Effects of EGR rate on performance and emissions of a diesel power generator fueled by B7

This paper analyses the impacts of the application of an exhaust gas recirculation (EGR) system on the performance and emissions of a stationary, direct-injection diesel engine operating with diesel oil containing 7% biodiesel (B7). Experiments were carried out in a 49-kW diesel power generator with the adapted EGR system, and engine performance and emissions were evaluated for different load and EGR settings. The results were compared with the engine operating with its original configuration without the EGR system, and revealed a reduction of peak cylinder pressure and fuel conversion efficiency, mainly at high engine loads. The use of EGR caused opposite effects on carbon dioxide (CO2), carbon monoxide (CO) and total hydrocarbons (THC) emissions, depending on load and EGR rate, showing an increase in most situations. The application of EGR consistently reduced oxides of nitrogen (NOX) emissions, reaching a maximum reduction close to 30%. In general, the use of EGR increased CO2, CO and THC emissions at high loads. The use of 7.5% EGR was found to be at an adequate rate to simultaneously reduce CO, THC and NOX emissions at low and moderate loads, without major penalties on CO2 emissions and engine performance

Resource allocation in underpro-visioned multioverlay peer-to-peer live video sharing services.

International audienceMultioverlay peer-to-peer live video streaming systems face the problem of finding a suitable peer upload bandwidth allocation among concurrent overlays. So far, no efficient solution has been proposed for the important case where the overall system is underprovisioned, that is, when peers do not have enough upload bandwidth to ensure video distribution at full quality. We design various objective functions for this upload bandwidth allocation problem and show how optimal solutions can be computed using a bipartite flow network. Simulation results show that our solutions improve on existing algorithms in terms of video quality

Investigation of the effect of exhaust particles on ocular blood flow in highway toll collectors using color Doppler ultrasonography

BILGIN, CAHIT/0000-0003-2213-5881WOS: 000245792000018PubMed: 17354145Purpose: To investigate the effect of exhaust particles on orbital blood flow velocity of the ophthalmic artery, central retinal artery, and posterior ciliary artery by color Doppler ultrasonography in highway toll collectors. Material and Methods: Color Doppler imaging was used to measure the peak-systolic and end-diastolic flow velocities and resistivity indices of the ophthalmic artery, central retinal artery, and posterior ciliary artery in 20 toll collectors and 20 controls. Results: Both the peak-systolic and the end-diastolic flow velocities were decreased in the ophthalmic artery, central retinal artery, and posterior ciliary artery, and the resistivity index was increased in the central retinal artery in toll collectors when compared with control groups. Results were considered statistically significant if P < 0.05. Conclusion: It was determined that the effect of exhaust particles reduced ocular blood flow velocity in toll collectors as measured by color duplex Doppler ultrasonography