Hasil untuk "Heat"

Je-Chin Han, Sandip Dutta, S. Ekkad

T. Vilaro, C. Colin, J. Bartout

R. Mittler, Andrija Finka, P. Goloubinoff

Brooke G. Anderson, M. Bell

D. Renaudeau, A. Collin, S. Yahav et al.

Despite many challenges faced by animal producers, including environmental problems, diseases, economic pressure, and feed availability, it is still predicted that animal production in developing countries will continue to sustain the future growth of the world's meat production. In these areas, livestock performance is generally lower than those obtained in Western Europe and North America. Although many factors can be involved, climatic factors are among the first and crucial limiting factors of the development of animal production in warm regions. In addition, global warming will further accentuate heat stress-related problems. The objective of this paper was to review the effective strategies to alleviate heat stress in the context of tropical livestock production systems. These strategies can be classified into three groups: those increasing feed intake or decreasing metabolic heat production, those enhancing heat-loss capacities, and those involving genetic selection for heat tolerance. Under heat stress, improved production should be possible through modifications of diet composition that either promotes a higher intake or compensates the low feed consumption. In addition, altering feeding management such as a change in feeding time and/or frequency, are efficient tools to avoid excessive heat load and improve survival rate, especially in poultry. Methods to enhance heat exchange between the environment and the animal and those changing the environment to prevent or limit heat stress can be used to improve performance under hot climatic conditions. Although differences in thermal tolerance exist between livestock species (ruminants > monogastrics), there are also large differences between breeds of a species and within each breed. Consequently, the opportunity may exist to improve thermal tolerance of the animals using genetic tools. However, further research is required to quantify the genetic antagonism between adaptation and production traits to evaluate the potential selection response. With the development of molecular biotechnologies, new opportunities are available to characterize gene expression and identify key cellular responses to heat stress. These new tools will enable scientists to improve the accuracy and the efficiency of selection for heat tolerance. Epigenetic regulation of gene expression and thermal imprinting of the genome could also be an efficient method to improve thermal tolerance. Such techniques (e.g. perinatal heat acclimation) are currently being experimented in chicken.

Wenhua Yu, D. M. France, J. Routbort et al.

R. Memon, D. Leung, Li Chunho

Y. Kawashima, Shigeyashu, Nak et al.

P. S. Gupta, A. Gupta

A. Abhat

R. Ji, T. Samad, Shan-xue Jin et al.

O. Alifanov

A. Bejan

M. Anderson

Xinyu Chen, C. Kang, M. O’Malley et al.

S. Brückner, S. Liu, L. Miró et al.

Devrim Aydin, S. Casey, S. Riffat

F. Adersh, M. Muhsin, M. Sahoo

We theoretically investigate the thermodynamic performance characteristics of an active magneto-gyrator taking into account the two-dimensional motion of an inertial charged active particle confined in an asymmetric parabolic potential and in contact with two heat baths kept at two different temperatures. A magnetic field of constant magnitude is applied in a direction perpendicular to the plane of motion. In such a system, the particle exhibits a gyrating motion across the potential minimum and exerts a torque on the confining potential as long as there is a potential asymmetry and temperature gradient. Hence, this system can operate as an active magneto-heat engine or pump in the presence of a load force. Interestingly, we observe that the activity or self-propulsion impacts the thermodynamic performance characteristics of the gyrator only in the presence of the magnetic field. We examine two scenarios: first, by applying a load in a direction opposing the torque and second, by applying a load in the same direction as that of torque. In the first case, for a fixed parameter regime, the gyrator is found to act as a heat engine or a heat pump depending on the strength of the applied load, whereas in the latter case, it can only operate as a heat pump. Moreover, unlike the Brownian gyrator or Brownian magneto gyrator, captivatingly, the efficiency is found to have no universal upper bound and can be made $100\%$ by tuning the system parameters. Additionally, when the system is suspended in a viscoelastic medium characterized by the presence of a finite memory, for a short persistence of memory and a fixed duration of activity, the efficiency can be $100\%$ even for more than one value of viscoelastic memory timescale.

Junpo Yu, Yajun Si, Wen Zhao et al.

As the world’s largest loess deposit region, the Loess Plateau’s vegetation dynamics are crucial for its regional water–heat balance and ecosystem functioning. Leaf Area Index (LAI) serves as a key indicator bridging canopy architecture and plant physiological activities. Existing studies have made significant advancements in simulating LAI, yet accurate LAI simulation remains challenging. To address this challenge and gain deeper insights into the environmental controls of LAI, this study aims to accurately simulate LAI in the Loess Plateau using deep learning models and to elucidate the spatiotemporal influence of soil moisture and temperature on LAI dynamics. For this purpose, we used three deep learning models, namely Artificial Neural Network (ANN), Long Short-Term Memory (LSTM), and Interpretable Multivariable (IMV)-LSTM, to simulate LAI in the Loess Plateau, only using soil moisture and temperature as inputs. Results indicated that our approach outperformed traditional models and effectively captured LAI variations across different vegetation types. The attention analysis revealed that soil moisture mainly influenced LAI in the arid northwest and temperature was the predominant effect in the humid southeast. Seasonally, soil moisture was crucial in spring and summer, notably in grasslands and croplands, whereas temperature dominated in autumn and winter. Notably, forests had the longest temperature-sensitive periods. As LAI increased, soil moisture became more influential, and at peak LAI, both factors exerted varying controls on different vegetation types. These findings demonstrated the strength of deep learning for simulating vegetation–climate interactions and provided insights into hydrothermal regulation mechanisms in semiarid regions.

Kyuhae Min, Taejun Kang, Tae Yeob Kang et al.

As data centers expand, immersion cooling systems are gaining attention for thermal management of memory devices. To enable widespread adoption, it is essential to evaluate the impact of coolants on the reliability of memory packages. In this study, high-voltage direct current (DC) stress tests were conducted on commercial dynamic random access memory (DRAM) packages in both single-phase coolant and air environments to analyze heat generation and electrical characteristics. A DC voltage ranging from 2.5 to 3.1 V, which is higher than the regular operating voltage of 1.2 V, was applied. Temperature changes were measured using an infrared camera in the air, and a contact-based thermometer in the coolant. The leakage current was also evaluated through I-V curve analysis. Heat generation and changes in leakage currents were not significant in either environment until the applied voltage stress exceeded approximately twice the standard voltage (2.5–2.8 V). However, the package’s degradation accelerated when the applied voltages exceeded 3.0 V, demonstrating a nonlinear increase in temperature and leakage current.