Search Results (758)

Understanding the mechanical behaviour of blocky materials and structures is critical in engineering fields dealing with rock masses, masonry, ice crust, and fault gouge. The diverse block kinematics make mechanical responses difficult to predict. An important mechanism controlling deformation of block assemblies (e.g., blocky rock mass) is so-called block elbowing, a process in which rotating blocks push neighbouring blocks apart. Previously, this mechanism has been studied using 1D chain models; however, the effect of higher dimensionality has not been fully understood. In this paper, a two-dimensional blocky structure (block panel) is analysed. It is found that adding a kinematic degree of freedom fundamentally alters structural behaviour. The rotation angle of blocks remains the same such that the assembly breaks into layers sliding over each other; however, the mutual sliding is complex and dependent on frictional conditions. First, the structure becomes skewed, with the sliding directions both subhorizontal and/or subvertical. Second, the sliding modes are not necessarily purely subhorizontal or purely subvertical; combined sliding patterns are more prevalent. These observations highlight the fundamental role of elbowing in governing the block kinematics. In frictionless conditions, coordinated block rotations and complex block sliding are observed. The only mechanism capable of producing this behaviour is elbowing. In frictional conditions, sliding is considerably restrained and the assembly tends to rotate as a whole. These findings contribute to the understanding that neglecting block elbowing may overlook critical deformation mechanisms. The results provide a mechanical basis for analysing blocky structures in rock engineering and related geophysical systems. Full article

Ultra-deep lattice-like fractured carbonate reservoirs, formed by multi-period tectonic movements, feature strong heterogeneity, multi-scale fracture nesting, and anisotropic in situ stress. However, hydraulic fracture (HF) propagation behaviors within these complex formations remain poorly understood. In this study, using an unstructured fracture network approach, we simulated HF propagation in two typical fault-controlled lattice-like structures: compressive-torsion and pull-apart overlap zones. The performance of commingled, staged, and temporary plugging fracturing was evaluated, alongside sensitivity analyses of wellbore orientation, plugging timing, pump rate, and fluid viscosity. Results indicate that HFs in compressive-torsion zones exhibit long, straight geometries with local tensile activation points. Conversely, pull-apart overlap zones promote step-shaped, multi-branched fractures with superior lateral connectivity. The optimal timing for temporary plugging exhibits a delayed trend with increasing natural fracture density, ranging from 50% to 70% of the fracturing process in compressive-torsion zones, whereas an earlier implementation is preferred in pull-apart overlap zones, occurring at 33–65% of the fracturing process. Furthermore, HFs in compressive-torsion zones are less sensitive to viscosity and pump rate. To optimize stimulated volume, a moderate viscosity of 50–60 mPa·s is universally recommended. Regarding pump rates, 8–10 m³/min is ideal for balanced connectivity in pull-apart overlap zones, whereas >12 m³/min is required for compressive-torsion zones. These findings provide critical theoretical and engineering guidelines for differentiated fracturing strategies in ultra-deep reservoirs. Full article

Western Anatolia is a tectonically and seismically active region shaped by the complex interaction among the Eurasian, African, and Arabian plates. Since the Late Cenozoic, it has been dominated by an extensional tectonic regime. This study investigates the morphotectonic, seismotectonic, and kinematic evolution of the Edremit and Bakırçay basins and their surroundings, located at the intersection zone of the right-lateral strike-slip North Anatolian Fault System (NAFS) and the subduction-zone-driven Aegean Extensional System (AES). Within the scope of this research study, paleostress analyses were conducted using slip data obtained from fault planes, and these data were compared with 240 earthquake focal mechanism solutions reflecting the contemporary seismicity of the region. The findings indicate that both basins underwent a synchronized, two-stage tectonic evolution throughout the Plio-Quaternary period. During the first phase, encompassing the Pliocene, back-arc extensional forces related to slab rollback in the Hellenic subduction zone were dominant, and the main graben-forming processes (NW-SE-trending extension) took place. In the second phase, spanning the Quaternary period, an axis shift occurred as the southern branches of the NAFS reached the region, leading to the development of transtensional pull-apart basin mechanisms dominated by NE-SW-trending extension. Also supported by GPS velocity vectors and paleomagnetic block rotation data, this kinematic model demonstrates that the neotectonic evolution of Northwest Anatolia is governed not only by upper-crustal deformations but also by deep asthenospheric/lithospheric processes, such as slab rollback, lithospheric slab tear, and the NAFS-controlled westward differential escape of the Anatolian block. Full article

Self-supervised graph collaborative filtering suffers from two geometric pathologies. In Dimensional Collapse, embeddings quietly collapse into a low-rank subspace, a well-documented but poorly solved problem. Semantic Collapse is more complex: stiff $L^2$-squared orthogonalization penalties that are supposed to push the embeddings apart end up ripping through the heavy-tailed community overlaps that contain the collaborative signal. Earlier studies attempted to mitigate sparsity by injecting static noise or structural perturbations, but such interventions did not pinpoint the root cause, i.e., the distortions in the global covariance geometry itself. In this paper, we propose a Huber-Contrastive Graph Convolutional Network (HCGCN) that combines a spatial message-passing backbone with an $O(1)$ contrastive augmentation overhead and a Relation-Aware Dual-View Gated Contrastive Network. The main novelty is a Huber Covariance Whitening module that imposes a geometry-aware threshold on the cross-correlation matrix of augmented views—below the threshold, the gradients follow an $L^2$ penalty (enforcing uniformity); above it, the penalty flattens to $L^1$ (protecting genuine semantic clusters from gradient explosion). This theoretically motivated dual-regime penalty actively preserves the macro-semantic topology of the graph while aggressively stamping out spurious noise correlations. The HCGCN is evaluated on the Yelp2018, Amazon-Book, and MovieLens datasets and performs significantly better than state-of-the-art baselines like LightGCN, SGL, SimGCL, and NESCL, especially under severe cold-start settings where covariance regulation proves most critical. Full article

The coronavirus disease (COVID-19) pandemic highlighted critical limitations in ongoing diagnostic and therapeutic strategies, underscoring the urgent need for alternative and complementary approaches. Carbon dots (CDs) represent a novel class of fluorescent carbon-based nanomaterials with increased research interest owing to their enhanced biocompatibility, tunable photoluminescence, aqueous solubility, and rich surface chemistry. This review outlines current approaches in the diagnosis and treatment of COVID-19, along with the main structural, physicochemical, and biological features of CDs. Recent advances in the application of CDs as biosensing and antiviral nanomaterials against SARS-CoV-2 are critically discussed with an emphasis on the influence of synthetic routes, precursor compounds, heteroatom doping, surface functionalization, and purification strategies on their optical behavior and biological performance. CD-based biosensors mainly rely on fluorescence-sensing strategies, exploiting changes in photoluminescence intensity or energy-transfer processes upon recognition of viral targets. Electrochemical approaches are also investigated, highlighting the role of CDs as electrode modifiers to enable sensitive immunodetection in complex biological samples. Apart from diagnosis, the therapeutic potential of CDs is underscored by inhibiting viral entry, replication, disrupting cell membranes, or modulating oxidative stress. Finally, current limitations, challenges, and future perspectives regarding mechanistic understanding, synthesis parameters, biodistribution, and clinical translation are discussed, demonstrating the potential of CDs as novel “shiny weapons” against COVID-19, combining therapeutic and diagnostic functions. Full article

In South Korea, apartments dominate the residential housing market, accounting for 67.5% of total housing transactions in the fourth quarter of 2018. With this figure continuing to rise, apartments are the most significant asset for many families. Consequently, precise and timely valuations are crucial for stakeholders, including homeowners, buyers, and mortgage lenders. Traditionally, these stakeholders have relied on the qualitative judgments of certified real estate agents. Because of market opacity and low liquidity, agents often use a comparative approach, referencing the most recent transaction prices of nearby comparable apartments. However, this method is subjective, potentially biased, time-consuming, and costly. Our study seeks to offer a more objective and quantitative method for determining fair apartment prices in Korea, helping market participants make informed decisions. The prediction target is the monthly representative price of an apartment complex (the within-complex average of transaction prices), from which a complex-level price index is subsequently constructed; we distinguish this target from individual transaction prices throughout. By employing clustering methods to identify similar apartments and imputation techniques for missing values, our model demonstrates promising results, with a mean absolute percentage error as low as 5.38% in the worst-case (consecutive-mask) setting and 4.76% in the typical (random-mask) setting. Because the training (2006–2015) and test (2016–2022) periods are temporally disjoint, these figures reflect out-of-sample performance rather than in-sample fit. We further validate the resulting series against external references: it attains a 5.03% MAPE against actual transactions nationwide—outperforming the appraiser-based Kookmin Bank index (7.29%)—and, once aggregated, closely tracks the official KREB transaction-based index while becoming available earlier; complex-level Granger tests confirm that our series temporally leads the appraiser-based series about 1.5 times as often as the reverse. We also outline the missing-data assumptions under which the approach is valid. Full article

Ultra-wideband (UWB) localization is widely used in indoor positioning because it provides high temporal resolution and direct geometric range constraints. In complex indoor environments, however, UWB ranging is affected by non-line-of-sight propagation, multipath reflection, heterogeneous measurement quality, and link-dependent persistent bias, producing long-tailed errors and trajectory drift. This paper proposes HBR-PGD, a heteroscedastic bias-robust projected gradient descent framework for UWB-only indoor localization. Its central idea is a role-separated error-source formulation that assigns packet-level quality degradation, anchor-channel persistent bias, and sparse instantaneous NLOS anomalies to different roles in a unified constrained residual model. Packet-level quality features are mapped to heteroscedastic uncertainty scales, robust loss shape parameters, and non-negative NLOS correction priors; anchor-channel soft gating limits residual-correction freedom; and target trajectories and bounded structural bias states are jointly estimated in overlapping sliding windows. Experiments on a public indoor UWB dataset show that HBR-PGD achieves RMSE values of 0.107 m, 0.068 m, and 0.204 m in residential-apartment, small-apartment, and workshop/industrial environments, respectively. Compared with WLS, MCC-VC-TOA, SR-MCC, and AR-PNN, HBR-PGD consistently improves overall accuracy and high-percentile robustness, with the largest gain in the workshop/industrial environment. Ablation results verify the contributions of heteroscedastic weighting, structural-bias estimation, gated correction, and information-weighted fusion. These results suggest that HBR-PGD is a practical UWB-only localization framework for complex indoor environments with heterogeneous measurement quality, persistent link bias, and sparse NLOS anomalies. Full article

Purpose: Owing to rapid economic development and increasing social complexity, parenting stress has intensified for many families. When parents are exposed to parenting-related stress without sufficient coping resources, they may become vulnerable to parental burnout. Based on two-wave parent–adolescent dyadic data, this study explored whether parental neglect and parental violence may serve as potential indirect pathways linking parental burnout to adolescents’ growth mindset. Methods: Using a semi-longitudinal design, we collected two waves of survey data one month apart from 382 middle-school students and their parents in a city in Central China. An initial cross-lagged panel model (CLPM) was estimated based on the proposed hypotheses. Because the initial model showed poor fit, it was modified based on the modification indices and theoretical considerations, yielding the final model. Results: The final model showed acceptable fit, χ²(15) = 39.15, RMSEA = 0.065, CFI = 0.978, and TLI = 0.952. T1 parental burnout was significantly and positively associated with T2 neglect (β = 0.20, p < 0.001), and T1 neglect was significantly and negatively associated with T2 growth mindset (β = −0.13, p < 0.01). The indirect effect = −0.02, 95% CI [−0.033, −0.003], p < 0.05. Supplementary analyses also showed a generally consistent pattern of results. Conclusions: These findings provide preliminary evidence that parental neglect may be an important linking pathway between parental burnout and lower levels of adolescents’ growth mindset. Full article

Background/Objectives: Multisensory inputs generate a common gravity-reference frame, but just the otoliths sense the gravity vector. Graviception is frequently assessed by setting a luminous line to the subjective visual vertical (S.V.V.). Population aging and diabetes prevalence, with insufficient physical activity, imply the need to ponder these factors in clinical assessments. This study aimed to assess S.V.V. accuracy/precision in adults with/without diabetes, according to age, physical activity, and general characteristics. Methods: Participants were 262 adults without diabetes (21–80 years old (y.o.)) and 187 adults with diabetes (28–80 y.o.; matched with 187 without diabetes). All participants had no history of otology/vestibular/neurology/autoimmune/orthopedic/severe renal disease or proliferative retinopathy or traumatic injury or balance complaints. After audiology–vestibular evaluations, the International Physical Activity Questionnaire was self-administered and the S.V.V. was estimated during static and on-axis rotation conditions. Results: In participants without diabetes, S.V.V. precision but not S.V.V. accuracy decreased after the age of 50 years, with no further decrease after the age of 70 years (up to 80 y.o.); the main cofactors contributing to the variability on the S.V.V. precision were physical activity and sitting time, with inconsistent contribution from a history of COVID-19 (R = 0.44 static and 0.35 on-axis, p < 0.00001). In participants with diabetes, the major contribution to the S.V.V. precision variability was from diabetes and age (R = 0.33, static and 31 on-axis, p < 0.00001). Conclusions: Apart from aging, the sensorimotor process affected by insufficient physical activity and sedentary behavior includes vestibular decline. The complex pathophysiology of diabetes may account for the contribution from these cofactors. Full article

To address robust polarization-domain adaptive anti-jamming for dual-polarized radars with limited secondary data and time-varying interference, this paper proposes a covariance-reliability-driven MVDR framework based on forgetting-factor covariance estimation and adaptive diagonal loading. The forgetting-factor recursion assigns larger weights to recent jammer-plus-noise snapshots to track nonstationary interference, while the adaptive loading coefficient is jointly controlled by sample deficiency and covariance condition-number degradation to improve inversion stability. Unlike many robust adaptive beamforming methods that require steering-vector uncertainty sets, mismatch distributions, or subspace information, the proposed method relies only on secondary data and a small set of scalar design parameters. Simulation results based on a synthetic dual-polarized array model show that the proposed method achieves competitive output SINR, effective jammer suppression, and improved robustness to moderate DOA and polarization mismatch under limited-snapshot and time-varying interference conditions. Complexity analysis indicates that the proposed method has the same dominant computational order as standard covariance-based MVDR beamforming, apart from condition-number evaluation. The present validation is simulation-based, and further verification using measured polarimetric radar data, realistic propagation models, or hardware experiments is still required. Full article

Melancholia remains a severe and complex form of depression. One possible avenue to a better understanding of melancholia and potentially improved methods of treating it, is via examination of the profiles of brain electrical activity of patients suffering from melancholia. However, apart from work using fMRI, relatively little is known about the electrophysiological basis of melancholia despite the potential for this to inform targeted effective treatments such as Transcranial Magnetic Stimulation. To better understand the state of research regarding EEG variables and melancholia, a systematic review was undertaken. Results indicated that there was a large degree of complexity in the association between melancholia and various EEG parameters, and that many specific aspects of brain electrical activity remain under-studied. Suggestions are made for future research. Full article

This study examined how older adults living in public rental apartment complexes perceive and interpret information signs related to wayfinding, facility use, and safety. A questionnaire survey was conducted with 80 residents aged 65 years and older in two public rental apartment complexes in Nowon-gu, Seoul, and 12 participants with varying levels of cognitive function were selected for an eye-tracking experiment. The survey identified small sign and font sizes, insufficient color contrast and clarity, and inappropriate installation locations as the main problems. Time to First Fixation (TTFF) and dwell time were analyzed. Signs with clearer contrast against the background and increased sign size tended to elicit more favorable visual responses, whereas adjusting font size alone had limited effects. Heat map and scan path analyses also showed that the cognitively impaired group had more widely dispersed visual exploration patterns. Due to the limited sample size, statistical significance could not be sufficiently verified, and the findings cannot be generalized. Nevertheless, older adults’ subjective perceptions did not always correspond to the objective experimental results. Information sign improvements should therefore consider both rapid detection and ease of reading. Full article

Bronchopleural fistula is a rare but severe complication of lung resection, associated with significant morbidity and mortality, especially when an open-window thoracostomy is required. The clinical and surgical management is complex and becomes even more challenging in the presence of underlying conditions such as recurrent infections or malignancy. Postoperative management is equally demanding, as local compression may help prevent fistula recurrence but can compromise flap perfusion. A 65-year-old male with a history of right upper lobectomy and subsequent sublobar resection for lung adenocarcinoma presented with an 8 × 4 cm open-window thoracostomy complicated by chronic bronchopleural fistula and empyema. Extensive fibrosis of the surrounding tissues, including the ipsilateral latissimus dorsi muscle, limited the available reconstructive locoregional options. Reconstruction was performed using primary fistula closure reinforced with a contralateral free latissimus dorsi musculocutaneous flap and a fascia patch graft secured with cyanoacrylate-based bioadhesive. Postoperatively, continuous near-infrared spectroscopy monitoring enabled safe application of compressive bandage while minimizing the risk of flap perfusion compromise. Complete fistula closure was achieved. Apart from a surgical site abscess requiring debridement on postoperative day 7, no further complications occurred. At the 2-year follow-up, the patient remains free of fistula recurrence, wound dehiscence, or oncological relapse. We describe a novel approach for open-window thoracostomy closure combining a free musculocutaneous flap with a fascia patch graft reinforced by bioadhesive, together with postoperative perfusion monitoring using near-infrared spectroscopy. This strategy may help address both the reconstructive and postoperative challenges associated with complex bronchopleural fistulas. Full article

Wind turbine blade (WTB) end-of-life waste is projected to increase significantly, yet no sustainable recycling solution with a clear energy, economic, and environmental (3E) assessment exists. This paper presents a validated 3E model of a WTB thermal recycling pilot (1 t/day) to benchmark recycled glass fibre (rGF) against virgin glass fibre (vGF) and identifies the throughput at which rGF becomes competitive. This subsequently leads to a projection of 3E performance at 5000 t/y plant capacity, at which rGF achieves approximately 46% lower specific primary thermal energy, 92% of the CO₂ emissions of vGF, and a selling price of 80% of vGF for a financial break-even. Building on this baseline, a novel combined material, heat, and power system is proposed and simulated, integrating the WTB recycling pilot with a 20 kWₑₗ/130 kWₜₕ organic Rankine cycle to serve residential buildings. Results show that coupling the pilot with 3000 m² of apartments yields a near net-zero CO₂ and energy-cost residential complex, with overall CO₂ emissions falling below those of standalone residential buildings combined with vGF production when more than 25 apartments are integrated. Full article

This paper presents a case study demonstrating the operation of a 50 kVA three-phase variable-speed diesel generator at a Spanish Antarctic research base, located in an area of special ecological and environmental value, under conditions of extreme humidity and temperature. It verifies the fuel savings achieved through the use of variable-speed technology compared to standard, constant-speed generators. Furthermore, given that the price of fuel is significantly higher due to the high cost and complexity of transporting it to the base, the fuel savings at the base represent a huge logistical advantage, quite apart, of course, from the environmental benefits of such savings. A key feature of the equipment presented is that it has a system for recovering waste heat from the combustion engine, which, when integrated into the base’s hot water system, is used to increase the domestic hot water capacity, adding value to the machine whilst also delivering fuel savings. Full article