Search Results (20,660)

A backhand flick is frequently used in table tennis to initiate offensive play, yet how racket motion evolves during subsequent stroke transitions remains insufficiently characterized. This study examined racket kinematics in two common follow-up combinations: a backhand flick followed by a backhand fast block (BFBB) and a backhand flick followed by a forehand fast block (BFFB). In a within-subject design, ten national-level male players performed both combinations, and racket motion was recorded using a three-dimensional motion capture system at 200 Hz. Racket velocity, phase duration, and spatial displacement were quantified across the stroke sequence, and within-player differences between the two stroke transition combinations following the backhand flick were examined. Compared with BFBB, BFFB showed higher racket velocity at most key moments, particularly near ball contact, whereas no significant difference was found at the end of the follow-through. Backward-phase duration did not differ between the two conditions, but BFFB showed longer durations during the hitting and follow-through phases, together with a longer overall duration. BFFB also exhibited greater directional displacement across multiple phases, whereas BFBB was characterized by a more compact spatiotemporal pattern. These findings provide biomechanical evidence that different follow-up strokes after an identical backhand flick are associated with distinct patterns of racket motion during stroke transitions and may offer a kinematic reference for sequence-specific training in table tennis. Full article

Climate change and environmental degradation are increasingly recognized as major drivers of human mobility, operating through both sudden-onset disasters and slow-onset processes such as sea-level rise, desertification and resource scarcity. Although estimates vary widely, projections suggest that millions of people may become displaced by 2050 because of climate change, predominantly within their own countries but also across international borders. This article examines the emerging phenomenon of “environmental migration” against the backdrop of international refugee law and broader human rights frameworks. It first maps the diverse environmental scenarios that trigger displacement before analyzing the existing international legal landscape. Particular attention is paid to the contested terminology surrounding “climate refugees”, “environmental migrants” and “environmentally displaced persons” and to the protection gaps that arise from current categorizations. This article argues that, while existing norms on human rights, disaster risk reduction and internal displacement offer partial safeguards, they do not provide coherent legal status or systematic protection for people displaced across borders by climate-related harms. It concludes that climate-related displacement should be addressed through a combination of evolving human rights-based climate litigation, enhanced use of existing instruments and the progressive elaboration of specific normative frameworks. Full article

To solve the problems of high injection pressure and low water injection in an ultra-low-permeability reservoir, nanoemulsion was injected to reduce the surface interfacial tension, change the wettability, and achieve the purpose of depressurization. In this paper, the surface and interfacial tension, wettability properties, and particle size distribution characterization of nanoemulsion were determined, and the performance of nanoemulsion was evaluated by laboratory experiments such as core displacement. At the same time, the depressurize and augmented injection mechanism of the nanoemulsion was studied through a scanning electron microscope. The experiment shows that the nanoemulsion system has good compatibility with brine. With the increase in temperature, the surface and interfacial tension does not change, and there is no precipitation. And the system can reduce the oil–water interfacial tension to about 1 mN·m⁻¹ under the best conditions. By measuring the wettability angle of nanoemulsion at the concentration of 0.1% to 0.5%, which can adjust the wettability of the rock surface, the hydrophilicity is weakened. The depressurization performance of nanoemulsion under different injection rates, concentrations, and slug sizes was also compared through core displacement experiments, to provide reasonable experimental support for field operations. In the most reasonable case, the depressurization rate after using nanoemulsion can reach 16.78%. Full article

Compliant displacement amplification mechanisms are widely used in MEMSs and micro-actuated systems to enhance the limited stroke of micro-actuators. However, systematic integration of instantaneous center building block (IC-BB)-based conceptual design and structured post-synthesis optimization for symmetric single-input dual-output compliant displacement amplification mechanisms (SIDO-CDAMs) remains limited in the literature. In this work, a symmetric SIDO-CDAM is first conceptually synthesized using the IC-BB approach by employing only compliant dyad building blocks (CDBs), resulting in a mechanism that produces dual outputs in the same direction. The synthesized conceptual mechanism is subsequently realized with necessary geometric refinements and modeled to validate the conceptual design. A two-stage post-synthesis optimization framework is then proposed to enhance geometrical advantage (GA) while reducing stiffness. In Stage-1, Taguchi design of experiments combined with analysis of variance (ANOVA) is used to screen design parameters, identify the dominant factor, and fix it at its optimal level to eliminate masking effects. In Stage-2, a reduced Taguchi design integrated with gray relational analysis (GRA) is applied for multi-response optimization based on finite element analysis (FEA). Regression models and FEA-based confirmation tests are employed to validate the optimized design. The results demonstrate a significant improvement in displacement amplification with a simultaneous reduction in stiffness compared to the base design. The proposed IC-BB-based conceptual synthesis, coupled with structured post-synthesis optimization, provides a robust and computationally efficient framework for the development of micro-actuation and precision engineering applications. Full article

Geosynthetics-reinforced soil technology represents an innovative reinforcement method for calcareous sand foundations and revetment engineering in coral reef areas. The interaction response at the reinforced soil interface directly influences the safety and stability of reinforced soil structures. However, research on the interaction mechanisms between geosynthetics and calcareous sand interfaces remains insufficient. Therefore, this paper investigates the effects of different normal stresses and various interface types on the shear characteristics of the geosynthetics–calcareous sand interface through a series of large-scale monotonic direct shear tests. By integrating statistical damage theory and accounting for the influence of residual strength, we establish the constitutive relation for interface damage. The results indicate that the shear stress–displacement curves for both the geosynthetics–calcareous sand interface and the unreinforced calcareous sand exhibit softening behavior. Furthermore, the relationship between the interface shear modulus and horizontal displacement for the geogrid–calcareous sand and unreinforced calcareous sand adheres to a power function model, while the relationship for the geotextile–calcareous sand follows a logarithmic function model. In the structural design of geosynthetics-reinforced calcareous sand, it is crucial to consider the influence of residual shear strength on structural stability. This study proposes a statistical damage constitutive model that accounts for the strain-softening characteristics of the geosynthetics–calcareous sand interface, while also considering the impact of residual strength. The findings provide a theoretical basis for the stability analysis of geosynthetics-reinforced calcareous sand structures in coral reefs with significant engineering implications for island reef construction, coastal development, and bank slope protection projects. Full article

Polyurethane cement (PUC) is a high-performance composite that combines the high toughness of polymers with the durability of cementitious materials, showing potential in the field of structural strengthening. However, when used alone, its crack confinement capability is limited. To investigate the strengthening effect of wire mesh–polyurethane cement (WM-PUC) composite on the shear performance of damaged reinforced concrete (RC) beams, static loading tests were conducted on four RC beams. All strengthened beams were preloaded to induce initial damage and subsequently retrofitted on the sides using the two composite materials. Their shear performance was evaluated through single-point monotonic loading. The failure modes, load–displacement curves, shear capacity, and crack development patterns of the strengthened beams were analyzed in detail. The experimental results indicated that after strengthening with PUC and WM-PUC, the shear capacity of the damaged beams was effectively enhanced. The ultimate loads of the damaged beams strengthened with PUC and WM-PUC were 360 kN and 390 kN, respectively, representing increases of 12.5% and 21.88% compared to the unstrengthened beam. Compared to the PUC-strengthened beam, the ultimate load of the WM-PUC-strengthened beam increased by 8.3%, indicating that the incorporation of wire mesh further enhanced the strengthening effectiveness of the polyurethane cement composite. In terms of crack control, WM-PUC strengthening was more effective than PUC strengthening in restraining the initiation and propagation of diagonal cracks. The findings demonstrate that WM-PUC composite exhibits favorable applicability for the shear strengthening of damaged RC beams, with overall performance superior to that of PUC-only strengthening, thereby providing a technical reference for high-performance shear strengthening of existing concrete structures. Full article

Soft story irregularity poses a critical seismic risk to existing building stocks. While current seismic codes define stiffness irregularity factors to detect this vulnerability, they are typically evaluated based solely on initial elastic properties. This study investigates the evolution of these code-defined factors (ASCE/SEI-7, UBC, NBC, TBEC-2018, and BSL) within the post-elastic range to examine how structural damage affects soft story irregularity. The methodology comprises two phases: a low-strength RC plane frame (Case A) and a parametric study on a 3D RC building with incrementally increased ground story heights (Case B). Nonlinear pushover analyses were conducted to track the variation in irregularity factors at each pushover step and examined graphically. Results demonstrate that soft story behavior is not a static characteristic; irregularity factors deteriorate significantly as plastic hinges form. Crucially, several models that initially satisfied code limits in the elastic range eventually exceeded irregularity thresholds under inelastic behavior. This indicates that relying solely on initial stiffness may mask latent irregularities emerging during seismic actions. Consequently, to capture the true severity of soft story mechanisms, it is recommended that stiffness irregularity factors be evaluated at target displacement levels corresponding to the design earthquake. Full article

This study tested quarter-scale adobe masonry walls under monotonic in-plane loading, considering the effect of water content at the foundation–wall interface, fiber type, and openings (i.e., door, window). Seven walls were constructed with unstabilized adobe bricks containing either cut straw or sisal fibers and mud mortar. Gravimetric water content (w_b) at the foundation–wall interface (i.e., wall base) varied by test wall, ranging from 2.4 to 4.9% by dry mass. The walls were instrumented to measure in-plane and out-of-plane displacements and vertical deflections during the load tests. Greater water contents at and near the wall base shifted cracking toward the lower courses and along the foundation–wall interface; however, the peak load capacity did not vary significantly with w_b but was strongly influenced by crack trajectory, including whether cracking diverted into the foundation or propagated rapidly along the foundation–wall interface. Peak loads ranged from 1928 N (433 lb) to 6517 N (1465 lb). Fiber type influenced deformation behavior of the walls, with sisal-brick walls generally developing larger vertical deflections and, in some instances, larger peak in-plane displacements than straw-brick walls. Window and door openings altered crack initiation and propagation by concentrating cracking at opening corners and producing segmented mechanisms, increasing in-plane displacements in some cases, but still sustaining comparatively large peak loads. Full article

Background/Objectives: The rapid expansion of New Approach Methodologies (NAMs) is transforming oral biopharmaceutics by offering mechanistically rich, human-relevant tools that can reduce reliance on animal testing while improving translational confidence. Regulatory agencies, including the Food and Drug Administration (FDA) and the European Medicines Agency (EMA), are increasingly open to NAM-generated evidence, provided that methods are fit-for-purpose and scientifically justified. This review synthesizes current advances and evaluates how NAMs can be integrated across drug-development stages to enhance the prediction of oral absorption, formulation performance, and regulatory decision-making. Methods: A comprehensive literature review was conducted across classical and emerging methodologies, including in vitro permeability and solubility models, organoids, organ-on-a-chip (OoC) systems, machine learning frameworks, and mechanistic approaches such as the physiologically based pharmacokinetic (PBPK) and biopharmaceutics (PBBM) models. Emphasis was placed on physiological relevance, predictive performance, validation status, and regulatory applicability. Results: Classical tools remain essential for the Biopharmaceutics Classification System (BCS)-based biowaivers and risk-based assessments, yet they often lack physiological fidelity. NAMs provide enhanced representation of intestinal architecture, hydrodynamics, transporter activity, and metabolism. Organoids and microphysiological systems generate high-quality permeability and metabolic data, while computational NAMs enable scalable prediction of ADME properties and formulation behavior. When integrated into PBPK/PBBM models, these methods have great potential in predicting in vivo performance in humans. Evidence demonstrates that NAMs can refine, reduce, and, in specific contexts, replace animal studies without compromising scientific rigor. Conclusions: NAMs complement, rather than displace, classical biopharmaceutic tools, enabling a more mechanistic, human-centered, and ethically responsible framework for drug development. Their effective implementation will depend on continued validation, standardization, and regulatory harmonization as the field transitions toward fully NAM-supported biopharmaceutical assessment. Full article

To clarify the migration characteristics of overlying strata during backfill mining of close-distance coal seams, the 3306 working face of Chaili Coal Mine was taken as the engineering background, and similar-material simulation, fracture-fractal analysis, and FLAC3D numerical simulation were carried out under an 85% backfill ratio. The study reveals the coordinated inherited and reactivated evolution of fractures, displacement, and stress in the overlying strata during successive extraction of the upper and lower seams. The results indicate that the movement of the overlying strata shows pronounced stage dependence and inheritance. After extraction of the upper No. 3 coal seam, the response of the overlying strata evolves from local disturbance to overall structural readjustment, with continuous bending subsidence and progressive fracture propagation, and ultimately forms a two-belt structure. During extraction of the lower No. 3 coal seam, the response develops on the basis of the structural state formed after upper-seam mining and is manifested mainly by the reactivation and readjustment of the pre-existing fracture network and displacement field. The fractures undergo a dynamic process of generation, development, closure, redevelopment, and reclosure. Compared with upper-seam mining, lower-seam mining produces a larger vertical displacement and a weaker stress response. The maximum vertical displacement in-creases from 478.85 mm to 1019.76 mm, whereas the stress concentration coefficient of the immediate roof decreases from 2.01–2.03 to 1.93–1.99. Under the geological and mining conditions considered in this study, the 85% backfill ratio maintains overall bending subsidence of the overlying strata and alleviates strata pressure manifestations during lower-seam extraction. These findings provide a reference for strata control under similar backfill mining conditions. Full article

A collinear holographic data storage system stores two-dimensional information in the three-dimensional spatial domain of the medium, offering features such as high speed, high density, and long lifespan, making it a promising technology for the future of data storage. However, a collinear holographic data storage system is limited by the alignment error of the optical system and is also sensitive to environmental noise and external interference, which increases the reading error. When recording and reading holographic storage materials, synchronous marks are used for positioning to correct data misalignment. Therefore, optimizing synchronous mark design of data pages is crucial for improving storage stability and reading accuracy. In this paper, we propose a star-shaped synchronous mark to replace the square-shaped synchronous mark, which improves the holographic grating coupling efficiency. Experimental results show that this method enhances reconstruction strength and reduces reading errors caused by external factors. The star-shaped synchronous mark achieves a better spectral match with the reference pattern, yielding a stronger diffracted signal. Experimental results show that this method reduces the bit error rate by approximately 25% compared to square-shaped synchronous marks under displacement multiplexing. Full article

Addressing the problem of limited methane (CH₄) recovery degree under different production conditions in a target low-permeability carbonate gas reservoir, this study intends to further investigate the effect of carbon dioxide (CO₂) injection on enhanced gas recovery (EGR). A group of long-core physical simulation experiments of CO₂ injection for EGR was adopted. Field injection–production parameters were converted to laboratory conditions through similarity criteria to simulate the actual production process of gas wells. Systematic experiments on CH₄ depletion and CO₂ displacement were carried out under different irreducible water saturation, gas injection timing pressure and injection rates. The influence laws of each key parameter on the CO₂ breakthrough time and CH₄ recovery degree were analyzed emphatically, and the optimal injection–production scheme was obtained. For the target low-permeability carbonate gas reservoir (permeability < 1 mD), the optimal CO₂ injection scheme is as follows: for layers with medium to high irreducible water saturation (≥40%), CO₂ injection at a rate of 36,000 m³/d per well after the end of stable production (formation pressure > 7.38 MPa) can increase the CH₄ recovery degree by 3–5%. This study provides experimental support for the optimization of CO₂ injection schemes for enhanced recovery in gas reservoirs and the adjustment of gas reservoir development strategies under different irreducible water saturation conditions. Full article

An integrated numerical method is proposed for analyzing the nonlinear seismic response of near-fault building clusters, comprising three algorithms: (1) a structural investigated lump algorithm for elastoplastic dynamic response of structure; (2) a connecting investigated lump algorithm for bidirectional wave propagation between the site and elastoplastic building clusters; (3) a geomedia investigated lump algorithm for seismic wave propagation with an improved viscoelastic constitutive model, which allows independent definition of P/S-wave quality factors to characterize geomedia attenuation. Validated for its capability in simulating site-city dynamic interaction problems via a shaking table test, the method is applied to study the seismic response of near-fault building clusters in Xichang City under a hypothetical M_w6.8 earthquake. It is shown that irrespective of whether shallow geological structures are considered, clusters (c2–c4) situated in rupture-forward surface area within ~1.5 km of the fault trace entered the elastoplastic stage, while others (c1, c5) remained elastic. Shallow geological structures may reverse locally hanging-wall/footwall effects of both near-fault structural seismic response and ground motion. A notable seismic-response characteristic of near-fault structures undergoing the elastoplastic stage is that the permanent structural motion displacement (PSMD) at the slab of a specific floor incorporates not only the non-zero permanent ground motion displacement (PGMD) but also the non-zero final structural residual displacement (FSRD) relative to the supporting ground. The developed method could provide support for seismic damage assessment, site selection, and structural optimization design of near-fault building clusters. Full article

The Ordos Basin hosts abundant lacustrine shale oil resources. Adequately retained hydrocarbons in source rocks, together with favorable mobility, are prerequisites for large-scale shale oil exploitation. Therefore, the quantitative characterization of retained hydrocarbon content and mobility is a core research focus in shale oil exploration and development. This study investigates Chang 7 shale with varying lithofacies and geochemical characteristics. Stepwise pyrolysis and pyrolysis gas chromatography–mass spectrometry (GC–MS) were applied to analyze retained hydrocarbons in different occurrence states, their compositions, and biomarkers. In addition, nuclear magnetic resonance (NMR) combined with CO₂ flooding experiments was conducted, and the collected products under different displacement pressures were analyzed using GC–MS. The aim was to quantitatively examine the variations in expelled oil volume, compositional differences during migration, and occurrence features of shale oil within reservoir micro-pores. The results show the following: (1) Organic-rich shale is characterized by higher proportions of light and medium hydrocarbons, lower heavy fractions, and elevated aromatic hydrocarbon content. In contrast, low-organic-carbon mudstone or siltstone contains more medium and heavy hydrocarbons, with lower light and aromatic fractions. The C13−/C14+ ratio increases with total organic carbon (TOC). (2) In black shale, oil displacement is mainly contributed by mesopores. At low pressures, oil expulsion is difficult and dominated by heavy hydrocarbons. When pressure reaches a threshold, the capillary-bound oil in micropores is released, increasing production and improving oil quality. Muddy siltstone shows higher displacement efficiency than black shale, with contributions from pores of all sizes. At low pressures, its expelled oil volume is larger and lighter than that of black shale. With increasing pressure, the oil yield rises significantly, and medium–large pores produce heavier fractions compared with micropores, likely because light hydrocarbons preferentially enter micropores and are less prone to dissipation. (3) The main controlling factors for shale oil enrichment include retained hydrocarbon content, mobile hydrocarbon fraction, fluidity, and engineering-related parameters. Thick shale layers with high organic matter abundance, high proportions of light–medium hydrocarbons, and favorable porosity–permeability conditions, as well as interbedded siltstone, are enriched in mobile hydrocarbons. Full article

This work explores the key capabilities of emerging sensing technologies in the context of Structural Health Monitoring (SHM) of civil infrastructures, aiming to contribute to research on integrated and intelligent systems for more accessible and efficient monitoring solutions. As a case study, it focuses on the analysis of the static and dynamic behavior of the Edgar Cardoso stay-cable bridge during its rehabilitation, using fully customized transducers and equipment. The developed system integrates sensors capable of measuring accelerations, displacements, and temperature, which are connected to an autonomous data acquisition and transmission network. A digital interface was also developed to store, process, and visualize the collected data, enabling remote access for subsequent interpretation and analysis. The main contribution of this research lies in the use of optimized wireless monitoring systems with extended autonomy. This is achieved by employing edge computing techniques to minimize energy consumption during data transmission, as well as by managing the sleep modes of the sensor nodes. At same time, a methodology was proposed for the automatic and real-time estimation of axial forces in cables. This approach relies on the use of innovative edge computing tools, combined with the taut string theory as a simplified modelling framework. The results confirm the effectiveness of the developed system in achieving long-term operation without compromising monitoring performance. In addition, the developed system enabled the identification of the structure’s dynamic properties, particularly natural frequencies. The temperature profiles in critical sections, as well as displacements in the expansion joint were also measured and evaluated. The results demonstrate the potential of customized sensing solutions as effective tools for the management, maintenance, and long-term preservation of strategic infrastructures. Full article