增益下，程序觸發(fā)的的SDAS（設(shè)置平均從10到30秒）ICS-110A卡用8秒采樣62.5千赫茲，Paci_c TDRs卡2秒采樣250千赫茲。當(dāng)前值在后臺寫一個開始和結(jié)束時的平均周期的日志。</p><p><b>　　5.未來的改進(jìn)</b&

91、gt;</p><p>　　為研究需求的變化,所以做必要的工具來滿足這些需求。JNL的每一個方面讓數(shù)據(jù)采集和控制系統(tǒng)已經(jīng)在某種程度上進(jìn)入服務(wù)。該控制系統(tǒng)是目前不適用于閉環(huán)控制的兩個燃燒器同時進(jìn)行。更換部分的I/O和更高的速度打字是提高整個系統(tǒng)的閉環(huán)控制的一種方式。安裝計算機(jī)I/O卡是一個可以控制TNT軟件的選擇。添加一個可編程邏輯控制器(PLC)控制系統(tǒng)或其他控制系統(tǒng)/軟件包,可以用于TNT作為模板。這是一個理想

92、的模擬輸入12位A/D轉(zhuǎn)換器和較多特定參數(shù)的設(shè)計。目前的DDAS是有限的12位分辨率和有限的數(shù)據(jù)下載速度。因為得到了12位分辨率必須設(shè)置防止削波,但會取得最高的信噪比(SNR)和動態(tài)范圍。未來的計劃包括購買16位A/D轉(zhuǎn)換器,為設(shè)置一個給定的增益更大的動態(tài)范圍提供一個解決方案。增益就必須設(shè)置足夠高,使獲得較好的噪聲記錄。為所有頻道計算增益要求做到大約1伏特，設(shè)置增益,然后在獲得數(shù)據(jù)前不斷地復(fù)查有效值的數(shù)據(jù)。噴氣機(jī)噪聲產(chǎn)生3個因素（非正弦

93、），因此使用RMS不是一個防止削波的可靠方法。增益設(shè)置過程需要2到5分鐘。</p><p>　　TDR系統(tǒng)的另一個限制是緩慢的下載速度。需要大約4.5分鐘來讀數(shù)據(jù),并把它記錄到DDAS電腦的磁盤上。目標(biāo)增益的設(shè)定和寫數(shù)據(jù)到DDAS的磁盤一共用2分鐘。現(xiàn)正研究一個類型的產(chǎn)品，以滿足這一要求是基于VME總線的16位的A/D轉(zhuǎn)換器，可在250 kHz采樣的A/D卡，連接到一個輔助處理器（AP），如目前使用的高速數(shù)據(jù)端口

94、。32通道的,總的數(shù)據(jù)比例每秒達(dá)800萬個樣本或每秒15.26MB。</p><p><b>　　6.致謝</b></p><p>　　感謝射流噪聲集團(tuán)的Aeroacoustic分公司,感謝他們的支持和系統(tǒng)開發(fā)過程中的意見。在此范圍內(nèi)的任何項目,許多人積極參與到整個系統(tǒng)的建立。我特別想要認(rèn)識到美國宇航局的工程師們杰克,邁克爾·波頓,瑪莎·布朗,亨利