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Climate drought and resilience of karst hydrosystems in semi-arid regions: Case of the Dir of Beni Mellal Atlas (Morocco)
No full textThis study examines climatic drought and the sustainability of karst springs in the Dir of Beni Mellal Atlas in Morocco, based on an analysis of precipitation, spring flows and hydrological breaks. Rainfall series were evaluated using the Standardised Precipitation Index (SPI-12), while multi-year variations in flow rates were analysed using baseflow and the CUSUM test. The results reveal high hydroclimatic variability marked by alternating dry and wet years, with a clear trend towards more frequent and intense dry spells since the 2000s. The CUSUM analysis shows a persistent cumulative deficit, reflecting progressive aridification and a decline in the resilience of karst systems. Karst springs show different responses depending on their location and hydrogeological structure, highlighting the importance of local characteristics in flow dynamics. This study highlights the complementarity of the SPI-12 and CUSUM indicators in assessing both the intensity of droughts and their accumulation, providing essential tools for the sustainable management of water resources in semi-arid areas of Morocco
Microwave-assisted transesterification for optimized biodiesel production from waste cooking oil using a heterogeneous base catalyst derived from
No full textBiodiesel production from waste cooking oil (WCO) provides an environmentally friendly solution for reducing fossil fuel dependence while addressing improper oil disposal. This study contributes a targeted optimization strategy for biodiesel synthesis by integrating two specific research initiatives: (1) the application of microwave-assisted transesterification to accelerate reaction kinetics, and (2) the development of a heterogeneous CaO catalyst derived from
Pila ampullacea shells with controlled particle-size variation. The effects of these initiatives were systematically evaluated by measuring biodiesel yield and fuel quality under nine treatment combinations of microwave power (80, 240, 400 W) and catalyst particle size (40–60, 60–100, <100 mesh). The measurements revealed that higher microwave power significantly improved reaction efficiency due to enhanced dielectric heating, while larger catalyst particles produced higher CaO crystallinity, contributing to increased catalytic activity. The optimal condition (400 W, 40–60 mesh) produced a biodiesel yield of 62.75%. Characterization results showed compliance with SNI 7182:2015 for density, viscosity, cetane number, and iodine value, while acid number and calorific value indicated the need for further refinement. Overall, the findings demonstrate that combining microwave energy with biomass-derived CaO catalysts can substantially enhance biodiesel production performance, while the measurement outcomes clarify the mechanisms responsible for yield and quality improvements. These results offer important implications for scalable, low-cost biodiesel technologies using waste-based resources
IoT and AI-driven approaches to sustainable eco-tourism and cultural heritage management in Uzbekistan: Multidisciplinary frameworks and local implementation
No full textWhile in many developing regions, the increasing resource strain from pressure on local infrastructure is a major concern for stakeholders and the environment, its impact on site-specific tourism dynamics may differ across regions, depending on the local context and the adaptive capacity of the institutions. We analyzed the combined effects of IoT integration, AI-based monitoring, and stakeholder collaboration and governance quality on the tourism performance, heritage preservation, and environmental sustainability, an evaluation that is restricted to the mountainous ecological corridors and heritage-rich valleys. This multidisciplinary investigation revealed heterogeneity in the relationships between technology deployment and levels of resilience across the study area over the analysis period. The trajectory of impacts from the longitudinal data set, ranging from the pre-digital phase to the post-adoption stage and seasonal variation to annual aggregation, was simulated using the Structural Equation Modeling (SEM) model. A regression-based hybrid method was proposed to quantify the interdependencies between ecological indicators and tourism activity. Our results showed that performance improvements can be achieved from digitally monitored interventions with targeted governance alignment. The results indicate that resilience outcomes may vary from one region to another, but communities in the same geographic cluster follow a shared trajectory in the short term
Bioeconomic Analysis and Risk Assessment of Integrated Forestry and Wood Pellet Production for Post-Mining Land Use in East Kalimantan
No full textCoal mining in East Kalimantan, Indonesia, has spurred economic growth but inflicted severe environmental degradation, necessitating innovative PMLU strategies for ecosystem restoration and sustainable development. This study evaluates the financial viability and risks of an integrated wood forestry and wood pellet factory using Acacia mangium plantations on 10,500 hectares of degraded land, aligning with SDGs 7, 15, and 8. Employing a bioeconomic model, we constructed a base case financial framework with proforma statements, free cash flow calculations, and Monte Carlo simulations (50,000 iterations) to assess NPV, IRR, and DPP under uncertainty. Results indicate baseline feasibility with an NPV of USD 2.2 million, IRR of 12.08% (exceeding 9% WACC), and DPP of 19 years, transitioning to positive cash flows by year 5. Simulations reveal a mean NPV of USD 6.146 million and DPP of 14.87 years, but high variability (coefficient of variation up to 1.60) and risks from pellet price fluctuations (over 70% variance contribution) and cost growth, where a 5% adverse pellet price change reduces NPV by 72%. These findings underscore the project’s potential for bioenergy production and land rehabilitation, while highlighting the need for market stabilization strategies
Preliminary Techno-Economic Analysis of Wind Power Plant Development in Central Java
No full textThe wind energy potential in Central Java offers promising opportunities for utility-scale wind power development. This study evaluates the techno-economic feasibility of four candidate sites using the System Advisor Model, analyzing turbine capacities from 500 to 2000 kW and total plant capacities of 30, 50, and 70 MW. Technical assessments include wind resource analysis, turbine layout design, and system loss estimation. Wlahar Village in Brebes emerges as the most promising site, with an average wind speed of 6.2 m/s and a net capacity factor of 37%. Two financing structures were compared: a 70% debt scheme and a conservative DSCR-targeted approach. Although the 70% debt model yields attractive metrics (LCOE 5.62 ¢/kWh, NPV USD 71.95 million, IRR 9.38%), it is financially unfeasible due to a low DSCR of 0.62. In contrast, the conservative scheme, designed to meet a minimum DSCR of 1.25, achieves a viable NPV of USD 61.31 million and an IRR of 7.05%. Grid connection costs increase total capital expenditure by approximately 1.46% but do not significantly affect feasibility. Overall, Wlahar demonstrates strong technical performance and economic viability under conservative financing assumptions, supporting its potential for wind power development in Central Java
La technologie LiDAR pour une agriculture innovante et précise
No full textAvec la démocratisation et la miniaturisation des sources impulsionnelles, le LiDAR a su s’implanter dans de nombreux secteurs tels que le transport et l’aérospatial. Il permet de rapidement quantifier une information spatiale avec une grande précision ou un déplacement avec une fine sensibilité. Depuis quelques années, d’autres domaines s’intéressent à cette technologie comme l’agriculture afin de proposer des pratiques agricoles durables ou de faciliter les prises de décision
First reverberation mapping of a Bowen fluorescence line
No full textContext. Reverberation mapping (RM) is a powerful tool to determine the extent, structure, and kinematics of the broad-line region (BLR) of active galactic nuclei (AGNs). So far, RM of the BLR has only been performed for recombination lines responding to the varying ionizing continuum.
Aims. We tested whether O
Effects of the sheared flow velocity profile on impedance eduction in a 2D duct
No full textImpedance eduction methods are the current standard approach to measure the impedance of acoustic liner under sheared grazing flow. The dedicated facilities for these methods consists on a waveguide with rectangular cross-section, which implies a sheared grazing flow. A current debate in the literature is the effect of this sheared flow in the impedance eduction methods. We assess the impact of the flow profile shape on acoustic propagation in a two-dimensional duct within the typical operating range of impedance eduction facilities. Firstly, a numerical experiment is proposed in which the Pridmore–Brown equation is assumed to represent the true physical behaviour, and is used with both simplified flow profiles commonly used in the literature and a realistic representation of a turbulent boundary layer using a van Driest universal law of the wall model. The data from these numerical experiments are then used with a traditional impedance eduction process, and the resulting variation in obtained impedances are investigated. Secondly, we apply a less-traditional impedance eduction method that incorporates the sheared velocity profile to data obtained from real-world experiments. The results suggest that the Ingard–Myers boundary condition remains a good approximation to a realistic boundary layer profile, such as the universal law of the wall, at least in the two-dimensional case. However, it is also shown that the simplified flow profiles often used in the literature can lead to significant deviations from the results obtained using a realistic velocity distribution
On finite interweaving relations
No full textA faithful bi-interweaving relation is a Markovian similarity-type relation between two Markov chains, strengthening the Markovian intertwining relation and introducing warming-up times after which the time-marginal distributions of the chains can be tightly compared (for any initial distributions). For irreducible transition kernels on the same finite state space, these relations are shown to be equivalent to the generalised isospectrality relation, but this is no longer true for nontransient transition kernels, contrary to the faithful bi-intertwining relations. Some bounds are deduced on corresponding warming-up times, when the eigenvalues are furthermore assumed to be real (but still allowing for Jordan blocks). When the eigenvalues are non-negative, the same approach enables us to construct strong stationary times for irreducible Markov chains through interweaving relations with model absorbed Markov chains, thus extending a result due to Matthews in the reversible situation