As a vessel navigates at high speeds in waves,considerable pitching motion can result in the discomfort of passengers.In this study is proposed a ride control system consisting of dual T-foils to generate a larger rig...As a vessel navigates at high speeds in waves,considerable pitching motion can result in the discomfort of passengers.In this study is proposed a ride control system consisting of dual T-foils to generate a larger righting moment than a common single T-foil system.One T-foil is mounted at the bow,and the other at the stern.Accordingly,different control strategies for dual T-foils were proposed To verify the stratigies,a model experiment was conducted in the Towing Tank,Dalian Unievrsity of Technology.The optimal control signal was determined by comparing the pitch responses,heave responses,bow accelerations,and stern accelerations of a vessel in regular waves.In addition,the control strategy for the best motion-reduction effect was investigated.The optimized dual T-foil system provides a 34%reduction in pitch motion.展开更多
The flutter of a hydrofoil can cause structural damage and failure,which is a dangerous situation that must be avoided.In this work,based on computational fluid dynamics and structural finite element methods,a co-simu...The flutter of a hydrofoil can cause structural damage and failure,which is a dangerous situation that must be avoided.In this work,based on computational fluid dynamics and structural finite element methods,a co-simulation framework for the flow-induced vibration of hydrofoil was established to realize fluid-structure interaction.Numerical simulation research was conducted on the flow-induced vibration characteristics of rigid hydrofoil with 2-DOF under uniform flow,and the heave and pitch vibration responses of hydrofoil were simulated.The purpose is to capture the instability of hydrofoil vibration and evaluate the influence of natural frequency ratio and inertia radius on vibration state to avoid the generation of flutter.The results indicate that when the inflow velocity increases to a certain critical value,the hydrofoil will enter the flutter critical state without amplitude attenuation.The attack angle of a hydrofoil has a significant impact on the vibration amplitude of heave and pitch.Additionally,the natural frequency ratio and inertia radius of the hydrofoil significantly affect the critical velocity of the flutter.Adjusting the natural frequency ratio by reducing the vertical stiffness or increasing the pitch stiffness can move the vibration from a critical state to a convergent state.展开更多
Background Synthesizing dance motions to match musical inputs is a significant challenge in animation research.Compared to functional human motions,such as locomotion,dance motions are creative and artistic,often infl...Background Synthesizing dance motions to match musical inputs is a significant challenge in animation research.Compared to functional human motions,such as locomotion,dance motions are creative and artistic,often influenced by music,and can be independent body language expressions.Dance choreography requires motion content to follow a general dance genre,whereas dance performances under musical influence are infused with diverse impromptu motion styles.Considering the high expressiveness and variations in space and time,providing accessible and effective user control for tuning dance motion styles remains an open problem.Methods In this study,we present a hierarchical framework that decouples the dance synthesis task into independent modules.We use a high-level choreography module built as a Transformer-based sequence model to predict the long-term structure of a dance genre and a low-level realization module that implements dance stylization and synchronization to match the musical input or user preferences.This novel framework allows the individual modules to be trained separately.Because of the decoupling,dance composition can fully utilize existing high-quality dance datasets that do not have musical accompaniments,and the dance implementation can conveniently incorporate user controls and edit motions through a decoder network.Each module is replaceable at runtime,which adds flexibility to the synthesis of dance sequences.Results Synthesized results demonstrate that our framework generates high-quality diverse dance motions that are well adapted to varying musical conditions and user controls.展开更多
Few studies have predicted indoor ozone(O_(3))levels using machine learning methods.This study aimed to predict hourly indoor O_(3) concentrations using easily accessible predictors and a machine learning algorithm.We...Few studies have predicted indoor ozone(O_(3))levels using machine learning methods.This study aimed to predict hourly indoor O_(3) concentrations using easily accessible predictors and a machine learning algorithm.We took measurements of indoor O_(3) concentrations based on low-cost sensors in 18 cities in China,along with ambient O_(3) concentration,meteorological factors,and a binary window status indicator as a proxy for ventilation behaviour,to establish random forest models.The results showed that including window status as a predictor improved model performance,with the cross-validation R^(2) increasing from 0.80 to 0.83 and the root mean square error(RMSE)decreasing from 7.89 to 7.21 ppb,highlighting the importance of considering ventilation behavior in enhancing model accuracy.The model also effectively captured hourly variations in indoor O_(3),revealing that indoor O_(3) concentrations were consistently lower and more stable than outdoor levels.These differences suggest that relying solely on ambient data may misrepresent true personal exposure,underscoring the need to incorporate indoor exposure in assessments.This is the first study to apply easily accessible variables and machine learning methods for indoor O_(3) prediction at a large geographic spatial scale,showing promising potential for improving the accuracy of exposure assessments in epidemiological studies.展开更多
The interaction between ultrasound and the air-liquid interface is widely involved in sonar communication,medical imaging,acoustic detection,etc.In this work,we report an intriguing bubbling phenomenon occurring at th...The interaction between ultrasound and the air-liquid interface is widely involved in sonar communication,medical imaging,acoustic detection,etc.In this work,we report an intriguing bubbling phenomenon occurring at the liquid surface exposed to acoustic radiation.The phenomenon can be robustly triggered once the distance between the liquid surface and the acoustic probe is adjusted to multiples of half sound wavelength.It is clarified that the bubbling is attributed to the Helmholtz resonance of the liquid concavity caused by the acoustic radiation force.The sizes of the final obtained bubbles show a universal scaling law with acoustic Bond number and acoustic Reynolds number:R≈λ·Bo_(a)·(Re_(a))^(1/2),which is independent of the types of liquids.Moreover,it was found that the bubbling phenomenon showed a significantly enhanced particle absorption ability,thus shedding light on the development of solid filter-free air purification techniques.展开更多
This study seeks to elucidate the reduction in brain functional network connectivity during exercise compared to rest,utilizing graph theory techniques to analyze data from resting and movement phases across various e...This study seeks to elucidate the reduction in brain functional network connectivity during exercise compared to rest,utilizing graph theory techniques to analyze data from resting and movement phases across various exercise modalities.This study employed a graph theory approach to examine differences in brain network functions across various motor phases.The participants engaged in upper limb rehabilitation exercises,including passive,active,and resistance exercises,while functional near-infrared spectroscopy was used to monitor the motor-related cortex.Functional connectivity was reduced during exercise compared with rest,particularly during active and resistance exercises.Small-world network properties did not vary significantly between the two phases,although these properties were higher during movement under conditions of high sparsity.Both global and local efficiencies remained largely unchanged between phases.However,local efficiency increased during the active and resistance exercises in the movement phase.Node efficiency analysis indicated that the motor and supplementary motor areas played critical roles during exercise,with the movement phase exhibiting shorter path lengths.While the overall brain functional connectivity decreased during exercise,there was an improve-ment in the efficiency of specific brain nodes,suggesting a network mechanism that supports movement execution.During exercise,there was a decrease in whole-brain functional connectivity,yet an enhancement in brain efficiency was observed.This enhancement in functionality of specific nodes may signify the network mechanism responsible for movement execution.展开更多
Gravity-induced drainage is one of the main destabilizing mechanisms for soap bubbles and foams.Here we show that solely through acoustic levitation without introducing any chemical stabilizers,liquid drainage in the ...Gravity-induced drainage is one of the main destabilizing mechanisms for soap bubbles and foams.Here we show that solely through acoustic levitation without introducing any chemical stabilizers,liquid drainage in the bubble film can be completely inhibited,therefore leading to a significant enhancement of bubble lifetime by more than two orders of magnitude and enabling the bubble to survive puncturing by a needle.Based on sound simulation and force analysis,it has been found that acoustic radiation force,exerted on both the inner and outer surfaces of the levitated bubble,acts in opposite directions,thus providing a squeezing effect to the bubble film.The hydrostatic pressure that induces drainage has been balanced by the acoustic radiation pressure exerted on both sides of the film,which is at the origin of the sound stabilization mechanism.This study provides new insights into the interplay between sound and soap bubbles or films,thus stimulating a wide range of fundamental research concerning bubble films and expanding their applications in bio/chemical reactors.展开更多
Cultured meat technology has rapidly advanced in recent years,offering promising prospects.However,a major challenge in industrializing this process is the procurement and expansion of seed cells,which frequently lose...Cultured meat technology has rapidly advanced in recent years,offering promising prospects.However,a major challenge in industrializing this process is the procurement and expansion of seed cells,which frequently lose their proliferative potential during in vitro culture.In this study,high-purity bovine muscle stem cells were isolated using fluorescence-activated cell sorting,achieving a pax7 positivity rate of 90%.These cells demonstrated standard proliferation and differentiation capabilities in vitro.However,long-term culture led to decreased proliferation and differentiation capacities,as well as an accumulation of reactive oxygen species.To restore cellular function,we investigated the effects of Trolox(6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid),a powerful antioxidant.Treatment with 50μM Trolox effectively reversed the decline in bovine muscle stem cells proliferation,decreased reactive oxygen species levels,and preserved cell stemness during extended culture.These results provide a foundation for muscle seed cells acquisition and preservation,improving their viability and functionality in vitro.展开更多
基金supported by Shenzhen 2022 Key Project for Technological Research(Grant Number JSGG20220831110803006)key technology research and demonstration project of 10 MW deep-sea floating offshore wind turbine(DTGD-2023-10174)key technology research task of floating offshore combined wind and wave power generation and MIIT program for Floating VAWT.
文摘As a vessel navigates at high speeds in waves,considerable pitching motion can result in the discomfort of passengers.In this study is proposed a ride control system consisting of dual T-foils to generate a larger righting moment than a common single T-foil system.One T-foil is mounted at the bow,and the other at the stern.Accordingly,different control strategies for dual T-foils were proposed To verify the stratigies,a model experiment was conducted in the Towing Tank,Dalian Unievrsity of Technology.The optimal control signal was determined by comparing the pitch responses,heave responses,bow accelerations,and stern accelerations of a vessel in regular waves.In addition,the control strategy for the best motion-reduction effect was investigated.The optimized dual T-foil system provides a 34%reduction in pitch motion.
基金supported by the National Natural Science Foundation of China(Grant No.52001043)the Chinese Academy of Sciences Youth Innovation Promotion Association(Grant No.2020205)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.DUT22GF202 and DUT20TD108)Liaoning Revitalization Talents Program(Grant No.XLYC1908027).
文摘The flutter of a hydrofoil can cause structural damage and failure,which is a dangerous situation that must be avoided.In this work,based on computational fluid dynamics and structural finite element methods,a co-simulation framework for the flow-induced vibration of hydrofoil was established to realize fluid-structure interaction.Numerical simulation research was conducted on the flow-induced vibration characteristics of rigid hydrofoil with 2-DOF under uniform flow,and the heave and pitch vibration responses of hydrofoil were simulated.The purpose is to capture the instability of hydrofoil vibration and evaluate the influence of natural frequency ratio and inertia radius on vibration state to avoid the generation of flutter.The results indicate that when the inflow velocity increases to a certain critical value,the hydrofoil will enter the flutter critical state without amplitude attenuation.The attack angle of a hydrofoil has a significant impact on the vibration amplitude of heave and pitch.Additionally,the natural frequency ratio and inertia radius of the hydrofoil significantly affect the critical velocity of the flutter.Adjusting the natural frequency ratio by reducing the vertical stiffness or increasing the pitch stiffness can move the vibration from a critical state to a convergent state.
基金Supported by Startup Fund 20019495,McMaster University。
文摘Background Synthesizing dance motions to match musical inputs is a significant challenge in animation research.Compared to functional human motions,such as locomotion,dance motions are creative and artistic,often influenced by music,and can be independent body language expressions.Dance choreography requires motion content to follow a general dance genre,whereas dance performances under musical influence are infused with diverse impromptu motion styles.Considering the high expressiveness and variations in space and time,providing accessible and effective user control for tuning dance motion styles remains an open problem.Methods In this study,we present a hierarchical framework that decouples the dance synthesis task into independent modules.We use a high-level choreography module built as a Transformer-based sequence model to predict the long-term structure of a dance genre and a low-level realization module that implements dance stylization and synchronization to match the musical input or user preferences.This novel framework allows the individual modules to be trained separately.Because of the decoupling,dance composition can fully utilize existing high-quality dance datasets that do not have musical accompaniments,and the dance implementation can conveniently incorporate user controls and edit motions through a decoder network.Each module is replaceable at runtime,which adds flexibility to the synthesis of dance sequences.Results Synthesized results demonstrate that our framework generates high-quality diverse dance motions that are well adapted to varying musical conditions and user controls.
基金funded by the National Natural Science Foundation of China(82003413 and 82030103).
文摘Few studies have predicted indoor ozone(O_(3))levels using machine learning methods.This study aimed to predict hourly indoor O_(3) concentrations using easily accessible predictors and a machine learning algorithm.We took measurements of indoor O_(3) concentrations based on low-cost sensors in 18 cities in China,along with ambient O_(3) concentration,meteorological factors,and a binary window status indicator as a proxy for ventilation behaviour,to establish random forest models.The results showed that including window status as a predictor improved model performance,with the cross-validation R^(2) increasing from 0.80 to 0.83 and the root mean square error(RMSE)decreasing from 7.89 to 7.21 ppb,highlighting the importance of considering ventilation behavior in enhancing model accuracy.The model also effectively captured hourly variations in indoor O_(3),revealing that indoor O_(3) concentrations were consistently lower and more stable than outdoor levels.These differences suggest that relying solely on ambient data may misrepresent true personal exposure,underscoring the need to incorporate indoor exposure in assessments.This is the first study to apply easily accessible variables and machine learning methods for indoor O_(3) prediction at a large geographic spatial scale,showing promising potential for improving the accuracy of exposure assessments in epidemiological studies.
基金supported by the National Natural Science Foundation of China (Grant Nos. 12272314, and 11972303)。
文摘The interaction between ultrasound and the air-liquid interface is widely involved in sonar communication,medical imaging,acoustic detection,etc.In this work,we report an intriguing bubbling phenomenon occurring at the liquid surface exposed to acoustic radiation.The phenomenon can be robustly triggered once the distance between the liquid surface and the acoustic probe is adjusted to multiples of half sound wavelength.It is clarified that the bubbling is attributed to the Helmholtz resonance of the liquid concavity caused by the acoustic radiation force.The sizes of the final obtained bubbles show a universal scaling law with acoustic Bond number and acoustic Reynolds number:R≈λ·Bo_(a)·(Re_(a))^(1/2),which is independent of the types of liquids.Moreover,it was found that the bubbling phenomenon showed a significantly enhanced particle absorption ability,thus shedding light on the development of solid filter-free air purification techniques.
基金The National Key R&D Program of China(Grant Number:2023YFC3603700).
文摘This study seeks to elucidate the reduction in brain functional network connectivity during exercise compared to rest,utilizing graph theory techniques to analyze data from resting and movement phases across various exercise modalities.This study employed a graph theory approach to examine differences in brain network functions across various motor phases.The participants engaged in upper limb rehabilitation exercises,including passive,active,and resistance exercises,while functional near-infrared spectroscopy was used to monitor the motor-related cortex.Functional connectivity was reduced during exercise compared with rest,particularly during active and resistance exercises.Small-world network properties did not vary significantly between the two phases,although these properties were higher during movement under conditions of high sparsity.Both global and local efficiencies remained largely unchanged between phases.However,local efficiency increased during the active and resistance exercises in the movement phase.Node efficiency analysis indicated that the motor and supplementary motor areas played critical roles during exercise,with the movement phase exhibiting shorter path lengths.While the overall brain functional connectivity decreased during exercise,there was an improve-ment in the efficiency of specific brain nodes,suggesting a network mechanism that supports movement execution.During exercise,there was a decrease in whole-brain functional connectivity,yet an enhancement in brain efficiency was observed.This enhancement in functionality of specific nodes may signify the network mechanism responsible for movement execution.
基金the National Natural Science Foundation of China(Grant Nos.12272314,11972303)the Opening Fund of the State Key Laboratory of Nonlinear Mechanics for supporting this research financially.
文摘Gravity-induced drainage is one of the main destabilizing mechanisms for soap bubbles and foams.Here we show that solely through acoustic levitation without introducing any chemical stabilizers,liquid drainage in the bubble film can be completely inhibited,therefore leading to a significant enhancement of bubble lifetime by more than two orders of magnitude and enabling the bubble to survive puncturing by a needle.Based on sound simulation and force analysis,it has been found that acoustic radiation force,exerted on both the inner and outer surfaces of the levitated bubble,acts in opposite directions,thus providing a squeezing effect to the bubble film.The hydrostatic pressure that induces drainage has been balanced by the acoustic radiation pressure exerted on both sides of the film,which is at the origin of the sound stabilization mechanism.This study provides new insights into the interplay between sound and soap bubbles or films,thus stimulating a wide range of fundamental research concerning bubble films and expanding their applications in bio/chemical reactors.
基金supported by Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)Jiangsu Synergetic Innovation Center of Meat Processing and Quality Control.
文摘Cultured meat technology has rapidly advanced in recent years,offering promising prospects.However,a major challenge in industrializing this process is the procurement and expansion of seed cells,which frequently lose their proliferative potential during in vitro culture.In this study,high-purity bovine muscle stem cells were isolated using fluorescence-activated cell sorting,achieving a pax7 positivity rate of 90%.These cells demonstrated standard proliferation and differentiation capabilities in vitro.However,long-term culture led to decreased proliferation and differentiation capacities,as well as an accumulation of reactive oxygen species.To restore cellular function,we investigated the effects of Trolox(6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid),a powerful antioxidant.Treatment with 50μM Trolox effectively reversed the decline in bovine muscle stem cells proliferation,decreased reactive oxygen species levels,and preserved cell stemness during extended culture.These results provide a foundation for muscle seed cells acquisition and preservation,improving their viability and functionality in vitro.
