Spatio-Temporal Heterogeneity of Climate Warming in the Chinese Tianshan Mountainous Region

The Chinese Tianshan mountainous region (CTMR) is a typical alpine region with high topographic heterogeneity, characterized by a large altitude span, complex topography, and diverse landscapes. A significant increase in air temperature had occurred in the CTMR during the last five decades. However, the detailed, comprehensive, and systematical characteristics of climate warming, such as its temporal and spatial heterogeneity, remain unclear. In this study, the temporal and spatial heterogeneity of climate warming across the CTMR had been comprehensively analyzed based on the 10-day air temperature data gathered during 1961–2020 from 26 meteorological stations. The results revealed local cooling in the context of general warming in the CTMR. The amplitude of variation (AV) varied from −0.57 to 3.64 °C, with the average value of 1.19 °C during the last six decades. The lapse rates of the elevation-dependent warming that existed annually, and in spring, summer, and autumn are −0.5 °C/100 m, −0.5 °C/100 m, −0.7 °C/100 m, and −0.4 °C/100 m, respectively. The warming in the CTMR is characteristic of high temporal heterogeneity, as represented by the amplified warming at 10-d scale for more than half a year, and the values of AV were higher than 1.09 °C of the global warming during 2011–2020 (GWV2011–2020). Meanwhile, the amplitudes of warming differed greatly on a seasonal scale, with the rates in spring, autumn, and winter higher than that in summer. The large spatial heterogeneity of climate warming also occurred across the CTMR. The warming pole existed in the warm part, the Turpan-Hami basin (below 1000 m asl) where the air temperature itself was high. That is, the warm places were warmer across the CTMR. The cooling pole was also found in the Kuqa region (about 1000 m asl). This study could greatly improve the understanding of the spatio-temporal dynamics, patterns, and regional heterogeneity of climate warming across the CTMR and even northwest China.

Distinguishing Time Scales of Katabatic Flow in Complex Terrain

To examine spatial and temporal scales of katabatic flow, a distributed temperature sensing (DTS) optical fiber was deployed 2 km down a mild slope irregularly interrupted by small-scale drainage features as part of the Mountain Terrain Atmospheric Modeling and Observation (MATERHORN) experiment conducted at the U.S. Army Dugway Proving Ground, Utah. The fiber was suspended at two heights near the surface, enabling measurement of variations in lapse rate near the surface at meter-scale spatial resolution with 1-min temporal resolution. Experimental results derived from the DTS and tower-mounted instrumentation indicate that airflow through small-scale drainage features regulated the local cooling rate whereas topographic slope and distance along the drainage strongly influenced the larger-scale cooling rate. Empirical results indicate that local cooling rate decays exponentially after local sunset and basin-wide cooling rate decreases linearly with time. The difference in the functional form for cooling rate between local and basin-wide scales suggests that small-scale features have faster timescales that manifests most strongly shortly after local sunset. More generally, partitioning drainage flow by scale provides insight and a methodology for improved understanding of drainage flow in complex terrain.

Reverse heat flow with Peltier-induced thermoinductive effect

The concept of “thermal inductance” expands the options of thermal circuits design. However, the inductive component is the only missing components in thermal circuits unlike their electromagnetic counterparts. Herein, we report an electrically controllable reverse heat flow, in which heat flows from a low-temperature side to a high-temperature side locally and temporarily in a single material by imposing thermal inertia and ac current. This effect can be regarded as an equivalent of the “thermoinductive” effect induced by the Peltier effect. We derive the exact solution indicating that this reverse heat flow occurs universally in solid-state systems, and that it is considerably enhanced by thermoelectric properties. A local cooling of 25 mK is demonstrated in (Bi,Sb)2Te3, which is explained by our exact solution. This effect can be directly applicable to the potential fabrication of “thermoinductor” in thermal circuits.

Myocardial Contractility in Young People During Cold Exposure of the Foot

This paper studied the physiological response of the human circulatory system to local cooling of the feet. The research involved young men (n = 27) and women (n = 30) aged between 17 and 20 years, born and permanently living in the Arctic zone of the Russian Federation (Arkhangelsk). SIMONA 111 integrated monitoring system was used. We found that stimulation of peripheral temperature-sensitive receptors of the foot skin at local cooling causes a decrease in heart contractility in both sexes, while young women demonstrate greater sensitivity to the cold factor than young men. For citation: Korobitsyna E.V., Gudkov A.B., Popova O.N., Shcherbina Yu.F. Myocardial Contractility in Young People During Cold Exposure of the Foot. Journal of Medical and Biological Research, 2021, vol. 9, no. 4, pp. 459–462. DOI: 10.37482/2687-1491-Z084

Study on Distribution of Wellbore Temperature in Gas Drilling with Gradient Equations

Precise calculation of gas temperature profile is the key to gas drilling design. It is traditionally assumed that the gas temperature distribution in the wellbore is equal to the formation temperature, without considering the influence of fluid flow and Joule-Thomson cooling effect. This paper puts forward a gradient equation method for gas temperature distribution in wellbore considering gas flow and Joule-Thomson local cooling of the bit. The method applies pressure, temperature, density, and velocity equations to gas flow in drillstrings and annulus. The solution of the gradient equation is in the form of the fourth-order Runge-Kutta equation. Bottom wellbore temperatures measured at depths of 700 to 2000 m in an actual well are consistent with those predicted by the gradient method. Due to the Joule-Thomson cooling effect at the bit nozzle, the temperature drops by about 30°C. The sensitivity analysis is carried out by gradient method, and the results show that the temperature drop range of different nozzle sizes can reach 60°C due to the Joule-Thomson cooling effect. Stable temperature curves can be established within a few minutes of the gas cycle. Due to the influence of gas flow and Joule-Thomson cooling, the gas temperature in the wellbore deviates significantly from the geothermal temperature in the formation under the flow condition. The temperature of the gas in drillstrings increases as the drill depth increases and then decreases rapidly near the bottom of the hole. As the gas flows upward along the annulus, the gas temperature rises first, surpasses the formation temperature, and then decreases gradually along the geothermal gradient trend.

Characterization of High-Density Aircraft Electronic and Thermal Management Systems

As aircrafts move toward electrification with the research and development of hybrid-electric powertrains, the focus has begun to shift to the reliability challenges of electronic devices subject to flight. Electronic components in aircraft applications are subject to two main sources of failure inducing stresses: the thermomechanical stresses that develop due to unequal coefficients of thermal expansion of different materials used in the components, and the stresses developing due to shocks and vibrations during flight as well as landing and takeoff. While the challenge of dealing with CTE mismatches is applicable to electronic devices in general, the ambient conditions surrounding the aircraft in flight, combined with weight and space constrains add significant logistical issues to any cooling mechanism. This paper will focus on the environmental influence on the thermal dissipation profile that will ultimately lead to CTE failures. The push toward more-electric-aircraft (MEA) increases the need to further advance the power and versatility of electronic cooling systems to adequately manage high density power modules, which until recently were not highly incorporated in aviation systems. Environmental conditions will play a large role in the design space and limitations of potential cooling solutions and will dictate the effectiveness of current thermal management systems. In arising scenarios where high-density electronics cannot be contained within a pressurized and temperature-controlled cabin, drastic pressure and temperature swings, facilitated by the external environment, will lead to an extra source of fluctuating stress on the cooling system. This is likely to be a prevalent factor in hybrid-electric and all-electric powertrains as requiring environmental controlled spaces for major components could be limited. This can easily be seen in current attempts to examine and redesign local cooling systems for electric motors in aviation. Representing just one of the major cooling requirements on an electric aircraft, motor cooling systems demonstrate the universal cooling problems limiting all aspects of the powertrains system. This paper aims to define the impact of the changing environment, through a flight profile of an aircraft, on high density electronic cooling systems by assessing the potential system stressors that significantly impact performance, efficiency, and reliability of the cooling systems. It will also utilize local cooling efforts for motors to relate the general problems to applicable design considerations that must be understood to further the performance capability of the overall propulsion system.

Identifying the need for locally-observed wet bulb globe temperature across outdoor athletic venues for current and future climates in a desert environment

Exertional heat illness and stroke are serious concerns across youth and college sports programs. While some teams and governing bodies have adopted the wet bulb globe temperature (WBGT), few practitioners use measurements on the field of play; rather, they often rely on regionally modeled or estimated WBGT. However, urban development-induced heat and projected climate change increase exposure to heat. We examined WBGT levels between various athletic surfaces and regional weather stations under current and projected climates and in hot-humid and hot-dry weather regimes in the southwest U.S. in Tempe, Arizona. On-site sun-exposed WBGT data across five days (07:00–19:00 local time) in June (dry) and August (humid) were collected over five athletic surfaces: rubber, artificial turf, clay, grass, and asphalt. Weather stations data were used to estimate regional WBGT (via the Liljegren model) and compared to on-site, observed WBGT. Finally, projected changes to WBGT were modeled under mid-century and late-century conditions. On-field WBGT observations were, on average, significantly higher than WBGT estimated from regional weather stations by 2.4°C–2.5°C, with mean on-field WBGT across both months of 28.52.76°C (versus 25.83.21°C regionally). However, between-athletic surface WBGT differences were largely insignificant. Significantly higher mean WBGTs occurred in August (30.12.35°C) versus June (26.92.19°C) across all venues; August conditions reached ‘limit activity’ or ‘cancellation’ thresholds for 6–8 hours and 2–4 hours of the day, respectively, for all sports venues. Climate projections show increased WBGTs across measurement locations, dependent on projection and period, with average August WBGT under the highest representative concentration pathway causing all-day activity cancellations. Practitioners are encouraged to use WBGT devices within the vicinity of the fields of play, yet should not rely on weather station estimations without corrections used. Heat concerns are expected to increase in the future, underlining the need for athlete monitoring, local cooling design strategies, and heat adaptation for safety.

Influence of Spatial Characteristics of Green Spaces on Microclimate: A Case Study in Suzhou Industrial Park, China

Continuous urban development leads to urban heat island effects. Research suggests that urban green spaces can help effectively reduce urban heat island effects in the summer. Previous studies have mainly focused on the influence of different underlying surfaces on air cooling and humidification. There is a lack of in-depth research on the relationship between park structure and microclimatic effects. Here, we examined the main landscape parameters of green spaces in 15 parks located in Suzhou Industrial Park (SIP) with a subtropical maritime monsoon climate zone during the summer to analyze their influence on the microclimate. The average cooling and humidifying effect of medium-size green spaces was most significant during high-temperature hours in the daytime. When the distance to a water body was the same, the average cooling and humidifying effect ranked as follows: large-size green space > small-size green space > medium-size green space. We explored the mechanisms of the local cooling and humidifying effects of woodland and water areas in parks by numerical simulations. The significance of the cooling and humidifying effects of water areas of different shapes was as follows: annular water > massive water > banded water. This confirmed that the shape and size of water areas within a green space has a significant influence on local cooling and humidification.

The Effect of Local Cooling at the Elbow on Nerve Conduction Velocity and Motor Unit Behaviour: An Exploration of a Novel Neurological Assessment

Background: This study aimed to determine the effects of a standard therapeutic cooling protocol using crushed ice on the elbow to explore if changes in the motor unit (MU) firing rates in the first dorsal interosseous (FDI) muscle are comparable to known changes in sensory and motor nerve conduction velocity (NCV) due to a regional temperature drop around a peripheral nerve. Methods: Twelve healthy individuals were assessed before cooling, immediately after cooling, and 15 min of rewarming. Assessments included two standard non-invasive nerve conduction velocity tests and a non-invasive investigation of the MU firing rates using surface electromyography decomposition (dEMG). Results: Repeated ANOVAs showed significant differences in the MU firing rates and NCV between time points (p = 0.01 and p < 0.001). All measures showed significant differences between pre and post cooling and between pre-cooling and 15 min of passive re-warming, however, no changes were seen between post cooling and rewarming except in the sensory NCV, which increased but did not return to the pre-cooled state. Conclusions: This current study showed a significant, temporary, and reversible reduction in ulnar NCV across the elbow in healthy subjects, which was associated with a significant decrease in mean MU firing rates in the FDI muscle.