Effects of elliptical burner geometry on partially premixed gas jet flames in quiescent surroundings.

The 3:1 AR elliptical and circular burners produced similar carbon monoxide and nitric oxide emission indexes over the range of equivalence ratios of 0.55 to 4.0, for laminar flames. (Abstract shortened by UMI.)It was found that the laminar flames were similar in appearance and overall flame length for the 3:1 AR elliptical and the circular burner. The laminar 4:1 AR elliptical burner flame split into two sub-flames along the burner major axis. This splitting had the effect of greatly shortening the 4:1 AR elliptical burner flame to have an overall flame length about half of that of the circular and 3:1 AR elliptical burner flames. The length of all three burners flames increased with increasing burner exit equivalence ratio.The blowout velocity for the three burners increased with increase in hydrogen mass fraction of the hydrogen/propane fuel mixture. For the rich premixed flames, the circular burner was the most stable, the 3:1 AR elliptical burner, was the least stable, and the 4:1 AR elliptical burner was intermediate to the two other burners. This order of stability was due to two reasons. The elliptical burners have enhanced turbulence generation that lowers their stability when compared to the circular burner. The 4:1 AR elliptical burner had greater stability due to a greater velocity decay rate and wider OH reaction zones particularly in the region between the two jets.This study is the investigation of the effect of elliptical nozzle burner geometry and partial premixing, both 'passive control' methods, on a hydrogen/hydrocarbon flame. Both laminar and turbulent flames for circular, 3:1, and 4:1 aspect ratio (AR) elliptical burners are considered. The amount of air mixed with the fuel is varied from fuel-lean premixed flames to fuel-rich partially premixed flames. The work includes measurements of flame stability, global pollutant emissions, flame radiation, and flame structure for the differing burner types and fuel conditions. Special emphasis is placed on the near-burner region. Experimentally, both conventional (IR absorption, chemiluminecent, and polarographic emission analysis, ) and advanced (laser induced fluorescence, planar laser induced fluorescence, Laser Doppler Velocimetry (LDV), Rayleigh scattering) diagnostic techniques are used. Numerically, simulations of 3-dimensional laminar and turbulent reacting flow are conducted. These simulations are run with reduced chemical kinetics and with a Reynolds Stress Model (RSM) for the turbulence modeling

Internally generated conscious activity: ​Reflections upon (lucid) dreaming, mind-wandering and meditation

editorial reviewedCertain conscious states such as dreaming reveal that conscious activity can be to a large extent internally generated rather than being driven by sensory stimuli. In this interview, psychologist and neuroscientist Benjamin Baird discusses the developments of scientific research on these conscious phenomena including dreaming, mind-wandering and meditation and how they interrelate. Lucid dreaming, the ability to become aware that one is dreaming while in a dream, is highlighted as a unique way to gain experimental control over internally generated conscious activity during sleep

Easily Prepared Chiral Scorpionates: Tris(2-oxazolinyl)boratoiridium(I) Compounds and Their Interactions with MeOTf

Optically active C3-symmetric monoanionic ligands are uncommon in organometallic chemistry. Here we describe the synthesis of readily prepared tris(4S-isopropyl-2-oxazolinyl)phenylborate [ToP] and fluxional, zwitterionic four- and five-coordinate iridium(I) compounds [Ir(ToP)(η4-C8H12)] (4) and [Ir(ToP)(CO)2] (5). The highly fluxional nature of 4 and5 makes structural assignment difficult, and the interaction between the iridium(I) center and the [ToP] ligand is established by solid-state and solution 15N NMR methods that permit the direct comparison between solution and solid-state structures. Although iridium cyclooctadiene 4 is a mixture of four- and five-coordinate species, the dicarbonyl 5 is only the five-coordinate isomer. The addition of electrophiles MeOTf and MeI provides the oxazoline N-methylated product rather than the iridium methyl oxidative addition product. N-Methylation was unequivocally proven by through-bond coupling observed in 1H−15N HMBC experiments

Sensitivity of terrestrial precipitation trends to the structural evolution of sea surface temperatures

Pronounced intermodel differences in the projected response of land surface precipitation (LSP) to future anthropogenic forcing remain in the Coupled Model Intercomparison Project Phase 5 model integrations. A large fraction of the intermodel spread in projected LSP trends is demonstrated here to be associated with systematic differences in simulated sea surface temperature (SST) trends, especially the representation of changes in (i) the interhemispheric SST gradient and (ii) the tropical Pacific SSTs. By contrast, intermodel differences in global mean SST, representative of differing global climate sensitivities, exert limited systematic influence on LSP patterns. These results highlight the importance to regional terrestrial precipitation changes of properly simulating the spatial distribution of large-scale, remote changes as reflected in the SST response to increasing greenhouse gases. Moreover, they provide guidance regarding which region-specific precipitation projections may be potentially better constrained for use in climate change impact assessments

Insulation for Daydreams: A Role for Tonic Norepinephrine in the Facilitation of Internally Guided Thought

Although consciousness can be brought to bear on both perceptual and internally generated information, little is known about how these different cognitive modes are coordinated. Here we show that between-participant variance in thoughts unrelated to the task being performed (known as task unrelated thought, TUT) is associated with longer response times (RT) when target presentation occurs during periods when baseline Pupil Diameter (PD) is increased. As behavioral interference due to high baseline PD can reflect increased tonic activity in the norepinephrine system (NE), these results might implicate high tonic NE activity in the facilitation of TUTs. Based on these findings, it is hypothesised that high tonic mode NE leads to a generalised de-amplification of task relevant information that prioritses internally generated thought and insulates it from the potentially disruptive events taking place in the external environment

Ultra Low NOx Catalytic Combustion for IGCC Power Plants

In order to meet DOE's goals of developing low-emissions coal-based power systems, PCI has further developed and adapted it's Rich-Catalytic Lean-burn (RCL{reg_sign}) catalytic reactor to a combustion system operating on syngas as a fuel. The technology offers ultra-low emissions without the cost of exhaust after-treatment, with high efficiency (avoidance of after-treatment losses and reduced diluent requirements), and with catalytically stabilized combustion which extends the lower Btu limit for syngas operation. Tests were performed in PCI's sub-scale high-pressure (10 atm) test rig, using a two-stage (catalytic then gas-phase) combustion process for syngas fuel. In this process, the first stage consists of a fuel-rich mixture reacting on a catalyst with final and excess combustion air used to cool the catalyst. The second stage is a gas-phase combustor, where the air used for cooling the catalyst mixes with the catalytic reactor effluent to provide for final gas-phase burnout and dilution to fuel-lean combustion products. During testing, operating with a simulated Tampa Electric's Polk Power Station syngas, the NOx emissions program goal of less than 0.03 lbs/MMBtu (6 ppm at 15% O{sub 2}) was met. NOx emissions were generally near 0.01 lbs/MMBtu (2 ppm at 15% O{sub 2}) (PCI's target) over a range on engine firing temperatures. In addition, low emissions were shown for alternative fuels including high hydrogen content refinery fuel gas and low BTU content Blast Furnace Gas (BFG). For the refinery fuel gas increased resistance to combustor flashback was achieved through preferential consumption of hydrogen in the catalytic bed. In the case of BFG, stable combustion for fuels as low as 88 BTU/ft{sup 3} was established and maintained without the need for using co-firing. This was achieved based on the upstream catalytic reaction delivering a hotter (and thus more reactive) product to the flame zone. The PCI catalytic reactor was also shown to be active in ammonia reduction in fuel allowing potential reductions in the burner NOx production. These reductions of NOx emissions and expanded alternative fuel capability make the rich catalytic combustor uniquely situated to provide reductions in capital costs through elimination of requirements for SCR, operating costs through reduction in need for NOx abating dilution, SCR operating costs, and need for co-firing fuels allowing use of lower value but more available fuels, and efficiency of an engine through reduction in dilution flows

The Decoupled Mind : Mind-wandering Disrupts Cortical Phase-locking to Perceptual Events

The mind flows in a "stream of consciousness," which often neglects immediate sensory input in favor of focusing on intrinsic, self-generated thoughts or images. Although considerable research has documented the disruptive influences of task-unrelated thought for perceptual processing and task performance, the brain dynamics associated with these phenomena are not well understood. Here we investigate the possibility, suggested by several convergent lines of research, that task-unrelated thought is associated with a reduction in the trial-to-trial phase consistency of the oscillatory neural signal in response to perceptual input. Using an experience sampling paradigm coupled with continuous high-density electroencephalography, we observed that task-unrelated thought was associated with a reduction of the P1 ERP, replicating prior observations that mind-wandering is accompanied by a reduction of the brain-evoked response to sensory input. Time-frequency analysis of the oscillatory neural response revealed a decrease in theta-band cortical phase-locking, which peaked over parietal scalp regions. Furthermore, we observed that task-unrelated thought impacted the oscillatory mode of the brain during the initiation of a task-relevant action, such that more cortical processing was required to meet task demands. Together, these findings document that the attenuation of perceptual processing that occurs during task-unrelated thought is associated with a reduction in the temporal fidelity with which the brain responds to a stimulus and suggest that increased neural processing may be required to recouple attention to a task. More generally, these data provide novel confirmatory evidence for the mechanisms through which attentional states facilitate the neural processing of sensory input

The MuSe 2021 Multimodal Sentiment Analysis Challenge: sentiment, emotion, physiological-emotion, and stress

Multimodal Sentiment Analysis (MuSe) 2021 is a challenge focusing on the tasks of sentiment and emotion, as well as physiological-emotion and emotion-based stress recognition through more comprehensively integrating the audio-visual, language, and biological signal modalities. The purpose of MuSe 2021 is to bring together communities from different disciplines; mainly, the audio-visual emotion recognition community (signal-based), the sentiment analysis community (symbol-based), and the health informatics community. We present four distinct sub-challenges: MuSe-Wilder and MuSe-Stress which focus on continuous emotion (valence and arousal) prediction; MuSe-Sent, in which participants recognise five classes each for valence and arousal; and MuSe-Physio, in which the novel aspect of 'physiological-emotion' is to be predicted. For this year's challenge, we utilise the MuSe-CaR dataset focusing on user-generated reviews and introduce the Ulm-TSST dataset, which displays people in stressful depositions. This paper also provides detail on the state-of-the-art feature sets extracted from these datasets for utilisation by our baseline model, a Long Short-Term Memory-Recurrent Neural Network. For each sub-challenge, a competitive baseline for participants is set; namely, on test, we report a Concordance Correlation Coefficient (CCC) of .4616 CCC for MuSe-Wilder; .5088 CCC for MuSe-Stress, and .4908 CCC for MuSe-Physio. For MuSe-Sent an F1 score of 32.82% is obtained