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Design-space adaptation method for multiobjective and multidisciplinary optimization

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Chinese Journal of Aeronautics 2024年第8期37卷 166-189页

作者： Jongho JUNG Kwanjung YEE Shinkyu JEONG Department of Aerospace Engineering Seoul National UniversitySeoul 08826Republic of Korea Department of mechanical Engineering Kyunghee UniversityYoungin 17104Republic of Korea

This paper developed a new method that adaptively adjusts a design space by considering the actual solution distribution of a problem to overcome the conventional design-space adaptation method that assumes the solutions distribution to be a normal distribution because the distributions of solutions are rarely normal distributions for real-world *** developed method was applied to nineteen multiobjective test functions that are widely used to evaluate the characteristics and performance of optimization *** results showed that this method adapted the design space to an appropriate design space where the solution existence probability was *** optimization performance achieved using the developed method was higher than that of the conventional ***,the developed method was applied to the conceptual design of an unmanned spacecraft to confirm its validity in real-world design and multidisciplinaryoptimization *** results showed that the Pareto solutions of the developed method were superior to those of conventional ***,the optimization efficiency with the developed method was improved by more than 1.4 times over that of the conventional *** this regard,the developed method has the potential to be applied to complicated real-world optimization problems to achieve better performance and efficiency.

关键词： Multiobjective optimization Multiobjective genetic algorithm Design-space adaptation Multidisciplinary optimization Hypersonic vehicle

Fast and Accurate Predictor-Corrector Methods Using Feedback-Accelerated Picard Iteration for Strongly Nonlinear Problems

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 1263-1294页

作者： Xuechuan Wang Wei He Haoyang Feng Satya N.Atluri School of Astronautics Northwestern Polytechnical UniversityXi’an710072China Department of mechanical Engineering Texas Tech UniversityLubbock79409USA

Although predictor-corrector methods have been extensively applied,they might not meet the requirements of practical applications and engineering tasks,particularly when high accuracy and efficiency are necessary.A novel class of correctors based on feedback-accelerated Picard iteration(FAPI)is proposed to further enhance computational *** optimal feedback terms that do not require inversion of matrices,significantly faster convergence speed and higher numerical accuracy are achieved by these correctors compared with their counterparts;however,the computational complexities are comparably *** advantages enable nonlinear engineering problems to be solved quickly and accurately,even with rough initial guesses from elementary *** proposed method offers flexibility,enabling the use of the generated correctors for either bulk processing of collocation nodes in a domain or successive corrections of a single node in a finite difference *** our method,the functional formulas of FAPI are discretized into numerical forms using the collocation *** collocated iteration formulas can directly solve nonlinear problems,but they may require significant computational resources because of the manipulation of *** address this,the collocated iteration formulas are further converted into finite difference forms,enabling the design of lightweight predictor-corrector algorithms for real-time *** generality of the proposed method is illustrated by deriving new correctors for three commonly employed finite-difference approaches:the modified Euler approach,the Adams-Bashforth-Moulton approach,and the implicit Runge-Kutta ***,the updated approaches are tested in solving strongly nonlinear problems,including the Matthieu equation,the Duffing equation,and the low-earth-orbit tracking *** numerical findings confirm the computational accuracy and efficiency of the derived predictor-correc

关键词： Predictor-corrector method feedback-accelerated Picard iteration nonlinear dynamical system real-time computation

Improved combustion stability of biogas at different CO_(2) concentrations using inhomogeneous partially premixed stratified flames

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Global Energy Interconnection 2024年第4期7卷 486-502页

作者： Mohy Saad Mansour Maged Kiriakos Lili Hao Mohamed Amr Serag-Eldin mechanical Power Engineering Department Cairo University1 Gamaa StreetCairo Governorate 12613Egypt mechanical Engineering Department The American University in CairoAUC AveCairo Governorate 11835Egypt College of Electrical Engineering and Control Science Nanjing Tech UniversityNanjing 211816P.R.China

Biogas is a renewable and clean energy source that plays an important role in the current environment of lowcarbon *** high-content CO_(2) in biogas can be separated,transformed,and utilized,it not only realizes high-value utilization of biogas but also promotes carbon reduction in the biogas *** improve the combustion stability of biogas,an inhomogeneous,partially premixed stratified(IPPS)combustion model was adopted in this *** thermal flame structure and stability were investigated for a wide range of mixture inhomogeneities,turbulence levels,CO_(2) concentrations,air-to-fuel velocity ratios,and combustion energies in a concentric flow slot burner(CFSB).A fine-wire thermocouple is used to resolve the thermal flame *** flame size was reduced by increasing the CO_(2) concentration and the flames became lighter *** flame temperature also decreased with increase in CO_(2) *** stability was reduced by increasing the CO_(2) ***,at a certain level of mixture inhomogeneity,the concentration of CO_(2) in the IPPS mode did not affect the ***,the IPPS mode of combustion should be suitable for the combustion and stabilization of *** should support the design of highly stabilized biogas turbulent flames independent of CO_(2) *** data show that the lower stability conditions are partially due to the change in fuel combustion energy,which is characterized by the Wobbe index(WI).In addition,at a certain level of mixture inhomogeneity,the effect of the WI on flame stability becomes dominant.

关键词： Biogas Renewable energy Effect of CO_(2) Combustion stability Burner design Renewable fuels Partial premixed

Semi-analytical Solutions for Wellbores with Graded Skin Zones in Poroelastic Media

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Acta Mechanica Solida Sinica 2024年第3期37卷 385-395页

作者： Zhiqiang Fan Zhihe Jin School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an710072China Department of mechanical Engineering University of MaineOronoME04469USA

In analyzing the complex interaction between the wellbore and the reservoir formation,the hydromechanical properties of the region proximal to the wellbore,referred to as the“wellbore skin zone”,play a pivotal role in determining flow dynamics and the resulting formation *** models of the wellbore skin zone generally assume a constant permeability throughout,resulting in a sharp permeability discontinuity at the skin-reservoir *** paper introduces a model for a wellbore with a continuously graded skin zone of finite thickness within a poroelastic *** solutions are derived using the Laplace transform method,addressing both positive and negative skin *** results are presented to illustrate the effects of graded permeability/skin zone thickness on pore pressures and stresses around a *** results highlight a distinct divergence in stress and pore pressure fields when comparing wellbores with negative skin zones to those with positive skin zones or no skin at all.

关键词： Poroelastic Graded permeability Analytical solution Wellbore Skin zone

Prediction of collapse process and tipping points for mutualistic and competitive networks with k-core method

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Chinese Physics B 2024年第5期33卷 173-180页

作者：段东立毕菲菲李思凡吴成星吕长春蔡志强 School of Information and Control Engineering Xi'an University of Architecture and TechnologyXi'an 710311China School of mechanical Engineering Northwestern Polytechnical UniversityXi'an 710072China

Ecosystems generally have the self-adapting ability to resist various external pressures or disturbances,which is always called ***,once the external disturbances exceed the tipping points of the system resilience,the consequences would be catastrophic,and eventually lead the ecosystem to complete *** capture the collapse process of ecosystems represented by plant-pollinator networks with the k-core nested structural method,and find that a sufficiently weak interaction strength or a sufficiently large competition weight can cause the structure of the ecosystem to collapse from its smallest k-core towards its largest *** we give the tipping points of structure and dynamic collapse of the entire system from the one-dimensional dynamic function of the *** work provides an intuitive and precise description of the dynamic process of ecosystem collapse under multiple interactions,and provides theoretical insights into further avoiding the occurrence of ecosystem collapse.

关键词： complex networks tipping points dimension reduction k-core

Particle Size Optimization of Thermochemical Salt Hydrates for High Energy Density Thermal Storage

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Energy & Environmental Materials 2024年第2期7卷 326-333页

作者： Andrew Martin Drew Lilley Raνi Prasher Sumanjeet Kaur Energy Technologies Area Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA Department of mechanical Engineering UC BerkeleyBerkeleyCA 94720USA

Thermal energy storage(TES)solutions offer opportunities to reduce energy consumption,greenhouse gas emissions,and ***,they can help reduce the peak load and address the intermittency of renewable energy sources by time shifting the load,which are critical toward zero energy *** materials(TCMs)as a class of TES undergo a solid-gas reversible chemical reaction with water vapor to store and release energy with high storage capacities(600 kWh m^(-3))and negligible self-discharge that makes them uniquely suited as compact,stand-alone units for daily or seasonal ***,TCMs suffer from instabilities at the material(salt particles)and reactor level(packed beds of salt),resulting in poor multi-cycle efficiency and high-levelized cost of *** this study,a model is developed to predict the pulverization limit or Rcrit of various salt hydrates during thermal *** is critical as it provides design rules to make mechanically stable TCM composites as well as enables the use of more energy-efficient manufacturing process(solid-state mixing)to make the *** model is experimentally validated on multiple TCM salt hydrates with different water content,and effect of Rcrit on hydration and dehydration kinetics is also investigated.

关键词： high energy density hydration kinetics long-term cycling thermal energy storage thermochemical materials

Generating synthetic as-built additive manufacturing surface topography using progressive growing generative adversarial networks

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Friction 2024年第6期12卷 1283-1298页

作者： Junhyeon SEO Prahalada RAO Bart RAEYMAEKERS Department of mechanical Engineering Virginia TechBlacksburgVA 24061USA Grado Department of Industrial and Systems Engineering Virginia TechBlacksburgVA 24061USA

Numerically generating synthetic surface topography that closely resembles the features and characteristics of experimental surface topography measurements reduces the need to perform these intricate and costly ***,existing algorithms to numerically generated surface topography are not well-suited to create the specific characteristics and geometric features of as-built surfaces that result from laser powder bed fusion(LPBF),such as partially melted metal particles,porosity,laser scan lines,and ***,we present a method to generate synthetic as-built LPBF surface topography maps using a progressively growing generative adversarial *** qualitatively and quantitatively demonstrate good agreement between synthetic and experimental as-built LPBF surface topography maps using areal and deterministic surface topography parameters,radially averaged power spectral density,and material ratio *** ability to accurately generate synthetic as-built LPBF surface topography maps reduces the experimental burden of performing a large number of surface topography ***,it facilitates combining experimental measurements with synthetic surface topography maps to create large data-sets that facilitate,*** as-built surface topography to LPBF process parameters,or implementing digital surface twins to monitor complex end-use LPBF parts,amongst other applications.

关键词： additive manufacturing surface topography synthetic surface topography generative adversarial networks

Fabrication and integration of photonic devices for phase-change memory and neuromorphic computing

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International Journal of Extreme Manufacturing 2024年第2期6卷 2-27页

作者： Wen Zhou Xueyang Shen Xiaolong Yang Jiangjing Wang Wei Zhang Center for Alloy Innovation and Design(CAID) State Key Laboratory for Mechanical Behavior of MaterialsXi’an Jiaotong UniversityXi’an 710049People’s Republic of China

In the past decade,there has been tremendous progress in integrating chalcogenide phase-change materials(PCMs)on the silicon photonic platform for non-volatile memory to neuromorphic in-memory computing *** particular,these non von Neumann computational elements and systems benefit from mass manufacturing of silicon photonic integrated circuits(PICs)on 8-inch wafers using a 130 nm complementary metal-oxide semiconductor *** manufacturing based on deep-ultraviolet lithography and electron-beam lithography enables rapid prototyping of PICs,which can be integrated with high-quality PCMs based on the wafer-scale sputtering technique as a back-end-of-line *** this article,we present an overview of recent advances in waveguide integrated PCM memory cells,functional devices,and neuromorphic systems,with an emphasis on fabrication and integration processes to attain state-of-the-art device *** a short overview of PCM based photonic devices,we discuss the materials properties of the functional layer as well as the progress on the light guiding layer,namely,the silicon and germanium waveguide ***,we discuss the cleanroom fabrication flow of waveguide devices integrated with thin films and nanowires,silicon waveguides and plasmonic microheaters for the electrothermal switching of PCMs and mixed-mode ***,the fabrication of photonic and photonic–electronic neuromorphic computing systems is *** systems consist of arrays of PCM memory elements for associative learning,matrix-vector multiplication,and pattern *** large-scale integration,the neuromorphic photonic computing paradigm holds the promise to outperform digital electronic accelerators by taking the advantages of ultra-high bandwidth,high speed,and energy-efficient operation in running machine learning algorithms.

关键词： nanofabrication silicon photonics phase-change materials non-volatile photonic memory neuromorphic photonic computing

Enhanced Flexoelectricity in Barium Titanate-Cellulose Composite Thin Films

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Acta Mechanica Solida Sinica 2024年第4期37卷 521-527页

作者： Wensi Xing Hongyu Cao Xin Zhang Xu Liang Jianwei Song Shengping Shen Chemomechanics and Intelligent Media Laboratory State Key Laboratory for Strength and Vibration of Mechanical StructuresSchool of Aerospace EngineeringXi’an Jiaotong UniversityXi’an710049China

Biopolymers,the potential flexoelectric materials,are environment-friendly,degradable,lightweight,cost-effective,and possess remarkable processing properties catering to the requirements of advanced ***,the flexoelectric coefficient of biopolymers is normally much weaker than that of ceramic materials,limiting their potential applications for designing high-performance green electromechanical coupling *** improve the flexoelectric response in biopolymers,we composited barium titanate(BTO)with 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized cellulose nanofibrils(TOCNF)to enhance the flexoelectric response of *** to the high permittivity and flexoelectric effect of BTO,the relative dielectric constant and flexoelectric coefficient of 33.3 wt%BTO-TOCNF films reached 30.94@1 kHz and 50.05±1.88 nC/m@1 Hz,which were almost 172 times and 27 times higher than those of TOCNF,*** composite thin film contains high dielectric constant and flexoelectric coefficient,as well as excellent *** study provided a straightforward and efficient method for improving the flexoelectric effect of biopolymers,and demonstrated its great potential applications in flexoelectric-based devices.

关键词： Flexoelectricity Cellulose BaTiO_(3) Composite Thin films