Search Results (376)

Flooding has become increasingly severe due to rapid urbanization and changing hydrological conditions, necessitating effective and sustainable mitigation strategies. This study investigates the hydraulic performance of a hybrid flood defense system comprising a dike, a moat, and vegetation under varying surface roughness conditions. The results demonstrate that increasing roughness significantly enhances flood mitigation performance by improving energy dissipation and delaying the propagation of floodwater. A maximum energy reduction of approximately 75.56% and a delay in floodwater arrival of up to 65% were observed under higher roughness conditions. In contrast, increasing flow intensity reduced system efficiency, highlighting the importance of optimizing roughness under varying hydraulic conditions. The findings reveal that surface roughness is the dominant factor controlling flow resistance, turbulence generation, and hydraulic jump formation within the system. The novelty of this study lies in systematically quantifying the combined effect of roughness across structural and vegetative components within a hybrid defense framework. These results provide a practical basis for the design and optimization of eco-engineered flood defense systems, offering a cost-effective approach for reducing flood risk in riverine environments. Full article

In the digital economy, small and medium-sized enterprises (SMEs) face growing pressure to align digital transformation with sustainability-oriented value creation. Yet, it remains unclear how and through which mechanisms digital leadership is associated with sustainable digital innovation in resource-constrained and turbulent contexts. This study investigates whether digital leadership is associated with sustainable digital innovation directly and indirectly through digital capabilities and digital orientation, and whether strategic agility strengthens these relationships. Drawing on the Resource-Based View (RBV) and Dynamic Capability Theory (DCT), the study develops an integrated framework that explains sustainable digital innovation as a strategically managed outcome of digital economy transformation rather than a simple result of technology adoption. Using survey data from 423 employees in Lebanese SMEs, the hypotheses were tested through partial least squares structural equation modeling (PLS-SEM). The findings show that digital leadership is positively associated with sustainable digital innovation both directly and indirectly, with digital orientation emerging as the stronger mediating pathway compared to digital capabilities. In addition, strategic agility strengthens the association between digital orientation and sustainable digital innovation, while its moderating role on the digital capabilities path is not significant. These findings contribute to the literature by identifying dual transformation mechanisms and revealing an asymmetric boundary role of agility in sustainability-oriented digital transformation. The study also offers practical implications for SME leaders seeking to align digital strategy with long-term environmental, social, and economic value creation. Full article

Background: Territorial logistics management has become increasingly important in turbulent environments, where digitalization, sustainability, resilience, and governance interact to shape regional logistics performance. This study aims to identify the strategic dimensions that structure territorial logistics management. Methods: A sequential mixed-methods design was adopted. First, relevant variables were identified through a structured literature review and expert judgment. Second, a survey of 376 specialists was analyzed using principal component analysis (PCA) to explore the empirical structure of the retained variables. Results: The analysis identified a four-dimensional structure comprising: (1) digital infrastructure and intelligent logistics, (2) sustainability and circular economy, (3) systemic resilience and risk management, and (4) territorial logistics, governance, and accessibility. Together, these dimensions explained more than 70% of the total variance. Conclusions: The findings suggest that territorial logistics management is a multidimensional phenomenon shaped by the interaction of technological, environmental, institutional, and spatial factors. The study provides an empirically grounded exploratory framework for understanding territorial logistics and supporting more integrated strategies for smart, sustainable, and resilient supply chains. Full article

Solid fuel ramjets (SFRJs) are air-breathing propulsion systems with a high specific impulse, but their sudden expansion combustors often exhibit axially nonuniform fuel regression because of the distinct recirculation, reattachment, and downstream turbulent diffusion flame regions. However, previous studies have primarily focused on the average regression rate, with limited attention to local combustion characteristics. This study applied a photogrammetry-based three-dimensional shape reconstruction technique to obtain the post-combustion internal port geometry of a sudden-expansion SFRJ combustor burning high-density polyethylene fuel under different chamber pressure and air mass flux conditions. This geometry was employed to determine the axial distributions of the local regression rates. The analysis procedure was validated against the corresponding space–time averaged regression rate obtained from fuel mass loss, showing suitable agreement with relative errors of 1.7–5.7%. The axial distributions consistently exhibited low values in the upstream, increased rapidly in the middle region, and sustained high or gradually decreasing in the downstream. In addition, an empirical expression for the space–time averaged regression rate indicated greater sensitivity to air mass flux than chamber pressure. These results confirm that photogrammetry is an effective tool for resolving the axially nonuniform regression behavior and informing spatial insights beyond the average regression rate alone. Full article

Fluid-dynamic drag accounts for a substantial fraction of energy consumption across air, ground, and maritime transport systems, making its reduction a critical lever for decarbonizing mobility. While active flow control (AFC) strategies have demonstrated significant drag reduction potential, their design remains constrained by heuristic physical assumptions about dominant flow structures. Recent developments in deep reinforcement learning (DRL) have emerged as a transformative paradigm, capable of autonomously discovering control strategies in high-dimensional turbulent environments. This perspective traces the evolution of drag reduction approaches from classical passive and active control approaches toward data-driven methods based on DRL. A particularly promising direction is the integration of explainable artificial intelligence (XAI) with DRL, which provides physically interpretable information about flow regions associated with drag generation and guides the learning process toward physically meaningful actuation schemes. As a result, XAI-guided DRL controllers have been shown in canonical configurations to achieve comparable or improved drag reduction with substantially lower actuation power than controllers trained directly for drag minimization. This transition from opaque optimization toward flow control informed by dynamical causal relationships represents a key step for the development of energy-efficient and sustainable flow-control solutions for transport systems. Full article

Hydrogen enrichment of compression ignition (CI) engines has emerged as a promising strategy to simultaneously enhance thermal efficiency and reduce carbon-based emissions. This study numerically investigates how hydrogen enrichment affects engine performance and emissions in methanol–diesel dual-fuel CI engines, a combustion mode gaining increasing attention for replacing fossil diesel with sustainable fuels, particularly in hard-to-abate sectors such as maritime transport. The simulations are based on the Unsteady Reynolds-Averaged Navier–Stokes (URANS) equations, incorporating the RNG k-ε turbulence model, the Eddy Dissipation Concept (EDC) for turbulence–chemistry interaction, and the G-equation for turbulent premixed flame propagation. The numerical model is validated against experimental data for in-cylinder pressure and heat release rate at 45% methanol substitution ratio (by energy). The results indicate that increasing the hydrogen enrichment ratio (HER, defined on an energy basis) from 5% to 20% raises the Sauter mean diameter (SMD) of the diesel fuel from 20.2 µm to 28.0 µm (+38%), driven by reduced aerodynamic breakup intensity associated with modified gas-phase properties under hydrogen enrichment. Furthermore, hydrogen’s elevated adiabatic flame temperature and superior mass diffusivity intensify combustion, raising peak in-cylinder pressure from 75.2 to 79.1 bar (+5.2%), amplifying the peak heat release rate from 129 to 211 J/°CA (+63.6%), and elevating maximum in-cylinder temperature from 1542 to 1735 K (+193 K). Under the investigated CFD operating conditions, these thermodynamic gains translate into an engine-level 6% improvement in indicated thermal efficiency and a 14% reduction in indicated specific fuel consumption (accounting for hydrogen, methanol, and diesel) at HER 20%. On the emissions front, CO₂ declines by 24% in direct proportion to the carbon-containing fuel mass displaced by hydrogen substitution, while NO_x increases approximately twofold from 0.10 g/kWh at HER 0 to 0.21 g/kWh at HER 20, driven by peak temperature elevation. These findings establish hydrogen-enriched methanol–diesel dual-fuel combustion as a viable pathway toward high-efficiency, low-carbon CI engine operation for heavy-duty transport applications. Full article

Digital news organizations increasingly adopt generative artificial intelligence (GenAI) under conditions of economic strain and platform dependency. While AI integration is often framed as a strategy for operational efficiency, its institutional implications extend beyond productivity gains. This study examines how different governance approaches to GenAI adoption—specifically variations in transparency, disclosure, and oversight practices—correspond to shifts in audience engagement and financial performance. Using a comparative mixed-methods design, we analyze three prominent cases between 2022 and 2025—CNET, Gizmodo, and The New York Times—representing, respectively, covert AI use with limited disclosure, transparent but poorly managed deployment, and proactive ethical and legally grounded positioning. To operationalize audience stability, we introduce two behavioral indicators: the Engagement Resilience Index (ERI), measuring depth and consistency of user engagement; and the Market Turbulence Ratio (MTR), capturing post-incident volatility in audience behavior. The findings indicate that AI deployment strategies associated with limited disclosure or weak governance correspond with increased engagement instability and revenue contraction, whereas approaches framed through institutional accountability and ethical positioning align with more stable or positive performance trajectories. The results suggest that AI integration functions not merely as a technological shift but as a governance-mediated signal interpreted by audiences in economic terms. These dynamics highlight the centrality of institutional trust in shaping the sustainability of digital journalism in the age of automation. Full article

We perform three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulations of a near-maximally spinning black hole (spin parameter $a=0.998$) with varying initial magnetic field geometries, systematically exploring the parameter space connecting magnetically arrested disk (MAD), intermediate (INT), and standard and normal evolution (SANE) accretion states. The magnetic flux threading the black hole horizon emerges as the fundamental state variable controlling jet efficiency, flow magnetization, and radiative output across all three states. We introduce complementary diagnostics—broadband spectral energy distributions spanning radio through hard X-ray frequencies and time-resolved X-ray light curves—that together connect simulation dynamics directly to multiwavelength observables. The radiative output follows a clear MAD > INT > SANE hierarchy in time-averaged luminosity, mean X-ray emission, as well as variability. Furthermore, MAD exhibits the highest fractional variability through quasi-periodic magnetic flux eruption events, and INT and SANE show moderate variability driven by episodic reconnection and stochastic MRI turbulence, respectively. Scaling to GRS 1915+105, Cyg X-1, and HLX-1, we demonstrate that all twelve temporal classes of GRS 1915+105 map naturally onto our three magnetic states, Cyg X-1’s persistent hard state is reproduced by a sustained INT configuration, and HLX-1’s extreme luminosities arise through efficient Blandford–Znajek extraction in MAD states scaled to higher black hole mass. Full article

Airfoil fin Printed Circuit Heat Exchangers (PCHEs) offer significant advantages in reducing flow resistance, promoting turbulence, and enhancing heat transfer performance due to their discrete fin configuration. However, compared with conventional continuous-channel structures, the geometric discontinuities and sharp trailing edges introduced by discrete fins tend to induce severe stress concentration at the fin roots, resulting in a more complex structural response. In this study, a PCHE core with NACA0020 airfoil fins is investigated. Finite element analysis combined with a sequential one-way thermo-structural coupling approach is conducted to characterize the fins’ stress and deformation behavior under high temperature and pressure. The plate region is evaluated based on the linear elastic stress criteria specified in ASME Boiler and Pressure Vessel Code Section III, while localized yielding regions such as the fin roots are assessed using an equivalent plastic strain indicator. Results indicate that the structural response of the PCHE core is dominated by pressure loading under the investigated operating conditions with ΔT = 18 °C and ΔP = 12.05 MPa, whereas thermal stress caused by constrained thermal expansion mainly modifies local stress distributions and has a limited effect on global deformation. Owing to the discontinuous support provided by discrete airfoil fins, the fin roots act as the primary load-transfer path and sustain higher stress levels. The maximum von Mises stress is observed at the trailing edge of the fin root on the high-pressure side, while the largest deformation occurs in the unsupported plate region and is governed by bending. Parametric analysis indicates that, within the investigated parameter range, a fully staggered fin arrangement promotes more uniform load distribution and exhibits the most favorable structural response. In contrast, increasing the fin chord length and relative thickness reduces the overall load-carrying capacity of the core. Finally, a power-law predictive correlation for the maximum total plate deformation was developed, showing that the parameter influence on plate structural response follows the order horizontal pitch (L_h) > vertical pitch (L_v) > channel etching depth (L_e) > staggered pitch (L_s). In contrast, normalized sensitivity analysis of the maximum fin-root von Mises stress shows the order staggered pitch (L_s) > horizontal pitch (L_h) > vertical pitch (L_v) > channel etching depth (L_e), indicating that global plate deformation and local fin-root response are governed by different structural mechanisms. Full article

The increasing integration of intermittent renewable energy sources (RESs) into islanded Hybrid Power Systems (HPSs) is a critical step towards global energy sustainability; however, it poses significant challenges to frequency stability owing to low system inertia and stochastic power fluctuations. To address these challenges and enable higher penetration of green energy, this study proposes a novel and robust Load Frequency Control (LFC) strategy based on the Crested Porcupine Optimizer (CPO). A customized Mode-Dependent Adaptive Balloon (MDAB) controller is developed, wherein the virtual control gain is dynamically tuned based on the real-time operating modes and disturbance severity. Furthermore, to optimize communication resources and mitigate actuator wear in networked microgrids, an intelligent event-triggered (ET) mechanism is seamlessly integrated into the adaptive logic. The proposed control framework is rigorously validated through comprehensive nonlinear simulations and comparative analyses with state-of-the-art metaheuristic algorithms (GTO, GWO, JAYA, and GO). The evaluation encompasses step load disturbances, severe parametric uncertainties (+25%), realistic 24-h diurnal cycles with solar cloud shading and wind turbulence, and extended practical constraints, including Battery Energy Storage System (BESS) integration and Internet of Things (IoT) communication delays. The results demonstrate the superiority of the CPO-tuned framework, which achieved the fastest transient recovery (settling time of 3.4367 s) and the lowest absolute Integral Absolute Error (IAE). Additionally, the proposed ET-based strategy not only reduced the communication burden but also improved the overall control performance by 37% in terms of IAE compared with continuous approaches. By inherently filtering measurement noise, mitigating control signal chattering, and maintaining resilience under nonideal latency, the proposed architecture offers a highly robust and resource-efficient solution that directly guarantees the operational sustainability and reliability of modern smart microgrids. Full article

Due to acute resource constraints and environmental turbulence, many small and medium-sized construction enterprises (SMEs) prioritize short-term survival over corporate social responsibility (CSR) initiatives. Grounded in social exchange theory (SET), this study investigates how CSR implementation drives financial performance (FP) via the mediating role of non-financial performance (NP), aiming to deconstruct the “psychological black box” of this transformation. Drawing on a sequential mixed-methods design involving PLS-SEM analysis of 380 responses and 10 semi-structured interviews, the results confirm that CSR practices, particularly ethical practices and community engagement, can be effectively translated into improved NP, which acts as a vital strategic conduit for enhancing FP. However, skills development and training showed limited immediate impact due to a systemic “digital mismatch” and significant time-lag effects. Theoretically, this research refines SET by identifying a hierarchical transition where socio-emotional assets serve as compensatory resources in volatile and resource-constrained environments. Practically, the findings offer a strategic roadmap for SMEs to mitigate technological and systemic barriers, providing novel pathways for fostering CSR to achieve sustainable growth. Full article

Mode division multiplexing (MDM) is an emerging optical communication solution for high-capacity wired–wireless applications. Due to the presence of modal crosstalk and link impairments in MDM, this work aims to design a system that provides low complexity, an improved Shannon Capacity limit, and high spectral efficiency. In this work, a quad modal MDM system using an integrated parabolic index multimode fiber and free-space optics (PIMMF-FSO) link is presented. Four linearly polarized (LP) modes, LP₀₁, LP₂₂, LP₀₃, and LP₁₃ based on a 16 × 10 Gbps MDM system offering different sixteen channels, are realized. Results show that the system can sustain a 7.5 dB insertion loss over 100 m FSO and a 100 m fiber range for different LP modes under the impact of clear air, moderate haze, heavy rain and wet snow climates with weak turbulence. A faithful fiber range of 3000 m can be obtained successfully in the proposed system with a −10 dB link loss, −7.62 dBm received power and 10 dB noise. Compared to existing designs, the proposed design offers optimum performance in terms of high channel capacity and a high traffic rate with low complexity and high spectral efficiency. Additionally, high received power, with acceptable noise, link loss, FSO misalignments and fiber nonlinearities, is successfully obtained. Full article

Business development unfolds within complex adaptive environments marked by nonlinear interaction, structural asymmetry, and recurrent instability. Sustained performance under such conditions requires regulatory structures that preserve coherence while enabling structural transformation. This study advances symmetry evolution as a systems principle that explains the emergence of balance through interaction among decision bias, structural symmetry, and regulatory intensity. An evolutionary regulation framework represents this interaction as a closed-loop dynamic that drives coevolution of regulation and symmetry through recursive feedback. Stability emerges as a property of proportional coupling rather than correction of deviations. Multi-modal simulations representing turbulent decision landscapes demonstrate formation of bounded oscillatory equilibrium under perturbation while preserving exploratory capacity, with a mean recovery interval of 1.01 iterations, compared with 9.56 under fixed regulatory intensity and 47.29 under exogenous adjustment, indicating a substantial reduction in recovery time. Coordinated evolution of regulatory gain and structural symmetry sustains adaptive stability without suppressing innovation dynamics. The study establishes a systemic foundation for resilience and endogenous governance in complex business systems and reframes decision optimization as structural adaptation within evolving regulatory architectures. Full article

The aviation industry is under increasing pressure to enhance sustainability by improving energy efficiency and reducing climate impact. A promising approach is to reduce aerodynamic drag using laminar flow technologies, particularly Natural Laminar Flow (NLF) and Hybrid Laminar Flow Control (HLFC). Previous research has primarily focused on aerodynamic performance, often considering only one technology at a time, using simplified HLFC system design models, and targeting long-range aircraft. This study adopts a more holistic approach by conducting a conceptual design of a short-medium range (SMR) aircraft equipped with both NLF and HLFC. The technologies are applied to the wing and empennage, with detailed HLFC system modelling integrated into the conceptual design process using established methods. A failure analysis is also performed to assess the performance impact of potential malfunctions. Results indicate that combining NLF and HLFC can reduce fuel consumption by 5.9% on the design mission compared to a fully turbulent reference aircraft. Moreover, selectively applying the technologies to specific components enhances fuel savings while reducing system complexity. These findings demonstrate the potential of laminar flow technologies to improve fuel efficiency in SMR aircraft and highlight the importance of integrated aerodynamic and systems-level evaluation. Full article

With the decreasing availability of high-quality mineral resources and the increasing complexity of ore properties, efficient and sustainable flotation technology has become a research focus in the field of mineral processing. To optimize the taper angle of the air distributor in a KYF flotation machine, numerical simulation was used in this study to investigate its influence on the internal flow field, gas-phase characteristics, structural pressure distribution, and stirring power consumption. The results show that the peak turbulent kinetic energy and gas holdup are concentrated in the shear zone between the impeller and stator. Under the +5° condition, the peak turbulent kinetic energy is the lowest, while its vertical distribution is the most uniform. The peak gas holdup in the impeller–stator region reaches 19.2%, and the number of efficient bubbles with a diameter of 0.5 mm reaches 3.8 × 10⁶ per m³, which is significantly higher than under the other conditions. During stable operation, this condition exhibits the lowest stirring power consumption at 126.0 W, which is 7.557% and 4.255% lower than under the −5° and 0° conditions, respectively. The optimal taper angle is therefore determined to be +5°. However, the associated large pressure gradient on the impeller surface may accelerate blade wear, indicating that surface strengthening measures should be considered to balance performance and durability. Full article