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Characterization and source apportionment of volatile organic compounds in hong Kong:A 5-year study for three different archetypical sites

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Journal of Environmental Sciences 2025年第5期151卷 424-440页

作者： Yuchen Mai Vincent Cheung Peter K.K.Louie Kenneth Leung Jimmy C.h.Fung Alexis K.h.Lau donald R.B.lake Dasa Gu Division of Environment and Sustainability The Hong Kong University of Science and TechnologyHong Kong 999077China Environmental Protection Department Hong Kong 999077China Environment and Ecology Bureau Hong Kong 999077China Department of Chemistry University of CaliforniaIrvine 92617USA

Initial success has been achieved in hong Kong in controlling primary air pollutants,but ambient ozone levels kept increasing during the past three *** organic compounds(VOCs)are important for mitigating ozone pollution as its major *** study analyzed VOC characteristics of roadside,suburban,and rural sites in hong Kong to investigate their compositions,concentrations,and source *** showthat the TVOC concentrations were 23.05±13.24,12.68±15.36,and 5.16±5.48 ppbv for roadside,suburban,and rural sites between May 2015 to June 2019,*** using Positive Matrix Factorization(PMF)model,six sources were identified at the roadside site over five years:Liquefied petroleum gas(LPG)usage(33%–46%),gasoline evaporation(8%–31%),aged air mass(11%–28%),gasoline exhaust(5%–16%),diesel exhaust(2%–16%)and fuel filling(75–9%).Similarly,six sources were distinguished at the suburban site,including LPG usage(30%–33%),solvent usage(20%–26%),diesel exhaust(14%–26%),gasoline evaporation(8%–16%),aged air mass(4%–11%),and biogenic emissions(2%–5%).At the rural site,four sources were identified,including aged airmass(33%–51%),solvent usage(25%–30%),vehicular emissions(11%–28%),and biogenic emissions(6%–12%).The analysis further revealed that fuel filling and LPG usage were the primary contributors to OFP and Oh reactivity at the roadside site,while solvent usage and biogenic emissions accounted for almost half of OFP and Oh reactivity at the suburban and rural sites,*** findings highlight the importance of identifying and characterizing VOC sources at different sites to help policymakers develop targeted measures for pollution mitigation in specific areas.

关键词： Volatile organic compounds Positive matrix factorization Source apportionment Ozone formation

Dark Future for Dark Matter

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Journal of Modern Physics 2020年第10期11卷 1589-1597页

作者： donald h. eckhardt José Luis Garrido Pestañ a Canterbury NH USA Departamento de Física Universidad de Jaén Campus Las Lagunillas Jaén Espa&ntilde a

The prevailing cosmological constant and cold dark matter (ΛCDM) cosmic concordance model accounts for the radial expansion of the universe after the Big Bang. The model appears to be authoritative because it is based on the Einstein gravitational field equation. however, a thorough scrutiny of the underlying theory calls into question the suitability of the field equation, which states that the Einstein tensor Gμv is a constant multiple of the stress-energy tensor Tμv when they both are evaluated at the same 4D space-time point: hite-space:normal;">Gμv = 8πkhite-space:normal;">Tμv, where k is the gravitational constant. Notwithstanding its venerable provenance, this equation is incorrect unless the cosmic pressure is p = 0;but then all that remains of the Einstein equation is the Poisson equation which models the Newtonian gravity field. This shortcoming is not resolved by adding the cosmological constant term to the field equation, hite-space:normal;">Gμv +Λ hite-space:normal;">gμv =hite-space:normal;">8πkhite-space:normal;">Thite-space:normal;">hite-space:nowrap;">μv

关键词： Classical General Relativity General Relativity and Gravitation: Fundamental Problems and General Formalism Fundamental Aspects of Astrophysics Relativity and Gravitation Dark Energy Mathematical and Relativistic Aspects of Cosmology

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

Parameterizations of the Daytime Friction Velocity, Temperature Scale, and Upslope Flow over Gently Inclined Terrain in Calm Synoptic Conditions

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Advances in Atmospheric Sciences 2009年第3期26卷 577-584页

作者：张占海周明煜 Sharon ZhONG donald h. LENSChOW Qing WANG Key Laboratory for Polar Science Polar Research Institute of ChinaShanghai 200136 State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 Department of Geography Michigan State University East LansingMI 48824-111USA National Center for Atmospheric Research BoulderCO 80307USA Department of Meteorology Naval Postgraduate SchoolMontereyCA 93943USA

A set of new parameterizations for the friction velocity and temperature scale over gently sloped terrain and in calm synoptic conditions are theoretically derived. The friction velocity is found to be proportional to the product of the square root of the total accumulated heating in the boundary layer and the sinusoidal function of the slope angle, while the temperature scale is proportional to the product of the boundary layer depth, the sinusoidal function of the slope angle and the potential temperature gradient in the free atmosphere. Using the new friction velocity parameterization, together with a parameterization of eddy diffusivity and an initial potential temperature profile around sunrise, an improved parameterization for the thermally induced upslope flow profile is derived by solving the Prandtl equations. The upslope flow profile is found to be simply proportional to the friction velocity.

关键词： friction velocity temperature scale slope terrain flux-profile relationship upslope 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