The thermal switch plays a crucial role in regulating system temperature,protecting devices from overheating,and improving energy efficiency.Achieving a high thermal switching ratio is essential for its practical appl...The thermal switch plays a crucial role in regulating system temperature,protecting devices from overheating,and improving energy efficiency.Achieving a high thermal switching ratio is essential for its practical application.In this study,by utilizing first-principles calculations and semi-classical Boltzmann transport theory,it is found that hole doping with an experimentally achievable concentration of 1.83×10^(14)cm^(-2)can reduce the lattice thermal conductivity of monolayer MoS_(2) from 151.79 W·m^(-1)·K^(-1)to 12.19 W·m^(-1)·K^(-1),achieving a high thermal switching ratio of 12.5.The achieved switching ratio significantly surpasses previously reported values,including those achieved by extreme strain methods.This phenomenon mainly arises from the enhanced lattice anharmonicity,which is primarily contributed by the S atoms.These results indicate that hole doping is an effective method for tuning the lattice thermal conductivity of materials,and demonstrate that monolayer MoS_(2) is a potential candidate material for thermal switches.展开更多
Field-effect nanofluidic transistors(FENTs),biomimicking the structure and functionality of neuron,act as biological transistors with the ability to gate switching responses to external stimuli.The switching ratio has...Field-effect nanofluidic transistors(FENTs),biomimicking the structure and functionality of neuron,act as biological transistors with the ability to gate switching responses to external stimuli.The switching ratio has been verified to evaluate the performance of FENTs,but until recently,the response time,another crucial indicator,has been ignored.Employing finite-element method,we investigated the relationship among gate charge,switching ratio and response time by divisionally manipulating gate charge,including entrance surface and the surface of confinement space,for ion transport to optimize switching capability.The dual-split gate charge on FENTs exhibits synergistic effect on switching response.Based on the two regional gate charge on FENTs,multivalence ions in lower concentration,high aspect ratio and single channel show higher switching ratio but longer response time compared to monovalent ions.The findings highlight the necessity of balancing these two signals in FENTs and offer insights for optimizing their design and expanding applications to dual-signal-detection iontronics.展开更多
This paper describes a fixed-fixed beam ohmic switch in series with a fixed capacitor as a replacement for a capacitive switch.In this switch,a metal plate deposited on the dielectric ensures perfectly contact with th...This paper describes a fixed-fixed beam ohmic switch in series with a fixed capacitor as a replacement for a capacitive switch.In this switch,a metal plate deposited on the dielectric ensures perfectly contact with the dielectric layer in the down state.The area size of the metal plate directly influences the capacitance ratio of the switch,as the area size of the metal cap decreases,the capacitance ratio dramatically rises up.The down/up capacitance ratio can exceed 800 times over the conventional designs using the same materials and the equal size.Measurement results show that high capacitance ratio of the switches has a large effect on the isolation,and can actually improve the performance of the switches.展开更多
Cu/HfOx/n^＋Si devices are fabricated to investigate the influence of technological parameters including film thickness and Ar/02 ratio on the resistive switching （RS） characteristics of HfOx films, in terms of swit...Cu/HfOx/n^＋Si devices are fabricated to investigate the influence of technological parameters including film thickness and Ar/02 ratio on the resistive switching （RS） characteristics of HfOx films, in terms of switch ratio, endurance properties, retention time and multilevel storage. It is revealed that the RS characteristics show strong dependence on technological parameters mainly by altering the defects （oxygen vacancies） in the film. The sample with thickness of 2Onto and Ar/O2 ratio of 12：3 exhibits the best RS behavior with the potential of multilevel storage. The conduction mechanism of all the films is interpreted based on the filamentary model.展开更多
Previous studies on droplet generation in microfluidics mainly focus on the monodisperse droplet,but limited attention has paid to the generation of droplet groups composed of multiple droplets with different volumes ...Previous studies on droplet generation in microfluidics mainly focus on the monodisperse droplet,but limited attention has paid to the generation of droplet groups composed of multiple droplets with different volumes or components.In this study,a programmable electromagnetic valve is externally connected with the microfluidic chip featuring a conventional flow-focused structure.Different from the previous situation where only one droplet is generated by a single actuation of the electromagnetic valve,by precisely controlling the opening and closing of the valve,the continuous phase fluid exhibits periodic flow in the channel,and we realized the generation of a droplet group by a single actuation of the valve,and the number and volume of the droplets in each group can be regulated.Specifically,the number of large droplets in a droplet group is mainly determined by the opening time of the electromagnetic valve and the two-phase flow rate,and the number of small droplets is dominated by the valve closing time.The volume of individual droplets in a droplet group is largely dependent on the flow rate of the continuous phase.Our study extends the understanding of microfluidic droplet formation.It provides a feasible method for the efficient preparation of polydisperse droplets,which is important for microfluidic chip-based droplet control and has potential applications in industries related to microfluidic droplets.展开更多
The high-speed on/off valve(HSV)serves as the fundamental component responsible for generating discrete fluids within digital hydraulic systems.As the switching frequency of the HSV increases,the properties of the gen...The high-speed on/off valve(HSV)serves as the fundamental component responsible for generating discrete fluids within digital hydraulic systems.As the switching frequency of the HSV increases,the properties of the generated discrete fluid approach those of continuous fluids.Therefore,a higher frequency response characteristic of HSV is the key to ensure the control accuracy of digital hydraulic systems.However,the current research mainly focuses on its dynamic performance,but neglect its FRC.This paper presents a theoretical analysis demonstrating that the FRC of the HSV can be enhanced by minimizing its switching time.The maximum switching frequency(MSF)is mainly determined by opening dynamic performance when HSV operates with low switching duty ratio(SDR),whereas the closing dynamic performance limits the MSF when HSV operates with high SDR.Building upon these findings,the pre-excitation control algorithm(PECA)is proposed to reduce the switching time of the HSV,and consequently enhance its FRC.Experimental results demonstrate that PECA shortens the opening delay time of HSV by 1.12 ms,the closing delay time by 2.54 ms,and the closing moving time by 0.47 ms in comparison to the existing advanced control algorithms.As a result,a larger MSF of 417 Hz and a wider controllable SDR range from 20%to 70%were achieved at a switching frequency of 250 Hz.Thus,the proposed PFCA in this paper has been verified as an effective and promising approach for enhancing the control performance of digital hydraulic systems.展开更多
As a combination device for a step-up pulse transformer and a magnetic switch,the saturable pulse transformer is widely used in pulsed-power and plasma technology.A fractional-turn ratio saturable pulse transformer is...As a combination device for a step-up pulse transformer and a magnetic switch,the saturable pulse transformer is widely used in pulsed-power and plasma technology.A fractional-turn ratio saturable pulse transformer is constructed and analyzed in this paper.Preliminary experimental results show that if the primary energy storage capacitors are charged to 300 V,an output voltage of about 19 kV can be obtained across the capacitor connected to the secondary windings of a fractional-tum ratio saturable pulse transformer.Theoretical and experimental results reveal that this kind of pulse transformer is not only able to integrate a step-up transformer and a magnetic switch into one device,but can also lower the saturable inductance of its secondary windings,thus leading to the relatively high step-up ratio of the pulse transformer.Meanwhile,the application of the fractional-turn ratio saturable pulse transformer in a μs range pulse modulator as a voltage step-up device and main switch is also included in this paper.The demonstrated experiments display that an output voltage with an amplitude of about 29 kV,and a 1.6 μs pulse width can be obtained across a 3500 Ω resistive load,based on a pulse modulator,if the primary energy storage capacitors are charged to 300 V.This compact fractional-turn ratio saturable pulse transformer can be applied in many other fields such as surface treatment,corona plasma generation and dielectric barrier discharge.展开更多
Analyzes the mechanism of overvoltage when contactless tap changer switch which is applied in distributing transformer converted directly.When the device convert the tap off,it employs the way that the SSR is switche...Analyzes the mechanism of overvoltage when contactless tap changer switch which is applied in distributing transformer converted directly.When the device convert the tap off,it employs the way that the SSR is switched on when voltage through zero and switched off when current through zero.But in the experiment we found that overvoltage will occur in the process of changing tap changer.The paper illustrates the mechanism of overvoltage in theory by analyzing the equivalent circuit and using analytic method of transition process.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12104145 and 12374040)。
文摘The thermal switch plays a crucial role in regulating system temperature,protecting devices from overheating,and improving energy efficiency.Achieving a high thermal switching ratio is essential for its practical application.In this study,by utilizing first-principles calculations and semi-classical Boltzmann transport theory,it is found that hole doping with an experimentally achievable concentration of 1.83×10^(14)cm^(-2)can reduce the lattice thermal conductivity of monolayer MoS_(2) from 151.79 W·m^(-1)·K^(-1)to 12.19 W·m^(-1)·K^(-1),achieving a high thermal switching ratio of 12.5.The achieved switching ratio significantly surpasses previously reported values,including those achieved by extreme strain methods.This phenomenon mainly arises from the enhanced lattice anharmonicity,which is primarily contributed by the S atoms.These results indicate that hole doping is an effective method for tuning the lattice thermal conductivity of materials,and demonstrate that monolayer MoS_(2) is a potential candidate material for thermal switches.
基金supported by the Natural Science Foundation of Guangdong Province,China (No.2025A1515011654)the National Natural Science Foundation of China (No.22090053)+3 种基金the Fundamental Research Funds for National Universities,China University of Geosciences (Wuhan)support from the program of China Scholarships Council (No.202406410155)Young Elite Scientists Sponsorship Program by CAST-Doctoral Student Special Plansupport from the S&T Special Program of Huzhou (No.2024GZ07)。
文摘Field-effect nanofluidic transistors(FENTs),biomimicking the structure and functionality of neuron,act as biological transistors with the ability to gate switching responses to external stimuli.The switching ratio has been verified to evaluate the performance of FENTs,but until recently,the response time,another crucial indicator,has been ignored.Employing finite-element method,we investigated the relationship among gate charge,switching ratio and response time by divisionally manipulating gate charge,including entrance surface and the surface of confinement space,for ion transport to optimize switching capability.The dual-split gate charge on FENTs exhibits synergistic effect on switching response.Based on the two regional gate charge on FENTs,multivalence ions in lower concentration,high aspect ratio and single channel show higher switching ratio but longer response time compared to monovalent ions.The findings highlight the necessity of balancing these two signals in FENTs and offer insights for optimizing their design and expanding applications to dual-signal-detection iontronics.
文摘This paper describes a fixed-fixed beam ohmic switch in series with a fixed capacitor as a replacement for a capacitive switch.In this switch,a metal plate deposited on the dielectric ensures perfectly contact with the dielectric layer in the down state.The area size of the metal plate directly influences the capacitance ratio of the switch,as the area size of the metal cap decreases,the capacitance ratio dramatically rises up.The down/up capacitance ratio can exceed 800 times over the conventional designs using the same materials and the equal size.Measurement results show that high capacitance ratio of the switches has a large effect on the isolation,and can actually improve the performance of the switches.
基金Supported by the National Natural Science Foundation of China under Grant No 51202196the National Aerospace Science Foundation of China under Grant No 2013ZF53067+2 种基金the Natural Science Basic Research Plan in Shaanxi Province of China under Grant No 2014JQ6204the Fundamental Research Funds for the Central Universities under Grant No 3102014JCQ01032the 111 Project under Grant No B08040
文摘Cu/HfOx/n^＋Si devices are fabricated to investigate the influence of technological parameters including film thickness and Ar/02 ratio on the resistive switching （RS） characteristics of HfOx films, in terms of switch ratio, endurance properties, retention time and multilevel storage. It is revealed that the RS characteristics show strong dependence on technological parameters mainly by altering the defects （oxygen vacancies） in the film. The sample with thickness of 2Onto and Ar/O2 ratio of 12：3 exhibits the best RS behavior with the potential of multilevel storage. The conduction mechanism of all the films is interpreted based on the filamentary model.
基金supported by the Chongqing Human Resources and Social Security Bureau(Grant No.CX2023079)the Fundamental Research Funds for the Central Universities,China(Grant Nos.2023CDJXY-049 and 2024CDJXY-022)the National Natural Science Foundation of China(Grant Nos.T2350007 and 127404)。
文摘Previous studies on droplet generation in microfluidics mainly focus on the monodisperse droplet,but limited attention has paid to the generation of droplet groups composed of multiple droplets with different volumes or components.In this study,a programmable electromagnetic valve is externally connected with the microfluidic chip featuring a conventional flow-focused structure.Different from the previous situation where only one droplet is generated by a single actuation of the electromagnetic valve,by precisely controlling the opening and closing of the valve,the continuous phase fluid exhibits periodic flow in the channel,and we realized the generation of a droplet group by a single actuation of the valve,and the number and volume of the droplets in each group can be regulated.Specifically,the number of large droplets in a droplet group is mainly determined by the opening time of the electromagnetic valve and the two-phase flow rate,and the number of small droplets is dominated by the valve closing time.The volume of individual droplets in a droplet group is largely dependent on the flow rate of the continuous phase.Our study extends the understanding of microfluidic droplet formation.It provides a feasible method for the efficient preparation of polydisperse droplets,which is important for microfluidic chip-based droplet control and has potential applications in industries related to microfluidic droplets.
基金Supported by National Natural Science Foundation of China (Grant No.52005441)Young Elite Scientist Sponsorship Program by CAST of China (Grant No.2022-2024QNRC001)+4 种基金Zhejiang Provincial Natural Science Foundation of China (Grant No.LQ21E050017)Zhejiang Provincial“Pioneer”and“Leading Goose”R&D Program of China (Grant Nos.2022C01122,2022C01132)State Key Laboratory of Mechanical System and Vibration of China (Grant No.MSV202316)Fundamental Research Funds for the Provincial Universities of Zhejiang of China (Grant No.RF-A2023007)Research Project of ZJUT of China (Grant No.GYY-ZH-2023075)。
文摘The high-speed on/off valve(HSV)serves as the fundamental component responsible for generating discrete fluids within digital hydraulic systems.As the switching frequency of the HSV increases,the properties of the generated discrete fluid approach those of continuous fluids.Therefore,a higher frequency response characteristic of HSV is the key to ensure the control accuracy of digital hydraulic systems.However,the current research mainly focuses on its dynamic performance,but neglect its FRC.This paper presents a theoretical analysis demonstrating that the FRC of the HSV can be enhanced by minimizing its switching time.The maximum switching frequency(MSF)is mainly determined by opening dynamic performance when HSV operates with low switching duty ratio(SDR),whereas the closing dynamic performance limits the MSF when HSV operates with high SDR.Building upon these findings,the pre-excitation control algorithm(PECA)is proposed to reduce the switching time of the HSV,and consequently enhance its FRC.Experimental results demonstrate that PECA shortens the opening delay time of HSV by 1.12 ms,the closing delay time by 2.54 ms,and the closing moving time by 0.47 ms in comparison to the existing advanced control algorithms.As a result,a larger MSF of 417 Hz and a wider controllable SDR range from 20%to 70%were achieved at a switching frequency of 250 Hz.Thus,the proposed PFCA in this paper has been verified as an effective and promising approach for enhancing the control performance of digital hydraulic systems.
基金supported by National Natural Science Foundation of China under Grant Nos.51477177 and 51641707
文摘As a combination device for a step-up pulse transformer and a magnetic switch,the saturable pulse transformer is widely used in pulsed-power and plasma technology.A fractional-turn ratio saturable pulse transformer is constructed and analyzed in this paper.Preliminary experimental results show that if the primary energy storage capacitors are charged to 300 V,an output voltage of about 19 kV can be obtained across the capacitor connected to the secondary windings of a fractional-tum ratio saturable pulse transformer.Theoretical and experimental results reveal that this kind of pulse transformer is not only able to integrate a step-up transformer and a magnetic switch into one device,but can also lower the saturable inductance of its secondary windings,thus leading to the relatively high step-up ratio of the pulse transformer.Meanwhile,the application of the fractional-turn ratio saturable pulse transformer in a μs range pulse modulator as a voltage step-up device and main switch is also included in this paper.The demonstrated experiments display that an output voltage with an amplitude of about 29 kV,and a 1.6 μs pulse width can be obtained across a 3500 Ω resistive load,based on a pulse modulator,if the primary energy storage capacitors are charged to 300 V.This compact fractional-turn ratio saturable pulse transformer can be applied in many other fields such as surface treatment,corona plasma generation and dielectric barrier discharge.
基金Harbin science an technology officecontract num ber is 0 0 112 110 98
文摘Analyzes the mechanism of overvoltage when contactless tap changer switch which is applied in distributing transformer converted directly.When the device convert the tap off,it employs the way that the SSR is switched on when voltage through zero and switched off when current through zero.But in the experiment we found that overvoltage will occur in the process of changing tap changer.The paper illustrates the mechanism of overvoltage in theory by analyzing the equivalent circuit and using analytic method of transition process.
