Design and analysis of an advanced thermal management system for the solar close observations and proximity experiments spacecraft

In this paper,the mission and the thermal environment of the Solar Close Observations and Proximity Experiments(SCOPE)spacecraft are analyzed,and an advanced thermal management system(ATMS)is designed for it.The relationship and functions of the integrated database,the intelligent thermal control system and the efficient liquid cooling system in the ATMS are elaborated upon.For the complex thermal field regulation system and extreme space thermal environment,a modular simulation and thermal field planning method are proposed,and the feasibility of the planning algorithm is verified by numerical simulation.A solar array liquid cooling system is developed,and the system simulation results indicate that the temperatures of the solar arrays meet the requirements as the spacecraft flies by perihelion and aphelion.The advanced thermal management study supports the development of the SCOPE program and provides a reference for the thermal management in other deep-space exploration programs.

Physics-informed machine learning for metamodeling thermal comfort in non-air-conditioned buildings

There is a growing need for accurate and interpretable machine learning models of thermal comfort in buildings.Physics-informed machine learning could address this need by adding physical consistency to such models.This paper presents metamodeling of thermal comfort in non-air-conditioned buildings using physics-informed machine learning.The studied metamodel incorporated knowledge of both quasi-steady-state heat transfer and dynamic simulation results.Adaptive thermal comfort in an office located in cold and hot European climates was studied with the number of overheating hours as index.A one-at-a-time method was used to gain knowledge from dynamic simulation with TRNSYS software.This knowledge was used to filter the training data and to choose probability distributions for metamodel forms alternative to polynomial.The response of the dynamic model was positively skewed;and thus,the symmetric logistic and hyperbolic secant distributions were inappropriate and outperformed by positively skewed distributions.Incorporating physical knowledge into the metamodel was much more effective than doubling the size of the training sample.The highly flexible Kumaraswamy distribution provided the best performance with R2 equal to 0.9994 for the cold climate and 0.9975 for the hot climate.Physics-informed machine learning could combine the strength of both physics and machine learning models,and could therefore support building design with flexible,accurate and interpretable metamodels.

Adaptive thermal comfort in naturally ventilated hostels of warm and humid climatic region,Tiruchirappalli,India

Thermal comfort is an important factor in hostel buildings when the aim is to maximize the productivity of the students.Due to the extreme weather conditions,achieving thermal comfort in a hostel building in a hot and humid climate is even more difficult.Studies conducted in naturally ventilated hostel buildings in warm-humid climates involved the influence of outdoor air temperature only up to 34.4℃ and have been conducted in a specific season.In contrast,the Tiruchirappalli climate is characterized by a higher range of environmental variables.Therefore,to understand the thermal comfort conditions and usage of the environmental controls in naturally ventilated hostel buildings at the higher range of the environmental variables,a thermal comfort field study spread over one year was carried out at the National Institute of Technology,Tiruchirappalli,India,in twenty-seven hostel buildings.This study relies on field observation and thermal comfort responses from 2028 questionnaires collected from the students between September 2019 to August 2020.The analysis revealed a neutral temperature of 29.5℃ and a comfort range from 26.1℃ to 32.8℃,indicating a wide range of ther-mal adaptation than suggested by the National Building Code of India and ASHRAE standard 55.The preferred temperature was 27.8℃,indicating that students preferred a cooler environment.Acceptability with sweating conditions extended the upper limit of thermal acceptability from 31.8℃ to 32.4℃.The use of a mosquito net can increase the probability of opening a window.Results indicated that overall behavioral adjustment could extend the comfort limits.The study results would be helpful to develop guidelines and designs for naturally ventilated hostel buildings in warm and humid climates that will contribute to reducing energy demand.

Assessing the energy saving potential of using adaptive setpoint temperatures:The case study of a regional adaptive comfort model for Brazil in both the present and the future

It has been found in recent years that using setpoint temperatures based on adaptive thermal comfort models is a successful method of energy conservation.Recent studies using adaptive setpoint temperatures incorporate international models from ASHRAE Standard 55 and EN16798-1.This study,however,has instead considered a regional Brazilian adaptive comfort model.This study investigates the energy demand arising from the use of a local Brazilian comfort model in order to assess the energy implications from the use of the worldwide ASHRAE Standard 55 adaptive model and various fixed setpoint temperatures.All of Brazil’s climate zones,full air-conditioning,mixed-mode building operating modes,present-day climate change scenarios,and future scenarios—specifically Representative Concentration Pathways(RCP)2.6,4.5,and 8.5 for the years 2050 and 2100—have all been taken into account in building energy simulations.The use of adaptive setpoint temperatures based on the Brazilian local model considering mixed-mode has been found to significantly reduce energy consumption when compared to static setpoint temperatures(average energy-saving values ranging from 52%to 58%)and the ASHRAE 55 adaptive model(average values ranging from 15%to 21%).Considering climate change and the mixed-mode Brazilian model,the overall energy demand for the three groups of climatic zones(annual average outdoor temperatures≤21℃,>21 and≤25℃and>25℃)ranged between 2%decrease and 5%increase,4%and 27%increase,and 13%and 45%increase,respectively.It is concluded as a consequence that setting setpoint temperatures based on the Brazilian local adaptive comfort model is a very efficient energy-saving method.

Physiological and subjective thermal responses to heat exposure in northern and southern Chinese people

When studying the thermal adaptation of building occupants,understanding the effects of different thermal experiences on adaptation is necessary,particularly for moderate and severe heat exposure.However,this area has seen limited research.Further,skin temperature,a common parameter for quantifying thermal sensation,may insufficiently reflect the automatic thermoregulation of the human body.This study investigates the effects of long-term heat exposure on the human body using multiple physiological and subjective indexes.Two heat exposure experiments were conducted on healthy male participants from northern and southern China.Participant responses,including skin temperature,heart rate,heart rate variability,blood volume pulse(BVP),subjective thermal comfort thermal sensation,thermal acceptability,and normalized high and low frequency values were collected and compared The results indicated that the subjective responses of northern and southern participants were not significantly different;however,the subjective physiological symptoms and self-reported discomfort of the latter were less than those of the former,indicating that the southern participants had superior heat tolerance.Additionally,the physiological responses of all the participants were largely similar.However,southern participants showed slightly higher normalized high frequency and BVP values,indicating that they have more active vagus nerves and better vasodilation.They also showed a wider acceptable temperature range and better acclimation to heat exposure.Notably,the mean skin temperature could not effectively predict thermal sensation during heat exposure;this was more accurately achieved using the rate of change of skin temperature.These findings suggest that long-term thermal experiences can affect building occupants’thermal adaptability.

Thermal comfort analysis of earth-sheltered buildings: The case of meymand village, Iran

Vernacular buildings are known for their localized passive settings to provide comfortable indoor environment without air conditioning systems.One alternative is the consistent ground temperature over the year that earth-sheltered envelopes take the benefit;however,ensuring annual indoor comfort might be challenging.Thus,this research monitors the indoor thermal indicators of 22 earth-sheltered buildings in Meymand,Iran with a warmdry climate.Furthermore,the observations are used to validate the simulation results through two outdoor and indoor environmental parameters,air temperature and relative humidity during the hottest period of the year.Findings indicated that the main thermal comfort differences among case studies were mainly due to their architectural layouts where the associated variables including length,width,height,orientation,window-to-wall ratio,and shading depth were optimized through a linkage between Ladybug-tools and Genetic Algorithm(GA)concerning adaptive thermal comfort model definition and could enhance the annual thermal comfort by 31%.

Blubber fatty acid compositions in different geographic populations of finless porpoise in Chinese waters:implications for thermal adaptation

The stratification of blubber fatty acids(FAs)is a widely used strategy in marine mammals and can be influenced by many factors,including their diet,environmental temperature,and physiological status.There are 3 distinct finless porpoise species/subspecies in Chinese coastal and inland waters in a wide range from 20°N to 40°N.The biochemical stratification of the blubbers of finless porpoises in different regions may provide valuable information for understanding their environmental adaptations.The FA compositions of 4 geographic populations of finless porpoise(FP)collected from the Bohai Gulf,East China Sea,South China Sea,and Yangtze River were therefore analyzed and compared.The blubber FA compositions of finless porpoises were dominated by∑MUFAs,followed by∑SFAs and∑PUFAs,and were generally consistent with those of other cetaceans.The blubber of finless porpoises was significantly stratified with increasing levels of∑MUFAs and decreasing levels of∑SFAs and∑PUFAs from the inner to the outer layers.The 3 marine populations shared more similarities in their FA compositions and stratifications compared to the freshwater porpoises,particularly regarding the PUFAs in the inner layers,which might have been mainly influenced by the diet compositions of marine and freshwater porpoises.Contrary to what was expected,in the 3 marine populations,the SFA and MUFA levels showed opposite correlations(negative and positive,respectively)with habitat temperatures,possibly indicating an adaptation mechanism in finless porpoises characterized by a trade-off between the insulation and fluidity properties of the blubber through the adjustment of the compositions and gradients of MUFAs and SFAs across the blubber depth in response to environmental temperature/latitude changes.

Development of data-driven thermal sensation prediction model using quality-controlled databases

Predicting the thermal sensations of building occupants is challenging,but useful for indoor environment conditioning.In this study,a data-driven thermal sensation prediction model was developed using three quality-controlled thermal comfort databases.Different machine-learning algorithms were compared in terms of prediction accuracy and rationality.The model was further improved by adding categorical inputs,and building submodels and general models for different contexts.A comprehensive data-driven thermal sensation prediction model was established.The results indicate that the multilayer perceptron(MLP)algorithm achieves higher prediction accuracy and more rational results than the other four algorithms in this specific case.Labeling AC and NV scenarios,climate zones,and cooling and heating seasons can improve model performance.Establishing submodels for specific scenarios can result in better thermal sensation vote(TSV)predictions than using general models with or without labels.With 11 submodels corresponding to 11 scenarios,and three general models without labels,the final TSV prediction model achieved higher prediction accuracy,with 64.7%–90.7%fewer prediction errors(reducing SSE by 3.2–4.9)than the predicted mean vote(PMV).Possible applications of the new model are discussed.The findings of this study can help in development of simple,accurate,and rational thermal sensation prediction tools.

Studies on preparation and thermal control behavior of hybrid fillers/binary-polymer composites with positive temperature coefficient characteristic

Conductive polymer composites(CPCs) as the thermo-sensitive materials have attracted much attention in thermal control field due to their reliable self-regulating behaviors, high efficiency and mechanical flexibility. However, the development of these materials needs to manage the normal conflicting requirements, such as effective heating performance and good self-regulating capability. This paper presents a series of novel CPCs material having different amounts of hybrid fillers of multi-walled carbon nanotubes(CNTs) and carbon black(CB). The positive temperature coefficient intensity is enhanced to 105.2, and the roomtemperature resistivity is optimized to 320 ? cm. Besides, the Curie temperatures are regulated to room-temperature range by incorporating the low-melting-point blend matrix into the poly(ethylene-co-vinyl acetate)/CNTs/CB composite. The thermalcontrol experiment demonstrates that CPCs-heating elements can adjust the equilibrium temperature of controlled equipment near their Curie temperatures without any control methods. Compared with the ordinary resistor, the CPCs materials have the remarkable adaptive thermal control behavior. Furthermore, the temperature control capability is particularly prominent in the changing environment temperature. The CPCs as a safe and reliable adaptive heating element is potential to replace the conventional active thermal control means.

Thermal expanded core technique applied to high power fiber mode field adapter

A mode field adapter （MFA） fabricated by the thermal expanded core （TEC） technique is investigated. Firstly, the mode field characteristics of the TEC large mode area fiber （LMAF） are analyzed. Compared with the single-mode fiber （SMF）, the mode field diameter of the LMAF enlarged slower than that of the SMF. Secondly, the mode field characteristics of the different fibers with TEC treatment are discussed. Thirdly, the transmission efficiency of the MFA fabricated by the SMF and LMAF is also investigated. Finally, we used the 6/125 μm SMF and 15/130 μm LMAF to fabricate an MFA with transmission efficiency of 92% and the handling power as high as 100 W.

Variation of blubber thickness of the Yangtze finless porpoise(Neophocaena asiaeorientalis asiaeorientalis)in human care:Adaptation to environmental temperature

Blubber thickness(BT)has a seasonal pattern in most small cetaceans in temperate and polar regions,which may be a crucial adaptive mechanism in response to environmental temperature changes.However,BT and environmental temperature correlations have never been tested experimentally in any cetacean species owing to logistical difficulties in the aquatic environment.The Yangtze finless porpoise(Neophocaena asiaeorientalis asiaeorientalis,YFP)is one of the smallest cetacean species worldwide,which exclusively inhabits the middle and lower regions of the Yangtze River in China.Here,we investigated BT variation patterns in YFPs and their relationship to environmental temperature changes using ultrasound imaging technology by longitudinally monitoring four YFPs in human care.We found that blubber was not evenly distributed in the skin of YFPs.BT increased along the craniocaudal axis from the head to the umbilical girth,and decreased towards the fluke,with relatively thicker blubber in the dorsal region than in the ventral and lateral regions.Significant negative correlations between BT and seasonal water temperature changes were observed in YFPs.However,different body regions display different sensitivities to seasonal temperature changes.The BT in the anal girth region exhibited noticeable seasonal changes.In contrast,the umbilical lateral and ventral regions showed relatively blunt seasonal changes,indicating different adaptive functions of the blubber in different regions.BT in the dorsal region decreased linearly with increasing water temperature.In the lateral and ventral regions,BT significantly changed with water temperature at a threshold of 18C.The YFPs had relatively thinner BT than similar-sized harbor porpoises that inhabit relatively high latitudes with much lower water temperatures.This further demonstrates the adaptive function of BT in response to environmental temperatures in small cetaceans.This study elucidates the seasonal pattern of BT variation in small cetaceans and provides insight into adaptation mechanisms of small cetaceans to temperature changes.

Moisture and temperature controls on nitrification differ among ammonia oxidizer communities from three alpine soil habitats

Climate change is altering the timing and magnitude of biogeochemical fluxes in many high- elevation ecosystems. The consequent changes in alpine nitrification rates have the potential to influence ecosystem scale responses. In order to better understand how changing temperature and moisture conditions may influence ammonia oxidizers and nitrification activity, we conducted laboratory incubations on soils collected in a Colorado watershed from three alpine habitats （glacial outwash, talus, and meadow）. We found that bacteria, not archaea, dominated all ammonia oxidizer communities. Nitrification increased with moisture in all soils and under all temperature treatments. However, temperature was not correlated with nitrification rates in all soils. Site-specific temperature trends suggest the development of generalist ammonia oxidzer communities in soils with greater in situ temperature fluctuations and specialists in soils with more steady temperature regimes. Rapidly increasing tempera- tures and changing soil moisture conditions could explain recent observations of increased nitrate production in some alpine soils.

Ambient temperature alters body size and gut microbiota of Xenopus tropicalis

Temperature is important to determine physiological status of ectotherms. However, it is still not fully understood how amphibians and their symbiotic microbiota acclimate to ambient temperature. In this study, we investigated the changes of gut microbiota of Xenopus tropicalis at different temperatures under controlled laboratory conditions. The results showed that microbial communities were distinct and shared only a small overlap among froglet guts, culture water and food samples.Furthermore, the dominant taxa harbored in the gut exhibited low relative abundance in water and food. It indicates that bacterial taxa selected by amphibian gut were generally of low abundance in the external environment. Temperature could affect betadiversity of gut microbiota in terms of phylogenetic distance, but it did not affect alpha diversity. The composition of gut microbiota was similar in warm and cool treatments. However, signature taxa in different temperature environments were identified. The relationships between temperature, gut microbiota and morphology traits of X. tropicalis revealed in this study help us to predict the consequences of environmental changes on ectothermic animals.