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Optimizing waste cooking biodiesel production using ultrasonic-assisted and studying its combustion characteristics blended with diesel in diesel engine

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Environmental Science and Pollution Research 2025年第11期32卷 6984-7001页

作者： Belal, Belal Y. Li, Gesheng Zhang, Zunhua Liang, Junjie Zhou, Mengni Masoud, Shaimaa M. Attia, Ali M. A. El-Zoheiry, Radwan M. El-Seesy, Ahmed I. School of Naval Architecture Ocean and Energy Power Engineering Wuhan University of Technology Hubei Wuhan430063 China Mechanical and Nuclear Engineering Department College of Engineering and Physical Sciences Khalifa University Abu Dhabi127788 United Arab Emirates Mechanical Engineering Department College of Engineering University of Bisha Bisha Saudi Arabia Mechanical Engineering Department Benha Faculty of Engineering Benha University Qalubia Benha Egypt

This study aimed to optimize biodiesel production from waste cooking oil using ultrasonic-assisted transesterification and evaluate the combustion characteristics of a diesel engine powered by various biodiesel blends. The effects of transesterification parameters, including reaction time, alcohol-to-oil molar ratio, catalyst concentration, and ultrasonic amplitude, were experimentally investigated. The optimal conditions for achieving a biodiesel yield of 96.65% were found to be a reaction time of 6 min, an alcohol-to-oil molar ratio of 6:1, a catalyst concentration of 1.0 wt.%, and an ultrasonic amplitude of 75% with a duty cycle of 0.7. In the subsequent phase, engine performance and emissions were evaluated for biodiesel–diesel blends at volume ratios of 0:100 (B0), 10:90 (B10), 20:80 (B20), 30:70 (B30), 40:60 (B40), and 100:0 (B100) under varying load conditions at a constant speed of 1500 rpm. The results indicated that biodiesel blends exhibited similar engine performance to diesel, with a slight increase in brake-specific fuel consumption and a minor decrease in brake thermal efficiency. Emission analysis revealed significant improvements, with B100 reducing carbon monoxide (CO), unburned hydrocarbons (HC), and smoke opacity by 42.9%, 29.9%, and 42.1%, respectively, compared to B0. Notably, B40 showed the highest reduction in nitrogen oxide (NOx) emissions, achieving a 4.94% decrease. These findings suggested that B40 can serve as a viable diesel substitute without requiring fuel system modifications, offering comparable mechanical performance and enhanced emission characteristics. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.

关键词： Waste incineration

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Retrofitting Design of a Deep Drilling Rig Mud Pump Load Balancing System

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Energy engineering 2025年第5期122卷 1669-1696页

作者： Danijel Pavkovic Pietro Kristovic Mihael Cipek Dragutin Lisjak Faculty of Mechanical Engineering and Naval Architecture University of ZagrebZagrebHR-10000Croatia

In deep drilling applications,such as those for geothermal energy,there are many challenges,such as those related to efficient operation of the drilling fluid(mud)pumping *** drilling rigs often use paired,parallel-connected independent-excitation direct-current(DC)motors for mud pumps,that are supplied by a single power *** configuration results in electrical power imbalance,thus reducing its *** paper investigates this power imbalance issue in such legacy DC mud pump drive systems and offers an innovative solution in the form of a closed-loop control system for electrical load *** paper first analyzes the drilling fluid circulation and electrical drive layout to develop an analytical model that can be used for electrical load balancing and related energy efficiency *** on this analysis,a feedback control system(so-called“current mirror”control system)is designed to balance the electrical load(i.e.,armature currents)of parallel-connected DC machines by adjusting the excitation current of one of the DC machines,thus mitigating the power imbalance of the electrical *** control systemeffectiveness has been validated,first through simulations,followed by experimental testing on a deep drilling rig during commissioning and field *** results demonstrate the practical viability of the proposed“current mirror”control system that can effectively and rather quickly equalize the armature currents of both DC machines in a parallel-connected electrical drive,and thus balance both the electrical and mechanical load of individual DC machines under realistic operating conditions of the mud pump electrical drive.

关键词： Deep drilling mud pump electrical load balancing direct current motor excitation control armature current mirroring field tests

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Academic Careers for Women in Nondestructive Testing A Perspective on Barriers and Opportunities

e-Journal of Nondestructive Testing

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e-Journal of Nondestructive Testing 2025年第3期30卷

作者： Grozdanić, Maria Faculty of Mechanical Engineering and Naval Architecture University of Zagreb Croatia

Maria Grozdanić, a PhD student and teaching assistant at the faculty of mechanical engineering and naval architecture, University of Zagreb, specializes in ultrasonic testing (UT) and nondestructive testing (NDT). Driven by a fascination with "seeing the invisible," this her passion for NDT sparked during undergraduate studies, leading to a PhD in ultrasonic testing. Inspired by trailblazing women who paved the way, she aims to carve her own path while advocating for NDT's significance among students as a university teaching assistant. Recognizing academia as a space where knowledge and hard work transcend gender barriers, she emphasizes the importance of supportive mentors and continuous skill refinement. Her message to young women in NDT is to seek mentors who value their contributions and treat them as equals, highlighting women's strength and capability to lead, innovate, and shape NDT's bright future. © 2025 The Authors.

关键词： Students

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Application of Deep Learning Models for Predicting Health Alerts in Pilots 3rd

Application of Deep Learning Models for Predicting Health Al...

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3rd International Conference on Cognitive Mobility, CogMob 2024

作者： Zolfaghari, Farzad Kale-Halasz, Györgyi Alharasees, Omar Kilikevicius, Arturas Department of Mechanical Engineering Faculty of Mechanics Vilnius Tech University Vilnius Lithuania Robert Bosch Kft. Budapest Hungary Department of Aeronautics and Naval Architecture Faculty of Transportation Engineering and Vehicle Engineering Budapest University of Technology and Economics Budapest Hungary

ISBN: (纸本)9783031817984

Aviation’s safety relies on pilots’ well-being, making health monitoring vital. Traditional health monitoring methods, including self-reported assessments, often fail to accurately capture emerging health problems, necessitating a more proactive and reliable solution. This study explores the use of deep learning (DL) models to predict pilots’ health alerts based on physiological data—heart rate (HR), heart rate variability (HRV), and respiratory rate (RR)—from both experienced and non-experienced pilots in flight simulations. A deep neural network (DNN) was developed, achieving 94.87% accuracy, 95.45% precision, 94.07% recall, and 99.28% AUC in classifying pilot health statuses. These results highlight the model’s potential to identify at-risk pilots, enabling timely interventions and advancing proactive health monitoring, ultimately enhancing aviation safety and operational efficiency. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.

关键词： Electronic health record

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Developing a Morphing Wingtip: Aeroelastic Design and FSI Analysis

Developing a Morphing Wingtip: Aeroelastic Design and FSI An...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Boughou, Smail Omar, Ashraf A. Batistić, Ivan Boukharfane, Radouan Inman, Daniel J. School of Aerospace and Automotive Engineering Université Internationale de Rabat Rabat Morocco Faculty of Mechanical Engineering and Naval Architecture University of Zagreb Zagreb Croatia Benguerir Morocco Department of Aerospace Engineering University of Michigan Ann ArborMI United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

This paper analyzes the implementation of a flexible wingtip and its impact on aerodynamic performance. The interaction between the fluid and the flexible wing is modeled by employing a partitioned FSI approach and finite volume solvers for both fluid and solid domains. The flexible wingtip is simulated by varying the distribution of material properties along the wing span. The impact of wing deformation on airflow dynamics is analyzed, specifically with regard to changes in the separation bubble. It describes how the deformation of a flexible wingtip causes the separation bubble to increase in size and move towards the leading edge, potentially disrupting airflow and reducing lift efficiency. This understanding is vital to improving the design and performance of wings, particularly in flexible wings. The ongoing research aims to fully understand the impact of the flexible wingtip on the performance of this concept, paving the way for groundbreaking advances in aeronautical engineering. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Flexible wings

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Assessment of the effect of speed and scale on the total resistance and its components for a bulk carrier

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Results in engineering 2025年 26卷

作者： Grlj, Carlo Giorgio Degiuli, Nastia Martić, Ivana University of Zagreb Faculty of Mechanical Engineering and Naval Architecture Ivana Lučića 5 Zagreb10000 Croatia

Reducing greenhouse gas emissions has become one of the primary goals for maritime transport today. One widely adopted, short-term, and cost-effective operational measure is slow steaming. Therefore, it is essential to assess the resistance characteristics of ships operating at reduced speeds, given that each vessel is optimized for a specific design speed. Computational fluid dynamics is employed to predict the total resistance coefficient and its components and to determine the form factor at various speeds and scales. The numerical approach is based on the Reynolds Averaged Navier-Stokes equations, discretized using the finite volume method. The study employs two numerical approaches: simulations conducted both with and without the presence of the free surface. This allows the decomposition of the total resistance coefficient into its components, namely, frictional, viscous pressure, and wave resistance coefficients. The results show significant scale effects and a minor effect of speed on the total resistance coefficient and its components. The total resistance coefficient and its components decrease as speed increases and scale decreases. The virtual fluid method is employed, and the results show that the total resistance coefficient and its components for the full-scale ship can be derived from numerical simulations conducted at model scale. Although speed has a minor effect on the form factor, significant scale effects are observed. © 2025 The Author(s)

关键词： Navier Stokes equations

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New approach to organization of interlaboratory comparisons on calibration of climatic chambers

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Measurement: Sensors 2025年

作者： Matas, Ivan Šestan, Danijel Bermanec, Lovorka Grgec University of Zagreb Faculty of Mechanical Engineering and Naval Architecture Laboratory for Process Measurement Zagreb Croatia

This paper presents a new approach to organization and conduction of interlaboratory comparisons on calibration of climatic chamber with the goal of elimination of the influence of drift and instability of the chamber on the comparison results and overall decrease in conduction time which also contributes to lower energy consumption. The proposed approach has been evaluated through a simulation of bilateral comparison using two independent measurement systems developed and characterized at The Laboratory for Process Measurement at the faculty of mechanical engineering and naval architecture. The new comparison measurement approach has been compared to the traditional comparison conduction method with separate measurements of all participating laboratories. © 2024

关键词： naval architecture

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Investigation of the influence of measurement duration on results of resistance bridge ratio error assessment

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Measurement: Sensors 2025年

作者： Šestan, Danijel Matas, Ivan Bermanec, Lovorka Grgec University of Zagreb Faculty of Mechanical Engineering and Naval Architecture Ivana Lucica 5 Zagreb Croatia

The realization and dissemination of the International Temperature Scale (ITS-90) relies greatly on the performance of resistance ratio bridges that are used for the precise measurement of electrical resistances of standard platinum resistance thermometers (SPRTs). Characterization of resistance bridges has been made significantly easier since the invention of resistance bridge calibrators (RBCs), which can be used for the determination of ratio error and linearity of a resistance ratio bridge. Even though there has been a lot of research on the operation and performance of RBCs, the influences of measurement time on the results of resistance ratio bridge characterizations have not been investigated in much detail yet. Minimizing measurement time for each separate resistance ratio leads to a reduction of the overall duration of the characterization process, which could easily exceed 10 hours. It could also lead to the reduction of uncertainty of bridge characterization since its results rely greatly on the stability of the RBC's resistances as well as the resistance of the standard resistor connected to the bridge during the entire characterization process. In this research, a new method is proposed for the determination of the minimum delay required between changing the RBC resistance and start taking the readings, as well as for the determination of a minimum number of readings that should be taken by resistance ratio bridge for obtaining representative overall characterization results. © 2024

关键词： Velocity measurement

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Fully Few-Shot Class-Incremental Audio Classification With Adaptive Improvement of Stability and Plasticity

IEEE Transactions on Audio, Speech and Language Processing

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IEEE Transactions on Audio, Speech and Language Processing 2025年 33卷 418-433页

作者： Yongjie Si Yanxiong Li Jiaxin Tan Guoqing Chen Qianqian Li Mladen Russo School of Electronic and Information Engineering South China University of Technology Guangzhou China Faculty of Electrical Engineering Mechanical Engineering and Naval Architecture University of Split Split Croatia

In the problem of Few-shot Class-incremental Audio Classification (FCAC), training samples per class in the base session are required to be abundant. However, in many scenarios, it is difficult to collect abundant training samples in the base session because of data scarcity and high collection cost. In this paper, we explore a new FCAC problem, namely Fully FCAC (FFCAC), in which training samples for all classes in both the base and incremental sessions are few. Moreover, we propose a FFCAC method by adaptively improving the model's stability for seen classes and plasticity for unseen classes. The model consists of an Embedding Extractor (EE) and an Evolvable Classifier (EC). The EE consists of an encoder of pretrained Audio Spectrogram Transformer (AST), an encoder of finetuned AST and three fusion modules. In each incremental session, the two encoders are frozen for memorizing the knowledge learned by the model and thus can improve the model's stability. The three fusion modules are used to fuse the embeddings output by the two encoders. The EC is composed of a fully-connected layer and a Softmax layer. The fusion modules and EC are updated in incremental sessions to improve the model's plasticity for unseen classes. Besides, two losses are defined to train the model in the base and incremental sessions. Results on three public audio datasets (LS-100, NSynth-100, and FSC-89) show that our FFCAC method exceeds previous methods in accuracy under many conditions.

关键词： Training Adaptation models Stability analysis Speech processing Data models Computational modeling Vectors Transformers Training data Testing

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Integrated Torque and Inertia Phase Model Predictive Controls of Automatic Transmission Upshifts

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IEEE Transactions on Vehicular Technology 2025年

作者： Cvok, Ivan Soldo, Jure Deur, Josko Ivanovic, Vladimir Zhang, Yijing Fujii, Yuji University of Zagreb Faculty of Mechanical Engineering and Naval Architecture Zagreb10002 Croatia Ford Research and Advanced Engineering DearbornMI48124 United States

Advanced step-ratio automatic transmission shift control that can provide optimal shift performance and reduce calibration effort is highly sought after in today's product development environment. This article explores Control Allocation (CA) and Model Predictive Control (MPC) concepts to meet the requirements for both conventional and electrified powertrains such as parallel hybrid electric transmissions. The CA and MPC strategies, previously proposed for the upshift inertia phase, are extended in this article to torque phase to obtain integrated optimal shift control strategies. These strategies optimally coordinate oncoming and off-going clutch torque with engine torque to balance the conflicting shift quality criteria reflecting shift comfort, duration, and efficiency. The designer sets the shift quality requirements through torque and inertia phase durations, reference and constraint profiles, and cost function weights, which facilitates calibration of the control strategy performance. To further improve the performance, the CA strategy is extended with a virtual torque sensor system during the torque phase. Two variants of MPC strategy are proposed and compared: (i) separate MPCs for torque and inertia phase and (ii) integrated MPC whose prediction model in torque phase spreads to the inertia phase. The CA and MPC strategies are realized in the form of constrained quadratic programs and efficiently solved on-line by an interior-point solver. Their performance is demonstrated and compared via nonlinear powertrain model simulations for 1-3 shift, including a system robustness analysis with respect to actuation parameter uncertainties. © 2025 IEEE. All rights reserved.

关键词： Model predictive control

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