Increase In Temperature Research Articles

Modeling load sensing pressure and flow control of axial piston pump by analyzing impact of bulk modulus

This research is focused on investigating the impact of the bulk modulus on the dynamics of variable delivery hydraulic axial piston pump (VAPP). The bulk modulus decreases exponentially with an increase in temperature whereas there is a linear positive relationship with pressure. The research revealed that there is a 6% (1 litre/s) increase in flow rate and a 2.6% (1.5 MPa) decrease in delivery pressure with a 38.75% (0.434 GPa) decrease in bulk modulus. Flow ripple and pressure pulsation are reduced by 39.3% and 43.2% respectively with a corresponding 38.75% decrease in bulk modulus. Pressure pulsation and flow ripple are responsible for the generation of noise and vibrations in the system. Flow rate increase contributes to better response and control of the VAPP. While a reduction in bulk modulus offers improved dynamic performance and overall response of the VAPP, it is noteworthy that a decrease in bulk modulus hurts the pump delivery pressure. The research allows the pump designer to formulate a strategy to optimize the bulk modulus under dynamic operating conditions to achieve optimal pump performance.

Climate- and scale-dependent sex ratio in threatened Araucaria forests

Male and female dioecious trees often differ in their sensitivity to environmental stress, resulting in unbalanced sex ratios that can affect forest regeneration. Dioecious species are thus especially vulnerable to climate change, which can intensify their sexual bias. We investigated the sex ratio in endangered pehuén (Araucaria araucana) forests to determine whether there is an imbalance in ratio at different spatial scales, and if so, whether this is climate-dependent. To assess deviations in sex ratios on local and regional scales, we quantified the proportion of males along 37 transects within 11 patches in two populations. To assess the sex–climate relationship, we used WorldClim data; for the biogeographic scale, we added published sex ratio information from other populations. We found a bias towards males both locally and regionally. On a local scale, this bias was related to heterogeneous temperature conditions, especially in patches with particularly wet or hot summers. On a biogeographic scale, this bias increased in warmer, humid and thermally more homogeneous conditions. The male bias we found implies a direct reduction in the effective size of these already threatened forests. Considering climate change projections for Patagonia, predicting an increase in temperatures and their anomalies, our results suggest that males would be less affected than females; this points to an intensification of the male bias and thus to increased vulnerability of these already endangered pehuén forests. This study provides evidence of climate-dependent sex bias in threatened dioecious forests and discusses its importance in the context of climate change.

Estimation of Surface Ice Velocity of Durung Drung Glacier, Western Himalaya using COSI-Corr from Landsat images

Glaciers all over the world have been experiencing recession at varying rates. Alterations in glacial retreat, volume, and mass have direct implications for sea level rise and have implications for the overall health of glaciers. Measuring the surface ice velocity of glaciers presents challenges due to the rugged terrain and harsh climate at high altitudes, making field observations difficult. This study aims to address these challenges by focusing on the calculation of the surface ice velocity of the Durung Drung glacier in Zanskar Valley, Ladakh. Landsat- 7 & 8 panchromatic bands with a resolution of 15 m were used in conjunction with the COSI-Corr module of ENVI image processing software to derive surface ice velocity. The method involved the crosscorrelation of Landsat images from 1999/2000 and 2019/2020. The COSI-Corr module used in this study provided three key outputs: east–west displacement, north–south displacement, and signal-to-noise ratio. These outputs are essential for understanding the movement of the glacier and evaluating the quality of the image correlation. The results indicate that the surface velocity of Durung Drung glacier was 71 ± 6.1 m yr−1 in 1999/2000, which increased (by ∼ 50 %) to 140 ± 7.4 m yr−1 in 2019/2020. An increasing trend in velocity manifests the rising trend in temperature in the western Himalaya. Analysis of CRU TS4 gridded data reveals an increase in temperature while precipitation decreased during 1976–2020. The study recommends that the annual variations in surface ice velocity are a consequence of temperature fluctuations that influence the availability of meltwater.

Crop diversification in perennial plantation systems of Sri Lanka: Patterns, determinants and challenges

CONTEXTThe adoption of crop diversification in response to climate change in perennial cropping systems is poorly understood. OBJECTIVEThis study identifies the current level of diversification, determinants of and constraints to adopting crop diversification in tea plantations in Sri Lanka as an example of a perennial crop in a developing country context. METHODSWe use a Panel Tobit model to analyse the driving forces of crop diversification using 2004–2018 data collected from 49 tea estates. In addition, tea estates' managers were interviewed to investigate barriers to adopting crop diversification. RESULTS AND CONCLUSIONSThe study reveals that geo-climatic conditions, magnitude of increase in temperature, and higher revenue variability are the specific factors influencing managers' probability of adopting crop diversification. Constraints to crop diversification include technological lock-in hindering alternative crops and worker shortages, financial difficulties, lack of productive lands suitable for alternative crops, ineffective Government land-use policies and regional weather patterns such as prolonged rainfall and heavy winds. SIGNIFICANCEIdentified barriers provide important insights into how to assist plantations to adopt crop diversification. We propose three policy recommendations to enhance tea estate managers' adaptive capacity to various environmental and social changes through crop diversification. These are: (1) enable managers to acquire the technical know-how on cultivating alternative crops by conducting practical training programmes connecting with the Department of Agriculture or Agriculture Faculties of regional Universities.; (2) increase awareness of less labor-intensive crops for diversification along with strategies for mechanisation via programmes integrated with the Ministry of Plantation Agriculture and the Agriculture Modernization Project of the Department of Agriculture; and (3) enact a national policy to mandate crop diversification in marginal tea lands with financial assistance from the Government.

Research on microplastic deformation of Inconel718 under the conditions of high temperature and high strain rate

The compression experiments of the nickel-based superalloy Inconel718 were carried out with the help of split Hopkinson pressure bar device, and the microstructure evolution law in the compression deformation of the alloy was studied by means of optical microscopy, electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). Based on the dislocation theory, a three-dimensional discrete dislocation dynamics model is established. By simulating the dynamic evolution of the discrete dislocation, the interaction of the dislocation itself and the formation of the dislocation microstructure were captured, and further explore the microplastic deformation process of Inconel718. The results show that deformation conditions significantly affect the rheological behavior and dynamic recrystallization behaviour. The cross slip of dislocations is closely related to temperature and strain rate, which in turn affect the dislocation configuration. The deformation mechanism of Inconel718 under the conditions of high temperature and high strain rate is jointly dominated by dislocation slip and twin deformation. As the temperature increases, the average Schmidt factor increases, and more dislocation slip systems are activated. As the strain rate increases, the number of deformation twins increases, while the thickness of deformation twins decreases.

Theoretical and experimental study on mixed-mode I + II fracture characteristics of thermally treated granite under liquid nitrogen cooling

Liquid nitrogen fracturing technology is widely used in the exploitation of hot dry rock (HDR) geothermal resources. It is necessary to understand the fracture characteristics of hot dry rocks under liquid nitrogen cooling. In this study, the mixed-mode I + II fracture characteristics of the thermally treated granite under liquid nitrogen cooling were investigated. The results indicate that as the exposed temperature increases, the number of internal microcracks increases, while the fracture energy and fracture toughness of the granites decrease. From 25 ℃ to 600 ℃, mode I fracture toughness decreases from 1.286MP·m1/2 to 0.612MP·m1/2; mode Ⅱ fracture toughness decreases from 0.830MP·m1/2 to 0.413MP·m1/2; mixed-mode Ⅰ+Ⅱ fracture toughness decreases from 1.082 MP·m1/2 to 0.530MP·m1/2 at Me = 0.705 and from 0.914 MP·m1/2 to 0.445 MP·m1/2 at Me = 0.427, respectively. Additionally, the intergranular fracture behavior increases as temperature increases, resulting in an increase in irregularity of fracture surfaces. The generalized maximum tangential stress (GMTS) criterion is used for predicting the fracture characteristics (fracture initiation angle and fracture toughness) of thermal damaged granites. The accuracy of the GMTS criterion in predicting crack resistance when mode II loading dominates has been improved by considering the variation of critical damage radius.

Role of oxygen vacancy on rapid densification and giant dielectric properties of flash sintered Ca2+ and Ta5+ co-doped TiO2 ceramics

(Ca, Ta) co-doped TiO2 ceramics were successfully prepared using flash sintering technology, and the effects of oxygen vacancies on the rapid densification and giant dielectric properties were studied. The results suggest that the maximum volume fraction of oxygen vacancies in flash-sintered samples is approximately 10%. Oxygen vacancies decrease the barrier energy level of atomic diffusion and provide convenient diffusion channels, resulting in rapid densification of the sample within 24 min at 1100 °C. All flash-sintered samples exhibit high relative density, exceeding 95%. Oxygen vacancies promote the electron-pinning defect dipole effect at low temperatures. As the temperature increases, carriers such as oxygen vacancies move to the grain boundary, forming an internal barrier layer capacitance effect. The optical dielectric constant reaches 7.25 × 104, and the dielectric loss drops to 0.09. Oxygen vacancy play an important role in both flash sintering technology and the giant dielectric properties of co-doped TiO2 ceramics.

Exploring the joint influence of SO2 and alkali metal on FeW mixed oxides catalyst for NOx elimination

The coexistence of multiple substances in the flue gas, such as alkali metal and SO2, results in the NH3-SCR catalysts suffering from serious deactivation. Therefore, we systematically studied the effects of coexisting SO2 and Na on the FeW oxides for NOx elimination. This study elucidates that the joint influence mechanism of these substances on SCR activity was regulated by reaction temperatures. When the temperature was below 300oC, the catalyst suffered a double whammy. The addition of SO2 in process of NH3-SCR resulted in a decrease in the activity of Na-poisoned FeW catalyst. It was largely due to the formation of inorganic SO42-, which not only consumed the NH3 but also blocked active sites. With the increase of reaction temperatures above 300oC, the SO2 could interact with Na2O to construct a ternary electron interaction of SO42--Na+-FeW, contributing to the improvement of alkali metal resistance. This sulfate adjusted the D-band center energy of the catalyst closer to the Fermi level, thereby boosting the adsorption energies of NH3 and NO, increasing their adsorption abilities. Furthermore, sulfate binding broke the Na-O-Fe and Na-O-W bonds, resulting in the restoration of Fe-O-W and Fe-O-Fe active sites and accumulation of Na+ species. Precise characterizations and theoretical calculations shed light on the joint mechanism of SO2 and alkali metals which provide guidance to the design SCR catalyst with excellent resistance to SO2 and alkali metal poisoning.

Multimorbidity and emergency hospitalisations during hot weather

BackgroundPeople with chronic diseases are a commonly listed heat-vulnerable group in heat-health action plans. While prior research identifies multiple health conditions that may increase vulnerability to ambient heat, there is minimal evidence regarding the implications of multimorbidity (two or more chronic diseases). MethodsFrom the statewide hospital registry of Queensland, Australia, we identified people aged ≥15 years who had emergency hospitalisation(s) between March 2004 and April 2016 and previously had 0, 1, 2, or ≥3 of five chronic diseases: cardiovascular disease, diabetes, mental disorders, asthma/COPD, and chronic kidney disease. We conducted time-stratified case-crossover analyses to estimate the odds ratio of hospitalisations associated with ambient heat exposure in people with different numbers, types, and combinations of chronic diseases. Ambient heat exposure was defined as a 5 °C increase in daily mean temperature above the median. FindingsThere were 2,263,427 emergency hospitalisations recorded (48.7% in males and 51.3% in females). When the mean temperature increased, hospitalisation odds increased with chronic disease number, particularly in older persons (≥65 years), males, and non-indigenous people. For instance, in older persons with 0, 1, 2, or ≥3 chronic diseases, the odds ratios associated with ambient heat exposure were 1.00 (95% confidence interval: 0.96, 1.04), 1.06 (1.02, 1.09), 1.08 (1.02, 1.14), and 1.13 (1.07, 1.19), respectively. Among the chronic diseases, chronic kidney disease, and asthma/COPD, either existing alone, together, or in combination with other diseases, were associated with the highest odds of hospitalisations under ambient heat exposure. InterpretationWhile individuals with multimorbidity are considered in heat-health action plans, this study suggests the need to consider specifically examining them as a distinct and vulnerable subgroup. FundingWellcome.

Investigation on ash fusion characteristics and mineral transformation mechanism of sorghum straw by paper-making sludge addition

The co-combustion of sorghum straw and paper-making sludge (PMS) is beneficial to alleviate the ash-related problem in sorghum straw combustion process. In this paper, the mineral migration and transformation behavior in sorghum straw ashes with the addition of PMS ashes under an oxidizing atmosphere were investigated using an X-ray diffractometer, thermogravimetric-derivative thermogravimetric, scanning electron microscopy-energy dispersive X-ray detector, and FactSage software. The results demonstrated that the increase in the PMS ash mass ratio led to an increase in ash fusion temperature (AFT) of sorghum straw mixtures. The generations of high melting-point (MP) calcium feldspar (e.g., Ca2MgSi2O7, Ca2Al2SiO7, Ca3MgSi2O8, and Ca7Mg (SiO4)4) and phosphates (e.g., Ca3P2O8, Ca5P2SiO12, and Ca7P2Si2O16) caused the increases in the AFT. The maximum weight loss of sorghum straw ashes decreased with the increasing PMS ash mass ratio, and the surface of the ashes underwent the transition from smooth to a whole loose and rough, which alleviated the ash-related problems of sorghum straw. The addition of PMS ashes decreasing the liquid-phase content calculated by FactSage at the same temperature also explained the sorghum straw AFT increase. The changes of AFT and its corresponding mechanisms in the sorghum straw with PMS ash addition under an oxidizing atmosphere provided the support for large-scale combustion of biomass.

A nonlocal photoacoustic effect with variable thermal conductivity of semiconductor material subjected to laser heat source

This study explores the behavior of laser-exposed photo-excited carriers, investigating the propagation of photoacoustic waves in the thermoelastic domain. It also delves into the theoretical generation of surface acoustic waves in semiconductors through photo-thermoelastic processes. The research considers the interaction between thermomechanical and acoustic waves in a nonlocal medium with temperature-dependent thermal conductivity. Unlike relying on electron–phonon or electron-hole thermalization processes, photoacoustic waves here result from thermoelastic stress induced by the laser-induced temperature increase. The investigation accounts for the optical, mechanical, and thermoelastic properties of nanoscale semiconductor materials. Predictions of photoacoustic signals are derived by solving a combined thermal diffusion issue and a thermoelastic problem, using Laplace and Fourier transforms in the mathematical model. Numerical solutions encompass various physical fields within the time domain using the inversion technique of Laplace and Fourier transforms, such as thermal, acoustic, mechanical, and carrier density diffusion. The study evaluates and compares the influences of thermal memory and thermal conductivity presenting visual representations.

Influence of microstructure evolution on hot ductility behavior of a Cr and Mo alloyed Fe-C-Mn steel during hot deformation

Cr and Mo alloyed Fe-C-Mn steel was conducted by hot tensile experiments under different strain rates and deformation temperatures. The influence of microstructure evolution on fracture mechanism was studied. The principal failure mechanism was attributed to intergranular crack propagation and microvoid aggregation when deformed at 800-1100 ℃, changing to a mixed ductile-brittle intergranular fracture when deformed at 1200 ℃. After hot deformation, the microstructure transformed from a mixed phase of pearlite and ferrite to a lath martensite structure. Moreover, the lath martensite structure transitioned from disorder to order as the deformation temperature increases. The study revealed that in case of lower temperature when dynamic recovery (DRV) was dominated, the growth of voids was impeded by fine dynamic recrystallization (DRX) grains, resulting in an irregular void morphology. In case of higher temperature, the degree of DRX was high, voids were surrounded and impeded by newly formed DRX grains, which were gradually elongate with deformation. On the other hand, when there were DRX grains present between voids, void coalescence was less likely to occur, thereby inhibiting damage propagation.

Influences of solution temperature on microstructures and performance of electron beam welded joints of laser powder bed fusion TC11 thin-walled samples

The effects of subtransus treatment (750 °C, 800 °C, 850 °C, 900 °C, and 950 °C) as well as supertransus treatment (1100 °C) on the microstructures and mechanical performance of electron beam welded (EBW) joints of laser powder bed fusion (LPBF) TC11 alloy were investigated. At a solution temperature of 950 °C, globular α phases and transformed β phases were observed in the joint. When the solution temperature exceeded the β transus temperature (Tβ), α colonies and massive α phases emerged in the joints, resulting in Widmanstatten structures. The base metal (BM) exhibited the highest microhardness, followed by the heat affected zone (HAZ), whereas the fusion zone (FZ) demonstrated the lowest microhardness. As the solution temperature increases, the microhardness of joints decreases at first and then increases. Notably, the joint subjected to a solution temperature of 850 °C exhibited the lowest microhardness. When the solution temperature was ≥900 °C, transformed β phases emerged within the joints, resulting in an elevation of microhardness. Below Tβ, the elongation of welded joints gradually augmented while the tensile strength reduced at first and then increased with the rising solution temperature. Microstructures in joint with solution temperature of 950 °C consisted of lamellar α phases, globular α phases, and transformed β phases. As a result, the joint exhibited an optimal balance between strength (1103.1 ± 34.9 MPa) and plasticity (9.37 ± 0.20%). Ductile fracture characteristics with dimples on the fracture surface were observed in the tensile samples. Therefore, it can be concluded that a solid solution temperature of 950 °C is optimal for LPBF TC11 alloy.

Biochar Enriched Concrete for Carbon Sequestration

Abstract: In upcoming years , a lot of construction is going to happen leading to more cement consumption and more GHG’s emissions by default as an embodied carbon. Reduction of cement consumption is possible by partially repacing it with biochar which is a by-product of pyrolysis of biomass or adding it as an additive in cement mortar and concrete for carbon sequestration. Biochar is effective in carbon sequestration activity and results in high water and carbon dioxide holding capacity. Increase in biochar lead to increase in carbon sequestration . As pozzolanic activity lead to strength gaining characteristics and durability of concrete, this study focusses on investigating pozzolanic activity of biochar. Biomass considered in this study were walnut shells and pretreatment was done with 0.1 N HCl and and pozzolanic activity is checked by chapelle test by observing Ca(OH)2 fixation during the titration. It was observed that increase in temperature or Normality of HCl in pretreatment does not enhance pozzolanic activity of biochar . Hence pretreatment with 0.1 N HCl at room temperature for an hour is sufficient to enhance the pozzolanic activity of biochar with much high carbon dioxide sorption as compared to usual concrete without compromising with the strength of concrete. This study reclaims the potential use of biochar in concrete is reliable for carbon sequestration.

Exploring the Tar Component Characteristics of Coalfield Fire Residual Coal Under Different Constant Temperature Oxidation

ABSTRACT Due to incomplete combustion of coal, a large amount of tar will be produced in coal fire area, which will cause serious pollution to the environment. In this paper, we dissolve the tar components in the residual coal by solvent extraction technique, analyze the organic components in the residual coal tar at different temperatures by GC-MS, study the characteristics of the residual coal tar components at different temperatures, and analyze the influence of the residual coal tar on the combustion and rekindling characteristics of the fire zone of the coalfield. The results show that: the components of coal combustion residual tar are mainly alkane organics which are easy to be oxidized and volatilized, and the content is more than 55%. At 300°C, the color of residual tar extract is light yellow or yellowish brown, and becomes colorless with the increase of temperature. At 300–500°C, the lower the temperature in the fire zone, the more residual tar in the coal, and the greater the risk of reignition in the extinguishing fire zone. The types of organic compounds in the tar residue from combustion have obvious characteristics at different temperature stages. Organic species have obvious characteristics at different temperature stages. By identifying the temperature stage of the coalfield fire area development, the organic structure characteristics and change trend of the residual coal tar can be deduced, and mastering the organic structure characteristics of the residual tar in the coalfield fire area can also reflect the temperature stage of coal fire area to a certain extent.

Vertical and temporal flight patterns of coffee berry borer (Coleoptera: Curculionidae) in Hawaii.

Coffee berry borer (Hypothenemus hampei Ferrari)(Coleoptera: Curculionidae) is the most damaging insect pest of coffee worldwide, causing significant losses in coffee yields and quality. Knowledge of vertical and temporal flight patterns in coffee berry borer could be used to optimize spray timing and precision targeting of areas within the coffee tree, which may be more susceptible. In the present study, we estimated the vertical distribution of coffee berry borer females using traps set at 1-m intervals up to 5 m in height. We also quantified coffee berry borer infestation in the low, mid, and high canopy and documented fruit availability. Temporal flight patterns were estimated using timer traps, and correlation analyses were conducted to determine the relationship between the timing of daily flight and weather variables. Across the 4 study sites, we observed that 77%-84% of the trap catch was at 1 m, 11%-20% was at 2 m, and 1%-4% was at 3-5 m in height. Fruit infestation was significantly higher in the low branches (35%) relative to the high branches (17%). Flight height remained the same year-round, regardless of fruit availability. Coffee berry borer flew in low numbers during the day and night but peaked from 12 to 4 PM. Daily flight was positively correlated with an increase in air temperature and wind speed and negatively correlated with relative humidity. Findings from this study suggest that pesticide sprays should target low- to mid-level branches at 1-2 m in height and aim to be conducted in the early afternoon when coffee berry borer are actively flying and most vulnerable to chemical controls.

Waste-Heat Renewable Gasifier Design through Taguchi's Method and MANFIS

Ensuring a global average temperature increase of no more than 1.5°C is crucial for aligning with the objectives of the Paris Agreement. The Intergovernmental Panel on Climate Change (IPCC) estimates that a 45% reduction in carbon dioxide emissions by 2030 or a 25% reduction by the same year is necessary to cap the temperature rise at 2°C. Failure to achieve this target by 2030 would necessitate substantial subsequent reductions to compensate for the delayed progress toward net zero emissions, potentially incurring higher costs. Elevating the focus on enhancing energy efficiency has emerged as a key strategy in expediting progress toward these climate goals. Hydrogen, renowned for its high efficiency and emission-free combustion, is anticipated to play a pivotal role in this endeavor. Traditionally, gasifiers have served as the conduit for transforming inexpensive fuels like coal or biomass into hydrogen. However, their energy-intensive nature poses a challenge.Addressing this inherent issue, an innovative approach known as the external-heating gasifier has been proposed and designed. The design of the external-heating gasifier represents a quintessential nonlinear and multiple-input multiple-output (MIMO) problem. To achieve optimal performance, the integration of Taguchi's method and inverse-model technology has been employed, with a simulation platform developed using the COMSOL Multiphysics software.Initially, Taguchi's method was utilized to determine the minimum number of experiments required for a full-factorial design and identify the most critical factors influencing product performance. Subsequently, an adaptive neuro-fuzzy inference system (ANFIS) was developed with a MIMO–ANFIS architecture. This system was employed to train an inverse model, facilitating the mapping of relationships between each input and output set. In essence, this approach enables the identification of manufacturing parameters that result in optimal performance. To illustrate the efficacy of the proposed method, a simulation study on an existing gasifier is presented.

Active and passive cooling techniques of graphical processing units in automotive applications - a review

Abstract Graphical Processing Units (GPU) have become a vital source for data processing in many advanced or smart technologies. They have proven to be faster and more efficient than the Central Processing Unit (CPU) in computing large data sets. The automotive industry has adopted GPUs for Advanced Driver Assistance Systems (ADAS), but other systems like electric vehicles and autonomous vehicles will also employ GPUs soon. Although GPUs are faster at computing large data sets, there is the challenge of a substantial increase in core temperature during the process. This review paper primarily focuses on Active and Passive cooling methods for GPUs in automotive. The paper commences by addressing the role and need for GPUs in the automotive industry and explores the challenges faced by them and the factors that lead to an increase in temperature. The paper further reviews various cooling methods used by Original Equipment Manufacturers (OEM) in the automotive industry. The outcomes of the review are a detailed understanding of the use of GPUs in automotive, a brief interpretation of heating issues in GPUs and what causes them, a comprehensive understanding of the cooling methods used to reduce the core temperature, and a perception of an anticipated technology to resolve the heating problem.

Using Brownian model to study the effect of temperature on diffusion coefficient

This study employs molecular simulation techniques, particularly the Brownian motion model, to investigate the influence of temperature on diffusion coefficients. Leveraging Einsteins relationship for calculating diffusion coefficients and a one-dimensional random walk model, we systematically explore the impact of simulation direction, particle quantity, and simulation duration on diffusion behavior. The research extends its scope to three-dimensional Brownian motion simulations, offering insights into the stochastic motion of particles in a fluid. The primary objective is to analyze the relationship between temperature and diffusion coefficients. Through rigorous linear regression analysis, a significant and strong linear association is identified, demonstrating that an increase in temperature correlates with an increase in the diffusion coefficient. The research not only contributes to the fundamental understanding of molecular motion but also provides practical recommendations for simulation parameters, especially in resource-constrained computational environments. The study acknowledges certain limitations in the current Brownian motion algorithm and proposes avenues for future research to enhance computational efficiency and precision. This abstract encapsulates the key methodologies, findings, and implications of the research, laying the foundation for a comprehensive exploration of temperature-dependent diffusion coefficients in molecular systems.

Evaluating Performance of Multiple Machine Learning Models for Drought Monitoring: A Case Study of Typical Grassland in Inner Mongolia

Driven by continuously evolving precipitation shifts and temperature increases, the frequency and intensity of droughts have increased. There is an obvious need to accurately monitor drought. With the popularity of machine learning, many studies have attempted to use machine learning combined with multiple indicators to construct comprehensive drought monitoring models. This study tests four machine learning model frameworks, including random forest (RF), convolutional neural network (CNN), support vector regression (SVR), and BP neural network (BP), which were used to construct four comprehensive drought monitoring models. The accuracy and drought monitoring ability of the four models when simulating a well-documented Inner Mongolian grassland site were compared. The results show that the random forest model is the best among the four models. The R2 range of the test set is 0.44–0.79, the RMSE range is 0.44–0.72, and the fitting accuracy relationship could be described as RF > CNN > SVR ≈ BP. Correlation analysis between the fitting results of the four models and SPEI found that the correlation coefficient of RF from June to September was higher than that of the other three models, though we noted the correlation coefficient of CNN in May was slightly higher than that of RF (CNN = 0.79; RF = 0.78). Our results demonstrate that comprehensive drought monitoring indices developed from RF models are accurate, have high drought monitoring ability, and can achieve the same monitoring effect as SPEI. This study can provide new technical support for comprehensive regional drought monitoring.