Burn Reduction Research Articles

Reversionary Control Modes for the Mitigation of Failures in a Partially Turboelectric Aircraft Propulsion System

Abstract In support of emission and fuel burn reduction goals, the aviation industry is actively pursuing the advancement of electrified aircraft propulsion (EAP) technology. This includes turboelectric and hybrid electric propulsion designs that combine gas turbine engine and electrical system hardware. Such architectures exhibit a high degree of coupling between subsystems. This drives the need for system-level control strategies to ensure the safe, coordinated, and efficient operation of all subsystems. The design and certification of any aircraft propulsion system requires that all potential subsystem failures are identified, and the hazards posed by these failures are appropriately mitigated. This requirement is particularly challenging for EAP systems due to their integrated nature. One approach to assist in EAP failure mitigation is the inclusion of automated reconfiguration capabilities within the propulsion control system. Such control modes, referred to as reversionary control modes, are designed to automatically detect failures and activate backup control modes upon failure detection. This paper covers the design and evaluation of reversionary control mode logic developed for a partially turboelectric propulsion concept. Test results from a real-time hardware-in-the-loop evaluation of the concept are also presented and discussed. The results show that the developed reversionary control logic can successfully detect and mitigate subsystem failures in a representative environment that includes actual electrical system hardware.

Fat, protein, and temperature each contribute to reductions in capsaicin oral burn.

It is widely accepted that milk provides the greatest relief from capsaicin burn, an effect typically attributed to its fat content and temperature. Previously, Lawless etal. reported partitioning lipophilic capsaicin in fat reduces burn, whereas Green showed lower temperature reduces burn. Recent research shows that dairy and nondairy proteins also reduce capsaicin burn, suggesting that multiple factors reduce oral burn from chilies. Here, we investigated the effectiveness of palate cleansers with varied viscosities, temperatures, and sugar, fat, and protein content. Specifically, we tested ice cream, Italian ice, yogurt, lassi, cold water (4°C), and warm water (37°C). Participants rinsed with a 5ppm capsaicin solution, followed by a palate cleanser, before rating burn intensity continuously for 2min on a general Labeled Magnitude Scale. Inspection of the time-intensity (TI) curves revealed all palate cleansers performed better than warm water. Italian ice performed on par with cold water, which did better than yogurt. Pairwise comparisons showed that ice cream and lassi had significantly lower burn ratings at some time points relative to warm or cold water. We extracted scaffolding parameters for each TI curve, finding that ice cream and lassi had the lowest areas-under-the-curve and the greatest percent decrease from their maxima, with ice cream performing slightly better in both parameters. These data support the view that it is not just one characteristic of a product, but rather a combination of product factors that reduce oral burn, including fat content, protein content, and temperature. More research is required to determine the relative weight of these factors in combination, given the multiple mechanisms underlying burn reduction.

Effectiveness of Argymax spray in treating xerostomia in pregnant women with isthmic-cervical insufficiency

Relevance. Xerostomia, commonly known as dry mouth, is a prevalent orofacial disorder among pregnant women experiencing isthmic-cervical insufficiency. This condition manifests as a burning sensation in the mouth, pain, and discomfort during eating. A clear correlation exists between pain, taste alterations, and the perception of oral dryness, highlighting the multifaceted impact of xerostomia on affected individuals. Pregnant women with isthmic-cervical insufficiency, a complication that significantly increases the risk of preterm labor, are particularly susceptible to xerostomia. This condition is often accompanied by heightened psycho-emotional stress, which can exacerbate the symptoms of dry mouth. Despite the multitude of treatments available for xerostomia, the primary objective for dentists is to formulate an appropriate and effective treatment plan, tailored to the physiological needs of the patient. This study evaluates the efficacy of Argymax spray in alleviating xerostomia in pregnant women with isthmic-cervical insufficiency.Materials and methods. A study was conducted involving 84 pregnant women who were assessed and treated over a three-week period to evaluate the rate of mixed saliva secretion. Subjective data were collected using a five-point scale to analyze the reduction in pain potential, itching, and burning. Hygienic and periodontal indices were determined before therapy and three months after the use of the spray.Results. The study demonstrated that Argymax spray begins to act within seven days of initial application and maintains its effectiveness throughout the observation period.Conclusion. Hormonal changes during pregnancy affect both the overall body and the condition of the oral cavity, making it particularly vulnerable. Early diagnosis and appropriate management strategies can prevent the development of several oral mucosal diseases associated with xerostomia. Argymax spray is recommended as symptomatic therapy for the treatment of xerostomia in pregnant women with isthmic-cervical insufficiency.

Different variations in PM2.5 sources and their specific health risks in different periods in a heavily polluted area of the Beijing-Tianjin-Hebei region of China

The temporal variations in source-specific health risks of airborne particles and the differences in estimated source contributions to PM2.5 mass and PM2.5 exposure in severely polluted areas with the implementation of control measures remain unclear. In this study, PM2.5 samples were collected from a city of heavy pollution in the Beijing-Tianjin-Hebei region of China in two autumn-winter seasons during 2017–2019. The dominant species of PM2.5 was SNA (sum of sulfate, nitrate, and ammonium; 34 %), organic matter (OM; 23 %), and fine soil (15 %). PM2.5 concentration decreased across the years, whereas trace elements and OM showed the largest increases. A positive matrix factorization model combined with a health risk assessment method identified six sources, and quantified their specific health risks. The major sources of PM2.5 mass were secondary source (37 %) and coal combustion (20 %). The health risks (non-cancer risk for children, and cancer risk for children and adults) exceeded the guidelines, and were dominated by industrial processes (38 % and 40 %) and coal combustion (22 % and 52 %). The interannual decline in PM2.5 concentration was mainly due to reductions in biomass burning and soil dust, but the significant increase in health risks was attributed to the enhancement of industrial processes and coal combustion. On clean days, both PM2.5 mass and health risks were significantly affected by industrial processes and soil dust. As PM2.5 pollution increased, secondary source and coal combustion contributed significantly to PM2.5 mass. Coal combustion posed high health risks during pollution and the heating periods, especially in 2018–2019. Mn, Cr, and As were the dominant elements responsible for source-specific health risks. The quantitative result highlights the different responses of PM2.5 mass and health risks to recent mitigation measures, and suggests that both source concentrations and source-specific health risks should be of concern in the future.

Development and performance evaluation of paddy straw based insulating block composite for low temperature storage application

The study focuses on the conversion of crop residues into thermal insulation materials, to gain better utility with value addition. Such applications will divert the paddy straw to useful purposes, leading to reduction in the open field burning of paddy straw in various developing countries. The process was optimized for manufacturing of insulating block composite and evaluating the mechanical and thermal performance of the same. Properties like compressive strength, internal bonding strength, density, porosity, and thermal conductivity were studied for the block. The optimum physical and mechanical properties were observed as moisture content 8–10 %, a block density 450–500 kg/m3, porosity 70 % with particle size of 8–15 mm. The mixture ratio of block was optimized as paddy straw 574.9 g, clay 840 g, and seed lac 260 g with thermal conductivity, compressive strength, bonding strength, and porosity as 0.08 W/m K, 1.19 MPa, 0.028 MPa, and 70.7 %, respectively, using Response Surface Methodology. An eco-friendly, economical and sustainable technological value addition for paddy straw was obtained and used for insulation purposes in cold storages as well as drying chambers. Paddy straw insulating block can also be utilized in combination with conventional insulation materials.

Skeletal Kinetics Reduction for Astrophysical Reaction Networks

A novel methodology is developed to extract accurate skeletal reaction models for nuclear combustion. Local sensitivities of isotope mass fractions with respect to reaction rates are modeled based on the forced optimally time-dependent (f-OTD) scheme. These sensitivities are then analyzed temporally to generate skeletal models. The methodology is demonstrated by conducting skeletal reduction of constant density and temperature burning of carbon and oxygen relevant to Type Ia supernovae (SNe Ia). The 495-isotopes Torch model is chosen as the detailed reaction network. A map of maximum production of 56Ni in SNe Ia is produced for different temperatures, densities, and proton-to-neutron ratios. The f-OTD simulations and the sensitivity analyses are then performed with initial conditions from this map. A series of skeletal models are derived and their performances are assessed by comparison against currently existing skeletal models. Previous models have been constructed intuitively by assuming the dominance of α-chain reactions. The comparison of the newly generated skeletal models against previous models is based on the predicted energy release and 44Ti and 56Ni abundances by each model. The consequences of y e ≠ 0.5 in the initial composition are also explored where y e is the electron fraction. The simulated results show that 56Ni production decreases by decreasing y e as expected, and that the 43Sc is a key isotope in proton and neutron channels toward 56Ni production. It is shown that an f-OTD skeletal model with 150 isotopes can accurately predict the 56Ni abundance in SNe Ia for y e ≲ 0.5 initial conditions.

Mining Associations between Air Quality and Natural and Anthropogenic Factors

The urbanization and industrialization of human society boost the socioeconomic growth but yet inevitably result in unprecedented damages to environment and organisms. One of the threats is the air pollution produced from anthropogenic activities. Moreover, the pollution concentrates longer in certain meteorological phenomena and exacerbates the impact on nature species and human health. This paper presents an association mining approach to identify the influential factors which result in a high volume of air pollution concentration, in particular, the particulate matter with aerodynamic diameter ≤ 2.5 μm (PM2.5). Since the literature showed that the identified factors are location and spatial-scale dependent, we chose a basin geography, Puli township, Taiwan, and inferred the association relationships with two different-scaled monitoring stations. The government-built supersite at Puli estimates the PM2.5 concentration for the entire township of the area around 150 km2, while the participatory microsites monitor air quality in a smaller region of a hundred thousand square meters. Our research was conducted with relevant data during 2017–2019. The mining result has unique findings as compared to the literature. The relative humidity, precipitation, wind speed and direction, which were identified as major factors in many previous studies, have less impact on air quality of our studied field than temperature and atmospheric pressure. The remarkable distinction is mainly attributed to the special weather patterns of basin geography. We investigated the impact of all national festivals and identified the most significant ones. The probability of observing PM2.5 concentrations greater than 35 μg/m3 in the activity hours of New Year’s Eve is 50% which is significantly greater than 11.74%, the probability of observing the same concentration range over all days in the investigated years, while the Tomb Sweeping Day (TSD) has a varying impact on air quality depending on the order of the TSD date within the long holiday. The increase of PM2.5 concentration is remarkably more significant if the TSD is the last day in the long holiday than if it is the middle day. This finding can be taken into consideration when the government agent makes schedules for national festivals. Finally, it was learned in our study that different landmarks and land uses have various significant impacts on micro-scale air quality. The microsites monitor high PM2.5 concentrations at particular landmarks with a greater confidence than the mean confidence over all microsites. These pollution-associated landmarks with the confidence ranked from highest to lowest are night markets, crossroads, paper mills, temples, and highway exits. It is worth noting that the PM2.5 increase contributed by temples is negligible, which may be attributed to the citizen action for promoting reduction in joss paper and incense stick burning. The land uses have diverse impacts on air quality. Anthropogenic activities contribute higher PM2.5 concentrations in business districts and residential areas. The PM2.5 concentration monitored at high lands and agricultural lands is lower than the overall background due to fewer mass gathering and combustion activities in these land uses.

Control Co-Design Optimization of Spacecraft Trajectory and System for Interplanetary Missions

This paper develops a control co-design (CCD) framework to simultaneously optimize the spacecraft’s trajectory and onboard system (rocket engine) and quantify its benefit. An open-loop optimal control problem (two-finite burn Mars missions) is used as the benchmark, and the engine design considers the combustion equilibrium and nozzle geometry. The objective function is the fuel burn. The design variables are the trajectory control parameters (such as burn times, burn directions, and time of flight), initial fuel mass, and engine design parameters (such as throat area, mixture ratio, and chamber pressure). The constraints include the final velocities and positions of spacecraft. Single-point optimizations are conducted for three departure dates in May, July, and September 2020. A multipoint optimization is also performed to balance the engine performance for these dates with 49 design variables and 20 constraints. It is found that the CCD optimizations exhibit 22–28% more fuel burn reduction than the trajectory-only optimization with fixed engine parameters and 16–20% more fuel burn reduction than the decoupled trajectory-engine optimization. The proposed CCD optimization framework can be extended to more spacecraft trajectory control parameters and onboard systems and has the potential to design more efficient spacecraft missions.

Regulation of open straw burning and residential coal burning around urbanized areas could achieve urban air quality standards in the cold region of northeastern China

Air quality issues in Northeast China are concerning due to the significant seasonal atmospheric pollution and typical climatic, geographic and industrial structure characteristics of the area. However, urban air quality managers are having great difficulty achieving targeted pollution control goals in the time allotted due to limited studies in the region. In this study, using the city of Siping in Jilin Province as a case study, we analysed the cause of seasonal atmospheric pollution, developed a high-resolution emissions inventory for major atmospheric pollutants and simulated urban air quality improvements under projected emission control scenarios to select a reasonable source control scheme to inform urban air quality management planning in the region. Years with available air quality data (2014–2020) were divided into three periods, i.e., a weak control period (WCP: 2014–2017), an enhanced control period (ECP: 2018–2019) and the COVID-19 period (CDP: 2020). The annual PM2.5, PM10, SO2 and NOx emissions varied by 62∼46 μg·m−3, 103∼76 μg·m−3, 27∼22 μg·m−3 and 46∼41 μg·m−3, respectively, during the WCP; the emissions decreased to 37 μg·m−3, 69 μg·m−3, 11 μg·m−3 and 34 μg·m−3, respectively, during the ECP and to 33 μg·m−3, 61 μg·m−3, 11 μg·m−3 and 33 μg·m−3, respectively, during the CDP, which reached the limits of the Ambient Air Quality Standard of China (level II, 35 μg·m−3, 70 μg·m−3, 60 μg·m−3 and 50 μg·m−3). The PM2.5 and PM10 indices exceeded the standards, mainly in late autumn (October and November) and in the middle of winter (January and February). Based on comprehensive data analysis of the spatiotemporal air quality and the local high-resolution emissions inventory, straw burning, stationary combustion (especially for coal burning) and vehicle emissions were the main pollution sources in late autumn, and continuous adverse weather conditions were the dominant factors in severe pollution days during the middle of winter. In addition, the urban air quality of Siping was also affected by pollutant transport from the northwest (the city of Songyuan in Jilin Province), northeast (the city of Changchun in Jilin Province) and south (the city of Tieling in Liaoning Province) according the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. Strict straw-burning policy was implemented in autumn during the ECP and CDP, which significantly improved the air quality from that of the WCP, with an AQI reduction of 31.58 %. However, the planned burning policy was not well-implemented, resulting in more days of moderate or heavy pollution. Using 2017 as the base year, scenarios were simulated in which feasible source control measures were set (namely, straw-burning control, the elimination of small boilers in urbanized areas, staggered peak heating measures and a 50 % reduction in residential bulk coal burning around urbanized areas and suburban areas), and the concentrations of PM2.5 and PM10 were projected to decline by more than 29.79 %, meeting the urban air quality standards. This study highlights the importance of combining straw burning regulation in no-burning areas, limited burning areas and residential coal-burning substitution around urbanized areas to improving the air quality in cold regions.

Inducible desensitization to capsaicin with repeated low-dose exposure in human volunteers

Responses to capsaicin are reduced following repeated exposure, a phenomenon known as capsaicin desensitization. Heavy consumers of chilies consistently report reduced oral burn relative to infrequent consumers, presumably due to chronic desensitization. However, the mechanism(s) underlying capsaicin desensitization remain poorly understood. We hypothesized that reduced response to capsaicin due to repeated oral exposure may result from a change in the expression of the capsaicin receptor (TRPV1) gene. To test this, we conducted two longitudinal desensitization studies in healthy human volunteers. In Study 1, 51 adults completed a 17-day capsaicin desensitization protocol. The study consisted of three in-person visits where they were asked to sample stimuli, including 3, 6, and 9 ppm capsaicin, and rate intensity on a general labeled magnitude scale (gLMS). Between days 3 & 17, participants rinsed at home with 6 ppm capsaicin (n = 31) or a control (n = 20) solution (20 uM sucrose octaccetate; SOA) twice a day. Before and after the oral exposure protocol, a clinician collected fungiform papillae. Participants randomized to the capsaicin rinse showed a statistically significant reduction in oral burn ratings that was not observed in controls, indicating repeated low-dose exposure can systematically induce desensitization. TRPV1 expression was not associated with reported capsaicin burn, and there was no evidence of a decrease in TRPV1 expression following capsaicin exposure. In Study 2, participants (n = 45) rinsed with 6 ppm capsaicin in a similar protocol, rating capsaicin, vanillyl butyl ether (VBE), cinnamaldehyde, ethanol, menthol, and sucrose on days 1, 3, & 17. Burn from capsaicin, VBE, cinnamaldehyde, and ethanol all showed a statistically significant change – capsaicin, VBE and cinnamaldehyde burn all dropped ∼20 %, and a larger reduction was seen for ethanol – while menthol cooling and sucrose sweetness did not change. Collectively, this suggests reductions in oral burn following chronic capsaicin exposure generalizes to other stimuli (i.e., cross desensitization) and this cannot be explained by a change in TRPV1 mRNA expression. More work is needed to elucidate the underlying mechanism for capsaicin desensitization in the oral cavity.

Tail-Integrated Boundary Layer Ingesting Propulsion Systems for Turbo-Electric Aircraft

Abstract This article presents conceptual design guidelines and results for a tail-integrated propulsion system for a turbo-electric civil transport aircraft with boundary layer ingestion (BLI). The aerodynamic performance goal is separation-free and shock-free operation at cruise with fuel burn reduction, compared with a baseline conventional aircraft for the same mission. The assessment of BLI benefits is based on calculations using CFD and TASOPT software, both to characterize the design challenges and to establish the physical mechanisms for resolving these challenges. The guidelines include a “horseshoe” inlet to accept the non-uniform flow without incurring separation, a nacelle profile similar to supercritical airfoils to reduce shock strength, and an annular nozzle to eliminate flow separation between tail-BLI propulsors. The conceptual design has nine BLI propulsors with electric fans on an axisymmetric tail of a single-aisle aircraft. The fans are powered by twin underwing turbofans. The estimated benefit of the tail-BLI, twin underwing turbofan aircraft is 10.4% in Payload-Range Fuel Consumption (PRFC) at a cruise Mach number of 0.8, compared to a baseline twin underwing turbofan configuration. Sensitivity studies further show that a 1% increase in installed (i.e., with BLI) fan isentropic efficiency translates to 0.8% rise in PRFC benefit.

More than fat – Proteins in dairy and plant milks contribute to the reduction of oral burn from capsaicin

The effectiveness of cow’s milk in reducing capsaicin-induced burn is well-known, and typically attributed to capsaicin’s lipophilicity. Still, controlled laboratory studies show full-fat milk is not more efficacious than fat-free milk, suggesting other components may contribute to milk’s effectiveness. Recent research has shown milk proteins like micellar casein and whey reduce capsaicin burn in the absence of fat. This paper reports two experiments in moderate capsaicin users that investigate the efficacy of dairy and plant milks varying in fat and protein content. In Experiment One, participants were exposed to 5-ppm capsaicin solutions before rinsing with conventional full-fat milk, ultra-filtered full-fat milk, almond milk, soy milk, and pea protein-enriched flax milk. In Experiment Two, they rinsed with fat-free, conventional full-fat, and ultra-filtered full-fat milk, and three soy milks of varying protein content. Participants made burn ratings on a general Labelled Magnitude Scale (gLMS) once every 10 s for 2-min (Experiment One) or continuously for 2-min (Experiment Two). Experiment One showed significant main effects of time and sample, with planned comparisons revealing differences for water versus conventional and ultra-filtered full-fat milk. In Experiment Two, a main effect of time and a time-by-sample interaction were observed, with samples in both blocks (soy milk, dairy milk) significantly outperforming water. Some evidence of a concentration-dependent effect was observed for protein, with both experiments suggesting ultra-filtered high protein full-fat milk was most efficacious. These findings suggest proteins play a role in mitigating capsaicin burn, although further research is needed to quantify the relative contributions of fat and protein.

A data-driven flow loss prediction model for the blade hub region of a boundary layer ingestion fan rotor

PurposeIn a boundary layer ingestion (BLI) propulsion system, the fan operates continuously under distorted inflow conditions, leading to an increment of aerodynamic loss and in turn impacting the potential fuel burn reduction of the aircraft. Usually, in the preliminary design stage of a BLI propulsion system, it is essential to assess the impact of fuselage boundary layer fluids on fan aerodynamic performances under various flight conditions. However, the hub region flow loss is one of the major loss sources in a fan and would greatly influence the fan performances. Moreover, the inflow distortion also results in a complex and highly nonlinear mapping relation between loss and local physical parameters. It will diminish the prediction accuracy of the commonly used low-fidelity computational approaches which often incorporate traditional physics-based loss models, reducing the reliability of these approaches in evaluating fan performances. Meanwhile, the high-fidelity full-annulus unsteady Reynolds-averaged Navier–Stokes (URANS) approach, even though it can give rather accurate loss predictions, is extremely time-consuming. This study aims to develop a fast and accurate hub loss prediction method for a BLI fan under distorted inflow conditions.Design/methodology/approachThis paper develops a data-driven hub loss prediction method for a BLI fan under distorted inflows. To improve the prediction accuracy and applicability, physical understandings of hub flow features are integrated into the modeling process. Then, the key physical parameters related to flow loss are screened by conducting a sensitivity analysis of influencing parameters. Next, a quasi-steady assumption of flow is made to generate a training sample database, reducing the computational time by acquiring one single sample from the highly time-consuming full-annulus URANS approach to a cost-efficient single-blade-passage approach. Finally, a radial basis function neural network is used to establish a surrogate model that correlates the input parameters and the output loss.FindingsThe data-driven hub loss model shows higher prediction accuracy than the traditional physics-based loss models. It can accurately capture the circumferentially and radially nonuniform variation trends of the losses and the associated absolute magnitudes in a BLI fan under different blade load, inlet distortion intensity and rotating speed conditions. Compared with the high-fidelity full-annulus URANS results, the averaged relative prediction errors of the data-driven hub loss model are kept less than 10%.Originality/valueThe originality of this paper lies in developing a new method for predicting flow loss in a BLI fan rotor blade hub region. This method offers higher prediction accuracy than the traditional loss models and lower computational time cost than the full-annulus URANS approach, which could realize fast evaluations of fan aerodynamic performances and provide technical support for designing high-performance BLI fans.

Assessment of peatland burning in Scotland during 1985–2022 using Landsat imagery

Abstract In the Scottish uplands, prescribed burning of moorland vegetation is widely practised either to boost gamebird numbers for recreational shooting or to improve livestock grazing. In recent years, this system of land management has become controversial due to concerns over the potential impacts on ecosystem services. However, there are limited data on the extent, distribution or frequency of burning and it is unclear whether there are long‐term trends in burning. Crucially, the extent of burning on peat soils is not well known. We used a time series of Landsat imagery covering 7750 km2 of moorland in Eastern Scotland to detect annual variation in area burnt from 1985 to 2022. Burnt areas were detected using annual changes in Normalised Burn Ratio. An accuracy evaluation conducted over eight sites covering 415 km2 using a combination of Google Earth imagery, and field studies suggested a user's accuracy of 90% and a producer's accuracy of 77%. We estimate an average annual mean area burnt of 61 km2 with large interannual variability and no significant change in area burnt over the 38‐year study period. We estimate that 32% of burning (19 km2 year−1) occurred on deep peat soils with no reduction in burning on deep peat after the revision of national guidelines (the Muirburn Code) in 2017 recommended ceasing this practice. We find that in Eastern Scotland there has been no significant change in moorland area burnt over the last four decades. The fractional area burnt that is on deep peat is a matter of management concern.

Vegetation, fire and climate history in central-western Tasmania (41°S), Australia, over the last ∼21,000 years

We present high resolution pollen and macroscopic charcoal records from Basin Lake, a relatively small mid-latitude (42°S) lake located in central-western Tasmania, Australia, to examine vegetation, fire and climate change since and during the Last Glacial Maximum (LGM). We find dominance of cold-resistant alpine vegetation with buttongrass moorland and scant trees between ∼21.0-17.7 cal kyr BP, with local biomass burning and low lake levels between ∼21.0-20.0 cal kyr BP and a reduction in local biomass burning and a rise in lake levels between ∼20.0-17.7 cal kyr BP. These data suggest glacial-cold conditions during the last millennia of the LGM, with relatively humid conditions between ∼21.0-20.0 cal kyr BP and a further increase in humidity between ∼20.0-17.7 cal kyr BP. These shifts suggest an intensification of the South Westerly Winds (SWW) over the site between ∼20.0-17.7 cal kyr BP. An increase in cold-temperate rainforest taxa followed between ∼17.7-16.0 cal kyr BP along with lake-level lowering, suggesting a warm pulse and southward shift of the SWW at the beginning of the Last Glacial Termination (T1). Subsequent cold-temperate conditions and increased precipitation ensued between ∼16.0-14.9 cal kyr BP promoted by increased SWW influence. A rise in cold-resistant and hygrophilous rainforest taxa and lower biomass burning activity occurred between ∼14.9-12.8 cal kyr BP under colder conditions, enhanced precipitation and major SWW influence. A multi-millennial warm/dry interval began at ∼12.8 cal kyr BP with a decline in rainforest taxa, high fire activity and low lake levels and a further opening of the vegetation in response to elevated biomass burning between ∼11.1-8.9 cal kyr BP. We suggest a decline in the SWW influence that started at ∼12.8 cal kyr BP and accentuated between ∼11.1-8.9 cal kyr BP at the beginning of the Holocene. We detect increases in precipitation between ∼8.9-5.8, ∼3.4-1.9 cal kyr BP and the last ∼900 years, with declines in the intervening intervals. Our data indicate a pronounced and sustained fire-driven shift to a more open and shrub dominant landscape after ∼5.0 cal kyr BP, in synchronous with other pollen data from Tasmania's west, reflecting an increased efficacy of Aboriginal burning under more variable and overall reduced precipitation. Our climate inferences from Basin Lake are coherent with variations of the SWW identified in other terrestrial mid-latitudes records, suggesting synchronic changes in the SWW during and since the LGM.

Off-Design Performance Analysis of a Parallel Hybrid Electric Regional Turboprop Aircraft

Hybrid electric propulsion is one of the alternative solutions for reducing fuel burn and lower emissions while keeping a reasonable battery mass for regional turboprop aircraft operating on short routes. Most studies reporting fuel burn reductions evaluate the aircraft on the design mission, although regional transport aircraft rarely operate under these conditions. Therefore, considering its off-design performance is essential for providing a more complete understanding of aircraft capabilities under various operating conditions. Under these flight conditions, the multi-energy management aspect of hybrid propulsion and the fixed size of the batteries could have a significant impact on the system robustness in off-design operation. In this study, the off-design performance of an existing regional turboprop aircraft retrofitted with a parallel hybrid electric powertrain is assessed. Fuel burn benefits are evaluated on the payload–range diagram for an initial hybrid design and compared to the baseline aircraft. Then, using a novel sizing approach, considering a typical mission operation, this study shows an average improvement of percentage point on fuel burn benefits relative to the initial hybrid aircraft, creating a more robust design.

Mitigating agricultural fires with carrot or stick? Evidence from China

This paper examines the effects of biomass power plants (BPPs) on farmers’ use of agricultural fires for land clearance in China from 2001 to 2019. We show that the entry of BPPs leads to a significant reduction of agricultural fires by 14%. Farmers near BPPs display stronger responses, leading to a more significant reduction in straw burning, especially during high agricultural fire seasons. The notable decline in agricultural fires is likely driven by economic incentives provided by BPPs to farmers for collecting crop straw from their land. Additionally, straw-burning bans have limited effectiveness in reducing total agricultural fires, but they appear to reduce straw burning during nighttime, when the monitoring of agricultural fires is easier. We also provide evidence that local air quality has markedly improved, resulting in substantial health benefits that surpass the social benefits of reducing carbon emissions.

Investigation on the inflow distortion of a propulsive fuselage aircraft and its impact on the propulsion fan performance

Boundary layer ingesting (BLI) propulsion represents a promising concept that can achieve a great fuel burn reduction compared to conventional aircraft. This study numerically investigates the BLI inflow distortion and its impact on propulsion fan performance using commercial software CFX. First, Reynolds-averaged Navier–Stokes (RANS) simulations were performed to obtain the inflow distortion of a propulsive fuselage aircraft with various geometries and flight conditions. Then, full-annulus URANS simulations were carried out to assess the effect of various inflow distortions on the performance of NASA rotor 67. The results show that the fuselage sweep dominates the BLI inflow distortion, while the effects of the wing and vertical tail are local. As the angle of attack increases, the BLI inflow distortion is alleviated due to the freestream being ingested from the bottom of the propulsor. With the increase in the angle of sideslip, the redistributing and impinging flow significantly aggravates the total pressure and swirl distortion. With regard to the fan performance, various BLI inflow distortions share a similar static pressure distribution upstream of the rotor, as a result of the comparable total pressure distribution, so the cases without swirl distortion show a similar distribution of migration-induced swirl angle. At the peak efficiency condition, a minimum reduction in efficiency of approximately 4.5% and a total pressure ratio reduction of over 2.9% are observed for the investigated inflow distortions, in comparison with the Clean case. Moreover, the findings reveal that the effect of swirl distortion on fan performance is minor for the cruise case, but substantial for the two sideslip cases. These results offer useful insights into BLI propulsion.

Off‐setting climate change through formation flying of aircraft, a feasibility study reliant on high fidelity gas‐phase chemical kinetic data

AbstractApplication of formation flights to civil aviation is gaining interest, primarily due to the fuel burn reduction achieved by flying through another aircraft's wake. However, it is emerging that there are additional, less‐recognized climate benefits via reduction in ozone and contrail warming through this concept. The NOx threshold level is defined as when the loss rate for OH by reaction with NO2 is equal to the loss rates for OH with CO and CH4, beyond which level, ozone formation will decrease. In this study, The NOx threshold level was calculated at different altitudes and found that at cruise altitude (∼10 km), the amount of NO2 required for parity in OH loss with loss due to reaction with CO and CH4 is around 2 ppb. The spatial and temporal NOx threshold levels were estimated by STOCHEM‐Common Representative Intermediate (CRI) global chemical transport model and In‐service Aircraft for Global Observing System (IAGOS) measurement data and found that northern midlatitudes of the atmosphere are the most favorable region existing with the smallest NOx thresholds (0.5 ppb) needed before reduction in ozone formation is likely to occur at cruise altitude of aircraft. Incorporating the major air traffic corridors into the coarse spatial resolution of the chemical transport model overestimated the NOx compensation point, that is, increased photochemical ozone production. Thus, a simple one‐dimensional (1D) aircraft plume dispersion model was developed with higher spatial and temporal resolution for considering aircraft plumes and its chemistry more accurately. The model run shows that the impact of formation flying aircraft emissions on spatially averaged ozone could be halved if the aircraft could maintain separations inside 4 km relative to well separated flights of 10 km or more.

Efficient Aerostructural Wing Optimization Considering Mission Analysis

Aerostructural optimization traditionally uses a single or small number of cruise conditions to estimate the mission fuel burn objective function. In reality, a mission includes other flight segments contributing to fuel burn, such as climbing and descent. We aim to quantify how much performance is sacrificed by optimizing the design for a fuel burn approximation that ignores these other flight segments and flight conditions. To do this, we compare traditional approaches to mission-based optimization, which uses an accurate fuel burn objective computed by numerically integrating fuel flow across the mission profile. We find that mission-based optimization offers only marginal benefits over traditional single-point and multipoint approaches for aerostructural optimization of a narrow-body aircraft—only 1–2% in the most extreme cases. Thus, the traditional aerostructural optimization is acceptable, especially in cases where most fuel is burned during cruise. For the cases where climb fuel burn is significant, we introduce a simple change to traditional fuel burn approximation methods that allows the optimizer to find nearly all the fuel burn reduction of mission-based optimization but at the computational cost of multipoint optimization.