调查人员如何找到火灾源头：英语精读讲义

November 18th, 1987.

1987年11月18日。

Like every night on the London Underground,

像每个夜晚的伦敦地铁一样，

it's packed.

这里挤满了人。

A train on the Piccadilly Line has just pulled into King's Cross, 短語動詞

一列皮卡迪利线的列车刚刚驶入国王十字车站，

one of Britain's busiest stations.

这是英国最繁忙的车站之一。

The horde of passengers get off,

大批乘客下了车，

but as they squeeze their way up the old wooden escalators, 短語搭配

但当他们挤上老旧的木制自动扶梯时，

one passenger notices a strange glow coming from within the escalator.

一名乘客注意到扶梯内部发出了奇怪的火光。

It's on fire.

起火了。

10 minutes later,

10分钟后，

the London Fire Brigade arrive on the scene 短語搭配

伦敦消防局赶到了现场，

to what is now a small escalator fire.

面对的只是一个自动扶梯上的小火情。

Nothing they haven't dealt with before. 語法

这不过是他们习以为常的情况。

But in a matter of seconds,

但几秒钟之内，

the entire escalator suddenly ignites,

整部自动扶梯突然燃烧起来，

sending a jet of fire upwards and into the ticket hall,

喷射出一股火柱直冲上方并涌入售票大厅，

killing 31 people inside.

导致里面的31人丧生。

Figuring out what exactly happened here was mind-boggling, 語法

弄清楚这里究竟发生了什么是极其困难的，

and it led investigators down a 7-month rabbit hole 習語

它让调查人员陷入了长达7个月的漫长探寻，

until they eventually discovered a unique physical phenomena

直到他们最终发现了一种独特的物理现象，

completely unknown until this point

一种在此之前完全不为人知的现象，

that allowed the fire to behave in mysterious ways.

正是它使得火势表现得如此诡异。

We animated the entire thing to show you how investigators locate the source of a fire

我们将整个过程制作成动画，向你展示调查人员是如何寻找火源的，

and how early computer simulations led to the discovery of this gravity-defying effect.

以及早期的计算机模拟是如何带来这种反重力效应发现的。

Even in a large fire,

即使在大型火灾中，

buildings usually don't burn all the way to the ground.

建筑物通常也不会完全被烧毁至平地。

Firefighters normally arrive in time to control the fire,

消防员通常能及时赶到控制火势，

leaving behind a scene full of clues and evidence that can lead investigators to the source.

留下一个充满线索和证据的现场，引导调查人员找到起火点。

By systematically narrowing down the search to the rooms with the most damage, 語法

通过系统性地将搜索范围缩小到受损最严重的房间，

they can start looking at the details.

他们可以开始研究细节。

Fire burns upwards and outwards.

火焰是向上和向外燃烧的。

And so when an object burns next to a wall,

因此，当一个物体靠墙燃烧时，

it creates a distinct V-shape that widens out closer to the ceiling.

它会形成一个明显的V字形，越靠近天花板就越宽。

If the object is slightly further from the wall,

如果物体离墙稍微远一点，

it creates more of a U-shaped burn mark

它则会形成一个更偏向U字形的燃烧痕迹，

since the tip of the fire doesn't touch the wall.

因为火焰的顶端没有接触到墙壁。

In a small simple fire that gets put out early, 短語動詞

在被及早扑灭的小型简单火灾中，

these burn marks usually point towards an obvious source of the fire.

这些燃烧痕迹通常指向一个明显的火源。

But once a fire spreads to multiple objects,

但一旦火势蔓延到多个物体，

these burn patterns start blending together.

这些燃烧图案就会开始融合在一起。

On top of that, 表達脈絡

除此之外，

fire can get pulled towards openings like doors and windows,

火焰会被门窗等开口吸引，

where the abundance of oxygen helps the fire grow.

那里充足的氧气有助于火势蔓延。

This can leave some areas of the room looking more damaged than the actual source.

这可能会使得房间的某些区域看起来比实际的起火点受损更严重。

Take a look at this room,

看看这个房间，

for example.

举个例子。

Is it obvious where the fire started?

起火点在哪里明显吗？

We can see multiple V-patterns,

我们可以看到多个V字图案，

but this area here looks more burnt.

但这里的区域看起来烧得更严重。

It's possible that the fire started here,

有可能火是从这里开始的，

but worked its way up to the curtain, 短語搭配

但一路向上烧到了窗帘，

dropping burning debris onto the sofa.

将燃烧的碎片掉落到了沙发上。

Then eventually,

然后最终，

the window smashed with the heat and allowed fresh oxygen to flow in,

窗户因高温碎裂，新鲜的氧气流了进来，

drawing the fire towards that side of the room.

将火焰引向了房间的那一侧。

But wait,

但是等等，

if you lift up the carpet,

如果你掀起地毯，

you'll see what looks like liquid stains. 語法

你会看到看起来像液体污渍的痕迹。

This can be a sign that something like gasoline was used to quickly and deliberately start the fire. 短語搭配

这可能是一个迹象，表明有人使用汽油之类的东西迅速并蓄意纵火。

If an investigator suspects arson,

如果调查人员怀疑是人为纵火，

they can send in a sniffer dog,

他们可以派出一只嗅探犬，

specially trained to sniff out these kinds of flammable substances. 短語動詞

专门训练来嗅出这类易燃物质。

If none of this leads towards an obvious source,

如果这些都没有指向一个明显的火源，

the investigators will look towards the objects themselves.

调查人员就会把目光投向物体本身。

When materials reach a certain temperature,

当材料达到一定温度时，

the water molecules and other organic compounds inside turn into gas,

内部的水分子和其他有机化合物会变成气体，

leaving behind a layer of carbon.

留下了一层碳。

This is known as char. 用詞

这就是所谓的炭化层。

As the material keeps burning,

随着材料继续燃烧，

it works its way inward towards the fresh unburnt material,

它会向内侵入尚未燃烧的新鲜材料，

leaving behind a thicker and thicker layer of char over time. 語法

随着时间的推移，留下的炭化层会越来越厚。

And so by measuring the char depth of similar materials at various points in the room,

因此，通过测量房间内不同位置相似材料的炭化深度，

investigators can build up an image of which areas started burning first.

调查人员可以构建出一幅图像，显示哪些区域最先开始燃烧。

This doesn't give a definitive result,

这并不能给出一个确切的结果，

but it can help lead them closer to a possible source.

但它可以帮助他们更接近可能的起火点。

But what happens when a fire defies all of these rules?

但是，当一场大火打破所有这些规律时，会发生什么呢？

In the London Underground fire,

在伦敦地铁火灾中，

eyewitnesses reported the fire behaving in strange ways.

目击者报告说火势表现得很奇怪。

It wasn't burning upwards,

它不是向上燃烧，

but at an angle,

而是呈一个角度，

perfectly horizontal to the escalator.

与自动扶梯完全平行地燃烧。

This baffled the investigators for months until they tried recreating the fire on one of the most powerful supercomputers around,

这让调查人员困惑了几个月，直到他们尝试在当时最强大的超级计算机之一上重现火灾场景，

Odoo.

那就是Odoo。

Just kidding. 語氣意圖

开个玩笑。

Odoo is actually an all-in-one business management software

Odoo实际上是一款多合一的商业管理软件，

that gives entrepreneurs access to more than 45 apps to simplify the daily management of their business.

它让企业家可以使用超过45个应用程序来简化他们企业的日常管理。

One of my favorites is the invoicing app.

我最喜欢的之一是开票应用。

It's hands-down the quickest and easiest way to make invoices. 習語

这毫无疑问是制作发票最快、最简单的方式。

Simply select one of your existing customers

只需选择你现有的一个客户，

and it automatically fills out their information.

它就会自动填入他们的信息。

Then add your products and services,

然后添加你的产品和服务、

quantities, price, billing terms,

数量、价格、账单条款，

then send it off by email. 短語動詞

接着通过电子邮件发送出去。

Your customer can pay online by using the customer portal

你的客户可以通过客户门户网站在线支付，

and choosing their preferred payment method.

并选择他们偏好的支付方式。

With Odoo,

有了Odoo，

you can track invoices in real-time by connecting your bank,

你可以通过连接你的银行来实时追踪发票，

so you'll always know who has paid you and who still owes you money.

这样你总能知道谁付了款，谁还欠你钱。

Perhaps the best part is that it isn't behind a paywall. 用詞

或许最好的一点是它没有任何付费墙阻挡。

You can use it for free for life with Odoo's first app offer,

你可以通过Odoo的首个应用优惠活动终身免费使用，

including unlimited hosting and support.

包含无限期的托管和支持。

To get started with Odoo,

想要开始使用Odoo，

check out the link in the description.

请点击描述中的链接。

The first Odoo application is free for life.

第一个Odoo应用是终身免费的。

After that,

在那之后，

as your business grows,

随着你业务的增长，

you can easily add more apps when you need them

你可以在需要时轻松添加更多应用，

and have access to all applications at an affordable subscription.

并以可负担的订阅费用使用所有应用程序。

Escalator fires on the London Underground weren't uncommon.

伦敦地铁的自动扶梯起火并不罕见。

In fact,

事实上，

in the 30 years before the King's Cross fire,

在国王十字车站火灾发生前30年里，

more than 400 had been reported.

已经报告了超过400起火灾。

Although smoking had been recently banned in underground stations,

尽管近期地铁站内已经禁止吸烟，

people regularly broke this rule

人们还是经常违反这项规定，

and would often light up just before getting on the escalator. 短語動詞

而且往往会在踏上自动扶梯前点上一根烟。

Matches and cigarettes would fall between the gaps,

火柴和香烟会掉进缝隙里，

igniting the escalator steps,

点燃自动扶梯的台阶，

which were still surprisingly made of wood in many underground stations.

当时许多地铁站里的台阶竟然还是木制的。

The thing is, 表達脈絡

问题在于，

these fires would almost always go out by themselves. 短語動詞

这些火往往都会自行熄灭。

So why did this one go from a small fire 語法

那么，为什么这一场火会在短短几秒内，

to an enormous inferno in just a matter of seconds?

从小火苗变成一场巨大的地狱之火呢？

When investigators opened up the other escalators in the station,

当调查人员打开车站内其他的自动扶梯时，

they noticed that a large amount of grease had built up. 短語動詞

他们注意到积聚了大量的油脂。

And according to staff,

据工作人员称，

this hadn't been cleaned in years.

这里已经很多年没有清理过了。

Normally,

通常情况下，

this grease on its own would be very hard to ignite. 用詞

仅仅这些油脂本身是很难点燃的。

But after years of accumulation,

但经过多年的积累，

the grease was full of dust,

这些油脂里吸满了灰尘、

fiber, and debris that had dropped through the gaps

从缝隙掉落的纤维和碎屑，

after years of operation.

这是经过多年运行积累下来的。

The investigators tested this grease on an open model of the escalators

调查人员在一个开放的自动扶梯模型上测试了这种油脂，

and found that it was very easy for lit matches to fall down the gaps,

发现点燃的火柴很容易掉进缝隙，

ignite the grease,

点燃油脂，

and start a small fire.

并引发小火。

But no matter what they did, 語法

但无论他们怎么做，

the fire would always burn vertically

火总是垂直燃烧，

and eventually put itself out.

最终自行熄灭。

There was still something missing.

显然还遗漏了什么。

One of the main theories was that the ceiling paint,

当时一个主要的理论是，天花板上的油漆，

which was 20 layers thick,

有20层之厚，

had absorbed the heat,

吸收了热量，

ignited, and caused the fire to spread up the escalator shaft.

发生起火，并导致火势沿着扶梯井蔓延向上。

But this went against the witness statements, 短語動詞

但这与目击者的陈述相悖，

which claimed that the fire never touched the ceiling at all

目击者称火焰根本没有接触到天花板，

and instead stuck to the escalator steps all the way to the top.

而是一直紧贴着自动扶梯台阶向上蔓延到了顶部。

To determine whether this was even possible or not, 語法

为了确定这是否真的可能，

a computer simulation was set up using the Cray-2 supercomputer,

他们使用Cray-2超级计算机建立了一个计算机模拟，

the only one that existed in the UK.

当时英国只有这一台 Cray-2。

This calculated the temperature and airflow of gas at various points

这台计算机计算了各个位置气体的温度和气流，

to simulate how the fire might have spread. 語法

以模拟火势可能蔓延的方式。

The result was astonishing.

结果令人震惊。

The simulation perfectly predicted that the flames and hot gases wouldn't travel upwards, 語法

模拟结果完美预测了火焰和高温气体不会向上方移动，

but instead hugged the entire length of the escalator steps.

而是紧贴着整个自动扶梯台阶的长度行进。

This completely defied normal fire behavior,

这完全违背了正常的火灾行为，

as you would expect the hot buoyant gases

因为你本以为那些高温且具备浮力的气体

to have a lot of upwards force.

会有很大的向上力量。

Here's what's happening.

实际情况是这样的。

Thanks to the trench-like shape of the escalator shaft and its 30-degree angle, 短語搭配

由于自动扶梯井呈现出沟槽状的形状以及它的30度倾角，

the flame couldn't spread outwards,

火焰无法向外蔓延，

and so the heat had to flow in the direction of the trench.

因此热量只能顺着沟槽的方向流动。

At first,

起初，

some of the flames did escape upwards through the gaps, 語法

确实有一些火焰从缝隙中向上逃逸，

but the majority were forced to travel under the escalator steps. 語法

但大部分都被迫在自动扶梯台阶下方行进。

As this stream of hot gas accelerated up the escalator shaft,

随着这股热气流在扶梯井中向上加速，

its pressure dropped,

其压力下降，

creating a difference in pressure above and below the steps.

在台阶的上方和下方之间形成了压力差。

This gradually pushed the fire over

这逐渐将火焰推倒，

until it started sticking to the underside of the steps.

直到它开始紧贴在台阶的下侧。

The hotter it burned, 語法

它燃烧得越热，

the faster it traveled,

移动得就越快，

and the more it stuck to the steps.

它就越紧贴着台阶。

To witnesses,

在目击者看来，

all they could see was a rather small insignificant fire halfway up the escalator. 語法

他们能看到的只是自动扶梯走了一半处那团相对较小、不起眼的火苗。

But beneath the steps,

但在台阶之下，

the hot gases were heating the entire length of the wooden escalator

高温气体正在把整条木制自动扶梯

to temperatures well above 500°.

加热到远超500度的温度。

Those hot gases were then funneling into the ticket hall 用詞

然后这些高温气体顺着通道涌入售票大厅，

and filling up the void above the false ceiling.

并填满了假天花板上方的空隙。

What happened next turned the small fire into a disaster.

接下来发生的事情将这场小火变成了一场灾难。

When materials reach a certain temperature,

当材料达到一定温度时，

they ignite automatically,

它们会自动起火，

causing the fire to spread almost instantly.

导致火势几乎瞬间蔓延。

This is known as a flashover. 用詞

这就是所谓的轰燃。

Eventually,

最终，

the escalator and hot gases reached this temperature,

自动扶梯和高温气体达到了这个温度，

and in an instant,

在瞬间，

everything ignited.

一切都被点燃了。

This sent a fireball rushing up the escalator and into the ticket hall,

这导致一个火球冲上自动扶梯进入售票大厅，

igniting every surface and filling the place with fire and smoke.

点燃了所有表面，让整个地方充满了火焰和浓烟。

The computer simulation had shown this exact effect perfectly,

计算机模拟完美展示了这确切的效应，

but it wasn't fully believed until the investigators performed real tests

但直到调查人员进行真实的测试之前，它还没有被完全相信，

on a scale model of the escalator shaft.

该测试是在自动扶梯井的比例模型上进行的。

At first,

起初，

the fire burned upwards,

火焰是向上燃烧的，

but after just a few minutes,

但仅仅过了几分钟后，

it started lying down and hugging the floor of the escalator. 習語

它就开始伏低，并紧贴着自动扶梯的地板燃烧。

This brand new discovery was named the trench effect, 用詞

这项全新的发现被命名为“沟槽效应”，

and it led to a bunch of new safety improvements.

它促成了一系列新的安全改进措施。

All the wooden escalators were replaced,

所有的木制自动扶梯都被替换了，

and heat detectors were added beneath escalators with automatic sprinkler systems.

并在自动扶梯下方增设了热探测器和自动喷水灭火系统。

Thanks for watching,

感谢观看，

and I'll see you in the next video.

我们下期视频再见。