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Mean-Square Approximation of Navier-Stokes Equations with Additive Noise in vorticity-velocity Formulation

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Numerical Mathematics(Theory,Methods and Applications) 2021年第1期14卷 1-30页

作者： g.N.Milstein M.v.Tretyakov Ural Federal University EkaterinburgRussia School of Mathematical Sciences University of NottinghamNottinghamUK

We consider a time discretization of incompressible Navier-Stokes equations with spatial periodic boundary conditions and additive noise in the vorticity-velocity *** approximation is based on freezing the velocity on time subintervals resulting in a linear stochastic parabolic equation for *** each time step,the velocity is expressed via vorticity using a formula corresponding to the Biot-Savart-type *** prove the first mean-square convergence order of the vorticity approximation.

关键词： Navier-Stokes equations vorticity numerical method stochastic partial differential equations mean-square convergence

Advancement in utilization of magnetic resonance imaging and biomarkers in the understanding of schizophrenia

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World Journal of Clinical Cases 2025年第1期13卷 11-15页

作者： Aidan K Tirpack Danyaal g Buttar Mandeep Kaur Department of Psychiatry Campbell University School of Osteopathic MedicineBuies CreekNC 27506United States Department of Psychiatry and Behavioral Health Mercyhealth Hospital and Trauma CenterJanesvilleWI 53548United States

Historically,psychiatric diagnoses have been made based on patient’s reported symptoms applying the criteria from diagnostic and statistical manual of mental *** utilization of neuroimaging or biomarkers to make the diagnosis and manage psychiatric disorders remains a distant *** have been several studies that examine brain imaging in psychiatric disorders,but more work is needed to elucidate the complexities of the human *** this editorial,we examine two articles by Xu et al and Stoyanov et al,that show developments in the direction of using neuroimaging to examine the brains of people with schizo-phrenia and *** et al used magnetic resonance imaging to examine the brain structure of patients with schizophrenia,in addition to examining neurotransmitter levels as *** et al used functional magnetic resonance imaging to look at modulation of different neural circuits by diagnostic-specific scales in patients with schizophrenia and *** two studies provide crucial evidence in advancing our understanding of the brain in prevalent psychiatric disorders.

关键词： Schizophrenia Magnetic resonance imaging Biomarkers Neurotransmitters Psychiatric disorders

Electron-beam Treatment of Tungsten-free TiC/NiCr Cermet Ⅰ:Influence of Subsurface Layer Microstructure on Resistance to Wear during Cutting of Metals

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Journal of Materials Science & Technology 2005年第3期21卷 427-429页

作者： v.E.Ovcharenko BaohaiYU S.g.Psakhie InstituteofStrengthPhysicsandMaterialsScience SiberiaBranchRussianAcademyofSciences2/1AcademicheskyPr.Tomsk634021Russia InstituteofMetalResearch ChineseAcademyofSciences72WenhuaRoadShenyang110016China

An experimental investigation were performed on the effect of the impulse electron-beam irradiation upon microstruc-ture of the surface layer and on wear resistance of a cutting tool for sintered TiC/NiCr cermet. The results showed that the surface electron-beam treatment of the TiC/NiCr cermet is an efficient method for investigating the mi-crostructure and phase composition in the surface layer of the powder composite and there are optimal regimes of electron-beam treatment, which ensure a substantial increase in the resistance of the cermet to wear during cutting of metals.

关键词： Cermet TiC/NiCr Electron-beam treatment Microstructure Wear resistance

Understanding the mechanisms of friction stir welding based on computer simulation using particles

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Defence Technology（防务技术） 2018年第6期14卷 643-656页

作者： A.Yu.Smolin E.v.Shilko S.v.Astafurov E.A.Kolubaev.g.M.Eremina S.g.Psakhie Institute of Strength Physics and Materials Science SB RAS Tomsk634055Russia Tomsk State University Tomsk634050Russia Skolkovo Institute of Science and Technology Skolkovo143025Russia

Friction stir welding(FSW) is a novel technique for joining different materials without melting. In FSW the welded components are joined by stirring the plasticized material of the welded edges with a special rotating pin plunged into the material and moving along the joint line. From the scientific point of view,the key role of the FSW processes belongs to formation of the special plasticized conditions and activation of physical mechanisms of mixing the materials in such conditions to produce the strong homogeneous weld. But it is still a lack of complete understanding of what are these conditions and *** paper is devoted to understanding the mechanisms of material mixing in conditions of FSW based on a computer simulation using particles. The movable cellular automaton method(MCA), which is a representative of the particle methods in mechanics of materials, was used to perform all ***, material flow including material stirring in FSW is simulated using computational fluid mechanics or smoothed particle hydrodynamics, which assume that the material is a continuum and does not take into account the material structure. MCA considers a material as an ensemble of bonded particles. Breaking of inter-particle bonds and formation of new bonds enables simulation of crack nucleation and healing, as well as mass mixing and *** paper consists of two main parts. In the first part, the simulations in 2 D statements are performed to study the dynamics of friction stir welding of duralumin plates and influence of different welding regimes on the features of the material stirring and temperature distribution in the forming welded joints. It is shown that the ratio of the rotational speed to the advancing velocity of the tool has a dramatic effect on the joint quality. A suitable choice of these parameters combined with additional ultrasonic impact could considerably reduce the number of pores and microcracks in the weld without significa

关键词： Friction stir welding Plastic flow Deformation mechanisms Simulation Particle method

Electron-beam Treatment of Tungsten-free TiC/NiCr CermetⅡ: Structural Transformations in the Subsurface Layer

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Journal of Materials Science & Technology 2006年第4期22卷 511-513页

作者： Baohai YU v.E.Ovcharenko S.g.Psakhie O.v.Lapshin Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Institute of Strength Physics and Materials Science Siberia Branch Russian Academy of Sciences Russia

The character of structural changes in the surface layer of titanium carbide （TiC） with Ni-Cr alloy binder was investigated theoretically and experimentally after electron-beam treatment of the material surface. The thermal influence of the electron-beam irradiation on the surface layer microstructure of the composite fine-grained material was mathematically analyzed. Quantitative estimations of the depth of the zone in microstructural phase transformations were carried out. The microstructure and concentration profile of Ti distribution in the metallic binder over the cross section of the surface layer with microstructural phase transformations after electron-pulse treatment of the hard metal surface were experimentally investigated.

关键词： Cermets TiC/NiCr Electron-beam treatment Structural transformation

Low-temperature green synthesis of boron carbide using aloe vera

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Chinese Physics B 2018年第10期27卷 578-583页

作者： H v SarithaDevi M S Swapna g Ambadas S Sankararaman Department of Optoelectronics and Department of Nanoscience and Nanotechnology University of Kerala Kariavattom Thiruvananthapuram-695581 Kerala India government victoria College Palakkad Kerala India

The unique structural and physical properties of boron carbide, which make it suitable for a wide range of applications,demands the development of low-cost and green synthesis method. In the present work, the commonly available leaves of aloe vera are hydrothermally treated to form the carbon precursor for the synthesis of boron carbide. The morphological characterization reveals the porous nature of the precursor turning into a tubular structure upon boron carbide *** structural characterization by x-ray diffraction and other spectroscopic techniques such as Fourier transform infrared,Raman, photoluminescence and uv-visible near-infrared spectroscopy confirm the formation of boron carbide. The thermogravimetric analysis of the sample is found to exhibit good thermal stability above 500 °C. When the sample is annealed to 600 °C, boron carbide with phase purity is obtained, which is confirmed through XRD and FTIR analyses. The optical emission properties of the sample are studied through CIE plot and power spectrum. Compared with other natural precursors for boron carbide, the aloe vera is found to give a good yield above 50%.

关键词： aloe vera boric acid boron carbide hydrothermal method

Lanthanide NIR luminescence for telecommunications, bioanalyses and solar energy conversion

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Journal of Rare Earths 2010年第6期28卷 824-842页

作者： Jean-Claude g. Bünzli Svetlana v. Eliseeva cole Polytechnique Fédérale de Lausanne Institute of Chemical Sciences and Engineering WCU Professor Korea University Center for Next Generation Photovoltaic Systems Katholieke Universiteit Leuven Department of Chemistry Laboratory of Coordination Chemistry

Present-day advanced technologies heavily rely on the exciting magnetic and spectroscopic properties of lanthanide ions. In particular, their ability to generate well-characterized and intense near-infrared (NIR) luminescence is exploited in any modern fiber-optic telecommunication network. In this feature article, we first summarize the whereabouts underlying the design of highly luminescent NIR molecular edifices and materials. We then focus on describing the main trends in three applications related to this spectral range: telecommunications, biosciences, and solar energy conversion. In telecommunications, efforts concentrate presently on getting easily processable polymer-based wav.g.ide amplifiers. Upconversion nanophosphors emitting in the visible after NIR excitation are now ubiquitous in many bioanalyses while their application to bio-imaging is still in its early stages; however, highly sensitive NIR-NIR systems start to be at hand for both in vitro and in vivo imaging, as well as dual probes combining magnetic resonance and optical imaging. Finally, both silicon-based and dye-sensitized solar cells benefit from the downconversion and upconversion capabilities of lanthanide ions to harvest Uv and NIR solar light and to boost the overall quantum efficiency of these next-generation devices.

关键词： lanthanide luminescence near-infrared luminescence telecommunications bioanalysis solar energy conversion solar cell upconversion downconversion

Influences of diffusion bonding process parameters on bond characteristics of Mg-Cu dissimilar joints

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Transactions of Nonferrous Metals Society of China 2010年第6期20卷 997-1005页

作者： g. MAHENDRAN v. BALASUBR AMANIAN T. SENTHILvELAN Department of Mechanical Engineering V.R.S. College of Engineering and Technology Centre for Materials Joining & Research (CEMAJOR) Department of Manufacturing Engineering Annamalai University Department of Mechanical Engineering Pondicherry Engineering College

In many circumstances,dissimilar metals have to be bonded together and the resulting joint interfaces must typically sustain mechanical and/or electrical forces without failure,which is not possible by fusion welding *** melting points of magnesium(Mg)and copper(Cu)have a significant difference(nearly 400℃)and this may lead to a large difference in the microstructure and joint performance of Mg-Cu ***,diffusion bonding can be used to join these alloys without much *** work analyses the effect of parameters on diffusion layer thickness,hardness and strength of magnesium-copper dissimilar *** experiments were conducted using three-factor,five-level,central composite rotatable design *** relationships were developed to predict diffusion layer thickness,hardness and strength using response surface *** is found that bonding temperature has predominant effect on bond *** fabricated at a bonding temperature of 450℃, bonding pressure of 12 MPa and bonding time of 30 min exhibited maximum shear strength and bonding strength of 66 and 81 MPa, respectively.

关键词： diffusion bonding magnesium alloy copper alloy shear strength bonding strength diffusion layer thickness interface hardness

Relation between Mass and Radius of Exoplanets Distinguished by their Density

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Research in Astronomy and Astrophysics 2023年第6期23卷 47-55页

作者： Alberto S.Betzler Joség.v.Miranda Centro de Ciência e Tecnologia em Energia e Sustentabilidade Universidade Federal do Recôncavo da BahiaFeira de SantanaBahia44.085-132Brazil Instituto de Fisica Universidade Federal da BahiaSalvadorBahia40.170-115Brazil

The formation of the solar system has been studied since the 18th century and received a boost in 1995 with the discovery of the first exoplanet,51 Pegasi *** investigations increased the number of confirmed planets to about5400 to *** possible internal structure and composition of these planets can be inferred from the relationship between planet mass and radius,*** have analyzed the M-R relation of a selected sample of iron-rock and ice-gas planets using a fractal approach to their *** application of fractal theory is particularly useful to define the physical meaning of the proportionality constant and the exponent in an empirical M-R power law in exoplanets,but this does not necessarily mean that they have an internal fractal *** M-R relations based on this sample are M=(1.46±0.08)R^(2.6±0.2)for the rocky population(3.6≤ρ≤14.3 g cm^(-3)),with 1.5≤M≤39M_(⊕),and M=(0.27±0.04)R^(2.7±0.2)for ice-gas planets(0.3≤ρ≤2.1 g cm^(-3))with 5.1≤M≤639 M_(⊕)(or■2 M_(J))and orbital periods greater than 10 *** M-R relations have in their density range a great predictive power for the determination of the mass of exoplanets and even for the largest icy moons of the solar *** average fractal dimension of these planets is D=2.6±0.1,indicating that these objects likely have a similar degree of heterogeneity in their densities and a nearly similar composition in each *** M-R diagram shows a"gap"between ice-gas and iron-rock *** gap is a direct consequence of the density range of these two *** empirically propose an upper mass limit of about 100 M_(⊕),so that an M-R relation for ice-gas planets in a narrow density range is defined by M∝R^(3).

关键词： planets and satellites:formation planets and satellites:terrestrial planets planets and satellites:gaseous planets