Search Results (77)

Introduction: Adolescents and young adults (AYAs), especially those from underserved communities, often face barriers to sexual and reproductive health (SRH). This pilot study evaluated the implementation of mobile health technologies to promote SRH care, including the integration of the Rapid Adolescent Prevention Screening^TM (RAAPS) and the Health-E You/Salud iTu^TM (Health-E You) app at a School-Based Health Center (SBHC) in Los Angeles using the RE-AIM (Reach, Effectiveness, Adoption, Implementation, Maintenance) framework. Methods: This multi-method pilot study included the implementation of an integrated tool with two components, the RAAPS electronic health screening tool and the Health-E You app, which delivers tailored SRH education and contraceptive decision support to patients (who were sex-assigned as female at birth) and provides an electronic summary to clinicians to better prepare them for the visit with their patient. Quantitative data on tool usage were collected directly from the back-end data storage for the apps, and qualitative data were obtained through semi-structured interviews and in-clinic observations. Thematic analysis was conducted to identify implementation barriers and facilitators. Results: Between April 2024 and June 2024, 60 unique patients (14–19 years of age) had a healthcare visit. Of these, 35.00% used the integrated RAAPS/Health-E You app, and 88.33% completed the Health-E You app only. All five clinic staff were interviewed and expressed that they valued the tools for their educational impact, noting that they enhanced SRH discussions and helped uncover sensitive information that students might not disclose face-to-face. However, the tools affected clinic workflows and caused rooming delays due to the time-intensive setup process and lack of integration with the clinic’s primary electronic medical record system. In addition, they also reported that the time to complete the screener and app within the context of a 30-min appointment limited the time available for direct patient care. Additionally, staff reported that some students struggled with the two-step process and did not complete all components of the tool. Despite these challenges, clinic staff strongly supported renewing the RAAPS license and continued use of the Health-E You app, emphasizing the platform’s potential for improving SRH care and its educational value. Conclusions: The integrated RAAPS and Health-E You app platform demonstrated educational value and improved SRH care but faced operational and technical barriers in implementing the tool. These findings emphasize the potential of such tools to address SRH disparities among vulnerable AYAs while providing a framework for future implementations in SBHCs. Full article

In a smart microgrid (SMG) system that deals with unpredictable loads and incorporates fluctuating solar and wind energy, it is crucial to have an efficient method for controlling frequency in order to balance the power between generation and load. In the last decade, cyberattacks have become a growing menace, and SMG systems are commonly targeted by such attacks. This study proposes a framework for the frequency management of an SMG system using an innovative combination of a smart controller (i.e., the Fuzzy Logic Controller (FLC)) with three conventional cascaded controllers, including Fractional-Order PI (FOPI), Tilt Integral Fractional Derivative (TID^μ), and Proportional Integral Derivative Acceleration (PIDA). The recently released Eel and Grouper Optimization (EGO) algorithm is used to fine-tune the parameters of the proposed controller. This algorithm was inspired by how eels and groupers work together and find food in marine ecosystems. The Integral Time Squared Error (ITSE) of the frequency fluctuation (ΔF) around the nominal value is used as an objective function for the optimization process. A diesel engine generator (DEG), renewable sources such as wind turbine generators (WTGs), solar photovoltaics (PVs), and storage components such as flywheel energy storage systems (FESSs) and battery energy storage systems (BESSs) are all included in the SMG system. Additionally, electric vehicles (EVs) are also installed. In the beginning, the supremacy of the adopted EGO over the Gradient-Based Optimizer (GBO) and the Smell Agent Optimizer (SAO) can be witnessed by taking into consideration the optimization process of the recommended regulator’s parameters, in addition to the optimum design of the membership functions of the fuzzy logic controller by each of these distinct algorithms. The subsequent phase showcases the superiority of the proposed EGO-based FFOPI-TID^μ-PIDA structure compared to EGO-based conventional structures like PID and EGO-based intelligent structures such as Fuzzy PID (FPID) and Fuzzy PD-(1 + PI) (FPD-(1 + PI)); this is across diverse symmetry operating conditions and in the presence of various cyberattacks that result in a denial of service (DoS) and signal transmission delays. Based on the simulation results from the MATLAB/Simulink R2024b environment, the presented control methodology improves the dynamics of the SMG system by about 99.6% when compared to the other three control methodologies. The fitness function dropped to 0.00069 for the FFOPI-TID^μ-PIDA controller, which is about 200 times lower than the other controllers that were compared. Full article

This paper analyzes the electricity dispatch process and the importance of predicting infrastructure construction delays and network congestion using a system dynamics methodology. Two scenarios of renewable energy integration within Colombia are examined, together with their impact on electrical generation, pricing, and the growth of transmission networks. The results indicate that delays significantly influence the system’s long-term development. Incorporating network congestion into energy dispatch significantly alters investment requirements for generation and transmission, emphasizing network constraints that an idealized dispatch would neglect. Considering congestion highlights the necessity of incorporating delays into energy planning, as these impacts are overlooked in models that fail to account for actual network limitations. This paper emphasizes the strategic significance of considering delays and congestion to attain more realistic and successful planning in extensive power networks. Full article

Bamboo, as a sustainable and renewable biomass resource, possesses significant application prospects along with underutilized potential. However, challenges such as mildew infestation, insect damage, and discoloration during processing and utilization negatively impact its service life and economic value. This study proposes a simplified hydrogen peroxide bleaching method for bamboo processing, resulting in bleached materials with uniform coloration and improved mildew resistance. The scanning electron microscopy (SEM) analysis of bleached bamboo showed significantly reduced starch and protein inclusions, expanded intercellular spacing, partial fiber detachment, and localized structural deformation in treated bamboo. The X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analyses revealed substantial lignin degradation in hydrogen peroxide-treated samples. The color difference (ΔE) was measured at 13.65 between treated and untreated samples, confirming effective bleaching efficacy. The mercury intrusion porosimetry (MIP) analysis revealed enhanced porosity accompanied by diameter enlargement in treated bamboo. Antifungal assessments indicated that hydrogen peroxide bleaching delayed the onset of mold colonization and significantly enhanced the mildew resistance of bamboo substrates. Full article

To facilitate power system decarbonization, optimizing clean energy integration has emerged as a critical pathway for establishing sustainable power infrastructure. This study addresses the multi-timescale operational challenges inherent in power networks with high renewable penetration, proposing a novel stochastic dynamic programming framework that synergizes intraday microgrid dispatch with a multi-phase carbon cost calculation mechanism. A probabilistic carbon flux quantification model is developed, incorporating source–load carbon flow tracing and nonconvex carbon pricing dynamics to enhance environmental–economic co-optimization constraints. The spatiotemporally coupled multi-microgrid (MMG) coordination paradigm is reformulated as a continuous state-action Markov game process governed by stochastic differential Stackelberg game principles. A communication mechanism-enabled multi-agent twin-delayed deep deterministic policy gradient (CMMA-TD3) algorithm is implemented to achieve Pareto-optimal solutions through cyber–physical collaboration. Results of the measurements in the MMG containing three microgrids show that the proposed approach reduces operation costs by 61.59% and carbon emissions by 27.95% compared to the least effective benchmark solution. Full article

In the age of widespread renewable energy integration, coal-fired power plants are transitioning from a primary baseload role to a more flexible peak-shaving capacity. Under frequent load changes, the thermal efficiency will significantly decrease. In order to achieve efficient dynamic operation, this study proposes a comprehensive mechanical model of a 300 MW drum-type boiler. Based on the Modelica/DYMOLA platform, the multi-domain equations describing energy and mass balance are programmed and solved. A comprehensive evaluation of the energy transformation within the boiler’s heat exchange components was performed. Utilizing the principles of exergy analysis, this study investigates how fluctuating operational conditions impact the energy dynamics and exergy losses in the drum and heating surfaces. Steady-state simulation reveals that the evaporator and superheater units account for 81.3% of total exergy destruction. Dynamic process analysis shows that the thermal inertia induced by the drum wall results in a significant delay in heat transfer quantity, with a dynamic period of up to 5000 s. The water wall exhibits the highest total dynamic exergy destruction at 9.5 GJ, with a destruction rate of 7.9–8.5 times higher than other components. Full article

The implementation of innovative strategies in transportation is fundamental for the transition to sustainable mobility in road freight transport. Electric trucks provide a sustainable solution, significantly contributing to the reduction in pollutant emissions, lower operational costs, and the ability to recharge from renewable energy sources. In this context, this article proposes a methodology to support sustainable mobility optimization considering the variables related to the logistical problems of electric vehicles (recharging time and autonomy), which allows for routes to be compared based on the shortest time, lowest costs, and shortest distance for delivering goods while integrating recharge time windows into optimized routes. The study results reveal that additional recharging can significantly impact total travel time and total costs due to variable tariffs at charging stations. Consequently, the model assists in improving resource management and delivery schedule management, thereby increasing operational efficiency and correcting potential conflicts or delays. Therefore, the method provides mobility as a service and offers greater flexibility to decision-makers in selecting the path that best meets delivery objectives, aiming to propose solutions to reduce the impact on the logistics process through the adoption of electric trucks in last-mile freight transport. Full article

Cellulose ethers (CEs), synthesized through the etherification of cellulose, have emerged as indispensable “green additives” in our modern industries, earning the moniker of industrial “monosodium glutamate” due to their unparalleled multifunctionality. Unlike traditional petroleum-based modifiers, CEs offer a unique combination of renewability, low toxicity, and tunable properties (e.g., water retention, thickening, and stimuli-responsiveness), making them pivotal for advancing sustainable construction practices. This review presents an overview of the preparation methods of various CEs and the applications of CEs especially in concrete and mortars as well as corresponding mechanisms. We systematically analyze the preparation methodologies (homogeneous vs. heterogeneous processes) and highlight the effect of molecular determinants (degree of substitution, molecular weight, functional groups) on the performances of CEs. CEs can enhance the workability and other properties of concrete and mortars primarily by acting as water-retaining and thickening agents to mitigate rapid water loss, improve hydration efficiency and cohesion. The effects of CEs on the delay of hydration and microstructure of concrete and mortars are also analyzed and highlighted. Beyond construction, we reviewed the current and emerging CE applications in biomedicine, tissue-engineering, petroleum industry and food engineering, highlighting their cross-disciplinary potential. This review provides some insights into the structure–property–application relationships of CEs and their brief historical developments, offering guidance for optimizing their utilizations especially in sustainable construction practices. Full article

Scheduling is essential in managing projects. ‘Schedula Anima’ is a new software designed to provide a comprehensive view of schedules between early and late dates for construction project managers. Capturing the dynamic nature of projects, it offers improved visualization through an animation process that creates incremental frames of bar charts and the corresponding resource graphs. As activity delays are simulated, it is observed that delays earlier in the schedule have more significant effects on project completion. A new prioritization method is introduced to evaluate the ease of rescheduling activities. A metric for monitoring resource usage float is presented, and the search space for resource utilization is delineated. As resource smoothing is studied in the resource usage graph and the time domain, a correlation is discovered between resource smoothness and the float consumption rate. It is shown that the schedule and resource usage graph comprises five sub-areas representing different risk exposures. Animation also improves communication in project teams and is beneficial in education. Finally, it is discovered that the permutations of activities in the simulation form a group. Enhancing our perception of resource utilization and the management of delays, ‘Schedula Anima’ brings a renewed perspective to project scheduling. Full article

2-Methylfuran (2-MF) has emerged as a promising renewable alternative fuel, primarily due to its sustainable production processes and its potential to significantly reduce soot emissions. However, when blended with diesel, it presents challenges, including an increase in NOx emissions, which is attributed to the lower cetane number (CN) of the M30 blend. This study investigates the effect of adding 2-ethylhexyl nitrate (2-EHN), a cetane enhancer, to the M30 blend (30% 2-MF by volume), on combustion characteristics and exhaust emissions. Experiments were conducted using a modified four-cylinder, four-stroke, direct-injection compression ignition (DICI) engine featuring a common rail fuel injection system. The engine was evaluated under different load conditions, with brake mean effective pressure (BMEP) ranging from 0.13 to 1.13 MPa, while maintaining a constant engine speed of 1800 rpm. The incorporation of 1.5% and 2.5% 2-EHN into the M30 blend enhanced combustion performance, as indicated by a reduction in the maximum pressure rise rate, a shorter ignition delay (ID), and an extended combustion duration (CD). Furthermore, the brake-specific fuel consumption (BSFC) reduced by 2.78% and 5.7%, while the brake thermal efficiency (BTE) increased by 3.54% and 7.1%, respectively. Moreover, the inclusion of 2-EHN led to a significant reduction in Nox by 9.20–17.57%, with the most significant reduction observed at a 2.5% 2-EHN, where hydrocarbon (HC) decreased by 7.93–21.59%, and carbon monoxide (CO) reduced by 12.11–33.98% as compared to the M30 blend without 2-EHN. Although a slight increase in soot emissions was observed with higher concentrations of 2-EHN, soot levels remained significantly lower than those from pure diesel. The results indicate that the addition of 2-EHN can effectively mitigate the trade-off between NOx and soot emissions in low cetane number oxygenated fuels. Full article

Fractional calculus provides tools to model systems with memory effects; when coupled with delays, they model process histories inspired by two independent sources—the memory of the fractional derivative and the impact conditioned by the delays. This work considers a Cauchy (initial) problem for a linear delayed system with derivatives in Caputo’s sense of incommensurate order, distributed delays, and piecewise initial functions. For this initial problem, we study the important problem of the backward continuation of its solutions. We consider the backward continuation of the solutions as a problem of the renewal of a process with aftereffect under given final observation. Sufficient conditions for backward continuation of the solutions of these systems have been obtained. As application, a formal (Lagrange) adjoint system for the studied homogeneous system is introduced, and using the backward continuation, it is proved that for this system there exists a unique matrix solution called by us as the formal adjoint fundamental matrix, which can play the same role as the fundamental matrix in the forward case. Full article

The elevated penetration of renewable energy has seen a significant increase in the integration of inverter-based resources (IBRs) into the electricity network. According to various industrial standards on interconnection and interoperability, IBRs should be able to withstand variability in grid conditions. Positive sequence voltage-oriented control (PSVOC) with a feed-forward decoupling approach is often adopted to ensure closed-loop control of inverters. However, the dynamic response of this control scheme deteriorates during fluctuations in the grid voltage due to the sensitivity of proportional–integral controllers, the presence of the direct- and quadrature-axis voltage terms in the cross-coupling, and predefined saturation limits. As such, a twin delayed deep deterministic policy gradient-based voltage-oriented control (TD3VOC) is formulated and trained to provide effective current control of inverter-based resources under various dynamic conditions of the grid through transfer learning. The actor–critic-based reinforcement learning agent is designed and trained using the model-free Markov decision process through interaction with a grid-connected photovoltaic inverter environment developed in MATLAB/Simulink^® 2023b. Using the standard PSVOC method results in inverter input voltage overshoots of up to 2.50 p.u., with post-fault current restoration times of as high as 0.55 s during asymmetrical faults. The designed TD3VOC technique confines the DC link voltage overshoot to 1.05 p.u. and achieves a low current recovery duration of 0.01 s after fault clearance. In the event of a severe symmetric fault, the conventional control method is unable to restore the inverter operation, leading to integral-time absolute errors of 0.60 and 0.32 for the currents of the d and q axes, respectively. The newly proposed agent-based control strategy restricts cumulative errors to 0.03 and 0.09 for the d and q axes, respectively, thus improving inverter regulation. The results indicate the superior performance of the proposed control scheme in maintaining the stability of the inverter DC link bus voltage, reducing post-fault system recovery time, and limiting negative sequence currents during severe asymmetrical and symmetrical grid faults compared with the conventional PSVOC approach. Full article

Based on the background of the continuously rising global demand for clean energy, offshore wind power, as an important form of renewable energy utilization, is booming. However, the pile foundations of offshore wind turbines are subject to long-term erosion in the harsh marine environment, and the problem of corrosion damage is prominent, which seriously threatens the safe and stable operation of the wind power system. In view of this, a meshless numerical simulation method based on smoothed particle hydrodynamics (SPH) and a method for generating the concrete meso-structures are developed. Concrete pile foundation models with different aggregate contents, particle sizes, and ion concentration diffusion coefficients are established to simulate the corrosion damage processes under various conditions. The rationality of the numerical algorithm is verified by a typical example. The results show that the increase in the aggregate percentage gradually reduces the diffusion rate of chemical ions, and the early damage development also slows down. However, as time goes, the damage will still accumulate continuously; when the aggregate particle size increases, the ion diffusion becomes more difficult, the damage initiation is delayed, and the early damage is concentrated around the large aggregates. The increase in the ion diffusion coefficient significantly accelerates the ion diffusion process, promotes the earlier and faster development of damage, and significantly deepens the damage degree. The research results contribute to a deeper understanding of the corrosion damage mechanisms of pile foundations and providing important theoretical support for optimizing the durability design of pile foundations. It is of great significance for ensuring the safe operation of offshore wind power facilities, prolonging the service life, reducing maintenance costs, and promoting the sustainable development of offshore wind power. Full article

The increasing environmental pollution resulting from plastic waste and the need to reuse agro-industrial wastes as a source of discarding has led to the development of innovative biobased products. In the frame of this context, the use of neat polylactic acid (PLA) and its blend with polybutylene succinate (PBS) with or without cellulose nanocrystals (CNCs) extracted from hemp fibers is explored here. This study aimed to assess the biogas production of different biopolymeric films. In parallel, life cycle assessment (LCA) analysis was performed on the same films, focusing on their production phase and potential end-of-life scenarios, regardless of film durability (i.e., single-use packaging) and barrier performance, to counteract possible soil health threats. Specifically, this study considered three specific systems: PLA, PLA_PBS (PLA/PBS blend 80:20 w/w), and PLA_PBS_3CNC (PLA/PBS blend + 3% CNCs) films. The assessment involved a batch anaerobic digestion (AD) process at 52 °C, using digestate obtained from the anaerobic treatment of municipal waste as the inoculum and cellulose as a reference material. The AD process was monitored over about 30 days, revealing that reactors containing cellulose showed inherent biodegradability and enhanced biogas production. On the other hand, biopolymeric films based on PLA and its blends with PBS and CNCs exhibited an inhibitory effect, likely due to their recalcitrant nature, which can limit or delay microbial activity toward biomass degradation and methanogenesis. LCA analysis was performed taking into consideration the complex environmental implications of both including biopolymers in the production of renewable energy and the use of post-composting digestate as an organic fertilizer. Remarkably, the PLA_PBS_3CNC formulation revealed slightly superior performance in terms of biodegradability and biogas production, mainly correlated to the presence of CNCs in the blend. The observed enhanced biodegradability and biogas yield, coupled with the reduced environmental impact, confirm the key role of optimized biopolymeric formulations in mitigating inhibitory effects on AD processes while maximizing, at the same time, the utilization of naturally derived energy sources. Full article

Under the background of achieving carbon dioxide peaking and carbon neutrality, the rapid development of renewable energy power generation poses new challenges to the flexible adjustment capabilities of traditional power plants. To explore the furnace combustion stability and optimal operation modes during deep peak shaving, a simulation of the combustion process under low-load conditions for a 600 MW wall-fired boiler is performed utilizing computational fluid dynamics (CFD) analysis. The impact of burner combination modes on the combustion process within the furnace is explored at 25% and 35% boiler maximum continuous ratings (BMCRs). This study investigates two configurations of burner combinations. One mode operates burners in layers A, B, and C, which include the lower layers of burners on the front and rear walls of the boiler, as well as the middle-layer burners on the rear wall, referred to as OM1. The other mode operates burners in layers A and C, which include the lower layers of burners on the front and rear walls of the boiler, referred to as OM2. The results indicate that OM2 exhibits superior capabilities in orchestrating the distribution of the airflow velocity field and temperature field under the premise of ensuring no more than a 1% decrease in the pulverized coal burnout rate. When OM1 is employed, the airflow ejected from the middle-level burners hinders the upward movement of pulverized coal sprayed from the lower-level burners, causing a larger proportion of pulverized coal to enter the ash hopper for combustion. Consequently, the ash hopper attains a peak mole fraction of CO₂ at 0.163. OM2 delays the blending of pulverized coal with air by enhancing the injection quantity of pulverized coal per burner. As a result, the generation of CO in the ash hopper reaches a notable mole fraction of up to 0.108. The decreased furnace temperature promotes the formation of fuel-based NO_x during low-load operation. Taking the 25% BMCR as an example, the NO_x emissions measured at the furnace outlet are 743 and 1083 ppm for OM1 and OM2, respectively. This study focuses on the impact of combustion combinations on the combustion stability when the boiler is operating at low loads. The findings could enrich previous research on combustion stability and contribute to the optimization of combustion schemes for power plant boilers operating at low loads. Full article