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

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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 *** this paper,the elastic performance of a novel slab trackform for high-speed railways is investigated using three-dimensional finite element modelling in *** is then compared to the performance of a ballasted ***,slab and ballasted track models are developed to replicate the full-scale testing of track *** the models are calibrated with the experimental results,the novel slab model is developed and compared against the calibrated slab track *** 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 *** 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 *** train loading methods are discussed,and the most practical approach is retained and ***,correlations are made between the geotechnical parameters of modern high-speed rail and conventional *** 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

Stability analysis of a time-delayed Van der pol–Helmholtz–Duffing oscillator in fractal space with a non-perturbative approach

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Communications in Theoretical physics 2024年第4期76卷 22-31页

作者： Yusry o El-Dib Department of Mathematics Faculty of EducationAin Shams UniversityRoxyCairoEgypt

The time-delayed fractal Van der pol–Helmholtz–Duffing(VpHD)oscillator is the subject of this paper,which explores its mechanisms and highlights its stability *** time-delayed technologies are currently garnering significant attention,the focus of this research remains crucially relevant.A non-perturbative approach is employed to refine and set the stage for the system under *** innovative methodologies introduced yield an equivalent linear differential equation,mirroring the inherent nonlinearities of the ***,the incorporation of quadratic nonlinearity into the frequency formula represents a cutting-edge *** analytical solution's validity is corroborated using a numerical *** conditions are ascertained through the residual Galerkin ***,it is observed that the delay parameter,in the context of the fractal system,reverses its stabilizing influence,impacting both the amplitude of delayed velocity and the *** analytical solution's precision is underscored by its close alignment with numerical ***,the study reveals that fractal characteristics emulate damping *** its applicability across diverse nonlinear dynamical systems,this non-perturbative approach emerges as a promising avenue for future research.

关键词： Van der pol-Helmholtz-Duffing oscillator fractal space time-delay non-perturbative approach stability analysis El-Dib's frequency formula

Sensing nanoscale electromagnetic forces when the heat is on

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National Science Review 2024年第7期11卷 64-65页

作者： Eric o.potma Department of Chemistry University of California

In scanning probe microscopy(SpM),a sharp tip scans across a sample to produce an image with nanometer-scale resolution or better. SpM contrast is derived from the physical interplay between the tip and the sample. A special class of SpM techniques measures forces when the tip–sample junction is illuminated by an external light source. photo-induced forces can be sensitive to the optical properties of the sample, thus enabling nanoscale imaging with spectroscopic,material-specific contrast.

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optimization of bio-oil production parameters from the pyrolysis of elephant grass (pennisetum purpureum) using response surface methodology

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Clean Energy 2024年第5期8卷 241-251页

作者： Sunday C.Ikpeseni Samuel o.Sada Ufuoma J.Efetobor Henry o.orugba Mathias Ekpu Hilary I.owamah Jeremiah L.Chukwuneke Solomon oyebisi Uche p.onochie Department of Mechanical Engineering Delta State UniversityP.M.B.1AbrakaNigeria Department of Mechanical Engineering Delta State PolytechnicP.M.B.3Otefe-OgharaNigeria Department of Chemical Engineering Delta State UniversityP.M.B.1AbrakaNigeria Department of Civil Engineering Delta State UniversityP.M.B.1AbrakaNigeria Department of Mechanical Engineering Nnamdi Azikiwe UniversityP.M.B.2025AwkaNigeria Department of Civil Engineering Covenant UniversityP.M.B.1023OttaNigeria Department of Civil Engineering The University of the South PacificP.M.B.9072SuvaFiji Department of Mechanical Engineering Delta State University of Science and TechnologyP.M.B.5OzoroNigeria

The need to increase bio-oil yield from biomass and enhance its fuel properties has driven research into optimizing the pyrolysis *** study investigated the influence of three key process parameters—temperature,heating rate,and nitrogen flow rate—on the pyrolysis of elephant grass(pennisetum purpureum)in a fixed-bed *** surface methodology was used to study the im-pact of the aforementioned variables on bio-oil yield to improve its production *** analysis of the biomass revealed 79.24 wt%volatile matter,14.22 wt%fixed carbon,and 5.86%ash,with ultimate analysis showing 45.44%carbon,5.59%hydrogen,and 40.95%*** high volatile matter content and favourable carbon and hydrogen percentages indicate that elephant grass is a vi-able energy source due to its potential for high bio-oil yield and energy *** resulting bio-oil exhibited a higher heating value of 20.9 MJ/kg,indicating its suitability for various heating applications.A second-order regression model was developed for bio-oil yield,with optimal conditions identified as a temperature of 550°C,a heating rate of 17°C/min,and a nitrogen flow rate of 6 ml/*** study achieved an optimal bio-oil yield of 59.03 wt%,and the model’s high R²value of 0.8683 from analysis of variance analysis confirmed its predictive *** research highlights elephant grass as a sustainable feedstock for bio-oil production,offering valuable insights into optimizing pyrolysis conditions to enhance bio-oil yield,thus advancing biofuel technology.

关键词： renewable energy biomass sustainable feedstock regression model fixed-bed reactor

髋关节镜手术:无症状和有症状病人术后MR关节成像异常表现的发生率

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国际医学放射学杂志 2017年第4期 474-474页

作者： C.H.o.Kim T.J.Dietrich p.o.zingg C.Dora C.W.A.pfirrmann R.Sutter 刘学焕 Department of Radiology Orthopedic University Hospital Balgrist

摘要目的确定并比较髋关节镜手术后无症状和有症状病人异常影像表现的发生率。材料与方法本研究由机构伦理委员会批准。所有病人均签署知情同意书。34例(17例无症状和17例有症状)因股骨髋臼撞击综合征行关节镜手术治疗1年后的病人行1.5 ...

摘要目的确定并比较髋关节镜手术后无症状和有症状病人异常影像表现的发生率。材料与方法本研究由机构伦理委员会批准。所有病人均签署知情同意书。34例(17例无症状和17例有症状)因股骨髋臼撞击综合征行关节镜手术治疗1年后的病人行1.5 T MR髋关节成像检查。2名阅片者独立分析所有MR关节成像异常影像表现,包括股骨颈处关节囊粘连、髋臼唇旁沟闭锁、髋臼唇缺损和几个解剖位置

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RBC aggregation,deformation and adhesion to endothelium:Role of nitric oxide derived from L-Arginine and sodium nitroprusside

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Journal of Innovative optical Health Sciences 2024年第5期17卷 53-65页

作者： M.K.Maksimov p.B.Ermolinskiy o.N.Scheglovitova N.N.Sklyankina A.V.Muravyov A.E.Lugovtsov A.V.priezzhev Faculty of physics M.V.Lomonosov Moscow State University bld.1subbuilding.2Leninskie goryMoscow 11991Russia N.F.Gamaleya National Research Center for Epidemiology and Microbiology 18 Gamaleya StreetMoscow 123098Russia K.D.Ushinsky Yaroslavl State pedagogical University 108/1 Respublikanskaya StreetYaroslavl 150000Russia

Red blood cells(RBCs)are the most abundant human blood *** aggregation and deformation strongly determine blood viscosity which impacts hemorheology and *** turn,RBC properties depend on di®erent endogenous and exogenous *** such factor is nitric oxide(No),which is mainly produced by endothelial cells(EC)from L-arginine amino acid in the circulatory *** the mechanisms of the RBC-endothelium interplay are not clear up to date and considering its possible clinical importance,the aims of this study are to investigate in vitro:(1)The e®ect of L-arginine induced No on RBC aggregation and adhesion to endothelium;(2)the No e®ect on RBC aggregation and deformation induced by L-arginine and sodium nitroprusside without the presence of endothelium in the *** RBC aggregation and adhesion to a monolayer of EC were studied using optical tweezers(oT).The RBC deformability and aggregation without endothelium in the samples were studied using the°ow chamber method and Myrenne *** con¯rmed that No increases deformability and decreases aggregation of *** showed that the soluble guanylate cyclase pathway appears to be the only No signaling pathway *** the samples with the endothelium,the\bell-shaped"dependence of RBC aggregation force on L-arginine concentration was observed,which improves our knowledge about the process of No production by ***,data related to L-arginine accumulation by endothelium were obtained:Necessity of the presence of extracellular L-arginine stated by other authors was put under *** our study,No decreased the RBC-endothelium adhesion,however,the tendency appeared to be weak and was not con¯rmed in another set of *** our knowledge,this is the¯rst attempt to measure the forces of RBC adhesion to endothelium monolayer with oT.

关键词： Red blood cells aggregation L-arginine endothelium optical tweezers Myrenne flow chamber

Making topological protein links using enzymatic reactions

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National Science Review 2024年第3期11卷 50-51页

作者： Roger Castells-Graells Todd o.Yeates Department of Chemistry and Biochemistry University of California UCLA-DoE Institute for Genomics and proteomics

proteins are exceedingly complex molecules though, at their heart, they are essentially linear polymers. pull at their ends and one obtains an extended backbone. While that is true in most cases, some natural proteins... 详细信息

关键词： DESIGN

Characterizing objective and self-report habitual physical activity and sedentary time in outpatients with an acquired brain injury

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Sports Medicine and Health Science 2024年第4期6卷 338-343页

作者： Liam p.pellerine Katerina Miller Ryan J.Frayne Myles W.o'Brien Division of Kinesiology School of Health and Human PerformanceFaculty of HealthDalhousie UniversityHalifaxNova ScotiaCanada Acquired Brain Injury NeuroCommons Nova Scotia Health AuthorityHalifaxNova ScotiaCanada School of physiotherapy(Faculty of Health)&Department of Medicine(Faculty of Medicine) Dalhousie UniversityHalifaxNova ScotiaCanada Geriatric Medicine Research Dalhousie University&Nova Scotia HealthHalifaxNova ScotiaCanada Centre de Formation Medicale Du Nouveau-Brunswick New Brunswick&Department of MedicineUniversite de SherbrookeSherbrookeQuebecCanada

outpatients with an acquired brain injury(ABI)experience physical,mental,and social *** can be classified into two subgroups based on mechanism of injury:mild traumatic brain injury(mTBI;e.g.,concussion)and other ABI(e.g.,stroke,brain aneurysm,encephalitis).our understanding of habitual activity levels within ABI populations is limited because they are often collected using self-report *** purpose of this study was to,1)describe the habitual activity levels of outpatients with ABI using objective and self-report monitoring,and 2)compare the activity levels of outpatients with mTBI *** *** outpatients with other ABI(mean±standard deviation:[58±13]years,9 females)and 12 outpatients with mTBI([48±11]years,9 females)wore a thigh-worn activpAL 24 h/day(h/day)for *** with ABI averaged(6.0±2.3)h/day of upright time,(10.6±2.2)h/day of sedentary time,(5.6±2.7)h/day in prolonged sedentary bouts>1 h,(5960±3037)steps/day,and(11±13)minutes/day(min/day)of moderate-vigorous physical activity(MVpA).There were no differences between activpAL-derived upright,sedentary,prolonged sedentary time,and physical activity between the mTBI and other ABI groups(all,p>0.31).outpatients with ABI overestimated their MVpA levels(t138 min/week)and underestimated sedentary time(-4.3 h/day)compared to self-report(all,ppite self-reporting high activity levels,outpatients with ABI objectively exhibit highly inactive and sedentary *** habitual movement behaviours of our sample did not differ by mechanism of injury(i.e.,mTBI versus other ABI).Targeting reductions in objectively measured sedentary time are needed to progressively improve the habitual movement behaviours of outpatients with ABI.

关键词： Accelerometry Stroke Brain aneurysm Encephalitis Mild traumatic brain injury Rehabilitation

A synthetic microbial community used as a bioinoculant can overcome rice production constraints in acid soils

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Science China(Life Sciences) 2024年第5期67卷 1085-1086页

作者： Maureen o’Callaghan Shengjing Shi Resilient Agriculture Group AgResearchLincolnChristcurch 8140New Zealand

A customised synthetic microbial community(SynCom)composed of carefully selected rhizosphere-competent bacterial strains improved rice growth,yield and resistance to soil acidity and Al toxicity.

关键词： soil soils rhizosphere