Research on Operation Optimization of Central Air Conditioning Cold Source System Based on PSO-SA Algorithm

This paper takes a data center air-conditioning cold source system as the research object. According to the historical operating data of the cold source system in the transition season, a cold source model is built on the EBSILON platform. The total energy consumption of the cold source system is the research goal. This paper establishes an overall optimization strategy based on PSO-SA. A simulation experiment was conducted on a typical day in the transition season, and the results showed that the optimization strategy can achieve 21.68% energy saving based on the original operation mode when the wet bulb temperature in the transition season is low.

Recent changes in the atmospheric circulation patterns during the dry-to-wet transition season in south tropical South America (1979-2020): Impacts on precipitation and fire season

We analyze the characteristics of atmospheric variations over tropical South America using the pattern recognition framework of weather typing or atmospheric circulation patterns (CPs). During 1979-2020, nine CPs are defined in the region, using a k-means algorithm based on daily unfiltered 850 hPa winds over 0035°N-30°S, 90°W-30°W. CPs are primarily interpreted as stages of the annual cycle of the low-level circulation. We identified three “winter” CPs (CP7, CP8 and CP9), three “summer” CPs (CP3, CP4 and CP5) and three “transitional” CPs (CP1, CP2 and CP6). Significant long-term changes are detected during the dry-to-wet transition season (July-October) over south tropical South America (STSA). One of the wintertime patterns (CP9) increases from 20% in the 1980s to 35% in the last decade while the “transitional” CP2 decreases from 13% to 7%. CP9 is characterized by enhancement of the South American Low-Level Jet and increasing atmospheric subsidence over STSA. CP2 is characterized by southerly cold-air incursions and anomalous convective activity over STSA. The years characterized by high (low) frequency of CP9 (CP2) during the dry-to-wet transition season are associated with a delayed South American Monsoon onset and anomalous dry conditions over STSA. Consistently, a higher frequency of CP9 intensifies the fire season over STSA (1999-2020). Over the Brazilian states of Maranhão, Tocantins, Goiás and São Paulo, the seasonal frequency of CP9 explains around 35%-44% of the interannual variations of fire counts.

Performance of the wall implanted with heat pipes on indoor thermal environment

In order to improve the utilization of solar energy absorbed by the building wall, a passive building technology, that is the wall implanted with heat pipes, had been proposed. In the present study, two rooms with the same environmental conditions were built, and the one with a wall implanted with heat pipes installed was taken as a test room and the other as a control. The dynamic heat transfer characteristics of a wall implanted with heat pipes in transition season and its impact on indoor thermal environment were studied experimentally. The results showed that the application of a wall implanted with heat pipes could increase the indoor temperature by about 0.5 °C and would assert a positive influence on the vertical distribution of temperature. The PMV-PPD values of two rooms were calculated to compare and evaluate the improvement in thermal comfort, and the results indicated that the wall implanted with heat pipes reduced the dissatisfaction rate by more than one seventh in comparison to the indoor thermal environment. Also, it enhanced the PMV value. Therefore, wall implanted with heat pipes as an auxiliary heat source has a good effect on the indoor thermal environment during the transition season.

Total OH reactivity over the Amazon rainforest: variability with temperature, wind, rain, altitude, time of day, season, and an overall budget closure

The tropical forests are Earth's largest source of biogenic volatile organic compounds (BVOCs) and thus also the largest atmospheric sink region for the hydroxyl radical (OH). However, the OH sink above tropical forests is poorly understood, as past studies have revealed large unattributed fractions of total OH reactivity. We present the first total OH reactivity and volatile organic compound (VOC) measurements made at the Amazon Tall Tower Observatory (ATTO) at 80, 150, and 320 m above ground level, covering two dry seasons, one wet season, and one transition season in 2018–2019. By considering a wide range of previously unaccounted for VOCs, which we identified by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS), the unattributed fraction was with an overall average of 19 % within the measurement uncertainty of ∼ 35 %. In terms of seasonal average OH reactivity, isoprene accounted for 23 %–43 % of the total and oxygenated VOCs (OVOCs) for 22 %–40 %, while monoterpenes, sesquiterpenes, and green leaf volatiles combined were responsible for 9 %–14 %. These findings show that OVOCs were until now an underestimated contributor to the OH sink above the Amazon forest. By day, total OH reactivity decreased towards higher altitudes with strongest vertical gradients observed around noon during the dry season (−0.026 s−1 m−1), while the gradient was inverted at night. Seasonal differences in total OH reactivity were observed, with the lowest daytime average and standard deviation of 19.9 ± 6.2 s−1 during a wet–dry transition season with frequent precipitation; 23.7 ± 6.5 s−1 during the wet season; and the highest average OH reactivities during two dry-season observation periods with 28.1 ± 7.9 s−1 and 29.1 ± 10.8 s−1, respectively. The effects of different environmental parameters on the OH sink were investigated, and quantified, where possible. Precipitation caused short-term spikes in total OH reactivity, which were followed by below-normal OH reactivity for several hours. Biomass burning increased total OH reactivity by 2.7 to 9.5 s−1. We present a temperature-dependent parameterization of OH reactivity that could be applied in future models of the OH sink to further reduce our knowledge gaps in tropical-forest OH chemistry.

Effect of Air Pollution on Metabolism-Associated Fatty Liver Disease: A Hospital-Based Study

Background Many studies have shown that the fine particulate matter in air is related to the incidence rate of chronic diseases. However, research on air pollution and metabolism-associated fatty liver disease (MAFLD) is limited. The purpose of this study was to explore the relationship between the incidence rate of MAFLD and air pollutants.Methods using a quasi-Poisson regression generalized additive model. Stratified analyses by season and age were also performed. Results A 10 µg/m3 increase of PM10, PM2.5, and NO2 concentrations corresponded to 0.82 (95%Cl: 0.49, 1.15), 0.57(95%Cl: 0.18,0.98), and 0.86(95%Cl: 0.59,1.13) elevation in MAFLD. In terms of season, the impact estimates of NO2 and PM2.5 were 3.55 (95% CI, 1.23-5.87) and 1.12 (95% CI, 0.78-1.46) in the hot season and transition season, respectively. Compared with warm season, the impact estimates of PM10 were more significant in the cool season: 2.88 (95% CI, 0.66-5.10). NO2 has the highest effect in the transition season, while PM10 has the highest effect in the cool and hot seasons. In the two age groups with 45 years as the dividing line, PM2.5 has the highest impact estimate: 2.69 (95% CI, 0.77-5.61) and 2.88 (95% CI, 0.37-6.40). The impact values of PM2.5 in male and Female were 3.60 (95% CI, 0.63-6.57) and 1.65 (95% CI, 1.05-2.25), respectively. The most important link is in different lag models, there is a significant correlation.Conclusion: This study shows that the air pollutants are related to the incidence rate of MAFLD. The effects of different air pollutants on MAFLD incidence rate were different in different seasons, ages, and gender. It is found that air pollution has a lag effect on MAFLD.