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To evaluate the beneficial effect of rubber bearings on the seismic performance of underground station structures, three-dimensional finite element models of seismic soil-structural systems are established for a single-layer double span subway station. The seismic mitigation effect is investigated by employing the pushover analysis method. The obtained results indicated that the installation of rubber bearings can effectively alleviate stress concentration and damage degree of the central column, especially at its end area. Compared with the conventional column, the elastic and elastoplastic deformation capacity of the column fitted with rubber bearings both improved significantly. It was also found that the load bearing and deformation performance decrease with the increase of the axial pressure ratio. Furthermore, the lateral force distribution mechanism of the structural system fitted with the rubber bearings is significantly different from the original structure; the deformation and internal forces of central column of the seismic mitigation structure decreased substantially, but side walls' deformation and internal forces increased slightly. The proportion of shear force taken by the central column has decreased, while the side walls have taken larger share, i.e., the rubber bearings facilitated the transfer of seismic forces from the middle column to the side wall.

期刊论文 2025-09-01 DOI: 10.1016/j.soildyn.2025.109487 ISSN: 0267-7261

This study investigates the influence of the soil-structure interaction (SSI) on the seismic performance of structures, focusing on the effects of foundation size, soil type, and superstructure height. While the importance of SSI is well recognized, its impact on structural behavior under seismic loads remains uncertain, particularly in terms of whether it reduces or amplifies structural demands. A simplified dynamic model, incorporating both the mechanical behavior of the soil and structural responses, is developed and validated to analyze these effects. Using a discrete element approach and the 1940 El Centro earthquake for validation, the study quantitatively compares the response of soil-interacting structures to those with fixed bases. The numerical results show that larger foundation blocks (20 m x 20 m and 30 m x 30 m) increase the seismic response values across all soil types, causing the structure to behave more like a fixed-base system. In contrast, reducing the foundation size to 10 m x 10 m increases the flexibility of structures, particularly buildings built on soft soils, which affects the displacement and acceleration response spectra. Softer soils also increase natural vibration periods and extend the plateau region in regard to spectral acceleration. This study further finds that foundation thickness has a minimal impact on spectral displacement, but structures on soft soils show more than a 15% reduction in spectral displacement (SD) compared to those on hard soils, indicating a dampening effect. Additionally, increasing the building height from 7 to 21 m results in a more than 20% decrease in SD for superstructures with natural vibration periods exceeding 2.4 s, while taller buildings with longer natural vibration periods exhibit opposite trends. Structures built on soft soils experience larger foundation-level displacements, absorbing more seismic energy and reducing earthquake accelerations, which mitigates structural damage. These results highlight the importance of considering SSI effects in seismic design scenarios to achieve more accurate performance predictions.

期刊论文 2024-12-01 DOI: 10.3390/app142310994

Exploring the relationship between the physio-mechanical properties of the loess-paleosol sequences and the paleoclimate can help provide essential references for engineering construction in the Chinese Loess Plateau, revealing the vital application value of Quaternary climate research. Continuous loess-paleosol sequence in the central Loess Plateau was selected to determine its physio-mechanical and chemical characteristics. The main results show: (1) During the interglacial period, the East Asian summer monsoon intensified, and the cementation of clay minerals made the soil structure dense under more precipitation, increasing soil cohesion. During the glacial period, the East Asian winter monsoon was stronger, and the loess's unstable microstructure was formed under the weak pedogenesis, increasing the compressibility and collapsibility. (2) The alternation of cold-dry/ warm-humid climate in the Quaternary is the fundamental reason for the differences in physio-mechanical properties and structural strength between loess and paleosol; pedogenesis plays a direct decisive role. The impact of compaction after burial on the physio-mechanical properties of loess-paleosol sequences is less than that of pedogenesis. (3) Precipitation plays a dominant role in the shear strength and compressibility of loesspaleosol sequences, while precipitation and temperature jointly affect the collapsibility. A quantitative relationship between paleoclimate and physio-mechanical properties was established.

期刊论文 2024-12-01 DOI: 10.1016/j.quascirev.2024.109047 ISSN: 0277-3791

This paper proposes an efficient algorithm in a discretization-based kinematic approach (DKA) to investigate the stability of non-uniform soil slopes in the presence of pore water pressure. In response to the problems of high dependency on discretization interval and low computational accuracy involved in the initial DKA based on a forward difference scheme (DKA-FD), a central difference 'point-to-point' method is developed to generate discretized failure surface. Based on this, an improved DKA with a central difference algorithm (DKA-CD) is formulated, with slope stability solutions obtained in terms of stability number, safety factor and critical failure surface. The research findings demonstrate that slope failure at limit state gradually shifts from below-toe and deep-toe modes to shallow-toe mode with the increase of slope angle and soil friction angle. The transition on slope failure pattern becomes more obvious with decreased pore pressure and increment in non-uniform gradient for soil friction angle.

期刊论文 2024-12-01 DOI: 10.1016/j.compgeo.2024.106737 ISSN: 0266-352X

Surface albedo (SA) is crucial for understanding land surface processes and climate simulation. This study analyzed SA changes and its influencing factors in Central Asia from 2001 to 2020, with projections 2025 to 2100. Factors analyzed included snow cover fraction, fractional vegetation cover, soil moisture, average state climate indices (temperature and precipitation), and extreme climate indices (heatwave indices and extreme precipitation indices). Pearson correlation coefficient, geographical convergent cross mapping, and geographical detector were used to quantify the correlation, causal relationship strength, and impact degree between SA and the influencing factors. To address multicollinearity, ridge regression (RR), geographically weighted ridge regression (GWRR), and piecewise structural equation modeling (pSEM) were combined to construct RR-pSEM and GWRR-pSEM models. Results indicated that SA in Central Asia increased from 2001 to 2010 and decreased from 2011 to 2020, with a projected future decline. There is a strong correlation and significant causality between SA and each factor. Snow cover fraction was identified as the most critical factor influencing SA. Average temperature and precipitation had a greater impact on SA than extreme climate indices, with a 1 degrees C temperature increase corresponding to a 0.004 decrease in SA. This study enhances understanding of SA changes under climate change, and provides a methodological framework for analyzing complex systems with multicollinearity. The proposed models offer valuable tools for studying interrelated factors in Earth system science.

期刊论文 2024-11-01 DOI: 10.1016/j.jag.2024.104233 ISSN: 1569-8432

Caffeine, a significant naturally occurring alkaloid in beverages like tea and coffee, can be degraded by bacteria. Prolonged caffeine consumption can stimulate adrenal glands, cause irregular muscle activity, cardiac arrhythmias, and withdrawal symptoms such as headaches and fatigue. Beyond its health-related concerns, the environmental impact of caffeine degradation is noteworthy. Effluents from coffee industries contain high caffeine concentrations, and the discharge of such effluents into lakes poses a risk to the portability of drinking water. This study isolated a novel bacterium from agricultural soil, identified as Bacillus sp. KS38 through 16 S rRNA gene sequencing, which can metabolize caffeine as the sole carbon and nitrogen source. The bacterium exhibited Gram-positive characteristics. Response surface methodology (RSM) optimized bacterial growth conditions. The relevant parameter for the degradation of caffeine was obtained by first screening the parameters using the Plackett-Burman design. Using central composite design (CCD) and RSM, the important parameters were determined to achieve the ideal degradation conditions. The identified the ideal degradation conditions: 0.66 g/L caffeine, 0.85 g/L glucose, pH 6.83, and 20.5 degrees C. RSM predicted a bacterial growth of 0.591, which was confirmed experimentally. This bacterium has potential applications in wastewater treatment and caffeine bioremediation.

期刊论文 2024-10-01 DOI: 10.1016/j.dwt.2024.100628 ISSN: 1944-3994

This study uses a new dataset on gauge locations and catchments to assess the impact of 21st-century climate change on the hydrology of 221 high-mountain catchments in Central Asia. A steady-state stochastic soil moisture water balance model was employed to project changes in runoff and evaporation for 2011-2040, 2041-2070, and 2071-2100, compared to the baseline period of 1979-2011. Baseline climate data were sourced from CHELSA V21 climatology, providing daily temperature and precipitation for each subcatchment. Future projections used bias-corrected outputs from four General Circulation Models under four pathways/scenarios (SSP1 RCP 2.6, SSP2 RCP 4.5, SSP3 RCP 7.0, SSP5 RCP 8.5). Global datasets informed soil parameter distribution, and glacier ablation data were integrated to refine discharge modeling and validated against long-term catchment discharge data. The atmospheric models predict an increase in median precipitation between 5.5% to 10.1% and a rise in median temperatures by 1.9 degrees C to 5.6 degrees C by the end of the 21st century, depending on the scenario and relative to the baseline. Hydrological model projections for this period indicate increases in actual evaporation between 7.3% to 17.4% and changes in discharge between + 1.1% to -2.7% for the SSP1 RCP 2.6 and SSP5 RCP 8.5 scenarios, respectively. Under the most extreme climate scenario (SSP5-8.5), discharge increases of 3.8% and 5.0% are anticipated during the first and second future periods, followed by a decrease of -2.7% in the third period. Significant glacier wastage is expected in lower-lying runoff zones, with overall discharge reductions in parts of the Tien Shan, including the Naryn catchment. Conversely, high-elevation areas in the Gissar-Alay and Pamir mountains are projected to experience discharge increases, driven by enhanced glacier ablation and delayed peak water, among other things. Shifts in precipitation patterns suggest more extreme but less frequent events, potentially altering the hydroclimate risk landscape in the region. Our findings highlight varied hydrological responses to climate change throughout high-mountain Central Asia. These insights inform strategies for effective and sustainable water management at the national and transboundary levels and help guide local stakeholders.

期刊论文 2024-09-01 DOI: 10.1007/s10584-024-03799-y ISSN: 0165-0009

The central carbon (C) metabolic network is responsible for most of the production of energy and biosynthesis in microorganisms and is therefore key to a mechanistic understanding of microbial life in soil communities. Many upland soil communities have shown a relatively high C flux through the pentose phosphate (PP) or the Entner-Doudoroff (ED) pathway, thought to be related to oxidative damage control. We tested the hypothesis that the metabolic organization of the central C metabolic network differed between two ecosystems, an anoxic marsh soil and oxic upland soil, and would be affected by altering oxygen concentrations. We expected there to be high PP/ED pathway activity under high oxygen concentrations and in oxic soils and low PP/ED activity in reduced oxygen concentrations and in marsh soil. Although we found high PP/ED activity in the upland soil and low activity in the marsh soil, lowering the oxygen concentration for the upland soil did not reduce the relative PP/ED pathway activity as hypothesized, nor did increasing the oxygen concentration in the marsh soil increase the PP/ED pathway activity. We speculate that the high PP/ED activity in the upland soil, even when exposed to low oxygen concentrations, was related to a high demand for NADPH for biosynthesis, thus reflecting higher microbial growth rates in C-rich soils than in C-poor sediments. Further studies are needed to explain the observed metabolic diversity among soil ecosystems and determine whether it is related to microbial growth rates. IMPORTANCE We observed that the organization of the central carbon (C) metabolic processes differed between oxic and anoxic soil. However, we also found that the pentose phosphate pathway/Entner-Doudoroff (PP/ED) pathway activity remained high after reducing the oxygen concentration for the upland soil and did not increase in response to an increase in oxygen concentration in the marsh soil. These observations contradicted the hypothesis that oxidative stress is a main driver for high PP/ED activity in soil communities. We suggest that the high PP/ED activity and NADPH production reflect higher anabolic activities and growth rates in the upland soil compared to the anaerobic marsh soil. A greater understanding of the molecular and biochemical processes in soil communities is needed to develop a mechanistic perspective on microbial activities and their relationship to soil C and nutrient cycling. Such an increased mechanistic perspective is ecologically relevant, given that the central carbon metabolic network is intimately tied to the energy metabolism of microbes, the efficiency of new microbial biomass production, and soil organic matter formation. We observed that the organization of the central carbon (C) metabolic processes differed between oxic and anoxic soil. However, we also found that the pentose phosphate pathway/Entner-Doudoroff (PP/ED) pathway activity remained high after reducing the oxygen concentration for the upland soil and did not increase in response to an increase in oxygen concentration in the marsh soil. These observations contradicted the hypothesis that oxidative stress is a main driver for high PP/ED activity in soil communities. We suggest that the high PP/ED activity and NADPH production reflect higher anabolic activities and growth rates in the upland soil compared to the anaerobic marsh soil. A greater understanding of the molecular and biochemical processes in soil communities is needed to develop a mechanistic perspective on microbial activities and their relationship to soil C and nutrient cycling. Such an increased mechanistic perspective is ecologically relevant, given that the central carbon metabolic network is intimately tied to the energy metabolism of microbes, the efficiency of new microbial biomass production, and soil organic matter formation.

期刊论文 2024-06-18 DOI: 10.1128/aem.00724-24 ISSN: 0099-2240

Aerosol optical properties, including absorption and scattering coefficients (B-abs, and B-scat), extinction coefficient (B-ext), single scattering albedo (SSA), and so forth, are critical metrics to estimate the radiative balance of the atmosphere. However, their ground measurements are sparsely distributed in the world, where Central Asia is void in these measurements. We had been performing the measurements of AOPs and BC with a photoacoustic extinctiometer (PAX) in Jimunai, a border town of China neighboring Kazakhstan, Central Asia, from Aug 2016 to Apr 2019. This three-year study first reported statistically significant trends of B-abs, B-scat, B-ext, SSA, and derived concentrations of BC (Mann-Kendall trend test, p-value 0.05) in the Central-Asian area. B-abs and B-scat show increasing trends and SSA was decreasing determined by the greater increasing pace of B-abs than B-scat. Seasonal and diurnal variations of the AOPs were associated with climate shift and residents' commute activity, respectively. The difference in the magnitudes and trends of AOPs between the measurements and satellites' observations advise that more care should be invested when choosing remote-sensing data to represent the AOPs at a specific site. The increasing trend of derived BC concentrations is reflected in the deposition record of BC in a snowpit of the nearby Muz Taw glacier. We suppose that the dramatically increasing BC particles emitted from Jimunai are significant factors triggering the melting of the adjacent mountain glaciers. The outflow of dust from the neighboring Gurbantiinggiit Desert could occasionally invade into Jimunai and deteriorate the local air quality, as evidenced by a probable dust event captured by the PAX on Feb 15, 2018. Finally, we outlook the future perspectives of measurements in Jimunai as a long-standing station.

期刊论文 2024-06-01 DOI: http://dx.doi.org/10.1021/acsearthspacechem.0c00306 ISSN: 2472-3452

The epicentral region of earthquakes is typically where liquefaction -related damage takes place. To determine the maximum distance, such as maximum epicentral distance (Re), maximum fault distance (Rf), or maximum hypocentral distance (Rh), at which an earthquake can inflict damage, given its magnitude, this study, using a recently updated global liquefaction database, multiple ML models are built to predict the limiting distances (Re, Rf, or Rh) required for an earthquake of a given magnitude to cause damage. Four machine learning models LSTM (Long Short -Term Memory), BiLSTM (Bidirectional Long Short -Term Memory), CNN (Convolutional Neural Network), and XGB (Extreme Gradient Boosting) are developed using the Python programming language. All four proposed ML models performed better than empirical models for limiting distance assessment. Among these models, the XGB model outperformed all the models. In order to determine how well the suggested models can predict limiting distances, a number of statistical parameters have been studied. To compare the accuracy of the proposed models, rank analysis, error matrix, and Taylor diagram have been developed. The ML models proposed in this paper are more robust than other current models and may be used to assess the minimal energy of a liquefaction disaster caused by an earthquake or to estimate the maximum distance of a liquefied site provided an earthquake in rapid disaster mapping.

期刊论文 2024-05-25 DOI: 10.12989/gae.2024.37.4.395 ISSN: 2005-307X
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