【摘要】：航天器密閉乘員艙內熱環(huán)境是人類進軍空間不可回避的環(huán)境要素。它不僅影響著航天員的健康和舒適，更與航天員的工作效率、物質能量流的循環(huán)密切相關。艙內熱環(huán)境對人的熱舒適性影響和其評價是航天器工程設計和航天飛行任務物質能量循環(huán)設計的關鍵環(huán)節(jié)之一。 航天飛行中失重對人體熱調節(jié)的影響主要表現(xiàn)為機體皮膚血管舒張反應能力下降和核心體溫的升高；而且自然對流的消失和低風速等飛行因素造成的機體與周圍環(huán)境熱交換能力下降，會進一步擾亂航天員的熱平衡和熱舒適。這些都可能對航天員的身心健康、工作生活以及包括艙外活動（Extravehicular activity, EVA）和應急逃逸等的航天活動產生不利影響，因而維持航天員在太空環(huán)境下，特別是長期飛行任務中的體溫恒定與熱舒適尤為重要。目前國內外載人航天器熱環(huán)境的工程設計均基于穩(wěn)態(tài)熱舒適理論，艙內空氣的流動依靠恒速通風（Artificial constant air flow, CAF）的風扇提供。一份“和平號”空間站研究總結報告指出，“失重消除了氣體自然對流，也對機體溫度的產生和維持產生了影響”，通過對和平號空間站上28個批次長期考察組駐站期間熱環(huán)境狀態(tài)進行評價，證明乘員艙普遍存在著熱環(huán)境控制不良的狀態(tài)，甚至在第23次考察任務期間由于座艙溫度過高，乘組全體人員出現(xiàn)了不同程度的體溫升高（最高體溫達37.5℃）。最近的研究發(fā)現(xiàn)，與CAF相比，自然風或仿自然風（Simulated natural air flow, SNAF）產生的動態(tài)熱舒適環(huán)境可有效增強人體的散熱和冷感覺，并改善可接受性。那么，前瞻性探索SNAF對失重狀態(tài)人體散熱和核心體溫維持的作用很有必要。 航天環(huán)境下人體熱舒適維持與調整的重要前提是客觀真實地評價熱環(huán)境的舒適性。熱舒適是人體暴露于熱環(huán)境中基于自主性體溫調節(jié)出現(xiàn)的心理感知結果，人體主觀熱反應會受生理體溫調節(jié)活動的影響。但迄今為止，主觀熱反應與生理指標之間的有效對應關系，仍未完全建立。我國現(xiàn)有的航天熱舒適評價體系主要通過主觀問卷的方式，調查航天員在軌期間的熱感覺和舒適程度，其評價結果在很大程度上會受到個體掩飾、航天心理因素、天地通訊等的限制和影響，其時效性和準確性受到一定的影響。因此，充分利用在軌的生理信息監(jiān)測資源，對人體整體熱舒適性狀態(tài)進行主客觀結合地評價，對于實時、準確地掌握航天員個體的熱舒適性及健康狀態(tài)，進而提出熱環(huán)境調節(jié)建議具有十分重要的意義。特別是對于出艙活動狀態(tài)下人體代謝負荷、健康狀態(tài)的評估，具有直接的指導價值。為此，必須開展航天器密閉艙內人體的主觀熱反應與熱效應敏感生理指標的有效對應關系研究，建立生理與主觀指標相結合的評價模型。 在環(huán)境相同的情況下，由于性別、生活地域、工作生活方式、基礎能量代謝率等個體因素的差異，人體熱舒適性感受并不一致。人體能量代謝率（Energy metabolismrate, EMR）即單位時間人體的產熱量，不僅是熱舒適評價模型和熱平衡方程中的重要個體參數，而且還是載人航天器熱環(huán)境控制工程設計的參考依據。對于飛行乘組這個有限的群體，有必要準確了解其個體的能量代謝狀態(tài)，為航天器熱環(huán)境評價和熱舒適性研究提供支持。 因此，本課題的研究目的如下：1）探索相同平均風速的SNAF是否較CAF更能有效維持模擬失重狀態(tài)人體的體溫恒定和熱舒適；2）探討密閉氣候室內人體主觀熱反應與生理反應的關系，篩選航天活動時可以反映熱舒適的敏感生理指標；3）探索建立模擬失重狀態(tài)下的雙標記水（Doubly labeled water, DLW）和改善心率（Heartrate, HR）估測EMR評價方法，分別提高航天飛行和EVA條件下EMR估測準確性。 為實現(xiàn)上述研究目的，本課題采取以下實驗方法： 首先，以30天-6°頭低位臥床模擬微重力的生理效應，以各國航天器普遍采用的熱舒適溫度23℃為背景環(huán)境溫度，7名男性受試者分別在臥床前3天和臥床第29天，暴露于對照無風環(huán)境（CON，平均風速0.05m/s，暴露時間為50min）及采用動態(tài)送風裝置產生的SNAF（=0.2m/s,30min）和CAF（=0.2m/s,30min）環(huán)境中。分析仿自然通風和恒速機械通風下，臥床狀態(tài)人體的直腸溫度（Rectal temperature,Tre）、皮膚溫度（skin temperature, Tsk）、皮膚血流傳導率（Cutaneous vascularconductance, CVC）、熱感覺投票（Thermal sensation vote, TSV）等熱反應指標的變化。 其次，在密閉氣候室設置34℃、31℃、28℃、26℃、23℃和20℃6種溫度環(huán)境。實驗以15名男性青年為受試對象，測量受試者在密閉室60min靜坐狀態(tài)下的Tsk、Tre、心率變異性（Heart rate variability, HRV）和EMR等生理指標，同時受試者填寫TSV和熱舒適投票（Thermal comfort vote, TCV）等主觀問卷，分析不同環(huán)境下的生理指標與主觀熱反應變化及兩者的相關程度； 最后，課題關注了熱舒適評價重要參數EMR的估測方法。1）以30天頭低位臥床模擬失重效應，依據DLW服用方法將21名男性受試者分為3組：15天測量周期的常規(guī)劑量法（A組）、20天測量周期的補充劑量法（B組）和1.5倍常規(guī)劑量法（C組），分析不同服用方法所測EMR的質量控制準確性，建立模擬失重狀態(tài)人體的DLW估測方法；之后按照在軌飛行任務安排，3名受試者（2名男性，1名女性）在組合體實驗艙生活工作13天。分別采用常規(guī)劑量DLW法和氧氣消耗法估測密閉艙內受試者的平均EMR，并進行結果的比較，進一步確定DLW法的有效性和準確性；2）通過測量10名男性受試者在跑臺、上肢和下肢自行車功量計三種運動方式下的EMR和HR等生理指標，，分別建立個體在不同運動方式和整體運動方式下EMR和HR的線性回歸方程，并采用驗證性實驗評價兩種方法估測EMR的準確性和估測誤差率。 本研究的主要結果和發(fā)現(xiàn)如下： 1.仿自然風對模擬失重人體熱調節(jié)的影響 1）隨著臥床時間延長，受試者靜息狀態(tài)腋溫（Axillary temperature, Taxil）逐漸升高，并在第15天后具有顯著性差異（P 0.05），其中在第20天升高了0.37℃。HR、舒張壓、收縮壓及靜息狀態(tài)氧耗量無顯著變化（P0.05）；臥床后，受試者體重減輕約1.7kg（P 0.01）；排尿量在臥床期間并未發(fā)生明顯改變，但受試者的飲水量在臥床第1天出現(xiàn)顯著下降（P 0.01）； 2）對照環(huán)境下，經過29天臥床，Tre升高了約0.18℃（P 0.05）。與臥床前對照相比，臥床后CAF通風環(huán)境下Tre仍然顯著升高，但臥床后SNAF通風環(huán)境下Tre無顯著差異（P0.05），這提示在SNAF通風暴露下，核心體溫接近臥床前對照水平； 3）與CAF相比，SNAF的湍流度（Turbulence intensity, Tu)更高，這可能提高了機體與周圍環(huán)境的對流散熱，抑制了臥床導致的Tre升高，維持了體溫的相對恒定； 4）經過29天臥床，平均皮膚溫度（Mean skin temperature,）呈下降趨勢，但無統(tǒng)計學差異。臥床后，與CAF或CON環(huán)境相比，SNAF環(huán)境下的和CVC顯著降低（P 0.05），表明SNAF對人體的散熱效果更強； 5）與臥床前相比，臥床后對照環(huán)境下的TSV未見顯著差別；臥床前，CON、SNAF和CAF氣流模式的TSV間均無顯著差異。臥床后，與CON和CAF環(huán)境相比，SNAF環(huán)境下的TSV顯著降低（P 0.05）。三種環(huán)境的TSV值均在“稍涼”和“中性”之間。2.密閉環(huán)境人體熱舒適生理研究 1）TSV隨周圍實測環(huán)境溫度而上升，并且與環(huán)境溫度相關程度很高（R2=0.99）；受試者靜坐狀態(tài)下，感到熱中性的環(huán)境溫度約25.78℃；TCV隨著環(huán)境溫度的上升呈現(xiàn)倒“U”型分布，曲線頂點對應環(huán)境溫度約為26℃； 2）Tsk和HRV隨環(huán)境溫度變化較為顯著，而Tre、額足溫差和EMR隨環(huán)境溫度變化不顯著；其中與軀干Tsk相比，肢端Tsk隨環(huán)境溫度變化更為顯著；多重檢驗表明，上臂和前臂Tsk更易受到環(huán)境溫度的影響； 3）隨著環(huán)境溫度上升，HRV的LFnorm值（低頻標準化值）和LF/HF比值呈現(xiàn)升高趨勢，HFnorm（高頻標準化值）呈現(xiàn)降低趨勢；機體EMR的最低值出現(xiàn)在熱中性環(huán)境附近； 4）Tsk、HRV、EMR和Tre分別與TSV具有顯著相關性（P 0.05），其中上臂、前臂的Tsk和與熱感覺的密切程度最高（r0.82）；受試者感到最舒適時的為33.42°C。 3.航天熱舒適環(huán)境人體能量代謝的估測方法研究 1）A組、B組和C組三種DLW服用方案獲得的人體模擬失重狀態(tài)能量代謝數據均符合質量控制準確性要求，分別適合15天至20天的飛行任務，受試者平均能量代謝率為(433.3±79.2) kJ/h~(512.5±29.2) kJ/h； 2）采用氧氣消耗法估測密閉組合體艙內受試者在全周期任務段的平均能量代謝率為417.36kJ/h，與雙標記水法估測結果（408.89kJ/h）接近；受試者活動水平介于靜息和輕度活動之間； 3）不同的運動方式下的個體EMR-HR線性關系有一定的差異性。完成同樣負荷運動時所對應的心率，跑臺最低，上肢自行車功量計最高。采用基于運動方式的估測方法，HR與EMR相關程度較不加區(qū)分的分析方法更為密切（r=0.97），而且估測誤差更低（P 0.05），這表明基于運動方式的分析可提高運動狀態(tài)下HR估測個體EMR的準確性。 本研究得到以下結論： 1）臥床模擬失重可導致人體靜息狀態(tài)下Tre的升高，這可能與皮膚血流量改變，機體表面對流、蒸發(fā)散熱降低有關。 2）與恒速機械風相比，仿自然風可更為有效地維持模擬失重狀態(tài)下的核心體溫恒定，熱感覺接近中性。仿自然風維持模擬失重狀態(tài)核心體溫的機制可能與高湍流度增加了身體與周圍環(huán)境的對流散熱有關； 3）密閉艙室環(huán)境中，人體上臂、前臂Tsk及與主觀熱反應關系最為密切，可以作為航天員空間飛行熱舒適的客觀評價指標； 4）首次在我國建立了模擬失重狀態(tài)人體EMR的DLW估測方法，其中常規(guī)劑量服用方案可滿足測試周期為15天的航天飛行任務；與補充劑量方案相比，對于測試周期為20天的飛行任務，1.5倍常規(guī)劑量服用方案更利于在空間任務中進行實施； 5）航天員運動狀態(tài)或EVA期間，基于運動方式改進的HR-EMR回歸方程，可降低心率法估測個體能量代謝的誤差，提高估測的準確性。
[Abstract]:The thermal environment in the enclosed cabin of a spacecraft is an unavoidable environmental factor for human beings to march into space. It not only affects the health and comfort of the astronauts, but also is closely related to the work efficiency of the astronauts and the cycle of material and energy flow. One of the key links in material energy cycle design.
The effects of weightlessness on human thermal regulation during space flight are mainly manifested by the decrease of skin vasodilation and the increase of core body temperature, and the loss of natural convection and the decrease of heat exchange between the body and the surrounding environment caused by low wind speed will further disturb the thermal balance and thermal comfort of astronauts. It may have adverse effects on astronauts'physical and mental health, work and life as well as space activities including extravehicular activities (EVA) and emergency escape. Therefore, it is very important to maintain the constant temperature and thermal comfort of astronauts in space environment, especially in long-term missions. The engineering design of the environment is based on the theory of steady-state thermal comfort. The flow of air in the cabin is provided by a fan with constant velocity ventilation (CAF). Evaluations of the thermal environment during the stationing of 28 batches of long-term crew on the space station proved that the crew cabin was generally in a state of poor thermal environment control, and even during the 23rd mission due to excessive cabin temperature, crew members of the crew experienced varying degrees of temperature rise (the highest body temperature reached 37.5 degrees Celsius). Recent studies It is found that compared with CAF, the dynamic thermal comfort environment produced by natural wind or Simulated natural air flow (SNAF) can effectively enhance the human body's heat dissipation and cold sensation, and improve acceptability.
The important premise of maintaining and adjusting human thermal comfort in space environment is to evaluate the comfort of thermal environment objectively and truly. The existing evaluation system of space thermal comfort in China mainly investigates the thermal sensation and comfort degree of astronauts in orbit by means of subjective questionnaires. The evaluation results will be limited and influenced to a great extent by individual disguise, space psychological factors, Space-earth communication and so on. Therefore, it is of great significance to make full use of on-orbit physiological information monitoring resources to evaluate the overall thermal comfort state of the human body both subjectively and objectively, so as to grasp the thermal comfort and health status of the astronauts in real time and accurately, and then put forward suggestions for adjusting the thermal environment. Therefore, it is necessary to study the effective relationship between the subjective thermal response and the sensitive physiological indexes of thermal effect in the spacecraft enclosed cabin, and establish an evaluation model combining physiological and subjective indexes.
In the same environment, human thermal comfort sensation is not consistent because of the differences of individual factors such as sex, living area, working life style and basic energy metabolic rate. Individual parameters are also the reference for the design of thermal environment control engineering for manned spacecraft. It is necessary to accurately understand the energy metabolism state of the flying crew, which is a limited group, so as to provide support for spacecraft thermal environment assessment and thermal comfort research.
Therefore, the research purposes of this topic are as follows: 1) to explore whether SNAF with the same average wind speed can maintain the body temperature stability and thermal comfort more effectively than CAF in simulated weightlessness; 2) to explore the relationship between the subjective thermal response and physiological response in the closed climate chamber, and to screen sensitive physiological indicators that can reflect thermal comfort in space activities; To explore the establishment of double labeled water (DLW) and improved heart rate (HR) EMR evaluation methods under simulated weightlessness, and to improve the accuracy of EMR estimation under space flight and EVA conditions, respectively.
In order to achieve the above research objectives, the following experimental methods are adopted in this study.
Firstly, the physiological effects of microgravity were simulated by 30-6 degrees head-down bed rest, and the thermal comfort temperature of 23 C, which is commonly used by spacecraft in various countries, was taken as the background environment temperature. Seven male subjects were exposed to the control windless environment (CON, average wind speed 0.05 m/s, exposure time 50 min) and the dynamic air supply device on the first 3 days and the 29th day of bed rest, respectively. SNAF (= 0.2m/s, 30min) and CAF (= 0.2m/s, 30min) were produced. Rectal temperature, Tre, skin temperature, Tsk, Cutaneous vascularity conductance (CVC), Thermal sensation vote (TS) were analyzed under natural ventilation and constant speed mechanical ventilation. V) changes in other thermal response indicators.
Secondly, six temperature environments were set up in the closed climate chamber, including 34, 31, 28, 26, 23, and 20. The physiological indexes of Tsk, Tre, HRV and EMR were measured in 15 male young people during 60 minutes of sitting in the closed climate chamber. At the same time, the subjects filled in TSV and Therm comfort voting. Subjective questionnaires such as Al comfort vote (TCV) were used to analyze the changes of physiological indices and subjective heat response in different environments and the correlation between them.
Finally, we focused on the estimation method of EMR, an important parameter of thermal comfort assessment. 1) 21 male subjects were divided into three groups according to the DLW method: 15-day routine dose method (group A), 20-day supplementary dose method (group B) and 1.5-fold routine dose method (group C) to analyze different doses. The DLW estimation method of simulated weightlessness was established by using the accuracy of quality control of EMR. Three subjects (2 males and 1 females) lived and worked for 13 days in the combined experimental cabin according to the on-orbit mission arrangement. The validity and accuracy of the DLW method were further confirmed by comparing the results. 2) By measuring the physiological indexes of EMR and HR of 10 male subjects in treadmill, bicycle ergometer of upper limb and lower limb, the linear regression equations of EMR and HR were established under different exercise modes and overall exercise modes, respectively. Confirmatory experiments evaluate two methods to estimate the accuracy of EMR and estimate the error rate.
The main findings and findings of this study are as follows:
1. the influence of imitation natural wind on the thermal regulation of simulated weightlessness
1) Axillary temperature (Taxil) in resting state increased gradually with the prolongation of bedtime, and there was a significant difference (P 0.05) after the 15th day. On the 20th day, Axillary temperature (Taxil) increased by 0.37 C. HR, diastolic blood pressure (DBP), systolic blood pressure (SBP) and oxygen consumption in resting state did not change significantly (P 0.05). Urine output did not change significantly during bed rest, but water intake decreased significantly on the first day of bed rest (P 0.01).
2) Tre increased about 0.18 ((P 0.05)) after 29 days in bed. Compared with the control group, Tre still increased significantly under CAF ventilation after bed rest, but Tre had no significant difference under SNAF ventilation after bed rest (P 0.05).
3) Compared with CAF, the Turbulence intensity (Tu) of SNAF is higher, which may increase the convective heat transfer between the body and the surrounding environment, inhibit the rise of Tre caused by bed rest, and maintain the relative constant body temperature.
4) After 29 days in bed, mean skin temperature (Mean skin temperature,) showed a downward trend, but there was no statistical difference. After lying in bed, compared with CAF or CON environment, SNAF environment and CVC significantly decreased (P 0.05), indicating that SNAF has a stronger heat dissipation effect on human body.
5) There was no significant difference in TSV between the two groups before and after bed rest; there was no significant difference in TSV between CON, SNAF and CAF before bed rest. After bed rest, TSV in SNAF was significantly lower than that in CON and CAF (P 0.05). TSV values in the three environments were between "slightly cool" and "neutral". 2. Physiologic study
1) TSV increased with the measured ambient temperature and had a high degree of correlation with ambient temperature (R2 = 0.99); the subjects felt thermal neutral ambient temperature at about 25.78 while the TCV showed an inverted U-shaped distribution with the increase of ambient temperature, and the corresponding ambient temperature at the top of the curve was about 26.
2) Tsk and HRV changed significantly with ambient temperature, while Tre, forehead-foot temperature difference and EMR did not change significantly with ambient temperature. Compared with trunk Tsk, limb Tsk changed more significantly with ambient temperature.
3) With the increase of ambient temperature, the LFnorm (low frequency standardized value) and LF / HF ratio of HRV increased, while HFnorm (high frequency standardized value) decreased. The lowest EMR value of organism appeared near the thermal neutral environment.
4) Tsk, HRV, EMR and Tre were significantly correlated with TSV (P 0.05). The Tsk of upper arm and forearm had the highest degree of intimacy with thermal sensation (r 0.82), and the subjects felt the most comfortable was 33.42 degree C.
3. estimation method of human body energy metabolism in space thermal comfort environment
1) The energy metabolism data of group A, group B and group C under three DLW regimens met the accuracy requirements of quality control, and were suitable for 15-20 days flight mission respectively. The average energy metabolism rate of subjects was (433.3 (79.2) kJ / H ~ (512.5 (29.2) kJ / h.
2) Oxygen consumption method was used to estimate the average energy metabolism rate of the subjects in the closed cabin during the whole cycle task period, which was 417.36 kJ/h, close to that of the double-labeled water method (408.89 kJ/h).
3) There is a certain difference in the EMR-HR linear relationship between individuals under different exercise modes. The heart rate corresponding to the same load exercise is the lowest on the treadmill and the highest on the bicycle ergometer. Low (P 0.05), indicating that exercise-based analysis can improve the accuracy of HR estimation of individual EMR.
The following conclusions are drawn:
1) Simulated weightlessness in bed can lead to the increase of Tre in resting state, which may be related to the change of skin blood flow, convection on the body surface, and the decrease of evaporation and heat dissipation.
2) Compared with the constant-speed mechanical wind, the simulated natural wind is more effective in maintaining the core body temperature under simulated weightlessness, and the thermal sensation is close to neutral.
3) In the enclosed cabin environment, the human upper arm, forearm Tsk and the subjective thermal response are most closely related, which can be used as an objective evaluation index of thermal comfort for astronauts in space flight.
4) The DLW estimation method of simulated weightlessness human EMR was established for the first time in China, in which the conventional dosage regimen could meet the requirements of a 15-day spaceflight mission.
【學位授予單位】：第四軍醫(yī)大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：R852

【參考文獻】

相關期刊論文 前3條

1 孫京霞,白延強;心率變異分析方法的研究進展[J];航天醫(yī)學與醫(yī)學工程;2001年03期

2 邱曼,劉武,劉鋼,文計福,劉國印,常紹勇;模擬失重條件下體溫調節(jié)的特點[J];航天醫(yī)學與醫(yī)學工程;1997年03期

3 龐誠,顧鼎良;失重因素對航天員體溫調節(jié)影響的分析[J];中國空間科學技術;2001年03期

本文編號：2241847