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Open Journal of Civil Engineering 2024年第3期14卷 374-390页

作者： lloyd Ndlovu Zaid Mustafa Department of Civil and Environmental Engineering Jackson State University Jackson MS USA

This paper investigates particle transportation using a numerical model application approach to understand the final fate of suspended sediment particle masses due to a dredging operation in a navigational harbor inlet using PTM (Particle Tracking Model). The investigation applied PTM and simulated particle transportation at a navigational harbor called St Jerome Creek Inlet in Chesapeake Bay in Maryland. The United States Army Corps of Engineers (USACE), Maryland District, designed jetties for the inlet, which, when constructed, would minimize dredging requirements from once in a two-year period to once in a ten-year period. In the meantime, due to the frequent dredging requirements of the inlet, there exists a need to understand the fate of the suspended sediments from the dredging operations to assess the environmental impact on the aquatic environment and the coastal community. This study used PTM to simulate the transportation of sediments in a 30-day period during a dredging operation. Ten sediment source locations were selected as possible sites from which dredged materials could be introduced into the flow system. The model output was analyzed to draw conclusions. Results showed that most suspended sediment particle masses moved from their initial site locations and settled along the shoreline, whilst the sediments that found their way out of the inlet system towards the ocean migrated southward and settled approximately 6 miles at the tip of the mainland. The objective of the study is to track sediment particles from a dredging operation. This would be significant in tracking possible contaminants in an aquatic environment for future environmental management decisions.

关键词： PTM Suspended Sediments Dredging Particle Tracking

Fragipan Horizon Changes Using Annual Ryegrass and Other Admendments

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Open Journal of Soil Science 2024年第6期14卷 388-397页

作者： lloyd Murdock Anastasios Karathanasis Dottie Call Dana L. Dinnes Amitava Chatterjee Department of Plant & Soil Science University of Kentucky Lexington KY USA USDA-ARS National Laboratory for Agriculture and the Environment University Bldg Ames IA USA

A greenhouse experiment was conducted involving intact fragipan soil cores of 50 cm thickness after removing the topsoil horizons. The cores were maintained in moist condition throughout the experiment and received several treatments with various amendments for different periods ranging from 9 to 17 months. The amendments included annual ryegrass or Festulolium residues, powder limestone and various humate compounds alone or in combination with the grass residues. The results suggested a significant effect of ryegrass and Festulolium in reducing penetration resistance into the top 10 cm of the fragipan within 9 - 17 months, particularly when used in combination with certain humate materials such as Leonardite. Apparently, this is the result of the release of certain soluble organic compounds from the plant residues or the humate amendments that increase the solubility of Si and Al associated with the fragipan brittleness, thus decreasing the density of the compacted fragipan material.

关键词： Fragipan Fragipan Horizon Fragipan Soils Changing the Fragipan Annual Ryegrass Changes Fragipan Festulolium Changes Fragipan Amendments That Change the Fragipan

坦桑尼亚梅拉尼坦桑石矿床地质特征及成因模式

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世界地质 2024年第3期43卷 353-362页

作者：孙国锋张明云闫红圃张猛张伟杰 lloyd Shawarira 河南省地质研究院郑州450001 河南省第二地质勘查院有限公司郑州450046 中金国检珠宝玉石质量检验中心有限公司广东深圳518020 津巴布韦地质调查局津巴布韦哈拉雷ZW192201

通过野外实地矿区地质填图,对坦桑尼亚梅拉尼坦桑石矿床的地质背景及矿区矿床地质特征进行详细描述,尤其对矿体及矿物宝石学特征进行了剖析和综述,探讨了宝石成因模式。认为坦桑石形成于约5亿年前的泛非运动,仅产于新元古代莫桑比克变... 详细信息

通过野外实地矿区地质填图,对坦桑尼亚梅拉尼坦桑石矿床的地质背景及矿区矿床地质特征进行详细描述,尤其对矿体及矿物宝石学特征进行了剖析和综述,探讨了宝石成因模式。认为坦桑石形成于约5亿年前的泛非运动,仅产于新元古代莫桑比克变质带的蚀变石墨片麻岩中,属于接触交代成因的矽卡岩矿床,主要受地层岩性和构造变形两个因素控制。

关键词：矽卡岩地质特征坦桑石成因模式梅拉尼

CFD-DEM simulation of Small-Scale Challenge Problem 1 with EMMS bubble-based structure-dependent drag coefficient

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Particuology 2021年第2期19卷 48-61页

作者： Musango Lungu John Siame lloyd Mukosha Multiphase Flow Research Group Chemical Engineering DepartmentSchool of Mines and Mineral SciencesCopperbelt UniversityKitwe 10101Zambia

In this study,the energy minimization multi-scale(EMMS)/Bubbling model is coupled with the computational fluid dynamics/discrete element method(CFD-DEM)model via a structure-dependent drag coefficient to simulate the National Energy Technology Laboratory(NETL)small-scale challenge problem using the open-source multiphase flow code *** numerical predictions are compared against particle velocity measurements obtained from high-speed particle image velocimetry(HSPIV)and differential pressure *** drag-reduction effect of the EMMS bubble-based drag coefficient is observed to significantly improve predictions of the horizontal particle velocity and granular temperature when compared to several other drag coefficients tested;however,the vertical particle velocity and pressure fluctuation characteristic predictions are *** drag-reduction effect is characterized by a reduction in the sizes of slugs or voids,as identified through spectral decomposition of the pressure ***,this study shows great promise in employing drag coefficients,developed via multi-scale approaches(such as the EMMS paradigm),in CFD-DEM models.

关键词： CFD-DEM Drag model EMMS/Bubbling model Fluidization Multi-scale

Arabidopsis Mutants and the Network of M icrotu bu le-Associated Functions

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Molecular Plant 2008年第6期1卷 888-898页

作者： Henrik Buschmann Clive W. lloyd Department of Cell and Developmental Biology John Innes Centre 1 Colney Lane Norwich NR4 7UH UK

In early eukaryotes, the microtubule system was engaged in mitosis, intracellular transport, and flagellumbased motility. In the plant lineage, the evolution of a multicellular body involved the conservation of some core functions, the loss of others, and the elaboration of new microtubule functions associated with the multicellular plant habit. This diversification is reflected by the presence of both conserved （animal/fungi-like） and novel （plant-like） sequences encoding microtubule-related functions in the Arabidopsis genome. The collection of microtubule mutants has grown rapidly over recent years. These mutants present a wide range of phenotypes, consistent with the hypothesis of a functional diversification of the microtubule system. In this review, we focus on mutant analysis and, in particular, discuss double mutant analysis as a valuable tool for pinpointing pathways of gene function. A future challenge will be to define the complete network of genetic and physical interactions of microtubule function in plants. In addition to reviewing recent progress in the functional analysis of the ＇MAPome＇, we present an online database of Arabidopsis mutants impaired in microtubule functions.

关键词： cell division cell morphogenesis cytoskeleton genetics development Arabidopsis.

Observer error in vegetation surveys:a review

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Journal of Plant Ecology 2016年第4期9卷 367-379页

作者： lloyd W.Morrison Department of Biology Missouri State University901 S.National AvenueSpringfieldMO 65897USA National Park Service Heartland Inventory and Monitoring Program6424 W.Farm Road 182RepublicMO 65738USA

Aims Vegetation sampling employing observers is prone to both inter-observer and intra-observer *** types of errors are common:(i)overlooking error(*** observing species actually present),(ii)misidentification error(*** correctly identifying species)and(iii)estimation error(*** accurately estimating abundance).I conducted a literature review of 59 articles that provided quantitative estimates or statistical inferences regarding observer error in vegetation *** FindingsAlmost all studies(92%)that tested for a statistically significant effect of observer error found at least one significant *** surveys of species composition,mean pseudoturnover(the percentage of species overlooked by one observer but not another)was 10-30%.Species misidentification rates were on the order of 5-10%.The mean coefficient of variation(CV)among observers in surveys of vegetation cover was often several hundred%for species with low cover,although CVs of 25-50%were more representative of species with mean covers of>50%.A variety of metrics and indices(including commonly used diversity indices)and multivariate data analysis techniques(including ordinations and classifications)were found to be sensitive to observer *** of error commonly include both characteristics of the vegetation(*** size of populations,rarity,morphology,phenology)and attributes of the observers(*** fatigue,personal biases,differences in experience,physical stress).The use of multiple observers,additional training including active feedback approaches,and continual evaluation and calibration among observers are recommended as strategies to reduce observer error in vegetation surveys.

关键词： interobserver error intraobserver error misidentification pseudoturnover vegetation sampling

Nestedness in insular floras:spatiotemporal variation and underlying mechanisms

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Journal of Plant Ecology 2013年第6期6卷 480-488页

作者： lloyd W.Morrison Department of Biology Missouri State University901 S.National AvenueSpringfieldMO 65897USA

Aims Nestedness is a characteristic of insular metacommunity *** few studies,however,have attempted to evaluate temporal changes in nestedness,or elucidate the mechanisms underlying nestedness.I evaluated both spatial and temporal patterns of nestedness in the insular floras of four archipelagoes of small islands in the Bahamas and the potential underlying environmental *** The NODF(a nestedness metric based on overlap and decreasing fill)and the matrix temperature measure,T,were used to quantify nestedness in insular floras on small islands near Abaco,Andros,Great Exuma and the Exuma Cays,*** different null models were employed for each nestedness *** environmental variables were evaluated in relation to nestedness by ordering islands according to gradients and recalculating NODF *** Findings All archipelagoes were significantly *** among sites contributed more to overall nestedness than did nestedness among *** scores varied among archipelagoes,but were surprisingly constant over *** islands by vegetated area yielded the highest nestedness scores for three archipelagoes;ordering islands by protection from exposure yielded the highest nestedness score for one *** scores varied little over time even though species compositions changed,indicating that extinctions occurred in a deterministic *** relative importance of area suggests extinction is an important mechanism in producing *** to determine the relative importance of immigrations or extinctions requires some assumptions,however,and both processes are likely cumulative in most cases.

关键词： Bahamas environmental gradient insular floras nestedness NODF metric

Chebfun and numerical quadrature

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Science China Mathematics 2012年第9期55卷 1749-1760页

作者： HALE Nicholas TREFETHEN lloyd N Mathematical Institute University of OxfordOxford OX1 3LBUK

Chebfun is a Matlab-based software system that overloads Matlab's discrete operations for vectors and matrices to analogous continuous operations for functions and *** begin by describing Chebfun's fast capabilities for Clenshaw-Curtis and also Gauss-Legendre,-Jacobi,-Hermite,and-Laguerre quadrature,based on algorithms of Waldvogel and Glaser,Liu and *** we consider how such methods can be applied to quadrature problems including 2D integrals over rectangles,fractional derivatives and integrals,functions defined on unbounded intervals,and the fast computation of weights for barycentric interpolation.

关键词： Chebfun Clenshaw-Curtis quadrature Gauss quadrature barycentric interpolation formula Riemann-Liouville integral fractional calculus

Thermomechanical analysis of long-term global modal and local deformation measurements of the Kishwaukee Bridge using the bootstrap

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Earthquake Engineering and Engineering Vibration 2004年第1期3卷 107-115页

作者： George M.lloyd Ming L.Wang Department of Civil and Material Engineering University of Illinois at Chicago

In this paper we present a comparative analysis of global frequency and local deformation data for a large concrete bridge. The asymptotic probability distributions of the central statistics are presented, and compared with empirical bootstrap estimates. Bootstrapped distributions are calculated from reference data obtained during 1999–2000 and used to develop change-point alarm criteria for the structure, using reasonable sensitivity measures developed from FEM simulations and structural analysis. The implications of the frequency data are discussed in conjunction with the strain and displacement measurements in order to discern if the load carrying capacity of the bridge has been affected. The critical need for more advanced temperature compensation models for large structures continually in thermal disequilibrium is discussed.

关键词： thermomechanical effects bootstrap methods local & global monitoring long term measurement concrete bridge