Information System Design,
April - June 2013
Earthquakes are among the most devastating events on earth. Because China is situated between two major earthquake belts — the "Pacific Ring of Fire and "Eurasia Earthquake Zone", China's seismic activities are quite frequent. And schools, as a densely populated area, highly tend to become the center of hazard because of the low-age students‘ limited knowledge and competence of first aid and self-aid, as well as the high density of school buildings. Take the 5.12 Wenchuan Earthquake for example. The disaster killed 68624 in Sichuan Province, within which 6376 were low-age students, who were having classes in schools when the earthquake happened.
This is a course project I did in college. The purpose is to increase the survivability in schools under the situation of earthquakes.
Main Reasons for Death Or Injure
Building collapse; hit by falling objects; stampede accidents or jumping from buildings during evacuation procedure; aftershocks, mud-rock flows, landslides and quake lakes that happened after earthquake. These are the main reasons for death or injure in earthquake( in Chinese earthquake-prone zone, which are normally mountainous area). Schools usually have high teaching buildings with narrow stairs. Besides building collapse, stampede accidents is a significant reason for death and injure in schools.
Different age groups have disparate mental states in earthquakes. Some people are flustered and tend to gush out the classroom and escape in a panic. This situation mainly exists in low-age students. Some underestimate the severity of earthquakes and just stay on their spots after the first shake. This situation mainly exists in elder students and adults.
Seismic Wave Feature
There are two kinds of seismic wave arriving at the seismograph station when an earthquake happens, the primary waves and secondary waves.
Primary waves are compressional waves that are longitudinal in nature, which is relatively less devastating to architectures. P waves are pressure waves that travel faster than other waves through the earth to arrive at seismograph stations firstly. Its typical speeds is 5500-7000 m/s in crust.
Secondary waves are shear waves that are transverse in nature, and therefore much more devastating to buildings. Following an earthquake event, S-waves arrive at seismograph stations after the faster-moving P-waves. S-waves are slower than P-waves, and speeds are typically around 60% of that of P-waves.
Therefore, unless the seismography station is very close to the epicenter, there will be a stable period of seconds to tens of seconds between the arrival of P-waves and S-waves, which should be well used to evacuate or look for shelters before the S-waves arrive.
#2. Technology Research
Mobile communication, satellite phone and microwave communication are three technologies that are commonly applied in current communication products for emergency. This research is to evaluate the applicability of these technologies for after-earthquake products.
It depends on the transatlantic cable and mobile base station system. Once the system is damaged, the mobile communication becomes unavailable. Considering the earthquakes are very likely to damage the cable and mobile base, the mobile communication is not an ideal method.
It depends on the satellite communications system. It is available as long as the device is within the coverage area (which is normally a large area) of satellite signal. However, it is much more expensive than other communication device and the signal will be unstable if interfered by large architectures or mountains. For reasons above, the satellite phone is not appropriate for large use.
Microwave is a kind of radio waves. It has very wide frequency range, and in other words, it has large capability. Its communication distance is only tens of kilometers, but it is still useful for limited areas like schools.
When an earthquake happens, people should evacuate calmly and orderly to safe area and wait for rescue. To lead to this procedure, I want to design an information communication system, which could collect information of the school building condition and victim situation as well as the incoming aftershakes. It could also provide information to victims and rescuers.
After the earthquake, the victims need reliable self-aid guidance information as well as a accurate understanding of the after-earthquake environment to evacuate and survive, while the rescuer need timely and valid information of the affected area to prepare for a rescue plan. Affected by the seismic waves, the normal information communication methods would fail to some degrees. Therefore, direct and fluent communication is not available in a short span of time. This project is mean to design a phased and multi-step after-earthquake information communication system for schools, based on disparate information technologies, in order to increase the survivability of students.
To design an organized information system for after-earthquake situation with the available information technologies in the former research, I designed three devices.
This device is carried and operated by the security directors of the school. It is able to aggregate the information of the disaster area and transmit it to the government rescuers and also receive guidance from them. It is also a conductor center for individual device. It is chargeable and portable. When several general control devices work together, they can accurately detect the locations of students.
It has emergency power supply, emergency lighting, talkback to the general controls and emergency supply kit storage. It provides route guidance to evacuating students.
It is a small-scale microwave transponder. It is able to automatically alert to the general controls, broadcast earthquake early-warning. It is manual-chargeable and has emergency lighting.
The individual equipment receives earthquake early-warning, and automatically transmit signal to the general control, provide information for rescuer to locate the positions of students. The relay device is installed with camera. It collects building information from camera monitor and student report via talkback, and broadcast accurate route guidance received from the general control. The general control is able to detect the locations of students through an analysis of the signal transmitted from the individual equipment, and then provide an immediate and efficient direction to students. It can also provide information to the rescuers to help them make rescue plan.