利用暖体假人对液冷服散热特性的实验研究分析

目的：利用暖体假人对液冷服的各设计参数间的内在关系进行分析,同时对液冷服的散热特性进行评价分析。方法：温度舱内暖体假人着液冷服和隔热服,在不同的温度环境和不同的暖体假人体谢率条件下,改变服装设计参数,以获得液冷服在不同实验条件下进口液温、液体流率和液冷服散热量及温度比效率间的关系。并测量冷却液进出口温度,计算液冷服的实际散热量。结果：得到了液冷服在不同实验条件下进口液温、液体流率与液冷服散热量及温度比效率间的关系和液冷服的实际散热量,为服装设计了参数的合理性提供了评价依据。结论：验证了该舱外航天服的液冷服结构参数选取较为合理,揭示了液体流率受管道结构等条件的限制,合理调节流较窄,服装国度比效率不会很高,应主要靠调节进口液温来改变服装的散热量。     

应用潜热型功能热流体的液冷服散热性能分析

目的 研究潜热型功能热流体作为液冷服(LCG)冷却液的散热性能及其影响因素.方法 基于Pennes生物热方程建立人体躯干穿着液冷服的传热模型,通过对比各种条件下的液冷服散热量、液冷服效率、冷却液温度和人体皮肤温度等参数,分析液冷服的散热性能以及人体热舒适性.结果 相比以水为冷却液,潜热型功能热流体可以显著提高液冷服散热...     

液冷服散热原理模型及其分析

目的 建立舱外航天液冷服散热的原理模型,提出其在工程设计中应遵循的基本原则。并以该原理模型为基础找到液冷服设计参数与散热量和散热效率的模化关系。方法 根据工程实际,对舱外航天液冷服散热过程进行分析。结果 液冷服各参数（管长、管径、流率和进口液温）对散热量和散热效率的影响是相互制约,相互作用的,因此各参数的合理取值是设计液冷服的关键。结论 该分析和研究对今后舱外航天液冷服的设计研制具有一定的指导意义     

舱外航天服液温调节特性试验研究

目的研究舱外服的液温调节特性与换热量的对应关系,为液温调节阀的档位设计和自动温控设计提供依据。方法舱外服置于温度舱内,尽可能减小其与环境的热流;暖体假人着液冷服穿入舱外服内,模拟人体代谢产热;舱外服加压并控制余压40 kPa。开启风机和循环泵,保证通风和液冷循环并实现设备产热;净化装置采用模拟件;利用地面设备模拟改变水升华器出口水温和冷路流量。热平衡时计算系统换热量。结果液冷换热量随着冷路水流量的增大和水升华器出口水温降低而增大;通风换热量随着冷路水流量的增大而减小,随水升华器出口水温降低而增大。结论舱外服换热量与冷路流量为非线性变化关系;舱外服液温调节阀的分流特性应分段设计;在满足最大换热量的前提下,水升华器出口水温应控制在5~7℃。     

俄美航天服回顾与展望

本文系统回顾了前苏联/俄罗斯和美国航天服的研制历史。俄美航天服的研发都基于高空压力服的技术,经历了从舱内航天服到舱内航天服与舱外航天服结合型航天服,再到舱内航天服与舱外航天服分开研制的发展路线。随着国际交流与合作的增加,俄罗斯与美国航天服的技术差异逐渐模糊,多功能和零吸氧排氮航天服是未来的重点发展方向。     

基于径向基网络的液冷服人体实验非线性模型辨识

目的建立液冷服人体实验的非线性数学模型,研究人体状态参数与液冷服入口水温的关系.方法根据人体热学特性和以前的实验数据,运用径向基（RBF）神经网络辨识建模,考察了网络对该实验系统建模的适应性.结果 RBF液冷服人体网络对人体状态和液冷服相关数据有很好的辨识能力,逼近速度快.结论 RBF网络适合本文仿真实验,有利于今后实时的自适应控制.     

舱外航天服动力学模型

目的：根据舱外航天服的实际结构，建立舱外航天服的简化的动力学模型。方法：考虑舱外航天服的各个部分的质量、惯量、各关节活动性能以及航天服施加给航天员的服装力矩，对舱外航天服各部分几何形状进行了简化，并给出了计算航天服各部分惯量的公式。采用经典Preisach模型定量地描述了航天服服装力矩迟滞曲线特性。结果：得到了考虑质量、惯量以及服装力矩的舱外航天服动力学模型。结论：本文建立的模型为进行计算机动态仿真航天员舱外活动提供了一定的基础。     

舱外航天服关节阻力矩测量与建模方法研究

目的探索更为精准的舱外航天服关节阻力矩测量和建模方法,为人-服交互运动生物力学仿真建立舱外航天服力学约束。方法分析国内外现有的关节阻力矩测量技术利弊,提出了自驱动式等速测量舱外航天服关节阻力矩的方法,并应用于服装内部有人和无人工况;采用NNOPM(RBF神经网络优化的Preisach迟滞模型)预测阻力矩随运动轨迹的变化,并与测量结果对比验证。结果内部无人和有人工况下的舱外航天服肘关节的阻力矩差异较大,肩关节的阻力矩差异较小。模型预测结果与实验测量结果一致。结论自驱动式等速测量方法和NNOPM能有效用于舱外航天服关节阻力矩的测量和建模。     

舱外航天服热控基础科学问题研究进展

本文分析了航天员舱外作业时舱外航天服热控系统中的基础科学问题,主要包括:失重环境下的人体热调节模型问题;舱外航天服自动液温调节问题;基于人体热调节模型的暖体假人热控问题。从建立多生理耦合模型、利用人工神经网络进行航天服自动热控、搭建新型暖体假人控制模型等方面对上述问题提出了解决方案以及未来发展建议。     

舱外航天服便携式生命保障系统研究进展

随着空间探索的发展,舱外航天服便携式生命保障系统必须具有更优良的性能.本文介绍了国外舱外航天服生保系统的研究进展,主要包括CO2去除和H2O去除等方面的新技术.对各种技术进行了分析、比较.探讨了舱外航天服生保系统的发展趋势.我国载人航天应该采用成熟、可靠的生保技术,同时开展再生式生保技术的研制工作.     

Model of human thermoregulation for intermittent regional cooling

INTRODUCTION: A prospective approach to save energy expenditure for a liquid cooling garment (LCG) system is to provide intermittent regional cooling (IRC) to the human body instead of continuous cooling. In order to gain insight into IRC mechanisms, a mathematical model was developed to simulate thermal interaction between the human and IRC. METHODS: Human thermoregulatory responses were simulated by a previously validated six-cylinder mathematical model. Two equations were derived from the energy balance principle to estimate LCG heat removal during ON (coolant circulation) and OFF (no coolant circulation) periods. The heat removal equations were incorporated into the boundary equations of the human model. The augmented model was used to predict human thermal responses under different IRC conditions. RESULTS AND CONCLUSIONS: The model was evaluated against experimental results with IRC in warm environments. The comparison demonstrated that the model predictions of the core temperature and mean skin temperature were reliable within root mean square deviations of +/- 0.10 degrees C and 0.44 degrees C, respectively. Simulation analysis showed that IRC has the potential to reduce power requirements. Modeling is an effective alternative to predict efficacy when actual responses cannot be attempted. A systematic approach, consisting of manikin measurements, physiological experiments, and mathematical modeling can expedite the research and development of LCG systems.     

Automatic control of thermal neutrality for space suit applications using a liquid cooling garment

BACKGROUND: Thermal control in the EVA spacesuit requires attention from the astronaut which is not always desirable or feasible. Improvements in thermal control involve implementation of an automatic thermal control system operating independently of the knowledge of the working astronaut. METHODS: A control system was designed, developed, and tested to automatically maintain a subject's thermal neutrality while wearing a liquid cooling garment (LCG). Measurement of CO2 production as an indication of metabolic rate was used as a signal to initiate the control response. Mean body temperature, computed as a function of ear canal temperature and mean skin temperature, provided feedback to account for the thermal state of subjects as they were being cooled by the LCG. The control algorithm was tested on nine subjects, six males and three females, who performed a varying 90-min metabolic profile using an arm cranking ergometer. A total of 27 tests, three for each subject, were conducted in a thermal chamber at three different environmental temperatures: 10 degrees C, 18.3 degrees C and 26.7 degrees C. RESULTS AND CONCLUSIONS: Evaluation of subjective comfort rating and quantitative energy storage indicates good performance of the controller in maintaining thermal neutrality for the subject over a wide range of environmental and transient metabolic states. Measurements of metabolic rate effectively initiated controller response, and feedback of mean body temperature to the controller proved very capable of accounting for various steady-state environmental conditions and inter-subject variability.     

Efficiency of liquid cooling garments: prediction and manikin measurement

INTRODUCTION: We studied the efficiency of liquid cooling garments (LCG) and their relationship to the insulation of outer clothing, perfusate inlet temperatures, and environmental conditions by both theoretical analysis and thermal manikin (TM) testing. METHODS: An equation to estimate LCG cooling efficiency was developed on the basis of energy balance. Cooling efficiency is a function of the thermal resistance between the TM skin and perfusate in the LCG, the thermal resistance between the environment and the perfusate, and TM skin, ambient, and perfusate temperatures. Three ensembles, a cooling vest (CV) only, CV plus a battle dress uniform (CVB), and CVB plus a battle dress overgarment (CVO), were tested on a sweating TM in dry and wet conditions. The TM surface temperature was maintained at 33 degrees C and the environment was 30 degrees C and 50% RH. The LCG heat removal from the TM was calculated using the power inputs to the TM with and without perfusate flow. RESULTS: The cooling efficiency was increased from approximately 0.45 for CV to approximately 0.70 for CVO in dry experiments and from approximately 0.53 for CV to 0.78 for CVO in wet experiments. CONCLUSION: With additional outer clothing layers, higher thermal resistances increased the rate of heat removal from the TM surface, and decreased heat gain from the ambient environment, thus increasing efficiency. The perfusate inlet temperature had minimal influence on the efficiency. The equations developed can predict cooling efficiency and heat removal rates under a wider range of environmental conditions.     

Skin temperature feedback optimizes microclimate cooling

INTRODUCTION: A novel pulsed cooling paradigm (PCskin) integrating mean skin temperature (Tsk) feedback was compared with constant cooling (CC) or time-activated pulsed cooling (PC). METHODS: Eight males exercised while wearing personal protective equipment (PPE) in a warm, dry environment (dry bulb temperature: 30 degrees C; dew-point temperature: 11 degrees C) in each of the tests. Treadmill exercise was performed (approximately 225 W x m(-2)) for 80 min. A liquid cooling garment (LCG) covered 72% of the body surface area. Core temperature (Tc), local skin temperatures, heart rate, inlet and outlet LCG perfusate temperatures, flow, and electrical power to the LCG and metabolic rate were measured during exercise. RESULTS: At 75 min of exercise Tsk was higher (33.9 +/- 0.2 degrees C) in PCskin, than in PC (33.1 +/- 0.5 degrees C) or CC (32.0 +/- 0.6 degrees C) and PC > CC. The changes in Tc and heart rate during the tests were not different. Tc at 75 min was not different among the cooling paradigms (37.6 +/- 0.3 degrees C in PCskin, 37.6 +/- 0.2 degrees C in PC and 37.6 +/- 0.2 degrees C in CC). Heart rate averaged 124 +/- 10 bpm in PCskin, 120 +/- 9 bpm in PC and 117 +/- 9 bpm in CC. Total body insulation (degrees C x W(-1) x m(-2)) was significantly reduced in PCskin (0.020 +/- 0.003) and PC (0.024 +/- 0.004) from CC (0.029 +/- 0.004). Electrical power in PCskin was reduced by 46% from CC and by 28% from PC. DISCUSSION/CONCLUSION: Real-time Tsk feedback to control cooling optimized LCG efficacy and reduced electrical power for cooling without significantly changing cardiovascular strain in exercising men wearing PPE.     

The exercise and environmental physiology of extravehicular activity

Extravehicular activity (EVA), i.e., exercise performed under unique environmental conditions, is indispensable for supporting daily living in weightlessness and for further space exploration. From 1965-1996 an average of 20 h x yr(-1) were spent performing EVA. International Space Station (ISS) assembly will require 135 h x yr(-1) of EVA, and 138 h x yr(-1) is planned for post-construction maintenance. The extravehicular mobility unit (EMU), used to protect astronauts during EVA, has a decreased pressure of 4.3 psi that could increase astronauts' risk of decompression sickness (DCS). Exercise in and repeated exposure to this hypobaria may increase the incidence of DCS, although weightlessness may attenuate this risk. Exercise thermoregulation within the EMU is poorly understood; the liquid cooling garment (LCG), worn next to the skin and designed to handle thermal stress, is manually controlled. Astronauts may become dehydrated (by up to 2.6% of body weight) during a 5-h EVA, further exacerbating the thermoregulatory challenge. The EVA is performed mainly with upper body muscles; but astronauts usually exercise at only 26-32% of their upper body maximal oxygen uptake (VO2max). For a given ground-based work task in air (as opposed to water), the submaximal VO2 is greater while VO2max and metabolic efficiency are lower during ground-based arm exercise as compared with leg exercise, and cardiovascular responses to exercise and training are also different for arms and legs. Preflight testing and training, whether conducted in air or water, must account for these differences if ground-based data are extrapolated for flight requirements. Astronauts experience deconditioning during microgravity resulting in a 10-20% loss in arm strength, a 20-30% loss in thigh strength, and decreased lower-body aerobic exercise capacity. Data from ground-based simulations of weightlessness such as bed rest induce a 6-8% decrease in upper-body strength, a 10-16% loss in thigh extensor strength, and a 15-20% decrease in lower-body aerobic exercise capacity. Changes in EVA support systems and training based on a greater understanding of the physiological aspects of exercise in the EVA environment will help to insure the health, safety, and efficiency of working astronauts.     

Human conscious response to thermal input is adjusted to changes in mean body temperature

OBJECTIVE AND DESIGN: To detect the dependable criteria of behavioural thermoregulation through modelling temperature fluctuations of individuals allowed to freely manipulate inlet water temperature of a liquid conditioning garment (LCG) during 130 min of passive exposure to -20 degrees C interspersed with a 10 min period of moderate exercise at the 65th minute using a double-blind experiment. PARTICIPANTS: Eleven volunteers (5 women; 23.40 (SD 2.09) years; BMI: 23.24 (SD 2.19)) who lacked previous experience with LCG and cold exposure experiments. RESULTS: Despite variations in core and skin temperatures, thermal comfort, thermal sensation, and mean body temperature did not fluctuate significantly over time. Participants were able to find a desired level of LCG inlet temperature within 25 minutes which was maintained at similar levels until the 65th minute of the cold exposure. During exercise, LCG inlet water temperature decreased significantly. Regression models demonstrated that mean skin temperature and change in mean body temperature were significantly associated with thermal comfort and thermal sensation. Subsequent models revealed that, although all temperature variables were associated with LCG inlet water temperature, the coefficient of determination mainly depended on mean skin temperature and change in mean body temperature. The involvement of skin temperature was anticipated as the liquid conditioning garment was in contact with the skin. CONCLUSIONS: Humans generate conscious thermoregulatory responses in resting and exercise conditions during exposures to cold environments that are aimed towards maintaining a threshold mean body temperature, rather than temperature changes in individual body regions.     

模拟失重对人体皮肤温度分布和不同部位非蒸发散热的影响

目的研究模拟失重时人体体温调节系统的改变对人体非蒸发散热的影响。方法 5名被试者 - 6°头低位卧床 7d ,采用HR -Ⅱ型医用红外热像仪测量人体体表温度的分布 ,根据体表温度计算身体各部位的非蒸发散热量及其在总散热量中所占百分比例。结果卧床中 ,人体纵向温度梯度增加 ,在卧床第 3天 ,胸 -足部位皮肤温差较对照增加 6.7℃ ;各部位散热所占全身散热比例躯干增加了近 6% ,头部增加约 2 % ,上肢散热减少 3% ,下肢减少约 5 %。结论模拟失重条件下人体不同部位散热所占比例发生变化 ,这一结果可用于舱外航天服液冷层流量分配的设计。