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This study investigates pollutant emissions and fuel consumption of six Euro VI hybrid-diesel public transport buses operating on different scheduled routes in a metropolitan urban road network. Portable emission measurement systems (PEMS) are used in measurements and results are compared to those obtained from a paired number of Euro V conventional buses of the same body type used as control over the same routes. The selected routes vary from urban to highway driving and the experimentation was conducted over the first half of 2015. The available emissions data correspond to a wide range of driving, operating, and ambient conditions. Fuel consumption, distance- and energy-based emission levels are derived and presented in a comparative manner. The effect of different factors, including speed, ambient temperature, and road grade on fuel consumption and emissions performance is investigated. Mean fuel consumption of hybrid buses was found 6.1% lower than conventional ones, from 20% lower up to 16% higher, over six routes tested in total. The mean route difference between the two technologies was not statistically significant. Air conditioning decreased consumption benefits of the hybrid buses. Decrease of the mean route speed from 15 km h−1 tο 8 km h−1 increased the hybrid buses consumption by 63%. Nitrogen oxides (NOx) emissions of the Euro VI hybrid buses were 93 ± 5% lower than conventional Euro V ones. Nitrous oxide (N2O) emissions from hybrid Euro VI buses made up 5.9% of total greenhouse gas emissions and largely offset carbon dioxide (CO2) benefits. The results suggest that hybrid urban buses need to be assessed under realistic operation and environmental conditions to assess their true environmental and fuel consumption benefits.

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In this paper Space-Time Block Coding (STBC) is examined in powerline and satellite communications, comparing the gains that this coding-modulation technique provides to these communications systems. The powerline environment is assumed to be a frequency-selective, multipath fading environment with Additive White Class A Noise (AWCN), which is used to model the actual powerline noise characteristics. The satellite channel for urban area, modeled as a combination of Rayleigh and lognormal processes with the presence of Additive White Gaussian Noise (AWGN) is also studied. System efficiency is enhanced by the application of Orthogonal Frequency Division Multiplexing (OFDM), convolutional coding and block interleaving and the performance of different Phase Shift Keying (PSK) modulation schemes under the imposed channel conditions is investigated. The performance of the system is assessed by the commonly used Bit Error Rate (BER) vs. Signal to Noise Ratio (SNR) diagrams and there is also a comparison regarding the throughput efficiency among the examined systems. As stated in the results section, STBC can be used in powerline and satellite communications providing remarkable results, comparable to those in terrestrial wireless communications where STBC is nowadays a rather mature technique.