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Science and Technology Military camouflage That old razzle dazzle
科技 軍事偽裝 舊式迷魂戰術
How to confuse the enemy about how quickly you are travelling
如何讓敵方無法判斷己方的前行速度
IN THE second world war, many Allied ships were painted with dark and light stripes, and other contrasting shapes, making them look a bit like zebra.
二戰期間，許多盟軍軍艦船身都被噴涂了黑白條紋及其它迷彩圖案，這讓它們看上去有些象斑馬。
The idea was to distort an enemy submarine commander's perception of the ship's size, shape, range, heading and speed, so as to make it harder to hit with the non-homing torpedoes of the period.
這樣做的目的是為了迷惑敵軍潛水艇指揮官，使其無法判斷盟軍船艦的尺寸，形狀，距離，航向和速度。由于當時的魚雷還不具備制導系統，因此想要擊中目標愈加困難。
These had to be pointed not at the target directly but, rather, at the place where the commander thought the target would be when the torpedo arrived.
因此敵軍指揮官不再讓魚雷直接對準目標發射，而是將它們發射到他認為盟軍軍艦可能會駛向的位置。
At the time, though, it was only an educated guess that this so-called dazzle camouflage would work.
當時, 對于這種所謂的迷彩偽裝術的有效性判斷還只是基于經驗上的考量。
Now someone has actually tested it and the short answer is that it does work—but not in the way that Allied navies thought it did. Ships move too slowly for dazzle camouflage to be effective.
而如今已經有人對此進行了真實測試，結果驗證這種迷彩偽裝的確有效——但并不是按照盟軍海軍所設想的那種方式發揮作用。
However, it might well have a role in protecting faster-moving vehicles, such as military Land Rovers.
迷彩偽裝無法保護航行速度過慢的船艇。但它對于軍用路虎這樣快速行駛的車輛卻能起到很好的保護作用。
Nicholas Scott-Samuel, of the University of Bristol, and his colleagues, came to this conclusion by asking volunteers to watch patterned rectangles cross a computer screen.
以上結論是由布里斯托爾大學的Nicholas Scott-Samuel和他的同事通過實驗得出的。
Some of the rectangles had horizontal stripes inside them. Some had vertical stripes. Some had zigzags. And some had checks.
他們讓志愿者觀察在電腦屏幕內橫向移動的長方形物體，這些物體內部被噴涂了不同圖案，圖案形式有橫紋，豎紋，鋸齒紋和方格紋。
Others, acting as controls, had no internal patterns.
而作為參照的物體則未噴涂任何圖案。
Each test involved a jazzy rectangle crossing the screen either before or after a plain one. Volunteers had to estimate which of the two was travelling faster.
每次實驗志愿者在觀看了迷彩圖案的長方形橫過電腦屏幕之前或之后,還被要求觀看一個沒有條紋圖案的物體橫過屏幕，之后志愿者需要估計這兩個物體哪個移動速度較快。
In fact, in all cases, the two rectangles travelled at the same speed.
實際上，在所有實驗中，這兩個長方形物體移動的速度都相同。
But the researchers varied the conditions in other ways, without telling the participants.
但研究人員通過其它方式改變了實驗條件，志愿者對此卻一無所知。
Sometimes both rectangles travelled slowly, at just over 3o of arc a second from the observer's point of view, as a ship might. Sometimes they travelled much faster, at 20o a second, mimicking the way a land vehicle moves.
有時兩個長方形物體移動速度都很慢，從志愿者的觀察角度看，就象一艘船以每秒駛過3度的距離在航行，有時它們都模仿陸地車輛行駛方式以每秒走過20度的距離快速移動。
The jazzy rectangles also came in different flavours. Some were low-contrast (ie, not very jazzy at all) and some high-contrast.
長方形物體的迷彩圖案也不盡相同，有些圖案對比度不強烈（看起來不那么花哨），有些圖案的對比度則很強。
The upshot, as Dr Scott-Samuel reports in the Public Library of Science, was that participants were not fooled by slow-moving rectangles, nor by low-contrast ones.
實驗結果如同Scott-Samuel 博士在公共科學圖書館報告所說，志愿者對慢速移動或圖案對比度不強的物體移動速度判斷較準確。
Fast-moving, high-contrast shapes, however, did befuddle them.
而對于快速移動和圖案對比度強烈的物體,他們的判斷常常出錯。
On average, an observer reckoned that such a fast, jazzy rectangle was going 7% slower than was actually the case.
志愿者對于有迷彩圖案和快速移動的正方形物體的速度估計要比它們的實際速度平均低了7%。
Ships, therefore, travel too slowly for dazzle camouflage to work.
因此噴涂迷彩偽裝的軍艦航行速度過于緩慢是起不到迷惑敵軍作用的。
In any case, modern torpedoes and missiles are guided to their target electronically.
在任何情況下,現代的魚雷和導彈都采用了電子制導來跟蹤目標。
But 20o a second corresponds to the perceived movement of a vehicle 70 metres away that is travelling at 90kph.
但是從視覺角度看,每秒20度的移動速度相當于在70米外看到一部車輛在以90公里/小時行駛。
That is precisely the sort of distance from which an unguided rocket-propelled grenade might be fired at a lightly armoured military vehicle, and just the sort of speed such a vehicle might be travelling at.
在與此相同的距離和速度條件下,一個非制導火箭推進榴彈能夠擊中一輛輕型裝甲軍車。
Perhaps the answer, then, is for modern armies to buy their Land Rovers second-hand from game parks, which often paint them in zebra stripes for effect.
如果果真如此,那么現代軍隊可以考慮在狩獵公園買個涂有斑馬條紋的二手路虎車了。
Whether real zebra got their own jazzy stripes to confuse predators has yet to be determined.
至于斑馬身上的條紋能否讓其躲過掠食動物的捕殺則還有待證實。
