Combined Effects Of Temperature Research Articles

Characterization and analysis of high‐entropy boride ceramics sintered at low temperature

AbstractMulticomponent transition metal boride composite–sintered bodies were prepared by spark plasma sintering, and the composite sintered bodies prepared at different sintering temperatures (1500–1900°C) were characterized. The experimental results showed that several other compounds diffused into the TiBx phase at lower sintering temperatures under the combined effect of temperature and pressure due to the nonstoichiometric ratio of TiB1.5 vacancies. When the temperature reached 1900°C, only the hexagonal phase remained. With the continuous increase of sintering temperature, the Vickers hardness and fracture toughness of the sintered bodies had a trend of increasing first and then decreasing, due to the continuous reduction of the porosity of the cross section of the sintered bodies and the growth of the grain size. The Vickers hardness and fracture toughness of sintered body obtained at 1800°C are the best, which are 24.4 ± 1.8 GPa and 5.9 ± 0.2 MPa m1/2. At 1900°C, the sintered body was a single‐phase hexagonal high‐entropy diboride. Its Vickers hardness and fracture toughness were 21.9 ± 1.5 GPa and 5.4 ± 0.2 MPa m1/2, respectively; it showed a clear downward trend.

Solar radiation, temperature and the reproductive biology of the coral Lobactis scutaria in a changing climate

Coral reefs worldwide are at risk due to climate change. Coral bleaching is becoming increasingly common and corals that survive bleaching events can suffer from temporary reproductive failure for several years. While water temperature is a key driver in causing coral bleaching, other environmental factors are involved, such as solar radiation. We investigated the individual and combined effects of temperature, photosynthetically active radiation (PAR), and ultraviolet radiation (UVR) on the spawning patterns and reproductive physiology of the Hawaiian mushroom coral Lobactis scutaria, using long-term experiments in aquaria. We examined effects on spawning timing, fertilisation success, and gamete physiology. Both warmer temperatures and filtering UVR altered the timing of spawning. Warmer temperatures caused a drop in fertilisation success. Warmer temperatures and higher PAR both negatively affected sperm and egg physiology. These results are concerning for the mushroom coral L. scutaria and similar reproductive data are urgently needed to predict future reproductive trends in other species. Nonetheless, thermal stress from global climate change will need to be adequately addressed to ensure the survival of reef-building corals in their natural environment throughout the next century and beyond. Until then, reproduction is likely to be increasingly impaired in a growing number of coral species.

A nonparametric analysis of climate change nexus on agricultural productivity in Africa: implications on food security

Abstract Earlier research largely ignored the effects of climate change on the growth of agricultural total factor productivity (TFP) in Africa. This study shows how climate inputs impact TFP growth in addition to other productivity growth indicators and metrics, as well as how they can impact overall input efficiency as productivity drivers. We use a panel of 42 African nations from 1999 to 2019 and a nonparametric data envelopment analysis-Malmquist technique. The non-parametric analysis revealed that the average growth rate of the non-climate-induced TFP estimates was 1.9%, while the average growth rate of the climate-induced TFP estimates was 2.4%. Accounting for temperature and precipitation separately, TFP grew by 2.3% on average. This growth rate (2.3%) is slightly less than the combined effect of temperature and precipitation (2.4%) but higher than the typical TFP growth rate (1.9%) that ignores climate variables, indicating that TFP growth in African agriculture risks being underestimated when climate inputs are ignored. We also find the distribution of the climate effects to vary across regions. In northern Africa, for example, the temperature-induced TFP growth rates were negative due to rising temperature in the region. Evidence from the decomposed TFP estimates indicates that climate variables also influence productivity determinants. However, technology improvement is fundamental to mitigating the effects of extreme weather inputs on TFP growth in Africa's agriculture. As a result, a few policy suggestions are provided to help policymakers deal with the effects of climate change on TFP growth in Africa's agriculture and ensure food security. The study advocated for a reevaluation of the climate–agriculture effect in order to fully comprehend the role of climate factors and their contributions to agricultural TFP growth in Africa.

Study on the thermal response of spiral energy piles based on field test

Field tests of spiral energy piles under the combined effect of temperature and loading are relatively few. Based on the field test, the heat transfer efficiency, pile strain, axial force and shaft friction of two spiral energy piles were studied. The major findings of the experimental studies were: First, when the double spiral energy pile was heated, the temperature distribution was more uniform; the total heat transfer and the heat transfer rate were higher than those of the single spiral energy pile. Second, the pile strain distribution was such that smaller values were noticed at both pile ends while larger values were in the middle part of the pile. The additional tensile stresses of the two piles generated during cooling reached 4.06 MPa and 4.75 MPa, which exceeded the tensile strength of concrete. Finally, during heating, the shaft friction was negative in the middle and upper pile and positive in the middle and lower pile. The single spiral energy pile showed two neutral points. The downward load generated by the single spiral energy pile was about 885 kN higher than that generated by the double one. The aforementioned changes should be focused on in the actual project.

Experimental investigation of fountains in homogeneous fluid with coexistent temperature and concentration effects using PIV/PLIF

Fountains formed due to the injection into homogeneous fluids with the combined effect of temperature and concentration occur widely in nature and in environmental improvement and industrial applications such as brine water discharge, living sewage disposal, release of waste hot gases into the atmosphere from chimneys, solar desalination discharge, and sewage wastewater discharge for agriculture irrigation. In this study, the behavior of round fountains with salt water as a homogeneous ambient fluid in a transparent glass tank over 0.25 ≤ FrT ≤ 2.0, 0 ≤ N ≤ 5.0, and 47 ≤ Re ≤ 824 was studied using particle image velocimetry/planar laser-induced fluorescence (PIV/PLIF). The recorded PIV/PLIF images provide a better understanding of the transient behavior and intrinsic laws of buoyant jets in an ambient fluid and optimally use their transport mechanisms and entrainment characteristics in environmental improvement and industrial applications. Scaling for the initial maximum fountain height at the development stage, the obtained scaling correlation from the experimental results is consistent with previous results from direct numerical simulation results.

Soil Carbon Fluxes and Sensitivity Analysis – A Study in Pinus roxburghii Forest

The predicted increasing atmospheric carbon dioxide (CO2) level is responsive to altering the future climate, and a small change in the soil carbon may significantly affect the forest carbon cycle and climate system. Soil respiration (SR) and its influencing factors like soil temperature (ST), soil water content (SWC) and surface litter-fall were measured monthly over one year in a sub-tropical Pine (Pinus roxburghii) forest of Bhaktapur district located in central Nepal to determine the SR of the forest and, its variations and sensitivity. The results showed that SR varied to the changes in ST by an exponential significant positive correlation between them. The optimum SR was observed between 10 and 22ºC, and the highest SR were obtained above ST at 20ºC. The temperature sensitivity value of SR (Q10) was estimated at Q10 = 2.13. The significant exponential curve represented the effect of SWC on SR. The higher SR rate was mostly measured between 10 and 25% SWC. The monthly and seasonal variations of the SR rate were consistent with the ST, SWC and litter-fall variations. The study showed that the combined effect of temperature and precipitation might be the major cause of SR variations; however, ST is adequate for increasing SR. Hence, the warming further enhances carbon emission from the forest floor and inversely increases carbon to contribute to climatic change through this pine-dominated forest stand structure.

The combined effects of temperature and salinity on the digestion and respiration metabolism of Pinctada fucata

The combined effects of temperature and salinity on the digestion and respiration metabolism of Pinctada fucata were evaluated via response surface methodology and box-benhnken design under laboratory condition. Results indicated that the primary and secondary effects of salinity and temperature had significant effects on amylase (AMS) of P. fucata (P < 0.05)., The digestive enzyme reached the maximum activity when temperature was 26 °C. The AMS and trypsin (TRYP) increased at first, and then decreased with increasing temperature. The Lipase (LPS) was positively correlated with either salinity or temperature. Salinity had no significant effect on TRYP as a primary effect (P > 0.05), but had a significant effect on TRYP as a secondary effect (P < 0.01). These effects were completely opposite to the effect of temperature on pepsin (PEP) as primary and secondary effects. The combined effects of salinity and temperature on AMS, TRYP and PEP were significant (P < 0.01), but had no significant effect on LPS (P > 0.05). The primary, secondary and interaction effects of salinity had significant effects on NKA (Na+-K+-ATPase) of P. fucata (P < 0.05), and NKA presented a U-shaped distribution with increasing salinity. The quadratic and interactive effects of temperature had a significant effect on AKP (P < 0.05), and AKP showed a U-shaped distribution with increasing temperature. Lactate dehydrogenase (LDH) activity decreased at first, and then increased when temperature and salinity changed from 20 to 30 °C and 23–33 ‰, respectively. The expression of GPX gene affected by temperature in gills may be delayed compared with that in hepatopancreas, and its expression is tissue-specific. The appropriate digestion and respiratory metabolism index models were established under the combined temperature and salinity conditions. The optimization results showed that the optimal combination of temperature and salinity was 26.288 °C/28.272‰. The desirability was 0.832. Results from the present study will provide a theoretical reference for shellfish culture affected by environmental interactions and the establishment of related index models.

Multi-parametric analysis of the CVD of CNTs: Effect of reaction temperature, pressure and acetylene flow rate

The effect of process parameters (temperature, pressure and acetylene flow) during the chemical vapor deposition of carbon nanotubes (CNTs) on the final product are computationally investigated after having established a mechanism for the deposition of CNTs. The results are consistent with experimental measurements for the same process. It is found that temperature, pressure and acetylene flow rate affect the mechanisms that limit the catalyst deactivation and thus, the CNT growth. The combined effect of temperature with pressure and acetylene flow rate is investigated mechanistically, by identifying the mechanisms responsible for the effect of process parameters, for the first time. The influence of these key-parameters on the deposition uniformity along the wafer area is also investigated. The study findings illustrate the importance of carefully adjusting the process parameters during the process engineering for the CVD of CNTs which can in turn result in a knowledge-based redesign or scale-up of the process.

Electrochemical conversion of CO2 to formic acid using a Sn based cathode: Combined effect of temperature and pressure

Electrochemical conversion of CO2 in the aqueous electrolyte into value-added chemicals is considered one of the most promising strategies to valorize waste-CO2. In the last decade, high attention was focused on the electrochemical synthesis of formic acid (FA) via CO2 reduction using Sn cathodes. To improve the final concentration of FA in aqueous electrolytes, several approaches, including the utilization of different technologies (i.e. pressurized CO2 reactor, a gas diffusion electrode, divided cell etc…) and different operative conditions (i.e. pH, current densities, temperature, mixing rate, etc...) were investigated in detail. To date, the effect of temperature (T) on the electrochemical conversion of CO2 into FA under pressurized undivided cells is still unexplored. Hence, in this work, the simultaneous effect of CO2 pressure (PCO2) (1 ÷ 3 bar) and T (3 ÷ 60 °C) on the electrochemical synthesis of FA in an aqueous electrolyte using a Sn cathode was studied in detail. It was found that the adoption of low T and high PCO2 values allows to work at high current densities (j) by achieving high final concentrations of FA ([FA]) and good relative faradaic efficiency (FEFA). As an example, a quite high final [FA] of approximately 360 mM coupled with a FEFA higher than 50% was reached in an aqueous electrolyte by working at T of 10 °C, j of − 75 mA cm−2 and PCO2 of 30 bar.

Effect of Temperature and Wind Speed on Efficiency of Five Photovoltaic Module Technologies for Different Climatic Zones

The objective of this study is to investigate the effect of temperature and wind speed on the performance of five photovoltaic (PV) module technologies for different climatic zones of Pakistan. The PV module technologies selected were mono-crystalline silicon (MC); poly-crystalline silicon (PC); heterogeneous intrinsic thin-film (TFH); copper–indium–allium–selenide (TFC); and thin-film amorphous silicon (TFA). The module temperature and actual efficiency were calculated using measured data for one year. The actual efficiency of MC, PC, TFH, TFC, and TFA decreases by 3.4, 3.1, 2.2, 3.7, and 2.7%, respectively, considering the effect of temperature only. The actual efficiency of MC, PC, TFH, TFC, and TFA increases by 9.7, 9.0, 6.5, 9.5, and 7.0% considering the effect of both temperature and wind speed. The TFH module is the most efficient (20.76%) and TFC is the least efficient (16.79%) among the five materials. Under the effect of temperature, the actual efficiency of TFH is the least affected while the efficiency of TFC is the most affected. The actual efficiency of MC is the most affected and that of TFH is the least affected under the combined effect of wind speed and temperature. The performance ratio of TFC is the most affected and that of TFH is the least affected under the effect of temperature and the combined effect of temperature and wind speed. The performance of PV technology, under real outdoor conditions, does not remain the same due to environmental stresses (solar irradiance, ambient temperature, and wind speed). This study plays an important role in quantifying the long-term behavior of PV modules in the field, hence identifying specific technology for the PV industry in suitable climatic conditions.

Combined effects of temperature and humidity on the interaction between tomato and Botrytis cinerea revealed by integration of histological characteristics and transcriptome sequencing.

The environment significantly impacts the interaction between plants and pathogens, thus remarkably affecting crop disease occurrence. However, the detailed combined mechanisms of temperature and humidity influencing this interaction remain unclear. In this study, the interaction between tomato and Botrytis cinerea in various temperature and humidity conditions was analyzed by histological observation and a dual RNA-seq approach. Results showed that low humidity was not favorable for mycelial growth, resulting in infection failure. Both high and low temperatures at high humidity successfully inhibited pathogenic infection and disease incidence in the tomato plants, thus enhancing their resistance to B. cinerea. The high temperature and high humidity (HH) treatment induced the upregulation of light reaction genes, increased the net photosynthetic rate, and expanded the chloroplast morphology of infected tomatoes. The HH treatment also inhibited the expression of cell cycle-related genes of B. cinerea, interfered with conidial germination and mycelial growth, and damaged mycelial cell structure. Low temperature and high humidity (LH) treatment induced the expression of cell wall modification genes and remodeled the cell wall morphology of tomatoes in response to B. cinerea. In addition, the downregulated fungal catabolic genes and the abnormal increase in electron density of mycelial cells under LH treatment subsequently reduced the infection ability of B. cinerea. These results further explain the coupled effects of temperature and humidity on plant defenses and pathogen virulence, and provide a potential means to control gray mold.

The Time Lag Effect Improves Prediction of the Effects of Climate Change on Vegetation Growth in Southwest China

Climate change is known to significantly affect vegetation development in the terrestrial system. Because Southwest China (SW) is affected by westerly winds and the South and East Asian monsoon, its climates are complex and changeable, and the time lag effect of the vegetation’s response to the climate has been rarely considered, making it difficult to establish a link between the SW region’s climate variables and changes in vegetation growth rate. This study revealed the characteristics of the time lag reaction and the phased changes in the response of vegetation to climate change across the entire SW and the typical climate type core area (CA) using the moving average method and multiple linear model based on the climatic information of CRU TS v. 4.02 from 1982 to 2017 together with the annual maximum (P100), upper quarter quantile (P75), median (P50), lower quarter quantile (P25), minimum (P5), and mean (Mean) from GIMMS NDVI. Generally, under the single and combined effects of temperature and precipitation, taking the time lag effect (annual and interannual delay effect) into account significantly improved the average prediction rates of temperature and precipitation, which increased by 18.48% and 25.32%, respectively. The optimal time delay was 0–4 months when the annual delay was taken into consideration, but it differed when considering the interannual delay, and the delaying effect of precipitation was more significant than that of temperature. Additionally, the response intensity of vegetation to temperature, precipitation, and their interaction was significantly more robust when the annual delay was taken into account than when it was not (p &lt; 0.05), with corresponding multiple correlation coefficients of 0.87 and 0.91, respectively. However, the degree of response to the combined effect of individual effects and climate factors tended to decrease regardless of whether time delay effects were taken into account. A more comprehensive analysis of the effects of climate change on vegetation development dynamics suggested that the best period for synthesizing NDVI annual values might be the P25 period. Our study could provide a new theoretical framework for analyzing, predicting, and evaluating the dynamic response of vegetation growth to climate change.

Quantification of microstructural changes in artichoke by-products by image analysis after high-power ultrasound-assisted extraction of bioactive compounds

Image analysis of optical and scanning electron micrographs was successfully used to quantify the microstructural effect of ultrasound application (at 200 and 335 W/L) in artichoke stem samples during the extraction of phenolic compounds and chlorogenic acid. Three temperatures were evaluated (25, 40, and 60 °C) and ultrasound-assisted extraction was compared with mechanical assisted extraction (100 rpm). The low extraction yields of phenolic compounds and chlorogenic acid at 25 °C with mechanical agitation (3.9% and 0.9%) increased up to 96.7% and 78.5%, respectively, at 60 °C and 335 W/L ultrasonic power density. Breakages in plant tissue increased from 4.3% after extraction by mechanical agitation at 25 °C to 10.7% and 16.7% at 25 °C when US at 200 W/L and 335 W/L were applied, respectively. The combined effect of temperature and ultrasound during extraction promoted cell shrinkage, and thus, an increase in cell number per area, reaching the highest increase (36%) when extraction was performed at 60 °C and 335 W/L. The intensified ultrasonic-assisted extraction process affected the microstructure of the solid, with the magnitude of the effects depending on both the extraction temperature and the ultrasonic power density, which explains the increase in extraction yields.

Combined effect of temperature and a reference toxicant (KCl) on Daphnia middendorffiana (Crustacea, Daphniidae) in a high-mountain lake

Climate change has direct effects on aquatic systems where increased water temperature leads to range shifts and changes in the distribution of aquatic organisms. The effects of climate change on aquatic ecosystems are expected in all biomes, and in Alpine environments in particular. Anthropogenic pressure (e.g., chemical pollution) besides climate change impact on the state and quality of aquatic systems in which climate change and environmental contaminants can interact. To better understand the effect of increases in temperature and environmental pollution on high-mountain lakes, we performed an ecotoxicological assay on Daphnia middendorffiana collected during summer 2021 in a high-mountain lake (Upper Balma Lake, Cottian Alps, 2212 m a.s.L.). Samples were exposed to two temperature values (15 °C and 20 °C), potassium chloride (KCl) as the reference toxicant, and D. magna as the model organism for comparison. Findings showed immobilization after exposure to KCl in both species, but exposure to non-optimal water temperature (20 °C and 15 °C for D. middendorffiana and D. magna, respectively) enhanced this effect. The mean half-maximal effective concentration (EC50; 24 h) for D. middendorffiana was significantly lower than that recorded for D. magna exposed to 20 °C (KCl) (46.9 mg/L vs 255 mg/L). A significantly higher EC50 (273.4 mg/L; 24 h) was recorded for D. middendorffiana exposed to 15 °C (KCl) compared to D. magna (EC50 50.6 mg/L; 24 h). Our findings suggest that the combined effects of temperature and chemical pollution may severely affect the occurrence of D. middendorffiana, which occupies a central position in the food webs of high-mountain lakes in the Alps.

Genome-wide selection signatures reveal widespread synergistic effects of two different stressors in Drosophila melanogaster.

Experimental evolution combined with whole-genome sequencing (evolve and resequence (E&R)) is a powerful approach to study the adaptive architecture of selected traits. Nevertheless, so far the focus has been on the selective response triggered by a single stressor. Building on the highly parallel selection response of founder populations with reduced variation, we evaluated how the presence of a second stressor affects the genomic selection response. After 20 generations of adaptation to laboratory conditions at either 18°C or 29°C, strong genome-wide selection signatures were observed. Only 38% of the selection signatures can be attributed to laboratory adaptation (no difference between temperature regimes). The remaining selection responses are either caused by temperature-specific effects, or reflect the joint effects of temperature and laboratory adaptation (same direction, but the magnitude differs between temperatures). The allele frequency changes resulting from the combined effects of temperature and laboratory adaptation were more extreme in the hot environment for 83% of the affected genomic regions—indicating widespread synergistic effects of the two stressors. We conclude that E&R with reduced genetic variation is a powerful approach to study genome-wide fitness consequences driven by the combined effects of multiple environmental factors.

Combined Effects of Temperature and Salinity on Antioxidants in the Immune System of the Pearl Oyster Pinctada fucata

A water environment can impact many physiological processes of aquatic animals. The antioxidant response of immune system of the pearl oyster to temperature and salinity is of great significance to health. This study analyzed the physiological changes and immune responses under different temperature and salinity levels (temperature: 20, 25, and 30 °C; salinity: 23, 28, and 33‰) in the short term (7 d) in the hepatopancreas and other tissues of 405 pearl oysters. The combined effects of temperature and salinity on antioxidants in the immune system of the pearl oyster were evaluated via response surface methodology and Box–Benhnken design (BBD) under laboratory conditions. The secondary effects of salinity on the activities of glutathione peroxidase (GSH-PX), catalase (CAT), and superoxide dismutase (SOD) were significant, and CAT and SOD showed an inverted U-shaped trend with the increase in salinity. Temperature significantly impacted GSH-PX, CAT, glutathione (GSH), and SOD in primary and secondary effects, and the maximum values of CAT, GSH, and SOD were observed. The phenoloxidase (POX) and alkaline phosphatase (AKP) activities increased with the increasing temperatures. The interaction of temperature and salinity was significant on CAT and SOD, but was not significant on GSH-PX. The interaction between salinity and temperature on AKP was significant, which was contrary to the results of AKP in the hemolymph. The expression levels of antioxidant genes varied between tissues, and the expression levels of different genes in the same tissue were different. Appropriate immunity and antioxidant index models were established under the combined temperature and salinity conditions. The optimal combination of temperature and salinity was 24.95 °C and 28.11‰, respectively, and the desirability was 0.803. This study provides theoretical reference points for the pearl oyster to respond to temperature and salinity changes and can be used to establish an index model for shellfish aquaculture.

Dipole modelling of temperature-dependent magnetic flux leakage

Due to the nonlinear coupling, assessing the direct effect of temperature on magnetic flux leakage (MFL) signal is a complicated task. If temperature induces inner stress, it makes the problem doubly difficult, so few models are available for predicting the MFL signal under this condition. To model the effect of temperature on MFL signal, the temperature-dependent magnetic dipole models are proposed. In the first case, where the direct thermal effect is involved only, the dipole model is improved via the modified temperature-dependent Jiles-Atherton (J-A) model. While in the second case, where the combined effects of temperature and thermal stress are considered, the magnetomechanical J-A parameters are further introduced into the dipole model. The thermal stress distribution around a cylindrical through-hole defect is solved by thermoelastic and solid mechanics theories. The magnetomechanical theory is employed to analyse the stress-dependent magnetisation distribution, the key parameter in the magnetic dipole model. The verified experiments are conducted on an M250-50A non-oriented grain (NO) silicon steel specimen with a cylindrical through-hole defect. And the MFL signals predicted by both proposed models agree with the experimental results. When the direct effect of temperature is involved only, the peak-to-peak amplitude of the MFL signal (MFLpp) presents approximately linear dependence on temperature in the range from −40 °C to 60 °C. In addition, when both temperature and thermal stress are considered, the MFLpp changes as a parabolic function of temperature, this being much more significant than the direct effect. The proposed models can act as effective tools to understand the temperature and thermal stress influences on MFL signals. They are also appropriate to solve the inverse problem of sizing the defects accurately when the temperature is involved.

Insight into the interaction between water and surfactant aerosol particles based on molecular dynamics simulations

The ubiquitous surfactant significantly influences the hygroscopic growth of atmospheric aerosol particles. However, knowledge on the morphology of surfactant particles after the adsorption of water is insufficient. In this study, the interaction between water and particles composed of surface active malonic acid (MA) or adipic acid (AA) are simulated based on the molecular dynamics method. The key point is the combined effect of temperature and water content on the structural properties of particles and the surface propensity of surfactants at the equilibrium state. Results show that demixed structure 1 with the adsorption of water clusters on acid grain, mixed structure and demixed structure 2 with acids coating on water droplet can be observed. With temperature increasing from 160 K to 330 K the surface propensity of MA and AA increases first and then weakens. Near the standard atmospheric temperature (280–330 K), the surface propensity of MA and AA increases with increasing water content and alkyl group, and its sensitivity to temperature and water content varies regularly. Moreover, all surfactants at the particle surface orient their hydrophobic groups toward the gas. These findings improve our insight into the surfactant partitioning and further assist in more accurate prediction of the particle hygroscopic growth.

Temporal Variability of Temperature, Precipitation and Drought Indices in Hyper-Arid Region of Northwest China for the Past 60 Years

The temporal variability and abrupt change analysis of temperature and precipitation in Turpan was investigated and examined based on a monthly data set of temperature, precipitation and drought indices (1960–2019) from three meteorological stations over the study area. The Yamamoto method, Mann–Kendall test, Standardized Precipitation Index (SPI), Standardized Precipitation Evaporation Index (SPEI), and Reconnaissance Drought Index (RDI) were applied to reveal temperature, precipitation and drought indices trends in their annual volumes. The conclusions were as follows: (1) in the past 60 years, the annual average temperature in the Turpan region has increased at a rate of 0.33 °C·(10a)−1. Whereas the temperature has accelerated since the 1980s, the annual average minimum temperature has increased more than the annual average maximum temperature, and the temperature difference between winter and summer has increased since the 1990s. (2) The inter-annual, inter-decadal and normal value changes in precipitation in the Turpan region and its three meteorological stations indicated a decreasing trend during 1960–2019. Though the normal value of summer and autumn precipitation decreased and increased as a whole, the normal values of spring, summer, winter and annual precipitation in the Turpan region displayed downward trends. (3) Abrupt changes in temperature were observed in the mid-1990s, and abrupt changes in precipitation were not obvious. (4) The SPI and RDI responded quickly to precipitation and temperature, and the overall characteristics of dry and wet trend changes were consistent. When the SPEI considered the combined effect of temperature and precipitation, the SPI and SPEI are better correlated, and the SPI and RDI are better correlated than the SPEI and RDI. On the whole, the occurrence of drought has obvious regional and seasonal characteristics. These conclusions not only provide scientific data for sustainable development in Turpan but also offer scientific information to further understand the trends and periodicity of climate change and drought conditions in hyper-arid regions around the world.

A micromechanical model for the temperature dependent tensile strength of cross-ply fiber reinforced polymer composites

The tensile properties of cross-ply fiber reinforced polymer (FRP) composites at different temperatures have been an essential issue of concern. This work established a temperature dependent tensile strength (TDTS) micromechanical model for cross-ply FRP composites according to the Force-Heat Equivalence Energy Density (FHEED) principle and failure analysis. The combined effects of temperature, fiber strength and its scatter, especially the evolution of constituent’ properties and residual thermal stress with temperature on the tensile strength are considered in the model. The predicted results of TDTS by the model realize a reasonable agreement with the available experimental results. Moreover, the influencing factors analysis regarding the evolution of tensile strength with temperature were performed. This study contributes a reliable theoretical model for predicting the TDTS of cross-ply FRP composites, and provides useful insights for strength evolution with temperature and composite strengthening.