Search Results (5,032)

This article discusses the fundamental limitations of Light Fidelity (Li-Fi) systems, an emerging visible light communication technology that is constrained by line-of-sight dependency and optical attenuation. Unlike existing adaptive modulation approaches that focus solely on improving signal processing, we present an integrated framework that combines three key contributions: (1) an adaptive modulation optimization algorithm that selects among OOK, PAM, and OFDM schemes based on instantaneous signal-to-noise ratio thresholds, achieving a 30–40% range extension compared to fixed modulation references; (2) a method for spatial optimization of access points (APs) using the L-BFGS-B algorithm to determine the optimal location of APs, taking into account lighting constraints and coverage uniformity; and (3) comprehensive system-level modeling incorporating shot noise, thermal noise, inter-symbol interference, and dynamic shadowing effects for realistic performance evaluation. Through extensive simulations on multiple room geometries (6 m × 5 m to 20 m × 15 m) and AP configurations (one to six APs), we demonstrate that the proposed adaptive system achieves an average throughput 60% higher than that of fixed OOK, while maintaining 98.7% coverage in a 10 m × 8 m environment with two optimally placed APs. The framework provides practical design guidelines for Li-Fi deployment, including an analysis of computational complexity $O(M\times N)$ for coverage assessment, $O(I\times D^3)$ for access point optimization) and a characterization of convergence behavior. A comparative analysis with state-of-the-art techniques (optical smart reflective surfaces, machine learning-based blockage prediction, and Li-Fi/RF hybrid configurations) positions our lightweight algorithmic approach as suitable for resource-constrained deployment scenarios, where system-level integration and practical feasibility take precedence over innovation in individual components. Full article

Smart microgrids are localized energy systems that integrate distributed energy resources, such as photovoltaics (PVs) and battery storage, to optimize energy use, enhance reliability, and minimize environmental impacts. This paper investigates the operation of a smart microgrid installed at the Hellenic Mediterranean University (HMU) campus in Heraklion, Crete, Greece. The system, consisting of PVs and battery storage, operates under a zero feed-in scheme, which maximizes on-site self-consumption while preventing electricity exports to the main grid. With increasing PV penetration and growing grid congestion, this scheme is an increasingly relevant strategy for microgrid operations, including university campuses. A properly sized PV–battery microgrid operating under zero feed-in operation can remain financially viable over its lifetime, while additionally it can achieve significant environmental benefits. The study performed at the HMU Campus utilizes measured hourly data of load demand, solar irradiance, and ambient temperature, while PV and battery components were modeled based on real technical specifications. The study evaluates the system using financial and environmental performance metrics, specifically net present value (NPV) and annual greenhouse gas (GHG) emission reductions, complemented by sensitivity analyses for battery technology (lead–carbon and lithium-ion), load demand levels, varying electricity prices, and projected reductions in lithium-ion battery costs over the coming years. The findings indicate that the microgrid can substantially reduce grid electricity consumption, achieving annual GHG emission reductions exceeding 600 tons of CO₂. From a financial perspective, the optimal configuration consisting of a 760 kWp PV array paired with a 1250 kWh lead–carbon battery system provides a system autonomy of 46% and achieves an NPV of EUR 1.41 million over a 25-year horizon. Higher load demands and electricity prices increase the NPV of the optimal system, whereas lower load demands enhance the system’s autonomy. The anticipated reduction in lithium-ion battery costs over the next 5–10 years is expected to provide improved financial results compared to the base-case scenario. These results highlight the techno-economic viability of zero feed-in microgrids and provide valuable insights for the planning and deployment of similar systems in regions with increasing renewable penetration and grid constraints. Full article

Ultra-low latency communication is fundamentally required to reduce end-to-end (E2E) latency related to the transportation of time-critical or time-sensitive traffic in 5G networks. Time-sensitive networking has significant prospects in factory automation and Industrial Internet of Things (IIoT) as a key technology that can provide low-latency, highly reliable, and deterministic communications over Ethernet, whereas IETF deterministic networking (DetNet) seeks to provide a complementary network layer to support ultra-low latency communications. DetNet, as standardized in the IETF, provides time-sensitive characteristics that assure extremely low packet loss and latency for ultra-reliable low-latency communications. This study develops a novel framework to enable 3GPP support for DetNet functionalities. First, the proposed framework seeks to support IP-based DetNet traffic and urgent data transmission in the network overload conditions of 3GPP 5G systems. Additionally, the proposed design supports DetNet service connectivity between non-DetNet and DetNet service areas. Based on simulation results, the proposed framework can guarantee deterministic latency requirements and critical data transmission for DetNet compared with conventional approaches. The proposed scheme can achieve more effective performance for moving DetNet devices. Full article

The decarbonisation of the construction sector represents a central pillar of sustainable development strategies, contributing simultaneously to climate change mitigation, energy efficiency, energy security, and long-term socio-economic resilience. In this context, the European regulatory framework increasingly recognises the role of digitalisation and smart technologies in improving building performance beyond static energy efficiency indicators. The Smart Readiness Indicator (SRI), introduced in Energy Performance of Buildings Directive IV (EPBD), is designed to evaluate a building’s ability to optimise energy usage, adapt to the needs of its occupants, and interact intelligently with energy networks through automation and control systems. However, the scientific literature has only partially explored its potential contribution to sustainability-oriented decision-making and decarbonisation governance. This study adopts a conceptual and methodological research approach to investigate the role of the SRI as a sustainability-oriented assessment and governance tool for building decarbonisation. The paper develops a multi-scale analytical framework based on a structured synthesis of the scientific literature, European policy documents and evidence emerging from national SRI test phases. The framework systematically links smart readiness functionalities with digital modelling tools, automation systems, and decarbonisation objectives across building, system, and policy levels. The results highlight that the SRI can be interpreted not only as a descriptive rating scheme, but also as a strategic instrument for assessing sustainability, capable of supporting environmentally, economically, and operationally sustainable decision-making in the built environment. This study contributes to the advancement of sustainability assessment tools that enable the monitoring, governance and long-term decarbonisation of the building stock in line with European climate and sustainability goals by reframing the SRI within a digital and decarbonisation-oriented methodological perspective. Full article

The problem of urban surface runoff (USR) treatment is associated with the presence of high concentrations of specific pollutants. One of these pollutants is petroleum product (PP), whose concentration depends on the season and the location of the formation of snow masses, meltwater, and rainwater. For USR treatment, it is possible to use very environmentally friendly and inexpensive technologies. The article discusses natural sorbents based on wood materials, which effectively remove dissolved petroleum products from water. Pine sawdust and shredded branches of maple, birch, and poplar are used as raw materials, which are waste products from the city’s woodworking enterprise and utilities. These materials were pre-microwave (MW) treated to improve their sorption properties. As a result of the experiment, it turned out that modified pine sawdust and crushed maple pinwheels proved to be the most effective sorbents. The maximum sorption capacity values were 0.689 mg/g and 0.952 mg/g for pine and maple sorbents, respectively. This article proposes schemes for filtering devices that can be used in practice in an urban environment. Full article

In the coordinated management of air pollutants and carbon emissions, governments impose differentiated regulatory requirements on gases, while mitigation technologies have heterogeneous abatement potential. However, existing studies on emission quota management, an important mitigation instrument, focus on single gases and neglect integrating multigas policy preferences and heterogeneous abatement potentials, weakening policy responsiveness and scheme feasibility. This study develops a two-stage allocation framework. First, policy preference weights are introduced to evaluate multigas synergistic emission reduction potential and determine maximum quota reduction constraints for each gas. Second, policy preference weights and a non-radial directional distance function (NDDF) are embedded in a zero-sum gains data envelopment analysis (ZSG-DEA) model to capture multigas heterogeneity in policy preferences and reduction constraints, improving applicability and feasibility. Applied to the coal-fired power sector, the results show that, relative to the equal weight scenario, CO₂ incentive intensity rises by 22% under a carbon priority scenario and SO₂ incentive intensity increases by 13% under a pollution priority scenario, while the maximum quota reduction ratios of CO₂ and SO₂ are constrained from 41.75% to 9.18% and from 78.57% to 37.28%, respectively, ensuring alignment with policy preferences and keeping abatement within feasible ranges to support carbon neutrality and pollution control targets, thereby contributing to sustainable development. Full article

Wireless Body Area Network (WBAN) is an emerging medical health monitoring technology. However, WBANs encounter critical challenges in balancing reliability, energy efficiency, and Quality of Service (QoS) requirements for life-critical medical data. The design of its Medium Access Control (MAC) protocol has challenges since dynamic body-shadowing effects and heterogeneous traffic patterns. In this paper, we propose the Nash Bargaining Rate-optimization MAC (NBR-MAC), a hybrid MAC protocol that integrates TDMA-based Guaranteed Time Slots (GTS) with CSMA/CA-based contention access. Unlike traditional schemes, we model the rate allocation as an Asymmetric Nash Bargaining Game, introducing a rigorous disagreement point to guarantee minimum service for critical nodes. The utility function is normalized to resolve dimensional inconsistencies, incorporating sensor priority, buffer status, and channel quality. The Nash Bargaining solution is derived after proving convexity and verifying the axioms. Superframe time slots are allocated based on sensor data priority. Simulation results demonstrate that the proposed protocol enhances transmission success ratio and throughput while reducing packet age and energy consumption under different load conditions. Full article

Steering angle control in self-driving cars is usually organized in layers combining trajectory planning, path tracking, and low-level actuator control. The steering controller converts the planned path into a desired steering angle and then ensures accurate tracking by the electric power steering (EPS). However, automotive electric power steering (AEPS) systems face many problems caused by model uncertainties, disturbances, and unknown system dynamics. In this paper, a robust finite-time control strategy based on an adaptive backstepping scheme is proposed to handle these problems. First, radial basis function neural networks (NNs) are designed to approximate the unknown system dynamics. Then, an adaptive sliding-mode disturbance observer (ASMDO) is introduced to address the impacts of the lumped disturbance. Enhanced control performance for the AEPS system is implemented using a combination of the above technologies. Numerical simulations and a hardware-in-the-loop (HIL) experimental verification are performed to demonstrate the significant improvement in performance achieved using the proposed strategy. Full article

With the rapid evolution of wireless networks, the need to explore novel technologies to meet the demands of future systems, particularly 6G, has become a significant challenge. One promising solution is integrating radio frequency (RF) and optical wireless communication (OWC) technologies to leverage their unique strengths. This paper introduces a novel model for integrating RF and OWC technologies within the framework of emerging 6G. The main objective of this approach is the dynamic technology selection (TS) and modulation scheme selection (MSS), which play a pivotal role in optimizing network efficiency and adapting to diverse 6G requirements. The proposed cross-layer architecture integrates the application layer, network layer based on a software-defined network (SDN), and physical layer consisting of a hybrid cell and software-defined radio with optical functionality (SDR-O). This approach facilitates real-time decision-making based on environmental factors and application requirements. Full article

To address the insufficient bearing capacity and severe deformation of narrow coal pillars in deep gob-side entries under the influence of residual dynamic loading and hydraulic punching of the coal mass, this study investigates the plastic-damage evolution mechanism of narrow pillars and proposes a novel “grip-anchoring (GA)” collaborative support system. A physical model testing system for narrow coal pillars reinforced by double-pull cable bolts was established based on similarity theory, and six support schemes were designed for comparative experiments. Digital image correlation was employed to analyze the displacement field and the evolution of plastic failure, and an industrial-scale field test was carried out to verify the reliability of the proposed support technology. The results indicate that the double-pull cable bolts, through a “dual-tensioning and synergistic locking” procedure, can effectively solve the support challenges of narrow coal pillars under asynchronous excavation. The dense double-row double-pull cable-bolt scheme maintained overall structural stability even under a 2.5p overload, with only localized damage occurring at the roof- and floor-corner zones of the pillar. This scheme exhibited the smallest deformation and the highest peak load among all tested configurations, demonstrating its significant advantage in enhancing structural stability. Full article

Table grapes are among the main fruit crops cultivated in Brazil, supported by cultivar diversity, technological advances, and adaptation to diverse edaphoclimatic conditions. Rootstock selection is critical in viticulture, influencing phenology, yield, and fruit quality. This study evaluated yield- and fruit-related production parameters, cluster characteristics, and biochemical composition of ‘BRS Núbia’ table grape grafted onto different rootstocks. The experiment was conducted at the Experimental Farm of the Faculty of Agricultural Sciences (UNESP), São Manuel, São Paulo, Brazil, using a randomized block design in a split-plot scheme (three rootstocks × three seasons) with seven replicates. Rootstocks included ‘IAC 572 Jales’, ‘IAC 766 Campinas’, and ‘Paulsen 1103’, while subplots corresponded to the first three production seasons after grafting. Evaluated variables comprised bud fruitfulness, yield, productivity, physical attributes of clusters, berries, and rachises, and in 2022, berry biochemical traits, including total phenolics, flavonoids, anthocyanins, and antioxidant activity. Rootstocks did not significantly affect bud fruitfulness or yield-related parameters. In contrast, production season markedly influenced vine performance, with the third (2023) season showing higher cluster and berry mass and size. Regarding fruit composition, vines grafted onto ‘Paulsen 1103’ and ‘IAC 766 Campinas’ showed greater accumulation of total phenolics and anthocyanins than those grafted onto ‘IAC 572 Jales’, overall. Full article

The deep brine reservoirs in the Jianshishan area of the Qaidam Basin are abundant in strategic mineral resources. Traditional extraction methods suffer from insufficient reservoir energy and low recovery efficiency, while CO₂ flooding technology offers a new solution integrating brine development and CO₂ sequestration. However, the reservoir comprises three typical lithologies (calcareous mudstone, laminated mudstone, and massive sandstone) with distinct mineral compositions and structural characteristics and the mechanisms by which CO₂–brine–reservoir reactions affect their pore structures remain unclear. This study conducted laboratory simulation experiments combined with multiple analytical techniques to investigate the evolutionary characteristics of the three lithologies under CO₂ action. The results show that (1) calcareous mudstone has the strongest dissolution effect, with porosity increasing from 6.25% to 9.29% (an increase of 48.6%) and permeability increasing from 0.0012 mD to 0.0511 mD (an increase of 41.6 times); (2) laminated mudstone shows a trend of “first improvement, then deterioration”, with porosity initially rising to 11.84% and then slightly decreasing, and permeability decreasing from 0.0042 mD to 0.0036 mD; and (3) massive sandstone has stable mineral composition, with porosity increasing from 10.74% to 11.63% (an increase of 8.3%) and permeability fluctuating slightly between 0.0028 and 0.0032 mD. This study reveals that lithological mineral composition and structural characteristics are core factors controlling pore structure evolution, providing theoretical and experimental support for optimizing differentiated CO₂ flooding schemes for deep brine reservoirs. Full article

Photocatalytic degradation of tetracycline (TC) is considered a viable technology due to its stable molecular structure and resistance to absorption by biological organisms. As a promising photocatalyst, TiO₂ suffers from a wide bandgap and rapid charge recombination rates. In this work, the S-scheme heterojunctions of g-C₃N₄/TiO₂ (CNTOx, x = 10, 30, and 70) were synthesized via solvothermal, calcination, and impregnation methods. Furthermore, carbon quantum dots (CQDs) were incorporated into the CNTO30 samples, resulting in yCQDs-CNTO30 (y = 0.5, 1, and 3). The 1CQDs-CNTO30 demonstrat an impressive TC degradation efficiency of 76.7% in 60 min under visible light, which is higher than that of CNTO30 (59.8%). This enhanced efficiency is ascribed to the effective charge separation induced by the dual-effect of S-scheme heterojunction and the CQDs. The built-in electric field within the heterojunction drives the separation of electrons and holes. Meanwhile, the highly conductive CQDs accelerate the electron transport, thereby promoting the charge separation. Additionally, the CQDs improve the ability of absorption light. This research provides critical insights into the strategic development of efficient ternary photocatalytic S-scheme heterojunctions for environmental remediation. Full article

The rapid growth of mobile payment systems has positioned Near Field Communication (NFC) as a core enabling technology. However, conventional NFC protocols primarily emphasize transmission efficiency rather than robust authentication and privacy protection, which exposes users to threats such as eavesdropping, replay, and tracking attacks. In this study, a lightweight and privacy-preserving authentication protocol is proposed for NFC-based mobile payment services. The protocol integrates anonymous authentication, replay resistance, and tracking protection while maintaining low computational overhead suitable for resource-constrained devices. A secure offline session key generation mechanism is incorporated to enhance transaction reliability without increasing system complexity. Formal security verification using the Scyther tool (version 1.1.3) confirms resistance against major attack vectors, including impersonation, man-in-the-middle, and replay attacks. Comparative performance analysis further demonstrates that the proposed scheme achieves superior efficiency and stronger security guarantees compared with existing approaches. These results indicate that the protocol provides a practical and scalable solution for secure and privacy-aware NFC mobile payment environments. Full article

The increasing need for flexible and decentralized electricity systems in Colombia has renewed interest in biomass as a complementary renewable energy source beyond conventional large-scale applications. Rather than focusing on specific conversion technologies, this study develops an indicator-based framework aimed at qualifying the energetic suitability of diverse biomass resources for integration into electrical microgrids and distributed generation schemes. The research follows a documentary and comparative methodological design structured around sequential analytical stages, including the systematization of biomass resources, their physicochemical and energetic characterization based on reported data, conceptual analysis of the biomass-to-electricity pathway, and the formulation of quantitative energy indicators. These indicators are subsequently transformed into qualitative categories through a discretization procedure that enables relative comparison across resource types. Agricultural residues, livestock by-products, urban pruning waste, and residues from dedicated energy crops were considered within a unified analytical framework. The resulting indicator set captures resource availability, energy content, and conversion-relevant attributes, allowing biomass alternatives to be assessed in a consistent and comparable manner without relying on site-specific technological assumptions. By translating quantitative parameters into qualitative energy profiles, the proposed approach supports early-stage planning and decision-making for decentralized power systems. The framework provides a systematic basis for identifying biomass resources with favorable energetic characteristics and contributes to the broader discussion on sustainable and diversified electricity generation in Colombia. Full article