Average Temperature Difference Research Articles

Thermal characteristics analysis and cooling model optimization of motorized spindle

Aiming at the influence of poor cooling conditions and traditional cooling control strategy on motorized spindle temperature and machining performance. Firstly, the heat transfer model of the motorized spindle cooling system is studied. Secondly, the influence of coolant inlet flow rate and temperature on the thermal characteristics of the motorized spindle is studied. Then, a thermal network model is established to solve the temperature of each temperature measuring point. Finally, the thermal characteristic experiment of the motorized spindle is carried out, and the cooling fluid flow optimization model is established based on the particle swarm optimization algorithm and simulated annealing algorithm. The results show that the temperature difference of the motorized spindle does not exceed 45 °C, the thermal deformation does not exceed 40.2 μm, and the thermal elongation is inhibited by 36 %. The maximum error of the Thermal Network Method and Finite Element Method（FEM）is 14.24 %. The utilization of the average logarithmic temperature difference for assessing the cooling effectiveness of optimal flow rates revealed that the particle swarm optimization algorithm demonstrates a comparatively lower average logarithmic temperature difference in comparison to the simulated annealing algorithm. The heat exchange efficiency of the motorized spindle is higher under the optimal flow rate obtained by the particle swarm algorithm.

Novel Correlations for flow and heat transfer processes in S-CO2 Brayton cycle with different roughness by experimental and simulation methods

This study comprehensively examines heat transfer performance of supercritical carbon dioxide (S-CO2) in horizontal tubes under actual operating conditions of precooler, regenerator and heater, with a focus on the impact of tube roughness. By employing both experimental and numerical methods, it aims to bridge the gap in current research regarding S-CO2 heat exchanger performance that incorporates the effect of roughness. The results indicate that roughness height can suppress the influence of buoyancy effects. As roughness height increases from 1.5 μm to 100 μm, average temperature difference of heater at an outlet temperature of 1000 K decreases from 134.9 K to 61.1 K. Although roughness height can significantly enhance heat transfer, yet the rate of this enhancement diminishes when the roughness height surpasses 50 μm. To address the need for accurate heat transfer and flow correlations considering roughness, high-precision correlations are proposed and validated. The correlations of precooler, regenerator and heater exhibit average absolute deviations of within 8 %, 10 % and 12 %, respectively. The proposed correlations not only enrich theoretical framework of related fields but also provide a solid foundation for optimizing the design and operation of S-CO2 Brayton cycle, enabling more efficient energy conversion and reduced carbon emissions.

Thermoelectric installation for lifting objects from shallow reservoirs using the freezing method

Objective. The purpose of the study is to develop the design of a thermoelectric installation for lifting objects from shallow reservoirs using the freezing method, as well as its calculation, analysis of parameters and electrical and thermophysical characteristics. Method. The research is based on the use of methods of thermodynamic analysis, full-scale and computational modeling of cryogenic equipment in order to find optimal solutions for the reliability and service life of low-temperature installations. Result. The installation includes a waterproof probe, on the end surface of which, facing the bottom of the reservoir, thermoelectric modules are installed, heat is removed from the hot junctions of which by means of a heat removal system made in the form of an all-metal heat pipe or in the form of a thermal thermosiphon. The connection between the object lifted from the reservoir and the thermoelectric installation is carried out through a cold wall by freezing. The thermoelectric installation was calculated and its parameters were determined. Graphs were constructed and dependencies were obtained describing the main characteristics of TEMs included in the thermoelectric installation. The graphs are presented at a temperature of the hot junctions of the TEM of 300 K and the achievement of such values of the thickness of frozen water ice on the cold wall of the technical device that would allow lifting objects from a reservoir up to 4 m deep. Conclusion. The installation parameters have been determined: the number of TEMs of the DRIFT-1.2 type is 8, the operating power range of a single TEM of the DRIFT-1.2 type is from 14 to 40 W with an average temperature difference between the junctions of 45 K, the supply current is from 3.8 to 7 .6 A with power consumption from 50 to 200 W, coefficient of performance - from 0.1 to 0.45, minimum temperature of the cold wall of the TU - 248 K, a domestically produced thermal thermosyphon is used as a heat removal system from the hot junctions of the TEM.

Performance investigation of a building-integrated collector based on spectrum splitting technology

Based on solar spectrum splitting technology, a novel concentrating photovoltaic/thermal (CPV/T) solar collector is proposed, which primarily composed of six Fresnel collector units with separate photovoltaic and photothermal modules. The compact overall structure is optimally designed that can be effectively integrated with ordinary buildings while supply both electrical and thermal energy. The proposed collector achieves the maximum annual average optical efficiency when installed north–south axially with a tilt angle approximately equal to the installation latitude, as a 64.97 % in Nanjing (32°N). Simulation analysis shows that the main influencing factors of the system performance are direct solar irradiance, working medium mass flow, and optical efficiency, the theoretical outlet working medium temperature can reach 150 °C while the photovoltaic and photothermal efficiencies are 12.37 % and 39.74 % when the normalized temperature difference T* is 0.06. Further, to verify the theoretical/simulation analysis results, the outdoor experimental tests are conducted and show that the optimal inlet working medium mass flow is 10.8 kg/h, while the efficiencies are 5.99 % and 27.59 %, respectively, that is, the proposed system comprehensive thermal efficiency can reach 43.35 %. The comparative analysis of theoretical research and experimental tests shows that the proposed system has rationality and practical value, which can provide guidance for practical engineering.

Thermal transport of flexural phonons in a rectangular plate

The quantum thermal transport of elastic excitations through a two-dimensional elastic waveguide between two thermal reservoirs is studied. We solve the classical Kirchhoff–Love equation for rectangular plates and explore the dispersion relation for both the symmetric and antisymmetric solutions. Then, we study the phonon transport of these modes within the second quantization framework by analyzing the mean quadratic displacement, from which the energy density current, the temperature field, and conductance are determined. We identify the relevant modes contributing to thermal transport and explore the average temperature difference to reach the high-temperature limit. We expect our results to pave the way for understanding phonon-mediated thermal transport in two-dimensional mesoscopic quantum devices.

Experimental Investigation of Two-Pass Solar Dryer with V-Corrugated Absorber for Potato Slice Drying

Reducing the moisture level of food items can help prevent bacterial development and deterioration, extend shelf life, reduce packaging, and improve storage for convenient transportation. In this paper, a two-pass solar dryer with V-Corrugated absorber plate is developed. Its experimental performance evaluation in forced convection is carried out for potato chip drying. Various parameters like Hourly Variation of Solar Radiation Intensity, Temperature Distribution Curves inside Solar Dryer, Collector Efficiency Curve, Hourly Mass Loss of Potato Slices and Moisture Removal Comparison with Conventional Open Sun Drying Method are calculated and presented graphically. The peak temperature of the absorber plate reached 69.30C, and the air temperature at the collector outlet recorded the highest value at 57.50C. The average temperature difference of 28.580C is obtained for heat transfer by convection between the modified corrugated absorber plate and the air. An important finding in this experimental investigation was that there is an average 6.50C difference in temperature between the hot air exiting the collector and the air available at the bottom of the lower tray of the drying chamber, which should be reduced by applying means of avoiding heat loss. The highest collector efficiency is calculated as 88.9 % at 2 PM. The lowest efficiency is calculated at 9 AM as 66.8 %. The thermal inertia of the system adds to the collector efficiency in the last 2 hours of the experimentation and hence collector performs better than in the morning hours, though the insolation is nearly the same for the first and last two hours of sunshine. The percentage reduction in drying time was found to be 38.9 % for 50 % moisture removal from potato slices as compared to open sun drying.

Experimental and numerical investigations of a diffusion bonded flat-type loop heat pipe for passive thermal management

Previous diffusion bonded loop heat pipes have been researched due to the benefits of this manufacturing technique, which includes direct sealing and maintaining material properties. The previous single-material diffusion bonded loop heat pipes were made of copper, leading to a high heat leak due to high thermal conductivity, causing a reduction in efficiency. This research used a new approach that separated the evaporator from the loop heat pipe while using diffusion bonding to manufacture a loop heat pipe using two materials, copper and stainless steel. This separation allowed for lower thermal conductivity materials to be used to help reduce the heat leak. Two evaporators with different wicks were tested, one made of copper and the other made of polytetrafluoroethylene. Both designs were tested in multiple orientations and operated for a range of 15 W to 45 W with an evaporator to condenser thermal resistance ranging from 2.18 °C/W to 0.004 °C/W. Additionally, a numerical model was developed to predict the performance of both evaporators, with an average temperature difference ranging from 5.5 °C to 6.6 °C for all thermocouple locations. The heat leak ratio was analyzed using the model, and a heat leak ratio of 7.6% to 8.0% and 13.6% to 16.0% for the copper wick and polytetrafluoroethylene wick loop heat pipe was calculated, respectively. This research demonstrates that diffusion bonding copper with a lower thermal conductivity material and using low thermal conductivity sealing material can help reduce the heat leak within diffusion bonded loop heat pipes.

Heat Transfer Enhancement in a 3D-Printed Compact Heat Exchanger

The study describes experimental data on thermal tests during the condensation of HFE7100 refrigerant in a compact heat exchanger. The heat exchanger was manufactured using the additive 3D printing in metal. The material is AISI 316L steel. MPCM slurry was used as the heat exchanger coolant, and water was used as the reference medium. The refrigerant was condensed on a bundle of circular tubes made of steel with an internal/external diameter of di/de = 2/3 mm, while a mixture of water and phase change materials as the coolant flowed through the channels. Few studies consider the heat exchange in condensation using phase change materials; furthermore, there is also a lack of description of heat exchange in small-sized exchangers printed from metal. Most papers deal with computer research, including flow simulations of heat exchange. The study describes the process of heat exchange enhancement using the phase transition of coolant. Experimental data for the mPCM slurry coolant flow was compared to the data of pure water flow as a reference liquid. The tests were carried out under the following thermal and flow conditions: G = 10–450 [kg m−² s−1], q = 2000–25,000 [W m−²], and ts = 30–40 [°C]. The conducted research provided many quantities describing the heat exchange in compact heat exchangers, including heat exchanger heat power, heat exchange coefficient, and heat exchange coefficients for working media. Based on these factors, the thermal performance of the heat exchanger was described. External characteristics include the value of the thermal power and the heat exchange coefficient as a function of the mass flow density of the working medium and the average logarithmic temperature difference. The performance of the heat exchanger was presented as the dependencies of the heat exchange coefficients on the mass flux density and the heat flux density on the heat exchange surface. The thickness of the refrigerant’s condensate film was also determined. Furthermore, a model was proposed to determine the heat exchange coefficient value for the condensing HFE7100 refrigerant on the outer surface of a bundle of smooth tubes inside a compact heat exchanger. According to experimental data, the calculation results were in good agreement with each other, with a range of 25%. These data can be used to design mini condensers that are widely used in practice.

A graph theory-based modelling method for multi-splitting-merging-channel refrigerant-cooled evaporator in battery thermal management

A multi-splitting-merging-channel refrigerant-cooled evaporator can provide non-uniform cooling capacity distribution to match a non-uniform distributed heat flux produced by a battery by properly arranged hierarchical refrigerant channel network, however the design of the refrigerant channels is extremely complex. The purpose of this study is to present a model to support the design of a multi-splitting-merging-channel refrigerant-cooled evaporator, and the model should have the functions of describing various channel network, predicting the refrigerant flow distribution in splitting and merging channels, and accurately presenting temperature distribution at unevenly distributed heat flux. In the model, the distributed parameter modelling approach is applied for predicting the thermal performance distribution; arbitrary kinds of control volumes are normalized into five standard types according to channel structures; the refrigerant flows with multiple splitting and merging are described by the calculation sequences of control volumes, which are generated based on the graph theory. Model validations are done on a small sized and a large sized evaporator samples by comparing the simulated results with the experiment data. It is shown show that, the average temperature deviations of the small sized and the large sized evaporator samples are 1.0 °C and 0.9 °C, respectively while their average pressure drop deviations are 2.8% and 2.1%, respectively. The validation result indicates that the accuracy of the proposed model is acceptable for engineering application.

Registration of thermal images of dead teeth to identify odontogenic infection foci

Infrared thermal imaging (IRT) remotely and contactless maps the temperature on the examined surface, recording the distribution of infrared radiation emitted by each body whose temperature is higher than absolute zero. The aim of the study was to evaluate the usefulness of thermography in the assessment of asymptomatic infection foci in patients with high systemic infection. The 150 cases diagnosed based on roentgenograms, divided into 6 groups of diagnosed odontogenic lesions, along with a control group. Thermal imaging was performed with a FLIR Systems T1020 thermal camera. Thermal image analysis was performed using ThermaCAM Researcher Pro 2.10, MS Office Excel 2022 and Statistica 10. The periapical areas of selected dead teeth were selected as areas of interest. The Mann Whitney’s U test showed statistically significant (p < 0.001) differences in average temperature between each patient’s and healthy group. Depper’s analysis showed statistical significance also between the ZM and BZ groups (p = 0.004). Moreover, obtained results may also suggest that thermal imaging can be useful in identify odontogenic infection foci. The thermal asymmetry of periapical tissues of teeth differentiates dead from living teeth, as well as individual pathologies related to the process of gangrenous pulp decay. Thermographic mapping is a promising diagnostic technique that can detect asymptomatic inflammations that carry the risk of infection of the entire body.

Optimization of water supply parameters for enhanced thermal uniformity in aquaculture ponds under varied working conditions: An experimental study

Aquaculture ponds are critical for the successful rearing of fish larvae, and achieving consistent temperature distribution within these systems is essential for optimal growth conditions. This study explores methods for precise temperature regulation on both the water and atmospheric sides of the pond ecosystem. Based on the original design, systematic changes were made to parameters such as water supply pipe layout, bend angles, perforation rates, and working conditions. Metrics including average temperature, average temperature difference, and extreme temperature difference were utilized to extensively discuss the impacts of these parameters. Through this, temperature distributions across five distinct water supply layouts were analyzed, and the impacts of four different bending angles and perforation rates were evaluated using optimized configurations. Our findings demonstrate that a water supply layout radius of 2000 mm, coupled with a 60° bending angle and a 25 % perforation rate, increased overall temperature uniformity in the pond by 5 %. Additionally, seasonal variations significantly impact temperature distribution in ponds, particularly with different extreme temperature differences observed in winter and summer. Compared to the transitional season and summer, the average temperature difference in the pond during winter decreased by 30 % and 45 %, respectively. It was further revealed that winter conditions naturally yield more uniform water-side temperatures, making seasonal fluctuations irrelevant in determining optimal perforation rates. After the implementation of a water agitator, the average extreme temperature difference decreased from 0.6 K to 0.52 K. In the shallow water layer, the water agitator reduced the extreme temperature difference in the pond by 26 %. The use of water agitators has enhanced thermal uniformity in ponds, thereby improving the growth environment for fish larvae and providing valuable insights for environmental management in aquaculture.

Acupuncture artery technique at Zusanli (ST 36) for Wagner grade 0 diabetic foot

To observe the clinical efficacy of acupuncture artery technique at Zusanli (ST 36) for Wagner grade 0 diabetic foot. Sixty patients with Wagner grade 0 diabetic foot were randomly divided into an observation group and a control group, with 30 patients in each group. Both groups selected bilateral Zusanli (ST 36). In the control group, the needle was inserted about 10 mm under ultrasound guidance to avoid blood vessels in the Zusanli (ST 36) area, with needle retention for 5 min without manipulation. In the observation group, the needle was inserted about 25 mm under ultrasound guidance to the anterior tibial artery branch below Zusanli (ST 36), followed by lifting and thrusting manipulation for 5 min before withdrawing the needle. Both groups were treated twice a week for 4 weeks. The traditional Chinese Medicine (TCM) syndrome scores were observed; infrared thermography was used to measure the temperature difference between the left and right sides in four areas, i.e. the medial malleolus, lateral malleolus, and upper and lower parts of the sole of the foots; Doppler ultrasound was used to measure the logarithm of the peak systolic velocity (ln PS) and the logarithm of the time average maximum velocity (ln TAMAX) of the anterior tibial artery below the right Zusanli (ST 36); the ankle-brachial index (ABI) was measured using Doppler blood flow detector and blood pressure monitor before treatment, after the first treatment, and at the end of treatment. Clinical efficacy was compared between the two groups. Compared before treatment, the TCM syndrome scores in both groups were reduced after the first treatment and at the end of treatment (P<0.01, P<0.05), and the scores in the observation group were lower than those in the control group (P<0.01). In the observation group, compared before treatment, the maximum, minimum, and average temperature differences between the left and right sides of the upper and lower parts of the sole of the foots, medial malleolus, and lateral malleolus were reduced after the first treatment and at the end of treatment (P<0.05, P<0.01). After the first treatment, the maximum temperature difference between the left and right sides of the upper part of the sole of the foots and the medial malleolus in the observation group was lower than that in the control group (P<0.05). At the end of treatment, except for the average temperature difference of the medial malleolus, the maximum, minimum, and average temperature differences between the left and right sides of the upper and lower parts of the sole of the foots, medial malleolus, and lateral malleolus in the observation group were lower than those in the control group (P<0.01, P<0.05). After the first treatment and at the end of treatment, the ln PS, ln TAMAX, and ABI of the anterior tibial artery below the right Zusanli (ST 36) in the observation group were higher than those before treatment (P<0.01) and higher than those in the control group (P<0.01). The total effective rate in the observation group was 96.7% (29/30), higher than 3.3% (1/30) in the control group (P<0.05). Acupuncture artery technique at Zusanli (ST 36) could effectively improve the clinical symptoms of patients with Wagner grade 0 diabetic foot, increase blood flow velocity in the lower limb vessels, and reduce the temperature difference between the left and right lower limbs.

Understanding the differences in the contribution and impact of urbanization on urban warming during heatwave and non-heatwave periods in China

Heatwaves (HW) present a significant threat to human health, making it essential to understand HW trends in China and the interaction between urbanization and HW is crucial for effective climate change adaptation. This study aims to quantify the differences in the contribution and impact of urbanization on urban warming during HW and non-heatwave (NHW) periods in China. By utilizing remote sensing impervious surface data, 2, 421 meteorological stations were dynamically classified into urban and rural stations from 1978 to 2017. The study identified concurrent heatwave (CHW) and NHW periods in both urban and rural areas, exploring the differences in urbanization effect between these periods. The results revealed that most regions in China were experiencing increasingly frequent and severe HW, with the number of HW events and total HW days rising by 0.3 events and 2.2 days per decade, respectively. During CHW periods, the average temperature difference between urban and rural areas increased by 0.33 °C, while the effect of urbanization on urban warming rose by 0.21 °C per decade, compared to NHW period. This indicates a synergistic enhancement of population exposure risk due to HW and urbanization. Over 60% of cities experienced a steeper linear trend in urban temperatures compared to rural areas during CHW, alongside reduced wind speeds and decreased precipitation. Implementing targeted adaptation and mitigation strategies is crucial to mitigating the increased risk of population exposure during HW events.

Optimization of water supply parameters for enhanced thermal uniformity in aquaculture ponds: An experimental study based on orthogonal experimental design

The temperature distribution in aquaculture ponds plays a crucial role in the rearing of fish larvae. To achieve a more uniform temperature distribution in the pond and alleviate the problem of thermal stratification, precise control of pond temperature is essential. A recirculating aquaculture pond was taken as the test object. Single-factor experiments and orthogonal experiments were conducted to comprehensively test the aquaculture pond's water supply pipe layout, bend angle, perforation rate, and environmental conditions. Three evaluation indicators were used to analyze the temperature distribution of the aquaculture pond under various water supply pipe structures, leading to the identification of optimal structural configurations. The optimal structure I, obtained from single-factor experiments, was determined to be 2.5 m, 50 %, and 60°, while the optimal structure II, derived from orthogonal experiments, was 1.25 m, 75 %, and 30°. Both optimized structures exhibited significant temperature fluctuations in the pond during the summer season. However, Structure II demonstrated the lowest average temperature difference in the winter season, indicating its superior adaptability during winter. Moreover, Structure II could provide higher temperatures for shallow areas with depths greater than 600 mm, making it more suitable for fish larvae cultivation. Additionally, local devices effectively decreased temperature variations by 17.5 % within the pond. Furthermore, energy consumption output was evaluated for different operational conditions. The results showed that Structure II had the lowest energy consumption output during the summer season. In contrast, during the winter season, the energy consumption output increased by approximately 12 %, indicating significant energy-saving potential in aquaculture ponds during winter.

Differential warming at crown scale impacts walnut primary growth onset and secondary growth rate.

Trees are exposed to significant spatio-temporal thermal variations, which can induce intracrown discrepancies in the onset and dynamics of primary and secondary growth. In recent decades, an increase in late winter and early spring temperatures has been observed, potentially accelerating bud break, cambial activation and their potential coordination. Intracrown temperature heterogeneities could lead to asymmetric tree shapes unless there is a compensatory mechanism at the crown level. An original warming experiment was conducted on young Juglans regia trees in a greenhouse. From February to August, the average temperature difference during the day between warmed and control parts was 4°C. The warming treatment advanced the date of budbreak significantly, by up to 14 days. Warming did not alter secondary growth resumption but increased growth rates, leading to higher xylem cell production (twice as many) and to an increase in radial increment (+80% compared to control). Meristems resumptions were asynchronous without coordination in response to temperature. Buds on warmed branches began to swell two weeks prior to cambial division, which was one week earlier than on control branches. A difference in carbon and water remobilisation at the end of bud ecodormancy was noted under warming. Overall, our results argue for a lack of compensatory mechanisms at the crown scale, which may lead to significant changes in tree architecture in response to intra-crown temperature heterogeneities.

The Faustini Permanently Shadowed Region on the Moon

Faustini crater (41 km diameter) hosts a large (664 km2) permanently shadowed region (PSR) with a high potential to harbor water-ice deposits. One of the 13 candidate Artemis III landing areas contains a portion of the crater rim and proximal ejecta. The ShadowCam instrument aboard the Korea Pathfinder Lunar Orbiter provides detailed images of the PSR within Faustini. We characterize the terrain and thermal environment within the Faustini PSR from ShadowCam images, Lunar Reconnaissance Orbiter thermal measurements and laser ranging, and thermal modeling. Our mapping revealed three distinct areas of the floor of Faustini based on elevations, slopes, and surface roughness. These units broadly correlate with temperatures; thus, they may be influenced by variations in volatile sublimation. Crater retention and topographic diffusion rates appear to be asymmetric across the floor, likely due to differences in maximum and average temperatures. Several irregular depressions and a pronounced lobate-rim crater are consistent with subsurface ice. However, differences in the thicknesses of deposited materials on the floor may also explain the asymmetry. Additionally, zones of elevated surface roughness across Faustini appear to result from overprinted crater ray segments, possibly from Tycho and Jackson craters. Mass wasting deposits and pitting on opposite sides of the crater wall may have resulted from the low-angle delivery of material ejected by the Shackleton crater impact event, suggesting that the Artemis III candidate landing region named “Faustini Rim A” will contain material from Shackleton.

Temperature monitoring test and thermal analysis during construction of deep orifice of arch dam

In the low-temperature season of Southwest China, concrete of orifice is easy to crack during pouring, and the superficial heat preservation of dam is needed. In this paper, the temperature gradient monitoring test of deep orifice of Baihetan Dam is carried out to obtain measured temperature data based on the distributed optical fiber sensing technique. Based on monitoring data, a finite element model of deep orifice of pouring blocks considering thermal insulation materials is established. By comparing calculated temperature with measured temperature, accuracy of the simulation model is verified. The temperature and stress of deep orifice with or without thermal insulation measures are analyzed, considering the thermal insulation effects of different thicknesses and different types of thermal insulation materials. The results show that when the insulation measures are not covered, the average temperature difference between day and night exceeds 2 °C, and the average temperature difference between day and night is within 1 °C after coverage. Using 3 cm or 5 cm polyethylene coil at the top surface and the transverse joint surface of pouring blocks, and spraying 3 cm or 5 cm polyurethane at the upstream surface of pouring blocks for thermal insulation can effectively prevent the temperature cracks.

Relationship Between Environmental Meteorological Factors and the Incidence of Epistaxis in Different Age Groups in Yangzhou.

Objective: To investigate the relationship between environmental and meteorological factors and the incidence of epistaxis in different age groups in Yangzhou, as well as to provide a reference and theoretical basis for epistaxis prevention and treatment. Methods: The patients with epistaxis who were treated in Northern Jiangsu People's Hospital of Jiangsu Province from January 2016 to December 2020 were reviewed, and the relationship between the local environmental meteorological factors at the time of onset and the incidence of epistaxis in different age groups was analyzed, and the potential environmental meteorological risk factors of epistaxis in each age group were determined by Stepwise logistic regression. Results: From 2016 to 2020, there were 24,407 cases of epistaxis, mostly males and children. The effects of O3 concentration, average humidity, average temperature, NO2 concentration, sunshine duration, average wind speed, CO concentration, and temperature difference on the study population were statistically significant (P < .05). Analysis by age group showed that there were differences in environmental and meteorological factors related to epistaxis in different age groups. Conclusions: In Yangzhou, epistaxis is more prevalent among males and children. The environmental meteorological factors are related to the incidence of epistaxis in Yangzhou, among which the average humidity and temperature difference are negatively correlated with the incidence of epistaxis. In contrast O3 concentration, average temperature, NO2 concentration, sunshine duration, average wind speed, and CO concentration are positively correlated with epistaxis occurrence. However, the impact of these environmental and meteorological factors varies in different age groups.

Multi-source transfer learning method for enhancing the deployment of deep reinforcement learning in multi-zone building HVAC control

Deep reinforcement learning (DRL) control methods have shown great potential for optimal HVAC control, but they require significant time and data to learn effective policies. By employing transfer learning (TL) with pre-trained models, the need to learn the data from scratch is avoided, saving time and resources. However, there are two main critical issues with this approach: the inappropriate selection of the source domain resulting in worse control performance and inefficient utilization of multi-source domain control experience. To address these challenges, a multi-source transfer learning and deep reinforcement learning (MTL-DRL) integrated framework is proposed for efficient HVAC system control. In order to select appropriate source domains, the contribution of various source domains to the target task is quantified first, followed by a comprehensive evaluation of transfer performance based on average energy consumption and average temperature deviation. The well-pretrained DRL parameters from the optimal multi-source transfer set are then sequentially transferred to the target DRL controller. Results from a series of transfer experiments between buildings with different thermal zones and weather conditions indicate that the MTL-DRL framework significantly reduces the training time of HVAC control, with improvements of up to 20% compared to DRL baseline models trained from scratch. Additionally, the MTL-DRL method leads to reductions in average energy consumption ranging from 1.43% to 3.12% and average temperature deviation up to 14.32%. The impact of the source domain transfer sequence on the performance of the DRL-based control method is also discussed. Overall, the proposed framework presents a promising solution for enhancing DRL-based HVAC control methods by reducing training time and energy consumption while maintaining occupants’ comfort.

Experimental and thermodynamic modelling of hydrate dissociation conditions for CO[formula omitted] + propane mixtures

The possibility of hydrate formation poses a central issue for Carbon Capture and Storage (CCS) and Enhanced Oil Recovery with Water-Alternating-Gas (EOR/WAG) injection projects. In most of the cases, however, the available fluid for this purpose consists of a CO2-rich stream containing contaminants such as hydrocarbons and permanent gases. As a result, there is a growing interest in evaluating the effect of small impurities concentrations on the phase behaviour of such streams. This work investigates the impact of propane as a promoter in carbon dioxide hydrate formation, covering a concentration range in the feed gas phase between 10 and 69% on mole basis. The study also considers the Lw-LCO2-H region, taking into account liquid and supercritical transportation commonly encountered in CCS projects. Additionally, a procedure to estimate uncertainties in the graphical determination of the dissociation temperature and pressure is discussed. The thermodynamic modelling approach includes three different modifications of cubic equations of state (CEoS): asymmetric mixing rule, advanced Huron-Vidal mixing rule, and cubic-plus-association approach. An alternative procedure based on setting different sets of CO2 Kihara’s parameters when shifting between structures was also used. While satisfactory average temperature deviations were obtained for those equations of state, maximum deviation between calculated and experimental temperatures spanned from 0.5 to 2.5 K, depending on the thermodynamic model.