Locomotion performance degradation after carrying payloads is a significant challenge for insect-scale microrobots.Previously,a legged microrobot named BHMbot with a high load-carrying capacity based on front-leg actu...Locomotion performance degradation after carrying payloads is a significant challenge for insect-scale microrobots.Previously,a legged microrobot named BHMbot with a high load-carrying capacity based on front-leg actuation configuration and efficient running gait was proposed.However,insects,mammals and reptiles in nature typically use their powerful rear legs to achieve rapid running gaits for predation or risk evasion.In this work,the load-carrying capacity of the BHMbots with front-leg actuation and rear-leg actuation configurations is comparatively studied.Simulations based on a dynamic model with four degrees of freedom,along with experiments,have been conducted to analyze the locomotion characteristics of the two configurations under different payload masses.Both simulation and experimental results indicate that the load-carrying capacity of the microrobots is closely related to their actuation configurations,which leads to different dynamic responses of the microrobots after carrying varying payload masses.For microrobots with body lengths of 15 mm,the rear-leg actuation configuration exhibits a 31.2%enhancement in running speed compared to the front-leg actuation configuration when unloaded.Conversely,when carrying payloads exceeding 5.7 times the body mass(350 mg),the rear-leg actuation configuration demonstrates an 80.1%reduction in running speed relative to the front-leg actuation configuration under the same payload conditions.展开更多
A thermal hydraulic model based on the lumped parameter method is presented to analyze the load-carrying capacity of a slipper pair in an aviation axial-piston pump under specified operating conditions. Both theoretic...A thermal hydraulic model based on the lumped parameter method is presented to analyze the load-carrying capacity of a slipper pair in an aviation axial-piston pump under specified operating conditions. Both theoretical and experimental results are presented to demonstrate the validity of the thermal hydraulic model. The results illustrate that the squeezing force and thermal wedge bearing force are the main factors that affect the film thickness and load-carrying capacity.At high oil temperature and high load pressure, the film thickness decreases with increasing clamping force due to a combined action of the squeezing bearing force and the thermal wedge bearing force, but the load-carrying capacity will increase. An increase of the film thickness is proven to be beneficial under high shaft rotational speed but especially dangerous as it strongly increases the ripple amplitude of the film thickness, which leads to decreasing the load-carrying capacity. The structural parameters of the slipper can be optimized to achieve desired performance, such as the slipper radius ratio and orifice length diameter ratio. To satisfy the requirement of the load-carrying capacity, the slipper radius ratio should be selected from 1.4 to 1.8, and the orifice length diameter ratio should be selected from 4 to 5.展开更多
Finding out the most effective parameters relating to the resistance of reinforced concrete connections(RCCs)is an important topic in structural engineering.In this study,first,a finite element(FE)model is developed f...Finding out the most effective parameters relating to the resistance of reinforced concrete connections(RCCs)is an important topic in structural engineering.In this study,first,a finite element(FE)model is developed for simulating the performance of RCCs under post-earthquake fire(PEF).Then surrogate models,including multiple linear regression(MLR),multiple natural logarithm(Ln)equation regression(MLn ER),gene expression programming(GEP),and an ensemble model,are used to predict the remaining load-carrying capacity of an RCC under PEF.The statistical parameters,error terms,and a novel statistical table are used to evaluate and compare the accuracy of each surrogate model.According to the results,the ratio of the longitudinal reinforcement bars of the column(RLC)has a significant effect on the resistance of an RCC under PEF.Increasing the value of this parameter from 1%to 8%can increase the residual load-carrying capacity of an RCC under PEF by 492.2%when the RCC is exposed to fire at a temperature of 1000°C.Moreover,based on the results,the ensemble model can predict the residual load-carrying capacity with suitable accuracy.A safety factor of 1.55 should be applied to the results obtained from the ensemble model.展开更多
A method is developed to predict the lateral load-carrying capacity of composite shear walls with double steel plates and filled concrete with binding bars(SCBs). Nonlinear finite element models of SCBs were establish...A method is developed to predict the lateral load-carrying capacity of composite shear walls with double steel plates and filled concrete with binding bars(SCBs). Nonlinear finite element models of SCBs were established by using the finite element tool, Abaqus. Tie constraints were used to connect the binding bars and the steel plates. Surface-to-surface contact provided by the Abaqus was used to simulate the interaction between the steel plate and the core concrete. The established models could predict the lateral load-carrying capacity of SCBs with a reasonable degree of accuracy. A calculation method was developed by superposition principle to predict the lateral load-carrying capacity of SCBs for the engineering application. The concrete confined by steel plates and binding bars is under multi-axial compression; therefore, its shear strength was calculated by using the Guo-Wang concrete failure criterion. The shear strength of the steel plates of SCBs was calculated by using the von Mises yielding criterion without considering buckling. Results of the developed method are in good agreement with the testing and finite element results.展开更多
A type of hollow cylinder joints connected with H-shaped beams is proposed for spatial structures. Based on von Mises yield criterion and perfect elasto-plasticity model, a series of finite element models of the joint...A type of hollow cylinder joints connected with H-shaped beams is proposed for spatial structures. Based on von Mises yield criterion and perfect elasto-plasticity model, a series of finite element models of the joints is established, in which the effect of geometric nonlinearity is taken into account. Then mechanical behavior and load-carrying capacity of the joints were investigated, which were subjected to axial load, in- and out-plane bending moments, and their combinations. The results show that the ultimate loads of the joints are determined by the maximum displacement. Furthermore, the case of one joint connected with multiple beams was discussed. Experiments on a set of typical full-scale joints were conducted to understand the structural behavior and the failure mechanism of joint, and also to validate the finite element models. Finally, the practical calculation method was established through finite elements analysis (FEA) results and numerical fitting. The results show that the joints are more ductile and materially economical than welded hollow spherical joints, and the practical calculation method can provide a reference for direct design and the revision of relevant design codes.展开更多
The elastic-plastic method is often used in designing the inner flat bulkhead plates of submarines, and the upper structure of ships and drilling platforms. Such bulkhead plates can bear the load only once. For the im...The elastic-plastic method is often used in designing the inner flat bulkhead plates of submarines, and the upper structure of ships and drilling platforms. Such bulkhead plates can bear the load only once. For the improvement of the load-carrying capacity or the reduction of the weight of plates, the yield line analytical method is employed in this paper to design the bulkhead plate to improve economy and increase the effiective load. Besides, a further sutdy of this method has been made theoretically and experimentally, and the data of the limited load-carrying capacity of the plate have been obtained. Furthermore, the safety coefficients for such a method are presented, which can be used as reference for related departments and staffs.展开更多
Boundary slippage is used to generate the load-carrying capacity of the hydrodynamic contact between two parallel plane surfaces. In the fluid inlet zone, the fluidcontact interfacial shear strength on a stationary su...Boundary slippage is used to generate the load-carrying capacity of the hydrodynamic contact between two parallel plane surfaces. In the fluid inlet zone, the fluidcontact interfacial shear strength on a stationary surface is set at low to generate boundary slippage there, while in the fluid outlet zone the fluid-contact interfacial shear strength on the stationary surface is set at high enough to prevent the occurrence of boundary slippage. The fluid-contact interfacial shear strength on the entire moving surface is set at high enough to prevent boundary slippage on the moving surface. These hydrodynamic contact configurations are analyzed to generate the pronounced load-carrying capacity. The optimum ratio of the outlet zone width to the inlet zone width for the maximum load-carrying capacity of the whole contact is found to be 0.5.展开更多
The concept of load-carrying capacity of the soil can be evaluated by two main components: permissible stress and permissible depth;and therefore, running it begins its assessment that allows an outline of exploitatio...The concept of load-carrying capacity of the soil can be evaluated by two main components: permissible stress and permissible depth;and therefore, running it begins its assessment that allows an outline of exploitation. Nevertheless, the assessment of the load-carrying capacity made the object of several works of research and many models, based on the multi-criteria analysis, have been established. This work examines the contribution of GIS approach to assessment load-carrying capacity of the soil. This one has been finished in two practicums: 1) Assessment of the capacity of soil by a multi-criteria approach, using the Weighted Sum Model (WSM);2) It brought to use the GIS approach to evaluate and spatialize degree of soil bearing stresses resulting from the buildings, as well as load distribution. The method has been applied to the Berhoum area of Hodna Basin, in eastern Algeria, where each is characterized by its various natural properties and density of equipment. Final results are better in the classification of the degree of load-carrying capacity possible in each site. This results in allowing exploiters to program their optimal designs for the rational management of the area.展开更多
Clearance not only affects the startup torque,rotation precision and stiffness of bearing,but also affects the load distribution,load-carrying capacity and life of bearing.A computational model in which the clearance ...Clearance not only affects the startup torque,rotation precision and stiffness of bearing,but also affects the load distribution,load-carrying capacity and life of bearing.A computational model in which the clearance of bearing is first included is presented for determining the contact force distribution and static load-carrying capacity of a double row four-point contact ball bearing which is subjected to the combined radial,axial and overturning moment loadings.The relation between the negative axial clearance and the contact force distribution is analyzed.The static load-carrying capacity curves are established,and the effects of the changes in negative axial clearance,curvature radius coefficient of raceway groove and initial contact angle on the static load-carrying capacity are analyzed.The results show that,with the increase in the absolute value of negative clearance,the maximum contact load decreases first and then increases.The clearance values in the range of 0.2 mme0 mm have little effect on the static load-carrying capacity of bearing.With the increase in the curvature radius coefficient of raceway groove and the decrease in the initial contact angle,the static load capacity of bearing decreases.展开更多
The aim of this paper is to explore the effect of geometrical parameters on ultimate load-carrying capacity of a circular hollow section(CHS)X-joint under axial compression of the brace end.First of all,finite element...The aim of this paper is to explore the effect of geometrical parameters on ultimate load-carrying capacity of a circular hollow section(CHS)X-joint under axial compression of the brace end.First of all,finite element(FE)model to calculate ultimate load-carrying capacity of the CHS X-joint subjected to uniaxial load of the brace is constructed,and the calculated load–displacement curves are compared to the experimental ones.After validation of the FE model,46080 groups of FE calculation models with different geometrical parameters are generated by means of parametric modeling.Subsequently,eight variables including gusset thickness and chord thickness are set as input to predict load-carrying capacity of the CHS X-joint by four machine learning(ML)algorithms,i.e.,Generalized Regression Neural Network,Support Vector Machine,random forest(RF),and Extreme Gradient Boosting(XGBoost).Finally,the constructed ML prediction models are interpreted by SHapley Additive exPlanations,to explore the impact weight of each factor on ultimate load-carrying capacity of the joint.The results show that all the four models can predict the load-carrying capacity of the subject accurately,with all the R2 values greater than 0.97.In addition,RF model yields the minimum mean-square error,Root Mean Squared Error,Mean Absolute Error,and Mean Absolute Percentage Error values,and the greatest R2 value,while the prediction accuracy of XGBoost is relatively worse.Among all the eight considered geometrical parameters,brace diameter has the strongest impact on load-carrying capacity of the joint,followed by chord thickness,chord ring width,chord ring thickness,brace ring width,and brace thickness,while the thicknesses of the gusset plate and brace have marginal influence on load-carrying capacity.The study of the current paper can provide guidelines for dimension design of CHS X-joints.展开更多
Background:The trajectory of intrinsic capacity(IC)among the older population is characterized by its diversity and is predictive of adverse health outcomes such as disability,nursing home admission,decline in quality...Background:The trajectory of intrinsic capacity(IC)among the older population is characterized by its diversity and is predictive of adverse health outcomes such as disability,nursing home admission,decline in quality of life,and mortality.Gaining an understanding of the trajectory of IC and the factors that influence it is of paramount importance for fostering healthy aging.This research is focused on exploring the trajectory of IC among older adults in China and examining the factors that influence it.Methods:This observational longitudinal cohort study leveraged data from the China Health and Retirement Longitudinal Study(CHARLS),which was conducted in the years 2011,2013,and 2015.For the purpose of this analysis,a total of 2,233 participants who were aged 60 and over were included.A Growth Mixture Model(GMM)was utilized to define trajectory categories for IC.Influential factors were ascertained based on the health ecology model,and binary logistic regression analysis was utilized to investigate the factors linked with the different trajectory categories.Results:Two distinct trajectory classes of IC were identified:Class 1,the normal-stable group,encompassed 90.4%of the elderly population,while Class 2,the declining group,made up 9.6%.Advanced age and a history of stroke were found to be significantly associated with Class 2.High scores in activities of daily living(ADL),employment status,receiving primary or junior high school education,and residence in the East or Central regions of China were significantly linked with Class 1.Conclusion:The trajectory of IC among older Chinese adults is marked by its heterogeneity.Advanced age and a history of stroke are significant risk factors for a declining IC trajectory,while higher ADL scores,being employed,receiving primary or junior high school education,and residing in the East or Central regions of China are protective factors associated with a stable IC trajectory.Healthcare institutions must closely monitor IC levels and understand these trajectory patterns to implement personalized and targeted interventions promptly to maintain IC at a healthy level and advocate for healthy aging.展开更多
Large-scale access of distributed photovoltaic(PV)in distribution networks(DNs),if not properly evaluated,brings several operational problems.Uncertainties arising from both PV outputs and load demand significantly im...Large-scale access of distributed photovoltaic(PV)in distribution networks(DNs),if not properly evaluated,brings several operational problems.Uncertainties arising from both PV outputs and load demand significantly impact evaluation results.To address this issue,this paper proposes a possibilistic approach to evaluate PV hosting capacity(PVHC).First,possibility distribution is used to model load demand in order to reflect uncertainties associated with human factor,whereas the interval model is applied to deal with uncertainties of PV outputs.Second,a voltage deterioration index is proposed considering overvoltage risk of entire system on time scale.After that,possibilistic PVHC evaluation method based on this index is proposed.A 6-bus system is used to illustrate advantages of the proposed method,followed by a discussion of role of PVHC possibility distribution in actual decision-making of utilities.Moreover,sensitivity of simulation parameters is analyzed to reduce computational burden.Finally,the proposed method is tested on the IEEE 123-bus DN to validate adaptability to a larger system and to analyze impact of PVHC results against different acceptable values set by utilities.展开更多
China has set its economic growth target for 2026 in the range of 4.5-5 percent.After three consecutive years of aiming for growth of around 5 percent,the slightly adjusted range reflects a prudent assessment of a com...China has set its economic growth target for 2026 in the range of 4.5-5 percent.After three consecutive years of aiming for growth of around 5 percent,the slightly adjusted range reflects a prudent assessment of a complex global environment while still signalling a commitment to stable development.展开更多
Background:Intrinsic capacity reflects the overall health status of older adults and decline in intrinsic abilities can lead to adverse health outcomes.However,empirical studies examining the association between digit...Background:Intrinsic capacity reflects the overall health status of older adults and decline in intrinsic abilities can lead to adverse health outcomes.However,empirical studies examining the association between digital health literacy,health-promoting lifestyles and intrinsic capacity are scarce.Methods:A cross-sectional study was conducted.Using convenience sampling method,371 older adults were recruited from communities.Multidimensional intrinsic capacity,digital health literacy,health promoting lifestyle and sociodemographic information were measured.Results:The intrinsic capacity of older adults scored 3.75±1.10.The prevalences of declined cognitive capacity,psychological capacity,sensory capacity,vitality,and locomotor capacity were 13.7%,24.3%,19.1%,14.8%,53.1%,respectively.The multiple regression analysis revealed that age(β=−0.253),only living with children and/or grandchildren(β=0.249),current working status(β=−0.132),number of chronic diseases(β=−0.149),frequency of Internet usage(β=0.193),the domain of ability to acquire and evaluate digital health information(β=0.197)in digital health literacy,and the domain of nutrition(β=0.171)in health-promoting lifestyle were the significant factors influencing intrinsic capacity,explaining 27.1%of the variance.Conclusion:Digital health literacy and health-promoting lifestyle have a significant impact on intrinsic capacity.Enhancing digital health literacy and advocating a health-promoting lifestyle are critical to promoting intrinsic capacity for community-dwelling older adults.展开更多
Although wind energy is volatile,the output of a wind-storage plant is partially dispatchable,making it a promising paradigm on the generation side.A grid-friendly wind-storage plant ought to be able to continuously o...Although wind energy is volatile,the output of a wind-storage plant is partially dispatchable,making it a promising paradigm on the generation side.A grid-friendly wind-storage plant ought to be able to continuously output the desired power over a certain period of time.This paper proposes a dependable dynamic capacity provision scheme of a wind-storage plant over a daily horizon.It stipulates a minimum number of periods during which the committed capacity must be fulfilled and a maximum mismatch during the remaining periods when the desired power output is not achievable.In the general case,the day-ahead piecewise constant capacity provision results in a two-stage stochastic program formulated as a mixed-integer linear program.Specifically,for constant capacity provision,a decomposition algorithm is developed to determine the global optimal solution,and the complexity grows linearly with the number of scenarios.Given the committed capacity trajectory,the real-time operation problem is modeled as a four-state stochastic dynamic program.The discrete state-action values are derived recursively via the principle of optimality.Real-time dispatch actions are generated by using the action-value tabular leveraging inexact ultra-short-term forecasts.Numerical tests over one year demonstrate that the proposed method successfully fulfills reliable operation on 355 days and achieve an optimality gap of 9.47%compared with the ex-post optimum,which is comparable to model predictive control using exact 2–3-hour-ahead wind power forecasts.展开更多
Research on high-speed railways is a relatively new yet highly significant field in Vietnam.Among its key components,train control signaling plays a critical role,as it directly affects various interconnected systems,...Research on high-speed railways is a relatively new yet highly significant field in Vietnam.Among its key components,train control signaling plays a critical role,as it directly affects various interconnected systems,including infrastructure,traction power supply,operational planning,and overall railway safety.This article focuses on evaluating the capacity of the line based on the types of signals suitable for high-speed railways that have been effectively implemented in several European countries and successfully adapted in China.The research and simulation are conducted using MATLAB software,a reliable and widely adopted tool in the scientific community.The findings demonstrate that under normal conditions,the European Railway Traffic Management System/European Train Control System(ERTMS/ETCS)Level 2 signaling can support up to 23.7485 trains/hour/direction.Meanwhile,ERTMS/ETCS Level 3 with full moving block can accommodate up to 30.8735 trains/hour/direction,and ERTMS/ETCS Level 3 with fixed virtual blocks up to 29.4694 trains/hour/direction.In emergency scenarios,ERTMS/ETCS Level 3 with full moving block reduces headway by 33.27%compared to CTCS Level 3,while ERTMS/ETCS Level 3 with fixed virtual blocks achieves a 28.78%reduction.Overall,the ERTMS/ETCS Level 3 emerges as a state-of-the-art signaling technology offering high capacity and operational efficiency,and is recommended as a forward-looking solution for future implementation in Vietnam.展开更多
Purpose-This study investigates the impact of flagship trains on high-speed railway capacity utilization and develops a brand value-oriented optimization framework that balances service quality enhancement with operat...Purpose-This study investigates the impact of flagship trains on high-speed railway capacity utilization and develops a brand value-oriented optimization framework that balances service quality enhancement with operational efficiency.Design/methodology/approach-A mathematical optimization model based on integer programming is developed,incorporating flagship train constraints into capacity optimization.Case studies compare scenarios with and without flagship train considerations using the Beijing-Shanghai High-Speed Railway data across 20 experimental groups.Findings-Operating flagship trains with hourly departure constraints results in an average decrease of 0.9 trains and an 8.4%reduction in capacity utilization rate.When scheduling 2 flagship trains within a 2-h timeframe,capacity utilization decreases from 86.43%to 83.73%,quantifying the trade-off between brand positioning and operational capacity.Originality/value-This research provides the first quantitative framework for brand value-oriented railway capacity optimization,establishing clear definitions for flagship trains and mathematical foundations for evaluating service quality versus efficiency trade-offs.The findings offer practical decision support for railway operators balancing competitive positioning with capacity maximization.展开更多
Background Selective breeding for disease resistance is an effective strategy to control duck hepatitis A virus type 3(DHAV-3)in waterfowl.However,the mechanism underlying resistance remains poorly understood,particul...Background Selective breeding for disease resistance is an effective strategy to control duck hepatitis A virus type 3(DHAV-3)in waterfowl.However,the mechanism underlying resistance remains poorly understood,particularly those associated with antioxidant defense,intestinal development and host-microbiota interactions.Method A total of 1001-day-old Pekin ducklings were used in this study with 50 DHAV-3 susceptible and resistant ducks,respectively.Samples were collected at 7 days post-hatching(D7),D21 and D42,10 birds per group.We compared DHAV-3 resistant and susceptible ducks during early development with respect to immune organ indices,antioxidant capacity,intestinal morphology,barrier-related gene expression and cecal microbiota.Result Resistant ducks exhibited higher spleen indices and stronger antioxidant capacity,characterized by increased superoxide dismutase,reduced glutathione,and total antioxidant capacity,along with lower malondialdehyde levels at D7 and D21.In contrast,susceptible ducks showed compensatory thymus hypertrophy and delayed development of antioxidant defense and intestinal maturation.Ileal morphology revealed greater villus height and width with more regular arrangement in resistant ducks at D7,whereas these differences diminished at D21 and D42.Gene expression analysis demonstrated higher early expression of the tight junction proteins CLDN1 and CLDN3 in resistant ducks,while susceptible ducks displayed elevated MUC2 and OCLN,suggesting stress induced compensatory responses.Cecal microbiota analysis revealed distinct colonization patterns in early development.Resistant ducks were enriched with Firmicutes and beneficial genera such as Enterococcus and Lactobacillus,whereas susceptible ducks harbored higher abundances of Bacteroidota and potentially opportunistic taxa.Microbial diversity increased with age in both groups,but resistant ducks displayed more orderly succession and enrichment of SCFA producing genera,including Subdoligranulum and Phascolarctobacterium,which positively correlated with plasma antioxidant indices.Conclusion DHAV-3 resistant ducks exhibit early advantages in antioxidant defense,intestinal barrier development and colonization by beneficial microbiota,which collectively contribute to enhanced disease resistance.These findings highlight the synergistic roles of host physiology and gut microbiota in shaping resistance.In the future,integrating genomic selection with microbiota modulation and antioxidant interventions may accelerate the breeding of highly resistant duck lines and provide scientific evidence and practical strategies for controlling duck viral hepatitis.展开更多
China Standardization:Can you please briefly introduce ISO,its international standards as well as your scope of work?Rachel Miller Prada:ISO is an independent non-governmental organization dedicated to developing inte...China Standardization:Can you please briefly introduce ISO,its international standards as well as your scope of work?Rachel Miller Prada:ISO is an independent non-governmental organization dedicated to developing international standards.Currently,ISO has 175 member bodies,representing 175 countries that participate in its standard development work.We have a portfolio of over 24,000 international standards,with around 100 new standards issued or existing ones revised every month.The ultimate goal of our standardization work is to support the achievement of the United Nations Sustainable Development Goals(SDGs).Every standard we develop and every task I undertake in my role contributes to these global objectives.展开更多
In this paper,we propose a novel probabilistic method for predicting the undrained bearing capacity of spatially variable soils.Our approach combines a Gaussian process regression(GPR)-based surrogate model with rando...In this paper,we propose a novel probabilistic method for predicting the undrained bearing capacity of spatially variable soils.Our approach combines a Gaussian process regression(GPR)-based surrogate model with random cell-based smoothed finite analysis.The Gaussian process emulator(GPE)serves as a statistical tool for making predictions from a data set.First,we validate the accuracy and efficiency of kinematic limit analysis using the cell-based smoothed finite element method(CS-FEM)against the standard finite element method(FEM)and edge-based smoothed FEM(ES-FEM).The numerical results demonstrate that the CS-FEM framework surpasses traditional numerical approaches,establishing its reliability in computing collapse loads.Subsequently,we conduct several hundred simulations to develop a surrogate model for predicting the undrained bearing capacity of shallow foundations.By utilizing various kernel functions,we enhance the accuracy of the GPE in these predictions.This method offers a practical and efficient solution,effectively addressing multiple uncertainties.Numerical results indicate that the GPE significantly boosts computational efficiency,achieving satisfactory outcomes within minutes compared to the days required for conventional simulations.Notably,the mean absolute percentage error(MAPE)decreases from 2.38%to 1.82%for rough foundations when employing Matérn and rational quadratic kernel functions,respectively.Additionally,combining different kernel functions further enhances the accuracy of collapse load predictions.展开更多
基金supported in part by Beijing Natural Science Foundation under Grant 3232010in part by the National Natural Science Foundation of China under Grant 12002017+2 种基金in part by AECC Industry-university Collocation Fund under Grant HFZL2023CXY026in part by Beihang Outstanding Young Scholars Project under Grant YWF-23-L-1201in part by 111 Project under Grant B08009.
文摘Locomotion performance degradation after carrying payloads is a significant challenge for insect-scale microrobots.Previously,a legged microrobot named BHMbot with a high load-carrying capacity based on front-leg actuation configuration and efficient running gait was proposed.However,insects,mammals and reptiles in nature typically use their powerful rear legs to achieve rapid running gaits for predation or risk evasion.In this work,the load-carrying capacity of the BHMbots with front-leg actuation and rear-leg actuation configurations is comparatively studied.Simulations based on a dynamic model with four degrees of freedom,along with experiments,have been conducted to analyze the locomotion characteristics of the two configurations under different payload masses.Both simulation and experimental results indicate that the load-carrying capacity of the microrobots is closely related to their actuation configurations,which leads to different dynamic responses of the microrobots after carrying varying payload masses.For microrobots with body lengths of 15 mm,the rear-leg actuation configuration exhibits a 31.2%enhancement in running speed compared to the front-leg actuation configuration when unloaded.Conversely,when carrying payloads exceeding 5.7 times the body mass(350 mg),the rear-leg actuation configuration demonstrates an 80.1%reduction in running speed relative to the front-leg actuation configuration under the same payload conditions.
基金co-supported by the National Natural Science Foundation of China (No. 51505338 and No. 51475332)the Youths Science Foundation of Zhejiang (No. LQ16E050004 and No. LQ17E050003)
文摘A thermal hydraulic model based on the lumped parameter method is presented to analyze the load-carrying capacity of a slipper pair in an aviation axial-piston pump under specified operating conditions. Both theoretical and experimental results are presented to demonstrate the validity of the thermal hydraulic model. The results illustrate that the squeezing force and thermal wedge bearing force are the main factors that affect the film thickness and load-carrying capacity.At high oil temperature and high load pressure, the film thickness decreases with increasing clamping force due to a combined action of the squeezing bearing force and the thermal wedge bearing force, but the load-carrying capacity will increase. An increase of the film thickness is proven to be beneficial under high shaft rotational speed but especially dangerous as it strongly increases the ripple amplitude of the film thickness, which leads to decreasing the load-carrying capacity. The structural parameters of the slipper can be optimized to achieve desired performance, such as the slipper radius ratio and orifice length diameter ratio. To satisfy the requirement of the load-carrying capacity, the slipper radius ratio should be selected from 1.4 to 1.8, and the orifice length diameter ratio should be selected from 4 to 5.
文摘Finding out the most effective parameters relating to the resistance of reinforced concrete connections(RCCs)is an important topic in structural engineering.In this study,first,a finite element(FE)model is developed for simulating the performance of RCCs under post-earthquake fire(PEF).Then surrogate models,including multiple linear regression(MLR),multiple natural logarithm(Ln)equation regression(MLn ER),gene expression programming(GEP),and an ensemble model,are used to predict the remaining load-carrying capacity of an RCC under PEF.The statistical parameters,error terms,and a novel statistical table are used to evaluate and compare the accuracy of each surrogate model.According to the results,the ratio of the longitudinal reinforcement bars of the column(RLC)has a significant effect on the resistance of an RCC under PEF.Increasing the value of this parameter from 1%to 8%can increase the residual load-carrying capacity of an RCC under PEF by 492.2%when the RCC is exposed to fire at a temperature of 1000°C.Moreover,based on the results,the ensemble model can predict the residual load-carrying capacity with suitable accuracy.A safety factor of 1.55 should be applied to the results obtained from the ensemble model.
基金Project(51178333)supported by the National Natural Science Foundation of ChinaProject(SLDRCE09-D-03)supported by the Ministry of Science and Technology of China
文摘A method is developed to predict the lateral load-carrying capacity of composite shear walls with double steel plates and filled concrete with binding bars(SCBs). Nonlinear finite element models of SCBs were established by using the finite element tool, Abaqus. Tie constraints were used to connect the binding bars and the steel plates. Surface-to-surface contact provided by the Abaqus was used to simulate the interaction between the steel plate and the core concrete. The established models could predict the lateral load-carrying capacity of SCBs with a reasonable degree of accuracy. A calculation method was developed by superposition principle to predict the lateral load-carrying capacity of SCBs for the engineering application. The concrete confined by steel plates and binding bars is under multi-axial compression; therefore, its shear strength was calculated by using the Guo-Wang concrete failure criterion. The shear strength of the steel plates of SCBs was calculated by using the von Mises yielding criterion without considering buckling. Results of the developed method are in good agreement with the testing and finite element results.
基金Project supported by the National Natural Science Foundation of China (No. 51178414)the Science Foundation of Zhejiang Province (No. Y1110438), China
文摘A type of hollow cylinder joints connected with H-shaped beams is proposed for spatial structures. Based on von Mises yield criterion and perfect elasto-plasticity model, a series of finite element models of the joints is established, in which the effect of geometric nonlinearity is taken into account. Then mechanical behavior and load-carrying capacity of the joints were investigated, which were subjected to axial load, in- and out-plane bending moments, and their combinations. The results show that the ultimate loads of the joints are determined by the maximum displacement. Furthermore, the case of one joint connected with multiple beams was discussed. Experiments on a set of typical full-scale joints were conducted to understand the structural behavior and the failure mechanism of joint, and also to validate the finite element models. Finally, the practical calculation method was established through finite elements analysis (FEA) results and numerical fitting. The results show that the joints are more ductile and materially economical than welded hollow spherical joints, and the practical calculation method can provide a reference for direct design and the revision of relevant design codes.
文摘The elastic-plastic method is often used in designing the inner flat bulkhead plates of submarines, and the upper structure of ships and drilling platforms. Such bulkhead plates can bear the load only once. For the improvement of the load-carrying capacity or the reduction of the weight of plates, the yield line analytical method is employed in this paper to design the bulkhead plate to improve economy and increase the effiective load. Besides, a further sutdy of this method has been made theoretically and experimentally, and the data of the limited load-carrying capacity of the plate have been obtained. Furthermore, the safety coefficients for such a method are presented, which can be used as reference for related departments and staffs.
文摘Boundary slippage is used to generate the load-carrying capacity of the hydrodynamic contact between two parallel plane surfaces. In the fluid inlet zone, the fluidcontact interfacial shear strength on a stationary surface is set at low to generate boundary slippage there, while in the fluid outlet zone the fluid-contact interfacial shear strength on the stationary surface is set at high enough to prevent the occurrence of boundary slippage. The fluid-contact interfacial shear strength on the entire moving surface is set at high enough to prevent boundary slippage on the moving surface. These hydrodynamic contact configurations are analyzed to generate the pronounced load-carrying capacity. The optimum ratio of the outlet zone width to the inlet zone width for the maximum load-carrying capacity of the whole contact is found to be 0.5.
文摘The concept of load-carrying capacity of the soil can be evaluated by two main components: permissible stress and permissible depth;and therefore, running it begins its assessment that allows an outline of exploitation. Nevertheless, the assessment of the load-carrying capacity made the object of several works of research and many models, based on the multi-criteria analysis, have been established. This work examines the contribution of GIS approach to assessment load-carrying capacity of the soil. This one has been finished in two practicums: 1) Assessment of the capacity of soil by a multi-criteria approach, using the Weighted Sum Model (WSM);2) It brought to use the GIS approach to evaluate and spatialize degree of soil bearing stresses resulting from the buildings, as well as load distribution. The method has been applied to the Berhoum area of Hodna Basin, in eastern Algeria, where each is characterized by its various natural properties and density of equipment. Final results are better in the classification of the degree of load-carrying capacity possible in each site. This results in allowing exploiters to program their optimal designs for the rational management of the area.
基金supported by NSFC(51105131)Excellent Youth Foundation of Henan Scientific Committee(124100510002)Creative Talent Foundation in University of Henan Province(2011HASTIT016)
文摘Clearance not only affects the startup torque,rotation precision and stiffness of bearing,but also affects the load distribution,load-carrying capacity and life of bearing.A computational model in which the clearance of bearing is first included is presented for determining the contact force distribution and static load-carrying capacity of a double row four-point contact ball bearing which is subjected to the combined radial,axial and overturning moment loadings.The relation between the negative axial clearance and the contact force distribution is analyzed.The static load-carrying capacity curves are established,and the effects of the changes in negative axial clearance,curvature radius coefficient of raceway groove and initial contact angle on the static load-carrying capacity are analyzed.The results show that,with the increase in the absolute value of negative clearance,the maximum contact load decreases first and then increases.The clearance values in the range of 0.2 mme0 mm have little effect on the static load-carrying capacity of bearing.With the increase in the curvature radius coefficient of raceway groove and the decrease in the initial contact angle,the static load capacity of bearing decreases.
文摘The aim of this paper is to explore the effect of geometrical parameters on ultimate load-carrying capacity of a circular hollow section(CHS)X-joint under axial compression of the brace end.First of all,finite element(FE)model to calculate ultimate load-carrying capacity of the CHS X-joint subjected to uniaxial load of the brace is constructed,and the calculated load–displacement curves are compared to the experimental ones.After validation of the FE model,46080 groups of FE calculation models with different geometrical parameters are generated by means of parametric modeling.Subsequently,eight variables including gusset thickness and chord thickness are set as input to predict load-carrying capacity of the CHS X-joint by four machine learning(ML)algorithms,i.e.,Generalized Regression Neural Network,Support Vector Machine,random forest(RF),and Extreme Gradient Boosting(XGBoost).Finally,the constructed ML prediction models are interpreted by SHapley Additive exPlanations,to explore the impact weight of each factor on ultimate load-carrying capacity of the joint.The results show that all the four models can predict the load-carrying capacity of the subject accurately,with all the R2 values greater than 0.97.In addition,RF model yields the minimum mean-square error,Root Mean Squared Error,Mean Absolute Error,and Mean Absolute Percentage Error values,and the greatest R2 value,while the prediction accuracy of XGBoost is relatively worse.Among all the eight considered geometrical parameters,brace diameter has the strongest impact on load-carrying capacity of the joint,followed by chord thickness,chord ring width,chord ring thickness,brace ring width,and brace thickness,while the thicknesses of the gusset plate and brace have marginal influence on load-carrying capacity.The study of the current paper can provide guidelines for dimension design of CHS X-joints.
基金China Health and Retirement Longitudinal Study(CHARLS)the 2022-2023 Nursing Research Project of Chinese Medical Association Publishing House(Grant No.CMAPH-NRD2022024)。
文摘Background:The trajectory of intrinsic capacity(IC)among the older population is characterized by its diversity and is predictive of adverse health outcomes such as disability,nursing home admission,decline in quality of life,and mortality.Gaining an understanding of the trajectory of IC and the factors that influence it is of paramount importance for fostering healthy aging.This research is focused on exploring the trajectory of IC among older adults in China and examining the factors that influence it.Methods:This observational longitudinal cohort study leveraged data from the China Health and Retirement Longitudinal Study(CHARLS),which was conducted in the years 2011,2013,and 2015.For the purpose of this analysis,a total of 2,233 participants who were aged 60 and over were included.A Growth Mixture Model(GMM)was utilized to define trajectory categories for IC.Influential factors were ascertained based on the health ecology model,and binary logistic regression analysis was utilized to investigate the factors linked with the different trajectory categories.Results:Two distinct trajectory classes of IC were identified:Class 1,the normal-stable group,encompassed 90.4%of the elderly population,while Class 2,the declining group,made up 9.6%.Advanced age and a history of stroke were found to be significantly associated with Class 2.High scores in activities of daily living(ADL),employment status,receiving primary or junior high school education,and residence in the East or Central regions of China were significantly linked with Class 1.Conclusion:The trajectory of IC among older Chinese adults is marked by its heterogeneity.Advanced age and a history of stroke are significant risk factors for a declining IC trajectory,while higher ADL scores,being employed,receiving primary or junior high school education,and residing in the East or Central regions of China are protective factors associated with a stable IC trajectory.Healthcare institutions must closely monitor IC levels and understand these trajectory patterns to implement personalized and targeted interventions promptly to maintain IC at a healthy level and advocate for healthy aging.
基金supported by the National Key R&D Program of China(2018YFB0904700).
文摘Large-scale access of distributed photovoltaic(PV)in distribution networks(DNs),if not properly evaluated,brings several operational problems.Uncertainties arising from both PV outputs and load demand significantly impact evaluation results.To address this issue,this paper proposes a possibilistic approach to evaluate PV hosting capacity(PVHC).First,possibility distribution is used to model load demand in order to reflect uncertainties associated with human factor,whereas the interval model is applied to deal with uncertainties of PV outputs.Second,a voltage deterioration index is proposed considering overvoltage risk of entire system on time scale.After that,possibilistic PVHC evaluation method based on this index is proposed.A 6-bus system is used to illustrate advantages of the proposed method,followed by a discussion of role of PVHC possibility distribution in actual decision-making of utilities.Moreover,sensitivity of simulation parameters is analyzed to reduce computational burden.Finally,the proposed method is tested on the IEEE 123-bus DN to validate adaptability to a larger system and to analyze impact of PVHC results against different acceptable values set by utilities.
文摘China has set its economic growth target for 2026 in the range of 4.5-5 percent.After three consecutive years of aiming for growth of around 5 percent,the slightly adjusted range reflects a prudent assessment of a complex global environment while still signalling a commitment to stable development.
基金funded by the College Students’Innovation and Entrepreneurship Program(X2024110650385).
文摘Background:Intrinsic capacity reflects the overall health status of older adults and decline in intrinsic abilities can lead to adverse health outcomes.However,empirical studies examining the association between digital health literacy,health-promoting lifestyles and intrinsic capacity are scarce.Methods:A cross-sectional study was conducted.Using convenience sampling method,371 older adults were recruited from communities.Multidimensional intrinsic capacity,digital health literacy,health promoting lifestyle and sociodemographic information were measured.Results:The intrinsic capacity of older adults scored 3.75±1.10.The prevalences of declined cognitive capacity,psychological capacity,sensory capacity,vitality,and locomotor capacity were 13.7%,24.3%,19.1%,14.8%,53.1%,respectively.The multiple regression analysis revealed that age(β=−0.253),only living with children and/or grandchildren(β=0.249),current working status(β=−0.132),number of chronic diseases(β=−0.149),frequency of Internet usage(β=0.193),the domain of ability to acquire and evaluate digital health information(β=0.197)in digital health literacy,and the domain of nutrition(β=0.171)in health-promoting lifestyle were the significant factors influencing intrinsic capacity,explaining 27.1%of the variance.Conclusion:Digital health literacy and health-promoting lifestyle have a significant impact on intrinsic capacity.Enhancing digital health literacy and advocating a health-promoting lifestyle are critical to promoting intrinsic capacity for community-dwelling older adults.
基金supported by the Smart Grid-National Science and Technology Major Project of China(2024ZD0802000).
文摘Although wind energy is volatile,the output of a wind-storage plant is partially dispatchable,making it a promising paradigm on the generation side.A grid-friendly wind-storage plant ought to be able to continuously output the desired power over a certain period of time.This paper proposes a dependable dynamic capacity provision scheme of a wind-storage plant over a daily horizon.It stipulates a minimum number of periods during which the committed capacity must be fulfilled and a maximum mismatch during the remaining periods when the desired power output is not achievable.In the general case,the day-ahead piecewise constant capacity provision results in a two-stage stochastic program formulated as a mixed-integer linear program.Specifically,for constant capacity provision,a decomposition algorithm is developed to determine the global optimal solution,and the complexity grows linearly with the number of scenarios.Given the committed capacity trajectory,the real-time operation problem is modeled as a four-state stochastic dynamic program.The discrete state-action values are derived recursively via the principle of optimality.Real-time dispatch actions are generated by using the action-value tabular leveraging inexact ultra-short-term forecasts.Numerical tests over one year demonstrate that the proposed method successfully fulfills reliable operation on 355 days and achieve an optimality gap of 9.47%compared with the ex-post optimum,which is comparable to model predictive control using exact 2–3-hour-ahead wind power forecasts.
文摘Research on high-speed railways is a relatively new yet highly significant field in Vietnam.Among its key components,train control signaling plays a critical role,as it directly affects various interconnected systems,including infrastructure,traction power supply,operational planning,and overall railway safety.This article focuses on evaluating the capacity of the line based on the types of signals suitable for high-speed railways that have been effectively implemented in several European countries and successfully adapted in China.The research and simulation are conducted using MATLAB software,a reliable and widely adopted tool in the scientific community.The findings demonstrate that under normal conditions,the European Railway Traffic Management System/European Train Control System(ERTMS/ETCS)Level 2 signaling can support up to 23.7485 trains/hour/direction.Meanwhile,ERTMS/ETCS Level 3 with full moving block can accommodate up to 30.8735 trains/hour/direction,and ERTMS/ETCS Level 3 with fixed virtual blocks up to 29.4694 trains/hour/direction.In emergency scenarios,ERTMS/ETCS Level 3 with full moving block reduces headway by 33.27%compared to CTCS Level 3,while ERTMS/ETCS Level 3 with fixed virtual blocks achieves a 28.78%reduction.Overall,the ERTMS/ETCS Level 3 emerges as a state-of-the-art signaling technology offering high capacity and operational efficiency,and is recommended as a forward-looking solution for future implementation in Vietnam.
基金funded by the Science and Technology Research and Development Program Project of China Railway Group Co.,Ltd,grant number P2024X002the China Academy of Railway Sciences Corporation Limited,grant number 2024YJ154.
文摘Purpose-This study investigates the impact of flagship trains on high-speed railway capacity utilization and develops a brand value-oriented optimization framework that balances service quality enhancement with operational efficiency.Design/methodology/approach-A mathematical optimization model based on integer programming is developed,incorporating flagship train constraints into capacity optimization.Case studies compare scenarios with and without flagship train considerations using the Beijing-Shanghai High-Speed Railway data across 20 experimental groups.Findings-Operating flagship trains with hourly departure constraints results in an average decrease of 0.9 trains and an 8.4%reduction in capacity utilization rate.When scheduling 2 flagship trains within a 2-h timeframe,capacity utilization decreases from 86.43%to 83.73%,quantifying the trade-off between brand positioning and operational capacity.Originality/value-This research provides the first quantitative framework for brand value-oriented railway capacity optimization,establishing clear definitions for flagship trains and mathematical foundations for evaluating service quality versus efficiency trade-offs.The findings offer practical decision support for railway operators balancing competitive positioning with capacity maximization.
基金supported by the National Key R&D Program of China(2022YFD1301800)grants from the National Natural Science Foundation of China(grant number 32502899)+1 种基金China Agriculture Research System of MOF and MARA(CARS-42-10)the Agricultural Science and Technology Innovation Program of CAAS(CAAS-ASTIP-2023-IFR-13)。
文摘Background Selective breeding for disease resistance is an effective strategy to control duck hepatitis A virus type 3(DHAV-3)in waterfowl.However,the mechanism underlying resistance remains poorly understood,particularly those associated with antioxidant defense,intestinal development and host-microbiota interactions.Method A total of 1001-day-old Pekin ducklings were used in this study with 50 DHAV-3 susceptible and resistant ducks,respectively.Samples were collected at 7 days post-hatching(D7),D21 and D42,10 birds per group.We compared DHAV-3 resistant and susceptible ducks during early development with respect to immune organ indices,antioxidant capacity,intestinal morphology,barrier-related gene expression and cecal microbiota.Result Resistant ducks exhibited higher spleen indices and stronger antioxidant capacity,characterized by increased superoxide dismutase,reduced glutathione,and total antioxidant capacity,along with lower malondialdehyde levels at D7 and D21.In contrast,susceptible ducks showed compensatory thymus hypertrophy and delayed development of antioxidant defense and intestinal maturation.Ileal morphology revealed greater villus height and width with more regular arrangement in resistant ducks at D7,whereas these differences diminished at D21 and D42.Gene expression analysis demonstrated higher early expression of the tight junction proteins CLDN1 and CLDN3 in resistant ducks,while susceptible ducks displayed elevated MUC2 and OCLN,suggesting stress induced compensatory responses.Cecal microbiota analysis revealed distinct colonization patterns in early development.Resistant ducks were enriched with Firmicutes and beneficial genera such as Enterococcus and Lactobacillus,whereas susceptible ducks harbored higher abundances of Bacteroidota and potentially opportunistic taxa.Microbial diversity increased with age in both groups,but resistant ducks displayed more orderly succession and enrichment of SCFA producing genera,including Subdoligranulum and Phascolarctobacterium,which positively correlated with plasma antioxidant indices.Conclusion DHAV-3 resistant ducks exhibit early advantages in antioxidant defense,intestinal barrier development and colonization by beneficial microbiota,which collectively contribute to enhanced disease resistance.These findings highlight the synergistic roles of host physiology and gut microbiota in shaping resistance.In the future,integrating genomic selection with microbiota modulation and antioxidant interventions may accelerate the breeding of highly resistant duck lines and provide scientific evidence and practical strategies for controlling duck viral hepatitis.
文摘China Standardization:Can you please briefly introduce ISO,its international standards as well as your scope of work?Rachel Miller Prada:ISO is an independent non-governmental organization dedicated to developing international standards.Currently,ISO has 175 member bodies,representing 175 countries that participate in its standard development work.We have a portfolio of over 24,000 international standards,with around 100 new standards issued or existing ones revised every month.The ultimate goal of our standardization work is to support the achievement of the United Nations Sustainable Development Goals(SDGs).Every standard we develop and every task I undertake in my role contributes to these global objectives.
文摘In this paper,we propose a novel probabilistic method for predicting the undrained bearing capacity of spatially variable soils.Our approach combines a Gaussian process regression(GPR)-based surrogate model with random cell-based smoothed finite analysis.The Gaussian process emulator(GPE)serves as a statistical tool for making predictions from a data set.First,we validate the accuracy and efficiency of kinematic limit analysis using the cell-based smoothed finite element method(CS-FEM)against the standard finite element method(FEM)and edge-based smoothed FEM(ES-FEM).The numerical results demonstrate that the CS-FEM framework surpasses traditional numerical approaches,establishing its reliability in computing collapse loads.Subsequently,we conduct several hundred simulations to develop a surrogate model for predicting the undrained bearing capacity of shallow foundations.By utilizing various kernel functions,we enhance the accuracy of the GPE in these predictions.This method offers a practical and efficient solution,effectively addressing multiple uncertainties.Numerical results indicate that the GPE significantly boosts computational efficiency,achieving satisfactory outcomes within minutes compared to the days required for conventional simulations.Notably,the mean absolute percentage error(MAPE)decreases from 2.38%to 1.82%for rough foundations when employing Matérn and rational quadratic kernel functions,respectively.Additionally,combining different kernel functions further enhances the accuracy of collapse load predictions.
