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
Metal droplet deposition is a kind of additive manufacturing(3D Printing)technique that fabricates near-net part through droplets deposition with lower cost and higher efficiency.This paper proposed a solution to prob...Metal droplet deposition is a kind of additive manufacturing(3D Printing)technique that fabricates near-net part through droplets deposition with lower cost and higher efficiency.This paper proposed a solution to problems of electric power fittings that large inventories,high procurement costs,low manufacturing efficiency and transportation cost.Using additive Manufacturing technique-metal droplet deposition,electric power fittings fabricated on power construction site.This paper describes the manufacturing process of typical thin-walled samples(the structure optimized based on additive manufacturing principle)and ball head rings of electric power fittings.Aiming at the integral AM forming for ball and ball socket electric power fitting workpiece,a novel easy removal forming support material(ceramics and gypsum mixed with UV cured resin)have been developed.Here this support material was used to fabricate nested integral workpieces.Dimensional accuracy and microstructure of the test pieces were analyzed.The error of the height and width of the forming workpiece is within 5%.No obvious overlap trace(such as overlap line and cracks)observed,and the internal microstructure is equiaxial crystal.The average density of the component is 99.51%,which measured by drainage method and 13.39%higher than the cast raw material.展开更多
Flexible pipes function effectively in practical applications only when they are securely connected to specific components using specially designed end fittings.These end fittings must be precisely manufactured to ens...Flexible pipes function effectively in practical applications only when they are securely connected to specific components using specially designed end fittings.These end fittings must be precisely manufactured to ensure a tight connection,preventing any potential leakage.Otherwise,even perfectly manufactured flexible pipes will fail to perform their intended function.Although extensive research exists on the mechanical analysis of flexible pipes,studies on pipes connected to end fittings are scarce.The primary challenge in investigating this combined structure lies in the complex interaction between flexible pipes and end fittings after assembly,in addition to the already intricate structural behavior of flexible pipes.This paper presents both experimental and numerical analyses.Experimentally,we conducted comprehensive torsion tests on steel strip reinforced flexible pipes connected to commonly used end fittings,observing various torsional failure modes.On the numerical side,we developed a method to model the interaction between flexible pipes and end fittings.The proposed approach enables the prediction of torsional failure modes in practical applications and lays the groundwork for further failure analysis under different loading conditions and for various end fitting designs.展开更多
Nonbonded flexible pipes consist of polymer materials that experience stress relaxation at high temperatures,which ultimately affects the sealing performance of end sealing systems.To assess stress relaxation curves u...Nonbonded flexible pipes consist of polymer materials that experience stress relaxation at high temperatures,which ultimately affects the sealing performance of end sealing systems.To assess stress relaxation curves under varying temperatures and pre-strains,this paper conducts both tensile and stress relaxation tests on PVDF materials.To describe the stress relaxation characteristics of these materials,the Prony series is utilized.In order to identify the parameters of the series,the paper employs the Levenberg-Marquardt method of nonlinear regression.A finite element model is established to verify the accuracy of the parameter identification method.Subsequently,the paper establishes a two-dimensional axisymmetric finite element model of the sealing system in the end fitting,while taking into account fluid pressure inside the pipeline using a pressure penetration method.The impact of stress relaxation on the sealing performance is then discussed.Finally,the paper alters the coefficients of the Prony series to explore their significance on the sealing performance of the sealing system.展开更多
Gauss radial basis functions(GRBF)are frequently employed in data fitting and machine learning.Their linear independence property can theoretically guarantee the avoidance of data redundancy.In this paper,one of the m...Gauss radial basis functions(GRBF)are frequently employed in data fitting and machine learning.Their linear independence property can theoretically guarantee the avoidance of data redundancy.In this paper,one of the main contributions is proving this property using linear algebra instead of profound knowledge.This makes it easy to read and understand this fundamental fact.The proof of linear independence of a set of Gauss functions relies on the constructing method for one-dimensional space and on the deducing method for higher dimensions.Additionally,under the condition of preserving the same moments between the original function and interpolating function,both the interpolating existence and uniqueness are proven for GRBF in one-dimensional space.The final work demonstrates the application of the GRBF method to locate lunar olivine.By combining preprocessed data using GRBF with the removing envelope curve method,a program is created to find the position of lunar olivine based on spectrum data,and the numerical experiment shows that it is an effective scheme.展开更多
The search for mechanical properties of materials reached a highly acclaimed level, when indentations could be analysed on the basis of elastic theory for hardness and elastic modulus. The mathematical formulas proved...The search for mechanical properties of materials reached a highly acclaimed level, when indentations could be analysed on the basis of elastic theory for hardness and elastic modulus. The mathematical formulas proved to be very complicated, and various trials were published between the 1900s and 2000s. The development of indentation instruments and the wish to make the application in numerous steps easier, led in 1992 to trials with iterations by using relative values instead of absolute ones. Excessive iterations of computers with 3 + 8 free parameters of the loading and unloading curves became possible and were implemented into the instruments and worldwide standards. The physical formula for hardness was defined as force over area. For the conical, pyramidal, and spherical indenters, one simply took the projected area for the calculation of the indentation depth from the projected area, adjusted it later by the iterations with respect to fused quartz or aluminium as standard materials, and called it “contact height”. Continuously measured indentation loading curves were formulated as loading force over depth square. The unloading curves after release of the indenter used the initial steepness of the pressure relief for the calculation of what was (and is) incorrectly called “Young’s modulus”. But it is not unidirectional. And for the spherical indentations’ loading curve, they defined the indentation force over depth raised to 3/2 (but without R/h correction). They till now (2025) violate the energy law, because they use all applied force for the indenter depth and ignore the obvious sidewise force upon indentation (cf. e.g. the wood cleaving). The various refinements led to more and more complicated formulas that could not be reasonably calculated with them. One decided to use 3 + 8 free-parameter iterations for fitting to the (poor) standards of fused quartz or aluminium. The mechanical values of these were considered to be “true”. This is till now the worldwide standard of DIN-ISO-ASTM-14577, avoiding overcomplicated formulas with their complexity. Some of these are shown in the Introduction Section. By doing so, one avoided the understanding of indentation results on a physical basis. However, we open a simple way to obtain absolute values (though still on the blackbox instrument’s unsuitable force calibration). We do not iterate but calculate algebraically on the basis of the correct, physically deduced exponent of the loading force parabolas with h3/2 instead of false “h2” (for the spherical indentation, there is a calotte-radius over depth correction), and we reveal the physical errors taken up in the official worldwide “14577-Standard”. Importantly, we reveal the hitherto fully overlooked phase transitions under load that are not detectable with the false exponent. Phase-transition twinning is even present and falsifies the iteration standards. Instead of elasticity theory, we use the well-defined geometry of these indentations. By doing so, we reach simple algebraically calculable formulas and find the physical indentation hardness of materials with their onset depth, onset force and energy, as well as their phase-transition energy (temperature dependent also its activation energy). The most important phase transitions are our absolute algebraically calculated results. The now most easily obtained phase transitions under load are very dangerous because they produce polymorph interfaces between the changed and the unchanged material. It was found and published by high-enlargement microscopy (5000-fold) that these trouble spots are the sites for the development of stable, 1 to 2 µm long, micro-cracks (stable for months). If however, a force higher than the one of their formation occurs to them, these grow to catastrophic crash. That works equally with turbulences at the pickle fork of airliners. After the publication of these facts and after three fatal crashing had occurred in a short sequence, FAA (Federal Aviation Agency) reacted by rechecking all airplanes for such micro cracks. These were now found in a new fleet of airliners from where the three crashed ones came. These were previously overlooked. FAA became aware of that risk and grounded 290 (certainly all) of them, because the material of these did not have higher phase-transition onset and energy than other airplanes with better material. They did so despite the 14577-Standard that does not find (and thus formally forbids) phase transitions under indenter load with the false exponent on the indentation parabola. However, this “Standard” will, despite the present author’s well-founded petition, not be corrected for the next 5 years.展开更多
Energy expenditure estimation can be used to measure the exercise load and physical condition of different individuals, such as soldiers, athletes, firemen, etc., during their training and work. Energy expenditure est...Energy expenditure estimation can be used to measure the exercise load and physical condition of different individuals, such as soldiers, athletes, firemen, etc., during their training and work. Energy expenditure estimation methods based on computer vision have rapidly developed in recent years. Compared with sensor-based methods, such methods are capable of monitoring several target persons at the same time, and the subjects do not need to wear different sensor devices that hamper their movement. In this paper, we propose a cross-attention spatial–temporal convolutional neural network to predict the energy expenditure of people under different exercise intensities. The model explores the relationship between changes in the human skeleton and energy expenditure intensity. In addition, a cross-attention correction module is used to reduce the negative effects of individual physical fitness characteristics during energy expenditure estimation. The experimental results show that our proposed method achieves high accuracy for energy expenditure estimation and performs better than existing computer vision-based energy expenditure estimation methods do. The proposed method can be widely used in various physical activity scenarios to measure energy expenditure, increasing the convenience of usage.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
Objectives:Cardiorespiratory fitness(CRF)and skeletal muscle mass(SMM)are both key parameters of intrinsic capacity.To date,the impact of adherence to physical activity guidelines by older adults on these facets is po...Objectives:Cardiorespiratory fitness(CRF)and skeletal muscle mass(SMM)are both key parameters of intrinsic capacity.To date,the impact of adherence to physical activity guidelines by older adults on these facets is poorly understood.Therefore,this study aimed to assess the impact of 4 weeks adherence to UK physical activity guidelines on parameters of intrinsic capacity in older adults,with a secondary aim to determine the utility of a bedside-suitable predictive model of assessing CRF for predicting change in this parameter.Methods:14 older adults(22%female,age:66–80 years)completed a 4-week intervention in which they adhered to UK physical activity guidelines via a combination of supervised and home-based exercise.In addition to assessments of CRF via cardiopulmonary exercise testing and SMM via ultrasonography,whole-body and handgrip strength(HGS)and step-box test(SBT)variables were also measured before and after the intervention.Results:Our intervention resulted in significant increases in CRF(ventilatory threshold(VT):+2.7±0.9 mL/kg/min,p<0.01),vastus lateralis muscle thickness(+9%,p=0.02)and whole body strength(+47%,p<0.01).There was no change in HGS or SBT performance.The bedside-suitable predictive model of CRF was not able to determine change(R^(2)=0.11,p=0.25).Conclusions:Adherence to UK physical activity guidelines for just 4 weeks improves the CRF,SMM and whole-body strength of community-dwelling older adults.Collectively,these findings illustrate that adherence to current guidelines can improve key aspects of intrinsic capacity in older individuals.The impact of such interventions in populations at risk of accelerated physiological decline,warrant further investigation.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
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
Blooms of the toxic dinoflagellate Alexandrium spp.,which produce paralytic shellfish toxins(PSTs),have threatened marine ecosystems for decades.However,their impacts on benthic copepods remain underexplored.Here,we i...Blooms of the toxic dinoflagellate Alexandrium spp.,which produce paralytic shellfish toxins(PSTs),have threatened marine ecosystems for decades.However,their impacts on benthic copepods remain underexplored.Here,we investigated the physiological and biochemical responses of marine benthic copepod Tigriopus japonicus to Alexandrium pacificum.Adult female showed no mortality within 24 h and maintained high survival(>80%)across all A.pacificum concentrations over 96 h,with no significant difference from non-toxic controls.Ingestion rates on A.pacificum and non-toxic controls were similar,when algal prey concentrations were lower than about 2500µgC/L.However,above this threshold,feeding of T.japonicus was significantly depressed by A.pacificum.Six-day exposure induced oxidative stress,marked by elevated level of reactive oxygen species,malondialdehyde,total antioxidant capacity and superoxide dismutase activity,while catalase activity showed a non-significant increase.Moreover,concentration-dependent increase was observed in acetylcholinesterase activity,and its positive correlation with oxidative biomarkers suggests additional roles in coping with stress.Chronic exposure over three generations did not consistently affect development,except for complete development failure in F2 and F3 at the highest concentration.However,moderate-to-high concentrations of A.pacificum significantly impaired reproduction,reducing egg production by 9.66%–96.07%and clutch numbers by 33.33%–55.56%.Our findings indicate that Alexandrium blooms can adversely impact benthic copepod feeding and population recruitment through neurotoxicity and oxidative stress,highlighting the ecological risks of prolonged algal blooms in benthic habitats.展开更多
Oil tanks are essential components of the oil industry, facilitating the safe storage and transportation of crude oil. Safely managing oil tanks is a crucial aspect of environmental protection. Oil tanks are often use...Oil tanks are essential components of the oil industry, facilitating the safe storage and transportation of crude oil. Safely managing oil tanks is a crucial aspect of environmental protection. Oil tanks are often used under extreme operational conditions, including dynamic loads, temperature variations, etc., which may result in unpredictable deformations that can cause severe damage or tank collapses. Therefore, it is essential to establish a monitoring system to prevent and predict potential deformations. Terrestrial laser scanning (TLS) has played a significant role in oil tank monitoring over the past decades. However, the full extent of TLS capabilities for oil tank monitoring has not yet been thoroughly investigated. This study aims to evaluate TLS’s abilities in detecting deformations of oil tanks under various operating conditions. The paper has two objectives: first, to examine the deformations of two vertical oil tanks over six years, and second, to investigate potential deformations of the tanks’ surfaces during filling. Each tank was scanned three times—in the years 2015, 2016, and 2021. Mathematical models and appropriate software were developed to determine the achievable accuracy of TLS monitoring. The anticipated monitoring accuracy was simulated based on the design parameters of the oil tanks. This accuracy was subsequently used to differentiate between deformations and measurement errors. The tank surface was approximated utilizing the cylinder equation for each monitoring epoch. Additionally, deformations were analyzed at different cross-sections with the appropriate circular approximations. The results indicated that both tanks exhibited no significant deformations within a range of less than 20 mm. For the empty tanks, the average radius decreased by 4 mm, without any changes in shape. The total spatial inclination of the oil tanks was calculated using cylinder equations at different monitoring epochs. In the final stage, the observed deformations were employed to simulate the strain-stress conditions of the oil tanks. Thus, this paper presents a complex technology and the results of oil tank monitoring by TLS under various operating conditions.展开更多
Mounting evidence suggests that male sperm may be gradually depleted after consecutive matings,resulting in the decline of female reproductive output in insect species.It is predicted that females may employ adaptive ...Mounting evidence suggests that male sperm may be gradually depleted after consecutive matings,resulting in the decline of female reproductive output in insect species.It is predicted that females may employ adaptive strategies to avoid the sperm-depleted males,such as mating multiply with different males and/or discriminating against previously mated males(MMs).Similarly,males may exhibit adaptive behaviors toward females varying in mating status.However,in spiders with males lacking primary copulatory organs and their pedipalps modified to transfer sperm,there are few studies on male mating potential and previous mating experience on their subsequent mate choice.In this study,we used a polyandrous crab spider,Ebrechtella tricuspidata,a sit-and-wait predator with female-biased sex ratio as a model system to ascertain whether 1)male mating experiences influence female reproductive fitness;2)females respond differently to males varying in mating status;and 3)males respond differently to females varying in mating status.Our results showed that female fecundity was independent of male mating experiences,but female fertility markedly declined with the increase of male previous mating experiences in the first eggsac.Counter to our predictions,females preferred to choose and mate with the larger males,regardless of their mating status.In contrast,male mating status influenced their mating preference toward females.Virgin males did not show any preference between virgin and mated females;however,MMs were more likely to prefer the virgin females over the mated ones.Overall,our results indicated that female choice depended primarily on male relative size rather than male mating status,whereas male choice depended on female mating status,Depending on the investigation of reproductive dynamics and mate choice in E.tricuspidata,the study will provide valuable insights into the adaptive behaviors of both males and females exhibiting toward mates varying inmating status.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
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
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This research was funded by National Natural Science Foundation of China under grant number 51575313 and 51775420.This paper got help from Du Jun and Wang Xin of Xi’an Jiaotong University.
文摘Metal droplet deposition is a kind of additive manufacturing(3D Printing)technique that fabricates near-net part through droplets deposition with lower cost and higher efficiency.This paper proposed a solution to problems of electric power fittings that large inventories,high procurement costs,low manufacturing efficiency and transportation cost.Using additive Manufacturing technique-metal droplet deposition,electric power fittings fabricated on power construction site.This paper describes the manufacturing process of typical thin-walled samples(the structure optimized based on additive manufacturing principle)and ball head rings of electric power fittings.Aiming at the integral AM forming for ball and ball socket electric power fitting workpiece,a novel easy removal forming support material(ceramics and gypsum mixed with UV cured resin)have been developed.Here this support material was used to fabricate nested integral workpieces.Dimensional accuracy and microstructure of the test pieces were analyzed.The error of the height and width of the forming workpiece is within 5%.No obvious overlap trace(such as overlap line and cracks)observed,and the internal microstructure is equiaxial crystal.The average density of the component is 99.51%,which measured by drainage method and 13.39%higher than the cast raw material.
文摘Flexible pipes function effectively in practical applications only when they are securely connected to specific components using specially designed end fittings.These end fittings must be precisely manufactured to ensure a tight connection,preventing any potential leakage.Otherwise,even perfectly manufactured flexible pipes will fail to perform their intended function.Although extensive research exists on the mechanical analysis of flexible pipes,studies on pipes connected to end fittings are scarce.The primary challenge in investigating this combined structure lies in the complex interaction between flexible pipes and end fittings after assembly,in addition to the already intricate structural behavior of flexible pipes.This paper presents both experimental and numerical analyses.Experimentally,we conducted comprehensive torsion tests on steel strip reinforced flexible pipes connected to commonly used end fittings,observing various torsional failure modes.On the numerical side,we developed a method to model the interaction between flexible pipes and end fittings.The proposed approach enables the prediction of torsional failure modes in practical applications and lays the groundwork for further failure analysis under different loading conditions and for various end fitting designs.
基金the National Natural Science Foundation of China[Grant No.52088102,52001208,52111530135]Joint Funds of the National Natural Science Foundation of China[Grant No.U19B2013]+2 种基金Young Elite Scientists Sponsorship Program by CAST[Grant No.2020QNRC001]Chenguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission[Grant No.21CGA15,19CG10]Natural Science Foundation of Shanghai[Grant No.21ZR1434500,22ZR1434100].
文摘Nonbonded flexible pipes consist of polymer materials that experience stress relaxation at high temperatures,which ultimately affects the sealing performance of end sealing systems.To assess stress relaxation curves under varying temperatures and pre-strains,this paper conducts both tensile and stress relaxation tests on PVDF materials.To describe the stress relaxation characteristics of these materials,the Prony series is utilized.In order to identify the parameters of the series,the paper employs the Levenberg-Marquardt method of nonlinear regression.A finite element model is established to verify the accuracy of the parameter identification method.Subsequently,the paper establishes a two-dimensional axisymmetric finite element model of the sealing system in the end fitting,while taking into account fluid pressure inside the pipeline using a pressure penetration method.The impact of stress relaxation on the sealing performance is then discussed.Finally,the paper alters the coefficients of the Prony series to explore their significance on the sealing performance of the sealing system.
基金Supported by the National Basic Research Program of China(2012CB025904)Zhengzhou Shengda University of Economics,Business and Management(SD-YB2025085)。
文摘Gauss radial basis functions(GRBF)are frequently employed in data fitting and machine learning.Their linear independence property can theoretically guarantee the avoidance of data redundancy.In this paper,one of the main contributions is proving this property using linear algebra instead of profound knowledge.This makes it easy to read and understand this fundamental fact.The proof of linear independence of a set of Gauss functions relies on the constructing method for one-dimensional space and on the deducing method for higher dimensions.Additionally,under the condition of preserving the same moments between the original function and interpolating function,both the interpolating existence and uniqueness are proven for GRBF in one-dimensional space.The final work demonstrates the application of the GRBF method to locate lunar olivine.By combining preprocessed data using GRBF with the removing envelope curve method,a program is created to find the position of lunar olivine based on spectrum data,and the numerical experiment shows that it is an effective scheme.
文摘The search for mechanical properties of materials reached a highly acclaimed level, when indentations could be analysed on the basis of elastic theory for hardness and elastic modulus. The mathematical formulas proved to be very complicated, and various trials were published between the 1900s and 2000s. The development of indentation instruments and the wish to make the application in numerous steps easier, led in 1992 to trials with iterations by using relative values instead of absolute ones. Excessive iterations of computers with 3 + 8 free parameters of the loading and unloading curves became possible and were implemented into the instruments and worldwide standards. The physical formula for hardness was defined as force over area. For the conical, pyramidal, and spherical indenters, one simply took the projected area for the calculation of the indentation depth from the projected area, adjusted it later by the iterations with respect to fused quartz or aluminium as standard materials, and called it “contact height”. Continuously measured indentation loading curves were formulated as loading force over depth square. The unloading curves after release of the indenter used the initial steepness of the pressure relief for the calculation of what was (and is) incorrectly called “Young’s modulus”. But it is not unidirectional. And for the spherical indentations’ loading curve, they defined the indentation force over depth raised to 3/2 (but without R/h correction). They till now (2025) violate the energy law, because they use all applied force for the indenter depth and ignore the obvious sidewise force upon indentation (cf. e.g. the wood cleaving). The various refinements led to more and more complicated formulas that could not be reasonably calculated with them. One decided to use 3 + 8 free-parameter iterations for fitting to the (poor) standards of fused quartz or aluminium. The mechanical values of these were considered to be “true”. This is till now the worldwide standard of DIN-ISO-ASTM-14577, avoiding overcomplicated formulas with their complexity. Some of these are shown in the Introduction Section. By doing so, one avoided the understanding of indentation results on a physical basis. However, we open a simple way to obtain absolute values (though still on the blackbox instrument’s unsuitable force calibration). We do not iterate but calculate algebraically on the basis of the correct, physically deduced exponent of the loading force parabolas with h3/2 instead of false “h2” (for the spherical indentation, there is a calotte-radius over depth correction), and we reveal the physical errors taken up in the official worldwide “14577-Standard”. Importantly, we reveal the hitherto fully overlooked phase transitions under load that are not detectable with the false exponent. Phase-transition twinning is even present and falsifies the iteration standards. Instead of elasticity theory, we use the well-defined geometry of these indentations. By doing so, we reach simple algebraically calculable formulas and find the physical indentation hardness of materials with their onset depth, onset force and energy, as well as their phase-transition energy (temperature dependent also its activation energy). The most important phase transitions are our absolute algebraically calculated results. The now most easily obtained phase transitions under load are very dangerous because they produce polymorph interfaces between the changed and the unchanged material. It was found and published by high-enlargement microscopy (5000-fold) that these trouble spots are the sites for the development of stable, 1 to 2 µm long, micro-cracks (stable for months). If however, a force higher than the one of their formation occurs to them, these grow to catastrophic crash. That works equally with turbulences at the pickle fork of airliners. After the publication of these facts and after three fatal crashing had occurred in a short sequence, FAA (Federal Aviation Agency) reacted by rechecking all airplanes for such micro cracks. These were now found in a new fleet of airliners from where the three crashed ones came. These were previously overlooked. FAA became aware of that risk and grounded 290 (certainly all) of them, because the material of these did not have higher phase-transition onset and energy than other airplanes with better material. They did so despite the 14577-Standard that does not find (and thus formally forbids) phase transitions under indenter load with the false exponent on the indentation parabola. However, this “Standard” will, despite the present author’s well-founded petition, not be corrected for the next 5 years.
基金supported by the National Key Research and Development Program of China (Grant No.2022YFC3600403)Emerging Interdisciplinary Platform for Medicine and Engineering in Sports (EIPMES),Beijing,China。
文摘Energy expenditure estimation can be used to measure the exercise load and physical condition of different individuals, such as soldiers, athletes, firemen, etc., during their training and work. Energy expenditure estimation methods based on computer vision have rapidly developed in recent years. Compared with sensor-based methods, such methods are capable of monitoring several target persons at the same time, and the subjects do not need to wear different sensor devices that hamper their movement. In this paper, we propose a cross-attention spatial–temporal convolutional neural network to predict the energy expenditure of people under different exercise intensities. The model explores the relationship between changes in the human skeleton and energy expenditure intensity. In addition, a cross-attention correction module is used to reduce the negative effects of individual physical fitness characteristics during energy expenditure estimation. The experimental results show that our proposed method achieves high accuracy for energy expenditure estimation and performs better than existing computer vision-based energy expenditure estimation methods do. The proposed method can be widely used in various physical activity scenarios to measure energy expenditure, increasing the convenience of usage.
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funded through a Biotechnology and Biosciences Research Council(BBSRC)grant awarded to BE Phillips(BB/R010358/1)a Medical Research Council(MRC),United Kingdom grant awarded to BE Phillips(MR/X005240/1)+1 种基金through the MRC(grant no.MR/P021220/1)as part of the MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research awarded to the Universities of Nottingham and Birminghamsupported by the National Institute for Health Research,United Kingdom,Nottingham Biomedical Research Centre。
文摘Objectives:Cardiorespiratory fitness(CRF)and skeletal muscle mass(SMM)are both key parameters of intrinsic capacity.To date,the impact of adherence to physical activity guidelines by older adults on these facets is poorly understood.Therefore,this study aimed to assess the impact of 4 weeks adherence to UK physical activity guidelines on parameters of intrinsic capacity in older adults,with a secondary aim to determine the utility of a bedside-suitable predictive model of assessing CRF for predicting change in this parameter.Methods:14 older adults(22%female,age:66–80 years)completed a 4-week intervention in which they adhered to UK physical activity guidelines via a combination of supervised and home-based exercise.In addition to assessments of CRF via cardiopulmonary exercise testing and SMM via ultrasonography,whole-body and handgrip strength(HGS)and step-box test(SBT)variables were also measured before and after the intervention.Results:Our intervention resulted in significant increases in CRF(ventilatory threshold(VT):+2.7±0.9 mL/kg/min,p<0.01),vastus lateralis muscle thickness(+9%,p=0.02)and whole body strength(+47%,p<0.01).There was no change in HGS or SBT performance.The bedside-suitable predictive model of CRF was not able to determine change(R^(2)=0.11,p=0.25).Conclusions:Adherence to UK physical activity guidelines for just 4 weeks improves the CRF,SMM and whole-body strength of community-dwelling older adults.Collectively,these findings illustrate that adherence to current guidelines can improve key aspects of intrinsic capacity in older individuals.The impact of such interventions in populations at risk of accelerated physiological decline,warrant further investigation.
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.
基金the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(No.LSKJ202203206)the Fundamental Research Funds for the Central Universities(No.202161069)。
文摘Blooms of the toxic dinoflagellate Alexandrium spp.,which produce paralytic shellfish toxins(PSTs),have threatened marine ecosystems for decades.However,their impacts on benthic copepods remain underexplored.Here,we investigated the physiological and biochemical responses of marine benthic copepod Tigriopus japonicus to Alexandrium pacificum.Adult female showed no mortality within 24 h and maintained high survival(>80%)across all A.pacificum concentrations over 96 h,with no significant difference from non-toxic controls.Ingestion rates on A.pacificum and non-toxic controls were similar,when algal prey concentrations were lower than about 2500µgC/L.However,above this threshold,feeding of T.japonicus was significantly depressed by A.pacificum.Six-day exposure induced oxidative stress,marked by elevated level of reactive oxygen species,malondialdehyde,total antioxidant capacity and superoxide dismutase activity,while catalase activity showed a non-significant increase.Moreover,concentration-dependent increase was observed in acetylcholinesterase activity,and its positive correlation with oxidative biomarkers suggests additional roles in coping with stress.Chronic exposure over three generations did not consistently affect development,except for complete development failure in F2 and F3 at the highest concentration.However,moderate-to-high concentrations of A.pacificum significantly impaired reproduction,reducing egg production by 9.66%–96.07%and clutch numbers by 33.33%–55.56%.Our findings indicate that Alexandrium blooms can adversely impact benthic copepod feeding and population recruitment through neurotoxicity and oxidative stress,highlighting the ecological risks of prolonged algal blooms in benthic habitats.
文摘Oil tanks are essential components of the oil industry, facilitating the safe storage and transportation of crude oil. Safely managing oil tanks is a crucial aspect of environmental protection. Oil tanks are often used under extreme operational conditions, including dynamic loads, temperature variations, etc., which may result in unpredictable deformations that can cause severe damage or tank collapses. Therefore, it is essential to establish a monitoring system to prevent and predict potential deformations. Terrestrial laser scanning (TLS) has played a significant role in oil tank monitoring over the past decades. However, the full extent of TLS capabilities for oil tank monitoring has not yet been thoroughly investigated. This study aims to evaluate TLS’s abilities in detecting deformations of oil tanks under various operating conditions. The paper has two objectives: first, to examine the deformations of two vertical oil tanks over six years, and second, to investigate potential deformations of the tanks’ surfaces during filling. Each tank was scanned three times—in the years 2015, 2016, and 2021. Mathematical models and appropriate software were developed to determine the achievable accuracy of TLS monitoring. The anticipated monitoring accuracy was simulated based on the design parameters of the oil tanks. This accuracy was subsequently used to differentiate between deformations and measurement errors. The tank surface was approximated utilizing the cylinder equation for each monitoring epoch. Additionally, deformations were analyzed at different cross-sections with the appropriate circular approximations. The results indicated that both tanks exhibited no significant deformations within a range of less than 20 mm. For the empty tanks, the average radius decreased by 4 mm, without any changes in shape. The total spatial inclination of the oil tanks was calculated using cylinder equations at different monitoring epochs. In the final stage, the observed deformations were employed to simulate the strain-stress conditions of the oil tanks. Thus, this paper presents a complex technology and the results of oil tank monitoring by TLS under various operating conditions.
基金the National Natural Science Foundation of China(30800121).
文摘Mounting evidence suggests that male sperm may be gradually depleted after consecutive matings,resulting in the decline of female reproductive output in insect species.It is predicted that females may employ adaptive strategies to avoid the sperm-depleted males,such as mating multiply with different males and/or discriminating against previously mated males(MMs).Similarly,males may exhibit adaptive behaviors toward females varying in mating status.However,in spiders with males lacking primary copulatory organs and their pedipalps modified to transfer sperm,there are few studies on male mating potential and previous mating experience on their subsequent mate choice.In this study,we used a polyandrous crab spider,Ebrechtella tricuspidata,a sit-and-wait predator with female-biased sex ratio as a model system to ascertain whether 1)male mating experiences influence female reproductive fitness;2)females respond differently to males varying in mating status;and 3)males respond differently to females varying in mating status.Our results showed that female fecundity was independent of male mating experiences,but female fertility markedly declined with the increase of male previous mating experiences in the first eggsac.Counter to our predictions,females preferred to choose and mate with the larger males,regardless of their mating status.In contrast,male mating status influenced their mating preference toward females.Virgin males did not show any preference between virgin and mated females;however,MMs were more likely to prefer the virgin females over the mated ones.Overall,our results indicated that female choice depended primarily on male relative size rather than male mating status,whereas male choice depended on female mating status,Depending on the investigation of reproductive dynamics and mate choice in E.tricuspidata,the study will provide valuable insights into the adaptive behaviors of both males and females exhibiting toward mates varying inmating status.
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.
