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1. The role of energy in ecological processes has hitherto been considered primarily from the standpoint that energy supply is limited. That is, traditional resource-based ecological and evolutionary theories and the recent 'metabolic theory of ecology' (MTE) all assume that energetic constraints operate on the supply side of the energy balance equation. 2. For endothermic animals, we provide evidence suggesting that an upper boundary on total energy expenditure is imposed by the maximal capacity to dissipate body heat and therefore avoid the detrimental consequences of hyperthermia - the heat dissipation limit (HDL) theory. We contend that the HDL is a major constraint operating on the expenditure side of the energy balance equation, and that processes that generate heat compete and trade-off within a total boundary defined by heat dissipation capacity, rather than competing for limited energy supply. 3. The HDL theory predicts that daily energy expenditure should scale in relation to body mass (Mb) with an exponent of about 0·63. This contrasts the prediction of the MTE of an exponent of 0·75. 4. We compiled empirical data on field metabolic rate (FMR) measured by the doubly-labelled water method, and found that they scale to Mb with exponents of 0·647 in mammals and 0·658 in birds, not significantly different from the HDL prediction (P > 0·05) but lower than predicted by the MTE (P < 0·001). The same statistical result was obtained using phylogenetically independent contrasts analysis. Quantitative predictions of the model matched the empirical data for both mammals and birds. There was no indication of curvature in the relationship between Loge FMR and LogeMb. 5. Together, these data provide strong support for the HDL theory and allow us to reject the MTE, at least when applied to endothermic animals. 6. The HDL theory provides a novel conceptual framework that demands a reframing of our views of the interplay between energy and the environment in endothermic animals, and provides many new interpretations of ecological and evolutionary phenomena.

Under cold shutdown conditions, the heat dissipation performance of the high-pressure coolant pipeline critically impacts pressurized water reactor (PWR) safety by governing residual heat removal efficiency. To quantify key drivers of thermal behavior during stagnant coolant operation, a high-fidelity thermal–hydraulic model is established by using the REALP5 MOD3.2 code. Systematic parametric analyses evaluate radiation effects and insulation-environment interactions through three dimensions. The results show that under stagnant coolant and zero-wind conditions, radiation contributes 90% of total heat transfer in the high-pressure coolant pipeline in the vertical direction, yielding a larger coolant temperature drop (ΔT) of 6.12 K over 86,400 s compared to the no-radiation model. Pipeline heat dissipation exhibits an inverse relationship with insulation cotton thickness but scales positively with material thermal conductivity. Within 800,000 s, when the insulation cotton thickness(δ) is reduced from 15 to 5 mm, the coolant temperature drops by nearly 18 K. This means that for every 10 mm reduction in the thickness of insulation cotton(δ), the heat dissipation efficiency increases by 40%. The coolant temperature drop (ΔT) of the pipe with asbestos insulation (thermal conductivity λ = 0.046W /(m·K)) reaches 43.98 K, which is 53.1% higher than that of the pipe with ultra-fine glass fiber cotton insulation(ΔT = 28.72 K) (thermal conductivity λ = 0.022W /(m·K)). Ambient temperature and airflow velocity exhibit inverse and positive correlations with coolant temperature drop (ΔT), the coolant temperature is reduced by 12.51 K more than the ambient temperature of 10℃ and 30℃. For every 1℃ decrease in ambient temperature, the temperature drop increases by 0.625 K. When the airflow velocity is 0.5 m/s compared to 0.1 m/s, the coolant temperature drops by 1.65 K more. This paper pioneers a high-fidelity thermo-hydraulic model of the main coolant pipeline of PWR under the stagnation condition after cold shutdown, which advances the theoretical framework of heat dissipation such as natural convection in the external environment and provides a quantitative safety margin for the removal of waste heat from the core. Further, it guides the design of insulation cotton material and the thickness of the high-pressure coolant pipeline and delivers predictive tools for the optimization of the heat dissipation strategy after cold shutdown.

3D printing-assisted streamline orientation method was proposed to fabricate composite thermal materials. Mechanism of fluid-based filler orientation control along streamlines was revealed. Thermal conductivity of 3D mesh-shape PDMS/LM composite was 4.8 times higher than that of random PDMS/LM composite. 3D-PSO method exhibits programmable design capability to adopt versatile distributions of heat sources. Filler-reinforced polymer composites demonstrate pervasive applications due to their strengthened performances, multi-degree tunability, and ease of manufacturing. In thermal management field, polymer composites reinforced with thermally conductive fillers are widely adopted as thermal interface materials (TIMs). However, the three dimensional (3D)-stacked heterogenous integration of electronic devices has posed the problem that high-density heat sources are spatially distributed in the package. This situation puts forward new requirements for TIMs, where efficient heat dissipation channels must be established according to the specific distribution of discrete heat sources. To address this challenge, a 3D printing-assisted streamline orientation (3D-PSO) method was proposed to fabricate composite thermal materials with 3D programmable microstructures and orientations of fillers, which combines the shape-design capability of 3D printing and oriented control ability of fluid. The mechanism of fluid-based filler orientation control along streamlines was revealed by mechanical analysis of fillers in matrix. Thanks to the designed heat dissipation channels, composites showed better thermal and mechanical properties in comparison to random composites. Specifically, the thermal conductivity of 3D mesh-shape polydimethylsiloxane/liquid metal (PDMS/LM) composite was 5.8 times that of random PDMS/LM composite under filler loading of 34.8 vol%. The thermal conductivity enhancement efficiency of 3D mesh-shape PDMS/carbon fibers composite reached 101.05% under filler loading of 5.2 vol%. In the heat dissipation application of 3D-stacked chips, the highest chip temperature with 3D-PSO composite was 42.14 °C lower than that with random composites. This is mainly attributed to the locally aggregated and oriented fillers’ microstructure in fluid channels, which contributes to thermal percolation phenomena. The 3D-PSO method exhibits excellent programmable design capabilities to adopt versatile distributions of heat sources, paving a new way to solve the complicated heat dissipation issue in 3D-stacked chips integration application.

A low-cost signal processing circuit developed to measure and drive a heat dissipation soil matric potential sensor based on a single thermosensitive resistor is demonstrated. The SnSe2 has a high thermal coefficient, from −2.4Ω/°C in the 20 to 25 °C to −1.07Ω/°C in the 20 to 25 °C. The SnSe2 thermosensitive resistor is encapsulated with a porous gypsum block and is used as both the heating and temperature sensing element. To control the power dissipated on the thermosensitive resistor and keep it constant during the heat pulse, a mixed analogue/digital circuit is used. The developed control circuit is able to maintain the dissipated power at 327.98±0.3% mW when the resistor changes from 94.96Ω to 86.23Ω. When the gravimetric water content of the porous block changes from dry to saturated (θw=36.7%), we measured a variation of 4.77Ω in the thermosensitive resistor, which results in an end-point sensitivity of 130 mΩ/%. The developed system can easily meet the standard requirement of measuring the gravimetric soil water content with a resolution of approximately Δθw=1%, since the resistance is measured with a resolution of approximately μ31μΩ, three orders of magnitude smaller than the sensitivity.

In this paper, the thermal management of missile-borne components in a flight state is studied. Avoiding excessive component temperatures under the high-temperature circumstances brought by aerodynamic heat is a requirement to guarantee the equipment’s safe and reliable operation. In this work, we designed four finned shell constructions for a phase change module using the phase change temperature control method and then studied their effects on the module’s ability to dissipate heat using an experimental approach. Three sizes of 30 mm, 40 mm, and 50 mm heating pads were used to replicate heat sources with various heat flux densities and heat dissipation regions, with reference to the heating characteristics of various chips. The results demonstrated that the square-shaped fin had the best heat dissipation effect after operating for 10 min under the power of 10 W and 20 W, while the strip-shaped fins exhibited the highest performance under the power of 30 W. The square-shaped fins had the best heat dissipation effect when reducing working time to 5 min. This paper proposes the optimal fin scheme under different power densities, as well as an enhanced heat dissipation idea for the melting process of the phase change materials based on the test results.

The aerodynamics and heat transfer performance in the rear-mounted automobile cabin have an important influence on the engine's safety and the operational stability of the automobile. The article uses STAR-CCM and GT-COOL software to establish the 3D wind tunnel model and engine cooling system model of the internal combustion engine. At the same time, we established a 3D artificial coupling model through parameter transfer. The research results show that the heat transfer coefficient decreases with the increase of the comprehensive drag coefficient of the nacelle. This shows that the cabin flow field has an important influence on the heat transfer coefficient. The mainstream temperature rise of the engine room increases with the increase of the engine load. It is proved that vehicle speed affects the amount of heat dissipation of the engine room internal combustion engine under certain load conditions. The article provides a more effective and fast calculation method for the research on the heat dissipation of the internal combustion engine and the optimization of the cooling system equipment.

The increase of mining depth of mines causes the rising temperature of surrounding rocks, especially the non-steady heat dissipation of surrounding rocks in roadways, which is influenced by multiple factors. By establishing a mathematical model for non-steady heat dissipation of surrounding rocks in mines, the main factors (including lithology of surrounding rocks, ventilation velocity, equivalent radius and ventilation time of roadway) influencing the wall temperature and heat dissipation capacity of surrounding rocks were determined. The relationship between wall temperature and surrounding rock heat dissipation with various influencing factors was analyzed. The research results show that it can be seen that under the influences of different lithology, equivalent radius and ventilation velocities, the wall temperature of surrounding rocks constantly declined, while the heat dissipation capacity of surrounding rocks rose at first and then decreased, with the prolongation of ventilation time. And there is a maximum value of heat dissipation in surrounding rock. By calculating the maximum of heat dissipation capacity of surrounding rocks, it can be seen that the values of wall temperature of surrounding rocks exhibited certain consistency, keeping in the range of 303–304 K.

Black locust (Robinia pseudoacacia L.) is a major tree species in China’s large-scale afforestation. Despite its significance, black locust is underrepresented in sap flow literature; moreover, the published water consumption data might be biased. We applied two field methods to estimate water consumption of black locust during the growing seasons in 2012 and 2013. The application of Granier’s original sap flow method produced a very low transpiration rate (0.08 mm d−1) while the soil water balance method yielded a much higher rate (1.4 mm d−1). A dye experiment to determine the active sapwood area showed that only the outermost annual ring is responsible for conducting water, which was not considered in many previous studies. Moreover, an in situ calibration experiment was conducted to improve the reliability of Granier’s method. Validation showed a good agreement in estimates of the transpiration rate between the different methods. It is known from many studies that black locust plantations contribute to the significant decline of discharge in the Yellow River basin. Our estimate of tree transpiration at stand scale confirms these results. This study provides a basis for and advances the argument for the development of more sustainable forest management strategies, which better balance forest-related ecosystem services such as soil conservation and water supply.

In the current study, a new configuration of minichannels is proposed to improve the thermal performance of conventional plate-fin aluminum heat sink used for the thermal management of the electronic components. The case under consideration to implement the current idea is an aluminum heat sink equipped with rectangular square minichannels. Hence, an enhanced model is investigated, and the obtained results are evaluated as compared with the conventional plate-fin aluminum heat sink. A minichannel heat sink (MC-HS) that has 18 parallel minichannels was developed on the aluminum plate and charged with acetone. The experimental results demonstrated that the proposed MC-HS startup was successfully under a heat load ranging from 10 to 40 W in the vertical orientation. From the investigations, a MC-HS is found to be more effective for the thermal management of the electronic components than the conventional method. The thermal resistance of the MC-HS is 20–31% lower in comparison with the conventional plate-fin aluminum heat sink. It is shown that the MC-HS not only surpasses the conventional solution but also provides greater thermal management of the electronic components.