Impurity is one of the main factors that affect the measurement accuracy of an ultrasonic heat meter. To study the effects of different impurity species and concentrations on the accuracy of heat meters, flow tests we...Impurity is one of the main factors that affect the measurement accuracy of an ultrasonic heat meter. To study the effects of different impurity species and concentrations on the accuracy of heat meters, flow tests were carried out for the suspending of calcium carbonate and yellow mud. By analyzing the attenuation characteristics of the ultrasound amplitude in different impurity concentrations and species, the influence of the impurities on the heat meter measurement accuracy is evaluated. In order to avoid the inaccuracy caused by the sediment of the reflective bottom surface, a vortex generator is put ahead of the reflective surface. According to the test, the calcium carbonate suspension with a mass concentration of 1%, which influences the heat meter accuracy severely, is used as the flow media. The influence of the vortex generator on the calcium carbonate suspension flow field in the heat meter body is studied with numerical simulations. The results of this paper provide some theoretical guide on improving the heat meter measurement accuracy when the water contains impurities.展开更多
We experimentally demonstrate a high-speed phosphorescent white light emitting diode （LED） visible light communication （VLC） system without utilizing an optical blue filter. Here, the white light response is equal...We experimentally demonstrate a high-speed phosphorescent white light emitting diode （LED） visible light communication （VLC） system without utilizing an optical blue filter. Here, the white light response is equalized by using the proposed analog equalizers. The 3 dB bandwidth of the VLC link could be extended from 3 to 132 MHz, which allows 330 Mbit/s non-return-to-zero on-off keying （NRZ-OOK） data transmission with a bit error ratio （BER） of 7,2 × 10^-10 and 672 Mbit/s 64-quadrature amplitude modulation （64-QAM） data transmission with a BER of 3.2 × 10^-3. These resultant BERs are less than the forward error correction （FEC） limit of 3.8× 10^-3. The VLC link distance is 1 m using a single 1 W LED. The transmitter and receiver modules are integrated to a compact size. Furthermore, the relationships between the signal performance and illumination level or optical power are investigated and analyzed.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51276102)the Natural Science Foundation of Shandong Province(Grant No.ZR2014EEM015,ZR2011EEM011.)
文摘Impurity is one of the main factors that affect the measurement accuracy of an ultrasonic heat meter. To study the effects of different impurity species and concentrations on the accuracy of heat meters, flow tests were carried out for the suspending of calcium carbonate and yellow mud. By analyzing the attenuation characteristics of the ultrasound amplitude in different impurity concentrations and species, the influence of the impurities on the heat meter measurement accuracy is evaluated. In order to avoid the inaccuracy caused by the sediment of the reflective bottom surface, a vortex generator is put ahead of the reflective surface. According to the test, the calcium carbonate suspension with a mass concentration of 1%, which influences the heat meter accuracy severely, is used as the flow media. The influence of the vortex generator on the calcium carbonate suspension flow field in the heat meter body is studied with numerical simulations. The results of this paper provide some theoretical guide on improving the heat meter measurement accuracy when the water contains impurities.
基金supported by the National 973Program of China(No.2013CB329205)the National 863Program of China(Nos.2013AA013602,2013AA013603,2013AA03A104,and 2013AA031903)+1 种基金the National Natural Science Foundation of China(Nos.61036002 and61178051)the Beijing Municipal Science and Technology Project(No.Z141100001414004)
文摘We experimentally demonstrate a high-speed phosphorescent white light emitting diode （LED） visible light communication （VLC） system without utilizing an optical blue filter. Here, the white light response is equalized by using the proposed analog equalizers. The 3 dB bandwidth of the VLC link could be extended from 3 to 132 MHz, which allows 330 Mbit/s non-return-to-zero on-off keying （NRZ-OOK） data transmission with a bit error ratio （BER） of 7,2 × 10^-10 and 672 Mbit/s 64-quadrature amplitude modulation （64-QAM） data transmission with a BER of 3.2 × 10^-3. These resultant BERs are less than the forward error correction （FEC） limit of 3.8× 10^-3. The VLC link distance is 1 m using a single 1 W LED. The transmitter and receiver modules are integrated to a compact size. Furthermore, the relationships between the signal performance and illumination level or optical power are investigated and analyzed.
