Plasma control of forebody asymmetric vortices is mostly achieved by means of dielectric barrier discharge(DBD)plasma actuators. However, DBD actuators suffer from some disadvantages such as a weak induced body force,...Plasma control of forebody asymmetric vortices is mostly achieved by means of dielectric barrier discharge(DBD)plasma actuators. However, DBD actuators suffer from some disadvantages such as a weak induced body force, a singledirection induced jet, and an unclear control mechanism. We carry out wind tunnel experiments involving the forebody vortex control of a slender body at high angles of attack using an innovative extended DBD actuator, which has a stronger capacity to induce an electric wind than a DBD actuator. Through synchronous measurements of the pressure distribution and particle image velocimetry(PIV), the spatiotemporal evolution of the dynamic interactions between plasma-actuationinduced vortices and forebody asymmetric vortices is analyzed. The influence of plasma discharge on the boundary layer separation around a slender body and the spatial topological structures of asymmetric vortices are further surveyed, as the optimized actuation parameters. Extended DBD actuators are found to be more capable of controlling asymmetric vortices than DBD actuators, and a linear proportionality of the sectional lateral force versus the duty ratio is achieved.There exists an optimal normalized reduced frequency( f+= 2π fpd/U∞= 2.39) for asymmetric vortex control under the present experimental conditions. The research results can provide technical guidance for the control and reuse of forebody asymmetric vortices.展开更多
The design of a universal waveform generator derived from displaying driving applications using floating power and Miller integrator circuit is introduced first. Then, the feasibility of driving ultrasound transducers...The design of a universal waveform generator derived from displaying driving applications using floating power and Miller integrator circuit is introduced first. Then, the feasibility of driving ultrasound transducers is verified by the test of the circuit and compared with other specific design of pulse generator for ultrasound driving purpose.展开更多
This paper reviews the recent progress on bionic microelectromechanical systems(MEMS)used for touching and hearing sensations,focusing on the following three types of devices:MEMS tactile sensors,MEMS directional micr...This paper reviews the recent progress on bionic microelectromechanical systems(MEMS)used for touching and hearing sensations,focusing on the following three types of devices:MEMS tactile sensors,MEMS directional microphones,and MEMS vector hydrophones.After reviewing the electromechanical coupling principles,design,and performance of these MEMS devices,the authors conclude that it is vital for future research efforts in bionic MEMS to focus more on microfabrication technologies.The development of robust microfabrication flows is the basis to implement hybrid electromechanical coupling principles based on novel functional materials.High-quality polymeric micromachining technologies can also significantly enhance the potential of existing bionic MEMS designs for more practical applications.展开更多
This paper presents a literature review exploring the potential of piezoelectric field-effect transistors(piezo-FETs)as bionic microelectromechanical systems(MEMS).First,piezo-FETs are introduced as bionic counterpart...This paper presents a literature review exploring the potential of piezoelectric field-effect transistors(piezo-FETs)as bionic microelectromechanical systems(MEMS).First,piezo-FETs are introduced as bionic counterparts to natural mechanoreceptors,highlighting their classic configuration and working principles.Then,this paper summarizes the existing research on piezo-FETs as sensors for pressure,inertial,and acoustic sensors.Material selections,design characteristics,and key performance metrics are reviewed to demonstrate the advantage of piezo-FETs over traditional piezoelectric sensors.After identifying the limitations in these existing studies,this paper proposes using bionic piezoelectric coupling structures in piezo-FETs to further enhance the sensing capabilities of these artificial mechanoreceptors.Experimentally validated manufacturing methods for the newly proposed piezo-FET structures are also reviewed,pointing out a novel,feasible,and impactful research direction on these bionic piezoelectric MEMS sensors.展开更多
Sugarcane mechanized planting technology consists of seed preparation and field planting.This study aims at the issues of easy damage to the seeds during the operation of the automatic cutting machine for single-bud s...Sugarcane mechanized planting technology consists of seed preparation and field planting.This study aims at the issues of easy damage to the seeds during the operation of the automatic cutting machine for single-bud segment sugarcane,lack of intelligent seed selection and calibration technology,low recognition accuracy,and the need for manual feeding of the planting machine’s seed meter which leads to seed leakage.This study,based on machine vision and deep learning,optimizes the seed calibration method and proposes an improved YoloV5-STD target detection algorithm to improve the recognition accuracy of seed characteristics and optimize the overall engineering structure.For the planting machine,a new type of hopper for the seed meter is designed using natural rubber as the base material mixed with polystyrene,and the flexible automatic seed metering mechanism is analyzed to achieve automatic feeding and seed metering.Test assessment indicators were formulated based on the enterprise standards of the Institute of Agricultural Machinery Research,Chinese Academy of Tropical Agricultural Sciences.Experimental results show that the recognition accuracy of the 2DZ-2 type single-bud segment intelligent cutting machine is≥95%,the bud injury rate is<1.8%,the qualified rate of cutting is 95.8%,and the single-channel cutting efficiency is 64 buds/min.The 2CZD-2C type single-bud segment planter has a planting qualification rate of 96.6%,a planting efficiency of 208 buds/min,and a seed leakage rate of<2.1%.展开更多
BACKGROUND Spinal deformities in Ehlers-Danlos syndrome(EDS; type VI) are generally progressive and severe. Surgical treatment has been described for kyphoscoliosis in the thoracolumbar spine. However, there are few s...BACKGROUND Spinal deformities in Ehlers-Danlos syndrome(EDS; type VI) are generally progressive and severe. Surgical treatment has been described for kyphoscoliosis in the thoracolumbar spine. However, there are few studies describing the consequences of an anterior approach in cervical kyphosis. An anterior approach may not be able to fully decompress the spinal canal and restore the normal curvature of the cervical spine. Therefore, the anterior approach for cervical kyphosis in young children is hard. We describe the first case in an EDS girl with cervical kyphosis who received satisfactory anterior cervical corpectomy decompression and fusion.CASE SUMMARY The chief complaints of a 16-year-old girl with EDS were double upper limb weakness for 7 years and double lower limb walking instability for 2 years.Moreover, the imaging results revealed that the degree of kyphosis from cervical vertebra 2 to 4 accompanying with spinal cord compression was 30°. An anterior cervical corpectomy involving cervical vertebra 3 and a titanium mesh implant were performed with internal fixation. The results at 3 mo after surgery demonstrated that the anterior fusion was solid, and the kyphosis of the cervical spine was corrected. Additionally, the power of all four extremities was significantly improved.CONCLUSION The incidence rate of cervical kyphosis in EDS is rare. The surgical treatment for these patients, especially an anterior approach, is challenging. Therefore, to develop safer and more effective strategies to treat cervical kyphosis in EDS,there is still much work to do.展开更多
We present a novel stackable luminescent device integrating a blue light emitting diode(LED)with a red organic LED(OLED)in series.The anode of the OLED is connected with the cathode of the LED through a via in the ins...We present a novel stackable luminescent device integrating a blue light emitting diode(LED)with a red organic LED(OLED)in series.The anode of the OLED is connected with the cathode of the LED through a via in the insulation layer on the LED.The LED–OLED hybrid device is electroluminescent and two electroluminescence(EL)peaks(the blue peak around 454 nm and the red peak around 610 nm)are observed clearly.The effect of the indium tin oxide(ITO)layer on the device performance is analyzed.Compared with the individual LED and OLED,their combination shows great potential applications in the field of white lighting,plant lighting,and display.展开更多
基金National Natural Science Foundation of China(Grant Nos.51607188 and 61971345)the Foundation for Key Laboratories of National Defense Science and Technology,China(Grant No.614220202011801)+1 种基金the Natural Science Basic Research Program of Shaanxi Province of China(Grant No.2019JM-393)Xi’an Municipal Science and Technology Project of China(Grant No.201805037YD15CG21(28)).
文摘Plasma control of forebody asymmetric vortices is mostly achieved by means of dielectric barrier discharge(DBD)plasma actuators. However, DBD actuators suffer from some disadvantages such as a weak induced body force, a singledirection induced jet, and an unclear control mechanism. We carry out wind tunnel experiments involving the forebody vortex control of a slender body at high angles of attack using an innovative extended DBD actuator, which has a stronger capacity to induce an electric wind than a DBD actuator. Through synchronous measurements of the pressure distribution and particle image velocimetry(PIV), the spatiotemporal evolution of the dynamic interactions between plasma-actuationinduced vortices and forebody asymmetric vortices is analyzed. The influence of plasma discharge on the boundary layer separation around a slender body and the spatial topological structures of asymmetric vortices are further surveyed, as the optimized actuation parameters. Extended DBD actuators are found to be more capable of controlling asymmetric vortices than DBD actuators, and a linear proportionality of the sectional lateral force versus the duty ratio is achieved.There exists an optimal normalized reduced frequency( f+= 2π fpd/U∞= 2.39) for asymmetric vortex control under the present experimental conditions. The research results can provide technical guidance for the control and reuse of forebody asymmetric vortices.
文摘The design of a universal waveform generator derived from displaying driving applications using floating power and Miller integrator circuit is introduced first. Then, the feasibility of driving ultrasound transducers is verified by the test of the circuit and compared with other specific design of pulse generator for ultrasound driving purpose.
文摘This paper reviews the recent progress on bionic microelectromechanical systems(MEMS)used for touching and hearing sensations,focusing on the following three types of devices:MEMS tactile sensors,MEMS directional microphones,and MEMS vector hydrophones.After reviewing the electromechanical coupling principles,design,and performance of these MEMS devices,the authors conclude that it is vital for future research efforts in bionic MEMS to focus more on microfabrication technologies.The development of robust microfabrication flows is the basis to implement hybrid electromechanical coupling principles based on novel functional materials.High-quality polymeric micromachining technologies can also significantly enhance the potential of existing bionic MEMS designs for more practical applications.
文摘This paper presents a literature review exploring the potential of piezoelectric field-effect transistors(piezo-FETs)as bionic microelectromechanical systems(MEMS).First,piezo-FETs are introduced as bionic counterparts to natural mechanoreceptors,highlighting their classic configuration and working principles.Then,this paper summarizes the existing research on piezo-FETs as sensors for pressure,inertial,and acoustic sensors.Material selections,design characteristics,and key performance metrics are reviewed to demonstrate the advantage of piezo-FETs over traditional piezoelectric sensors.After identifying the limitations in these existing studies,this paper proposes using bionic piezoelectric coupling structures in piezo-FETs to further enhance the sensing capabilities of these artificial mechanoreceptors.Experimentally validated manufacturing methods for the newly proposed piezo-FET structures are also reviewed,pointing out a novel,feasible,and impactful research direction on these bionic piezoelectric MEMS sensors.
基金supported by the Project of Guangxi Zhuang Autonomous Region Key Technologies R&D Program(Grant No.GK AB23026069 and GN AB241484034)the Basic Scientific Research Expenses of Central Public Welfare Scientific Research Institutes(Grant No.1630132022001)+1 种基金the Basic Scientific Research Expenses of Chinese Academy of Tropical Agricultural Sciences(Grant No.1630132024004)the Zhanjiang Science and Technology Project(Grant No.2023A01009).
文摘Sugarcane mechanized planting technology consists of seed preparation and field planting.This study aims at the issues of easy damage to the seeds during the operation of the automatic cutting machine for single-bud segment sugarcane,lack of intelligent seed selection and calibration technology,low recognition accuracy,and the need for manual feeding of the planting machine’s seed meter which leads to seed leakage.This study,based on machine vision and deep learning,optimizes the seed calibration method and proposes an improved YoloV5-STD target detection algorithm to improve the recognition accuracy of seed characteristics and optimize the overall engineering structure.For the planting machine,a new type of hopper for the seed meter is designed using natural rubber as the base material mixed with polystyrene,and the flexible automatic seed metering mechanism is analyzed to achieve automatic feeding and seed metering.Test assessment indicators were formulated based on the enterprise standards of the Institute of Agricultural Machinery Research,Chinese Academy of Tropical Agricultural Sciences.Experimental results show that the recognition accuracy of the 2DZ-2 type single-bud segment intelligent cutting machine is≥95%,the bud injury rate is<1.8%,the qualified rate of cutting is 95.8%,and the single-channel cutting efficiency is 64 buds/min.The 2CZD-2C type single-bud segment planter has a planting qualification rate of 96.6%,a planting efficiency of 208 buds/min,and a seed leakage rate of<2.1%.
文摘BACKGROUND Spinal deformities in Ehlers-Danlos syndrome(EDS; type VI) are generally progressive and severe. Surgical treatment has been described for kyphoscoliosis in the thoracolumbar spine. However, there are few studies describing the consequences of an anterior approach in cervical kyphosis. An anterior approach may not be able to fully decompress the spinal canal and restore the normal curvature of the cervical spine. Therefore, the anterior approach for cervical kyphosis in young children is hard. We describe the first case in an EDS girl with cervical kyphosis who received satisfactory anterior cervical corpectomy decompression and fusion.CASE SUMMARY The chief complaints of a 16-year-old girl with EDS were double upper limb weakness for 7 years and double lower limb walking instability for 2 years.Moreover, the imaging results revealed that the degree of kyphosis from cervical vertebra 2 to 4 accompanying with spinal cord compression was 30°. An anterior cervical corpectomy involving cervical vertebra 3 and a titanium mesh implant were performed with internal fixation. The results at 3 mo after surgery demonstrated that the anterior fusion was solid, and the kyphosis of the cervical spine was corrected. Additionally, the power of all four extremities was significantly improved.CONCLUSION The incidence rate of cervical kyphosis in EDS is rare. The surgical treatment for these patients, especially an anterior approach, is challenging. Therefore, to develop safer and more effective strategies to treat cervical kyphosis in EDS,there is still much work to do.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFB0404800)。
文摘We present a novel stackable luminescent device integrating a blue light emitting diode(LED)with a red organic LED(OLED)in series.The anode of the OLED is connected with the cathode of the LED through a via in the insulation layer on the LED.The LED–OLED hybrid device is electroluminescent and two electroluminescence(EL)peaks(the blue peak around 454 nm and the red peak around 610 nm)are observed clearly.The effect of the indium tin oxide(ITO)layer on the device performance is analyzed.Compared with the individual LED and OLED,their combination shows great potential applications in the field of white lighting,plant lighting,and display.
