As Malaysia seeks to enhance its educational development,understanding student attitudes toward various scientific disciplines—particularly STEM fields—becomes crucial.This study investigates the perceptions of pre-...As Malaysia seeks to enhance its educational development,understanding student attitudes toward various scientific disciplines—particularly STEM fields—becomes crucial.This study investigates the perceptions of pre-university students in Malaysia regarding the geoscience discipline.Data were collected through a questionnaire designed to explore students’experiences with geoscience-related subjects and their perceptions of this essential field,focusing on their understanding and interest in geoscience.展开更多
Background:Schistosomiasis is a parasitic disease.It is caused by a prevalent infection in tropical areas and is transmitted through contaminated water with larvae parasites.Schistosomiasis is the second most parasiti...Background:Schistosomiasis is a parasitic disease.It is caused by a prevalent infection in tropical areas and is transmitted through contaminated water with larvae parasites.Schistosomiasis is the second most parasitic disease globally,so investigating its prevention and treatment is crucial.Methods:This paper aims to suggest a time-fractional model of schistosomiasis disease(T-FMSD)in the sense of the Caputo operator.The T-FMSD considers the dynamics involving susceptible ones not infected with schistosomiasis(S_(h)(t)),those infected with the infection(Ih(t)),those recovering from the disease(R(t)),susceptible snails with and without schistosomiasis infection,respectively shown by I_(v)(t)and S_(v)(t).We use a new basis function,generalized Bernoulli polynomials,for the approximate solution of T-FMSD.The operational matrices are incorporated into the method of Lagrange multipliers so that the fractional problem can be transformed into an algebraic system of equations.Results:The existence and uniqueness of the solution,and the convergence analysis of the model are established.The numerical computations are graphically presented to depict the variations of the compartments with time for varied fractional order derivatives.Conclusions:The proposed method not only provides an accurate solution but also can accurately predict schistosomiasis transmission.The results of this study will assist medical scientists in taking necessary measures during screening and treatment processes.展开更多
Asthma is the most common allergic disorder and represents a significant global public health problem.Strong evidence suggests a link between ascariasis and asthma.This study aims primarily to determine the prevalence...Asthma is the most common allergic disorder and represents a significant global public health problem.Strong evidence suggests a link between ascariasis and asthma.This study aims primarily to determine the prevalence of Ascaris lumbricoides infection among various risk factors,to assess blood parameters,levels of immunoglobulin E(IgE)and interleukin-4(IL-4),and to explore the relationship between ascariasis and asthma in affected individuals.The secondary objective is to examine a fractal-fractional mathematical model that describes the four stages of the life cycle of Ascaris infection,specifically within the framework of the Caputo-Fabrizio derivative.A case-control study was conducted that involved 270 individuals with asthma and 130 healthy controls,all of whom attended general hospitals in Duhok City,Iraq.Pulmonary function tests were performed using a micromedical spirometer.The presence of Ascaris lumbricoides antibodies-Immunoglobulin M(IgM),Immunoglobulin G(IgG),and Immunoglobulin E(IgE)-was detected using ELISA.Blood parameters were analyzed using a Coulter counter.The overall infection rate was(42.5%),with the highest rates observed among asthmatic men(70.0%)and rural residents(51.4%).Higher infection rates were also recorded among low-income individuals(64.3%)and those with frequent contact with the soil(58.6%).In particular,infected individuals exhibited a significant decrease in red blood cell count and hemoglobin concentration,while a marked increase in white blood cell count was recorded.In addition,levels of Immunoglobulin E(IgE)and interleukin-4 were significantly higher in the infected group compared to the controls.Effective disease awareness strategies that incorporate health education and preventive measures are needed.Exposure to Ascaris has been associated with reduced lung function and an increased risk of asthma.More research is required to elucidate the precise mechanisms that link Ascaris infection with asthma.Furthermore,the existence and uniqueness of solutions for the proposed model are investigated using the Krasnosel’skii and Banach fixed-point theorems.The Ulam-Hyers and Ulam-Hyers-Rassias stability types are explained within the framework of nonlinear analysis inŁp-space.Finally,an application is presented,including tabulated results and figures generated using MATLAB to illustrate the validity of the theoretical findings.展开更多
In this paper,we study the uniqueness of positive solutions to the following semilinear equations{-Δu=λ|x|^(α)ue^(u^(2)),in B_(1),u=0,onδB_(1)ueu2;in B_(1);u=0;on@B_(1);whereλ>0,α>-2;B_(1)denotes the unit ...In this paper,we study the uniqueness of positive solutions to the following semilinear equations{-Δu=λ|x|^(α)ue^(u^(2)),in B_(1),u=0,onδB_(1)ueu2;in B_(1);u=0;on@B_(1);whereλ>0,α>-2;B_(1)denotes the unit disk in R^(2):By delicate and relatively complicated computation of radial solutions to the above equation and the asymptotic expansion of solutions near the boundary of B_(1),the uniqueness of positive solutions is obtained.The results of this paper extend the uniqueness result for the semilinear equation with critical exponential growth in CHEN et al.(2022)to the case that includes a Henon term.展开更多
In this paper,we establish and study a single-species logistic model with impulsive age-selective harvesting.First,we prove the ultimate boundedness of the solutions of the system.Then,we obtain conditions for the asy...In this paper,we establish and study a single-species logistic model with impulsive age-selective harvesting.First,we prove the ultimate boundedness of the solutions of the system.Then,we obtain conditions for the asymptotic stability of the trivial solution and the positive periodic solution.Finally,numerical simulations are presented to validate our results.Our results show that age-selective harvesting is more conducive to sustainable population survival than non-age-selective harvesting.展开更多
This paper deals with Mckean-Vlasov backward stochastic differential equations with weak monotonicity coefficients.We first establish the existence and uniqueness of solutions to Mckean-Vlasov backward stochastic diff...This paper deals with Mckean-Vlasov backward stochastic differential equations with weak monotonicity coefficients.We first establish the existence and uniqueness of solutions to Mckean-Vlasov backward stochastic differential equations.Then we obtain a comparison theorem in one-dimensional situation.展开更多
Natural product(NPT)derived from traditional Chinese medicine has a rich history as an integral part of Chinese healthcare for thousands of years.Recently,the application of NPT in sonodynamic antibacterial therapy(SD...Natural product(NPT)derived from traditional Chinese medicine has a rich history as an integral part of Chinese healthcare for thousands of years.Recently,the application of NPT in sonodynamic antibacterial therapy(SDAT)has emerged as a promising area of research.This perspective summarizes the recent NPT-based sonosensitizers in SDAT.Currently,common NPT-based sonosensitizers include curcumin,chlorophyll derivatives,hypericin,and berberine.Compared with other sonosensitizers,natural sources of NPT-based sonosensitizers with reactive oxide species production performance under ultrasound conditions,low biotoxicity,and other additional biological activity make them have application prospects in bacterial removal.Finally,the potential benefits and challenges of NPT-based nanosonosensitizers were also discussed.展开更多
Aqueous Zn-iodine batteries(ZIBs)face the formidable challenges towards practical implementation,including metal corrosion and rampant dendrite growth on the Zn anode side,and shuttle effect of polyiodide species from...Aqueous Zn-iodine batteries(ZIBs)face the formidable challenges towards practical implementation,including metal corrosion and rampant dendrite growth on the Zn anode side,and shuttle effect of polyiodide species from the cathode side.These challenges lead to poor cycle stability and severe self-discharge.From the fabrication and cost point of view,it is technologically more viable to deploy electrolyte engineering than electrode protection strategies.More importantly,a synchronous method for modulation of both cathode and anode is pivotal,which has been often neglected in prior studies.In this work,cationic poly(allylamine hydrochloride)(Pah^(+))is adopted as a low-cost dual-function electrolyte additive for ZIBs.We elaborate the synchronous effect by Pah^(+)in stabilizing Zn anode and immobilizing polyiodide anions.The fabricated Zn-iodine coin cell with Pah^(+)(ZnI_(2) loading:25 mg cm^(−2))stably cycles 1000 times at 1 C,and a single-layered 3.4 cm^(2) pouch cell(N/P ratio~1.5)with the same mass loading cycles over 300 times with insignificant capacity decay.展开更多
Shikonin,a naphthoquinone compound derived from the root of Lithospermum erythrorhizon,has been extensively studied for its antibacterial,antioxidant,and anti-inflammatory properties.Increasing evidence highlights its...Shikonin,a naphthoquinone compound derived from the root of Lithospermum erythrorhizon,has been extensively studied for its antibacterial,antioxidant,and anti-inflammatory properties.Increasing evidence highlights its potential in treating inflammation-related diseases.However,its clinical application is hindered by challenges such as poor water solubility,rapid metabolism in vivo,and other limitations.Recent advancements have demonstrated that encapsulating shikonin within nanocarriers can significantly enhance its water solubility and pharmacokinetic profile.Building on this,this perspective paper outlines the current landscape of inflammation treatment,explores the anti-inflammatory mechanisms of shikonin,reviews the latest progress in shikonin-based nanomaterials for anti-inflammatory applications,and discusses the challenges and future directions for the clinical translation of shikonin nanoformulations.展开更多
The two-dimensional magneto-hydrodynamic （MHD） equations are considered in this article. Viscous approximations are used to obtain the local existence and uniqueness of the classical solution. When the viscous term ...The two-dimensional magneto-hydrodynamic （MHD） equations are considered in this article. Viscous approximations are used to obtain the local existence and uniqueness of the classical solution. When the viscous term vanishes, the convergence rates, a main problem in turbulence, are also discussed. Moreover, a blow-up criterion for our classical solution is established in terms of the magnetic fields.展开更多
For many continuous bio-medieal signals with both strong nonlinearity and non-stationarity, two criterions were proposed for their complexity estimation ： （1） Only a short data set is enough for robust estimation; ...For many continuous bio-medieal signals with both strong nonlinearity and non-stationarity, two criterions were proposed for their complexity estimation ： （1） Only a short data set is enough for robust estimation; （2） No over-coarse graining preproeessing, such as transferring the original signal into a binary time series, is needed. Co complexity measure proposed by us previously is one of such measures. However, it lacks the solid mathematical foundation and thus its use is limited. A modified version of this measure is proposed, and some important properties are proved rigorously. According to these properties, this measure can be considered as an index of randomness of time series in some senses, and thus also a quantitative index of complexity under the meaning of randomness finding complexity. Compared with other similar measures, this measure seems more suitable for estimating a large quantity of complexity measures for a given task, such as studying the dynamic variation of such measures in sliding windows of a long process, owing to its fast speed for estimation.展开更多
In this paper we work with the ordinary diffential equation u′′ u3 = 0 and obtain some interesting phenomena concerning blow-up, blow-up rate, life-spann, zeros and critical points of solutions to this equation.
This paper presents the development and implementation of an innovative mixed integer programming based mathematical model for an open pit mining operation with Grade Engineering framework.Grade Engineering comprises ...This paper presents the development and implementation of an innovative mixed integer programming based mathematical model for an open pit mining operation with Grade Engineering framework.Grade Engineering comprises a range of coarse-separation based pre-processing techniques that separate the desirable(i.e.high-grade)and undesirable(i.e.low-grade or uneconomic)materials and ensure the delivery of only selected quantity of high quality(or high-grade)material to energy,water,and cost-intensive processing plant.The model maximizes the net present value under a range of operational and processing constraints.Given that the proposed model is computationally complex,the authors employ a data preprocessing procedure and then evaluate the performance of the model at several practical instances using computation time,optimality gap,and the net present value as valid measures.In addition,a comparison of the proposed and traditional(without Grade Engineering)models reflects that the proposed model outperforms the traditional formulation.展开更多
The running correlation coefficient(RCC)is useful for capturing temporal variations in correlations between two time series.The local running correlation coefficient(LRCC)is a widely used algorithm that directly appli...The running correlation coefficient(RCC)is useful for capturing temporal variations in correlations between two time series.The local running correlation coefficient(LRCC)is a widely used algorithm that directly applies the Pearson correlation to a time window.A new algorithm called synthetic running correlation coefficient(SRCC)was proposed in 2018 and proven to be rea-sonable and usable;however,this algorithm lacks a theoretical demonstration.In this paper,SRCC is proven theoretically.RCC is only meaningful when its values at different times can be compared.First,the global means are proven to be the unique standard quantities for comparison.SRCC is the only RCC that satisfies the comparability criterion.The relationship between LRCC and SRCC is derived using statistical methods,and SRCC is obtained by adding a constraint condition to the LRCC algorithm.Dividing the temporal fluctuations into high-and low-frequency signals reveals that LRCC only reflects the correlation of high-frequency signals;by contrast,SRCC reflects the correlations of high-and low-frequency signals simultaneously.Therefore,SRCC is the ap-propriate method for calculating RCCs.展开更多
Grain crushing is commonly encountered in deep foundation engineering,high rockfill dam engineering,railway engineering,mining engineering,coastal engineering,petroleum engineering,and other geoscience application.Gra...Grain crushing is commonly encountered in deep foundation engineering,high rockfill dam engineering,railway engineering,mining engineering,coastal engineering,petroleum engineering,and other geoscience application.Grain crushing is affected by fundamental soil characteristics,such as their mineral strength,grain size and distribution,grain shape,density and specimen size,and also by external factors including stress magnitude and path,loading rate and duration,degree of saturation,temperature and geochemical environment.Crushable material becomes a series of different materials with the change in its grading during grain crushing,resulting in a decrease in strength and dilatancy and an increase in compressibility.Effects of grain crushing on strength,dilatancy,deformation and failure mechanisms have been extensively investigated through laboratory testing,discrete element method(DEM)modelling,Weibull statistics,and constitutive modelling within the framework of the extended crushing-dependent critical state theory or the energy-based theory.Eleven papers summarized in this review article for this special issue addressed the above issues in grain crushing through the advanced testing and modelling.展开更多
In this paper, we work with the ordinary differential equation n^2u （n）＂ = u（n）^p and obtain some interesting phenomena concerning, boundedness, blow-up, blow-up rate, life-span of solutions to those equations.
This paper introduces a new spontaneous potential log model for the case in which formation resistivity is not piecewise constant. The spontaneous potential satisfies an elliptic boundary value problem with jump condi...This paper introduces a new spontaneous potential log model for the case in which formation resistivity is not piecewise constant. The spontaneous potential satisfies an elliptic boundary value problem with jump conditions on the interfaces. It has beer/ shown that the elliptic interface problem has a unique weak solution. Furthermore, a jump condition capturing finite difference scheme is proposed and applied to solve such elliptic problems. Numerical results show validity and effectiveness of the proposed method.展开更多
A model based on chemical kinetics for the rate of utilization and/or storage of carbohydrates, fats and proteins is derived and analyzed. This system is studied under different conditions of supply and usage and for ...A model based on chemical kinetics for the rate of utilization and/or storage of carbohydrates, fats and proteins is derived and analyzed. This system is studied under different conditions of supply and usage and for short term dynamics and long term dynamics. Both the short term and long term models indicate that starting above an equilibrium threshold leads to growth of the stored species. Results from the short-term and long-term submodels show that the qualitative behavior depends on the levels of certain enzymes. The analysis of a model for enzyme dynamics indicates that the steady-state level of an enzyme should depend on the rate of supply of the substrate.展开更多
In this study, we investigate the dynamics of the COVID-19 epidemic in Northern Ireland from 1<sup>st</sup> March 2020 up to 25<sup>th</sup> December 2020, using sever</span><span>&...In this study, we investigate the dynamics of the COVID-19 epidemic in Northern Ireland from 1<sup>st</sup> March 2020 up to 25<sup>th</sup> December 2020, using sever</span><span><span style="font-family:Verdana;">al copies of a Susceptible-Exposed-Infectious-Recovered (<i></span><i><span style="font-family:Verdana;">SEIR</span></i><span style="font-family:Verdana;"></i>) compart</span></span><span style="font-family:Verdana;">mental model, and compare it to </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">a </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">detailed publicly available dataset. We split the data into 10 time intervals and fit the models on the consecutive intervals to the cumulative number of confirmed positive cases on each interval. Using the fitted parameter estimates, we also provide estimates of the reproduction number.</span><span style="font-family:Verdana;"> We also discuss the limitations and possible extensions of the employed model.展开更多
文摘As Malaysia seeks to enhance its educational development,understanding student attitudes toward various scientific disciplines—particularly STEM fields—becomes crucial.This study investigates the perceptions of pre-university students in Malaysia regarding the geoscience discipline.Data were collected through a questionnaire designed to explore students’experiences with geoscience-related subjects and their perceptions of this essential field,focusing on their understanding and interest in geoscience.
文摘Background:Schistosomiasis is a parasitic disease.It is caused by a prevalent infection in tropical areas and is transmitted through contaminated water with larvae parasites.Schistosomiasis is the second most parasitic disease globally,so investigating its prevention and treatment is crucial.Methods:This paper aims to suggest a time-fractional model of schistosomiasis disease(T-FMSD)in the sense of the Caputo operator.The T-FMSD considers the dynamics involving susceptible ones not infected with schistosomiasis(S_(h)(t)),those infected with the infection(Ih(t)),those recovering from the disease(R(t)),susceptible snails with and without schistosomiasis infection,respectively shown by I_(v)(t)and S_(v)(t).We use a new basis function,generalized Bernoulli polynomials,for the approximate solution of T-FMSD.The operational matrices are incorporated into the method of Lagrange multipliers so that the fractional problem can be transformed into an algebraic system of equations.Results:The existence and uniqueness of the solution,and the convergence analysis of the model are established.The numerical computations are graphically presented to depict the variations of the compartments with time for varied fractional order derivatives.Conclusions:The proposed method not only provides an accurate solution but also can accurately predict schistosomiasis transmission.The results of this study will assist medical scientists in taking necessary measures during screening and treatment processes.
文摘Asthma is the most common allergic disorder and represents a significant global public health problem.Strong evidence suggests a link between ascariasis and asthma.This study aims primarily to determine the prevalence of Ascaris lumbricoides infection among various risk factors,to assess blood parameters,levels of immunoglobulin E(IgE)and interleukin-4(IL-4),and to explore the relationship between ascariasis and asthma in affected individuals.The secondary objective is to examine a fractal-fractional mathematical model that describes the four stages of the life cycle of Ascaris infection,specifically within the framework of the Caputo-Fabrizio derivative.A case-control study was conducted that involved 270 individuals with asthma and 130 healthy controls,all of whom attended general hospitals in Duhok City,Iraq.Pulmonary function tests were performed using a micromedical spirometer.The presence of Ascaris lumbricoides antibodies-Immunoglobulin M(IgM),Immunoglobulin G(IgG),and Immunoglobulin E(IgE)-was detected using ELISA.Blood parameters were analyzed using a Coulter counter.The overall infection rate was(42.5%),with the highest rates observed among asthmatic men(70.0%)and rural residents(51.4%).Higher infection rates were also recorded among low-income individuals(64.3%)and those with frequent contact with the soil(58.6%).In particular,infected individuals exhibited a significant decrease in red blood cell count and hemoglobin concentration,while a marked increase in white blood cell count was recorded.In addition,levels of Immunoglobulin E(IgE)and interleukin-4 were significantly higher in the infected group compared to the controls.Effective disease awareness strategies that incorporate health education and preventive measures are needed.Exposure to Ascaris has been associated with reduced lung function and an increased risk of asthma.More research is required to elucidate the precise mechanisms that link Ascaris infection with asthma.Furthermore,the existence and uniqueness of solutions for the proposed model are investigated using the Krasnosel’skii and Banach fixed-point theorems.The Ulam-Hyers and Ulam-Hyers-Rassias stability types are explained within the framework of nonlinear analysis inŁp-space.Finally,an application is presented,including tabulated results and figures generated using MATLAB to illustrate the validity of the theoretical findings.
基金Supported by the Natural Science Foundation of China(12571122,12061010)。
文摘In this paper,we study the uniqueness of positive solutions to the following semilinear equations{-Δu=λ|x|^(α)ue^(u^(2)),in B_(1),u=0,onδB_(1)ueu2;in B_(1);u=0;on@B_(1);whereλ>0,α>-2;B_(1)denotes the unit disk in R^(2):By delicate and relatively complicated computation of radial solutions to the above equation and the asymptotic expansion of solutions near the boundary of B_(1),the uniqueness of positive solutions is obtained.The results of this paper extend the uniqueness result for the semilinear equation with critical exponential growth in CHEN et al.(2022)to the case that includes a Henon term.
基金Supported by the National Natural Science Foundation of China(12261018)Universities Key Laboratory of Mathematical Modeling and Data Mining in Guizhou Province(2023013)。
文摘In this paper,we establish and study a single-species logistic model with impulsive age-selective harvesting.First,we prove the ultimate boundedness of the solutions of the system.Then,we obtain conditions for the asymptotic stability of the trivial solution and the positive periodic solution.Finally,numerical simulations are presented to validate our results.Our results show that age-selective harvesting is more conducive to sustainable population survival than non-age-selective harvesting.
基金Supported by the National Natural Science Foundation of China(12001074)the Research Innovation Program of Graduate Students in Hunan Province(CX20220258)+1 种基金the Research Innovation Program of Graduate Students of Central South University(1053320214147)the Key Scientific Research Project of Higher Education Institutions in Henan Province(25B110025)。
文摘This paper deals with Mckean-Vlasov backward stochastic differential equations with weak monotonicity coefficients.We first establish the existence and uniqueness of solutions to Mckean-Vlasov backward stochastic differential equations.Then we obtain a comparison theorem in one-dimensional situation.
基金supported by the Innovation and Entrepreneurship Training Program for College Students(X2025102911746,X2025102910483).
文摘Natural product(NPT)derived from traditional Chinese medicine has a rich history as an integral part of Chinese healthcare for thousands of years.Recently,the application of NPT in sonodynamic antibacterial therapy(SDAT)has emerged as a promising area of research.This perspective summarizes the recent NPT-based sonosensitizers in SDAT.Currently,common NPT-based sonosensitizers include curcumin,chlorophyll derivatives,hypericin,and berberine.Compared with other sonosensitizers,natural sources of NPT-based sonosensitizers with reactive oxide species production performance under ultrasound conditions,low biotoxicity,and other additional biological activity make them have application prospects in bacterial removal.Finally,the potential benefits and challenges of NPT-based nanosonosensitizers were also discussed.
基金supported by the financial support from the National Research Foundation,Singapore,under its Singapore-China Joint Flagship Project(Clean Energy).
文摘Aqueous Zn-iodine batteries(ZIBs)face the formidable challenges towards practical implementation,including metal corrosion and rampant dendrite growth on the Zn anode side,and shuttle effect of polyiodide species from the cathode side.These challenges lead to poor cycle stability and severe self-discharge.From the fabrication and cost point of view,it is technologically more viable to deploy electrolyte engineering than electrode protection strategies.More importantly,a synchronous method for modulation of both cathode and anode is pivotal,which has been often neglected in prior studies.In this work,cationic poly(allylamine hydrochloride)(Pah^(+))is adopted as a low-cost dual-function electrolyte additive for ZIBs.We elaborate the synchronous effect by Pah^(+)in stabilizing Zn anode and immobilizing polyiodide anions.The fabricated Zn-iodine coin cell with Pah^(+)(ZnI_(2) loading:25 mg cm^(−2))stably cycles 1000 times at 1 C,and a single-layered 3.4 cm^(2) pouch cell(N/P ratio~1.5)with the same mass loading cycles over 300 times with insignificant capacity decay.
基金supported by the National Natural Science Foundation of China(82373393),Xinjiang Uygur Autonomous Region“Tianchi Yingcai”Project(2023TCYCQNBS02)Xinjiang Uygur Autonomous Region Colleges and Universities Basic Research Operating Expenses Scientific Research Project(XJEDU2022P106).
文摘Shikonin,a naphthoquinone compound derived from the root of Lithospermum erythrorhizon,has been extensively studied for its antibacterial,antioxidant,and anti-inflammatory properties.Increasing evidence highlights its potential in treating inflammation-related diseases.However,its clinical application is hindered by challenges such as poor water solubility,rapid metabolism in vivo,and other limitations.Recent advancements have demonstrated that encapsulating shikonin within nanocarriers can significantly enhance its water solubility and pharmacokinetic profile.Building on this,this perspective paper outlines the current landscape of inflammation treatment,explores the anti-inflammatory mechanisms of shikonin,reviews the latest progress in shikonin-based nanomaterials for anti-inflammatory applications,and discusses the challenges and future directions for the clinical translation of shikonin nanoformulations.
基金The research is partially supported by NSF of China (10431060)NSF of Beijing (1042003)key project of NSFB-FBEC
文摘The two-dimensional magneto-hydrodynamic （MHD） equations are considered in this article. Viscous approximations are used to obtain the local existence and uniqueness of the classical solution. When the viscous term vanishes, the convergence rates, a main problem in turbulence, are also discussed. Moreover, a blow-up criterion for our classical solution is established in terms of the magnetic fields.
文摘For many continuous bio-medieal signals with both strong nonlinearity and non-stationarity, two criterions were proposed for their complexity estimation ： （1） Only a short data set is enough for robust estimation; （2） No over-coarse graining preproeessing, such as transferring the original signal into a binary time series, is needed. Co complexity measure proposed by us previously is one of such measures. However, it lacks the solid mathematical foundation and thus its use is limited. A modified version of this measure is proposed, and some important properties are proved rigorously. According to these properties, this measure can be considered as an index of randomness of time series in some senses, and thus also a quantitative index of complexity under the meaning of randomness finding complexity. Compared with other similar measures, this measure seems more suitable for estimating a large quantity of complexity measures for a given task, such as studying the dynamic variation of such measures in sliding windows of a long process, owing to its fast speed for estimation.
基金financed by NSC, Metta Education, Grand Hall Company and Auria Solar Company
文摘In this paper we work with the ordinary diffential equation u′′ u3 = 0 and obtain some interesting phenomena concerning blow-up, blow-up rate, life-spann, zeros and critical points of solutions to this equation.
文摘This paper presents the development and implementation of an innovative mixed integer programming based mathematical model for an open pit mining operation with Grade Engineering framework.Grade Engineering comprises a range of coarse-separation based pre-processing techniques that separate the desirable(i.e.high-grade)and undesirable(i.e.low-grade or uneconomic)materials and ensure the delivery of only selected quantity of high quality(or high-grade)material to energy,water,and cost-intensive processing plant.The model maximizes the net present value under a range of operational and processing constraints.Given that the proposed model is computationally complex,the authors employ a data preprocessing procedure and then evaluate the performance of the model at several practical instances using computation time,optimality gap,and the net present value as valid measures.In addition,a comparison of the proposed and traditional(without Grade Engineering)models reflects that the proposed model outperforms the traditional formulation.
基金This study was supported by the National Natural Sci-ence Foundation of China(Nos.41976022,41941012)the Major Scientific and Technological Innovation Projects of Shandong Province(No.2018SDKJ0104-1).
文摘The running correlation coefficient(RCC)is useful for capturing temporal variations in correlations between two time series.The local running correlation coefficient(LRCC)is a widely used algorithm that directly applies the Pearson correlation to a time window.A new algorithm called synthetic running correlation coefficient(SRCC)was proposed in 2018 and proven to be rea-sonable and usable;however,this algorithm lacks a theoretical demonstration.In this paper,SRCC is proven theoretically.RCC is only meaningful when its values at different times can be compared.First,the global means are proven to be the unique standard quantities for comparison.SRCC is the only RCC that satisfies the comparability criterion.The relationship between LRCC and SRCC is derived using statistical methods,and SRCC is obtained by adding a constraint condition to the LRCC algorithm.Dividing the temporal fluctuations into high-and low-frequency signals reveals that LRCC only reflects the correlation of high-frequency signals;by contrast,SRCC reflects the correlations of high-and low-frequency signals simultaneously.Therefore,SRCC is the ap-propriate method for calculating RCCs.
基金financial support from the National Science Foundation of China (Grant Nos. 51922024, 41831282, 51678094 and 51578096)
文摘Grain crushing is commonly encountered in deep foundation engineering,high rockfill dam engineering,railway engineering,mining engineering,coastal engineering,petroleum engineering,and other geoscience application.Grain crushing is affected by fundamental soil characteristics,such as their mineral strength,grain size and distribution,grain shape,density and specimen size,and also by external factors including stress magnitude and path,loading rate and duration,degree of saturation,temperature and geochemical environment.Crushable material becomes a series of different materials with the change in its grading during grain crushing,resulting in a decrease in strength and dilatancy and an increase in compressibility.Effects of grain crushing on strength,dilatancy,deformation and failure mechanisms have been extensively investigated through laboratory testing,discrete element method(DEM)modelling,Weibull statistics,and constitutive modelling within the framework of the extended crushing-dependent critical state theory or the energy-based theory.Eleven papers summarized in this review article for this special issue addressed the above issues in grain crushing through the advanced testing and modelling.
基金financed by NSC,Metta Education,Grand Hall Company and Auria Solar Company
文摘In this paper, we work with the ordinary differential equation n^2u （n）＂ = u（n）^p and obtain some interesting phenomena concerning, boundedness, blow-up, blow-up rate, life-span of solutions to those equations.
基金supported by the National Natural Science Foundation of China (No. 10431030)the Shanghai Natural Science Foundation (No. 08ZR1401100)
文摘This paper introduces a new spontaneous potential log model for the case in which formation resistivity is not piecewise constant. The spontaneous potential satisfies an elliptic boundary value problem with jump conditions on the interfaces. It has beer/ shown that the elliptic interface problem has a unique weak solution. Furthermore, a jump condition capturing finite difference scheme is proposed and applied to solve such elliptic problems. Numerical results show validity and effectiveness of the proposed method.
文摘A model based on chemical kinetics for the rate of utilization and/or storage of carbohydrates, fats and proteins is derived and analyzed. This system is studied under different conditions of supply and usage and for short term dynamics and long term dynamics. Both the short term and long term models indicate that starting above an equilibrium threshold leads to growth of the stored species. Results from the short-term and long-term submodels show that the qualitative behavior depends on the levels of certain enzymes. The analysis of a model for enzyme dynamics indicates that the steady-state level of an enzyme should depend on the rate of supply of the substrate.
文摘In this study, we investigate the dynamics of the COVID-19 epidemic in Northern Ireland from 1<sup>st</sup> March 2020 up to 25<sup>th</sup> December 2020, using sever</span><span><span style="font-family:Verdana;">al copies of a Susceptible-Exposed-Infectious-Recovered (<i></span><i><span style="font-family:Verdana;">SEIR</span></i><span style="font-family:Verdana;"></i>) compart</span></span><span style="font-family:Verdana;">mental model, and compare it to </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">a </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">detailed publicly available dataset. We split the data into 10 time intervals and fit the models on the consecutive intervals to the cumulative number of confirmed positive cases on each interval. Using the fitted parameter estimates, we also provide estimates of the reproduction number.</span><span style="font-family:Verdana;"> We also discuss the limitations and possible extensions of the employed model.
