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Chebyshev polynomial-based Ritz method for thermal buckling and free vibration behaviors of metal foam beams

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 891-910页

作者： N.d.NGUYEN t.N.NGUYEN Faculty of Civil Engineering Ho Chi Minh City University of Technology and EducationHo Chi Minh City 71309Viet Nam Faculty of Engineering and technology Kien Giang UniversityChau Thanh 92000Viet Nam

this study presents the Chebyshev polynomials-based Ritz method to examine the thermal buckling and free vibration characteristics of metal foam beams.the analyses include three models for porosity distribution and two scenarios for thermal distribution.the material properties are assessed under two conditions,i.e.,temperature dependence and temperature independence.the theoretical framework for the beams is based on the higher-order shear deformation theory,which incorporates shear deformations with higher-order polynomials.the governing equations are established from the Lagrange equations,and the beam displacement fields are approximated by the Chebyshev polynomials.Numerical simulations are performed to evaluate the effects of thermal load,slenderness,boundary condition(BC),and porosity distribution on the buckling and vibration behaviors of metal foam beams.the findings highlight the significant influence of temperature-dependent(td)material properties on metal foam beams'buckling and vibration responses.

关键词： Ritz method Chebyshev function buckling vibration metal foam beam higher-order beam theory(HOBt)

Near resonance vibration isolation on a levered-dual response(LEdAR)Coulomb-damped system by differential preloads/offsets in linear springs

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Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 1033-1050页

作者： t.I.tOLUWALOJU C.K.tHEIN d.HALIM department of Mechanical Materials and Manufacturing EngineeringUniversity of Nottingham Ningbo ChinaNingbo 315100Zhejiang ProvinceChina Nottingham Ningbo China Beacons of Excellence Research and Innovation Institute University of Nottingham Ningbo ChinaNingbo 315048Zhejiang ProvinceChina

the levered-dual response(LEdAR)Coulomb-damped system attains near resonant vibration isolation by differential preloads/offsets in linear springs.It takes the advantages of both the preloads/offsets in linear springs and the guiderail friction for realizing different levels of vibration isolation.the isolation capacities are investigated on the strategies with both the horizontal and vertical guiderails,with the horizontal rail only,and without guiderails.the compressive preloads generally result in the consumption of most of the initial excitation energy so as to overcome the potential threshold.the isolation onsets at the frequency ratio of 1∓0.095 on the left-hand side(LHS)and the right-hand side(RHS)of the lever are relative to the load plate connector.the observed near resonant isolation thus makes the LEdAR system a candidate for the isolation of the mechanical systems about resonance while opening a path for simultaneous harvesterisolation functions and passive functions at extreme frequencies.

关键词： lever ratio Coulomb damping preload tension/compression isolation band/depth offset potential

SMILE soft X-ray Imager flight model CCd370 pre-flight device characterisation

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Earth and Planetary Physics 2024年第1期8卷 25-38页

作者： S.Parsons d.J.Hall O.Hetherington t.W.Buggey t.Arnold M.W.J.Hubbard A.Holland Centre for Electronic Imaging the Open UniversityMilton KeynesMK76AAUK

throughout the SMILE mission the satellite will be bombarded by radiation which gradually damages the focal plane devices and degrades their performance.In order to understand the changes of the CCd370s within the soft X-ray Imager,an initial characterisation of the devices has been carried out to give a baseline performance level.three CCds have been characterised,the two flight devices and the flight spa re.this has been carried out at the Open University in a bespo ke cleanroom measure ment facility.the results show that there is a cluster of bright pixels in the flight spa re which increases in size with tempe rature.However at the nominal ope rating tempe rature(-120℃) it is within the procure ment specifications.Overall,the devices meet the specifications when ope rating at -120℃ in 6 × 6 binned frame transfer science mode.the se rial charge transfer inefficiency degrades with temperature in full frame mode.However any charge losses are recovered when binning/frame transfer is implemented.

关键词： CCd soft X-ray imager characterisation SMILE

Advancing Wound Filling Extraction on 3d Faces:An Auto-Segmentation and Wound Face Regeneration Approach

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 2197-2214页

作者： duong Q.Nguyen thinh d.Le Phuong d.Nguyen Nga t.K.Le H.Nguyen-Xuan department of Mathematics and Statistics Quy Nhon UniversityQuy Nhon City55100Viet Nam Applied Research Institute for Science and technology Quy Nhon UniversityQuy Nhon City55100Viet Nam CIRtECH Institute HUTECH UniversityHo Chi Minh City72308Viet Nam

Facial wound segmentation plays a crucial role in preoperative planning and optimizing patient outcomes in various medical applications.In this paper,we propose an efficient approach for automating 3d facial wound segmentation using a two-stream graph convolutional network.Our method leverages the Cir3d-FaIR dataset and addresses the challenge of data imbalance through extensive experimentation with different loss functions.to achieve accurate segmentation,we conducted thorough experiments and selected a high-performing model from the trainedmodels.the selectedmodel demonstrates exceptional segmentation performance for complex 3d facial wounds.Furthermore,based on the segmentation model,we propose an improved approach for extracting 3d facial wound fillers and compare it to the results of the previous study.Our method achieved a remarkable accuracy of 0.9999993% on the test suite,surpassing the performance of the previous method.From this result,we use 3d printing technology to illustrate the shape of the wound filling.the outcomes of this study have significant implications for physicians involved in preoperative planning and intervention design.By automating facial wound segmentation and improving the accuracy ofwound-filling extraction,our approach can assist in carefully assessing and optimizing interventions,leading to enhanced patient outcomes.Additionally,it contributes to advancing facial reconstruction techniques by utilizing machine learning and 3d bioprinting for printing skin tissue implants.Our source code is available at https://***/SIMOGroup/WoundFilling3d.

关键词： 3d printing technology face reconstruction 3d segmentation 3d printed model

Late Ordovician Mass Extinction: Earth, fire and ice

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National Science Review 2024年第1期11卷 51-65页

作者： david A.t.Harper Palaeoecosystems Group Department of Earth SciencesDurham University

the Late Ordovician Mass Extinction was the earliest of the ‘big’ five extinction events and the earliest to affect the trajectory of metazoan life. two phases have been identified near the start of the Hirnantian period and in the middle. It was a massive taxonomic extinction, a weak phylogenetic extinction and a relatively benign ecological extinction. A rapid cooling, triggering a major ice age that reduced the temperature of surface waters, prompted a drop in sea level of some 100 m and introduced toxic bottom waters onto the shelves. these symptoms of more fundamental planetary processes have been associated with a range of factors with an underlying driver identified as volcanicity. Volcanic eruptions, and other products, may have extended back in time to at least the Sandbian and early Katian, suggesting the extinctions were more protracted and influential than hitherto documented.

关键词： Ordovician LOME paleoecology palaeobiogeography biotas

detailed seismic zoning of the East Kazakhstan region in the Republic of Kazakhstan

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Geodesy and Geodynamics 2024年第2期15卷 156-165页

作者： Natalya V.Silacheva N.P.Stepanenko O.K.Kurilova A.d.Kudabayeva A.t.danabayeva Institute of Seismology Ministry of Emergency SituationsAlmaty 050060Kazakhstan

Kazakhstan is currently drafting new construction regulations that comply with the major provisions of the Eurocodes.Such regulations are created on the basis of seismic zoning maps of various degrees of detail,developed by our Institute of Seismology using a new methodological approach for Kazakhstan.the article is about creating the first normative map of the detailed Seismic Zoning on a probabilistic foundation for the Republic of Kazakhstan’s East Kazakhstan region.We carried out the probabilistic assessment of seismic hazard using a methodology consistent with the main provisions of Eurocode 8and updated compared with that used in developing maps of Kazakhstan’s General Seismic Zoning and seismic microzoning of Almaty.the most thorough and current data accessible for the area under consideration were combined with contemporary analytical techniques.Updates have been done to not only the databases being used but also the way seismic sources were shown,including active faults now.On a scale of 1:1000000,precise seismic zoning maps of the East Kazakhstan region were created for two probabilities of exceedance:10%and 2%in 50 years in terms of peak ground accelerations and macroseismic intensities.the obtained seismic hazard distribution is generally consistent with the General Seismic Zoning of Kazakhstan’s previous findings.However,because active faults were included and a thoroughly revised catalog was used,there are more pronounced zones of increased danger along the fault in the western part of the region.In the west of the territory,acceleration values also increased due to a more accurate consideration of seismotectonic conditions.Zoning maps are the basis for developing new state building regulations of the Republic of Kazakhstan.

关键词： Probabilistic seismic hazard assessment detailed seismic zoning Peak ground acceleration Microseismical intensity

Aerodynamics of a tandem-Bladed Axial Compressor Rotor under Circumferential distortion at different Rotational Speeds

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Journal of thermal Science 2024年第4期33卷 1340-1356页

作者： Amit KUMAR Jerry t.JOHN A.M.PRAdEEP R.A.d.AKKERMANS dragan KOZULOVIC department of Aerospace Engineering Indian Institute of Technology Bombay department of Automotive and Aeronautical Engineering Hamburg University of Applied Sciences Institute of Jet Propulsion Bundeswehr University Munich

For most aircraft engines,inflow distortion is inevitable.Inflow distortion is known to degrade the aerodynamic performance and stable operating limits of a compressor.tandem rotor configuration is an arrangement that effectively controls the growth of the boundary layer over the suction surface of the blade.therefore,a higher total pressure rise can be achieved through this unconventional design approach involving the splitting of the blade into forward and aft sections.It is expected that the effect of inlet flow distortion would be more severe for a tandem-rotor design due to the greater flow turning inherent in such designs.However,this aspect needs to be thoroughly examined.the present study discusses the effect of circumferential distortion on the tandem-rotor at different rotational speeds.Full-annulus RANS simulations using ANSYS CFX are used in the present study.the performance of the rotor at a particular flow coefficient and different rotational speeds is compared.the total pressure and efficiency are observed to drop at lower mass flow rates under the influence of circumferential distortion.the loss region in each blade passage is mainly associated with the blade wake,tip leakage vortex,secondary flow,and boundary layer.However,their contribution varies from passage to passage,particularly in the distorted sector.At the lower span,the wake width is found to be higher than that at a higher span.due to the redistribution of the mass flow,the circumferential extent reduces at a higher span.In the undistorted sector,the strength of the tip leakage vortex is significantly higher at the design rotational speed than at lower speeds.the distortion near the tip region promotes an early vortex breakdown even at the design operating condition.this adversely affects the total pressure,efficiency,and stall margin.Under clean flow conditions,this phenomenon is only observed near the stall point.At the design operating condition,the breakdown of the forward rotor tip leakage vortex is detected in four blade passages

关键词： tandem rotor circumferential distortion loss tip leakage vortex vortex breakdown diffusion factor aerodynamics of compressor blade

the CCd instrument background of the SMILE SXI

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Earth and Planetary Physics 2024年第1期8卷 15-24页

作者： M.W.J.Hubbard O.Hetherington d.J.Hall t.W.Buggey S.Parsons t.Arnold A.Holland C.Pagani S.Sembay Centre for Electronic Imaging The Open UniversityMilton KeynesMK76AAUK X-ray and Observational Astronomy Group Department of Physics&AstronomyUniversity of LeicesterLE17RHUK

the ESA and CAS SMILE mission orbit is highly elliptical and will pass through multiple radiation environments.the Soft X-ray Imager(SXI)instrument aboard has a radiation shutter door designed to close when the surrounding radiation flux is high.the shutter door will close when passing below an altitude threshold to protect against trapped particles in the Earth’s Van Allen Belts.therefore,two radiation environments can be approximated based on the shutter door position:open and closed.the instrument background for the CCds(Charge-Coupled devices)that form the focal plane array of the SXI were evaluated for the two environments.due to the correlation of the space environment with the solar cycle,the solar minima and maxima,the background was also evaluated at these two extremes.the results demonstrated that the highest instrument background will occur during solar minima due to the main contributing source being Galactic Cosmic Rays(GCRs).It was also found that the open background was highest for solar minima and that the closed background was highest during solar maxima.this is due to the radiation shutter door acting as a scattering centre and the changes in the energy flux distribution of the GCRs between the two solar extremes.

关键词： instrument background X-ray astronomy space radiation

Ion heat transport in electron cyclotron resonance heated L-mode plasma on the t-10 tokamak

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Plasma Science and technology 2024年第4期26卷 52-60页

作者： V.A.KRUPIN M.R.NURGALIEV A.R.NEMEtS I.A.ZEMtSOV S.d.SUNtSOV t.B.MYALtON d.S.SERGEEV N.A.SOLOVEV d.V.SARYCHEV d.V.RYJAKOV S.N.tUGARINOV N.N.NAUMENKO National Research Centre“Kurchatov Institute” Moscow 123182Russia Bauman Moscow State technical University Moscow 105005Russia Institution“Project Center ItER” Moscow 123098Russia JSC“SOLAR” Minsk 220034Belarus

Anomalous ion heat transport is analyzed in the t-10 tokamak plasma heated with electron cyclotron resonance heating(ECRH) in second-harmonic extra-ordinary mode. Predictive modeling with empirical scaling for Ohmical heat conductivity shows that in ECRH plasmas the calculated ion temperature could be overestimated, so an increase of anomalous ion heat transport is required. to study this effect two scans are presented: over the EC resonance position and over the ECRH power. the EC resonance position varies from the high-field side to the low-field side by variation of the toroidal magnetic field. the scan over the heating power is presented with on-axis and mixed ECRH regimes. discharges with high anomalous ion heat transport are obtained in all considered regimes. In these discharges the power balance ion heat conductivity exceeds the neoclassical level by up to 10 times. the high ion heat transport regimes are distinguished by three parameters: the ratio te/ti, the normalized electron density gradient R/■, and the ion–ion collisionality νii~*. the combination of high te/ti, high νii~*, and R/■=6-10 results in values of normalized anomalous ion heat fluxes up to 10 times higher than in the low transport scenario.

关键词： tokamak L-mode electron cyclotron resonance heating ion heat transport