Changes In Thermal Conditions Research Articles

Capability of the building-resolving PALM model system to capture micrometeorological characteristics of an urban environment in Vienna, Austria

Understanding and evaluating possible changes in thermal conditions of urban settlements are crucial for risk assessment, adaptation to climate change and sustainable urban development. This study presents the results of a micro-scale measurement campaign conducted in Vienna, Austria, to investigate the effects of natural and artificial surfaces on temperature and humidity variability. The observational data set is used for the evaluation of the newly developed building-resolving urban climate model system PALM. Dragino LHT65 LoRaWAN air temperature and humidity sensors were installed to monitor local-scale variations. On selected summer days, drones equipped with thermal imaging cameras were used to provide hourly surface temperature. The monitoring data show higher temperatures near buildings and overall strong spatial and temporal variations. The model demonstrates the capability to simulate the main thermal characteristics of the study area, although it slightly overestimates temperatures at night. Compared to the measurements, it has a less pronounced spatial variability in air temperature and relative humidity, but a larger one in surface temperature. The analysis confirmed that the urban climate model has the potential to appropriately assess microclimate conditions and therefore, contribute to future-oriented urban planning.

Latest Evolution of the X-Ray Remnant of SN 1987A: Beyond the Inner Ring

Based on our Chandra imaging-spectroscopic observations, we present the latest evolution of the X-ray remnant of SN 1987A. Recent changes in the electron temperatures and volume emission measures suggest that the blast wave in SN 1987A is moving out of the dense inner ring structure, also called the equatorial ring (ER). The 0.5–2.0 keV X-ray light curve shows a linearly declining trend (by ∼4.5% yr−1) between 2016 and 2020 as the blast wave heats the hitherto unknown circumstellar medium (CSM) outside the ER. While the peak X-ray emission in the latest 0.3–8.0 keV image is still within the ER, the radial expansion rate in the 3.0–8.0 keV images suggests an increasing contribution of the X-ray emission from less dense CSM since 2012, at least partly from beyond the ER. It is remarkable that, since 2020, the declining soft X-ray flux has stabilized around ∼7 × 10−12 erg s−1 cm−2, which may signal a contribution from the reverse-shocked outer layers of ejecta as predicted by the three-dimensional magnetohydrodynamic models. In the latest ACIS spectrum of supernova remnant 1987A in 2022 we report a significant detection of the Fe K line at ∼6.7 keV, which may be due to changing thermal conditions of the X-ray emitting CSM and/or the onset of reverse shock interactions with the Fe ejecta.

Poromechanics Modeling Forecasts Production, Analyzes Productivity Decline

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 212200, “Accurate Production Forecasting and Productivity Decline Analysis Using Coupled Full-Field and Near-Wellbore Poromechanics Modeling,” by Yan Li, Bin Wang, and Jiehao Wang, Chevron, et al. The paper has not been peer reviewed. _ Productivity index (PI) decline is caused by different mechanisms in both the wellbore region and the far field. Damage in the wellbore region can be simulated by detailed wellbore modeling. A newly developed full-field and near-wellbore poromechanics coupling scheme is used in the complete paper to model PI degradation against time. Near-wellbore damage and field and well interactions are identified when applying the coupling scheme for a deepwater well. History matching, production forecasting, and safe drawdown limits are derived for operational decisions. Full-Field Reservoir Model and Near-Wellbore Poromechanics Model Coupling Full-field and near-wellbore modeling involves coupling the simulation of a full-field reservoir model with one or more near-wellbore poromechanics models. In the coupled simulation, the full-field reservoir model dictates the changing flow or thermal boundary conditions for the embedded near-wellbore models. Meanwhile, near-wellbore phenomena affect well productivity in the full-field reservoir model, altering the flow and thermal boundary conditions on all near-wellbore models in the same field. While capturing the dynamic interactions between the full-field model and all embedded near-wellbore models is of vital importance, the traditional near-wellbore modeling work flow considers only one-way coupling. This work flow is labor-intensive and lacks the dynamic interplay between the reservoir and near-wellbore models. A novel near-wellbore coupling framework is developed to automate data exchange and capture dynamic interactions between the full-field model and the near-wellbore model. In the full-field reservoir and geomechanics coupling applications, only a reservoir simulator solves reservoir flow and thermal equations and a geomechanics simulator solves solid mechanics equations. The reservoir and geomechanics simulators exchange 3D field data. Because solid mechanics equations are quasistatic, the geomechanics simulator does not take timesteps in full-field coupling. In near-wellbore coupling, however, both reservoir and geomechanics simulators solve reservoir flow and thermal equations. The near-wellbore geomechanics model also may solve solid mechanics or other equations coupled to flow or thermal equations in the near-wellbore model. All physics are included in the near-wellbore model for the coupling. Both field properties (3D) and transient boundary conditions (2D) must be mapped onto the near-wellbore model. It is important to ensure that the full-field and near-wellbore models are consistent. A 3D data-mapping module is developed to map flow and rock properties and initial conditions from the full-field model to the near-wellbore model. During the simulation, the transient pressure/temperature boundary conditions (2D) at the external boundary of the near-wellbore model must be mapped from the full-field model to the near-wellbore model to update transient boundary conditions. The automated data mapping in the coupling scheme eliminates the need for manual mapping of field properties and transient boundary conditions.

A dataset of thermal preferences for Mediterranean demersal and benthic macrofauna

Climate change is swiftly reshaping marine ecosystems, affecting different biological levels. Changes in thermal conditions profoundly influence ectotherms’ growth, behaviour, and functions, making knowledge of species’ thermal preferences (TP) crucial for understanding their responses to ongoing warming. However, obtaining this data is challenging due to limited studies, especially for deep-sea demersal and bottom-dwelling species. Here, we present the MedFaunaTP dataset, a collection of survey-based TPs for 939 Mediterranean species of fish, crustaceans, molluscs, echinoderms, cnidarians, and tunicates calculated using species abundance data obtained from the international bottom-trawl survey in the Mediterranean (MEDITS) and bottom temperature data derived from the Copernicus Monitoring Environment Marine Service. MEDITS estimates are based on species biomass indices from 27587 sampling stations, collected from 1994 to 2020, covering the northern Mediterranean Sea and spanning depths from 10 to 800 m. The MedFaunaTP dataset may serves as a valuable resource for understanding and addressing marine ecosystem ecological, conservation, and management challenges in the context of climate change and associated global warming.

Regime change in northwest Atlantic sea surface temperatures revealed using a quantile approach

Trends in sea surface temperatures (SST) of the US Northeast Continental Shelf and the adjacent Slope Sea were analyzed using a quantile approach. SST through the period 1982–2021 were analyzed for change in annual mean and range. In addition, the mean of each 25% quantile of the data by year was calculated. Using the full time series, the climatological SSTs at each quantile was determined, which in turn were used with the annual data to determine the number of days temperature fell within the limits of each climatological quantile. The time series of the data parameters were summarized by grid location and for a series of representative index areas. The index areas were analyzed for evidence of change points or regime shifts using the STARS (Sequential T-test Analysis of Regime Shifts) algorithm. The widely reported SST warming in this region was reinforced with our analysis; our findings also revealed new aspects of the change of thermal conditions in important ways. Mean annual temperature trended at approximately 0.36 °C per decade; however, warm quantile SSTs increased by more than 1.25 °C per decade in the Slope Sea, representing a five degree increase over the study period. The change point analysis suggested the change in thermal regime began as early as 2005 or 2007 with the study region fully enveloped by regime change by 2012. A previously identified change point in 1999 appears to be related to the duration of warming as opposed to SST levels. Mean SST alone does not capture the nature of high temperature exposure for living marine species in the study area; these regions may be experiencing a month or more of stressfully higher SST. The thermal effects derived using the quantile approach suggest different types of thermal exposures compared to heat wave analyses, especially related to cumulative exposure.

How have thermal conditions changed in different phenological stages of apple (Malus domestica) in Northeastern Hungary?

In temperate climates, most fruit trees need cold weather, low temperatures in winter, and a certain amount of heat during the growing season until harvest. One of the most apparent effects of climate change is the elevated temperature in all seasons of the year. In our study, the changes in thermal conditions have been calculated in Hungary's most significant growing region of apples using the Chill Unit for winters and the Growing Degree Days for summers. The meteorological data were obtained from the gridded dataset of the Hungarian Meteorological Service on a 10 km × 10 km grid, so the whole studied area is well-covered over the last 50 years. The results show that the trees are more exposed to early budding than a few decades ago. Furthermore, the accumulated heat amount in summers has increased drastically, which may increase the heat stress and lead to higher yield losses.

Contemporary Climate Change in Montenegro

Contemporary Climate Change in Montenegro

Decadal Variations in the Meridional Thermal Contrast in East Asia and Its Adjacent Regions: Relative Roles of External Forcing and Internal Variability

Abstract Against the backdrop of global warming, the Eurasian continent and its surrounding areas have experienced ununiform warming in recent decades. Variations in the meridional thermal contrast (MTC) in East Asia and its adjacent regions have a critical influence on the East Asian summer monsoon (EASM); therefore, its forcings were analyzed in this study. The results show that the MTC in East Asia and the surrounding regions showed significant decadal changes during the interval 1960–2014, with a decadal strengthening in the late 1970s and a decadal weakening in the late 1990s. Further investigation showed that internal variability was the dominant control on these two decadal changes of MTC, accounting for 135% and 78.5% of the two observed changes in the 1970s and 1990s, respectively. Based on pacemaker experiments and a method that reconstructs decadal changes in the interdecadal Pacific oscillation (IPO), we found that a positive phase of the IPO tends to cause cooling in the low latitudes and warming in the mid–high latitudes and that a negative phase of the IPO tends to cause warming in the low latitudes and cooling in the mid–high latitudes, which in turn can explain 54.4% and 35.8% of the two internally generated decadal changes in the MTC, respectively. The Atlantic multidecadal oscillation (AMO), when in the same phase as the IPO, exhibits an opposing pattern of surface air temperature. This only had a significant influence in the late 1990s, where it explained 37.9% of the internally generated decadal changes in the MTC. Our findings highlight that internal variability, especially that relating to the IPO and the AMO, should be considered when predicting future changes in thermal conditions in East Asia and its adjacent regions.

Estimation of long-term changes in thermal conditions and distribution of Atlantic and Subarctic water in the XXI Century in the Norwegian Sea on area surveys data

Purpose of the work: assessing the spatial and temporal variability of thermal conditions in waters of various origins in the Norwegian Sea in the first decades of the 21st century. Materials: oceanographic data collected during the International Ecosystem Surveys in the Norwegian Sea in 2000–2021. Methods used: comparative data analysis, descriptive statistics methods, correlation analysis. Results: the “boxes”, temperature in which most fully describes the change in the temperature of the Atlantic and Subarctic waters of the Norwegian Sea, were identified. This is confirmed by the high correlation coefficients of temperature in the “boxes” with the water temperature over a wide area of distribution of waters of various origins. The interannual temperature variability in the “boxes” was studied with the separation of warm and cold periods. An assessment of the interannual variability of the distribution boundaries of the Atlantic and subarctic waters is made by the position of isotherms at different horizons. A statistically significant relationship is shown between changes in the temperature of Atlantic and Subarctic waters according to the “boxes” data and changes in the boundaries of the distribution of water masses and the position of the frontal zone between them. Practical significance: the results of the analysis of in situ data from annual areal surveys make it possible to estimate the interannual variability of the thermal state of waters of various origins in the Norwegian Sea in the absence of standard sections and can be used to predict the distribution of pelagic fish in the sea area depending on oceanographic conditions.

Temperature dependence of optical fiber current sensor with external conversion

The paper presents the research of a optical fiber current sensor with external conversion (OFCS-EC) as a function of temperature. The sensor was developed in the Department of Optoelectronics. The sensor was tested in the temperature range from 23 °C – 80 °C. For each of the temperatures, the sensitivity was determined on the basis of a sinusoidal waveform. Thus, the linearity of the transfer characteristics was checked. The main purpose of the experiment was to check the limits of sensitivity changes in changing thermal conditions and whether the sensor meets the standards used in the power industry. Full Text: PDF References M.J. Weber, "CRC Handbook of Laser Science and Technology. Supplement 2: Optical Materials", CRC Press, Boca Raton, FL, USA (1995). CrossRef S. Ju, Y. Lee, Y.T. Ryu, S.G. Kang, J. Kim, P.R. Watekar, B.H. Kim, Y. Lee, Y.H. An, C.J. Kim, W.T. Han, "Temperature Dependence of Faraday Rotation of Glass Optical Fibers Doped with Quantum Dots of CdSe and CdMnTe", Phys. Status Solidi A, 216: 1800549 (2019). CrossRef E. Lage, L. Beran, A.U. Quindeau, L. Ohnoutek, M. Kucera, R. Antos, S. R. Sani, G.F. Dionne, M. Veis, C.A. Ross; Temperature-dependent Faraday rotation and magnetization reorientation in cerium-substituted yttrium iron garnet thin films. APL Mater. 5, 036104 (2017). CrossRef S. Ju, J. Kim, K. Linganna, P.R. Watekar, S.G. Kang, B.H. Kim, S. Boo, Y. Lee, Y.H. An, C.J. Kim, et al. "Temperature and Vibration Dependence of the Faraday Effect of Gd2O3 NPs-Doped Alumino-Silicate Glass Optical Fiber". Sensors, 18, 988 (2018). CrossRef A. Jeffrey, D. and R.M. Bunch, "Temperature dependence of the Faraday rotation of Hoya FR-5 glass," Appl. Opt. 23, 633 (1984). CrossRef K. Barczak, J. Juraszek, "Optoelectronic system for detecting short-circuits in low voltage networks", Photon. Lett. Pol, 14, 37 (2022). CrossRef K. Barczak, K. Mazniewski, "Optical fiber current sensor with external conversion for measurements of low AC electric currents", Proc. SPIE, 10455 (2017). CrossRef

Effects of heating rate and shell colour on the cardiac thermal performance in a polymorphic gastropod Batillaria attramentaria

Heating rate has gained extensive attention in mechanistic understanding of physiological responses to changing thermal conditions in the context of climate change. In polymorphic gastropods, differences in the absorption of solar energy between dark- and light-coloured individuals lead to supposable differences in their heating rates and body temperatures in sunshine. In the present study, we examined the effect of heating rate on heart rate (HR) in a polymorphic gastropod Batillaria attramentaria. By using biomimetic models, we found that daily maximum temperature of snails with a dark unbanded shell (D-type morph) was higher than snails with a white line on the upper side of each whorl (UL-type morph) by 0.6 °C when exposed to sunlight, but there was no apparent difference in heating rates between D- and UL-type models. We measured HR of snails at various heating rates from 3.0 to 9.0 °C h−1. Faster heating rates significantly increased maximum thermal tolerance in both D- and UL-type snails, highlighting the importance to have thorough knowledge on the heating rate in the field to obtain accurate maximum thermal limit of gastropods. Critical temperature at which HR precipitously declines was higher in D-type snails than UL-type snails. Our results suggested that the impacts of heating rate as well as the shell colour should be considered to gain a mechanistic understanding of the population dynamics of polymorphic gastropods.

Developmental environments do not affect thermal physiological traits in reptiles: an experimental test and meta-analysis.

On a global scale, organisms face significant challenges due to climate change and anthropogenic disturbance. In many ectotherms, developmental and physiological processes are sensitive to changes in temperature and resources. Developmental plasticity in thermal physiology may provide adaptive advantages to environmental extremes if early environmental conditions are predictive of late-life environments. Here, we conducted a laboratory experiment to test how developmental temperature and maternal resource investment influence thermal physiological traits (critical thermal maximum: CTmax and thermal preference: Tpref) in a common skink (Lampropholis delicata). We then compared our experimental findings more broadly across reptiles (snakes, lizards and turtles) using meta-analysis. In both our experimental study and meta-analysis, we did not find evidence that developmental environments influence CTmax or Tpref. Furthermore, the effects of developmental environments on thermal physiology did not vary by age, taxon or climate zone (temperate/tropical). Overall, the magnitude of developmental plasticity on thermal physiology appears to be limited across reptile taxa suggesting that behavioural or evolutionary processes may be more important. However, there is a paucity of information across most reptile taxa, and a broader focus on thermal performance curves themselves will be critical in understanding the impacts of changing thermal conditions on reptiles in the future.

Reconstructing terrestrial ice sheet retreat dynamics from hummocky topography using multiscale evidence: An example from central Ireland

The research reported here combines high-resolution digital elevation models (DEMs) derived from airborne LiDAR with ground-penetrating radar (GPR) surveys and macro- and micro-scale sedimentological analyses to study the geomorphology and internal structure and composition of ridges and mounds within an area of hummocky topography in the Brosna basin, central Ireland. Our evidence indicates that much of the hummocky topography consists of fragmented mega-scale glacial lineations (MSGLs) indicating a phase of accelerated ice flow, overlain by groups of small ridges composed of subglacially derived till and sediment gravity flow deposits. Subtle differences in ridge morphology indicate they may be multi-genetic and formed both ice-marginally as moraines and subglacially as small ribbed moraine. We interpret MSGL-ridge associations as a subglacial bedform continuum reflecting the evolution from a deforming bed to brittle deformation, due to changing thermal and hydrological conditions at the ice-bed interface during ice sheet retreat. Adjacent glaciofluvial landforms indicate initial en- and supra-glacial meltwater drainage, possibly directly related to changing basal thermal/hydrological characteristics and subglacial ridge formation. Subsequently a subglacial conduit system evolved, and later retreat involved formation of ice-marginal ridges. The partially preserved landsystem reflects formation at a polythermal to active temperate ice marginal zone, rather than the stagnating temperate margin previously assumed for this area. Our work demonstrates the usefulness of hummocky topography in identifying changes in ice sheet bed thermal/hydrological characteristics during deglaciation and the importance of combining multiple evidence strands in reconstructing the processes involved in glacial landform construction.

Trends in Area of Occurrence and Biomass of Fish and Macroinvertebrates on the Northeast U.S. Shelf Ecosystem

AbstractClimate change can affect the habitat of marine species and hence their persistence and adaptation. Trends in area of occurrence and population biomass were examined for 177 fish and macroinvertebrates resident to the Northeast U.S. Continental Shelf ecosystem. Samples of these organisms were taken during a time series of research bottom trawl surveys conducted in the spring and autumn 1976–2019. The occurrence area of each taxon was modeled as the distribution of occurrence probability based on a random forest presence/absence classification model. Following, a population biomass of each taxon was modeled as a minimum swept area estimate, where the ecosystem was stratified biannually based on each taxon's spatial distribution. In both seasons, the sum of occurrence area and biomass across all modeled species increased over the study period. The summation of biomass is problematic since catchability is not known for most species; more importantly, most time series of individual species biomass trended higher. We found that the ratio of biomass to occurrence area, intended as a measure of productivity, showed no change in the autumn and had a weak increasing trend in spring. For the majority of taxa, the rate of change in biomass tracked changes in occurrence area (either positive or negative), but there were cases where the direction of change in biomass was opposite to the direction of change in occurrence area. Thermal conditions in surface waters appear to be a more important driver of occurrence area and biomass change than the change in thermal conditions near the bottom. These findings provide critical insights into the expected changes in ecosystem productivity transpiring with climate change.

The effect of fiber orientation and stacking sequence on carbon/Kevlar/epoxy intraply hybrid composites under dynamic loading conditions

AbstractThis work investigated the thermo‐mechanical behavior of (carbon/Kevlar) intraply hybrid composites. The carbon/Kevlar plies' orientation and sequential arrangement were varied. Carbon and Kevlar composites, as well as five different intraply hybrids (HFRPs) composite such as carbon‐0°/Kevlar‐90°, carbon‐45°/Kevlar‐135°, carbon‐90°/Kevlar‐0°, carbon/Kevlar (inter‐changing layer), and carbon/Kevlar‐45° (inter‐changing layer) composites, and a plain epoxy panel, have been developed. The thermo‐mechanical characteristics of the fabricated composites were estimated using a dynamic automated analyzer under changing mechanical and thermal load conditions. The DMA technique measured the HFRPs composite visco‐elastic parameters by increasing the temperature from 30°C to 150°C at frequencies ranging from 1 to 20 Hz. Flexural test characteristics for neat epoxy, carbon fiber‐reinforced composites, Kevlar fiber‐reinforced composites, and carbon/Kevlar fiber‐reinforced composites were estimated to aid the study. The experimentally measured versus analytically calculated viscoelastic parameters were related. The results revealed that carbon‐90° oriented in warp direction/Kevlar‐0° oriented in weft direction exhibited higher modulus and lower loss tangent followed by carbon/Kevlar plies oriented in alternate layers and carbon/Kevlar plies oriented in inter‐changing layers at 45°. Carbon‐0° introduced in the weft direction/ Kevlar‐90° introduced in the warp direction, and carbon‐45°/Kevlar‐135° exhibited intermediate storage and loss modulus and a moderate loss tangent at the various frequency levels considered in the study.

Recent and projected climate change–induced expansion of Atlantic halibut in the Northwest Atlantic

With the influence of climate change on marine systems expanding, climate adaptation will be fundamental for the future of fisheries management. An exponential increase in Atlantic halibut Hippoglossus hippoglossus landings over the past decade has coincided with warming ocean temperatures. Here, we explore how historical changes in abundance have been linked to changing thermal habitat conditions and project trends with a warming climate under different emissions scenarios. From 1990 to 2018, available thermal habitat increased by 11.6 ± 7.35% and growing degree days have increased by 13.5 ± 7.86 °C·days across the region. With warming, the probability of occurrence is projected to increase up to 20.5% in Canada by 2085 under RCP 8.5 for Atlantic halibut. Our results suggest that shifting patterns of halibut distribution and abundance are linked to thermal conditions and that continued warming will likely continue to enhance habitat conditions, leading to increased abundance in the Canadian range. Collectively, these results illustrate the influence of shifting environmental conditions on population dynamics and emphasize the importance of adaptive management practices in a dynamic future climate.

Distribution and abundance of walleye pollock <i>Theragra chalcogramma</i> in the northwestern Bering Sea in the summer-fall period of 2020 and their interannual variability

Spatial distribution and abundance of walleye pollock are considered for the northwestern Bering Sea in the summer-fall of 2020 on the data of echo-integration trawl-acoustic survey. The pollock aggregated mostly in the shelf areas with positive or close to zero water temperature, with the higher concentration in the high-gradient zones. The densest aggregations (> 300 . 103 pcs./nmi 2 ) were found in the eastern part of the Gulf of Anadyr and at the line between the economic zones of Russia and USA. Characteristic acoustic images and daily distribution of walleye pollock on the survey transects are presented. Spatial and bathymetric differentiation of certain size groups of pollock are revealed. More than 83 % of the fish were counted in the areas with bottom depth of 50–150 m. Immature walleye pollock with the size of 21–37 cm accumulated mainly in the areas with bottom depth of 75–125 m. Interannual dynamics of the size composition and abundance of walleye pollock in the northwestern Bering Sea is considered on the data of trawl-acoustic surveys in 2013–2020. The fluctuations of abundance and distribution are compared with changes of thermal conditions. Significant dependence of the pollock abundance on the mean anomaly of bottom temperature is confirmed (correlation coefficient +0.69): the species biomass was noticeably higher and its distribution was wider in the years with favorable (relatively warm) thermal regime than in cold periods.

Temperature‐mediated transgenerational plasticity influences movement behaviour in the green algae Chlamydomonas reinhardtii

Abstract A prerequisite for the survival and reproduction of organisms is to successfully navigate thermal environmental conditions that unfold over time and space. While effective movement behaviour has been highlighted as a key mechanism by which organisms and populations may persist amidst the backdrop of directional environmental warming, it remains unclear how behavioural plasticity may mediate such effects, particularly across time‐scales that span multiple generations. Here, we examine the capacity for transgenerational plasticity to alter the movement behaviour of the motile green algae Chlamydomonas reinhardtii in response to changes in thermal conditions. We first acclimated C. reinhardtii populations to thermal environments near (25°C), below (12.5°C) or above (37.5°C) the temperature range that maximizes population growth rate. Subsequently, we assayed the micro‐spatial scale movement behaviour of these populations in thermally homogeneous environments across a period of 2 weeks in each respective environment, with the goal of evaluating the influence of thermal history on movement behaviour in a novel thermal environment. Our results indicate that thermal history can mediate the movement patterns of C. reinhardtii individuals for up to 10 generations and that the trajectory by which phenotypes converge on their acclimated values can be highly nonlinear. Subsequently, we demonstrated—using a dispersal assay in spatially variable environments—that thermal acclimation history can additionally alter movement patterns at ecologically relevant scales. Collectively these findings indicate the possibility for transgenerational plasticity to modify behaviour across extended time‐scales and converge on acclimated states via nonlinear trajectories. Understanding the efficacy of behaviour for navigating novel thermal environments, such as environments anticipated amidst environmental warming, may thus require considering past as well as present environmental conditions. Read the free Plain Language Summary for this article on the Journal blog.

Mechanical behavior of thermally-induced shape memory polymer composites thin-wall tube in non-uniform thermal field: Experiments and simulations

Thermally-induced shape memory polymer composites (SMPCs) have the capability to self-deploy when stimulated by a specific temperature. As a basic component of deployable truss structure, SMPCs thin-wall circular tubes will undergo complex non-linear deformation and changing thermal boundary conditions during application. This article aims to research the mechanical behavior of thermally-induced SMPCs thin-wall circular tubes in a non-uniform thermal field. Thermal properties of SMPCs including thermal conductivities and coefficients of thermal expansion are tested as fundamental temperature-dependent parameters. A 500 mm-long SMPCs thin-wall tube is conducted in the flattening-folding-cooling-reheating experiments through a specially manufactured loading apparatus. Combining phase transition theory and Fourier heat conduction, a coupling algorithm is proposed to describe the thermo-mechanical behavior of SMPCs, which is implemented by the user subroutines VUMAT by commercial finite element analysis packages ABAQUS. By comparing the results from the simulation of the non-uniform thermal field, the simulation of the uniform thermal field and experiments, the coupling algorithm is verified, and the effect on SMPCs from the non-uniform thermal field is given.

Experimental study to evaluate soil water retention curve of HYPER clay geosynthetic clay liner

Geosynthetic clay liners are widely used as hydraulic barrier due to their low hydraulic conductivity but bentonite in the liners loses its effectiveness due to significant thermal fluxes by both diurnal and seasonal heating and cooling cycles. Modified sodium carboxy methyl cellulose-based bentonite clay (HYPER clay) has shown better hydraulic performance in both situations. A possible reason for this improved performance of HYPER clay based geosynthetic clay liner is the improvement in the suction under changing thermal conditions. Thus, the relationship between soil suction and moisture content, also called the soil water retention curve, needs to be estimated. Therefore, we investigated the soil-water retention curve of the HYPER clay based geosynthetic clay liner and compared it with the untreated clay based geosynthetic clay liner. The article presents the suction test results on wetting path conducted on geosynthetic clay liner prototypes containing HYPER and untreated clay assessed by the contact filter paper method and the relative humidity sensor. The results showed that the geosynthetic clay liner containing HYPER clay has a high volumetric water content and thus, high water retention compared to untreated bentonite at a given suction value. In other words, the HYPER clay can be considered as a potential alternative to conventional bentonite due to its improved water retention capacity.