Thermal Limits Research Articles

Temporal dynamics of climate change exposure and opportunities for global marine biodiversity

Climate change is exposing marine species to unsuitable temperatures while also creating new thermally suitable habitats of varying persistence. However, understanding how these different dynamics will unfold over time remains limited. We use yearly sea surface temperature projections to estimate temporal dynamics of thermal exposure (when temperature exceeds realised species’ thermal limits) and opportunity (when temperature at a previously unsuitable site becomes suitable) for 21,696 marine species globally until 2100. Thermal opportunities are projected to arise earlier and accumulate gradually, especially in temperate and polar regions. Thermal exposure increases later and occurs more abruptly, mainly in the tropics. Assemblages tend to show either high exposure or high opportunity, but seldom both. Strong emissions reductions reduce exposure around 100-fold whereas reductions in opportunities are halved. Globally, opportunities are projected to emerge faster than exposure until mid-century when exposure increases more rapidly under a high emissions scenario. Moreover, across emissions and dispersal scenarios, 76%-97% of opportunities are projected to persist until 2100. These results indicate thermal opportunities could be a major source of marine biodiversity change, especially in the near- and mid-term. Our work provides a framework for predicting where and when thermal changes will occur to guide monitoring efforts.

Onboard guidance and control algorithms for increased autonomous aerobraking capabilities at Mars

Aerobraking represents a valuable option for interplanetary missions thanks to its capability of reducing the orbital semi-major axis through multiple atmospheric passages, thus with limited fuel consumption. However, due to structural and thermal loads the spacecraft undergoes, mission risks and ground operations costs increase. This study aims to tackle this aerobraking drawback by enhancing its autonomy. The main activities required for aerobraking execution, including atmospheric prediction, orbital state estimation, and orbit control, are tailored for onboard execution. Regarding orbit control, two different methodologies, differentiated by working principle and prediction horizon breadth, are investigated. The first plans orbit control manoeuvres based on the prediction of the atmospheric conditions for a single upcoming pericentre, while the second schedules and optimizes the manoeuvres considering the recent atmospheric conditions experienced by the spacecraft and the altitude trend of multiple upcoming pericentres. The whole operational concept is tested within a simulated environment, with the primary objective of accurately reproducing the intense atmospheric variations of the Martian atmosphere, which represents the most challenging aspect during aerobraking execution. The numerical testing, involving the simulation of different aerobraking regimes under varied conditions, shows that the natural dynamics of the orbital motion can be exploited to minimize both fuel consumption for orbit control manoeuvres and spacecraft load variations, thus enabling more efficient aerobraking and more stable flight conditions, even with the limited predictive capabilities that characterize onboard resources. Both control logics permit the aerobraking execution without exceeding the maximum allowed thermal limits, hence showing their effectiveness. Furthermore, a Monte Carlo analysis conducted on a complete aerobraking simulation reveals a 25.5% reduction in propellant consumption and a 9.4% reduction in heat rate variability when the orbit control decision process uses information relative to multiple future pericentres.

Ontogenetic variation in metabolic rate-temperature relationships during larval development.

Predictive models of ectotherm responses to environmental change often rely on thermal performance data from the literature. For insects, the majority of these data focus on two traits, development rate and thermal tolerance limits. Data are also often limited to the adult stage. Consequently, predictions based on these data generally ignore other measures of thermal performance and do not account for the role of ontogenetic variation in thermal physiology across the complex insect life cycle. Theoretical syntheses for predicting metabolic rate also make similar assumptions despite the strong influence of body size as well as temperature on metabolic rate. The aim of this study was to understand the influence of ontogenetic variation on ectotherm physiology and its potential impact on predictive modeling. To do this, we examined metabolic rate-temperature (MR-T) relationships across the larval stage in a laboratory strain of the spongy moth (Lymantria dispar dispar). Routine metabolic rates (RMRs) of larvae were assayed at eight temperatures across the first five instars of the larval stage. After accounting for differences in body mass, larval instars showed significant variation in MR-T. Both the temperature sensitivity and allometry of RMR increased and peaked during the third instar, then declined in the fourth and fifth instar. Generally, these results show that insect thermal physiology does not remain static during larval ontogeny and suggest that ontogenetic variation should be an important consideration when modeling thermal performance.

Effects of heating rate on upper thermal limit: insights from cardiac performance and transcriptomic response in mudflat snail Batillaria attramentaria

Effects of heating rate on upper thermal limit: insights from cardiac performance and transcriptomic response in mudflat snail Batillaria attramentaria

Impact of Temperature on the Growth Performance, Survival Rate, Osmoregulation, Dissolved Oxygen and Physiological Changes of Freshwater Tilapia (Oreochromis mossambicus)

For many aquatic species, any changes in water temperature affect their survival. This study was performed to investigate the effect of rising temperature on the growth parameters, protein content, dissolved oxygen content, moisture content osmoregulation, and physiological activity of freshwater Tilapia (Oreochromis mossambicus). The experiments were set in plastic fish tanks, the experimental tank placed in direct sunlight and the control tank in shade, and measuring temperature and pH daily, with proper aeration and feed was provided. The study found that increasing water temperature led to higher mortality rates and low survivability percentages in fish, with a higher growth rate in the experimental group with a pH range of 5.7 to 8.2. High dissolved oxygen levels were recorded during the experimental period, with a mean difference of 26.56 compared to the control group, possibly causing restless movement in fish. The study revealed that the alkalinity of water decreases with increasing temperature. The study found that increased salinity led to a significant increase in growth performance, indicating an increase in metabolic rate, and a decrease in alkaline nature. The difference between the mean protein value in the experimental and control groups is 0.896mg/ml. Thermal limitations may negatively impact O. mossambicus physiological responses, impacting aquaculture production due to predicted global climate change-induced water temperature changes.

Thermal Tolerance and Preferred Temperature in the Critical Endangered Montseny Brook Newt (Calotriton arnoldi).

Climate change, driven by increased human greenhouse gas emissions since the beginning of the industrial revolution up to the present day, is considered one of the major threats to biodiversity in the twenty-first century. One of the most affected groups is the ectotherms due to their direct dependence on environmental temperatures. In recent years, several studies have analysed the effects of temperature and thermal tolerance on several species of ectotherms. However, there are species whose thermal tolerances are still unknown. Such is the case of the critically endangered species, the Montseny Brook Newt (Calotriton arnoldi), endemic to the Montseny massif in Spain and whose thermal biology is unknown. Its critical situation makes it essential to know its tolerance to cooling, warming and thermopreferendum in water environments where the newt lives. Three experimental procedures were conducted from the western and eastern subspecies of C. arnoldi, considering four classes separately (males, females, juveniles and larvae). The results obtained showed that the CTmax of the species exceeded 31 °C, with a significant difference between the two subspecies. We found that the species tolerates low temperatures (<1 °C) well because the genera Calotriton is adapted to live in cold waters with temperatures below 15 °C. Although the thermopreference of the species was expected to trend to cold temperatures, some individuals chose relatively high temperatures, obtaining a range of 11.7 °C to 21.6 °C. The results presented in this study are an advance in the knowledge of the thermal physiology of this species and support the importance of the temperature of the torrent on its survival. Knowing their thermal limits and their preferred temperature range will help to propose management measures that promote the conservation of streams and riparian forest cover to mitigate temperature increases due to climate change.

Approach for sizing by optimization of an electrical drive considering a multiphysics and multidynamics behaviour

PurposeThis paper aims to describe a modelling and solving methodology of a (static converter–electric motor–control) system for its sizing by optimization, considering the dynamic thermal heating of the machine.Design/methodology/approachThe electrical drive sizing model is composed of two simulators (electrical and thermal) that are co-simulated with a master−slave relationship for the time step management. The computation is stopped according to simulation criteria.FindingsThis paper details a methodology to represent and size an electrical drive using a multiphysics and multidynamics approach. The thermal simulator is the master and calls the electrical system simulator at a fixed exchange time step. The two simulators use a dedicated dynamic time solver with adaptive time step and event management. The simulation automatically stops on pre-established criteria, avoiding useless simulations.Research limitations/implicationsThis paper aims to present a generic methodology for the sizing by optimization of electrical drives with a multiphysics approach, so the precision and computation time highly depend on the modelling method of each components. A genetic multiobjective optimization algorithm is used.Practical implicationsThe methodology can be applied to size electrical drives operating in a thermally limited zone. The power electronics converter and electrical machine can be easily adapted by modifying their sub-model, without impacting the global model and simulation principle.Originality/valueThe approach enables to compute a maximum operating duration before reaching thermal limits and to use it as an optimization constraint. These system considerations allow to over constrain the electrical machine, enabling to size a smaller machine while guaranteeing the same output performances.

Numerical and Thermal Response of the Bacterivorous Ciliate Colpidium kleini, a Species Potentially at Risk of Extinction by Rising Water Temperatures

We investigated the food-dependent growth and thermal response of the freshwater ciliate Colpidium kleini using numerical response (NR) experiments. This bacterivorous ciliate occurs in lotic water and the pelagial of lakes and ponds. The C. kleini strain used in this work was isolated from a small alpine lake and identified by combining detailed morphological inspections with molecular phylogeny. Specific growth rates (rmax) were measured from 5 to 21 °C. The ciliate did not survive at 22 °C. The threshold bacterial food levels (0.3 − 2.2 × 106 bacterial cells mL−1) matched the bacterial abundance in the alpine lake from which C. kleini was isolated. The food threshold was notably lower than previously reported for C. kleini and two other Colpidium species. The threshold was similar to levels reported for oligotrich and choreotrich ciliates if expressed in terms of bacterial biomass (0.05 − 0.43 mg C L−1). From the NR results, we calculated physiological mortality rates at zero food concentration. The mean mortality (0.55 ± 0.17 d−1) of C. kleini was close to the mean estimate obtained for other planktonic ciliates that do not encyst. We used the data obtained by the NR experiments to fit a thermal performance curve (TPC). The TPC yielded a temperature optimum at 17.3 °C for C. kleini, a maximum upper thermal tolerance limit of 21.9 °C, and a thermal safety margin of 4.6 °C. We demonstrated that combining NR with TPC analysis is a powerful tool to predict better a species’ fitness in response to temperature and food.

Active Thermal Management Method for Improving Current Capability of Power Devices under Influence of Random Convection

The active thermal management (ATM) method can improve the current capability of power devices safely by utilizing the thermal limit of the device. However, the existing methods are not suitable for power devices affected by random convection. This is because the randomness of convection will lead to the uncertainty of increased current capability, which is unacceptable in most engineering applications. To overcome the shortcomings of existing ATM methods, this paper proposed a novel ATM method for power devices under the influence of random convection. In the proposed method, the short-time current capability of the power device is maximized according to the thermal inertia of the device and maximum load current. The continuous current capability of the power device is determined by a maximum continuous current that satisfies the over-temperature risk constraint of the device. To accurately estimate the maximum continuous current, an uncertainty model is presented for the convective thermal resistance of the power device based on wavelet packet transform and Markov chain. A series of experimental studies are carried out by taking a power MOSFET as an example. The experimental results show that the proposed method can safely improve the output performance of the power device without causing random fluctuations in the current capability.

An arctic breeding songbird overheats during intense activity even at low air temperatures

Birds maintain some of the highest body temperatures among endothermic animals. Often deemed a selective advantage for heat tolerance, high body temperatures also limits birds’ thermal safety margin before reaching lethal levels. Recent modelling suggests that sustained effort in Arctic birds might be restricted at mild air temperatures, which may require reductions in activity to avoid overheating, with expected negative impacts on reproductive performance. We measured within-individual changes in body temperature in calm birds and then in response to an experimental increase in activity in an outdoor captive population of Arctic, cold-specialised snow buntings (Plectrophenax nivalis), exposed to naturally varying air temperatures (− 15 to 36 °C). Calm buntings exhibited a modal body temperature range from 39.9 to 42.6 °C. However, we detected a significant increase in body temperature within minutes of shifting calm birds to active flight, with strong evidence for a positive effect of air temperature on body temperature (slope = 0.04 °C/ °C). Importantly, by an ambient temperature of 9 °C, flying buntings were already generating body temperatures ≥ 45 °C, approaching the upper thermal limits of organismal performance (45–47 °C). With known limited evaporative heat dissipation capacities in these birds, our results support the recent prediction that free-living buntings operating at maximal sustainable rates will increasingly need to rely on behavioural thermoregulatory strategies to regulate body temperature, to the detriment of nestling growth and survival.

A cautionary message on combining physiological thermal limits with macroclimatic data to predict species distribution

AbstractMacroclimatic data are widely used to estimate the realized environmental niche of species and predict the current or the future spatial distribution of species. Because the realized niche is a subset of the fundamental niche—constrained by biotic interactions and dispersal limitations—proxies of the fundamental niche (e.g., thermal limits obtained from physiological experiments) are sometimes combined with macroclimatic data under the assumption that areas predicted as unsuitable from a realized niche perspective may belong to the species' fundamental niche. However, it is unclear whether this assumption is valid and whether thermal limits can be combined with macroclimatic data. Here, we explored these questions using available physiological thermal limits measured for 151 ectotherms. Specifically, we explored whether physiological thermal limits are larger than observed (realized) thermal limits measured using macroclimatic data, and what would be the effect of considering the physiological niche in addition to the realized niche for current and future predictions. Our results confirm previously raised concerns, as physiological limits can delimit a narrower range of thermal tolerance than the realized niche, particularly at the cold end of the thermal gradient where adaptive and/or facilitative mechanisms could allow species to survive in temperatures below physiological limits. These findings show that combining data on physiological thermal limits with macroclimatic data is dubious and that spatial predictions should be interpreted with caution because data on physiological thermal limits do not fit well with macroclimatic data that do not capture the conditions that organisms experience in the wild. While estimated physiological thermal limits are likely of value to complement species distribution studies, they are likely more useful in biophysical models that account for additional processes including the animal's behavior.

Elevational shifts in tree community composition in the Brazilian Atlantic Forest related to climate change

AbstractQuestionClimate change induces shifts in species distributions, ultimately changing community composition. Mountains are especially sensitive to climate change, and tree species are predicted to move towards higher elevations, but observed changes are not always unidirectional. The diversity and complexity of tropical and subtropical systems limits our understanding of climate‐induced responses of subtropical mountain forests. Here, we investigated migration trends in tree community composition along an elevational gradient, and between the transition from lowland to montane forests in subtropical forests.LocationBrazilian Atlantic Forest.MethodsWe used thermal affiliations of 627 tree species to calculate community temperature scores (CTS) for different life‐history stages of trees in 96 permanent plots. We compared CTS of different life‐history stages across space and time.ResultsMost tree communities (58%) did not show a significant difference of CTS between life‐history stages, indicating a non‐migration trend. On the other hand, 27% of tree communities showed upward migration and 15% downward migration. Upward migration was more common in montane forests, and downward migration in lowland forests. Our temporal analysis shows significant changes in CTS values for juvenile communities with 0.36°C decrease in lowland forests and 0.34°C increase in montane forests.ConclusionsContrasting results between lowland and montane forest communities indicate that the transition zone influences migration patterns and may reflect differences in species’ thermal limitations, as well as by non‐thermal factors such as biotic interactions. Our findings provide the first evidence of climate change‐induced community shifts in the Brazilian Atlantic Forest. We demonstrated that upward migration trends were predominantly observed in montane–upper mountain forests, while downward migrations were noted in lowland–submontane forests. The thermophilization of montane forests may suggest an increased risk of reduction for cold‐demanding species under climate change scenarios.

The lack of plasticity and interspecific variability in thermal limits produce a highly heat-tolerant tropical host-parasitoid system

Thermal limits are often used as proxies to assess the vulnerability of ectotherms to environmental change. While meta-analyses point out a relatively low plasticity of heat limits and a large interspecific variability, only few studies have compared the heat tolerance of interacting species. The present study focuses on the thermal limits, and their plasticity (heat hardening), of three species co-occurring in Western Africa: two ectoparasitoid species, Dinarmus basalis (Rondani) (Hymenoptera: Pteromalidae) and Eupelmus vuilleti (Crawford) (Hymenoptera: Eupelmidae), and their common host, Callosobruchus maculatus (F.) (Coleoptera: Bruchidae). The investigation delves into the Critical Thermal Maximum (CTmax), representing the upper tolerance limit, to understand how these species may cope with extreme thermal events. The CTmax of all three species appeared similarly high, hovering around 46.5 °C, exceeding the global mean CTmax observed in insects by 3.5 °C. Short-term exposure to moderate heat stress showed no impact on CTmax, suggesting a potential lack of heat hardening in these species. Therefore, we emphasized the similarity of heat tolerance in these interacting species, potentially stemming from both evolutionary adaptations to high temperatures during development and the stable and similar microclimate experienced by the three species over the years. While the high thermal tolerance should allow these species to endure extreme temperature events, the apparent lack of plasticity raises concerns about their ability to adapt to future climate change scenarios. Overall, this research provides valuable insights into the thermal physiology of these interacting species, providing a basis for understanding their responses to climate change and potential implications for the host-parasitoid system.

Testing metabolic cold adaptation and the climatic variability hypothesis in two latitudinally distant populations of a supratidal water beetle

Temperature significantly impacts ectotherm physiology, with thermal tolerance and metabolic traits typically varying with latitude across species ranges. The drivers of this variation remain unclear, however, despite obvious consequences for population persistence and conservation in the face of ongoing global change. This study explored local adaptation and phenotypic plasticity of metabolic rates and thermal limits in the supratidal rockpool beetle Ochthebius lejolisii. Using populations from localities at different ends of the species range that experience contrasting thermal variability, we simultaneously tested two of the major paradigms of spatial physiological ecology: metabolic cold adaptation (MCA) and the climatic variability hypothesis (CVH). Reciprocal acclimation was conducted under spring temperature regimes of both localities, incorporating local diurnal variation. Metabolic rates were measured by closed respirometry, and thermal tolerance limits estimated through thermography. In line with MCA, the higher-latitude population (colder climate) showed higher metabolic rates and temperature coefficients (Q10s) at lower temperatures than the lower-latitude population. As predicted by the CVH, the lower-latitude population (more variable climate) showed higher upper thermal tolerance but only the higher-latitude population was able to acclimate upper thermal limits. This result suggests trade-offs between physiological thermal limits and thermal plasticity in this species. A limited acclimation capacity could make populations on Mediterranean coasts especially vulnerable in the face of projected increases in extreme temperatures under ongoing climate change.

First upper limits on the 21 cm signal power spectrum from cosmic dawn from one night of observations with NenuFAR (Corrigendum)

The redshifted 21 cm signal from neutral hydrogen is a direct probe of the physics of the early universe and has been an important science driver of many present and upcoming radio interferometers. In this study we use a single night of observations with the New Extension in Nan cay Upgrading LOFAR (NenuFAR) to place upper limits on the 21 cm power spectrum from cosmic dawn at a redshift of $z$ = 20.3. NenuFAR is a new low-frequency radio interferometer, operating in the 10--85 MHz frequency range, currently under construction at the Nan cay Radio Observatory in France. It is a phased array instrument with a very dense $u coverage at short baselines, making it one of the most sensitive instruments for 21 cm cosmology analyses at these frequencies. Our analysis adopts the foreground subtraction approach, in which sky sources are modeled and subtracted through calibration and residual foregrounds are subsequently removed using Gaussian process regression. The final power spectra are constructed from the gridded residual data cubes in the $u plane. Signal injection tests are performed at each step of the analysis pipeline, the relevant pipeline settings are optimized to ensure minimal signal loss, and any signal suppression is accounted for through a bias correction on our final upper limits. We obtain a best 2sigma upper limit of $2.4 mK $ at $z$ = 20.3 and $k$ = 0.041 $h\ cMpc $. We see a strong excess power in the data, making our upper limits two orders of magnitude higher than the thermal noise limit. We investigate the origin and nature of this excess power and discuss further improvements to the analysis pipeline that can potentially mitigate it and consequently allow us to reach thermal noise sensitivity when multiple nights of observations are processed in the future.

Thermal tolerance plasticity and dynamics of thermal tolerance in Eublepharis macularius: Implications for future climate-driven heat stress

The intensity and duration of heat waves, as well as average global temperatures, are expected to increase due to climate change. Heat waves can cause physiological stress and reduce fitness in animals. Species can reduce overheating risk through phenotypic plasticity, which allows them to raise their thermal tolerance limits over time. This mechanism could be important for ectotherms whose body temperatures are directly influenced by available environmental temperatures. Geckos are a large, diverse group of ectotherms that vary in their thermal habitats and times of daily activity, which could affect how they physiologically adjust to heat waves. Data on thermal physiology are scarce for reptiles, with only one study in geckos. Understanding thermal tolerance and plasticity, and their relationship, is essential for understanding how some species are able to adjust or adapt to changing temperatures. In this study, we estimated thermal tolerance and plasticity, and their interaction, in the crepuscular gecko, Eublepharis macularius, a species that is emerging as a model for reptile biology. After estimating basal thermal tolerance for 28 geckos, thermal tolerance was measured for each individual a second time at several timepoints (3, 6, or 24 h) to determine thermal tolerance plasticity. We found that thermal tolerance plasticity (1) does not depend on the basal thermal tolerance of the organism, (2) was highest after 6 h from initial heat shock, and (3) was negatively influenced by individual body mass. Our findings contribute to the increasing body of work focused on understanding the influence of biological and environmental factors on thermal tolerance plasticity in organisms and provide phenotypic data to further investigate the molecular basis of thermal tolerance plasticity in organisms.

Hot, dry, and salty: The present and future of an Extremophile model lizard from Argentina

Global warming poses a threat to lizard populations by raising ambient temperatures above historical norms and reducing thermoregulation opportunities. Whereas the reptile fauna of desert systems is relatively well studied, the lizard fauna of saline environments has not received much attention and—to our knowledge—thermal ecology and the effects of global warming on lizards from saline environments have not been yet addressed. This pioneer study investigates the thermal ecology, locomotor performance and potential effects of climate warming on Liolaemus ditadai, a lizard endemic to one of the largest salt flats on Earth. We sampled L. ditadai using traps and active searches along its known distribution, as well as in other areas within Salinas Grandes and Salinas de Ambargasta, where the species had not been previously recorded. Using ensemble models (GAM, MARS, RandomForest), we modeled climatically suitable habitats for L. ditadai in the present and under a pessimistic future scenario (SSP585, 2070). L. ditadai emerges as an efficient thermoregulator, tolerating temperatures near its upper thermal limits. Our ecophysiological model suggests that available activity hours predict its distribution, and the projected temperature increase due to global climate change should minimally impact its persistence or may even have a positive effect on suitable thermal habitat. However, this theoretical increase in habitat could be linked to the distribution of halophilous scrub in the future. Our surveys reveal widespread distribution along the borders of Salinas Grandes and Salinas de Ambargasta, suggesting a potential presence along the entire border of both salt plains wherever halophytic vegetation exists. Optimistic model results, extended distribution, and no evidence of flood-related adverse effects offer insights into assessing the conservation status of L. ditadai, making it and the Salinas Grandes system suitable models for studying lizard ecophysiology in largely unknown saline environments.

Engineering a Robust UDP-Glucose Pyrophosphorylase for Enhanced Biocatalytic Synthesis via ProteinMPNN and Ancestral Sequence Reconstruction.

UDP-glucose is a key metabolite in carbohydrate metabolism and plays a vital role in glycosyl transfer reactions. Its significance spans across the food and agricultural industries. This study focuses on UDP-glucose synthesis via multienzyme catalysis using dextrin, incorporating UTP production and ATP regeneration modules to reduce costs. To address thermal stability limitations of the key UDP-glucose pyrophosphorylase (UGP), a deep learning-based protein sequence design approach and ancestral sequence reconstruction are employed to engineer a thermally stable UGP variant. The engineered UGP variant is significantly 500-fold more thermally stable at 60 °C and has a half-life of 49.8 h compared to the wild-type enzyme. MD simulations and umbrella sampling calculations provide insights into the mechanism behind the enhanced thermal stability. Experimental validation demonstrates that the engineered UGP variant can produce 52.6 mM UDP-glucose within 6 h in an in vitro cascade reaction. This study offers practical insights for efficient UDP-glucose synthesis methods.

Flight or fight: different strategies of intertidal periwinkle Littoraria sinensis coping with high temperature across populations.

Intertidal organisms usually live near their upper thermal limits, and are vulnerable to future global warming. As a vital response to thermal stress, thermoregulatory strategy in physiological and behavioral performance is essential for organisms coping with thermal stressand surviving the changing world. To investigate the relationship between the thermoregulatory strategy and habitat temperature, in the present study, we comparatively investigated the thermal responsive strategy among different geographic populations of the supralittoral snail Littoraria sinensis by determining snails' cardiac function and behavioral performance. Our results indicated that populations inhabiting high ambient temperatures had higher sublethal temperatures (i.e. Arrhenius breakpoint temperatures, ABTs, the temperature at which the heart rate shapely decreases with further heating) and lethal temperatures (i.e. Flatline temperatures, FLTs, the temperature at which heart rate ceases), and behaved less actively (e.g. shorter moving distances and shorter moving time) in the face of high and rising temperatures-a physiological fight strategy. On the other hand, populations at relatively low ambient temperatures had relatively lower physiological upper thermal limits with lower ABTs and FLTs and moved more actively in the face of high and rising temperatures-a behavioral flight strategy. These results demonstrate that the thermoregulatory strategies of the snails are closely related to their habitat temperaturesand are different among populations surviving divergent thermal environments.

Thermal and loss modeling of scaled permanent magnet synchronous machines for automotive driving cycles

With the goal of enhancing the efficiency of electric vehicles and improving the driving range, the appropriate dimensioning, so-called “right-sizing,” of the electric machines is a promising approach. This paper presents an efficient approach of scaling the thermal parameters in a low order lumped parameter thermal network (LPTN) model to estimate the temperature of the scaled permanent magnet synchronous machine (PMSM) by taking into account the temperature dependence of the power losses. At an early stage of development, the proposed scaling approach enables a preliminary evaluation of the thermal limit of the PMSM within the optimization of the electric powertrain and offers a notable benefit in that the low order LPTN model can easily be parameterized and scaled based on the experimental measurements. Validation for both axial scaling and radial scaling with factors ranging from 0.8 to 1.2 was carried out on a previously validated Ansys Motor-CAD model for typical automotive driving cycles. The maximum temperature error between the scaling approach and the Ansys Motor-CAD model is less than 3.5°C.