Soft robots have become important members of the robot community with many potential applications owing to their unique flexibility and security embedded at the material level.An increasing number of researchers are i...Soft robots have become important members of the robot community with many potential applications owing to their unique flexibility and security embedded at the material level.An increasing number of researchers are interested in their designing,manufacturing,modeling,and control.However,the dynamic simulation of soft robots is difficult owing to their infinite degrees of freedom and nonlinear characteristics that are associated with soft materials and flexible geometric structures.In this study,a novel multi-flexible body dynamic modeling and simulation technique is introduced for soft robots.Various actuators for soft robots are modeled in a virtual environment,including soft cable-driven,spring actuation,and pneumatic driving.A pneumatic driving simulation was demonstrated by the bending modules with different materials.A cable-driven soft robot arm prototype and a cylindrical soft module actuated by shape memory alley springs inspired by an octopus were manufactured and used to validate the simulation model,and the experimental results demonstrated adequate accuracy.The proposed technique can be widely applied for the modeling and dynamic simulation of other soft robots,including hybrid actuated robots and rigid-flexible coupling robots.This study also provides a fundamental framework for simulating soft mobile robots and soft manipulators in contact with the environment.展开更多
The reusable launch vehicle (RLV) presents a new avenue for reducing cost of space transportation. The landing mechanism, which provides landing support and impact absorption, is a vital component of the RLV at final ...The reusable launch vehicle (RLV) presents a new avenue for reducing cost of space transportation. The landing mechanism, which provides landing support and impact absorption, is a vital component of the RLV at final stage of recovery. This study proposes a novel legged deployable landing mechanism (LDLM) for RLV. The Watt-II six-bar mechanism is adopted to obtain the preferred configuration via the application of the linkage variation approach. To endow the proposed LDLM with advantages of large landing support region, lightweight, and reasonable linkage internal forces, a multi-objective optimization paradigm is developed. Furthermore, the optimal scale parameters for guiding the LDLM prototype design is obtained numerically using the non-dominated sorting genetic algorithm-II (NSGA-II) evolutionary algorithm. A fully-functional scaled RLV prototype is developed by integrating the gravity-governed deploying scheme to facilitate unfolding action to avoid full-range actuation, a dual-backup locking mechanism to enhance reliability of structure stiffening as fully deployed, and a shock absorber (SA) with multistage honeycomb to offer reliable shock absorbing performance. The experimental results demonstrate that the proposed LDLM is capable of providing rapid and smooth deployment (duration less than 1.5 s) with mild posture disturbance to the cabin (yaw and pitch fluctuations less than 6°). In addition, it provides satisfactory impact attenuation (acceleration peak less than 10g (g is the gravitational acceleration)) in the 0.2 m freefall test, which makes the proposed LDLM a potential alternative for developing future RLV archetype.展开更多
The electrically driven large-load-ratio six-legged robot with engineering capability can be widely used in outdoor and planetary exploration.However,due to the particularity of its parallel structure,the effective ut...The electrically driven large-load-ratio six-legged robot with engineering capability can be widely used in outdoor and planetary exploration.However,due to the particularity of its parallel structure,the effective utilization rate of energy is not high,which has become an important obstacle to its practical application.To research the power consumption characteristics of robot mobile system is beneficial to speed up it toward practicability.Based on the configuration and walking modes of robot,the mathematical model of the power consumption of mobile system is set up.In view of the tripod gait is often selected for the six-legged robots,the simplified power consumption model of mobile system under the tripod gait is established by means of reducing the dimension of the robot’s statically indeterminate problem and constructing the equal force distribution.Then,the power consumption of robot mobile system is solved under different working conditions.The variable tendencies of the power consumption of robot mobile system are respectively obtained with changes in the rotational angles of hip joint and knee joint,body height,and span.The articulated rotational zones and the ranges of body height and span are determined under the lowest power consumption.According to the walking experiments of prototype,the variable tendencies of the average power consumption of robot mobile system are respectively acquired with changes in duty ratio,body height,and span.Then,the feasibility and correctness of theory analysis are verified in the power consumption of robot mobile system.The proposed analysis method in this paper can provide a reference on the lower power research of the large-load-ratio multi-legged robots.展开更多
Legged locomotion poses significant challenges due to its nonlinear,underactuated and hybrid dynamic properties.These challenges are exacerbated by the high-speed motion and presence of aerial phases in dynamic legged...Legged locomotion poses significant challenges due to its nonlinear,underactuated and hybrid dynamic properties.These challenges are exacerbated by the high-speed motion and presence of aerial phases in dynamic legged locomotion,which highlights the requirement for online planning based on current states to cope with uncertainty and disturbances.This article proposes a real-time planning and control framework integrating motion planning and whole-body control.In the framework,the designed motion planner allows a wider body rotation range and fast reactive behaviors based on the 3-D single rigid body model.In addition,the combination of a Bézier curve based trajectory interpolator and a heuristic-based foothold planner helps generate continuous and smooth foot trajectories.The developed whole-body controller uses hierarchical quadratic optimization coupled with the full system dynamics,which ensures tasks are prioritized based on importance and joint commands are physically feasible.The performance of the framework is successfully validated in experiments with a torque-controlled quadrupedal robot for generating dynamic motions.展开更多
Effectively controlling active power-assist lower-limb exoskeletons in a human-in-the-loop manner poses a substantial chal-lenge,demanding an approach that ensures wearer autonomy while seamlessly adapting to diverse ...Effectively controlling active power-assist lower-limb exoskeletons in a human-in-the-loop manner poses a substantial chal-lenge,demanding an approach that ensures wearer autonomy while seamlessly adapting to diverse wearer needs.This paper introduces a novel hierarchical control scheme comprising five integral components:intention recognition layer,dynamics feedforward layer,force distribution layer,feedback compensation layer,as well as sensors and actuators.The intention rec-ognition layer predicts the wearer's movement and enables wearer-dominant movement through integrated force and position sensors.The force distribution layer effectively resolves the statically indeterminate problem in the context of double-foot support,showcasing flexible control modes.The dynamics feedforward layer mitigates the effect of the exoskeleton itself on movement.Meanwhile,the feedback compensation layer provides reliable closed-loop control.This approach mitigates abrupt changes in joint torques during frequent transitions between swing and stance phases by decomposed dynamics.Validating this innovative hierarchical control scheme on a hydraulic exoskeleton platform through a series of experiments,the results demonstrate its capability to deliver assistance in various modes such as stepping,squatting,and jumping while adapting seamlessly to different terrains.展开更多
Moral education is a part of talent training.Based on the analysis of the current situation of moral education in colleges and universities,this study systematically analyzes the ideological and political position of ...Moral education is a part of talent training.Based on the analysis of the current situation of moral education in colleges and universities,this study systematically analyzes the ideological and political position of local college students,their ideological and moral character,as well as moral characterization through questionnaire,interview,induction,and factor analysis;then,the existing problems in moral education are summarized as follows:the mode of moral education is rigid,students'subjectivity and subjective initiative are disregarded,spoon-feeding is common,and a single theme is used.The form and content are not relevant to students'life,and they do not stimulate students'interest in learning;in addition,the effect of moral education is not evident.Based on the above problems,this study fully considers the students'subjectivity and subjective initiative.In line with the goal of moral education in colleges and universities,the ARCS model is constructed for moral education.Through pre-class flipped classroom,problem-based learning(PBL)during classes,as well as the summary and reflection after classes,the function of moral education for self-education,self-management,self-reflection,and sel&service can be realized.展开更多
Objective:This study was aimed at investigating the correlations between heart failure onset age and all-cause mortality.Methods:The study examined 186,249 patients treated at Kailuan Group hospitals who underwent med...Objective:This study was aimed at investigating the correlations between heart failure onset age and all-cause mortality.Methods:The study examined 186,249 patients treated at Kailuan Group hospitals who underwent medical evalua-tions between 2006 and 2018.Biennial health assessments were conducted,and,as of December 31,2020,4022 heart failure instances were identified.For each patient with new-onset heart failure,four control participants were randomly selected,matched for age(within±1 year)and sex.Cox regression models were used to calculate the hazard ratios of all-cause mortality across age groups.Results:The median follow-up duration was 5.25(2.65,8.63)years.All-cause mortality occurred in 1783 partici-pants in the new-onset heart failure group and 2633 participants in in the control group.Refined multivariable Cox regression analysis revealed that patients with heart failure under 55 years of age had the highest relative mortality risk,with an HR(95%CI)6.86(4.42–10.64)with respect to their matched controls.Moreover,the relative mortality risk systematically decreased with increasing age of heart failure onset:HR(95%CI)4.70(3.73–5.92)for ages 55–64,HR(95%CI)3.23(3.73–3.81)for ages 65–74,and HR(95%CI)1.69(1.48–1.94)for 75 years or older.Conclusion:Heart failure significantly elevates the risk of all-cause mortality,and the risk is more pronounced with earlier manifestation of the condition.展开更多
A parallel wheelset suspension(PWS)designed for a heavy-duty lunar vehicle,specifically for a multi-wheeled pressurized lunar rover(MWPLR),is beneficial for adapting wheels to rough terrain and absorbing vertical vibr...A parallel wheelset suspension(PWS)designed for a heavy-duty lunar vehicle,specifically for a multi-wheeled pressurized lunar rover(MWPLR),is beneficial for adapting wheels to rough terrain and absorbing vertical vibrations passively.It is a 2-degree-of-freedom spatial parallel mechanism.However,when a lunar vehicle is driven over rough terrain,the wheelset alignment parameters of the PWS vary substantially,resulting in poor wheel-to-ground contact.This paper aims to address these problems.It first presented a PWS design approach,used simulations to confirm the correctness of the kinematic model,evaluated the initial suspension performance,and established an optimization objective.We then analyzed the suspension’s instantaneous screw axis variations as the wheelset crossed the obstacle.The results help us determine the causes and optimization variables that affect the alignment parameters.Finally,based on the kinematic and simulation analysis methods,the optimized suspension ensured that the variation in the camber,toe,and inclination angle of the steering axis would be[-1°,-1°]when the MWPLR crossed a 0.4 m high obstacle.The simulation demonstrated that the PWS improved the ride comfort of the MWPLR and that the optimized PWS enhanced the straight-line drivability and flexible steering capability of the MWPLR.PWS and its design methodology provide a design reference for other multi-wheeled rovers.展开更多
Direct laser writing(DLW)has been shown to render 3D polymeric optical components,including lenses,beam expanders,and mirrors,with submicrometer precision.However,these printed structures are limited to the refractive...Direct laser writing(DLW)has been shown to render 3D polymeric optical components,including lenses,beam expanders,and mirrors,with submicrometer precision.However,these printed structures are limited to the refractive index and dispersive properties of the photopolymer.Here,we present the subsurface controllable refractive index via beam exposure(SCRIBE)method,a lithographic approach that enables the tuning of the refractive index over a range of greater than 0.3 by performing DLW inside photoresist-filled nanoporous silicon and silica scaffolds.Adjusting the laser exposure during printing enables 3D submicron control of the polymer infilling and thus the refractive index and chromatic dispersion.Combining SCRIBE’s unprecedented index range and 3D writing accuracy has realized the world’s smallest(15μm diameter)spherical Luneburg lens operating at visible wavelengths.SCRIBE’s ability to tune the chromatic dispersion alongside the refractive index was leveraged to render achromatic doublets in a single printing step,eliminating the need for multiple photoresins and writing sequences.SCRIBE also has the potential to form multicomponent optics by cascading optical elements within a scaffold.As a demonstration,stacked focusing structures that generate photonic nanojets were fabricated inside porous silicon.Finally,an all-pass ring resonator was coupled to a subsurface 3D waveguide.The measured quality factor of 4600 at 1550 nm suggests the possibility of compact photonic systems with optical interconnects that traverse multiple planes.SCRIBE is uniquely suited for constructing such photonic integrated circuits due to its ability to integrate multiple optical components,including lenses and waveguides,without additional printed supports.展开更多
Trophoblast stem cells (TSCs), which can be derived from the trophoectoderm of a blastocyst, have the ability to sustain self-renewal and differentiate into various placental trophoblast cell types. Meanwhile, essenti...Trophoblast stem cells (TSCs), which can be derived from the trophoectoderm of a blastocyst, have the ability to sustain self-renewal and differentiate into various placental trophoblast cell types. Meanwhile, essential insights into the molecular mechanisms controlling the placental development can be gained by using TSCs as the cell model. Esrrb is a transcription factor that has been shown to play pivotal roles in both embryonic stem cell (ESC) and TSC, but the precise mechanism whereby Esrrb regulates TSC-specific transcriptome during differentiation and reprogramming is still largely unknown. In the present study, we elucidate the function of Esrrb in self-renewal and differentiation of TSCs, as well as during the induced TSC (iTSC) reprogramming. We demonstrate that the precise level of Esrrb is critical for stem state maintenance and further trophoblast differentiation of TSCs, as ectopically expressed Esrrb can partially block the rapid differentiation of TSCs in the absence of fibroblast growth factor 4. However, Esrrb depletion results in downregulation of certain key TSC-specific transcription factors, consequently causing a rapid differentiation of TSCs and these Esrrb-deficient TSCs lose the ability of hemorrhagic lesion formation in vivo. This function of Esrrb is exerted by directly binding and activating a core set of TSC-specific target genes including Cdx2, Eomes, Sox2, Fgfr4, and Bmp4. Furthermore, we show that Esrrb overexpression can facilitate the MEF-to-iTSC conversion. Moreover, Esrrb can substitute for Eomes to generate GEsTM-iTSCs. Thus, our findings provide a better understanding of the molecular mechanism of Esrrb in maintaining TSC self-renewal and during iTSC reprogramming.展开更多
The planned missions to explore the surfaces of the Moon and Mars require high exploration efficiency,thus imposing new demands on the mobility system of planetary rovers.In this paper,a design method for a high-speed...The planned missions to explore the surfaces of the Moon and Mars require high exploration efficiency,thus imposing new demands on the mobility system of planetary rovers.In this paper,a design method for a high-speed planetary rover(HPR)is proposed,and the representative configurations are modeled and simulated.First,the influence of the planetary surface environment on the design of HPRs is analyzed,and the design factors for HPRs are determined by studying a single-wheel suspension.Second,a design methodology for HPRs is proposed.The adaptive suspension mechanisms of a four-wheeled rover are synthesized using the all-wheel-attachment condition and position and orientation characteristics theory,which are expressed in the form of a graph theory for the increase in elastic components and active joints.Finally,a dynamic model is built,and a simulation is carried out for the proposed rover.The validity of the proposed method and rover is verified,thus highlighting their potential application in future planetary exploration.展开更多
As a well-explored template that captures the essential dynamical behaviors of legged locomotion on sagittal plane,the spring-loaded inverted pendulum(SLIP)model has been extensively employed in both biomechanical stu...As a well-explored template that captures the essential dynamical behaviors of legged locomotion on sagittal plane,the spring-loaded inverted pendulum(SLIP)model has been extensively employed in both biomechanical study and robotics research.Aiming at fully leveraging the merits of the SLIP model to generate the adaptive trajectories of the center of mass(CoM)with maneuverability,this study presents a novel two-layered sagittal SLIP-anchored(SSA)task space control for a monopode robot to deal with terrain irregularity.This work begins with an analytical investigation of sagittal SLIP dynamics by deriving an approximate solution with satisfactory apex prediction accuracy,and a two-layered SSA task space controller is subsequently developed for the monopode robot.The higher layer employs an analytical approximate representation of the sagittal SLIP model to form a deadbeat controller,which generates an adaptive reference trajectory for the CoM.The lower layer enforces the monopode robot to reproduce a generated CoM movement by using a task space controller to transfer the reference CoM commands into joint torques of the multi-degree of freedom monopode robot.Consequently,an adaptive hopping behavior is exhibited by the robot when traversing irregular terrain.Simulation results have demonstrated the effectiveness of the proposed method.展开更多
基金Supported by the National Natural Science Foundation of China(Grant Nos.51822502 and 91948202)the National Key Research and Development Program of China(No.2019YFB1309500)the“111 Project”(Grant No.B07018).
文摘Soft robots have become important members of the robot community with many potential applications owing to their unique flexibility and security embedded at the material level.An increasing number of researchers are interested in their designing,manufacturing,modeling,and control.However,the dynamic simulation of soft robots is difficult owing to their infinite degrees of freedom and nonlinear characteristics that are associated with soft materials and flexible geometric structures.In this study,a novel multi-flexible body dynamic modeling and simulation technique is introduced for soft robots.Various actuators for soft robots are modeled in a virtual environment,including soft cable-driven,spring actuation,and pneumatic driving.A pneumatic driving simulation was demonstrated by the bending modules with different materials.A cable-driven soft robot arm prototype and a cylindrical soft module actuated by shape memory alley springs inspired by an octopus were manufactured and used to validate the simulation model,and the experimental results demonstrated adequate accuracy.The proposed technique can be widely applied for the modeling and dynamic simulation of other soft robots,including hybrid actuated robots and rigid-flexible coupling robots.This study also provides a fundamental framework for simulating soft mobile robots and soft manipulators in contact with the environment.
文摘The reusable launch vehicle (RLV) presents a new avenue for reducing cost of space transportation. The landing mechanism, which provides landing support and impact absorption, is a vital component of the RLV at final stage of recovery. This study proposes a novel legged deployable landing mechanism (LDLM) for RLV. The Watt-II six-bar mechanism is adopted to obtain the preferred configuration via the application of the linkage variation approach. To endow the proposed LDLM with advantages of large landing support region, lightweight, and reasonable linkage internal forces, a multi-objective optimization paradigm is developed. Furthermore, the optimal scale parameters for guiding the LDLM prototype design is obtained numerically using the non-dominated sorting genetic algorithm-II (NSGA-II) evolutionary algorithm. A fully-functional scaled RLV prototype is developed by integrating the gravity-governed deploying scheme to facilitate unfolding action to avoid full-range actuation, a dual-backup locking mechanism to enhance reliability of structure stiffening as fully deployed, and a shock absorber (SA) with multistage honeycomb to offer reliable shock absorbing performance. The experimental results demonstrate that the proposed LDLM is capable of providing rapid and smooth deployment (duration less than 1.5 s) with mild posture disturbance to the cabin (yaw and pitch fluctuations less than 6°). In addition, it provides satisfactory impact attenuation (acceleration peak less than 10g (g is the gravitational acceleration)) in the 0.2 m freefall test, which makes the proposed LDLM a potential alternative for developing future RLV archetype.
基金supported in part by the National Key Research and Development Program of China(2018YFB1304903)in part by the National Natural Science Foundation of China(62003116,61925304,and 62127810)+1 种基金in part by the Project funded by China Postdoctoral Science Foundation(2021M690832)in part by the Heilongjiang Postdoctoral Fund of China(LBH-Z20138)。
文摘本文介绍了一种基于磁驱动正交悬臂探针(magnetically driven-orthogonal cantilever probes,MDOCP)的三维原子力显微镜(three-dimensional atomic force microscopy,3D-AFM)表征方法,该方法采用两个独立的三自由度纳米扫描器,能够实现探针沿可控矢量角度跟踪扫描样品表面。该3D-AFM系统还配备了高精度旋转台,可实现360°全向成像。定制的MD-OCP包含水平悬臂、垂直悬臂和磁球三部分,其中磁球可在磁场中机械驱动OCP实现激振。垂直悬臂具有一个突出的尖端,可检测深槽和具有悬垂/凹边特征的结构。首先,对MD-OCP的设计、模拟、制造和性能分析进行了描述;其次,详细介绍了探针振幅补偿和360°旋转原点定位的方法。通过使用标准AFM阶梯光栅进行对比实验,验证了所提出方法对于陡峭侧壁和拐角处细节的表征能力,其中采用了三维地形重建方法将图像整合。通过对具有微梳结构的微机电系统(MEMS)器件进行3D表征,进一步证实了所提出基于MD-OCP的3D-AFM技术的有效性。最后,该技术被用于确定微阵列芯片的关键尺寸(critical dimensions,CD)。实验结果表明,所提出的方法可以高精度地获取三维结构的CD信息,相比于难以获得侧壁信息的二维技术,在三维微纳制造检测领域具有更好的潜力。
基金National Natural Science Foundation of China(Grant No.51505335)Industry University Cooperation Collaborative Education Project of the Department of Higher Education of the Ministry of Education of China(Grant No.202102517001)Doctor Startup Projects of TUTE of China(Grant No.KYQD1806)。
文摘The electrically driven large-load-ratio six-legged robot with engineering capability can be widely used in outdoor and planetary exploration.However,due to the particularity of its parallel structure,the effective utilization rate of energy is not high,which has become an important obstacle to its practical application.To research the power consumption characteristics of robot mobile system is beneficial to speed up it toward practicability.Based on the configuration and walking modes of robot,the mathematical model of the power consumption of mobile system is set up.In view of the tripod gait is often selected for the six-legged robots,the simplified power consumption model of mobile system under the tripod gait is established by means of reducing the dimension of the robot’s statically indeterminate problem and constructing the equal force distribution.Then,the power consumption of robot mobile system is solved under different working conditions.The variable tendencies of the power consumption of robot mobile system are respectively obtained with changes in the rotational angles of hip joint and knee joint,body height,and span.The articulated rotational zones and the ranges of body height and span are determined under the lowest power consumption.According to the walking experiments of prototype,the variable tendencies of the average power consumption of robot mobile system are respectively acquired with changes in duty ratio,body height,and span.Then,the feasibility and correctness of theory analysis are verified in the power consumption of robot mobile system.The proposed analysis method in this paper can provide a reference on the lower power research of the large-load-ratio multi-legged robots.
基金supported by the China Scholarship Council under Grant[2020]06120186the Engineering and Physical Sciences Research Council[Grant number EP/V026801/2]+1 种基金the Advanced Machinery and Productivity Institute[Innovate UK project number 84646]the National Natural Science Foundation of China under Grant 52175011.
文摘Legged locomotion poses significant challenges due to its nonlinear,underactuated and hybrid dynamic properties.These challenges are exacerbated by the high-speed motion and presence of aerial phases in dynamic legged locomotion,which highlights the requirement for online planning based on current states to cope with uncertainty and disturbances.This article proposes a real-time planning and control framework integrating motion planning and whole-body control.In the framework,the designed motion planner allows a wider body rotation range and fast reactive behaviors based on the 3-D single rigid body model.In addition,the combination of a Bézier curve based trajectory interpolator and a heuristic-based foothold planner helps generate continuous and smooth foot trajectories.The developed whole-body controller uses hierarchical quadratic optimization coupled with the full system dynamics,which ensures tasks are prioritized based on importance and joint commands are physically feasible.The performance of the framework is successfully validated in experiments with a torque-controlled quadrupedal robot for generating dynamic motions.
基金supported by the China Postdoctoral Science Foundation(No.2020M672823)National Natural Science Foundation of China National Natural Science Foundation of China(No.52305072,U2013602)+3 种基金Natural Science Foundation of Hebei Province of China(No.E2022203095)Shenzhen Science and Technology Program(No.JSGG20201102152602007)Shenzhen Science and Technology Research and Development Foundation(No.JCYJ20190813171009236)Basic Scientific Research of Technology(No.JCKY2020603C009).
文摘Effectively controlling active power-assist lower-limb exoskeletons in a human-in-the-loop manner poses a substantial chal-lenge,demanding an approach that ensures wearer autonomy while seamlessly adapting to diverse wearer needs.This paper introduces a novel hierarchical control scheme comprising five integral components:intention recognition layer,dynamics feedforward layer,force distribution layer,feedback compensation layer,as well as sensors and actuators.The intention rec-ognition layer predicts the wearer's movement and enables wearer-dominant movement through integrated force and position sensors.The force distribution layer effectively resolves the statically indeterminate problem in the context of double-foot support,showcasing flexible control modes.The dynamics feedforward layer mitigates the effect of the exoskeleton itself on movement.Meanwhile,the feedback compensation layer provides reliable closed-loop control.This approach mitigates abrupt changes in joint torques during frequent transitions between swing and stance phases by decomposed dynamics.Validating this innovative hierarchical control scheme on a hydraulic exoskeleton platform through a series of experiments,the results demonstrate its capability to deliver assistance in various modes such as stepping,squatting,and jumping while adapting seamlessly to different terrains.
文摘Moral education is a part of talent training.Based on the analysis of the current situation of moral education in colleges and universities,this study systematically analyzes the ideological and political position of local college students,their ideological and moral character,as well as moral characterization through questionnaire,interview,induction,and factor analysis;then,the existing problems in moral education are summarized as follows:the mode of moral education is rigid,students'subjectivity and subjective initiative are disregarded,spoon-feeding is common,and a single theme is used.The form and content are not relevant to students'life,and they do not stimulate students'interest in learning;in addition,the effect of moral education is not evident.Based on the above problems,this study fully considers the students'subjectivity and subjective initiative.In line with the goal of moral education in colleges and universities,the ARCS model is constructed for moral education.Through pre-class flipped classroom,problem-based learning(PBL)during classes,as well as the summary and reflection after classes,the function of moral education for self-education,self-management,self-reflection,and sel&service can be realized.
文摘Objective:This study was aimed at investigating the correlations between heart failure onset age and all-cause mortality.Methods:The study examined 186,249 patients treated at Kailuan Group hospitals who underwent medical evalua-tions between 2006 and 2018.Biennial health assessments were conducted,and,as of December 31,2020,4022 heart failure instances were identified.For each patient with new-onset heart failure,four control participants were randomly selected,matched for age(within±1 year)and sex.Cox regression models were used to calculate the hazard ratios of all-cause mortality across age groups.Results:The median follow-up duration was 5.25(2.65,8.63)years.All-cause mortality occurred in 1783 partici-pants in the new-onset heart failure group and 2633 participants in in the control group.Refined multivariable Cox regression analysis revealed that patients with heart failure under 55 years of age had the highest relative mortality risk,with an HR(95%CI)6.86(4.42–10.64)with respect to their matched controls.Moreover,the relative mortality risk systematically decreased with increasing age of heart failure onset:HR(95%CI)4.70(3.73–5.92)for ages 55–64,HR(95%CI)3.23(3.73–3.81)for ages 65–74,and HR(95%CI)1.69(1.48–1.94)for 75 years or older.Conclusion:Heart failure significantly elevates the risk of all-cause mortality,and the risk is more pronounced with earlier manifestation of the condition.
基金supported by the National Natural Science Foundation of China(Grant Nos.T2388101 and U23A20614)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(Grant No.51521003)+2 种基金the“111”Project,China(Project No.B07018)the Harbin Institute of Technology(HIT)Key Project Research and Development Grant,China(Grant No.HIT2021005)the Self-Planned Task of State Key Laboratory of Robotics and System,HIT,China(Grant No.SKLRS202101A02).
文摘A parallel wheelset suspension(PWS)designed for a heavy-duty lunar vehicle,specifically for a multi-wheeled pressurized lunar rover(MWPLR),is beneficial for adapting wheels to rough terrain and absorbing vertical vibrations passively.It is a 2-degree-of-freedom spatial parallel mechanism.However,when a lunar vehicle is driven over rough terrain,the wheelset alignment parameters of the PWS vary substantially,resulting in poor wheel-to-ground contact.This paper aims to address these problems.It first presented a PWS design approach,used simulations to confirm the correctness of the kinematic model,evaluated the initial suspension performance,and established an optimization objective.We then analyzed the suspension’s instantaneous screw axis variations as the wheelset crossed the obstacle.The results help us determine the causes and optimization variables that affect the alignment parameters.Finally,based on the kinematic and simulation analysis methods,the optimized suspension ensured that the variation in the camber,toe,and inclination angle of the steering axis would be[-1°,-1°]when the MWPLR crossed a 0.4 m high obstacle.The simulation demonstrated that the PWS improved the ride comfort of the MWPLR and that the optimized PWS enhanced the straight-line drivability and flexible steering capability of the MWPLR.PWS and its design methodology provide a design reference for other multi-wheeled rovers.
基金funded by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences under Award Number DE-SC0019140(Brongersma and Braun group focal characterization collaboration)the University of Illinois at Urbana-Champaign College of Engineering Strategic Research Initiative(proof-of-concept studies)the National Science Foundation(ECCS-1935289)(Goddard group,and Braun group laser patterning).
文摘Direct laser writing(DLW)has been shown to render 3D polymeric optical components,including lenses,beam expanders,and mirrors,with submicrometer precision.However,these printed structures are limited to the refractive index and dispersive properties of the photopolymer.Here,we present the subsurface controllable refractive index via beam exposure(SCRIBE)method,a lithographic approach that enables the tuning of the refractive index over a range of greater than 0.3 by performing DLW inside photoresist-filled nanoporous silicon and silica scaffolds.Adjusting the laser exposure during printing enables 3D submicron control of the polymer infilling and thus the refractive index and chromatic dispersion.Combining SCRIBE’s unprecedented index range and 3D writing accuracy has realized the world’s smallest(15μm diameter)spherical Luneburg lens operating at visible wavelengths.SCRIBE’s ability to tune the chromatic dispersion alongside the refractive index was leveraged to render achromatic doublets in a single printing step,eliminating the need for multiple photoresins and writing sequences.SCRIBE also has the potential to form multicomponent optics by cascading optical elements within a scaffold.As a demonstration,stacked focusing structures that generate photonic nanojets were fabricated inside porous silicon.Finally,an all-pass ring resonator was coupled to a subsurface 3D waveguide.The measured quality factor of 4600 at 1550 nm suggests the possibility of compact photonic systems with optical interconnects that traverse multiple planes.SCRIBE is uniquely suited for constructing such photonic integrated circuits due to its ability to integrate multiple optical components,including lenses and waveguides,without additional printed supports.
基金the National Key R&D Program of China (2016YFA0100400)the National Natural Science Foundation of China (31721003)+6 种基金the Ministry of Science and Technology of China (2015CB964800, 2015CB964503, and 2018YFA0108900)the National Natural Science Foundation of China (81630035, 31871446, and 31771646)the Shanghai Rising-Star Program (17QA1404200)the Shanghai Chenguang Program (16CG17)the Shanghai Municipal Medical and Health Discipline Construction Projects (2017ZZ02015)National Postdoctoral Program for Innovative Talents (BX201700307)China Postdoctoral Science Foundation (2017M621527).
文摘Trophoblast stem cells (TSCs), which can be derived from the trophoectoderm of a blastocyst, have the ability to sustain self-renewal and differentiate into various placental trophoblast cell types. Meanwhile, essential insights into the molecular mechanisms controlling the placental development can be gained by using TSCs as the cell model. Esrrb is a transcription factor that has been shown to play pivotal roles in both embryonic stem cell (ESC) and TSC, but the precise mechanism whereby Esrrb regulates TSC-specific transcriptome during differentiation and reprogramming is still largely unknown. In the present study, we elucidate the function of Esrrb in self-renewal and differentiation of TSCs, as well as during the induced TSC (iTSC) reprogramming. We demonstrate that the precise level of Esrrb is critical for stem state maintenance and further trophoblast differentiation of TSCs, as ectopically expressed Esrrb can partially block the rapid differentiation of TSCs in the absence of fibroblast growth factor 4. However, Esrrb depletion results in downregulation of certain key TSC-specific transcription factors, consequently causing a rapid differentiation of TSCs and these Esrrb-deficient TSCs lose the ability of hemorrhagic lesion formation in vivo. This function of Esrrb is exerted by directly binding and activating a core set of TSC-specific target genes including Cdx2, Eomes, Sox2, Fgfr4, and Bmp4. Furthermore, we show that Esrrb overexpression can facilitate the MEF-to-iTSC conversion. Moreover, Esrrb can substitute for Eomes to generate GEsTM-iTSCs. Thus, our findings provide a better understanding of the molecular mechanism of Esrrb in maintaining TSC self-renewal and during iTSC reprogramming.
基金supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(Grant No.51521003)the National Natural Science Foundation of China(Grant Nos.51975140,52005122)+1 种基金the“111”Project of China(Grant No.B07018)the Harbin Institute of Technology Key Project Research and Development Grant of China(Grant No.HIT2021005).
文摘The planned missions to explore the surfaces of the Moon and Mars require high exploration efficiency,thus imposing new demands on the mobility system of planetary rovers.In this paper,a design method for a high-speed planetary rover(HPR)is proposed,and the representative configurations are modeled and simulated.First,the influence of the planetary surface environment on the design of HPRs is analyzed,and the design factors for HPRs are determined by studying a single-wheel suspension.Second,a design methodology for HPRs is proposed.The adaptive suspension mechanisms of a four-wheeled rover are synthesized using the all-wheel-attachment condition and position and orientation characteristics theory,which are expressed in the form of a graph theory for the increase in elastic components and active joints.Finally,a dynamic model is built,and a simulation is carried out for the proposed rover.The validity of the proposed method and rover is verified,thus highlighting their potential application in future planetary exploration.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51605115)State Key Laboratory of Robotics and System(Self-Planned Task No.SKLRS201719A)+1 种基金Heilongjiang Postdoctoral Financial Assistance(Grant No.LBH-Z16083)Natural Science Foundation of Heilongjiang Province(Grant No.QC2017052).
文摘As a well-explored template that captures the essential dynamical behaviors of legged locomotion on sagittal plane,the spring-loaded inverted pendulum(SLIP)model has been extensively employed in both biomechanical study and robotics research.Aiming at fully leveraging the merits of the SLIP model to generate the adaptive trajectories of the center of mass(CoM)with maneuverability,this study presents a novel two-layered sagittal SLIP-anchored(SSA)task space control for a monopode robot to deal with terrain irregularity.This work begins with an analytical investigation of sagittal SLIP dynamics by deriving an approximate solution with satisfactory apex prediction accuracy,and a two-layered SSA task space controller is subsequently developed for the monopode robot.The higher layer employs an analytical approximate representation of the sagittal SLIP model to form a deadbeat controller,which generates an adaptive reference trajectory for the CoM.The lower layer enforces the monopode robot to reproduce a generated CoM movement by using a task space controller to transfer the reference CoM commands into joint torques of the multi-degree of freedom monopode robot.Consequently,an adaptive hopping behavior is exhibited by the robot when traversing irregular terrain.Simulation results have demonstrated the effectiveness of the proposed method.
