Seasonal Transition Research Articles

Thermal performance of south-facing envelopes in solar enrichment zone of Qinghai–Tibet plateau: Field measurements of multiple dwellings in winter and transition seasons

Thermal performance of south-facing envelopes in solar enrichment zone of Qinghai–Tibet plateau: Field measurements of multiple dwellings in winter and transition seasons

Total replacing soybean meal with extruded urea in supplements on the intake, ruminal, and metabolic parameters of beef cattle during the rainy and wet-dry transition seasons.

The objective was to evaluate supplement intake, ruminal parameters, and blood parameters of beef cattle supplemented with different protein sources (soybean meal or extruded urea- starea) during the rainy and wet-dry transition seasons. Four ruminally cannulae crossbred cattle were distributed in a completely randomized design in four paddocks Brachiaria brizantha cv. Marandu, with two paddocks per treatment, with three 30-d periods each season (rainy and wet-dry). The treatments were: (1) Concentrated supplement containing extruded urea (Starea) and (2) Concentrated supplement containing soybean meal. During the rainy season, the animals received 0.45% of BW in supplement per day. In the wet-dry transition period, the animals received 0.70% of BW of supplement per day. Animals fed soybean meal had greater supplement intake. The treatment with extruded urea supplement had rumen pH higher in the wet period. There was an interaction of treatment × hour for ammonia N for both seasons, where during the wet season, soybean meal at 6h sampling had greater ammonia N compared with the other treatment, and during the wet-dry transition, soybean meal at 6h and extruded urea supplement at 0h had greater ammonia concentration. The total VFA was not affected by treatment independent of the season. The acetate: propionate ratio was lower with soybean meal supplement during the wet season. The total replacement is not recommended of true protein by non-protein nitrogen sources in supplements for beef cattle kept in Marandu-grass pastures during the rainy and wet-dry transition seasons.

Research on the Green Construction Technology of Stilt Houses Based on the Climate Adaptation of Transitional Seasons

Stilt houses are extremely adaptable to terrain and climate. However, current indoor thermal environment research in transitional seasons is not prominent. Therefore, in this research, a typical stilt house in southwest China was chosen as the research object and analyzed by combining Climate Consultant climate analysis software and field measurement data. The results showed that the indoor thermal stability of a stilt house was excellent during the transition season, and the attic had the most obvious climate regulation, with the maximum temperature difference between indoors and outdoors being 9 °C when the outdoor temperature was the highest. The difference between the mean radiant temperature and the average air temperature was only 0.04 °C, and the radiant effect of the enclosure on the interior was small. The indoor relative humidity ranged from 63.2% to 85.1%, showing high relative humidity, but the fluctuation was relatively stable. Stilt floors did not play a significant role in climate regulation during the transition season, and the semi-open space structure was more prone to moisture accumulation when the outdoor humidity was high. Regarding practical application, the climate adaptation strategies of shading, cooling, and dehumidification were applied in the transition season, but dehumidification was ineffective.

Energy-Efficient Architectural Design of a Banquet Hall with Integrated Tunnel Ventilation: Monitoring Performance During the Transitional Season in China

The construction industry, a significant contributor to global energy consumption and greenhouse gas emissions, is under considerable pressure to adopt transformative approaches. Public buildings, which account for a substantial portion of total energy usage, must balance high standards of thermal comfort with ventilation efficiency. In China, many public buildings are part of urban landscapes, where façade designs often limit natural ventilation. Consequently, technologies like earth-to-air heat exchangers and wind towers are increasingly essential for enhancing natural ventilation. However, research on the efficacy of these systems remains sparse. This study examines the transitional seasonal environment by evaluating the thermal-humidity index of a banquet hall equipped with an earth-to-air heat exchanger system. Using DeST software [DeST 2.0], the study simulates indoor natural ventilation, calculates ventilation rates, and assesses residual heat removal efficiency. The system’s performance is also modeled under various thermal design zones. Results demonstrate that under natural ventilation, the system can achieve a residual heat removal efficiency of up to 490%. Simulations across different climate zones indicate that the system performs best in regions with extreme temperature fluctuations, particularly those with hot summers and warm winters. In these areas, the system reduces the annual temperature difference by up to 56.7%, significantly improving thermal comfort and reducing dependency on air conditioning. In contrast, performance in milder regions like Kunming achieves only a 37.5% reduction in temperature difference. Overall, this study provides valuable insights into energy-efficient design strategies and thermal optimization for banquet halls, with significant potential for energy savings and enhanced occupant comfort.

Seasonal variation of coastal currents and residual currents in the CAT BA – HA long coastal area (VIET NAM): Results of coherens model

The COHERENS model is used to investigate the temporal and spatial variation of the coastal currents in 2021 at the Cat Ba - Ha Long, northern Vietnam. The findings indicate that tidal oscillation has a notable impact on the current fields in short-term variations (hours to days). Meanwhile, the wind field and river discharge are the decisive factors affecting the seasonal variation of the current fields in Cat Ba - Ha Long coastal area. Furthermore, the characteristics of residual currents are significantly affected by river discharges and wind patterns, which vary across different months and seasons. During the southwest monsoon season (May to August), the residual currents have a prevailing direction towards the sea, from the west and south-southwest towards the east and north-northeast, reaching maximum speeds of approximately 0.1–0.15 m/s. Conversely, in the transitional and northeast monsoon seasons, the directions of residual currents are from the east-northeast to the west-southwest, with peak speed up to 0.2–0.25 m/s. Notably, the residual currents in the bottom and surface layers in the eastern-southwestern area of Cat Ba Island and the north of Ha Long Bay are in opposite directions.

Field Investigation on the Thermal Environment and Comfort of People Exercising in a Fitness Center

A favorable thermal environment in fitness centers is important to attract more members and is beneficial to the health of exercising people. The purpose of this study was to research the actual thermal environment of a typical fitness center in different seasons and the thermal requirement of exercising people. A field investigation covering winter, spring, and summer was conducted. The environmental parameters were measured. Subjective questionnaires involving individual information, clothing insulation, thermal sensation, etc., were collected. Participants’ heart rates were tested to estimate their metabolic rate (MR). A total of 740 valid questionnaires were collected. The results showed that a scissors gap existed between the predictive mean vote (PMV) and the thermal sensation vote (TSV) for the exercising people. For the higher MR group, there was a separation between the TSV and thermal preference vote, e.g., most participants would not prefer to cooler or warmer thermal environment when they felt hot or cold. The CO2 concentration changed greatly among seasons and the distribution in the fitness center was not uniform. With mechanical ventilation, the CO2 concentration in summer was the lowest. In other seasons it became much higher due to limited natural ventilation. However, subjective response to indoor air quality showed no significant difference among seasons. The participants felt more satisfied to the overall thermal environment in the transition season. The results can be referenced in the thermal environment management in fitness centers during seasonal changes.

Influence of the Thickness of Freezing of the Soil Surface and Snow Cover on Methane Emissions during Freezing of Seasonal Permafrost

Methane, a type of greenhouse gas, poses considerable concern for humans. This study uses field experiments and satellite measurements to explore methane emission mechanisms during the freezing of seasonal permafrost and the contributing factors. In the transitional seasons of autumn and winter, as soil begins to freeze, methane emissions surge dramatically in a brief period. During this phase, the emissions peak, enabling the soil to accumulate over 9000 mg/m3 of methane rapidly. Snow cover also plays a crucial role in mitigating methane emissions. The porous nature of a sufficiently thick snow cover aids in temporarily trapping methane through a stratified blocking process, effectively matching the inhibitory capability of unfrozen soil. In comparison to unfrozen soil (54–237 mg/m3), snow cover can suppress methane emissions up to 20 times more, reducing emissions by as much as 3399 mg/m3.

The Characteristics of the Chemical Composition of PM2.5 during a Severe Haze Episode in Suzhou, China

During the past decade, the air quality has been greatly improved in China since the implementation of the “Clean Air Act”. However, haze events are still being reported in some regions of China, and the pollution mechanism remains unclear. In this study, we investigate the chemical characteristics of the pollution mechanism of the PM2.5 composition in Suzhou from October 18 to December 15, 2020. A notable declining trend in temperature was observed from 18 to 27 November, which indicates the seasonal transition from fall to the winter season. Four representative periods were identified based on meteorological parameters and the PM2.5 mass concentrations. The heavy pollution period had the typical characteristics of a relatively low temperature, a high relative humidity, and mass loadings of atmospheric pollutants; nitrate was the dominant contributor to the haze pollution during this period. The nitrate formation mechanism was driven by the planetary boundary layer dynamics. The potential source contribution function model (PSCF) showed that the major PM2.5 composition originated from the northwest direction of the sampling site. The aerosol liquid water content presented increasing trends with an increasing relative humidity. The pH was the highest during the heavy pollution period, which was influenced by the aerosol liquid water content and the mass loadings of NO3−, SO42−, NH4+, and Cl−. The comprehensive analysis in this paper could improve our understanding of the nitrate pollution mechanism and environmental effects in this region.

Analysis of Ozone Pollution and Precursor Control Strategies in the Pearl River Delta During Summer and Autumn Transition Season

To analyze the causes of ozone pollution in the Pearl River Delta （PRD） Region during the summer and autumn transition seasons, a case study was carried out in Guangzhou, which is located in the center of the PRD Region, to analyze the ozone photochemical production and destruction pathways as well as emission reduction scenarios using a box model based on comprehensive observation. The results showed that the stagnant meteorological conditions and high temperature during the observation period were suitable for the photochemical production of ozone, which led to widespread and prolonged ozone pollution. Aromatic hydrocarbons （AHs） contributed the most to the ozone formation potential （OFP）, and m/p-xylene, toluene, and o-xylene were the major three VOC species contributing to the OFP. Box model analysis revealed that the averaged net O3 production rate during the polluted period was 23.2×10-9 h-1 and the peak reached 39.2×10-9 h-1. The HO2·+NO and NO2+·OH reaction pathways contributed the most to the local photochemical ozone production （51.2%） and destruction （47.0%）, respectively. Observed ozone concentration was primarily controlled by both the local photochemical O3 production and the export-dominated transport. The RIR and EKMA analyses showed that O3 formation in Guangzhou during the summer-autumn transition seasons was mainly a VOC-limited regime and AHs showed the greatest sensitivity to O3 production. Toluene, m/p-xylene, o-xylene, n-butane, and propylene were the five key components affecting O3 generation. The analysis of reduction scenarios showed that reducing anthropogenic VOC emissions was the most favorable way to reduce O3 concentrations； however, if NOx emission was controlled after reducing VOCs, the O3 concentration would rebound in a short time. Our results suggested that the synergistic reduction of VOCs and NOx while mainly focusing on VOCs alleviation should be implemented to continuously reduce ozone concentrations in the future.

Investigation of a novel combined ab- and ad- sorption based thermal energy storage and upgrade system

This paper presents a novel sorption-based cycle combining energy storage with energy upgrade to store low-grade heat for long periods and transform it on demand to usable energy at elevated temperatures. The system consists of an ammonia-water absorption system coupled to a resorption thermal transformer using manganese chloride and calcium chloride as the working pair with an ammonia absorbate. The absorption and adsorption systems are charged by separating the constituent sorbent-sorbate pairs, and they remain separated during the transition season. The discharge consists of a two-stage sorption process between the two systems. This work presents a transient thermodynamic model and analysis of the two-stage sorption system. For a typical solar thermal energy input of 106 °C during charging, and ambient temperatures of 5 °C and 25 °C in the winter and summer, respectively, the system is capable of discharging at an average elevated temperature of 62 °C with an energy storage efficiency of 27 %. This system is capable of simultaneously producing heat at a lower temperature by varying the mass flow rate through the high-temperature salt. The energy storage density of the combined system under different conditions is between 71 and 185 kJ kg−1. In comparison with other conventional single-stage thermal energy storage systems, this combination of absorption and adsorption-based storage provides a higher coefficient of performance for a comparable temperature output.

Assessment of water quality and emerging pollutants in two fish species from the mallorquin swamp in the Colombian Caribbean

The Mallorquín Swamp, an important ecosystem in Atlántico, Colombian Caribbean, underwent environmental monitoring at eight points during rainy, transition, and dry seasons. This was to assess water quality, seasonal variation, and the bioaccumulation of metals, emerging pollutants, and organic compounds in the fish Ariopsis canteri and Mugil incilis. Water parameters were analyzed using descriptive statistics and multifactorial ANOVA with the Tukey HSD test for seasonal differences. Normality and variance of the fish results were verified, and differences between groups were evaluated using ANOVA or Kruskal-Walli's method when data transformation failed. Spearman correlation was used to relate the results. Water sampling revealed variations in temperature, dissolved oxygen, salinity, and nutrient levels. Significant differences in alkalinity and hardness were observed across seasons and sample points. The most probable number (MPN) levels of Total coliform and E. coli peaked near areas with domestic wastewater inputs, reaching 5.4x106 and 4.0x106 MPN, respectively, indicating potential microbiological contamination of water. Fish samples revealed high concentrations of persistent substances such as methylmercury, polycyclic aromatic hydrocarbons (PAHs), and emerging pollutants. Heavy metal analysis showed elevated iron levels (5.28 ± 0.657 mg/L), while emerging pollutants, including ibuprofen (218 μg/L) and naproxen (343.89 μg/L), exhibited high concentrations near human settlements. Ariopsis canteri showed higher bioconcentration tendencies for methylmercury (238.5 ± 100 μg/kg), and acenaphthene (7782 ± 4123.8 μg/kg), possibly influenced by its feeding habits and habitat preferences. In contrast, Mugil incilis exhibited higher bioaccumulation trends of PAH (2376.23 ± 599.63 μg/kg acenaphthene) and emerging pollutants like galaxolide (139.49 ± 34.98 μg/kg), possibly due to its mobility and exposure to various contaminants in their environment. These findings emphasize the need to monitor and manage aquatic ecosystems' health to mitigate anthropogenic influences on water quality and biodiversity. This research serves as a reference for global conservation efforts, emphasizing the need for comprehensive monitoring and regulatory frameworks to protect aquatic environments and ensure their sustainability for future generations.

Research on an adaptive prediction method for restaurant air quality based on occupancy detection

This study evaluates the impact of personnel on air quality in air-conditioned restaurant environments during winter, summer, and transitional seasons, characterized by the peculiarities of personnel movement, high concentration of personnel in a short period of time, poor ventilation and high personnel density, leading to the accumulation of pollutants that can severely damage personnel health. This study examines carbon dioxide (CO2) and particulate matter (PM) concentrations and proposes an online adaptive model for their prediction.Environmental influence factors are analyzed through correlations of measured data, and appropriate input parameters (time-lagged cumulative number of people) are selected. The Auto-Regressive with Exogenous Inputs (ARX) model is used to predict the change of air quality with the movement and number of people, compared with classical models (LR, DT, SVM, ENS, GPR, NN, VARX). Results show that the ARX model performs excellently in predicting restaurant environments; the effect of different environmental factors on the predictive effectiveness of the model was also explored. When combined with real-time sensor data and AIC-based adaptive optimization, the prediction accuracy is further improved by more than 25 %. The R2 of the ARX model is 0.9549, the MAE is 0.8352 μg/m3 and the MAPE is 3.17 %. The adaptively optimized model can be adapted to different environments, overcoming the problem of poor adaptability of such models. Our results enable effective environmental control strategies in public spaces, contributing to Sustainable Development Goal (SDG) 3: Good Health and Well-being by reducing health risks associated with indoor air pollution.

Seasonal wet–dry transition and denitrifying communities contributed to nitrous oxide emissions in the water-level fluctuating zone of the largest freshwater lake in China

The water-level fluctuating zone (WLFZ) is the alternating dry/wet zone in freshwater lakes, and plays a crucial role in nitrogen (N) biogeochemical cycling and nitrous oxide (N2O) emissions. However, N2O emission fluxes, the underlying microbial mechanisms, and their feedbacks to global warming in the extensive WLFZ of the freshwater lakes with dramatic water-level variations remain unclear. Here, we sampled through both wet and dry seasons and compared the N removal rates, N2O emission fluxes, composition and co-occurrence network properties of the denitrifying microbial communities of the WLFZ, continuously flooded, and non-flooded zones covered with the dominant plant (Carex. cinerascens) in Poyang Lake, the largest freshwater lake of China. We observed higher potential denitrification (1.129–5.657 nmol N g-1h−1) and anammox (0.047–0.756 nmol N g-1h−1) rates in the WLFZ for both wet and dry seasons than those in the other two zones. A large seasonal N2O sink-source transition (−2.297 and 0.297 μg m-2h−1 for wet and dry season, respectively) was observed in WLFZ. Moreover, the composition of nirK and nirS communities significantly varied in WLFZ between the wet and dry seasons. Especially, several keystone taxa (e.g., Mesorhizobium and Rhodanobacter) were enriched in the WLFZ and were responsible for denitrification and N2O emissions under drought stress in the dry season. Variations in denitrification rates and N2O fluxes were driven by pH, C and N substrates, as well as the co-occurrence network properties, including natural connectivity and small-world coefficients of the nirK and nirS communities. Our results suggested that WLFZ in freshwater lakes under future climate change scenarios would be a substantial N2O source and aggravate climate, which would result in the positive feedback.

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.

Implications for extreme midlatitude weather events of secondary flow associated with polar jets

AbstractIn the Earth's general circulation, polar jets act as baroclinic pumps of angular momentum and heat. Reanalysis datasets indicate that shear changes near jets induce upward displacements of the jet cores, suggesting a weakening thermodynamic pumping over the last 50 years. From secondary flow theory, a well‐established principle in fluid dynamics, an increased frequency of heatwaves and persistent winter storms is expected. The ageostrophic wind shear between 700 and 50 hPa indicates the strength of this secondary circulation. The weakening tendency during the reanalysis period also exists in multimodel simulations under the RCP8.5 emissions scenario for the 21st century. The reduction between the periods 2005–2025 and 2081–2100 reaches 18%, 5.3% and 19%, respectively, for the North America, Mid‐Europe and East Asia sectors of the Northern Hemisphere polar jet. Within this background, cold‐surge events are the result of synergic co‐working of several factors. The occurrence trend for transitional season winter extreme events also is examined. The winter extremes seemingly have larger temperature drops. However, in a warming climate, they emerge more rapidly from extreme cold states. The storm tracks, especially over North America, have equatorward extensions, indicating that winter storms can reach lower latitudes. Due to the temperature‐dependence of air viscosity, secondary flows decrease more slowly than the main zonal flow. This imposes an important adjustment to the traditional polar amplification effects on midlatitude winter extremes. During a warmer winter (the primary manifestation of a warmer climate), spatially uniform positive trends in cold extreme events are not expected. There are, however, regions experiencing more winter extremes. These regions show consistent patterns in both the reanalysis period and the remainder of the 21st century.

Warm, moderate, or cool-liker? A benchmarking framework to characterize occupant overall thermal preferences based on large-scale thermostat data

Humans could exhibit distinct overall thermal preferences when exposed to identical indoor thermal environments, leading to preference groups such as "warm-likers" or "cool-likers", who consistently prefer warmer or cooler conditions than the average population, respectively. Currently, most thermal comfort modelling studies focus on capturing the instantaneous comfort states/preferences of occupants, while overlooking their overall thermal preferences. This paper proposes a benchmarking framework to identify and characterize overall thermal preferences based on the relationship between preferred setpoints and outdoor air temperatures, derived from the ECOBEE Donate Your Data program. Using descriptive statistics, we establish three temporally consistent overall preference groups, including warm-liker, moderate and cool-liker, along with a temporally chaotic preference group termed random. Our results demonstrate that warm-likers prefer temperature setpoints above 21.5 °C on heating days and 24–25 °C on cooling days, while cool-likers prefer setpoints below 19.6 °C on heating days and 22 °C on cooling days, indicating a significant impact of the seasonal transitions. We observed that around 50 % of users exhibit secondary overall preferences, implying that overall thermal preference could change over time. On average, overall thermal preference can be established in 10–16 setpoint adjustments. The study reveals varied responses to outdoor temperature changes among users: many maintain constant indoor temperature preferences, while a significant number adjust their indoor temperatures upwards by 0.1 °C–0.4 °C for each 1 °C rise in outdoor temperature. A smaller group prefers cooler indoor temperatures as it gets warmer outside, showing a unique negative adjustment trend of −0.1. We also found that climate interacts with the overall preference group, with warmer climates having more warm-likers and vice versa.

Seasonal effects on blue swimming crab catch per unit effort (CPUE) in Tiworo Strait, Southeast Sulawesi, Indonesia

Abstract Blue swimming crab (BSC) resources are fisheries commodities that have important economic value, so their utilization needs to be carried out sustainably. Understanding crab fishing season patterns is very important in efforts to improve the efficiency and effectiveness of crab fishing industry. This study aimed to analyze the abundance and catch per unit effort (CPUE) of blue swimming crab based on season in the the Tiworo Strait, Southeast Sulawesi, Indonesia. BSC sampling was conducted monthly from October 2022 to March 2023 (west season) and April to September 2023 (east season). The results showed that the maximum catch occurred during the east to west transition season, amounting to 1,668.50 kg, while the lowest catch was 376.70 kg with a total of 1,032 trips. The maximum catch in the west season was 1,402.10 kg, while the lowest was 666.50 kg with a total of 1,265 trips. The highest CPUE value was observed in July at 7.92 kg/trip, while the lowest CPUE occurred in April at 2.18 kg/trip. Differences in crab catches and number of trips in each season may be influenced by environmental conditions that occur in that season as well the location of the fishing ground.

The Seasonal Variations of the Thermocline in the Banda Sea and its Water Mass Characteristics

This research was conducted to examine the seasonal variations in the Banda Sea's thermocline layer and its water mass characteristics. The research was conducted by analyzing Argo Float data. The data consists of six observation stations in West Season and Transitional Season II, and four stations in Transition Season I and East Season The thermocline layer thickness was identified based on the depth where the temperature decreased ≥ 0.05oC/m. The thermocline layer's distribution of depth and thickness and the distribution of temperature and salinity seasonally in the thermocline layer were analyzed with Microsoft Excel 2010. The analysis results showed that East Season and Transition Season II have a shallower upper boundary depth of the thermocline layer, a deeper lower boundary of the thermocline layer, and the thermocline layer is thicker when compared to the West Season and Transition Season I. The average temperature distribution is higher and the average salinity is lower in the West Season and Transition Season I. The mean rate of change in salinity and temperature in the thermocline layer seasonally ranged from 0.002-0.004 PSU/m and 0.06-0.08oC/m. The thermocline layer's stratification is stronger in the West Season and Transition Season I.

Variability of biophysical parameters during La Niña condition in the Eastern Region of the Indian Ocean

The La Niña event not only affected global ocean dynamics but also marine productivity. Due to its importance to the life of organisms and ecosystems, the biophysical aspects should be analyzed. One of the important regions in the eastern region of the Indian Ocean is located in the upwelling system and central marine biodiversity. The study aims to investigate several parameters, including SSTs, dissolved oxygen levels, nitrate distribution, and Chlor-a concentration, which are combined with ocean currents. These parameters are then analyzed in the period 2020 to 2022, which is La Niña condition. Based on the results, significant changes occur in SST during the first transitional season of 2022, where the increase reaches 1–4 °C. There was an increase in La Niña during this period. For marine productivity parameters, the recorded DO is in the range of 197 to 218 mmol/m3, nitrate with a value range of 0 to 0,02 mmol/m3, nanoplankton with a value range of 0 to 0.03 mg/m3, and Chlor-a with a value range of 0 to 4 mg/m3. We also found that changes in ENSO events affect the productivity of the Eastern Region of the Indian Ocean, especially in the Chlor-a parameter, where the occurrence of La Niña extreme is the most important parameter.

Optimizing efficiency of proton exchange membrane electrolyzer system based on multiphysics model and differential evolution strategy

This work focuses on a comprehensive performance enhancement considering hydrogen production, energy consumption of balance of plant (BOP), and thermal safety by optimizing the inlet water temperature and flow velocity. First, a multiphysics model is introduced to show that the inlet water temperature and flow velocity can affect the current density as well as the hydrogen production. An overall efficiency is defined to balance the hydrogen production and the energy consumption of BOP. After that, a surrogate model is established based on artificial neural network to replace the multiphysics model because of its huge computational effort. For the thermal safety and performance enhancement, an optimization problem with the maximum membrane temperature as a constraint and the overall efficiency as an objective function is proposed. The differential evolution (DE) strategy with the feasibility rule (FR) is adopted to solve this optimization problem. Finally, the DE-FR-based optimization algorithm is applied to three typical days in Chengdu of China representing summer, winter, and transitional seasons, respectively. Compared to the invariant inlet water flow velocity and temperature, the optimal and time-varying parameters improve their efficiency by relative percentages of 2.68%, 3.79%, and 3.29% for the three typical days, respectively.