Owing to their rolling friction,two-dimensional piston pumps are highly suitable as power components for electro-hydrostatic actuators(EHAs).These pumps are particularly advantageous for applications requiring high ef...Owing to their rolling friction,two-dimensional piston pumps are highly suitable as power components for electro-hydrostatic actuators(EHAs).These pumps are particularly advantageous for applications requiring high efficiency and reliability.However,the ambiguity surrounding the output flow characteristics of individual two-dimensional pumps poses a significant challenge in achieving precise closed-loop control of the EHA positions.To address this issue,this study established a comprehensive numerical model that included gap leakage to analyze the impact of leakage on the output flow characteristics of a two-dimensional piston pump.The validity of the numerical analysis was indirectly confirmed through meticulous measurements of the leakage and volumetric efficiency,ensuring robust results.The research findings indicated that,at lower pump speeds,leakage significantly affected the output flow rate,leading to potential inefficiencies in the system.Conversely,at higher rotational speeds,the impact of leakage was less pronounced,implying that the influence of leakage on the pump outlet flow must be carefully considered and managed for EHAs to perform position servo control.Additionally,the research demonstrates that two-dimensional motion does not have a unique or additional effect on pump leakage,thus simplifying the design considerations.Finally,the study concluded that maintaining an oil-filled leakage environment is beneficial because it helps reduce the impact of leakage and enhances the overall volumetric efficiency of the pump system.展开更多
The porous structure in pomelo peel is believed to be responsible for the protection of its fruit from damage during the free falling from a tree.The quantitative understanding of the relationship between the deformat...The porous structure in pomelo peel is believed to be responsible for the protection of its fruit from damage during the free falling from a tree.The quantitative understanding of the relationship between the deformation behavior and the porous structure could pave the way for the design of porous structures for efficient energy absorption.Here,a universal feature of pore distribution in pomelo peels along the radial direction is extracted from three varieties of pomelos,which shows strong correlation to the deformation behavior of the peels under compression.Guided by the porous design found in pomelo peels,porous polyether-ether-ketone(PEEK)cube is additively manufactured and possesses the highest ability to absorb energy during compression as compared to the non-pomelo-inspired geometries,which is further confirmed by the finite element simulation.The nature-optimized porous structure revealed here could guide the design of lightweight and high-energy-dissipating materials/devices.展开更多
Cornus officinalis,a medicinal and edible plant known for its liver-nourishing properties,has shown promise in inhibiting the activation of hepatic stellate cells(HSCs),crucial indicators of hepatic fibrosis,especiall...Cornus officinalis,a medicinal and edible plant known for its liver-nourishing properties,has shown promise in inhibiting the activation of hepatic stellate cells(HSCs),crucial indicators of hepatic fibrosis,especially when processed by high pressure wine steaming(HPWS).Herein,this study aims to investigate the regulatory effects of cornus officinalis,both in its raw and HPWS forms,on inflammation and apoptosis in liver fibrosis and their underlying mechanisms.In vivo liver fibrosis models were established by subcutaneous injection of CCl4,while in vitro HSCs were exposed to transforming growth factor-b(TGF-b).These findings demonstrated that cornus officinalis with HPWS conspicuously ameliorated histopathological injury,reduced the release of proinflammatory factors,and decreased collagen deposition in CCl4-induced rats compared to its raw form.Utilizing ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometer(UHPLC-QTOF-MS)combined with network analysis,we identified that the pharmacological effects of the changed components of cornus officinalis before and after HPWS,primarily centered on the adenosine phosphate(AMP)-activated protein kinase(AMPK)pathway.Of note,cornus officinalis activated AMPK and sirtuin 3(SIRT3),promoting the apoptosis of activated HSCs through the caspase cascade by regulating caspase3,caspase6 and caspase9.small interfering RNA(siRNA)experiments showed that cornus officinalis could regulate AMPK activity and its mediated-apoptosis through SIRT3.In conclusion,cornus officinalis exhibited the ability to reduce inflammation and apoptosis,with the SIRT3-AMPK signaling pathway identified as a potential mechanism underlying the synergistic effect of cornus officinalis with HPWS on anti-liver fibrosis.展开更多
The manufacturing of spiral groove structure of two-dimensional valve(2D valve)feedback mechanism has shortcomings of both high cost and time-consuming.This paper presents a novel configuration of rotary electro-mecha...The manufacturing of spiral groove structure of two-dimensional valve(2D valve)feedback mechanism has shortcomings of both high cost and time-consuming.This paper presents a novel configuration of rotary electro-mechanical converter with negative feedback mechanism(REMC-NFM)in order to replace the feedback mechanism of spiral groove and thus reduce cost of valve manufacturing.In order to rapidly and quantitative evaluate the driving and feedback performance of the REMC-NFM,an analytical model taking leakage flux,edge effect and permeability nonlinearity into account is formulated based on the equivalent magnetic circuit approach.Then the model is properly simplified in order to obtain the optimal pitch angle.FEM simulation is used to study the influence of crucial parameters on the performance of REMC-NFM.A prototype of REMC-NFM is designed and machined,and an exclusive experimental platform is built.The torque-angle characteristics,torque-displacement characteristics,and magnetic flux density in the working air gap with different excitation currents are measured.The experimental results are in good agreement with the analytical and FEM simulated results,which verifies the correctness of the analytical model.For torque-angle characteristics,the overall torque increases with both current and rotation angle,which reaches about 0.48 N·m with 1.5 A and 1.5°.While for torque-displacement characteristics,the overall torque increases with current yet decrease with armature displacement due to the negative feedback mechanism,which is about 0.16 N·m with 1.5 A and 0.8 mm.Besides,experimental results of conventional torque motor are compared with counterparts of REMC-NFM in order to validate the simplified model.The research indicates that the REMC-NFM can be potentially used as the electro-mechanical converter for 2D valves in civil servo areas.展开更多
We consider a general framework of optimal contract design under the heterogeneity and short-termism of agents.Our research shows that the optimal contract must weigh the agent's information rent,incentive cost,an...We consider a general framework of optimal contract design under the heterogeneity and short-termism of agents.Our research shows that the optimal contract must weigh the agent's information rent,incentive cost,and benefit to overcome the contract's adverse selection and moral hazards.Agents with higher moral levels were more likely to choose higher effort and lower manipulation.Simultaneously,the principal offers lower incentives and receives more significant payoff.We also extend our model to investigate the benefits of Bayesian learning.Furthermore,we compare the principal's returns in general and learning models and find that the learning contract can bring more profit to the principal。展开更多
Taxifolin(TAX)is a natural compound known for its liver protection effect,but the mechanism remains unknown.Phosphorylated proteomics analyses discovered that the phosphorylation level of NDRG1 at T328 was a key event...Taxifolin(TAX)is a natural compound known for its liver protection effect,but the mechanism remains unknown.Phosphorylated proteomics analyses discovered that the phosphorylation level of NDRG1 at T328 was a key event of TAX-improved liver fibrosis.We established models with NDRG1 knockout(KO)in vivo and in vitro,demonstrating that NDRG1 KO attenuated the development of hepatocyte injury,and combining NDRG1 KO and TAX administration did not result in a reduction in protection against liver injury.Cellular thermal shift assay and surface plasma resonance analysis showed that TAX directly binds to NDRG1 rather than its upstream kinase,subsequently demonstrating that TAX regulated phosphorylation of NDRG1 at T328 through binding to its C289 site.NDRG1 T328A(phosphorylated mutation)and T328E(mimic phosphorylation)in vivo and in vitro confirmed that pNDRG1T328 exacerbates hepatocyte injury along with DNA damage,inflammatory response,and apoptosis,thereby contributing to hepatic stellate cells(HSCs)activation.In contrast,TAX can inhibit the above pathological abnormalities and block hepatocyte injury-triggered HSCs activation and fibrosis.Overall,TAX is a potent liver protection drug primarily targeting NDRG1 and inhibiting pNDRG1T328 in hepatocytes.展开更多
Under the bounded rationality assumption,a principal rarely provides an optimal contract to an agent.Learning from others is one way to improve such a contract.This paper studies the efficiency of social network learn...Under the bounded rationality assumption,a principal rarely provides an optimal contract to an agent.Learning from others is one way to improve such a contract.This paper studies the efficiency of social network learning(SNL)in the principal–agent framework.We first introduce the Cobb-Douglas production function into the classic Holmstrom and Milgrom(1987)model with a constant relative risk-averse agent and work out the theoretically optimal contract.Algorithms are then designed to model the SNL process based on profit gaps between contracts in a network of principals.Considering the uncertainty of the agent's labor output,we find that the principals can reach a consensus that tends to result in overcompensation compared to the optimal contract.Then,this study examines how network attributes and model parameters impact learning efficiency and posits several summative hypotheses.The simulation results validate these hypotheses,and we discuss the relevant economic implications of the observed changes in SNL efficiency.展开更多
Given the differences between cities in the United States and China,and the changing structure of Chinese cities,this paper examines the viability of some basic predictions of the Muth-Mills model of urban spatial str...Given the differences between cities in the United States and China,and the changing structure of Chinese cities,this paper examines the viability of some basic predictions of the Muth-Mills model of urban spatial structure for modern cities in China,using data for the year 2010. Chinese cities are experiencing rapid motorization and road construction over the last two decades,so we have tried to use different measurements for commuting cost in these cities to estimate the empirical model,and concluded that most results support the Muth-Mills assertion. The elasticities of the urban spatial size with respect to the signifi cant variables are discussed,comparing to those for cities in the United States. The results we obtain from both theoretical and empirical analyses can further increase our understanding on the model as a tool for a policy analysis on cities in China.展开更多
In theory,there is a close interactive relationship between urbanization and motorization. This paper investigates the interactive relationship between urbanization and motorization in China after its reform and openi...In theory,there is a close interactive relationship between urbanization and motorization. This paper investigates the interactive relationship between urbanization and motorization in China after its reform and opening-up by using the urbanization and motorization data during the period 1985 – 2010. The research fi nds that during the period 1985 – 2000,there indeed was a long-run stable interactive relationship between urbanization and motorization in China. It proves that motorization has a time lagged impact on urbanization,whereas urbanization alone has less effect on motorization growth than the infl uence of motorization growth on the rapid growth of urbanization.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.52205072).
文摘Owing to their rolling friction,two-dimensional piston pumps are highly suitable as power components for electro-hydrostatic actuators(EHAs).These pumps are particularly advantageous for applications requiring high efficiency and reliability.However,the ambiguity surrounding the output flow characteristics of individual two-dimensional pumps poses a significant challenge in achieving precise closed-loop control of the EHA positions.To address this issue,this study established a comprehensive numerical model that included gap leakage to analyze the impact of leakage on the output flow characteristics of a two-dimensional piston pump.The validity of the numerical analysis was indirectly confirmed through meticulous measurements of the leakage and volumetric efficiency,ensuring robust results.The research findings indicated that,at lower pump speeds,leakage significantly affected the output flow rate,leading to potential inefficiencies in the system.Conversely,at higher rotational speeds,the impact of leakage was less pronounced,implying that the influence of leakage on the pump outlet flow must be carefully considered and managed for EHAs to perform position servo control.Additionally,the research demonstrates that two-dimensional motion does not have a unique or additional effect on pump leakage,thus simplifying the design considerations.Finally,the study concluded that maintaining an oil-filled leakage environment is beneficial because it helps reduce the impact of leakage and enhances the overall volumetric efficiency of the pump system.
基金supported by the National Key R&DProgram of China(2018YFB1105100)National Natural Science Foundation of China(51973165).
文摘The porous structure in pomelo peel is believed to be responsible for the protection of its fruit from damage during the free falling from a tree.The quantitative understanding of the relationship between the deformation behavior and the porous structure could pave the way for the design of porous structures for efficient energy absorption.Here,a universal feature of pore distribution in pomelo peels along the radial direction is extracted from three varieties of pomelos,which shows strong correlation to the deformation behavior of the peels under compression.Guided by the porous design found in pomelo peels,porous polyether-ether-ketone(PEEK)cube is additively manufactured and possesses the highest ability to absorb energy during compression as compared to the non-pomelo-inspired geometries,which is further confirmed by the finite element simulation.The nature-optimized porous structure revealed here could guide the design of lightweight and high-energy-dissipating materials/devices.
基金supported by the National Natural Science Foundation of China(Grant Nos.:82104394 and 81973481)the Natural Science Foundation of Zhejiang Province(Grant Nos.:LY23H280008 and LQ23H280004)+2 种基金Zhejiang Province Traditional Chinese Medicine Science and Technology Project(Grant No.:2022ZQ033)Zhejiang Chinese Medicine University UniversityLevel Talent Special Project(Grant No.:2021ZR06)Zhejiang Province Postdoctoral Research Project(Grant No.:ZJ2022057).
文摘Cornus officinalis,a medicinal and edible plant known for its liver-nourishing properties,has shown promise in inhibiting the activation of hepatic stellate cells(HSCs),crucial indicators of hepatic fibrosis,especially when processed by high pressure wine steaming(HPWS).Herein,this study aims to investigate the regulatory effects of cornus officinalis,both in its raw and HPWS forms,on inflammation and apoptosis in liver fibrosis and their underlying mechanisms.In vivo liver fibrosis models were established by subcutaneous injection of CCl4,while in vitro HSCs were exposed to transforming growth factor-b(TGF-b).These findings demonstrated that cornus officinalis with HPWS conspicuously ameliorated histopathological injury,reduced the release of proinflammatory factors,and decreased collagen deposition in CCl4-induced rats compared to its raw form.Utilizing ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometer(UHPLC-QTOF-MS)combined with network analysis,we identified that the pharmacological effects of the changed components of cornus officinalis before and after HPWS,primarily centered on the adenosine phosphate(AMP)-activated protein kinase(AMPK)pathway.Of note,cornus officinalis activated AMPK and sirtuin 3(SIRT3),promoting the apoptosis of activated HSCs through the caspase cascade by regulating caspase3,caspase6 and caspase9.small interfering RNA(siRNA)experiments showed that cornus officinalis could regulate AMPK activity and its mediated-apoptosis through SIRT3.In conclusion,cornus officinalis exhibited the ability to reduce inflammation and apoptosis,with the SIRT3-AMPK signaling pathway identified as a potential mechanism underlying the synergistic effect of cornus officinalis with HPWS on anti-liver fibrosis.
基金National Natural Science Foundation of China(Grant Nos.51975524,51405443)National Key Research and Development Program of China(Grant No.2019YFB2005200).
文摘The manufacturing of spiral groove structure of two-dimensional valve(2D valve)feedback mechanism has shortcomings of both high cost and time-consuming.This paper presents a novel configuration of rotary electro-mechanical converter with negative feedback mechanism(REMC-NFM)in order to replace the feedback mechanism of spiral groove and thus reduce cost of valve manufacturing.In order to rapidly and quantitative evaluate the driving and feedback performance of the REMC-NFM,an analytical model taking leakage flux,edge effect and permeability nonlinearity into account is formulated based on the equivalent magnetic circuit approach.Then the model is properly simplified in order to obtain the optimal pitch angle.FEM simulation is used to study the influence of crucial parameters on the performance of REMC-NFM.A prototype of REMC-NFM is designed and machined,and an exclusive experimental platform is built.The torque-angle characteristics,torque-displacement characteristics,and magnetic flux density in the working air gap with different excitation currents are measured.The experimental results are in good agreement with the analytical and FEM simulated results,which verifies the correctness of the analytical model.For torque-angle characteristics,the overall torque increases with both current and rotation angle,which reaches about 0.48 N·m with 1.5 A and 1.5°.While for torque-displacement characteristics,the overall torque increases with current yet decrease with armature displacement due to the negative feedback mechanism,which is about 0.16 N·m with 1.5 A and 0.8 mm.Besides,experimental results of conventional torque motor are compared with counterparts of REMC-NFM in order to validate the simplified model.The research indicates that the REMC-NFM can be potentially used as the electro-mechanical converter for 2D valves in civil servo areas.
基金supported by the National Natural Science Foundation of China(Grant numbers:71701164,71671142,and 72271249).
文摘We consider a general framework of optimal contract design under the heterogeneity and short-termism of agents.Our research shows that the optimal contract must weigh the agent's information rent,incentive cost,and benefit to overcome the contract's adverse selection and moral hazards.Agents with higher moral levels were more likely to choose higher effort and lower manipulation.Simultaneously,the principal offers lower incentives and receives more significant payoff.We also extend our model to investigate the benefits of Bayesian learning.Furthermore,we compare the principal's returns in general and learning models and find that the learning contract can bring more profit to the principal。
基金the National Natural Science Foundation of China(No.82104394)“Pioneer”and“Leading Goose”R&D Program of Zhejiang(No.2024C03102)+1 种基金the Natural Science Foundation of Zhejiang Province(No.LY23H280008,China)Zhejiang Chinese Medicine University universitylevel talent special project(No.2024JKZKTS09,China).
文摘Taxifolin(TAX)is a natural compound known for its liver protection effect,but the mechanism remains unknown.Phosphorylated proteomics analyses discovered that the phosphorylation level of NDRG1 at T328 was a key event of TAX-improved liver fibrosis.We established models with NDRG1 knockout(KO)in vivo and in vitro,demonstrating that NDRG1 KO attenuated the development of hepatocyte injury,and combining NDRG1 KO and TAX administration did not result in a reduction in protection against liver injury.Cellular thermal shift assay and surface plasma resonance analysis showed that TAX directly binds to NDRG1 rather than its upstream kinase,subsequently demonstrating that TAX regulated phosphorylation of NDRG1 at T328 through binding to its C289 site.NDRG1 T328A(phosphorylated mutation)and T328E(mimic phosphorylation)in vivo and in vitro confirmed that pNDRG1T328 exacerbates hepatocyte injury along with DNA damage,inflammatory response,and apoptosis,thereby contributing to hepatic stellate cells(HSCs)activation.In contrast,TAX can inhibit the above pathological abnormalities and block hepatocyte injury-triggered HSCs activation and fibrosis.Overall,TAX is a potent liver protection drug primarily targeting NDRG1 and inhibiting pNDRG1T328 in hepatocytes.
基金the support of the National Natural Science Foundation of China(Grant number:72371202)the Fundamental Research Funds for the Central Universities(Grant number:JBK2207051).
文摘Under the bounded rationality assumption,a principal rarely provides an optimal contract to an agent.Learning from others is one way to improve such a contract.This paper studies the efficiency of social network learning(SNL)in the principal–agent framework.We first introduce the Cobb-Douglas production function into the classic Holmstrom and Milgrom(1987)model with a constant relative risk-averse agent and work out the theoretically optimal contract.Algorithms are then designed to model the SNL process based on profit gaps between contracts in a network of principals.Considering the uncertainty of the agent's labor output,we find that the principals can reach a consensus that tends to result in overcompensation compared to the optimal contract.Then,this study examines how network attributes and model parameters impact learning efficiency and posits several summative hypotheses.The simulation results validate these hypotheses,and we discuss the relevant economic implications of the observed changes in SNL efficiency.
基金partly supported by the National Natural Science Foundation of China(Grant 51008002)the Natural Science Foundation of Guangdong Province(S2012040007176)+2 种基金the Research Fund for the State Key Laboratory of Subtropical Building Science(Grant 2011KB20)the Research Fund for the Harbin Institute of Technology(Grants HIT.NSRIF.2013100 and HIT.NSFIR.2011126)the Peking University-Lincoln Institute Center for Urban Development and Land Policy(DS20120901).
文摘Given the differences between cities in the United States and China,and the changing structure of Chinese cities,this paper examines the viability of some basic predictions of the Muth-Mills model of urban spatial structure for modern cities in China,using data for the year 2010. Chinese cities are experiencing rapid motorization and road construction over the last two decades,so we have tried to use different measurements for commuting cost in these cities to estimate the empirical model,and concluded that most results support the Muth-Mills assertion. The elasticities of the urban spatial size with respect to the signifi cant variables are discussed,comparing to those for cities in the United States. The results we obtain from both theoretical and empirical analyses can further increase our understanding on the model as a tool for a policy analysis on cities in China.
基金supported by the National Science Foundation of China(Grant 51008002)the State Key Laboratory of Subtropical Building Science South China University of Technology(Grant 2011KB20)+1 种基金the Research Fund of Harbin Institute of Technology(Grant HIT.NSRIF.2013100 and HIT.NSFIR.2011126)the Peking University–Lincoln Institute Center for Urban Development and Land Policy(DS20120901).
文摘In theory,there is a close interactive relationship between urbanization and motorization. This paper investigates the interactive relationship between urbanization and motorization in China after its reform and opening-up by using the urbanization and motorization data during the period 1985 – 2010. The research fi nds that during the period 1985 – 2000,there indeed was a long-run stable interactive relationship between urbanization and motorization in China. It proves that motorization has a time lagged impact on urbanization,whereas urbanization alone has less effect on motorization growth than the infl uence of motorization growth on the rapid growth of urbanization.
