The self-heating effect severely limits device performance and reliability.Although some studies have revealed the heat distribution ofβ-Ga_(2)O_(3) MOSFETs under biases,those devices all have small areas and have di...The self-heating effect severely limits device performance and reliability.Although some studies have revealed the heat distribution ofβ-Ga_(2)O_(3) MOSFETs under biases,those devices all have small areas and have difficulty reflecting practical con-ditions.This work demonstrated a multi-fingerβ-Ga_(2)O_(3) MOSFET with a maximum drain current of 0.5 A.Electrical characteris-tics were measured,and the heat dissipation of the device was investigated through infrared images.The relationship between device temperature and time/bias is analyzed.展开更多
Ying Chao,born in the 1990s in Jiaxing City of east China’s Zhejiang Province,is of the opinion that traditional agricultural methods cannot meet the demands of modern farming.He plans to change agricultural practice...Ying Chao,born in the 1990s in Jiaxing City of east China’s Zhejiang Province,is of the opinion that traditional agricultural methods cannot meet the demands of modern farming.He plans to change agricultural practices and follow the road of mechanisation after taking part in a one-year vocational training course on drones in Jiaxing Vocational and Technical College in 2021.In fact,more and more young people like Ying are applying digital technology and big data to agricultural production and rural development.And the government has laid out plans to encourage this transition.展开更多
A large area multi-finger configuration power SiGe HBT device （with an emitter area of about 880μm^2） was fabricated with 2μm double-mesa technology. The maximum DC current gain β is 214. The BVCEO is up to 10V,a...A large area multi-finger configuration power SiGe HBT device （with an emitter area of about 880μm^2） was fabricated with 2μm double-mesa technology. The maximum DC current gain β is 214. The BVCEO is up to 10V,and the BVCBO is up to 16V with a collector doping concentration of 1 × 10^17cm^-3 and collector thickness of 400nm. The device exhibits a maximum oscillation frequency fmax of 19. 3GHz and a cut-off frequency fT of 18.0GHz at a DC bias point of Ic = 30mA and VCE = 3V.MSG （maximum stable gain） is 24.5dB,and U （Mason unilateral gain） is 26.6dB at 1GHz. Due to the novel distribution layout, no notable current gain fall-off or thermal effects are observed in the I-V characteristics at high collector current.展开更多
Due to the correlation and diversity of robotic kinematic dexterity indexes, the principal component analysis （PCA） and kernel principal component analysis （KPCA） based on linear dimension reduction and nonlinear ...Due to the correlation and diversity of robotic kinematic dexterity indexes, the principal component analysis （PCA） and kernel principal component analysis （KPCA） based on linear dimension reduction and nonlinear dimension reduction principle could be respectively introduced into comprehensive kinematic dexterity performance evaluation of space 3R robot of different tasks. By comparing different dimension reduction effects, the KPCA method could deal more effectively with the nonlinear relationship among different single kinematic dexterity indexes, and its calculation result is more reasonable for containing more comprehensive information. KPCA＇ s calculation provides scientific basis for optimum order of robotic tasks, and furthermore a new optimization method for robotic task selection is proposed based on various performance indexes.展开更多
A study about the action control of a dexterous mechanical gripper based on stereo-vision system was proposed. The vision-based system was used to replace the data-glove for gesture measurement. The stereo vision theo...A study about the action control of a dexterous mechanical gripper based on stereo-vision system was proposed. The vision-based system was used to replace the data-glove for gesture measurement. The stereo vision theory was applied to calculate the 3D information of the hand gesture. The information was used to generate the grasping action parameters of a 3-finger dexterous mechanical gripper. Combined with a force feedback device, a closed control loop could be constructed. The test for the precision of the algorithms and action control simulation result were shown in the paper.展开更多
In the field of medical equipment and equipment storage work, when we access accessories and equipment, due to the actual conditions, it causes low efficiency. It is often difficult to quickly and efficiently search b...In the field of medical equipment and equipment storage work, when we access accessories and equipment, due to the actual conditions, it causes low efficiency. It is often difficult to quickly and efficiently search by using simple data management software, such as excel. In order to solve the problem, our team used Python development tool to build high-performance retrieval software, which enabled the equipment custodian to maintain or redesign the database according to actual needs. Through actual verification, this system not only can greatly improve the accuracy of device access, but also has good expansion portability, which could manage various multimedia data systems.展开更多
The dynamics properties of a kind of multi-fingered robot hand is analyzed. It is pointed out that the dynamics property of this kind of multifingered robot hand in the approaching process is quite different from that...The dynamics properties of a kind of multi-fingered robot hand is analyzed. It is pointed out that the dynamics property of this kind of multifingered robot hand in the approaching process is quite different from that in the grasping process and,different control algorithm should be taken in the two process. A position-force hybrid control algorithm is proposed which is applied to the control system of the University of Science and Technology Beijing double-thumb robot hand successfully.展开更多
We present a mathematical method for acceleration workspace analysis of cooperating multi-finger robot systems using a model of point-contact with friction. A new unified formulation from dynamic equations of cooperat...We present a mathematical method for acceleration workspace analysis of cooperating multi-finger robot systems using a model of point-contact with friction. A new unified formulation from dynamic equations of cooperating multi-finger robots is derived considering the force and acceleration relationships between the fingers and the object to be handled. From the dynamic equation, maximum translational and rotational acceleration bounds of an object are calculated under given constraints of contact conditions, configurations of fingers, and bounds on the torques of joint actuators for each finger. Here, the rotational acceleration bounds can be applied as an important manipulability index when the multi-finger robot grasps an object. To verify the proposed method, we used a set of case studies with a simple multi-finger mechanism system. The achievable acceleration boundary in task space can be obtained successfully with the proposed method and the acceleration boundary depends on the configurations of fingers.展开更多
After stroke,even high-functioning individuals may experience compromised bimanual coordination and fine motor dexterity,leading to reduced functional independence.Bilateral arm training has been proposed as a promisi...After stroke,even high-functioning individuals may experience compromised bimanual coordination and fine motor dexterity,leading to reduced functional independence.Bilateral arm training has been proposed as a promising intervention to address these deficits.However,the neural basis of the impairment of functional fine motor skills and their relationship to bimanual coordination performance in stroke patients remains unclear,limiting the development of more targeted interventions.To address this gap,our study employed functional near-infrared spectroscopy to investigate cortical responses in patients after stroke as they perform functional tasks that engage fine motor control and coordination.Twenty-four high-functioning patients with ischemic stroke(7 women,17 men;mean age 64.75±10.84 years)participated in this cross-sectional observational study and completed four subtasks from the Purdue Pegboard Test,which measures unimanual and bimanual finger and hand dexterity.We found significant bilateral activation of the sensorimotor cortices during all Purdue Pegboard Test subtasks,with bimanual tasks inducing higher cortical activation than the assembly subtask.Importantly,patients with better bimanual coordination exhibited lower cortical activation during the other three Purdue Pegboard Test subtasks.Notably,the observed neural response patterns varied depending on the specific subtask.In the unaffected hand task,the differences were primarily observed in the ipsilesional hemisphere.In contrast,the bilateral sensorimotor cortices and the contralesional hemisphere played a more prominent role in the bimanual task and assembly task,respectively.While significant correlations were found between cortical activation and unimanual tasks,no significant correlations were observed with bimanual tasks.This study provides insights into the neural basis of bimanual coordination and fine motor skills in high-functioning patients after stroke,highlighting task-dependent neural responses.The findings also suggest that patients who exhibit better bimanual performance demonstrate more efficient cortical activation.Therefore,incorporating bilateral arm training in post-stroke rehabilitation is important for better outcomes.The combination of functional near-infrared spectroscopy with functional motor paradigms is valuable for assessing skills and developing targeted interventions in stroke rehabilitation.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)under Grant Nos.61925110,62004184 and 62234007the Key-Area Research and Development Program of Guangdong Province under Grant No.2020B010174002.
文摘The self-heating effect severely limits device performance and reliability.Although some studies have revealed the heat distribution ofβ-Ga_(2)O_(3) MOSFETs under biases,those devices all have small areas and have difficulty reflecting practical con-ditions.This work demonstrated a multi-fingerβ-Ga_(2)O_(3) MOSFET with a maximum drain current of 0.5 A.Electrical characteris-tics were measured,and the heat dissipation of the device was investigated through infrared images.The relationship between device temperature and time/bias is analyzed.
文摘Ying Chao,born in the 1990s in Jiaxing City of east China’s Zhejiang Province,is of the opinion that traditional agricultural methods cannot meet the demands of modern farming.He plans to change agricultural practices and follow the road of mechanisation after taking part in a one-year vocational training course on drones in Jiaxing Vocational and Technical College in 2021.In fact,more and more young people like Ying are applying digital technology and big data to agricultural production and rural development.And the government has laid out plans to encourage this transition.
文摘A large area multi-finger configuration power SiGe HBT device （with an emitter area of about 880μm^2） was fabricated with 2μm double-mesa technology. The maximum DC current gain β is 214. The BVCEO is up to 10V,and the BVCBO is up to 16V with a collector doping concentration of 1 × 10^17cm^-3 and collector thickness of 400nm. The device exhibits a maximum oscillation frequency fmax of 19. 3GHz and a cut-off frequency fT of 18.0GHz at a DC bias point of Ic = 30mA and VCE = 3V.MSG （maximum stable gain） is 24.5dB,and U （Mason unilateral gain） is 26.6dB at 1GHz. Due to the novel distribution layout, no notable current gain fall-off or thermal effects are observed in the I-V characteristics at high collector current.
基金Supported by the National Natural Science Foundation of China(No.51075005)the Beijing City Science and Technology Project(No.Z131100005313009)
文摘Due to the correlation and diversity of robotic kinematic dexterity indexes, the principal component analysis （PCA） and kernel principal component analysis （KPCA） based on linear dimension reduction and nonlinear dimension reduction principle could be respectively introduced into comprehensive kinematic dexterity performance evaluation of space 3R robot of different tasks. By comparing different dimension reduction effects, the KPCA method could deal more effectively with the nonlinear relationship among different single kinematic dexterity indexes, and its calculation result is more reasonable for containing more comprehensive information. KPCA＇ s calculation provides scientific basis for optimum order of robotic tasks, and furthermore a new optimization method for robotic task selection is proposed based on various performance indexes.
文摘A study about the action control of a dexterous mechanical gripper based on stereo-vision system was proposed. The vision-based system was used to replace the data-glove for gesture measurement. The stereo vision theory was applied to calculate the 3D information of the hand gesture. The information was used to generate the grasping action parameters of a 3-finger dexterous mechanical gripper. Combined with a force feedback device, a closed control loop could be constructed. The test for the precision of the algorithms and action control simulation result were shown in the paper.
文摘In the field of medical equipment and equipment storage work, when we access accessories and equipment, due to the actual conditions, it causes low efficiency. It is often difficult to quickly and efficiently search by using simple data management software, such as excel. In order to solve the problem, our team used Python development tool to build high-performance retrieval software, which enabled the equipment custodian to maintain or redesign the database according to actual needs. Through actual verification, this system not only can greatly improve the accuracy of device access, but also has good expansion portability, which could manage various multimedia data systems.
文摘The dynamics properties of a kind of multi-fingered robot hand is analyzed. It is pointed out that the dynamics property of this kind of multifingered robot hand in the approaching process is quite different from that in the grasping process and,different control algorithm should be taken in the two process. A position-force hybrid control algorithm is proposed which is applied to the control system of the University of Science and Technology Beijing double-thumb robot hand successfully.
文摘We present a mathematical method for acceleration workspace analysis of cooperating multi-finger robot systems using a model of point-contact with friction. A new unified formulation from dynamic equations of cooperating multi-finger robots is derived considering the force and acceleration relationships between the fingers and the object to be handled. From the dynamic equation, maximum translational and rotational acceleration bounds of an object are calculated under given constraints of contact conditions, configurations of fingers, and bounds on the torques of joint actuators for each finger. Here, the rotational acceleration bounds can be applied as an important manipulability index when the multi-finger robot grasps an object. To verify the proposed method, we used a set of case studies with a simple multi-finger mechanism system. The achievable acceleration boundary in task space can be obtained successfully with the proposed method and the acceleration boundary depends on the configurations of fingers.
基金supported by the National Key R&D Program of China,No.2020YFC2004202(to DX).
文摘After stroke,even high-functioning individuals may experience compromised bimanual coordination and fine motor dexterity,leading to reduced functional independence.Bilateral arm training has been proposed as a promising intervention to address these deficits.However,the neural basis of the impairment of functional fine motor skills and their relationship to bimanual coordination performance in stroke patients remains unclear,limiting the development of more targeted interventions.To address this gap,our study employed functional near-infrared spectroscopy to investigate cortical responses in patients after stroke as they perform functional tasks that engage fine motor control and coordination.Twenty-four high-functioning patients with ischemic stroke(7 women,17 men;mean age 64.75±10.84 years)participated in this cross-sectional observational study and completed four subtasks from the Purdue Pegboard Test,which measures unimanual and bimanual finger and hand dexterity.We found significant bilateral activation of the sensorimotor cortices during all Purdue Pegboard Test subtasks,with bimanual tasks inducing higher cortical activation than the assembly subtask.Importantly,patients with better bimanual coordination exhibited lower cortical activation during the other three Purdue Pegboard Test subtasks.Notably,the observed neural response patterns varied depending on the specific subtask.In the unaffected hand task,the differences were primarily observed in the ipsilesional hemisphere.In contrast,the bilateral sensorimotor cortices and the contralesional hemisphere played a more prominent role in the bimanual task and assembly task,respectively.While significant correlations were found between cortical activation and unimanual tasks,no significant correlations were observed with bimanual tasks.This study provides insights into the neural basis of bimanual coordination and fine motor skills in high-functioning patients after stroke,highlighting task-dependent neural responses.The findings also suggest that patients who exhibit better bimanual performance demonstrate more efficient cortical activation.Therefore,incorporating bilateral arm training in post-stroke rehabilitation is important for better outcomes.The combination of functional near-infrared spectroscopy with functional motor paradigms is valuable for assessing skills and developing targeted interventions in stroke rehabilitation.
