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In Situ Mineralization of Biomass-Derived Hydrogels Boosts Capacitive Electrochemical Energy Storage in Free-Standing 3D Carbon Aerogels

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Energy & Environmental Materials 2024年第2期7卷 363-375页

作者： Anjali Achazhiyath Edathil Babak Rezaei Kristoffer Almdal Stephan Sylνest Keller National Centre for Nano Fabrication and Characterization DTU Nanolab Technical University of Denmark DTU Chemistry Technical University of Denmark

Here,a novel fabrication method for making free-standing 3D hierarchical porous carbon aerogels from molecularly engineered biomass-derived hydrogels is *** situ formed flower-like CaCO3molecularly embedded within the hydrogel network regulated the pore structure during in situ mineralization assisted one-step activation graphitization（iMAG）,while the intrinsic structural integrity of the carbon aerogels was *** homogenously distributed minerals simultaneously acted as a hard template,activating agent,and graphitization *** decomposition of the homogenously distributed CaCO3during iWAG followed by the etching of residual CaO through a mild acid washing endowed a robust carbon aerogel with high porosity and excellent electrochemical *** 0.5 mA cm-2,the gravimetric capacitance increased from 0.01 F g-1without mineralization to 322 F g-1with iMAG,which exceeds values reported for any other free-standing or powder-based biomass-derived carbon *** outstanding cycling stability of ～104%after 1000 cycles in 1 M HCIO4was *** assembled symmetric supercapacitor device delivered a high specific capacitance of 376 F g-1and a high energy density of 26 W h kg-1at a power density of 4000 W kg-1,with excellent cycling performance（98.5% retention after 2000 cycles）.In combination with the proposed 3D printed mold-assisted solution casting（3DMASC）,iWAG allows for the generation of free-standing carbon aerogel architectures with arbitrary ***,the novel method introduces flexibility in constructing free-standing carbon aerogels from any ionically cross-linkable biopolymer while maintaining the ability to tailor the design,dimensions,and pore size distribution for specific energy storage applications.

关键词： biomass carbon aerogel sustainable energy materials free-standing supercapacitors

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Features of rare earth elements geochemistry in coals of Central Kazakhstan

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Acta Geochimica 2024年第05期43卷 876-888页

作者： Aiman Nygmetovna Kopobayeva Altynay Amangeldikyzy Gulim Galymzhanovna Blyalova Nazym Srajadinkyzy Askarova Abylkas Saginov Karaganda technical university

This research presents the results of a comprehensive study of mineralogical and geochemical features of REE distribution in coals of Central Kazakhstan deposits—Karaganda coal basin and Shubarkol deposit, which have large hard coal reserves and are industrially important for the coal industry of Kazakhstan; the research is based on 205 samples of clayey interlayers and coal seams. It shows basic patterns of distribution and features of concentration for impurity elements, gives an estimate of the impurity elements concentration, including REE, defi nes conditions and factors of their accumulation, and studies features of their forms in coal and coal-bearing rocks, which allows estimating the mechanisms of their migration and conditions of accumulation. According to the results of geochemical indicators, the article establishes the factors of REE dislocation, reveals the composition of margin rocks that have infl uenced REE concentration in coal seams, and the presented latest data on mineralogy allowed to establish the ways of their transportation to the paleobasin during the synand epigenetic periods of formation of the coal deposits of Central Kazakhstan being researched. It was found that the coals are insignifi cantly enriched with heavy lanthanides from Ho to Lu. The distribution curves of UCC normalized REE values in the coals are similar and coincide, but they are less than the average value for world coal, and amount to only one-third of the UCC. It was found that the highest concentrations of all REE are characteristic of clayey interlayers and oxidized coals. The La/Yb ratio in this case increases upwards along the section, indicating mainly clastogenic mechanism of REE delivery to the coals. In coal and clay samples, the predominant mineral form of REE is light lanthanide phosphates. Identifi ed particles of REE from minerals and their composition peculiarities suppose autigene nature of their formation. The formation of the bulk of autigene minerals occ

关键词： Accumulation conditions Coal Concentration factors Impurity elements REE

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Gust response of an elasto-flexible morphing wing using fluid–structure interaction simulations

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Chinese Journal of Aeronautics 2024年第2期37卷 45-57页

作者： Jonathan PFLÜGER Christian BREITSAMTER Department of Mechanical Engineering Technical University of MunichGarching 85748Germany

Small and micro unmanned aircraft are the focus of scientific interest due to their wide range of *** often operate in a highly unstable flight environment where the application of new morphing wing technologies offers the opportunity to improve flight *** investigated concept comprises port and starboard adjustable wings,and an adaptive elastoflexible membrane serves as the lifting *** focus is on the benefits of the deforming membrane during the impact of a one-minus-cosine type *** a low Reynolds number of Re=264000,the morphing wing model is investigated numerically by unsteady fluid-structure interaction ***,the numerical results are validated by experimental data from force and moment,flow field,and deformation ***,with the rigid wing as the baseline,the flexible case is investigated,focusing on the advantages of the elastic *** all configurations studied,the maximum amplitude of the lift coefficient under gust load shows good agreement between the experimental and numerical *** the decay of the gust,they differ more the higher the aspect ratio of the *** considering the flow field,the main differences are due to the separation behavior on the upper side of the *** flow reattaches earlier in the experiments than in the simulations,which explains the higher lift values observed in the *** at one intermediate configuration does the lift amplitude of the rigid configuration exceeds that of the flexible by about 12%,with the elastic membrane resulting in a smaller and more uniform peak load,which is also evident in the wing loading and hence in the root bending moment.

关键词： Membrane wing Morphing wing Flexible wing surface Computational fluid dynam-ics Fluid-structure interaction Unsteady inflow condition Gust response

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A robust optimization method for label noisy datasets based on adaptive threshold: Adaptive-k

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Frontiers of Computer Science 2024年第4期18卷 49-60页

作者： Enes DEDEOGLU Himmet Toprak KESGIN Mehmet Fatih AMASYALI Department of Computer Engineering Yildiz Technical UniversityIstanbul 34220Turkey

The use of all samples in the optimization process does not produce robust results in datasets with label *** the gradients calculated according to the losses of the noisy samples cause the optimization process to go in the wrong *** this paper,we recommend using samples with loss less than a threshold determined during the optimization,instead of using all samples in the *** proposed method,Adaptive-k,aims to exclude label noise samples from the optimization process and make the process *** noisy datasets,we found that using a threshold-based approach,such as Adaptive-k,produces better results than using all samples or a fixed number of low-loss samples in the *** the basis of our theoretical analysis and experimental results,we show that the Adaptive-k method is closest to the performance of the Oracle,in which noisy samples are entirely removed from the ***-k is a simple but effective *** does not require prior knowledge of the noise ratio of the dataset,does not require additional model training,and does not increase training time *** the experiments,we also show that Adaptive-k is compatible with different optimizers such as SGD,SGDM,and *** code for Adaptive-k is available at GitHub.

关键词： robust optimization label noise noisy label deep learning noisy datasets noise ratio estimation robust training

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Investigation of micro-scale shear response of sand–rubber granule mixture in terms of particle shape and grain scale deformability effects

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Particuology 2024年第7期90卷 452-469页

作者： Abdulmuttalip Ari Suat Akbulut Department of Civil Engineering Yildiz Technical UniversityIstanbul34220Turkey

In this study,the effects of particle shape of rigid sand and soft rubber materials on macro-scale shear response were reasoned based on micro-scale *** this purpose,first,the shape properties of three different sand and two different rubber samples were quantified using image processing techniques,and the contact model parameters were calibrated through physical *** direct shear test was simulated in a two-dimensional discrete element software with realistic particle *** soft nature of rubber particles was reflected using body-centered cubic packing with a linear-parallel bond contact *** a result,coordination number,distribution of contact forces(i.e.,strong contact,and fabric anisotropy),and contact sliding were derived by the numerical *** has been observed that the particle shape leads to distinctive micro-scale responses due to the variations in the stiffness of the contacts.

关键词： Particle shape Sand Rubber Shear response Micro-scale response Discrete element method

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Ink-structing the future of vascular tissue engineering:a review of the physiological bioink design

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Bio-Design and Manufacturing 2024年第2期7卷 181-205页

作者： Judith Synofzik Sebastian Heene Rebecca Jonczyk Cornelia Blume Institute for technical Chemistry Leibniz University Hannover30167 HannoverGermany

Three-dimensional(3D)printing and bioprinting have come into view for a plannable and standardizable generation of implantable tissue-engineered constructs that can substitute native tissues and *** tissue-engineered structures are intended to integrate with the patient’s *** tissue engineering(TE)is relevant in TE because it supports the sustained oxygenization and nutrition of all tissue-engineered *** have a specific role,representingthenecessarymedium for printability and vascular cell *** review aims to understand the requirements for the design of vascular ***,an in-depth analysis of vascular cell interaction with their native environment must be gained.A physiological bioink suitable for a tissue-engineered vascular graft(TEVG)must not only ensure good printability but also induce cells to behave like in a native vascular vessel,including self-regenerative and growth *** review describes the general structure of vascular walls with wall-speciﬁc cell and extracellular matrix(ECM)components and biomechanical properties and ***,the physiological role of vascular ECM components for their interaction with vascular cells and the mode of interaction is *** currently available or imaginable bioinks are described from physiological matrix proteins to nonphysiologically occurring but natural chemical compounds useful for vascular *** physiological performance of these bioinks is evaluated with regard to biomechanical properties postprinting,with a view to current animal studies of 3D printed vascular ***,the main challenges for further bioink development,suitable bioink components to create a self-assembly bioink concept,and future bioprinting strategies are *** concepts are discussed in terms of their suitability to be part of a TEVG with a high potential for later clinical use.

关键词： Vascular wall histology Vascular cells Microenvironment Extracellular matrix Cell–matrix interaction Bioink Printability

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Automated regression test method for scientific computing libraries:Illustration with SPHinXsys

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Journal of Hydrodynamics 2024年第3期36卷 466-478页

作者： Bo Zhang Chi Zhang Xiangyu Hu TUM School of Engineering and Design Technical University of MunichMunichGermany

Scientific computing libraries,whether in-house or open-source,have witnessed enormous progress in both engineering and scientific ***,it is important to ensure that modifications to the source code,prompted by bug fixing or new feature development,do not compromise the accuracy and functionality that have been already validated and *** paper introduces a method for establishing and implementing an automatic regression test environment,using the open-source multi-physics library SPHinXsys as an illustrative ***,a reference database for each benchmark test is generated from observed data across multiple *** comprehensive database encapsulates the maximum variation range of metrics for different strategies,including the time-averaged,ensemble-averaged,and dynamic time warping *** accounts for uncertainties arising from parallel computing,particle relaxation,physical instabilities,and ***,new results obtained after source code modifications undergo testing based on a curve-similarity comparison against the reference *** the source code is updated,the regression test is automatically executed for all test cases,providing a comprehensive assessment of the validity of the current *** regression test environment has been successfully implemented in all dynamic test cases within SPHinXsys,including fluid dynamics,solid mechanics,fluid-structure interaction,thermal and mass diffusion,reaction-diffusion,and their multi-physics couplings,and demonstrates robust capabilities in testing different *** is noted that while the current test environment is built and implemented for a particular scientific computing library,its underlying principles are generic and can be easily adapted for use with other libraries,achieving equal effectiveness.

关键词： Scientific computing open-source library verification and validation regression test automatic test environment curve similarity comparison smoothed particle hydrodynamics

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Experimental study of the damage characteristics of rocks containing non-penetrating cracks under cyclic loading

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International Journal of Mining Science and Technology 2024年第2期34卷 197-210页

作者： Jun Xu Xiaochun Xiao Lu Ma Sen Luo Jiaxu Jin Baijian Wu School of Mechanics and Engineering Liaoning Technical UniversityFuxin 123000China School of Civil Engineering Liaoning Technical UniversityFuxin 123000China Department of Engineering Mechanics Southeast UniversityNanjing 211189China

The damage evolution process of non-penetrating cracks often causes some unexpected engineering *** specimens containing non-penetrating crack(s)are used to study the damage evolution and characteristics under cyclic *** results show that under cyclic loading,the relationship between the number of non-penetrating crack(s)and the characteristic parameters(cyclic number,peak stress,peak strain,failure stress,and failure strain)of the pre-cracked specimens can be represented by a decreasing linear *** damage evolution equation is fitted by calibrating the accumulative plastic strain for each cycle,and the damage constitutive equation is proposed by the concept of effective ***,non-penetrating cracks are more likely to cause uneven stress distribution,damage accumulation,and local failure of *** local failure can change the stress distribution and relieve the inhibition of non-penetrating crack extension and eventually cause a dramatic destruction of the ***,the evolution process caused by non-penetrating cracks can be regarded as one of the important reasons for inducing *** results are expected to improve the understanding of the process of spalling formation and rockburst and can be used to analyze the stability of rocks or rock structures.

关键词： Damage characteristics Constitutive model Fissured rocks Non-penetrating crack Cyclic loading

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Study on the force chain characteristics with coal dust layer and the three-body contact stiffness

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颗粒学报（英文版） 2024年第9期92卷 288-304页

作者： Xinwei Yang Dongxuan Wu Hongyue Chen Dong Wang School of Mechanical Engineering Liaoning Technical UniversityFuxin123000China Ordos Institute of Liaoning technical university Ordos017000China School of Mining Liaoning Technical UniversityFuxin123000China School of Mechanical Engineering Liaoning Technical UniversityFuxin123000China School of Mechanical Engineering Liaoning Technical UniversityFuxin123000China China National Coal Association Dynamic Research for High-end Complete Integrated Coal Mining Equipment and Big Data Analysis CentreFuxin123000China School of Mining Liaoning Technical UniversityFuxin123000China

To explore the influence of the meso-mechanical behaviors of the wet coal dust layers on the contact stiffness of mechanical bonding surfaces,a three-body contact model incorporating an interface with wet coal dust was constructed based on breakage *** model considered the mechanical surface morphology and contact characteristics of the wet coal *** force chain evolution laws of the wet coal dust layer were elucidated under the effects of gap filling and the cover layer,and the bearing characteristics of the three-body contact bonding surfaces were revealed by quantitative analyses of the number,length,collimation coefficient,and coordination number of the force chains within the wet coal dust ***,the three-body normal contact stiffness under various preload forces was computed and experimentally *** results demonstrate that the external load transfer path of the three-body contact bonding surfaces was from mechanical surface(macroscopic stress)to wet coal dust layer(mesoscopic force chains)and then to mechanical surface(peaks and valleys).The interactions among these three elements contributed to transforming the distributions of the macroscopic stresses and mesoscopic force chains to the locations at the peaks and valleys of the mechanical *** them,the proportion of short force chains in the wet coal dust layer increased from approximately 0.8％-91％,while the proportion of long force chains exhibited an opposite changing *** force chain colli-mation coefficient initially increased and subsequently stabilized,reaching a maximum value of 0.93.A large number of broken,small particles in the wet coal dust layer mainly served to fill the gaps among large *** maximum relative error between the experimental and simulated values on the three-body contact stiffness is 7.26％,indicating that the simulation results can be an approximate substitute for the experimental results with a certain degree of accuracy and practi

关键词： Cover layer effect Force chain Gap filling effect Three-body contact stiffness Wet coal dust

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Selection of shaped charges parameters for producing aluminum particles with velocities in the range of 2.5-16 km/s

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Defence Technology（防务技术） 2024年第8期38卷 126-135页

作者： Vladimir I.Kolpakov Sergey V.Fedorov Ekaterina P.Vinogradova Irina A.Bolotina Bauman Moscow State technical university Moscow 105005Russia

Testing rocket and space technology objects in ground conditions for resistance to the impact of meteoroids and fragments of space debris can be carried out using shaped charges. To substantiate the design parameters of shaped charges that ensure the formation of aluminum particles in a wide velocity range(from 2.5 to 16 km/s), numerical modeling of the formation process was carried out within the framework of a two-dimensional axisymmetric problem of continuum mechanics using three different computing codes to increase the reliability of the results. The calculations consider shaped charges with a diameter of 20-100 mm with aluminum liners of various shapes. It is shown that the formation of particles with velocities close to the lower limit of the considered range is ensured by gently sloping segmental liners of degressive thickness. To form higher-velocity particles with velocities over 5 km/s, it is proposed to use combined liners, the jet-forming part of which has the shape of a hemisphere of constant thickness or the shape of a semi-ellipsoid or semi-superellipsoid of rotation of degressive thickness.

关键词： Space debris Meteoric impact Explosion Shaped charge High-velocity aluminum element Segmental liner Combined liner Numerical simulation

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