Design of a real-time tyre pressure monitoring system for LMVs
The tyre pressure is not adequately maintained by the majority of automobile drivers, even though they drop more than one pounds per square inch (PSI) of air pressure a month. The National Highway Traffic Safety Administration (NHTSA) statistics show that low-tyre pressure-related crashes cause 660 fatalities and 33,000 injuries every year. At present, the tyre pressure is monitor from differences in the rotational speed and deduces the pressure differences between tyres. The anti-lock braking system (ABS) sensors can be used to measure it. The proposed system employs advanced integration techniques to provide a TPMS solution that provides real-time tyre pressure monitoring (both stationary and movement condition of the vehicle) and alerts the driver about improperly inflated tyres. The unit includes a pressure sensor, microcontroller, RF transmitter and long life battery. The TPMS unit communicates by an on- board RF receiver and displays real-time tyre pressure of all tyres. Tyre pressure is monitored in the stationary condition of the vehicle at present. This project can be extended to read pressure values in the moving condition of vehicle and generate the alert signal to the driver when the threshold value is reached. The entire design is envisaged to be developed as a small and compact unit that can be easily fitted onto a tyre.
Compact low profile UHF switched-beam antenna for advanced tyre monitoring systems
Advanced tyre monitoring systems are based on small sensor units directly embedded into the tyre rubber. In contrast to conventional tyre monitoring systems, more data like vibration information and slip angle are collected at this exposed position, so vehicular safety systems can be further improved. Powering of and communication with these sensor units, could be done with UHF radio frequency identification technology. In this contribution we propose a novel compact switched-beam antenna suitable for UHF frequencies. When mounted below the body floor pan of a vehicle, its directivity of 6 dB and the possibility to switch the main beam direction in 90? steps enables selection of a specific tyre for communication. Finally, we present measurements of the assembled antenna performed in an anechoic chamber.
Comparative study of in vitro flow characteristics between a human aortic valve and a designed aortic valve and six corresponding types of prosthetic heart valves.
A model of a pulsatile cardiovascular system is described including an electronic control, a hydraulic driving unit, a volume storage, a peripheral resistance and measuring equipment. Six different artificial heart valves, a designed aortic valve (Aachen pockett valve II) and a human aortic valve have been tested in the outflow position of the pump. Three of them are presently being used in clinical applications. Measurements of pressure and volume flow have been obtained for different frequencies n, pump volumes Vp and time ratios between pressure and suction phase. From the experimental results a comparative evaluation was deducted for different working conditions. In comparison to natural human aortic valve (NK) large volume flow is verified by the Aachen pocket valve II (AT), the Gott-Dagget value (GD), the Starr-Edwards valve (SE) and the Lillehei-Kaster valve (LK). The Gott-Daggett valve has the smallest back flow volume. The Smeloff-Cutter and in particular the Wada-Cutter valve have the largest regurgitation. This is to be expected since the Cutter valves are purposely so designed that they do not close tightly in order to avoid blood sedimentation. The human aortic valve, the Gott-Daggett valve and the Aachen pocket valve demonstrate the most favourable opening-closing characteristics. The human aortic valve achieves a negligible pressure loss, followed by the Björk-Shiley and the Lillehei-Kaster valve.