Improvement of Temperature and Optical Power of an LED by Using Microfluidic Circulating System of Graphene Solution

Electric devices have evolved to become smaller, more multifunctional, and increasingly integrated. When the total volume of a device is reduced, insufficient heat dissipation may result in device failure. A microfluidic channel with a graphene solution may replace solid conductors for simultaneously supplying energy and dissipating heat in a light emitting diode (LED). In this study, an automated recycling system using a graphene solution was designed that reduces the necessity of manual operation. The optical power and temperature of an LED using this system was measured for an extended period and compared with the performance of a solid conductor. The temperature difference of the LED bottom using the solid and liquid conductors reached 25 °C. The optical power of the LED using the liquid conductor was higher than that of the solid conductor after 120 min of LED operation. When the flow rate was increased, the temperature difference of the LED bottom between initial and 480 min was lower, and the optical power of the LED was higher. This result was attributable to the higher temperature of the LED with the solid conductor. Moreover, the optical/electric power transfer rate of the liquid conductor was higher than that of the solid conductor after 120 min of LED operation, and the difference increased over time.

Railway Sign Power Line As Transmission Medium for Narrowband PLC

This work shows transmission parameters of specific power line, which is control cable used for supplying a railway sign. Two transmission parameters are considered, namely: attenuation and characteristic impedance, these two secondary parameters are calculated from primary parameters i.e. R, L and C. Primary parameters and their components were calculated if they depended on the frequency or were taken from producers notes. Analysis was done for the frequency in range from 50 kHz up to 100 kHz. Two types of cables were analysed, as extreme cases, first with the 1 mm2 solid conductors cable and second with the 1.5 mm2 19 strands conductors. Knowing the PLC modem transmission parameters together with the transmission parameters of the railway sign power line it is possible to calculate the capabilities of the communication system e. g. distance or maximum bit rate.