This paper proposes a surface acoustic wave (SAW) passive wireless sensor system for monitoring the temperature of the electric cord connectors. The low-loss sensor consists of a temperature-sensing high-Q SAW resonator, a small antenna and a matching circuit. The resonant frequency of the SAW sensor is varied with the temperature. While the interrogational signal is a sinusoidal burst, the response is a damped resonant signal. In order to detect the weak response signal, an ultra-high-sensitivity receiver with a low-noise amplifier, a programmable gain amplifier (PGA), a highprecision correlation detector, and an active 8th-order bandpass filter is designed. A method for decreasing coherent noise is used in transceiver system. To track precisely the resonant frequency of the sensor, a high-resolution hardware direct digital synthesis (DDS) signal source with a wide changeable frequency range (1MHz) is implemented. A smallsize prototype instrument is built. The maximum detecting distance of the sensor system is over 20 meter at a transmitting power of 24 dbm, and a temperature measurement resolution of 0.1 degree can be obtained.I.
Subway station fire can easily cause many calamities that lead to a large amount of social and public problems, because the smoke spread moves in the same direction as the personnel evacuation. Therefore, life safety issues caused by the subway station fire and relevant investigation should be comprehensively taken into account in the fire safety design in order to minimize the fire accident loss. Here previously reported fire accidents in the subway station are reviewed in detail and some research on the life safety of the subway station fire are presented, which could be helpful for the accident prevention and provide guidance to future study on the safety design in the subway station fire.
The geometric design of motorways in the mountainous area is the top priority of the interchange planning and design. Reasonable ramp geometric design can not only reduce the cost and difficulties of construction of the interchange, but also improve the driving conditions, ensure traffic safety and improve the comfort of driving. Based on the development of foreign geometric alignment design practice, this paper analyze the continuous travel performance of vehicles on mountainous interchange ramps, and then proposes a highway geometric elements design method based on operating speed for practitioners to predict operating speed on ramps. The method will allow the auditors and the designers to proceed operating speed prediction for varied vehicle types for mountainous interchange ramps, which is also expected to give the auditors a good way to evaluate the consistency between driver’s expectation and the geometric design of the ramps.
The fire accident is a substantial risk in the subway due to the complexity of the underground construction confined space, which can cause a large number of human fatalities. Therefore, some effort should be made to promote the public security in subway fire accidents. Among of them, the establishment of emergency evacuation plan is very important in fire safety design and should be paid enough attention because it can provide beneficial help to life safety. The evacuation strategy including the evacuation route and evacuation safety zone are detailedly discussed in this paper, which lays the foundation for future studies of safe evacuation in the subway fire accidents.
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