经济学人下载:发烧预测(1)

Sticking a thermometer into an armpit, mouth, ear or other body cavity is the most accurate way to take someone's temperature.
将体温计插入腋窝、口腔、耳朵或其他体腔是测量体温最准确的方法。

Understandably, though, this cannot be done at airports or checkpoints set up elsewhere
然而，可以理解的是，这在机场或其他地方设立的检查站是做不到的，

to screen the masses for feverish victims of covid-19.
这些地方是为了筛查人群中是否有covid-19的发烧患者。

So, in a bid to detect the warmth produced by a fever without touching any bodies, officials have opted for alternatives.
因此，为了在不接触任何身体部位的情况下检测发烧产生的热量，各国选择了其他办法。

The hand-held "thermometer guns" now ubiquitous in China, among other places, are one option.
现在在中国和其他地方随处可见的手持“温度计枪”是一种选择。

These instruments, known technically as spot pyrometers, use a device called a bolometer to estimate an object's temperature.
这些仪器，技术上称为现场高温计，使用一种称为辐射热测定器的设备来估计一个物体的温度。

A bolometer's electrical resistance depends on how hot it is.
辐射热测定器的电阻取决于它的热度。

That, in turn, depends on the amount of infrared radiation falling on it from whatever it is pointing at.
反过来，这又取决于从它指向的任何地方落在它身上的红外辐射的数量。

Spot pyrometers are used widely in industry to check equipment for signs of overheating,
现场高温计在工业中广泛用于检查设备过热迹象，

but the infrared signals they rely on can be muddled by dust, moisture, smoke, a change in ambient temperature,
但是它们所依赖的红外信号可能会被灰尘、湿气、烟雾、环境温度的变化、

a smudge on the device's lens or even by radio signals.
设备镜头上的污迹甚至无线电信号所干扰。

Beyond all this, an official checking a stream of foreheads may, for reasons of personal safety,
除此之外，出于个人安全的考虑，测量额头体温的检察人员

be reluctant to hold the gun close enough to obtain an accurate reading.
可能不愿意拿着测温枪近距离读取准确的读数。

An alternative technology, the thermal camera, is costlier. But it can operate from farther away.
另一种替代技术，即热感摄像机，成本更高。但它可以在更远的地方运行。

Instead of a single bolometer, it has an array of them.
它不是单一的辐射热测定器，而是大量的辐射热测定器。

These form the pixels which generate the camera's image, thus building up a heat map of whatever that camera is looking at.
这些像素形成了相机的图像，从而将相机看到的画面形成一个热图。

One popular thermal camera, the A320, made by FLIR Systems, an American firm,
一种受欢迎的热感摄像机是A320，由美国FLIR公司制造，

can detect variations in radiation which correspond to temperature differences within an image of just 0.02°C.
该设备可以在在0.02°C的图像中，探测到与温差相对应的辐射变化。

But this merely shows whether one part of the object being examined is warmer or cooler than another.
但这仅仅表明了被检测物体的一部分比另一部分更热或更冷。

When measuring the object's actual temperature, the A320 is accurate only to about 2°C, says Giovanni Scaglia, FLIR's head of sales in Italy.
当测量物体的实际温度时，A320的精确度只有2摄氏度左右，FLIR在意大利的销售主管Giovanni Scaglia说到。

For a single reading, this is enough to mistake normal body temperature for a raging fever.
仅仅一个读数，就足以将正常体温误认为是高烧。

In practice, however, the camera's software looks for deviations from the average temperature of passers-by.
但在实际操作中，相机的软件会寻找路人平均温度的偏差。

Those noticeably hotter than their fellows can then be selected for closer investigation.
那些体温明显比他们同伴更高的人可以被挑选出来进行更深入的调查。