Under the"Four Specials"conditions(special environments,special tasks,special equipment,and special personnel),complex tightly-coupled human-machine systems exhibit distinct characteristics such as human-in-the-loop,frequent human-machine interactions,and significant mutual influence between humans and machines.These features lead to prominent and typical human related safety issues.Through aggregating knowledge from literature review,accident case studies,and engineering practice,this paper elaborates on the characteristics of complex tightly-coupled human-machine systems,clarifies the definition of human related safety(including its research subjects,topics,and methods),and provides a systematic analysis framework on the causes of human related safety from a whole life-cycle perspective of system development.Furthermore,theoretical hypotheses are proposed for human related safety,along with its fundamental scientific research questions and methods.

Objective Accurate speed perception is crucial for tasks such as man-controlled rendezvous and docking,and teleoperation of space manipulator.Therefore,it is necessary to conduct in-orbit experiments to explore the influence of long-term spaceflight on human speed perception characteristics.Methods The Time-to-Collision(TTC)paradigm was selected to develop experimental software,using a tablet computer for stimulus presentation.Human speed perception characteristics were evaluated based on the subjects'keystroke response data on the keyboard.Through ground-based experiments,the usability and reliability of the paradigm were explored,and the gravity internal model effect was quantitatively analyzed.Through in-orbit experiments on space station tasks,the influence of long-term spaceflight on human speed perception characteristics was further investigated.Results Under the 1G environment on the ground,the TTC paradigm has a high test-retest reliability(r>0.8),and indicators such as average deviation rate and absolute value of average deviation rate show no practice effect.In addition,ground experiments found that compared to vertical upward movement,vertical downward movement is estimated to be faster(i.e.,keystroke time is advanced),showing the existence of the gravity internal model effect.In the microgravity environment of spaceflight,there are no significant differences in average deviation rate and absolute value of average deviation rate among three stages(pre-flight,in-flight,post-flight)and seven tests,indicating that no obvious changes in astronauts'speed perception ability were found at the existing test time points and paradigms.However,the gravity internal model effect(difference between vertical downward and vertical upward)showed a trend of fading in the early stage of astronauts entering orbit.Conclusion Based on the computer screen TTC estimation paradigm,no significant changes in human speed perception ability were found during long-term spaceflight,but microgravity may weaken the human brain's gravity internal model.

Objective In this study,patients with idiopathic intracranial hypertension(IIH)were selected as a model for spaceflight-associated neuro-ocular syndrome(SANS)to conduct an eye movement manipulation intervention experiment.The aim was to explore whether eye movements have an effect on reducing the subarachnoid space around the optic nerve.Methods Twenty-three patients with IIH who met the inclusion criteria were subjected to history taking,collection of basic systemic data including age,height,weight,and blood pressure,and baseline data collection including intraocular pressure(prone)and transorbital ultrasound optic nerve sheath complex image acquisition.The subjects were then subjected to the eye movements intervention and IOP(prone)and transorbital ultrasound optic nerve sheath complex image acquisition were measured at 10 minutes,30 minutes and again 3 days after the intervention.Results The study enrolled 23 subjects with an average age of(29.58±11.25)years and a mean BMI of(28.56±6.3)kg/m2.The average cerebrospinal fluid pressure through lumbar puncture was(310.25±20.78)mmH2O.There were no significant changes in intraocular pressure at various time points before and after the eye movement exercises(P=1.000).Similarly,there were no significant changes in the diameter of the optic nerve at 3 mm and 5 mm posterior to the globe(P=1.000).However,the diameter of the optic nerve sheath at 5 mm posterior to the globe,as well as the width of the subarachnoid space of the optic nerve at 3 mm and 5 mm posterior to the globe,and the area of the subarachnoid space of the optic nerve from 3 mm to 5 mm posterior to the globe,all decreased significantly after performing eye movement exercises for 10 minutes and 30 minutes.These measures returned to baseline levels after three days of eye movement exercises,with significant differences observed across time points(P<0.05).Specifically,compared to baseline values,the diameter of the optic nerve sheath at 5 mm posterior to the globe decreased by 0.33 mm(95%CI:0.034-0.624,P=0.02)after performing 30 minutes of eye movement exercises.Additionally,the width of the subarachnoid space of the optic nerve at 3 mm and 5 mm posterior to the globe decreased by 0.2 mm(95%CI:?0.037-0.452,P=0.034)and 0.29 mm(95%CI:?0.265-0.344,P=0.01),respectively.Finally,the area of the subarachnoid space of the optic nerve from 3 mm to 5 mm posterior to the globe decreased by 0.21 mm2(95%CI:0.155-0.762,P=0.02).Conclusion This study initially proposes an eye movement manipulation method(eye movement exercise)that can reduce the subarachnoid space gap of the optic nerve posterior to the globe,including the direction,duration,rhythm,and frequency of eye movements.It was found that regular eye movements for a certain period of time can deform the optic nerve sheath,compress the subarachnoid space of the optic nerve posterior to the globe,and narrow its gap.As the duration and frequency of eye movement exercises increase,the width or area of the subarachnoid space of the optic nerve decreases more significantly.However,eye movement exercises cannot maintain the deformation of the optic nerve sheath for a long time,and after a certain period of time,the gap of the optic nerve sheath returns to baseline levels.

Objective To address the bottlenecks in the application of wastewater biological treatment technology under space conditions,an experimental system for the biological treatment of space wastewater was constructed and its biochemical performance examined.The findings of this study will provide technical support for the biological treatment of space wastewater.Methods Based on the Membrane Aerated Biofilm Reactor(MABR)process,a biological treatment experimental system for space wastewater was constructed and conducted the continuous flow test for 77 days to investigate the performance of PVDF and PP membrane modules in the treatment of simulated air condensate.Results The results demonstrated that both membrane modules exhibited an average TOC removal rate of 90%,indicative of their effective organic matter removal capacity.In the air supply mode,the ammonia oxidation capacity was observed to be comparatively lower,whereas in the oxygen source without bubbling mode,the nitrogen oxidation rate and total nitrogen removal rate could be attained above 90%,indicating a notable degree of simultaneous nitrification and denitrification.The results demonstrated that the mode of gas supply had a significant impact on the nitrogen conversion performance.The abundance of nitrogen-converting bacteria in PP membrane module is higher than that in PVDF membrane module,indicating a better nitrogen-converting performance in PP membrane module.Conclusion The constructed wastewater biological treatment system is optimally suited for the treatment of air condensate,thereby offering a novel technical approach for space wastewater treatment.

Objective In this study,the gas exchange performance and impact patterns of microalgae culture based on hollow fiber membrane technology were investigated for the culture of space microalgae.Methods The effects of parameters and conditions such as gas flow rate,membrane area and liquid flow rate on the CO2 fixation efficiency and fixation rate of hollow fiber membrane modules were studied,and the gas exchange performance of different parameters were compared by fitting formula.Results The gas flow rate and membrane area have a significant effect on the gas exchange performance of the module.With the increase of gas flow rate,the fixation rate of CO2 increases at first and then stabilizes,and the fixation efficiency of CO2 shows a continuous downward trend;with the increase of membrane area,the fixation rate and fixation efficiency of CO2 increase significantly,while the liquid flow rate has no significant effect on the gas exchange performance of the module.The highest CO2 fixation rate was 168.24 mg/(L·h)when the membrane area was 0.3m2 and the gas flow rate was 2.0 L/min.Conclusion The use of hollow fiber membrane technology can solve the problem of two-phase flow management in the gas exchange between algae culture and atmosphere,which has a better effect on gas exchange,and can provide reference for the design of gas exchange module of space microalgae photobioreactor.

Objective Fasting hypometabolism regulation technology has broad application potential in long-term space flight and survival in extreme extraterrestrial environments.In-depth research on the substrate conversion of energy metabolism and the formation of new steady states under fasting hypometabolism will provide theoretical basis and experimental data support for formulating effective prolonged fasting application mode.Methods 30 SD rats were randomly divided into control group and fasting group(fasting for 1,2,3,and 5 days).Blood biochemical examination,qRT-PCR,and western blotting were performed to analyze the body weight,blood biochemistry,and expression changes of genes and proteins related to glucose and lipid metabolism during different fasting periods.Results Prolonged fasting significantly reduced the body weight,blood glucose,and triglyceride levels of rats;increased the blood ketone level,and replaced glucose as the main energy substance in the body.There are temporal and tissue-specific changes as a whole.Hepatic and renal gluconeogenesis play major roles respectively during different fasting periods.As the fasting time prolongs,the level of hepatic gluconeogenesis gradually decreases,the content of FFA in the blood increases,the expression level of genes related to fat synthesis decreases,fatty acid oxidation is enhanced,and the expression level of the key gene HMGCS2 for ketone body generation increases.Conclusion During prolonged fasting,there is a significant conversion of glucose-ketone energy supply substrates,and a new steady state of energy metabolism mainly supplied by ketone bodies is formed within 2-5 days of fasting.The body maintains a low metabolic state by regulating changes in key genes in pathways such as glucose and lipid metabolism.

Objective To investigate the effects of simulated-microgravity on the osteogenic differentiation,primary cilia status,cytoskeleton structure,and the YAP(Yes-associated protein)expression in primary osteoblasts.Methods Primary osteoblasts were isolated from the skull bones of neonatal Wistar rats and cultured in random positioning machine system to simulate the cellular effects of microgravity.The calcified nodules were stained with Arlizarin to assess the cellular mineralization ability,the primary cilia and cytoskeleton were detected by immunofluorescence staining of Arl13b/γ-Tubulin and α-Tubulin,respectively,and the expression of YAP was measured by western blot.Results The cellular osteogenic differentiation were markedly suppressed after treated with simulated microgravity for 24 h,and the ciliated cells decreased from(58.44±3.65)%to(15.76±1.84)%in parallel with a decline of average cilium length from(3.19±0.51)μm to(1.59±0.46)μm.In addition,simulated microgravity induced disassembly of microtubules.Notably,simulated microgravity interfered YAP expression and the inhibition of YAP into nucleus.Furthermore,knockdown of YAP expression in osteoblasts notably reduced primary cilia expression and inhibited osteogenic differentiation.Conclusion Primary cilia is a key organelle of osteoblasts in sensing microgravity and regulating osteogenic differentiation.Interference with YAP expression and inhibition of nuclear YAP entry may play an important role in the deaggregation of primary cilia induced by microgravity.

Objective To screen antidepressant-active compounds from Polygonati Rhizoma and explore their effects and possible mechanisms against depression induced by simulated weightlessness.Methods A systems pharmacology approach was used to screen potential antidepressant-active compounds and their targets from Polygonati Rhizoma.The hindlimb unloading(HLU)rat model was employed for the study.Twenty-four healthy male Sprague-Dawley rats were randomly divided into three groups:control group(administered 0.5%carboxymethylcellulose by gavage),HLU group(hindlimb unloading),and HLU+treatment group(hindlimb unloading+active compound gavage),with 8 rats in each group.After 28 days of hindlimb unloading,depressive-like behaviors in rats were evaluated using the forced swimming test and tail suspension test.Hippocampal morphology was examined with H&E staining,and GO and KEGG enrichment analyses were conducted on the targets of active compounds.Results A total of 38 active compounds were screened from Polygonati Rhizoma,among which apigenin had an oral bioavailability of 23.06%and a drug-likeness score of 0.21.Compound-target network analysis indicated that apigenin had the highest degree and betweenness centrality values,suggesting it might be the key active component with antidepressant potential in Polygonati Rhizoma.In the forced swimming and tail suspension tests,rats in the HLU group showed a significant increase in immobility time compared to the control group,indicating successful establishment of the depression model.However,compared to the HLU group,rats in the HLU plus apigenin group exhibited significantly reduced immobility time.The H&E staining results of hippocampal tissue showed a significant reduction in the number of hippocampal neurons,along with numerous shrunken neurons and small vacuoles in nerve fibers in the HLU group.In contrast,the treatment group exhibited an increased number of hippocampal neurons,with improved cellular morphology.Target enrichment analysis indicated that apigenin targets were mainly involved in the regulation of apoptosis and cancer-related signaling pathways.Conclusion Apigenin significantly improved depressive-like behaviors in rats subjected to hindlimb unloading,and it has a protective effect on hippocampal tissue.It may provide a new natural active compound for the treatment of depression caused by spaceflight-induced weightlessness.

Traditional mass measurement methods are not applicable in microgravity environments,and the main challenge for in-orbit body mass measurement technology based on inertial principles is to address the random errors brought about by the weightless environment.These include additional torques due to shifts in the center of mass,nonlinear accelerations due to non-rigid human bodies,mechanical energy consumption due to organ vibrations,and random vibrations of the measurement device itself.To address the above difficulties,the project proposes a technical scheme based on the principle of linear acceleration,designs and constructs a ground-specific air-floating experimental and simulation platform,studies key data such as motion trajectory,acceleration change,and vibration frequency amplitude during the mass measurement process,and simulates the changes in the center of mass and random vibrations of the human body in a weightless environment.The project has designed an adjustable posture bracket to adapt to changes in the center of mass,enhance body restraint,and greatly reduce shaking;it has also developed an integrated four-bar linkage motion guidance mechanism,high-precision integrated photoelectric distance measurement,and modular motion constant force measurement device to ensure the accurate measurement of acceleration and constant force data.The product has undergone simulation calculations,ground human applicability tests,and in-orbit applicability verification in the space station.Ground test results show that the device achieves a body mass measurement accuracy better than 0.5%,and the dispersion is better than 0.38%;after flight mission verification and evaluation,the in-orbit body mass measurement dispersion is less than 0.4%,which is superior to the SLAMMD,a mass measurement device of the same principle on the International Space Station,and is at the forefront internationally,achieving accurate body mass measurement.

Addressing the challenge of traditional physical/semi physical simulation methods being difficult to achieve full process and full element simulation of extravehicular activities,virtual reality technology is utilized to break through the limitations of physical environments and establish a virtual reality simulation system for extravehicular activities.Based on the application characteristics of space station extravehicular activity engineering,with the goal of improving system practicality and usability,integrating the visual immersion of virtual images,the ontology of real operation,and the consistency of virtual and real space perception,a three-dimensional scene simulation,multi-mode joystick interaction paradigm,continuous operation actions simulation of extravehicular operations,and interactive operation virtual/real space consistency method that were proposed and designed for the realistic visual perception and extravehicular operation.The system has been successfully applied to astronaut training,program validation,joint exercise,and flight control support for sixteen extravehicular activities from SZ-12 to SZ-18.The results showed that the complete reproduction of the static/dynamic realistic comprehensive scene was achieved on the ground for the human-machine operation in the entire process of extravehicular activity,and the system is an essential and important means of ground simulation for extravehicular activity.