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Applied Mathematics and Mechanics(English Edition) 2009年第6期30卷 765-770页

作者： donald o. Besong Department of Numerical Analysis and Computer Science (NADA) Royal Institute of TechnologyS-10044 StockholmSweden

The main purpose of this work is to show that the gravity term of the segregation-mixing equation of fine mono-disperse particles in a fluid can be derived from first-principles （i.e., elementary physics）. our derivation of the gravity-driven flux of particles leads to the simplest case of the Richardson and Zaki correlation. Stokes velocity also naturally appears from the physical parameters of the particles and fluid by means of derivation only. This derivation from first-principle physics has never been presented before. It is applicable in small concentrations of fine particles.

关键词： gravity segregation Kynch batch flux first-principles derivation Burger-type equation

A Lognormal Distribution of Metal Resources

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地球科学（中国地质大学学报） 2011年第2期36卷 201-208页

作者： donald A. Singer U.S. Geological Survey 345 Middlefield Road Menlo Park California 94025 USA

For national or global resource estimation of frequencies of metals,a lognormal distribution has commonly been recommended but not adequately *** of frequencies of Cu,Zn,Pb,Ag,and Au contents of 1 984 well-explored mineral deposits display a poor fit to the lognormal *** the same metals plus Mo,Co,Nb2o3,and REE2o3 are grouped into 19 geologically defined deposit types,only eight of the 73 tests fail to be fit by lognormal distribution,and most of those failures are in two deposit types suggesting a problem with those *** of the mean and standard deviation of each of the metals in each of the deposit types are provided for modeling.

关键词：地质矿石矿产资源地球科学

How Deep Learning Networks could be Designed to Locate Mineral Deposits

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Journal of Earth Science 2021年第2期32卷 288-292页

作者： donald A.Singer 10191 N.Blaney Ave. Cupertino 95014CA USA

Whether using a shallow neural network with one hidden layer,or a deep network with many hidden layers,the training data must represent subgroups of the deposit type being explored to be *** examples of neural networks have mostly been limited to one individual mineral deposit for *** of geologic features among deposits within a type are so large that a single deposit cannot provide proper information to train a neural net to generalize and guide exploration for other *** trained with only one deposit tend to be academic successes but are not of practical value in exploration for other *** is why it takes much experience examining many deposits to properly train an economic geologist—a neural network is not any *** examples of shallow neural networks are used to demonstrate the power of neural networks to possibly locate undiscovered deposits and to provide some suggestions of how to deal with missing *** training data needs to include information spatially related to known deposits and hopefully information from many different deposits of the *** learned from these and other examples point to a proposed sampling plan for data that could lead to a generalized neural network for *** this plan,10 or more well-explored gold-rich porphyry copper deposits from around the world with 100 or more sample sites near and some distance from each deposit would probably capture important variability among such deposits and provide proper data to train and test a shallow neural network to predict locations of undiscovered deposits.

关键词： porphyry copper training neural networks missing observations

Lateral distributions of streamwise velocity in compound channels with partially vegetated floodplains

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Science China(Technological Sciences) 2009年第11期52卷 3357-3362页

作者： KNIGHT donald W School of Civil Engineering The University of Birmingham Birmingham B15 2TT UK

Natural rivers are commonly characterized by a main channel for primary flow conveyance and a floodplain, often partially covered with vegetation such as shrubs or trees, to carry extra flow during floods. The hydraulic resistance due to vegetation on the floodplain typically causes a further reduction of flow velocity and increases the velocity difference between the main channel and the floodplain. As a consequence a strong lateral shear layer leads to the exchange of mass and momentum between the main channel and floodplain, which in turn affects the overall channel conveyance and certain fluvial processes. The prediction of the lateral velocity distribution is important for many flood alleviation schemes, as well as for studies on sediment transport and dispersion in such channels. The present paper proposes a method for predicting the depth-averaged velocity in compound channels with partially vegetated floodplains, based on an analytical solution to the depth-integrated Reynolds-Averaged Navier-Stokes equation with a term included to account for the effects of vegetation. The vegetation is modelled via an additional term in the momentum equation to account for the additional drag force. The method includes the effects of bed friction, drag force, lateral turbulence and secondary flows, via four coefficients f, CD, λ & Γ respectively. The predicted lateral distributions of depth-averaged velocity agree well with the experimental data. The analytical solutions can also be used to predict the distribution of boundary shear stresses, which adds additional weight to the method proposed.

关键词： vegetation compound channel floodplain velocity

Sediment Transport in Rivers with overbank Flow

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四川大学学报（工程科学版） 2005年第S1期37卷 16-29页

作者： donald W KNIGHT Water Eng. The Univ.of BirminghamUK

Some concepts related to sediment transport in rivers with overbank flow are *** a description of the physical processes that are involved when a river inundates its floodplains,some simple com- putational methods are presented which permit the depth-averaged velocity and boundary shear stress to be pre- dicted within a cross section of variable,but prismatic *** methoda account for the strong transverse shear in velocity that occurs when the stage is just above bankfull,as well as ...

关键词： sediment transport overbank flow

A numerical implementation of the length-scale independent phase field method

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Acta Mechanica Sinica 2021年第1期37卷 92-104,I0003页

作者： Wenlong Zhang Ala Tabiei donald French Department of Civil Engineering University of CincinnatiCincinnatiOH45220USA Department of Mathematics University of CincinnatiCincinnatiOH45220USA

The phase field method for fracture integrates the Griffith theory and damage mechanics approach to predict crack initiation and propagation within one *** replaced the discrete representation of crack by diffusive damage and solved it based on a minimization of the global energy storage *** a result,no crack tracking topology is needed,and complex crack shapes can be captures without user ***,it is also reported to have an inconsistency between the predicted fracture toughness and the material ***,a novel energetic degradation function was proposed in literature to handle this *** research does some further modifications to the global energy storage functional so that Newton's method can be directly used to solve the energy *** the new energy form,direct implementation of the length-scale independent phase field method into finite element packages like LS-DYNA becomes *** paper presents the framework and details of implementing the length-scale independent phase field method into LS-DYNA through a user-defined element and material *** numerical examples are presented to compare with the experiment crack *** importantly,this paper is one of the first ones to quantitatively predict accurate force response compared to *** examples verify the accuracy of the new energy form and implementation.

关键词： Phase field method Length-scale independency Newton’s method LS-DYNA

Species longevity in North American fossil mammals

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Integrative Zoology 2014年第4期9卷 383-393页

作者： donald R.PRoTHERo Department of Vertebrate Paleontology Natural History Museum of Los Angeles CountyLos AngelesCAUSA

Species longevity in the fossil record is related to many paleoecological variables and is important to macroevolutionary studies,yet there are very few reliable data on average species durations in Cenozoic fossil *** of the online databases(such as the Paleobiology Database)use only genera of North American Cenozoic mammals and there are severe problems because key groups(***,oreodonts,pronghorns and proboscideans)have no reliable updated taxonomy,with many invalid genera and species and/or many undescribed genera and *** of the published datasets yield species duration estimates of approximately 2.3-4.3 Myr for larger mammals,with small mammals tending to have shorter species *** own compilation of all the valid species durations in families with updated taxonomy(39 families,containing 431 genera and 998 species,averaging 2.3 species per genus)yields a mean duration of 3.21 Myr for larger *** breaks down to 4.10-4.39 Myr for artiodactyls,3.14-3.31 Myr for perissodactyls and 2.63-2.95 Myr for carnivorous mammals(carnivorans plus creodonts).These averages are based on a much larger,more robust dataset than most previous estimates,so they should be more reliable for any studies that need species longevity to be accurately estimated.

关键词： Cenozoic genus mammals North America species

Adsorption of As on hydroxy-Fe-montmorillonite complexes

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Science China Earth Sciences 2005年第12期48卷 2155-2165页

作者： donald G. Fraser Department of Earth Sciences Oxford University Parks Road Oxford OX1 3PR UK

Arsenate has high affinity for soluble hydroxy-Fe species and Fe-oxyhydroxide pre-cipitates. In addition, the hydrolysis of Fe(III) and the growth of the initially precipitated Fe(III) phases are strongly influenced by the presence of montmorillonite. In this paper, the adsorption of As onto various hydroxy-Fe-montmorillonite (H-F-M) complexes was studied. Three systems of samples were prepared by mixing montmorillonite, hydroxy-Fe and arsenate in different se-quences: (1) Prior mixing of montmorillonite and hydroxy-Fe before the addition of arsenate; (2) prior mixing of hydroxy-Fe and arsenate before the addition of montmorillonite; and (3) prior mixing of montmorillonite and arsenate before the addition of hydroxy-Fe. For each system, the effects of pH, ionic strength, temperature, initial Fe and As concentrations and adsorption dura-tion on the overall uptake of As by H-F-M complexes were studied. Results showed that the up-take of As increased with increasing pH, temperature, initial Fe concentration and adsorption duration, and decreased with increasing ionic strength and initial As concentration to different extents for the three systems. The variation of the As uptake of H-F-M complexes with pH in the range of study is opposite to that reported previously for Fe-o-H systems in the absence of montmorillonite and similar to that reported for montmorillonite in the absence of hydroxy-Fe. The marked influence of ionic strength on the As uptake of H-F-M complexes indicates that outer-sphere complexation plays an important role. This is quite different from the adsorption of As on the surface of either Fe-oxyhydroxides or montmorillonite alone in which inner-sphere complexation dominates. Under all experimental conditions, the H-F-M complexes studied dis-played a very strong affinity for As, among which system 2 had the highest As adsorption capac-ity and system 1 the lowest. The authors attribute this to the differences in mixing sequence which resulted in more hy

关键词： hydroxy-Fe, montmorillonite, complex, arsenate adsorption.

Engel Subalgebras of n-Lie Algebras

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Acta Mathematica Sinica,English Series 2008年第1期24卷 159-166页

作者： donald W.BARNES 1 Little Wonga Rd

Engel subalgebras of finite-dimensional n-Lie algebras are shown to have similar properties to those of Lie algebras. Using these, it is shown that an n-Lie algebra, all of whose maximal subalgebras are ideals, is nilpotent. A primitive 2-soluble n-Lie algebra is shown to split over its minimal ideal, and all the complements to its minimal ideal are conjugate. A subalgebra is shown to be a Cartan subalgebra if and only if it is minimal Engel, provided that the field has sufficiently many elements. Cartan subalgebras are shown to have a property analogous to intravariance.

关键词： n-Lie algebras soluble nilpotent Engel subalgebras