Wide bandgap(WBG)semiconductors,such as silicon carbide(SiC)and gallium nitride(GaN),exhibit superior physical properties and demonstrate great potential for replacing conventional silicon(Si)semiconductors with WBG t...Wide bandgap(WBG)semiconductors,such as silicon carbide(SiC)and gallium nitride(GaN),exhibit superior physical properties and demonstrate great potential for replacing conventional silicon(Si)semiconductors with WBG technology,pushing the boundaries of power devices to handle higher blocking voltages,switching frequencies,output power levels,and operating temperatures.However,tradeoffs in switching performance and converter efficiency when substituting GaN devices for Si and SiC counterparts are not well-defined,especially in a cascode configuration.Additional research with further detailed investigation and analysis is necessitated for medium-voltage GaN devices in power converter applications.Therefore,the aim of this research is to experimentally investigate the impact of emerging 650/900 V cascode GaN devices on bidirectional dc-dc converters that are suitable for energy storage and distributed renewable energy systems.Dynamic characteristics of Si,SiC,and cascode GaN power devices are examined through the double-pulse test(DPT)circuit at different gate resistance values,device currents,and DC bus voltages.Furthermore,the switching behavior and energy loss as well as the rate of voltage and current changes over the time are studied and analyzed at various operating conditions.A 500 W experimental converter prototype is implemented to validate the benefits of cascode GaN devices on the converter operation and performance.Comprehensive analysis of the power losses and efficiency improvements for Si-based,SiC-based,and GaN-based converters are performed and evaluated as the switching frequency,working temperature,and output power level are in-creased.The experimental results reveal significant improvements in switching performance and energy efficiency from the emerging cascode GaN devices in the bidirectional converters.展开更多
The interests on energy storage schemes, bidirectional dc-dc converter and uninterruptible power supplies have been increasing nowadays as there wide researches are undertaken in the area of electric vehicles. A modif...The interests on energy storage schemes, bidirectional dc-dc converter and uninterruptible power supplies have been increasing nowadays as there wide researches are undertaken in the area of electric vehicles. A modified bi directional class-E resonant dc-dc converter is introduced here in this proposed topology for the application in electric vehicles. The advantages of soft switching techniques have been utilized for making analysis simple. The main advantage here in this system is that it can operate in a wide range of frequencies with minimal switching loss in transistors. This paper elaborates a detailed analysis on converter design and the same has been simulated and verified in Matlab/Simulink.展开更多
The design of a bidirectional dc-dc power converter specifically for a distributed energy application is presented. The existing two different DC voltage battery bank of the distributed generation needs to interlink e...The design of a bidirectional dc-dc power converter specifically for a distributed energy application is presented. The existing two different DC voltage battery bank of the distributed generation needs to interlink each other using a bi-directional dc-dc converter in order to minimize the unbalance of the output load currents of the three inverters connected to electric grid system. Through this connection, a current can flow from one system to another or vice versa depending on which systems need the current most. Thus, unbalanced currents of the grid line have been minimized and the reliability and performance of the DER grid connected system has been increased. A detailed mathematical analysis of the converter under steady state and transient condition are presented. Mathematical models for boost and buck modes are being derived and the simulink model is constructed in order to simulate the system. Moreover, the model has been validated on the actual operation of the converter, showing that the simulated results in Matlab Simulink are consistent with the experimental ones.展开更多
A microgrid is defined as a local electric power distribution system with diverse DG （distributed generation） units, energy storage systems, and loads, which can operate as a part of the distribution system or when ...A microgrid is defined as a local electric power distribution system with diverse DG （distributed generation） units, energy storage systems, and loads, which can operate as a part of the distribution system or when needed can operate in an islanded mode. Energy storage systems play a key role in improving security, stability, and power quality of the microgrid. During grid-connected mode, these storage units are charged from various DG sources as well as the main grid. During islanded mode, DG sources along with the storage units need to supply the load. Power electronic interfaces between the microgrid buses and the storage units should be able to detect the mode of operation, allow seamless transition between the modes, and allow power flow in both directions, while maintaining stability and power quality. An overview of bidirectional converter topologies relevant to microgrid energy storage application and their control strategies will be presented in this paper.展开更多
In this paper, analysis, design and implementation of non-isolated soft-switching bidirectional DC-DC converter with an active switch are described. The proposed topology gives the output voltage as twice as the input...In this paper, analysis, design and implementation of non-isolated soft-switching bidirectional DC-DC converter with an active switch are described. The proposed topology gives the output voltage as twice as the input voltage and enhances the efficiency up to 94.5% and 92.9% for boost and buck mode operation by proper selection of the duty cycle. Soft switching can be achieved at both steps up and step down operating modes. Small signal analysis based on state space averaging and transfer functions have been presented in detail for the proposed converter. Finally, the feasibility of the desired converter is confirmed to mat lab simulation and investigational results.展开更多
Single-atom catalysts(SACs)have garnered significant attention in lithium-sulfur(Li-S)batteries for their potential to mitigate the severe polysulfide shuttle effect and sluggish redox kinetics.However,the development...Single-atom catalysts(SACs)have garnered significant attention in lithium-sulfur(Li-S)batteries for their potential to mitigate the severe polysulfide shuttle effect and sluggish redox kinetics.However,the development of highly efficient SACs and a comprehensive understanding of their structure-activity relationships remain enormously challenging.Herein,a novel kind of Fe-based SAC featuring an asymmetric FeN_(5)-TeN_(4) coordination structure was precisely designed by introducing Te atom adjacent to the Fe active center to enhance the catalytic activity.Theoretical calculations reveal that the neighboring Te atom modulates the local coordination environment of the central Fe site,elevating the d-band center closer to the Fermi level and strengthening the d-p orbital hybridization between the catalyst and sulfur species,thereby immobilizing polysulfides and improving the bidirectional catalysis of Li-S redox.Consequently,the Fe-Te atom pair catalyst endows Li-S batteries with exceptional rate performance,achieving a high specific capacity of 735 mAh g^(−1) at 5 C,and remarkable cycling stability with a low decay rate of 0.038%per cycle over 1000 cycles at 1 C.This work provides fundamental insights into the electronic structure modulation of SACs and establishes a clear correlation between precisely engineered atomic configurations and their enhanced catalytic performance in Li-S electrochemistry.展开更多
Recognizing human interactions in RGB videos is a critical task in computer vision,with applications in video surveillance.Existing deep learning-based architectures have achieved strong results,but are computationall...Recognizing human interactions in RGB videos is a critical task in computer vision,with applications in video surveillance.Existing deep learning-based architectures have achieved strong results,but are computationally intensive,sensitive to video resolution changes and often fail in crowded scenes.We propose a novel hybrid system that is computationally efficient,robust to degraded video quality and able to filter out irrelevant individuals,making it suitable for real-life use.The system leverages multi-modal handcrafted features for interaction representation and a deep learning classifier for capturing complex dependencies.Using Mask R-CNN and YOLO11-Pose,we extract grayscale silhouettes and keypoint coordinates of interacting individuals,while filtering out irrelevant individuals using a proposed algorithm.From these,we extract silhouette-based features(local ternary pattern and histogram of optical flow)and keypoint-based features(distances,angles and velocities)that capture distinct spatial and temporal information.A Bidirectional Long Short-Term Memory network(BiLSTM)then classifies the interactions.Extensive experiments on the UT Interaction,SBU Kinect Interaction and the ISR-UOL 3D social activity datasets demonstrate that our system achieves competitive accuracy.They also validate the effectiveness of the chosen features and classifier,along with the proposed system’s computational efficiency and robustness to occlusion.展开更多
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
Nekemias megalophylla is a popular folk tea consumed by people in the Western Hubei(China)of which ampelopsin(AMP)is the main active ingredient.In this study,we investigated the effect of AMP on cervical cancer and ex...Nekemias megalophylla is a popular folk tea consumed by people in the Western Hubei(China)of which ampelopsin(AMP)is the main active ingredient.In this study,we investigated the effect of AMP on cervical cancer and explored its mechanism of action,focusing on apoptosis and autophagy.Firstly,we verified that AMP strongly inhibited the growth of C-33A cells and observed apoptosis and autophagy phenomenon in vivo,and found that AMP induces C-33A cell apoptosis via death receptor or mitochondrial pathways.The results also indicated that AMP-induced autophagy occurs via the PI3K/Akt/m TOR pathway.Secondly,when autophagy was inhibited,the AMP-induced apoptosis of C-33A cells was strengthened,when apoptosis was inhibited,the AMP-induced autophagy of C-33A cells was strengthened.PI3K/Akt/m TOR pathway activation enhances AMP-induced apoptosis in C-33A cells,while its inhibition strengthens AMP-induced autophagy.Finally,we confirmed that AMP inhibited cell growth and induced apoptosis and autophagy of C-33A cells in an in vivo nude mouse model of C-33A tumor xenografts.These results elucidate that AMP bidirectionally regulates apoptosis and autophagy in human cervical cancer C-33A cells by mediating the PI3K/Akt/m TOR pathway.展开更多
In today’s fast-paced,information-driven world,data centers can offer high-speed,intricate capabilities on a larger scale owing to the ever-growing demand for networks and information systems.Because data centers pro...In today’s fast-paced,information-driven world,data centers can offer high-speed,intricate capabilities on a larger scale owing to the ever-growing demand for networks and information systems.Because data centers process and transmit information,stability and reliability are important.Data center power supply architectures rely heavily on isolated bidirectional DC-DC converters to ensure safety and stability.For the smooth operation of a data center,the power supply must be reliable and uninterrupted.In this study,we summarize the basic principle,topology,switch conversion strategy,and control technology of the existing isolated bidirectional DC-DC converters.Subsequently,existing research results and problems with isolated bidirectional DC-DC converters are reviewed.Finally,future trends in the development of isolated bidirectional DC-DC converters for data centers are presented,which offer valuable insights for solving engineering obstacles and future research directions in the field.展开更多
This paper introduces a tri-state modulation technique for a soft-switching bidirectional DC-DC converter (BDC). This method maintains the soft-switching condition and introduces a freewheeling interval that reduces t...This paper introduces a tri-state modulation technique for a soft-switching bidirectional DC-DC converter (BDC). This method maintains the soft-switching condition and introduces a freewheeling interval that reduces the rise and fall times of the inductor current, effectively suppressing inductor current ripples. Additionally,the tri-state modulation provides an extra degree of freedom, enabling optimization for reduced operating losses. The paper details the operation principles of tri-state modulation in both buck and boost modes and discusses optimization strategies for minimizing losses. An experimental setup is developed to validate the tri-state modulation approach, where switching waveforms and efficiency are measured. The experimental results confirm that the proposed method achieves soft-switching conditions, suppresses inductor current ripples, and provides higher efficiency compared to conventional hard-switching BDC and typical soft-switching BDC.展开更多
This paper presents a quasi-Z-source based isolated bidirectional DC-DC converter(qZIBDC)for renewable energy applications.The converter utilizes a dual active bridge circuit with a quasi-Z-source network on both side...This paper presents a quasi-Z-source based isolated bidirectional DC-DC converter(qZIBDC)for renewable energy applications.The converter utilizes a dual active bridge circuit with a quasi-Z-source network on both sides,so the converter works as buck/boost converter from either side.It has a wider input/output voltage operating range,soft-switching capabilities without additional devices,and higher boost capability than a traditional dual active bridge circuit.Apart from that,shoot-through states are incorporated in its operating cycle to boost the input voltage resulting in high reliability of the proposed converter.Due to the symmetrical structure of the circuit,there is no defined high voltage or low voltage side as in traditional isolated bidirectional DC-DC converter.The operating principle and control strategy of the proposed converter are presented.Simulation and experimental results are provided to verify the effectiveness of the proposed converter topology and its control strategy.展开更多
Modelling of bidirectional full bridge DC-DC converter as one of the most applicable converters has received significant attention. Mathematical modelling reduces the simulation time in comparison with detailed circui...Modelling of bidirectional full bridge DC-DC converter as one of the most applicable converters has received significant attention. Mathematical modelling reduces the simulation time in comparison with detailed circuit response;moreover it is convenient for controller design purpose. Due to simple and effective methodology, average state space is the most common method among the modelling methods. In this paper a bidirectional full bridge converter is modelled by average state space and for each mode of operations a controller is designed. Attained mathematical model results are in a close agreement with detailed circuit simulation.展开更多
BACKGROUND Propofol has been widely used in bidirectional gastrointestinal endoscopy sedation;however,it frequently leads to cardiovascular adverse events and respiratory depression.Propofol target-controlled infusion...BACKGROUND Propofol has been widely used in bidirectional gastrointestinal endoscopy sedation;however,it frequently leads to cardiovascular adverse events and respiratory depression.Propofol target-controlled infusion(TCI)can provide safe sedation but may require higher dosages of propofol.On the contrary,etomidate offers hemodynamic stability.AIM To evaluate the effect of different dose etomidate added to propofol TCI sedation during same-visit bidirectional endoscopy.METHODS A total of 330 patients from Fujian Provincial Hospital were randomly divided into three groups:P,0.1EP,and 0.15EP.Patients in the P group received propofol TCI only,with an initial effect-site concentration of the propofol TCI system of 3.0 mg/mL.Patients in the 0.1EP and 0.15EP groups received 0.1 and 0.15 mg/kg etomidate intravenous injection,respectively,followed by propofol TCI.RESULTS Patients in the 0.15EP group had higher mean blood pressure after induction than the other groups(P group:78 mmHg,0.1EP group:82 mmHg,0.15EP group:88 mmHg;P<0.05).Total doses of propofol consumption significantly decreased in the 0.15EP group compared with that in the other groups(P group:260.6 mg,0.1EP group:228.1 mg,0.15EP group:201.2 mg;P<0.05).The induction time was longer in the P group than in the other groups(P group:1.9±0.7 minutes,0.1EP group:1.2±0.4 minutes,0.15EP group:1.1±0.3 minutes;P<0.01).The recovery time was shorter in the 0.15EP group than in the other groups(P group:4.8±2.1 minutes,0.1EP group:4.5±1.6 minutes,0.15EP group:3.9±1.4 minutes;P<0.01).The incidence of hypotension(P group:36.4%,0.1EP group:29.1%,0.15EP group:11.8%;P<0.01)and injection pain was lower in the 0.15EP group than in the other groups(P<0.05).Furthermore,the incidence of respiratory depression was lower in the 0.15EP group than in the P group(P<0.05).Additionally,the satisfaction of the patient,endoscopist,and anesthesiologist was higher in the 0.15EP group than in the other groups(P<0.05).CONCLUSION Our findings suggest that 0.15 mg/kg etomidate plus propofol TCI can significantly reduce propofol consumption,which is followed by fewer cardiovascular adverse events and respiratory depression,along with higher patient,endoscopist,and anesthesiologist satisfaction.展开更多
Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish ...Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish redox dynamics.Herein,we supply a strategy to optimize the electron structure of Ni_(2)P by concurrently introducing B-doped atoms and P vacancies in Ni_(2)P (Vp-B-Ni_(2)P),thereby enhancing the bidirectional sulfur conversion.The study indicates that the simultaneous introduction of B-doped atoms and P vacancies in Ni_(2)P causes the redistribution of electron around Ni atoms,bringing about the upward shift of d-band center of Ni atoms and effective d-p orbital hybridization between Ni atoms and sulfur species,thus strengthening the chemical anchoring for lithium polysulfides (LiPSs) as well as expediting the bidirectional conversion kinetics of sulfur species.Meanwhile,theoretical calculations reveal that the incorporation of B-doped atoms and P vacancies in Ni_(2)P selectively promotes Li2S dissolution and nucleation processes.Thus,the Li-S batteries with Vp-B-Ni_(2)P-separators present outstanding rate ability of 777 m A h g^(-1)at 5 C and high areal capacity of 8.03 mA h cm^(-2)under E/S of 5μL mg^(-1)and sulfur loading of 7.20 mg cm^(-2).This work elucidates that introducing heteroatom and vacancy in metal phosphide collaboratively regulates the electron structure to accelerate bidirectional sulfur conversion.展开更多
The primary challenge in renewable-energy utilization is an energy-storage system involving its power converter.The systems have to promise high efficiency,reliability and durability.Also,all of these can be realized ...The primary challenge in renewable-energy utilization is an energy-storage system involving its power converter.The systems have to promise high efficiency,reliability and durability.Also,all of these can be realized at an economical cost.Buck and boost converters connected in parallel can convert power in both directions.It is the basic non-isolated bidirectional topology commonly used with energy-storage systems.The primary issue with the buck-boost non-isolated bidirectional converter is how to enhance its performance,so the modification involving this topology is still conducted.This paper examines 29 proposed converters from 30 research publications published in the last 10 years,the most recent of which focuses on modified non-isolated bidirectional converters based on the buck-boost topology.These are classified into eight modification schemes,which involve adding new components or circuits to the base topology.Each is evaluated against six parameters:the number of components,control complexity,power-rating applications,soft-switching ability,efficiency outcome and capacity to minimize losses.Moreover,each modified non-isolated bidirectional converter was compared from the renewable-energy-based power-generation-source perspective utilized.Based on these studies,researchers might think of ways to improve the buck-boost converter by changing it to make a new non-isolated bidirectional converter that can be used in systems that need it.展开更多
文摘Wide bandgap(WBG)semiconductors,such as silicon carbide(SiC)and gallium nitride(GaN),exhibit superior physical properties and demonstrate great potential for replacing conventional silicon(Si)semiconductors with WBG technology,pushing the boundaries of power devices to handle higher blocking voltages,switching frequencies,output power levels,and operating temperatures.However,tradeoffs in switching performance and converter efficiency when substituting GaN devices for Si and SiC counterparts are not well-defined,especially in a cascode configuration.Additional research with further detailed investigation and analysis is necessitated for medium-voltage GaN devices in power converter applications.Therefore,the aim of this research is to experimentally investigate the impact of emerging 650/900 V cascode GaN devices on bidirectional dc-dc converters that are suitable for energy storage and distributed renewable energy systems.Dynamic characteristics of Si,SiC,and cascode GaN power devices are examined through the double-pulse test(DPT)circuit at different gate resistance values,device currents,and DC bus voltages.Furthermore,the switching behavior and energy loss as well as the rate of voltage and current changes over the time are studied and analyzed at various operating conditions.A 500 W experimental converter prototype is implemented to validate the benefits of cascode GaN devices on the converter operation and performance.Comprehensive analysis of the power losses and efficiency improvements for Si-based,SiC-based,and GaN-based converters are performed and evaluated as the switching frequency,working temperature,and output power level are in-creased.The experimental results reveal significant improvements in switching performance and energy efficiency from the emerging cascode GaN devices in the bidirectional converters.
文摘The interests on energy storage schemes, bidirectional dc-dc converter and uninterruptible power supplies have been increasing nowadays as there wide researches are undertaken in the area of electric vehicles. A modified bi directional class-E resonant dc-dc converter is introduced here in this proposed topology for the application in electric vehicles. The advantages of soft switching techniques have been utilized for making analysis simple. The main advantage here in this system is that it can operate in a wide range of frequencies with minimal switching loss in transistors. This paper elaborates a detailed analysis on converter design and the same has been simulated and verified in Matlab/Simulink.
文摘The design of a bidirectional dc-dc power converter specifically for a distributed energy application is presented. The existing two different DC voltage battery bank of the distributed generation needs to interlink each other using a bi-directional dc-dc converter in order to minimize the unbalance of the output load currents of the three inverters connected to electric grid system. Through this connection, a current can flow from one system to another or vice versa depending on which systems need the current most. Thus, unbalanced currents of the grid line have been minimized and the reliability and performance of the DER grid connected system has been increased. A detailed mathematical analysis of the converter under steady state and transient condition are presented. Mathematical models for boost and buck modes are being derived and the simulink model is constructed in order to simulate the system. Moreover, the model has been validated on the actual operation of the converter, showing that the simulated results in Matlab Simulink are consistent with the experimental ones.
文摘A microgrid is defined as a local electric power distribution system with diverse DG （distributed generation） units, energy storage systems, and loads, which can operate as a part of the distribution system or when needed can operate in an islanded mode. Energy storage systems play a key role in improving security, stability, and power quality of the microgrid. During grid-connected mode, these storage units are charged from various DG sources as well as the main grid. During islanded mode, DG sources along with the storage units need to supply the load. Power electronic interfaces between the microgrid buses and the storage units should be able to detect the mode of operation, allow seamless transition between the modes, and allow power flow in both directions, while maintaining stability and power quality. An overview of bidirectional converter topologies relevant to microgrid energy storage application and their control strategies will be presented in this paper.
文摘In this paper, analysis, design and implementation of non-isolated soft-switching bidirectional DC-DC converter with an active switch are described. The proposed topology gives the output voltage as twice as the input voltage and enhances the efficiency up to 94.5% and 92.9% for boost and buck mode operation by proper selection of the duty cycle. Soft switching can be achieved at both steps up and step down operating modes. Small signal analysis based on state space averaging and transfer functions have been presented in detail for the proposed converter. Finally, the feasibility of the desired converter is confirmed to mat lab simulation and investigational results.
基金supported by the National Natural Science Foundation(52302284,22002086,22204096)Shanghai Sailing Program(23YF1412200)the Fundamental Research Funds for the Central Universities(22120240314).
文摘Single-atom catalysts(SACs)have garnered significant attention in lithium-sulfur(Li-S)batteries for their potential to mitigate the severe polysulfide shuttle effect and sluggish redox kinetics.However,the development of highly efficient SACs and a comprehensive understanding of their structure-activity relationships remain enormously challenging.Herein,a novel kind of Fe-based SAC featuring an asymmetric FeN_(5)-TeN_(4) coordination structure was precisely designed by introducing Te atom adjacent to the Fe active center to enhance the catalytic activity.Theoretical calculations reveal that the neighboring Te atom modulates the local coordination environment of the central Fe site,elevating the d-band center closer to the Fermi level and strengthening the d-p orbital hybridization between the catalyst and sulfur species,thereby immobilizing polysulfides and improving the bidirectional catalysis of Li-S redox.Consequently,the Fe-Te atom pair catalyst endows Li-S batteries with exceptional rate performance,achieving a high specific capacity of 735 mAh g^(−1) at 5 C,and remarkable cycling stability with a low decay rate of 0.038%per cycle over 1000 cycles at 1 C.This work provides fundamental insights into the electronic structure modulation of SACs and establishes a clear correlation between precisely engineered atomic configurations and their enhanced catalytic performance in Li-S electrochemistry.
基金supported and funded by Princess Nourah bint Abdulrahman University Researchers Supporting Project number(PNURSP2025R410),Princess Nourah bint Abdulrahman University,Riyadh,Saudi Arabia.
文摘Recognizing human interactions in RGB videos is a critical task in computer vision,with applications in video surveillance.Existing deep learning-based architectures have achieved strong results,but are computationally intensive,sensitive to video resolution changes and often fail in crowded scenes.We propose a novel hybrid system that is computationally efficient,robust to degraded video quality and able to filter out irrelevant individuals,making it suitable for real-life use.The system leverages multi-modal handcrafted features for interaction representation and a deep learning classifier for capturing complex dependencies.Using Mask R-CNN and YOLO11-Pose,we extract grayscale silhouettes and keypoint coordinates of interacting individuals,while filtering out irrelevant individuals using a proposed algorithm.From these,we extract silhouette-based features(local ternary pattern and histogram of optical flow)and keypoint-based features(distances,angles and velocities)that capture distinct spatial and temporal information.A Bidirectional Long Short-Term Memory network(BiLSTM)then classifies the interactions.Extensive experiments on the UT Interaction,SBU Kinect Interaction and the ISR-UOL 3D social activity datasets demonstrate that our system achieves competitive accuracy.They also validate the effectiveness of the chosen features and classifier,along with the proposed system’s computational efficiency and robustness to occlusion.
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 Major Science and Technology Project of Hubei Province(2020ACA007)the Scientific and Technological Bureau of Wuhan(2018060401011308).
文摘Nekemias megalophylla is a popular folk tea consumed by people in the Western Hubei(China)of which ampelopsin(AMP)is the main active ingredient.In this study,we investigated the effect of AMP on cervical cancer and explored its mechanism of action,focusing on apoptosis and autophagy.Firstly,we verified that AMP strongly inhibited the growth of C-33A cells and observed apoptosis and autophagy phenomenon in vivo,and found that AMP induces C-33A cell apoptosis via death receptor or mitochondrial pathways.The results also indicated that AMP-induced autophagy occurs via the PI3K/Akt/m TOR pathway.Secondly,when autophagy was inhibited,the AMP-induced apoptosis of C-33A cells was strengthened,when apoptosis was inhibited,the AMP-induced autophagy of C-33A cells was strengthened.PI3K/Akt/m TOR pathway activation enhances AMP-induced apoptosis in C-33A cells,while its inhibition strengthens AMP-induced autophagy.Finally,we confirmed that AMP inhibited cell growth and induced apoptosis and autophagy of C-33A cells in an in vivo nude mouse model of C-33A tumor xenografts.These results elucidate that AMP bidirectionally regulates apoptosis and autophagy in human cervical cancer C-33A cells by mediating the PI3K/Akt/m TOR pathway.
基金Supported by the Natural Science Foundation for Distinguished Young Scholars of Guangdong Province(2022B1515020002).
文摘In today’s fast-paced,information-driven world,data centers can offer high-speed,intricate capabilities on a larger scale owing to the ever-growing demand for networks and information systems.Because data centers process and transmit information,stability and reliability are important.Data center power supply architectures rely heavily on isolated bidirectional DC-DC converters to ensure safety and stability.For the smooth operation of a data center,the power supply must be reliable and uninterrupted.In this study,we summarize the basic principle,topology,switch conversion strategy,and control technology of the existing isolated bidirectional DC-DC converters.Subsequently,existing research results and problems with isolated bidirectional DC-DC converters are reviewed.Finally,future trends in the development of isolated bidirectional DC-DC converters for data centers are presented,which offer valuable insights for solving engineering obstacles and future research directions in the field.
基金supported by the National Natural Science Foundation of China(No.52207076)the Natural Science Foundation of Hunan Province(No.2023JJ50025).
文摘This paper introduces a tri-state modulation technique for a soft-switching bidirectional DC-DC converter (BDC). This method maintains the soft-switching condition and introduces a freewheeling interval that reduces the rise and fall times of the inductor current, effectively suppressing inductor current ripples. Additionally,the tri-state modulation provides an extra degree of freedom, enabling optimization for reduced operating losses. The paper details the operation principles of tri-state modulation in both buck and boost modes and discusses optimization strategies for minimizing losses. An experimental setup is developed to validate the tri-state modulation approach, where switching waveforms and efficiency are measured. The experimental results confirm that the proposed method achieves soft-switching conditions, suppresses inductor current ripples, and provides higher efficiency compared to conventional hard-switching BDC and typical soft-switching BDC.
文摘This paper presents a quasi-Z-source based isolated bidirectional DC-DC converter(qZIBDC)for renewable energy applications.The converter utilizes a dual active bridge circuit with a quasi-Z-source network on both sides,so the converter works as buck/boost converter from either side.It has a wider input/output voltage operating range,soft-switching capabilities without additional devices,and higher boost capability than a traditional dual active bridge circuit.Apart from that,shoot-through states are incorporated in its operating cycle to boost the input voltage resulting in high reliability of the proposed converter.Due to the symmetrical structure of the circuit,there is no defined high voltage or low voltage side as in traditional isolated bidirectional DC-DC converter.The operating principle and control strategy of the proposed converter are presented.Simulation and experimental results are provided to verify the effectiveness of the proposed converter topology and its control strategy.
文摘Modelling of bidirectional full bridge DC-DC converter as one of the most applicable converters has received significant attention. Mathematical modelling reduces the simulation time in comparison with detailed circuit response;moreover it is convenient for controller design purpose. Due to simple and effective methodology, average state space is the most common method among the modelling methods. In this paper a bidirectional full bridge converter is modelled by average state space and for each mode of operations a controller is designed. Attained mathematical model results are in a close agreement with detailed circuit simulation.
文摘BACKGROUND Propofol has been widely used in bidirectional gastrointestinal endoscopy sedation;however,it frequently leads to cardiovascular adverse events and respiratory depression.Propofol target-controlled infusion(TCI)can provide safe sedation but may require higher dosages of propofol.On the contrary,etomidate offers hemodynamic stability.AIM To evaluate the effect of different dose etomidate added to propofol TCI sedation during same-visit bidirectional endoscopy.METHODS A total of 330 patients from Fujian Provincial Hospital were randomly divided into three groups:P,0.1EP,and 0.15EP.Patients in the P group received propofol TCI only,with an initial effect-site concentration of the propofol TCI system of 3.0 mg/mL.Patients in the 0.1EP and 0.15EP groups received 0.1 and 0.15 mg/kg etomidate intravenous injection,respectively,followed by propofol TCI.RESULTS Patients in the 0.15EP group had higher mean blood pressure after induction than the other groups(P group:78 mmHg,0.1EP group:82 mmHg,0.15EP group:88 mmHg;P<0.05).Total doses of propofol consumption significantly decreased in the 0.15EP group compared with that in the other groups(P group:260.6 mg,0.1EP group:228.1 mg,0.15EP group:201.2 mg;P<0.05).The induction time was longer in the P group than in the other groups(P group:1.9±0.7 minutes,0.1EP group:1.2±0.4 minutes,0.15EP group:1.1±0.3 minutes;P<0.01).The recovery time was shorter in the 0.15EP group than in the other groups(P group:4.8±2.1 minutes,0.1EP group:4.5±1.6 minutes,0.15EP group:3.9±1.4 minutes;P<0.01).The incidence of hypotension(P group:36.4%,0.1EP group:29.1%,0.15EP group:11.8%;P<0.01)and injection pain was lower in the 0.15EP group than in the other groups(P<0.05).Furthermore,the incidence of respiratory depression was lower in the 0.15EP group than in the P group(P<0.05).Additionally,the satisfaction of the patient,endoscopist,and anesthesiologist was higher in the 0.15EP group than in the other groups(P<0.05).CONCLUSION Our findings suggest that 0.15 mg/kg etomidate plus propofol TCI can significantly reduce propofol consumption,which is followed by fewer cardiovascular adverse events and respiratory depression,along with higher patient,endoscopist,and anesthesiologist satisfaction.
基金Institute of Technology Research Fund Program for Young Scholars21C Innovation Laboratory Contemporary Amperex Technology Co.,Limited,Ninde, 352100, China (21C–OP-202314)。
文摘Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish redox dynamics.Herein,we supply a strategy to optimize the electron structure of Ni_(2)P by concurrently introducing B-doped atoms and P vacancies in Ni_(2)P (Vp-B-Ni_(2)P),thereby enhancing the bidirectional sulfur conversion.The study indicates that the simultaneous introduction of B-doped atoms and P vacancies in Ni_(2)P causes the redistribution of electron around Ni atoms,bringing about the upward shift of d-band center of Ni atoms and effective d-p orbital hybridization between Ni atoms and sulfur species,thus strengthening the chemical anchoring for lithium polysulfides (LiPSs) as well as expediting the bidirectional conversion kinetics of sulfur species.Meanwhile,theoretical calculations reveal that the incorporation of B-doped atoms and P vacancies in Ni_(2)P selectively promotes Li2S dissolution and nucleation processes.Thus,the Li-S batteries with Vp-B-Ni_(2)P-separators present outstanding rate ability of 777 m A h g^(-1)at 5 C and high areal capacity of 8.03 mA h cm^(-2)under E/S of 5μL mg^(-1)and sulfur loading of 7.20 mg cm^(-2).This work elucidates that introducing heteroatom and vacancy in metal phosphide collaboratively regulates the electron structure to accelerate bidirectional sulfur conversion.
基金supported and funded by the Higher Education Leading Applied Research(PTUPT)programme of the Ministry of Education,Culture,Research,and Technology of the Republic of Indonesia under contract number 011/PL.PTUPT/BRIn.LPPM/VI/2022the Indonesia Endowment Funds for Education(LPDP),Ministry of Finance of the Republic of Indonesia[number:20200811214083].
文摘The primary challenge in renewable-energy utilization is an energy-storage system involving its power converter.The systems have to promise high efficiency,reliability and durability.Also,all of these can be realized at an economical cost.Buck and boost converters connected in parallel can convert power in both directions.It is the basic non-isolated bidirectional topology commonly used with energy-storage systems.The primary issue with the buck-boost non-isolated bidirectional converter is how to enhance its performance,so the modification involving this topology is still conducted.This paper examines 29 proposed converters from 30 research publications published in the last 10 years,the most recent of which focuses on modified non-isolated bidirectional converters based on the buck-boost topology.These are classified into eight modification schemes,which involve adding new components or circuits to the base topology.Each is evaluated against six parameters:the number of components,control complexity,power-rating applications,soft-switching ability,efficiency outcome and capacity to minimize losses.Moreover,each modified non-isolated bidirectional converter was compared from the renewable-energy-based power-generation-source perspective utilized.Based on these studies,researchers might think of ways to improve the buck-boost converter by changing it to make a new non-isolated bidirectional converter that can be used in systems that need it.
