Minimum Temperature Research Articles

Study on Betaine and Growth Characteristics of Lycium chinense Mill. in Different Cultivation Environments in South Korea.

Betaine is a useful compound that has various activities and is the marker compound of Lycium chinense fruit in Korean Pharmacopoeia. we seek to support the stable production of medicinal goji berries, which have significant potential in the pharmaceutical industry due to their high values, and to provide foundational data for consistent quality control. This study's purpose was to examine the correlation among betaine content, environmental variables, and the growth characteristics of L. chinense fruits. The fruits were collected from 25 cultivation sites across South Korea. We investigated five growth characteristics and betaine contents in L. chinense fruits and twelve soil physicochemical properties, and seven meteorological data at cultivation sites. The fruit's growth characteristics included a length of 15.62-26.49 mm, a width of 7.09-11.38 mm, a fresh weight of 0.73-1.62 g, and a sugar content of 11.10-19.62 Brix°. Its betaine content ranged from 0.54% to 0.97%. The betaine content was positively correlated with electrical conductivity (0.327 **), exchangeable potassium (0.314 **), and sodium (0.259 *) and negatively correlated with annual average minimum temperature (-0.256 *) and annual average temperature (-0.242 *). Also, betaine showed a positive correlation with the length of the fruit (0.294 *) and the fresh weight of the fruit (0.238 *). These results can be used to find the best cultivation method and to manage quality control for the highly economical L. chinense fruit.

Impact of Greenhouse Size on the Growth and Yield of Warm Season Vegetables During the Summer Ladakh, India

No guidelines exist on the size of naturally ventilated passive solar greenhouses in mountain regions, especially above 10,000 feet above mean sea level (AMSL). Two different-sized greenhouses in Ladakh were studied, and it was figured out that a large greenhouse (60 feet in length, 24 feet in width, 9 feet 6 inches in height) was better than a small greenhouse (32 feet in length, 18 feet width, 9 feet 6 inches height) for growing cucumber, capsicum, and brinjal in summer. The mean maximum and minimum temperature of the large greenhouse was 3.6±4.1°C and 1.3±1.6°C warmer in comparison to the small greenhouse. Cucumber was harvested seven days earlier, while capsicum and brinjal were harvested 17 days earlier in the large greenhouse. The marketable fruit numbers in cucumber, capsicum, and brinjal were 50.5 %, 46.9 %, and 67.7 % higher in the large greenhouse. The average marketable fruit yield of cucumber, capsicum and brinjal was 112 %, 55 % and 71.4 % higher in the large greenhouse than in the small greenhouse. Hence, large greenhouses are suggested for high-altitude Ladakh regions for growing warm-season crops in summer.

Assessment of the thermodynamic feasibility of a new configuration for enhancing the performance of an Allam cycle using the reheating method

This study presents a new arrangement of the reheating Allam cycle and investigates the efficacies of key parameters on the net specific work and thermal and exergy efficiencies of the proposed cycle. The performance of the optimized reheating Allam cycle is compared to several oxy-combustion cycles, and the results show that the inlet temperature of the low-pressure turbine, followed by the inlet temperature of the high-pressure turbine, has a remarkable efficacy on the thermodynamic performance of the reheating Allam cycle. In contrast, the minimum temperature of the proposed system has the lowest impact on its performance. The study identifies that the low-pressure combustion chamber accounts for the biggest share of the exergy destruction of the proposed reheating Allam cycle, representing 20.68 % of the overall input exergy. The net specific work of the optimized reheating Allam cycle is evaluated at up to 596.3 kJ/kg, with thermal and exergy efficiencies obtained at 52.37 % and 46.70 %, respectively. These values indicate significant performance improvements compared to other oxy-combustion cycles. This study supplies valuable perceptions into the design of the reheating Allam cycle and suggests that this configuration has the potential to be a promising alternative to other cycles in terms of its high efficiency and low environmental impact.

Long-Term Wind and Air Temperature Patterns in the Southeastern Region of Iran through Model Simulation and Ground Observations

Dust storms are one of the important natural hazards that affect the lives of inhabitants all around the world, especially in North Africa and the Middle East. In this study, wind speed, wind direction, and air temperature patterns are investigated in one of the dustiest cities in Sistan Basin, Zahedan City, located in southeast Iran, over a 17-year period (2004–2020) using a WRF model and ground observation data. The city is located near a dust source and is mostly affected by local dust storms. The World Meteorology Organization (WMO) dust-related codes show that the city was affected by local dust, with 52 percent of the total dust events occurring during the period (2004–2021). The city’s weather station reported that 17.5% and 43% were the minimum and maximum dusty days, respectively, during 2004–2021. The summer and July were considered the dustiest season and month in the city. Since air temperature, wind speed, and wind direction are important factors in dust rising and propagation, these meteorological factors were simulated using the Weather Research and Forecasting (WRF) model for the Zahedan weather station. The WRF model’s output was found to be highly correlated with the station data; however, the WRF simulation mostly overestimated when compared with station data during the study period (2004–2020). The model had a reasonable performance in wind class frequency distribution at the station, demonstrating that 42.6% of the wind was between 0.5 and 2, which is in good agreement with the station data (42% in the range of 0.5–2). So, the WRF model effectively simulated the wind class frequency distribution and the wind direction at Zahedan station, despite overestimating the wind speed as well as minimum, maximum, and average air temperatures during the 17-year period.

Deep learning hybrid models with multivariate variational mode decomposition for estimating daily solar radiation

Solar energy is one of the renewable and clean energy sources. Accurate solar radiation (SR) estimates are therefore needed in solar energy applications. Firstly, two deep learning models, including gated recurrent unit (GRU) and long short-term memory (LSTM), were developed in this study. Next, a data pre-processing technique named multivariate variational mode decomposition (MVMD) was used to construct the MVMD-GRU and MVMD-LSTM hybrid models. To better test the performance of proposed simple and hybrid models, four stations located in the Illinois State of the USA (i.e., Dixon Springs, Fairfield, Rend Lake, and Carbondale) were considered as the study sites. Whole the simple and hybrid models were established under two different strategies, i.e., local and external. In the local strategy, SR of each location was estimated using the minimum and maximum air temperatures from the same station. While, minimum and maximum air temperatures as well as SR data from the nearby station were utilized in external strategy to estimate SR time series of any target site. Root mean square error (RMSE), mean absolute error (MAE), and coefficient of determination (R2) metrics were used when evaluating the models performances. The overall results revealed that the proposed MVMD-GRU and MVMD-LSTM hybrid models illustrated better SR estimates compared to the simple GRU and LSTM in both the local and external strategies. The values of error metrics obtained for the superior hybrid models (i.e., MVMD-LSTM) during the testing period were as: RMSE = 2.532 MJ/m2.day, MAE = 1.921 MJ/m2.day, R2 = 0.916 at Dixon Springs; RMSE = 2.476 MJ/m2.day, MAE = 1.878 MJ/m2.day, R2 = 0.921 at Fairfield; RMSE = 2.359 MJ/m2.day, MAE = 1.780 MJ/m2.day, R2 = 0.924 at Rend Lake; RMSE = 2.576 MJ/m2.day, MAE = 1.941 MJ/m2.day, R2 = 0.914 at Carbondale. Therefore, the coupled models proposed in this study can be possibly recommended as suitable alternatives to the simple deep learning models with a reliable precision in estimating SR time series.

Computational study of pulse current and thermal stress on thermoelectric cooler

The thermal performance of a Peltier thermoelectric cooler (TEC) can be enhanced by multi-staging, modifying the geometry of the thermoelement, and using new material with improved thermoelectric properties. This study utilizes COMSOL multiphysics to simulate thermomechanical analyses of various geometries of thermoelectric coolers under pulse current conditions. This investigation explores the influence of pulse current parameters, such as pulse width, pulse ratio, and hot-side convective heat transfer coefficient, on a thermoelectric cooler with different leg geometries. Additionally, the impact of the TEC cold-side temperature, hot-side temperature, and thermal stress on both sides is discussed. The results indicate that TEC leg shapes, such as pin and trapezoid, exhibit the minimum cold-side temperature. Increasing the pulse ratio leads to a decrease in the cold-side temperature and an increase in the hot-side temperature. A notable improvement in the cold-side temperature is also observed with higher pulse ratios, with the pin geometry achieving a minimum cold-side temperature of 276 K. Furthermore, the cooling load affects the temperature on both sides of the TEC. These findings provide valuable insights for optimizing thermoelectric coolers for electronic cooling applications using pulse current methods.

A 19-year analysis of hot and cold temperature burdens on mortality in Amman, Jordan

BackgroundMost studies on climate-induced health effects have primarily focused on developed countries. Jordan, in particular, has seen limited research in quantifying the differential impacts of temperature on mortality. Jordan's unique demographic composition, characterized by significant refugee population influxes, necessitates research in this area to identify vulnerable populations. This study aims to: 1) quantify the mortality burden of hot and cold temperature in Amman, Jordan, and 2) identify vulnerable groups within the population. MethodsWe collected 19 years of daily all-cause mortality records from 2000 to 2018 in Amman, Jordan, aggregated by sex and nationality. We used a time series design in a distributed lag non-linear model for temperature to estimate non-linear associations and lagged effects of temperature on mortality across sex and nationality. We calculated attributable mortality for temperatures above (heat) and below (cold) the minimum mortality temperature for each category. ResultsWe analyzed 184,166 all-cause mortalities; 106,977 were males, and 22,118 were non-Jordanians. Amman's calculated minimum mortality temperatures were 23.2 °C for males, 21.5 °C for females, 22.3 °C for Jordanians, and 24.7 °C for non-Jordanians. Our findings reveal that females exhibited greater vulnerability to heat, with a 2.59 % (1.54 %, 3.59 %) heat attributable mortality fraction compared to 1.17 % (0.53 %, 1.80 %) for males, while non-Jordanians were susceptible to cold, with an 8.36 % (2.83 %, 14.66 %) cold attributable mortality fraction compared to 5.91 % (4.37 %, 7.41 %) for Jordanians. ConclusionThis study highlights the increased vulnerability of marginalized communities in Amman to temperature extremes. It emphasizes the need for further research to identify at-risk groups not only in Amman but also in other cities across Jordan. Such research is crucial for developing targeted protective strategies to safeguard these populations.

Adapting Harvests: A Comprehensive Study of Farmers’ Perceptions, Adaptation Strategies, and Climatic Trends in Dera Ghazi Khan, Pakistan

Understanding farmers’ perceptions, attitudes, and adaptation strategies toward climate change is important for developing effective policies that support agricultural development and food security in rural communities. This study aimed to understand climatic trends over the past two decades (2003–2022), farmers’ perceptions, and adaptation strategies regarding climate change in Dera Ghazi Khan, Pakistan. The Mann–Kendall trend test identified a significant decrease in average minimum temperature (τ = −0.357, p < 0.05) and an increase in rainfall patterns (τ = 0.337, p < 0.05). A mixed-method approach is employed, utilizing a survey of 180 randomly selected farmers, focus group discussions, and climate data analysis. Ordinal and binary logistic regression models were used to analyze the influence of sociodemographic factors on farmers’ perceptions of climate change and their choice of adaptation strategies. The results indicate that farmers primarily rely on religious beliefs/prayers (65.6%) to cope with climate change, followed by seeking off-farm jobs (50%) and changing fertilizer use (42.2%). The result of the binary logistic regression indicates that among the different demographic characteristics, education, and land size significantly influence farmers’ decisions in taking adaptation measures against climate change. This study emphasizes the need for climate policies that integrate farmer knowledge with meteorological data and sociodemographic analysis to ensure a sustainable agricultural sector in Pakistan. Further research is necessary to explore more effective adaptation methods.

Extension and trend of the London urban heat island under Lamb weather types

Understanding and describing how urban heat islands evolve is important, given the noticeable impact they have on people living in cities. This paper considers the London heat island from gridded values with one-arcminute spatial resolution over a 33-year period, from 1990 to 2022. Among the available variables in the database, maximum and minimum air temperatures were used. A cold island was not observed, since temperatures in the city centre were higher than those in the surroundings during the day and at night. However, the urban heat island extension was higher for the maximum temperature, whereas this island was limited to the city centre for the minimum temperature, in line with the area delimited by the congestion charge. Lamb weather types were determined, and it was found that the anticyclonic type prevailed, followed by southwest, west, and cyclonic types. The difference between both temperatures was about 6.8 °C in the city centre, and was particularly defined for anticyclonic and cyclonic types. Moreover, anticyclonic situations were linked with the highest urban heat island intensities for minimum temperature. Finally, the temperature trend was similar for both temperatures –about 0.2–0.3 °C/10 years in the city centre– thereby offering a possible quantification of climate change.

Rancang Bangun Green Portable Cooler Box

Freon is one of the refrigerants used in refrigeration systems. The refrigeration system has a very important role, namely to preserve food ingredients so that food can last longer. The use of freon is not only used in ships but is widely found in home appliances in refrigeration systems used in freezers, air conditioners, refrigerators, and dispensers. If more freon is used, the negative impact that arises is greater, namely the depletion of the ozone layer and global warming which can have a bad influence on health, the life of living things and the environment. The purpose of this researcher is to create a tool to reduce the negative impact of freon use, namely by using peltier as a cooling medium with environmentally friendly thermoelectric modules. This study uses trial and error methods. Where the trial process is carried out by turning on one of the working push buttons and observing the temperature value. Then it is processed by the control system, namely Arduino Mega which will later provide a PWM output signal to the IRF540 mosfet when the output temperature value is in line with the reference value and vice versa. The test of this tool was carried out by comparing measurements between the author's prototype tool and the standard measuring tool, namely the digital thermometer. Based on the test results, this device can produce a minimum temperature of 140C at 30-minute intervals without any media. The trial using 330ml bottled water can reach a temperature of 170C within 30 minutes in the cooler box. This tool is also equipped with an automatic monitoring system using a PWM signal in the form of a change in fan speed, which is 255 RPS maximum speed and when getting a PWM signal it changes to 50 RPS. The percentage of errors resulting from the comparison of standard measuring instruments and sensor values had the highest and lowest percentages of 2.37% and 0.84% in cold dispersion conditions without charge. Then the highest and lowest error percentages were 1.69% and 0.72% in the state of containing a load of 1 330ml mineral bottle. This ptototype uses data recording using Micro-SD as a data logger.

Interactive and lag effects of environmental factors on the density of schistosome-transmitting Oncomelania hupensis: A twelve-year monthly repeated survey.

Schistosomiasis is a significant public health threat, and Oncomelania hupensis is the only intermediate host for schistosoma japonicum. We conducted 12-year monthly repeated surveys to explore the interactive and lag effects of environmental factors on snail density and to monitor their long-term and seasonal trends in a bottomland around the Dongting Lake region in China. Relevant environmental data were obtained from multiple sources. A Bayesian kernel machine regression model and a Bayesian temporal model combined with a distributed lag model were constructed to analyze interactive and lag effects of environmental factors on snail density. The results indicated the average annual snail density in the study site exhibited an increasing and then decreasing trend, peaking in 2013. Snail densities were the highest in October and the lowest in January in a year. Normalized Difference Vegetation Index (NDVI) and water level were the most effective predictors of snail density, with potential interactions among temperature, precipitation, and NDVI. The mean minimum temperature in January, water level, precipitation and NDVI were positively correlated with snail density at lags ranging from 1 to 4 months. These findings could serve as references for relevant authorities to monitor the changing trend of snail density and implement control measures, thereby reducing the occurrence of schistosomiasis.

Reconstructing the Temperature and Precipitation Changes in the Northern Part of the Greater Khingan Mountains over the Past 210 Years Using Tree Ring Width Data

In northeastern China, simultaneous reconstruction of temperature and precipitation changes in the same region using tree ring data has not yet been reported, limiting our understanding of the historical climate. Using tree ring samples from the Greater Khingan Mountains, it was established that there are five standardized tree ring width chronologies of Pinus sylvestris var. mongolica at five elevations. Correlation analyses revealed significant relationships between the tree ring chronologies and climate data for multiple months. Specifically, the correlation coefficient between the average minimum temperature from May to July and the composite chronologies of mid–high and mid-elevations was 0.726, whereas that between the total precipitation from August to July and the low-elevation chronology was 0.648 (p < 0.01). Based on these findings, we reconstructed two series: the average minimum temperature from May to July over the past 211 years and the total precipitation from August to July over the past 214 years. The reconstructed sequences revealed changes in the average minimum temperature from 1812 to 2022 and precipitation from 1809 to 2022 in the northern part of the Greater Khingan Mountains. The variances explained by the reconstruction equations were 0.528 and 0.421 (adjusted R-squared: 0.520 and 0.411), with F-test values of 65.896 and 42.850, respectively, exceeding the significance level of 0.01. The reliability of the reconstructed sequences was validated by historical records of meteorological disasters and the reconstruction results in the surrounding area. The reconstructed temperature and precipitation sequences exhibited distinct patterns of temperature fluctuations, dry–wet changes, and periodic oscillations. The region experienced two warm periods (1896–1909 and 2006–2020), two cold periods (1882–1888 and 1961–1987), a wet period (1928–1938), a drought period (1912–1914), and a period prone to severe drought events (1893–1919) during the past 210 years. The temperature series showed periodicities of 2–2.5 years, 3.9 years, 5.2 years, and 68 years, while the precipitation series exhibited periodicities of 2.1 years, 2.5 years, and 2.8 years, possibly related to El Niño–Southern Oscillation (ENSO) events, quasi-biennial oscillation, and Pacific Decadal Oscillation (PDO). Spatial correlation analysis indicated that the reconstructed temperature and precipitation sequences accurately represented the hydrothermal changes in the study area.

CFD design and testing of an air flow distribution device for microwave infrared hot-air rolling-bed dryer

In this study, a new microwave infrared hot air rolling bed dryer (MIHRBD) was developed and computational fluid dynamics (CFD) techniques were introduced into the design process of the integrated drying system. The structure of the air distribution device was optimised to improve the airflow uniformity over the curved surface of the rolling bed in the microwave-hot air drying combined equipment. The research findings reveal that, across eleven models, the outlet airflow velocity stabilises once the number of mesh elements reaches 5 million, achieving significant computational accuracy at that point. Optimizing components like the uniform air distribution pipe, turbulence plates, and wind deflectors significantly enhanced airflow distribution uniformity by 52.1%. The best airflow and temperature distribution uniformity on the rolling bed surface was achieved when the inlet airflow velocity ranged from 1 to 3 m s−1, with minimum Vd, Uv and temperature non-uniformity coefficients of 0.007 m s−1, 7.2% and 0.2%, respectively. Validation tests on the MIHRBD pilot equipment showed that after optimizing the uniform air distribution device, the minimum temperature difference on the pleurotus eryngii surface was 3.1 °C. This confirmed the feasibility of the computational fluid dynamics method. Introducing hot air significantly enhanced pleurotus eryngii's drying uniformity, with the Page model effectively predicting the MIHRBD drying process. This study provides technical support for future developments in this field of equipment manufacturing and drying process analysis.

Examining the glacier-glacial lake interactions of potentially dangerous glacial lakes (PDGLs) under changing climate in Shyok catchment of the Upper Indus Basin

With the ongoing glacier recession, the Himalayan region is witnessing the development of glacial lakes fed by the glacial meltwater. Besides threatening the hydrological regime in the area, the rapid expansion of these lakes at the expense of their feeding glaciers poses a serious risk to the downstream communities in the form of Glacial Lake Outburst Floods, as many of these high-altitude water bodies are vulnerable to this cryospheric disaster under the changing climatic regime. Studying these potentially dangerous glacial lakes (PDGLs) and their feeding glaciers in the context of the changing climate has become crucial in understanding this phenomenon and managing the risk associated with these lakes. The present study focuses on understanding the glacier-lake interactions between the PDGLs and their feeding glaciers under the changing climatic regime. We analyzed the spatio-temporal dynamics of 16 PDGLs, identified in our previous study, and their feeding glaciers for the past three decades (1992–2022), and tried to unravel the relationships between glacier area, glacial lake area, and climatic variables such as temperature and precipitation. The results reveal a rapid expansion of 49.6% in the glacial lake area accompanied by a corresponding glacier recession of 3.27 % and an average terminus retreat of 171 m. The average glacier mass balance was found to be ⁓ −0.22 m w.e. y−1 during this period. The minimum temperature (Tmin) revealed statistically significant increasing trend, whereas the annual precipitation (Pcp) in the area revealed a slightly declining trend in this region. The glacial lake area was found to be in a significant positive correlation with the Tmin and a slight negative correlation with the annual precipitation (Pcp). The glacier area revealed a strong negative correlation with the glacial lake area, Tmax, and the Tmin and a positive correlation with the annual precipitation. The results indicate that the glacial lakes in the region are expanding at the expense of their feeding glaciers under warming climate.

Continental scale spatial temporal interpolation of near-surface air temperature: do 1 km hourly grids for Australia outperform regional and global reanalysis outputs?

Near-surface air temperature is an essential climate variable for the study of many biophysical phenomena, yet is often only available as a daily mean or extrema (minimum, maximum). While many applications require sub-diurnal dynamics, temporal interpolation methods have substantial limitations and atmospheric reanalyses are complex models that typically have coarse spatial resolution and may only be periodically updated. To overcome these issues, we developed an hourly air temperature product for Australia with spatial interpolation of hourly observations from 621 stations between 1990 and 2019. The model was validated with hourly observations from 28 independent stations, compared against empirical temporal interpolation methods, and both regional (BARRA-R) and global (ERA5-Land) reanalysis outputs. We developed a time-varying (i.e., time-of-day and day-of-year) coastal distance index that corresponds to the known dynamics of sea breeze systems, improving interpolation performance by up to 22.4% during spring and summer in the afternoon and evening hours. Cross-validation and independent validation (n = 24/4 OzFlux/CosmOz field stations) statistics of our hourly output showed performance that was comparable with contemporary Australian interpolations of daily air temperature extrema (climatology/hourly/validation: R2 = 0.99/0.96/0.92, RMSE = 0.75/1.56/1.78 °C, Bias = -0.00/0.00/-0.03 °C). Our analyses demonstrate the limitations of temporal interpolation of daily air temperature extrema, which can be biased due to the inability to represent frontal systems and assumptions regarding rates of temperature change and the timing of minimum and maximum air temperature. Spatially interpolated hourly air temperature compared well against both BARRA-R and ERA5-Land, and performed better than both reanalyses when evaluated against the 28 independent validation stations. Our research demonstrates that spatial interpolation of sub-diurnal meteorological fields, such as air temperature, can mitigate the limitations of alternative data sources for studies of near-surface phenomena and plays an important ongoing role in supporting numerous scientific applications.

Numerical analysis of tapered wick configurations in cylindrical heat pipes

Heat pipes are essential devices in thermal engineering due to their ability to transport heat with remarkable efficiency. They are crucial for heat distribution and control in a variety of applications, such as aircraft systems and electronics cooling. This paper presents a numerical analysis on the performance characteristics of a cylindrical heat pipe featuring a novel tapered wick geometry. A two-dimensional numerical model incorporating non-Darcian liquid transport is formulated and solved at steady state. To investigate the effect of the tapered wick geometry, major characteristics such as axial distribution of vapor pressure, liquid pressure and wall temperature are evaluated and analyzed. Based on the direction of taper, three configurations viz., THPE (Tapering wick heat pipe from evaporator end), THPC (Tapering wick heat pipe from condenser end) and THPA (Tapering wick heat pipe at adiabatic center) are studied. A novel non-dimensional parameter termed as Temperature Pressure Index (TPI) is proposed to signify the extent to which an HP can reduce its evaporator temperature relative to increase in pressure drop. Initially a parametric study is performed. Results showed a superior performance of THPE and THPC designs over THPA in terms of output parameters. The numerical findings demonstrate that when compared to a uniform wick heat pipe, both the THPE and THPC configurations exhibit a notable enhancement of 58 % in effective thermal conductivity under a maximum load of 455 W. Further, by conducting a variance-based (Sobol) sensitivity analysis, the THPC design is found to be marginally better as compared to THPE. Finally, the BOBYQA optimization algorithm is employed to find optimum taper angle for THPC design that maximizes the output parameters. The optimum taper angle of the wick is found to be 0.0372° for minimum average evaporator temperature in the present case. For this optimized THPC design, a reduction in average evaporator temperature of 6.51 K is obtained compared to uniform wick heat pipe. Additionally, the obtained TPI value is about 1.86 times than that of a uniform wick heat pipe.

Investigation on the operation performance of solar panels cooled by a natural draft cooling system

This paper is to investigate the feasibility of a natural draft cooling system for PV panel cooling in a typical hot and dry region (Hami, Xinjiang, China). A 3-D model of PV panels cooled by a natural draft cooling system is established using Fluent 2020R2 software, and the cooling effect of the natural draft cooling system on PV panels is simulated and analyzed based on the meteorological data of Hami, China. Simulation finds that the natural draft cooling system can reduce the average temperature of the PV panels. The minimum temperature drops of the PV panels in January (represents winter season), April (represents spring season), July (represents summer season) and October (represents autumn season) of the year 2020 are 1.7 °C, 3.1 °C, 6.1 °C and 2.5 °C, respectively; while the maximum temperature drops of the PV panels are 7.0 °C, 11.2 °C, 15.5 °C and 6.3 °C, respectively. Besides, the natural draft cooling system is also compared with the PV panels without cooling system in six typical days, and finds that the PV panel with a natural draft cooling system increases the photoelectric conversion efficiency by up to 1.41 % (i.e., from 13.71 % to 15.12 %) when compared with the PV panel without cooling. Therefore, the proposed natural draft cooling system can effectively reduce the temperature of PV panels in Hami, Xinjiang.

Analysis of Meteorological Drought for Selected Districts of Saurashtra Region of Gujarat

Drought, in particular, is a complex and recurring phenomenon triggered by insufficient precipitation or changes in its distribution, often resulting in decreased water availability. It evolves slowly, affecting large populations' access to food and water, disrupting the entire hydrological cycle, and causing long-term economic losses. The present study attempts a comprehensive analysis of meteorological drought characteristics for selected districts (Junagadh, Amreli, Jamnagar, and Rajkot) in the semi-arid Saurashtra region of Gujarat. The analysis of meteorological drought was performed using rainfall (RF), maximum temperature (Tmax), and minimum temperature (Tmin) data from four stations (each district has one station) for the 43 years duration (1981–2023). The Standardized Precipitation Evapotranspiration Index (SPEI) is utilized across multiple timescales to assess the number of drought affected years, occurrence of drought and drought parameters (total drought duration, magnitude, and intensity). The meteorological drought incidence varied significantly across Junagadh, Amreli, Jamnagar and Rajkot, with Junagadh experiencing droughts in 29% of years, Amreli in 32%, and higher rates in Jamnagar (37%) and Rajkot (36%). The most severe drought years in the four districts were 1987 and 2002, with additional major droughts occurred in 1985, 1986, 1987, 1993, 2002 and 2012. These districts also faced consecutive droughts from 1985 to 1987 and again from 1999 to 2002.Analysis of drought parameters in Junagadh, Amreli, Jamnagar and Rajkot districts showed that drought duration (DD) ranged from 29.46% (Junagadh) to 35.85% (Jamnagar) of months, drought magnitude (DM) varied between -37.58% (Jamnagar) and -34.10% (Junagadh), and drought intensity (DI) spanned from -1.17 (Rajkot) to -1.04 (Junagadh). The analysis of drought occurrence in all districts shows that mild and moderate droughts have been most frequent while severe and extreme droughts have been less common. The study's findings enhance water managers' understanding of how climate change influences drought patterns in the region, thereby assisting policymakers in conducting effective drought risk assessments.

Efficacy of cardiopulmonary bypass method with blood delivery via femoral artery cannulation for paediatric aortic arch repair

IntroductionThe efficacy of cardiopulmonary bypass (CPB) management with blood delivery via femoral artery cannulation for paediatric aortic arch repair has yet to be reported. This study aimed to verify the hypothesis that this CPB method would reduce lactate elevation compared to CPB management using circulatory arrest of the lower body under deep hypothermia.MethodsThis study included patients who underwent paediatric aortic arch repairs between March 2012 and March 2018 at the German Paediatric Heart Centre, Sankt Augustin. Patients who were repumped intraoperatively were excluded. Group A (lower body circulatory arrest), Group F (retrograde aortic perfusion via femoral artery cannulation), and Group D (antegrade descending aortic perfusion) included 41, 18, and 15 patients, respectively. The CPB records were retrospectively reviewed for the minimum body temperature during CPB (℃), lactate levels before CPB (mmol/L), CPB duration (min), aortic clamp time duration (min), total urine output (mL) and changes in lactate levels during CPB (mmol/L).ResultsThe minimum body temperatures during CPB were 16.79 ± 1.48℃, 23.73 ± 4.67℃, and 30.59 ± 2.35 ℃ in Groups A, F, and D, respectively. The increases in lactate levels during CPB in Group F (1.06 ± 0.94) were significantly lower than in Group A (1.66 ± 0.90, p = 0.033); however, no different from Group D (0.92 ± 1.13, p = 0.807).ConclusionThis CPB method is a promising alternative to the CPB method using antegrade descending aortic perfusion for paediatric aortic arch repair.Trial registrationUMIN000052933.

Heat Enhancement in a Short Air Channel with Solid and Permeable Baffles

Heat transfer enhancement to turbulent air flow in a short rectangular constant-wall temperature channel fitted with either solid or permeable baffles were numerically studied based on COMSOL® simulations. The number of used baffles (1 to 7), Reynolds number (10000, 20000, and 30000), and baffle permeability (1 × 10−11 to 1 × 10−6) were investigated. Operations under turbulent flow conditions were considered, which has not been extensively studied. The average temperature of air at the channel exit and the pressure drop along the channel were obtained via simulation for different cases. For solid baffles, the heat transfer enhancement parameter ranged from 0.30 to 0.35 due to the high friction, while for permeable baffles, it ranged from 1 to 35 as the permeability and number of baffles increased. This is due to the heat-transfer-area increase and pressure-drop reduction when the flow passes through the permeable baffles. For permeable baffles, a minimum heat exchanger temperature approach of 10 K was achieved with minimal pressure drop at a permeability of approximately 4 × 10−8 when using 4–6 permeable baffles. Accordingly, the results demonstrated that using four permeable baffles with a permeability of approximately 4 × 10−8 m 2 is optimal from thermal, economical, and mechanical viewpoints.