Regional Burn Research Articles

Algorithm evaluation for polarimetric remote sensing of atmospheric aerosols

Abstract. From a passive satellite remote sensing point of view, the richest set of information on aerosol properties can be obtained from instruments that measure both intensity and polarization of backscattered sunlight at multiple wavelengths and multiple viewing angles for one ground pixel. However, it is challenging to exploit this information at a global scale because complex algorithms are needed with many fit parameters (aerosol and land/ocean reflection), based on online radiative transfer models. So far, two such algorithms have demonstrated this capability at a global scale: the Generalized Retrieval of Atmosphere and Surface Properties (GRASP) algorithm and the Remote sensing of Trace gas and Aerosol Products (RemoTAP) algorithm. In this paper, we present a detailed comparison of the most recent versions of RemoTAP and GRASP. We evaluate both algorithms for synthetic observations, for real PARASOL (Polarization and Anisotropy of Reflectances for Atmospheric Science coupled with Observations from a Lidar) observations against AERONET (Aerosol Robotic Network) for common pixels, and for global PARASOL retrievals for the year 2008. For the aerosol optical depth (AOD) over land, both algorithms show a root mean square error (RMSE) of 0.10 (at 550 nm). For single scattering albedo (SSA), both algorithms show a good performance in terms of RMSE (0.04), but RemoTAP has a smaller bias (0.002) compared to GRASP (0.021). For the Ångström exponent (AE), GRASP has a smaller RMSE (0.367) than RemoTAP (0.387), mainly caused by a small overestimate of AE at low values (large particles). Over ocean both algorithms perform very well. For AOD, RemoTAP has an RMSE of 0.057 and GRASP an even smaller RMSE of 0.047. For AE, the RMSEs of RemoTAP and GRASP are 0.285 and 0.224, respectively. Based on the AERONET comparison, we conclude that both algorithms show very similar overall performance, where both algorithms have stronger and weaker points. For the global data products, we find a root mean square difference (RMSD) between RemoTAP and GRASP AOD of 0.12 and 0.038 over land and ocean, respectively. The largest differences occur over the biomass burning region in equatorial Africa. The global mean values are virtually unbiased with respect to each other. For AE the RMSD between RemoTAP and GRASP is 0.33 over land and 0.23 over ocean. For SSA, we find much better agreement over land (bias = −0.01, RMSD = 0.043 for retrievals with AOD > 0.2) than over ocean (bias = 0.053, RMSD = 0.074). As expected, the differences increase towards low AOD, over both land and ocean. We also compared the GRASP and RemoTAP AOD and AE products against MODIS. For AOD over land, the agreement of either GRASP or RemoTAP with MODIS is worse than the agreement between the two PARASOL algorithms themselves. Over ocean, the agreement is very similar among the three products for AOD. For AE, the agreement between GRASP and RemoTAP is much better than the agreement of both products with MODIS. The agreement of the latest product versions with each other and with AERONET improved significantly compared to the previous version of the global products of GRASP and RemoTAP. The results demonstrate that the dedicated effort in algorithm development for multi-angle polarimetric (MAP) aerosol retrievals still leads to substantial improvement of the resulting aerosol products, and this is still an ongoing process.

Effect of Dexmedetomidine on Fluid Resuscitation in Burn-Injured Patients.

Fluid creep occurs when resuscitation after extensive burn injury reaches volumes higher than predicted. Since this has been described in patients with high opioid requirements, continuous analgesics and sedatives, including dexmedetomidine, have been avoided during resuscitation. This study sought to describe the impact of dexmedetomidine on fluid resuscitation requirements. This retrospective cohort study included adult patients with burns greater than 20% total body surface area (TBSA) resuscitated between January 2017 and June 2022 at a regional burn center. Patients deceased within 48 hours of burn were excluded. The primary outcome was volume of fluid required in the first 24 and 48 hours postburn. Secondary outcomes were the incidence of fluid-related adverse events within 7 days postburn. A total of 170 patients were included: 55 in the dexmedetomidine cohort and 115 in the control cohort. After propensity matching for variables associated with fluid creep, the dexmedetomidine cohort required 4.2 ± 1.7 mL/kg/%TBSA in the first 24 hours compared to 3.6 ± 1.1 mL/kg/%TBSA in the control cohort (P = 0.03). The difference was no longer significant at 48 hours (P = 0.11). There were no differences in the incidence of acute respiratory distress syndrome, delayed escharotomy/fasciotomy, intra-abdominal hypertension, or renal replacement therapy. Dexmedetomidine exposure during acute resuscitation resulted in increased fluid requirements in the first 24 hours, suggesting it is independently associated with fluid creep; however, this increase was not sustained at 48 hours. Clinical significance of this finding is unclear, as there was no increase in adverse events related to excessive fluid resuscitation between cohorts.

Flame self-interactions in MILD combustion of homogeneous and inhomogeneous mixtures

Flame self-interaction (FSI) events in Moderate or Intense Low-Oxygen Dilution (MILD) combustion of homogeneous and inhomogeneous mixtures of methane and oxidiser have been analysed using three-dimensional Direct Numerical Simulations (DNS). The simulations have been conducted at the same global equivalence ratio (⟨ϕ⟩=0.8\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\langle \\phi \\rangle = 0.8$$\\end{document}) for different levels of O2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathrm {O_2}$$\\end{document} concentration (dilution) and initial turbulence intensities. It has been reported that both homogeneous and inhomogeneous mixture MILD combustion cases exhibit significant occurrences of FSI events, with the peak frequency of FSI events occurring towards the burned gas side in all cases. Moreover, the frequency of FSI events increases with increasing dilution level and turbulence intensity, but the presence of mixture inhomogeneity leads to a reduction in total FSI events. In all cases, the cylindrical FSI topologies (i.e. tunnel formation and tunnel closure) were found to have a higher likelihood of occurrence compared to spherical FSI topologies (i.e. unburned and burned gas pockets). The geometries of FSI topologies were also analysed using the mean and Gaussian curvatures. It has been shown that the inward propagating spherical FSI topologies (i.e. unburned gas pockets) are associated with negative mean curvature, while outward propagating spherical FSI topologies (i.e. burned gas pockets) are associated with positive mean curvature. Moreover, tunnel formation (tunnel closure) FSI topologies predominantly exhibit either elliptic geometries with positive (negative) mean curvature or hyperbolic saddle geometries with negative (positive) mean curvature. It has been shown for the first time in MILD combustion that the mean values of kinematic restoration and dissipation terms in the transport equation of the magnitude of the reaction progress variable conditional upon the reaction progress variable tend to cancel each other in the vicinity of the critical points associated with cylindrical topologies. Thus, the singular contributions in these terms, which are obtained from analytical descriptions in the vicinity of tunnel formation and tunnel closure topologies, do not affect the balance equation of the magnitude of the gradient of the reaction progress variable. Consequently, there is no need for a separate model treatment for singularities in modelling approaches based on the magnitude of the gradient of the reaction progress variable. The FSI events in the reaction dominated and propagating flame regions of MILD combustion have also been analysed for the first time. It has been found that more FSI events occur in the reaction dominated region, particularly towards the burned gas side. However, the majority of spherical FSI topologies are found in the propagating flame region. The findings from this study indicate that turbulence intensity, dilution level and mixture inhomogeneity effects need to be considered in any attempt to extend flame surface-based modelling approaches to MILD combustion.

Associations between burn care services and impairment at discharge after burn injury: Analysis of the Global Burn Registry

BackgroundThroughout the world, burn injury is a major cause of death and disability. In resource-limited countries, burn injury is one of the leading causes of permanent disability among children who survive traumatic injuries, and burn injury is the fourth leading cause of disability worldwide. This study applied Andersen’s model of health care access to evaluate if patient characteristics (predisposing factors), burn care service availability (enabling factors) and injury characteristics (need) are associated with physical impairment at hospital discharge for patients surviving burn injuries globally. Specifically, access to rehabilitation, nutrition, operating theatre, specialized burn unit services, and critical care were investigated as enabling factors. The secondary aim was to determine whether associations between burn care service availability and impairment differed by country income level. Methods: This is a cross-sectional secondary analysis of prospectively collected data from the World Health Organization, Global Burn Registry. The outcome of interest was physical impairment at discharge. Simple and multivariable logistic regressions were used to test the unadjusted and adjusted associations between the availability of burn care services and impairment at hospital discharge, controlling for patient and injury characteristics. Effect modification was analyzed with service by country income level interaction terms added to the models and, if significant, the models were stratified by income. Results: The sample included 6622 patients from 20 countries, with 11.2% classified with physical impairment at discharge. In the fully adjusted model, patients had 89% lower odds impairment at discharge if the treatment facility provided reliable rehabilitation services compared to providing limited or no rehabilitation services (OR.11, 95%CI.08,.16, p < .01). However, this effect was modified by county income with the strong and significant association only present in high/upper middle-income countries. Sophisticated nutritional services were also significantly associated with less impairment in high/upper middle-income countries (OR=.04, 95% CI 0.203, 0.05, p < .01), but significantly more impairment in lower middle/low-income countries (OR=2.01, 95% CI 1.50, 2.69, p < .01). Patients had 444% greater odds of impairment if treated at a center with specialty burn unit services (OR 5.44, 95%CI 3.71, 7.99, p < .01), possibly due to a selection effect. Discussion: Access to reliable rehabilitation services and sophisticated nutritional services were strongly associated with less physical impairment at discharge, but only in resource-rich countries. Although these findings support the importance of rehabilitation and nutrition after burn injury, they also highlight potential disparities in the quantity or quality of services available to burn survivors in poorer countries.

Measurement the 3D temperature distribution in the combustion zone using acoustic tomography and nolinear wavefont tracing

A non-invasive temperature measurement method in three dimensions is proposed to reconstruct the three-dimensional temperature. It relies on the use of nonlinear acoustic travel-time tomography, which incorporates acoustic path tracing, Gaussian kernel function, and modified Tikhonov regularization. Sound signals can be distorted due to large average temperature gradients and oscillatory release of heat in the combustion region. The effective acoustic signal is extracted based on spectral subtraction to evaluate the sound propagation time under distorted signals. The analysis of experimental errors indicates that the proposed acoustic pyrometry method has an average relative error of less than 15% compared to the time-averaged temperature measured by thermocouples. This result verifies the efficacy of the method when it comes to accurately reconstructing the temperature field in the combustion area. The reduction in error is attributed to the consideration of acoustic ray tracing within the proposed method.

Injury Pattern Analysis to Optimize Burn Injury Prevention in the Unhoused Community.

Unhoused patients are an overrepresented group in burn injury, and are a uniquely vulnerable population. Current research focuses on the consequences of homelessness on burn outcomes, with little known about the specific circumstances and behaviors leading to burn injury that may represent specific targets for injury prevention efforts. The burn registry at an urban regional burn center was queried for burn admissions in unhoused adults from 2019 to 2022. Registry data pulled included demographics, urine toxicology, mechanism of injury, and injury subjective history. Subjective injury history was reviewed to determine more specific injury circumstances and activities during which accidental burns occurred. Demographic and mechanistic trends in burn admissions were explored via descriptive statistics. Among 254 admissions for burns from the unhoused community, 58.1% of patients were positive for stimulants on admission. Among accidental injuries (69.7%), common circumstances included preparing food or beverages, cooking or using methamphetamine, smoking cannabis or tobacco, bonfires, and candles. A specific common circumstance was lighting a cigarette while handling accelerants (6.7%). Interventions for stimulant abuse, as well as outreach efforts to educate unhoused patients about situational awareness, safe handling of accelerants, safe smoking practices, and safe cooking practices, may be effective tools in reducing burn admissions in this vulnerable population.

Design study of a 450MW thermal Modified CANDLE fast reactor using helium gas as a coolant

The Modified CANDLE (MCANDLE) burnup scheme divides the reactor core into several regions in an axial or radial direction with equal volume. It works like the CANDLE burnup scheme except that, in the CANDLE burnup scheme, the reactor core is divided into three main regions in the axial direction. Namely, spent fuel, burning region and fresh fuel region. In this study, the design of a modular modified CANDLE fast reactor using helium gas as a coolant has been performed. One of the important roles of a modified CANDLE fast reactor is that it can utilize natural uranium as fuel without the need for enrichment or reprocessing. This type of reactor can be used, including in developing countries, without the nuclear proliferation problem. Using helium gas as a coolant gives hope for a fast reactor due to its properties, such as its less neutron absorption, less radioactive, and as helium is an inert gas, prevents chemical reactions with other materials. The study was performed on a rector with a thermal power of 450MWth. The active core was divided into ten regions with equal volume in radial directions. The refueling scheme has been optimized every ten years of burnup to obtain a good reactor design. In the beginning, the fuel was put in the first region after ten years of burnup was moved to the second region, after another ten years of burnup was moved to the third region and so on until the tenth region where the fuel gets out. The neutronic calculation has been performed using the SRAC (Standard Reactor Analysis Code system). The collision probability method (PIJ) was employed for cell burnup calculation, and CITATION was used for the reactor core design with JENDL 4.0 as the nuclear data library.

Benchmarking GOCART-2G in the Goddard Earth Observing System (GEOS)

Abstract. The Goddard Chemistry Aerosol Radiation and Transport (GOCART) model, which controls the sources, sinks, and chemistry of aerosols within the Goddard Earth Observing System (GEOS), recently underwent a major refactoring and update, including a revision of the emissions datasets and the addition of brown carbon. A 4-year benchmark simulation utilizing the new version of the model code, termed GOCART Second Generation (GOCART-2G) and coupled to the Goddard Earth Observing System (GEOS) model, was evaluated using in situ and spaceborne measurements to develop a baseline and prioritize future development. A comparison of simulated aerosol optical depth between GOCART-2G and MODIS retrievals indicates the model captures the overall spatial pattern and seasonal cycle of aerosol optical depth but overestimates aerosol extinction over dusty regions and underestimates aerosol extinction over Northern Hemisphere boreal forests, requiring further investigation and tuning of emissions. This MODIS-based analysis is corroborated by comparisons to MISR and selected AERONET stations; however, discrepancies between the Aqua and Terra satellites indicate there is a diurnal component to biases in aerosol optical depth over southern Asia and northern Africa. Despite the underestimate of aerosol optical depth in biomass burning regions in GEOS, there is an overestimate in the surface mass of organic carbon in the United States, especially during the summer months. Over Europe, GOCART-2G is unable to match the summertime peak in aerosol optical depth, opposing the observed late fall and early spring peaks in surface mass concentration. A comparison of the vertical profile of attenuated backscatter to observations from CALIPSO indicates the GEOS model is capable of capturing the vertical profile of aerosol; however, the mid-troposphere plumes of dust in the North Atlantic and smoke in the southeastern Atlantic are perhaps too low in altitude. The results presented highlight priorities for future development with GOCART-2G, including improvements for dust, biomass burning aerosols, and anthropogenic aerosols.

Routinely collected burn clinical data in Canada: Determining the knowledge gap

Unlike other developed countries that hold national burn registries to monitor burn injury and care, Canada relies on single-centre secondary datasets and administrative databases as surveillance mechanisms. The objective of this study was to determine the knowledge gap faced in Canada for not having a dedicated burn registry. A comprehensive scoping review was conducted to identify the burn literature that has arisen from secondary datasets in Canada. Literature of all study designs was included with the exception of case reports and cases series. Once data extraction was concluded, a thematic framework was constructed based on the information that arose from nations that hold national burn registries. Eighty-eight studies were included. Twelve studies arose from national datasets, and 18 from provincial databases, most of which were from Ontario and British Columbia. Only seven studies were conducted using a combination of Canadian units’ single-centre datasets. The majority of included studies (58%) resulted from non-collaborative use of single-centre secondary datasets. Research efforts were predominantly conducted by burn units in Ontario, British Columbia, Manitoba and Alberta. A significant number of the included studies were outdated and several provinces/territories had no published burn data whatsoever. Efforts should be made towards the development of systems to surveil burn injury and care in Canada. This study supports the development of a nation-wide burn registry to bridge this knowledge gap.

Cold burn injuries in the United Kingdom: A five-year cohort study of patients presenting to a regional burn unit

AimsTo assess the aetiology, management and outcomes of cold burn injuries presenting to a regional burn unit in the United Kingdom. MethodsRetrospective cohort study of consecutive patients over a five-year period (2018-22). ResultsSixty-two patients (M:F 34:38; median age 23.5 years) were identified. The most common aetiology was aerosol (n=28, 45.2%). Seven (11.5%) injuries were sustained during a social media or peer ‘challenge’ and nineteen (31.2%) were self-harm, of whom five (26.3%) were inpatients on a mental health ward at the time of injury. All ‘challenge’ and self-harm injuries were caused by aerosol. ‘Challenge’ injury patients were younger than those with self-harm (p=.007) and non-intentional injuries (p<.001). A greater proportion of self-harm injuries were in female patients compared to non-intentional injuries (p<.001). Median TBSA was 0.35% (IQR 0.3). Most burns were superficial partial-thickness (n=35, 56.5%), followed by deep-dermal (n=18, 29.0%), full-thickness (n=8, 12.9%), and superficial (n=1, 1.6%). The upper limb was most frequently affected (n=35, 56.5%). Aetiology and whether a non-intentional, ‘challenge’ or self-harm injury did not affect TBSA (p=0.776 & p=0.364) or depth (p=0.353 & p=0.381). Five (8.1%) patients underwent autografting. The median time to healing was 17 days (range 7-45, IQR 22.75). Follow-up ranged from 1-173 weeks. ConclusionsThe incidence of cold burns has increased when compared with previous literature. A disproportionate number of cold burns are self-inflicted using aerosols, either as self-harm or due to social media or peer ‘challenges’. Other emerging aetiologies include non-intentional skin contact with nitrous oxide containers during its recreational use.

A Comparison of Teleburn to In-Person Consultation of Pediatric Patients in a Children's Emergency Department.

Pediatric burn care is an essential component of emergency care and there are disparities in access to regional burn centers. Teleburn is a tool that enables providers without a certified burn center to provide photos of a burn to experts and receive recommendations. The purpose of this study is to evaluate the effectiveness of a Teleburn system to the in-person consultation regarding burn infection rate, clinic follow-up rate, postburn admission rate, and 72-h bounce back rate. Data were collected from December 2019 to March 2022 through the electronic medical record. A total of 416 patient encounters that met the criteria were analyzed. A non-inferiority study was designed comparing proportional outcomes of Teleburn initial visits to emergency department visits regarding burn infection rate, clinic follow-up rate, postburn admission rate, and 72-h bounce back rate. The data were compared with a difference of greater than 10% being considered inferior. No differences were identified in rates of readmission-1.67% difference (95% CI -27%< x < 23.8%) and return within 72 h-0.7% difference (-18.4%< x < 19.7%). Teleburn patients were 12.6% less likely to follow-up (2.7%< x < 22.40%). Only one infection was identified, which was insufficient to conclude non-inferiority. While convenient, Teleburn consult could not be demonstrated to be non-inferior to in-person consultation. No differences in infection rates were identified, and differences in readmission and return were clinically insignificant. This study demonstrates that Teleburn may be effective and feasible for regional burn centers if follow-up can be improved.

Aerosol characterization and peculiarities of source apportionment in Moscow, the largest and northernmost European megacity

High population and a wide range of activities in a megacity lead to large-scale ecological consequences which require the assessment with respect to distinct characteristics of climate, location, fuel consumption, and emission sources. In-depth study of aerosol characteristics was carried out in Moscow, the largest megacity in Europe, during the cold period (autumn and winter) and in spring. PM10 chemical speciation based on carbonaceous matter, water-soluble ions, and elements was carried out to reconstruct the PM mass and evaluate the primary and secondary aerosol contribution. For the whole study period organic matter, mineral dust, and secondary inorganic/organic accounted for 34, 24, and 16 % of PM10 mass, respectively. PM10, OC, and EC approached a maximum in spring and decreased in winter. Mineral dust seasonal fraction increased from spring (17 %) to autumn (32 %), and then decreased in winter (22 %). Secondary inorganic aerosols (SIA) in opposite showed the maximum 27 % in winter. K+ marked the residential biomass burning in the region surrounding a megacity in spring and autumn, agriculture fires in spring. In winter primary aerosol contribution dropped down 56 % while secondary approached practically equal 44 %. Source factors with the relative contributions are quantified, namely city dust (26 %), traffic (23 %), industrial (20 %), biomass burning (12 %), secondary (12 %), and de-icing salt (7 %); they were significantly varying between the cold heating period and springtime. The relevance of sources to meteorological parameters and mass transportation is investigated by using both bivariate polar plots and Lagrangian integrated trajectory (HYSPLIT) model. Trajectory clustering demonstrates regional sources being crucial contributors to PM10 pollution. Aerosol speciation and source apportion factors identify the differences of the Moscow urban background among large European and Asian cities due to northern climate conditions, fast construction, long-range transport from industrial-developing area surrounding a city, regional biomass burning preferably in spring and autumn, and winter road management.

Characteristics and risk factors for electrical burn injuries: a study based on World Health Organization Global Burn Registry

ObjectiveElectrical burn injuries (EBIs) represent an important subset of burn injuries, but the information on them from the global level is limited. We aimed to investigate the characteristics and risk factors for EBIs reported to the World Health Organization Global Burn Registry. MethodsPatients with EBIs and non-EBIs were identified from the registry. Patient demographics, income of the country, setting of the injury occurred, and outcomes were described and compared. Multivariable analysis was performed to identify risk factors associated with the EBIs and their outcomes. ResultsOf the 9276 patients, 814 (8.8%) were grouped as EBIs. EBIs patients had a median age of 28 years, and they were predominantly males (89.2%). EBIs were more likely to occur in lower-middle- and low-income countries (60.9% versus 43.4%) and in an occupational setting (49.1% versus 6.7%) than the non-EBIs. Older age, male, lower-income, and occupational and public setting were risk factors for EBIs. For EBIs patients, adolescents and young adults, those from low-middle and low-income countries, and those injured by high-voltage electricity were more likely to have more than 15% of the total body surface area. In addition, those from low-middle and low-income countries and those injured by high-voltage electricity were more likely to die. ConclusionThe characteristics of EBIs are significantly different from that of non-EBIs. To prevent EBIs and avoid unpleasant outcomes, particular attention should be given to adolescent boys and young adult men who are employed in electrical jobs in lower-income countries.

Factors associated with emergency department disposition among burn injury patients: Analysis of prehospital and emergency care characteristics using South Asia Burn Registry (SABR) data

IntroductionImprovement in burn injury data collections and the quality of databanks has allowed meaningful study of the epidemiologic trends in burn care. The study assessed factors associated with disposition of burn injury patients from emergency department accounting for pre-hospital care and emergency care. MethodsThis prospective observational pilot study of the South Asia Burn Registry project was conducted at selected public sector burn centers in Bangladesh and Pakistan (September 2014 – January 2015). All age groups with an initial presentation to the burn centers were enrolled. Descriptive and regression analysis is presented. ResultsA total of 2749 patients were enrolled. The mean age was 21.7 ± 18.0 years, 55.3% were males, and about a quarter were children < 5 years. About 46.9% of the females were housewives. Scald burns were common among children (67.6%) while flame burns were common among adults (44.3%). About 75% of patients were brought in via non-ambulance mode of transport. More than 55% of patients were referrals from other facilities or clinics. The most common first aid given pre-hospital was the use of water or oil. About 25% were admitted for further care. The adjusted odds of being admitted compared to being sent home were highest for children < 5 yrs, those with higher total body surface area burnt, having arrived via ambulance, scald and electrical burn, having an associated injury and inhalational injury. ConclusionThe study provides insight into emergency burn care and associated factors that influenced outcomes for patients with burn injuries.

Mathematical modelling of a slow flameless combustion of a two-dimensional paper

We present a mathematical model for the slow combustion (smoldering) of a two-dimensional sheet of paper. We describe the evolution of the char region, and we investigate the effects of an orthogonal air flow on the shape of the combustion front. The mathematical formulation consists in a set of two nonlinear PDEs for the temperature and the oxygen concentrations coupled with one ODE for the cellulose concentration. The (dimensionless) problem is solved numerically by means of a spectral collocation scheme based on Chebyshev polynomials. Our results show that the Péclet and the Lewis number strongly influence the shape of the ignition front and that the advancement of the combustion front does not occur if advection and diffusion are neglected (zero Péclet and Lewis numbers). In particular we observe that the burning region and the ignition front are strongly influenced by the velocity of the airflow and by the mass and heat transport phenomena due to diffusion and advection. We shall see that the increasing of the ratio between the convective and diffusive characteristic times (Péclet number) and the decreasing of the ratio between the mass and heat diffusive characteristic times (Lewis number) have a “flattening effect” on the combustion front.

Evaluation of Mixing Effect on Coupled Heat Release and Transfer Performance of a Novel Segregated Solid Rocket Motor

The effect of mixing on coupled heat release and transfer performance of a novel segregated solid motor is numerically evaluated with a transient two-dimensional combustion model. The results show that vortex structures are formed and evolved in the combustion chamber. Quantitative calculation of the mixing effect shows the inhomogeneous distribution of oxidant and fuel species. The well-mixing area is located in a narrow belt-like coupled combustion region near the burning surface of the propellant. Heat transfer coefficient decreases greatly due to lower combustion reaction rate and enlarged flow channel area. Heat transfer coefficients near the two ends of the propellant grain are higher than other parts due to the influence of vortex mixing. Raising the inlet mass flow rate leads to enhanced mixing and heat transfer, which results in a lower temperature and regression rate of the propellant with combustion time. Temperature and oxidation rates of H2 and CO are unevenly distributed in the boundary layer of coupled combustion. Increasing the mass flux of inlet oxidizer gas leads to a higher combustion heat release rate. Therefore, the gas-phase temperature increases significantly. The heat release rate reaches the maximum near the ends of the propellant grain, where vortex mixing strengthens the coupled combustion process in the motor.

Factors Predicting Burn Surgery Operative Time in a Middle-Income Country Regional Burn Service.

Access to theater is essential for the surgical management of deep burns. This is a scarce resource in low-middle-income countries. It underpins the importance of optimizing theater time. We sought to look at specific factors and their influence on operative time in minor to moderate burn surgery. This knowledge can assist teams where theater planning and optimization may be beneficial in resource-limited settings. Operative records between January and December 2018 at the Regional Hospital were analyzed. Data fields included age, gender, TBSA of burn, surface area burn operated on, intraoperative position change, seniority of surgeon, presence of an assistant, inclusion of special areas, predicted operative time, and actual operative time. Operative records for 265 patients were analyzed, with a median operative time of 40 minutes (interquartile range 25-64). Overall factors that predict longer operating time are larger total body surface area burn, larger surface area burn operated on, an operation involving at least one special area, number of special areas operated on, position change, presence of an assistant, and longer predicted operative time. Total percentage burn, operated percentage, special areas to be operated, and position change are overall factors to be considered when planning a burns list for the nonspecialist burn surgeon. This knowledge may be useful for an inexperienced surgeon to understand and aid in the effective utilization of limited operative time available for the surgical management of deep burns in resource-limited settings.

Development of information support of the decision-making management system for emergency prevention based on distance video systems

The possibilities of identifying combustion from the mobile observation point located on an unmanned aircraft are considered. A qualifying sign of frequency fluctuations in the region of combustion was derived and presented in the form of a program filter of vyvyl-analysis in the temporary area. The frequency characteristics of the detectors and experimental data used in fire detectors were compared. A stable correlation was obtained confirming the conformity of the hypothesis existing tested data. It is proposed as a sign of defining burning to use the frequency of the color of the color of the pixels from the gama of fire to the color of the underlying surface. It is experimentally determined that combustion corresponds to the range from 12 to 30 Hz. The work takes into account the dynamic location of the observation point on an unmanned aircraft. The boundary conditions of the operation of the aviation system allowing to obtain relevant data for analysis are described.

Internal flame structures of thermo-diffusive lean premixed H2/air flames with increasing turbulence

Turbulent flow fields, instantaneous flame structures, and internal thermo-chemical states of lean premixed hydrogen/air jet flames at an initial equivalence ratio of 0.4 are experimentally investigated by simultaneous laser-induced fluorescence of hydroxyl radicals (OH-LIF) and particle image velocimetry (PIV), and quasi-simultaneous 1D Raman/Rayleigh and 2D Rayleigh scattering measurements over a range of Karlovitz numbers (Ka) from 50 to 730. At low Ka, intense burning characterized by elevated local equivalence ratio, high water mole fraction (XH2O), and super-adiabatic flame temperature is mainly observed in post-flame regions surrounded by positively curved flame surfaces, where the fast diffusive hydrogen is locally focused. The flame features stronger differential diffusion and curvature effects than that in the planar laminar flame, which indicates that both molecular and turbulent mixing play significant roles, and thermo-diffusive instabilities have synergistic interactions with turbulence at low turbulence level. With increasing Ka, the burning intensity in corresponding regions is weakened, even though the flame surface is more disturbed by the turbulence. At the highest Ka, no intense burning region is observed in the jet flame as the turbulent transport dominates over the molecular diffusion. In the temperature domain, the conditional means of hydrogen mole fraction (XH2) and local equivalence ratio feature effects of diffusive instabilities with broad distributions at low-Ka conditions. Elevated XH2O and local equivalence ratios with super-adiabatic flame temperatures are observed, which is attributed to differential diffusion in hydrogen-containing mixtures and the fuel focusing effect near positively curved flame surfaces. At high Ka, the XH2 shows a more linear decreasing trend and the local equivalence ratio profile becomes flatter over temperature with a narrower distribution, indicating the dominance of turbulent mixing.

The circumferential force on a cylindrical rotating detonation engine

Rotating detonation engines (RDEs) utilize single or multiple detonation waves continuously traveling at velocities ranging from 1 to 3 km/s. These waves induce a strong swirl near the inlet surface, generating circumferential shear stress on the surface of the combustion chamber. This stress works as torque in the axial direction. This characteristic is promising for turbine applications. However, for long-term operation, such applications require reduction in the thermal damage risk. While annular RDEs, which have an inner wall surface, involve the thermally independent center body, cylindrical RDEs have no center body and more suitable. On the other hand, the contact surface exposed to the swirling flow is smaller. This study evaluated the differences in combustion mode and circumferential phenomena between annular and cylindrical RDEs through the measurement of thrust and torque. The results showed that the torque generated by the cylindrical RDE was as large (around 0.1 Nm) as that generated by the annular RDE under mass flow rate of approximately 0.05 kg/s. This was due to the stronger swirl derived from the 16 % faster detonation waves. In addition, the presence of strong detonation combustion around the outer wall of the cylindrical RDE was indicated through the control surface method. When a fuel‒oxidizer was supplied to the strong detonation combustion region, the detonation waves reached velocities around the Chapman–Jouguet value, with the maximum torque in this study being 0.127 Nm. From these results, the effect of the propagation mode of detonation waves on the circumferential flow and force was evaluated. The results indicated that the increase of detonation wave velocity enhanced the circumferential flow and force. The tendency to increase became large as the number of the detonation waves increased.