传统移相控制下,无线电能传输(Wireles power transfer,WPT)系统输出功率宽范围调节时逆变器开关管易丢失零电压开关(Zero voltage switching,ZVS)状态,导致逆变器切换损耗增大甚至损坏。阶跃脉冲调制(Stepped Pulse Modulation)是一种...传统移相控制下,无线电能传输(Wireles power transfer,WPT)系统输出功率宽范围调节时逆变器开关管易丢失零电压开关(Zero voltage switching,ZVS)状态,导致逆变器切换损耗增大甚至损坏。阶跃脉冲调制(Stepped Pulse Modulation)是一种低输出纹波调制方法,可实现宽负载范围内的ZVS运行。但是,该调制方法包含有限状态机等环节,不易采用传统的机理建模访求进行建模,给控制器设计带来困难。在Simulink电路的基础上,基于数据驱动方法辨识了无线电能传输在阶跃脉冲调制下传递函数模型,并基于该模型设计内模控制器。实验表明,基于Simulink电路仿真方法获取采样数据,能够有效解决实物实验在某些场景下难以获取实验数据的难题,获得满意的辨识模型。同时,基于辨识模型设计的内模控制器,能够精确估计不同控制参数下的系统控制性能,满足了阶跃脉冲调制无线电能传输输出电压闭环控制的性能需求。展开更多
China’s“common prosperity”policy is a multidimensional pursuit of social and economic progress aimed at full realization by 2050.A CHIEVING common prosperity–prosperity that is universally shared–has been a longs...China’s“common prosperity”policy is a multidimensional pursuit of social and economic progress aimed at full realization by 2050.A CHIEVING common prosperity–prosperity that is universally shared–has been a longstanding aspiration of the Chinese government.展开更多
Sandwich functionally graded(FG)auxetic beams are extensively utilized in aerospace,automotive,and biomedical industries due to their excellent strength-toweight ratio,impact resistance,and tunable mechanical properti...Sandwich functionally graded(FG)auxetic beams are extensively utilized in aerospace,automotive,and biomedical industries due to their excellent strength-toweight ratio,impact resistance,and tunable mechanical properties.The integration of FG materials with auxetic structures enhances their adaptability in advanced engineering applications.However,understanding their dynamic behavior under external excitations is essential for optimal design and structural reliability.Nonlinear interactions in such structures pose significant challenges in vibration analysis,necessitating robust analytical methods.This study presents a closed-form solution for the nonlinear forced vibration analysis of sandwich FG auxetic beams,offering an accurate and efficient method for predicting their dynamic response.The beam consists of two FG face sheets with material properties varying through the thickness and a re-entrant honeycomb auxetic core with an adjustable Poisson's ratio.The governing nonlinear equations of motion are derived using the first-order shear deformation theory(FSDT),the modified Gibson model,and the von Kármán relations,formulated through Hamilton's principle.A closed-form solution is obtained via the Galerkin method and multiple-scale technique.The results demonstrate that FG layers enable control of the overweight and dynamic response amplitude,with positive power law indexes reducing weight.Comparisons with finite element results confirm the accuracy of the proposed formulation.展开更多
Premature yeast flocculation(PYF)has been shown to induce early and enhanced yeast flocculation and can result in a myriad of produc-tion difficulties and delays.Researchers have demonstrated that PYF is linked to fun...Premature yeast flocculation(PYF)has been shown to induce early and enhanced yeast flocculation and can result in a myriad of produc-tion difficulties and delays.Researchers have demonstrated that PYF is linked to fungal infection of barley and/or malt.Therefore,one might suspect that PYF occurrence would increase in wet climates.To test this hypothesis,a control,a PYF-positive malt sample,and two Scot-tish-sourced malt varieties were compared with a control dataset of 77 femientations.Miniature fermentation trials using the ASBC method Yeast-14 were performed on these samples.Miniature fermentation tri-als have been optimized to detect PYF-causing malt by directly meas-uring attenuation via extract readings and indirectly measuring yeast in suspension via absorbance.Nonlinear and tilted Gaussian regressions were fit to the data sets to obtain attenuation and absorbance curves,respectively.Results obtained indicated that the PYF-causing malt in-duced both early and enhanced flocculation,whereas the other three malts(including the Scottish malts)did not induce early or enhanced flocculation.All four samples were compared using the F test,and it was determined that the PYF-positive malt sample was significantly different than the other three malts(P<0.05).Using previous results from 77 miniature fermentation trials on control malts,a novel 95%prediction band was developed.This band was applied and used to identify and decisively confirm the presence of PYF-causing malt as demonstrated herein.展开更多
This paper presents a high-fidelity lumpedparameter(LP)thermal model(HF-LPTM)for permanent magnet synchronous machines(PMSMs)in electric vehicle(EV)applications,where various cooling techniques are considered,includin...This paper presents a high-fidelity lumpedparameter(LP)thermal model(HF-LPTM)for permanent magnet synchronous machines(PMSMs)in electric vehicle(EV)applications,where various cooling techniques are considered,including frame forced air/liquid cooling,oil jet cooling for endwinding,and rotor shaft cooling.To address the temperature misestimation in the LP thermal modelling due to assumptions of concentrated loss input and uniform heat flows,the developed HF-LPTM introduces two compensation thermal resistances for the winding and PM components,which are analytically derived from the multi-dimensional heat transfer equations and are robust against different load/thermal conditions.As validated by the finite element analysis method and experiments,the conventional LPTMs exhibit significant winding temperature deviations,while the proposed HF-LPTM can accurately predict both the midpoint and average temperatures.The developed HFLPTM is further used to assess the effectiveness of various cooling techniques under different scenarios,i.e.,steady-state thermal states under the rated load condition,and transient temperature profiles under city,freeway,and hybrid(city+freeway)driving cycles.Results indicate that no single cooling technique can maintain both winding and PM temperatures within safety limits.The combination of frame liquid cooling and oil jet cooling for end winding can sufficiently mitigate PMSM thermal stress in EV applications.展开更多
Belt conveyors are extensively utilized in mining and power industries.In a typical coal mine conveyor system,coal is transported over distances exceeding 2 km,involving more than 20000 idlers,which far exceeds a reas...Belt conveyors are extensively utilized in mining and power industries.In a typical coal mine conveyor system,coal is transported over distances exceeding 2 km,involving more than 20000 idlers,which far exceeds a reasonable manual inspection capacity.Given that idlers typically have a lifespan of 1-2 years,there is an urgent need for a rapid,cost-effective,and intelligent safety monitoring system.However,current embedded systems face prohibitive replacement costs,while conventional monitoring technologies suffer from inefficiency at low rotational speeds and lack systematic structural optimization frameworks for diverse idler types and parameters.To address these challenges,this paper introduces an integrated,on-site detachable self-powered idler condition monitoring system(ICMS).This system combines energy harvesting based on the magnetic modulation technology with wireless condition monitoring capabilities.Specifically,it develops a data-driven model integrating convolutional neural networks(CNNs) with genetic algorithms(GAs).The conventional testing results show that the data-driven model not only significantly accelerates the parameter response time,but also achieves a prediction accuracy of 92.95%.The in-situ experiments conducted in coal mines demonstrate the system's reliability and monitoring functionality under both no-load and fullload conditions.This research provides an innovative self-powered condition monitoring solution and develops an efficient data-driven model,offering feasible online monitoring approaches for smart mine construction.展开更多
Cyber-physical systems(CPSs)are regarded as the backbone of the fourth industrial revolution,in which communication,physical processes,and computer technology are integrated.In modern industrial systems,CPSs are widel...Cyber-physical systems(CPSs)are regarded as the backbone of the fourth industrial revolution,in which communication,physical processes,and computer technology are integrated.In modern industrial systems,CPSs are widely utilized across various domains,such as smart grids,smart healthcare systems,smart vehicles,and smart manufacturing,among others.Due to their unique spatial distribution,CPSs are highly vulnerable to cyber-attacks,which may result in severe performance degradation and even system instability.Consequently,the security concerns of CPSs have attracted significant attention in recent years.In this paper,a comprehensive survey on the security issues of CPSs under cyber-attacks is provided.Firstly,mathematical descriptions of various types of cyberattacks are introduced in detail.Secondly,two types of secure estimation and control processing schemes,including robust methods and active methods,are reviewed.Thirdly,research findings related to secure control and estimation problems for different types of CPSs are summarized.Finally,the survey is concluded by outlining the challenges and suggesting potential research directions for the future.展开更多
文摘传统移相控制下,无线电能传输(Wireles power transfer,WPT)系统输出功率宽范围调节时逆变器开关管易丢失零电压开关(Zero voltage switching,ZVS)状态,导致逆变器切换损耗增大甚至损坏。阶跃脉冲调制(Stepped Pulse Modulation)是一种低输出纹波调制方法,可实现宽负载范围内的ZVS运行。但是,该调制方法包含有限状态机等环节,不易采用传统的机理建模访求进行建模,给控制器设计带来困难。在Simulink电路的基础上,基于数据驱动方法辨识了无线电能传输在阶跃脉冲调制下传递函数模型,并基于该模型设计内模控制器。实验表明,基于Simulink电路仿真方法获取采样数据,能够有效解决实物实验在某些场景下难以获取实验数据的难题,获得满意的辨识模型。同时,基于辨识模型设计的内模控制器,能够精确估计不同控制参数下的系统控制性能,满足了阶跃脉冲调制无线电能传输输出电压闭环控制的性能需求。
文摘China’s“common prosperity”policy is a multidimensional pursuit of social and economic progress aimed at full realization by 2050.A CHIEVING common prosperity–prosperity that is universally shared–has been a longstanding aspiration of the Chinese government.
文摘Sandwich functionally graded(FG)auxetic beams are extensively utilized in aerospace,automotive,and biomedical industries due to their excellent strength-toweight ratio,impact resistance,and tunable mechanical properties.The integration of FG materials with auxetic structures enhances their adaptability in advanced engineering applications.However,understanding their dynamic behavior under external excitations is essential for optimal design and structural reliability.Nonlinear interactions in such structures pose significant challenges in vibration analysis,necessitating robust analytical methods.This study presents a closed-form solution for the nonlinear forced vibration analysis of sandwich FG auxetic beams,offering an accurate and efficient method for predicting their dynamic response.The beam consists of two FG face sheets with material properties varying through the thickness and a re-entrant honeycomb auxetic core with an adjustable Poisson's ratio.The governing nonlinear equations of motion are derived using the first-order shear deformation theory(FSDT),the modified Gibson model,and the von Kármán relations,formulated through Hamilton's principle.A closed-form solution is obtained via the Galerkin method and multiple-scale technique.The results demonstrate that FG layers enable control of the overweight and dynamic response amplitude,with positive power law indexes reducing weight.Comparisons with finite element results confirm the accuracy of the proposed formulation.
文摘Premature yeast flocculation(PYF)has been shown to induce early and enhanced yeast flocculation and can result in a myriad of produc-tion difficulties and delays.Researchers have demonstrated that PYF is linked to fungal infection of barley and/or malt.Therefore,one might suspect that PYF occurrence would increase in wet climates.To test this hypothesis,a control,a PYF-positive malt sample,and two Scot-tish-sourced malt varieties were compared with a control dataset of 77 femientations.Miniature fermentation trials using the ASBC method Yeast-14 were performed on these samples.Miniature fermentation tri-als have been optimized to detect PYF-causing malt by directly meas-uring attenuation via extract readings and indirectly measuring yeast in suspension via absorbance.Nonlinear and tilted Gaussian regressions were fit to the data sets to obtain attenuation and absorbance curves,respectively.Results obtained indicated that the PYF-causing malt in-duced both early and enhanced flocculation,whereas the other three malts(including the Scottish malts)did not induce early or enhanced flocculation.All four samples were compared using the F test,and it was determined that the PYF-positive malt sample was significantly different than the other three malts(P<0.05).Using previous results from 77 miniature fermentation trials on control malts,a novel 95%prediction band was developed.This band was applied and used to identify and decisively confirm the presence of PYF-causing malt as demonstrated herein.
文摘This paper presents a high-fidelity lumpedparameter(LP)thermal model(HF-LPTM)for permanent magnet synchronous machines(PMSMs)in electric vehicle(EV)applications,where various cooling techniques are considered,including frame forced air/liquid cooling,oil jet cooling for endwinding,and rotor shaft cooling.To address the temperature misestimation in the LP thermal modelling due to assumptions of concentrated loss input and uniform heat flows,the developed HF-LPTM introduces two compensation thermal resistances for the winding and PM components,which are analytically derived from the multi-dimensional heat transfer equations and are robust against different load/thermal conditions.As validated by the finite element analysis method and experiments,the conventional LPTMs exhibit significant winding temperature deviations,while the proposed HF-LPTM can accurately predict both the midpoint and average temperatures.The developed HFLPTM is further used to assess the effectiveness of various cooling techniques under different scenarios,i.e.,steady-state thermal states under the rated load condition,and transient temperature profiles under city,freeway,and hybrid(city+freeway)driving cycles.Results indicate that no single cooling technique can maintain both winding and PM temperatures within safety limits.The combination of frame liquid cooling and oil jet cooling for end winding can sufficiently mitigate PMSM thermal stress in EV applications.
基金supported by the National Natural Science Foundation of China(Nos.12172248,12302022,12021002,and 12132010)the Tianjin Research Program of Application Foundation and Advanced Technology of China(No.23JCZDJC00950)。
文摘Belt conveyors are extensively utilized in mining and power industries.In a typical coal mine conveyor system,coal is transported over distances exceeding 2 km,involving more than 20000 idlers,which far exceeds a reasonable manual inspection capacity.Given that idlers typically have a lifespan of 1-2 years,there is an urgent need for a rapid,cost-effective,and intelligent safety monitoring system.However,current embedded systems face prohibitive replacement costs,while conventional monitoring technologies suffer from inefficiency at low rotational speeds and lack systematic structural optimization frameworks for diverse idler types and parameters.To address these challenges,this paper introduces an integrated,on-site detachable self-powered idler condition monitoring system(ICMS).This system combines energy harvesting based on the magnetic modulation technology with wireless condition monitoring capabilities.Specifically,it develops a data-driven model integrating convolutional neural networks(CNNs) with genetic algorithms(GAs).The conventional testing results show that the data-driven model not only significantly accelerates the parameter response time,but also achieves a prediction accuracy of 92.95%.The in-situ experiments conducted in coal mines demonstrate the system's reliability and monitoring functionality under both no-load and fullload conditions.This research provides an innovative self-powered condition monitoring solution and develops an efficient data-driven model,offering feasible online monitoring approaches for smart mine construction.
文摘Cyber-physical systems(CPSs)are regarded as the backbone of the fourth industrial revolution,in which communication,physical processes,and computer technology are integrated.In modern industrial systems,CPSs are widely utilized across various domains,such as smart grids,smart healthcare systems,smart vehicles,and smart manufacturing,among others.Due to their unique spatial distribution,CPSs are highly vulnerable to cyber-attacks,which may result in severe performance degradation and even system instability.Consequently,the security concerns of CPSs have attracted significant attention in recent years.In this paper,a comprehensive survey on the security issues of CPSs under cyber-attacks is provided.Firstly,mathematical descriptions of various types of cyberattacks are introduced in detail.Secondly,two types of secure estimation and control processing schemes,including robust methods and active methods,are reviewed.Thirdly,research findings related to secure control and estimation problems for different types of CPSs are summarized.Finally,the survey is concluded by outlining the challenges and suggesting potential research directions for the future.
