[原创]09/01/02 first GMAT in Hong Kong 700 新鲜JJ

蚊子漫步

wiki了一下，只搜到下面的文章，请LZ看看。

Gas leak detection is the detection of gas leaks with apparatus like catalytic/infrared point sensors and IR open path sensors, more recent detection methods include Ultrasonic Gas Leak Detectors.

In order to detect gas leaks with traditional methods, the gas itself must either be in close proximity to the detector or within a pre-defined area. Outdoor environmental conditions such as changing wind directions and quick dispersion of a potential gas cloud, which can be found e.g. on an offshore platform, can result in undetected gas leaks, leading to extremely dangerous situations.

An alternative to these traditional detection methods is ultrasonic gas leak detectors. This detection method often use a microphone technology; which detect outdoor leaks by sensing the distinct high frequency ultrasound emitted by all high pressure gas leaks, meaning that the gas does not have to reach the sensor – just the sound of the gas leak.

Basic detection can be accomplished using semiconductor gas detection. The semiconductor sensor method can be used for a variety of gases including combustible, toxic, and refrigerant gases. Semiconductor gas detectors are very economical and have a lifespan of 5 to 8 years however they are prone to cross sensitivity.

Gas released from any environment into another may undergo chemical changes. Electrochemical gas sensors are used where gases can undergo an oxidation/reduction reaction. This method is very selective. Electrochemical gas sensors can measure at only a few particles per billion. Unfortunately the sensors themselves are subject to corrosive elements and may last only 1-2 years before a replacement must be deployed.

[此贴子已经被作者于2009-1-3 10:40:30编辑过]

少林考僧

请问LZ MM，是不是下面类似这个内容啊？

不过只找到2句话，还望MM 补充，非常感谢！

地下管道经常漏油。
一种结合软硬件的设备EMAT可以勘测漏油的地点。下面是E的工作原理。(出现了Aà第二段后面提到).另一种设备结合人工也可以勘测漏油的地点。两种结合效果好。

GMATNL

以下是引用flutemama在2009-1-3 10:32:00的发言：
a number of  amount of  seems right http://www.google.com/search?hl=en&q=%22a+number+of++amount+of%22  seems lots of people using it

强大的Google只能搜出十几条记录的，一般都不是正确用法

y_a

请问楼主都看了那些JJ阿？

有没有链接可以告我一下？

kaffeel

以下是引用蚊子漫步在2009-1-3 10:40:00的发言：

wiki了一下，只搜到下面的文章，请LZ看看。

Gas leak detection is the detection of gas leaks with apparatus like catalytic/infrared point sensors and IR open path sensors, more recent detection methods include Ultrasonic Gas Leak Detectors.

In order to detect gas leaks with traditional methods, the gas itself must either be in close proximity to the detector or within a pre-defined area. Outdoor environmental conditions such as changing wind directions and quick dispersion of a potential gas cloud, which can be found e.g. on an offshore platform, can result in undetected gas leaks, leading to extremely dangerous situations.

An alternative to these traditional detection methods is ultrasonic gas leak detectors. This detection method often use a microphone technology; which detect outdoor leaks by sensing the distinct high frequency ultrasound emitted by all high pressure gas leaks, meaning that the gas does not have to reach the sensor – just the sound of the gas leak.

Basic detection can be accomplished using semiconductor gas detection. The semiconductor sensor method can be used for a variety of gases including combustible, toxic, and refrigerant gases. Semiconductor gas detectors are very economical and have a lifespan of 5 to 8 years however they are prone to cross sensitivity.

Gas released from any environment into another may undergo chemical changes. Electrochemical gas sensors are used where gases can undergo an oxidation/reduction reaction. This method is very selective. Electrochemical gas sensors can measure at only a few particles per billion. Unfortunately the sensors themselves are subject to corrosive elements and may last only 1-2 years before a replacement must be deployed.

这个看起来不太像，我也补充点类似的背景知识在JJ里面。你用上面的关键字，在google里面search一下吧