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Extraction of eucalyptus age and estimation of its aboveground biomass in China with the integration of empirical model and machine learning algorithm 认领 引用
1
作者 Chunxian Tang Guiying Li Dengsheng Lu 《Forest Ecosystems》 SCIE CAS CSCD 2026年第3期565-582,共18页
Eucalyptus plantations are extensively distributed in tropical and subtropical regions and play important roles in timber production,economic development,and regional carbon cycles.Due to its fast growth and short rot... Eucalyptus plantations are extensively distributed in tropical and subtropical regions and play important roles in timber production,economic development,and regional carbon cycles.Due to its fast growth and short rotation periods,mapping of high spatial resolution eucalyptus age and its aboveground biomass(AGB)distribution becomes an urgent task,but such products are unavailable due to the difficulty in distinguishing eucalyptus from other tree species and lack of suitable methods to accurately estimate eucalyptus age and AGB.This study aims to develop a new approach to extract eucalyptus age and a new procedure to estimate AGB through integration of an empirical model and machine learning algorithm in subtropical and tropical regions of China.The eucalyptus distribution was first developed using Sentinel-2 imagery and its forest age in unit of months was then generated with a continuous threshold-based decision strategy based on monthly median composites of normalized difference vegetation index(NDVI)and the difference between NDVI and the normalized burn ratio(NBR)(DIF)from Landsat and Sentinel-2 time series data.The Chapman-Richards function was used to build a growth model based on eucalyptus age,and SHapley Additive exPlanations(SHAP)approach was used to identify key environmental factors for use in the AGB modeling procedure.The results showed that a root mean square error(RMSE)of 1.54 years was obtained,much lower than existing age products.About 77%of eucalyptus plantations were four years or younger.The predicted eucalyptus AGB in China was 217.41 million tons in 2023,with RMSE of 21.18 t⋅ha−1 and relative RMSE(RMSEr)of 22.41%.This study provided the first products of eucalyptus distribution with 10 m spatial resolution,the estimated age and AGB distributions with 30 m resolution in China in 2023.The proposed framework provides a new insight for age extraction and AGB estimation for other tree species.The results from this research provide a fundamental data source for eucalyptus forest resource management,carbon assessment,and policy-making. 展开更多
关键词 Eucalyptus Age Aboveground biomass China Empirical model Machine learning
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A quantitative framework for tree-soil interaction mechanisms in expansive clay:Field investigation and empirical modeling 认领 引用
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作者 Xi Sun Jie Li +2 位作者 You Gao Xin Liu Annan Zhou 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2025年第8期5155-5169,共15页
The complex behaviors of expansive soils,particularly their volumetric changes driven by moisture variations,pose significant challenges in urban geotechnical engineering.Although vegetation-induced moisture changes a... The complex behaviors of expansive soils,particularly their volumetric changes driven by moisture variations,pose significant challenges in urban geotechnical engineering.Although vegetation-induced moisture changes are known to affect ground movement,quantitative characterization of tree–soil interactions remains limited due to insufficient field data and unclear relationships between tree water uptake and soil response.This study investigates the mechanical behavior of expansive clay soils influenced by two Lophostemon confertus samples during a 14-month field monitoring program in Melbourne,Australia.The research methodology integrates measurements of soil displacement,total soil suction,moisture content,and tree water consumption through instrumentation and monitoring systems.Field measurements suggest that tree roots reached the limits of their water extraction capacity when total soil suction exceeded 2880 kPa within the active root zone.The spatial extent of tree-induced soil desiccation reached 0.6–0.7 times the tree height laterally and penetrated to depths of 2.5–3.3 m vertically.The mature sample,with an 86%greater crown area and a threefold larger sapwood area,exhibited 142%higher water consumption(35 kL),demonstrating the scalability of tree–soil interaction mechanisms.A multiple linear regression model was developed to quantify the coupled relationships between soil movement and key variables,achieving a high adjusted R2 value of 0.97,which provides engineers and practitioners with a practical tool for estimating ground movement near trees.These findings offer valuable insights for infrastructure design in tree-adjacent environments and can inform computational models and design codes to enable more accurate site assessments and sustainable urban development. 展开更多
关键词 Empirical model Expansive soil Ground movement Soil suction Soil water dynamics Tree root–soil interaction
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Develop an Empirical Model to Forecast Rainfall Intensity as a Function of Probability For Al-Diwaniyah City in Iraq 认领 引用
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作者 Ahmed Sagban Khudier Mohammed Hameed Al-Tofan Yasser Mohamed Ahmmed 《Journal of Environmental & Earth Sciences》 CAS 2025年第7期353-367,共15页
The study aims to develop an empirical model to predict the rainfall intensity in Al-Diwaniyah City,Iraq,according to a statistical analysis based on probability and the specific rainfall return period.Rainfall data w... The study aims to develop an empirical model to predict the rainfall intensity in Al-Diwaniyah City,Iraq,according to a statistical analysis based on probability and the specific rainfall return period.Rainfall data were collected daily for 25 years starting in 2000.Daily rainfall data were converted to rainfall intensity for five duration periods ranging from one to five hours.The extreme values were checked,and data that deviated from the group trend were removed for each period,and then arranged in descending order using the Weibull formula to calculate the probability.Statistically,the model performance with a return period of two years is considered good when compared with observed results and other methods such as Talbot and Sherman with a coefficient of determination(R2)>0.97 and Nash-Sutcliffe efficiency(NSE)>0.80.The results showed that a mathematical equation was obtained that describes the relationship between rainfall intensity,probability,and rainfall duration,which can be used for a confined return period with a 50% probability.Therefore,decision-makers can rely on the model to improve the performance of the city’s current drainage system during flood periods in the future. 展开更多
关键词 Rainfall Intensity Probability of Flood Al-Diwaniyah City Empirical Model
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Statistical prediction of waterflooding performance by K-means clustering and empirical modeling 认领 引用 被引量：3
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作者 Qin-Zhuo Liao Liang Xue +3 位作者 Gang Lei Xu Liu Shu-Yu Sun Shirish Patil 《Petroleum Science》 SCIE CAS CSCD 2022年第3期1139-1152,共14页
Statistical prediction is often required in reservoir simulation to quantify production uncertainty or assess potential risks.Most existing uncertainty quantification procedures aim to decompose the input random field... Statistical prediction is often required in reservoir simulation to quantify production uncertainty or assess potential risks.Most existing uncertainty quantification procedures aim to decompose the input random field to independent random variables,and may suffer from the curse of dimensionality if the correlation scale is small compared to the domain size.In this work,we develop and test a new approach,K-means clustering assisted empirical modeling,for efficiently estimating waterflooding performance for multiple geological realizations.This method performs single-phase flow simulations in a large number of realizations,and uses K-means clustering to select only a few representatives,on which the two-phase flow simulations are implemented.The empirical models are then adopted to describe the relation between the single-phase solutions and the two-phase solutions using these representatives.Finally,the two-phase solutions in all realizations can be predicted using the empirical models readily.The method is applied to both 2D and 3D synthetic models and is shown to perform well in the P10,P50 and P90 of production rates,as well as the probability distributions as illustrated by cumulative density functions.It is able to capture the ensemble statistics of the Monte Carlo simulation results with a large number of realizations,and the computational cost is significantly reduced. 展开更多
关键词 Waterflooding Statistical prediction K-means clustering Empirical modeling Uncertainty quantification
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Empirical modeling of normal/cyclo-alkanes pyrolysis to produce light olefins 认领 引用 被引量：3
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作者 Xu Hou Bochong Chen +6 位作者 Zhenzhou Ma Jintao Zhang Yuanhang Ning Donghe Zhang Liu Zhao Enxian Yuan Tingting Cui 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2022年第2期389-398,共10页
Due to the complexity of feedstock,it is challenging to build a general model for light olefins production.This work was intended to simulate the formation of ethylene,propene and 1,3-butadiene in alkanes pyrolysis by... Due to the complexity of feedstock,it is challenging to build a general model for light olefins production.This work was intended to simulate the formation of ethylene,propene and 1,3-butadiene in alkanes pyrolysis by referring the effects of normal/cyclo-structures.First,the pyrolysis of n-pentane,n-hexane,n-heptane,n-octane,n-nonane,n-decane,cyclohexane,methylcyclohexane,n-hexane and cyclohexane mixtures,and n-heptane and methylcyclohexane mixtures were carried out at 650–800℃,and a particular attention was paid to the measurement of ethylene,propene and 1,3-butadiene.Then,pseudo-first order kinetics was taken to characterize the pyrolysis process,and the effects of feedstock composition were studied.It was found that chain length and cyclo-alkane content can be qualitatively and quantitively represented by carbon atom number and pseudo-cyclohexane content,which made a significant difference on light olefins formation.Furthermore,the inverse proportional/quadratic function,linear function and exponential function were proposed to simulate the effects of chain length,cycloalkane content and reaction temperature on light olefins formation,respectively.Although the obtained empirical model well reproduced feedstock conversion,ethylene yield and propene yield in normal/cycloalkanes pyrolysis,it exhibited limitations in simulating 1,3-butadiene formation.Finally,the accuracy and flexibility of the present model was validated by predicting light olefins formation in the pyrolysis of multiple hydrocarbon mixtures.The prediction data well agreed with the experiment data for feedstock conversion,ethylene yield and propene yield,and overall characterized the changing trend of 1,3-butadiene yield along with reaction temperature,indicating that the present model could basically reflect light olefins production in the pyrolysis process even for complex feedstock. 展开更多
关键词 Empirical model Normal-alkane Cyclo-alkane Pyrolysis Light olefins
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Development of EMC-based empirical model for estimating spatial distribution of pollutant loads and its application in rural areas of Korea 认领 引用 被引量：3
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作者 Qitao Yi Hui Li +1 位作者 Jin-Woo Lee Youngchul Kim 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2015年第9期1-11,共11页
An integrated approach to easily calculate pollutant loads from agricultural watersheds is suggested and verified in this research. The basic concepts of this empirical tool were based on the assumption that variation... An integrated approach to easily calculate pollutant loads from agricultural watersheds is suggested and verified in this research. The basic concepts of this empirical tool were based on the assumption that variations in event mean concentrations（EMCs） of pollutants from a given agricultural watershed during rainstorms were only attributable to the rainfall pattern.Fifty one sets of EMC values were obtained from nine different watersheds located in the rural areas of Korea, and these data were used to develop predictive tools for the EMCs in rainfall runoff. The results of statistical tests of these formulas show that they are fairly good in predicting actual EMC values of some parameters, and useful in terms of calculating pollutant loads for any rainfall event time span such as daily, weekly, monthly, and yearly. This model was further checked in for its field applicability in a reservoir receiving stormwater after a cleanup of the sediments, covering 17 consecutive rainfall events from 1 July to 15 August in2007. Overall the predicted values matched the observed values, indicating the feasibility of this empirical tool as a simple and useful solution in evaluating timely distribution of nonpoint source pollution loads from small rural watersheds of Korea. 展开更多
关键词 EMC Empirical model Nonpoint source pollution Spatial distribution
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An Empirical Model for Estimating Stratospheric Ozone Vertical Distributions over China 认领 引用
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作者 杨景梅 邱金桓 《Advances in Atmospheric Sciences》 SCIE CAS 2009年第2期352-358,共7页
Based on the Stratospheric Aerosol and Gas Experiment （SAGE） Ⅱ and the Halogen Occultation Experiment （HALOE） ozone profiles and the Total Ozone Mapping Spectrometer （TOMS） total ozone data sets, an empirical m... Based on the Stratospheric Aerosol and Gas Experiment （SAGE） Ⅱ and the Halogen Occultation Experiment （HALOE） ozone profiles and the Total Ozone Mapping Spectrometer （TOMS） total ozone data sets, an empirical model for estimating the vertical distribution of stratospheric ozone over China is proposed. By using this model, the vertical distribution of stratospheric （16-50 km） ozone can be estimated according to latitude, month and total ozone. Comparisons are made between the modeled ozone profiles and the SAGEII/HALOE monthly mean ozone measurements, and the results show that the model calculated ozone concentrations conform well with the SAGEII/HALOE measured values, with the differences being less than 15% between 16 km and 18 km, less than 5% between 19 km and 40 km, and less than 10% between 41 km and 50 kin. Comparisons of the model results with balloon-borne ozonesonde measurements performed in Beijing also show good agreement, within 5%, at altitudes between 19 km and 30 km. 展开更多
关键词 ozone vertical distribution empirical model
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An Empirical Model for Estimating the Zonal Mean Aerosol Extinction Profiles from SAGE II Measurements 认领 引用
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作者 YANG Jing-Mei ZONG Xue-Mei 《Atmospheric and Oceanic Science Letters》 CSCD 2014年第6期553-558,共6页
This paper presents an empirical model for estimating the zonal mean aerosol extinction profiles in the stratosphere over 10°-wide latitude bands between 60°S and 60°N, on the basis of Stratospheric Aer... This paper presents an empirical model for estimating the zonal mean aerosol extinction profiles in the stratosphere over 10°-wide latitude bands between 60°S and 60°N, on the basis of Stratospheric Aerosol and Gas Experiment(SAGE) II aerosol extinction measurements at 1.02, 0.525, and 0.452 μm during the volcanically quiescent period between 1998–2004. First, an empirical model is developed for calculating the stratospheric aerosol extinction profiles at 1.02 μm. Then, starting from the 1.02 μm extinction profile and an exponential spectral dependence, an empirical algorithm is developed that allows the aerosol extinction profiles at other wavelengths to be calculated. Comparisons of the model-calculated aerosol extinction profiles at the wavelengths of 1.02, 0.525, and 0.452 μm and the SAGE II measurements show that the model-calculated aerosol extinction coefficients conform well with the SAGE II values, with the relative differences generally being within 15% from 2 km above the tropopause to 40 km. The model-calculated stratospheric aerosol optical depths at the three wavelengths are also in good agreement with the corresponding optical depths derived from the SAGE II measurements, with the relative differences being within 0.9% for all latitude bands. This paper provides a useful tool in simulating zonal mean aerosol extinction profiles, which can be used as representative background stratospheric aerosols in view of atmospheric modeling and remote sensing retrievals. 展开更多
关键词 aerosol extinction coefficient stratosphere empirical model
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Assessment of the three representative empirical models for zenith tropospheric delay(ZTD)using the CMONOC data 认领 引用
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作者 Debao Yuan Jian Li +4 位作者 Yifan Yao Fei Yang Yingying Wang Ran Chen Tairan Xu 《Geodesy and Geodynamics》 EI CSCD 2024年第5期488-494,共7页
The precise correction of atmospheric zenith tropospheric delay(ZTD)is significant for the Global Navigation Satellite System(GNSS)performance regarding positioning accuracy and convergence time.In the past decades,ma... The precise correction of atmospheric zenith tropospheric delay(ZTD)is significant for the Global Navigation Satellite System(GNSS)performance regarding positioning accuracy and convergence time.In the past decades,many empirical ZTD models based on whether the gridded or scattered ZTD products have been proposed and widely used in the GNSS positioning applications.But there is no comprehensive evaluation of these models for the whole China region,which features complicated topography and climate.In this study,we completely assess the typical empirical models,the IGGtropSH model(gridded,non-meteorology),the SHAtropE model(scattered,non-meteorology),and the GPT3 model(gridded,meteorology)using the Crustal Movement Observation Network of China(CMONOC)network.In general,the results show that the three models share consistent performance with RMSE/bias of 37.45/1.63,37.13/2.20,and 38.27/1.34 mm for the GPT3,SHAtropE and IGGtropSH model,respectively.However,the models had a distinct performance regarding geographical distribution,elevation,seasonal variations,and daily variation.In the southeastern region of China,RMSE values are around 50 mm,which are much higher than that in the western region,approximately 20 mm.The SHAtropE model exhibits better performance for areas with large variations in elevation.The GPT3 model and the IGGtropSH model are more stable across different months,and the SHAtropE model based on the GNSS data exhibits superior performance across various UTC epochs. 展开更多
关键词 GNSS Zenith tropospheric delay Empirical ZTD model CMONOC data
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Empirical Models for the Evaluation of Global Solar Radiation for the Site of Abeche in the Province of Ouaddaï, in Chad 认领 引用 被引量：1
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作者 Marcel Hamda Soulouknga Abraham Dandoussou Noel Djongyang 《Smart Grid and Renewable Energy》 2022年第10期223-234,共12页
The global sustainability plan for future development relies on solar radiation which is the main source of renewable energy. Thus, this work studies the performance of six models to estimate global solar radiation on... The global sustainability plan for future development relies on solar radiation which is the main source of renewable energy. Thus, this work studies the performance of six models to estimate global solar radiation on a horizontal surface for the Abeche site in Chad. The data used in this work were collected at the General Directorate of National Meteorology of Chad. The reliability and accuracy of different models for estimating global solar radiation were validated by statistical indicators to identify the most accurate model. The results show that among all the models, the Sabbagh model has the best performance in estimating the global solar radiation. The average is 6.354 kWh/m2 with an average of -3.704%. This model is validated against NASA data which is widely used. 展开更多
关键词 Empirical Models Statistical Indicators Solar Radiation Abeche
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Empirical tropospheric zenith wet delay models with strong generalization capability based on a robust machine learning fusion algorithm 认领 引用
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作者 Jiahao Zhang Qin Liang Yunqing Huang 《Geodesy and Geodynamics》 EI CSCD 2026年第2期211-224,共14页
Tropospheric zenith wet delay(ZWD)plays a vital role in the analysis of space geodetic observations.In recent years,machine learning methods have been increasingly applied to improve the accuracy of ZWD calculations.H... Tropospheric zenith wet delay(ZWD)plays a vital role in the analysis of space geodetic observations.In recent years,machine learning methods have been increasingly applied to improve the accuracy of ZWD calculations.However,a single machine learning model has limited generalization capabilities.To address these limitations,this study introduces a novel machine learning fusion(MLF)algorithm with stronger generalization capabilities to enhance ZWD modeling and prediction accuracy.The MLF algorithm utilizes a two-layer structure integrating extra trees(ET),backpropagation neural network(BPNN),and linear regression models.By comparing the root mean square error(RMSE)of these models,we found that both ET-based and MLF-based models outperform RF-based and BPNN-based models in terms of internal and external accuracy,across both surface meteorological data-based and blind models.The improvement in exte rnal accuracy is particularly significant in the blind models.Our re sults show that the MLF(with an RMSE of 3.93 cm)and ET(3.99 cm)models outperform the traditional GPT3model(4.07 cm),while the RF(4.21 cm)and BPNN(4.14 cm)have worse external accuracies than the GPT3 model.It is worth noting that the BPNN suffered from overfitting during external accuracy tests,which was avoided by the MLF.In summary,regardless of the availability of surface meteorological data,the MLF-based empirical models demonstrate superior internal and external accuracy compared to the other tested models in this study. 展开更多
关键词 Tropospheric zenith wet delay Machine learning Extra trees Machine learning fusion algorithm Empirical models
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Discrepancies between predictions of mainstream empirical growth models and observed forest growth of Pinus radiata(D.Don)plantations in New Zealand 认领 引用
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作者 Serajis Salekin Yvette Dickinson +5 位作者 Jo Liddell Christine Dodunski Priscilla Lad Steven Dovey Donald A.White David Pont 《Forest Ecosystems》 SCIE CAS CSCD 2026年第1期157-165,共9页
Pinus radiata(D.Don)dominates New Zealand's forestry industry,constituting 91%of plantations,and is among the world's most important plantation species.Given the socio-economic and environmental importance of ... Pinus radiata(D.Don)dominates New Zealand's forestry industry,constituting 91%of plantations,and is among the world's most important plantation species.Given the socio-economic and environmental importance of this species,it is important to have accurate and precise projections over time to make efficient decisions for forest management and greenfield investments in afforestation projects,especially for permanent carbon forests.Future projections of any natural resource systems rely on modeling;however,the acceleration of climate change makes future projections of yield less certain.These challenges also impact national expectations of the contribution planted forests will provide to address climate change and meet international commitments under the Paris Agreement.Using a large national-scale set of contemporary ground-measured data(2013–2023),this study investigates the performance of two growth models developed over 30 years ago that are widely used by NZ plantation growers:1)the Pumice Plateau Model 1988(PPM88)and 2)the 300-index(including a model variant of regional drift).Model simulations were made using the FORECASTER modeling suite with geographic boundaries to adjust for drift in space and time.Basal area(BA,m2⋅ha-1)and volume(m3⋅ha-1)were simulated,and standard errors and goodness-of-fit metrics calculated up to a typical rotation age of 30 years.Model residuals were then separated and analysed for the main plantation growing regions.The models overpredicted observed growth by between 6.8%and 16.2%,but model predictions and errors varied significantly between regions.The results of this study provided clear evidence of divergence between the outputs of both models and the measured data.Finally,this study suggests future measures to address challenges posed by these discrepancies that will provide better information for forest management and investment decisions in a changing climate. 展开更多
关键词 Pinus radiata Growth and yield prediction Empirical growth models Plantation forest Permanent sample plots Prediction errors Climate changeA
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Cold-formed steel under fire:Dual testing and empirical strength modeling 认领 引用
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作者 Fatih Mehmet OZKAL Casim YAZICI +1 位作者 Suleyman Nazif ORHAN Burak Kaan CIRPICI 《ENGINEERING Structure and Civil Engineering》 SCIE EI CAS CSCD 2026年第4期736-756,共21页
This research investigates the structural behavior of cold-formed steel(CFS)under elevated temperature conditions,focusing on the response against both in-fire and post-fire effects.Through experimental analysis and e... This research investigates the structural behavior of cold-formed steel(CFS)under elevated temperature conditions,focusing on the response against both in-fire and post-fire effects.Through experimental analysis and empirical modeling,the study aims to specify the impact of temperature on the mechanical properties of CFS,specifically examining the changes in yield strength,ultimate tensile strength,and ultimate elongation.Tensile tests were conducted on CFS specimens of S235 and S355 grades exposed to temperatures ranging from 23 to 1000℃,both during and after exposure to heating.Experimental findings revealed that yield strength and ultimate tensile strength decreased by up to 70%at 600℃,85%at 800℃,and approximately 95%at 1000℃ during fire exposure,while post-fire conditions showed smaller decreases,with reductions of 15%at 800℃ and 30%at 1000℃.In addition,empirical models,based on regression analysis and curve-fitting techniques,were developed to predict the yield strength variations of CFS,aiming to provide a supportive tool for predicting material behavior in fire scenarios.The empirical prediction models exhibit high accuracy in predicting post-fire conditions within a specific range of temperature,strength,and thickness but showed higher errors for in-fire conditions,emphasizing the complexity of material response under dynamic heating conditions.Validation of the prediction models involves an extensive analysis of previous studies,considering factors such as yield strength,specimen thickness,heating regimes,soaking times,and tensile loading rates.The results highlight the importance of considering especially initial yield strength and specimen thickness in predicting material behavior accurately.Overall,this research contributes to a deeper understanding of the sensitivity of steel material to elevated temperatures and provides substantial insights for enhancing fire safety assessments and structural design practices in the construction industry.The findings offer the baselines for developing more robust and reliable methodologies for evaluating structural performance in fire scenarios. 展开更多
关键词 cold-formed steel fire resistance elevated temperatures empirical prediction model
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Partially empirical model-based water depth retrieval in shallow sea using GF5-AHSI hyperspectral remote sensing data:a case study on Meizhou Bay in Fujian Province,China 认领 引用
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作者 Xiaoai DAI Yunfeng SHAN +7 位作者 Cheng LI Hao CHEN Tangrui DAI Ge QU Tianyi XIE Chengbo TONG Htun NAING Min ZHANG 《Frontiers of Earth Science》 SCIE CSCD 2025年第4期533-549,共17页
Bathymetric mapping using quantitative remote sensing techniques is a crucial research domain for accurately retrieving oceanic depths.This study uses GF5-AHSI hyperspectral remote sensing data to evaluate the accurac... Bathymetric mapping using quantitative remote sensing techniques is a crucial research domain for accurately retrieving oceanic depths.This study uses GF5-AHSI hyperspectral remote sensing data to evaluate the accuracy of three semi-empirical models for shallow water depth retrieval:single-band,multi-band,and band-ratio models.The methodology involved parameter extraction,optimal band selection,and combining bands to create the models.A Pearson correlation analysis was conducted to assess parameter sensitivity,optimizing the models for water depth retrieval.The models’precision was evaluated by comparing their outputs with actual underwater topography measurements from Meizhou Bay,Fujian Province.Error margins in estimated water depths ranged from 10%to 50%across the three models,with accuracy generally improving at greater depths.Among the models,the band-ratio model showed the highest reliability,followed by the multi-band model,and the single-band model was the least reliable.However,in depths greater than 30 m,the single-band model’s error margin could be reduced to within 10%,surpassing the performance of the multi-band and band-ratio models.A spectral reflectance sensitivity test revealed variations in reflectance across different water depths,with a slight increase in the nearinfrared band due to water turbidity.To further improve model accuracy,strategies must be implemented to mitigate the interference of suspended sediments and reduce noise,thereby enhancing the reliability of water depth retrieval. 展开更多
关键词 GF5-AHSI water depth retrieval Pearson correlation coefficient partially theoretical and empirical model
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Anisotropic time-dependent behaviors of shale under direct shearing and associated empirical creep models 认领 引用 被引量：16
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作者 Yachen Xie Michael Z.Hou +1 位作者 Hejuan Liu Cunbao Li 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第4期1262-1279,共18页
Understanding the anisotropic creep behaviors of shale under direct shearing is a challenging issue.In this context,we conducted shear-creep and steady-creep tests on shale with five bedding orientations (i.e.0°,... Understanding the anisotropic creep behaviors of shale under direct shearing is a challenging issue.In this context,we conducted shear-creep and steady-creep tests on shale with five bedding orientations (i.e.0°,30°,45°,60°,and 90°),under multiple levels of direct shearing for the first time.The results show that the anisotropic creep of shale exhibits a significant stress-dependent behavior.Under a low shear stress,the creep compliance of shale increases linearly with the logarithm of time at all bedding orientations,and the increase depends on the bedding orientation and creep time.Under high shear stress conditions,the creep compliance of shale is minimal when the bedding orientation is 0°,and the steady-creep rate of shale increases significantly with increasing bedding orientations of 30°,45°,60°,and 90°.The stress-strain values corresponding to the inception of the accelerated creep stage show an increasing and then decreasing trend with the bedding orientation.A semilogarithmic model that could reflect the stress dependence of the steady-creep rate while considering the hardening and damage process is proposed.The model minimizes the deviation of the calculated steady-state creep rate from the observed value and reveals the behavior of the bedding orientation's influence on the steady-creep rate.The applicability of the five classical empirical creep models is quantitatively evaluated.It shows that the logarithmic model can well explain the experimental creep strain and creep rate,and it can accurately predict long-term shear creep deformation.Based on an improved logarithmic model,the variations in creep parameters with shear stress and bedding orientations are discussed.With abovementioned findings,a mathematical method for constructing an anisotropic shear creep model of shale is proposed,which can characterize the nonlinear dependence of the anisotropic shear creep behavior of shale on the bedding orientation. 展开更多
关键词 Rock anisotropy Direct shear creep Creep compliance Steady-creep rate Empirical model Creep constitutive model
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An empirical model for high energy density lithium-(ion)batteries with ultra-thick electrodes 认领 引用 被引量：7
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作者 Li-Ming Jin Guang-Guang Xing +4 位作者 Nan Qin Yan-Yan Lu Jun-Sheng Zheng Cun-Man Zhang Jim P.Zheng 《Tungsten》 EI CSCD 2024年第1期230-237,共8页
Increasing the electrode thickness is a significant method to decrease the weight and volume ratio of the inactive components for high energy density of the devices.In this contribution,we extracted a repeating unit i... Increasing the electrode thickness is a significant method to decrease the weight and volume ratio of the inactive components for high energy density of the devices.In this contribution,we extracted a repeating unit in the configurations and establish the empirical energy density model based on some assumptions.In this model,the effects of the electrode thickness on the energy density for lithium-ion batteries(LIBs),lithium metal batteries(LMBs),and anode-free lithium batteries(ALBs)are evaluated quantitively with the current parameters of the batteries.The results demonstrate that the structure evolutions from LIBs,LMBs to ALBs with the reduction of the anode weight contribution,the energy density can be well improved exactly.While the increase of the thickness of the electrode provide another route to furthe r enhance the energydensity by decreasing the weight contribution of inactive materials;meanwhile the effects for ALBs are higher than LMBs and LIBs due to the higher weight ratio of inactive materials.This empirical energy density model is also applied into the practical system and provide intuitional results to guide the battery design for higher energy density. 展开更多
关键词 Empirical model High energy density Lithium batteries Ultra-thick electrodes
Empirical modeling of ionospheric F2 layer critical frequency over Wakkanai under geomagnetic quiet and disturbed conditions 认领 引用 被引量：4
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作者 LIU Jing LIU LiBo +2 位作者 ZHAO BiQiang WAN WeiXing CHEN YiDing 《Science China(Technological Sciences)》 SCIE EI CAS 2012年第5期1169-1177,共9页
The hourly values of the ionospheric F2 layer critical frequency, foF2, recorded at Wakkanai ionosonde station （45.4°N, 141.7°E） have been collected to construct a middle-latitude single-station model for ... The hourly values of the ionospheric F2 layer critical frequency, foF2, recorded at Wakkanai ionosonde station （45.4°N, 141.7°E） have been collected to construct a middle-latitude single-station model for forecasting foF2 under geomagnetic quiet and disturbed conditions. The module for the geomagnetic quiet conditions incorporates local time, seasonal, and solar vari- ability of climatological foF2 and its upper and lower quartiles. It is the first attempt to predict the upper and lower quartiles of foF2 to account for the notable day-to-day variability in ionospheric foF2. The validation statistically verifies that the model captures the climatological variations of foF2 with higher accuracy than IRI does. The storm-time module is built to capture the geomagnetic storm induced relative deviations of foF2 from the quiet time references. In the geomagnetically disturbed module, the storm-induced deviations are described by diumal and semidiumal waves, which are modulated by a modified magnetic activity index, the Kf index, reflecting the delayed responses of foF2 to geomagnetic activity forcing. The coeffi- cients of the model in each month are determined by fitting the model formula to the observation in a least-squares way. We provide two options for the geomagnetic disturbed module, including or not including Kalman filter algorithm. The Kalman filter algorithm is introduced to optimize these coefficients in real time. Our results demonstrate that the introduction of the Kalman filter algorithm in the storm time module is promising for improving the accuracy of predication. In addition, comparisons indicate that the IRI model prediction of the F2 layer can be improved to provide better performances over this region. 展开更多
关键词 Empirical modeling Kalman f＇dter ionospheric storm
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Empirical model of concrete block fragment behavior under explosion loads 认领 引用 被引量：2
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作者 YANG Shuai NING JianGuo +1 位作者 REN HuiLan XU XiangZhao 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2024年第8期2515-2529,共15页
Concrete structures undergo integral fragmentation under explosion loads. The fragmentation degree and particle-size distribution of concrete blocks under explosion loads must be considered during mining to ensure saf... Concrete structures undergo integral fragmentation under explosion loads. The fragmentation degree and particle-size distribution of concrete blocks under explosion loads must be considered during mining to ensure safety. In this study, the impulse is calculated based on the relationship between overpressure and time, and the impact energy of the explosion wave is obtained based on blast theory. Subsequently, the Mohr-Coulomb shear strength fracture criterion is introduced to determine the ultimate shear stress of the concrete materials, and an empirical model that can effectively calculate the energy consumption of concrete blocks under explosion loads is established. Furthermore, concrete fragments with different particle sizes under explosion scenarios are quantitatively predicted with the principle of energy conservation. Finally, explosion tests with different top standoff distances are conducted, and the concrete fragments after the explosion tests are recovered, sieved, weighed, and counted to obtain experimental data. The effectiveness of the fragment empirical model is verified by comparing the model calculation results with the experimental data. The proposed model can be used as a reference for civil blasting, protective engineering design, and explosion-damage assessment. 展开更多
关键词 concrete structures explosion loads fragment behavior empirical model
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Skillful prediction of winter Arctic Oscillation from previous summer in a linear empirical model 认领 引用 被引量：3
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作者 Hong-Li REN Yu NIE 《Science China Earth Sciences》 SCIE EI CAS CSCD 2021年第1期27-36,共10页
The winter Arctic Oscillation(WAO),as a primary atmospheric variability mode in the Northern Hemisphere,plays a key role in influencing mid-high-latitude climate variations.However,current dynamical seasonal forecasti... The winter Arctic Oscillation(WAO),as a primary atmospheric variability mode in the Northern Hemisphere,plays a key role in influencing mid-high-latitude climate variations.However,current dynamical seasonal forecasting systems have limited skills in predicting WAO with lead time longer than two months.In this study,we design a linear empirical model using two effective precursors from anomalies of the Arctic sea ice concentration(SIC)and the tropical sea surface temperature(SST)initiated in preceding late summer(August)which are both significantly correlated with WAO in recent four decades.This model can provide a skillful prediction of WAO at about half-year lead started from previous summer and perform much better than the dynamical models.Such a significantly prolonged lead time is owed to the stable precursor signals extracted from the SIC and SST anomalies over specific areas,which can persist from previous August and be further enhanced through autumn months.Validation results show that this model can produce a 20-year independent-validated prediction skill of 0.45 for 1999–2018 and a 39-year cross-validated skill of 0.67 for 1980–2018,providing a potentially effective tool for earlier predictions of winter climate variations at mid-high latitudes. 展开更多
关键词 Arctic Oscillation(AO) Winter AO prediction Sea ice concentration Sea surface temperature Linear empirical model
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Novel empirical model for predicting residual flexural capacity of corroded steel reinforced concrete beam 认领 引用
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作者 Zhao-Hui LU Hong-Jun WANG +3 位作者 Fulin QU Yan-Gang ZHAO Peiran LI Wengui LI 《Frontiers of Structural and Civil Engineering》 SCIE EI CSCD 2020年第4期888-906,共19页
In this study,a total of 177 flexural experimental tests of corroded reinforced concrete(CRC)beams were collected from the published literature.The database of flexural capacity of CRC beam was established by using un... In this study,a total of 177 flexural experimental tests of corroded reinforced concrete(CRC)beams were collected from the published literature.The database of flexural capacity of CRC beam was established by using unified and standardized experimental data.Through this database,the effects of various parameters on the flexural capacity of CRC beams were discussed,including beam width,the effective height of beam section,ratio of strength between longitudinal reinforcement and concrete,concrete compressive strength,and longitudinal reinforcement corrosion ratio.The results indicate that the corrosion of longitudinal reinforcement has the greatest effect on the residual flexural capacity of CRC beams,while other parameters have much less effect.In addition,six available empirical models for calculating the residual flexural strength of CRC beams were also collected and compared with each other based on the established database.It indicates that though five of six existing empirical models underestimate the flexural capacity of CRC beams,there is one model overestimating the flexural capacity.Finally,a newly developed empirical model is proposed to provide accurate and effective predictions in a large range of corrosion ratio for safety assessment of flexural failure of CRC beams confirmed by the comparisons. 展开更多
关键词 CRC beams flexural capacity steel corrosion database empirical models
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