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The outcomes of research regarding pyrolysis oils obtained from waste sources (WPO) used to power a compression-ignition engine have been presented in this paper. Oils obtained in an industrial process based on polypropylene (PPO), polystyrene (PSO) and used car tires (TPO) were used. Prior to conducting engine tests, a in-depth examination of the tested fuels parameters was undertaken. An advanced single-cylinder research engine utilizing split fuel injection technique was used for the tests. Emission analysis was performed using multi-compound FTIR analytical system. The WPO were blended with diesel fuel in proportions of 20%, on the mass basis and tested at middle engine load and variable EGR rates. Tests have shown that modern combustion systems compliant with the Tier 4/Stage IV standard with multi-pulse injection can handle fuels with a WPO content of 20% without the need for recalibration. The addition of PPO did not significantly affect the emission, while mixing with PSO resulted in elevated levels of hydrocarbon and carbon monoxide emissions. Regarding to the mixture with TPO, increased levels of particulate matter, sulfur oxides, aromatic compounds and formic acid were observed. [ABSTRACT FROM AUTHOR]

In this article, the authors refer to the measurement of acoustic emission, where they found that this methodology can determine the combustion characteristics in the combustion chamber of the engine and thus it is possible to confirm a better combustion process and overall reduction of engine noise after decarbonization. The formation of diesel exhaust soot is also supported by the authors' paper, in which they describe how such soot is formed and what effect the addition of special mixtures to the combustion process has on the formation of such carbon deposits. The article uses BG technologies for deep engine decarbonization, including intake and exhaust parts. This technology is one of many on the market, but it was only with this technology that the authors managed to achieve the relevant results that this article will introduce to. For the test, we selected vehicles that had a problem to pass at the emission control. [ABSTRACT FROM AUTHOR]

Oxidative potential (OP) has been proposed as a possible integrated metric for particles smaller than 2.5 μm in diameter (PM2.5) to evaluate adverse health outcomes associated with particulate air pollution exposure. Here, we investigate how OP depends on sources and chemical composition and how OP varies by land use type and neighborhood socioeconomic position in the Los Angeles area. We measured OH formation (OPOH), dithiothreitol loss (OPDTT), black carbon, and 52 metals and elements for 54 total PM2.5 samples collected in September 2019 and February 2020. The Positive Matrix Factorization source apportionment model identified four sources contributing to volume-normalized OPOH: vehicular exhaust, brake and tire wear, soil and road dust, and mixed secondary and marine. Exhaust emissions contributed 42% of OPOH, followed by 21% from brake and tire wear. Similar results were observed for the OPDTT source apportionment. Furthermore, by linking measured PM2.5 and OP with census tract level socioeconomic and health outcome data provided by CalEnviroScreen, we found that the most disadvantaged neighborhoods were exposed to both the most toxic particles and the highest particle concentrations. OPOH exhibited the largest inverse social gradients, followed by OPDTT and PM2.5 mass. Finally, OPOH was the metric most strongly correlated with adverse health outcome indicators.

With the new pollution control rules and surging requirements for the increase in efficiency of the internal combustion engines, designing the exhaust manifold has become a growing area of interest. The present work focuses on modelling the multi-end exhaust manifold and comparing it with the single-end exhaust manifold. Both the structural and thermal analyses are carried out using the finite element method. Along with the modified design, various materials such as mild steel, cast iron, stainless steel and medium carbon steel are also evaluated for their structural and thermal behaviour. It is found that the multi-end exhaust manifold performs better in terms of better stress and temperature distribution in comparison to the single-end exhaust manifold. The magnitude of the stress experienced by multi-end exhaust manifolds is 20 MPa lesser than single-end exhaust manifolds. However, the change in material has a marginal effect in terms of stress and temperature distribution. [ABSTRACT FROM AUTHOR]

The level of gaseous pollutants CO, NO2, NH3, and H2S at four strategic places CAS campus (site A), PRESCO campus (site B), ISHIEKE campus (site C), and PERMSITE campus (site D) in Ebonyi State University, Abakaliki business centers were determined using a hand-held Portable gas monitor (gas man model CO1925 6H, NO2 19835H, NH3 19736H, and H2S1975 2H) for a period of two seasons (dry and rainy season). The ascending order of magnitude of the concentration of the gaseous pollutants in the dry season was NH3 < NO2 < CO. The same trend was also recorded in the rainy season while H2S was not detected in both seasons. The range of NH3, NO2, and CO in the dry season was 0.24±0.00 site B to 0.53±0.05 site D, 0.38±0.08 site B to 0.82±0.25 site D, and 0.98±0.28 site C to 1.52±0.51 site D respectively. The result of NH3 obtained during the rainy season ranged from 0.12±0.10 site B to 0.64±0.24 site C while the range of NO2 and CO were 0.43±0.21 site B to 0.70±0.25 site A, 0.89±0.36 site C to 1.03±0.56 site D respectively. CO recorded the highest concentration in all the sites studied followed by NO2 while NH3 had the least concentration. In this study, all the results obtained were not above World Health Organization (W.H.O) standard (NO2=20.1 ppm, NH3=67 ppm, CO = 2.68 ppm, and H2S = 0.03 ppm). Therefore, the air quality of these campuses' business centers is conducive for now. [ABSTRACT FROM AUTHOR]

This document is a list of references related to the topic of anxiety and exhaustion in students during online distance learning, particularly in the context of the COVID-19 pandemic. The references include studies on the impact of psychological capital and social support on student engagement and burnout, the effects of disasters and pandemics on mental health, the transition to remote learning during the pandemic, and the relationship between student anxiety and academic performance. The document also includes references on coping strategies, self-regulation of learning, and the role of social support in mitigating burnout. [Extracted from the article]

A previous investigation showed that fire in circular, mechanically-ventilated, horizontal 0.30-m and 0.61-m ducts could be extinguished effectively by discharging water mist in a co-flow manner with the exhaust flow. However, besides horizontal ducts, an exhaust system is likely to also have ductwork in vertical and other orientations. Since the water mist dispersion and transport to the fire could be affected by the duct orientation due to fire buoyancy, there was a need to determine if the established horizontal duct protections would also be applicable to other duct orientations. Considering the fact that the fire buoyancy effect in ducts is bracketed between horizontal and vertical duct orientations, a series of fire tests was therefore conducted to evaluate if the above-mentioned horizontal duct protections would also be applicable when the ducts were to be in the vertical orientation. This paper presents the evaluation of vertical duct protection employing the same nominal spacing of 0.31 m for the water mist application as for the horizontal duct protection. The evaluation included the two protections established previously for the horizontal 0.30-m duct: one provided a minimum water mist concentration of 300 g/m3 with a median droplet size of 77 μm, while the other provided 399 g/m3 with a median droplet size of 88 μm. On the other hand, the protection for the horizontal 0.61-m duct yielded a minimum water mist concentration of 270 g/m3 with a median droplet size of 115 μm. The vertical duct tests showed that, by discharging water mist upward in the co-flow manner with the exhaust flow, both the protections for the horizontal 0.30-m duct could successfully extinguish the fire in the vertical duct, but the protection for the horizontal 0.61-m duct could not completely extinguish the fire in the vertical duct when water mist was discharged upward in the co-flow manner. However, by discharging water mist downward against the exhaust flow, the fire in the vertical 0.61-m duct could be extinguished rapidly. The vertical duct tests showed that, to ensure the applicability of a water mist protection for different duct orientations, the protection should be verified for both the horizontal and vertical duct orientations, with appropriate adjustments if required. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Test & Measurement Technology is the property of Publishing Center of North University of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Metal Working (1674-165X) is the property of Metal Working Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Reliable diagnostics that measure the detached state of the ITER divertor plasma will be necessary to control heat flux to the divertor targets during steady state, burning plasma operation. This paper conducts an initial exploration into the feasibility of the divertor shunt diagnostic as a lightweight, robust, and real-time detachment sensor. This diagnostic is a set of shunt lead pairs that measure the voltage drop along the divertor cassette body, from which the plasma scrape-off layer (SOL) current is calculated. Using SOLPS-ITER simulations for control-relevant ITER plasma scenarios, the thermoelectric current magnitude along the SOL is shown to decrease significantly with the onset of partial detachment at the outer divertor target. Electromagnetic modelling of a simplified divertor cassette is used to develop a control-oriented inductance-resistance circuit model, from which SOL currents can be calculated from shunt pair voltage measurements. The sensitivity and frequency-response of the resulting system indicates that the diagnostic will accurately measure SOL thermoelectric currents during ITER operation. These currents will be a good measure of the detached state of the divertor plasma, making the divertor shunt diagnostic a potentially extremely valuable and physically robust sensor for real-time detachment control. [ABSTRACT FROM AUTHOR]

This paper analyses the influence of the type of electrode in a spark plug on exhaust gas emission. The objects of the research were the following vehicles of different years of production: the Volkswagen Beetle 1300, the Honda Nighthawk 650, the BMW e46 318i, the Hyundai i10, and the Audi A4 B6. The vehicles were powered by petrol and LPG. Spark plugs were selected for the vehicles, with different kinds of construction for the main electrodes and different numbers of poles but with similar heat values. A comparative analysis of the composition of the exhaust gas mixture was performed, depending on the set of spark plugs used. The amount of CO, HC, CO2, and O2 emissions was analysed. The results were compared with the applicable exhaust gas emission standards. Both in the case of E5 95 petrol and LPG gas, lower exhaust gas emissions were observed when iridium spark plugs were used. [ABSTRACT FROM AUTHOR]

Particulate matter (PM) emissions significantly impact air quality in poultry production facilities. Electrostatic precipitators (ESPs) have been identified as a potentially effective technology for poultry PM mitigation. However, the design and optimisation of full-scale ESPs for PM mitigation in poultry facilities requires further study. An ESP with a cross-sectional airflow area of 0.371 m2 designed for installation inside a poultry facility (indoor ESP), and an ESP with a cross-sectional airflow area of 0.767 m2 designed for installation after the exhaust fans (exhaust ESP) were developed and tested in a laboratory setting. A wind tunnel with a custom-built dust generator was used to test each ESP across a range of air velocities (0.5–2.0 m s−1), total suspended PM concentrations (0.15–2.0 mg m−3), and applied voltages (24–32 kV for indoor ESP, 38–46 kV for exhaust ESP). The optimised operating conditions for the indoor ESP were an air velocity of 1.5 m s−1 and an applied voltage of 26 kV, resulting in PM 2.5 and PM 10 removal efficiencies of 90.3% ± 3.3% and 93.1% ± 2.7%, respectively, with a specific corona power (SCP) of 0.0510 ± 0.0021 W m−3 h1. The exhaust ESP was optimised to operate at 1.5 m s−1 and 40 kV, resulting in respective PM 2.5 and PM 10 removal efficiencies of 98.2% ± 0.5% and 98.9% ± 0.3%, and an SCP of 0.0301 ± 0.0018 W m−3 h1. The indoor and exhaust ESPs performed sufficiently to proceed with field evaluations in a commercial poultry facility. • Indoor and exhaust ESP for poultry PM control tested using flour in a wind tunnel. • Indoor ESP showed optimal performance at 26 kV and an air velocity of 1.5 m s−1. • Exhaust ESP exhibited maximum PM removal efficiencies at 40 kV and 1.5 m s−1. • Indoor ESP removed up to 90.3% of flour PM 2.5 and up to 93.1% of flour PM 10. • Exhaust ESP removed up to 98.2% of flour PM 2.5 and up to 98.9% of flour PM 10. [ABSTRACT FROM AUTHOR]

Thermoelectric generators can be used to utilize the waste heat from vehicle exhaust for power generation. Due to the poor heat transfer of the exhaust, the thermoelectric conversion efficiency of the generator is poor, thus strengthening the heat transfer in the exhaust heat exchanger (EHE) is crucial. However, the complex optimized structure also poses challenges for the processing of EHE. In this paper, the addition of porous plates in the exhaust channel is proposed to improve the thermoelectric conversion efficiency of exhaust waste heat, and a coupled heat-electric-flow model of the exhaust generator is constructed. The simulation results found that the addition of the porous plate has a greater impact on the rear side flow, which can cause a pronounced increase in the overall temperature of the channel. Moreover, optimal insertion position exists for maximum net power generation.

Passenger cars differ in their levels of emitted noise and mileage, which can have a negative impact on the environment and humans. This was confirmed by the results of this study on the noise levels generated by passenger cars that have the same parameters, or are of one type. The loudest place in the tested vehicles turned out to be the combustion engine compartment, with the average noise level exceeding 90 dB and exhibiting a noticeable, significant increase alongside an increase in the mileage of the vehicles. This value of noise intensity is classified as dangerous for the human body. As a result of the conducted tests, it can be concluded that an engine cover is an important element in damping the sounds emitted by an internal combustion engine after the use of an aluminum heat shield to increase noise absorption. In the future, the environmental problem of noise emission from cars can be solved by encouraging the use of quieter, electric vehicles. [ABSTRACT FROM AUTHOR]

The paper reports for the first time the heat and particle exhaust at the plasma boundary through various edge diagnostics for the high-performance plasma obtained after pellet injection on Wendelstein 7-X. The plasma density at the edge is found to be reduced by a factor of 2 in the high-performance phase, supporting the previously reported density peaking at the plasma centre. The plasma beta effect on the magnetic topology is reflected by the appearance of the second strike line, which is well understood with simulation. However, during the rapid decay phase of the enhanced confinement, a transient localized heat flow of up to 16 MW m ^−2 is observed at the leading edge of a poorly cooled divertor component, which has not been understood but raises concerns about machine safety.

A review is given on the highlights of a scatter-shot approach of developing machine-learning methods and artificial neural networks based fast predictors for the application to fusion exhaust. The aim is to enable and facilitate optimized and improved modeling allowing more flexible integration of physics models in the light of extrapolations towards future fusion devices. The project encompasses various research objectives: (a) developments of surrogate model predictors for power & particle exhaust in fusion power plants; (b) assessments of surrogate models for time-dependent phenomena in the plasma-edge; (c) feasibility studies of micro–macro model discovery for plasma-facing components surface morphology & durability; and (d) enhancements of pedestal models & databases through interpolators and generators exploiting uncertainty quantification. Presented results demonstrate useful applications for machine-learning and artificial intelligence in fusion exhaust modeling schemes, enabling an unprecedented combination of both fast and accurate simulation.

Recent results from MAST Upgrade are presented, emphasising understanding the capabilities of this new device and deepening understanding of key physics issues for the operation of ITER and the design of future fusion power plants. The impact of MHD instabilities on fast ion confinement have been studied, including the first observation of fast ion losses correlated with Compressional and Global Alfvén Eigenmodes. High-performance plasma scenarios have been developed by tailoring the early plasma current ramp phase to avoid internal reconnection events, resulting in a more monotonic q profile with low central shear. The impact of m / n = 3/2, 2/1 and 1/1 modes on thermal plasma confinement and rotation profiles has been quantified, and scenarios optimised to avoid them have transiently reached values of normalised beta approaching 4.2. In pedestal and ELM physics, a maximum pedestal top temperature of ∼350 eV has been achieved, exceeding the value achieved on MAST at similar heating power. Mitigation of type-I ELMs with n = 1 RMPs has been observed. Studies of plasma exhaust have concentrated on comparing conventional and Super-X divertor configurations, while X-point target, X-divertor and snowflake configurations have been developed and studied in parallel. In L-mode discharges, the separatrix density required to detach the outer divertors is approximately a factor 2 lower in the Super-X than the conventional configuration, in agreement with simulations. Detailed analysis of spectroscopy data from studies of the Super-X configuration reveal the importance of including plasma-molecule interactions and D _2 Fulcher band emission to properly quantify the rates of ionisation, plasma-molecule interactions and volumetric recombination processes governing divertor detachment. In H-mode with conventional and Super-X configurations, the outer divertors are attached in the former and detached in the latter with no impact on core or pedestal confinement.

An overview is presented of the progress since 2021 in the construction and scientific programme preparation of the Divertor Tokamak Test (DTT) facility. Licensing for building construction has been granted at the end of 2021. Licensing for Cat. A radiologic source has been also granted in 2022. The construction of the toroidal field magnet system is progressing. The prototype of the 170 GHz gyrotron has been produced and it is now under test on the FALCON facility. The design of the vacuum vessel, the poloidal field coils and the civil infrastructures has been completed. The shape of the first DTT divertor has been agreed with EUROfusion to test different plasma and exhaust scenarios: single null, double null, X-divertor and negative triangularity plasmas. A detailed research plan is being elaborated with the involvement of the EUROfusion laboratories.

Optimizing vehicle aerodynamics is more effective than solely reducing engine weight and improving efficiency. The exhaust pipe ejects hot air that affects the vehicle's aerodynamics by interacting with its surroundings. Simulating a 3D vehicle model requires significant computing capabilities, so a cheaper alternative is sought. This research simulated the DrivAer model in 2D and 3D and compared results to prove the ability of 2D simulations to represent 3D models. The more cost-effective dimension was used to determine the optimal configuration for different exhaust pipe positions. The 2D simulation had a 12% discrepancy in drag coefficient compared to the 3D simulation, but required significantly fewer computational resources due to its lower number of elements (5 million less elements). The position of the exhaust pipe significantly impacts the lift force, with a possible 41% decrease in stability and 18% potential for improvement. Findings reveal that there is a higher possibility of performance setback due to the exhaust pipe position rather than improvement. The results provide a guide on which exhaust locations to avoid for optimal performance.

For catalytic converter-equipped light-duty gasoline vehicles (LDGV), the hot-stabilized tailpipe emissions for pollutants such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) are well controlled. However, there are few reported real-world measurements of cold starts. Idling cold start and hot-stabilized trip exhaust emissions were measured for 37 LDGVs using a portable emissions measurement system (PEMS). Five vehicles were also measured for transient driving cold starts. On average, it took approximately 400, 150, 330, and 120 s to accumulate 90 percent of the idle cold start increments for fuel use, CO, HC, and NOx, respectively. Driving cold start increments were substantially higher than idling cold start increments, whereas cold start duration was typically shorter. For example, driving cold start contributed approximately 64%, 68%, 58%, and 4.5% of the trip total CO, HC, NOx, and carbon dioxide (CO2), respectively. This study is unique in quantifying the cold start contribution on a trip basis with real-world data. Although the cold start increment is sensitive to driving compared to idling, in either case, cold starts contribute substantially to total exhaust mass emissions. Furthermore, driver decisions regarding driving versus idle can substantially affect the contribution of cold starts, especially for CO and NOx. [ABSTRACT FROM AUTHOR]

he paper makes a comparison between two types of automatic control systems for the opening of the exhaust nozzle as objects subject to automatic control, under the conditions of their use on various types of jet engines for aircraft. Mathematical models of these nozzles are issued and some possible control schemes are described; Matlab-Simulink simulations are performed concerning object(s) step responses for throttle’s step input. Some conclusions are drawn and some comments concerning the properties and the quality of the studied systems were also presented. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Currently, the problem of air pollution is topical. In this study, we described the question of environmental influence on human health. Sickness statistics over the past years (in compliance with the Health Ministry of the Russian Federation) were analyzed. National health deterioration and an increase in sicknesses are observed. During the last few years, respiratory diseases account for up to 46% of all cases. We studied the components of harmful substances of gasoline and diesel engine emissions and analyzed some of the chemical compounds of the exhaust (which cause a negative influence on the human respiratory system). The study aims to determine the impact of exhaust pollution on citizens’ health conditions. Barnaul citizens participated in this research. The questionnaire was conducted with the help of Google Forms. The received data illustrate that 90% of the respondents use motor transport. Moreover, 76%–79% of motor service users experience the reduced general condition, dizziness, and nausea caused by exhaustion. Around 90% of participants understood the negative influence of exhaust on their health (in places with less concentration of cars, they feel better). To improve the situation of air pollution in cities, we suggest a multi methodology focused on a preventive approach: (1) restrict the usage of personal autos; (2) promote a healthy way of life; use of alternative eco gasoline (including electric cars); (3) develop infrastructure for pedestrians and bicycles; and (4) carry out vast landscaping of cities.

This study investigates about the designing and Computational Fluid Dynamics (CFD) analysis of the exhaust system of a formula student vehicle. Based on FSAE rules KTM Duke 390 engine is used and the noise level is to keep below 110 dB. The main aim of the design is to have a smooth flow exhaust gases without restriction to increase engine efficiency and to keep minimal backpressure. An absorptive type of muffler is finalized to attenuate the sound levels. Based on three different equations, exhaust runner dimensions are calculated and CFD analysis is performed to choose the optimum runner dimensions. Using ASHRAE guidelines muffler dimensions range is calculated. Using Ricardo software based on effective volumetric efficiency analysis, volume of muffler that fits in ASHRAE dimension range was finalized. Both runner and muffler are analyzed and CFD analysis was carried out which resulted in streamline velocity profile of the exhaust gas and acceptable values of pressure, velocity and velocity streamline was found. CFD analysis of the full exhaust system was carried out to understand the flow characteristics of exhaust gases. [ABSTRACT FROM AUTHOR]

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the current work, a novel combination of discharge plasma and industrial wastes has been proposed to explore the possibility of treating the oxides of nitrogen (NOX) in diesel exhaust through plasma-activation of abundant and freely available industrial wastes. Five industrial wastes have been selected for testing as potential catalysts, namely fly ash, foundry sand, bagasse, mulberry residue, and oyster shells. The diesel exhaust was treated using plasma catalysis, by allowing it to flow through a dielectric barrier discharge plasma reactor packed with industrial waste pellets, at ambient temperature and atmospheric pressure. An increase in NOX removal during plasma catalysis, in comparison to plasma-only treatment, was observed through experiments conducted using the pellets. Maximum removal of NOX (70%) was obtained during plasma catalysis using oyster shell pellets. The results have been discussed in detail along with the possible reaction pathways and explanations for the NOX removal during plasma catalysis. [ABSTRACT FROM AUTHOR]

Nowadays, the devastating effects of the pollutants produced by gasoline are known well. As a result, scientists are looking for a better formula to replace the gasoline currently in use. Using different additives has been one of the strategies developed throughout the years. However, because certain compounds damage the environment and human life, researchers must now choose which additives to use. The primary goal of this work is to test a gasoline combination with nano-additives Ag2O and MnO2 in a 4-stroke vehicle engine (Fiat 128) and to investigate the influence of novel mixes on the efficiency of combustion rates and the amount of target pollutant gas released (CO, NOx, and the exhaust temperature). The tests were carried out at three different engine speeds: 2000, 2500, and 2900 rpm. At the end of the test, the 0.05% concentration of Ag2O nano-additive was chosen as the best sample, which increases engine performance in gasoline combustion rates and minimizes harmful gas emissions. Furthermore, CO and NOx emissions were lowered by 52% and 35%, respectively, according to EURO 6, indicating a considerable reduction in mortality rates and costs. Finally, a new mechanism was observed using Ag2O nanoparticles, leading to a reduction in CO and CO2 at the same time. [ABSTRACT FROM AUTHOR]

The global automotive industry is undergoing a significant transition as battery electric vehicles enter the market and diesel sales decline. It is widely recognized that internal combustion engines (ICE) will be needed for transport for years to come; however, demands on ICE fuel efficiency, emissions, cost, and performance are extremely challenging. Gasoline compression ignition (GCI) is one approach for achieving the demanding efficiency and emissions targets. A key technology enabler for GCI is partially-premixed, compression ignition (PPCI) combustion, which involves two high-pressure, late fuel injections during the compression stroke. Both NOx and smoke emissions are greatly reduced relative to diesel, and this reduces the aftertreatment (AT) requirements significantly. For robust low-load and cold operation, a two-step valvetrain system is used for exhaust rebreathing (RB). Exhaust rebreathing involves the reinduction of hot exhaust gases into the cylinder during a second exhaust lift event during the intake stroke to help promote autoignition. The amount of exhaust rebreathing is controlled by exhaust backpressure, created by the vanes on the variable nozzle turbine (VNT) turbocharger. Because of the higher cycle temperatures during rebreathing, exhaust HC and CO may be significantly reduced, while combustion robustness and stability also improve. Importantly, exhaust rebreathing significantly increases exhaust temperatures in order to maintain active catalysis in the AT system for ultra-low tailpipe emissions. To achieve these benefits, it is important to optimize the rebreathe valve lift profile and develop an RB ON→OFF (mode switch) strategy that is easy to implement and control, without engine torque fluctuation. In this study, an engine model was developed using GT-Suite to conduct steady-state and transient engine simulations of the rebreathing process, followed by engine tests. The investigation was conducted in four parts. In part 1, various rebreathe lift profiles were simulated. The system performance was evaluated based on in-cylinder temperature, exhaust temperature, and pumping work. The results were compared with alternative variable valve actuation (VVA) strategies such as early exhaust valve closing (EEVC), negative valve overlap (NVO), positive valve overlap (PVO). In part 2, steady-state simulations were conducted to determine an appropriate engine load range for mode switching (exhaust rebreathing ON/OFF and vice-versa). The limits for both in-cylinder temperature and exhaust gas temperature, as well as the external exhaust gas recirculation (EGR) delivery potential were set as the criteria for load selection. In part 3, transient simulations were conducted to evaluate various mode switch strategies. For RB OFF, the cooled external EGR was utilized with the goal to maintain exhaust gas dilution during mode switches for low NOx emissions. The most promising mode-switch strategies produced negligible torque fluctuation during the mode switch. Finally, in part 4, engine tests were conducted, using the developed RB valve lift profile, at various low-load operating conditions. The mode switch experiments correlated well with the simulation results. The tests demonstrated the simplicity and robustness of the exhaust rebreathing approach. A robust engine response, low CNL, high exhaust gas temperature, and low engine out emissions were achieved in the low load region. [ABSTRACT FROM AUTHOR]

There exists a large body of previous work using reduced two-dimensional models of the scrape-off layer (SOL), which model fluctuations in the drift-plane but approximate parallel transport with effective loss terms. Full size three-dimensional simulations of SOL turbulence in experimental geometries are now possible, but are far more computationally expensive than 2D models. We therefore use a flux-tube geometry model of the SOL to compare the results of 2D simulations to 3D simulations with a similar setup, looking for systematic differences. Our setup mimics the outer SOL of a double-null plasma, with no neutrals and no shear, and is therefore likely more favourable to agreement. Overall, we do find good agreement in the basic radial profiles, probability distribution functions, and power spectra of fluctuations. However, the average temperature is over-predicted in 2D relative to 3D, and we explain the difference in terms of the effect of geometrical simplifications of devices at low power. Varying geometric parameters, we find that supersonic flow in the divertor leg, which occurs because our simulations do not include neutrals and so represent low-recycling conditions, means that the divertor leg length only has a weak effect on the output. Finally, we examine the effect of altering the magnitude of source and sink terms in 2D, concluding that they cannot easily be used to recreate both the density and temperature profiles observed in 3D simultaneously. [ABSTRACT FROM AUTHOR]

This paper investigates beam evolution and beam sizes variation of hyperbolic sinusoidal Gaussian (HSG) beam propagating in jet engine exhaust-induced turbulence. We find the received field by solving Huygens-Fresnel integral with a relevant power spectrum. Our results reveal that HSG loses its initial profile until 100 m. Besides, beam with low displacement parameter value is more resistive against turbulence. In terms of beam size, beams with low Gaussian source size expand less as compared to the beams with larger Gaussian source size. In the light of our findings, optical systems in aircrafts like directed infrared counter measure (DIRCM) and laser designators can be developed. [ABSTRACT FROM AUTHOR]

A study was conducted on the utilization of oil palm wood waste in the production of porous ceramics, which were then used as a motor vehicle exhaust gas filter. The porosity, hardness, and morphology of the resulting ceramics were all measured. Using the gas analysis approach, ceramics with a higher porosity value were also examined for their exhaust gas filtration power. The study's findings show that the particle size of oil palm sawdust has a significant impact on porosity, hardness, and ceramic morphology. The porosity of the ceramic decreases as the particle size decreases, but the hardness increases. Porous ceramics have porosity levels of 60, 57, and 56 percent. Porous ceramics have hardness values of 221, 62, 302, 83, and 363, 46 MPa. And Filtration of exhaust CO gas 1.88%, CO2 1.1%, and HC 1123 ppm. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Recent advances in data processing from the Cloud Imaging and Particle Size (CIPS) instrument on the NASA Aeronomy of Ice in the Mesosphere satellite allow observation of bright mesospheric clouds at mid‐latitudes (<60°). When adjusted for the evolving local time (LT) of the CIPS observations during its mission we find that the frequencies of these bright clouds in the northern hemisphere show no trend from 2007 to 2021 and no dependence on the solar cycle, although the interannual variability is extreme. Rather we investigate the possible link with propellant exhaust from orbital vehicles, typically launched at lower latitudes. By filtering the launch record equatorward of 60°N using only those launches between 23 and 10 LT, we find a strong correlation with the observed mid‐latitude mesospheric cloud frequency variability between 56° and 60°N. Meridional winds at 92 km from a meteorological analysis system reveal that these morning launches occurred at the time of maximum northward transport. Based upon this combination of high correlation between the cloud frequency and the launch record plus favorable transport conditions, it is likely that space traffic has a strong influence on the interannual variability of these bright mesospheric clouds. Key Points: Northern mid‐latitude mesospheric cloud frequencies are reported from satellite observations that detect the brightest clouds thereFrom 2007 to 2021 frequencies do not show a multi‐year trend or a dependence on the solar cycle but show extreme interannual variabilityJuly frequencies correlate with interannual variations in morning rocket launches, consistent with transport of exhaust modulated by tides [ABSTRACT FROM AUTHOR]