## 3 Classification Based on Function
### Life-Detection Sensors
\begin{table}
\begin{tabular}{c c c c} \hline
**Main Categories** & **Sub Categories** & **Benefits** & **Constraints** \\ \hline \multirow{6}{*}{Earthquake early warning} & \multirow{4}{*}{Mechanical} & Rapid notification and accuracy. & Limited coverage \\  & & Mechanical sensors to detect the initial & False alarms \\  & & shock-waves of an earthquake and accurately & Time delay \\  & & determine its location, magnitude, and expected & High cost \\  & & ground shaking intensity. & \\ \cline{2-4}  & \multirow{4}{*}{Electrochemical} & Quick, portable, and low cost. & \\  & & Detects multiple gases simultaneously, which can & Limited range \\  & & provide additional information with a high & Limited detection capability \\  & & signal/noise ratio about the type and severity of & False alarms \\  & & an earthquake. & \\ \hline \multirow{6}{*}{Radon} & \multirow{4}{*}{Radon} & Low-cost and long-term monitoring. & Limited range \\  & & Sensitive to precursory events. & Slow response time \\  & & Radon sensors do not require any external power & False alarms \\  & & source or maintenance once installed. & Limited applicability to certain \\  & & & geological settings \\ \hline \multirow{6}{*}{Shortwave radio} & \multirow{4}{*}{Shortwave radio} & Wide coverage, low cost, and reliable. & Limited bandwidth \\  & & Shortwave radio does not rely on any centralized & Vulnerable to interference \\  & & infrastructure or service provider, which means it & Reliance on specialized equipment \\  & & can operate independently, even when other & Communication delay \\  & & systems are down. & \\ \cline{2-4}  & \multirow{4}{*}{Digital trucking} & Real-time updates and increased efficiency. & \\  & & Digital trucking can improve coordination among & Dependence on technology \\  & & emergency responders by providing a centralized & Limited coverage \\  & & platform for tracking the location and movement & High cost \\ \cline{2-4}  & \multirow{4}{*}{Two-way radio systems} & Immediate communication and long range. & Limited coverage area \\  & & Two-way radios are more reliable than cellular & Interference by other electronic \\  & & phones during earthquakes, as they do not rely on & devices \\  & & cellular networks that may become congested or & Complex setup \\ \hline \multirow{6}{*}{Microwave communications} & \multirow{4}{*}{High-speed and long-distance coverage. } & \multirow{4}{*}{Vulnerability to weather conditions} \\  & & Microwaves are less prone to interference from & such as heavy rain \\  & & natural obstacles such as mountains or valleys, & Susceptibility to interference \\  & & making them more reliable for transmitting & \\ \cline{1-1}  & & messages during an earthquake. & \\ \hline \multirow{6}{*}{Radio frequency identification devices (RFID)} & Real-time monitoring and scalability. & Limited range \\ \cline{1-1}  & & RFID allows for automatic identification and & Security concerns \\ \cline{1-1}  & & tracking of objects, which can save time and effort & High cost \\ \cline{1-1}  & & during emergency response operations. & \\ \hline \end{tabular}
\end{table} 
Table 2: _Cont._a light source connected by a flexible data transmission line to penetrate the aperture of a collapsed building and avoid moving it. One form of life-detection technology, also known as a Snake Eye (SE) life detector [15], can determine the position and living condition of trapped individuals while avoiding secondary collapse. Infrared detection technology uses the infrared characteristics of the human body to distinguish a human body from the surrounding environment. Currently, Unmanned Aerial Vehicles (UAVs) are becoming popular for collecting video information, audio information, infrared information, and other information at the scene of disaster areas synchronously. The collected data are further classified by operating software to analyze the images and audio in the video and determine the location and living state of personnel [16; 17; 18].