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On the Monotonicity of Q^(3) Spectral Element Method for Laplacian

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Annals of Applied Mathematics 2024年第2期40卷 161-190页

作者： Logan j.cross Xiangxiong Zhang Department of Mathematics Purdue University150 N.University StreetWest LafayetteIN 47907-2067USA

The monotonicity of discrete Laplacian, i.e., inverse positivity of stiffness matrix, implies discrete maximum principle, which is in general not true for high order accurate schemes on unstructured meshes. On the other hand,it is possible to construct high order accurate monotone schemes on structured meshes. All previously known high order accurate inverse positive schemes are or can be regarded as fourth order accurate finite difference schemes, which is either an M-matrix or a product of two M-matrices. For the Q3spectral element method for the two-dimensional Laplacian, we prove its stiffness matrix is a product of four M-matrices thus it is unconditionally monotone. Such a scheme can be regarded as a fifth order accurate finite difference scheme. Numerical tests suggest that the unconditional monotonicity of Q^(k) spectral element methods will be lost for k ≥ 9 in two dimensions, and for k ≥ 4 in three dimensions. In other words, for obtaining a high order monotone scheme, only Q^(2) and Q^(3) spectral element methods can be unconditionally monotone in three dimensions.

关键词： Inverse positivity discrete maximum principle high order accuracy monotonicity discrete Laplacian spectral element method

Numerical Simulation of the Tip Aerodynamics and Acoustics Test

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journal of Thermal Science 2016年第2期25卷 153-160页

作者： F Tejero E P Doerffer O Szulc j L cross The Szwalski Institute of Fluid-Flow Machinery Polish Academy of Sciences. Fiszera 14 80-231 Gdansk Poland NASA Ames Research Center (retired) Moffett Field CA USA

The application of an efficient flow control system on helicopter rotor blades may lead to improved aerodynamic performance. Recently, our invention of Rod Vortex Generators(RVGs) has been analyzed for helicopter rotor blades in hover with success. As a step forward, the study has been extended to forward flight conditions. For this reason, a validation of the numerical modelling for a reference helicopter rotor(without flow control) is needed. The article presents a study of the flow-field of the AH-1G helicopter rotor in low-, medium- and high-speed forward flight. The CFD code FLOWer from DLR has proven to be a suitable tool for the aerodynamic analysis of the two-bladed rotor without any artificial wake modelling. It solves the URANS equations with LEA(Linear Explicit Algebraic stress) k-ω model using the chimera overlapping grids technique. Validation of the numerical model uses comparison with the detailed flight test data gathered by cross j. L. and Watts M. E. during the Tip Aerodynamics and Acoustics Test(TAAT) conducted at NASA in 1981. Satisfactory agreements for all speed regimes and a presence of significant flow separation in high-speed forward flight suggest a possible benefit from the future implementation of RVGs. The numerical results based on the URANS approach are presented not only for a popular, low-speed case commonly used in rotorcraft community for CFD codes validation but preferably for medium- and high-speed test conditions that have not been published to date.

关键词： AH-1G TAAT helicopter rotor forward flight chimera overlapping grid

Dissociation cross sections ofψ(3770),ψ(4040),ψ(4160),andψ(4415)mesons with nucleons

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Communications in Theoretical Physics 2024年第4期76卷 93-112页

作者： Ruo-Qing Ding Xiao-Ming Xu H j Weber Department of Physics Shanghai UniversityBaoshanShanghai 200444China Department of Physics University of VirginiaCharlottesvilleVA 22904United States of America

We study the dissociation of ψ(3770), ψ(4040), ψ(4160), and ψ(4415) mesons in collision with nucleons, which takes place in high-energy proton-nucleus collisions. The quark interchange between a nucleon and a ■ meson leads to the dissociation of the ■ meson. We consider the reactions:■, and■, where R stands for ψ(3770), ψ(4040), ψ(4160), or ψ(4415). A reaction of a neutron and a ■ meson corresponds to a reaction of a proton and the ■ meson by replacing the up quark with the down quark and vice versa. Transition-amplitude formulas are derived from the S-matrix *** cross sections are calculated with the transition amplitudes for scattering in the prior form and in the post form. The cross sections relate to nodes in the radial wave functions of ψ(3770), ψ(4040), ψ(4160), and ψ(4415) mesons.

关键词： inelastic nucleon-charmonium scattering quark interchange relativistic constituent quark potential model

Stable diffusion gradients in microfluidic conduits bounded by fluid walls

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Microsystems & Nanoengineering 2024年第3期10卷 357-367页

作者： Federico Nebuloni Cyril Deroy Peter R.Cook Edmond j.Walsh Department of Engineering Science Osney Thermo-Fluids InstituteUniversity of OxfordOxford OX20ESUK Sir William Dunn School of Pathology University of OxfordOxford OX13REUK

Assays mimicking in vitro the concentration gradients triggering biological responses like those involved in fighting infections and blood clotting are essential for biomedical *** assays prove especially attractive as they allow precise control of gradient shape allied to a reduction in *** microfluidic devices are fabricated using solid plastics that prevent direct access to responding ***-walled microfluidics allows the manufacture of circuits on standard Petri dishes in seconds,coupled to simple operating methods;cell-culture medium sitting in a standard dish is confined to circuits by fluid walls made of an immiscible *** develop and experimentally validate an analytical model of diffusion between two or more aqueous streams flowing at different rates into a fluid-walled conduit with the cross-section of a circular *** solid walls,fluid walls morph during flows as pressures fall,with wall shape changing down the *** model is validated experimentally for Fourier numbers<0.1 using fluorescein diffusing between laminar *** enables a priori prediction of concentration gradients throughout a conduit,so allowing rapid circuit design as well as providing bioscientists with an accurate way of predicting local concentrations of bioactive molecules around responsive and nonresponsive cells.

关键词： walls diffusion attractive

Comparative analysis of microstructure,mechanical,and corrosion properties of biodegradable Mg-3Y alloy prepared by selective laser melting and spark plasma sintering

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journal of Magnesium and Alloys 2024年第4期12卷 1496-1510页

作者： P.Minárik M.Zemková S.Šašek j.Dittrich M.Knapek F.Lukáˇc D.Koutný j.jaroš R.Král Faculty of Mathematics and Physics Charles UniversityKe Karlovu 5Praha 12116Czech Republic Research Centre University ofŽilinaUniverzitná8215/1Žilina 01026Slovakia Institute of Plasma Physics of the Czech Academy of Sciences Za Slovankou 1782/318200 Praha 8Czech Republic Institute of Machine and Industrial Design Brno University of TechnologyTechnická2896/2Brno 61669Czech Republic

This work explored possibilities of biodegradable magnesium alloy Mg-3Y preparation by two modern powder metallurgy techniques–spark plasma sintering(SPS)and selective laser melting(SLM).The powder material was consolidated by both methods utilising optimised parameters,which led to very low porosity(∼0.3%)in the SLM material and unmeasurably low porosity in the SPS *** main aim of the study was the thorough microstructure characterisation and interrelation between the microstructure and the functional properties,such as mechanical strength,deformability,and corrosion *** materials showed comparable strength of∼110 MPa in tension and compression and relatively good deformability of∼9%and∼21%for the SLM and SPS materials,*** corrosion resistance of the SPS material in 0.1 M NaCl solution was superior to the SLM one and comparable to the conventional extruded *** digital image correlation during loading and the cross-section analysis of the corrosion layers revealed that the residual porosity and large strained grains have the dominant negative effect on the functional properties of the SLM *** the other hand,one of the primary outcomes of this study is that the SPS consolidation method is very effective in the preparation of the W3 biodegradable alloy,resulting in material with convenient mechanical and degradation properties that might find practical applications.

关键词： Magnesium Yttrium Powder metallurgy Microstructure Mechanical strength Corrosion resistance

n-Alkane bound biomarker fingerprints from asphaltenes in the bitumens of Eastern Dahomey Basin,Nigeria:Source and genetic implications

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Petroleum Research 2024年第1期9卷 85-91页

作者： Modupe A.Egbeola Olubunmi C.Adeigbe Olajide j.Adamolekun Department of Geology University of IbadanIbadanNigeria Structural Geology and Tectonics Institute of Applied GeosciencesKIT-Karlsruhe Institute of TechnologyAdenauerring 20a76131KarlsruheGermany

The asphaltene fractions of the bitumens of Eastern Dahomey Basin in Nigeria,were analyzed by flash pyrolysis-gas chromatography(Py-GC)method in order to unravel its geochemical history and *** distributions of the initial biomarkers of the original oils from the pyrolysates are related to the assessment of organic matter source,paleo-redox conditions and source environment during ***,it effectively establishes the genetic relationship of the *** n-alkane distributions in the pyrolysates reveal nC_(9)-nC_(32)n-alkanes,maximizing at nC_(14),isoprenoids-pristane(Pr)and phytane(Ph),and some n-alkene *** peaks of low to medium-weight nC_(9)-nC20 n-alkanes and low peaks of nC_(21)+n-alkanes characterize the *** reveal that abundant algal organic matter with some terrigenous inputs contributed to the source rock of the *** high concentration of marine organic matter inputs to the source rock is further confirmed by the nC_(17)/nC27 ratios which range from 5.39 to 19.82 and shows the predominance of nC_(17)*** general unimodal n-alkane distributions in the bitumens indicate derivation from similar organic matter types showing that they are genetically *** anoxic to suboxic environmental conditions that prevailed during the deposition of the sediments is revealed by the isoprenoids,Pr/Ph ratios(0.72-1.28).Pristane/nC_(17)and Phytane/nC_(18)range from 0.16 to 0.33 and 0.22 to 0.56,revealing that the bitumens were from predominantly marine organic matter(type II kerogen)preserved in a reducing environment with no evidence of ***,the Ph/nC_(18)ratio and the cross plot of Pr+Ph/nC_(17)+nC_(18)allow the classification of the bitumens into two subfamilies/groups(A and B).The bitumen samples have low wax content as indicated by the degree of waxiness ranging from 0.21 to 0.38 which confirms low terrigenous *** on the carbon preference index(CPI:0.92 to 1.55)and odd-even predo

关键词： Genetic relationship Flash pyrolysis Biomarker Asphaltene Pyrolysates

Association of daily sitting time and leisure-time physical activity with body fat among ***

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journal of Sport and Health Science 2024年第2期13卷 195-203页

作者： jingwen Liao Min Hu Kellie Imm Clifton j.Holmes jie Zhu Chao Cao Lin Yang Guangdong Provincial Key Laboratory of Physical Activity and Health Promotion Guangzhou Sport UniversityGuangzhou 510500China Scientific Research Center Guangzhou Sport UniversityGuangzhou 510500China Division of Epidemiology&Genetics Department of Population and Public Health SciencesKeck School of Medicine of the University of Southern CaliforniaLos AngelesCA 90033USA Program in Physical Therapy Washington University School of MedicineSt.LouisMO 63110USA Center for Human Nutrition Washington University School of MedicineSt.LouisMO 63110USA Department of Plastic and Reconstructive Surgery Shanghai East HospitalTongji UniversityShanghai 200070China Department of Cancer Epidemiology and Prevention Research Alberta Health ServicesCalgary T2S 3C3Canada Department of Oncology and Community Health Sciences University of CalgaryCalgary T2N 1N4Canada

Background:Prolonged sitting and reduced physical activity lead to low energy ***,little is known about the joint impact of daily sitting time and physical activity on body fat *** investigated the independent and joint associations of daily sitting time and physical activity with body fat among ***:This was a cross-sectional analysis of *** representative data from the National Health and Nutrition Examination Survey2011-2018 among adults aged 20 years or *** sitting time and leisure-time physical activity(LTPA)were self-reported using the Global Physical Activity *** fat(total and trunk fat percentage)was determined via dual X-ray ***:Among 10,808 adults,about 54.6%spent 6 h/day or more sitting;more than one-half reported no LTPA(inactive)or less than 150 min/week LTPA(insufficiently active)with only 43.3%reported 150 min/week or more LTPA(active)in the past *** fully adjusting for sociodemographic data,lifestyle behaviors,and chronic conditions,prolonged sitting time and low levels of LTPA were associated with higher total and trunk fat percentages in both *** stratifying by LTPA,the association between daily sitting time and body fat appeared to be stronger in those who were inactive/insuufficiently *** the joint analyses,inactive/insuufficiently active adults who reported sitting more than 8 h/day had the highest total(female:3.99%(95%confidence interval(95%CI):3.09%-4.88%);male:3.79%(95%CI:2.75%-4.82%))and trunk body fat percentages(female:4.21%(95%CI:3.09%-5.32%);male:4.07%(95%CI:2.95%-5.19%))when compared with those who were active and sitting less than 4 h/***:Prolonged daily sitting time was associated with increased body fat among *** higher body fat associated with 6 h/day sitting may not be offset by achieving recommended levels of physical activity.

关键词： Adults Body fat distribution Physical activity Sitting time

Muscle strength deficits are associated with low bone mineral density in young pediatric cancer survivors:The iBoneFIT project

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journal of Sport and Health Science 2024年第3期13卷 419-427页

作者： Andres Marmol-Perez jose j.Gil-Cosano Esther Ubago-Guisado Francisco j.Llorente-Cantarero juan Francisco Pascual-Gázquez Kirsten K.Ness Vicente Martinez-Vizcaino jonatan R.Ruiz Luis Gracia-Marco Department of Physical Education and Sports Faculty of Sport SciencesSport and Health University Research Institute(iMUDS)University of GranadaGranada 18011Spain Department of Epidemiology and Cancer Control St.Jude Children's Research HospitalMemphisTN 38105USA Department of Communication and Education Loyola University AndalusiaSeville 41704Spain Biosanitary Research Institute ibs.GranadaGranada 18012Spain Maimonides Biomedical Research Institute of Cordoba(IMIBIC) Cordoba 14004Spain CIBEROBN Biomedical Research Networking Center for Physiopathology of Obesity and NutritionCarlos III Health InstituteMadrid 28029Spain Department of Specific Didactics Faculty of EducationUniversity of CordobaCordoba 14071Spain Pediatric and adolescent hematology and oncology service Pediatrics and Pediatric Surgery Clinical Management UnitVirgen de las Nieves University HospitalGranada 18014Spain Health and Social Research Center Universidad de Castilla-La ManchaCuenca 13001Spain

Background Pediatric cancer survivors are at increased risk of muscle weakness and low areal bone mineral density(aBMD).However,the prevalence of muscle strength deficits is not well documented,and the associations of muscle strength with aBMD are unknown in this ***,this study aimed to investigate the prevalence of upper-and lower-body muscle strength deficits and to examine the associations of upper-and lower-body muscle strength with age-,sex,and race-specific aBMD Z-scores at the total body,total hip,femoral neck,and lumbar *** This cross-sectional study included 116 pediatric cancer survivors(12.1±3.3 years old,mean±SD;42.2%female).Upper-and lower-body muscle strength were assessed by handgrip and standing long jump test,***‑energy X‑ray absorptiometry was used to measure aBMD(g/cm2).Associations between muscle strength and aBMD were evaluated in multivariable linear regression *** regression was used to evaluate the contribution of muscle strength(1-decile lower)to the odds of having low aBMD(Z-score≤1.0).All analyses were adjusted for time from treatment completion,radiotherapy exposure,and body mass *** More than one-half of survivors were within the 2 lowest deciles for upper-(56.9%)and lower-body muscle strength(60.0%)in comparison to age-and sex-specific reference *** strength deficits were associated with lower aBMD Z-scores at all sites(B=0.133–0.258,p=0.001–0.032).Each 1-decile lower in upper-body muscle strength was associated with 30%–95%higher odds of having low aBMD Z-scores at all *** 1-decile lower in lower-body muscle strength was associated with 35%–70%higher odds of having low aBMD Z-scores at total body,total hip,and femoral *** Muscle strength deficits are prevalent in young pediatric cancer survivors,and such deficits are associated with lower aBMD Z-scores at all *** results suggest that interventions designed to improve muscle strength in t

关键词： Bone health Childhood cancer DXA Lean mass Resistance training

A Sharding Scheme Based on Graph Partitioning Algorithm for Public Blockchain

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 3311-3327页

作者： Shujiang Xu Ziye Wang Lianhai Wang Miodrag j.Mihaljevi′c Shuhui Zhang Wei Shao Qizheng Wang Key Laboratory of Computing Power Network and Information Security Ministry of EducationShandong Computer Science CenterQilu University of Technology(Shandong Academy of Sciences)Jinan250014China Shandong Provincial Key Laboratory of Computer Networks Shandong Fundamental Research Center for Computer ScienceJinan250014China Mathematical Institute The Serbian Academy of Sciences and ArtsBelgrade11000Serbia

Blockchain technology,with its attributes of decentralization,immutability,and traceability,has emerged as a powerful catalyst for enhancing traditional industries in terms of optimizing business ***,transaction performance and scalability has become the main challenges hindering the widespread adoption of *** to its inability to meet the demands of high-frequency trading,blockchain cannot be adopted in many *** improve the transaction capacity,researchers have proposed some on-chain scaling technologies,including lightning networks,directed acyclic graph technology,state channels,and shardingmechanisms,inwhich sharding emerges as a potential scaling ***,excessive cross-shard transactions and uneven shard workloads prevent the sharding mechanism from achieving the expected *** paper proposes a graphbased sharding scheme for public blockchain to efficiently balance the transaction *** crossshard transactions and evening-out workloads among shards,the scheme reduces transaction confirmation latency and enhances the transaction capacity of the ***,the scheme can achieve a high-frequency transaction as well as a better blockchain *** results show that the scheme effectively reduces the cross-shard transaction ratio to a range of 35%-56%and significantly decreases the transaction confirmation latency to 6 s in a blockchain with no more than 25 shards.

关键词： Blockchain sharding graph partitioning algorithm