Oumaima Mikram, Abdelmajid Abouloifa, Ibtissam Lachkar
et al.
The widespread adoption of nonlinear loads in industry has introduced significant power quality issues in electric power distribution grids. The integration of these nonlinear loads has led to the proliferation of serious power quality problems such as the generation of harmonics and reactive power that negatively impact the quality and stability of the electrical grid. In addition to eliminating current harmonics, a shunt active power filter (APF) can also provide reactive power compensation. By dynamically adjusting the reactive power injection, these APFs can improve the power factor of the system and maintain the desired voltage regulation. The proposed control leverages the differential flatness property of the SAPF system, allowing for exact linearization and simplified tracking control without requiring complex modulation techniques. In this paper, a flatness-based control scheme is proposed for a three-phase three-level Neutral Point Clamped (NPC) APF. The main objectives of this work are twofold. The first objective is to mitigate current harmonics and compensate the reactive power drawn by nonlinear loads. The second objective focuses on maintaining a stable DC-link capacitor voltage of the active power filter (APF). To meet these requirements, a cascaded control structure is used, where the external loop regulates the DC-link voltage, while the inner loop is responsible for harmonic current compensation. The effectiveness of the proposed control strategy is validated through simulation results obtained using the MATLAB/Simulink R2024a environment.
Lignocellulosic biomass is one of the most abundant renewable carbon resources available, currently used predominantly for energy generation through direct combustion, yet still underutilized as a feedstock for higher-value biochemical conversion. Its structural complexity and intrinsic recalcitrance continue to challenge efficient biological processing. Overcoming these barriers requires an integrated understanding of plant cell-wall architecture, pretreatment chemistry, enzymatic mechanisms, and process engineering. This review provides a clear and conceptually grounded synthesis of these elements, illustrating how they converge to enable the development of second-generation (2G) lignocellulosic biorefineries. This review examines the hierarchical organization of cellulose, hemicelluloses, and lignin; the principles and performance of modern pretreatment technologies; the synergistic action of cellulolytic systems, including lytic polysaccharide monooxygenases (LPMOs) and non-hydrolytic proteins such as swollenins; advances in C5/C6 sugar fermentation; and emerging strategies for lignin upgrading. In addition to a comprehensive analysis of the literature, representative industrial and experimental case studies reported in the literature are discussed to illustrate practical process behavior and design considerations. By integrating mechanistic insight with industrially relevant examples, this review highlights the technical feasibility, current maturity, and remaining challenges of lignocellulosic biorefineries, underscoring their strategic role in enabling a competitive, low-carbon bioeconomy.
Kampala faces increasing congestion, air pollution, and dependence on fossil fuels, driven by widespread reliance on diesel minibuses and motorcycle taxis. Existing models—KAMPALA-TIMES, KLAP-TIMES, and GKMA-TIMES–CGE—show strong potential for electrified mass transit to reduce emissions, change commuter behavior, and boost macroeconomic welfare. However, these studies assume electric-bus reliability without examining the mechanical conditions needed to achieve their projected outcomes. This study combines system-level modeling insights with vehicle-level engineering analysis to identify key mechanical factors necessary for the successful deployment of electric Bus Rapid Transit (e-BRT) in Kampala. It considers drivetrain torque for steep gradients, battery thermal management in hot equatorial climates, and regenerative braking efficiency in traffic congestion, alongside policy, infrastructure, and grid readiness. Mechanical performance links modeling to implementation—adequate torque, thermal stability, and regenerative braking efficiency directly affect service reliability, headway adherence, fleet uptime, and lifecycle costs. These operational factors influence commuter mode choices, the realism of bottom-up pathways, and the broader economic benefits predicted in top-down scenarios. Engineering reliability must be a core policy consideration, guiding procurement standards, charging infrastructure design, and multisector coordination among KCCA, MoWT, MEMD, and Uganda’s power utilities. Incorporating mechanical parameters into future bottom-up or hybrid models, combined with digital-twin testing and degradation-aware analytics, will enable Kampala to serve as a living laboratory for low-carbon mobility transitions across Sub-Saharan Africa.
Annex A of EN 1992-1-1:2023—recently revised and amended in the context of the Second Generation of Eurocodes—introduces a method to adjust partial safety factors for the resistance side alongside a set of factors for different conditions and design situations, both for new and existing structures. The method proposed in Annex A is complemented by a set of stochastic models for relevant basic variables and forms a rather simple and objective format to adjust the partial safety factors from the default values offered in EN 1990:2023. Yet, over the last few years, advanced reliability-based methods aligned with modern computational tools have proved to enable rather robust and efficient structural reliability assessments. A thorough comparative analysis is imperative to understand how distinct reliability-based methods can be applied to adjust partial safety factors in the design of new structural components composed of steel-reinforced concrete. This analysis sheds light on the use of different methods to derive partial safety factors for the resolution of common engineering problems and offers inferences regarding possible implications in terms of safety and economic efficiency of design solutions.
The on-load tap changer (OLTC), widely used as a voltage regulation device in power systems, requires regular assessment and maintenance to ensure reliable operation and avoid adverse impacts on the power system. These assessments encompass key parameters such as transition waveform, transition time, three-phase synchronization, and transition resistor, along with the operational status of the mechanical structure. However, the maintenance process, typically conducted offline, can diminish equipment efficiency. Moreover, the accuracy of some parameter measurements needs improvement. To bolster equipment reliability and refine detection methods for critical parameters, this study explores online detection techniques for key switching parameters of the OLTC body. This paper proposes a method to identify these key parameters in the switching circuit, using coordinate transformation as the core algorithm. We used a specific vacuum OLTC device for our research, conducted theoretical analyses, developed a simulation model to validate the proposed method for identifying OLTC switching parameters, and further built a test platform to verify the algorithm’s effectiveness. The results show a close alignment between simulation and actual measurement outcomes. Each switching process interval conforms to the manufacturer’s design specifications for the equipment, with the transition resistor parameter calculation accuracy ranging from approximately 95.39% to 100%. Similarly, the tap winding voltage calculation accuracy is between approximately 91.52% and 100%, satisfying engineering requirements and enterprise standard [1]. This method provides a basis for optimizing the measurement of working parameters in OLTC equipment and aims to offer ideas for the next step of prototype development.
Production of electric energy or power. Powerplants. Central stations
Using the multiellipse-based discrete element method (DEM), we numerically study the biaxial shearing behavior of granular materials composed of star-shaped particles. These particle shapes are generated by overlapping two or three identical ellipses with a common center of mass, while varying the aspect ratio from 1 to 5. Our results reveal that the macroscopic shear strength of the system increases monotonically with particle non-convexity. In contrast, the packing fraction exhibits a non-monotonic dependence on non-convexity, initially increasing and then decreasing as non-convexity further grows. This behavior reflects variations in the local pore size due to the competition between short-range ordering and excluded volume effects. Furthermore, microscopic analysis indicates that the increase in shear strength is linked to higher contact numbers and reduced contact and inter-grain distances, corresponding to stronger interlocking at higher non-convexity.
［Objective］ By establishing a numerical seepage analysis model that aligns with real drainage systems and introducing the concept of a ′virtual permeability coefficient′ for secondary lining, the objective is to delve into the correlation between numerical methods and theoretical formulas, with expectation to leverage the efficiency and practicality of theoretical formulas in predicting external water pressure. ［Method］ Based on the principle of equivalent stable drainage volume in underwater tunnels, the concept of a ′virtual permeability coefficient′ for the secondary lining is introduced. On this basis, key factors, including the spacing of circumferential drainage blind pipes, the thickness of geotextiles, and their permeability coefficients, are selected as primary research factors. By adjusting these factors, multiple numerical seepage analysis models consistent with real drainage systems are established. ［Result & Conclusion］ The actual external water pressure acting on the secondary lining exhibits significant spatial distribution characteristics. Longitudinally, the variation in external water pressure displays periodic fluctuations corresponding to the spacing of circumferential drainage blind pipes. Circumferentially, the closer the position is to the longitudinal drainage blind pipe, the lower the external water pressure, with maximum circumferential water pressure occurring at the arch vault, followed by the inverted arch, and the smallest pressure on sidewalls. The reduction coefficients of external water pressure calculated with theoretical formulas are generally smaller than those derived from numerical methods. The stronger the drainage capacity of the design parameters, the smaller the difference between the two calculation results. The reduction coefficient consistently follows a decreasing trend from the vault to the invert to the sidewalls. When applying theoretical formulas directly in quantitative engineering design, it is necessary to introduce a comprehensive correction factor greater than 1.0 to ensure engineering safety. The value of comprehensive correction factor should be determined based on the specific structural location, with zones divided by the sidewalls. For the upper structure, a range of 1.48-1.97 is recommended, while a proper range of 1.21-1.39 for the lower structure
Inverter material is one of the essential materials in power electronics courses. An inverter is an electronic device that converts direct current (DC) into alternating current (AC). This concept is the foundation of electronics. Because the power electronics course is a practicum course, a practicum module is required as an intermediary teaching medium; this practical module discusses 3-phase inverter material, which uses the pulse width modulation (PWM) and sinusoidal pulse width modulation inverter (SPWM) switching methods. Through Tinkercad software, the circuit is assembled, and the output wave results from the two methods used are seen in designing the 3-phase inverter practical module using the Research and Development method. This research uses media and material validation sheet instruments to determine the feasibility of the 3-phase inverter practicum module. The research results showed that the percentage of media experts was 94%, material experts were 81%, and language experts were 84%. Hence, the 3-phase inverter practicum module is very suitable for use and can make it easier for students to understand inverters. Thus, developing a 3-phase inverter practicum module can effectively increase students' understanding of inverter material and interest in learning. It can also be an alternative for lecturers in teaching.
Rahele Sadeghzadeh, Fatemeh Rafieian, Mahdi Keshani
et al.
Pseudomonas aeruginosa is a Gram-negative human pathogenic bacterium that has the ability to form multicellular biofilm (BF) communities. Due to the presence of extracellular polymeric substances, BF protects bacteria from unfavorable environmental conditions and causes their resistance to antimicrobial substances. The presence of BF in the food industry has become a great threat to food safety. Conventional disinfection technologies are inappropriate for effective BF control due to the resistances created to them and the toxic residues for humans and the environment that they leave behind. Therefore, it is necessary to understand more about the formation and development of BF and environmentally friendly methods to remove BF from food and equipment in contact with food. This review article describes BF formation, its resistance mechanisms to antimicrobial agents, and BF development. Also, novel and effective strategies involved in BF removal are discussed including physical methods (plasma, pulsed electric field and ultrasonication), physicochemical method (electrolyzed water), biological methods (enzymes and bacteriophages), natural compounds such as essential oils, and application of nanomaterials.
Nutrition. Foods and food supply, Food processing and manufacture
Abdallah Dayhoum, Alejandro Ramirez-Serrano, Robert J. Martinuzzi
This study explores the implications of the number of blades on the performance of both open and shrouded rotors. By conducting a thorough experimental analysis at a fixed solidity ratio, this research seeks to enhance our understanding of rotor dynamics and efficiency. Two-, three-, four-, and five-bladed rotors were designed and manufactured to have the same solidity ratio. This leads to smaller chord distribution values for higher blade numbers. The experimental analysis aims to quantify the effects of the number of blades and provides a comparative analysis of performance differences between the two rotor configurations (shrouded and open). For the open rotor, results indicate that increasing the number of blades has a minimal impact on overall performance. This is due to the decrease in the tip loss factor being counterbalanced by a decline in efficiency caused by the two-dimensional airfoil performance, which results from a smaller chord and a lower Reynolds number. In contrast, the shrouded rotor exhibits a noticeable performance decay with an increased blade count. Since tip loss is inherently absent in shrouded designs, the decline is primarily attributed to the two-dimensional airfoil performance. This decay occurs while maintaining a constant solidity ratio, highlighting the significant effect of blade count on shrouded rotor efficiency, thereby contributing to the optimization of rotor design in various engineering applications.
Julien Guerrero, Ekaterina Maevskaia, Chafik Ghayor
et al.
Additive manufacturing has emerged as a transformative tool in biomedical engineering, offering precise control over scaffold design for bone tissue engineering and regenerative medicine. While much attention has been focused on optimizing pore-based scaffold architectures, filament-based microarchitectures remain relatively understudied, despite the fact that the majority of 3D-printers generate filament-based structures. Here, we investigated the influence of filament characteristics on bone regeneration outcomes using a lithography-based additive manufacturing approach. Three distinct filament-based scaffolds (Fil050, Fil083, and Fil125) identical in macroporosity and transparency, crafted from tri-calcium phosphate (TCP) with varying filament thicknesses and distance, were evaluated in a rabbit model of bone augmentation and non-critical calvarial defect. Additionally, two scaffold types differing in filament directionality (Fil and FilG) were compared to elucidate optimal design parameters. Distance of bone ingrowth and percentage of regenerated area within scaffolds were measured by histomorphometric analysis. Our findings reveal filaments of 0.50 mm as the most effective filament-based scaffold, demonstrating superior bone ingrowth and bony regenerated area compared to larger size filament (i.e., 0.83 mm and 1.25 mm scaffolds). Optimized directionality of filaments can overcome the reduced performance of larger filaments. This study advances our understanding of microarchitecture’s role in bone tissue engineering and holds significant implications for clinical practice, paving the way for the development of highly tailored, patient-specific bone substitutes with enhanced efficacy.
Achieving the dual carbon goal is a profound and challenging social transformation. The difficulty is mainly reflected in the fact that economic growth is usually linked to energy consumption. In today's society, no country or industry can completely abandon traditional energy, and the use of traditional energy, namely fossil fuels, would bring carbon emissions. Therefore, reducing carbon emissions while ensuring economic growth and achieving the dual carbon goals is an important issue at present. This article conducted a series of carbon emission analysis and carbon reduction path research for power generation enterprises, which are the major emitters of carbon emissions, based on the background of dual carbon goals.
Sameh Alsaqoor, Ahmad Alqatamin, Ali Alahmer
et al.
This study examines the impact of incorporating phase change material (PCM) in photovoltaic thermal (PVT) systems on their electrical and thermal performance. Although PVT systems have shown effectiveness in converting solar energy into both electricity and heat, there is a necessity for studies to investigate how integrating PCMs can further enhance performance. The study also aims to explore the effect of solar irradiation and coolant mass flow rate on the electrical and thermal output of both PVT and PVT-PCM systems. A graphical user interface was developed within the MATLAB Simulink under the weather conditions of Amman, Jordan. The results show that the incorporation of PCM in PVT systems significantly reduces solar cell temperature and increases electrical efficiency. The highest electrical efficiency of a PVT system with PCM was found to be 14%, compared to 13.75% in a PVT system without PCM. Furthermore, the maximum achievable electrical power in a PVT system with PCM was 21 kW, while in the PVT system without PCM it was 18 kW. The study also found that increasing the coolant mass flow rate in a PVT system with PCM further reduced PV cell temperature and increased electrical efficiency, while the electrical efficiency of both the PVT and PVT-PCM systems decreases as solar incident radiation flux increases, resulting in a significant rise in cell temperature. At an increased solar radiation level from 500 W/m2 to 1000 W/m2, the electrical efficiency of the PVT configuration decreases from 13.75% to 11.1%, while the electrical efficiency of the PVT-PCM configuration falls from 14% to 12%. The findings of this study indicate that the use of PCM in PVT systems can lead to significant improvements in energy production and cooling processes. The results provide valuable information for designing and optimizing PVT-PCM systems.
Drilling and blasting is still the most widely used method for tunnel excavation in hard rocks. However, this method causes damage to adjacent buildings and structures mainly because of tunnel blast-induced vibrations. Currently, no specific guidelines are available for optimizing the design of damping holes during controlled blasting. Therefore, this study analyzes the vibration reduction mechanism of damping holes. Six key factors, namely, hole radius, hole spacing, coverage length, arrangement type, number of rows, and row spacing, that can affect the blasting vibration reduction were analyzed theoretically. Six groups of 30 numerical models were established using LS-DYNA. The influences of the six factors on the average and maximum velocities and stress vibration reduction were analyzed to quantitatively evaluate their damping effects. Then, optimization design suggestions for damping holes were proposed. The results revealed that it is necessary to increase the hole diameter and reduce the hole and row spacings as much as possible. The reasonable coverage length of damping holes is 1.5 times the coverage length of blasting holes. The blossom-type arrangement is recommended for practical engineering applications and the number of rows of damping holes should not exceed four. Guidelines for reducing vibration in adjacent tunnel blasting were formulated. Finally, the optimized damping hole design was applied to a typical tunnel project, which verified its reasonability and applicability.
Materials of engineering and construction. Mechanics of materials
The low thermal conductivity of phase change materials (PCMs) is a crucial challenge in utilizing latent heat thermal energy storage (LHTES) systems. Incorporating fins into LHTES system is an effective approach to overcoming the low thermal conductivity of PCM and enhancing its performance. In the present study, computational fluid dynamics is used to investigate the effects of fin configurations and operating conditions on the performance of a shell-and-tube system assisted by fins. The heat transfer rate and liquid fraction are investigated to evaluate the thermal behavior of the proposed system. The enthalpy–porosity technique is employed to simulate the phase change. The temperature variations over time at different PCM locations are calculated and compared with the measured temperatures. The predicted results show that the fin thickness and the inlet temperature of the heat transfer fluid play a key role in reducing the melting and solidification time. The obtained results indicated that by increasing the fin thickness from 0.5 to 1 mm, the heat transfer rate increased by approximately 17%. Also, increasing the inlet temperature from 60 °C to 65 °C improved the heat transfer rate by 36.2%.
The use of fire safety engineering and performance-based techniques continues to grow in prominence as building design becomes more ambitious, increasing complexity. National fire safety enforcement agencies are tasked with evaluating and approving the resulting fire strategies, which have similarly continued to become more advanced and specialist. To assist with the evaluation of fire strategies, this paper introduces a methodology dedicated to sustainable building fire safety level simulations. The methodology derives from ideas originally introduced in British Standard Specification PAS 911 in 2007 and combines a visual representation of fire strategies with a semi-quantitative approach to allow for their evaluation. The concept can be applied to a range of industrial fire safety assessments and can be modified for specific needs relative to different industries.
As time passes, some elements of the structures are affected by local damage, though insignificantly. With the development and expansion of the damage , these structures may be completely destroyed and impose high socioeconomic costs. This study investigated the damage identification problem in the column under the axial load using modal data (frequencies and mode shapes) and wavelet transform analysis. The obtained results showed that by increasing the axial load proportional to the critical buckling load, the frequency value decreases in all modes in healthy and faulty modes. Additionally, under the effect of the same axial load, the frequency of the faulty sample is less than that of the healthy one, and as the damage severity increases, the rate of frequency reduction increases. The wavelet transform input signal was defined on the basis of the angle between the healthy and faulty mode shapes. The output signal details in the damage locations indicated perturbation so that in all the studied modes in different ratios of critical load, the damage locations were identified with high accuracy. Moreover, the results from the research showed that the perturbations in different damage locations are independent of each other and are only affected by the severity of the location damage and the axial load has no effect on the damage detection sensitivity of the wavelet transform algorithm. Furthermore, the sum of the wavelet coefficients of damaged locations in several damage modes is equal to the wavelet coefficients of damaged locations of the sum of damage modes.
Noela Rodriguez-Losada, Noela Rodriguez-Losada, Rune Wendelbob
et al.
Emerging scaffold structures made of carbon nanomaterials, such as graphene oxide (GO) have shown efficient bioconjugation with common biomolecules. Previous studies described that GO promotes the differentiation of neural stem cells and may be useful for neural regeneration. In this study, we examined the capacity of GO, full reduced (FRGO), and partially reduced (PRGO) powder and film to support survival, proliferation, differentiation, maturation, and bioenergetic function of a dopaminergic (DA) cell line derived from the mouse substantia nigra (SN4741). Our results show that the morphology of the film and the species of graphene (GO, PRGO, or FRGO) influences the behavior and function of these neurons. In general, we found better biocompatibility of the film species than that of the powder. Analysis of cell viability and cytotoxicity showed good cell survival, a lack of cell death in all GO forms and its derivatives, a decreased proliferation, and increased differentiation over time. Neuronal maturation of SN4741 in all GO forms, and its derivatives were assessed by increased protein levels of tyrosine hydroxylase (TH), dopamine transporter (DAT), the glutamate inward rectifying potassium channel 2 (GIRK2), and of synaptic proteins, such as synaptobrevin and synaptophysin. Notably, PRGO-film increased the levels of Tuj1 and the expression of transcription factors specific for midbrain DA neurons, such as Pitx3, Lmx1a, and Lmx1b. Bioenergetics and mitochondrial dysfunction were evaluated by measuring oxygen consumption modified by distinct GO species and were different between powder and film for the same GO species. Our results indicate that PRGO-film was the best GO species at maintaining mitochondrial function compared to control. Finally, different GO forms, and particularly PRGO-film was also found to prevent the loss of DA cells and the decrease of the α-synuclein (α-syn) in a molecular environment where oxidative stress has been induced to model Parkinson's disease. In conclusion, PRGO-film is the most efficient graphene species at promoting DA differentiation and preventing DA cell loss, thus becoming a suitable scaffold to test new drugs or develop constructs for Parkinson's disease cell replacement therapy.