Search Results (2,181)

Frictional energy piles are a more desirable form of shallow geothermal energy utilization. A pure friction pile condition cannot be achieved in field tests. In this study, foam was placed beneath the model pile tip to weaken the end-bearing resistance. The effects of different cyclic temperature patterns (including cyclic path, external load, and variable temperature duration) on the bearing characteristics of pure friction energy piles are investigated by conducting model tests in a self-designed model box, and the variation patterns of pile stress–strain and pile-top displacement are measured. The results show the following: (1) Under no load, the displacement of the pile top changes with temperature; each round of temperature change produces a partial irrecoverable displacement, and the pile maintains a raised state at the end of both rounds with no stress accumulation. (2) Under the combined action of working load and cyclic temperature, the pile strain reaches its peak and then partially rebounds. Thermal stress accumulates progressively with increasing cycle numbers, and after the cycling ends, an irrecoverable settlement displacement (0.52% D) remains at the pile top and continues to increase. (3) The temperature cycle caused the soil volume to shrink and decreased the shear strength of the pile–soil interface, resulting in a decrease in the ultimate bearing capacity of the test pile compared to the initial state. Full article

This paper proposes a mismatch-index-driven coordinated flexible-step terminal-free distributed model predictive control (DMPC) scheme with an adaptive prediction horizon for asynchronous multi-agent systems (MASs) subject to bounded disturbances. The proposed approach explicitly exploits the inherent symmetry of the undirected communication topology among the agents, which ensures reciprocal information exchange, balanced cooperative interactions, and facilitates the rigorous analysis of consensus under asynchrony. By extending the generalized discrete-time control Lyapunov function (g-dclf) framework to the perturbed setting, we introduce a robust g-dclf together with a robust average decrease constraint that explicitly accounts for the worst-case effect of disturbances. A coordinated self-triggering mechanism, built upon the cost prediction mismatch index and the flexible-step execution strategy, is developed to simultaneously determine the inter-execution times and the number of control steps to be applied in each iteration. In addition, an adaptive shrinking prediction horizon strategy is incorporated to further reduce the computational complexity of the local optimization control problems (OCPs) as the agents approach consensus. The resulting robust flexible-step terminal-free DMPC (RFSTDMPC) algorithm is fully distributed, handles asynchronous communication, and operates without any stability-related terminal constraint. Recursive feasibility of each local OCP and input-to-state stability (ISS) of the overall closed-loop MAS are rigorously established under the symmetric network structure. Simulation results on the consensus problem of three perturbed nonholonomic vehicles demonstrate the effectiveness of the proposed scheme in achieving practical full-state stabilization while significantly alleviating the online computational burden. Full article

In the context of the new power system, coal-fired units are transitioning into peaking units. This study investigates the combustion characteristics and NO_X emissions of a 600 MW opposed wall-fired boiler within a load range of 50% to 20%, and further analyzes the impact of burner operation modes on boiler performance at the 20% ultra-low load. The results indicate that as the boiler load decreases from 50% to 20%, the average temperature in the primary combustion zone drops from 1634.3 K to 1457.0 K, and the ignition distance extends from 0.228 m to 0.260 m, leading to a significant decline in combustion stability. Notably, at the 20% ultra-low load, although the drop in temperature suppresses the formation of thermal NO_X, the flow short-circuiting caused by the shrinking of the recirculation zone results in pulverized coal particles missing the optimal reduction window; the formation pathway dominated by fuel NO_X causes the NO_X concentration at the furnace outlet to surge to 670.6 mg/m³. Furthermore, the burner operation modes significantly influence boiler performance at the 20% ultra-low load. While ensuring combustion stability, operating the lower-tier burners effectively reduces NO_X emissions by up to 21.6%. Considering both combustion stability and NO_X emissions, prioritizing the operation of lower-tier burners is recommended. This study reveals the underlying mechanisms behind the surge in NO_X concentrations at ultra-low loads of 20% and proposes optimal burner operation strategies, providing a theoretical foundation for the clean and stable operation of boilers during deep peak shaving. Full article

Retrieval-augmented large language model (LLM) post-processing reportedly improves anomaly triage over streaming industrial Internet of Things (IoT) sensor data, yet its LLM and retrieval contributions are rarely separated. We audit a build-verified pipeline (detector, LLM, retrieval, reranking), adding each stage at a matched detector recall of 0.9 under SHA-256-frozen preregistration, with bootstrap intervals and two generator sizes on 40 NAB and SKAB streams (19 industrial). Retrieval, the preregistered primary contrast, is null in seven of eight design configurations, but a preregistered grid of lower recall targets breaks that null on precision at both targets under stream-level resampling and in two of four cells when benchmark families are the unit. Across that grid, the LLM gain (72B F1 +0.0502) shrinks as candidate recall falls (+0.0227 at 0.7, undetectable at 0.5), which is a bound, not a dose–response curve. There, retrieval buys precision at a significant cost of recall. On the 19 industrial streams, the LLM gain is null at one label-free point and exactly zero at the other two, where the generator confirmed every candidate. Faithfulness, by local natural language inference, is low in every arm and not raised by retrieval. Three annotators labeling 133 claims (Fleiss’ κ = 0.555) placed the shortfall in the verdicts; none entailed by consensus. The protocol is released as a tested artifact. Full article

To overcome the limitations of existing three-degree-of-freedom milling stability models in representing axial cutting conditions, this study develops a stability prediction framework that accounts for both axial segmentation and the axial contact angle. A three-degree-of-freedom dynamic model of the milling system is first formulated by introducing the axial contact angle. The tool axis is then discretized, so that the cutting force coefficients can be evaluated in different axial sections and the non-uniform distribution of cutting forces along the tool can be captured more accurately. After incorporating the regenerative mechanism, the milling dynamics are expressed in the form of a linear time-delay differential equation. To enhance the numerical accuracy of the time-delay system solution, a full-discretization scheme using third-order Lagrange–Hermite interpolation is developed for constructing the state transition matrix. The stability boundary is subsequently determined based on Floquet theory, from which the stability lobe diagram is generated. The proposed model and solution procedure are validated by comparison with existing methods and by time-domain simulation. The results show that, when the spindle speed ranges from 5000 to 10,000 rpm and the axial depth of cut ranges from 0 to 8 mm, the overall variation rate of the predicted stability region is 11.19% after incorporating axial discretization and 59.88% after considering the axial contact angle. The stable and unstable cutting responses obtained from time-domain simulations are consistent with the regions predicted by the stability lobe diagram, which supports the validity of the proposed approach. Further investigation shows that, for the established three-degree-of-freedom milling model and the specified cutting parameters, the axial contact angle exerts a pronounced nonlinear effect on the stability boundary. Specifically, as the axial contact angle $\epsilon$ increases within the range $0^{°}<\epsilon \le {45}^{°}$, the stable region gradually shrinks; when $\epsilon$ increases from 45° to 90°, the stable region expands instead. These observations can provide useful guidance for selecting milling parameters and identifying stable machining conditions. Full article

Background: Family caregivers play a central role in supporting people with colorectal cancer (CRC) and often manage complex physical, emotional, and practical demands. However, evidence regarding their experiences and supportive care needs in Kazakhstan remains limited. This qualitative study explored caregiving experiences, caregiving burden, caregivers’ needs, and coping strategies. Methods: A qualitative descriptive design was used, involving semi-structured interviews with 21 family caregivers caring for patients with CRC. Participants were recruited purposively from the Medical Center of West Kazakhstan Marat Ospanov Medical University and outpatient clinics in Aktobe between December 2025 and March 2026. Interviews were audio-recorded, transcribed verbatim, and analyzed using inductive reflexive thematic analysis. Results: Most family caregivers of patients with colorectal cancer were women (95.2%). Five main themes developed: emotional challenges, transformation of daily life, caregiving tasks, caregivers’ needs and support gaps, and coping strategies and resilience. Diagnosis was described as a distressing experience characterized by shock, fear, and uncertainty. Caregiving substantially disrupted employment, financial stability, and family roles, often requiring work adjustment or leaving the workforce. Caregivers reported insufficient preparation for stoma care and expressed a strong need for structured training. Social isolation was common, as both caregivers and patients experienced a shrinking of their social support networks. Despite substantial burden, caregivers described adaptive responses to ongoing emotional and practical demands, and resilience was a prominent theme. Conclusions: Family caregivers of patients with colorectal cancer in Kazakhstan face interconnected emotional, informational, physical, and system-level challenges, while also drawing on resilience. The findings highlight priorities for support, including structured stoma care education, psychological services, recognition of caregivers’ roles, and improved discharge and transitional care. Full article

Spent automotive catalysts represent an important secondary resource for platinum group metals, offering environmental and economic advantages over primary mining. This review evaluates bioleaching-based recovery strategies of these metals as sustainable alternatives to conventional pyrometallurgical and hydrometallurgical processing. The cyanogenic bioleaching using Chromobacterium violaceum, Pseudomonas fluorescens, and Bacillus megaterium, and acidophilic bioleaching using Acidithiobacillus spp. for washcoat degradation and base-metal removal are discussed through the one-step, two-step, spent-medium, and decoupled systems. The analysis shows progressive improvement of recovery as process separation increases. Sequential pretreatment involving ultrasound-assisted acid leaching, thermal oxidation, and pressure-enhanced processing improved recovery by removing competing base metals and increasing PGM accessibility. Kinetic analyses indicate that diffusion through the porous catalyst support matrix becomes the dominant rate-controlling mechanism at high conversion, which impacts reactor design. Despite sustainability potential, industrial implementation remains constrained by low pulp density, cyanide stability, reactor productivity, and scale-up limitations. Routes to commercialisation require feasibility studies of process designs that integrate viable process flow diagrams combining pretreatment, biological lixiviant generation, intensified bioleaching, and downstream metal purification. Full article

Achieving a balance between jobs and housing can reduce commuting distances and encourage residents to live and work within the same city. However, maintaining this balance may be challenging in shrinking cities, where population decline is often accompanied by housing vacancies and declining employment opportunities. Although previous studies have examined jobs–housing balance and urban shrinkage separately, little is known about how jobs–housing balance changes in the context of population decline. Using the 2010–2014 and 2015–2019 American Community Survey (ACS) 5-year estimates and the Office of Management and Budget (OMB) classification of principal cities, this study classified 677 U.S. cities into four groups based on population change and metropolitan location. Descriptive analysis was conducted to compare changes in jobs–housing balance across these groups using a newly proposed jobs–housing balance index. The results show that both growing and shrinking central cities experienced improvements in jobs–housing balance, although the mechanisms underlying these improvements differed. In contrast, shrinking non-central cities were the only group to exhibit a deterioration in jobs–housing balance. These findings suggest that strengthening employment opportunities in shrinking non-central cities may help improve jobs–housing balance and contribute to more sustainable urban development. Full article

Expansive soils are rich in hydrophilic clay minerals, and repeated wetting–drying cycles can induce deformation that threatens infrastructure safety. Therefore, accurate monitoring of soil moisture (SM) dynamics is essential for understanding hydro-mechanical processes and assessing related geohazards. In this study, spaceborne Global Navigation Satellite System Reflectometry (GNSS-R) is applied to expansive SM monitoring, and an Attention-Enhanced Spatio-Temporal Graph Convolution Network (ASTGCNet) is proposed for SM retrieval. The Texas coastal region, where Beaumont clay is widely distributed, was selected as the study area. The ASTGCNet-derived SM showed consistency with the Soil Moisture Active Passive (SMAP) reference product, with an overall correlation coefficient of 0.92, an RMSE of 0.035 m³/m³, and a bias of 0.006 m³/m³. Validation against in situ observations showed that ASTGCNet provided more accurate SM estimates than the Cyclone Global Navigation Satellite System (CYGNSS) L3 SM product. Extended triple collocation analysis further indicated that ASTGCNet achieved the lowest standard deviation of 0.020 m³/m³ and the highest signal-to-noise ratio of 7.33. Compared with non-expansive soils, expansive soils exhibited stronger water absorption and moisture retention behavior. By integrating GNSS vertical displacement observations, the retrieved SM revealed a nonlinear SM–deformation response that was mainly observed in shallow expansive soils. Drying-induced SM decreases corresponded to pronounced subsidence, while subsequent wetting led to ground rebound; this behavior was not clearly observed in non-expansive soils. This study demonstrates the potential of GNSS-R for expansive SM monitoring and provides new insights into the coupling between SM dynamics and deformation. Full article

SPARQ is an advanced global optimization algorithm, the direct evolution of an earlier method called ARQ2. It searches efficiently for the best solution to problems where the space of options is too vast to check exhaustively, such as tuning antenna arrays or planning fuel-efficient spacecraft trajectories. Like its predecessor, it works with a population of candidate solutions that improve generation after generation, alternating between two complementary search strategies. What sets SPARQ apart is that it makes nearly every part of this process adaptive. Its population shrinks intelligently as the search matures. Its internal settings draw from a memory of many past successful configurations, not a single average. Its escape-from-stagnation mechanisms come in graduated strength, from a gentle nudge to a deeper partial restart. It also adds capabilities its predecessor never had, including a dedicated phase that locally polishes the current best solution using its own memory of productive directions. Every addition is kept only where it showed an overall benefit during development, though a subsequent component-wise analysis shows this benefit varies markedly in size and statistical significance across mechanisms. The result is more reliable than its predecessor on the large majority of tested problems, while staying grounded in the same battle-tested core. Full article

Central Asia is a global climate-change hotspot where future water availability remains uncertain, as hydrological forcing data are ambiguous and observations provide limited constraints on model parameters. We reassessed future runoff changes in the glacierized Ala-Archa basin by reducing model equifinality with a multi-objective calibration strategy that explicitly incorporates winter low-flow runoff, total runoff, snow cover fraction, and glacier mass balance. The calibrated model was used to project annual and seasonal river discharge under four Shared Socioeconomic Pathways. Results indicate a transition from a nival–glacial to a more pluvial-driven runoff regime. Rising temperatures advance the melt season, increase the proportion of liquid precipitation, and shift peak runoff from July to June. Although glacier and snowmelt contributions decline substantially as cryospheric storage shrinks, total annual runoff decreases only modestly by the late 21st century. This muted annual response reflects compensating effects from increased rainfall and a sustained rise in summer baseflow. Improved low-flow calibration suggests that increased groundwater recharge can partly offset meltwater losses, leading to a less severe summer discharge reduction than previously reported. Neglecting low-flow constraints may therefore overestimate future water scarcity in glacier-fed catchments. Full article

An accurate prediction of gypsum-salt cap rocks is crucial for safe drilling and efficient development of subsalt hydrocarbons in the Tarim Basin. However, due to the complex lithological assemblages within the Middle Cambrian sequences, the P-impedance of gypsum severely overlaps with that of the background carbonate rocks, making conventional seismic prediction based on a single impedance threshold inadequate. To address this issue, this paper proposes a multi-parameter coupling while-drilling prediction method that integrates seismic data, drilling parameters and geochemical logging. First, pre-stack P-impedance inversion is performed on amplitude-preserved seismic data to macroscopically delineate the depth interval of gypsum-salt development. Second, a weighted synthetic change-rate model incorporating drilling time (DT), weight on bit (WOB), and outlet conductivity is constructed to dynamically calibrate the top interface of the gypsum-salt layer while drilling. Finally, within the constrained depth interval, X-ray fluorescence (XRF) elemental inversion of cuttings is used to quantitatively calculate the contents of clay, dolomite, gypsum and calcite, achieving fine-scale lithofacies identification at the sublayer level. An empirical application to Well XSC1 in the Keping fault-uplift, Tarim Basin, demonstrates that compared with the conventional single P-impedance threshold method, the proposed approach effectively distinguishes gypsum, salt and carbonate wall rocks, and significantly reduces the prediction errors of individual salt beds and gypsum sublayers. Specifically, the mean absolute error (MAE) of total gypsum-salt content decreases from 24.56% to 13.73% (a reduction of 44.1%), the bias drops from 2.45% to 0.31%, and the root mean square error (RMSE) decreases from 33.63% to 21.55%. At a 1% content threshold, the F1 score for gypsum-salt identification increases from 0.63 to 0.82; the absolute depth error of the top and bottom interfaces is reduced by approximately 70%, and the relative thickness error shrinks from $\pm$40% to within $\pm$10%. Transferability of this multi-parameter coupling strategy to other salt-bearing basins in central-western China remains unvalidated and requires future validation and testing. Full article

Oxygen bubbles, not catalysis, limit the anode of zero-gap alkaline water electrolysis (AWE) at industrial current densities. Here we compare stainless-steel (SS) mesh (M), felt (F), and a bonded felt–mesh bilayer mounted with the felt facing the Zirfon separator (FM) or reversed (MF) in a zero-gap cell (6 M KOH, 80 °C), bare and Ni-plated. On bare SS, architecture dominates: the felt generates fine bubbles (54 μm) and the mesh coarse ones (109 μm), and the correctly oriented bilayer exploits this contrast—fine generation at the separator, coarse evacuation (95 μm) through the mesh—to deliver 1.85 V at 1.0 A cm⁻², whereas the reversed stack is the worst electrode tested, showing voltage fluctuations symptomatic of interfacial gas blanketing. Ni plating improves every architecture (bilayer: 391 → 325 mV OER overpotential; 1.85 → 1.80 V) yet compresses the differences between them. Voltammetry and X-ray photoelectron spectroscopy show why: OER cycling converts the plated Ni into an Fe-incorporated NiFe (oxy)hydroxide—Fe appearing despite a nominally Fe-free bath—whose hydrophilicity shrinks bubbles on every architecture. Architecture and surface chemistry are thus complementary attacks on the same gas-management problem, and stacking orientation is a free design variable that no catalyst can replace. Operando impedance at 1.8 V and an overpotential decomposition price the penalty: flipping the electrode nearly triples the gas-transport overpotential at 1.0 A cm⁻², from ≈140 to ≈402 mV, while ohmic and kinetic terms remain nearly untouched. Full article

The obligate mixotroph Mesodinium rubrum significantly impacts coastal ecosystems, yet its population control in oligotrophic waters remains unclear. Integrating field observations from Coast of Sanya (South China Sea) with laboratory nutrient manipulation, we investigated how dissolved inorganic nutrients and prey availability regulate cell cycle progression, using biovolume as a proxy for cycle transitions. Nutrient starvation arrested cells at the small (newly divided) stage. Inorganic replenishment triggered rapid somatic growth and consistent diel biovolume oscillations, expanding in light and shrinking in darkness. However, without cryptophyte prey, cells failed to progress beyond the medium (actively growing) stage and could not accumulate into the large (pre-division) size class, revealing a decoupled regulatory mechanism. Dissolved inorganic nutrients drive cell size expansion (somatic growth), whereas prey-derived organelles serve as a critical prerequisite for division. Field data confirmed that the virtual absence of cryptophytes in Sanya waters restricts M. rubrum to consistently low levels. Our findings demonstrate that population dynamics of this specialist mixotroph transcend traditional nutrient-driven paradigms, underscoring the irreplaceable role of prey in sustaining photosynthetic metabolism and triggering population expansion in oligotrophic systems. Full article

Urban shrinkage in resource-based cities manifests not only as population decline but also as spatial mismatches between current human activities and inherited urban systems. Existing studies have mainly focused on single dimensions such as service accessibility or land-use efficiency, with limited attention to the multidimensional incompatibility between human activities, service systems, built environment, and industrial risks. This study develops a human activity-centered spatial mismatch framework to examine the spatial consistency between human activities and urban systems in shrinking resource-based cities. Taking the central urban area of Daqing as a case study, this study integrates multi-source urban big data across four spatial dimensions—human activity, public service provision, built environment, and industrial risk exposure—and identifies three types of spatial mismatch: service supply–demand mismatch, built environment mismatch, and industrial risk exposure conflict. The results show that human activities in central Daqing exhibit a polycentric pattern, while their spatial distribution is not fully consistent with existing urban systems. Specifically, service accessibility mismatch, built environment underutilization, and human activity–industrial risk overlap coexist across different areas, reflecting asynchronous adjustment between human activities and inherited urban structures. This study provides a human activity-centered framework for diagnosing multidimensional spatial conflicts in shrinking resource-based cities and supports a transition from expansion-oriented planning toward differentiated adaptive spatial governance. Full article