Search Results (70)

Understanding the climate–weathering coupling mechanisms remains pivotal for interpreting global glacial–interglacial cycles, yet advancements have been constrained by the limited high-resolution sedimentary archives. The newly acquired BXZK2017-2 borehole (30.5 m core) from Bohai Bay provides an exceptional sedimentary sequence to investigate the Late Quaternary climate–weathering interactions. Through an integrated high-resolution chronostratigraphic framework (AMS ¹⁴C and OSL dating) coupled with multi-proxy sedimentological analyses (major element geochemistry and granulometric parameters), we reconstructed the chemical–weathering dynamics in the Bohai coastal region since the Late Pleistocene. Our findings revealed four distinct climate-weathering phases that correlate with the regional paleoenvironmental evolution and global climate perturbations: (1) enhanced weathering during mid-MIS3 to ~37.5 cal kyr BP (Chemical Index of Alteration (CIA): 55.9–62.2), corresponding to regional warming and strengthened summer monsoon circulation; (2) weathering minimum in late MIS3 through early–mid-MIS2 (37.5–14.8 cal kyr BP, CIA < 55), marking the peak aridity before the Last Glacial Maximum; (3) maximum weathering intensity from mid-MIS2 to early MIS1 (14.8–3.34 cal kyr BP, CIA: 65–68), documenting the postglacial humidification driven by the intensified East Asian Summer Monsoon; (4) renewed weathering decline during the Neoglacial (3.34 cal kyr BP-present, CIA: 59–63), coinciding with the late Holocene cooling events. Remarkably, this study identifies a striking synchronicity between the CIA in marine drill cores and δ¹⁸O records derived from Greenland ice cores. Our results indicate that chemical weathering proxies from marginal sea sediments can serve as robust recorders of post-Late Pleistocene climate variability, establishing a new proxy framework for global paleoclimate comparative research. Full article

Hot water drilling is a drilling method that employs high-temperature and high-pressure hot water jetting to achieve ice melting drilling. Characterized by rapid drilling speed and large hole diameter, it is widely used for drilling observation holes in polar ice sheets and ice shelves. Understanding the hole-enlargement process at the bottom of hot water-drilled holes is crucial for rationally designing the structure of hot water drills. However, due to the complexity of heat transfer processes, no suitable theoretical model currently exists to accurately predict this process. To address this, this paper establishes an experimental platform for hot water drilling and conducts 24 sets of experiments under different drilling parameters using visualization techniques. The study reveals the influence mechanisms of drilling speed, hot water flow rate, hot water temperature, downhole drill shape, and nozzle structure on the hole-forming process at the borehole bottom. Experimental results indicate that the primary hole enlargement occurs near the nozzle, achieving 69–81% of the theoretical maximum borehole diameter. The thermal melting efficiency at the borehole bottom is approximately 80%, with about 20% of the input hot water energy heating the surrounding ice. Under identical hot water parameters, jet shapes and drill shapes exhibit minimal impact on borehole geometry. But the improvement of the jet speed and hot water temperature can accelerate the hole-forming process. Full article

This paper presents an ultrasonic sampling penetrator with a staggered-impact mode, which has been developed for the extraction of lunar water ice. A comparison of this penetrator with existing drilling and sampling equipment reveals its effectiveness in minimizing disturbance to the in situ state of lunar water ice. This is due to the interleaved impact penetration sampling method, which preserves the original stratigraphic information of lunar water ice. The ultrasonic sampling penetrator utilizes a single piezoelectric stack to generate the staggered-impact motion required for the sampler. Finite element simulation methods are employed for the structural design, with modal analysis and modal degeneracy carried out. The combined utilization of harmonic response analysis and transient analysis is instrumental in attaining the staggered-impact motion. The design parameters were then used to fabricate a prototype and construct a test platform, and the design’s correctness was verified by the experimental results. In future sampling of lunar water ice at the International Lunar Research Station, the utilization of the ultrasonic sampling penetrator is recommended. Full article

This study aimed to quantify the physical load of defensive pick-and-roll (PnR) actions according to court location (middle or side), defensive option employed (switch, drop/ice, or trap), and effectiveness (successful or unsuccessful) during official basketball games. Twenty-four male basketball players (age: 20.5 ± 1.1 years; stature: 191.5 ± 8.7 cm; body mass: 86.5 ± 11.3 kg; playing experience: 8.5 ± 2.4 years) from two teams competing in the Lithuanian third division were recruited, with data collected across six official games. Participants were monitored using a combination of video-based time–motion analysis (TMA) and inertial measurement units (IMUs), allowing the calculation of duration, PlayerLoad (PL), and PL·min⁻¹ for each of the 364 defensive PnR actions identified. No significant differences were found based on court location or defensive option employed (p > 0.05). By contrast, unsuccessful plays resulted in significantly higher physical loads than successful ones (duration: p < 0.001, ES = 0.46; PL: p < 0.001, ES = 0.41; PL·min⁻¹: p = 0.047, ES = 0.24). Overall, these findings highlight a consistent physical load based on court location and defensive option adopted and an increased physical load when the defensive effort failed. Therefore, basketball coaches are suggested to consider the physical load of different defensive PnR scenarios when planning training drills, defining performance profiles of defensive strategies, and managing team rotations during games. Full article

The sampling and observation of subglacial lakes play a vital role in studying the physical and chemical properties as well as the microbial characteristics of water within these Antarctic subglacial lakes. Compared to existing techniques, such as deep ice core drilling and clean hot water drilling, recoverable autonomous sondes, inspired by the spinning and reeling silk behavior of spiders, offer several advantages, including lightweight design, low power consumption, and minimal external pollution. Over the past six years, Jilin University, with support from the Ministry of Science and Technology of China, has developed an environmentally friendly sampling and observation system for Antarctic subglacial lakes, utilizing a recoverable autonomous sonde. The whole system includes a melting sonde, detection and control unit, scientific load platform, and ice surface auxiliaries. Extensive laboratory and joint system tests were conducted, both on key components and the complete system, including field tests in ice lakes. The results of these tests validated the feasibility of the underlying principles, the long-term reliability of the system operation, and the cleanliness of the drilling process. Ice penetration speed up to 2.14 m/h was reached with 6~6.5 kW melting tip power and a 660 mL lake water sample was collected. The relevant design concepts and technologies of the system are expected to play an important role in the clean detection and sampling of subglacial lakes in Antarctica, Greenland, and other regions. Full article

Summer processes in sea ice and their influence on the ridge action of structures in industrial areas are still rarely studied but of high interest. This article analyses data from two expeditions, the multidisciplinary GoNorth 2023 in the Arctic and the NPI Fram Strait 2024 cruise, combined with detailed analysis along the ridge keel and calculation of limit stress on vertical structures. The ice ridges were investigated by drilling cross-sections and sampling cores for temperature, salinity and density measurements. The keel depth ranged from 3.0 m to 4.8 m and the sail height ranged from 0.3 m to 0.9 m. The mean density and salinity of the ridge samples in 2023 were 899 kg/m³ and 2.2 ppt, respectively, and the mean salinity in 2024 was 2.0 ppt. The average constant temperature in the keel was −1.7 °C in 2023 and −1.6 °C in 2024. The upper limit of the strength of ridged ice on a vertical structure of 7.2 m in width ranged from 3.1 to 4.1 MPa. These results contribute to the knowledge of summer consolidation processes and are useful for statistical analysis of ice ridge loads exerted on offshore structures by drifting ice ridges. Full article

The study of ice runways has significant practical importance. Regarding inland lake ice, while little of the practicality of ice runways during the ice formation period was explored in the published articles, the analysis of the time period and suitable locations may be used. This study focused on Huhenuoer Lake, located in Chen Barag Banner in northeastern China. The time-dependent law of ice growth in this lake has been investigated over a study period from 2023 to 2024. Utilizing the drilling approach, the ice thickness, recorded at each site on 29 February 2024, has surpassed 100 cm. On 14 March 2024, the recorded ice thickness at site #2 reached a record high of 139 cm. Second, to assess the project’s ease of use and safety, we used the Stefan equation to model the lake’s ice growth processes, resulting in a fitted Stefan coefficient of 2.202. For safety considerations, the Stefan coefficient used for the construction of the ice runway was set at 1.870. We investigated the distribution of lake ice and concluded that the lake ice runway should be established in the north. We established the relationship between ice thickness, cumulative snowfall, and negative accumulated temperature by integrating the fitting technique with the Stefan model. Utilizing the P-III method, the minimum value of the maximum negative accumulated temperature for the 50-year return period is 2092.46 °C·d, while the maximum cumulative snowfall for the 50-year period is 58.4 mm. We can apply these values to the aforementioned relationship to derive the ice thickness patterns across varying return periods. Finally, the study provides recommendations for the construction of the ice runway at Huhenuoer Lake. This study introduces ice field research and an ice growth model into the analysis of lake ice runway operations to provide technical assistance for ice runways. Full article

In the drilling process in permafrost strata, the mass and heat transfer effects may thaw the strata around the boreholes and decrease the content of pore ice, thus causing the mechanical properties of the strata to deteriorate greatly, thus influencing the stability of the borehole walls. In this work, a multiphysics coupling mathematical model was built for the stability of borehole walls in permafrost strata. Based on this model, the leading factors for the influences of the mass and heat transfer effects of drilling fluids on the stability of borehole walls were analyzed, and the influences of different drilling conditions on the stability of borehole walls were studied. The results demonstrate that the heat conduction of drilling fluids to the strata is the most important factor that influences the stability of borehole walls, and the diffusion of salt components affects the freezing temperature of pore water and the pore ice content in the frozen area. As the duration of the drilling increases, the collapsed zones of the borehole walls develop toward the radial and circumferential directions. Decreasing the temperature of the drilling fluids can improve the temperature distribution in the strata around the boreholes and is beneficial to reducing the degree of collapse. The increment in the concentration of salt components in the drilling fluids can decrease the overall temperature distribution in the strata, while the increase in the ionic concentration substantially decreases the pore ice content in permafrost and increases the borehole expansion rate. Enlarging the fluid column pressure of the drilling fluids does not intensify the mass and heat transfer effect of drilling fluids on the strata, while it greatly affects the stress distribution in the strata, shrinks the borehole collapse range, and improves the stability of the borehole walls. Full article

Thermal ice drilling technology is extensively used in drilling operations such as temperature measurement holes and subglacial water environment investigations in Antarctica owing to its advantages of compactness, light weight, and ease of operation. However, thermal drilling disturbs the initial temperature of the surrounding ice, making it impossible to obtain the true ice temperature through a borehole within a short period. Meltwater refreezing also causes the borehole to shrink and close, posing a threat to drilling safety. Therefore, obtaining an accurate characterization of the temperature field around the hole and assessing the meltwater refreezing rate are crucial for determining the appropriate temperature measurement duration and optimizing drilling parameters. To address this issue, a temperature measurement platform for the ice surrounding the borehole was developed. Experimental investigations were conducted to analyze the temperature fields during thermal drilling using both small-diameter thermal heads and RECoverable Autonomous Sonde (RECAS) thermal heads. This study clarifies the temperature field changes in the surrounding ice during and after thermal drilling. It also elucidates the effects of parameters such as the ice temperature, thermal head heating power, and thermal head diameter on the temperature field around the hole and estimates the meltwater refreezing rate inside the borehole. The results indicated that the temperature of the surrounding ice peaked approximately 5–7 h after drilling and subsequently decreased and returned to the original temperature within 48 h. The thermal disturbance radius in the surrounding ice was approximately 1.1 to 1.7 times the borehole radius when the thermal head passed through. However, after the thermal head passed, the thermal disturbance radius continued to expand owing to the heat released from meltwater refreezing, reaching 9.7 to 12.5 times the borehole radius. The average meltwater refreezing rate, estimated from temperature measurement tests at −16 °C, was 3.6 mm/h. Full article

Forest fires, i.e., wildfires, often cause an inevitable strain on society and human living conditions. Incident Commanders (IC) at the Fire and Rescue Services (FRS) are challenged to handle forest fires and at the same time address the forest owners’ needs; this stipulates a need for collaboration, information, and communication. Hence, the aim of this study was to explore and describe the ICs’ experiences and actions in their interactions with forest owners during forest fires on private property. Interviews were conducted and analyzed using Flanagan’s Critical Incident Technique (CIT) to describe the experiences and actions of 22 ICs. The results showed that a firefighting operation needs clarity in information exchange with the forest owner as a stakeholder, not a victim. The trust between forest owner and IC accelerated the operational phase. The ICs demonstrate more care than the law stipulates, and they worry about the forest owners. Therefore, the FRS needs to form a strategic partnership with forest owners and their network on a local level. Also, future forest fire drills should not only include emergency stakeholders (i.e., police, ambulance, etc.) but also forest owners and local volunteer organizations. For a resilient community, FRS and forest owner collaboration is vital. Full article

The monitoring of carbon emissions is increasingly becoming a sustainability issue worldwide. Despite being largely unnoticed, the toxic gas carbon monoxide (CO) is ubiquitous in mechanized tunnel driving, but the individual sources, release and enrichment mechanisms are often unknown. In this study, the generation of CO from organic matter containing sedimentary rocks was investigated during mechanized tunnel driving and by reacting claystone and sandstone with 10 mM NaCl solutions for 2 months at 70 °C and 140 °C. The mineralogical and geochemical evolution of the solids and fluids was assessed by CO measurements and the XRD, DTA, TOC, IC and ICP-OES methods. The CO concentration in the atmosphere reached up to 1920 ppm (100 ppm on average) during tunnel driving, which is more than three times higher than the legal daily average dose for tunnellers, thus requiring occupational safety operations. Mineral-specific dissolution processes and the rapid decomposition of labile organic matter upon thermal alteration contributed to the liberation of CO and also carbon dioxide (CO₂) from the host rocks. In mechanized tunnel driving, frictional heat and ‘cold’ combustion with temperatures reaching 50–70 °C at the drill head is an important mechanism for increased CO and CO₂ generation, especially during drilling in sedimentary rocks containing significant amounts of OM and when the ventilation of the tunnel atmosphere and air mixing are limited. Under such conditions, human health damage due to CO exposure (HHD_CO) can be 30 times higher compared to tunnel outlets, where CO is emitted from traffic. Full article

The Yamal-Nenets Autonomous District, especially the Yamal Peninsula located in the permafrost zone, stores Russia’s largest oil and gas resources. However, development in the area is challenging because of its harsh climate and engineering–geological features. Drilling in oil and gas fields in permafrost faces problems that are fraught with serious accident risks: soil heaving leading to the collapse of wellheads and hole walls, deformation and breakage of casing strings, gas seeps or explosive emissions, etc. In this respect, knowledge of the permafrost’s structure is indispensable to ensure safe geological exploration and petroleum production in high-latitude regions. The extent and structure of permafrost in West Siberia, especially in its northern part (Yamal and Gydan Peninsulas), remain poorly studied. More insights into the permafrost’s structure have been obtained by a precise sTEM survey in the northern Yamal Peninsula. The sTEM soundings were performed in a large oil and gas field where permafrost is subject to natural and anthropogenic impacts, and its degradation, with freezing–thawing fluctuations and frost deformation, poses risks to exploration and development operations, as well as to production infrastructure. The results show that permafrost in the western part of the Yamal geocryological province is continuous laterally but encloses subriver and sublake unfrozen zones (taliks) and lenses of saline liquid material (cryopegs). The total thickness of perennially frozen rocks is 200 m. The rocks below 200 m have negative temperatures but are free from pore ice. Conductive features (<10 Ohm﮲m) traceable to the permafrost base may represent faults that act as pathways for water and gas fluids and, thus, can cause a geohazard in the oil and gas fields (explosion of frost mounds, gas blow during shallow drilling, etc.). Full article

Hybrid Laminar Flow Control (HLFC) is a promising technology for reducing aircraft drag and, therefore, emissions and fuel consumption. The integration of HLFC systems within the small space of the wing leading edge, together with de-icing and high lift systems, is one of the main challenges of this technology. This challenge can be tackled by using microholes along the outer skin panels to control suction without the need for an internal chamber. However, microperforations modify the mechanical properties of titanium sheets, which bring new challenges in terms of wing manufacturability. These modified properties create uncertainty that must be investigated. The present paper studies the mechanical properties of micro-drilled titanium grade 2 sheets and their modeling using the Finite Element Method (FEM). First, an experimental campaign consisting of tensile and Nakajima tests is conducted. Then, an FEM model is developed to understand the role of the anisotropy in sheet formability. The anisotropy ratios are found by combination of Design of Experiments (DoE) and the Response Surface Method (RSM); these ratios are as follows: 1.050, 1.320, and 0.975 in the directions Y, Z, and XY, respectively. Some mechanical properties are affected by the presence of microholes, especially the elongation and formability that are significantly reduced. The reduction in elongation depends on the orientation: 20% in longitudinal, 17% in diagonal, and 31% in transversal. Full article

During oil and gas development in permafrost, hot fluids within the wellbore can cause ice melting around wellbore and a decrease in sediment strength, as well as wellbore instability. In the present work, the experimental system for evaluating the insulation effectiveness was established, and the applicability of this experimental system and methodology was verified. It was found that the difference between the experimentally obtained and actual thermal conductivity of the ordinary casings are all within 1.0 W/(m·°C). Meanwhile, the evaluation of insulation effect found that the decrease in fluid temperature, ambient temperature, and vacuum degree can improve its insulation performance. Finally, the numerical simulation was conducted on ice melting and borehole stability during the drilling operation in permafrost. The investigation results demonstrate that the use of vacuum-insulated casings significantly reduces the total heat transferred during the simulation by 86.72% compared to the ordinary casing. The utilization of vacuum-insulated casing reduces the range of ice melting around wellbore to only 16%, which occurs when using ordinary casing. The use of the vacuum-insulated casing resulted in a reduction in the final borehole enlargement rate from 52.1% to 4.2%, and wellbore instability was effectively suppressed. Full article

The undrained shear strength is an essential parameter in the foundation design of marine structures. Due to the complex marine environment and technical limitations, it is difficult and costly to obtain offshore samples. Piezocone penetration tests (CPTU) are relatively low-cost compared to drilling and sampling methods. Therefore, based on the soil behavior type index (I_c) derived from CPTU results, a model for estimating cone factors (N_kt, N_ke) is proposed to improve the accuracy of estimation of undrained shear strength. The result shows that the soil behavior type index (I_c) and cone factors take on a negatively correlated exponential relation. Incorporating a cone factor that varies with the soil behavior type index (I_c) significantly enhances the accuracy of undrained shear strength predictions compared to the conventional method of using a constant cone factor. This approach reduces the root mean square error (RMSE) for N_kt (N_ke) from 0.124 (0.126) MPa to 0.056 (0.06) MPa, and the mean absolute error (MAE) from 0.0154 (0.016) MPa to 0.0032 (0.0036) MPa. The method was validated at an additional location and the predictions were in high agreement with the results of the consolidated quick direct shear test. The developed method can serve as an effective tool used in the design of foundations of marine structures. Full article