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Parametric Analysis and Designing Maps for Powder Spreading in Metal Additive Manufacturing

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Computer Modeling in engineering & Sciences 2025年第2期142卷 2067-2090页

作者： Yuxuan Wu Sirish Namilae Department of Aerospace engineering Embry-Riddle Aeronautical UniversityDaytona BeachFL 32114USA

Powder bed fusion(PBF)in metallic additive manufacturing offers the ability to produce intricate geometries,high-strength components,and reliable ***,powder processing before energy-based binding significantly impacts the final product’s *** maps guide efficient process design to minimize defects,but creating them through experimentation alone is challenging due to the wide range of parameters,necessitating a comprehensive computational parametric *** this study,we used the discrete element method to parametrically analyze the powder processing design space in PBF of stainless steel 316L *** lattice parameter sweeps are often used for parametric analysis,but are computationally *** find that non-uniform parameter sweep based on the low discrepancy sequence(LDS)algorithm is ten times more efficient at exploring the design space while accurately capturing the relationship between powder flow dynamics and bed packing *** introduce a multi-layer perceptron(MLP)model to interpolate parametric causalities within the LDS parameter *** over 99%accuracy,it effectively captures these causalities while requiring fewer ***,we generate processing design maps for machine setups and powder selections for efficient process *** find that recoating speed has the highest impact on powder processing quality,followed by recoating layer thickness,particle size,and inter-particle friction.

关键词： Powder bed fusion additive manufacturing discrete element method parameter sweep process design

An Online Exploratory Maximum Likelihood Estimation Approach to Adaptive Kalman Filtering

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IEEE/CAA Journal of Automatica Sinica 2025年第1期12卷 228-254页

作者： Jiajun Cheng Haonan Chen Zhirui Xue Yulong Huang Yonggang Zhang the college of Intelligent Systems Science and engineering Harbin Engineering University the engineering Research Center of Navigation Instruments Ministry of Education the college of Intelligent Systems Science and engineering the college of Future Technology Harbin Engineering University IEEE

Over the past few decades, numerous adaptive Kalman filters(AKFs) have been proposed. However, achieving online estimation with both high estimation accuracy and fast convergence speed is challenging, especially when both the process noise and measurement noise covariance matrices are relatively inaccurate. Maximum likelihood estimation(MLE) possesses the potential to achieve this goal, since its theoretical accuracy is guaranteed by asymptotic optimality and the convergence speed is fast due to weak dependence on accurate state ***, the maximum likelihood cost function is so intricate that the existing MLE methods can only simply ignore all historical measurement information to achieve online estimation,which cannot adequately realize the potential of MLE. In order to design online MLE-based AKFs with high estimation accuracy and fast convergence speed, an online exploratory MLE approach is proposed, based on which a mini-batch coordinate descent noise covariance matrix estimation framework is developed. In this framework, the maximum likelihood cost function is simplified for online estimation with fewer and simpler terms which are selected in a mini-batch and calculated with a backtracking method. This maximum likelihood cost function is sidestepped and solved by exploring possible estimated noise covariance matrices adaptively while the historical measurement information is adequately utilized. Furthermore, four specific algorithms are derived under this framework to meet different practical requirements in terms of convergence speed, estimation accuracy,and calculation load. Abundant simulations and experiments are carried out to verify the validity and superiority of the proposed algorithms as compared with existing state-of-the-art AKFs.

关键词： Adaptive Kalman filtering coordinate descent maximum likelihood estimation mini-batch optimization unknown noise covariance matrix

Quasinormal modes of a black hole surrounded by a fluid of strings in Rastall gravity

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Chinese Physics C 2025年第02期 197-205页

作者：张明岳瑞宏邹德成 Faculty of Science Xi'an Aeronautical University National Joint engineering Research Center for Special Pump System Technology Xi'an Aeronautical University Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou University college of Physics and Communication Electronics Jiangxi Normal University

In this paper, we explore the quasinormal modes(QNMs) of a black hole surrounded by a fluid of strings within the framework of Rastall gravity. We analyze the behavior of scalar, electromagnetic, and gravitational perturbations, focusing on the influences of black hole charge Q and angular momentum l on the quasinormal *** numerical results reveal a significant dependence on parameter ε. These trends are consistent across different types of perturbations, emphasizing the relationship between black hole parameters and QNM behavior.

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Characterization of combined blast-and fragments-induced synergetic damage in polyurea coated liquid-filled container

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Defence Technology(防务技术) 2025年第1期43卷 201-224页

作者： Chen Tao Chong Ji Xin Wang Juan Gu Yuting Wang Changxiao Zhao college of Field engineering Army Engineering University of PLANanjing210007China college of Defense engineering Army Engineering University of PLANanjing211101China

Liquid-filled containers(LFC)are widely used to store and transport petroleum,chemical reagents,and other *** an important target of military strikes and terrorist bombings,LFC are vulnerable to blast waves and *** explore the protective effect of polyurea elastomer on LFC,the damage characteristics of polyurea coated liquid-filled container(PLFC)under the combined loading of blast shock wave and fragments were studied *** microstructure of the polyurea layer was observed by scanning electron microscopy,and the fracture and self-healing phenomena were *** simulation approach was used to explain the combined blast-and fragments-induced on the PLFC in ***,the effects of shock wave and fragment alone and in combination on the damage of PLFC were comprehensively *** showed that the polyurea reduces the perforation rate of the fragment to the LFC,and the self-healing phenomenon could also reduce the liquid loss rate inside the *** polyurea reduces the degree of depression in the center of the LFC,resulting in a decrease in the distance between adjacent fragments penetrating the LFC,and an increase in the probability of transfixion and fracture between *** the close-in blast,the detonation shock wave reached the LFC before the *** does not all have an enhanced effect on the protection of *** presence of internal water enhances the anti-blast performance of the container,and the hydrodynamic ram(HRAM)formed by the fragment impacting the water aggravated the plastic deformation of the *** combined action has an enhancement effect on the deformation of the *** depth of the container depression was 27%higher than that of the blast shock wave alone;thus,it cannot be simply summarized as linear superposition.

关键词： Polyurea Prefabricated fragment Liquid-filled container Hydrodynamic ram Cumulative effect

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Dynamic Event-Triggered Active Disturbance Rejection Formation Control for Constrained Underactuated AUVs

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IEEE/CAA Journal of Automatica Sinica 2025年第2期12卷 460-462页

作者： Zhiguang Feng Sibo Yao IEEE the college of Intelligent Systems Science and engineering Harbin Engineering University

Dear Editor,This letter addresses the formation control problem for constrained underactuated autonomous underwater vehicles (AUVs). The feasibility condition of the virtual control law is eliminated by introducing a nonlinear state dependence function (NSDF) that transforms the state of each AUV in the formation.

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Comparative Evaluation and Performance Analysis of Heat Exchangers Featured with Peened Surface

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Journal of Thermal Science 2025年第1期34卷 50-61页

作者： DINESHBABU Chinnadurai SHIVA SANKARAN Nallasamy VENKATESH RAJAKrishnan VENKATESH Rathinavelu Department of Mechanical engineering Kongunadu College of Engineering and TechnologyTamil Nadu-621215India Department of Mechanical engineering Selvam College of TechnologyNamakkalTamil Nadu-637003India Department of Mechanical engineering Sona College of TechnologySalemTamil Nadu-636005India Department of Mechanical engineering Saveetha School of EngineeringSaveetha Institute of Medical and Technical Sciences(SIMATS)Saveetha UniversityChennai 602105TamilnaduIndia

Heat exchangers have the potential for various engineering applications,and their performance is enriched by surface *** proposed system enriches the heat exchanger's performance by adapting a peened stainless steel(SS)surface blasted with copper,grinding,sand,and *** influences peened SS surface modified with a copper blast,grinding,sandblast,and iron blast on the surface morphology of shell and tube heat exchanger surface(STHE)is analyzed via tungsten heated cathode electron gun featured scanning electron microscope and observed coarse grain *** SS surface featured STHE performance is experimentally evaluated by different flow rates(30,60,90,and 120 L/min)underwater fluid medium functioned by the temperature ranges of 25-75℃ and its results are compared with computational fluid dynamic(CFD)/heat transfer research(HTRI)analyzed *** 60 L/min flow rate was spotted as an optimum value for both shell and tube side *** STHE is operated with a 60 L/min flow rate under the different peened surfaces and evaluated its Stanton number,Nusselt number,logarithmic mean temperature difference(LMTD),overall heat transfer coefficient,number of transfer units(NTU),effectiveness,and exergy *** iron blasted SS peened surface was observed to have better SHTE performance like Stanton number(0.0012),Nusselt number(2180),reduced LMTD of 31℃,improved overall heat transfer co-efficient of 2400 W/(m^(2)·K),better NTU of 0.5532,good effectiveness value of 0.45162,and hiked exergy efficiency of 10% respectively.

关键词： penned surface performance analysis stainless steel shell and tube heat exchanger

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A six-variable quasi-3D isogeometric approach for free vibration of functionally graded graphene origami-enabled auxetic metamaterial plates submerged in a fluid medium

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 157-176页

作者： Wei CHEN Zhihong TANG Yufen LIAO Linxin PENG college of Civil engineering University of South China college of Civil engineering and Architecture Guangxi University Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education Guangxi University

This paper presents, for the first time, an effective numerical approach based on the isogeometric analysis(IGA) and the six-variable quasi-three dimensional(3D)higher-order shear deformation theory(HSDT) to study the free vibration characteristics of functionally-graded(FG) graphene origami(GOri)-enabled auxetic metamaterial(GOEAM) plates submerged in a fluid medium. The plate theory incorporates the thickness stretching and the effects of transverse shear deformation without using any shear correction factors. The velocity potential function and Bernoulli's equation are used to derive the hydrodynamic pressure acting on the plate surface. Both horizontally and vertically immersed plate configurations are considered here in the form of inertia *** plates are composed of multilayer GOEAMs, with the GOri content varying through the plate's thickness in a layer-wise manner. This design results in graded auxetic *** material properties are evaluated by mixing rules and a genetic programming(GP)-assisted micromechanical model. The governing equations of motion for the FG-GOEAM plates immersed in a fluid medium are derived by Hamilton's principle. After validating the convergence and accuracy of the present model, a comprehensive parametric study is carried out to examine the effects of the GOri content, GOri distribution pattern, GOri folding degree, fluid level, immersed depth, and geometric parameter on the natural frequencies of the FG-GOEAM plates. The results show that the natural frequencies for the four GOri distribution patterns increase with the increase in the layer number when the lay number is fewer than 10, and then stabilize after the layer number reaches ***, in general, the natural frequency of the FG-GOEAM plate in a vacuum or fluid increases when the GOri content increases, while decreases when the GOri folding degree increases. Some additional findings related to the numerical results are presented in the conclusions. It is belie

关键词： free vibration functionally-graded (FG) graphene origami (GOri)-enabled auxetic metamaterial (GOEAM) plate hydrodynamic pressure isogeometric analysis (IGA) O321 quasi-three dimensional (3D) higher-order shear deformation theory (HSDT)

Theoretical Calculations of HfSe_(3) Band Characteristics and Its Applications in Pulse Fiber Lasers

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Chinese Physics Letters 2025年第2期42卷 41-47页

作者： Weiwei Feng Ligang Chen Institute of Airport Shandong University of AeronauticsBinzhou 256603China Institute of aeronautical engineering Shandong University of AeronauticsBinzhou 256603China Shandong engineering Research Center of aeronautical Materials and Devices Binzhou 256603China

Transition metal trichalcogenides(TMTs)are known for their two-dimensional(2D)characteristics and the presence of quasi one-dimensional *** materials are less vulnerable to edge defects,which makes them suitable for optical and electronic devices with low-dimensional *** study demonstrates the application of HfSe_(3) nanomaterial as an emerging ultrafast photonic device capable of producing mode-locked and Q-switched pulses in fiber *** nonlinear optical absorption properties of a HfSe_(3)-based saturable absorber(SA)were analyzed,revealing a modulation depth of 7% and nonsaturable loss of 35%,*** addition,first principles-based theoretical calculations were performed to explore the optoelectronic properties of bulk HfSe_(3).The integration of the HfSe_(3)-based SA into an Er-doped fiber laser cavity enabled both Q-switched and mode-locked pulse *** the mode-locked operation,the pulse duration was 560 fs,accompanied by a signal-to-noise ratio(SNR)of 71.43 *** the Q-switched regime,the narrowest pulse width recorded was 757.1 ns with an SNR of 75.45 *** study indicates that nanodevices based on 2D TMTs hold promise for efficient ultrafast photonic applications and can be extensively employed in nonlinear optical technologies.

关键词： switched fiber absorber

Understanding excitonic behavior and electroluminescence light emitting diode application of carbon dots

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Chinese Chemical Letters 2025年第2期36卷 201-206页

作者： Yuan Liu Boyang Wang Yaxin Li Weidong Li Siyu Lu School of Chemistry and Chemical engineering Henan University of Technology college of Chemistry Zhengzhou University college of Material engineering Henan International Joint Laboratory of Rare Earth Composite MaterialsHenan University of Engineering

Carbon dots (CDs),due to their low cost,high stability,and high luminous efficiency,have emerged as an excellent material for the emissive layer in next-generation electroluminescent light-emitting diodes(ELEDs).However,improving the efficiency of fluorescent CDs-based ELEDs remains challenging,primarily because it is difficult to utilize triplet excitons in the electroluminescence ***,enhancing the exciton utilization efficiency of CDs during electroluminescence is *** on this,we exploited the characteristic large exciton binding energy commonly found in CDs to develop exciton-emitting *** CDs facilitate the radiative recombination of excitons during electroluminescence,thereby improving the electroluminescent *** rationally selecting precursors,we developed high quantum efficiency CDs and subsequently constructed CDs-based *** blue-light device exhibited an external quantum efficiency of over 4%.This study introduces a novel design concept for CDs,providing a new strategy for developing high-performance blue ELEDs based on CDs.

关键词： Carbon dots Controllable preparation Electroluminescence Exciton emission Light-emitting diodes