Pipelines are extensively used in environments such as nuclear power plants,chemical factories,and medical devices to transport gases and liquids.These tubular environments often feature complex geometries,confined sp...Pipelines are extensively used in environments such as nuclear power plants,chemical factories,and medical devices to transport gases and liquids.These tubular environments often feature complex geometries,confined spaces,and millimeter-scale height restrictions,presenting significant challenges to conventional inspection methods.Here,we present an ultrasonic microrobot(weight,80 mg;dimensions,24 mm×7 mm;thickness,210μm)to realize agile and bidirectional navigation in narrow pipelines.The ultrathin structural design of the robot is achieved through a high-performance piezoelectric composite film microstructure based on MEMS technology.The robot exhibits various vibration modes when driven by ultrasonic frequency signals,its motion speed reaches81 cm s-1 at 54.8 k Hz,exceeding that of the fastest piezoelectric microrobots,and its forward and backward motion direction is controllable through frequency modulation,while the minimum driving voltage for initial movement can be as low as 3 VP-P.Additionally,the robot can effortlessly climb slopes up to 24.25°and carry loads more than 36 times its weight.The robot is capable of agile navigation through curved L-shaped pipes,pipes made of various materials(acrylic,stainless steel,and polyvinyl chloride),and even over water.To further demonstrate its inspection capabilities,a micro-endoscope camera is integrated into the robot,enabling real-time image capture inside glass pipes.展开更多
It is one concern of the researchers how magnesium(Mg)alloys solidify under different conditions and how their microstructure evolves during solidification,and what are the relationship between the macroscopic propert...It is one concern of the researchers how magnesium(Mg)alloys solidify under different conditions and how their microstructure evolves during solidification,and what are the relationship between the macroscopic properties and various microstructures.Such issues are difficult to be revealed through experiments only,especially for the newly developed Mg alloys,for which there is a lack of more systematic and mature system.However,multi-scale modeling and simulation can promote and deepen our understanding of the microstructure and its deformation mechanism.In this paper,we review and summarize the recent research progress of numerical simulation of Mg alloys in forming and microstructure,namely casting,extrusion,rolling,and welding,using crystal plasticity finite element(CPFEM)and molecular dynamics(DM)methods.Besides,the methods and innovations of modeling are also summarized.Lastly,the paper discusses the development prospects and challenges of the numerical simulation in the field of Mg alloys.展开更多
Piezoelectric ultrasonic transducers have shown great potential in biomedical applications due to their high acoustic-to-electric conversion efficiency and large power capacity.The focusing technique enables the trans...Piezoelectric ultrasonic transducers have shown great potential in biomedical applications due to their high acoustic-to-electric conversion efficiency and large power capacity.The focusing technique enables the transducer to produce an extremely narrow beam,greatly improving the resolution and sensitivity.In this work,we summarize the fundamental properties and biological effects of the ultrasound field,aiming to establish a correlation between device design and application.Focusing techniques for piezoelectric transducers are highlighted,including material selection and fabrication methods,which determine the final performance of piezoelectric transducers.Numerous examples,from ultrasound imaging,neuromodulation,tumor ablation to ultrasonic wireless energy transfer,are summarized to highlight the great promise of biomedical applications.Finally,the challenges and opportunities of focused ultrasound transducers are presented.The aim of this review is to bridge the gap between focused ultrasound systems and biomedical applications.展开更多
Objective:To investigate the diagnostic value of transcranial Doppler ultrasound(TCD)in elderly patients with cerebrovascular disease and emotional disorder.Methods:Sixty-seven patients with cerebrovascular disease ag...Objective:To investigate the diagnostic value of transcranial Doppler ultrasound(TCD)in elderly patients with cerebrovascular disease and emotional disorder.Methods:Sixty-seven patients with cerebrovascular disease aged 60 years or above and with white matter hyperintensity(WMH)on magnetic resonance imaging(MRI)were enrolled in the study.The patients were divided into two groups according to Hamilton Depression Scale(HAMD)score:vascular depression group(WMH with depression)and non-depressive group(WMH without depression).TCD was performed in both groups,and the results of vascular pulsatility index(PI)and average blood flow velocity(Vm)were compared.Results:A total of 67 elderly patients were enrolled,with 33 cases in the vascular depression group and 34 in the non-depression group according to HAMD scores.(1)No statistically significant differences were observed between the two groups in age,gender,smoking history,alcohol consumption history,hypertension history,diabetes history,ischemic stroke history,hemorrhagic stroke history,coronary heart disease history,white matter score,and white matter grading(P>0.05).(2)The Vm on both sides of the anterior cerebral artery(ACA)and middle cerebral artery(MCA)in the vascular depression group was significantly lower than that in the non-depressive group(P<0.05).However,no statistically significant difference was found in Vm on both sides of the terminal internal carotid artery(TICA)between the two groups(P>0.05).(3)The PI on both sides of the ACA and MCA in the vascular depressive group was significantly higher than that in the non-depression group(P<0.05),while no statistically significant difference was observed in TICA PI values(P>0.05).(4)No statistically significant differences were found in Vm and PI values of the left ACA and MCA compared to the right side in the vascular depression group(P>0.05).Conclusion:The hemodynamic disturbance of vascular depression can be manifested as increased resistance and slowed flow velocity of intracranial small arteries.Transcranial Doppler ultrasound is a valuable method for dynamic evaluation and auxiliary diagnosis of vascular depression.展开更多
Over the past several years,high-β_(N) experiments have been carried out on HL-2A.The high-β_(N) is realized using double transport barriers(DTBs)with hybrid scenarios.A stationary high-β_(N) (>2)scenario was ob...Over the past several years,high-β_(N) experiments have been carried out on HL-2A.The high-β_(N) is realized using double transport barriers(DTBs)with hybrid scenarios.A stationary high-β_(N) (>2)scenario was obtained by pure neutral-beam injection(NBI)heating.Transient high performance was also achieved,corresponding to β_(N)≥3,ne/ne_(G)∼0.6,H_(98)∼1.5,f_(bs)∼30%,q_(95)∼4.0,and𝐺∼0.4.The high-β_(N) scenario was successfully modeled using integrated simulation codes,that is,the one modeling framework for integrated tasks(OMFIT).In high-𝛽𝑁plasmas,magnetohydrodynamic(MHD)instabilities are abundant,including low-frequency global MHD oscilla-tion with n=1,high-frequency coherent mode(HCM)at the edge,and neoclassical tearing mode(NTM)and Alfvénic modes in the core.In some high-β_(N) discharges,it is observed that the NTMs with m/n=3/2 limit the growth of the plasma energy and decrease β_(N).The low-n global MHD oscillation is consistent with the coupling of destabilized internal(m/n=1/1)and external(m/n=3/1 or 4/1)modes,and plays a crucial role in triggering the onset of ELMs.Achieving high-β_(N) on HL-2A suggests that core-edge interplay is key to the plasma confinement enhancement mechanism.Experiments to enhance β_(N) will contribute to future plasma operation,such as international thermonuclear experimental reactor.展开更多
基金supported by the National Key Research and Development Program of China(No.2024YFB3212901)National Natural Science Foundation of China(12072189)the Medicine and Engineering Interdisciplinary Research Fund of Shanghai Jiao Tong University(No.YG2025ZD05)。
文摘Pipelines are extensively used in environments such as nuclear power plants,chemical factories,and medical devices to transport gases and liquids.These tubular environments often feature complex geometries,confined spaces,and millimeter-scale height restrictions,presenting significant challenges to conventional inspection methods.Here,we present an ultrasonic microrobot(weight,80 mg;dimensions,24 mm×7 mm;thickness,210μm)to realize agile and bidirectional navigation in narrow pipelines.The ultrathin structural design of the robot is achieved through a high-performance piezoelectric composite film microstructure based on MEMS technology.The robot exhibits various vibration modes when driven by ultrasonic frequency signals,its motion speed reaches81 cm s-1 at 54.8 k Hz,exceeding that of the fastest piezoelectric microrobots,and its forward and backward motion direction is controllable through frequency modulation,while the minimum driving voltage for initial movement can be as low as 3 VP-P.Additionally,the robot can effortlessly climb slopes up to 24.25°and carry loads more than 36 times its weight.The robot is capable of agile navigation through curved L-shaped pipes,pipes made of various materials(acrylic,stainless steel,and polyvinyl chloride),and even over water.To further demonstrate its inspection capabilities,a micro-endoscope camera is integrated into the robot,enabling real-time image capture inside glass pipes.
基金supported by the National Natural Science Foundation of China(No.52271091)Natural Science Foundation Project of Ningxia Province(No.2023AAC03324)the National Key Research and Development Program of China(No.2021YFB3701100).
文摘It is one concern of the researchers how magnesium(Mg)alloys solidify under different conditions and how their microstructure evolves during solidification,and what are the relationship between the macroscopic properties and various microstructures.Such issues are difficult to be revealed through experiments only,especially for the newly developed Mg alloys,for which there is a lack of more systematic and mature system.However,multi-scale modeling and simulation can promote and deepen our understanding of the microstructure and its deformation mechanism.In this paper,we review and summarize the recent research progress of numerical simulation of Mg alloys in forming and microstructure,namely casting,extrusion,rolling,and welding,using crystal plasticity finite element(CPFEM)and molecular dynamics(DM)methods.Besides,the methods and innovations of modeling are also summarized.Lastly,the paper discusses the development prospects and challenges of the numerical simulation in the field of Mg alloys.
基金National Natural Science Foundation of China(12072189,82171011)Shanghai Jiao Tong University‘Deep Blue Program’Fund(Grant No.SL2103)+1 种基金Project of Biobank(No.YBKB202117)from Shanghai Ninth People’s HospitalShanghai Jiao Tong University School of Medicine and Science Foundation of National Key Laboratory of Science and Technology on Advanced Composites in Special Environments(No.6142905223704)。
文摘Piezoelectric ultrasonic transducers have shown great potential in biomedical applications due to their high acoustic-to-electric conversion efficiency and large power capacity.The focusing technique enables the transducer to produce an extremely narrow beam,greatly improving the resolution and sensitivity.In this work,we summarize the fundamental properties and biological effects of the ultrasound field,aiming to establish a correlation between device design and application.Focusing techniques for piezoelectric transducers are highlighted,including material selection and fabrication methods,which determine the final performance of piezoelectric transducers.Numerous examples,from ultrasound imaging,neuromodulation,tumor ablation to ultrasonic wireless energy transfer,are summarized to highlight the great promise of biomedical applications.Finally,the challenges and opportunities of focused ultrasound transducers are presented.The aim of this review is to bridge the gap between focused ultrasound systems and biomedical applications.
文摘Objective:To investigate the diagnostic value of transcranial Doppler ultrasound(TCD)in elderly patients with cerebrovascular disease and emotional disorder.Methods:Sixty-seven patients with cerebrovascular disease aged 60 years or above and with white matter hyperintensity(WMH)on magnetic resonance imaging(MRI)were enrolled in the study.The patients were divided into two groups according to Hamilton Depression Scale(HAMD)score:vascular depression group(WMH with depression)and non-depressive group(WMH without depression).TCD was performed in both groups,and the results of vascular pulsatility index(PI)and average blood flow velocity(Vm)were compared.Results:A total of 67 elderly patients were enrolled,with 33 cases in the vascular depression group and 34 in the non-depression group according to HAMD scores.(1)No statistically significant differences were observed between the two groups in age,gender,smoking history,alcohol consumption history,hypertension history,diabetes history,ischemic stroke history,hemorrhagic stroke history,coronary heart disease history,white matter score,and white matter grading(P>0.05).(2)The Vm on both sides of the anterior cerebral artery(ACA)and middle cerebral artery(MCA)in the vascular depression group was significantly lower than that in the non-depressive group(P<0.05).However,no statistically significant difference was found in Vm on both sides of the terminal internal carotid artery(TICA)between the two groups(P>0.05).(3)The PI on both sides of the ACA and MCA in the vascular depressive group was significantly higher than that in the non-depression group(P<0.05),while no statistically significant difference was observed in TICA PI values(P>0.05).(4)No statistically significant differences were found in Vm and PI values of the left ACA and MCA compared to the right side in the vascular depression group(P>0.05).Conclusion:The hemodynamic disturbance of vascular depression can be manifested as increased resistance and slowed flow velocity of intracranial small arteries.Transcranial Doppler ultrasound is a valuable method for dynamic evaluation and auxiliary diagnosis of vascular depression.
基金supported in part by the ITER-CN(Grants No.2017YFE0301202 and 2019YFE03020000)by National Natural Science Foundation of China(Grants No.12125502,11875021 and 11835010)by Sichuan Foundation(Grant No.2020JDJQ0070).
文摘Over the past several years,high-β_(N) experiments have been carried out on HL-2A.The high-β_(N) is realized using double transport barriers(DTBs)with hybrid scenarios.A stationary high-β_(N) (>2)scenario was obtained by pure neutral-beam injection(NBI)heating.Transient high performance was also achieved,corresponding to β_(N)≥3,ne/ne_(G)∼0.6,H_(98)∼1.5,f_(bs)∼30%,q_(95)∼4.0,and𝐺∼0.4.The high-β_(N) scenario was successfully modeled using integrated simulation codes,that is,the one modeling framework for integrated tasks(OMFIT).In high-𝛽𝑁plasmas,magnetohydrodynamic(MHD)instabilities are abundant,including low-frequency global MHD oscilla-tion with n=1,high-frequency coherent mode(HCM)at the edge,and neoclassical tearing mode(NTM)and Alfvénic modes in the core.In some high-β_(N) discharges,it is observed that the NTMs with m/n=3/2 limit the growth of the plasma energy and decrease β_(N).The low-n global MHD oscillation is consistent with the coupling of destabilized internal(m/n=1/1)and external(m/n=3/1 or 4/1)modes,and plays a crucial role in triggering the onset of ELMs.Achieving high-β_(N) on HL-2A suggests that core-edge interplay is key to the plasma confinement enhancement mechanism.Experiments to enhance β_(N) will contribute to future plasma operation,such as international thermonuclear experimental reactor.
