Effect Of Ambient Temperature Research Articles

Experimental and simulation studies on the influencing factors of mechanical stimulation threshold of HAN-based liquid propellant

ABSTRACT This paper presents a comprehensive analysis of the effects of water content and ambient temperature on the mechanical stimulation threshold of hydroxylammonium nitrate (HAN) based liquid propellant. Based on the stability analysis of slow cook-off test for HAN-based liquid propellant, the mechanical sensitivity of the liquid propellant with different water content was evaluated at different ambient temperatures in detailed. Differential scanning calorimetry was employed to investigate the influence of water content on the stability, demonstrating a significant dependence on water content. Additionally, the impact sensitivity of liquid propellant, which is strongly influenced by the variation of initiating bond length with the ambient temperature, was investigated using large scale atomic/molecular massively parallel simulator (LAMMPS), highlighting a notable correlation between the impact sensitivity and ambient temperature. The findings of this research contribute towards understanding the hazard level associated with HAN-based liquid propellant, providing crucial guidance for its formulation design, practical application and safety management.

Incremental capacity analysis (dQ/dV) as a tool for analysing the effect of ambient temperature and mechanical clamping on degradation

This work presents a comprehensive degradation study of two types of large lithium-ion pouch cells; 26 NMC532/Graphite (64 Ah) and 9 NMC433/Graphite (31 Ah) pouch cells. The cells were degraded under different cycling conditions and periodically characterized at room temperature. Specifically, the effect of different ambient temperatures and constraining the cells by clamping was studied. Incremental capacity analysis is an in situ, non-invasive characterization technique that allows the identification of battery degradation modes, and is a technique that does not require additional and advanced equipment. Therefore, in this study we also look into applying the analysis technique on an existing data set. This is done by combining incremental capacity analysis on a qualitative level with the tracking of features of interest in the incremental capacity curve as a function of State of Health and utilizing the simulation of different degradation modes for a more in-depth analysis. We combine simulation and experimental incremental capacity analysis with conclusions from capacity loss and resistance changes with a focus on understanding the benefit and limitations of the incremental capacity analysis for large cells. This is important, as incremental capacity analysis is a relatively fast analysis to qualify large commercial batteries for 2nd life applications. Specifically in this study, we found that degradation and capacity loss do not always correlate. For the 64 Ah Cells cycled at 15 °C and 25 °C, the rate of capacity loss appeared to be similar, although the degradation modes and mechanisms are found to be very different. The clamping was the most important factor for impeding degradation. The 31 Ah Cell cycled at low temperatures showed a very poor cycling performance, where the incremental capacity analysis revealed that Loss of Lithium Inventory from fast and irreversible plating was responsible.

Effects of ambient temperature and humidity on viruses activity on different architectural coatings and kinetics study

The inactivation rates of non-encapsulated virus (MS2, φA039, enterovirus EV71) and enveloped virus (influenza A virus H3N2) on architectural coating with different porosity were measured at different temperatures and relative humidity (RH). To study the variation of virus activity on different architectural coating with temperature and humidity and provide reference for the control of indoor building surface virus. The inactivation rate of the virus on different surfaces was analyzed at 15 °C, 25 °C, 35 °C and 45 °C and at RHs of 30 %, 60 %, and 90 % for 12 h or 24 h. Overall, the architectural porous coating is adsorbent to viruses. Under low temperatures and high RH conditions (15 °C, 90 % RH), the viruses can survive longer on the surface of the architectural nonporous (few pores) coating. At low humidity, water can evaporate rapidly on the porous surface, which contributes to virus inactivation, especially for nonenveloped viruses. Architectural porous coating can absorb and retain more water, which reduces the impact of high temperature on the virus under high humidity conditions. The inactivation rate of H3N2 on porous surfaces decreased with the decrease of humidity. In addition, the first-order kinetic and nonlinear Weibull models are used to describe the virus inactivation data. The inactivation of the virus on the surface of the architectural coating and the goodness of fit of the virus inactivation rate is related to the porosity of the architectural coating, temperature, RH, and the type of virus.

Effects of Microhabitat Temperature Variations on the Gut Microbiotas of Free-Living Hibernating Animals.

Variations in ambient temperature (Ta) may significantly influence the gut microbiotas of ectothermic and endothermic animals, affecting fitness. It remains unclear, however, whether temperature fluctuations affect the gut microbial communities of hibernating animals during torpor. To investigate temperature-induced changes in the gut microbiota during hibernation under entirely natural conditions, we took advantage of two adjacent but distinct populations of the least horseshoe bat (Rhinolophus pusillus), which inhabit sites with a similar summer Ta but a different winter Ta. Using 16S rRNA gene high-throughput sequencing, we estimated differences in gut microbial diversity and composition between the hibernating (winter) and active (summer) R. pusillus populations at both sites. During the active period, gut microbiotas did not differ significantly between the two populations, probably due to the similar Tas. However, during hibernation, a higher Ta was associated with decreased α-diversity in the gut microbiome. During hibernation, temperature variation did not significantly affect the relative abundance of Proteobacteria, the dominant phylum at both sites, but marked site-specific differences were detected in the relative abundances of Firmicutes, Actinobacteria, and Tenericutes. In total, 74 amplicon sequence variants (ASVs) were significantly differentially abundant between the hibernating and active bat guts across the two sites; most of these ASVs were associated with the cooler site, and many belonged to pathogenic genera, suggesting that lower ambient temperatures during hibernation may increase the risk of pathogen proliferation in the host gut. Our findings help to clarify the mechanisms underlying the gut microbiota-driven adaptation of hibernating mammals to temperature changes. IMPORTANCE Temperature variations affect gut microbiome diversity and structure in both ectothermic and endothermic animals. Here, we aimed to characterize temperature-induced changes in the gut microbiotas of adjacent natural populations of the least horseshoe bat (Rhinolophus pusillus) which hibernate at different ambient temperatures. We found that the ambient temperature significantly affected the α-diversity, but not the β-diversity, of the gut microbiota. Bats hibernating at cooler temperatures experienced more drastic shifts in gut microbiome structure, with consequent effects on energy-related metabolic pathways. Our results provide novel insights into the effects of ambient temperature on the gut microbiotas of hibernating animals.

High-Precision In Situ Total Alkalinity Analyzer Capable of Month-Long Observations in Seawaters.

Total alkalinity (TA) is an essential variable for the study of physical and biogeochemical processes in coastal and oceanic systems, and TA data obtained at high spatiotemporal resolutions are highly desired. The performance of the current in situ TA analyzers/sensors, including precision, accuracy, and deployment duration, cannot fully meet most research requirements. Here, we report on a novel high-precision in situ analyzer for surface seawater TA (ISA-TA), based on an automated single-point titration with spectrophotometric pH detection, and capable of long-term field observations. The titration was carried out in a circulating loop, where the titrant (a mixture of HCl and bromocresol green) and seawater sample were mixed in a constant volume ratio. The effect of ambient temperature on the TA measurement was corrected with an empirical formula. The weight, height, diameter, and power consumption of ISA-TA were 8.6 kg (in air), 33 cm, 20 cm, and 7.3 W, respectively. A single measurement required ∼7 min of running time, ∼32 mL of seawater, and ∼0.6 mL of titrant. ISA-TA was able to operate continuously in the field for up to 30 days, and its accuracies in the laboratory and field were 0.5 ± 1.7 μmol kg-1 (n = 13) and 10.3 ± 2.8 μmol kg-1 (n = 29) with precisions of 0.6-0.8 μmol kg-1 (n = 51) and 0.2-0.7 μmol kg-1 (n = 8), respectively. This study provides the research community with a new tool to obtain seawater TA data of high temporal resolution.

Effects of ambient temperature and relative humidity on preterm birth during early pregnancy and before parturition in China from 2010 to 2018: a population-based large-sample cohort study.

The progression of global warming and increase in instances of extreme weather have received considerable attention. We conducted a cohort study on women of childbearing age in Yunnan Province, examined the association between ambient temperature and humidity on preterm birth and evaluated the effects of extreme weather during early pregnancy and before parturition on preterm birth. We conducted a population-based cohort study on women of childbearing age 18-49 years who participated in National Free Preconception Health Examination Project (NFPHEP) in Yunnan Province from January 1, 2010, to December 31, 2018. Meteorological data, namely daily average temperature (°C) and daily average relative humidity (%), were obtained from China National Meteorological Information Center. Four exposure windows were explored: 1 week of pregnancy, 4 weeks of pregnancy, 4 weeks before delivery, and 1 week before delivery. We used a Cox proportional hazards model and adjusted the potential risk factors for preterm birth to obtain the effects of exposure to temperature and humidity on preterm birth among the stages of pregnancy. At 1 week of pregnancy and at 4 weeks of pregnancy, the association between temperature and preterm birth was U-shaped. The correlation between relative humidity and the risk of preterm birth was n-type at 1 week of pregnancy. The correlation between preterm birth and temperature and relative humidity at 4 weeks before delivery and at 1 week before delivery is J-shaped. Low temperature and low humidity were protective factors against preterm birth, whereas high temperature and high humidity were risk factors for preterm birth.The effects of high temperature and extremely high temperature were the strongest at 4 weeks before delivery, with HRs of 1.417 (95% CI: 1.362-1.474) and 1.627 (95% CI: 1.537-1.722), respectively. The effects of extremely low humidity and low humidity were strongest at 1 week before delivery, with HRs of 0.681 (95% CI: 0.609-0.761) and 0.696 (95% CI: 0.627-0.771), respectively. Temperature and relative humidity affect preterm birth differently for each pregnancy stage. The effects of meteorological factors on pregnancy outcomes such as premature birth should not be ignored.

The effect of gallic acid on malondialdehyde, hydrogen peroxide and nitric oxide that influence viability of broiler blood cells at high ambient temperatures

ABSTRACT 1. The objective of this study was to measure the effect of gallic acid on levels of ferric reducing antioxidant power, malondialdehyde, hydrogen peroxide, nitric oxide and the viability of broiler blood cells (BBCs) when exposed to high ambient temperature. 2. The BBCs were maintained at 41.5°C (control group, CG) or at ambient temperatures ranging from 41.5°C to 46°C. At 41.5°C to 46°C, BBCs were diluted with gallic acid at 0 (positive control group, PCG), 6.25, 12.5, 25 and 50 µM, respectively. Ferric reducing antioxidant power, malondialdehyde, hydrogen peroxide, nitric oxide and viability of BBCs were investigated. 3. Hydrogen peroxide, malondialdehyde and nitric oxide for the CG was lower than PCG (P < 0.05). However, the viability of CG was higher than PCG (P < 0.05). At 41.5 to 46°C, malondialdehyde, hydrogen peroxide, and nitric oxide of BBCs diluted with gallic acid were lower compared to PCG (P < 0.05). Viability of BBCs diluted with gallic acid was higher than PCG (P < 0.05). 4. These results indicated that gallic acid could reduce the adverse oxidative effects of high ambient temperature on BBCs, with an optimum dilution rate of 12.5 µM.

Large eddy simulation of combustion recession: Effects of ambient temperature and injection pressure

In the present study, large eddy simulation is used to investigate combustion recession for the Engine Combustion Network Spray A flame at two ambient temperatures (850K and 800K) and two injection pressures (100MPa and 50MPa). The present numerical results are able to capture different combustion recession phenomena after the end-of-injection (AEOI). With an injection pressure of 100MPa, the model predicts a “separated” combustion recession at the ambient temperature of 850K and no combustion recession at the ambient temperature of 800K, in which both predictions correspond to the measurements. The combustion recession is mainly controlled by the auto-ignition process at the ambient temperature of 850K. At the ambient temperature of 800K, the local temperature within the fuel-rich region is not high enough to promote the high-temperature ignition process. As time progresses, the mixture within the fuel-rich region rapidly transitions to become an overly fuel-lean mixture, which further hinders high-temperature ignition to occur. Nonetheless, it is shown that lowering the injection pressure to 50MPa causes the combustion recession to occur at the ambient temperature of 800 K. This is likely attributed to the low injection case having a lower air entrainment rate AEOI, which causes the mixtures upstream of the lift-off position to transition slower from fuel-rich to fuel-lean mixtures.

Performance analysis of a hybrid solar-driven cooler for refrigerator vehicle

This study focused on investigating the annual performance of a novel hybrid solar-driven cooling system that can be used on refrigerator vehicles. The cooling system is mainly driven by a DC compressor which is powered by a PV array, while an AC compressor which is powered by the car alternator assists the cooling system when the cooling load is higher than the capacity of the DC compressor. Detailed electrical modeling of the PV panels in the array is performed based on an algorithm that comprises a set of mathematical equations and is validated against the manufacturer's test data. The detailed transient electrical power generation of the PV array is analyzed. The effect of solar irradiation and ambient temperature on the performance of the PV modules is presented. Considering the refrigeration cycle, detailed thermodynamics and heat transfer analysis on the cycle are carried out. The effect of ambient temperature and refrigerator compartment temperature on the performance of the refrigeration cycle is investigated. It is concluded that an increase in ambient temperature decreases the performance of both the PV panel and the refrigeration cycle. While an increase in refrigerator compartment temperature increases the performance of the refrigeration cycle.

PCM-based hybrid thermal management system for photovoltaic modules: A comparative analysis.

Proper temperature regulation of photovoltaic (PV) modules increases their performance. Among various cooling techniques, phase change materials (PCMs) represent an effective thermal management route, thanks to their large latent heat at constant temperatures. Radiative cooling (RC) is also recently explored as a passive option for PV temperature regulation. In this paper, a heat sink (HS), phase change materials, and radiative cooling are integrated with photovoltaic modules to achieve low and uniform temperature distribution along the PV module and improved performance. Eight different combinations are considered for the proposed system, including HS, PCM, and RC, and their various combinations. The PCM is selected according to the environmental conditions ofthe selected location. A comprehensive 2-D model is developed and analyzed in COMSOL-Multiphysics software by solving the governing equations using the finite element method. The performance analysis is carried out for the climatic conditions of the Atacama Desert, having high solar radiation and ambient temperature. The effects of PCM height, ambient temperature, wind velocity, and solar radiation on the performance of the proposed system are studied. The performance of eight different configurations is also compared. The maximum reductions in PV temperature, maximum PV power, and a minimum drop in PV conversion efficiency are observed to be 22oC, 152W, and 14% using a combined heat sink and radiative cooling systems, among all other configurations. The findings of this study can be used to select the best PV cooling method among different configurations.

Multivariate time series short term forecasting using cumulative data of coronavirus.

Coronavirus emerged as a highly contagious, pathogenic virus that severely affects the respiratory system of humans. The epidemic-related data is collected regularly, which machine learning algorithms can employ to comprehend and estimate valuable information. The analysis of the gathered data through time series approaches may assist in developing more accurate forecasting models and strategies to combat the disease. This paper focuses on short-term forecasting of cumulative reported incidences and mortality. Forecasting is conducted utilizing state-of-the-art mathematical and deep learning models for multivariate time series forecasting, including extended susceptible-exposed-infected-recovered (SEIR), long-short-term memory (LSTM), and vector autoregression (VAR). The SEIR model has been extended by integrating additional information such as hospitalization, mortality, vaccination, and quarantine incidences. Extensive experiments have been conducted to compare deep learning and mathematical models that enable us to estimate fatalities and incidences more precisely based on mortality in the eight most affected nations during the time of this research. The metrics like mean absolute error (MAE), root mean square error (RMSE), and mean absolute percentage error (MAPE) are employed to gauge the model's effectiveness. The deep learning model LSTM outperformed all others in terms of forecasting accuracy. Additionally, the study explores the impact of vaccination on reported epidemics and deaths worldwide. Furthermore, the detrimental effects of ambient temperature and relative humidity on pathogenic virus dissemination have been analyzed.

Combined effect of ambient temperature and solar radiation on maned sloths' behaviour and detectability

AbstractChanges in ambient temperature and solar radiation may affect sloths' metabolic rate and body temperature, with consequent changes in activities, postures and microhabitat selection. Although the separate effect of temperature and solar radiation on sloth's behaviour have been previously studied, the combined effect of these climatic factors on behavioural aspects of sloths has never been systematically evaluated in field conditions. Here we evaluated the influence of hourly ambient temperature variation on maned sloth (Bradypus torquatus) activities, postures and tree crown positions, under sunny and cloudy conditions; and tested if any of the animal posture and position increase their exposure to human detection. We performed 350 h of visual observation on eight maned sloths, equipped with radio‐backpacks, in northern Bahia, Brazil, recording their activities, and their resting postures and positions on tree crowns. We also recorded the time taken to visualize the sloths on 58 days to analyse if sloths' detection is affected by posture and position. Higher ambient temperature, within a range of 21–33°C, increased the sloths' activity levels in cloudy conditions but reduced their activity in sunny conditions. Increasing ambient temperature also reduced the frequency of huddled posture and increased the frequency of extended posture and permanence in the inner tree crown. Lastly, the postures and positions did not influence sloths' detectability. Thus, the direction of the temperature–activity relationship depends on climatic conditions (sunny/cloudy), and individuals rely on resting postures and positions to thermoregulate. The warmer and drier future climate, expected to occur in the northern Atlantic Forest, may impose change in the diurnal activity levels and postural pattern for this threatened species, leading maned sloths to reduce its activity on sunny and warmer days and adopting an extended posture.

A pilot study investigating early postmortem interval of rats based on ambient temperature and postmortem interval-related metabolites in blood.

Estimation of the postmortem interval (PMI), especially the early PMI, plays a key role in forensic practice. Although several studies based on metabolomics approaches have presented significant findings for PMI estimation, most did not examine the effects of ambient temperature. In this study, gas chromatography-mass spectrometry (GC‒MS)‒based metabolomics was adopted to explore the changes in metabolites in the cardiac blood of suffocated rats at various ambient temperatures (5°C, 15°C, 25°C, and 35°C) from 0 to 24h after death. Isoleucine, alanine, proline, valine, glycerol, glycerol phosphate, xanthine, and hypoxanthine were found to contribute to PMI in all temperature groups. Hypoxanthine and isoleucine were chosen to establish estimation models (equations) with an interpolation function using PMI as the dependent variable (f(x, y)), relative intensity as the independent variable x, and temperature as the independent variable y. Thereafter, these two models were validated with predictive samples and shown to have potential predictive ability. The findings indicate that isoleucine, alanine, proline, valine, glycerol, glycerol phosphate, xanthine, and hypoxanthine may be significant for PMI estimation at various ambient temperatures. Furthermore, a method to determine PMI based on ambient temperature and PMI-related metabolites was explored, which may provide a basis for future studies and practical applications.

Theoretical and Numerical Study on The Effect of Ambient Temperature Towards Gas Dispersion in Indoor Environment using CFD approach

The usage of harmful chemical gas and natural gas has been increasing rapidly which increase the risk of gas leakage incident to occur especially in the indoor environment. It is important to learn the gas dispersal behavior in order to mitigate the casualty caused by gas leakage. In addition, one of the factors that contribute to the dispersion of gas is temperature. This paper focuses to study the role of ambient temperature toward gas dispersion in an indoor environment by looking at the theoretical and numerical knowledge of gas diffusion's relationship with temperature. Computational Fluid Dynamics (CFD) has been utilized to simulate gas dispersion at different ambient temperature levels in an indoor environment. This study released ethanol vapor to simulate gas dispersion at 5°C, 25°C, and 40°C of ambient temperature to observe the way gas distribute in the indoor environment. Both results from the theoretical calculation and simulation were compared. The result indicates that the gas diffusivity has an increment of 3.5% for every 5°C increment of the temperature. This causes the gas to diffuse rapidly in the warm air compared to the cool air. This paper also finds out that when the initial ambient temperature which is 5°C, was increased to 25°C and 40°C it causes the spread distance of the gas increased by 13.75% and 32.50% respectively.

Effect of Ambient Temperature and Discharge Current on Thermo-Electrochemical Behaviour of Lithium-Ion Cells Using Surrogate Modelling and Analysis

The thermal behaviour of lithium-ion cells plays a critical role in their overall performance and safety. The cell temperature fluctuates during operation due to varying operating conditions, particularly discharge current and ambient temperature. Thus, a precise thermo-electrochemical characterization is imperative for comprehending the behaviour of these cells under a wide range of operating conditions. Through experimental measurements, this study endeavours to determine the dependence of the thermo-electrochemical response of commercial lithium-ion cells as a function of discharge rates and ambient temperatures. High-fidelity reduced-order models are established using surrogate-based techniques to formulate response surfaces for the relevant output parameters, which enables the estimation of these parameters in cases where experiments were not performed. The study reaffirms that an increase in the discharge current rate results in an increase in the temperature difference between the core and surface of the cell. Also, a low ambient temperature has a relatively higher adverse impact on the battery performance, given the same discharge current. Furthermore, sensitivity analysis reveals that cell temperature, discharge capacity, and average discharge energy are more sensitive to ambient temperature than discharge current. On the other hand, the average discharge power is insensitive to ambient temperature and primarily dependent on the discharge current.

Field investigation on geothermal pavements

This article investigates the thermal response of a geothermal pavements located in Adelaide, South Australia. This geothermal pavement field trial is believed to be the first full-scale instrumented system of its kind in the country, and one of the handful around the world to date providing a rare set of experimental data. The ground temperature and weather parameters were monitored for over two years, including during two thermal response tests (TRTs) undertaken under different weather conditions. The annual ground temperature profile under the pavement provides helpful information for geothermal pavements design and model validation. Results revealed the significant impact of weather conditions on the TRTs due to the shallow burial depth of the pipe heat exchanger. To minimise these effects, it is then recommended to perform TRT or thermal performance testing during mid-season. Comparison of test results showed that the effect of ambient temperature was more intensive in summer due to the presence of heat-absorbing asphalt at the surface. In addition, the high amount of absorbed heat at the surface reduced the pavement depth-temperature fluctuations in winter as well as the temperature difference between days and nights, leading to a better performance.

The delayed effect of climatic conditions on pre‐fledging nestling haematocrit in a suboscine species in Patagonia

Haematocrit, the proportion of blood comprising erythrocytes, is often used as a proxy of individual condition. Nestling haematocrit is influenced by several factors but ambient temperature is generally agreed as a key driver. It is unclear which day(s) in embryonic or nestling development are most influential in determining pre‐fledgling haematocrit. This is important, because if we are able to identify what day(s) nestlings are physiologically most vulnerable to climatic conditions, this may inform future conservation management and help mitigate the effects. We investigated the effect of ambient temperature, precipitation, body size, brood size, age, food abundance and habitat on nestling haematocrit in Aphrastura spinicauda (thorn‐tailed rayaditos). We collected this data from two climatically different locations in Chile: northern Patagonia (Pucón) and Sub‐Antarctic Patagonia (Navarino Island), located ~ 1800 km further south. We aimed to identify the key drivers of nestling haematocrit and find when nestlings are physiologically most vulnerable to climatic conditions. We confirm that ambient temperature is the key driver of nestling haematocrit, with increasing ambient temperatures nestling haematocrit decreased. However, precipitation also affected haematocrit in the late incubation stage. At low and high precipitation, nestling haematocrit was low and is optimum in light rainfall. Our results show a delayed effect of ambient temperature and precipitation in late incubation and on the day of hatching which can determine pre‐fledgling haematocrit, which may cause lower post‐fledgling fitness. We found that climatic conditions on the day haematocrit was collected was not important in determining haematocrit. We found that haematocrit was higher in the sub‐Antarctic area and that higher temperatures and precipitation on the day of hatching will result in lower nestling haematocrit and poorer pre‐fledgling condition. As atmospheric temperatures rise, nestling fitness is at risk. This is a threat to many bird species, especially those in locations vulnerable to climate breakdown.

Experimental and Numerical Behavior of Encased Pultruded GFRP Beams under Elevated and Ambient Temperatures

In this research, experimental and numerical studies were carried out to investigate the performance of encased glass-fiber-reinforced polymer (GFRP) beams under fire. The test specimens were divided into two peer groups to be tested under the effect of ambient and elevated temperatures. The first group was statically tested to investigate the monotonic behavior of the specimens. The second group was exposed to fire loading first and then statically tested to explore the residual behavior of the burned specimens. Adding shear connectors and web stiffeners to the GFRP beam was the main parameter in this investigation. Moreover, service loads were applied to the tested beams during the fire. Utilizing shear connectors, web stiffeners, and both enhanced the load-carrying capacities of the encased beams by 100.6%, 97.3%, and 130.8%, respectively. Comparisons between the burned and unburned peer beams were presented with losses in the load-carrying capacity of the burned beams. These losses were the highest in the cases of shear connectors and web stiffeners due to the obtained severe damage, which led to more reductions in the residual behavior of the burned beams. Numerical analyses were performed using the general-purpose finite element (FE) ABAQUS package to conduct a parametric study. The investigated parameters included the effect of the exposure duration and the temperature level. The results of the FE analysis showed good agreement with the experimental results. Additional reductions in the residual capacities of the fire-damaged beams were observed due to exposure to longer fire durations. The improvements in the beam capacities due to using shear connectors and web stiffeners relative to the reference beams under the same exposure time decreased as the exposure duration increased. Furthermore, increasing the temperature to 700 °C, 800 °C, 900 °C, and 950 °C caused reductions in the residual capacities by about 25%, 45%, 70%, and 80%, respectively, for the encased beams in comparison to their peers at ambient temperature.

Effects of Ambient Temperature and State of Galvanized Layer on Corrosion of Galvanized Steel in High-Humidity Neutral Atmosphere.

Galvanized steel is a cost-effective and corrosion-resistant material with high strength, making it a popular choice for various engineering applications. In order to investigate the effects of ambient temperature and galvanized layer state on the corrosion of galvanized steel in a high-humidity neutral atmosphere environment, we placed three types of specimens (Q235 steel, undamaged galvanized steel, damaged galvanized steel) in a neutral atmosphere environment with a humidity of 95% at three different temperatures (50 °C, 70 °C, and 90 °C) for testing. The corrosion behavior of specimens under simulated high-temperature and high-humidity conditions was studied using weight changes, macroscopic and microscopic observations, and analysis of the corrosion products of the specimens before and after corrosion. Emphasis was placed on examining the effects of temperature and damage to the galvanized layer on the corrosion rate of the specimens. The findings indicated that damaged galvanized steel retains good corrosion resistance at 50 °C. However, at 70 °C and 90 °C, the damage to the galvanized layer will accelerate the corrosion of the base metal.

Effect of layer angle and ambient temperature on the mechanical and fracture characteristics of unidirectional 3D printed PLA material

This study aims to investigate the mechanical properties and crack resistance of unidirectional polylactic acid-based 3D printed components. In this regard, the effects of three printing angles (e.g., 0°, 45°, and 90°) and four ambient temperatures (e.g., −20, 0, 20, and 40 °C) on the tensile, flexural, and mode-I fracture characteristics were investigated. Additionally, utilizing theoretical theories appropriate for 3D printed samples as transversely isotropic samples, the results were assessed and expanded. Using the concepts of inlayer and interlayer failure modes in layered samples, the critical printing angle that separates the failure modes were evaluated. Also, failure patterns and the behavior of load-displacement curves were observed and assessed. The results show that an increase in temperature from − 20–40 °C caused tensile strength to decrease by 55–75%. Considering the samples isotropically, the strengths and energies were compared, then considering the anisotropy, inlayer, and interlayer tensile and shear strengths were reviewed. The results show that perpendicularly and transitively printed specimens have tensile strengths that are 4.4 and 2.5 times lower than parallel to loading direction printed specimens. Also, the critical printing angle is calculated as 23–31° based on the test temperature (respecting the load direction).