Changes In Thermal Environment Research Articles

Investigation of outdoor pedestrian shading preference under several thermal environment using remote sensing images

Following advancement in urbanization, outdoor thermal comfort is receiving increasing attention, with radiation being an influencing factor. To determine the shading preference, instead of a subjective questionnaire survey, an objective foot vote approach was proposed using remote sensing images. Subsequently, the meteorological data of cities were obtained from the Bureau of Meteorology. From the results, the foot vote was approximately consistent with the PMV, and pedestrians tended to move to the shaded area if it was hot and to the non-shaded area if it was cold. However, people do not move if the foot vote value ranges from 1 to 2, and the thermal acceptance range of PET is 19.2–29 °C in Beijing when using the definitions of foot vote. The outdoor thermal acceptance differs significantly with the types of outdoor sites and climates, and pedestrians in Beijing are significantly more sensitive than those in Wuhan if the outdoor thermal environment changes. Compared to transportation hubs and shopping malls, pedestrians in public buildings are less sensitive, whereas those in scenic spots are more sensitive. Results from this study will be beneficial to policymakers in urban designing to renovate and improve thermally comfortable urban environments at the pedestrian level.

A Global Assessment of Coastal Marine Heatwaves and Their Relation With Coastal Urban Thermal Changes

AbstractOcean temperature significantly influences global and regional weather and climate. Coastal marine heatwaves (MHWs) do not only profoundly impact marine ecosystems but can influence the climate of coastal regions. This study provides the first observational assessment of global coastal MHWs changes, showing a latitudinal‐dependent pattern with considerably strengthened severity of MHWs in the past four decades. Coastal MHWs have been found closely linked to remarkable changes in coastal urban thermal environments, showing consistent trends of increase in air temperature and moisture, and mostly reduced wind speed among 38 major coastal cities. These effects collectively exacerbate the thermal discomfort during the warm season. The findings demonstrate the strong coupling of coastal oceans and lands under the influence of global warming and regional interactions of ocean, land, and the atmosphere, and contribute to a global initial understanding of the characteristics and co‐variation of thermal extremes over the coastal regions.

Evaluation of conventional invasive measurements and examination of non-invasive measurement technique on human body core temperature

It is important in many cases to measure and monitor, human body core temperatures, to prevent the likes of heat stroke and hypothermia. Measuring core body temperatures is also important for example, in relation to the basal body temperatures of women, and for improving the quality of life for vulnerable people such as infants, and those with cervical spine injuries. In doing so, thermal environmental changes can be monitored. However, todays conventional measuring method is apparently invasive because a temperature sensor has to be inserted into the body, from the outside. Characteristics of the body parts measured were considered by the subject experiments. There was a difference in core temperatures, depending on the measurement body parts, and it was found that the temperature decreased in the order of rectum, sublingual, and tympanic during normal times. It was confirmed that the tympanic temperature showed the most significant increase in core temperature, with running and the sublingual temperature the best in responsiveness. As a non-invasive core temperature measurement method, the basic characteristics were examined by the heat transfer experiment for the dual-heat-flux method. Thus, it was clarified that adequate temperature accuracy can be guaranteed if appropriate materials, thicknesses, and sizes are selected and the adiabatic condition for the peripheral part is fulfilled.

Similarities and disparities in urban local heat islands responsive to regular-, stable-, and counter-urbanization: A case study of Guangzhou, China

Understanding the dynamics and spatial heterogeneity of the intra-city surface heat island (herein termed the surface urban heat island, SUHI) is critical for the design of urban heat mitigation strategies. Large disparities in the spatiotemporal variations of SUHIs are anticipated under different urbanization processes. However, most previous studies have focused solely on the inter-annual spatiotemporal SUHI variations of regular urbanization, while those for stable- and counter-urbanization remain largely unknown. Based on the remote identification of these three urbanization types over Guangzhou, China, we propose a novel strategy to investigate simultaneously the spatiotemporal variations and the associated controls of SUHIs. Our results indicate that: (1) Counter-, regular-, and stable-urbanization occurs mainly over the city center, city periphery, and the in-between areas, respectively. (2) The three urbanization types all demonstrate similar and significant growth in the daytime local SUHI intensity (SUHII). (3) There are significant disparities in the contributions of controls to the inter-annual daytime SUHII trends for these three urbanization processes. For the regular urbanization, the increase of the impervious surface percentage (ISP) dominates daytime SUHII growth, while the combination of ISP and residual factors (e.g., background climate and 3D urban geometry) leads for counter urbanization. For stable urbanization, the combination of residual controls and the increase in population density is the major factor. Urban divisional management may contribute to the mitigation of intra-city SUHI. Our findings potentially advance our understanding of changes in urban thermal environment under different urbanization processes.

Oviductal fluid counterbalances the negative effect of high temperature on sperm in an ectotherm model.

ABSTRACTGlobal warming is affecting biodiversity; however, the extent to which animal reproductive processes respond to predicted temperature increments remains largely unexplored. The thermal environment has a pronounced impact on metabolic rates of ectotherms; therefore, an interesting question to assess is whether temperature increase might affect specific reproductive mechanisms like sperm performance in ectotherms. Moreover, in many species, oviductal fluid (OF) is known to regulate and maintain sperm quality; however, the role of OF in relation to the effects of high temperature on sperm remains unclear. Our aim was to experimentally test the effect of increased temperature on sperm velocity, swimming path and percentage of motility in neutral conditions at ejaculation (without OF) and in female's reproductive tract fluid (with OF), in a social ectotherm lizard model, Tropidurus spinulosus, which has specific thermal requirements for reproduction. Our results suggest that a rising temperature associated with global warming (+4°C) affects negatively sperm dynamics and survival. However, OF ameliorated the harmful effects of high temperature. This is an important point, as this study is the first to have tested the role of OF in preserving sperm from a warmer pre-fertilization environment. These results contribute to our understanding of how thermal environment changes might affect post-copulatory reproductive mechanisms.This article has an associated First Person interview with the first author of the paper.

Computational fluid dynamics model for a variable conductance thermosyphon

A variable conductance thermosyphon is a unique type of heat pipe that responds passively to changes in thermal environment because of the presence of non-condensable gas (NCG). In this study, we develop a computational fluid dynamics (CFD) model to predict the behavior of a cylindrical-shaped variable conductance thermosyphon in the vertical orientation for a range of evaporator-side operating temperatures between 66.70 °C and 87.32 °C. Experiments are performed on a variable conductance thermosyphon that is made of a 262 mm long stainless steel tube with an outer diameter of 9.5 mm and a wall thickness of 0.92 mm. The working fluid is methanol and the NCG is argon. The model is able to predict the fluid flow and heat transfer in the fluid domain and the conjugate heat transfer to the solid wall domain. Experimental thermocouple data for both forced convection and natural convection test cases show temperature remaining almost uniform in the adiabatic section and dropping rapidly across the vapor/NCG interface between the vapor and NCG. This behavior of wall temperature change was also captured accurately by the CFD model, evidenced by MAEs of 3.09% and 3.52% for forced and natural convection test cases, respectively.

Three-Dimensional Electro-Thermal Analysis of a New Type Current Transformer Design for Power Distribution Networks

In recent years, the new type design of current transformer with bushing structure has been widely used in the distribution network system due to its advantages of miniaturization, high mechanical strength, maintenance-free, safety and environmental protection. The internal temperature field distribution is an important characteristic parameter to characterize the thermal insulation and aging performance of the transformer, and the internal temperature field distribution is mainly derived from the joule heat generated by the primary side guide rod after flowing through the current. Since the electric environment is a transient field and the thermal environment changes slowly with time as a steady field under the actual conditions, it is more complex and necessary to study the electrothermal coupling field of current transformer (CT). In this paper, a 3D simulation model of a new type design of current transformer for distribution network based on electric-thermal coupling is established by using finite element method (FEM) software. Considering that the actual thermal conduction process of CT is mainly by conduction, convection and radiation, three different kinds of boundary conditions such as solid heat transfer boundary condition, heat convection boundary condition and surface radiation boundary condition are applied to the CT. Through the model created above, the temperature rise process and the distribution characteristics of temperature gradient of the inner conductor under different current, different ambient temperatures and different core diameters conditions are studied. Meanwhile, the hottest temperature and the maximum temperature gradient difference are calculated. According to this, the position of weak insulation of the transformer is determined. The research results can provide a reference for the factory production of new type design of current transformer.

Thermal design and simulation of space-borne membrane antenna

Thermal deformation of space-borne radar antenna caused by dramatic changes in orbit thermal environment has a serious effect on image qualities. In this paper, the NX TMG module was used to simulate the orbit thermal environment of the antenna, and a thermal control design was proposed. The thermal control structure consists of three layers; the top is a radiator with high emissivity surface, the middle is a multi-layer insulation, and the bottom is a highly reflective layer. The simulation results show that the thermal design could reduce the temperature gradient from 238.1 to 31.4 °C effectively.

Field Observations of Body Temperature for the Wolf Spider, Rabidosa rabida (Araneae: Lycosidae), Differ From Reported Laboratory Temperature Preference Suggesting Thermoconforming Behavior.

Temperature affects all aspects of ectotherm ecology, behavior, and physiology. Descriptions of thermal ecology are important for understanding ecology in changing thermal environments. Both laboratory and field estimates are important for understanding thermal ecology. Rabidosa rabida (Walckenaer 1837) (Araneae: Lycosidae) is a large wolf spider with some natural history, including laboratory estimates of thermal preference, tolerance, and performance, reported in the scientific literature. Laboratory tests suggest the active choice of temperature environment. To test published estimates of thermal ecology from the laboratory, we took body temperature measurements of mature spiders in the field nocturnally and diurnally using a FLIR camera in July 2019. We made comparisons between sexes and activity periods using field observations. We compared these measurements with the published values for thermal preferences and thermal maximum and with mean weather station data. Observed field temperatures differed significantly from published preference, but not from mean temperature from a local weather station. This suggests that this species is thermoconforming rather than actively thermoregulating. Reported thermal preference fell between the diurnal and nocturnal mean measurements closer to the diurnal than nocturnal temperatures. These field observations show how important it is to make field observations for physiology and thermal ecology. Maximum observed diurnal temperatures closely approached the published critical thermal maximum. We observed spiders performing behaviors such as hunting and feeding in conditions well above published thermal preference and near-critical high temperature. These observations suggest that R. rabida is thermoconforming in this limited period but does not rule out that they might thermoregulate in certain situations.

Increases in Anthropogenic Heat Release from Energy Consumption Lead to More Frequent Extreme Heat Events in Urban Cities

With economic development and rapid urbanization, increases in Gross Domestic Product and population in fast-growing cities since the turn of the 21st Century have led to increases in energy consumption. Anthropogenic heat flux released to the near-surface atmosphere has led to changes in urban thermal environments and severe extreme temperature events. To investigate the effects of energy consumption on urban extreme temperature events, including extreme heat and cold events, a dynamic representation scheme of anthropogenic heat release (AHR) was implemented in the Advanced Research version of the Weather Research and Forecasting (WRF) model, and AHR data were developed based on energy consumption and population density in a case study of Beijing, China. Two simulations during 1999–2017 were then conducted using the developed WRF model with 3-km resolution with and without the AHR scheme. It was shown that the mean temperature increased with the increase in AHR, and more frequent extreme heat events were produced, with an annual increase of 0.02–0.19 days, as well as less frequent extreme cold events, with an annual decrease of 0.26–0.56 days, based on seven extreme temperature indices in the city center. AHR increased the sensible heat flux and led to surface energy budget changes, strengthening the dynamic processes in the atmospheric boundary layer that reduce AHR heating efficiency more in summer than in winter. In addition, it was concluded that suitable energy management might help to mitigate the impact of extreme temperature events in different seasons.

Nonlinear buckling analysis of FGP shallow spherical shells under thermomechanical condition

In this study, an analytical method is presented to investigate the nonlinear buckling analysis of functionally graded porous (FGP) shallow spherical shells exposed to external excitation in a thermal environment resting on elastic foundations. The elastic foundations of the FGP shell are consist of a two-term Winkler-Pasternak's model. Using the classical theory of shells and considering nonlinear von Karman-Donnell relations and Hook law, the governing equations of thin FG porous spherical shells are extracted. Galerkin's method is utilized to discretize the governing equation of shallow spherical shell. Regarding the discretized equations of motion, the explicit expressions for dynamic and static critical buckling loading are determined under thermomechanical effect. Two types of distributions for FG porous, including the uniform and symmetric porosity, are considered. To investigate the dynamic buckling exposed to external pressure and thermal effect, the equations of motion of FGP shallow spherical shells are examined via a numerical method named Runge-Kutta approach, and then with a procedure presented by Budiansky-Roth, the critical load for the nonlinear dynamic buckling is obtained. The influence of thermal environment changes, porosity coefficients, various porosity distributions, elastic foundations, and geometrical characteristics on the nonlinear static and dynamic buckling response of FGP shallow spherical shell is examined.

Thermal robustness of biomechanical processes

Temperature influences many physiological processes that govern life as a result of the thermal sensitivity of chemical reactions. The repeated evolution of endothermy and widespread behavioral thermoregulation in animals highlight the importance of elevating tissue temperature to increase the rate of chemical processes. Yet, movement performance that is robust to changes in body temperature has been observed in numerous species. This thermally robust performance appears exceptional in light of the well-documented effects of temperature on muscle contractile properties, including shortening velocity, force, power and work. Here, we propose that the thermal robustness of movements in which mechanical processes replace or augment chemical processes is a general feature of any organismal system, spanning kingdoms. The use of recoiling elastic structures to power movement in place of direct muscle shortening is one of the most thoroughly studied mechanical processes; using these studies as a basis, we outline an analytical framework for detecting thermal robustness, relying on the comparison of temperature coefficients (Q 10 values) between chemical and mechanical processes. We then highlight other biomechanical systems in which thermally robust performance that arises from mechanical processes may be identified using this framework. Studying diverse movements in the context of temperature will both reveal mechanisms underlying performance and allow the prediction of changes in performance in response to a changing thermal environment, thus deepening our understanding of the thermal ecology of many organisms.

Divergent trends of urban thermal environmental characteristics in China

Due to the rapid urbanization in China, urban expansion has gradually shifted from large cities to small cities, causing spatiotemporal changes in the urban thermal environment. The differential thermal environmental characteristics of 334 cities at different hierarchy caused by urbanization are investigated in this study. Then, the spatiotemporal changes of land surface temperature (LST), albedo, and emissivity among urban areas and their surrounding buffer areas are analyzed during 2000–2015. We found that the urban warming effect is usually prominent in the daytime, with an obvious seasonal differentiation between 0.32 °C[0.27,0.38] in summer and -0.14 °C[-0.20,-0.07] in winter. The nighttime warming effect during summer resembles that in winter, in the range 0.23–0.25 °C. In addition, the number of cities with intensifying trends of the warming effect in summer daytime account for 50% of the total cities, but only 9% in winter nighttime, 23% in summer nighttime, and 25% in winter daytime. Large cities usually have obvious warming effects compared with small cities. But the highest warming effect is found in megacities during the daytime and in medium cities during the nighttime. In southern subtropical cities, the warming of urban zones is high in the daytime and low in the nighttime, while it is opposite in arid and semiarid regions, especially in winter. The negative correlations between the difference of surface albedo (emissivity) and LST in megacities and metropolitan areas emphasize that nighttime warming primarily results from radiation absorption and release affected by urbanization. This study may advance the understanding of the heterogeneity in the warming effects of different cities in China and support policy formulation and regulation to adapt to urban warming.

Sensory and physiological assessment of spatial transient thermal environment changes at a tropical university campus

PurposeRecent studies have found that the high demand for air-conditioning usage in tropical countries has affected the thermal adaptability of building occupants to hot weather, and increased building energy consumption. This pilot study aims to investigate the effects of transient thermal environment changes on participants' sensory and physiological responses.Design/methodology/approachThe change of thermal perceptions, skin temperatures and core temperatures when exposed to transient thermal environments (cool-warm-cool) from 10 college-aged female participants during a simulated daily commute by foot to class in a tropical university campus were investigated. Subjective measurements were collected in real-time every 5 min.FindingsThe main finding suggests that participants were acclimatised to cool air-conditioned indoor environments, despite exhibiting significant mean skin temperature differences (p < 0.05). In addition, exposure to uniform air conditioning from 17 to 18°C for 20 min was thermally unacceptable and reduced concentration during given tasks.Research limitations/implicationsThe study focused on thermal comfort conditions in a uniform air-conditioned lecture hall, and the findings may not be applicable for residential and other private building spaces. The distinct temperature difference between indoor and outdoor in the tropical built environment resulted in high dependence on air-conditioning usage. The building occupants' well-being and energy conservation implications of the findings are discussed.Practical implicationsThis study provides the platform for discussion on the dynamics of occupants' comfort level and adopting a more variable thermal environment in tropical spatial transient thermal environments among architects and building management system managers. The findings from this study may contribute to the Malaysian Standards for Energy Efficiency and Use of Renewable Energy for Non-Residential Buildings (MS1525).Originality/valueA knowledge gap in adaptive thermal comfort due to exposure from transient conditions in tropical university campus for energy efficiency revision has been investigated.

Transient model and its application to investigate the injection mode and periodical operation of transpiration cooling with liquid coolant phase change

To study the stability and reliability of transpiration cooling with phase change in complicated and changeable thermal environment, this paper suggests a transient mathematical model and numerically investigates the dynamic evolution of phase change and transient behavior of fluid–structure coupling heat transfer under three typical time-varying thermal environments. First, the feasibility and reliability of two coolant injection methods are analyzed and compared. The results indicates that the coolant injection based on pressure control is stable only when the heat flux imposed on transpiration cooling structure is relatively low and phase change occurs at hot side, while the coolant injection based on mass flow rate control is absolutely stable no matter how the external thermal environment changes. Then, the effects of fluctuated operation condition on the cooling performance of system and the transport characteristic of coolant are further studied. Although without affecting the stability of the transpiration cooling system in the long term, the fluctuation of coolant injection and external heat flux will result in the fluctuation of structure temperature and coolant driving force, and thereby cause significant deterioration of cooling performance, which will increase the ablation risk and coolant driving cost of transpiration cooling system.

COMPREHENSIVE ANALYSIS OF URBAN THERMAL ENVIRONMENT – A CASE STUDY OF QINGDAO，CHINA

Abstract. The thermal environment is an important part of spatial planning of national land. It can be inverted by thermal infrared remote sensing image data. Qingdao is an important coastal city in China which is effected by the urban heat island. The driving factors of urban thermal environment in Qingdao are analysed by using Landsat 8 OLI/TIRS images, DMSP/OLS data, ZY-3 images, statistical data et al. Firstly, the urban heat island information in different periods are retrieved by Landsat8 TIRS by the surface temperature. On this basis, the coupling analysis of the characteristics of vegetation cover, water, land use type, night light, urban impervious surface, transportation, change density and other factors that related to spatial planning of national land and the change of thermal environment is completed from two dimensions of time and space. At the same time, according to the spatial distribution of the heat island evolution, with the aim of improving the thermal environment and optimizing the urban spatial layout of Qingdao, the paper puts forward reasonable suggestions and improvement strategies, and provides basic reference data for the development of urban heat island governance and land development and utilization.

Cytosine methylation patterns suggest a role of methylation in plastic and adaptive responses to temperature in European grayling (Thymallus thymallus) populations

ABSTRACT Temperature is a key environmental parameter affecting both the phenotypes and distributions of organisms, particularly ectotherms. Rapid organismal responses to thermal environmental changes have been described for several ectotherms; however, the underlying molecular mechanisms often remain unclear. Here, we studied whole genome cytosine methylation patterns of European grayling (Thymallus thymallus) embryos from five populations with contemporary adaptations of early life history traits at either ‘colder’ or ‘warmer’ spawning grounds. We reared fish embryos in a common garden experiment using two temperatures that resembled the ‘colder’ and ‘warmer’ conditions of the natal natural environments. Genome-wide methylation patterns were similar in populations originating from colder thermal origin subpopulations, whereas single nucleotide polymorphisms uncovered from the same data identified strong population structure among isolated populations, but limited structure among interconnected populations. This was surprising because the previously studied gene expression response among populations was mostly plastic, and mainly influenced by the developmental temperature. These findings support the hypothesis of the magnified role of epigenetic mechanisms in modulating plasticity. The abundance of consistently changing methylation loci between two warmer-to-colder thermal origin population pairs suggests that local adaptation has shaped the observed methylation patterns. The dynamic nature of the methylomes was further highlighted by genome-wide and site-specific plastic responses. Our findings support both the presence of a plastic response in a subset of CpG loci, and the evolutionary role of methylation divergence between populations adapting to contrasting thermal environments.

Spatio-temporal variation in egg-laying dates of nestbox-breeding varied tits (Poecile varius) in response to spring pre-breeding period temperatures at long-term study sites in South Korea and Japan

ABSTRACT Climate change can alter and disrupt the phenology and phenological interaction between organisms from various trophic levels in forest ecosystems. In temperate forests, the breeding phenology of birds is correlated to local microclimate, especially spring temperature to match the timing of food availability. Recent studies revealed that the temperature warming is more pronounced in high-elevation areas (elevation-dependent warming), while the breeding phenology shift of birds in this condition needs further investigation. We studied the annual change in the egg-laying dates of varied tits (Poecile varius) and a pre-breeding temperature index in three plots located along with the elevational gradient in South Korea and a low-elevation plot in Japan. We found strong support for disproportionate rates of changes in higher elevation for warming trends in pre-breeding period and advances in egg-laying dates over the last decade. Next, we compared three segments of 36-year data from Akazu Research Forest. The evidence from pre-breeding temperature during 36 years indicates that we could detect the change in thermal environment and breeding phenology with longer years of data, especially in lower elevation regions. This result shows the need for long-term research to understand the change in local temperatures and the ecology of forest birds. Our study presents evidence of elevation-dependent phenological advance in avian breeding activities and discusses the need for systematic long-term research on multiple taxa and climatic drivers in Asia.

Potential effects of elevated temperature on seasonal movements in slipper lobsters, Scyllarides latus (Latreille, 1803), in the eastern Mediterranean

Temperature serves a predominant motivator for movement and activity over a wide range of mobile marine ectotherms. Water temperature modulates the movements of many lobster species, which can vary widely over spatial and temporal scales. Providing insight into the thermal preferences (and refuges) that some lobsters seek remains a key tenet to our understanding of the behavioral ecology of these animals. The Mediterranean slipper lobster (Scyllarides latus) shows seasonal movements throughout most of its range and is subject to a changing thermal environment. We examined the seasonal movements of S. latus within a small marine reserve (Rosh Hanikra Marine Reserve, RHR) off the coast of Israel and tested the hypothesis that S. latus engage in increased movements when subjected to temperatures outside their range. We conducted a field survey in the RHR and tagged lobsters (n = 81, carapace length, CLavg= 88.7 ± 4.6) to investigate their activity during their putative summer movement. In the lab, we exposed a separate set of lobsters (n = 10, CLavg= 83.1 ± 6.1) to the same thermal profiles as in the field and assayed their locomotion using activity wheels. Field results revealed that lobsters tagged in shallow waters moved to deeper, cooler waters (~ 30 m) over the course of 2-2.5 months traveling an average distance of 3.4 km (range = 1-5 km). Our lab results showed that S. latus are more active at higher temperatures, but moreover, revealed that warming water temperatures elicited markedly longer movements over a similar timeframe. Combined, these findings suggest that increasing water temperatures in the eastern Mediterranean (Levant) may affect lobster movements and could alter seasonal patterns of distribution as well.

Effects of indoor thermal exposure on human dynamic thermal adaptation process

The effects of indoor thermal exposure on human thermal adaptation is a time-dependent process, and deconstructing the human thermal response in a dynamic process helps to reveal the thermal adaptation mechanism. Although many researchers have studied human thermal comfort under different indoor thermal conditions in cross-sectional field investigations, the temporal variation of the human thermal response in the adaptation process remains to be further studied. To study the combined effect of indoor thermal stress and exposure duration on human thermal adaptation, a follow-up study was performed on 30 subjects for nine weeks: they were exposed to three different heating intensities in winter (unheated room, low-level heated room, and high-level heated room). Subjects’ physiological responses to the thermal environmental changes were monitored, and psychological assessment was conducted with questionnaires at indoor temperatures of 14, 18, and 22 °C in a climate chamber in each week. The results showed that indoor thermal exposure exhibited a temporal cumulative effect on human thermal adaptation, and the physiological and psychological adaptation processes were not necessarily synchronous. Prolonged indoor cold exposure not only increased the acceptability of human body to cold exposure, but also elevated the vigilance to warm exposure; skin temperature was increased and sympathetic activity was decreased characterized by lower LF/HF ratio in cold exposure. The research results provide implications for the control of indoor thermal environments based on human adaptability.