設(shè)計(jì)主體內(nèi)容外文翻譯朱豪杰

1、譯文:航海學(xué)704. 重新設(shè)置航位推算重新設(shè)置航位推算圖，使之反復(fù)逐個(gè)修復(fù)或者運(yùn)行修復(fù)。此外，如果安裝了一個(gè)慣性系統(tǒng)，就需要考慮重新設(shè)置航位推算到一個(gè)慣性估計(jì)的位置。如果一個(gè)導(dǎo)航器在長(zhǎng)時(shí)間內(nèi)沒(méi)有被修復(fù)，航位推算圖沒(méi)有復(fù)位固定，將會(huì)累積時(shí)間誤差。隨著時(shí)間的推移，錯(cuò)誤可能變得越來(lái)越嚴(yán)重，以致于航位推算將再也無(wú)法顯示該船舶的精確位置。如果該船舶配備了一個(gè)慣性導(dǎo)航器，那么導(dǎo)航器可以考慮到重新設(shè)置航位推算到慣性估計(jì)的位置。作出這項(xiàng)決定時(shí)，需要考慮到以下這些：1、自上次修復(fù)和修復(fù)信息的可用性的時(shí)間。如果自上次修復(fù)到現(xiàn)在的時(shí)間距離很短，并且修復(fù)信息將很快成為可用的，那么等待下一次重新設(shè)置航位推算是明智的選擇

2、。2、動(dòng)態(tài)導(dǎo)航情況。舉個(gè)例子，假如一艘水下潛艇在墨西哥灣流行駛，修復(fù)信息可用但是運(yùn)行方面的考慮也許會(huì)阻礙潛艇潛望鏡深度得到修復(fù)。同樣，一艘配有一個(gè)慣性導(dǎo)航器的水上艦艇也許會(huì)被卷入動(dòng)態(tài)電流，并且電子修復(fù)設(shè)備的臨時(shí)損失。無(wú)論如何，修復(fù)信息的可用性是短期的，但是動(dòng)態(tài)的情況需要更準(zhǔn)確地評(píng)估船舶的位置。繪制一個(gè)慣性估計(jì)位置和復(fù)位航位推算，估計(jì)位置可以讓導(dǎo)航器更加準(zhǔn)確地評(píng)估導(dǎo)航情況。3、修復(fù)源的可靠性和準(zhǔn)確性。如果一艘潛艇在冰下運(yùn)行，例如，只有慣性估計(jì)位置修復(fù)在幾周之內(nèi)可用。鑒于慣性估計(jì)位置和高度準(zhǔn)確修復(fù)系統(tǒng)之間的高度相關(guān)性，比如 GPS，以及慣性導(dǎo)航器持續(xù)的正常運(yùn)轉(zhuǎn)，導(dǎo)航器可以決定重置航位推算到慣性 E

3、P。航位推算與船舶安全正確地一個(gè)航位推算圖對(duì)船舶安全。航位推算可以讓導(dǎo)航器在計(jì)劃的，并且采取適當(dāng)?shù)挠?jì)劃和行動(dòng)來(lái)避免它們。軌道中檢查一個(gè)點(diǎn)。它讓他預(yù)見(jiàn)到記住一點(diǎn)，航位推算的位置只是近似的。使用一個(gè)稱為修復(fù)擴(kuò)展的概念對(duì)航位推算的誤差進(jìn)行修復(fù)，并允許導(dǎo)航器使用航位推算進(jìn)行更有效地，避免。705.修復(fù)擴(kuò)建在通常情況下，一艘船在開(kāi)放的海洋上行駛，長(zhǎng)時(shí)間得不到修復(fù)。這可能會(huì)導(dǎo)致從大量的錯(cuò)誤到無(wú)法獲得修復(fù)故障的電子導(dǎo)航系統(tǒng)。在潛水艇上進(jìn)行修復(fù)更是罕見(jiàn)。無(wú)論什么原因，在某些情況下，導(dǎo)航員也許會(huì)發(fā)現(xiàn)他不得不在航位推算的單獨(dú)處理好幾個(gè)小時(shí)。導(dǎo)航員必須采取預(yù)防措施，以確保所有危害通過(guò)一個(gè)近似航位推算的位置?？梢允褂?/p>

4、的方法之一就是修復(fù)擴(kuò)建。修復(fù)擴(kuò)展應(yīng)該考慮到在傾向于影響船的實(shí)際路線和速度在地面造成的航位推算可能導(dǎo)致的錯(cuò)誤。導(dǎo)航員考慮所有這一類(lèi)并且在航位推算圖附近開(kāi)發(fā)一個(gè)不斷擴(kuò)大的“錯(cuò)誤圈”。修復(fù)擴(kuò)展的基本假設(shè)之一是個(gè)別影響當(dāng)前的回旋余地和轉(zhuǎn)向錯(cuò)誤相結(jié)合，導(dǎo)致錯(cuò)誤不斷累積。因此，隨著時(shí)間推移，擴(kuò)大的概念會(huì)不斷增加。事實(shí)上，雖然錯(cuò)誤可能互相抵消了，但是導(dǎo)航器必須到的情況，這是不斷累積的。在修復(fù)擴(kuò)展演算考慮的錯(cuò)誤中，包含可能導(dǎo)致航位推算不精確的所有錯(cuò)誤。一些最重要的是電流和風(fēng)、 指南針或陀螺儀誤差以及轉(zhuǎn)向錯(cuò)誤。嘗試確定錯(cuò)誤圈子中的任何方法都必須考慮到這些。導(dǎo)航員可以使用一整套的漂移計(jì)算來(lái)判斷航位推算圖的嚴(yán)重程度

5、。請(qǐng)參閱第 707 篇文章。他可以從試點(diǎn)圖表或天氣預(yù)報(bào)中獲取當(dāng)前的估計(jì)程度。他可以確定從天氣儀器中風(fēng)速。他可以通過(guò)羅盤(pán)誤差與一個(gè)準(zhǔn)確標(biāo)準(zhǔn)相比來(lái)獲得方位的羅盤(pán)錯(cuò)誤。導(dǎo)航員要確定這些錯(cuò)誤在他的路線和速度結(jié)束地面的作用，并且申請(qǐng)錯(cuò)誤，用于修復(fù)擴(kuò)展的演算。如上文所述，時(shí)間是一個(gè)錯(cuò)誤的函數(shù)，它隨著船沿軌道而逐漸得到修復(fù)。因此，導(dǎo)航器必須納入到半徑隨著時(shí)間而增長(zhǎng)的錯(cuò)誤圈子里。例如，假設(shè)導(dǎo)航員計(jì)算錯(cuò)誤的所有各種各樣的誤差源可能創(chuàng)造一個(gè)累積位置誤差不超過(guò) 2 毫微米，然后他的修復(fù)擴(kuò)展錯(cuò)誤圈子將以該速度不斷增長(zhǎng)，在第一個(gè)小時(shí)以后，它會(huì)變成 2 毫微米，兩個(gè)小時(shí)后，它會(huì)變成 4 毫微米，以此類(lèi)推。導(dǎo)航員使用這個(gè)錯(cuò)

6、誤圈子到底意義呢？從每個(gè)修復(fù)中撤銷(xiāo)航位推算。所有的修復(fù)來(lái)源有有限的絕對(duì)準(zhǔn)確性，并且初始的錯(cuò)誤圈子應(yīng)該反映出這種高準(zhǔn)確性。例如，假設(shè)導(dǎo)航系統(tǒng)有 0.5 毫微米的準(zhǔn)確性，那么應(yīng)該設(shè)置的最初的錯(cuò)誤圈子的附近修復(fù)在 0.5 毫微米。首先，將一個(gè)圓的半徑用于獲取此修復(fù)系統(tǒng)準(zhǔn)確性的修復(fù)位置。其次，計(jì)劃有序的路線和速度來(lái)修復(fù)位置。然后應(yīng)用修復(fù)擴(kuò)展圈子于每小時(shí)的航位推算，每次增加錯(cuò)誤圈子的半徑錯(cuò)誤。在上述例子中，一個(gè)小時(shí)后，航位推算的圈子半徑將會(huì)變成 2.5 毫微米，兩個(gè)小時(shí)后，將會(huì)變成 4.5 毫微米，以此類(lèi)推。圍繞了四個(gè)小時(shí)的航位推算與錯(cuò)誤圈子，導(dǎo)航員將繪制原產(chǎn)與原始錯(cuò)誤圓相切，并且與其他錯(cuò)誤圈子同時(shí)相切

7、的兩條線。然后導(dǎo)航員嚴(yán)密檢查導(dǎo)航到的兩條切線之間的區(qū)域。修復(fù)擴(kuò)展包括船的總面積（只要所有誤差源都被考慮）。如果有任何在錐體之內(nèi)被表明，那么導(dǎo)航員應(yīng)該對(duì)那些警報(bào)尤其。舉個(gè)例子，例如修復(fù)擴(kuò)展表明船也許駛?cè)霚\灘水，不斷監(jiān)測(cè)回聲測(cè)深儀。同樣，如果修復(fù)擴(kuò)展表明船也許會(huì)阻礙圖的繪制，那么崗位要被額外監(jiān)視。修復(fù)擴(kuò)展可能的增長(zhǎng)速度也許會(huì)變得難以控制。顯然，如果修復(fù)擴(kuò)大增長(zhǎng)，覆蓋面積太大，作為導(dǎo)航員的一個(gè)工具，它失去了它的有用性，并且他應(yīng)該通過(guò)所有可利用的獲得新的修復(fù)。確定一個(gè)估計(jì)位置估計(jì)位置 (EP)是為余地、的錯(cuò)誤和電流的作用修改的航位推算位置。該部分將簡(jiǎn)要地造成航位推算位置從船的實(shí)際位置分流的。然后，將計(jì)

8、算集合和漂移，以及運(yùn)用這些價(jià)值于航位推算，最終獲得一個(gè)估計(jì)的位置。706. 影響航位推算位置準(zhǔn)確性的潮流是月亮和表面的潮汐引力引起的水的表面的周期性水平運(yùn)動(dòng)。潮流是氣象，海洋學(xué)或者地形學(xué)作用造成的海表面的水平的運(yùn)動(dòng)。無(wú)論它的來(lái)源是哪里，海的表面的水平運(yùn)動(dòng)是船行駛的一股重要的動(dòng)態(tài)力量。設(shè)置指的是當(dāng)前的方向和漂移提到潮流的速度?；匦嗟厥侵复坝捎谶@部分垂直于船舶航跡的風(fēng)產(chǎn)生的矢量背風(fēng)運(yùn)動(dòng)?；匦嗟睾彤?dāng)前相結(jié)合產(chǎn)生的最顯著的影響是讓船行駛得更加順利?；匦嗟貙?duì)于航行的船只和雙面高的船只影響尤其之大。除了這些自然力量之外，相對(duì)較小的舵手和轉(zhuǎn)向指南針相結(jié)合也許會(huì)產(chǎn)生錯(cuò)誤，并且導(dǎo)致航位推算其他的錯(cuò)誤。外

9、文原文：The American Practical704. Resetting the DRReset the DR plot to each fix or running fixurn. In addition, consider resetting the DR toan inertial estimatedition, if an inertial system is installed.If a navigator has not taken a fix for an extended period of time, the DR plot, noving beenreset to

10、a fix, will accumulate time-dependent errors. Over timet error maye sosignificantt the DR will no longer show the shipsition wicceptable accuracy. Ifthe veis equipped win inertial navigator, the navigator should consider resetting theDR to the inertial estimated determination are:ition. Some factors

11、 to consider when making thisTime since the last fix and availability of fix information. If is been a short timesince the last fix and fix information may soon wait for the next fix to reset the DR.e available, it may be advisable toDynamics of the navigation situation. If, forexle, a submerged sub

12、marine isoperatinghe Gulf Stream, fix information is availabut operational considerationsmay preclude the submarine from going to periscope depth to obtain a fix. Similarly, asurfa loss of shortlyhip win inertial navigator may be in a dynamic current and suffer a temporaryelectronic fix equipment. I

13、n either case, the fix information will be available but the dynamics of the situation call for a more accurate assessment of thevesition. Plotting an inertial EP and resetting the DR tot EP may provide thenavigator wimore accurate assessment of the navigation situation.Reliability and accuracy of t

14、he fix source. If a submarine is operating under the ice,for exle, only the inertial EP fixes may be available forks aime. Given a high ch as GPS, andprior correlation betn the inertial EP and highly accurate fix systemthe continued proper operation of the inertial navigator, the navigator may decid

15、e to reset the DR to the inertial EP.DEAD RECKONING AND SHIP SAFETYProperly maaining a DR plot is important for ship safety. The DR allows the navigator toexamine a futureition in relation to a planned track. It allows him toipate charted ition is onlyhazards and plan appropriate action to avoid the

16、m. Recallt the DRapproximate. Using a concept called fix expancompensates for the DRs inaccuracy andallows the navigator to use the DR more effectively toipate and avoid danger.705. Fix ExpanOften a ship any number oshe open ocean for extended periods without a fix. This can result fromctors ranging

17、 from the inability to obtain celestial fixes to malfunctioningelectronic navigation systems. Infrequent fixes are particularly common on submarines.Whatever the reason, in some instana navigator may find himselfheition of havingtomany hours on DR alone.The navigator must take precautions to ensuret

18、 all hazards to navigation along his pareaccounted for by the approximate nature of a DRition. One method which can be used isfix expan.Fix expan which tendtakeso accountsible errors in the DR calculation caused by factorsto affect the ves actual course and speed over the ground. The navigatorconsid

19、ers all such factors and develops an expanding “error circle” around the DR plot. Oneof the basic amptions of fix expanist the various individual effects of current, cumulative error which increases over time,leeway, and steering error combine to cause ahence, the concept of expan. While the errors

20、may in fact cancel each other out, the worstcase ist they will all be additive, and this is what the navigator mustipate.Errors consideredhe calculation of fix expanpass all errorst can lead to DRinaccuracy. Some of the most important factors are current and wind, compassyro error, and steering erro

21、r. Any method which attempts to determine an error circle must take thesefactorso account. The navigator can use the magnitude of set and drift calculated from hisDR plot. See Article 707. He can obtahe currents estimated magnitude from pilot charts or weather reports. He can determine wind speed fr

22、om weather instruments. He candetermine compass error by comparison win accurate standard or by obtaining an azimuthof the Sun. The navigator determines the effect each of these errors has on his course andspeed over ground, and appst error to the fix expancalculation.As noted previously, error is a

23、 function of time; it grows as the ship proceeds along the trackwithout obtaining a fix. Therefore, the navigator must incorporate his calculated errorso anterror circle whose radius grows with time. For exle, ame the navigator calculatesall the various sour Then his fix expanof error can create a c

24、umulativeition error of no moren 2 nm.error circle would grow att rate; it would be 2 nm after thehour, 4 nm after the second, and so on.At what value should the navigator start this error circle? Recallt a DR is laid out fromevery fix. All fix sourhave a finite absolute accuracy, and the initial er

25、ror circle shouldreflectt accuracy. Ame, for exle,t a salite navigation system has an accuracyof 0.5 nm. Then the initial error circle aroundt fix should be se0.5 nm., enclose the fixition in a circle, the radius of which is equal to the accuracy of thesystem used to obtahe fix. Next, lay out the or

26、dered course and speed from the fixition.Then apply the fix expancircle to the hourly DRs, increasing the radius of the circythe error factor each time. In the exle given above, the DR after one hour would beenclosed by a circle of radius 2.5 nm, after two hours 4.5 nm, and so on. Having encircled t

27、hefour hour DRitions with the error circles, the navigator then draws two lines originatingtangent to the original error circle and simultaneously tangent to the other error circles. Thenavigator then closely examines the area betn the two tangent lines for hazards tonavigation. This technique is il

28、lustrated in Figure 705.The fix expanpasses the total area in which the vecould be located (as long asall sourof error are considered). If any hazards are indicated withhe cone, the navigatorshould be espelly alert for those dangers. If, for exle, the fix expanindicatestthe vemay be standingo shoal

29、water, continuously monitor the fathometer. Similarly,if the fix expan extra lookouts.indicatest the vemight be approaching a charted obstruction,tThe fix expanmay grow at such a ratet ites unwieldy. Obviously, if the fixexpangrows to cover too large an area, is lost its usefulness as a tool for the

30、 navigator,and he should obtain a new fix by any available means.DETERMINING AN ESTIMATEDITIONAn estimatedition (EP) is a DRition corrected for the effects of leeway, steering error,and current. This section will briefly discuss the factorst cause the DRition to divergefrom the veualition. It will then discuss calculating set and dri