Simulated Values Research Articles

Mechanical and environmental performance of structural concrete with coal gangue fine aggregate

Using coal gangue sand as fine aggregate is a feasible solution for the sustainable development of construction engineering. The mechanical and environmental properties of the gangue fine aggregate concrete-filled steel tube (GFACFST) and reinforced gangue fine aggregate concrete (RGFAC) with different gangue fine aggregate replacement ratios (rGFA) were investigated experimentally and numerically. The results showed that the GFACFST and RGFAC with various rGFA showed similar failure modes. The stiffness of the stubs decreases with the increase in rGFA. The ultimate strength of the GFACFST and RGFAC decreases by 3.8 % and 12.4 % respectively when rGFA is 100 %. The ductility of GFACFST shows an ascending tendency with the increase in rGFA, resulting from the increase in the confining effect of the steel tube on the core concrete. The stress-strain constitutive model of gangue fine aggregate concrete is proposed for numerical modeling. A design method for the bearing capacity of GFACFST and RGFAC is proposed by considering various gangue fine aggregate replacement ratios of which results differ from the tested and simulated values in the range of ±5 % and ±11 %. The life cycle assessment analysis shows that the environmental impact of GFACFST is less than that of RGFAC at the same axial compressive strength. The improvement of the mechanical-environmental performance efficiency by increasing cross-section diameter is more significant than that by increasing steel ratio.

Exploration of quality criteria for the detection of peak inspiratory flow under different resistance conditions.

At present, robust quality criteria and methods for the assessment of Peak inspiratory flow meter performance are lacking. A standard flow-volume simulator for quality control analyses of an inhalation assessment device was utilized with different simulated resistance levels in order to propose a quality testing method and associated standard for this device type. A standard flow-volume simulator was utilized to assess the performance of an In-Check DIAL® (Device I) and an intelligent inhalation assessment device (Device P) at a fixed volume and flow rate. Indices used to evaluate these two instruments included repeatability, accuracy, linearity, and impedance. Both devices exhibited good repeatability (<± 3 L/min). The difference between test results and standard simulator values for Device P was less than ± 5 L/min at resistance level R1 but higher than ± 5 L/min at resistance levels R2-5, while Device I were greater than 5 L/min at all resistance levels. The relative error for Device P was <± 10% at resistance levels R1, R2, and R4, but > 10% at resistance levels R3 and R5. The relative error values for Device I at all five resistance levels were > 10%. Device P passed the linearity test at the R2 resistance level, while Device I partially passed the linearity test at all five resistance levels. Standard monitoring methods and standards provide a valuable approach to the more reliable clinical assessment and application of these instruments.

Chloride ion diffusion performance of concrete and its influence on scour resistance

Hydraulic structures are affected by many factors, and chloride ions can significantly reduce the service life of concrete. In this paper, the erosion test of chloride ion erosion is studied, the damage characterization is carried out by two-dimensional and three-dimensional characterization methods, and the numerical simulation analysis is carried out. The results show that when the water cement ratio (w/c) is 0.3, 0.4 and 0.5, the grinding depth of concrete surface reaches 21 mm, and the chloride ion concentration is stable. With the increase of w/c, the porosity increases, especially the harmful pores have the greatest influence on ion erosion. Chloride ion erosion reduces the scour resistance of concrete. When the w/c decreases from 0.5 to 0.4, the influence of ions on the scour resistance of concrete is weakened by 5.3%. Under 0.5 w/c, the exposed area of aggregate on the surface of concrete increases by 15.6%, and the average erosion rate of concrete decreases by 3.3%, 5.0% and 16.0%. With the increase of chloride ion diffusion depth, the chloride ion concentration is in good agreement with the simulated value. The interfacial transition zone around the coarse aggregate promotes ion diffusion, so that the ion concentration of the concrete surface reaches the peak. Concrete with a w/c of 0.3 has a longer life under the same conditions.

Implementation of highly isolation OLR: based microstrip full-duplex Tx/Rx antenna systems with low insertion loss for contemporary wireless system applications

This paper presents a Highly Isolation open-loop resonators (OLR)—based microstrip full-duplex Tx/Rx antenna systems with low insertion loss for contemporary wireless system applications. Through a T-junction combiner, the proposed diplexer is accomplished by combining two OLR—based band-pass filters tuned at two distinct frequencies. The system is implemented on a Rogers TMM4 substrate with a loss tangent of 0.002, a dielectric constant of 4.7, and a thickness of 1.52 mm. The suggested full duplex has dimensions of (90 × 70) mm2. It achieves a modest frequency space ratio of R = 0.1646 in both transmit and receive modes by having two resonance frequencies of {f}_{t} = 2.191 GHz and {f}_{r} = 2.584 GHz, respectively. The simulated structure displays good insertion losses (IL) of approximately 1.2 dB and 1.79 dB for the two channels, respectively, at fractional bandwidths of 1.24% at 2.191 GHz and 0.636% at 2.584 GHz. The simulated isolation values for 2.191 GHz and 2.584 GHz are 53.3 dB and 66.5 dB, respectively.

Parametric study of battery module cooling: Configuration optimization using response curve method

Recently, cylindrical lithium-ion battery cells have been widely used in electric vehicles due to efficient automated production and cheap kilowatt-hour capacity. For optimal operation of a cell, the internal temperature of the cell should be maintained within the range of 15–35 °C by employing suitable cooling mechanism. This study comprehensively compares multiple air-cooling configurations specifically designed for lithium-ion battery three-series and three-parallel (3S3P) modules using. The methodology involves an experimental phase to measure the parameters of Bernardi's equation, essential for calculating heat generation with consideration of both Joule's heat and entropic heat. Subsequently, a numerical simulation using Ansys Fluent examines battery heat generation within the 3S3P modules, employing diverse air-cooling configurations. Each configuration undergoes simulation with the aid of design of experiments and parametric analysis, allowing the observation of cooling behavior across various input parameters. To ensure reliability of simulation, the cooling of the unit cell module is simulated under similar conditions. The comparison between these simulated results and experimental values is conducted to validate the accuracy of the overall analysis methodology. The heat measurements indicated a unit cell heat output of 0.9028 W at an average rate of 0.85C. Among the investigated air-cooling configurations, the SIDO (Single Input Double Output) arrangement stood out as the most effective in maintaining a consistently lower average cell temperature, as determined through the application of the response curve method. This study emphasizes the importance of air-cooling design for improving the performance and safety of lithium-ion battery modules used in electric vehicles.

Evaluate WRF-based Lightning Potential Index (LPI) lightning parameterization over Sri Lanka during second inter-monsoon in 2018

It is important to develop accurate and reliable lightning prediction system that can be contributed towards the safety of life, both concerning forecasting for the public safety and safety of aviation and electrical power. This study aims to evaluate WRF-based Lightning Potential Index(LPI) lightning parameterization and its applicability for predicting lightning over Sri Lanka during the second inter-monsoon. The WRF-ARW model 3.9.1 was used to produce predictions for three lightning events with various physical parameterization schemes with two nested domains with a resolution of 12km and 4km respectively. The model simulated LPI values were evaluated using the Earth Networks Global Lightning (ENGLN) dataset. Results show corresponding lightning simulations were produced with spatial distribution aligned with ground-based lightning data. Results consistently show a high correlation of the LPI index with an hourly CG flash rate over the three cases. Moreover, the WRF model was able to capture the lightning using LPI in Sri Lanka, suggesting that it can be used operationally to predict lightning potential region.

Investigation on the Dynamic Pressure Effect of Clearance Oil Film at a Stepped Hydrostatic Thrust Bearing Working in Heavy Loading Duty

The dynamic pressure effect of the clearance oil film of stepped hydrostatic thrust bearing is studied by taking the double rectangular cavity oil cushion as an example. According to the hydrodynamics theory, the dynamic pressure of lubricating oil film in different clearance height regions is theoretically deduced and calculated. The dynamic pressure effect of the clearance oil film in the stepped hydrostatic thrust bearing is studied through the combination of theoretical calculation, simulation, and experimental verification. It is found that the experimental value of the dynamic pressure is between the theoretical value and the simulated value, which is basically not affected by the load. In the speed range of 0 r/min–200 r/min, compared with the viscosity of lubricating oil, the speed is the main factor affecting the dynamic pressure of the oil film of the stepped hydrostatic thrust bearing. The dynamic pressure value of the clearance oil film increases in a stepped fashion along the radial direction of the double rectangular cavity oil cushion. The dynamic pressure value has an obvious upward trend at the junction of the circumferential right oil cavity and the sealing edge and then decreases to 0 after reaching the peak value.

Maximum likelihood outperforms binning methods for detecting differences in abundance size spectra across environmental gradients.

Individual body size distributions (ISD) within communities are remarkably consistent across habitats and spatiotemporal scales and can be represented by size spectra, which are described by a power law. The focus of size spectra analysis is to estimate the exponent ( ) of the power law. A common application of size spectra studies is to detect anthropogenic pressures. Many methods have been proposed for estimating most of which involve binning the data, counting the abundance within bins, and then fitting an ordinary least squares regression in log-log space. However, recent work has shown that binning procedures return biased estimates of compared to procedures that directly estimate using maximum likelihood estimation (MLE). While it is clear that MLE produces less biased estimates of site-specific λ's, it is less clear how this bias affects the ability to test for changes in λ across space and time, a common question in the ecological literature. Here, we used simulation to compare the ability of two normalised binning methods (equal logarithmic and log2 bins) and MLE to (1) recapture known values of , and (2) recapture parameters in a linear regression measuring the change in across a hypothetical environmental gradient. We also compared the methods using two previously published body size datasets across a natural temperature gradient and an anthropogenic pollution gradient. Maximum likelihood methods always performed better than common binning methods, which demonstrated consistent bias depending on the simulated values of . This bias carried over to the regressions, which were more accurate when was estimated using MLE compared to the binning procedures. Additionally, the variance in estimates using MLE methods is markedly reduced when compared to binning methods. The error induced by binning methods can be of similar magnitudes as the variation previously published in experimental and observational studies, bringing into question the effect sizes of previously published results. However, while the methods produced different regression slope estimates, they were in qualitative agreement on the sign of those slopes (i.e. all negative or all positive). Our results provide further support for the direct estimation of and its relative variation across environmental gradients using MLE over the more common methods of binning.

Modified (Spherical and Cylindrical) Permeation Diffusion Model Considering Deep Bed Filtration Effect

The study of the slurry reinforcement mechanism is mainly focused on the interaction between slurry and soil. The seepage effect of the slurry always exists no matter what way the slurry interacts with the soil around the pile. In the process of slurry diffusion, the porosity of the soil, the permeability of the slurry, and the slurry pressure vary due to some cement particles being blocked by the soil particle skeleton. Therefore, the study of the slurry filtration effect is of great significance for predicting the permeation and diffusion law of slurry. In this paper, a macroscopic linear filtration model was introduced and the changes of slurry properties in the permeation diffusion process were considered. Firstly, a spherical (cylindrical) permeation diffusion model, which takes the linear filtration effect and the variation of slurry viscosity into account, was derived based on the conservation of mass. Furthermore, in order to more accurately reflect the influence of the filtration effect on the slurry permeation diffusion model, a polynomial nonlinear filtration model was proposed, and the numerical solution for the permeation diffusion model was derived using finite difference and finite element methods. Finally, the numerically simulated values, the measured values, and the values from the spherical permeation diffusion model that does not consider slurry viscosity variations were compared. The results indicate that the grout pressure is inconsistent with the measured value without considering the effect of the filtration. The initial grouting pressure calculated by the model in this paper is slightly larger, and the required grouting pressure over time is greater than that without considering the filtration effect, regardless of whether the grout diffuses in a spherical or cylindrical manner. The results of this study can contribute to a better understanding of grouting engineering and provide some theoretical guidance for actual grouting.

On the double-sided shock diffractions in quiescent and supersonic crossflows

Shock diffraction is a widespread phenomenon in aerospace applications, such as shock tunnel nozzle and jet exciter exit, impacting their performance significantly. This paper focuses on the transient evolution of double-sided shock diffraction in both quiescent and supersonic crossflows by unsteady numerical simulations. The characteristics of the shock wave and the vortex are revealed. In the quiescent flow, the double-sided shock diffraction exhibits remarkable symmetry. The diffracted shock retains a self-similar nature, but its intensity distribution displays non-uniform characteristics, which gradually weakens from the center to both sides. The vortices on both sides also exhibit symmetrical behavior, with their trajectory behaving in linear tendency. When the supersonic crossflow interacts with the diffracted shock, an upward-moving separation shock and an asymmetric diffracted shock are generated. The vortices remain confined beneath the boundary layer and exhibit different shapes. Moreover, due to the rapid motion of the separation shock, the relative Mach number is introduced into the free-interaction theory (FIT) to predict the shock angle of the separation shock. The F(x¯) values corresponding to the separation point and pressure plateau are determined to be 3.04 and 4.68, respectively. The results evaluated by modified FIT show a good agreement with the values of simulation and experiment.

Effects of compression ratio on the performance and emission levels of a CI engine fueled with safflower oil methyl ester through an engine simulation approach

In recent years, the research community has shown significant interest in the potential of biodiesel as a renewable alternative to conventional fossil-based fuels. Nevertheless, the experimental investigation of the effects of diverse biodiesel formulations on internal combustion engines demands a significant investment of time and financial resources. Consequently, the numerical alternative methodologies are advocated as a viable substitute for practical experiments. Numerical simulations offer the opportunity for a meticulous examination of the characteristics of internal combustion engines under diverse operational conditions and various biodiesel blends, thereby optimizing efficiency and cost-effectiveness. This study focused on the simulation of performance and emission characteristics of a diesel engine running on safflower (Carthamus tinctorius L.) oil methyl ester (SOME) and traditional diesel fuel using AVL simulation software. Furthermore, the simulation results were compared with a laboratory study carried out under identical conditions. The simulated engine underwent testing across various compression ratios (CRs) (ranging from 12:1 to 18:1) and engine loads (from 25% to full load) while sustaining a consistent speed of 1500 rpm. The simulation findings revealed that the engine exhibited its highest BSFC as 0.495 kg/kWh with SOME fuel, at a CR of 12:1, modestly lower than the corresponding experimental observation of 0.520 kg/kWh. Concurrently, the lowest value of BSFC, recorded as 0.267 kg/kWh with diesel fuel and a CR of 18:1, demonstrated a marginal deviation from the experimental result of 0.281 kg/kWh. Additionally, SOME fuel usage was correlated with diminished CO and HC emissions. The experimental findings indicated the lowest value of CO and HC emissions, as 0.14% and 21.7 ppm, respectively, with SOME fuel at a CR of 18:1, marginally below the simulation-derived values of 0.13% and 20.8 ppm. Conversely, diesel fuel at a CR of 12:1 exhibited maximal CO and HC emissions, registering 0.38% and 199.5 ppm, respectively, in the experimental study. In comparison, the simulation values were slightly lower at 0.36% and 194.1 ppm. Moreover, the experimental investigation identified SOME fuel as yielding the highest CO2 emission, reaching a peak of 11.9% under a CR of 18:1, while the simulation showed a slightly lower value of 11.2%. In contrast, diesel fuel at a CR of 12:1 resulted in the lowest CO2 emission at 3.85% in the experiment, with the simulation reporting a slightly reduced value of 3.77%. Regarding NOx emissions, the experiment recorded the peak at 1687 ppm with SOME fuel and a CR of 18:1, slightly surpassing the simulation’s value of 1643 ppm. Conversely, the experimental data indicated the lowest NOx emission as 103 ppm with diesel fuel and a CR of 12:1, with the simulation suggesting a slightly lower value of 98.2 ppm under identical conditions. The simulation results demonstrated favorable concordance with experimental findings, notably strengthening with an increase in CR.

Synthesis, Crystal structure, weak interactions and Optical Properties of An Organic Charge-Transfer Compound―Benzyl 2-Aminopyridinium Picrate

In this work, a new organic charge-transfer compound, 1-benzyl 2-aminopyridinium picrate, [Bz-2-NH2Py][PIC](1), was prepared and characterized by single crystal X-ray diffraction (SC-XRD), power X-ray diffraction (PXRD), FT-IR, 1HNMR and Raman spectroscopy. The title compound crystallizes in monoclinic system with space group P2(1)/c, and contains one [Bz-2-NH2Py]+ cation and one [PIC]− anion. The cations stack into a columnar structure through C–H···π interactions and the N-H∙∙∙O and C-H∙∙∙O hydrogen bonds between the anions and cations stabilize the crystal stacking of [Bz-2-NH2Py][PIC](1). The frontier molecular orbitals HOMO and LUMO were computed with DFT (using B3LYP/6-31Gþ(d, p) basis set) approach to understand the chemical reactivity and kinetic stability of the title compound. The geometrical parameters obtained from XRD experiment are good in agreement with the simulated values from single crystal structure. In addition, the organic material shows two main emission peaks about 390 and 469 nm upon excitation at 241 nm in solid state at room temperature. Hirshfeld surface analysis was performed to quantify the contributions of the different intermolecular interactions.

Enhancing Anomaly Detection in Pedestrian Walkways using Improved Sparrow Search Algorithm with Parallel Features Fusion Model

Anomaly detection in pedestrian walkways is a vital research area, widely employed to enhance the safety of the pedestrians. Because of the widespread usage of the video surveillance systems and the increasing number of captured videos, the conventional manual examination of labeling abnormal events is a laborious process. Therefore, an automatic surveillance system to accurately detect anomalies becomes essential among computer vision researchers. Presently, the development of deep learning (DL) models has gained significant interest in different computer vision processes namely object classification and object detection, and these applications were depending on supervised learning that required labels. This article develops an Improved Meta-heuristic with Parallel Features Fusion Model for Anomaly Detection in Pedestrian Walkways (IMPFF-ADPW) method. The main aim of the IMPFF-ADPW approach is to recognize the existence of anomalies in pedestrian walkways. To obtain this, the IMPFF-ADPW method applies a joint bilateral filter (JBF) for the process of noise removal. Besides, a parallel fusion process comprising NasNet Mobile and Darknet-53 models can be utilized for feature extraction. For the anomaly detection method, the deep autoencoder (DAE) model is applied and its hyperparameters are finetuned by using an improved sparrow search algorithm (ISSA). A wide of experimental outcomes can be applied to the UCSD database to illustrate the betterment of the IMPFF-ADPW methodology. The simulation values indicated the enhanced performance of the IMPFF-ADPW method over other existing techniques.

Simulation study of drag force characteristics of nanoparticles in transition regime

Transport properties of nanoparticles in gases have many practical applications, such as aerosol science, combustion, and micro- and nano-scale fabrication. A nanoparticle moving in a fluid is expected to experience a drag force, which determines the transport property of the particle. According to the Einstein relationship, the diffusion coefficient of a particle is inversely proportional to the drag force coefficient. However, in the transition regime, it is usually difficult to evaluate the drag force of suspended particles. A typical method is to extend the asymptotic solution of the free molecular or continuum limit to the transition regime. According to the gas kinetic theory, Li and Wang proposed a theoretical expression for drag force on nanoparticles in the free molecular regime, which is then extended to the entire range of Knudsen number following a semi-empirical approach [Li Z G, Wang H 2003 &lt;i&gt;Phys. Rev. E&lt;/i&gt; &lt;b&gt;68&lt;/b&gt; 061207]. For nanoparticles, it is necessary to verify the theoretical predictions since the gas-particle non-rigid-body interactions must be taken into account. In this work, the drag force on nanoparticle in the transition regime is investigated by using molecular dynamics (MD) simulation. To evaluate the drag force, a harmonic potential is used to the nanoparticle to constrain its Brownian motion in our MD simulation. In the steady state, the drag force can be obtained by the balance between the drag force and harmonic force. It is found that the gas-particle non-rigid-body interaction has a significant influence on the drag force of nanoparticle. For weak gas-solid coupling, the MD simulation results can be in good agreement with the prediction of Li-Wang theory. However, for strong coupling, there exists significant discrepancy between the MD simulation results and the theoretical results. Due to the gas-solid intermolecular interactions, gas molecules can be adsorbed on the nanoparticle surface, and after a time period, they may be re-emitted from the surface when they gain sufficient kinetic energy. Therefore, an adsorption-desorption equilibrium and an adsorption layer can be established on the particle surface. The adsorption layer enlarges the collision cross-sectional area and enhances the momentum transfer between gas molecules and the particle, and thus the drag force increases. This can explain the inconsistencies between the theoretical results and MD simulations. In this work, we introduce an adsorption ratio to evaluate the thickness of the adsorption layer. Then, the effective particle radius can be defined by the sum of particle radius and the thickness of the adsorption layer. By using the effective particle radius, the simulation values are in very good agreement with the theoretical predictions. The results of this work provide insights into the applications of nanoparticles in aerosol science.

The value of virtual simulation for pre-operative planning in Rhinoplasty

The value of virtual simulation for pre-operative planning in Rhinoplasty

Biomolecular interactions on densely coated nanoparticles: a single-molecule perspective.

DNA-modified gold nanoparticles (AuNPs) play a pivotal role in bio-nanotechnology, driving advancements in bio-sensing, bio-imaging, and drug delivery. Synthetic protocols have focused on maximizing the receptor density on particles by fine-tuning chemical conditions, particularly for DNA. Despite their significance, the understanding of hybridization kinetics on functionalized AuNPs is lacking, particularly how this kinetics depends on DNA density and to what extent it varies from particle-to-particle. This study explores the molecular mechanisms of DNA hybridization on densely coated AuNPs by employing a combination of single-molecule microscopy and coarse-grained molecular dynamics simulations providing a quantification of the molecular rate constants for single particles. Our findings demonstrate that DNA receptor density and the presence of spacer strands profoundly impact association kinetics, with short spacers enhancing association rates by up to ∼15-fold. In contrast, dissociation kinetics are largely unaffected by receptor density within the studied range. Single-particle analysis directly reveals variability in hybridization kinetics, which is analyzed in terms of intra- and inter-particle heterogeneity. A coarse-grained DNA model that quantifies hybridization kinetics on densely coated surfaces further corroborates our experimental results, additionally shedding light on how transient base pairing within the DNA coating influences kinetics. This integrated approach underscores the value of single-molecule studies and simulations for understanding DNA dynamics on densely coated nanoparticle surfaces, offering guidance for designing DNA-functionalized nanoparticles in sensor applications.

Molecular dynamics simulation and experimental study of the rheological performance of graphene lubricant oil

The microscopic molecular motion behavior between graphene and the liquid lubricant oil affects the rheological and frictional behavior of the nano-lubricant. However, the effect of graphene on the rheological behavior of industrial #3 lubricant oil has not been revealed. Thus, molecular dynamics (MD) and experimental study are used to investigate the effect of graphene concentration, size, temperature, and shear rate on the viscosity, mean square displacement (MSD), and density of graphene lubricant oil are investigated. The results show that the viscosity of GLO increases with the increase of graphene concentration and decreases with the increase of temperature (293 K–330 K). The MSD of graphene lubricant oil decreases with the increase of graphene size and increases with the increase of temperature. It is worth noting that graphene lubricant oil with 3G has the maximum value of MSD, which means the graphene has the best diffusion performance at this concentration. Compared to the base oil, the simulation and experiment viscosity values of the GOL with 3G increased by 22.9 % and 47.6 %, respectively. The GOL has the characteristics of a Newtonian fluid. This study can provide a reference for the application of graphene lubricant oil in industry.

Effect of macular pigment optical density on Yellow‐Blue and Red‐Green colour discrimination

The macular pigment (MP) absorbs preferentially short‐wavelength light and its narrow spectral absorption curve overlaps mostly the spectral responsivity function of S‐cones, although the M‐ and L‐cones are also affected. The MP is restricted to the centre ~14° disc region of the retina with a peak optical density (OD) at the centre in the range 0 to 1 log units. Although the macular pigment optical density (MPOD) decreases rapidly with increasing eccentricity, carotenoid supplementation studies reveal a large uptake of lutein and zeaxanthin, particularly in the parafoveal region and covering the centre ~6° to 8° of the fovea (doi: 10.1111/j.1475‐1313.2006.00386.x).Since the MP contributes to the reduced excitation of S‐cones, it is of interest to examine the effects MP may have on colour vision, particularly when ‘blue‐blocking’ lenses are also involved. We studied the relationship between MPOD and red/green (RG) and yellow/blue (YB) colour thresholds by measuring the spatial distribution of the MP in normal trichromats using the Macular Assessment Profile (MAP) test (doi: 10.1111/j.1475‐1313.2010.00748.x) and the corresponding RG and YB colour thresholds using the CAD test (doi:10.1093/bmb/ldx007).The results show negligible correlation between peak MPOD and YB thresholds and a small, but significant negative correlation with RG thresholds. This observation is of interest since increased MPOD values result in lower RG thresholds. The same experiment was also carried out in subjects with significantly larger amounts of MP following 3 months of supplementation with carotenoids. When averaged over the centre disc region of 2.5° and then over a parafoveal annulus between 2.5° and 4°, the corresponding, mean MP densities show only negligible correlations with RG and YB colour thresholds. To explain these findings, we calculated the expected cone‐contrasts for S‐, M‐ and L‐cones for chromatic displacements defined by the threshold ellipse. The results show that MP absorption of short‐wavelength light has a negligible effect on S‐cone contrast over the whole range of displacement directions associated with the colour threshold ellipse. Repeated calculations with simulated MPOD values up to 1 log unit, produced the same result. More recently, we modelled the effects ‘blue‐blocking’ lenses and pre‐receptor filters in the eye to explore changes to the orientation and the size of the colour threshold ellipse. The model predicts well the measured RG and YB thresholds and confirms the absence of significant threshold changes for MPOD values in the range 0 to 1 log unit. The model does, however, predict systematic changes in the orientation of the major axis (i.e., the tritan axis) and MPOD. These observations are of interest since the orientation of the major axis of the best‐fit ellipse appears to decrease monotonically from ~75° to 55°, as MPOD increases from very small values up to a peak OD of 1 log unit. More work is needed to investigate how YB and RG chromatic sensitivity is affected by combined absorption of short‐wavelength light by MPOD, the lens of the eye and ‘blue‐blocking’ spectacle lenses.

Emission inventory and simulation of air pollution for developing an air quality management plan for Tra Vinh Province (Vietnam) period 2022-2025

Tra Vinh is a coastal province in the Mekong Delta region. In recent years, increasing economic and social development activities have been creating great pressure on the air environment in the province. Therefore, it is very necessary to develop a provincial air quality management plan to provide solutions to manage and control air pollution in the province. The study conducted an emissions inventory from three main sources (mobile, point and area sources) by using the emission factor method. Emission inventory results show that point source emission is dominated by NO2 (64.4%) and SO2 (92.7%). Meanwhile, the main pollutant of traffic source is CO (69.0%) and area source are TSP, PM10 and PM2.5 (59.1%, 72.5% and 71.1% respectively). Emission inventory data is used as input data for air quality simulation study (FVM-TAPOM model) according to the current scenario in 2022. In addition, the study also builds scenarios pollution emissions based on Tra Vinh's socio-economic development planning to 2025. The simulation results show that the air quality in Tra Vinh province is still good, the simulated parameters values lower than the threshold according to QCVN 05:2023/BTNMT. On that basis, the study has developed solutions to control air environment quality in the coming time, contributing to sustainable development for the locality and the Mekong Delta region.

Estimation Method of Covariance Matrix in Atmospheric Inversion of CO2 Emissions

Atmospheric inversion of CO2 Emissions is based on the correction of prior carbon dioxide flux inventories using concentration monitoring data and atmospheric transport models to obtain posterior carbon dioxide flux. In atmospheric inversion studies, fixed covariance functions are commonly used to generate covariance matrices, and the hyperparameters in the covariance functions are empirically estimated. In this study, we design and implement an ideal experiment based on meteorological data from the central urban area of Zhengzhou, using WRF-STILT to generate sensitivity matrices and construct real carbon emission inventories and prior inventories. Based on the real carbon emission inventories and sensitivity matrices of monitoring stations, simulated observation concentration values are generated. Firstly, based on the observed concentration values, sensitivity matrices of monitoring stations, prior inventories, and constructed covariance matrices, the values of hyperparameters are determined based on maximum marginal likelihood estimation. Then, the influence of different prior covariance functions on the inversion results is tested, and it is found that the prior covariance matrix generated by the balgovind covariance function is most suitable for the experimental data.