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Modeling the Newtonian dynamics for rotation curve analysis of thin-disk galaxies

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Research in Astronomy and Astrophysics 2011年第12期11卷 1429-1448页

作者： James Q.feng c.f.Gallo Superconix Inc 2440 Lisbon AvenueLake ElmoMN 55042USA

We present an efficient, robust computational method for modeling the Newtonian dynamics for rotation curve analysis of thin-disk galaxies. With appropriate mathematical treatments, the apparent numerical difficulties associated with singularities in computing elliptic integrals are completely removed. Using a boundary element discretization procedure, the governing equations are transformed into a linear algebra matrix equation that can be solved by straightforward Gauss elimination in one step without further iterations. The numerical code implemented according to our algorithm can accurately determine the surface mass density distribution in a disk galaxy from a measured rotation curve （or vice versa）. for a disk galaxy with a typical flat rotation curve, our modeling results show that the surface mass density monotonically decreases from the galactic center toward the periphery, according to Newtonian dynamics. In a large portion of the galaxy, the surface mass density follows an approximately exponential law of decay with respect to the galactic radial coordinate. Yet the radial scale length for the surface mass density seems to be generally larger than that of the measured brightness distribution, suggesting an increasing mass-tolight ratio with the radial distance in a disk galaxy. In a nondimensionalized form, our mathematical system contains a dimensionless parameter which we call the ＂galactic rotation number＂ that represents the gross ratio of centrifugal force and gravitational force. The value of this galactic rotation number is determined as part of the numerial solution. Through a systematic computational analysis, we have illustrated that the galactic rotation number remains within 4-10% of 1.70 for a wide variety of rotation curves. This implies that the total mass in a disk galaxy is proportional to V02 Rg, with V0 denoting the characteristic rotation velocity （such as the ＂flat＂ value in a typical ro- tation curve） and Rg the radius of the galacti

关键词： galaxy: disk -- galaxies: general -- galaxies: kinematics and dynamics -- galaxies: structure -- methods: numerical and analytical

DYNAMIc cOMPAcTION Of PURE cOPPER POWDER USING PULSED MAGNETIc fORcE

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Acta Metallurgica Sinica(English Letters) 2007年第4期20卷 277-283页

作者： H.P. Yu c.f. Li National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of Technology Harbin 150001 China

The compaction of pure cu powder was carried out through a series of experiments using dynamic magnetic pulse compaction, and the effects of process parameters, such as discharge energy and compacting direction, on the homogeneity and the compaction density of compacted specimens were presented and discussed. The results indicated that the compaction density of specimens increased with the augment of discharge voltage and time. During unidirectional compaction, there was a density gradient along the loading direction in the compacted specimen, and the minimum compaction density was localized to the center of the bottom of the specimen. The larger the aspect ratio of a powder body, the higher the compaction density of the compacted specimen. And high conductivity drivers were beneficial to the increase of the compaction density. The iterative and the double direction compaction were efficient means to manufacture the homogeneous and high-density powder parts.

关键词： magnetic pulse compaction copper powder compaction density electromagnetic forming

A RANS-Vof Numerical Model to Analyze the Output Power of An OWc-WEc Equipped with Wells and Impulse Turbines in A Hypothetical Sea-State

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china Ocean Engineering 2020年第6期34卷 760-771页

作者： Paulo R.f.Teixeira Rafael A.A.c.Gonçalves Eric Didier Engineering School Universidade Federal do Rio Grande-FURGRio GrandeRS 96203-900Brazil Harbours and Maritime Structures Division Hydraulics and Environment DepartmentLaboratório Nacional de Engenharia Civil-LNECLisbon 1700-066Portugal

Wave energy is a renewable source with significant amount in relation to the global demand. A good concept of a device applied to extract this type of energy is the onshore oscillating water column wave energy converter(OWc-WEc). This study shows a numerical analysis of the diameter determination of two types of turbines, Wells and Impulse, installed in an onshore OWc device subjected to a hypothetical sea state. commercial software fLUENT?,which is based on RANS-Vof(Reynolds-Averaged Navier-Stokes equations and Volume of fluid technique), is employed. A methodology that imposes air pressure on the chamber, considering the air compressibility effect, is used. The mathematical domain consists of a 10 m deep flume with a 10 m long and 10 m wide OWc chamber at its end(geometry is similar to that of the Pico's plant installed in Azores islands, Portugal). On the top of the chamber, a turbine works with air exhalation and inhalation induced by the water free surface which oscillates due to the incident wave. The hypothetical sea state, represented by a group of regular waves with periods from 6 to 12 s and heights from 1.00 to 2.00 m(each wave with an occurrence frequency), is considered to show the potential of the presented methodology. Maximum efficiency(relation between the average output and incident wave powers) of46% was obtained by using a Wells turbine with the diameter of 2.25 m, whereas the efficiency was 44% by an Impulse turbine with the diameter of 1.70 m.

关键词： wave energy oscillating water column Wells turbine Impulse turbine RANS-Vof compressible air

Regularized quantile regression for SNP marker estimation of pig growth curves

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Journal of Animal Science and Biotechnology 2017年第4期8卷 824-832页

作者： L.M.A.Barroso M.Nascimento A.c.c.Nascimento1 f.f.Silva N.V.L.Serao c.D.cruz M.D.V.Resende f.L.Silva c.f.Azevedo P.S.Lopes S.E.f.Guimaraes Department of Statistics Federal University of Vicosa Av. P H Rolfs s/nUniversity Campus Vicosa MG 36570-000 Brazil Department of Animal Science Federal University of Vicosa Av. P H Rolfs s/n University CampusVicosa MG 36570-000 Brazil Department of Animal Science Iowa State University Kildee Hall 50011 Ames Iowa USA Department of General Biology Federal University of Vicosa Av. P H Rolfs s/n University CampusVicosa MG 36570-000 Brazil Embrapa forestry Estrada da Ribeira km 111Colombo PR Brazil. Department of Plant Science Federal University of Vicosa Av. P H Rolfs s/n University Campus Vicosa MG 36570-000 Brazil

Background: Genomic growth curves are general y defined only in terms of population mean; an alternative approach that has not yet been exploited in genomic analyses of growth curves is the Quantile Regression(QR). This methodology allows for the estimation of marker effects at different levels of the variable of interest. We aimed to propose and evaluate a regularized quantile regression for SNP marker effect estimation of pig growth curves, as well as to identify the chromosome regions of the most relevant markers and to estimate the genetic individual weight trajectory over time(genomic growth curve) under different quantiles(levels).Results: The regularized quantile regression(RQR) enabled the discovery, at different levels of interest(quantiles), of the most relevant markers al owing for the identification of QTL regions. We found the same relevant markers simultaneously affecting different growth curve parameters(mature weight and maturity rate): two(ALGA0096701 and ALGA0029483)for RQR(0.2), one(ALGA0096701) for RQR(0.5), and one(ALGA0003761) for RQR(0.8). Three average genomic growth curves were obtained and the behavior was explained by the curve in quantile 0.2, which differed from the ***: RQR allowed for the construction of genomic growth curves, which is the key to identifying and selecting the most desirable animals for breeding purposes. furthermore, the proposed model enabled us to find, at different levels of interest(quantiles), the most relevant markers for each trait(growth curve parameter estimates) and their respective chromosomal positions(identification of new QTL regions for growth curves in pigs). These markers can be exploited under the context of marker assisted selection while aiming to change the shape of pig growth curves.

关键词： Genome association Growth curve Pig QTL Regularized quantile regression

Nutritional therapy for active crohn’s disease

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World Journal of Gastroenterology 2008年第27期14卷 4420-4423页

作者： Paul A smith Specialist Registrar in Gastroenterology North Manchester General Hospital Gastroenterology Department Delaunays Road Crumpsall Manchester

Nutritional therapy for active crohn’s disease (cD) is an underutilised form of treatment in adult patients, though its use is common in the paediatric population. There is evidence that nutritional therapy can effectively induce remission of cD in adult patients. Enteral nutrition therapy is safe and generally well tolerated. Meta-analysis data suggest that corticosteroids are superior to nutritional treatment for induction of remission in active cD. However, the potential side effects of such pharmacotherapy must be taken into consideration. This review examines the evidence for the efficacy of elemental and polymeric diets, and the use of total parenteral nutrition in active cD.

关键词： crohn's disease Nutrition Dietary Treatment Steroids

Damage detection on framed structures: modal curvature evaluation using Stockwell Transform under seismic excitation

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Earthquake Engineering and Engineering Vibration 2015年第2期14卷 265-274页

作者： R.Ditommaso f.c.Ponzo G.Auletta Department of Structures Geotechnics Engineering Geology University of Basilicata School of Engineering University of Basilicata

The key parameters for damage detection and localization are eigenfrequencies, related equivalent viscous damping factors and mode shapes. The classical approach is based on the evaluation of these structural parameters before and after a seismic event, but by using a modern approach based on time-frequency transformations it is possible to quantify these parameters throughout the ground shaking phase. In particular with the use of the S-Transform, it is possible to follow the temporal evolution of the structural dynamics parameters before, during and after an earthquake. In this paper, a methodology for damage localization on framed structures subjected to strong motion earthquakes is proposed based on monitoring the modal curvature variation in the natural frequency of a structure. Two examples of application are described to illustrate the technique: computer simulation of the nonlinear response of a model, and several laboratory(shaking table) tests performed at the University of Basilicata(Italy). Damage detected using the proposed approach and damage revealed via visual inspections in the tests are compared.

关键词： damage detection S-transform band-variable fi lter

All-electron basis sets for H to Xe specific for ZORA calculations:Applications in atoms and molecules

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chinese Physics B 2024年第8期33卷 238-246页

作者： c.S.Gomes f.E.Jorge A.canal Neto Departamento de fisica Universidade Federal do Espirito Santo29075-910 VitoriaESBrazil Departamento de fisica Instituto de Ciencias Exatas e BiologicasUniversidade Federal de Ouro Preto Campus Universitario Morro do Cruzeiro35402-136 Ouro PretoMGBrazil

A segmented basis set of quadruple zeta valence quality plus polarization functions(QZP)for H through Xe was developed to be used in conjunction with the ZORA *** set was augmented with diffuse functions to describe electrons farther away from the nuclei *** the ZORA-ccSD(T)/QZP-ZORA theoretical model,atomic ionization energies and bond lengths,harmonic vibrational frequencies,and atomization energies of some molecules were *** addition of core-valence corrections has been shown to improve the agreement between theoretical and experimental results for molecular *** atomization energies,a similar observation emerges when considering spin-orbit *** the augmented QZP-ZORA set,static mean dipole polarizabilities of a set of atoms were calculated and compared with previously published recommended and experimental *** evaluations of the ZORA and Douglas–Kroll–Hess Hamiltonians were made for each property studied.

关键词： QZP-ZORA and AQZP-ZORA basis sets elements from H to Xe ccSD(T)method atomic and molecular properties

Solid state crack repair by friction stir processing in 304L stainless steel

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Journal of Materials Science & Technology 2018年第1期34卷 140-147页

作者： c.Gunter M.P.Miles f.c.Liu T.W Nelson Manufacturing Engineering Technology Brigham Young University Department of Mechanical Engineering Brigham Young University

friction stir processing （fSP） was investigated as a method of repairing cracks in 12 mm thick 304L stainless steel plate. Healing feasibility was demonstrated by processing a tapered crack using a PcBN/W- Re tool with a 25 mm diameter shoulder and a pin length of 6.4 mm. The experiment showed that it was possible to heal a crack that begins narrow and then progressively grows up to a width of 2 mm. Bead on plate experiments were used to find the best parameters for creating a consolidated stir zone with the least amount of hardness difference compared to the base metal. Grain refinement in some specimens resulted in much higher stir zone hardness, compared to base metal, A plot of grain size versus microhardness showed a very strong inverse correlation between grain size and hardness, as expected from the Hall- Perch relationship. corrosion testing was carried out in order to evaluate the effect of fSP on potential sensitization of the stir zone. After 1000 h of intermittent immersion in 3.5% saline solution at room temperature it was found that no corrosion products formed on the base material controls or on any of the friction stir processed specimens.

关键词： Stainless steel crack healing friction stir processing corrosion resistance

Unusual f_(3)stacking fault in magnesium

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Journal of Magnesium and Alloys 2023年第7期11卷 2404-2428页

作者： Y.Yue S.L.Yang c.c.Wu J.f.Nie Department of Materials Science and Engineering Monash UniversityVictoria 3800Australia

An unusual f_(3)basal stacking fault resulting from twin-dislocation interaction in magnesium is observed in molecular dynamics *** f_(3)fault is produced in the twin lattice from the interaction between a migrating(1012)twin boundary and a partial dislocation of either a prismaticc>edge,or a prismaticc+a>mixed dislocation in the *** condition is that the partial dislocation needs to have a negative sign and lie on a plane intersecting a compression site of the twin *** f_(3)fault can also be generated when a positive basalmixed dislocation in the twin lattice,with slip plane intersecting a compression site of the twin boundary,interacts with a basal-prismatic twinning *** f_(3)fault comprises two I_(1) faults that have the same character but are separated by two basal *** has one end connected to the twin boundary,and the other end bounded by a lattice defect with a Burgers vector identical to that of a 30°Shockley partial *** formation frequency of the f_(3)fault is higher at a lower shear stress(below∼400 MPa)and/or a lower temperature(100 K and 200 K).The f_(3)fault can decompose into a glissile 30°Shockley and a T_(2) fault at a temperature above∼400 *** relationships between the f_(3)fault and other types of basal stacking faults such as I_(2),T_(2) or paired I_(1) faults that are separated by multiple basal layers are discussed.

关键词： Magnesium Basal stacking fault f3 fault Twin-dislocation interactions