Ice Formation Research Articles

Unsteady numerical simulations of aircraft icing based on the dynamic grid method

In this study, an unsteady numerical simulation method based on dynamic grids was established to solve unsteady aircraft icing processes. The dual-time step method was used to achieve the time advancement of the transient airflow and droplets fields. The droplets trajectory was calculated using the Euler method, which incorporates a supercooled large droplets model. The transient evolution of the water film and ice layer on the substrate surface was considered in the icing thermodynamic model. The accuracy of the unsteady method for ice-shape prediction was verified via comparison and analysis of numerical examples. Additionally, the rime and glaze ice formation processes were explored, and the coupling effects of ice horn growth and the air convective heat transfer coefficient, water collection coefficient, and water film flow on the substrate surface were studied. The ice shapes calculated by unsteady and quasi-steady methods were compared. The results indicated that the latter predicts a larger icing range than the former. Moreover, there may be more obvious distinctions between these two methods in predicting glaze ice.

Glacial interglacial variations in the natural iron fertilization during the low sea ice periods along the eastern continental margin of Antarctica

The Southern Ocean sequesters atmospheric CO2 through biological pumps, though its driving factors are debated. Modern productivity is regulated by natural iron fertilization from micronutrient influx through dust, regeneration, and Antarctic glaciers and sea ice melting (ice melt). The productivity along the eastern Antarctic continental margin was low during the last glacial period and gradually increased through the deglacial to Late Holocene, marked by distinct productivity peaks. The micronutrients also varied similarly, with reduced glacial influx and an increase in the Holocene, which may cause productivity peaks. Therefore, the coherence of enhanced productivity and micronutrient influx is considered as enhanced iron fertilization period. The productivity peaks declined within ∼1.5 kyr, mostly due to the Ekman transport and sea ice formation. Along with ice melt, the independent weathering pattern that responds with glacial- interglacial ice volume changes suggest the source of micronutrients is not terrigenous. Shelf interaction of oceanic currents can influence the water column nutrient stock significantly, while its utilization occurs during reduced ice periods (low sea ice and high glacier melting) for productivity. Therefore, enhanced natural iron fertilization periods are considered as ice low periods that occurred in a periodicity of 2 kyrs, at ∼7.5 kyr BP, ∼5.5 kyr BP, ∼4 kyr BP, ∼ 2.5 kyr BP, and ∼0.5 kyr BP, likely due to the combined effects of atmospheric and oceanographic factors driven by the high amplitude regional temperature variability during the mid to late Holocene.

The impact of surface metallization on multilayer carbon nanotubes regarding the operational characteristics of composite electric heaters utilized for anti-icing protection

The design of energy-efficient heating techniques is emerging as a crucial scientific and technical challenge, driven by the growing focus on the advancement of the northern regions of the country, particularly the Arctic. Research in Arctic materials science, which incorporates cutting-edge techniques from various interdisciplinary fields like nanotechnology and electrotechnology, could become a key area of study for the development of these northern regions. The development of an electric heating composite material that utilizes an organosilicon elastomer as the polymer matrix and metallized multilayer carbon nanotubes (MWCNTs) serving as a conductive filler with enhanced resistance to icing enables an efficient electrothermal anti-icing system The paper presents the results of the study of an electric heater based on the wiring of an elastic composite with the effect of temperature self-regulation. For modification of the silicon-organic compound, metallized MWCNTs were used, which increased the sensitivity of heating elements to ice formation. When the ambient temperature decreases, the polymer composite has different values of electrophysical parameters, which create the effect of acceptable electrical heating concerning the ambient temperature. The research results have significant practical value, as the heating elements can have different compositions and can be operated at low temperatures. Heating elements can effectively adjust the heating mode to the ambient temperature conditions, saving electrical energy. The heating time required for the ice to melt is 210 seconds, and the dynamics of the current consumption value correlate with the ambient temperature, reflecting the effect of temperature self-regulation.

Влияние колебаний стока реки Лены на площадь льда в море Лаптевых

The ice regime of the Laptev Sea has significant changes during the last twenty years. After the changes in the ice regime of the Laptev Sea, the influence of river runoff on the processes of seasonal formation and destruction of sea ice have increased. During the period from 2004 to 2022, the average annual ice area in the Laptev Sea has a positive correlation with a fluctuations of Lena runoff. The high-water content years of Lena has stimulated to the speedup of the ice cover formation process in autumn and the shift of the beginning of ice melting in spring to a later date.

Air mass history linked to the development of Arctic mixed-phase clouds

Abstract. Clouds formed during marine cold-air outbreaks (MCAOs) exhibit a distinct transition from stratocumulus decks near the ice edge to broken cumuliform fields further downwind. The mechanisms associated with ice formation are believed to be crucial in driving this transition, yet the factors influencing such formation remain unclear. Through Lagrangian trajectories collocated with satellite data, this study investigates the development of mixed-phase clouds using these outbreaks. Cloud formed in MCAOs are characterized by a swift shift from liquid to ice-containing states, contrasting with non-MCAO clouds also moving off the ice edge. These mixed-phase clouds are predominantly observed at temperatures below −20 °C near the ice edge. However, further into the outbreak, they become dominant at temperatures as high as −13 °C. This shift is consistent with the influence of biological ice-nucleating particles (INPs), which become more prevalent as the air mass ages over the ocean. The evolution of these clouds is closely linked to the history of the air mass, especially the length of time it spends over snow- and ice-covered surfaces – terrains may that be deficient in INPs. This connection also accounts for the observed seasonal variations in the development of Arctic clouds, both within and outside of MCAO events. The findings highlight the importance of understanding both local marine aerosol sources near the ice edge and the overarching INP distribution in the Arctic for modelling of cloud phase in the region.

Rapid drops of ocean temperatures in several shallow bays in Nova Scotia during a recent cold air outbreak

Abstract From February 3-5, 2023 Atlantic Canada experienced an extremecold Arctic air outbreak with high winds that set many local meteor-ological records, including wind chills as low as -47°C. The impacts of the cold air outbreak on ocean temperatures and ice formation are investigated using predictions from the Coastal Ice-Ocean Prediction System for the East Coast of Canada (CIOPS-E), developed by Environment and Climate Change Canada. Observations from moorings further inform the predictions. The analysis suggests that during the event, several shallow bays and coastal areas in Nova Scotia experienced significant, abrupt temperature decreases ranging from 1.0 to 3.9°C. Overall cooling estimated by the model was 2.3°C for nearshore locations where observations recorded an average temperature decrease of 3.0°C. On the other hand, at individual sites the difference between observed and modelled cooling was up to 2.4°C. This difference can be attributed partly to the fact that the model does not adequately resolve the coastline features of some of the nearshore mooring sites. In comparison, we also analyze another cold air outbreak that occurred on December 15-18, 2016, with wind chills as low as -37°C. The ocean temperatures changes associated with this earlier event saw decreases of 0.8 to 3.5°C, potentially contributing to an ongoing fish kill in St. Mary’s Bay (near the mouth of the Bay of Fundy) at the time. Keywords: Ocean temperature, Cold air outbreak, Ocean forecasting, Shallow bays, Nova Scotia

Impact and freezing characteristics of deionized water droplets on cold curved surfaces

Processes involving droplet impact and subsequent freezing occur widely in practical engineering applications. In the present study, a visualization experimental setup is utilized to investigate the effects of the impact of single millimeter-scale droplets on curved surfaces at room and low temperatures. The influences of the Weber number We, wall temperature, and wall wettability on the dynamics of droplet impact and the characteristics of ice formation are examined. The morphological evolution of droplet impact and the variations of the dimensionless spreading coefficient are analyzed. The results indicate that at high We (We = 277), droplets reach their maximum spread on cold walls in a shorter time than on room-temperature walls, and their peak spreading coefficient is smaller. Upon impact with a cold wall, droplets exhibit a spread–splatter behavior. Low temperatures suppress the oscillatory behavior of droplets on a curved wall. In the case of a hydrophilic wall surface, as the impact We increases from 42 to 277, the impact mode gradually transitions from spread–retract–freeze to spread–splatter–freeze. The maximum spreading coefficient first increases and then decreases with increasing impact We. At high We (We = 277), the wall wettability has a minimal effect on the dynamics of droplet impact and freezing, with a spread–splatter–freeze mode being exhibited for both hydrophobic and hydrophilic walls, and the final freezing morphology is similar.

Methodology for selecting optimal wire grade and cross-section based on an integrated technical and economic criterion

The aim was to develop a methodology for selecting an optimal wire grade and cross-section for overhead power lines with a voltage of above 1 kV under intensive development of power grid systems. This aim was solved using the authors’ previously developed methods: selection of an optimal wire grade based on hierarchy analysis and selection of an optimal wire cross-section by optimizing the specific discounted costs during the entire period of construction and operation of overhead power lines. In the present study, these methods are integrated into a single methodology. It is proposed to implement wire inspections prior to the stage of technical and economic calculations, since the necessary data has already been taken into account during the selection of a wire grade and its cross-section. The proposed methodology was tested on a typical example of reconstruction of the Zapadnaya– Davydovka 110 kV overhead line, which creates limitations in the power supply of Primorsky Krai due to insufficient wire capacity and its operation beyond the normative period. SENILEK AT3/C 150/24 wire was selected as a solution for the example under consideration. The application of this wire grade allows not only the overhead line capacity to be increased by 151% without replacing the existing supports, but also active and reactive power losses in the electric network to be reduced by 18.9 and 2.5%, respectively. The proposed methodology enables selection of an optimal grade and cross-section of any wire design, taking the dynamically changing operational conditions of power grid systems into account. The solutions found by the proposed methodology may contribute to a more efficient operation of power lines due to increasing their transmission capacity, reducing the number of used supports, replacing the line wire without replacing supports, decreasing ice formation on wires, and reducing power losses.

Easily Applicable Superhydrophobic Composite Coating with Improved Corrosion Resistance and Delayed Icing Properties

Mitigating the adverse effects of corrosion failure and low-temperature icing on aluminum (Al) alloy materials poses significant research challenges. The facile fabrication of bioinspired superhydrophobic materials offers a promising solution to the issues of corrosion and icing. In this study, we utilized laboratory-collected candle soot (CS), hydrophobic fumed SiO2, and epoxy resin (EP) to create a HF-SiO2@CS@EP superhydrophobic coating on Al alloy surfaces using a spray-coating technique. Various characterization techniques, including contact angle meter, high-speed camera, FE-SEM, EDS, FTIR, and XPS, were employed to investigate surface wettability, morphologies, and chemical compositions. Moreover, a 3.5 wt.% NaCl solution was used as a corrosive medium to evaluate the corrosion resistance of the uncoated and coated samples. The results show that the capacitive arc radius, charge transfer resistance, and low-frequency modulus of the coated Al alloy significantly increased, while the corrosion potential (Ecorr) shifted positively and the corrosion current (Icorr) decreased by two orders of magnitude, indicating improved corrosion resistance. Additionally, an investigation of ice formation on the coated Al alloy at −10 °C revealed that the freezing time was 4.75 times longer and the ice adhesion strength was one-fifth of the uncoated Al alloy substrate, demonstrating superior delayed icing and reduced ice adhesion strength performance.

Changes in freezing parameters and temperature distribution of beef induced by AC electric field: Alleviation on freezing damage and myowater loss

In this study, a specialized experimental device integrating infrared thermal imaging, real-visual photography, and a time-temperature data collector was designed to investigate the effects of alternating electric field (AEF) assisted freezing on the temperature histories and freezing parameters in different layers of beef as well as the freezing damage and myowater loss. The findings revealed distinct differences in the freezing curves (e.g., slope) and parameters (e.g., Tnuc, TF, tptand Fmiz) between the surface, middle, and inner layers of beef cubes under both AEF and traditional freezing conditions. AEF treatment regulated the freezing curves and key parameters of middle and surface layers, influencing ice crystallization. The equivalent ice areas for the surface, middle, and inner samples under AEF treatment were 8.16, 14.40, and 20.56%, respectively, significantly lower than those in traditional freezing (15.87, 24.60, and 28.8%). Compared to traditional freezing, AEF-assisted freezing decreased myofibrillar fragmentation index (MFI) of beef muscle, preserving its texture integrity. AEF treatment inhibited water migration and reduced water-holding capacity (WHC) loss. In conclusion, AEF-assisted freezing changed ice formation characteristics and alleviated freezing damage by regulating the freezing curve traits and parameters.

Kinetic study on the effect of ice nucleation and generation on methane hydrate dissociation below the quadruple point

Natural gas hydrates (NGHs) have captured worldwide attention because of its huge resources and high energy density. Deep depressurization by dropping the pressure below the quadruple point is recognized as a promising exploitation method. However, the impact of ice formation on NGHs dissociation within depressurization is still controversial. Thus, we examine the dissociative behavior of NGHs at low temperature below the quadruple point using a high-pressure reactor. It primarily focuses on how ice formation affects heat and mass transfer, as well as the kinetics of hydrate dissociation. The results indicate that during the hydrate dissociation process, liquid water initially transforms into metastable supercooled water, which then transitions to solid ice under external disturbance. Ice nucleation predominantly occurs in two locations: within the free water phase and on the surface of hydrate particles. A double-edged effect of ice on NGHs dissociation is observed: the latent heat released by ice nucleation and generation could accelerate the hydrate breakdown (positive effect), while the decrease in permeability along with the self-preservation effect from ice formation tends to inhibit the NGHs dissolution (negative effect). In addition, a higher pressure drawdown rate can accelerate both ice nucleation and formation, which in turn shortens the freezing induction time. The increase of water saturation (SA) and the decrease of hydrate saturation (SH) can significantly reduce the mining time and strengthen both the hydrate dissociation rate (QH) and gas production rate (QP). Therefore, hydrate sediments with higher SA or lower SH are more conductive to gas recovery of low-temperature NGHs deposits in permafrost regions.

All-day superhydrophobic photo-thermal and electro-thermal icephobic surfaces based on ZrN/MoSe2 composite

Ice formation on equipment and infrastructure surfaces can lead to severe damage and operational disruptions, necessitating advancements in passive anti-icing technologies to enhance de-icing efficiency. Superhydrophobic materials offer notable improvements, such as minimal water affinity and reduced ice adhesion. However, their practical application is hindered by limited durability and vulnerability to cold and humid conditions. This study presents the development of a micro-nanostructured ZrN/MoSe2 photo-electrothermal superhydrophobic composite coating, which exhibits physical and chemical self-cleaning capabilities both day and night. This innovative coating rapidly heats due to the combined effects of solar absorption and Joule heating. It reaches 89.4 °C in 600 s under simulated sunlight and 81 °C with a 15 V electrical input in 300 s. With a contact angle exceeding 155°, it demonstrates superior self-cleaning abilities. Moreover, the coating retains its exceptional anti-icing and de-icing properties even after exposure to mechanical stress, abrasion, and harsh chemical environments. It can rapidly melt ice from surfaces in just 66 s at −20 °C under one sun, achieving a 76 % efficiency in photo-thermal de-icing. Electro-thermal de-icing tests reveal that the coating can melt ice in 55 s with an 87 % efficiency. These promising features, attributed to the unique properties of ZrN nanoparticles and MoSe2 nanosheets, significantly provide substantial advancements in superhydrophobic coating technologies. They offer the potential for large-scale production and enhanced performance in ice management.

Ice Formation, Exsolution, and Multiphase Equilibria in the Methane–Ethane–Nitrogen System at Titan Surface Conditions

Titan is unique among the icy satellites in that it has a thick atmosphere, stable surficial bodies of liquid, and a precipitation system that promotes interactions between the two. Although Titan’s surface conditions are typically assumed to be above the freezing point temperatures of the major constituent species of the climate system (methane, ethane, and nitrogen), conditions may be sufficiently cool across parts of Titan to allow for ice formation alongside known liquid-vapor phases. In this study, we used Raman spectroscopy, visual inspection, and the CRYOCHEM 2.0 equation of state to map the appearance of first ice and to quantify the amount of nitrogen dissolution into liquid in the methane–ethane–nitrogen system along a 1.5 bar isobaric cooling path in the temperature range 80–95 K. This was with the intent of (1) determining the effects nitrogen has on the phase behaviors of the methane–ethane binary system, and (2) establishing the temperatures and ternary mixing ratios needed for ice formation on Titan’s surface. We found that ethane-rich mixtures enter a three-phase solid–liquid–vapor equilibrium and are characterized by nitrogen-rich exsolution upon freezing and ice that form at the bottom of the sample. With sufficient methane content, the mixtures cross a univariant four-phase solid–liquid–liquid–vapor boundary, which contributes to a distinct isothermal freezing point profile and ice that forms starting at the liquid–liquid interface. Our results generally agree with findings from previous studies of the methane–ethane–nitrogen system and are intended to add to our current understanding of Titan’s geochemical processes.

Seasonal Variability in Baffin Bay

AbstractThree dominant characteristics and underlying dynamics of the seasonal cycle in Baffin Bay are discussed. The study is based on a regional, high‐resolution coupled sea ice‐ocean numerical model that complements our understanding drawn from observations. Subject to forcing from the atmosphere, sea ice, Greenland, and other ocean basins, the ocean circulation exhibits complex seasonal variations that influence Arctic freshwater storage and export. The basin‐scale barotropic circulation is generally stronger (weaker) in summer (winter). The interior recirculation (∼2 Sv) is primarily driven by oscillating along‐topography surface stress. The volume transport along the Baffin Island coast is also influenced by Arctic inflows (∼0.6 Sv) via Smith Sound and Lancaster Sound with maximum (minimum) in June‐August (October‐December). In addition to the barotropic variation, the Baffin Island Current also has changing vertical structure with the upper‐ocean baroclinicity weakened in winter‐spring. It is due to a cross‐shelf circulation associated with spatially variable ice‐ocean stresses that flattens isopycnals. Greenland runoff and sea ice processes dominate buoyancy forcing to Baffin Bay. Opposite to the runoff that freshens the west Greenland shelf, stronger salinification by ice formation compared to freshening by ice melt enables a net densification in the interior of Baffin Bay. Net sea ice formation in the past 30 years contributes to ∼25% of sea ice export via Davis Strait. The seasonal variability in baroclinicity and water mass transformation changes in recent decades based on the simulation.

Narwhal (Monodon monoceros) associations with Greenland summer meltwater release

AbstractClimate change is rapidly transforming the coastal margins of Greenland. At the same time, there is increasing recognition that marine‐terminating glaciers provide unique and critical habitats to ice‐associated top predators. We investigated the connection between a top predator occupying glacial fjord systems in Northwest Greenland and the properties of Atlantic‐origin water and marine‐terminating glaciers through a multiyear interdisciplinary project. Using passive acoustic monitoring, we quantified the summer presence and autumn departure of narwhals (Monodon monoceros) at glacier fronts in Melville Bay and modeled what glacier fjord physical attributes are associated with narwhal occurrence. We found that narwhals are present at glacier fronts after Greenland Ice Sheet peak summer runoff and they remain there during the period when the water column is becoming colder and fresher. Narwhals occupied glacier fronts when ocean temperatures ranged from −0.6 to 0.8°C and salinities between 33.2 and 34.0 psu at around 200 m depth and they departed on their southbound migration between October and November. Narwhals' departure was approximately 4 weeks later in 2019 than in 2018, after an extreme 2019 summer heatwave event that also delayed sea ice formation by 2 months. Our study provides further support for the niche conservative narwhal's preference for cold ocean temperatures. These results may inform projections about how future changes will impact narwhal subpopulations, especially those occupying Greenland glacial fjords.

Robust photothermal anti/de-icing hydrophobic coating based on polydopamine (PDA) composition

The hydrophobic soft coating has low ice adhesion strength and hydrophobic stability in low-temperature and high-humidity environments, which is crucial for preventing ice formation on infrastructure and transportation systems. However, creating mechanically durable hydrophobic soft coatings using simple methods remains challenging. In this study, a high-hardness particle-toughened, self-stratifying organic layer with high photothermal conversion rate was developed to enhance coating durability and ice-repellent performance. By optimizing the ratio of dopamine (DA) and sodium alginate (SA), a hydrophobic photothermal agent (DPSn) with high hardness and a significant light-heat effect was synthesized. A durable, hydrophobic photothermal anti-ice coating (AR/20 %PDMS/x%DPS1) with varying DPS1 amounts was successfully created using a straightforward one-step spray method, utilizing the self-stratification characteristics of acrylic resin (AR) and polydimethylsiloxane (PDMS), along with the toughening effect of DPSn. The fiber cross-linked structure of DPS1 achieved a photothermal conversion rate of 87.5 %. Adding 4 wt% DPS1 increased the surface temperature of the AR/20 %PDMS coating to 96.5 ± 2.4 °C and boosted the coating’s adhesion strength from 6.70 ± 0.3 MPa to 7.23 ± 0.7 MPa. The AR/20 %PDMS/4%DPS1 coating demonstrated excellent anti-/de-icing performance after 60 friction cycles, 60 icing/de-icing cycles, and 132 h of acid-base immersion. Its simple preparation process and durable ice-repellent properties make it highly suitable for practical applications in photothermal hydrophobic soft coatings.

Vitreous Tissue Cryopreservation Using a Blood Vessel Model and Cryomacroscopy for Scale-Up Studies: Observations and Mathematical Modeling

Successful long term cryobanking of multicellular tissues and organs at deep subzero temperatures calls for the avoidance of ice cryoinjury by reliance upon ice-free cryopreservation techniques. However, the quality of the cryopreserved material is the direct result of its ability to survive a host of harmful mechanisms, chief among which is overcoming the trifecta effects of ice crystallization, toxicity, and mechanical stress. This study aims at exploring improved conditions to scale-up ice-free cryopreservation by combining DP6 as a base cryoprotective agent (CPA) solution with an array of synthetic ice modulators (SIMs). This study is conducted by integrating cryomacroscopy techniques, thermal modeling, solid mechanics analysis, and viability and contractility investigation to correlate physical effects, thermal outcomes, and cryobiology results. As an extension of previous work, this study aims at scale-up of established baseline blood vessel models, while comparing the relative toxicity and vitreous stability of 4ml and 10ml samples of DP6 containing either sucrose as a SIM, or the commercial synthetic ice blockers (X1000 and Z1000). Using that established protocol, the addition and removal of DP6+0.6M sucrose and DP6+1%X1000+1%Z1000 were both well tolerated in rabbit carotid and pig femoral artery models, when assessed for metabolic recovery and contractility. Using cryomacroscopy, it was demonstrated that DP6+0.6M sucrose provided a stable vitrification medium under marginal cooling and warming conditions that resulted in >50% survival rate. By contrast, DP6+1%X1000+1%Z1000 was subject to visible ice formation during cooling under the same thermal conditions, resulting in a significantly lower recovery of ∼20%. Thermal modeling is used in this study to verify the actual cooling and rewarming rates in the specimens, while thermo-mechanics analysis is used to explain why fractures were observed using cryomacroscopy when the specimens were contained in glass vials but not in plastic vials.

Changes in glacial meltwater system around Amundsen sea Polynya illustrated by radium and oxygen isotopes

The Amundsen Sea Polynya (ASP) is the most biologically productive area around Antarctica due to the input of iron-rich glacial meltwater (GMW). However, the source and path of GMW in the ASP, and how these have changed since the Dotson Ice Shelf (DIS), a primary GMW supplier, began experiencing a cooling period after 2011, remain unclear. This study presents the distribution of GMW in the ASP during the austral summer of 2020. Subsurface GMW proportions were estimated using a composite tracer derived from potential temperature, salinity, and dissolved oxygen, while surface GMW were using 226Ra and 228Ra. The results indicate that GMW in the ASP originates from DIS and Pine Island Bay. Surface GMW upwelled from the melting basal cavity of DIS is transported northwestward by katabatic winds, while subsurface GMW is transported northwestward beneath the mixed layer, with the upper portion upwelling to the surface in the ASP center along isopycnals (σθ) of 27.40 to 27.45 kg/m3. Depth variations of these isopycnals correlate well with brine inventories released by winter sea ice formation, suggesting that sea ice formation influences seawater σθ structures and consequently the transport path of subsurface GMW. Compared to 2011, the GMW content in the ASP in 2020 decreased by nearly half, and the transport routes have also changed. These changes align with the significantly reduced GMW discharge from the DIS after 2012. Our study confirms that the GMW system in the ASP has undergone significant changes following the onset of the cooling period experienced by the DIS.

Aircraft Electrothermal Pulse Deicing

Abstract Ice formation and accumulation on aircraft is a major problem in aviation. Icing is directly responsible for aircraft incidents, limiting the safety of air travel and requiring expensive, and sometimes ineffective deicing strategies. Furthermore, electrification of aircraft platforms leads to difficulties with integration of legacy deicing methods such as pneumatic boots. In this work, we study electrothermal pulse deicing capable of efficient and rapid removal of ice from aircraft wings. The pulse approach enables the efficient melting of a thin (<100 μm) ice layer on the wing surface to limit parasitic heat losses. Only the interface is melted, with the rest of the ice sliding on the melt lubrication layer due to aerodynamic forces. To study pulse deicing, we developed a transient thermal-hydrodynamic numerical model that accounts for multiple phases and materials, specific and latent heating effects, melt layer hydrodynamics, as well as boundary layer effects. To identify optimal deicing strategies, we use our model to study the effects of heater thickness (50 μm < th < 1 mm), substrate electrical insulation thickness (10 μm < ti < 1 mm), pulse duration (0.4 s < Δtpulse < 4.5 s), and pulse energy. Optimum operating points are identified for large (Boeing-747), midsize (Embraer-E175), and small (Cessna-172) aircraft. The scale-dependent thermal-hydraulic model results are used to estimate input conditions required for deicing and integrated into an electrical model considering energy storage, power electronics, integration, and layout, to achieve overall volumetric and gravimetric power density optimization.

Formation and evolution of thermokarst landslides in the Qinghai-Tibet Plateau, China

Thermokarst landslide (TL) activity in the Qinghai-Tibet Plateau (QTP) is intensifying due to climate warming-induced permafrost degradation. However, the mechanisms driving landslide formation and evolution remain poorly understood. This study investigates the spatial distribution, annual frequency, and monthly dynamics of TLs along the Qinghai-Tibet engineering corridor (QTEC), in conjunction with in-situ temperature and rainfall observations, to elucidate the interplay between warming, permafrost degradation, and landslide activity. Through the analysis of high-resolution satellite imagery and field surveys, we identified 1298 landslides along the QTEC between 2016 and 2022, with an additional 386 landslides recorded in a typical landslide-prone sub-area. In 2016, 621 new active-layer detachments (ALDs) were identified, 1.3 times the total historical record. This surge aligned with unprecedented mean annual and August temperatures. The ALDs emerged primarily between late August and early September, coinciding with maximum thaw depth. From 2016 to 2022, 97.8 % of these ALDs evolved into retrogressive thaw slumps (RTSs), identified as active landslides. Landslides typically occur in alpine meadows at moderate altitudes and on gentle northward slopes. The thick ice layer near the permafrost table serves as the material basis for ALD occurrence. Abnormally high temperature significantly increased the active layer thickness (ALT), resulting in melting of the ice layer and formation of a thawed interlayer, which was the direct causing factor for ALD. By altering the local material, micro-topography, and thermal conditions, ALD activity significantly increases RTS susceptibility. Understanding the mechanisms of ALD formation and evolution into RTS provides a theoretical foundation for infrastructure development and disaster mitigation in extreme environments.