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Control and vibration analyses of a sandwich doubly curved micro-composite shell with honeycomb, truss, and corrugated cores based on the fourth-order shear deformation theory

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Applied Mathematics and Mechanics(English Edition) 2024年第10期45卷 1773-1790页

作者： f.SHIRDELAN M.MOHAMMADIMEHR f.BARGOZINI Department of Solid Mechanics Faculty of Mechanical Engineering University of Kashan

Curved shells are increasingly utilized in applied engineering due to their shared characteristics with other sandwich structures, flexibility, and attractive appearance. However, the inability of controlling and regulating vibrations and destroying them afterward is a challenge to scientists. In this paper, the curve shell equations and a linear quadratic regulator are adopted for the state feedback design to manage the structure vibrations in state space forms. A five-layer sandwich doubly curved micro-composite shell, comprising two piezoelectric layers for the sensor and actuator, is modeled by the fourth-order shear deformation theory. The core(honeycomb, truss, and corrugated) is analyzed for the bearing of transverse shear forces. The results show that the honeycomb core has a greater effect on the vibrations. when the parameters related to the core and the weight percentage of graphene increase, the frequency increases. The uniform distribution of graphene platelets results in the lowest natural frequency while the natural frequency increases. furthermore, without taking into account the piezoelectric layers,the third-order shear deformation theory(TSDT) and fourth-order shear deformation theory(fOSDT) align closely. However, when the piezoelectric layers are incorporated,these two theories diverge significantly, with the frequencies in the fOSDT being lower than those in the TSDT.

关键词： 74f15 corrugate core doubly curved shell honeycomb micro-composite O343 truss vibration and control

The 2024 Compendium of Physical Activities and its expansion

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Journal of Sport and Health Science 2024年第1期13卷 1-2,F0003页

作者： stephen D.Herrmann Erik A.willis Barbara E.Ainsworth Kansas Center for Metabolism and Obesity Research University of Kansas Medical CenterKansas CityKS 66160USA Center for Health Promotion and Disease Prevention University of North Carolina at Chapel HillChapel HillNC 27599USA School of Exercise and Health Shanghai University of SportShanghai 200438China

first developed 30 years ago,the Compendium of Physical Activities(Compendium)was created to provide a standardized way of measuring and classifying specific physical activities(PAs),allowing researchers and health professionals to assess the energy expenditure and health benefits associated with different PA.1Since its inception,the Compendium has been widely utilized and recognized as a fundamental PA and health resource.

关键词： has utilized classify

A Preliminary Comparative Study on the Centering Algorithms for CassiniISS NAC Images

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Research in Astronomy and Astrophysics 2024年第10期24卷 58-65页

作者： T.Liang Q.-f.Zhang G.-M.Liu w.-H.Zhu C.-S.wang Department of Computer Science Jinan UniversityGuangzhou 510632China Sino-french Joint Laboratory for Astrometry Dynamics and Space ScienceJinan UniversityGuangzhou 510632China School of Computer Science Guangdong University of EducationGuangzhou 510303China

Obtaining high precision is an important consideration for astrometric studies using images from the Narrow Angle Camera(NAC)of the Cassini Imaging Science Subsystem(ISS).Selecting the best centering algorithm is key to enhancing astrometric *** this study,we compared the accuracy of five centering algorithms:Gaussian fitting,the modified moments method,and three point-spread function(PSf)fitting methods(effective PSf(ePSf),PSfEx,and extended PSf(x PSf)from the Cassini Imaging Central Laboratory for Operations(CICLOPS)).we assessed these algorithms using 70 ISS NAC star field images taken with CL1 and CL2 filters across different stellar *** ePSf method consistently demonstrated the highest accuracy,achieving precision below 0.03 pixels for stars of magnitude *** to the previously considered best,the modified moments method,the e PSf method improved overall accuracy by about 10%and 21%in the sample and line directions,***,the xPSf model provided by CICLOPS had lower precision than the ***,the ePSf exhibits an improvement in measurement precision of 23%and 17%in the sample and line directions,respectively,over the *** discrepancy might be attributed to the xPSf focusing on photometry rather than *** findings highlight the necessity of constructing PSf models specifically tailored for astrometric purposes in NAC images and provide guidance for enhancing astrometric measurements using these ISS NAC images.

关键词： methods:analytical techniques:image processing stars:imaging astrometry

Novel photoactive material and fabrication techniques for solar cells application: nanocellulose-based graphene oxide CdS composite

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CLEAN ENERGY 2024年第2期8卷 189-216页

作者： Shoyiga, Hassan Oriyomi Akpasi, stephen Okiemute Akpan, Joseph Amune, Ubani Oluwaseun Kiambi, Sammy Lewis North west Univ Chem Dept Mafikeng South Africa North west Univ Fac Nat & Agr Sci Mat Sci Innovat & Modelling MaSIM Res Focus Area Mafikeng Campus Mmabatho South Africa Durban Univ Technol Chem Engn Dept Green Engn Res Grp Durban South Africa Durban Univ Technol Ind Engn Dept Durban South Africa Edo State Univ Chem Engn Dept Uzairue Nigeria Vaal Univ Technol Chem Engn Dept Vanderbijlpark South Africa

In recent times, solar energy has become one of the largest available sources of renewable energy at our disposal. However, the design of highly efficient solar cells is increasingly becoming crucial as there has been a surge for economically viable alternative energy sources with the lowest cost. Significant advances have been made through different routes to make photovoltaic (PV)/solar technologies economically viable, eco-friendly and consequently scalable. As a result, cellulose nanomaterials have become one of the emerging technologies in this regard because of the advantages of high-value bio-based nanostructured materials, such as their abundance and sustainability. Nanocellulose-based photoactive nanocomposite materials can be made by integrating conducting photoactive and electroconductive materials with hydrophilic biocompatible cellulose. Inorganic nanoparticles, such as graphene/reduced graphene oxide cadmium sulphide quantum dots, amongst others, can be introduced into the nanocellulose matrix and can be applied either as charge transporters or photoactive materials in different types of solar cells. Thus, in this review, we highlight the optoelectronic properties of different photoactive materials, particularly nanocellulose-based graphene nanocomposites; their efficiencies and drawbacks were X-rayed. The effect of doping each PV material on the PV performance is also discussed. It is anticipated that the novel material would result in a reduction in the cost of solar cells, jointly enhancing their efficacy in generating environmentally friendly electricity. Since the fabrication techniques and equipment play a crucial role in the development of solar cells, the fabrication techniques of bulk-heterojunction (BHJ) cells containing a nanocellulose-based graphene composite and case studies of already fabricated BHJ PV cells with nanocellulose-based graphene composite are discussed. The optoelectronic properties of different photoactive materials, particu

关键词： nanocellulose-based composite bulk heterojunction graphene composite photoactive materials fabrication techniques solar energy power conversion efficiency INTERNAL QUANTUM EffICIENCY POLYMER PHOTOVOLTAIC CELLS OPEN-CIRCUIT VOLTAGE ONE-POT SEMICONDUCTING POLYMERS CONJUGATED POLYMERS EXCITON DIffUSION fACILE SYNTHESIS GREEN REDUCTION SMALL-MOLECULE

Scalable Jet-Based fabrication of PEI-Hydrogel Particles for CO2 Capture

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ENERGY & ENVIRONMENTAL MATERIALS 2024年第6期7卷 351-358页

作者： Jiang, Jieke van Daatselaar, Eline wijnja, Hylke de Koning Gans, Tessa Schellevis, Michel Venner, Cornelis H. Brilman, Derk w. f. Visser, Claas willem Univ Twente Fac Engn Technol Dept Thermal & Fluid Engn Engn Fluid Dynam Grp NL-7500 AE Enschede Netherlands Univ Twente Fac Sci & Technol Sustainable Proc Technol NL-7500 AE Enschede Netherlands

The capture, regeneration, and conversion of CO2 from ambient air and flue gas streams are critical aspects of mitigating global warming. Solid sorbents for CO2 absorption are very promising as they have high mass transfer areas without energy input and reduce emissions and minimize corrosion as compared to liquid sorbents. However, precisely tunable solid CO2 sorbents are difficult to produce. Here, we demonstrate the high-throughput production of hydrogel-based CO2-absorbing particles via liquid jetting. By wrapping a liquid jet consisting of an aqueous solution of cross-linkable branched polyethylenimine (PEI) with a layer of suspension containing hydrophobic silica nanoparticles, monodisperse droplets with a silica nanoparticle coating layer was formed in the air. A stable Pickering emulsion containing PEI droplets was obtained after these ejected droplets were collected in a heated oil bath. The droplets turn into mm-sized particles after thermal curing in the bath. The diameter, PEI content, and silica content of the particles were systematically varied, and their CO2 absorption was measured as a function of time. Steam regeneration of the particles enabled cyclic testing, revealing a CO2 absorption capacity of 6.5 +/- 0.5 mol kg(-1) solid PEI in pure CO2 environments and 0.7 +/- 0.3 mol kg(-1) solid PEI for direct air capture. Several thousands of particles were produced per second at a rate of around 0.5 kg per hour, with a single nozzle. This process can be further scaled by parallelization. The complete toolbox for the design, fabrication, testing, and regeneration of functional hydrogel particles provides a powerful route toward novel solid sorbents for regenerative CO2 capture.

关键词： CO2 capture droplet hydrogel liquid jet particle steam regeneration CARBON-DIOXIDE CAPTURE STEAM REGENERATION SORBENTS ADSORPTION SILICA GAS SEPARATION RECOVERY DROPLETS METHANE

The magnetosheath at high spectral resolution

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Earth and Planetary Physics 2024年第1期8卷 234-246页

作者： K.D.Küntz D.Koutroumpa w.R.Dunn A.foster f.S.Porter D.G.Sibeck B.walsh The Henry A.Rowland Department of Physics and Astronomy Johns Hopkins University3701 San Martin DriveBaltimoreMD21218USA NASA Goddard Space flight Center 8800 Greenbelt RoadGreenbeltMD 20771USA LATMOS-OVSQ CNRSUVSQ Paris-SaclaySorbonne Université11 Boulevard d’Alembert78280GuyancourtFrance Department of Physics and Astronomy University College LondonLondonUK The Centre for Planetary Science at UCL/Birkbeck Gower StreetLondon WC1E 6BTUK Center for Astrophysics Harvard University&Smithsonian Institution60 Garden StreetCambridgeMA 02138USA Center for Space Physics Boston University110 Cummington MallBostonMAUSA

while we eagerly anticipate SMILE’s(Solar wind Magnetosphere Ionosphere Link Explorer)unprecedented X-ray observations of the Earth’s magnetosheath and the initiation of a new era of magnetospheric research,it seems appropriate to look ahead to the abilities of the next generation of astrophysics *** these,the Line Emission Mapper(LEM),a large aperture micro-calorimeter based mission,is currently planned to be able to observe the magnetosheath at high spectral resolution(~2 eV).with a field of view of~30′,LEM will allow higher spatial resolution and higher cadence measurement of the motion of a very small portion of the magnetopause over relatively short periods of time(multiple hours),complementing SMILE’s global ***’s strength is its spectral *** will be able to measure the abundance of a broad range of elements and ionization states,many of which are inaccessible to current in situ instruments,and will be able to separate the emission from the magnetosheath from the emission from the cosmic X-ray background using the difference in their relative velocities.

关键词： magnetosheath charge exchange solar wind abundances

Bolstering integrity in environmental data science and machine learning requires understanding socioecological inequity

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frontiers of Environmental Science & Engineering 2024年第5期18卷 171-179页

作者： Joe f.Bozeman III School of Civil and Environmental Engineering Georgia Institute of TechnologyAtlantaGA30332USA School of Public Policy Georgia Institute of TechnologyAtlantaGA30332USA

Socioecological inequity in environmental data science—such as inequities deriving from data-driven approaches and machine learning(ML)—are current issues subject to debate and *** is growing consensus around embedding equity throughout all research and design domains—from inception to administration,while also addressing procedural,distributive,and recognitional ***,practically doing so may seem onerous or daunting to *** current perspective helps to alleviate these types of concerns by providing substantiation for the connection between environmental data science and socioecological inequity,using the Systemic Equity framework,and provides the foundation for a paradigmatic shift toward normalizing the use of equity-centered approaches in environmental data science and ML *** the integrity of environmental data science and ML is just beginning from an equity-centered tool development and rigorous application *** this end,this perspective also provides relevant future directions and challenges by overviewing some meaningful tools and strategies—such as applying the wells-Du Bois Protocol,employing fairness metrics,and systematically addressing irreproducibility;emerging needs and proposals—such as addressing data-proxy bias and supporting convergence research;and establishes a ten-step path ***,the work that environmental scientists and engineers do ultimately affect the well-being of us all.

关键词： Equity Bias Machine Learning Data Science Justice Systemic Equity

Neuropeptide cholecystokinin:a key neuromodulator for hippocampal functions

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Neural Regeneration Research 2025年第7期20卷 1991-1992页

作者： fengwen Huang stephen Temitayo Bello Department of Neuroscience City University of Hong KongKowloon TongHong Kong Special Administrative RegionChina Center for Regenerative Medicine and Health Hong Kong Institute of Science&InnovationChinese Academy of SciencesHong Kong Special Administrative RegionChina

Spatial memory is crucial for survival within external surroundings and wild *** hippocampus,a critical hub for spatial learning and memory formation,has received extensive investigations on how neuromodulators shape its functions(Teixeira et al.,2018;Zhang et al.,2024).However,the landscape of neuromodulations in the hippocampal system remains poorly understood because most studies focus on classical monoamine neuromodulators,such as acetylcholine,serotonin,dopamine,and *** neuropeptides,comprising the most abundant neuromodulators in the central nervous system,play a pivotal role in neural information processing in the hippocampal ***(CCK),one of the most abundant neuropeptides,has been implicated in regulating various physiological and neurobiological statuses(Chen et al.,2019).CCK-A receptor(CCK-AR)and CCK-B receptors(CCK-BR)are two key receptors mediating the biological functions of CCK,both of which belong to class-A sevenfold transmembrane G protein-coupled receptors(Nishimura et al.,2015).CCK-AR preferentially reacts to sulfated CCK,whereas CCK-BR binds both CCK and gastrin with similar affinities(Ding et al.,2022).The expression patterns of CCK-AR and CCK-BR are distinct,implying that CCK has various functions in target *** instance,CCK-AR is widely expressed in the GI and brain subregions and is hence implicated in the control of digestive function and satiety ***,CCK-BR is abundantly and widely distributed in the central nervous system,which majorly regulates anxiety,learning,and memory(Ding et al.,2022).However,the roles of endogenous CCK and CCK receptors in regulating hippocampal function at electrophysiological and behavioral levels have received less attention.

关键词： abundant functions modulator

Superplasticity of fine-grained Mg-10Li alloy prepared by severe plastic deformation and understanding its deformation mechanisms

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Journal of Magnesium and Alloys 2024年第1期12卷 316-331页

作者： H.T.Jeong S.w.Lee w.J.Kim Department of Materials Science and Engineering Hongik UniversityMapo-guSangsu-dong 72-1Seoul 121-791Republic of Korea

The superplastic behavior and associated deformation mechanisms of a fine-grained Mg-10.1 Li-0.8Al-0.6Zn alloy(LAZ1011)with a grain size of 3.2μm,primarily composed of the BCCβphase and a small amount of the HCPαphase,were examined in a temperature range of 473 K to 623 *** microstructural refinement of this alloy was achieved by employing high-ratio differential speed *** best superplasticity was achieved at 523 K and at strain rates of 10^(-4)-5×10^(-4)s^(-1),where tensile elongations of 550±600%were *** the heating and holding stage of the tensile samples prior to tensile loading,a significant increase in grain size was observed at temperatures above 573 ***,it was important to consider this effect when analyzing and understanding the superplastic deformation behavior and *** the investigated strain rate range,the superplastic flow at low strain rates was governed by lattice diffusion-controlled grain boundary sliding,while at high strain rates,lattice diffusion-controlled dislocation climb creep was the rate-controlling deformation *** was concluded that solute drag creep is unlikely to *** the late stages of deformation at 523 K,it was observed that grain boundary sliding led to the agglomeration of theαphase,resulting in significant strain *** mechanism maps were constructed forβ-Mg-Li alloys in the form of 2D and 3D formats as a function of strain rate,stress,temperature,and grain size,using the constitutive equations for various deformation mechanisms derived based on the data of the current tests.

关键词： Magnesium-lithium alloy Superplasticity Severe plastic deformation Grain size Grain growth