The intense research of lithium-ion batteries has been motivated by their successful applications in mobile devices and electronic vehicles.The emerging of intelligent control in kinds of devices brings new requiremen...The intense research of lithium-ion batteries has been motivated by their successful applications in mobile devices and electronic vehicles.The emerging of intelligent control in kinds of devices brings new requirements for battery systems.The high-energy lithium batteries are expected to respond or react under different environmental conditions.In this work,a tri-salt composite electrolyte is designed with a temperature switch function for intelligently temperature-controlled lithium batteries.Specifically,the halide Li_(3)YBr_(6)together with LiTFSI and LiNO_(3)works as active fillers in a low-melting-point polymer matrix(polyethyleneglycol dimethyl ether(PEGDME)and polyethylene oxide(PEO)),which is further filled into the pre-lithiated alumina fiber skeleton.Above 60°C,the composite electrolyte exists in the liquid state and fully contacts with the working electrodes on the liquid–solid interface,effectively minimizing the interfacial resistance and leading to high discharge capacity in the cell.The electrolyte is changed into a solid state below 30°C so that the ionic conductivity is significantly reduced and the interface resistance is increased dramatically on the solid–solid interface.Therefore,by simply adjusting the temperature,the cell can be turned“ON”or“OFF”intentionally.This novel function of the composite electrolyte has enlightening significance in developing intelligently temperature-controlled lithium batteries.展开更多
The yield of winter wheat is hindered by drought and low temperature in the Loess Plateau of China.Two common mulching methods to conserve soil moisture,ridge furrows with plastic film mulching (RP) and flat soil surf...The yield of winter wheat is hindered by drought and low temperature in the Loess Plateau of China.Two common mulching methods to conserve soil moisture,ridge furrows with plastic film mulching (RP) and flat soil surfaces with plastic film mulching (FP) are helpful for wheat production.Our previous study indicated that FP could improve wheat yield more effectively than RP,but the reason remains unclear.The effect of mulching method on functional bacteria also needs to be further studied.In this study,winter wheat was employed to evaluate the impacts of mulching method on soil temperature,moisture content,microorganisms and grain yield.The results showed that FP had a warming effect when the soil temperature was low and a cooling effect when the temperature was too high.However,the ability to regulate soil temperature in the RP method was unstable and varied with year.The lowest negative accumulated soil temperature was found in the FP treatment,which was 20–89 and 43–99%lower than that of the RP and flat sowing with non-film mulching control (NP) treatments,respectively.Deep soil moisture was better transferred to topsoil for wheat growth in the FP and RP treatments than the NP treatment,which made the topsoil moisture in the two treatments (especially FP) more sufficient than that in the NP treatment during the early growing stage of wheat.However,due to the limited water resources in the study area,there was almost no difference between treatments in topsoil water storage during the later stage.The wheat yield in the FP treatment was significantly higher,by 12–16and 23–56%,respectively,than in the RP and NP treatments.Significant positive correlations were observed among the negative accumulated soil temperature,spike number and wheat yield.The Chao1 and Shannon indices in the RP treatment were 17 and 3.9%higher than those in the NP treatment,respectively.However,according to network relationship analysis,the interspecific relationships of bacteria were weakened in the RP treatment.Phosphorus solubilizing,ammonification and nitrification bacteria were more active in the RP than in the FP treatment,and microbes with nitrate reduction ability and plant pathogens were inhibited in the RP treatment,which improved nutrient availability and habitat for wheat.展开更多
To evaluate and predict the quality of carrots during logistics process in North China under extreme temperature conditions,quality indicator changes of carrots were investigated,and temperature-coupled quality predic...To evaluate and predict the quality of carrots during logistics process in North China under extreme temperature conditions,quality indicator changes of carrots were investigated,and temperature-coupled quality prediction models were developed.Seven temperatures were selected from meteorological temperature data by cluster analysis to simulate the changes in extreme temperatures during the short-term transportation of carrots.No carrots rotted during the 48h storage period.Under both isothermal and nonisothermal conditions,weight loss andΔE increased while the firmness and sensory evaluation(SE)decreased.The RBFNN performed better than the Arrhenius model in predicting weight loss andΔE,with R^(2)>0.97,MSE<0.009 and relative errors within±18%.The results of the predictive confidence level and standardized residual indicated the good performance of the RBFNN model.The temperature-coupled prediction models of RBFNN were promising candidates for predicting the quality of vegetable products and therefore reducing economic loss of vegetable industry.展开更多
Soil temperature regime(STR)is important for soil classification and land use.Generally,STR is delineated by estimating the mean annual soil temperature at a depth of 50 cm(MAST50)according to the Chinese Soil Taxonom...Soil temperature regime(STR)is important for soil classification and land use.Generally,STR is delineated by estimating the mean annual soil temperature at a depth of 50 cm(MAST50)according to the Chinese Soil Taxonomy(CST).However,delineating the STR of China remains a challenge due to the difficulties in accurately estimating MAST50.The objectives of this study were to explore environmental factors that influence the spatial variation of MAST50 and generate an STR map for China.Soil temperature measurements at 40 and 80 cm depth were collected from 386 National Meteorological Stations in China during 1971–2000.The MAST50 was calculated as the average mean annual soil temperature(MAST)from 1971–2000 between 40 and 80 cm depths.In addition,2048 mean annual air temperature(MAAT)measurements from 1971 to 2000 were collected from the National Meteorological Stations across China.A zonal pedotransfer function(PTF)was developed based on the ensemble linear regression kriging model to predict the MAST50 in three topographic steps of China.The results showed that MAAT was the most important variable related to the variation of MAST50.The zonal PTF was evaluated with a 10%validation dataset with a mean absolute error(MAE)of 0.66°C and root mean square error(RMSE)of 0.78°C,which were smaller than the unified model with MAE of 0.83°C and RMSE of 0.96°C,respectively.This study demonstrated that the zonal PTF helped improve the accuracy of the predicted MAST50 map.Based on the prediction results,an STR map across China was generated to provide a consistent scientific base for the improvement and application of CST and land use support.展开更多
Temperature response functions have been developed to investigate sensor design and divertor heat flux estimation in magnetically confined plasmas. The time-dependent heat flux can be derived by fitting the response f...Temperature response functions have been developed to investigate sensor design and divertor heat flux estimation in magnetically confined plasmas. The time-dependent heat flux can be derived by fitting the response function to experimental thermocouple(TC) data. Because the TC signals have a time delay to transit events such as discharge start or confinement transition, the time delay is taken into account in a temperature response function. Such a function accurately describes the signal from each TC channel with time delay in a sensor test using a neutral beam injection. Measurement for commercial TCs shows that the time delay is caused by the finite heat capacity of TC wire and contact heat resistance between TC and target surface.展开更多
The shallow-water temperature profile is typically parameterized using a few empirical orthogonal function(EOF)coefficients.However,when the experimental area is poorly known or highly variable,the adaptability of the...The shallow-water temperature profile is typically parameterized using a few empirical orthogonal function(EOF)coefficients.However,when the experimental area is poorly known or highly variable,the adaptability of the EOFs will be significantly reduced.In this study,a new set of basis functions,generated by combining the internal-wave eigenmodes with the average temperature gradient,is developed for characterizing the temperature perturbations.Temperature profiles recorded by a thermistor chain in the South China Sea in 2015 are processed and analyzed.Compared to the EOFs,the new set of basis functions has higher reconstruction accuracy and adaptability;it is also more stable in ocean regions that have internal waves.展开更多
It is of utmost necessity to understand the dynamics of regional active accumulated temperature(AAT)to cope with the negative impacts of global warming on agroforestry development and food security and to provide a re...It is of utmost necessity to understand the dynamics of regional active accumulated temperature(AAT)to cope with the negative impacts of global warming on agroforestry development and food security and to provide a real-time and effective reference basis for regional agroforestry planning.The daily temperature data from 30 meteorological stations in Sichuan Province from 1970 to 2020,and sea surface temperature(SST)index data from the Atlantic Multiphase Oscillation(AMO)and Pacific Decadal Oscillation(PDO)were used for the study.Sichuan Province was divided into the western region(WS)and the eastern region(ES),considering 1000 m above sea level as the boundary.The spatiotemporal characteristics of≥0℃ and≥10℃ active accumulated temperature(AAT0,AAT10)in WS and ES were analyzed comprehensively using 5-day average sliding,empirical orthogonal function(EOF),ensemble empirical mode decomposition(EEMD),and multiple mutation tests.The results show that(1)AAT0 and AAT10 of WS ranged from 3034℃ to 3586℃ and 1971℃ to 2636℃,respectively,while the AAT0 and AAT10 of ES ranged from 5863℃ to 6513℃ and 4847℃ to 5875℃,respectively.The period around 1997 was a significant abrupt change,and the AAT in the province generally increased during the subsequent time period(2)AAT in the study area is mainly driven by the fluctuations of AMO,as reflected by the low-to-high variation of AAT coinciding with the jump of the cold-to-warm phase of AMO.Considering different time scale fluctuations in the past 51 years,the major cycle for both AAT0 and AAT10 in WS is 3.40 a,while the major cycles in ES are 3.64 a and 3.19 a,respectively with a sub-cycle of 7.29 a.AAT fluctuation has an insignificant periodic characteristic of 25.50 a on the interdecadal scale(3)The spatial heterogeneity of AAT in WS is prominent and is mainly reflected by the significantly warm conditions in the south of the WS region and relatively slight warm conditions in the north,as well as by the isolated cooling area in the form of"freezing point",i.e.,Xiaojin county.In contrast,the spatial variability of AAT in ES is more or less consistent,with the warming areas concentrated in the foothills of the western edge of the basin and a slight increase in AAT observed in the central part of the basin.展开更多
Binary azeotropes, which contain two chemicals with a relative volatility of 1, are very common in the chemical industry. Understanding azeotropes is essential for effectively separating binary azeotropes containing l...Binary azeotropes, which contain two chemicals with a relative volatility of 1, are very common in the chemical industry. Understanding azeotropes is essential for effectively separating binary azeotropes containing lower alcohols. Experimental techniques and ab initio approaches can produce accurate results;however, these two processes are time consuming and labor intensive. Although thermodynamic equations such as UNIFAC are widely used, experimental values are required, and it is difficult to choose the best groups to represent a complex system. Because of their high efficiency and fast calculation speed, quantitative structure–property relationship(QSPR) tools were used in this work to predict the azeotropic temperatures and compositions of binary azeotropes containing lower alcohols. The QSPR models for 64 binary azeotropes based on centroid approximation and weighted-contribution-factor approximation were established using the genetic function approximation(GFA) procedure in Materials Studio software, and a leave-one-out cross-validation procedure was conducted.External tests of an additional 16 azeotropes were also investigated, and high determination coefficient values were obtained. The best QSPR models were explained in terms of the molecular structure of the azeotropes,and good predictive ability was obtained within acceptable prediction error levels.展开更多
Understanding the temperature affecting parasitic efficiency is critical to succeed in utilizing parasitoid as natural enemy in pest management. Laboratory studies were carried out to determine the effects of temperat...Understanding the temperature affecting parasitic efficiency is critical to succeed in utilizing parasitoid as natural enemy in pest management. Laboratory studies were carried out to determine the effects of temperature on parasitoid preference of female Anagrus nilaparvatae Pang et Wang (Hymenoptera:Mymaridae) to the eggs of whitebacked planthopper (WBPH), Sogatella furcifera Horváth and brown planthopper (BPH), Nilaparvata lugens Stl to build a composite model describing changes in parasitic response along a temperature gradient (18, 22, 26, 30, 34°C). The results showed that attack responses of A. nilaparvatae on WBPH and BPH were the best described by a Type II functional response. The two parameters, attack rates (a) and handling times (Th), of A. nilaparvatae to both eggs were influenced by the temperature. The maximum attack rates to WBPH (1.235) and BPH (1.049) were at 26 and 34°C, respectively, and the shortest handling times to WBPH (0.063) and BPH (0.057) were at 30 and 26°C, respectively. However, the optimal temperature for parasitic efficiency of A. nilaparvatae to WBPH and BPH eggs was both at 26°C, which showed that the present microclimate temperature of the habitat in the paddyfield was beneficial to A. nilaparvatae and indicated that parasitic efficiency of A. nilaparvatae would be impaired by global warming.展开更多
Background: Air temperature affects absorptive root traits, which are closely related to species distribution.However, it is still unclear how air temperature regulates species distribution through changes in absorpti...Background: Air temperature affects absorptive root traits, which are closely related to species distribution.However, it is still unclear how air temperature regulates species distribution through changes in absorptive root traits. Seven functional traits of the absorptive roots of 240 individuals of 52 species, soil properties and air temperature were measured along an elevational gradient on Mt. Fanjingshan, Tongren City, Guizhou, and then the direct and indirect effects of these controls on species distribution were detected.Results: Absorptive roots adapted to air temperature with two strategies. The first strategy was positively associated with the specific root area(SRA) and specific root length(SRL) and was negatively associated with the root tissue density(RTD), representing the classic root economics spectrum(RES). The second strategy was represented by the trade-off between root diameter, mycorrhizal fungi colonization(MF) and SRL, representing the collaboration gradient with “do it yourself” resource uptake ranging from “outsourcing” to mycorrhizal resource uptake. Air temperature regulated species distribution in six ways: directly reducing species importance value;indirectly increasing the species importance value by reducing soil nitrogen content or increasing soil pH by reducing soil moisture inducing absorptive roots to change from “do it yourself” resource absorption to “outsourcing” resource absorption;indirectly decreasing the species importance value by decreasing soil moisture to change from“outsourcing”resource absorption to “do it yourself” resource absorption;indirectly increasing the species importance value with increasing soil pH by reducing soil moisture resulting in absorptive root traits turning into nutrient foraging traits;and indirectly decreasing the species importance value by promoting absorptive root traits to nutrient conservation traits.Conclusions: Absorptive root traits play a crucial role in the regulation of species distribution through multiapproaches of air temperature.展开更多
A new method is presented for getting the general thermal response factors and z-transfer functioncoefficients of a room by synthesizing them from the thermal response factors of different parts of the thermalinsulati...A new method is presented for getting the general thermal response factors and z-transfer functioncoefficients of a room by synthesizing them from the thermal response factors of different parts of the thermalinsulation structure. How to use the general thermal response factors and z-transfer function coefficients toca1culate the indoor air temperature variation directly is also studied. It is shown through practical use that it iseasy to program with the methods presented in this paper and the calculated results are reliable.展开更多
Wire arc additive manufacture(WAAM) is a new technique to fabricate large-scale complex aluminum alloy components.However, the performance of the parts is critically influenced by residual stresses and deformation. A ...Wire arc additive manufacture(WAAM) is a new technique to fabricate large-scale complex aluminum alloy components.However, the performance of the parts is critically influenced by residual stresses and deformation. A sequentially thermal-mechanical coupled model of residual stress and deformation for aluminum alloy WAAM parts was established based on commercial FE software ABAQUS. The temperature field was calculated by the moving heat source(MHS) method. The temperature function was obtained according to the distribution of the peak temperature. Furthermore, the MHS method and segmented temperature function(STF) method were used to calculate the residual stress and deformation. The results show that the STF method satisfies both the efficiency and accuracy requirements. 1-segment, 3-segment, and 5-segment STF methods can shorten the time for mechanical analysis by 91%, 79%, 63%, respectively.The error of the residual stress and deformation are all less than 20%. STF method provides an effective way to predict the residual stress and deformation of large-scale WAAM parts.展开更多
In order to simplify the boundary conditions of pavement temperature field,the "Environment-Surface" system which considered the natural environment and pavement surface was established.Based on this system,...In order to simplify the boundary conditions of pavement temperature field,the "Environment-Surface" system which considered the natural environment and pavement surface was established.Based on this system,the partial differential equations of the one-dimensional heat conduction in the pavement were established on the basis of the heat transfer theory.Furthermore,the function forms of the initial and boundary conditions of the equations were created through the field experiments.The general solution of the pavement one-dimensional heat conduction partial differential equations was acquired by using Green's function,and the explicit expression of pavement temperature field under specific constraint conditions was derived.For the purpose of analysis,the pavement temperatures in different seasons were calculated using the explicit expression of pavement temperature field,and the calculation accuracy was analyzed through the comparison between measured and calculated values.Then,the relationship between fitting accuracy and calculation accuracy of pavement temperatures was analyzed.The analysis results show that: the usage of "Environment-Surface" system simplifies the calculation of pavement temperature field; the relative error between calculated and measured values is generally less than 7% and is seldom influenced by seasons; there is a positive correlation between the calculation accuracy and the fitting accuracy of pavement surface temperature; high fitting accuracy would result in less error of pavement temperature prediction.展开更多
The air cooler is an important equipment in the petroleum refining industry.Ammonium chloride(NH4 Cl)deposition-induced corrosion is one of its main failure forms.In this study,the ammonium salt crystallization temper...The air cooler is an important equipment in the petroleum refining industry.Ammonium chloride(NH4 Cl)deposition-induced corrosion is one of its main failure forms.In this study,the ammonium salt crystallization temperature is chosen as the key decision variable of NH4 Cl deposition-induced corrosion through in-depth mechanism research and experimental analysis.The functional link neural network(FLNN)is adopted as the basic algorithm for modeling because of its advantages in dealing with non-linear problems and its fast-computational ability.A hybrid FLNN attached to a small norm is built to improve the generalization performance of the model.Then,the trained model is used to predict the NH4 Cl salt crystallization temperature in the air cooler of a sour water stripper plant.Experimental results show the proposed improved FLNN algorithm can achieve better generalization performance than the PLS,the back propagation neural network,and the conventional FLNN models.展开更多
The finite element method (FEM) and the boundary element method (BEM) are often adopted. However, they are not convenient to spatially vary thermal properties of functionally graded material (FGM). Therefore, the meth...The finite element method (FEM) and the boundary element method (BEM) are often adopted. However, they are not convenient to spatially vary thermal properties of functionally graded material (FGM). Therefore, the method of lines (MOL) is introduced to solve the temperature field of FGM. The basic idea of the method is to semi-discretize the governing equation into a system of ordinary differential equations (ODEs) defined on discrete lines by means of the finite difference method. The temperature field of FGM can be obtained by solving the ODEs. The functions of thermal properties are directly embodied in these equations and these properties are not discretized in the domain. Thus, difficulty of FEM and BEM is overcome by the method. As a numerical example, the temperature field of a plane problem is analyzed for FGMs through varying thermal conductivity coefficient by the MOL.展开更多
Effects of electron temperature on dielectric function and localization of laser beams in underdense collisional plasmas are investigated. Simulation results show that the electron temperature has a strong effect on t...Effects of electron temperature on dielectric function and localization of laser beams in underdense collisional plasmas are investigated. Simulation results show that the electron temperature has a strong effect on the dielectric constant and the laser beam localization. It is observed that due to the influence of the electron temperature, the dielectric function presents some interesting and complicated nonlinear variations, and gives rise to the laser beam lo- calization. Moreover, the amplitudes of the beam width and the beam intensity are subjected to continuously oscillatory variation in the region of localization. In addition, the effects of several parameters on the dielectric function and the beam localization are discussed.展开更多
A new static microwave sounding unit (MSU) channel 4 weighting function is obtained from using Coupled Model Inter-comparison Project, Phase 5 (CMIP5) historical multimodel simulations as inputs into the fast Radi...A new static microwave sounding unit (MSU) channel 4 weighting function is obtained from using Coupled Model Inter-comparison Project, Phase 5 (CMIP5) historical multimodel simulations as inputs into the fast Radiative Transfer Model for TOVS (RTTOV v10). For the same CMIP5 model simulations, it is demonstrated that the computed MSU channel 4 brightness temperature (T4) trends in the lower stratosphere over both the globe and the tropics using the proposed weighting function are equivalent to those calculated by RTTOV, but show more cooling than those computed using the traditional UAH (University of Alabama at Huntsville) or RSS (Remote Sensing Systems in Santa Rosa, California) static weighting functions. The new static weighting function not only reduces the computational cost, but also reveals reasons why trends using a radiative transfer model are different from those using a traditional static weighting function. This study also shows that CMIP5 model simulated T4 trends using the traditional UAH or RSS static weighting functions show less cooling than satellite observations over the globe and the tropics. Although not completely removed, this difference can be reduced using the proposed weighting function to some extent, especially over the tropics. This work aims to explore the reasons for the trend differences and to see to what extent they are related to the inaccurate weighting functions. This would also help distinguish other sources for trend errors and thus better understand the climate change in the lower stratosphere.展开更多
A functional integral approach (FIA) is introduced to calculate the transition temperature of a uniform imperfect Bose gas. With this approach we find that the transition temperature is higher than that of the corresp...A functional integral approach (FIA) is introduced to calculate the transition temperature of a uniform imperfect Bose gas. With this approach we find that the transition temperature is higher than that of the corresponding ideal gas. We obtain the expression of the transition temperature shift as , where n is the density of particle number and a is the scattering length. The result has never been reported in the literature.展开更多
In this study, the sliced functional time series (SFTS) model is applied to the Global, Northern and Southern temperature anomalies. We obtained the combined land-surface air and sea-surface water temperature from God...In this study, the sliced functional time series (SFTS) model is applied to the Global, Northern and Southern temperature anomalies. We obtained the combined land-surface air and sea-surface water temperature from Goddard Institute for Space Studies (GISS), NASA. The data are available for Global mean, Northern Hemisphere mean and Southern Hemisphere means (monthly, quarterly and annual) since 1880 to present (updated through March 2019). We analyze the global surface temperature change, compare alternative analyses, and address the questions about the reality of global warming. We detected the outliers during the last century not only in global temperature series but also in northern and southern hemisphere series. The forecasts for the next twenty years are obtained using SFTS models. These forecasts are compared with ARIMA, Random Walk with drift and Exponential Smoothing State Space (ETS) models. The comparison is made on the basis of root mean square error (RMSE), mean absolute percentage error (MAPE) and the length of prediction intervals.展开更多
The free vibration characteristics of functionally graded micro-switches under combined electrostatic, axial residual stress and temperature change is investigated, with an emphasis on the effect of geometric nonlinea...The free vibration characteristics of functionally graded micro-switches under combined electrostatic, axial residual stress and temperature change is investigated, with an emphasis on the effect of geometric nonlinear deformation due to mid-plane stretching, the influence of volume fraction profile parameter and temperature change. The micro-switch considered in this study is made of either homogeneous material or non-homogeneous functionally graded material with two material phases. Taking the temperature-dependency of the effective material properties into consideration, the Voigt model is used to simulate the material properties of the FGMs (functionally graded materials). The principle of virtual work is used to derive the nonlinear governing differential equation. The eigenvalue problem which describes free vibration of the micro-beam at its statically deflected state is then solved using DQM (differential quadrature method). The natural frequencies of clamped-clamped micro-switches are obtained. The solutions are validated through direct comparisons with experimental results reported in previous studies. A parametric study is conducted to show the effects of geometric nonlinearity, material composition, temperature change and geometrical parameters for the natural frequencies.展开更多
基金Financial support from the National Natural Science Foundation of China(22279065 and 21935006)is gratefully acknowledged.
文摘The intense research of lithium-ion batteries has been motivated by their successful applications in mobile devices and electronic vehicles.The emerging of intelligent control in kinds of devices brings new requirements for battery systems.The high-energy lithium batteries are expected to respond or react under different environmental conditions.In this work,a tri-salt composite electrolyte is designed with a temperature switch function for intelligently temperature-controlled lithium batteries.Specifically,the halide Li_(3)YBr_(6)together with LiTFSI and LiNO_(3)works as active fillers in a low-melting-point polymer matrix(polyethyleneglycol dimethyl ether(PEGDME)and polyethylene oxide(PEO)),which is further filled into the pre-lithiated alumina fiber skeleton.Above 60°C,the composite electrolyte exists in the liquid state and fully contacts with the working electrodes on the liquid–solid interface,effectively minimizing the interfacial resistance and leading to high discharge capacity in the cell.The electrolyte is changed into a solid state below 30°C so that the ionic conductivity is significantly reduced and the interface resistance is increased dramatically on the solid–solid interface.Therefore,by simply adjusting the temperature,the cell can be turned“ON”or“OFF”intentionally.This novel function of the composite electrolyte has enlightening significance in developing intelligently temperature-controlled lithium batteries.
基金supported by the State Key Laboratory of Integrative Sustainable Dryland Agriculture (in preparation)Shanxi Agricultural University, China (202105D121008)+1 种基金the National Natural Science Foundation of China (42007121)the National Key R&D Program of China (2021YFD1900700)。
文摘The yield of winter wheat is hindered by drought and low temperature in the Loess Plateau of China.Two common mulching methods to conserve soil moisture,ridge furrows with plastic film mulching (RP) and flat soil surfaces with plastic film mulching (FP) are helpful for wheat production.Our previous study indicated that FP could improve wheat yield more effectively than RP,but the reason remains unclear.The effect of mulching method on functional bacteria also needs to be further studied.In this study,winter wheat was employed to evaluate the impacts of mulching method on soil temperature,moisture content,microorganisms and grain yield.The results showed that FP had a warming effect when the soil temperature was low and a cooling effect when the temperature was too high.However,the ability to regulate soil temperature in the RP method was unstable and varied with year.The lowest negative accumulated soil temperature was found in the FP treatment,which was 20–89 and 43–99%lower than that of the RP and flat sowing with non-film mulching control (NP) treatments,respectively.Deep soil moisture was better transferred to topsoil for wheat growth in the FP and RP treatments than the NP treatment,which made the topsoil moisture in the two treatments (especially FP) more sufficient than that in the NP treatment during the early growing stage of wheat.However,due to the limited water resources in the study area,there was almost no difference between treatments in topsoil water storage during the later stage.The wheat yield in the FP treatment was significantly higher,by 12–16and 23–56%,respectively,than in the RP and NP treatments.Significant positive correlations were observed among the negative accumulated soil temperature,spike number and wheat yield.The Chao1 and Shannon indices in the RP treatment were 17 and 3.9%higher than those in the NP treatment,respectively.However,according to network relationship analysis,the interspecific relationships of bacteria were weakened in the RP treatment.Phosphorus solubilizing,ammonification and nitrification bacteria were more active in the RP than in the FP treatment,and microbes with nitrate reduction ability and plant pathogens were inhibited in the RP treatment,which improved nutrient availability and habitat for wheat.
基金This study was supported by the National Natural Science Foundation of China(grant numbers:3207150985)。
文摘To evaluate and predict the quality of carrots during logistics process in North China under extreme temperature conditions,quality indicator changes of carrots were investigated,and temperature-coupled quality prediction models were developed.Seven temperatures were selected from meteorological temperature data by cluster analysis to simulate the changes in extreme temperatures during the short-term transportation of carrots.No carrots rotted during the 48h storage period.Under both isothermal and nonisothermal conditions,weight loss andΔE increased while the firmness and sensory evaluation(SE)decreased.The RBFNN performed better than the Arrhenius model in predicting weight loss andΔE,with R^(2)>0.97,MSE<0.009 and relative errors within±18%.The results of the predictive confidence level and standardized residual indicated the good performance of the RBFNN model.The temperature-coupled prediction models of RBFNN were promising candidates for predicting the quality of vegetable products and therefore reducing economic loss of vegetable industry.
基金funded by the National Key Basic Research Special Foundation of China(2021FY100405)the National Natural Science Foundation of China(U20A20114,42201069 and 42077002)the Fundamental Research Funds for Central Non-profit Scientific Institution,China(1610132018012).
文摘Soil temperature regime(STR)is important for soil classification and land use.Generally,STR is delineated by estimating the mean annual soil temperature at a depth of 50 cm(MAST50)according to the Chinese Soil Taxonomy(CST).However,delineating the STR of China remains a challenge due to the difficulties in accurately estimating MAST50.The objectives of this study were to explore environmental factors that influence the spatial variation of MAST50 and generate an STR map for China.Soil temperature measurements at 40 and 80 cm depth were collected from 386 National Meteorological Stations in China during 1971–2000.The MAST50 was calculated as the average mean annual soil temperature(MAST)from 1971–2000 between 40 and 80 cm depths.In addition,2048 mean annual air temperature(MAAT)measurements from 1971 to 2000 were collected from the National Meteorological Stations across China.A zonal pedotransfer function(PTF)was developed based on the ensemble linear regression kriging model to predict the MAST50 in three topographic steps of China.The results showed that MAAT was the most important variable related to the variation of MAST50.The zonal PTF was evaluated with a 10%validation dataset with a mean absolute error(MAE)of 0.66°C and root mean square error(RMSE)of 0.78°C,which were smaller than the unified model with MAE of 0.83°C and RMSE of 0.96°C,respectively.This study demonstrated that the zonal PTF helped improve the accuracy of the predicted MAST50 map.Based on the prediction results,an STR map across China was generated to provide a consistent scientific base for the improvement and application of CST and land use support.
基金partially performed with the support and under the auspices of the NIFS Collaborative Research Program(Nos.NIFS20KLPR051,NIFS20KUHL099 and NIFS20KUGM153)。
文摘Temperature response functions have been developed to investigate sensor design and divertor heat flux estimation in magnetically confined plasmas. The time-dependent heat flux can be derived by fitting the response function to experimental thermocouple(TC) data. Because the TC signals have a time delay to transit events such as discharge start or confinement transition, the time delay is taken into account in a temperature response function. Such a function accurately describes the signal from each TC channel with time delay in a sensor test using a neutral beam injection. Measurement for commercial TCs shows that the time delay is caused by the finite heat capacity of TC wire and contact heat resistance between TC and target surface.
基金The Natural Science Foundation of Shandong Province of China under contract Nos ZR2022MA051 and ZR2020MA090the Fund of China Postdoctoral Science Foundation under contract No.2020M670891+1 种基金the Shandong University of Science and Technology Research Fund under contract No.2019TDJH103the Talent Introduction Plan for Youth Innovation Team in Universities of Shandong Province(Innovation Team of Satellite Positioning and Navigation).
文摘The shallow-water temperature profile is typically parameterized using a few empirical orthogonal function(EOF)coefficients.However,when the experimental area is poorly known or highly variable,the adaptability of the EOFs will be significantly reduced.In this study,a new set of basis functions,generated by combining the internal-wave eigenmodes with the average temperature gradient,is developed for characterizing the temperature perturbations.Temperature profiles recorded by a thermistor chain in the South China Sea in 2015 are processed and analyzed.Compared to the EOFs,the new set of basis functions has higher reconstruction accuracy and adaptability;it is also more stable in ocean regions that have internal waves.
基金the National Natural Science Foundation of China(Grant No.51779114)。
文摘It is of utmost necessity to understand the dynamics of regional active accumulated temperature(AAT)to cope with the negative impacts of global warming on agroforestry development and food security and to provide a real-time and effective reference basis for regional agroforestry planning.The daily temperature data from 30 meteorological stations in Sichuan Province from 1970 to 2020,and sea surface temperature(SST)index data from the Atlantic Multiphase Oscillation(AMO)and Pacific Decadal Oscillation(PDO)were used for the study.Sichuan Province was divided into the western region(WS)and the eastern region(ES),considering 1000 m above sea level as the boundary.The spatiotemporal characteristics of≥0℃ and≥10℃ active accumulated temperature(AAT0,AAT10)in WS and ES were analyzed comprehensively using 5-day average sliding,empirical orthogonal function(EOF),ensemble empirical mode decomposition(EEMD),and multiple mutation tests.The results show that(1)AAT0 and AAT10 of WS ranged from 3034℃ to 3586℃ and 1971℃ to 2636℃,respectively,while the AAT0 and AAT10 of ES ranged from 5863℃ to 6513℃ and 4847℃ to 5875℃,respectively.The period around 1997 was a significant abrupt change,and the AAT in the province generally increased during the subsequent time period(2)AAT in the study area is mainly driven by the fluctuations of AMO,as reflected by the low-to-high variation of AAT coinciding with the jump of the cold-to-warm phase of AMO.Considering different time scale fluctuations in the past 51 years,the major cycle for both AAT0 and AAT10 in WS is 3.40 a,while the major cycles in ES are 3.64 a and 3.19 a,respectively with a sub-cycle of 7.29 a.AAT fluctuation has an insignificant periodic characteristic of 25.50 a on the interdecadal scale(3)The spatial heterogeneity of AAT in WS is prominent and is mainly reflected by the significantly warm conditions in the south of the WS region and relatively slight warm conditions in the north,as well as by the isolated cooling area in the form of"freezing point",i.e.,Xiaojin county.In contrast,the spatial variability of AAT in ES is more or less consistent,with the warming areas concentrated in the foothills of the western edge of the basin and a slight increase in AAT observed in the central part of the basin.
基金Supported by the National Natural Science Foundation of China(21776145,21676152)Key Research Project of Shandong Province(2016GSF116004)
文摘Binary azeotropes, which contain two chemicals with a relative volatility of 1, are very common in the chemical industry. Understanding azeotropes is essential for effectively separating binary azeotropes containing lower alcohols. Experimental techniques and ab initio approaches can produce accurate results;however, these two processes are time consuming and labor intensive. Although thermodynamic equations such as UNIFAC are widely used, experimental values are required, and it is difficult to choose the best groups to represent a complex system. Because of their high efficiency and fast calculation speed, quantitative structure–property relationship(QSPR) tools were used in this work to predict the azeotropic temperatures and compositions of binary azeotropes containing lower alcohols. The QSPR models for 64 binary azeotropes based on centroid approximation and weighted-contribution-factor approximation were established using the genetic function approximation(GFA) procedure in Materials Studio software, and a leave-one-out cross-validation procedure was conducted.External tests of an additional 16 azeotropes were also investigated, and high determination coefficient values were obtained. The best QSPR models were explained in terms of the molecular structure of the azeotropes,and good predictive ability was obtained within acceptable prediction error levels.
基金supported by the Special Fund for Agro-Scientific Research in the Public Interest, China (200903051 and 200803003)
文摘Understanding the temperature affecting parasitic efficiency is critical to succeed in utilizing parasitoid as natural enemy in pest management. Laboratory studies were carried out to determine the effects of temperature on parasitoid preference of female Anagrus nilaparvatae Pang et Wang (Hymenoptera:Mymaridae) to the eggs of whitebacked planthopper (WBPH), Sogatella furcifera Horváth and brown planthopper (BPH), Nilaparvata lugens Stl to build a composite model describing changes in parasitic response along a temperature gradient (18, 22, 26, 30, 34°C). The results showed that attack responses of A. nilaparvatae on WBPH and BPH were the best described by a Type II functional response. The two parameters, attack rates (a) and handling times (Th), of A. nilaparvatae to both eggs were influenced by the temperature. The maximum attack rates to WBPH (1.235) and BPH (1.049) were at 26 and 34°C, respectively, and the shortest handling times to WBPH (0.063) and BPH (0.057) were at 30 and 26°C, respectively. However, the optimal temperature for parasitic efficiency of A. nilaparvatae to WBPH and BPH eggs was both at 26°C, which showed that the present microclimate temperature of the habitat in the paddyfield was beneficial to A. nilaparvatae and indicated that parasitic efficiency of A. nilaparvatae would be impaired by global warming.
基金financially supported by the National Nature Science Foundation of China (No.32001248)the Characteristic Field Project of Department of Education of Guizhou Province (NO.[2019]075)+3 种基金PhD Research Start-up Foundation of Tongren University (No.trxyDH1807)Guizhou Forestry Research Project (No.[2019]014)the Science and Technology Plan Project of Guizhou Province (NO.[2019]1312,NO.[2022]general-556)the Key Laboratory Project of Guizhou Province (No.[2020]2003)
文摘Background: Air temperature affects absorptive root traits, which are closely related to species distribution.However, it is still unclear how air temperature regulates species distribution through changes in absorptive root traits. Seven functional traits of the absorptive roots of 240 individuals of 52 species, soil properties and air temperature were measured along an elevational gradient on Mt. Fanjingshan, Tongren City, Guizhou, and then the direct and indirect effects of these controls on species distribution were detected.Results: Absorptive roots adapted to air temperature with two strategies. The first strategy was positively associated with the specific root area(SRA) and specific root length(SRL) and was negatively associated with the root tissue density(RTD), representing the classic root economics spectrum(RES). The second strategy was represented by the trade-off between root diameter, mycorrhizal fungi colonization(MF) and SRL, representing the collaboration gradient with “do it yourself” resource uptake ranging from “outsourcing” to mycorrhizal resource uptake. Air temperature regulated species distribution in six ways: directly reducing species importance value;indirectly increasing the species importance value by reducing soil nitrogen content or increasing soil pH by reducing soil moisture inducing absorptive roots to change from “do it yourself” resource absorption to “outsourcing” resource absorption;indirectly decreasing the species importance value by decreasing soil moisture to change from“outsourcing”resource absorption to “do it yourself” resource absorption;indirectly increasing the species importance value with increasing soil pH by reducing soil moisture resulting in absorptive root traits turning into nutrient foraging traits;and indirectly decreasing the species importance value by promoting absorptive root traits to nutrient conservation traits.Conclusions: Absorptive root traits play a crucial role in the regulation of species distribution through multiapproaches of air temperature.
文摘A new method is presented for getting the general thermal response factors and z-transfer functioncoefficients of a room by synthesizing them from the thermal response factors of different parts of the thermalinsulation structure. How to use the general thermal response factors and z-transfer function coefficients toca1culate the indoor air temperature variation directly is also studied. It is shown through practical use that it iseasy to program with the methods presented in this paper and the calculated results are reliable.
基金supported by the National Key Technologies R&D Program (Grant No. 2018YFB1106000)Innovation Funds of China Academy of Launch Vehicle Technology (CALT) for Universities (Grant No.CALT201709)Tsinghua Grants for Autonomous Research。
文摘Wire arc additive manufacture(WAAM) is a new technique to fabricate large-scale complex aluminum alloy components.However, the performance of the parts is critically influenced by residual stresses and deformation. A sequentially thermal-mechanical coupled model of residual stress and deformation for aluminum alloy WAAM parts was established based on commercial FE software ABAQUS. The temperature field was calculated by the moving heat source(MHS) method. The temperature function was obtained according to the distribution of the peak temperature. Furthermore, the MHS method and segmented temperature function(STF) method were used to calculate the residual stress and deformation. The results show that the STF method satisfies both the efficiency and accuracy requirements. 1-segment, 3-segment, and 5-segment STF methods can shorten the time for mechanical analysis by 91%, 79%, 63%, respectively.The error of the residual stress and deformation are all less than 20%. STF method provides an effective way to predict the residual stress and deformation of large-scale WAAM parts.
基金Projects(2012zzts019,2012QNZT048)supported by the Fundamental Research Funds for the Central Universities of Central South University,ChinaProject(201306370121)supported by the State Scholarship Fund of China+3 种基金Project(JT20090898002)supported by Traffic Technology Fund of Hainan Province,ChinaProject(2012M521563)supported by the China Postdoctoral Science FoundationProject(51248006)supported by The National Natural Science Foundation of ChinaProject(511114)supported by the Natural Science Foundation of Hainan Province,China
文摘In order to simplify the boundary conditions of pavement temperature field,the "Environment-Surface" system which considered the natural environment and pavement surface was established.Based on this system,the partial differential equations of the one-dimensional heat conduction in the pavement were established on the basis of the heat transfer theory.Furthermore,the function forms of the initial and boundary conditions of the equations were created through the field experiments.The general solution of the pavement one-dimensional heat conduction partial differential equations was acquired by using Green's function,and the explicit expression of pavement temperature field under specific constraint conditions was derived.For the purpose of analysis,the pavement temperatures in different seasons were calculated using the explicit expression of pavement temperature field,and the calculation accuracy was analyzed through the comparison between measured and calculated values.Then,the relationship between fitting accuracy and calculation accuracy of pavement temperatures was analyzed.The analysis results show that: the usage of "Environment-Surface" system simplifies the calculation of pavement temperature field; the relative error between calculated and measured values is generally less than 7% and is seldom influenced by seasons; there is a positive correlation between the calculation accuracy and the fitting accuracy of pavement surface temperature; high fitting accuracy would result in less error of pavement temperature prediction.
基金supported by the National Natural Science Foundation of China(Grant No.51876194,U1909216)the China Petrochemical Corporation Research Project(318023-2)the Zhejiang Public Welfare Technology Research Project(LGG20F030007)。
文摘The air cooler is an important equipment in the petroleum refining industry.Ammonium chloride(NH4 Cl)deposition-induced corrosion is one of its main failure forms.In this study,the ammonium salt crystallization temperature is chosen as the key decision variable of NH4 Cl deposition-induced corrosion through in-depth mechanism research and experimental analysis.The functional link neural network(FLNN)is adopted as the basic algorithm for modeling because of its advantages in dealing with non-linear problems and its fast-computational ability.A hybrid FLNN attached to a small norm is built to improve the generalization performance of the model.Then,the trained model is used to predict the NH4 Cl salt crystallization temperature in the air cooler of a sour water stripper plant.Experimental results show the proposed improved FLNN algorithm can achieve better generalization performance than the PLS,the back propagation neural network,and the conventional FLNN models.
文摘The finite element method (FEM) and the boundary element method (BEM) are often adopted. However, they are not convenient to spatially vary thermal properties of functionally graded material (FGM). Therefore, the method of lines (MOL) is introduced to solve the temperature field of FGM. The basic idea of the method is to semi-discretize the governing equation into a system of ordinary differential equations (ODEs) defined on discrete lines by means of the finite difference method. The temperature field of FGM can be obtained by solving the ODEs. The functions of thermal properties are directly embodied in these equations and these properties are not discretized in the domain. Thus, difficulty of FEM and BEM is overcome by the method. As a numerical example, the temperature field of a plane problem is analyzed for FGMs through varying thermal conductivity coefficient by the MOL.
基金Project supported by the Autonomous Innovation Fund,China (Grant Nos.0109012922 and 0109012926)the Youth Foundation of Department of Education of Hubei Province,China (Grant No.Q20101602)
文摘Effects of electron temperature on dielectric function and localization of laser beams in underdense collisional plasmas are investigated. Simulation results show that the electron temperature has a strong effect on the dielectric constant and the laser beam localization. It is observed that due to the influence of the electron temperature, the dielectric function presents some interesting and complicated nonlinear variations, and gives rise to the laser beam lo- calization. Moreover, the amplitudes of the beam width and the beam intensity are subjected to continuously oscillatory variation in the region of localization. In addition, the effects of several parameters on the dielectric function and the beam localization are discussed.
基金supported by the National Program on Key Basic Research Projects of China(Grant Nos.2010CB951604 and 2010CB28402)
文摘A new static microwave sounding unit (MSU) channel 4 weighting function is obtained from using Coupled Model Inter-comparison Project, Phase 5 (CMIP5) historical multimodel simulations as inputs into the fast Radiative Transfer Model for TOVS (RTTOV v10). For the same CMIP5 model simulations, it is demonstrated that the computed MSU channel 4 brightness temperature (T4) trends in the lower stratosphere over both the globe and the tropics using the proposed weighting function are equivalent to those calculated by RTTOV, but show more cooling than those computed using the traditional UAH (University of Alabama at Huntsville) or RSS (Remote Sensing Systems in Santa Rosa, California) static weighting functions. The new static weighting function not only reduces the computational cost, but also reveals reasons why trends using a radiative transfer model are different from those using a traditional static weighting function. This study also shows that CMIP5 model simulated T4 trends using the traditional UAH or RSS static weighting functions show less cooling than satellite observations over the globe and the tropics. Although not completely removed, this difference can be reduced using the proposed weighting function to some extent, especially over the tropics. This work aims to explore the reasons for the trend differences and to see to what extent they are related to the inaccurate weighting functions. This would also help distinguish other sources for trend errors and thus better understand the climate change in the lower stratosphere.
文摘A functional integral approach (FIA) is introduced to calculate the transition temperature of a uniform imperfect Bose gas. With this approach we find that the transition temperature is higher than that of the corresponding ideal gas. We obtain the expression of the transition temperature shift as , where n is the density of particle number and a is the scattering length. The result has never been reported in the literature.
文摘In this study, the sliced functional time series (SFTS) model is applied to the Global, Northern and Southern temperature anomalies. We obtained the combined land-surface air and sea-surface water temperature from Goddard Institute for Space Studies (GISS), NASA. The data are available for Global mean, Northern Hemisphere mean and Southern Hemisphere means (monthly, quarterly and annual) since 1880 to present (updated through March 2019). We analyze the global surface temperature change, compare alternative analyses, and address the questions about the reality of global warming. We detected the outliers during the last century not only in global temperature series but also in northern and southern hemisphere series. The forecasts for the next twenty years are obtained using SFTS models. These forecasts are compared with ARIMA, Random Walk with drift and Exponential Smoothing State Space (ETS) models. The comparison is made on the basis of root mean square error (RMSE), mean absolute percentage error (MAPE) and the length of prediction intervals.
基金Acknowledgments The research was financially supported by the National Natural Science Foundation of China (Grant No. 11402309) and the Science Foundation of China University of Petroleum, Beijing (No. YJRC-2013-32).
文摘The free vibration characteristics of functionally graded micro-switches under combined electrostatic, axial residual stress and temperature change is investigated, with an emphasis on the effect of geometric nonlinear deformation due to mid-plane stretching, the influence of volume fraction profile parameter and temperature change. The micro-switch considered in this study is made of either homogeneous material or non-homogeneous functionally graded material with two material phases. Taking the temperature-dependency of the effective material properties into consideration, the Voigt model is used to simulate the material properties of the FGMs (functionally graded materials). The principle of virtual work is used to derive the nonlinear governing differential equation. The eigenvalue problem which describes free vibration of the micro-beam at its statically deflected state is then solved using DQM (differential quadrature method). The natural frequencies of clamped-clamped micro-switches are obtained. The solutions are validated through direct comparisons with experimental results reported in previous studies. A parametric study is conducted to show the effects of geometric nonlinearity, material composition, temperature change and geometrical parameters for the natural frequencies.