## 3 Active Disaster Response System (ADRS)
### Active Disaster Response System
#### 3.3.2 Emergency Message Board  
According to the historical records and statistics [30,31], massive earthquakes usually cause power outages lasting three hours or longer. During this time, connections to the outside of the building, including cell phone connections, may be disrupted. Therefore, ADRS utilizes the embedded controllers to maintain a temporary network, as stated earlier. In this work, Tibbo EM1000-TEV embedded boards were used to build up a prototype of a one-hop network. Table 2 shows the hardware specification of the Tibbo EM1000-TEV device. The core of the board is a RISC (Reduced Instruction Set Computing) chip with 88 MHz. It supports both Wi-Fi and Ethernet interfaces. It also has a 2-KB EEPROM (Electrically Erasable Programmable Read Only Memory) to store important information. Figure 7 shows a use scenario of the emergency board. There \begin{table}
\begin{tabular}{l l} \hline Tibbo & EM1000-TEV Specification \\ \hline
1. & 88 MHz RISC (Reduced Instruction Set Computing) chip (T1000) \\
2. & 10/100 BaseT auto-MDIX Ethernet \\
3. & Provide Wi-Fi interface (GA1000 module) \\
4. & Four high speed serial port (CMOS) \\
5. & 1024-KB flash memory for firmware and application \\
6. & 2-KB EEPROM (Electrically Erasable Programmable Read Only Memory) for parameters and data storage \\ \hline \end{tabular}
\end{table} 
Table 2: Tibbo EM1000-TEV hardware specification. Figure 6: The flow of parsing CAP messages and controlling devices. are several embedded boards inside a building. Each of them has network capacity. When the Internet is disrupted, people can be connected to these embedded boards directly and post messages on emergency events. The events are stored in the embedded boards. As Figure 7 shows, people or victims may be divided into several groups, depending on their locations. When relief workers come to the threatened area, they can get emergency reports from these embedded boards and plan rescue actions. Figure 8 shows the two kinds of user interfaces of the emergency message service: the web interface and the Android app interface. Victims can use one of the interfaces to post emergency messages on the embedded boards. Since embedded boards are usually powered by battery, it is desirable to reduce possible communication to save energy. As a result, for victims, it is necessary to properly select an embedded board to store their emergency messages. In order to address this issue, a heuristic algorithm, called Algorithm 1, was designed to select an embedded board to store emergency messages. For each victim \(i\), \(m_{i}\) denotes the size of emergency message needed to be posted to a Tibbo embedded board. Furthermore, \(e_{i}\) is the approximated energy consumption of receiving the emergency message. In the beginning, the victim searches embedded boards nearby and queries the remaining energy capacity and memory capacity of each embedded  
Figure 8: Emergency message interface: (**a**) web interface; (**b**) Android interface. Figure 7: Usage scenario of emergency message board. board. Let \(k\) denote the number of Tibbo boards nearby victim \(i\). The remaining energy capacity of the \(k\)-th Tibbo is \(E_{k}\) and its remaining memory capacity is \(M_{k}\). Algorithm 1 shows the method to post emergency messages. The post function is used to select a suitable Tiboo board to post the emergency message. The goal is to reduce energy consumption as much as possible when posting emergency messages. For this, Algorithm 1 examines all Tiboo boards near the victim \(i\) (Lines 3 to 9). If the remaining energy capacity of the Tiboo board is larger than \(e_{i}\) and its remaining memory capacity is larger than \(m_{i}\), it will be selected as a candidate. The post function picks up one embedded board among the candidates with the highest energy as the result (Lines 5 and 7). After selecting the target embedded board, the emergency message is posted to the board. The advantage of Algorithm 1 is the ease of implementation, and it can be integrated with exit signs and emergency lights.