As seismic signals propagate underground,the subsurface media absorb high-frequency components,decreasing seismic resolution and limiting the identification and characterization of thin reservoirs.To address the limit...As seismic signals propagate underground,the subsurface media absorb high-frequency components,decreasing seismic resolution and limiting the identification and characterization of thin reservoirs.To address the limitation,this paper proposes a multichannel spectral fitting(MSF)method.The MSF method aims to enhance seismic resolution by considering the spectral characteristics and the correlations between adjacent seismic traces.The key to the MSF method involves utilizing the amplitude spectrum of the attenuated Ricker wavelet to construct an objective function for spectral fitting,leading to improved seismic resolution.Furthermore,the MSF method establishes the correlation between adjacent seismic traces as a constraint to stably solve the target parameters based on the entire seismic spectrum,which helps obtain horizontally consistent and more realistic seismic signals.Synthetic and field seismic examples demonstrate that the proposed method not only provides higher-resolution seismic signals but also reveals more fine details of thin reservoirs compared to the time-variant spectral whitening method.It is concluded that the MSF method is a promising tool for seismic signal processing.展开更多
In modern industrial applications,ensuring the reliability of mechanical fittings is critical for maintaining operational safety and efficiency,particularly in power grid systems where split pins serve a pivotal role ...In modern industrial applications,ensuring the reliability of mechanical fittings is critical for maintaining operational safety and efficiency,particularly in power grid systems where split pins serve a pivotal role despite being susceptible to environmental degradation and failure.Existing UAV-based inspection systems are hampered by a low representation of split pin elements and complex backgrounds,leading to challenges in accurate fault detection and timely maintenance.To address this pressing issue,our study proposes an innovative fault detection method for split pins.The approach employs a three-step process:first,cropping operations are used to accurately isolate the fittings containing split pins;second,super-resolution reconstruction is applied to enhance image clarity and detail;and finally,an improved YOLOv8 network,augmented with inner-shape IoU and local window attention mechanisms,is utilized to refine local feature extraction and annotation accuracy.Experimental evaluations on a split pin defect dataset demonstrate robust performance,achieving an accuracy rate of 72.1%and a mean average precision(mAP)of 67.7%,thereby validating the method’s effectiveness under challenging conditions.The proposed approach contributes to the field by specifically targeting the challenges associated with split pin detection in UAV-based inspections,offering a practically applicable and reliably precise method.展开更多
The ratio of the pressure drop force to the drag force,C_(P),is concerned for a non-closely fitting spherical particle settling along the central line in long rectangular tubes with different A_(r)(A_(r)is W/H,where W...The ratio of the pressure drop force to the drag force,C_(P),is concerned for a non-closely fitting spherical particle settling along the central line in long rectangular tubes with different A_(r)(A_(r)is W/H,where W,H is length of the longer and shorter side of the rectangle respectively).Under Stokes flow conditions,C_(P0)for an infinitely small sphere in long rectangular tubes and C_(P)for a sphere in a long channel between two parallel layered barriers are both calculated.Then C_(P)of a sphere settling in long rectangular tubes are conducted with the direct-forcing fictitious domain(DF/FD)method.At large Reynolds number,the sphere settles unstably with a fluctuating velocity and C_(P).The fluctuation of Cp is much stronger than that of velocity and both fluctuations are stronger for less confined sphere.The influences of the particle Reynolds number(Re_(p))on C_(P)is similar to the existing experimental results in long circular tubes.At low Re_(p),C_(P)is a determined value and is calculated.For a given d/H(d sphere diameter),Cp gets its maximum value at one A_(r)in the range of[1,1.5].For a given A_(r),C_(P)is a quadratic function of d/H similar to that in a circular tube,and parameters of the quadratic function are got by curve fitting from numerical data.The constant term coefficients got have almost no difference with C_(P0)and are furtherly replaced by the latter to get new quadratic coefficients C_(P1).Lastly,an algebraic correlation of C_(P1)to A_(r)is developed.The predictions of Cp are good with a maximum relative error about 1.5%for a sphere with d/H not greater than0.7,compared to numerical results.展开更多
The energy spectrum of energetic particles in space often shows a non-thermal spectral shape with two spectral transitions/breaks over a wide energy range, carrying crucial information about their acceleration, releas...The energy spectrum of energetic particles in space often shows a non-thermal spectral shape with two spectral transitions/breaks over a wide energy range, carrying crucial information about their acceleration, release and transportation process. To self-consistently characterize the spectral features of energetic particles, here we propose a novel extended pan-spectrum(EPS) formula to fit the particle energy-flux spectrum, which has the merit that can incorporate many commonly used spectrum functions with one spectral transition, including the pan-spectrum, double-power-law, Kappa, Ellison-Ramaty(ER) functions, etc. The formula can also determine the spectral shape with two spectral transitions, including the triple-power-law function, Kappa distribution(at low energy)plus power law(at high energy), power law(at low energy) plus ER function, etc. Considering the uncertainties in both J and E, we can fit this EPS formula well to the representative energy spectra of various particle phenomena in space, including solar energetic particles(electrons, protons, ~3He and heavier ions), anomalous cosmic rays, solar wind suprathermal particles(halo and superhalo electrons;pick-up ions and the suprathermal tail), etc. Therefore, the EPS fitting can help us self-consistently determine the spectral features of different particle phenomena, and improve our understanding of the physical nature of the origin, acceleration, and transportation of energetic particles in space.展开更多
Recently,researchers have proposed an emitter localization method based on passive synthetic aperture.However,the unknown residual frequency offset(RFO)between the transmit-ter and the receiver causes the received Dop...Recently,researchers have proposed an emitter localization method based on passive synthetic aperture.However,the unknown residual frequency offset(RFO)between the transmit-ter and the receiver causes the received Doppler signal to shift,which affects the localization accu-racy.To solve this issue,this paper proposes a RFO estimation method based on range migration fitting.Due to the high frequency modulation slope of the linear frequency modulation(LFM)-mod-ulation radar signal,it is not affected by RFO in range compression.Therefore,the azimuth time can be estimated by fitting the peak value position of the pulse compression in range direction.Then,the matched filters are designed under different RFOs.When the zero-Doppler time obtained by the matched filters is consistent with the estimated azimuth time,the given RFO is the real RFO between the transceivers.The simulation results show that the estimation error of azimuth distance does not exceed 20 m when the received signal duration is not less than 3 s,the pulse repe-tition frequency(PRF)of the transmitter radar signal is not less than 1 kHz,the range detection is not larger than 1000 km,and the signal noise ratio(SNR)is not less than-5 dB.展开更多
Background:Physicalfitness in childhood and adolescence is associated with a variety of health outcomes and is a powerful marker of current and future health.However,inconsistencies in tests and protocols limit interna...Background:Physicalfitness in childhood and adolescence is associated with a variety of health outcomes and is a powerful marker of current and future health.However,inconsistencies in tests and protocols limit international monitoring and surveillance.The objective of the study was to seek international consensus on a proposed,evidence-informed,Youth Fitness International Test(YFIT)battery and protocols for health monitoring and surveillance in children and adolescents aged 618 years.Methods:We conducted an international modified Delphi study to evaluate the level of agreement with a proposed,evidence-based,YFIT of core health-relatedfitness tests and protocols to be used worldwide in 6-to 18-year-olds.This proposal was based on previous European and North American projects that systematically reviewed the existing evidence to identify the most valid,reliable,health-related,safe,and feasiblefitness tests to be used in children and adolescents aged 618 years.We designed a single-panel modified Delphi study and invited 216 experts from all around the world to answer this Delphi survey,of whom one-third are from low-to-middle income countries and one-third are women.Four experts were involved in the piloting of the survey and did not participate in the main Delphi study to avoid bias.We pre-defined an agreement of 80%among the expert participants to achieve consensus.Results:We obtained a high response rate(78%)with a total of 169fitness experts from 50 countries and territories,including 63 women and 61 experts from low-or middle-income countries/territories.Consensus(>85%agreement)was achieved for all proposed tests and protocols,supporting the YFIT battery,which includes weight and height(to compute body mass index as a proxy of body size/composition),the 20-m shuttle run(cardiorespiratoryfitness),handgrip strength,and standing long jump(muscularfitness).Conclusion:This study contributes to standardizingfitness tests and protocols used for research,monitoring,and surveillance across the world,which will allow for future data pooling and the development of international and regional sex-and age-specific reference values,health-related cut-points,and a global picture offitness among children and adolescents.展开更多
Objective To study the increasing use of sports and fitness APPs against the background of national fitness and post-epidemic era,and to provide some suggestions for the development of sports and fitness APPs.Methods ...Objective To study the increasing use of sports and fitness APPs against the background of national fitness and post-epidemic era,and to provide some suggestions for the development of sports and fitness APPs.Methods Literature survey and mathematical statistics were used to define the concept of sports and fitness APPs,and their characteristics and advantages were investigated.Then,their problems were pointed out.Results and Conclusion The existing problems include some APPs favoring female users,single function,and slightly backward profit model.Some countermeasures such as enriching course types,taking into account all categories of users,expanding more functions,improving service quality,broadening profit channels,and improving marketing level are put forward.This can provide theoretical basis for the operation of sports and fitness APPs and better popularize the culture of national fitness.展开更多
BACKGROUND The prevalence of metabolic syndrome(MetS)in adolescents is rising,correlating with the global increase in obesity and physical inactivity.AIM To examine the individual and combined associations of fitness,...BACKGROUND The prevalence of metabolic syndrome(MetS)in adolescents is rising,correlating with the global increase in obesity and physical inactivity.AIM To examine the individual and combined associations of fitness,fatness,visceral adiposity index(VAI),and lipid ratios with MetS risk in Nigerian adolescents.METHODS This cross-sectional study included a sample of 403 adolescents(201 girls and 202 boys)aged 11-19 years.Participants were assessed for cardiorespiratory fitness,body mass index(BMI),VAI,triglyceride-to-high-density lipoprotein cholesterol ratio(TG/HDL-C),and total cholesterol-to-high-density lipoprotein cholesterol ratio(TC/HDL-C).Regression models adjusted for age and sexual maturity were used to determine the associations between these health markers and MetS risk.RESULTS Among the 177 high-risk adolescents,56.6%were at risk of central obesity,49.1%had low fitness,33.3%had dyslipidemia,and 11.7%were obese.After controlling for confounding variables,all health markers were independently and jointly associated with MetS risk,with VAI displaying the strongest explanatory power(girls:β=1.308,P<0.001;boys:β=2.300,P<0.001).Unfit girls were 5.1%more likely to be at risk of MetS,while the odds of unfit boys being at risk of MetS is 3.6.Boys with elevated VAI were 22.3 times more likely to be at risk of MetS,while the likelihood of girls with elevated VAI developing MetS risk is 2.78.CONCLUSION Health markers were independently and jointly associated with MetS risk in adolescents,with VAI and dyslip-idemia contributing most significantly.Promoting healthy eating and also aerobic activities among adolescents is crucial for improving metabolic health.展开更多
This opinion article discusses the original research work of Yünkül et al.(the Authors)published in the Journal of Mountain Science 21(9):3108–3122.Employing non-linear regression,fuzzy logic and artificial...This opinion article discusses the original research work of Yünkül et al.(the Authors)published in the Journal of Mountain Science 21(9):3108–3122.Employing non-linear regression,fuzzy logic and artificial neural network modeling techniques,the Authors interrogated a large database assembled from the existing research literature to assess the performance of twelve equation rules in predicting the undrained shear strength(s_(u))mobilized for remolded fine-grained soils at different values of liquidity index(I_(L))and water content ratio.Based on their analyses,the Authors proposed a simple and reportedly reliable correlation(i.e.,Eq.9 in their paper)for predicting s_(u) over the I_(L) range of 0.15 to 3.00.This article describes various shortcomings in the Authors’assembled database(including potentially anomalous data and covering an excessively wide I_(L) range in relation to routine geotechnical and transportation engineering applications)and their proposed s_(u)=f(I_(L))correlation.Contrary to the Authors’assertions,their proposed correlation is not reliable for fine-grained soils with consistencies in the general firm to stiff range(i.e.,for 0.15<I_(L)<0.40),increasingly overestimating s_(u) for reducing I_(L),and eventually predicting s_(u)→+∞for I_(L)→0.15+(while producing mathematically undefined s_(u) for I_(L)<0.15),thus rendering their correlation unconservative and potentially leading to unsafe geotechnical designs.Exponential or regular-power type s_(u)=f(I_(L))models are more s_(u)itable when developing correlations that are applicable over the full plastic range(of 0<I_(L)<1),thereby providing reasonably conservative s_(u) predictions for use in the preliminary design for routine geotechnical engineering applications.展开更多
Measuring cardiorespiratory fitness(CRF)is an important predictor of morbidity and mortality in epidemiological studies and clinical settings.1 However,the feasibility of measuring maximal CRF is low due to the time,e...Measuring cardiorespiratory fitness(CRF)is an important predictor of morbidity and mortality in epidemiological studies and clinical settings.1 However,the feasibility of measuring maximal CRF is low due to the time,equipment,and expertise needed to conduct laboratory cardiopulmonary exercise testing(CPET)to determine the maximal rate of oxygen uptake(VO2max)as an objective measure of CRF.Alternatively,indirect estimates of CRF have been applied by measuring maximal duration on treadmill or cycle ergometer tests,2,3 extrapolating maximal CRF from workload or heart rate during submaximal fitness tests,4,5 and using non-exercise algorithms to estimate CRF from an individual’s age,sex,body mass,and physical activity habits.6 It is assumed that objectively measured VO2max is superior to extrapolated and estimated values due to errors associated with the estimated values;7,8 however,until Singh et al.9 newly released article in the Journal of Sport and Health Science,the comparability of these methods in identifying risks for all-cause and cardiovascular disease(CVD)mortality was unknown.展开更多
Many experiments have supported the contact models,such as the GW and MB models,but the majority of previous validations have been performed under light loads,resulting in a linear relationship between normal force an...Many experiments have supported the contact models,such as the GW and MB models,but the majority of previous validations have been performed under light loads,resulting in a linear relationship between normal force and contact area.However,the real contact area fraction should never equal one;there must be a limit smaller than the apparent area,implying that the real contact area cannot increase linearly indefinitely.In this paper,the real contact area between two polymethylmethacrylate(PMMA)blocks under heavy load is measured using the total reflection method,and the contact area is analyzed using the image processing method.The results show that the real contact area increases with normal load linearly in light loads but non-linearly in heavy loads;the number of contact spots increases with load linearly in light loads but also non-linearly in heavy loads,synchronous with the change in the real contact area.The GW,MB,and Zhao,Maietta,and Chang(ZMC)models were used to predict the experiment results,but none of them predicted the non-linear stage.A revised GW model based on the bulk deformation hypothesis performs better in predicting the non-linear stage.The study’s findings can be applied to PMMA or other similar materials,and they can serve as a useful reference for future research on the contact mechanisms of other materials.展开更多
Background:Cardiorespiratory fitness(CRF)is a powerful health marker recommended by the American Heart Association as a clinical vital sign.Comparing the predictive validity of objectively measured CRF(the"gold s...Background:Cardiorespiratory fitness(CRF)is a powerful health marker recommended by the American Heart Association as a clinical vital sign.Comparing the predictive validity of objectively measured CRF(the"gold standara")and estimated CRF is clinically relevant because estimated CRF is more feasible.Our objective was to meta-analyze cohort studies to compare the associations of objectively measured,exerciseestimated,and non-exercise-estimated CRF with all-cause and cardiovascular disease(CVD)mortality in adults.Methods:Systematic searches were conducted in 9 databases(MEDLINE,SPORTDiscus,Embase,Scopus,PsycINFO,Web of Science,PubMed,CINAHL,and the Cochrane Library)up to April 11,2024.We included full-text refereed cohort studies published in English that quantified the association(using risk estimates with 95%confidence intervals(95%CIs))of objectively measured,exercise-estimated,and non-exercise-estimated CRF with all-cause and CVD mortality in adults.CRF was expressed as metabolic equivalents(METs)of task.Pooled relative risks(RR)for all-cause and CVD mortality per 1-MET(3.5 mL/kg/min)higher level of CRF were quantified using random-effects models.Results:Forty-two studies representing 35 cohorts and 3,813,484 observations(81%male)(362,771 all-cause and 56,471 CVD deaths)were included.The pooled RRs for all-cause and CVD mortality per higher MET were 0.86(95%CI:0.83-0.88)and 0.84(95%CI:0.80-0.87),respectively.For both all-cause and CVD mortality,there were no statistically significant differences in RR per higher MET between objectively measured(RR range:0.86-0.90)and maximal exercise-estimated(RR range:0.85-0.86),submaximal exercise-estimated(RR range:0.91-0.94),and non-exercise-estimated CRF(RR range:0.81-0.85).Conclusion:Objectively measured and estimated CRF showed similar dose-response associations for all-cause and CVD mortality in adults.Estimated CRF could provide a practical and robust alternative to objectively measured CRF for assessing mortality risk across diverse populations.Our findings underscore the health-related benefits of higher CRF and advocate for its integration into clinical practice to enhance risk stratification.展开更多
Organisms have evolved a strain limiting mechanism,reflected as a non-linear elastic constitutive,to prevent large deformations from threatening soft tissue integrity.Compared with linear elastic substrates,the wrinkl...Organisms have evolved a strain limiting mechanism,reflected as a non-linear elastic constitutive,to prevent large deformations from threatening soft tissue integrity.Compared with linear elastic substrates,the wrinkle of films on non-linear elastic substrates has received less attention.In this article,a unique wrinkle evolution of the film-substrate system with a J-shaped non-linear stress-strain relation is reported.The result shows that a concave hexagonal array pattern is formed with the shrinkage strain of the film-substrate systems developing.As the interconnection of hexagonal arrays,a unit cell ridge network appears with properties such as chirality and helix.The subparagraph maze pattern formed with high compression is mainly composed of special single-cell ridge networks such as spiral single cores,chiral double cores,and combined multi-cores.This evolutionary model is highly consistent with the results of experiments,and it also predicts wrinkle morphology that has not yet been reported.These findings can serve as a novel explanation for the surface wrinkle of biological soft tissue,as well as provide references for the preparation of artificial biomaterials and programmable soft matter.展开更多
The Internet of Things(IoT)technology offers significant advancements in fitness trackers and AI-driven health management systems and presents practical applications for monitoring health and performance.New energy co...The Internet of Things(IoT)technology offers significant advancements in fitness trackers and AI-driven health management systems and presents practical applications for monitoring health and performance.New energy composites,which improve the performance of traditional metals,have been widely used in automotive manufacturing but have limited application in the sports industry.To bridge this gap,the study proposes integrating these advanced composites into sports equipment and facilities,utilizing IoT technology as the foundation for intelligent health monitoring.The research explores how IoT technology can enhance the promotional impact of fitness equipment within the sports industry.Additionally,the communication process for data assessment is conducted using the Priority-based Congestion-avoidance Routing Protocol(PCRP)to ensure efficient data transmission.The analysis of sports activities is performed by utilizing the data transferred through PCRP.Experimental results show that the proposed mechanism outperforms conventional models,achieving an energy efficiency of 0.502 joules(J),a delay of 0.407 seconds(s),and a throughput of 0.620.These results demonstrate the potential of combining IoT technology and new energy composites to revolutionize sports equipment and enhance fitness monitoring systems.These findings highlight the potential of combining IoT and advanced composite materials to revolutionize sports equipment,improve fitness monitoring,and contribute to the growth of the sports industry through enhanced data management and energy-efficient technologies.展开更多
Background:This study evaluated physical fitness and mental health in young and elderly women 3 months after mild COVID-19 infection,and examined the impact of infection and age on long COVID occurrence and trajectory...Background:This study evaluated physical fitness and mental health in young and elderly women 3 months after mild COVID-19 infection,and examined the impact of infection and age on long COVID occurrence and trajectory.Methods:There were 213 eligible female volunteers(107 young,106 elderly)recruited approximately three months after the significant outbreak of COVID-19 in China.Participants completed a fitness test and mental health assessment using the Post-Traumatic Stress Disorder Self-Assessment Scale(PTSD)and the Pittsburgh Sleep Quality Inventory(PSQI).Results:Despite no significant difference in physical fitness,infected young and elderly females experienced poorer sleep quality related to mental health compared to their uninfected peers(+22%in young participants,p=0.027;+10%in elderly participants,p=0.005).The elderly scored significantly higher in sleep quality than the young(p<0.05).Age,previous infection,and PTSD were significant predictors of sleep quality,explaining 60.6%of the variance in PSQI scores.Conclusions:Three months following COVID-19 infection,infected women experienced poorer sleep quality compared to their uninfected peers.Irrespective of being infected,older individuals exhibited higher rates of sleep disorders compared to younger women,suggesting the importance of addressing postCOVID-19 sleep issues among at-risk individuals.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant 42174164 and Grant 41704132in part by the Key Program of the Joint Fund of the Science,Technology,and Education of Sichuan Province,China under Grant 2024NSFSC1955+4 种基金in part by the Natural Science Foundation of Sichuan Province,China under Grant 2024NSFSC0080in part by the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project under Grant SKLGP2022Z011in part by the Chengdu University of Technology Postgraduate Innovative Cultivation Program:Spatiotemporal Characterization of Seismic Signals for Tight Channel Sandstone Gas Reservoirs in the Synchro-Squeezing/Extracting Transform Domain under Grant CDUT2023BJCx002in part by the Creative Research Groups of the Natural Science Foundation of Sichuan under Grant 2023NSFSC198414th Five Year Plan Major Science and Technology Project of CNOOC under Grant KJGG2022-0903.
文摘As seismic signals propagate underground,the subsurface media absorb high-frequency components,decreasing seismic resolution and limiting the identification and characterization of thin reservoirs.To address the limitation,this paper proposes a multichannel spectral fitting(MSF)method.The MSF method aims to enhance seismic resolution by considering the spectral characteristics and the correlations between adjacent seismic traces.The key to the MSF method involves utilizing the amplitude spectrum of the attenuated Ricker wavelet to construct an objective function for spectral fitting,leading to improved seismic resolution.Furthermore,the MSF method establishes the correlation between adjacent seismic traces as a constraint to stably solve the target parameters based on the entire seismic spectrum,which helps obtain horizontally consistent and more realistic seismic signals.Synthetic and field seismic examples demonstrate that the proposed method not only provides higher-resolution seismic signals but also reveals more fine details of thin reservoirs compared to the time-variant spectral whitening method.It is concluded that the MSF method is a promising tool for seismic signal processing.
基金Fundamental Research Funds for the Central Universities(2023MS134)。
文摘In modern industrial applications,ensuring the reliability of mechanical fittings is critical for maintaining operational safety and efficiency,particularly in power grid systems where split pins serve a pivotal role despite being susceptible to environmental degradation and failure.Existing UAV-based inspection systems are hampered by a low representation of split pin elements and complex backgrounds,leading to challenges in accurate fault detection and timely maintenance.To address this pressing issue,our study proposes an innovative fault detection method for split pins.The approach employs a three-step process:first,cropping operations are used to accurately isolate the fittings containing split pins;second,super-resolution reconstruction is applied to enhance image clarity and detail;and finally,an improved YOLOv8 network,augmented with inner-shape IoU and local window attention mechanisms,is utilized to refine local feature extraction and annotation accuracy.Experimental evaluations on a split pin defect dataset demonstrate robust performance,achieving an accuracy rate of 72.1%and a mean average precision(mAP)of 67.7%,thereby validating the method’s effectiveness under challenging conditions.The proposed approach contributes to the field by specifically targeting the challenges associated with split pin detection in UAV-based inspections,offering a practically applicable and reliably precise method.
基金supported by the National Natural Science Foundation of China(12132015,12332015)。
文摘The ratio of the pressure drop force to the drag force,C_(P),is concerned for a non-closely fitting spherical particle settling along the central line in long rectangular tubes with different A_(r)(A_(r)is W/H,where W,H is length of the longer and shorter side of the rectangle respectively).Under Stokes flow conditions,C_(P0)for an infinitely small sphere in long rectangular tubes and C_(P)for a sphere in a long channel between two parallel layered barriers are both calculated.Then C_(P)of a sphere settling in long rectangular tubes are conducted with the direct-forcing fictitious domain(DF/FD)method.At large Reynolds number,the sphere settles unstably with a fluctuating velocity and C_(P).The fluctuation of Cp is much stronger than that of velocity and both fluctuations are stronger for less confined sphere.The influences of the particle Reynolds number(Re_(p))on C_(P)is similar to the existing experimental results in long circular tubes.At low Re_(p),C_(P)is a determined value and is calculated.For a given d/H(d sphere diameter),Cp gets its maximum value at one A_(r)in the range of[1,1.5].For a given A_(r),C_(P)is a quadratic function of d/H similar to that in a circular tube,and parameters of the quadratic function are got by curve fitting from numerical data.The constant term coefficients got have almost no difference with C_(P0)and are furtherly replaced by the latter to get new quadratic coefficients C_(P1).Lastly,an algebraic correlation of C_(P1)to A_(r)is developed.The predictions of Cp are good with a maximum relative error about 1.5%for a sphere with d/H not greater than0.7,compared to numerical results.
基金supported in part by NSFC under contracts 42225404, 42127803, 42150105by National Key R&D Program of China No. 2021YFA0718600by ISSI-BJ through the international teams Nos. 23-581 and 56。
文摘The energy spectrum of energetic particles in space often shows a non-thermal spectral shape with two spectral transitions/breaks over a wide energy range, carrying crucial information about their acceleration, release and transportation process. To self-consistently characterize the spectral features of energetic particles, here we propose a novel extended pan-spectrum(EPS) formula to fit the particle energy-flux spectrum, which has the merit that can incorporate many commonly used spectrum functions with one spectral transition, including the pan-spectrum, double-power-law, Kappa, Ellison-Ramaty(ER) functions, etc. The formula can also determine the spectral shape with two spectral transitions, including the triple-power-law function, Kappa distribution(at low energy)plus power law(at high energy), power law(at low energy) plus ER function, etc. Considering the uncertainties in both J and E, we can fit this EPS formula well to the representative energy spectra of various particle phenomena in space, including solar energetic particles(electrons, protons, ~3He and heavier ions), anomalous cosmic rays, solar wind suprathermal particles(halo and superhalo electrons;pick-up ions and the suprathermal tail), etc. Therefore, the EPS fitting can help us self-consistently determine the spectral features of different particle phenomena, and improve our understanding of the physical nature of the origin, acceleration, and transportation of energetic particles in space.
基金supported in part by the National Natural Foundation of China(No.62027801).
文摘Recently,researchers have proposed an emitter localization method based on passive synthetic aperture.However,the unknown residual frequency offset(RFO)between the transmit-ter and the receiver causes the received Doppler signal to shift,which affects the localization accu-racy.To solve this issue,this paper proposes a RFO estimation method based on range migration fitting.Due to the high frequency modulation slope of the linear frequency modulation(LFM)-mod-ulation radar signal,it is not affected by RFO in range compression.Therefore,the azimuth time can be estimated by fitting the peak value position of the pulse compression in range direction.Then,the matched filters are designed under different RFOs.When the zero-Doppler time obtained by the matched filters is consistent with the estimated azimuth time,the given RFO is the real RFO between the transceivers.The simulation results show that the estimation error of azimuth distance does not exceed 20 m when the received signal duration is not less than 3 s,the pulse repe-tition frequency(PRF)of the transmitter radar signal is not less than 1 kHz,the range detection is not larger than 1000 km,and the signal noise ratio(SNR)is not less than-5 dB.
基金supported by the Grant PID2020-120249RB-I00PID2023-148404OB-100funded by MCIN/AEI/10.13039/501100011033+4 种基金by the Andalusian Government(Junta de Andalucía,Plan Andaluz de Investigación,ref.P20_00124)by the Erasmus+Sport Programme of the European Union within the project FitBack4Literacy(No.101089829)Additional support is provided by the University of Granada,Plan Propio de Inves-tigación,Units of ExcellenceUnit of Excellence on Exercise,Nutrition and Health(UCEENS)by theCIBERobn Physiopa-thology of Obesity and Nutrition,and by the Spanish Network in Exercise and Health,EXERNET Network(RED2022-134800-Tand EXP_99828).
文摘Background:Physicalfitness in childhood and adolescence is associated with a variety of health outcomes and is a powerful marker of current and future health.However,inconsistencies in tests and protocols limit international monitoring and surveillance.The objective of the study was to seek international consensus on a proposed,evidence-informed,Youth Fitness International Test(YFIT)battery and protocols for health monitoring and surveillance in children and adolescents aged 618 years.Methods:We conducted an international modified Delphi study to evaluate the level of agreement with a proposed,evidence-based,YFIT of core health-relatedfitness tests and protocols to be used worldwide in 6-to 18-year-olds.This proposal was based on previous European and North American projects that systematically reviewed the existing evidence to identify the most valid,reliable,health-related,safe,and feasiblefitness tests to be used in children and adolescents aged 618 years.We designed a single-panel modified Delphi study and invited 216 experts from all around the world to answer this Delphi survey,of whom one-third are from low-to-middle income countries and one-third are women.Four experts were involved in the piloting of the survey and did not participate in the main Delphi study to avoid bias.We pre-defined an agreement of 80%among the expert participants to achieve consensus.Results:We obtained a high response rate(78%)with a total of 169fitness experts from 50 countries and territories,including 63 women and 61 experts from low-or middle-income countries/territories.Consensus(>85%agreement)was achieved for all proposed tests and protocols,supporting the YFIT battery,which includes weight and height(to compute body mass index as a proxy of body size/composition),the 20-m shuttle run(cardiorespiratoryfitness),handgrip strength,and standing long jump(muscularfitness).Conclusion:This study contributes to standardizingfitness tests and protocols used for research,monitoring,and surveillance across the world,which will allow for future data pooling and the development of international and regional sex-and age-specific reference values,health-related cut-points,and a global picture offitness among children and adolescents.
基金Liaoning Provincial Social Science Planning Fund Office(2019)(L19BGL034).
文摘Objective To study the increasing use of sports and fitness APPs against the background of national fitness and post-epidemic era,and to provide some suggestions for the development of sports and fitness APPs.Methods Literature survey and mathematical statistics were used to define the concept of sports and fitness APPs,and their characteristics and advantages were investigated.Then,their problems were pointed out.Results and Conclusion The existing problems include some APPs favoring female users,single function,and slightly backward profit model.Some countermeasures such as enriching course types,taking into account all categories of users,expanding more functions,improving service quality,broadening profit channels,and improving marketing level are put forward.This can provide theoretical basis for the operation of sports and fitness APPs and better popularize the culture of national fitness.
文摘BACKGROUND The prevalence of metabolic syndrome(MetS)in adolescents is rising,correlating with the global increase in obesity and physical inactivity.AIM To examine the individual and combined associations of fitness,fatness,visceral adiposity index(VAI),and lipid ratios with MetS risk in Nigerian adolescents.METHODS This cross-sectional study included a sample of 403 adolescents(201 girls and 202 boys)aged 11-19 years.Participants were assessed for cardiorespiratory fitness,body mass index(BMI),VAI,triglyceride-to-high-density lipoprotein cholesterol ratio(TG/HDL-C),and total cholesterol-to-high-density lipoprotein cholesterol ratio(TC/HDL-C).Regression models adjusted for age and sexual maturity were used to determine the associations between these health markers and MetS risk.RESULTS Among the 177 high-risk adolescents,56.6%were at risk of central obesity,49.1%had low fitness,33.3%had dyslipidemia,and 11.7%were obese.After controlling for confounding variables,all health markers were independently and jointly associated with MetS risk,with VAI displaying the strongest explanatory power(girls:β=1.308,P<0.001;boys:β=2.300,P<0.001).Unfit girls were 5.1%more likely to be at risk of MetS,while the odds of unfit boys being at risk of MetS is 3.6.Boys with elevated VAI were 22.3 times more likely to be at risk of MetS,while the likelihood of girls with elevated VAI developing MetS risk is 2.78.CONCLUSION Health markers were independently and jointly associated with MetS risk in adolescents,with VAI and dyslip-idemia contributing most significantly.Promoting healthy eating and also aerobic activities among adolescents is crucial for improving metabolic health.
文摘This opinion article discusses the original research work of Yünkül et al.(the Authors)published in the Journal of Mountain Science 21(9):3108–3122.Employing non-linear regression,fuzzy logic and artificial neural network modeling techniques,the Authors interrogated a large database assembled from the existing research literature to assess the performance of twelve equation rules in predicting the undrained shear strength(s_(u))mobilized for remolded fine-grained soils at different values of liquidity index(I_(L))and water content ratio.Based on their analyses,the Authors proposed a simple and reportedly reliable correlation(i.e.,Eq.9 in their paper)for predicting s_(u) over the I_(L) range of 0.15 to 3.00.This article describes various shortcomings in the Authors’assembled database(including potentially anomalous data and covering an excessively wide I_(L) range in relation to routine geotechnical and transportation engineering applications)and their proposed s_(u)=f(I_(L))correlation.Contrary to the Authors’assertions,their proposed correlation is not reliable for fine-grained soils with consistencies in the general firm to stiff range(i.e.,for 0.15<I_(L)<0.40),increasingly overestimating s_(u) for reducing I_(L),and eventually predicting s_(u)→+∞for I_(L)→0.15+(while producing mathematically undefined s_(u) for I_(L)<0.15),thus rendering their correlation unconservative and potentially leading to unsafe geotechnical designs.Exponential or regular-power type s_(u)=f(I_(L))models are more s_(u)itable when developing correlations that are applicable over the full plastic range(of 0<I_(L)<1),thereby providing reasonably conservative s_(u) predictions for use in the preliminary design for routine geotechnical engineering applications.
文摘Measuring cardiorespiratory fitness(CRF)is an important predictor of morbidity and mortality in epidemiological studies and clinical settings.1 However,the feasibility of measuring maximal CRF is low due to the time,equipment,and expertise needed to conduct laboratory cardiopulmonary exercise testing(CPET)to determine the maximal rate of oxygen uptake(VO2max)as an objective measure of CRF.Alternatively,indirect estimates of CRF have been applied by measuring maximal duration on treadmill or cycle ergometer tests,2,3 extrapolating maximal CRF from workload or heart rate during submaximal fitness tests,4,5 and using non-exercise algorithms to estimate CRF from an individual’s age,sex,body mass,and physical activity habits.6 It is assumed that objectively measured VO2max is superior to extrapolated and estimated values due to errors associated with the estimated values;7,8 however,until Singh et al.9 newly released article in the Journal of Sport and Health Science,the comparability of these methods in identifying risks for all-cause and cardiovascular disease(CVD)mortality was unknown.
基金Supported by National Natural Science Foundation of China(Grant No.11872033)Beijing Municipal Natural Science Foundation(Grant No.3172017)。
文摘Many experiments have supported the contact models,such as the GW and MB models,but the majority of previous validations have been performed under light loads,resulting in a linear relationship between normal force and contact area.However,the real contact area fraction should never equal one;there must be a limit smaller than the apparent area,implying that the real contact area cannot increase linearly indefinitely.In this paper,the real contact area between two polymethylmethacrylate(PMMA)blocks under heavy load is measured using the total reflection method,and the contact area is analyzed using the image processing method.The results show that the real contact area increases with normal load linearly in light loads but non-linearly in heavy loads;the number of contact spots increases with load linearly in light loads but also non-linearly in heavy loads,synchronous with the change in the real contact area.The GW,MB,and Zhao,Maietta,and Chang(ZMC)models were used to predict the experiment results,but none of them predicted the non-linear stage.A revised GW model based on the bulk deformation hypothesis performs better in predicting the non-linear stage.The study’s findings can be applied to PMMA or other similar materials,and they can serve as a useful reference for future research on the contact mechanisms of other materials.
基金supported by a grant from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska Curie(Grant agreement No.101028929)supported by an Investigator Grant from the Medical Research Future Fund(MRF1193862)supported by an Australian Government Research Training Program Scholarship.
文摘Background:Cardiorespiratory fitness(CRF)is a powerful health marker recommended by the American Heart Association as a clinical vital sign.Comparing the predictive validity of objectively measured CRF(the"gold standara")and estimated CRF is clinically relevant because estimated CRF is more feasible.Our objective was to meta-analyze cohort studies to compare the associations of objectively measured,exerciseestimated,and non-exercise-estimated CRF with all-cause and cardiovascular disease(CVD)mortality in adults.Methods:Systematic searches were conducted in 9 databases(MEDLINE,SPORTDiscus,Embase,Scopus,PsycINFO,Web of Science,PubMed,CINAHL,and the Cochrane Library)up to April 11,2024.We included full-text refereed cohort studies published in English that quantified the association(using risk estimates with 95%confidence intervals(95%CIs))of objectively measured,exercise-estimated,and non-exercise-estimated CRF with all-cause and CVD mortality in adults.CRF was expressed as metabolic equivalents(METs)of task.Pooled relative risks(RR)for all-cause and CVD mortality per 1-MET(3.5 mL/kg/min)higher level of CRF were quantified using random-effects models.Results:Forty-two studies representing 35 cohorts and 3,813,484 observations(81%male)(362,771 all-cause and 56,471 CVD deaths)were included.The pooled RRs for all-cause and CVD mortality per higher MET were 0.86(95%CI:0.83-0.88)and 0.84(95%CI:0.80-0.87),respectively.For both all-cause and CVD mortality,there were no statistically significant differences in RR per higher MET between objectively measured(RR range:0.86-0.90)and maximal exercise-estimated(RR range:0.85-0.86),submaximal exercise-estimated(RR range:0.91-0.94),and non-exercise-estimated CRF(RR range:0.81-0.85).Conclusion:Objectively measured and estimated CRF showed similar dose-response associations for all-cause and CVD mortality in adults.Estimated CRF could provide a practical and robust alternative to objectively measured CRF for assessing mortality risk across diverse populations.Our findings underscore the health-related benefits of higher CRF and advocate for its integration into clinical practice to enhance risk stratification.
基金This work was supported by the Youth Project of Hunan Provincial Department of Education(Grant No.22B0334)the Bridge and Tunnel Engineering Innovation Project of Changsha University of Science&Technology(Grant No.11ZDXK11)and the Practical Innovation and Entrepreneurship Capacity Improvement Plan of Changsha University of Science and Technology(Grant No.CLSJCX23029).
文摘Organisms have evolved a strain limiting mechanism,reflected as a non-linear elastic constitutive,to prevent large deformations from threatening soft tissue integrity.Compared with linear elastic substrates,the wrinkle of films on non-linear elastic substrates has received less attention.In this article,a unique wrinkle evolution of the film-substrate system with a J-shaped non-linear stress-strain relation is reported.The result shows that a concave hexagonal array pattern is formed with the shrinkage strain of the film-substrate systems developing.As the interconnection of hexagonal arrays,a unit cell ridge network appears with properties such as chirality and helix.The subparagraph maze pattern formed with high compression is mainly composed of special single-cell ridge networks such as spiral single cores,chiral double cores,and combined multi-cores.This evolutionary model is highly consistent with the results of experiments,and it also predicts wrinkle morphology that has not yet been reported.These findings can serve as a novel explanation for the surface wrinkle of biological soft tissue,as well as provide references for the preparation of artificial biomaterials and programmable soft matter.
基金supported by the Scientific Research and Innovation Team of Xi’an Eurasia University’Urban Sports Intellectualization Research Team’grant number[2021XJTD08]the Shaanxi Province Sports Bureau Research Project’Research on the Integration of the Whole Industry Chain of Sports Industry’grant number[2023317].
文摘The Internet of Things(IoT)technology offers significant advancements in fitness trackers and AI-driven health management systems and presents practical applications for monitoring health and performance.New energy composites,which improve the performance of traditional metals,have been widely used in automotive manufacturing but have limited application in the sports industry.To bridge this gap,the study proposes integrating these advanced composites into sports equipment and facilities,utilizing IoT technology as the foundation for intelligent health monitoring.The research explores how IoT technology can enhance the promotional impact of fitness equipment within the sports industry.Additionally,the communication process for data assessment is conducted using the Priority-based Congestion-avoidance Routing Protocol(PCRP)to ensure efficient data transmission.The analysis of sports activities is performed by utilizing the data transferred through PCRP.Experimental results show that the proposed mechanism outperforms conventional models,achieving an energy efficiency of 0.502 joules(J),a delay of 0.407 seconds(s),and a throughput of 0.620.These results demonstrate the potential of combining IoT technology and new energy composites to revolutionize sports equipment and enhance fitness monitoring systems.These findings highlight the potential of combining IoT and advanced composite materials to revolutionize sports equipment,improve fitness monitoring,and contribute to the growth of the sports industry through enhanced data management and energy-efficient technologies.
文摘Background:This study evaluated physical fitness and mental health in young and elderly women 3 months after mild COVID-19 infection,and examined the impact of infection and age on long COVID occurrence and trajectory.Methods:There were 213 eligible female volunteers(107 young,106 elderly)recruited approximately three months after the significant outbreak of COVID-19 in China.Participants completed a fitness test and mental health assessment using the Post-Traumatic Stress Disorder Self-Assessment Scale(PTSD)and the Pittsburgh Sleep Quality Inventory(PSQI).Results:Despite no significant difference in physical fitness,infected young and elderly females experienced poorer sleep quality related to mental health compared to their uninfected peers(+22%in young participants,p=0.027;+10%in elderly participants,p=0.005).The elderly scored significantly higher in sleep quality than the young(p<0.05).Age,previous infection,and PTSD were significant predictors of sleep quality,explaining 60.6%of the variance in PSQI scores.Conclusions:Three months following COVID-19 infection,infected women experienced poorer sleep quality compared to their uninfected peers.Irrespective of being infected,older individuals exhibited higher rates of sleep disorders compared to younger women,suggesting the importance of addressing postCOVID-19 sleep issues among at-risk individuals.
