Traditionally,passenger comfort in vehicles is perceived as being most influenced by acceleration and jerk.Consequently,the current research primarily focuses on developing control algorithms to limit the maximum acce...Traditionally,passenger comfort in vehicles is perceived as being most influenced by acceleration and jerk.Consequently,the current research primarily focuses on developing control algorithms to limit the maximum acceleration and jerk of the vehicle in order to improve passenger comfort.However,naturalistic driving studies demonstrate that such simple characteristics are insufficient for accurately evaluating passenger comfort.This study identifies motion complexity as a key factor of passenger comfort.A series of naturalistic driving studies are conducted,during which passenger comfort is assessed using a 5-point Likert scale.Moreover,a real-time passenger comfort measurement based on electromyography(EMG)and stepwise regression is proposed to facilitate seamless data collection.Time-series features representing motion complexity are then introduced to better describe passenger comfort.Hierarchical regression confirms that simple characteristics of motion are insufficient to explain passenger comfort,and shows that the proposed motion complexity features have a substantial effect on passenger comfort.Finally,a machine learning-based real-time passenger comfort estimation method is developed according to the foregoing findings.Experimental results show that the proposed method can accurately estimate passenger comfort in real-time using only vehicle motion information.The findings of this study suggest that vehicle motion complexity should be considered in future passenger comfort studies.展开更多
To enhance the robustness and real-time performance of robotic arm visual servoing in complex environments such as space,this study proposes Di FA-DETR,a modified object detection framework based on the DETR architect...To enhance the robustness and real-time performance of robotic arm visual servoing in complex environments such as space,this study proposes Di FA-DETR,a modified object detection framework based on the DETR architecture.The proposed model incorporates an improved Res Net50 Bottleneck structure with spatial dimensionality reduction and sparse interaction mechanisms,alongside a redesigned self-attention module featuring downsampling optimization and adaptive feature enhancement.A custom-annotated satellite component dataset was constructed to train and evaluate the system.Experimental results demonstrate that Di FA-DETR achieves an AP50 of 79.9%,outperforming existing DETR variants while reducing computational complexity by 31.9%and nearly doubling the inference speed.The method was further validated in a ground-based visual servoing system using an industrial robotic arm and camera setup.The system successfully tracked satellite targets under dynamic motion scenarios,maintaining millimeter-level positioning accuracy.These results confirm the feasibility and effectiveness of the proposed method in supporting future space robotic applications requiring precision tracking and fast response.展开更多
As humanity ventures deeper into space,our challenges become increasingly complex.Space medicine,once confi ned to ensuring the health and safety of astronauts on low-Earth orbit missions,is now tasked with ensuring t...As humanity ventures deeper into space,our challenges become increasingly complex.Space medicine,once confi ned to ensuring the health and safety of astronauts on low-Earth orbit missions,is now tasked with ensuring the health and safety of astronauts embarking on extended missions to the Moon,Mars,and beyond.Th e advancement of space medicine and the conduct of in-orbit medical experiments not only determine the boundaries of human exploration of the cosmos but also provide new insights that can benefi t human health on Earth.展开更多
With the intensification of lunar exploration,the failure risk caused by the adsorption of lunar dust on the spacecraft surface cannot be ignored.Therefore,three types of typical spatial solid lubrication films,namely...With the intensification of lunar exploration,the failure risk caused by the adsorption of lunar dust on the spacecraft surface cannot be ignored.Therefore,three types of typical spatial solid lubrication films,namely polytetrafluoroethylene(PTFE),amorphous carbon(a-C)and molybdenum disulfide(MoS2),were prepared as test samples.Firstly,the surface free energy parameters of the material were measured using a contact Angle measuring instrument.At the same time,atomic force microscopy(AFM)was used to quantify the adhesion of the film samples based on the lunar dust micro-adsorption model.In order to investigate the influence of the test environment,the environmental pressure was adjusted to normal pressure environment and high vacuum environment with a vacuum degree of 10−6 Pa for testing.The results indicate a positive correlation between surface energy and adhesion.As surface energy increases,molecules tend to move closer,forming a stronger attraction and thus enhancing surface adhesion.In addition,AFM was used to measure the adhesion force under atmospheric pressure and vacuum conditions,revealing that parameters measured in atmospheric environment were generally higher than those measured in vacuum,which effectively verified the existence of capillary force in the microscopic adsorption model and its influence on the adhesion effect.Through the test comparison of three groups of typical solid lubricating films,it is found that MoS2 has a lower adhesion effect than the other two groups of films,which can effectively reduce the adhesion phenomenon of lunar dust on the surface of the material,and provide suitable materials for future lunar exploration and manned lunar missions.展开更多
Unmanned Aerial Vehicle（UAV） is developing towards the direction of High Altitude Long Endurance（HALE）. This will have an important influence on the stability of its airborne electronic equipment using passive the...Unmanned Aerial Vehicle（UAV） is developing towards the direction of High Altitude Long Endurance（HALE）. This will have an important influence on the stability of its airborne electronic equipment using passive thermal management. In this paper, a multi-node transient thermal model for airborne electronic equipment is set up based on the thermal network method to predict their dynamic temperature responses under high altitude and long flight time conditions. Some relevant factors are considered into this temperature prediction model including flight environment,radiation, convection, heat conduction, etc. An experimental chamber simulating a high altitude flight environment was set up to survey the dynamic thermal responses of airborne electronic equipment in a UAV. According to the experimental measurement results, the multi-node transient thermal model is verified without consideration of the effects of flight speed. Then, a modified way about outside flight speed is added into the model to improve the temperature prediction performance. Finally, the corresponding simulation code is developed based on the proposed model. It can realize the dynamic temperature prediction of airborne electronic equipment under HALE conditions.展开更多
Two kinds of molecular sieve materials, TC-5A and PSA-5A, were produced to satisfy with special requirement of manned space flight. Their CO2 adsorption performances were investi- gated and compared through two experi...Two kinds of molecular sieve materials, TC-5A and PSA-5A, were produced to satisfy with special requirement of manned space flight. Their CO2 adsorption performances were investi- gated and compared through two experiments, the thermo gravimetric analysis （TGA） experiment and packed bed column experiment. Besides, some kinetic equations were compared according to the TGA experimental data, and their errors were analyzed. Finally, the classic linear driving force （LDF） model is improved to the new Avrami＇s model, and two models are analyzed based on the packed bed data. The TGA data shows that the CO2 loading has an approximately linear relation- ship with the CO2 concentration, and the best fit adsorption temperature range is from 283 to 303 K. The packed bed column results show that water vapor in air can affect the CO2 adsorption performance badly. The new Avrami＇s model is proved more suitable to reflect the complex adsorption mechanism for two molecular sieves. The materials are proved having much better adsorption capacity than the other adsorbents with room temperature and low CO2 concentration （≤ 1.0% in volume）, and they can meet the aerospace requirements. This work will benefit the optimal design and simulation of the air revitalization （AR） system for Chinese manned spacecraft.展开更多
The circadian clock and sleep are essential for human physiology and behavior; deregulation of circadian rhythms impairs health and performance. Circadian clocks and sleep evolved to adapt to Earth's environment, ...The circadian clock and sleep are essential for human physiology and behavior; deregulation of circadian rhythms impairs health and performance. Circadian clocks and sleep evolved to adapt to Earth's environment, which is characterized by a 24-hour light–dark cycle. Changes in gravity load, lighting and work schedules during spaceflight missions can impact circadian clocks and disrupt sleep, in turn jeopardizing the mood, cognition and performance of orbiting astronauts. In this review, we summarize our understanding of both the influence of the space environment on the circadian timing system and sleep and the impact of these changes on astronaut physiology and performance.展开更多
This study analyzed weekday shopping behavior from a home base to a destination using data from the 4th Keihanshin metropolitan area person trip survey.We first analyzed the relationships between occupation and transp...This study analyzed weekday shopping behavior from a home base to a destination using data from the 4th Keihanshin metropolitan area person trip survey.We first analyzed the relationships between occupation and transportation means,transportation means and travel time,and transportation means and duration of time at the destination.Results of a chi-square test,residual analysis,and correspondence analysis confirmed that employed persons tend to travel by cars while unemployed persons tend to travel by bus or walk.The relationship between travel time and duration of time at the destination was also revealed according to transportation means.Results of a cluster analysis then classified shopping behaviors to expose four patterns.Finally,multiple regression analyzed the degree to which certain variables were related to duration of time at the destination.Results confirmed a strong relationship between duration of time at the destination and travel time.The degree of this factor’s influence on other variables was also clarified.The value of these findings is that the relationship between travel time by means of transportation and the duration of time at the destination was clarified using statistical analysis.We then found a highly accurate equation that estimates the duration of time at a destination from the travel time.If the duration of time at a destination can be estimated,it may be possible to more accurately develop the structure of rest facilities,the number of parking lots,the degree of congestion,and so on,which can be associated with the customer’s usage behavior in a shopping site.This research in this paper contributes to the field of urban analysis and marketing by presenting a new effective method for person trip survey and analysis.展开更多
A brain-computer interface(BCI)-based electric wheelchair control system was developed, which enables the users to move the wheelchair forward or backward, and turn left or right without any pre-learning. This control...A brain-computer interface(BCI)-based electric wheelchair control system was developed, which enables the users to move the wheelchair forward or backward, and turn left or right without any pre-learning. This control system makes use of the amplitude enhancement of alpha-wave blocking in electroencephalogram(EEG) when eyes close for more than 1 s to constitute a BCI for the switch control of wheelchair movements. The system was formed by BCI control panel, data acquisition, signal processing unit and interface control circuit. Eight volunteers participated in the wheelchair control experiments according to the preset routes. The experimental results show that the mean success control rate of all the subjects was 81.3%, with the highest reaching 93.7%. When one subject's triggering time was 2.8 s, i.e., the flashing time of each cycle light was 2.8 s, the average information transfer rate was 8.10 bit/min, with the highest reaching 12.54 bit/min.展开更多
Objectives： The aim of the study is to evaluate the cognitive-enhancing effects of hydrolysate of polyga- lasaponin （HPS） on senescence accelerate mouse P8 （SAMP8） mice, an effective Alzheimer＇s disease （AD） m...Objectives： The aim of the study is to evaluate the cognitive-enhancing effects of hydrolysate of polyga- lasaponin （HPS） on senescence accelerate mouse P8 （SAMP8） mice, an effective Alzheimer＇s disease （AD） model, and to research the relevant mechanisms. Methods： The cognitive-enhancing effects of HPS on SAMP8 mice were assessed using Morris water maze （MWM） and step-through passive avoidance tests. Then N-methyl-D-aspartate （NMDA） receptor subunit expression for both the cortex and hippocampus of mice was observed using Western blot- ting. Results： HPS （25 and 50 mg/kg） improved the escape rate and decreased the escape latency and time spent in the target quadrant for the SAMP8 mice in the MWM after oral administration of HPS for 10 d. Moreover, it decreased error times in the passive avoidance tests. Western blotting showed that HPS was able to reverse the levels of NMDAR1 and NMDAR2B expression in the cortex or hippocampus of model mice. Conclusions： The present study suggested that HPS can improve cognitive deficits in SAMP8 mice, and this mechanism might be associated with NMDA receptor （NMDAR）-related pathways.展开更多
AIM： To compare the optical quality after implantation of implantable collamer lens（ICL） and wavefront-guided laser in situ keratomileusis（WG-LASIK）.METHODS： The study included 40 eyes of 22 patients with myopia...AIM： To compare the optical quality after implantation of implantable collamer lens（ICL） and wavefront-guided laser in situ keratomileusis（WG-LASIK）.METHODS： The study included 40 eyes of 22 patients with myopia who accepted ICL implantation and 40 eyes of 20 patients with myopia who received WG-LASIK. Before surgery and three months after surgery, the objective scattering index（OSI）, the values of modulation transfer function（MTF） cutoff frequency, Strehl ratio, and the Optical Quality Analysis System（OQAS） values（OVs） were accessed. The higher order aberrations（HOAs） data including coma, trefoil, spherical, 2^（nd） astigmatism and tetrafoil were also obtained. For patients with pupil size 〈6 mm, HOAs data were analyzed for 4 mm-pupil diameter. For patients with pupil size ≥6 mm, HOAs data were calculated for 6 mm-pupil diameter. Visual acuity, refraction, pupil size and intraocular pressures were also recorded.RESULTS： In both ICL and WG-LASIK group, significant improvements in visual acuities were found postoperatively, with a significant reduction in spherical equivalent（P〈 0.001）. After the ICL implantation, the OSI decreasedslightly from 2.34±1.92 to 2.24±1.18 with no statistical significance（P=0.62）. While in WG-LASIK group, the OSI significantly increased from 0.68±0.43 preoperatively to 0.91±0.53 postoperatively（Wilcoxon signed ranks test, P=0.000）. None of the mean MTF cutoff frequency, Strehl ratio, OVs showed statistically significant changes in both ICL and WG-LASIK groups. In the ICL group, there were no statistical differences in the total HOAs for either 4 mmpupil or 6 mm-pupil. In the WG-LASIK group, the HOA parameters increased significantly at 4 mm-pupil. The total ocular HOAs, coma, spherical and 2^（nd） astigmatism were 0.12±0.06, 0.06±0.03, 0.00±0.03, 0.02±0.01, respectively. After the operation, these values were increased into 0.16±0.07, 0.08±0.05,-0.04±0.04, 0.03±0.01 respectively（Wilcoxon signed ranks test, all P〈0.05）. At 6 mm-pupil, the induction of total HOAs was not statistically significant in the WG-LASIK group. CONCLUSION： ICL implantation has a less disturbance to optical quality than WG-LASIK. The OQAS is a valuable complementary measurement to the wavefront aberrometers in evaluating the optical quality.展开更多
Functional near-infrared imaging (fNIR) is a non-invasive, convenient, safe and stable imaging method to test biological state. It can obtain the biological tissue hemodynamic data, thus becoming a powerful tool to me...Functional near-infrared imaging (fNIR) is a non-invasive, convenient, safe and stable imaging method to test biological state. It can obtain the biological tissue hemodynamic data, thus becoming a powerful tool to measure brain activities, mental workload, metabolism and cognitive activities state. First of all, we introduced the characteristics and current situation of fNIR in this article. Then we focused on the applications of fNIR, discussed some existing problems and future directions, including the prospect in aerospace field. Our purpose is to give a comprehensive description of fNIR and show its potential in aerospace field.展开更多
Transcranial direct current stimulation(tDCS)is a promising method for altering cortical excitability with clinical implications.It has been increasingly used in neurodevelopmental disorders,especially attention-defic...Transcranial direct current stimulation(tDCS)is a promising method for altering cortical excitability with clinical implications.It has been increasingly used in neurodevelopmental disorders,especially attention-deficit hyperactivity disorder(ADHD),but its efficacy(based on effect size calculations),safety,and stimulation parameters have not been systematically examined.In this systematic review,we aimed to(1)explore the effectiveness of tDCS on the clinical symptoms and neuropsychological deficits of ADHD patients,(2)evaluate the safety of tDCS application,especially in children with ADHD,(3)model the electrical field intensity in the target regions based on the commonly-applied and effective versus less-effective protocols,and(4)discuss and propose advanced tDCS parameters.Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses approach,a literature search identified 14 empirical experiments investigating tDCS effects in ADHD.Partial improving effects of tDCS on cognitive deficits(response inhibition,working memory,attention,and cognitive flexibility)or clinical symptoms(e.g.,impulsivity and inattention)are reported in10 studies.No serious adverse effects are reported in 747 sessions of tDCS.The left and right dorsolateral prefrontal cortex are the regions most often targeted,and anodal tDCS the protocol most often applied.An intensity of 2 mA induced stronger electrical fields than 1 mA in adults with ADHD and was associated with significant behavioral changes.In ADHD children,however,the electrical field induced by 1 mA,which is likely larger than the electrical field induced by 1 mA in adults due to the smaller head size of children,was sufficient to result in significant behavioral change.Overall,tDCS seems to be a promising method for improving ADHD deficits.However,the clinical utility of tDCS in ADHD cannot yet be concluded and requires further systematic investigation in larger sample sizes.Cortical regions involved in ADHD pathophysiology,stimulation parameters(e.g.intensity,duration,polarity,and electrode size),and types of symptom/deficit are potential determinants of tDCS efficacy in ADHD.Developmental aspects of tDCS in childhood ADHD should be considered as well.展开更多
Serving the Stewart mechanism as a wheel-legged structure,the most outstanding superiority of the proposed wheel-legged hybrid robot(WLHR)is the active vibration isolation function during rolling on rugged terrain.How...Serving the Stewart mechanism as a wheel-legged structure,the most outstanding superiority of the proposed wheel-legged hybrid robot(WLHR)is the active vibration isolation function during rolling on rugged terrain.However,it is difficult to obtain its precise dynamic model,because of the nonlinearity and uncertainty of the heavy robot.This paper presents a dynamic control framework with a decentralized structure for single wheel-leg,position tracking based on model predictive control(MPC)and adaptive impedance module from inside to outside.Through the Newton-Euler dynamic model of the Stewart mechanism,the controller first creates a predictive model by combining Newton-Raphson iteration of forward kinematic and inverse kinematic calculation of Stewart.The actuating force naturally enables each strut to stretch and retract,thereby realizing six degrees-of-freedom(6-DOFs)position-tracking for Stewart wheel-leg.The adaptive impedance control in the outermost loop adjusts environmental impedance parameters by current position and force feedback of wheel-leg along Z-axis.This adjustment allows the robot to adequately control the desired support force tracking,isolating the robot body from vibration that is generated from unknown terrain.The availability of the proposed control methodology on a physical prototype is demonstrated by tracking a Bezier curve and active vibration isolation while the robot is rolling on decelerate strips.By comparing the proportional and integral(PI)and constant impedance controllers,better performance of the proposed algorithm was operated and evaluated through displacement and force sensors internally-installed in each cylinder,as well as an inertial measurement unit(IMU)mounted on the robot body.The proposed algorithm structure significantly enhances the control accuracy and vibration isolation capacity of parallel wheel-legged robot.展开更多
With cutting-edge technologies and considering airline human-resource-saving,a single pilot in commercial jets could be technically feasible.Investigating changes in captains’natural behaviours are initially required...With cutting-edge technologies and considering airline human-resource-saving,a single pilot in commercial jets could be technically feasible.Investigating changes in captains’natural behaviours are initially required to comprehend the specific safe human performance envelope for safeguarding single-pilot flight,particularly in high-risk situations.This paper investigates how captains’performance transforms for fixing emergencies when operating from Dual-Pilot Operations(DPO)to Single-Pilot Operations(SPO)through a physiological-based approach.Twenty pilots flew an emergency-included flight with/without first officers’assistance.The neural activities and scanning behaviours were recorded using a 32-channel Electroencephalogram(EEG)and glasses-based eye tracker,with the observation and post-experiment questionnaires to evaluate the flight operations and pilots’perception.Flying alone,there was a significantly increased cortical activity in h and b waves over the frontal,parietal,and temporal lobes during the more complicated emergencies,and pilots focused less on the primary flight display while spending significantly more time scanning the other interfaces.The physiological fluctuating patterns associated with risky operations in SPO were highlighted by cross-correlating multimodal data.The experimental-based noteworthy insights may wish to inform commercial SPO measures to lessen the persistent physiological fluctuation,assisting airlines in creating SPO-oriented intelligent flight systems to give captains adequate support for assuring safer air transportation.展开更多
A pressure-adaptive seal is developed to meet the demands of quick assembling and disassembling for an individual protection equipment in aerospace.The analysis model,which reflects the main characteristics of the sea...A pressure-adaptive seal is developed to meet the demands of quick assembling and disassembling for an individual protection equipment in aerospace.The analysis model,which reflects the main characteristics of the seal structure,is built based on the finite element method and the Roth’s theory of rubber seal,and verified by the prototype test.The influences of precompression ratio,hardness of the sealing ring rubber,and friction coefficient on the sealing performance are investigated by variable parameter method.Results show that the model can describe the essential characteristics of the pressure-adaptive seal structure,which has good follow-up to the cavity pressure to achieve the purpose of pressure self-adaptive.The leakage rate correlates negatively with the precompression ratio of the sealing ring and the hardness of the sealing ring material,while is positively related to the friction coefficient between the sealing ring and the sealing edge.The maximum contact stress on sealing surface has negative correlation with the precompression ratio of the sealing ring,and positive correlation with the hardness of the seal ring material.The damage risk of the sealing ring increases with the increases of the precompression ratio of sealing ring,hardness of sealing ring material,and friction coefficient.展开更多
Accurate assessment of mental fatigue level would improve operational safety and efficacy of astronauts for long-term space flight. Identification of neurophysiological markers can index impending overload or fatigue ...Accurate assessment of mental fatigue level would improve operational safety and efficacy of astronauts for long-term space flight. Identification of neurophysiological markers can index impending overload or fatigue before performance decrements using neuroimaging technologies. The current study utilized functional near-infrared spectroscopy (fNIR) to investigate the relationship of hemodynamic response in prefrontal cortex with changes of mental fatigue level, task performance (reaction time) during n-back working memory task and routine work task in analog space environment. Results indicated that the information entropy of hemodynamic response is related to task performance and subjective self-reported measures;the reaction time is predicted by regression analysis;and the accuracy of mental fatigue classification approaches 90%. Since fNIR is a portable, wearable and minimally intrusive methodology, it has the potential to be deployed in future space environments to monitoring mental fatigue and assessing the effort of operators in field environments.展开更多
Background: Low back pain is the most common spinal disorder among soldiers, and load carriage training(LCT) is considered the main cause. We aimed to investigate changes in the spine system of soldiers after LCT at h...Background: Low back pain is the most common spinal disorder among soldiers, and load carriage training(LCT) is considered the main cause. We aimed to investigate changes in the spine system of soldiers after LCT at high altitudes and the change trend of the lumbar spine and surrounding soft tissues under different load conditions.Methods: Magnetic resonance imaging scans of the lumbar spines of nine soldiers from plateau troops were collected and processed. We used ImageJ and Surgimap software to analyze changes in the lumbar paraspinal muscles, intervertebral discs(IVDs), intervertebral foramina, and curvature. Furthermore, the multiple linear regression equation for spine injury owing to LCT at high altitudes was established as the mathematical prediction model using SPSS Statistics version 23.0 software.Results: In the paraspinal muscles, the cross-sectional area(CSA) increased significantly from(9126.4±691.6) mm~2 to(9862.7±456.4) mm~2, and the functional CSA(FCSA) increased significantly from(8089.6±707.7) mm~2 to(8747.9±426.2) mm~2 after LCT(P<0.05);however, the FCSA/CSA was not significantly different. Regarding IVD, the total lumbar spine showed a decreasing trend after LCT with a significant difference(P<0.05). Regarding the lumbar intervertebral foramen, the percentage of the effective intervertebral foraminal area of L3/4 significantly decreased from 91.6%±2.0% to 88.1%±2.9%(P<0.05). For curvature, the lumbosacral angle after LCT(32.4°±6.8°) was significantly higher(P<0.05) than that before LCT(26.6°±5.3°), while the lumbar lordosis angle increased significantly from(24.0°±7.1°) to(30.6°±7.4°)(P<0.05). The linear regression equation of the change rate, ΔFCSA%=–0.718+23.085×load weight, was successfully established as a prediction model of spinal injury after LCT at high altitudes.Conclusion: The spinal system encountered increased muscle volume, muscle congestion, tissue edema, IVD compression, decreased effective intervertebral foramen area, and increased lumbar curvature after LCT, which revealed important pathophysiological mechanisms of lumbar spinal disorders in soldiers following short-term and high-load weight training. The injury prediction model of the spinal system confirmed that a load weight <60% of soldiers' weight cannot cause acute pathological injury after short-term LCT, providing a reference supporting the formulation of the load weight standard for LCT.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.52221005)Tsinghua-Toyota Joint Research Fund.
文摘Traditionally,passenger comfort in vehicles is perceived as being most influenced by acceleration and jerk.Consequently,the current research primarily focuses on developing control algorithms to limit the maximum acceleration and jerk of the vehicle in order to improve passenger comfort.However,naturalistic driving studies demonstrate that such simple characteristics are insufficient for accurately evaluating passenger comfort.This study identifies motion complexity as a key factor of passenger comfort.A series of naturalistic driving studies are conducted,during which passenger comfort is assessed using a 5-point Likert scale.Moreover,a real-time passenger comfort measurement based on electromyography(EMG)and stepwise regression is proposed to facilitate seamless data collection.Time-series features representing motion complexity are then introduced to better describe passenger comfort.Hierarchical regression confirms that simple characteristics of motion are insufficient to explain passenger comfort,and shows that the proposed motion complexity features have a substantial effect on passenger comfort.Finally,a machine learning-based real-time passenger comfort estimation method is developed according to the foregoing findings.Experimental results show that the proposed method can accurately estimate passenger comfort in real-time using only vehicle motion information.The findings of this study suggest that vehicle motion complexity should be considered in future passenger comfort studies.
基金supported by the Foundation of National Key Laboratory of Human Factors Engineering,China(No.HFNKL2023 WWO5)。
文摘To enhance the robustness and real-time performance of robotic arm visual servoing in complex environments such as space,this study proposes Di FA-DETR,a modified object detection framework based on the DETR architecture.The proposed model incorporates an improved Res Net50 Bottleneck structure with spatial dimensionality reduction and sparse interaction mechanisms,alongside a redesigned self-attention module featuring downsampling optimization and adaptive feature enhancement.A custom-annotated satellite component dataset was constructed to train and evaluate the system.Experimental results demonstrate that Di FA-DETR achieves an AP50 of 79.9%,outperforming existing DETR variants while reducing computational complexity by 31.9%and nearly doubling the inference speed.The method was further validated in a ground-based visual servoing system using an industrial robotic arm and camera setup.The system successfully tracked satellite targets under dynamic motion scenarios,maintaining millimeter-level positioning accuracy.These results confirm the feasibility and effectiveness of the proposed method in supporting future space robotic applications requiring precision tracking and fast response.
基金supported by the National Natural Science Foundation of China(T2192933).
文摘As humanity ventures deeper into space,our challenges become increasingly complex.Space medicine,once confi ned to ensuring the health and safety of astronauts on low-Earth orbit missions,is now tasked with ensuring the health and safety of astronauts embarking on extended missions to the Moon,Mars,and beyond.Th e advancement of space medicine and the conduct of in-orbit medical experiments not only determine the boundaries of human exploration of the cosmos but also provide new insights that can benefi t human health on Earth.
基金Supported by National Nature Science Foundation of China(Grant Nos.52205225,U2330202)The Foundation Project of China(Grant No.2023-JCJQ-JJ-0958).
文摘With the intensification of lunar exploration,the failure risk caused by the adsorption of lunar dust on the spacecraft surface cannot be ignored.Therefore,three types of typical spatial solid lubrication films,namely polytetrafluoroethylene(PTFE),amorphous carbon(a-C)and molybdenum disulfide(MoS2),were prepared as test samples.Firstly,the surface free energy parameters of the material were measured using a contact Angle measuring instrument.At the same time,atomic force microscopy(AFM)was used to quantify the adhesion of the film samples based on the lunar dust micro-adsorption model.In order to investigate the influence of the test environment,the environmental pressure was adjusted to normal pressure environment and high vacuum environment with a vacuum degree of 10−6 Pa for testing.The results indicate a positive correlation between surface energy and adhesion.As surface energy increases,molecules tend to move closer,forming a stronger attraction and thus enhancing surface adhesion.In addition,AFM was used to measure the adhesion force under atmospheric pressure and vacuum conditions,revealing that parameters measured in atmospheric environment were generally higher than those measured in vacuum,which effectively verified the existence of capillary force in the microscopic adsorption model and its influence on the adhesion effect.Through the test comparison of three groups of typical solid lubricating films,it is found that MoS2 has a lower adhesion effect than the other two groups of films,which can effectively reduce the adhesion phenomenon of lunar dust on the surface of the material,and provide suitable materials for future lunar exploration and manned lunar missions.
基金the financial support of National Key R&D Program of China (No.2017YFB1201100)
文摘Unmanned Aerial Vehicle（UAV） is developing towards the direction of High Altitude Long Endurance（HALE）. This will have an important influence on the stability of its airborne electronic equipment using passive thermal management. In this paper, a multi-node transient thermal model for airborne electronic equipment is set up based on the thermal network method to predict their dynamic temperature responses under high altitude and long flight time conditions. Some relevant factors are considered into this temperature prediction model including flight environment,radiation, convection, heat conduction, etc. An experimental chamber simulating a high altitude flight environment was set up to survey the dynamic thermal responses of airborne electronic equipment in a UAV. According to the experimental measurement results, the multi-node transient thermal model is verified without consideration of the effects of flight speed. Then, a modified way about outside flight speed is added into the model to improve the temperature prediction performance. Finally, the corresponding simulation code is developed based on the proposed model. It can realize the dynamic temperature prediction of airborne electronic equipment under HALE conditions.
基金the financial support of the Open Funding Project of National Key Laboratory of Human Factors Engineering(No.SYFD14005181K)
文摘Two kinds of molecular sieve materials, TC-5A and PSA-5A, were produced to satisfy with special requirement of manned space flight. Their CO2 adsorption performances were investi- gated and compared through two experiments, the thermo gravimetric analysis （TGA） experiment and packed bed column experiment. Besides, some kinetic equations were compared according to the TGA experimental data, and their errors were analyzed. Finally, the classic linear driving force （LDF） model is improved to the new Avrami＇s model, and two models are analyzed based on the packed bed data. The TGA data shows that the CO2 loading has an approximately linear relation- ship with the CO2 concentration, and the best fit adsorption temperature range is from 283 to 303 K. The packed bed column results show that water vapor in air can affect the CO2 adsorption performance badly. The new Avrami＇s model is proved more suitable to reflect the complex adsorption mechanism for two molecular sieves. The materials are proved having much better adsorption capacity than the other adsorbents with room temperature and low CO2 concentration （≤ 1.0% in volume）, and they can meet the aerospace requirements. This work will benefit the optimal design and simulation of the air revitalization （AR） system for Chinese manned spacecraft.
基金supported by the National Basic Program of China (2011CB711000 and 2012CB947600)the National Natural Science Foundation of China (31171119, 31171010, 31171049, 31121061, 31271164)Open Fund from Key Laboratory for Space Biosciences & Biotechnology, Northwestern Polytechnical University (2013KF1501)
文摘The circadian clock and sleep are essential for human physiology and behavior; deregulation of circadian rhythms impairs health and performance. Circadian clocks and sleep evolved to adapt to Earth's environment, which is characterized by a 24-hour light–dark cycle. Changes in gravity load, lighting and work schedules during spaceflight missions can impact circadian clocks and disrupt sleep, in turn jeopardizing the mood, cognition and performance of orbiting astronauts. In this review, we summarize our understanding of both the influence of the space environment on the circadian timing system and sleep and the impact of these changes on astronaut physiology and performance.
基金This work was supported by Kindai University under a Faculty Assistance and Development Research Grant in 2018[grant number SR09]This study was supported by Joint Research Program No.690 at Center for Spatial Information Science(CSIS),The University of Tokyo.
文摘This study analyzed weekday shopping behavior from a home base to a destination using data from the 4th Keihanshin metropolitan area person trip survey.We first analyzed the relationships between occupation and transportation means,transportation means and travel time,and transportation means and duration of time at the destination.Results of a chi-square test,residual analysis,and correspondence analysis confirmed that employed persons tend to travel by cars while unemployed persons tend to travel by bus or walk.The relationship between travel time and duration of time at the destination was also revealed according to transportation means.Results of a cluster analysis then classified shopping behaviors to expose four patterns.Finally,multiple regression analyzed the degree to which certain variables were related to duration of time at the destination.Results confirmed a strong relationship between duration of time at the destination and travel time.The degree of this factor’s influence on other variables was also clarified.The value of these findings is that the relationship between travel time by means of transportation and the duration of time at the destination was clarified using statistical analysis.We then found a highly accurate equation that estimates the duration of time at a destination from the travel time.If the duration of time at a destination can be estimated,it may be possible to more accurately develop the structure of rest facilities,the number of parking lots,the degree of congestion,and so on,which can be associated with the customer’s usage behavior in a shopping site.This research in this paper contributes to the field of urban analysis and marketing by presenting a new effective method for person trip survey and analysis.
基金Supported by the National Natural Science Foundation of China(No.81222021,No.30970875,No.90920015,No.61172008 and No.81171423)National Key Technology Research and Development Program of the Ministry of Science and Technology of China(No.2012BAI34B02)Program for New Century Excellent Talents in University of the Ministry of Education of China(No.NCET-10-0618)
文摘A brain-computer interface(BCI)-based electric wheelchair control system was developed, which enables the users to move the wheelchair forward or backward, and turn left or right without any pre-learning. This control system makes use of the amplitude enhancement of alpha-wave blocking in electroencephalogram(EEG) when eyes close for more than 1 s to constitute a BCI for the switch control of wheelchair movements. The system was formed by BCI control panel, data acquisition, signal processing unit and interface control circuit. Eight volunteers participated in the wheelchair control experiments according to the preset routes. The experimental results show that the mean success control rate of all the subjects was 81.3%, with the highest reaching 93.7%. When one subject's triggering time was 2.8 s, i.e., the flashing time of each cycle light was 2.8 s, the average information transfer rate was 8.10 bit/min, with the highest reaching 12.54 bit/min.
基金Project supported by the Medicinal Science and Technology Research Project(No.BWS11J052)the Ministry of Science and Technology of China(No.2012ZX09J12201)the Department of Science and Technology of Xinjiang Uygur Autonomous Region,China(No.201491174)
文摘Objectives： The aim of the study is to evaluate the cognitive-enhancing effects of hydrolysate of polyga- lasaponin （HPS） on senescence accelerate mouse P8 （SAMP8） mice, an effective Alzheimer＇s disease （AD） model, and to research the relevant mechanisms. Methods： The cognitive-enhancing effects of HPS on SAMP8 mice were assessed using Morris water maze （MWM） and step-through passive avoidance tests. Then N-methyl-D-aspartate （NMDA） receptor subunit expression for both the cortex and hippocampus of mice was observed using Western blot- ting. Results： HPS （25 and 50 mg/kg） improved the escape rate and decreased the escape latency and time spent in the target quadrant for the SAMP8 mice in the MWM after oral administration of HPS for 10 d. Moreover, it decreased error times in the passive avoidance tests. Western blotting showed that HPS was able to reverse the levels of NMDAR1 and NMDAR2B expression in the cortex or hippocampus of model mice. Conclusions： The present study suggested that HPS can improve cognitive deficits in SAMP8 mice, and this mechanism might be associated with NMDA receptor （NMDAR）-related pathways.
基金Supported by the Research Grant of Guangxi Natural Science Foundation(No.2015GXNSFCB139012No.2017GXNSFBA198320)the Research Grant of Guangxi Technology and Science Agency(No.Z2015316)
文摘AIM： To compare the optical quality after implantation of implantable collamer lens（ICL） and wavefront-guided laser in situ keratomileusis（WG-LASIK）.METHODS： The study included 40 eyes of 22 patients with myopia who accepted ICL implantation and 40 eyes of 20 patients with myopia who received WG-LASIK. Before surgery and three months after surgery, the objective scattering index（OSI）, the values of modulation transfer function（MTF） cutoff frequency, Strehl ratio, and the Optical Quality Analysis System（OQAS） values（OVs） were accessed. The higher order aberrations（HOAs） data including coma, trefoil, spherical, 2^（nd） astigmatism and tetrafoil were also obtained. For patients with pupil size 〈6 mm, HOAs data were analyzed for 4 mm-pupil diameter. For patients with pupil size ≥6 mm, HOAs data were calculated for 6 mm-pupil diameter. Visual acuity, refraction, pupil size and intraocular pressures were also recorded.RESULTS： In both ICL and WG-LASIK group, significant improvements in visual acuities were found postoperatively, with a significant reduction in spherical equivalent（P〈 0.001）. After the ICL implantation, the OSI decreasedslightly from 2.34±1.92 to 2.24±1.18 with no statistical significance（P=0.62）. While in WG-LASIK group, the OSI significantly increased from 0.68±0.43 preoperatively to 0.91±0.53 postoperatively（Wilcoxon signed ranks test, P=0.000）. None of the mean MTF cutoff frequency, Strehl ratio, OVs showed statistically significant changes in both ICL and WG-LASIK groups. In the ICL group, there were no statistical differences in the total HOAs for either 4 mmpupil or 6 mm-pupil. In the WG-LASIK group, the HOA parameters increased significantly at 4 mm-pupil. The total ocular HOAs, coma, spherical and 2^（nd） astigmatism were 0.12±0.06, 0.06±0.03, 0.00±0.03, 0.02±0.01, respectively. After the operation, these values were increased into 0.16±0.07, 0.08±0.05,-0.04±0.04, 0.03±0.01 respectively（Wilcoxon signed ranks test, all P〈0.05）. At 6 mm-pupil, the induction of total HOAs was not statistically significant in the WG-LASIK group. CONCLUSION： ICL implantation has a less disturbance to optical quality than WG-LASIK. The OQAS is a valuable complementary measurement to the wavefront aberrometers in evaluating the optical quality.
文摘Functional near-infrared imaging (fNIR) is a non-invasive, convenient, safe and stable imaging method to test biological state. It can obtain the biological tissue hemodynamic data, thus becoming a powerful tool to measure brain activities, mental workload, metabolism and cognitive activities state. First of all, we introduced the characteristics and current situation of fNIR in this article. Then we focused on the applications of fNIR, discussed some existing problems and future directions, including the prospect in aerospace field. Our purpose is to give a comprehensive description of fNIR and show its potential in aerospace field.
基金This review was supported by the Department of Psychology and Neurosciences,Leibniz-Institut fiir Arbeitsforschung Ministry of Science,Research and Technology,Deputy of Scholarship and Students Affairs,Iran(95000171)the German Ministry of Research and Education(German Center for Brain Stimulation grant number 01EE1403C).
文摘Transcranial direct current stimulation(tDCS)is a promising method for altering cortical excitability with clinical implications.It has been increasingly used in neurodevelopmental disorders,especially attention-deficit hyperactivity disorder(ADHD),but its efficacy(based on effect size calculations),safety,and stimulation parameters have not been systematically examined.In this systematic review,we aimed to(1)explore the effectiveness of tDCS on the clinical symptoms and neuropsychological deficits of ADHD patients,(2)evaluate the safety of tDCS application,especially in children with ADHD,(3)model the electrical field intensity in the target regions based on the commonly-applied and effective versus less-effective protocols,and(4)discuss and propose advanced tDCS parameters.Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses approach,a literature search identified 14 empirical experiments investigating tDCS effects in ADHD.Partial improving effects of tDCS on cognitive deficits(response inhibition,working memory,attention,and cognitive flexibility)or clinical symptoms(e.g.,impulsivity and inattention)are reported in10 studies.No serious adverse effects are reported in 747 sessions of tDCS.The left and right dorsolateral prefrontal cortex are the regions most often targeted,and anodal tDCS the protocol most often applied.An intensity of 2 mA induced stronger electrical fields than 1 mA in adults with ADHD and was associated with significant behavioral changes.In ADHD children,however,the electrical field induced by 1 mA,which is likely larger than the electrical field induced by 1 mA in adults due to the smaller head size of children,was sufficient to result in significant behavioral change.Overall,tDCS seems to be a promising method for improving ADHD deficits.However,the clinical utility of tDCS in ADHD cannot yet be concluded and requires further systematic investigation in larger sample sizes.Cortical regions involved in ADHD pathophysiology,stimulation parameters(e.g.intensity,duration,polarity,and electrode size),and types of symptom/deficit are potential determinants of tDCS efficacy in ADHD.Developmental aspects of tDCS in childhood ADHD should be considered as well.
基金Supported by National Natural Science Foundation of China(Grant No.61773060).
文摘Serving the Stewart mechanism as a wheel-legged structure,the most outstanding superiority of the proposed wheel-legged hybrid robot(WLHR)is the active vibration isolation function during rolling on rugged terrain.However,it is difficult to obtain its precise dynamic model,because of the nonlinearity and uncertainty of the heavy robot.This paper presents a dynamic control framework with a decentralized structure for single wheel-leg,position tracking based on model predictive control(MPC)and adaptive impedance module from inside to outside.Through the Newton-Euler dynamic model of the Stewart mechanism,the controller first creates a predictive model by combining Newton-Raphson iteration of forward kinematic and inverse kinematic calculation of Stewart.The actuating force naturally enables each strut to stretch and retract,thereby realizing six degrees-of-freedom(6-DOFs)position-tracking for Stewart wheel-leg.The adaptive impedance control in the outermost loop adjusts environmental impedance parameters by current position and force feedback of wheel-leg along Z-axis.This adjustment allows the robot to adequately control the desired support force tracking,isolating the robot body from vibration that is generated from unknown terrain.The availability of the proposed control methodology on a physical prototype is demonstrated by tracking a Bezier curve and active vibration isolation while the robot is rolling on decelerate strips.By comparing the proportional and integral(PI)and constant impedance controllers,better performance of the proposed algorithm was operated and evaluated through displacement and force sensors internally-installed in each cylinder,as well as an inertial measurement unit(IMU)mounted on the robot body.The proposed algorithm structure significantly enhances the control accuracy and vibration isolation capacity of parallel wheel-legged robot.
基金supported by the Research Committee and the Department of Aeronautical and Aviation Engineering,The Hong Kong Polytechnic University,Hong Kong SAR,China(RH1W,ZVS9,RJX2,RLPA and CE1G)Cho Yin Yiu is a recipient of the Hong Kong PhD Fellowship(Reference number:PF21-62058)This study has been granted human ethics approval from the PolyU Institutional Review Board of The Hong Kong Polytechnic University(IRB Reference Number:HSEARS20210318002).
文摘With cutting-edge technologies and considering airline human-resource-saving,a single pilot in commercial jets could be technically feasible.Investigating changes in captains’natural behaviours are initially required to comprehend the specific safe human performance envelope for safeguarding single-pilot flight,particularly in high-risk situations.This paper investigates how captains’performance transforms for fixing emergencies when operating from Dual-Pilot Operations(DPO)to Single-Pilot Operations(SPO)through a physiological-based approach.Twenty pilots flew an emergency-included flight with/without first officers’assistance.The neural activities and scanning behaviours were recorded using a 32-channel Electroencephalogram(EEG)and glasses-based eye tracker,with the observation and post-experiment questionnaires to evaluate the flight operations and pilots’perception.Flying alone,there was a significantly increased cortical activity in h and b waves over the frontal,parietal,and temporal lobes during the more complicated emergencies,and pilots focused less on the primary flight display while spending significantly more time scanning the other interfaces.The physiological fluctuating patterns associated with risky operations in SPO were highlighted by cross-correlating multimodal data.The experimental-based noteworthy insights may wish to inform commercial SPO measures to lessen the persistent physiological fluctuation,assisting airlines in creating SPO-oriented intelligent flight systems to give captains adequate support for assuring safer air transportation.
文摘A pressure-adaptive seal is developed to meet the demands of quick assembling and disassembling for an individual protection equipment in aerospace.The analysis model,which reflects the main characteristics of the seal structure,is built based on the finite element method and the Roth’s theory of rubber seal,and verified by the prototype test.The influences of precompression ratio,hardness of the sealing ring rubber,and friction coefficient on the sealing performance are investigated by variable parameter method.Results show that the model can describe the essential characteristics of the pressure-adaptive seal structure,which has good follow-up to the cavity pressure to achieve the purpose of pressure self-adaptive.The leakage rate correlates negatively with the precompression ratio of the sealing ring and the hardness of the sealing ring material,while is positively related to the friction coefficient between the sealing ring and the sealing edge.The maximum contact stress on sealing surface has negative correlation with the precompression ratio of the sealing ring,and positive correlation with the hardness of the seal ring material.The damage risk of the sealing ring increases with the increases of the precompression ratio of sealing ring,hardness of sealing ring material,and friction coefficient.
文摘Accurate assessment of mental fatigue level would improve operational safety and efficacy of astronauts for long-term space flight. Identification of neurophysiological markers can index impending overload or fatigue before performance decrements using neuroimaging technologies. The current study utilized functional near-infrared spectroscopy (fNIR) to investigate the relationship of hemodynamic response in prefrontal cortex with changes of mental fatigue level, task performance (reaction time) during n-back working memory task and routine work task in analog space environment. Results indicated that the information entropy of hemodynamic response is related to task performance and subjective self-reported measures;the reaction time is predicted by regression analysis;and the accuracy of mental fatigue classification approaches 90%. Since fNIR is a portable, wearable and minimally intrusive methodology, it has the potential to be deployed in future space environments to monitoring mental fatigue and assessing the effort of operators in field environments.
基金supported by the National Key Research and Development Program of China (2018YFB1307603)the National Natural Science Foundation of China (8174100706)。
文摘Background: Low back pain is the most common spinal disorder among soldiers, and load carriage training(LCT) is considered the main cause. We aimed to investigate changes in the spine system of soldiers after LCT at high altitudes and the change trend of the lumbar spine and surrounding soft tissues under different load conditions.Methods: Magnetic resonance imaging scans of the lumbar spines of nine soldiers from plateau troops were collected and processed. We used ImageJ and Surgimap software to analyze changes in the lumbar paraspinal muscles, intervertebral discs(IVDs), intervertebral foramina, and curvature. Furthermore, the multiple linear regression equation for spine injury owing to LCT at high altitudes was established as the mathematical prediction model using SPSS Statistics version 23.0 software.Results: In the paraspinal muscles, the cross-sectional area(CSA) increased significantly from(9126.4±691.6) mm~2 to(9862.7±456.4) mm~2, and the functional CSA(FCSA) increased significantly from(8089.6±707.7) mm~2 to(8747.9±426.2) mm~2 after LCT(P<0.05);however, the FCSA/CSA was not significantly different. Regarding IVD, the total lumbar spine showed a decreasing trend after LCT with a significant difference(P<0.05). Regarding the lumbar intervertebral foramen, the percentage of the effective intervertebral foraminal area of L3/4 significantly decreased from 91.6%±2.0% to 88.1%±2.9%(P<0.05). For curvature, the lumbosacral angle after LCT(32.4°±6.8°) was significantly higher(P<0.05) than that before LCT(26.6°±5.3°), while the lumbar lordosis angle increased significantly from(24.0°±7.1°) to(30.6°±7.4°)(P<0.05). The linear regression equation of the change rate, ΔFCSA%=–0.718+23.085×load weight, was successfully established as a prediction model of spinal injury after LCT at high altitudes.Conclusion: The spinal system encountered increased muscle volume, muscle congestion, tissue edema, IVD compression, decreased effective intervertebral foramen area, and increased lumbar curvature after LCT, which revealed important pathophysiological mechanisms of lumbar spinal disorders in soldiers following short-term and high-load weight training. The injury prediction model of the spinal system confirmed that a load weight <60% of soldiers' weight cannot cause acute pathological injury after short-term LCT, providing a reference supporting the formulation of the load weight standard for LCT.
