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Magnetic modulation of keyhole instability during laser welding and additive manufacturing

Science (New York, N.Y.) 2025年第6736期387卷 864-869页

作者： Fan, Xianqiang Fleming, Tristan G. Clark, Samuel J. Fezzaa, Kamel Getley, Anna C M Marussi, Sebastian Wang, Hongze Leung, Chu Lun Alex Kao, Andrew Lee, Peter D. Mechanical Engineering University College London London United Kingdom Research Complex at Harwell Harwell Campus Didcot United Kingdom Department of Physics Engineering Physics & Astronomy Queen's University Kingston ON Canada X-ray Science Division Argonne National Laboratory Lemont IL United States State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University Shanghai China School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai China Computational Science and Engineering Group Centre for Advanced Simulation and Modelling University of Greenwich London United Kingdom

Keyhole instability during laser welding and laser powder bed fusion (LPBF) can cause keyhole collapse and pore formation. Using high-speed x-ray imaging, we demonstrate that the flow vortex-induced protrusion on the rear keyhole wall is crucial in initiating keyhole instability. Applying a transverse magnetic field suppresses the keyhole instability by driving a secondary thermoelectric magnetohydrodynamics (TEMHD) flow that alters the net flow vortex. This minimizes protrusions and large-amplitude keyhole oscillations. The suppression effectiveness depends on the laser scanning direction relative to the magnetic field orientation because this controls the Seebeck effect-induced Lorentz force's direction. We show that at LPBF length scales, electromagnetic damping is weak, and for alloys with a large Seebeck coefficient, TEMHD becomes the dominant mechanism controlling flow behind the keyhole.

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Key Technologies and Future Development Trends of Intelligent Earth-Rock Dam Construction

Journal of Intelligent Construction

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Journal of Intelligent Construction 2025年第3期1卷 1-18页

作者： Yujie Wang Yufei Zhao Biao Liu Naixin Wang Chenfeng Li State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower Research Beijing China Key Laboratory of Construction and Safety of Hydraulic Engineering of Ministry of Water Resources Beijing China Zienkiewicz Institute for Modelling Data and AI Swansea University Swansea UK

The rapid advancement of information technologies, such as cloud computing, internet of things (loT), and big data, has significantly enhanced the intelligence level in dam construction. Intelligent monitoring systems for dam filling have garnered considerable attention from water conservancy and hydropower engineering units, owing to their capability for refined management and quality control of layered and compartmentalized construction processes. The construction of earth-rock dams has undergone a transformation, shifting from manual management of dam compaction equipment, layer management, and quality control to a comprehensive intelligent approach. This new approach encompasses fine-grained control of unit engineering, dam material identification, unmanned driving technology, real-time assessment and monitoring of compaction quality, and early warning forecasting. This article presents a systematic overview of key technologies employed in the intelligent construction process of earth-rock dams. These technologies include the fine decomposition of building information modeling (BIM) models on web platforms, rapid identification of dam material particle size, the application of autonomous driving technology for intelligent dam filling, and real-time monitoring and evaluation of dam compaction characteristics. Additionally, the paper discusses the latest research results in the field, building upon existing technology progress, and concludes by exploring the future development trends of intelligent dam construction. The construction of intelligent earth-rock dams serve as a crucial reference and valuable lessons for the development and construction of high earth-rock dam projects.

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Advanced Thermal Energy Solutions: Phase Change Material Evaluation for Building

Advanced Thermal Energy Solutions: Phase Change Material Eva...

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Innovative Research in Applied Science, engineering and Technology (IRASET),Conference on

作者： Sabrina Jellaj Salma Ouhaibi Laidi Zahiri Naoual Belouaggadia Laboratory of Modelling and Simulation of Intelligent Industrial Systems (M2S2I) ENSET Hassan II University of Casablanca Morocco Laboratory Engineering Systems and Applications ENSA Sidi Mohamed ben Abdellah University Fez Morocco

ISBN: (数字)9798331532970

ISBN: (纸本)9798331532987

This research evaluates the effectiveness of two types of phase-change materials (PCMs): one paraffin-based (PCM1) and the other bio-based (PCM2), integrated within a multi-layer wall system. The thermal management and energy-saving capabilities of these MCPs were examined under diverse climatic conditions by numerical simulations performed with ANSYS 2021 R1. The results indicate that PCM1 is more efficient at storing latent heat, allowing it to maintain thermal conditions for extended durations, which makes it particularly suitable for regions experiencing constant temperature fluctuations. On the other hand, PCM2 reacts quickly to sudden temperature shifts because of its reduced melting point and enhanced thermal conductivity, optimizing performance across various environmental settings. Both PCMs markedly diminished indoor temperature fluctuations, achieving energy savings of roughly 18% for cooling requirements. Furthermore, PCM2's bio-based composition provides significant environmental benefits, consistent with sustainable construction methodologies. The results highlight the synergistic advantages of PCM1 and PCM2, stressing the necessity to customize PCM selection according to particular climatic and operational demands to improve building energy efficiency and thermal comfort. This research advocates for the incorporation of phase change materials into wall systems as an effective strategy for sustainable architectural solutions.

关键词： Phase change materials Hands Fluctuations Buildings Energy conservation Conductivity Thermal management Energy efficiency Thermal stresses Thermal energy

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Machine learning-based multi-objective optimization of a carbon dioxide direct-expansion geothermal heat pump comprising an internal heat exchanger and expander

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Applied Thermal engineering 2025年 274卷

作者： Askari, Ighball Baniasad Ghazizade-Ahsaee, Hossein Shahsavar, Amin Keshtegar, Behrooz Department of Mechanical Engineering Faculty of Engineering University of Zabol Zabol Iran Tehran Iran Department of Mechanical Engineering Kermanshah University of Technology Kermanshah Iran Department of Civil Engineering Faculty of Engineering University of Zabol Zabol Iran Key Laboratory of Modelling and Simulation-based Reliability and Optimization University of Zabol ZabolP.B. *** Iran

The present study deals with the intelligent forecasting of the coefficient performance (COP), exergy efficiency (ηex), and capital cost of a transcritical CO2 direct expansion heat pump using a heuristic machine learning approach. For the first, the parametric analysis was conducted on six important variables to examine the influence of each on ηex, COP, and the length of ground heat exchanger (LGHX). The outputs were used to develop a predictive model using the Radial Basis Functions (RBFs) artificial numeral network machine learning approach. The results demonstrated that LGHX is significantly diminished by 70.21 % as the temperature difference between the soil and evaporator increases from 5 °C to 13 °C. Also, LGHX is reduced by 21.69 % as Tin,w is intensified. Moreover, an 80 % increase in Tin,w leads to 50.12 % and 45.55 % improvement in ηex and COP, respectively. In addition, the RBF machine learning approach exhibited a high performance and accuracy in forecasting ηex, COP, LGHX, heating energy (QGC), capital cost, and the compressor and expander work with R2 ≥ 0.9943 and a low RMSE. Moreover, the results of multi-objective genetic algorithm optimization showed that the heat pump with LGC, LGHX, and compressor speed of 10.06 m, 172.5 m, and 2158 RPM brings the optimum ηex and COP of 34.22 % and 3.05, respectively, delivering heating energy of 10.3 kW with a total capital cost of 22,303 $. © 2025 Elsevier Ltd

关键词： Geothermal heat pumps

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Superacid assisted high-throughput production and solution-processing of pristine two-dimensional materials

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Materials Today 2025年 86卷 228-237页

作者： Deng, Qixuan Ma, Jiabin Liu, Minsu Zhou, Yicong Ding, Siyuan Zhan, Ke Zhu, Yuan Xiong, Zhiyuan Su, Yang Yu, Kuang Cheng, Hui-Ming Qiu, Ling Shenzhen Geim Graphene Center Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen518055 China Laboratory for Simulation and Modelling of Particulate Systems Department of Chemical Engineering Department of Materials Science and Engineering Monash University VIC3800 Australia Monash Suzhou Research Institute Monash University Suzhou Suzhou SIP215000 China School of Microelectronics Southern University of Science and Technology Shenzhen518055 China School of Light Industry and Engineering South China University of Technology Guangzhou510640 China Shenzhen Key Lab of Energy Materials for Carbon Neutrality Shenzhen Institute of Advanced Technology Chinese Academy of Sciences 1068 Xueyuan Road Shenzhen518055 China Faculty of Materials Science and Energy Engineering Shenzhen University of Advanced Technology 291 Louming Road Shenzhen518107 China

Pristine two-dimensional (2D) materials have a multitude of interesting properties, promising a broad spectrum of applications. However, their poor affinity for common solvents and tendency to aggregate impede their effective exfoliation and solution-processing into various structures, such as fibers and membranes, thus limiting their practical use. We report a high-efficiency method for producing pristine 2D nanosheets by direct high-speed shearing exfoliation in trifluoromethanesulfonic acid (TfOH). Typically, this method produces hexagonal boron nitride nanosheets (BNNSs) with an unprecedented throughput of 38.8 mg mL-1h−1. The effective exfoliation is attributed to the strong binding affinity, large dipole moment and steric repulsion of TfOH, which collectively introduce layer edge distortion in hexagonal boron nitride (hBN), facilitating its exfoliation. The mechanical exfoliation and reversible edge interaction introduce no additional functional groups to the exfoliated BNNSs. The resulting pristine BNNS exhibit remarkable stability in TfOH solutions at ultrahigh concentrations of 200 mg mL−1 for over 28 days. The viscosity of the highly concentrated BNNS/TfOH dispersion can be adjusted, enabling techniques to produce BNNS-based spheres, fibers, and membranes with high thermal conductivity and mechanical strength, suitable for advanced thermal management applications. Room temperature processed BNNS-based spheres exhibit superior thermal conductivity compared to high temperature processed commercially available hBN or Al2O3 spheres. Moreover, TfOH can also be used to assist the efficient production and solution-processing of other 2D nanosheets, including graphene, molybdenum disulfide and tungsten disulfide, enabling the fabrication of high-quality bulk assemblies. © 2025 Elsevier Ltd

关键词： Molybdenum disulfide

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A mathematical reaction–diffusion model describing the connection between smokers and tuberculosis patients

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Partial Differential Equations in Applied Mathematics 2025年 14卷

作者： Khaloufi, Issam Karim, Marouane Rhila, Soukaina Ben Rachik, Mostafa Laboratory of Analysis Modelling and Simulation Department of Mathematics and Computer Science Faculty of Sciences Ben M'Sik Hassan II University Casablanca Casablanca Sidi Othman BP 7955 Morocco Multidisciplinary Research and Innovation Laboratory (LPRI) Moroccan School of Engineering Sciences (EMSI) Casablanca Morocco

In this paper, we introduce a new mathematical model that incorporates both temporal and spatial factors to characterize the relationship between the smoking population and tuberculosis (TB) cases. We validate the model's relevance by demonstrating the existence and positivity of the solutions. Furthermore, we propose three control measures aimed at reducing TB and smoking transmission, focusing on limiting contact between smokers and non-smokers, improving awareness of the health risks associated with smoking, and ensuring timely and effective medical treatment for TB patients. Mathematical analysis is employed to demonstrate the existence and characteristics of optimal controls for these strategies. The theoretical results are verified using numerical simulations, which also confirm the effectiveness of the suggested control strategies. Our results underline the importance of considering spatiotemporal dynamics in disease modeling and control, and they offer crucial insights for public health initiatives aimed at reducing the prevalence of smoking and TB. © 2025 The Authors

关键词： Mathematical model Optimal control Smoking Spatiotemporal dynamics Tuberculosis

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CFD-DEM modelling of mixing and segregation of binary mixtures of ellipsoidal particles in liquid fluidizations

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Journal of Hydrodynamics 2019年第6期31卷 1190-1203页

作者： Esmaeil Abbaszadeh Molaei Aibing Yu Zongyan Zhou Laboratory for Simulation and Modelling of Particulate Systems Department of Chemical EngineeringMonash UniversityClaytonVic 3800Australia

Solid-liquid fluidized beds of binary mixtures are widely used in many *** segregation may occur as particles can differ in size,density,or *** studies have been conducted in the past to understand the effects of particlesize and density on the mixing and segregation,but the effect of particle shape has not been well ***,in the present work,CFD-DEM approach is employed to perform a numerical analysis of the effect of particle shape on the particle mixing and segregation phenomenon in liquid fluidization *** particle shapes from oblate to prolate are produced by varying aspect ratio of ellipsoids from 0.25 to 3,and eight binary mixtures of spheres and ellipsoids are *** results show that when oblate or prolate particles are added to spheres,the segregation takes *** segregation degree increases with particle aspect ratio diverging from 1.0 and also liquid superficial *** relationship of mixing index with aspect ratio under different liquid velocities is established,and a detailed explanation is *** is revealed that increasing the projected area and hence the drag force results in the separation of ellipsoidal particles from spheres.

关键词： Mixing segregation binary mixture ellipsoids liquid fluidization CFD-DEM

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Advances in reduction of NO_x and N_2O emission formation in an oxy-fired fluidized bed boiler

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Chinese Journal of Chemical engineering 2019年第2期27卷 426-443页

作者： Khalid El Sheikh Mohammad Jakir Hossain Khan Mahar Diana Hamid Siddhartha Shrestha Brahim Si Ali G.A.Ryabov Lya A.Dolgushin Mohd Azlan Hussain Tatiana V.Bukharkina Elena A.Gorelova Dmitry Mendeleev University of Chemical Technology of Russia Department of Chemical Engineering Faculty of Engineering University of Malaya Laboratory for Simulation and Modelling of Particulate Systems Department of Chemical Engineering Monash University All-Russian Thermal Engineering Institute VTI

Fossil fuel combustion is one of the major means to meet the mounting global energy demand. However, the increasing NO_x and N_2 O emissions arising from fossil fuel combustion process have hazardous effects. Thus, mitigating these gases is vital to attain a sustainable environment. Interestingly, oxy-fuel combustion in fluidized bed for carbon capture and minimized NO_x emissions is strongly sustainable compare to the other approaches. It was assessed that NO_x formation and fuel-N conversion have significant limitation under oxy-fluidized bed compared to air mode and the mechanism of NO_x formation is still deficient and requires further development. In addition, this review paper discussed the potential of primary measure as low emission process with others supplementary techniques for feasible NO_x reduction. The influences of combustion mode, operating parameters, and reduction techniques such as flue gas recirculation, oxygen staging, biomass co-firing, catalyst, influence of fluidized bed design and structure, decoupling combustion and their merges are respectively evaluated. Findings show that significant minimization of NO_x emission can be achieved through combination of primary and secondary reduction techniques.

关键词： Oxy-fuel combustion Fluidized bed technology Biomass blend Primary/secondary measures NOx emission

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Shear test based identification of the hardening behaviour of stainless sheets after the onset of necking using cubic spline interpolation

Shear test based identification of the hardening behaviour o...

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10th International Conference on Computational Structures Technology, CST 2010

作者： Vrh, M. Halilovic, M. Štok, B. Laboratory for Numerical Modelling and Simulation Faculty of Mechanical Engineering University of Ljubljana Slovenia

ISBN: (纸本)9781905088386

The paper focuses on a reliable identification of the hardening curve of sheet metal after onset of necking with the developed shear test. The main comparative advantage of the test is its simple procedure for which no further development of experimental equipment regarding standard tensile test is needed. The only modification of the standard tensile test refers to a purposely designed symmetric shear specimen which enables achievement of large shear strains during stable loading condition. In addition the paper presents the hardening curve approximation based on the cubic spline techniques. Such approach is very convenient for use because splines are smooth and are able to approximate accurately local curvatures without global estimation being influenced. From a comparison between the analytically extrapolated and identified hardening curves it is shown that using analytical extrapolation at large strains is seriously flawed as a result of the considerable differences between the curves. © Civil-Comp Press, 2010.

关键词： Hardening

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Thermo-mechanical modelling of continuous casting primary zones

Thermo-mechanical modelling of continuous casting primary zo...

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13th International Conference on Civil, Structural and Environmental engineering Computing, CC 2011

作者： Halilovič, M. Mole, N. Štok, B. Laboratory for Numerical Modelling and Simulation Faculty of Mechanical Engineering University of Ljubljana Slovenia

ISBN: (纸本)9781905088454

The aim of this work is to present a modelling approach to thermo-mechanical analysis of the solidifying shell in the primary zone, as met in thin slab continuous casting process with the mould of non-constant cross-section subjected to oscillation. The thermo-mechanical problem considered in the Eulerian reference frame is treated as uncoupled, with the temperature and stress-strain fields being steady-state and cyclic steady-state, respectively. For validation of the developed numerical model the respective process simulation results are compared with the available measurements. Considering that great capability of the model in achieving a better physical insight into the complex thermo-mechanical behaviour in continuous casting is confirmed, the model can be used not only for direct analysis purposes, but above all for an advanced technology design involving a process parameters prescription and the mould's internal geometry determination, as well as corresponding optimization tasks. © Civil-Comp Press, 2011.

关键词： Molds

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