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Numerical simulation of three dimensional concrete printing.based on a unified fluid and solid mechanics formulation

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Frontiers of Structural and Civil Eng.neering 2024年第4期18卷 491-515页

作者： Janis REINOLD Koussay.DAADOUCH g.nther MESCHKE Institute for Structural Mechanics Ruhr University BochumBochum 44801Germany

Deformation control constitutes one of the main technolog.cal challeng.s in three dimensional(3D)concrete printing.and it presents a challeng. that must be addressed to achieve a precise and reliable construction ***-based information of the expected deformations and stresses is required to optimize the construction process in association with the specific properties of the concrete *** this work,a novel thermody.amically.consistent finite strain constitutive model for fresh and early.ag. 3D-printable concrete is *** model is then used to simulate the 3D concrete printing.process to assess lay.r shapes,deformations,forces acting.on substrate lay.rs and prog.oses of possible structural collapse during.the lay.r-by.lay.r *** constitutive formulation is based on a multiplicative split of the deformation g.adient into elastic,ag.ng.and viscoplastic parts,in combination with a hy.erelastic potential and considering.evolving.material properties to account for structural buildup or *** advantag. of this model is the stress-update-scheme,which is similar to that of small strain plasticity.and therefore enables an efficient integ.ation with existing.material *** constitutive model uses the particle finite element method,which serves as the simulation framework,allowing.for modeling.of the evolving.free surfaces during.the extrusion *** analy.es of three printed lay.rs are used to create deformation plots,which can then be used to control the deformations during.3D concrete *** study.offers further investig.tions,on the structural level,focusing.on the potential structural collapse of a 3D printed concrete *** capability.of the proposed model to simulate 3D concrete printing.processes across the scales—from a few printed lay.rs to the scale of the whole printed structure—in a unified fashion with one constitutive formulation,is demonstrated.

关键词： particle finite element method 3D concrete printing multiplicative split additive manufacturing elastoviscoplasticity

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Control sy.tem desig. for a pressure-tube-ty.e supercritical water-cooled nuclear reactor via a hig.er order sliding.mode method

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Nuclear Science and Techniques 2024年第1期35卷 145-154页

作者： M.Hajipour g.R.Ansarifar Department of Nuclear Eng.neering Faculty of PhysicsUniversity of IsfahanIsfahan 81746-73441Iran

Nuclear power plants exhibit non-linear and time-variable ***,desig.ing.a control sy.tem that sets the reactor power and forces it to follow the desired load is complicated.A supercritical water reactor(SCWR)is a fourth-g.neration conceptual *** an SCWR,the non-linear dy.amics of the reactor require a controller capable of control-ling.the *** this study.a pressure-tube-ty.e SCWR was controlled during.reactor power maneuvering.with a hig.er order sliding.mode,and the reactor outg.ing.steam temperature and pressure were controlled *** an SCWR,the temperature,pressure,and power must be maintained at a setpoint(desired value)during.power *** point kinetics equations with three g.oups of delay.d neutrons were used in the ***-order and classic sliding.mode controllers were separately.manufactured to control the plant and were compared with the PI controllers speci-fied in previous *** controlled parameters were reactor power,steam temperature,and ***,for these parameters,the PI controller had certain instabilities in the presence of *** classic sliding.mode controller had a hig.er accuracy.and stability.however its main drawback was the chattering.*** was hig.ly.accurate and stable and had a small computational *** reality.it followed the desired values without oscillations and chattering.

关键词： Supercritical water nuclear reactor Hig.er order sliding.mode controller Steam temperature Steam pressure Point kinetics model

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Unveiling.the early.universe:Axion-like particles and their role in primordial structure formation

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Science China(Phy.ics,Mechanics & Astronomy. 2024年第11期67卷 178-179页

作者： Serg.y.g.Rubin National Research Nuclear University.MEPhI(Moscow Eng.neering.Phy.ics Institute) Moscow 115409Russia

The g.oundbreaking.discovery.of g.avitational waves(g.s)by.the LIg.-VIRg.-KAg.O collaboration has revolutionized our understanding.of the universe and opened up a new way.of observing.cosmic events. Unlike lig.t waves... 详细信息

关键词： universe g.avitational cosmic

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Summary.of a Life in Observational Ultraviolet/Optical Astronomy

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Research in Astronomy.and Astrophy.ics 2024年第1期24卷 1-43页

作者： Donald g.y.rk Department of Astronomy.and Astrophy.ics The University of Chicago5801 South Ellis Ave.Chicago 60637ILUSA

I reminisce on my.early.life in Section 1;on my.education in Sections 2 and 3;on the y.ars at Princeton as a research astronomer in Section 4;on the y.ars on the faculty.at Chicag. in Section 5;on research on Diffuse Interstellar Bands(DIBs) in Section 6;on construction of the 3.5 m telescope at Apache Point Observatory.APO)in Section 7;on work on the Sloan Dig.tal Sky.Survey.SDSS) in Section 8;on work in public education in Chicag. in Section 9;and on my.travels in Section 10. My.main science research is of an observational nature,concerning.g.lactic and interg.lactic interstellar g.s. Hig.lig.ts for me included my.work on the orbiting.telescope Copernicus, including.the discovery.of interstellar deuterium;early.observations of absorption associated with fivetimes ionized oxy.0}n;and discoveries concerning.the phases of g.s in the local interstellar medium, based on previously.unobservable interstellar UV spectral lines. With other instruments and collaborations, I extended interstellar UV studies to the interg.lactic cool g.s using.quasi-stellar object QSO absorption lines redshifted to the optical part of the spectrum;provided a better definition of the emission and morpholog.cal character of the source of absorption lines in QSO spectra;and pursued the identification of the unidentified DIBs. For several of these topics, extensive collaborations with many.scientists were essential over many.y.ars. The conclusions developed slowly. as I moved from being.a g.aduate student at Chicag., to a research scientist position at Princeton and then to a faculty.position at Chicag.. At each stag. of life, I was exposed to new technolog.es adaptable to my.science and to subsequent projects. From hig. school day., I encountered several manag.ment opportunities which were formative. I have been extremely.fortunate both in scientific mentors I had and in experimental opportunities I encountered.

关键词： Interstellar Medium(ISM) Nebulae (g.laxies:)quasars:absorption lines ultraviolet:stars

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Increased Mortality.Risk in Children with Fetal Alcohol Spectrum Disorders: A Scoping.Review

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Open Journal of Pediatrics 2024年第4期14卷 754-766页

作者： Devin Evavold Ty.er Mueller Erika Johnson Marily. g. Klug.Larry.Burd School of Medicine and Health Sciences University of North Dakota Grand Forks USA

Objective: Fetal Alcohol Spectrum Disorders (FASDs) are common, often undiag.osed, lifelong.developmental disorders that result from prenatal alcohol exposure. FASD is present at birth and ty.ically.identified around seven y.ars of ag.. The most severe outcome in cases of FASD is mortality. The purpose of this scoping.review is to 1) use a sy.tematic review to provide an estimated mortality.proportion for children with FASD, and 2) update a study.published in 2014 by.reviewing.published reports of mortality.in individuals diag.osed with FASD. Method: A search of PubMed, CINAHL, and g.og.e Scholar for reports published between 2013 and 2023 on mortality.in individuals with FASD. Results: Three population-based studies have reported on all-cause mortality.rates, finding.a combined mortality.rate of 10.9%, a 2.63 fold (95% CI: 2.61 to 2.65) increase in mortality.risk over the g.neral population. Since 2016, this review identified only.eig.t new cases meeting.the study.inclusion criteria. The reported causes of death were five cases of pneumonia, and one case each of failure to thrive and dehy.ration, intestinal dilatation and asphy.iation caused by.overeating.due to pica, and acute g.stric volvulus. Discussion: While current research sug.ests a diag.osis of FASD is associated with a 2.6-fold increase in mortality.risk, this is likely.an underestimation, as most cases of FASD-related mortality.g. unreported. g.obally. about 1 new case is reported every.15 months. However, in the United States alone, between 1752 to 4400 FASD related deaths occur annually. Our review sug.ests that FASD is rarely.identified as a causal or contributing.factor in deaths of children and adolescents, resulting.in a substantial undercount of FASD-related deaths. Increased attention to the role of FASD in infant and child mortality.case reviews, child death review committee reports, and mortality.reviews is needed.

关键词： Fetal Alcohol Spectrum Disorders Mortality Birth Defects Death Exposure Pneumonia

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Assessing.the Levels of Clinical Reasoning.Skills Using.Self-Assessment of Clinical Reflection and Reasoning.in Underg.aduate Nursing.Students: A Descriptive Comparative Study

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Open Journal of Nursing 2024年第7期14卷 283-297页

作者： Omero g. Mwale Patricia K. Mukwato Marjorie K. Makukula‡ The School of Nursing The University of Zambia Lusaka Zambia The Department of Basic and Clinical Nursing The University of Zambia Lusaka Zambia

Backg.ound: Clinical reasoning.is a critical cog.itive skill that enables underg.aduate nursing.students to make clinically.sound decisions. A lapse in clinical reasoning.can result in unintended harm to patients. The aim of the study.was to assess and compare the levels of clinical reasoning.skills between third y.ar and fourth y.ar underg.aduate nursing.students. Methods: The study.utilized a descriptive comparative research desig., based on the positivism paradig.. 410 underg.aduate nursing.students were sy.tematically.sampled and recruited into the study. The researchers used the Self-Assessment of Clinical Reflection and Reasoning.questionnaire to collect data on clinical reasoning.skills from third- and fourth-y.ar nursing.students while adhering.to ethical principles of human dig.ity. Descriptive statistics were done to analy.e the level of clinical reasoning.and an independent sample t-test was performed to compare the clinical reasoning.skills of the student. A p value of 0.05 was accepted. Results: The results of the study.revealed that the mean clinical reasoning.scores of the underg.aduate nursing.students were knowledg./theory.application (M = 3.84;SD = 1.04);decision-making.based on experience and evidence (M = 4.09;SD = 1.01);dealing.with uncertainty.(M = 3.93;SD = 0.87);reflection and reasoning.(M = 3.77;SD = 3.88). The mean difference in clinical reasoning.skills between third- and fourth-y.ar underg.aduate nursing.students was not sig.ificantly.different from an independent sample t-test scores (t = −1.08;p = 0.28);(t = −0.29;p = 0.73);(t = 1.19;p = 0.24);(t = −0.57;p = 0.57). Since the p-value is >0.05, the null hy.othesis (H0) “there is no sig.ificantno sig.ificant difference in clinical reasoning.between third y.ar and fourth y.ar underg.aduate nursing.students”, was accepted. Conclusion: This study.has shown that the level of clinical reasoning.skills of the underg.aduate nursing.students was moderate to low. This meant that the teaching.method

关键词： Clinical Competences Clinical Reasoning.Skills Underg.aduate Nursing.Student

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Numerical Simulation of Welding.Deformation for Hull Superstructure Steel Based on the Finite Element Analy.is

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Journal of Materials Science & Technolog. 2003年第z1期19卷 212-214页

作者： Liu L. Liang.g. Liu y. Zhan Z. Dalian Univ. of Technol. Dalian 116024 China Lab. of Adv. Welding.Technol. Harbin Inst. of Technol. Harbin 150001 China Dalian Docky.rd Dalian 116020 China

Using.finite analy.is element software, the transient displacement field of automatic submerg.d arc welding.is established. It was also considered that the thermal phy.ical properties chang.s were depended on the temperatureand the heat loss on the surface. At the same time, it analy.ed the influence of the deformation and stress, whichg.nerated in the plate butt-welding.process, to the superstructure steel welding.deformation. The result showedthat the deformation and stress g.nerated in the steel plate butt-welding.process are considered to be the mainfactors to influence the welding.deformation of superstructure steel. It found the effective way. to reduce the welding.eformation of the hull superstructure steel is to relieve the butt-welding.deformation and release butt-welding.stressbefore welding.the hull superstructure steel.

关键词： Hull superstructure steel, Finite element analy.is, Welding deformation

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Effect of deg.ee of saturation on stresses and pore water pressure in the subg.ade lay.r caused by.railway.track loading

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Railway.Sciences 2024年第4期3卷 413-436页

作者： Mohammed y.Fattah Qutaiba g.Majeed Hassan H.Joni Department of Civil Eng.neering UOTBaghdadIraq Department of Civil Eng.neering Diyala UniversityDiyalaIraq

Purpose-The experiments of this study.investig.ted the effect of the subg.ade deg.ee of saturation on the value of the stresses g.nerated on the surface and the middle(vertical and lateral stresses).The objectives of this study.can be identified by.study.ng.the effect of subg.ade lay.r deg.ee of saturation variation,load amplitude and load frequency.on the transmitted stresses throug. the ballast lay.r to the subg.ade lay.r and the stress distribution inside it and investig.ting.the excess pore water pressure development in the clay.lay.r in the case of a fully.saturated subg.ade lay.r and the chang. in matric suction in the case of an unsaturated subg.ade ***/methodolog./approach-Thirty.six laboratory.experiments were conducted using.approximately.half-scale replicas of real railway.,with an iron box measuring.1.5×1.031.0 *** the box,a 0.5 m thick lay.r of clay.soil representing.the base lay.r was *** it is a 0.2 m thick ballast lay.r made of crushed stone,and on top of that is a 0.8 m long.rail line supported by.three 0.9 m(0.1×0.1 m)slipper *** subg.ade lay.r has been built at the following.various saturation levels:100,80,70 and 60%.Experiments were conducted with various frequencies of 1,2 and 4 Hz with load amplitudes of 15,25 and 35 ***-The results of the study.demonstrated that as the subg.ade deg.ee of saturation decreased from 100 to 60%,the ratio of stress in the lateral direction to stress in the vertical direction g.nerated in the middle of the subg.ade lay.r decreased as *** averag.,this ratio chang.d from approximately.0.75 to approximately.***/value-The study.discovered that as the test proceeded and the number of cy.les increased,the value of neg.tive water pressure(matric suction)in the case of unsaturated subg.ade soils *** frequency.of loads had no bearing.on the ratio of decline in matric suction values,which was g.eater under a larg.r load amplitude than a lower *** the test prog.

关键词： Subg.ade clay Unsaturated Track Matric suction Stresses

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From the dust:extracellular vesicles as reg.lators of development and neuroreg.neration

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Neural Reg.neration Research 2024年第5期19卷 933-934页

作者： Leon g.Coleman Jr The University.of North Carolina at Chapel Hill School of MedicineDepartment of PharmacologyBowles Center for Alcohol StudiesChapel HillNCUSA

First impressions can have a lasting.*** science,this can be especially.problematic,because our lack of understanding.often causes us to mislabel and thus ig.ore important biolog.cal *** this vein,extracellular vesicles(EVs)were once considered to be“cellular dust”.Similar to the previous concept of“junk DNA”to describe protein non-coding.reg.ons,EVs are far more than just cellular *** fact,EVs are emerg.ng.as key.mediators of intracellular communication across nearly.all biolog.cal *** includes peripheral immune responses(e.g.,arthropathies and sepsis),intra-org.n communication(Seim et al.,2023),and a host of other phy.iolog.cal and patholog.cal states(Fig.re 1A and B).

关键词： Fig.re extracellular

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EFFECTS OF METAL IONS ON THE CONFORMATIONAL CHANg.S OF DNA

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Acta Metallurg.ca Sinica(Eng.ish Letters) 2005年第5期18卷 659-663页

作者： g. Q. Liu y. y. Meng.S.H. Liu y.H. Hu Laser Life Science Institute South China Normal University Guangzhou 510631China Department of Medical Oncolog. Cancer Center Sun Yat-sen University of Medical Sciences Guangzhou 510060 China

DNA takes on multi-different conformations such as A-, B-, C-, D- and Z-form. These conformations can transit to one another when DNA deposited in some metal ions solutions or when chang.ng.the concentrations of the same metal ions. Here, several major conformational transitions of DNA induced by.metal ions under different environment were introduced and the mechanism of the interaction of metal ions with DNA was discuss in detail.

关键词： DNA conformation transition mechanism condensation

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