Investigation of the effect of DC electric field on a small ethanol diffusion flame

A small ethanol diffusion flame exhibited interesting characteristics under a DC electric field. A numerical study has been performed to elucidate the experimental observations. The flow velocity, chemical reaction rate, species mass fraction distribution, flame deformation and temperature of the flame in the applied DC electric field were considered. The results show that the applied electric field changes the flame characteristics mainly due to the body forces acting on charged particles in the electric field. The charged particles are accelerated in the applied electric field, resulting in the flow velocity increase. The effects on the species distribution are also discussed. It was found that the applied electric field promotes the fuel/oxidizer mixing, thereby enhancing the combustion process and leading to higher flame temperature. Flame becomes shorter with applied electric field and its deformation is related to the electric field strength. The study showed that it is feasible to use an applied DC electric field to control combustion and flame in small-scale

Effects of direct-current electric fields on flame shape and combustion characteristics of ethanol in small scale

The aim of this work is to investigate the effects of direct-current electric fields on the behavior of the small-scale diffusion ethanol flame. The flow rate of liquid ethanol, the flame temperatures, and the flame shapes were measured. The results showed that the stable working ranges of a small-scale combustor became narrower under the direct-current electric field. The main reason was that the evaporation velocity of liquid ethanol limited by great heat loss effect cannot keep up with the increasing of combustion velocity by the ionic wind effect. The movements of those charged particles in flame enhanced the combustion process, resulting in higher flame temperatures under positive or negative direct-current electric field. The flame heights decreased with increasing applied voltages, due to the ionic wind effect increasing the flame temperature and the diffusivity. The flame voltage–current characteristic was also examined. Three regions can be divided: the subsaturation region, the saturation region, and the supersaturation region. Finally, the ratios of electric active power to actual burning thermal power of ethanol flame were calculated. It can be inferred that using the external direct-current electric field with little power consumption to control combustion and flame is a feasible method

Exploring a Novel Reservoir Impoundment Operation Framework for Facilitating Hydropower Sustainability

Reservoir impoundment operation has far-reaching effects on the synergies of hydropower output, floodwater utilization, and carbon fluxes, but flood risk is significantly increasing, which is especially true when shifting to earlier impoundment timings and lifting reservoir water levels. This study proposed a novel reservoir impoundment operation framework driven by flood prevention, hydropower production, floodwater utilization, and carbon emission management. The Three Gorges Reservoir in the Yangtze River was selected as a case study. The results demonstrated that flood prevention safety could be guaranteed with the initial impoundment timings on and after the first of September. The best scheme of reservoir impoundment operation could efficiently boost synergistic benefits by enhancing 2.98 billion kW·h (8.8%) hydropower output and 6.4% water impoundment rate and decreasing greenhouse gas (GHG) fluxes and carbon budget by 28.15 GgCO2e/yr (4.6%) and 0.44 (23.1%), respectively, compared with the standard operation policy. This study can not only provide scientific and technical support for reservoir impoundment operations, benefiting water–carbon synergies, but can also suggest policymakers with various favorable advancing impoundment timing and lifting reservoir water level schemes to experience related risks and benefits in the interest of hydropower sustainability

Resolution of deadlocks in a fine discrete floor field cellular automata model-modeling of turning and lateral movement at bottlenecks

For a parallel scheme, finer discretization of space in cellular automaton models of pedestrian dynamics can lead to new problems, e.g. the formation of deadlocks. In order to deal with such problems in the floor field cellular automata (FFCA) model, the turning and lateral movement of occupants at a bottleneck are considered. Simulations of the proposed model are found to fit well with experiments. The turning breaks the deadlock and releases the congestion at the bottleneck. The deadlock frequency decreases and the free travel time increases with the turning probability at the bottleneck. For slow lateral movement, pedestrians take more time to reach the exit, and the peak flow is first reached at a later time. As the discretization becomes finer, the crowd shape around the bottleneck changes gradually from semi-circle to semi-ellipse. Pedestrians in the finer discrete model seem to prefer queuing in a line rather than making a detour. The increase of lateral velocity may lead to more frequent conflicts among pedestrians

Combination of C-Reactive Protein and Procalcitonin in Distinguishing Fungal from Bacterial Infections Early in Immunocompromised Children

Invasive fungal infection (IFI) is life-threatening in children with cancer and hematology disorders, especially when diagnosis and treatment are delayed. Conventional β-D-glucan and galactomannan tests have poor positive predictive values in the diagnosis of IFI in children with cancer. This study aims to access the diagnostic performance of C-reactive protein (CRP) and procalcitonin (PCT) in differentiating IFI from bacterial bloodstream infections in children with malignant and hematology disorders. CRP and PCT levels were measured in samples taken from patients between 12 and 24 h after fever onset, of which 24 and 102 were in the IFI and bacterial groups, respectively. We found that the CRP levels were much higher in the IFI group than the bacterial group (100.57 versus 40.04 mg/L, median, p < 0.001), while the PCT levels remained significantly lower (0.45 versus 1.29 μg/L, median, p = 0.007). Both CRP and PCT showed significant diagnostic utilities with an area under the curve (AUC) of 0.780 (95% CI, 0.664–0.896, p < 0.001) and 0.731 (95% CI, 0.634–0.828, p < 0.001) when using the cut-off values of 94.93 mg/L and 2.00 μg/L, respectively. However, the combined biomarker of CRP and PCT yielded a better diagnostic performance with an AUC of 0.934 (95% confidential interval (CI), 0.881–0.987, p < 0.001), which was significantly higher than that of CRP or PCT (both p < 0.001), with a sensitivity of 87.5% and a specificity of 87.3%. Our study demonstrates high levels of CRP combined with low PCT could differentiate IFI from bacterial bloodstream infections in immunocompromised children