Modelling with queues: an empirical study

Application of methanol and optimization of mixture design over the full operating map in an intelligent charge compression ignition (ICCI) engine

This research examined whether increased cognitive task loading decreases warning compliance behavior. Participants performed a task in which they installed an external disk drive to a computer. Inside the accompanying owner's manual were a set of specific procedures that were to be followed during the installation to avoid damaging the equipment (i.e., to turn off the computer, to touch the computer's rear metal connector to discharge static electricity, and to eject a transport disk from the disk drive). Concurrent with this task, participants in the low and high task load conditions had to speak the answers to a series of single-digit or double-digit addition problems that were presented by a tape player. A control condition lacked the addition task. The results showed reduced compliance to the discharge static electricity instruction in the high load condition compared to the no load condition. The low load condition produced intermediate compliance, but was not significantly different from the other two conditions with one exception: the high load condition produced significantly lower compliance for the discharge static electricity instruction than the low load condition. These results suggest that warning effectiveness can be reduced when the mental resources necessary to carry out compliance are being absorbed by other concurrently performed tasks. Implications for further research on task loading and warning compliance are described.

In the present study, penetration and evaporation of the diesel sprays injected by a group of two closely spaced orifices (a group-hole nozzle) were investigated and compared with those of conventional single-hole nozzle sprays under various engine loads and wall-impinging conditions of direct-injection (DI) diesel engines. Both free and wall-impinging conditions were considered. The experiments were performed inside a constant-volume vessel under simulated ambient conditions for low and high engine loads of DI diesel engines. To investigate the effect of spray targeting, two impinging conditions (impingement angles of 45° and 90° with the same impingement distance) were applied. Geometry and liquid/vapour mass distributions of the evaporating diesel sprays were analysed using a laser absorption scattering (LAS) technique. Under a free spray condition, fuel evaporation of the group-hole nozzle spray was improved compared with that of the single-hole nozzle spray at low load conditions, while it showed simultaneous deterioration in fuel evaporation and spray tip penetration at high load conditions. Jet axes deflection of the two jets from the group-hole nozzle, which generated a dense liquid region at the central region of the spray, was responsible for this deteriorated evaporation at high load conditions. Under a vertical impingement condition (impingement angle of 90°), the group-hole nozzle spray showed simultaneous improvement in spray tip penetration and fuel evaporation at both low and high load conditions from strong momentum interaction of the two jets on the impingement wall. However, this improvement from the group-hole nozzle did not appear at an inclined wall-impingement condition (impingement angle of 45°) owing to weakened and delayed momentum interaction of the two jets. Both spray tip penetration and fuel evaporation of the group-hole nozzle spray were deteriorated at the inclined wall-impinging condition.

The Paris agreement is exerting pressure on industries that generate significant greenhouse gas (GHG) emissions, such as transportation. Electrification can help reduce GHG emissions from light duty vehicles, but it is unfeasible for heavy duty vehicles that are predominately powered by diesel engines. Fuel switching from diesel to low carbon fuels is a more practical way helping reduce GHG emissions from heavy duty vehicles. Natural gas and renewable natural gas are low carbon or renewable fuels that generate much less carbon dioxide (CO2) emissions than diesel during combustion. Natural gas/renewable natural gas – diesel dual fuel combustion is an efficient way to replace diesel by natural gas/renewable natural gas in heavy duty diesel engines. This paper reports an experimental investigation on combustion and GHG emissions of a heavy duty natural gas – diesel dual fuel engine at different load/speed conditions. The variation in the effect of natural gas fraction on engine performance with changing engine load was compared and analyzed. Nitrous oxide (N2O), nitrogen oxides (NOx), methane (CH4) and CO2 emissions were experimentally investigated and analyzed. The results revealed that the effect of natural gas fraction on engine performance changed with varying engine load and speed condition. N2O emissions from a dual fuel engine changed with increasing natural gas fraction, but the effect of N2O emissions on overall GHG emissions was not significant. However, CH4 emissions contributed significantly to the overall GHG emissions in a dual fuel engine, especially at low load conditions.

Recent studies have shown that spontaneous pre-stimulus fluctuations in brain activity affect higher-order cognitive processes, including risky decision-making, cognitive flexibility, and aesthetic judgments. However, there is currently no direct evidence to suggest that pre-choice activity influences value-based decisions that require self-control. We examined the impact of fluctuations in pre-choice activity in key regions of the reward system on self-control in food choice. In the functional magnetic resonance imaging (fMRI) scanner, 49 participants made 120 food choices that required self-control in high and low working memory load conditions. The task was designed to ensure that participants were cognitively engaged and not thinking about upcoming choices. We defined self-control success as choosing a food item that was healthier over one that was tastier. The brain regions of interest (ROIs) were the ventral tegmental area (VTA), putamen, nucleus accumbens (NAc), and caudate nucleus. For each participant and condition, we calculated the mean activity in the 3-s interval preceding the presentation of food stimuli in successful and failed self-control trials. These activities were then used as predictors of self-control success in a fixed-effects logistic regression model. The results indicate that increased pre-choice VTA activity was linked to a higher probability of self-control success in a subsequent food-choice task within the low-load condition, but not in the high-load condition. We posit that pre-choice fluctuations in VTA activity change the reference point for immediate (taste) reward evaluation, which may explain our finding. This suggests that the neural context of decisions may be a key factor influencing human behavior.

Perceptual load, voluntary attention, and aging: An event-related potential study

Effects of injection timing on exhaust particle size and nanostructure on a diesel engine at different loads

Investigation of the effects of gasoline and CNG fuels on a dual sequential ignition engine at low and high load conditions

Storage interference in working memory cannot be removed by attention

Effects of EGR and combustion phasing on the combustion and emission characteristic of direct-injection CI engine fueled with n-butanol/diesel blends

The selection of turbocharging systems for 8-cylinder marine diesel engines is difficult due to the existence of scavenge interference between cylinders. The constant pressure and pulse converter turbocharging systems have been used to eliminate the scavenge interference by applying large volume exhaust manifolds or grouped exhaust branches according to the firing order. But, the performance of constant pressure turbocharging system under low speed conditions of propulsion characteristics and transient conditions is poor, because of less available exhaust gas energy. The structure and arrangement of pulse converter turbocharging system is complex, meanwhile, and the performance at high speed and loads is not as good. In this paper, three new turbocharging systems, such as, MIXPC (mixed pulse converter) system, dual-turbocharger system (DTS) and controllable exhaust system (CES) were designed to improve the performance of a marine diesel engine. In the upstream part of MIXPC system, the separated small diameter branch pipes were used to isolate the exhaust gas interference. In the downstream part of MIXPC system, the single main pipe was connected with one entry turbocharger to improve the operation efficiency of the turbocharger. In the DTS, two one-entry turbochargers were used, one of which connected with 4 cylinders by two branch pipes and a mixer. The two cylinders with firing intervals of 270 crank angles were connected with one branch pipe. In the CES, a control valve was used to control the exhaust gas flow. The valve was opened at high speed and load conditions and closed at low speed and load conditions. The steady and transient performance of the three turbocharging systems was analyzed by simulation. The experimental studies were also carried out to compare the performance of the three turbocharging systems. The experimental results showed that the CES had the best fuel efficiency under low speed and load conditions, and the DTS had the best fuel efficiency under high speed and load conditions. Compared with the MIXPC system, the overall brake specific fuel consumption under propeller operating conditions was reduced by 11.3g/kWh with DTS and 5.3g/kWh with CES. But the uniformity of exhaust gas temperatures of cylinder heads was the best for MIXPC system. In general, the DTS was superior considering the structure simplicity and performance of the engine.

Effect of addition of di-tert butyl peroxide (DTBP) on performance and exhaust emissions of dual fuel diesel engine with hydrogen as a secondary fuel

Experimental investigation of the hydrogen-rich offgas spark ignition engine under the various compression ratios

The present article discusses the effect of cerium oxide nanoadditive inclusion on the working characteristics (combustion, performance, and emission) of water emulsified soybean biodiesel-fueled single cylinder Diesel engine. Test fuels with 5% and 10% volume of water in soybean biodiesel along with mass fraction of 100 ppm cerium oxide nanoparticle were prepared using mechanical agitator and ultrasonicator, and the experiments were conducted under different loading conditions in a single cylinder Diesel engine. The experimental results reveal that the emulsion fuel increases the peak in-cylinder pressure and net heat release values compared to pure soybean biodiesel, and cerium oxide nanoparticle inclusion reduces the peak combustion parameters value. The performance parameters such as brake specific fuel consumption and brake energy consumption are significantly improved with emulsion fuel, and the nanoparticle inclusion further improve the performance parameters. At low load conditions, the emulsion fuels increase the hydrocarbon and CO emissions, whereas these emission magnitudes are reduced at high load conditions. As far as the NOx and smoke emissions are concerned, an increase in water concentration directly reduces the emissions irrespective of load conditions. The cerium oxide nanoparticle inclusion reduces the emissions level from the water emulsified soybean biodiesel-fueled diesel engine.

The execution of resistance exercise against heavy loads promotes an acute intraocular pressure (IOP) rise, which has detrimental effects on ocular health. However, the effect of load on the IOP behavior during exercise remains unknown due to technical limitations. IOP monitoring during isometric squat exercise permits assessment of IOP behavior during physical effort. Second, greater loads will induce a higher IOP rise. Randomized cross-sectional study. Level 2. Twenty-six young adults (13 women, 13 men) performed an isometric squat exercise against 3 loads relative to their maximum capacity (low, medium, and high). IOP was measured before, during (1 measurement every 6 seconds), and after exercise (10 seconds of recovery). There was a progressive IOP rise during exercise, which was dependent on the load applied (Bayes factor10 >100). Higher IOP values were found in the high load condition in comparison with the medium (mean IOP difference = 1.5 mm Hg) and low (mean IOP difference = 3.1 mm Hg) conditions, as well as when the medium load was compared with the low load condition (mean IOP difference = 1.6 mm Hg). Men reached higher IOP values in comparison with women during the last measurements in the high load condition. Ten seconds of recovery were enough to obtain IOP values similar to baseline levels. Isometric squat exercise induces an immediate and cumulative IOP elevation, which is positively associated with the load applied. These IOP increments return to baseline values after 10 seconds of recovery, and men demonstrate a more accentuated IOP rise in comparison with women when high levels of effort are accumulated. These findings may help in better management of different ocular conditions and highlight the importance of an individualized exercise prescription in clinical populations.