Daily Temperature Difference Research Articles

Влияние на климатичните промени върху хематологичния и биохимичен статус на стадо крави от порода Лимузин в средата на два последователни пасищни сезона

The aim of the present study was to evaluate the status in the red and white blood count, together with the values of some enzymes and metabolites - ALT, AST, ALP, serum iron and glucose in selected animals from a herd of Limousine beef cattle in the middle of two consecutive grazing seasons, with large differences in the average daily temperature, the amount and distribution of precipitation and of the quantity and quality of the grass at the end of its vegetation. The study was conducted in the experimental base “Zlatusha” of the IAS-Kostinbrod with 15 pregnant cows equalized by BCS and age, from which blood samples were taken in July, 2022 and 2023, by venipuncture of the tail vein. The analysis of hematological indicators in whole blood was performed with a 5-Part-Diff Automated Hematology Analyzer URIT-5160, and the analysis of biochemical indicators - in plasma extracted from it with a Semi-automatic Biochemical Analyzer BTS-350. Results are expressed as mean values ± S.E.M. and were analyzed statistically by the analysis of variance (ANOVA) method. Although there was almost no difference in the levels of hematocrit and the number of erythrocytes in the middle of two grazing seasons, in July, 2022, the studied cows had a significantly higher level of hemoglobin than in July, 2023 (P<0.001), which reflected also on the significance of the difference in mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) – also at P<0.001. There were no significant differences in leukocyte counts and leukocyte subpopulations and in iron and glucose concentrations in the middle of two consecutive years. ALT and AST enzyme activities were significantly lower (P<0.05), and ALP activity was significantly higher in July, 2022 (P<0.01).

Impact of typical environments in China's western mountainous areas on the durability of railway concrete: a review

PurposeThis study aims to analyze the impact mechanism of typical environments in China's western mountainous areas on the durability of railway concrete and propose measures to improve durability.Design/methodology/approachWith the continuous promotion of infrastructure construction, the focus of China's railway construction has gradually shifted to the western region. The four typical environments of large temperature differences, strong winds and dryness, high cold and low air pressure unique to the western mountainous areas of China have adverse effects on the durability of typical railway structure concrete (bridges, ballastless tracks and tunnels). This study identified the characteristics of four typical environments in the western mountainous areas of China through on-site research. The impact mechanism of the four typical environments on the durability of concrete in different structural parts of railways has been explored through theoretical analysis and experimental research; Finally, a strategy for improving the durability of railway concrete suitable for the western mountainous areas of China was proposed.FindingsThe daily temperature difference in the western mountainous areas of China is more than twice that of the plain region, which will lead to significant temperature deformation and stress in the multi-layered structure of railway ballastless tracks. It will result in cracking. The wind speed in the western plateau region is about 2.5 to 3 times that of the plain region, and the average annual rainfall is only 1/5 of that in the plain region. The drying effect on the surface of casting concrete will significantly accelerate its cracking process, leading to serious durability problems. The environmental temperature in the western mountainous areas of China is generally low, and there are more freeze-thaw cycles, which will increase the risk of freeze-thaw damage to railway concrete. The environmental air pressure in the western plateau region is only 60% of that in the plain region. The moisture inside the concrete is more likely to diffuse into the surrounding environment under the pressure difference, resulting in greater water loss and shrinkage deformation of the concrete in the plateau region. The above four issues will collectively lead to the rapid deterioration of concrete durability in the western plateau region. The corresponding durability improvement suggestions from theoretical research, new technology development and standard system was proposed in this paper.Originality/valueThe research can provide the mechanism of durability degradation of railway concrete in the western mountainous areas of China and corresponding improvement strategies.

Comparative transcriptome analysis reveals the impact of daily temperature difference on male sterility in photo-thermo-sensitive male sterile wheat

BackgroundPhoto-thermo-sensitive male sterility (PTMS), which refers to the male sterility triggered by variations in photoperiod and temperature, is a crucial element in the wheat two-line hybrid system. The development of safe production and efficient propagation for male sterile lines holds utmost importance in two-line hybrid wheat. Under the stable photoperiod condition, PTMS is mainly induced by high or low temperatures in wheat, but the effect of daily temperature difference (DTD) on the fertility conversion of PTMS lines has not been reported. Here, three BS type PTMS lines including BS108, BS138, and BS366, as well as a control wheat variety J411 were used to analyze the correlation between fertility and DTD using differentially sowing tests, photo-thermo-control experiments, and transcriptome sequencing.ResultsThe differentially sowing tests suggested that the optimal sowing time for safe seed production of the three PTMS lines was from October 5th to 25th in Dengzhou, China. Under the condition of 12 h 12 °C, the PTMS lines were greatly affected by DTD and exhibited complete male sterility at a temperature difference of 15 °C. Furthermore, under different temperature difference conditions, a total of 20,677 differentially expressed genes (DEGs) were obtained using RNA sequencing. Moreover, through weighted gene co-expression network analysis (WGCNA) and KEGG enrichment analysis, the identified DEGs had a close association with “starch and sucrose metabolism”, “phenylpropanoid biosynthesis”, “MAPK signaling pathway-plant”, “flavonoid biosynthesis”, and “cutin, and suberine and wax biosynthesis”. qRT-PCR analysis showed the expression levels of core genes related to KEGG pathways significantly decreased at a temperature difference of 15 ° C. Finally, we constructed a transcriptome mediated network of temperature difference affecting male sterility.ConclusionsThe findings provide important theoretical insights into the correlation between temperature difference and male sterility, providing guidance for the identification and selection of more secure and effective PTMS lines.

Variability in the summer movements, habitat use and thermal biology of two fish species in a temperate river

The ability of fish to cope with warm water temperatures in summer depends on factors including their thermal traits and the ability of individuals to access cool-water refugia. Knowledge is highly limited on the in situ responses of many fishes to elevated summer temperatures, including whether they express behavioural thermoregulation. The responses of two riverine species to summer water temperatures were tested here using the movement metrics, spatial habitat use and body temperatures of individual European barbel Barbus barbus (‘barbel’) and common bream Abramis brama (‘bream’) versus river temperatures. Acoustic biotelemetry was applied in the lower River Severn basin, western Britain, in summer 2021 (barbel) and 2022 (bream), where individuals could move across > 150 km of river, including a tributary of cooler water. Across all individuals, bream occupied 37 km of river length (mainstem only), with low inter-individual variability in their spatial habitat use, movements and body temperatures. In contrast, barbel occupied 62 km of river (main river/tributary), with relatively high inter-individual variability in spatial habitat use, movements and body temperatures, with higher variation in body temperatures as river temperatures increased (maximum mean daily temperature difference between individuals on the same day: 4.2 °C). Although warmer individuals generally moved more, their activity was greatest at relatively low temperatures and higher flows, and neither species revealed any evidence of behavioural thermoregulation during elevated temperatures. Enabling phenotypically diverse fish populations to express their natural behaviours and thermal preferences in summer water temperatures thus requires maintaining their free-ranging in thermally heterogenous habitats.

Asphalt pavement heat insulation bonding layer materials: Composition optimization and engineering application

To alleviate the influence of extreme temperature on the service quality and life of asphalt pavement, the heat insulation effect of the pavement bonding layer was endowed, and the composition of the heat insulation bonding layer materials were optimized. The microstructure of heat insulation bonding layer material was revealed, and its optimal spraying amounts was determined. On this basis, the engineering application and service performance monitoring of heat insulation bonding layer materials were carried out. The results show that the curing rate of the heat insulation bonding layer is significantly higher than that of the ordinary emulsified asphalt (OEA) bonding layer. Hollow glass bead (HGB), floating bead (FB), and expanded perlite (EP) bonding layer materials exhibit excellent mechanical strength, and the interlayer bonding strength can reach 0.41 MPa, 0.49 MPa, and 0.49 MPa, respectively. The recommended dosage of HGB, FB, and EP is 15%, 20%, and 20%, respectively, and the spraying amounts of heat insulation bonding layer material is 1.2 kg/m2. The maximum temperature of the test section in July can be reduced by 2.2 °C–3.6 °C, the maximum annual and daily temperature differences can be reduced by 6.2 °C and 2.3°C–4.9 °C, and the rate of temperature changes can be reduced by 37.5%–63.64%.

Sap Yield and Sugar Content of Boxelder and Norway Maple Trees in Northern Utah

Maple syrup is a well-known natural sweetener made from the sap harvested from maple trees (Acer sp.). The North American scientific literature regarding maple syrup has predominantly originated in the Northeastern United States and Canada. However, the range of this Holarctic genus extends across the continent and all species produce sap with the potential for syrup production. This study focuses on two maple species commonly found in Northern Utah, namely the native boxelder (Acer negundo) and the introduced Norway maple (Acer platanoides). Thirty trees of each species were tapped in Cache Valley, UT, USA, on 19 Feb 2022, and measured for daily sap yield and sugar content until the season ended 37 days later on 27 Mar 2022. The same trees were re-tapped on 1 Mar 2023 and taps were removed 41 days later on 10 Apr 2023. Average 2022 sap yields were 22.1 L for boxelder and 7.5 L for Norway maple per tree. In 2023, average sap yields were 26.4 L for boxelder and 9.3 L for Norway maple per tree. Boxelder trees produced an average sap yield more than double that of Norway maple in both years. Sugar content was similar for both species ranging from 2.2% to 2.8%. Air temperatures were analyzed using data from Utah AgWeather System weather stations nearest to the trees, and air temperature had a significant impact on sap yield. It was found that an average daily air temperature of 0.5 °C and a daily air temperature difference of ∼10 °C with a minimum air temperature close to −5 °C and a maximum air temperature of ∼6 °C was the optimal condition for production. An analysis of the mineral nutrient concentrations in the sap and soil showed no correlation. These findings indicate that there is potential for using Utah’s maple species for syrup production.

Effect of Temperature Variation on the Incidence of Acute Myocardial Infarction.

Harsh temperature exposure has been associated with a high risk of cardiovascular events. We sought to investigate the influence of temperature change on long-term incidence of acute myocardial infarction (AMI) in Korean patients. From the National Health Insurance Service (NHIS) customized health information database (from 2005 to 2014), data from a total of 192,567 AMI patients was assessed according to the International Classification of Disease 10th edition code and matched with temperature reports obtained from the Korea Meteorological Administration database. We analyzed data for a 10-year period on a monthly and seasonal basis. The incidence rate per 100,000 year of AMI exhibited a downward trend from 69.1 to 56.1 over the period 2005 to 2014 (P < 0.005), and the seasonal AMI incidence rate per 100,000 year was highest in spring (63.1), and winter (61.3) followed by autumn (59.5) and summer (57.1). On a monthly basis, the AMI incidence rate per 100,000 year was highest during March (64.4) and December (63.9). The highest incidence of AMI occurred during temperature differences of 8-10° in each season. Moreover, AMI incidence tended to increase as the mean temperature decreased (r = -0.233, P = 0.001), and when the mean daily temperature difference increased (r = 0.353, P < 0.001). The AMI incidence rate per 100,000 year has a decreasing trend over the 10-year period, derived from the Korean NHIS database. Modest daily temperature differences (8-10°) and the spring season are related to higher AMI incidence, indicating that daily temperature variation is more important than the mean daily temperature.

Structural Health Monitoring System for a Complicated Long‐Span Continuous Girder Bridge: Implementation and Demonstration

The Dongbao River Xin’an Bridge is the first hybrid continuous girder bridge with corrugated steel webs in China. To assess its service conditions and guarantee its safe operation, a continuous structural health monitoring (SHM) system is designed in this paper. The SHM system consists of a sensor system, a data acquisition and transmission system, and a data processing and control system. The measurement parameters, including vehicle loads, temperature, deformation, strain, and acceleration, are determined, and a detailed sensor layout is given based on the mechanical characteristics of the bridge. The SHM system adopts a bus gateway and an IP modem to collect and transmit sensor data. Monitoring data from October 9, 2022, to March 16, 2023, were analyzed. The probability distributions of the daily maximum temperature differences and vehicle loads are reconstructed. The correlation of girder deflection and strain with ambient temperature has been demonstrated. The identification and tracking of modal parameters are implemented. The results show that the maximum deflection is within the threshold range and that the modal parameters are basically stable. All the results demonstrate the healthy structural condition of the bridge and the excellent working performance of the SHM system. The collected data provide scientific guidance for the performance evaluation of the Dongbao River Xin’an Bridge and the optimized design of similar bridges.

Characterization of the Energy Balance of Wheat Grown under Irrigation in the Hot, Arid Environment of Sudan

An analysis of the crop microclimate is essential for assessing the climate’s appropriateness for cultivation. Here, the Bowen ratio (BR) was used to characterize the energy balance in an irrigated wheat field in a hot, arid environment in Sudan. The hourly BR was calculated using micrometeorological data, including net radiation (Rn) and soil heat flux (G), observed in the 2021–2022 and 2022–2023 growing seasons (December–March) and used to compute hourly daytime latent heat (LE) and sensible heat (H) fluxes during the days before and after irrigation. In both seasons, the observed significant evaporative cooling effect of irrigation led to a daily maximum temperature difference of 2.5–5.7 °C between the wheat field and a nearby meteorological station in a non-vegetated desert area. The energy balance calculation results showed that LE was dominant over H and G. Because BR tended to be negative, H was negative; thus, LE was larger than Rn because of sensible heat advection from the surrounding area. Further, a decrease in G after irrigation indicated an alteration in the soil’s thermal properties. These results provide insights into the micrometeorological response of irrigated wheat to a hot, arid environment and useful information for understanding soil–plant–atmosphere interactions in hot, dry environments.

Dynamics and variability of microclimate in an unmanaged mountain forest after a bark beetle outbreak

Forest disturbances alter hydrological, energy, and microclimatic characteristics and their extents vary with the landscape characteristics of the terrain. We evaluated changes in evapotranspiration and latent heat rate in an unmanaged, central European mountain forest (Norway spruce) after a bark beetle-induced mortality of >75 % trees, and the spatial variability in microclimate during its natural regeneration. We observed that (1) the annual mean incident solar radiation to the treeless plots was 8.2 MJ m−2 day−1 (95 W m−2), being reduced by ∼45 % compared to its theoretical flux by high average cloudiness (70.6%) and short daily sunshine (4.3 hour day−1). The observed energy input to the forest floor beneath survived canopies (1.2 MJ m−2 day−1) was an order of magnitude lower than solar radiation to the canopy surface. (2) The mean annual evapotranspiration and the average annual latent heat rate decreased by 155 mm yr−1 and 385 MJ m−2 yr−1 (12 W m−2), respectively, after tree dieback. (3) The soil and air temperatures at individual plots correlated positively with the incident solar radiation and negatively with elevation. Mean soil and air temperatures exhibited similar lapse rates of 5.9–8.0 °C km−1 during the growing season (May-October). The energy input (positive relationship) and elevation (negative relationship) explained 74–83 % of the between-plot variability in mean soil and air temperatures and 51–77 % of their daily amplitudes during the growing season. (4) On sunny days, the observed soil and air temperatures were significantly lower (by ∼50 and 15 %, respectively) than ground surface temperature based on thermal satellite data (Landsat-8). The ground surface temperature explained 80–92 % of the observed variability in the soil and air temperatures. (5) The between-plot differences in daily soil and air temperatures and their amplitudes were from 24 to 70 % explained by solar radiation (positive correlation) and relative air humidity and wind speed (negative correlations).

Temperature gradient of ballastless track in large daily temperature difference region and its influence on dynamic responses of vehicle-track-bridge system

Due to the large daily temperature difference on the ultra-high altitude plateau of China, the actual vertical temperature gradient (TG) of ballastless track may exceed the design value in the Code. The temperature monitoring platform of the double-block ballastless track was established to obtain the temperature distribution characteristics of track. The finite element model of the temperature field of the track is developed to study the warping deformation of track, and then the influence of TG on the dynamic responses of the vehicle-track-bridge system (VTBS) are investigated. The results show that the maximum positive temperature gradient (PTG) and negative temperature gradient (NTG) of the track bed slab are 88.875 ℃/m and − 47.159 ℃/m, respectively, and the latter exceeds the design value in the Code. The dynamic responses are positively correlated with the TG, and the influence of the NTG is more significant. The dynamic response of the rail is most sensitive to the TG.

Technical aspects of the development of solar energy refrigeration technology on solid sorbents

Objective. The purpose of the study is a scientific review of the stages of development of refrigeration technology with sorption action on solid sorbents and an assessment of the current state of development of such household equipment in relation to the use of solar energy.Method. The dynamics of the development of solar energy refrigeration equipment based on sorption thermotransformers, the working vapors of which are solid sorbents and ozone-safe refrigerants, are analyzed. The beginning of development comes from the creation of periodic installations operating from the thermal energy of traditional energy carriers: hot water, burning of hydrocarbon or organic fuels, electric energy, and cooling with water and air and ends with modern refrigeration units operating from the energy of solar radiation and the daily temperature difference of the environment.Result. The peculiarities of making technical decisions underlying the design of the main devices of solar energy refrigeration units are noted. Circuit designs and operating principles of installations and their devices used to improve operating efficiency are described. The main trends in research conducted by scientists to improve the operation of solar energy thermal transformers of cyclic action are considered.Conclusion. This article may be useful to young scientists, engineers and designers for the design and development of innovative autonomous thermal transmitters and refrigeration units for cooling and short-term storage of products and medicines, obtaining food ice, air conditioning, operating independently from solar energy. Such installations are easy to manufacture and operate.

Monitoring leaf area index of the sown mixture pasture through UAV multispectral image and texture characteristics

Leaf area index (LAI) is an important phenotypic trait closely related to photosynthesis, respiration, and water utilization. In recent years, unmanned aerial vehicles (UAVs) multispectral capabilities enable the acquisition of spectral information from visible light to near infrared, facilitating vegetation growth monitoring. This study aims to explore the methodology of combining vegetation indices, color indices, texture information, and ecological factors based on UAV multispectral images to enhance the accuracy of the sown mixture pasture LAI estimation. A field experiment involving 13 mixed sowing combinations of alfalfa (Medicago sativa L.), tall fescue (Festuca elata Keng ex E. Alexeev) and plantain (Plantaga lanceolata L.) was conducted out. Multiple linear regression, Bagging algorithm, support vector machine (SVM), random forest algorithm (RF), KNN algorithm, and back propagation neural network (BP) were used to construct the LAI prediction model. The results showed that combining vegetation index (VI) + color index (CI) + normalized difference texture index (NDTI), and ecological factors (EF) could enhance the accuracy of LAI estimation. The sensitive characteristic combinations for alfalfa, tall fescue, and plantain were found to be NDRE (Normalized difference red-edge index) + NGBDI (Normalized green–blue difference index) + (B) MEA-(G) HOM (Blue band Mean - Green band Homogeneity) + DTR (Daily temperature difference), MSR (Modified simple ratio) + NGRDI (Normalized green–red difference index) + (G) COR-(R) VAR (Green band Correlation – Red band Variance) + DTR (Daily temperature difference)), and MSR (Modified simple ratio) + ExG (Excess green) + (G) SEM-(G) MEA (Green band Second-order moment – Green band Mean) + DTR (Daily temperature difference), respectively. RF exhibited superior prediction capability, further enhancing the accuracy of forage LAI prediction. The alfalfa, tall fescue, and plantain obtained coefficient of determination (R2) of 0.83, 0.79 and 0.79, root mean squared error (RMSE) of 0.50, 0.58 and 0.70, and mean absolute error (MAE) of 0.36, 0.45 and 0.55, respectively. These findings provide valuable insights for the estimation of leaf area index of the sown mixture pasture through UAV multispectral images and texture characteristics.

Micrometeorological Analysis and Glacier Ablation Simulation in East Kunlun

Worldwide, there are great challenges for meteorological monitoring and glacier ablation monitoring in high-altitude mountain areas. It is often difficult to capture fine-scale climate and glacial changes in high-altitude mountainous areas due to the harsh natural environment and the extreme lack of observational sites. Based on high-altitude meteorological stations erected on the eastern shore of Aqikkule Lake (AQK) and at the terminus of Shenshechuan Glacier (SSG), as well as on mass balance data from SSG, the characteristics and correlation of temperature, solar radiation, relative humidity, precipitation, wind speed and direction of the two regions, and the mass balance in the ablation area of SSG from 30 May 2022 to 18 May 2023 were analyzed, and the average melting depth of SSG was simulated. The results indicate the following: (1) The average annual temperature of AQK and the terminus of SSG is −3.7 °C and −7.7 °C, respectively, and the vertical lapse rate of temperature in the summer half of the year is greater than that in the winter half of the year. Precipitation timing has a great influence on daily temperature differences. (2) Precipitation in both places is concentrated in summer; the glaciers in this area are of the summer recharge type, and precipitation has a significant reducing effect on the solar incident radiation and increases the relative humidity in this region. (3) AQK and SSG both have local circulation development, in the area of AQK all year round due to the lake effect, while the terminus of SSG only has the development of valley winds in the summer, being controlled in the winter by the westerly wind belt. (4) The average mass balance value of the ablation area of SSG was −1786 mm as measured by the range poles method. The average annual ablation depth of SSG simulated by using the empirical formula was 587–597 mm, which is not large compared with other glacier areas in the Tibetan Plateau, and it has the characteristics of typical continental-type glaciers.

Small‐scale surface heterogeneity and potential inhomogeneities in temperature time series: A case study

AbstractMeasurements in seven sites in the Campus of the University of the Balearic Islands (UIB; Mallorca, Spain) during an experimental campaign to study the contribution of local surface heterogeneities on the surface energy budget at one point have been used to characterize the differences in extreme daily temperatures between the sites during a summer month. Absolute temperature differences in this month reached up to 1.92 (with a median of 0.73) and 2.02 (median of 1.21)°C for daily maximum and minimum, respectively. Higher differences in the minimum temperature can be attributed to the stably stratified and weak turbulent conditions at night that enhance local differences in the surface energy fluxes, especially in an area with strong variability of the surface characteristics like the UIB Campus. Instead, during daytime, maximum temperature differences are smoothed due to the convection and the horizontal advection due to the sea‐breeze. Two sites with longer records allowed to study the seasonal variations of these differences, which were substantially lower in the colder months. These results suggest that relocation of observatories, even at distances as short as 200 m, may introduce important inhomogeneities in the temperature series. Therefore, raw values of series from nearby stations should not be used to infill missing data in other series without adequate statistical adjustments.

Rubber latex yield is affected by interactions between antecedent temperature, rubber phenology, and powdery mildew disease.

Rubber (Hevea brasiliensis) latex production is crucial to the local economy, yet Xishuangbanna's climate is considered sub-optimal for rubber cultivation. The prevalence of the powdery mildew disease (Oidium heveae) in this region has decreased the annual latex yield by 20%. Rubber latex yield is influenced by several factors, including temperature, disease, other biotic conditions, and plantation management. However, the interrelationships and potential influencing networks between rubber latex yield and these factors are rarely quantitatively assessed, and understanding their impacts on latex yield could inform better management practices. To address this gap, we investigated the effects of temperature, phenology, and powdery mildew disease on rubber latex yield in March using observational data on daily rubber latex yield combined with detailed phenology, powdery mildew, and temperature data from 2004 to 2010 in a state farm in the Xishuangbanna, Yunnan, China. We found that the critical influencing periods of daily temperature difference (or diurnal temperature difference) on the rubber latex yield were during Nov 27-Jan 19 and Jan 21-Mar 17. Partial least square regression analysis and variance partitioning analysis were conducted on the 35 phenological variables, eight powdery mildew-related variables, and two climatic variables. The most influential factors were identified as the factors of the daily temperature differences during Jan-Mar, the duration of leaf flushing phenology, and mean and maximum percentage of leaves infected by powdery mildew. Subsequent canonical correlation analysis and linear regression found that temperature difference directly affected the rubber latex yield and indirectly affected the yield through phenology and powdery mildew disease. Raised daily temperature differences from Jan to Mar had the greatest impact, leading to a higher rubber latex yield. Our comprehensive quantitative assessment revealed the relative importance of antecedent daily temperature differences, phenology, and powdery mildew disease as well as their complex interconnections in influencing rubber latex yield. Our findings are essential tofuture studies on both powdery mildew disease and rubber latex yield, and alsodevelop rubber latex models.

Field measurement and analysis of subway tunnel thermal environment in severe cold region

Recently, subways in China's severe cold regions have developed rapidly. Harbin, a typical city in a severe cold region, can reach the lowest outdoor temperature of −37.7 °C in winter, making the thermal environment of the underground tunnels a huge challenge. Due to the complexity of the subway environment, there are few long-term field measurements, and the research on entrance and exit lines is often neglected. In this study, the thermal environment of Harbin Metro Line 1/3 and the entrance and exit lines was measured and studied, the heat production of train operation and annual heat storage heat was calculated. The results show that climatic conditions, burial depth, operating phase of the tunnel, passenger flow, and driving interval have an impact on the thermal environment of the tunnel. The daily average temperature difference between the two ends of the entrance and exit lines reached a maximum of 27.4 °C in winter. The average air temperature of Line 1 in summer, transition season and winter were 4.0 °C, 1.0 °C and 2.5 °C higher than that of Line 3, and the heat generated per hour was 201 MJ–242 MJ higher than Line 3. Furthermore, the heat storage capacity of tunnels in severe cold region was significantly higher than that in hot summer and warm winter region, the maximum difference was 823 GJ. The monitoring data are useful for both analytical and numerical studies and this study provide a valuable reference for the construction and operation of subways in severe cold regions.

A New Method for Separating Temperature Effect of Bridge Strain Monitoring

Temperature has a significant influence on bridge strain monitoring data. To improve the accuracy of temperature effect separation in strain monitoring data, this paper proposes a temperature effect separation method comprising variational nonlinear chirp mode decomposition (VNCMD), principal component analysis (PCA) and blind source separation. Firstly, VNCMD was used to decompose the monitoring data of strain and temperature, and the intrinsic mode functions (IMF) of strain and temperature signals were obtained. Secondly, PCA was used to reduce the dimension of IMF, and the false components were eliminated to select the optimal components. After reducing the dimension, the components were used as the input of fast independent component analysis model for blind source separation. Finally, the feasibility and accuracy of the method was verified via the signal-to-noise ratio (SNR) in the simulated signal, and the separation results were evaluated using the Pearson correlation coefficient between the strain component and the corresponding temperature component in real bridge monitoring data. The proposed method performed better than the empirical mode decomposition (EMD) method. The signal-to-noise ratio (SNR) of VNCMD improved 51.80% for daily temperature difference effect and 32.41% for annual temperature difference effect in the numerical study, respectively; the correlation coefficients of VNCMD improved 52.90% for daily temperature difference effect and 4.26% for annual temperature difference effect in practical verification, respectively.

Study of the influence of meteorological factors on HFMD and prediction based on the LSTM algorithm in Fuzhou, China

BackgroundThis study adopted complete meteorological indicators, including eight items, to explore their impact on hand, foot, and mouth disease (HFMD) in Fuzhou, and predict the incidence of HFMD through the long short-term memory (LSTM) neural network algorithm of artificial intelligence.MethodA distributed lag nonlinear model (DLNM) was used to analyse the influence of meteorological factors on HFMD in Fuzhou from 2010 to 2021. Then, the numbers of HFMD cases in 2019, 2020 and 2021 were predicted using the LSTM model through multifactor single-step and multistep rolling methods. The root mean square error (RMSE), mean absolute error (MAE), mean absolute percentage error (MAPE) and symmetric mean absolute percentage error (SMAPE) were used to evaluate the accuracy of the model predictions.ResultsOverall, the effect of daily precipitation on HFMD was not significant. Low (4 hPa) and high (≥ 21 hPa) daily air pressure difference (PRSD) and low (< 7 °C) and high (> 12 °C) daily air temperature difference (TEMD) were risk factors for HFMD. The RMSE, MAE, MAPE and SMAPE of using the weekly multifactor data to predict the cases of HFMD on the following day, from 2019 to 2021, were lower than those of using the daily multifactor data to predict the cases of HFMD on the following day. In particular, the RMSE, MAE, MAPE and SMAPE of using weekly multifactor data to predict the following week's daily average cases of HFMD were much lower, and similar results were also found in urban and rural areas, which indicating that this approach was more accurate.ConclusionThis study’s LSTM models combined with meteorological factors (excluding PRE) can be used to accurately predict HFMD in Fuzhou, especially the method of predicting the daily average cases of HFMD in the following week using weekly multifactor data.

Optimization and regulation of pavement concrete properties in plateau environment with large daily temperature difference: From mixture design to field application

Cement concrete pavement has been widely utilized in road engineering in western China due to its low cost, easy maintenance, and long service life. However, the properties of pavement concrete were very sensitive to the local environment, particularly for high-speed wind and large daily temperature difference. This study aims to regulate the workability and mechanical properties of pavement concrete from mixture proportion design, then on-site paving was carried out to validate the feasibility of field application. Although the cement paste volume ratio decreased from 25.4% to 21.3%, target compressive strength (40 MPa) of pavement concrete was achieved by optimizing the gradation of fine and coarse aggregates. And the volume stability of pavement concrete was improved after replacing 8% of Portland cement by limestone powder. For field application in a plateau environment with daily temperature difference around 20 °C and wind-speed of 5.5–7.0 m/s, the temperature difference and internal strain of concrete pavement with thickness of 30 cm were controlled within 4.0 °C and 57 ε, respectively. More importantly, no visible cracks were observed for concrete pavement with surface area of 400 m2. The results provided a feasible approach to design and regulate the mixture of pavement concrete with superior cracking resistance, and then promoted the application of concrete pavement in high expressway engineering in severe environment.