Accurately simulating water flow movement in vadose zone is crucial for effective water resources assessment.Richards'equation,which describes the movement of water flow in the vadose zone,is highly nonlinear and ...Accurately simulating water flow movement in vadose zone is crucial for effective water resources assessment.Richards'equation,which describes the movement of water flow in the vadose zone,is highly nonlinear and challenging to solve.Existing numerical methods often face issues such as numerical dispersion,oscillation,and mass non-conservation when spatial and temporal discretization conditions are not appropriately configured.To address these problems and achieve accurate and stable numerical solutions,a finite analytic method based on water content-based Richards'equation(FAM-W)is proposed.The performance of the FAM-W is compared with analytical solutions,Finite Difference Method(FDM),and Finite Analytic Method based on the pressure Head-based Richards'equation(FAM-H).Compared to analytical solution and other numerical methods(FDM and FAM-H),FAM-W demonstrates superior accuracy and efficiency in controlling mass balance errors,regardless of spatial step sizes.This study introduces a novel approach for modelling water flow in the vadose zone,offering significant benefits for water resources management.展开更多
1.Discipline origins In 1984,“analytical pharmacology”was firstly used in the paper entitled“The future of analytical pharmacologyda personal view”by Dr.J.S.Cridland,director of a clinical pharmacological laborato...1.Discipline origins In 1984,“analytical pharmacology”was firstly used in the paper entitled“The future of analytical pharmacologyda personal view”by Dr.J.S.Cridland,director of a clinical pharmacological laboratory at Department of Pharmacology,University of Cape Town.He proposed“Analytical pharmacology is at present usually a tool of clinical pharmacology”,which is mainly used for therapeutic drug monitoring,analysis of clinical pharmacokinetics,and toxicological screening to provide a basis for reasonable medication and clinical dose adjustment[1].In 1984,W.J.Black,Director of Wellcome Research Laboratories,was offered a personal Chair at King's College Hospital School of Medicine and Dentistry,part of King's College London.He chose“Analytical Pharmacology”as a title for the Chair[2].展开更多
Objective Blood culture remains the gold standard for diagnosing bloodstream infections.Clinical laboratories must ensure the quality of blood culture processes from receipt to obtaining definitive results.We examined...Objective Blood culture remains the gold standard for diagnosing bloodstream infections.Clinical laboratories must ensure the quality of blood culture processes from receipt to obtaining definitive results.We examined laboratory analytical indicators associated with positive blood culture results.Methods Blood cultures collected from Peking Union Medical College Hospital between January 1,2020,and December 31,2022,were retrospectively analyzed.The mode of transportation(piping logistics delivery vs.staff),source of blood cultures(outpatient/emergency department vs.inpatient department),rotation of personnel,and time of reception(8:00–19:59 vs.20:00–07:59)were compared between blood culture-positive and-negative results.Results Between 2020 and 2022,the total positive rate of blood culture was 8.07%.The positive rate of blood cultures in the outpatient/emergency department was significantly higher than that in the inpatient department(12.46%vs.5.83%;P<0.0001).The time-to-detection of blood cultures was significantly affected by the delivery mode and personnel rotation.The blood culture positive rate of the total pre-analytical time within 1 h was significantly higher than that within 1–2 h or>2 h(P<0.0170).Conclusion Laboratory analytical indicators such as patient source,transportation mode,and personnel rotation significantly impacted the positive detection rate or time of blood culture.展开更多
A new analytical model for geometric size and forming force prediction in incremental flanging(IF)is presented in this work.The complex deformation characteristics of IF are considered in the modeling process,which ca...A new analytical model for geometric size and forming force prediction in incremental flanging(IF)is presented in this work.The complex deformation characteristics of IF are considered in the modeling process,which can accurately describe the strain and stress states in IF.Based on strain analysis,the model can predict the material thickness distribution and neck height after IF.By considering contact area,strain characteristics,material thickness changes,and friction,the model can predict specific moments and corresponding values of maximum axial forming force and maximum horizontal forming force during IF.In addition,an IF experiment involving different tool diameters,flanging diameters,and opening hole diameters is conducted.On the basis of the experimental strain paths,the strain characteristics of different deformation zones are studied,and the stable strain ratio is quantitatively described through two dimensionless parameters:relative tool diameter and relative hole diameter.Then,the changing of material thickness and forming force in IF,and the variation of minimum material thickness,neck height,maximum axial forming force,and maximum horizontal forming force with flanging parameters are studied,and the reliability of the analytical model is verified in this process.Finally,the influence of the horizontal forming force on the tool design and the fluctuation of the forming force are explained.展开更多
Waterproof performance of gaskets between segments is the focus of shield tunnels.This paper proposed an analytical method for determining seepage characteristics at tunnel-gasketed joints based on the hydraulic fract...Waterproof performance of gaskets between segments is the focus of shield tunnels.This paper proposed an analytical method for determining seepage characteristics at tunnel-gasketed joints based on the hydraulic fracturing theories.First,the mathematical model was established,and the seepage governing equation and boundary conditions were obtained.Second,three dimensionless parameters were introduced for simplifying the expressions,and the seepage governing equations were normalized.Third,analytical expressions were derived for the interface opening and liquid pressure.Moreover,the influencing factors of seepage process at the gasketed interface were analyzed.Parametric analyses revealed that,in the normalized criterion of liquid viscosity,the liquid tip coordinate was influenced by the degree of negative pressure in the liquid lag region,which was related to the initial contact stress.The coordinate of the liquid tip affected the liquid pressure distribution and the interface opening,which were analyzed under different liquid tip coordinate conditions.Finally,under two limit states,comparative analysis showed that the results of the variation trend of the proposed method agree well with those of previous research.Overall,the proposed analytical method provides a novel solution for the design of the waterproof in shield tunnels.展开更多
Point-of-care testing(POCT)refers to a category of diagnostic tests that are performed at or near to the site of the patients(also called bedside testing)and is capable of obtaining accurate results in a short time by...Point-of-care testing(POCT)refers to a category of diagnostic tests that are performed at or near to the site of the patients(also called bedside testing)and is capable of obtaining accurate results in a short time by using portable diagnostic devices,avoiding sending samples to the medical laboratories.It has been extensively explored for diagnosing and monitoring patients’diseases and health conditions with the assistance of development in biochemistry and microfluidics.Microfluidic paper-based analytical devices(μPADs)have gained dramatic popularity in POCT because of their simplicity,user-friendly,fast and accurate result reading and low cost.SeveralμPADs have been successfully commercialized and received excellent feedback during the past several decades.This review briefly discusses the main types ofμPADs,preparation methods and their detection principles,followed by a few representative examples.The future perspectives of the development inμPADs are also provided.展开更多
A segmented predictor-corrector method is proposed for hypersonic glide vehicles to address the issue of the slow computational speed of obtaining guidance commands using the traditional predictor-corrector guidance m...A segmented predictor-corrector method is proposed for hypersonic glide vehicles to address the issue of the slow computational speed of obtaining guidance commands using the traditional predictor-corrector guidance method.Firstly,an altitude-energy profile is designed,and the bank angle is derived analytically as the initial iteration value for the predictor-corrector method.The predictor-corrector guidance method has been improved by deriving an analytical form for predicting the range-to-go error,which greatly accelerates the iterative speed.Then,a segmented guidance algorithm is proposed.The above analytically predictor-corrector guidance method is adopted when the energy exceeds an energy threshold.When the energy is less than the threshold,the equidistant test method is used to calculate the bank angle command,which ensures guidance accuracy as well as computational efficiency.Additionally,an adaptive guidance cycle strategy is applied to reduce the computational time of the reentry guidance trajectory.Finally,the accuracy and robustness of the proposed method are verified through a series of simulations and Monte-Carlo experiments.Compared with the traditional integral method,the proposed method requires 75%less computation time on average and achieves a lower landing error.展开更多
We study the Cauchy problem of the Kolmogorov-Fokker-Planck equations and show that the solution enjoys an analytic smoothing effect with L?initial datum for positive time.
In the paper,a class of functions with bounded turnings involving cardioid domain,are studied in the region of the unit disc.The bounds of|a_(5)|,|a_(6)|,|a_(7)|and the fourth Hankel determinant are obtained,which are...In the paper,a class of functions with bounded turnings involving cardioid domain,are studied in the region of the unit disc.The bounds of|a_(5)|,|a_(6)|,|a_(7)|and the fourth Hankel determinant are obtained,which are more accurate than those obtained by Srivastava.展开更多
Renormalization group analysis has been proposed to eliminate secular terms in perturbation solutions of differential equations and thus expand the domain of their validity.Here we extend the method to treat periodic ...Renormalization group analysis has been proposed to eliminate secular terms in perturbation solutions of differential equations and thus expand the domain of their validity.Here we extend the method to treat periodic orbits or limit cycles.Interesting normal forms could be derived through a generalization of the concept'resonance',which offers nontrivial analytic approximations.Compared with traditional techniques such as multi-scale methods,the current scheme proceeds in a very straightforward and simple way,delivering not only the period and the amplitude but also the transient path to limit cycles.The method is demonstrated with several examples including the Duffing oscillator,van der Pol equation and Lorenz equation.The obtained solutions match well with numerical results and with those derived by traditional analytic methods.展开更多
The stress gradient of surrounding rock and reasonable prestress of support are the keys to ensuring the stability of roadways.The elastic-plastic analytical solution for surrounding rock was derived based on unified ...The stress gradient of surrounding rock and reasonable prestress of support are the keys to ensuring the stability of roadways.The elastic-plastic analytical solution for surrounding rock was derived based on unified strength theory.A model for solving the stress gradient of the surrounding rock with the intermediate principal stress parameter b was established.The correctness and applicability of the solution for the stress gradient in the roadway surrounding rock was verified via multiple methods.Furthermore,the laws of stress,displacement,and the plastic zone of the surrounding rock with different b values and prestresses were revealed.As b increases,the stress gradient in the plastic zone increases,and the displacement and plastic zone radius decrease.As the prestress increases,the peak stress shifts toward the sidewalls,and the stress and stress gradient increments decrease.In addition,the displacement increment and plastic zone increment were proposed to characterize the support effect.The balance point of the plastic zone area appears before that of the displacement zone.The relationship between the stress gradient compensation coefficient and the prestress is obtained.This study provides a research method and idea for determining the reasonable prestress of support in roadways.展开更多
Renewable energy sources,including wind,solar,and biofuels,are essential for promoting sustainable economic development and mitigating environmental challenges.As China’s overseas investments in renewable energy expa...Renewable energy sources,including wind,solar,and biofuels,are essential for promoting sustainable economic development and mitigating environmental challenges.As China’s overseas investments in renewable energy expand,effective risk assessment and management have become critical.This study develops a comprehensive risk evaluation framework for China’s overseas renewable energy investments using the Fuzzy Analytic Hierarchy Process(FAHP).The framework incorporates political,economic,and project-specific risks,organized through three primary criteria,nine sub-criteria,and thirty tertiary indicators.By integrating expert judgments with fuzzy set theory,the FAHP methodology assigns accurate weights to risk factors and ensures consistency in evaluation.The findings identify political risks as the most significant,emphasizing their influence on investment strategies.These insights offer valuable guidance for policymakers and investors to enhance risk management strategies and ensure the sustainability of China’s renewable energy initiatives abroad.展开更多
This paper delves into the visual teaching of analytic geometry facilitated by GeoGebra software.Through a meticulous analysis of the current landscape of analytic geometry instruction and the distinct advantages of G...This paper delves into the visual teaching of analytic geometry facilitated by GeoGebra software.Through a meticulous analysis of the current landscape of analytic geometry instruction and the distinct advantages of GeoGebra software,it expounds upon the imperative and feasibility of its application within the realm of analytic geometry teaching.Furthermore,it presents a detailed account of the teaching practice process grounded in this software,encompassing teaching design and the demonstration of teaching cases,and conducts an in-depth investigation and analysis of the teaching outcomes.The research findings indicate that the GeoGebra software can effectively elevate the level of visualization in analytic geometry teaching,thereby augmenting students’learning enthusiasm and comprehension capabilities.It thus offers novel perspectives and methodologies for the pedagogical reform of analytic geometry.展开更多
By using a certain hybrid-type convolution operator,we first introduce a new subclass of normalized analytic functions in the open unit disk.For members of this analytic function class,we then derive several propertie...By using a certain hybrid-type convolution operator,we first introduce a new subclass of normalized analytic functions in the open unit disk.For members of this analytic function class,we then derive several properties and characteristics including(for example)the modified Hadamard products,Holder's inequalities and convolution properties as well as some closure properties under a general family of integral transforms.展开更多
The analytic continuation serves as a crucial bridge between quantum Monte Carlo calculations in imaginary-time formalism,specifically the Green's functions,and physical measurements(the spectral functions)in real...The analytic continuation serves as a crucial bridge between quantum Monte Carlo calculations in imaginary-time formalism,specifically the Green's functions,and physical measurements(the spectral functions)in real time.Various approaches have been developed to enhance the accuracy of analytic continuation,including the Padéapproximation,the maximum entropy method,and stochastic analytic continuation.In this study,we employ different deep learning techniques to investigate the analytic continuation for the quantum impurity model.A significant challenge in this context is that the sharp Abrikosov-Suhl resonance peak may be either underestimated or overestimated.We fit both the imaginary-time Green's function and the spectral function using Chebyshev polynomials in logarithmic coordinates.We utilize Full-Connected Networks(FCN),Convolutional Neural Networks(CNNs),and Residual Networks(ResNet)to address this issue.Our findings indicate that introducing noise during the training phase significantly improves the accuracy of the learning process.The typical absolute error achieved is less than 10-4.These investigations pave the way for machine learning to optimize the analytic continuation problem in many-body systems,thereby reducing the need for prior expertise in physics.展开更多
The gastrointestinal tract of felines is inhabited by an active and intricate population of microorganisms whose alteration creates disturbances in the immune response and can affect health and disease states.Studies ...The gastrointestinal tract of felines is inhabited by an active and intricate population of microorganisms whose alteration creates disturbances in the immune response and can affect health and disease states.Studies using vari‑ous analytical methods have identified peculiar trends in various illnesses,with Firmicutes being the most prevalent phylum,followed by Bacteroidetes,Proteobacteria,and Actinobacteria.However,more Firmicutes and fewer Bac‑teroidetes have been observed in cats infected with Feline coronavirus.Alterations in the composition of these gut microbiota can be solved by microbiota modification through dietary fiber,probiotics,and fecal microbiota transplan‑tation.Therefore,it is critical to understand the composition of the gut microbiota,the changes in and roles of the gut environment,and the importance of these concepts for overall health while considering the exchange of microbes between humans and domestic animals.This review provides comprehensive information on feline gut microbiota composition,modulation,and analytic methods used for characterizing the gut microbiota.展开更多
Enhancing ecological security for sustainable social,economic,and environmental development is a key focus of current research and a practical necessity for ecological management.However,the integration of retrospecti...Enhancing ecological security for sustainable social,economic,and environmental development is a key focus of current research and a practical necessity for ecological management.However,the integration of retrospective ecological security assessments with future trend predictions and fine-scale targeted regulations remains inadequate,limiting effective ecological governance and sustainable regional development.Guided by Social-Economic-Natural Complex Ecosystems(SENCE)theory,this study proposes an analytical framework that integrates ecological security assessment,prediction,and zoning management.The Daqing River Basin,a typical river basin in the North China Plain,was selected as a case study.The results indicate that overall ecological security in the Daqing River Basin improved from a“Moderate”level to a“Relatively Safe”level between 2000 and 2020;however,spatial heterogeneity persisted,with higher ecological security in northwestern and eastern regions and lower ecological security in the central region.Approximately 62% of the Basin experienced an improvement in ecological security level,except in the major urban areas of Beijing,Tianjin,and Hebei,where ecological security deteriorated.From 2025 to 2040,the overall ecological security of the Daqing River Basin is expected to improve and remain at the“Relatively Safe”level.However,spatial heterogeneity will be further aggravated as the ecological security of major urban areas continues to deteriorate.Ecological security management zones and regulation strategies are proposed at the regional and county scales to emphasize integrated regulation for the entire basin and major urban areas.The proposed analytical framework provides valuable insights for advancing theoretical research on ecological security.The case study offers a practical reference for ecological security enhancement in river basins and other regions facing significant human-land conflicts.展开更多
This study evaluates the use of predictive analytics to forecast customer turnover in subscription-based Services in order to develop a predictive model to help small and medium-sized enterprises manage customer churn...This study evaluates the use of predictive analytics to forecast customer turnover in subscription-based Services in order to develop a predictive model to help small and medium-sized enterprises manage customer churn in the face of digital disruption.The research uses a quantitative approach focusing on empirical customer data to accurately predict buying trends and adapt marketing techniques.Demand forecasts in the health sector are important,as in every sector.In particular,the material forecast and stock forecasting of the purchasing unit of hospitals are among the areas that receive significant attention.Four classifiers(Random Forest,Logistic Regression,Gradient Boosting and XGBoost)are trained and evaluated using various performance indicators as part of a systematic approach involving Kaggle data collection,preparation and model selection.The results show excellent accuracy in predicting customer attrition,but there are limitations in precision and recall,indicating room for improvement.Confusion matrices provide information about the performance of each classifier,allowing for continuous improvement of predictive analytics techniques.Ethical concerns are rigorously addressed throughout the work process to guarantee appropriate data and machine learning methodologies.The proposals emphasize the proactive use of predictive analytics to identify at-risk customers and implement targeted retention strategies.Incorporating new data sources,improving customer experience,and utilizing collaborative churn management methods are recommended to increase forecast accuracy and business outcomes.Finally,this research provides important insights into the usefulness of predictive analytics for customer churn forecasting as well as practical recommendations for businesses seeking to increase customer retention and reduce churn risk.By leveraging empirical research findings and implementing ethical and rigorous churn control strategies,businesses can achieve long-term success in today’s changing market environment.展开更多
For the solution of peridynamic equations of motion,a meshless approach is typically used instead of utilizing semi-analytical or mesh-based approaches.In contrast,the literature has limited analytical solutions.This ...For the solution of peridynamic equations of motion,a meshless approach is typically used instead of utilizing semi-analytical or mesh-based approaches.In contrast,the literature has limited analytical solutions.This study develops a novel analytical solution for one-dimensional peridynamic models,considering the effect of damping.After demonstrating the details of the analytical solution,various demonstration problems are presented.First,the free vibration of a damped system is considered for under-damped and critically damped conditions.Peridynamic solutions and results from the classical theory are compared against each other,and excellent agreement is observed between the two approaches.Next,forced vibration analyses of undamped and damped conditions are performed.In addition,the effect of horizon size is investigated.It is shown that for smaller horizon sizes,peridynamic results agree well with classical results,whereas results from these two approaches deviate from each other as the horizon size increases.展开更多
Underhand cut-and-fill mining has been widely used in underground mining operations,especially when the rock mass or orebody is of poor quality or prone to rockburst due to high stress.In such cases,mining workers sho...Underhand cut-and-fill mining has been widely used in underground mining operations,especially when the rock mass or orebody is of poor quality or prone to rockburst due to high stress.In such cases,mining workers should carry out all production activities under the cemented backfill roof or sill mat instead of a highly fractured and unstable rock roof or a strong rock roof with a high potential of rockburst.Therefore,the stability and required strength of the sill mat are critical issues for mining engineers.In 1991,Mitchell considered that sill mat could fail by caving,sliding,rotation,and flexure.Mitchell also proposed an analytical solution to determine the minimum required strength of the sill mat for each type of failure based on two stiff or immobile rock walls.However,recent publications using numerical modeling and field measurements indicate that the compressive stresses in the sill mat induced by rock wall closure due to a stope excavation beneath the sill mat can be significant.It is thus highly necessary to investigate the required strength of the sill mat by considering rock wall closure.In this study,the crushing failure of sill mat due to rock wall closure generated by underground excavation and a new failure mode called"crushing and caving”is revealed by numerical modeling.An analytical solution corresponding to each failure mode is then developed to estimate the minimum required cohesion(cmin)of the sill mat.A criterion is also proposed to determine if the sill mat fails by crushing or crushing-and-caving failure.The proposed analytical solution does not involve any correction coefficients.The validity of the proposed analytical solution is demonstrated by numerical modeling.The proposed analytical solution can thus be employed to predict the cmin of sill mat subjected to wall closure generated by underlying stope excavation.展开更多
基金supported by the National Natural Science Foundation of China(No.42372287 and No.U24A20178)the Fundamental Research Funds for the Central Universities CHD(No.2024SHEEAR002)+3 种基金the Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shaanxi Province(No.2020024)the China Postdoctoral Science Foundation(GZC20232955,2024M753472,and 2024MD763937)the Science-Technology Foundation for Young Scientists of Gansu Province,China(No.24JRRA097)the Study of biodiversity survey and limiting factor analysis of Yinkentala(2023ZL01).
文摘Accurately simulating water flow movement in vadose zone is crucial for effective water resources assessment.Richards'equation,which describes the movement of water flow in the vadose zone,is highly nonlinear and challenging to solve.Existing numerical methods often face issues such as numerical dispersion,oscillation,and mass non-conservation when spatial and temporal discretization conditions are not appropriately configured.To address these problems and achieve accurate and stable numerical solutions,a finite analytic method based on water content-based Richards'equation(FAM-W)is proposed.The performance of the FAM-W is compared with analytical solutions,Finite Difference Method(FDM),and Finite Analytic Method based on the pressure Head-based Richards'equation(FAM-H).Compared to analytical solution and other numerical methods(FDM and FAM-H),FAM-W demonstrates superior accuracy and efficiency in controlling mass balance errors,regardless of spatial step sizes.This study introduces a novel approach for modelling water flow in the vadose zone,offering significant benefits for water resources management.
文摘1.Discipline origins In 1984,“analytical pharmacology”was firstly used in the paper entitled“The future of analytical pharmacologyda personal view”by Dr.J.S.Cridland,director of a clinical pharmacological laboratory at Department of Pharmacology,University of Cape Town.He proposed“Analytical pharmacology is at present usually a tool of clinical pharmacology”,which is mainly used for therapeutic drug monitoring,analysis of clinical pharmacokinetics,and toxicological screening to provide a basis for reasonable medication and clinical dose adjustment[1].In 1984,W.J.Black,Director of Wellcome Research Laboratories,was offered a personal Chair at King's College Hospital School of Medicine and Dentistry,part of King's College London.He chose“Analytical Pharmacology”as a title for the Chair[2].
基金supported by grants from the National High Level Hospital Clinical Research Funding(2022-PUMCH-B-074)Peking Union Medical College Hospital Research Funding for Postdoc(kyfyjj202320).
文摘Objective Blood culture remains the gold standard for diagnosing bloodstream infections.Clinical laboratories must ensure the quality of blood culture processes from receipt to obtaining definitive results.We examined laboratory analytical indicators associated with positive blood culture results.Methods Blood cultures collected from Peking Union Medical College Hospital between January 1,2020,and December 31,2022,were retrospectively analyzed.The mode of transportation(piping logistics delivery vs.staff),source of blood cultures(outpatient/emergency department vs.inpatient department),rotation of personnel,and time of reception(8:00–19:59 vs.20:00–07:59)were compared between blood culture-positive and-negative results.Results Between 2020 and 2022,the total positive rate of blood culture was 8.07%.The positive rate of blood cultures in the outpatient/emergency department was significantly higher than that in the inpatient department(12.46%vs.5.83%;P<0.0001).The time-to-detection of blood cultures was significantly affected by the delivery mode and personnel rotation.The blood culture positive rate of the total pre-analytical time within 1 h was significantly higher than that within 1–2 h or>2 h(P<0.0170).Conclusion Laboratory analytical indicators such as patient source,transportation mode,and personnel rotation significantly impacted the positive detection rate or time of blood culture.
基金supported in part by financial support from the National Key R&D Program of China(No.2023YFB3407003)the National Natural Science Foundation of China(No.52375378).
文摘A new analytical model for geometric size and forming force prediction in incremental flanging(IF)is presented in this work.The complex deformation characteristics of IF are considered in the modeling process,which can accurately describe the strain and stress states in IF.Based on strain analysis,the model can predict the material thickness distribution and neck height after IF.By considering contact area,strain characteristics,material thickness changes,and friction,the model can predict specific moments and corresponding values of maximum axial forming force and maximum horizontal forming force during IF.In addition,an IF experiment involving different tool diameters,flanging diameters,and opening hole diameters is conducted.On the basis of the experimental strain paths,the strain characteristics of different deformation zones are studied,and the stable strain ratio is quantitatively described through two dimensionless parameters:relative tool diameter and relative hole diameter.Then,the changing of material thickness and forming force in IF,and the variation of minimum material thickness,neck height,maximum axial forming force,and maximum horizontal forming force with flanging parameters are studied,and the reliability of the analytical model is verified in this process.Finally,the influence of the horizontal forming force on the tool design and the fluctuation of the forming force are explained.
基金Project(52278421)supported by the National Natural Science Foundation of ChinaProject(2024ZZTS0754)supported by the Fundamental Research Funds for the Central Universities of Central South University,China+2 种基金Project(2023CXQD067)supported by the Central South University Innovation-Driven Research Programme,ChinaProject(2022QNRC001)supported by Young Elite Scientists Sponsorship Program by CASTProject(2023TJ-N24)supported by the Youth Talent Program by China Railway Society and the Hunan Provincial Science and Technology Promotion Talent Project。
文摘Waterproof performance of gaskets between segments is the focus of shield tunnels.This paper proposed an analytical method for determining seepage characteristics at tunnel-gasketed joints based on the hydraulic fracturing theories.First,the mathematical model was established,and the seepage governing equation and boundary conditions were obtained.Second,three dimensionless parameters were introduced for simplifying the expressions,and the seepage governing equations were normalized.Third,analytical expressions were derived for the interface opening and liquid pressure.Moreover,the influencing factors of seepage process at the gasketed interface were analyzed.Parametric analyses revealed that,in the normalized criterion of liquid viscosity,the liquid tip coordinate was influenced by the degree of negative pressure in the liquid lag region,which was related to the initial contact stress.The coordinate of the liquid tip affected the liquid pressure distribution and the interface opening,which were analyzed under different liquid tip coordinate conditions.Finally,under two limit states,comparative analysis showed that the results of the variation trend of the proposed method agree well with those of previous research.Overall,the proposed analytical method provides a novel solution for the design of the waterproof in shield tunnels.
文摘Point-of-care testing(POCT)refers to a category of diagnostic tests that are performed at or near to the site of the patients(also called bedside testing)and is capable of obtaining accurate results in a short time by using portable diagnostic devices,avoiding sending samples to the medical laboratories.It has been extensively explored for diagnosing and monitoring patients’diseases and health conditions with the assistance of development in biochemistry and microfluidics.Microfluidic paper-based analytical devices(μPADs)have gained dramatic popularity in POCT because of their simplicity,user-friendly,fast and accurate result reading and low cost.SeveralμPADs have been successfully commercialized and received excellent feedback during the past several decades.This review briefly discusses the main types ofμPADs,preparation methods and their detection principles,followed by a few representative examples.The future perspectives of the development inμPADs are also provided.
基金National Natural Science Foundation of China(Nos.61773387 and 62022061).
文摘A segmented predictor-corrector method is proposed for hypersonic glide vehicles to address the issue of the slow computational speed of obtaining guidance commands using the traditional predictor-corrector guidance method.Firstly,an altitude-energy profile is designed,and the bank angle is derived analytically as the initial iteration value for the predictor-corrector method.The predictor-corrector guidance method has been improved by deriving an analytical form for predicting the range-to-go error,which greatly accelerates the iterative speed.Then,a segmented guidance algorithm is proposed.The above analytically predictor-corrector guidance method is adopted when the energy exceeds an energy threshold.When the energy is less than the threshold,the equidistant test method is used to calculate the bank angle command,which ensures guidance accuracy as well as computational efficiency.Additionally,an adaptive guidance cycle strategy is applied to reduce the computational time of the reentry guidance trajectory.Finally,the accuracy and robustness of the proposed method are verified through a series of simulations and Monte-Carlo experiments.Compared with the traditional integral method,the proposed method requires 75%less computation time on average and achieves a lower landing error.
基金Supported by NSFC (No.12031006)Fundamental Research Funds for the Central Universities of China。
文摘We study the Cauchy problem of the Kolmogorov-Fokker-Planck equations and show that the solution enjoys an analytic smoothing effect with L?initial datum for positive time.
基金Supported by the Natural Science Foundation of Anhui Provincial Department of Education(Grant Nos.KJ2020A 0993KJ2020ZD74)+2 种基金the High-Level Talent Research Start-Up Project(Grant No.DC2300000286)the Foundation of Guangzhou Civil Aviation College(Grant Nos.22X041824X4412).
文摘In the paper,a class of functions with bounded turnings involving cardioid domain,are studied in the region of the unit disc.The bounds of|a_(5)|,|a_(6)|,|a_(7)|and the fourth Hankel determinant are obtained,which are more accurate than those obtained by Srivastava.
文摘Renormalization group analysis has been proposed to eliminate secular terms in perturbation solutions of differential equations and thus expand the domain of their validity.Here we extend the method to treat periodic orbits or limit cycles.Interesting normal forms could be derived through a generalization of the concept'resonance',which offers nontrivial analytic approximations.Compared with traditional techniques such as multi-scale methods,the current scheme proceeds in a very straightforward and simple way,delivering not only the period and the amplitude but also the transient path to limit cycles.The method is demonstrated with several examples including the Duffing oscillator,van der Pol equation and Lorenz equation.The obtained solutions match well with numerical results and with those derived by traditional analytic methods.
基金Project(52274130)supported by the National Natural Science Foundation of ChinaProject(ZR2024ZD22)supported by the Major Basic Research Project of the Shandong Provincial Natural Science Foundation,China+2 种基金Project(2023375)supported by the Guizhou University Research and Innovation Team,ChinaProject(Leading Fund(2023)09)supported by the Natural Science Research Fund of Guizhou University,ChinaProject(JYBSYS2021101)supported by the Open Fund of Key Laboratory of Safe and Effective Coal Mining,Ministry of Education,China。
文摘The stress gradient of surrounding rock and reasonable prestress of support are the keys to ensuring the stability of roadways.The elastic-plastic analytical solution for surrounding rock was derived based on unified strength theory.A model for solving the stress gradient of the surrounding rock with the intermediate principal stress parameter b was established.The correctness and applicability of the solution for the stress gradient in the roadway surrounding rock was verified via multiple methods.Furthermore,the laws of stress,displacement,and the plastic zone of the surrounding rock with different b values and prestresses were revealed.As b increases,the stress gradient in the plastic zone increases,and the displacement and plastic zone radius decrease.As the prestress increases,the peak stress shifts toward the sidewalls,and the stress and stress gradient increments decrease.In addition,the displacement increment and plastic zone increment were proposed to characterize the support effect.The balance point of the plastic zone area appears before that of the displacement zone.The relationship between the stress gradient compensation coefficient and the prestress is obtained.This study provides a research method and idea for determining the reasonable prestress of support in roadways.
基金supported by the project VSB-TU Ostrava,SP2024/045.
文摘Renewable energy sources,including wind,solar,and biofuels,are essential for promoting sustainable economic development and mitigating environmental challenges.As China’s overseas investments in renewable energy expand,effective risk assessment and management have become critical.This study develops a comprehensive risk evaluation framework for China’s overseas renewable energy investments using the Fuzzy Analytic Hierarchy Process(FAHP).The framework incorporates political,economic,and project-specific risks,organized through three primary criteria,nine sub-criteria,and thirty tertiary indicators.By integrating expert judgments with fuzzy set theory,the FAHP methodology assigns accurate weights to risk factors and ensures consistency in evaluation.The findings identify political risks as the most significant,emphasizing their influence on investment strategies.These insights offer valuable guidance for policymakers and investors to enhance risk management strategies and ensure the sustainability of China’s renewable energy initiatives abroad.
基金The 2024 Undergraduate Education Teaching Research and Reform Project of Colleges and Universities in the Autonomous Region“Construction of School-based Digital Resources for Ideological and Political Education in the Course of Analytic Geometry”(XJGXJGPTB-2024104)。
文摘This paper delves into the visual teaching of analytic geometry facilitated by GeoGebra software.Through a meticulous analysis of the current landscape of analytic geometry instruction and the distinct advantages of GeoGebra software,it expounds upon the imperative and feasibility of its application within the realm of analytic geometry teaching.Furthermore,it presents a detailed account of the teaching practice process grounded in this software,encompassing teaching design and the demonstration of teaching cases,and conducts an in-depth investigation and analysis of the teaching outcomes.The research findings indicate that the GeoGebra software can effectively elevate the level of visualization in analytic geometry teaching,thereby augmenting students’learning enthusiasm and comprehension capabilities.It thus offers novel perspectives and methodologies for the pedagogical reform of analytic geometry.
文摘By using a certain hybrid-type convolution operator,we first introduce a new subclass of normalized analytic functions in the open unit disk.For members of this analytic function class,we then derive several properties and characteristics including(for example)the modified Hadamard products,Holder's inequalities and convolution properties as well as some closure properties under a general family of integral transforms.
基金Sponsored by National Natural Science Foundation of China(Grant No.12174101)Fundamental Research Funds for the Central Universities(Grant No.2022MS051).
文摘The analytic continuation serves as a crucial bridge between quantum Monte Carlo calculations in imaginary-time formalism,specifically the Green's functions,and physical measurements(the spectral functions)in real time.Various approaches have been developed to enhance the accuracy of analytic continuation,including the Padéapproximation,the maximum entropy method,and stochastic analytic continuation.In this study,we employ different deep learning techniques to investigate the analytic continuation for the quantum impurity model.A significant challenge in this context is that the sharp Abrikosov-Suhl resonance peak may be either underestimated or overestimated.We fit both the imaginary-time Green's function and the spectral function using Chebyshev polynomials in logarithmic coordinates.We utilize Full-Connected Networks(FCN),Convolutional Neural Networks(CNNs),and Residual Networks(ResNet)to address this issue.Our findings indicate that introducing noise during the training phase significantly improves the accuracy of the learning process.The typical absolute error achieved is less than 10-4.These investigations pave the way for machine learning to optimize the analytic continuation problem in many-body systems,thereby reducing the need for prior expertise in physics.
基金funded this manuscript for the Central Universities(Grant Nos.2662023DKPY004 and 2662021DKQD005).
文摘The gastrointestinal tract of felines is inhabited by an active and intricate population of microorganisms whose alteration creates disturbances in the immune response and can affect health and disease states.Studies using vari‑ous analytical methods have identified peculiar trends in various illnesses,with Firmicutes being the most prevalent phylum,followed by Bacteroidetes,Proteobacteria,and Actinobacteria.However,more Firmicutes and fewer Bac‑teroidetes have been observed in cats infected with Feline coronavirus.Alterations in the composition of these gut microbiota can be solved by microbiota modification through dietary fiber,probiotics,and fecal microbiota transplan‑tation.Therefore,it is critical to understand the composition of the gut microbiota,the changes in and roles of the gut environment,and the importance of these concepts for overall health while considering the exchange of microbes between humans and domestic animals.This review provides comprehensive information on feline gut microbiota composition,modulation,and analytic methods used for characterizing the gut microbiota.
基金supported by the project of the National Natural Science Foundation of China(42330705).
文摘Enhancing ecological security for sustainable social,economic,and environmental development is a key focus of current research and a practical necessity for ecological management.However,the integration of retrospective ecological security assessments with future trend predictions and fine-scale targeted regulations remains inadequate,limiting effective ecological governance and sustainable regional development.Guided by Social-Economic-Natural Complex Ecosystems(SENCE)theory,this study proposes an analytical framework that integrates ecological security assessment,prediction,and zoning management.The Daqing River Basin,a typical river basin in the North China Plain,was selected as a case study.The results indicate that overall ecological security in the Daqing River Basin improved from a“Moderate”level to a“Relatively Safe”level between 2000 and 2020;however,spatial heterogeneity persisted,with higher ecological security in northwestern and eastern regions and lower ecological security in the central region.Approximately 62% of the Basin experienced an improvement in ecological security level,except in the major urban areas of Beijing,Tianjin,and Hebei,where ecological security deteriorated.From 2025 to 2040,the overall ecological security of the Daqing River Basin is expected to improve and remain at the“Relatively Safe”level.However,spatial heterogeneity will be further aggravated as the ecological security of major urban areas continues to deteriorate.Ecological security management zones and regulation strategies are proposed at the regional and county scales to emphasize integrated regulation for the entire basin and major urban areas.The proposed analytical framework provides valuable insights for advancing theoretical research on ecological security.The case study offers a practical reference for ecological security enhancement in river basins and other regions facing significant human-land conflicts.
文摘This study evaluates the use of predictive analytics to forecast customer turnover in subscription-based Services in order to develop a predictive model to help small and medium-sized enterprises manage customer churn in the face of digital disruption.The research uses a quantitative approach focusing on empirical customer data to accurately predict buying trends and adapt marketing techniques.Demand forecasts in the health sector are important,as in every sector.In particular,the material forecast and stock forecasting of the purchasing unit of hospitals are among the areas that receive significant attention.Four classifiers(Random Forest,Logistic Regression,Gradient Boosting and XGBoost)are trained and evaluated using various performance indicators as part of a systematic approach involving Kaggle data collection,preparation and model selection.The results show excellent accuracy in predicting customer attrition,but there are limitations in precision and recall,indicating room for improvement.Confusion matrices provide information about the performance of each classifier,allowing for continuous improvement of predictive analytics techniques.Ethical concerns are rigorously addressed throughout the work process to guarantee appropriate data and machine learning methodologies.The proposals emphasize the proactive use of predictive analytics to identify at-risk customers and implement targeted retention strategies.Incorporating new data sources,improving customer experience,and utilizing collaborative churn management methods are recommended to increase forecast accuracy and business outcomes.Finally,this research provides important insights into the usefulness of predictive analytics for customer churn forecasting as well as practical recommendations for businesses seeking to increase customer retention and reduce churn risk.By leveraging empirical research findings and implementing ethical and rigorous churn control strategies,businesses can achieve long-term success in today’s changing market environment.
文摘For the solution of peridynamic equations of motion,a meshless approach is typically used instead of utilizing semi-analytical or mesh-based approaches.In contrast,the literature has limited analytical solutions.This study develops a novel analytical solution for one-dimensional peridynamic models,considering the effect of damping.After demonstrating the details of the analytical solution,various demonstration problems are presented.First,the free vibration of a damped system is considered for under-damped and critically damped conditions.Peridynamic solutions and results from the classical theory are compared against each other,and excellent agreement is observed between the two approaches.Next,forced vibration analyses of undamped and damped conditions are performed.In addition,the effect of horizon size is investigated.It is shown that for smaller horizon sizes,peridynamic results agree well with classical results,whereas results from these two approaches deviate from each other as the horizon size increases.
基金financial support from the Young Scientist Project of the National Key Research and Development Program of China(Grant No.2021YFC2900600)Beijing Nova Program(Grant No.20220484057)+1 种基金The authors acknowledge the financial support from the Natural Sciences and Engineering Research Council of Canada(Grant No.RGPIN-2018-06902)industrial partners of the Research Institute on Mines and the Environment(RIME UQAT-Polytechnique:https://irme.ca/en/).
文摘Underhand cut-and-fill mining has been widely used in underground mining operations,especially when the rock mass or orebody is of poor quality or prone to rockburst due to high stress.In such cases,mining workers should carry out all production activities under the cemented backfill roof or sill mat instead of a highly fractured and unstable rock roof or a strong rock roof with a high potential of rockburst.Therefore,the stability and required strength of the sill mat are critical issues for mining engineers.In 1991,Mitchell considered that sill mat could fail by caving,sliding,rotation,and flexure.Mitchell also proposed an analytical solution to determine the minimum required strength of the sill mat for each type of failure based on two stiff or immobile rock walls.However,recent publications using numerical modeling and field measurements indicate that the compressive stresses in the sill mat induced by rock wall closure due to a stope excavation beneath the sill mat can be significant.It is thus highly necessary to investigate the required strength of the sill mat by considering rock wall closure.In this study,the crushing failure of sill mat due to rock wall closure generated by underground excavation and a new failure mode called"crushing and caving”is revealed by numerical modeling.An analytical solution corresponding to each failure mode is then developed to estimate the minimum required cohesion(cmin)of the sill mat.A criterion is also proposed to determine if the sill mat fails by crushing or crushing-and-caving failure.The proposed analytical solution does not involve any correction coefficients.The validity of the proposed analytical solution is demonstrated by numerical modeling.The proposed analytical solution can thus be employed to predict the cmin of sill mat subjected to wall closure generated by underlying stope excavation.
