Search Results (595)

The rapid expansion of wireless connectivity has led to vast amounts of radio-frequency (RF) energy being continuously radiated into the environment, much of which is dissipated due to severe propagation losses. Recycling this otherwise wasted RF energy is, therefore, a critical enabler for energy-efficient and sustainable wireless systems. RF energy harvesting nodes and passive backscatter communication devices provide promising solutions by enabling battery-less or low-maintenance operation for future green networks. However, both paradigms suffer from fundamental limitations, including restricted communication range, near–far effects, and insufficient harvested energy at extended distances. This review examines how cooperative relays can address these challenges by harvesting ambient RF energy and assisting both information transfer and power delivery. From a communication perspective, we review cooperative backscatter communication and harvest-then-transmit (HTT) protocols, highlighting how multi-hop relaying significantly extends coverage and improves throughput for energy-constrained devices. Particular emphasis is placed on tag-to-tag (T2T) backscatter systems, relay-assisted architectures, decode-and-forward and amplify-and-forward protocols, and optimal multi-access time allocation strategies that mitigate the doubly near–far problem in passive networks. From an energy-transfer perspective, the review is structured around three pillars: wireless power transfer (WPT), multi-hop energy transfer (MET), and integrated charging-and-sensing frameworks. We discuss relay deployment and placement optimisation, UAV-enabled mobile energy relays, waveform and beam-forming design, and the transition from idealised linear harvesting models to practical nonlinear rectification models. Key practical constraints, such as regulatory limits, safety compliance, self-interference, protocol overhead, synchronisation, and imperfect channel knowledge, are systematically reviewed. The paper concludes by identifying the scalability limits of multi-hop cooperative systems, outlining how the joint optimisation of energy relaying and cooperative communication enables RF energy recycling for sustainable, low-carbon wireless networks and highlighting open challenges and future research directions. Full article

Introduction: The restoration of river connectivity through fishways is essential for the conservation of native freshwater fish, yet it may inadvertently facilitate the upstream spread of non-native invasive species. This trade-off is particularly relevant in Iberian river systems, where invasive cyprinids pose a growing ecological threat. Objective: In this study, we evaluated the potential for selective fish passage in a full-scale vertical slot fishway (VSF), aiming to promote native species movement while limiting invasive taxa. Methodology: Experimental trials were conducted with the common carp (Cyprinus carpio), a widespread invasive species, and the results were compared with those of the native Iberian barbel (Luciobarbus bocagei). Two fishway configurations were tested, both with high slope (15.2%) and high turbulence (volumetric power dissipation >150 W m⁻³), differing in water depth (0.55 m and 0.80 m). Fish passage performance was assessed through behavioural metrics, including motivation to attempt passage, ascent success, and transit time, using a time-to-event framework. Hydrodynamic conditions were characterised through computational fluid dynamics modelling. Results: The results revealed marked interspecific differences. Common carp exhibited significantly lower motivation to initiate passage and extremely limited success: no individuals ascended the shallower configuration, and only one ascended the deeper configuration. In contrast, Iberian barbel demonstrated high motivation and passage success under both configurations, particularly in more turbulent conditions. Conclusions: These findings suggest that manipulating key hydraulic parameters can create selective passage conditions that favour rheophilic native species while hindering limnophilic invasive taxa. This ecohydraulic approach offers a promising strategy to reconcile the restoration of longitudinal connectivity with the control of biological invasions. Nevertheless, further research under field conditions and across a broader range of species is required to validate and generalise these findings. Full article

Bandpass filters based on through-silicon-via (TSV) interposers offer advantages such as compact footprint, excellent radio frequency (RF) performance, simplified processing, and low cost. However, as power densities in three-dimensional (3D) integrated circuits continue to rise, thermal management has become a critical performance bottleneck. In this work, we present a TSV-based bandpass filter design where the TSVs feature annular Cu conductors with carbon nanotube (CNT) cores. The annular Cu structure provides the required vertical electrical connectivity, while the high-thermal-conductivity CNT core facilitates inter-layer heat dissipation. RF simulations confirm that the RF characteristics of the filter remain comparable to those of filters based on conventional TSVs with Cu-pillar conductors or TSVs with annular Cu conductors and polymer cores such as benzocyclobutene (BCB). In addition, multiphysics simulations demonstrate that the proposed filter exhibits a maximum steady-state temperature of only 89.1 °C with a 5 W constant heat source attached to the interposer surface and a heat sink at the bottom side, presenting an efficient reduction compared to the other two types. The filter also shows reduced thermally induced surface deformation, confirming the thermal benefits of the CNT cores. Furthermore, comprehensive parametric analyses involving the influences of critical TSV structural parameters on the TSV-based capacitors and inductors are performed, providing guidelines for customized filter design. We believe the proposed design highlights a promising pathway for addressing the thermal management challenges in high-density RF integrated microsystems. Full article

In order to clarify the controlling effects of tectonic activity on hydrocarbon migration efficiency in the Permian–Triassic strata of the Luzhou area, Sichuan Basin, this study takes faults as the research objective. Using 3D seismic data, tectonic evolution records, and single-well test data, we systematically analyze the geometric characteristics, activity phases, classification by grade and type, and reservoir-controlling effects of faults. The results show that a total of 843 reverse faults have been identified in the study area. The major faults are distributed in a NE-SW trend, with eight planar combination styles developed, and the main cross-sectional styles are back-thrust and “Y”-shaped types. The faults experienced four phases of tectonic activity: Caledonian, Hercynian, Indosinian, and Yanshan–Himalayan. Among these, the Indosinian phase is the key formative phase, effectively connecting the source rocks and reservoirs. The faults are classified into three grades and four categories: source-connected faults, reservoir-modifying faults, damaging faults, and source-connected and damaging faults. Migration efficiency is jointly controlled by fault grade, activity phases, and the penetrated formations. Among them, third-order source-connected faults formed during the Indosinian phase exhibit the highest migration efficiency, while first-order damaging faults formed during the Yanshan phase tend to cause hydrocarbon dissipation. This study can provide a reference for hydrocarbon exploration and the prediction of favorable areas in the Luzhou area. Full article

Rockburst is one of the major geological hazards in the construction of deep-buried and high-geotemperature tunnels. Using triaxial compression tests and acoustic emission (AE) techniques, this paper conducts a preliminary exploratory investigation on the deformation and failure characteristics, mechanical parameters, acoustic emission responses and energy evolution laws of typical rockburst-prone rocks under confining pressures of 10–30 MPa and temperatures of 100–250 °C. The results show that within the research scope, sandstone exhibits brittle characteristics including compaction, linear elasticity, crack initiation and propagation, stable crack propagation stage, accelerated crack propagation stage, and stress drop stage. Within a certain range, peak strength and damage strength increase with the rise in confining pressure and temperature. The elastic modulus increases with rising confining pressure. The damage point may be the critical point of energy conversion and acoustic emission activity. After damage, the work done by external forces is mainly converted into dissipated energy. With the intensification of surrounding rock damage, the ratio of elastic strain energy to total energy gradually decreases, while the ratio of dissipated energy to total energy gradually increases. Acoustic emission activity increases significantly at the damage point and reaches its peak at the peak strength. The cumulative acoustic emission ring count and cumulative energy increase slowly before the peak and grow rapidly after the peak. Under thermo-mechanical action, new cracks in sandstone preferentially initiate along grain boundaries, and the inconsistent deformation between grains will promote the formation of transgranular cracks. The connection, convergence and final penetration of cracks lead to sample failure. The elevation of temperature and confining pressure can enhance the bearing capacity of sandstone, indicating that a high-temperature and high-stress environment may be conducive to the occurrence of rockbursts. The research results provide scientific support for an in-depth understanding of the mechanical behavior and instability risk of rockburst in deep-buried and high-geotemperature tunnels, and can provide a theoretical basis for rockburst prevention and control of high-geotemperature tunnels of the CZ Railway. Full article

Hybrid carbon nanotube–fullerene architectures provide a controllable setting in which to study irreversibility and information flow in strongly structured quantum environments. We analyze entropy generation in a platform where paramagnetic endohedral fullerenes (PEFs), such as N@C₆₀ and P@C₆₀, are encapsulated inside a suspended carbon nanotube (CNT) resonator, such that selected multi-level PEF spin states define an effective qubit coupled to quantized CNT flexural modes. Motivated by prior work on fullerene-filled CNTs, on spin–phonon manipulation in suspended nanotubes, and on exact phase-space propagators for damped driven oscillators, we formulate a hybrid open-system description that combines a driven quantum Brownian description of the CNT resonator with an effective Jaynes–Cummings type spin–vibrational interaction. The resonator dynamics are represented in phase space through the Wigner function, whose time evolution can be written analytically in terms of the initial Wigner distribution and a Gaussian propagator. This representation makes it possible to separate drive-induced phase space displacement, diffusion, and damping, and to connect these features directly to entropy flow. The coupled spin–mechanical dynamics are then embedded in a Lindblad quantum master equation that includes mechanical damping, spin relaxation, pure dephasing, and thermally activated excitation channels. Within this framework we derive the entropy balance equation—identifying entropy flux and non-negative entropy production—and examine how hybridization between the molecular spin and the nanotube vibration redistributes irreversibility between coherent exchange and dissipative channels. We show that spin–phonon coupling enhanced by a magnetic field gradient, resonant driving, and moderate thermal occupation can produce identifiable crossovers between entropy–production regimes dominated by the oscillator and those dominated by the spin. The resulting framework provides a quantitative basis for using CNT–PEF hybrids as nanoscale platforms for studying nonequilibrium quantum thermodynamics, decoherence, and information loss in structured vibrational environments. Full article

This study experimentally investigates the structural behavior of hexagonal- and square-shaped composite specimens subjected to vertical compression, vertical tension, and diagonal tension loading. The specimens were fabricated using four- and six-layer alkali-resistant (AR) glass textile reinforcements embedded in a modified cementitious mortar via pull, pour, and roll manufacturing techniques. The mechanical performance of polyvinyl alcohol (PVA) fiber-reinforced composite connectors and steel clamp-type elements was also evaluated at the joints of hexagonal specimens under vertical tension and lateral shear loading. The results show that increasing the number of textile layers significantly enhances structural performance. A 50% increase in textile layers improved load-carrying capacity by up to 56% in compression, 104% in tension, and 216% in diagonal tension. Corresponding increases of approximately 20–42% in ductility and up to 266% in energy dissipation capacity were observed. No failure occurred in the connecting elements, confirming their adequate stiffness, strength, and ductility. In addition, validated three-dimensional finite element models were developed to simulate the response of the hexagonal specimens. Overall, the proposed system demonstrates strong potential for applications such as infill walls, cladding, and sandwich panels due to its favorable strength, ductility, and energy absorption capacity. Full article

Directional long-borehole hydraulic fracturing is an important technique for controlling rockbursts induced by hard roofs. Its effectiveness depends primarily on whether fracturing-induced damage can modify the roof-bearing structure and thereby regulate stress concentration and elastic strain energy accumulation in the coal-rock mass ahead of the working face. However, existing numerical simulations commonly rely on predefined weakened zones or empirical parameter reduction, which makes it difficult to represent the spatial heterogeneity and mechanical evolution of rock damage during field hydraulic fracturing. Taking the 2803 goaf-side working face in Hetaoyu Coal Mine as the engineering background, this study proposes a microseismic-data-driven method for characterizing hydraulic fracturing-induced damage and incorporates it into a FLAC3D finite-difference model. The stress field, elastic strain energy field, and damage distribution ahead of the working face are compared under non-fractured and hydraulically fractured conditions. In the proposed method, the energy of fracturing-induced microseismic events is converted into the Benioff strain of numerical zones according to the attenuation law of microseismic wave propagation, and the corresponding rock damage variable is then calculated using a Weibull damage model. The fracturing-damaged rock mass is further represented by weakening the elastic modulus, cohesion, and friction angle, together with the stochastic generation of strongly damaged zones. The results show that, without hydraulic fracturing, the hard roof maintains a strong, continuous bearing capacity, resulting in a continuous lateral abutment stress concentration zone and a high elastic strain energy accumulation zone ahead of the working face and near the goaf-side boundary. After hydraulic fracturing, a patchy and locally connected high-damage weakening zone forms in the target roof strata. This damaged zone cuts the original continuous load-transfer structure through which the hard roof concentrates load toward the goaf side, reduces the extent of high-stress and high-energy zones in the coal seam, and induces an asymmetric adjustment of the dominant mining-induced energy release zone from the goaf side toward the solid-coal side. These simulation results agree well with the field observation that microseismic activity is mainly concentrated near the roadway on the solid-coal side. The study indicates that the rockburst-control mechanism of directional long-borehole hydraulic fracturing is not limited to simple overall stress dissipation. A key finding is that the fracturing-induced heterogeneous damage zone effectively interrupts the continuous load-transfer and energy-storage paths on the goaf side. This induces an asymmetric spatial redistribution of the mining-induced energy field from the goaf side toward the solid-coal side, thereby mitigating the high static-load and high-energy-storage state ahead of the working face. Full article

Effective thermal management is crucial for the performance, thermal safety, and lifespan of lithium-ion batteries in electric vehicles (EVs). Thermal management strategies are essential for preventing overheating, thermal imbalance, and the associated risk of thermal runaway. Nanofluids are emerging and attracting considerable attention as potential coolants for high-power energy storage and electronics systems. This review updates and summarizes the most recent advances in nanofluid-based cooling strategies for battery thermal management systems (BTMSs) over the past five years, emphasizing their implications for battery thermal safety. Three main nanofluid-based cooling strategies have been evaluated in depth, including nanofluid-based indirect liquid cooling, nanoparticle-enhanced PCM cooling, and nanofluid-based heat pipe cooling. Various nanofluid formulations, including mono, hybrid, and ternary nanofluids, have been considered and evaluated for their heat dissipation under high charge/discharge and abuse-relevant conditions. Thermal and hydraulic performance characteristics, including maximum temperature, maximum temperature difference, and pressure drop, have been comprehensively evaluated for different nanofluid-based cooling strategies. The findings demonstrated that nanofluids significantly improved heat transfer rates and enhanced temperature control efficiency. In particular, hybrid and ternary nanofluids exhibit superior thermal performance and effectively suppress the escalation of safety-critical temperatures. Beyond summarizing cooling performance, this review further discusses the role of nanofluid-based cooling strategies as functional thermal-control layers within intelligent BTMS architectures. Particular attention is given to their compatibility with sensing networks, BMS-/VCU-level supervisory control, predictive thermal models, actuator responsiveness, fault-warning algorithms, and long-term reliability under realistic driving and fast charging conditions. Therefore, this review provides architecture-oriented insights for developing safe, energy-efficient, and control-ready BTMSs for next-generation high-power and connected EVs. Full article

Compact finite difference schemes approximate spatial derivatives through implicit relations between neighboring grid points. Despite using compact stencils and relatively simple algebraic structures, these schemes achieve high-order accuracy and spectral-like resolution, reducing dispersion errors while maintaining low numerical dissipation. These properties make them particularly attractive for problems requiring accurate spatial derivatives and computational efficiency, such as wave propagation, aeroacoustics, and turbulent flow simulations. This review presents the main ideas behind compact finite difference schemes, including their derivation from Taylor expansions and Padé approximations, their accuracy properties, and their resolution characteristics through modified wavenumber analysis. The manuscript is intended as a review and practical synthesis, rather than as the proposal of a new numerical scheme, and aims to connect the theoretical construction of compact schemes with their numerical behavior, practical implementation, and representative applications. To support reproducibility, we provide a fully documented open-source Python 3.11 notebook with a reference implementation of the schemes discussed in the paper. The examples include first- and second-order derivative calculations and representative one- and two-dimensional boundary-value problems, including Helmholtz-type equations. Finally, we survey applications across computational fluid dynamics, acoustics, geophysical flows, structural mechanics, biology, electromagnetism, and quantitative finance. Full article

Extensive research has been conducted on vehicle queuing and dissipation near signalized intersections. However, existing prediction methods for vehicle departure time primarily rely on assumptions of steady-state homogeneous traffic flow, utilizing shockwave theory and vehicle kinematic modeling. These methods encounter challenges in addressing traffic uncertainties during queue formation and dissipation, particularly in scenarios involving multiple lanes. This paper introduces a novel approach by leveraging unmanned aerial vehicle (UAV) trajectory data to construct fleet state features and proposes a prediction method for tail vehicle departure time based on Gaussian process regression. The objective of this method is to optimize the green light crossing time window and eco-driving trajectory for connected vehicles at signalized intersections. The findings reveal that the departure time of the tail vehicle within a specified distance adheres to a Gaussian process, demonstrating the applicability of Gaussian process regression for departure time prediction modeling. The effectiveness of the proposed method was validated using a field-measured dataset collected from three typical multi-lane signalized intersections. Notably, compared to four benchmark models (linear regression, decision trees, multilayer perceptron neural networks, and eXtreme Gradient Boosting—XGBoost), the mean absolute percentage error (MAPE) was reduced by an average of 5.146% on the test set under a random 70/30 split. Additionally, a robustness assessment demonstrates that the proposed model performs well, albeit slightly less effectively than the XGBoost model. We emphasize that the conclusions are drawn for the studied intersections; generalization to unseen intersections requires further validation with cross-site data. Full article

Coupling beams are critical connecting components in coupled shear wall systems and core tube structures. At the same time, they play an important role when the structure is subjected to an earthquake. Plate-reinforced composite (PRC) coupling beams exhibit superior comprehensive performance in terms of bearing capacity, deformation performance, energy dissipation capacity, and construction efficiency. However, research on PRC coupling beams remains limited both domestically and internationally. To better describe the structural response of steel plate–concrete composite coupling beams, this study collected existing experimental data. The beams had a small span-to-depth ratio. The loading was cyclic. The study normalized the skeleton curves of each specimen. The span-to-depth ratio ranged from 0.9 to 2.5. The plate ratio ranged from 3% to 5%. For these beams, preliminary skeleton curve fitting equations are proposed. The equations are based on existing data. The equations apply to two types of composite coupling beams. One type uses a steel plate and ordinary concrete. The other type uses a steel plate and fiber concrete. These equations are derived using a trilinear model and linear fitting tools. Furthermore, restoring force models for steel plate–conventional concrete and steel plate–fiber concrete composite coupling beams with a small span-to-depth ratio are proposed. Comparative analysis shows that each model captures the hysteretic response of PRC coupling beams with acceptable accuracy in the elastic and decline phases, while the elastic–plastic stage is suitable only for trend prediction. It should be noted that the proposed models are preliminary engineering approximations primarily applicable within the following ranges: a span-to-depth ratio of 0.9~2.5, a plate ratio of 3~5%, concrete strength of C30~C50, a longitudinal reinforcement ratio of 0.86~2.23%, a stirrup ratio of 0.56~0.63%, and a steel plate thickness of 6~10 mm. For configurations significantly outside these ranges, additional experimental validation is required. Full article

To promote the industrial development of reinforced concrete engineering and enhance the construction quality of prefabricated buildings, an innovative partial prefabricated construction method is proposed in this paper, namely the prefabricated reinforced cage–cast in situ concrete (PRC-CISC) structure with an innovative steel bar connection technology. The connection techniques, including direct thread rolling of steel bars and hot-forged sleeves, are adopted. With the design axial compression ratio and the layout of couplers in the reinforcement cage as the main parameters, quasi-static tests are carried out to investigate the failure mode, seismic behavior, and mechanical mechanism of couplers of PRC-CISC columns. The results indicate that all specimens present typical compression–bending failure with plump hysteretic curves, gradual stiffness degradation, good ductility, and energy dissipation capacity. The new couplers can effectively satisfy the seismic performance requirements of PRC-CISC columns. With the increase in axial compression ratio, the bearing capacity rises while ductility decreases, and the stress of longitudinal bars increases. The layout of couplers exerts a controllable influence on the mechanical and deformation performance of specimens. The steel stress in the core stress region of PRC-CISC columns shows a bilinear distribution with stress concentration at both ends of the sleeves, which is related to the material difference in couplers. Finally, two “non-equal” calculation methods (plastic hinge model and fiber model) are established based on experimental results and finite element analysis, forming a systematic calculation theory for the new material–new technology–new structure system. The research provides important references for the engineering application of such structures. Full article

The construction of single-story industrial halls in high-seismicity regions requires reliable beam-to-column connections to ensure adequate structural stiffness and strength. This paper investigates the emulative performance of a rigid precast beam–column connection utilizing threaded couplers and grouted corrugated steel sleeves. An experimental pro-gram was conducted on five scaled specimens—one monolithic reference and four pre-cast—subjected to quasi-static cyclic loading. The objective was to verify if the precast system achieved emulative behavior. Experimental results confirm this goal was fully achieved: the precast specimen exhibited a maximum recorded force nearly identical to the value recorded for the monolithic reference. Furthermore, the total dissipated energy for the precast joint had only a marginal 2.6% difference from the monolithic reference. Results demonstrate that the proposed solution provides emulative behavior consistent with monolithic casting. Specifically, the specimens achieved plastic deformation capacities exceeding 3%, surpassing current seismic design code requirements. While smaller diameter rebars (D14) experienced tensile failure at approximately 3% to 4% drift due to strain localization, specimen with larger D25 bars reached 4% drift without major damage. This paper concludes that the connection is suitable for seismic applications provided large diameter rebars (≥20 mm) are used. Full article

We develop an information-geometric framework for describing quantum state-update processes associated with measurement and statistical distinguishability. The approach is based on the quantum relative entropy and the quantum Fisher information metric, which together induce a natural Riemannian geometry on the manifold of quantum states. Using the second-order expansion of relative entropy, we show how the Fisher metric governs the local structure of distinguishability between nearby states and defines a corresponding thermodynamic length. This geometric structure provides an effective description of finite quantum state transitions in terms of fluctuation geometry and information-space distance. The formalism is applied to thermal two-level systems and harmonic oscillator states, illustrating how the Fisher metric encodes susceptibilities, fluctuations, and geometric transition costs. We also discuss the relation between thermodynamic length, dissipation bounds, and optimal paths in state space. Within this framework, wave function collapse is interpreted not as a microscopic dynamical mechanism, but as an effective state-update process that admits a geometric characterization in the manifold of density operators. The resulting perspective unifies concepts from quantum information theory, thermodynamics, and differential geometry within a common operational framework based on statistical distinguishability. Possible connections with quantum speed limits, entanglement geometry, and holographic relations between relative entropy and gravitational dynamics are briefly discussed. Full article