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Numerical analysis of high‑speed railway slab tracks using calibrated and validated 3d time‑domain modelling

Railway Engineering Science 2024年第1期32卷 36-58页

作者： A.F.Esen O.Laghrouche P.K.Woodward d.Medina‑Pineda Q.Corbisez J.Y.Shih d.P.Connolly Institute for High‑Speed Rail and System Integration University of LeedsLeeds LS29JTUK Institute for Infrastructure and Environment Heriot-Watt UniversityEdinburgh EH144ASUK Alstom Transport Saint‑OuenFrance Birmingham Centre for Railway Research and Education University of BirminghamBirmingham B152TTUK

Concrete slabs are widely used in modern railways to increase the inherent resilient quality of the tracks,provide safe and smooth rides,and reduce the maintenance frequency.In this paper,the elastic performance of a novel slab trackform for high-speed railways is investigated using three-dimensional finite element modelling in Abaqus.It is then compared to the performance of a ballasted track.First,slab and ballasted track models are developed to replicate the full-scale testing of track sections.Once the models are calibrated with the experimental results,the novel slab model is developed and compared against the calibrated slab track results.The slab and ballasted track models are then extended to create linear dynamic models,considering the track geodynamics,and simulating train passages at various speeds,for which the Ledsgard documented case was used to validate the models.Trains travelling at low and high speeds are analysed to investigate the track deflections and the wave propagation in the soil,considering the issues associated with critical speeds.Various train loading methods are discussed,and the most practical approach is retained and described.Moreover,correlations are made between the geotechnical parameters of modern high-speed rail and conventional standards.It is found that considering the same ground condition,the slab track deflections are considerably smaller than those of the ballasted track at high speeds,while they show similar behaviour at low speeds.

关键词： High-speed railways Slab track New ballastless track Ballasted track Critical speeds Finite element modelling Calibration of numerical models

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Connecting cellular mechanisms and extracellular vesicle cargo in traumatic brain injury

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Neural Regeneration Research 2024年第10期19卷 2119-2131页

作者： Nikita Ollen-Bittle Austyn d.Roseborough Wenxuan Wang Jeng-liang d.Wu Shawn N.Whitehead department of Anatomy and Cell Biology Western UniversityLondonONCanada Schulich School of Medicine and dentistry Western UniversityLondonONCanada deparment of Clinical Neurological Sciences Western UniversityLondonONCanada

Traumatic brain injury is followed by a cascade of dynamic and complex events occurring at the cellular level. These events include: diffuse axonal injury, neuronal cell death, blood-brain barrier break down, glial activation and neuroinflammation, edema, ischemia, vascular injury, energy failure, and peripheral immune cell infiltration. The timing of these events post injury has been linked to injury severity and functional outcome. Extracellular vesicles are membrane bound secretory vesicles that contain markers and cargo pertaining to their cell of origin and can cross the blood-brain barrier. These qualities make extracellular vesicles intriguing candidates for a liquid biopsy into the pathophysiologic changes occurring at the cellular level post traumatic brain injury. Herein, we review the most commonly reported cargo changes in extracellular vesicles from clinical traumatic brain injury samples. We then use knowledge from animal and in vitro models to help infer what these changes may indicate regrading cellular responses post traumatic brain injury. Future research should prioritize labeling extracellular vesicles with markers for distinct cell types across a range of timepoints post traumatic brain injury.

关键词： axonal injury biomarkers blood-brain barrier chronic traumatic encephalopathy extracellular vesicles glial activation neuroinflammation traumatic brain injury

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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 missions.Of 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 mapping.LEM’s strength is its spectral resolution.It 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

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Are population cycles recovering?

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Integrative Zoology 2024年第3期19卷 538-547页

作者： Vasily d.YAKUSHOV Boris I.SHEFTEL A.N.Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences MoscowRussia

The dynamics of populations of small mammals of Central Siberia was analyzed.The studies were carried out at the Yenisei ecological station“Mirnoye”of the A.N.Severtsov Institute of Ecology and Evolution,Russian Academy of Sciences.The time series analysis was performed by the wavelet transform using the statistical data processing language R.In the 20th century,the dynamics of the population of the community and some of its constituent species(Sorex araneus;S.caecutiens;S.isodon;S.tundrensis;S.minutus;Craseomys rufocanus;Clethrionomys rutilus;Microtus oeconomus;M.agrestis)were characterized by a 4-year periodicity.The type of dynamics changed to noncyclic by the nineties,but by 2022,four species(S.araneus,S.isodon,C.rutilus,and M.oeconomus)and the community as a whole showed a tendency toward recovery of population cycles.The remaining species were characterized by consistently low numbers with irregular low amplitude fluctuations.

关键词： population cycles small mammals time-series analysis wavelet transform

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Improved Leap-frog Method for Time-domain Fault Location

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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 670-674页

作者： Izudin džafić Rabih A.Jabr Faculty of Electrical Engineering University of SarajevoSarajevo 71000Bosnia and Herzegovina department of Electrical and Computer Engineering American University of BeirutBeirut 11072020Lebanon IEEE

The partial differential equation(PdE)solution of the telegrapher is a promising fault location method among time-domain and model-based techniques.Recent research works have shown that the leap-frog process is superior to other explicit methods for the PdE solution.However,its implementation is challenged by determining the initial conditions in time and the boundary conditions in space.This letter proposes two implicit solution methods for determining the initial conditions and an analytical way to obtain the boundary conditions founded on the signal decomposition.The results show that the proposal gives fault location accuracy superior to the existing leap-frog scheme,particularly in the presence of harmonics.

关键词： Fault location leap-frog partial differential equation time-domain analysis transmission line

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Numerical calculation of Z-scan measurements for nonlinear media with large phase shift

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Optoelectronics Letters 2024年第3期20卷 177-182页

作者： M.d.Zidan A.Allahham department of Physics Atomic Energy Commission of SyriaP.O.Box 6091DamascusSyria

We have reported the characteristics of a Z-scan for the poly(azaneylylidene-acylene)(dAZA) polymer, as nonlinear medium with a large nonlinear phase shift using continuous-wave(CW) laser beam. It has been verified that the Fresnel diffraction model is applicable for analyses of Z-scan measurements with dAZA polymer at high laser power. It was found that Z-scan curves with peak-to-valley features appear as the applied light intensity increases in the case of a large nonlinear phase shift. The Z-scan experiments were carried out using a CW laser to verify the theoretical calculations in the case of a large nonlinear phase shift model. Our results show good agreements between the experimental data and the proposed theoretical models.

关键词： nonlinear phase media

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Vitamin d and hypertension:Is there any significant relation?

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Chronic diseases and Translational Medicine 2024年第2期10卷 156-158页

作者： Naga P.Vakkalagadda Sri H.Narayana Gummadi S.Sree Lakshmi d.Bethineedi L.V.Simhachalam Kutikuppala Gnana d.Medarametla department of General Medicine Guntur Medical CollegeGunturAndra PradeshIndia department of General Medicine Narayana Medical College and HospitalNelloreAndhra PradeshIndia department of General Medicine Andhra Medical CollegeVisakhapatnamAndhra PradeshIndia department of General Surgery Dr NTR University of Health SciencesVijayawadaAndhra PradeshIndia department of General Medicine Amma Multi-Speciality HospitalThorrurTelanganaIndia

dear Editor,Around a billion individuals worldwide have hypertension.Of these,95%have essential hypertension,a type of undiagnosed hypertension.1 The regulation of blood pressure(BP)involves numerous signaling pathways.Among them,the Renin Angiotensin System is well known.All these pathways are regulated by modulation of renal salt handling and tone of vascular smooth muscle(VSM)tissue.Any of these mechanisms can become faulty and alter the resistance arteries’VSM tone,which can elevate BP.However,since the exact origin of PH and its pathophysiology are unknown,less effective,and generic treatments are used.2 The fact that more than 50%of hypertension patients in the USA do not have their BP under good control serves as an illustration of this.Antihypertensive treatment resistance affects an additional 5 million people and is defined as the inability to regulate BP despite the use of at least three antihypertensive drugs in combination.

关键词： hypertension drugs treatment

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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)

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Organic stabilization in earthen plaster:Eco-compatible architecture and ancient techniques in Tata Somba homes

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Frontiers of Architectural Research 2024年第3期13卷 625-638页

作者： d.Ben Ghida department of Architecture University of Naples FedericoⅡNaplesItaly

The study of organic stabilization is crucial for understanding its impact on the durability and effectiveness of earthen plaster.Analyzing natural admixtures’effects on plaster properties provides insights that aid in optimizing plaster composition and application for desired characteristics.The addition of biopolymers,known to enhance plaster performance,necessitates further investigation to understand their role in earthen plaster stabilization.This study focuses on Tata Somba homes in Benin and Togo,recognized as UNESCO World Heritage sites.These unique architectural examples embody“architecture without architects”,relying solely on local traditional knowledge.The objective is to explore and revive Tata Somba’s ancient eco-technology for earth plaster stabilization.Research shows that biopolymers’combined stabilization and application techniques can improve earthen plaster performance.Seven promising bio-stabilizers were identified,suggesting their potential as sustainable,effective options for CO_(2) mitigation in buildings.These findings not only deepen our understanding of earthen architecture but also underscore the potential of merging traditional,eco-friendly building methods with modern scientific insights to create sustainable solutions for cultural heritage preservation and contemporary built environments.

关键词： Vernacular architecture Cultural heritage preservation Sustainable architecture Biopolymer Earth architecture Earth stabilization

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Global patterns and ecological drivers of taxonomic and phylogenetic endemism in angiosperm genera

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Plant diversity 2024年第2期46卷 149-157页

作者： Hong Qian Brent d.Mishler Jian Zhang Shenhua Qian Research and Collections Center Illinois State Museum1011 East Ash StreetSpringfieldIL 62703USA University and Jepson Herbaria Department of Integrative BiologyUniversity of CaliforniaBerkeleyCA 94720-2465USA Center for Global Change and Complex Ecosystems Zhejiang Tiantong Forest Ecosystem National Observation and Research StationSchool of Ecological and Environmental SciencesEast China Normal UniversityShanghai 200241China Shanghai Institute of Pollution Control and Ecological Security Shanghai 200092China Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment Ministry of EducationChongqing UniversityChongqing 400045China

Endemism of lineages lies at the core of understanding variation in community composition among geographic regions because it reflects how speciation,extinction,and dispersal have influenced current distributions.Here,we investigated geographic patterns and ecological drivers of taxonomic and phylogenetic endemism of angiosperm genera across the world.We identify centers of paleo-endemism and neo-endemism of angiosperm genera,and show that they are mostly located in the Southern Hemisphere in tropical and subtropical regions,particularly in Asia and Australia.different categories of phylogenetic endemism centers can be differentiated using current climate conditions.Current climate,historical climate change,and geographic variables together explained~80%of global variation in taxonomic and phylogenetic endemism,while 42-46%,1%,and 15%were independently explained by these three types of variables,respectively.Thus our findings show that past climate change,current climate,and geography act together in shaping endemism,which are consistent with the findings of previous studies that higher temperature and topographic heterogeneity promote endemism.Our study showed that many centers of phylogenetic endemism of angiosperms,including regions in Amazonia,Venezuela,and west-central tropical Africa that have not previously been identified as biodiversity hotspots,are missed by taxon-based measures of endemism,indicating the importance of including evolutionary history in biodiversity assessment.

关键词： Angiosperm Current climate Endemism Historical climate change Topographic heterogeneity

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