Exurbia from the bottom-up: Confronting empirical challenges to characterizing a complex system

We describe empirical results from a multi-disciplinary project that support modeling complex processes of land-use and land-cover change in exurban parts of Southeastern Michigan. Based on two different conceptual models, one describing the evolution of urban form as a consequence of residential preferences and the other describing land-cover changes in an exurban township as a consequence of residential preferences, local policies, and a diversity of development types, we describe a variety of empirical data collected to support the mechanisms that we encoded in computational agent-based models. We used multiple methods, including social surveys, remote sensing, and statistical analysis of spatial data, to collect data that could be used to validate the structure of our models, calibrate their specific parameters, and evaluate their output. The data were used to investigate this system in the context of several themes from complexity science, including have (a) macro-level patterns; (b) autonomous decision making entities (i.e., agents); (c) heterogeneity among those entities; (d) social and spatial interactions that operate across multiple scales and (e) nonlinear feedback mechanisms. The results point to the importance of collecting data on agents and their interactions when producing agent-based models, the general validity of our conceptual models, and some changes that we needed to make to these models following data analysis. The calibrated models have been and are being used to evaluate landscape dynamics and the effects of various policy interventions on urban land-cover patterns.     

火山岩储层建模初探

火山岩储层建模研究是一个世界性难题。近年来 ,国内外在含油气盆地的火山岩中发现了大量的油气藏。为了探索火山岩储层物性的空间分布特征 ,作者选取了松辽盆地徐家围子地区火山岩发育的营城组为研究目的层 ,以火山岩相分析为基础 ,以基于相分析的神经网络技术为手段 ,通过多种参数的选取和计算 ,尝试性地建立了该区火山岩储层地质模型。该模型表明 :层状火山机构比块状火山机构的物性好 ;多相火山机构比单相火山机构物性好 ;裂缝发育的火山机构比裂缝不发育的火山机构物性好。基底涌流相、火山空落相、火山沉积相是有利的储集相带。     

Fuzzy Modeling for Reserve Estimation Based on Spatial Variability

This article addresses a new reserve estimation method which uses fuzzy modeling algorithms and estimates the reserve parameters based on spatial variability. The proposed fuzzy modeling approach has three stages: (1) Structure identification and preliminary clustering, (2) Variogram analysis, and (3) Clustering based rule system. A new clustering index approach and a new spatial measure function (point semimadogram) are proposed in the paper. The developed methodology uses spatial variability in each step and takes the fuzzy rules from input-output data. The model has been tested using both simulated and real data sets. The performance evaluation indicates that the new methodology can be applied in reserve estimation and similar modeling problems     

3D chemical model for geological macromolecules

This study defines a chemical representation of the kerogen macromolecule based on data from physicochemical analyses. The model should permit: creation of various schematic drawings representing an average macromolecule; future integration of new analytical results (for instance on structures of biomarkers or biopolymers); and determination of the distribution of chemical bonds.The models developed in this study can be represented in a 3D space, using classical chemical symbols, in the form of cyclic groups linked to each other by aliphatic chains. One cyclic group is a connected set of aromatic, naphthenoaromatic or naphthenic rings. These cyclic groups are constructed using basic elements such as atoms and bonds defined by their length and direction.Modeling of kerogen is done in three successive steps. A library is first created to define atoms, bonds and cyclic groups. Secondly, starting from a set of equations describing the analytical results, cyclic and aliphatic groups are chosen in the appropriate stoechiometric amount to match the analytical data. Finally the construction is done: cyclic groups are placed randomly in a 3D space, connections are made by aliphatic chains, and functional groups are added.The molecular modeling software Xmol^TM can be operated on APOLLO stations. It allows the creation of libraries, the calculation of chemical bonds corresponding to the analyses and the construction of macromolecules. An example is given for a type III kerogen at the beginning of diagenesis.     

A NEW RECEPTOR MODEL:A DIRECT TRILINEAR DECOMPOSITION FOLLOWED BY A MATRIX RECONSTRUCTION

In many cases,monitoring data for ambient airborne particles can be organized in the form of a three-way data table with one way for chemical species,one for sampling periods and one for sites.A directtrilinear decomposition followed by a matrix reconstruction(DTDMR)is developed to analyze such adata table as a whole.The three-way data set is composed into three two-way matrices by a direct trilineardecomposition(DTD).The column vectors of each of the matrices are called‘source profiles’,‘emissionpatterns’and‘site coefficients’respectively.Particulate sources are identified by examining both theirsource profiles and emission patterns.After the sources have been identified,emission patterns and sitecoefficients are used to produce a three-way matrix that gives estimates of mass contributions of sourcesto the samples collected at every site in every period.By simulation study,not only has the method beenverified,but a good indicator has been found that shows the number of factors(i.e.sources)in thesystem.Unlike other receptor models,DTDMR does not require source profile data and does not involvetrial-and-error procedures.Since DTDMR identifies sources based on variations in two dimensions,it hasa higher potential to distinguish two sources that have similar chemical compositions.The DTDMRmodel has provided excellent results with simulated data and has been applied in a real world three-waydata set.     

Differences in trace metal concentrations among fluvial morphologic units and implications for sampling

 This study examines the segregation of trace metals within and between fluvial morphologic units in sand-sized and finer bed sediments in a cobble bed stream. The types of fluvial morphologic units sampled are low gradient riffles, high gradient riffles, glides, eddy drop zones, lateral scour pools, attached bars, and detached bars. Three to nine samples were collected from ten of each type of morphologic unit. All 12 metals show significantly different concentrations between some morphologic units in sediments smaller than 2 mm. Eddy drop zones and attached bars consistently have the highest metal concentrations, while low gradient riffles, high gradient riffles, and glides typically have the lowest concentrations. Metals showing the greatest between-unit variability are Al, Cr, Fe, Cu, and Ti, followed by Co, Mn, and Pb, while Mg, Mn, V, and Zn display relatively few differences between units. Lateral and longitudinal variations of metals within units are not significant, and there was no consistent, predictable variation in metal concentrations with distance downstream. Results indicate that metal studies in other gravel- and cobble-bed streams should include a reconnaissance survey to determine variations between morphologic units, stratify sampling by morphologic unit, and analyze spatial autocorrelation to determine sample spacing. Received: October 1997 · Accepted: 23 March 1998     

Identifying components for interoperable process models using concept lattice and semantic reference system

The development of interoperable environmental process models is widely supported by both the research community and government agencies. This paper discusses a conceptual framework to guide the delineation of process components, the basic unit of interoperable models. The concepts of semantic reference system and dual hierarchy are explored to establish the conceptual framework. Based on this discussion, the Formal Concept Analysis is used as an analytical approach to decompose and fuse existing environmental process models in order to identify environmental process components. For purposes of discussion, a hydrological process, surface runoff, is used throughout the paper as an example of an environmental process to support the conceptual discussion and to illustrate the application of the conceptual framework and analytical approach.     

Crust structure of the northeastern Barents Sea basin area

Processing of data from regional geophysical surveys completed in the northern Barents Sea has provided updates to gravity and magnetic databases, structural maps of seismic interfaces, and positions of anomaly sources, which made a basis for 3D density and magnetic models of the crust. The new geological and geophysical results placed constraints on the boundaries between basement blocks formed in different settings and on the contours of deposition zones of different ages in the northeastern Barents Sea. The estimated thicknesses of sedimentary sequences that formed within certain time spans record the deposition history of the region. There is a 20-50 km wide deep suture between two basins of Mesozoic and Paleozoic ages in the eastern part of the region, where pre-Late Triassic reflectors have no clear correlation. The suture slopes eastward at a low angle and corresponds to a paleothrust according to seismic and modeling data. In the basement model, the suture is approximated by a zone of low magnetization and density, which is common to active fault systems. The discovery of the suture has important geological and exploration implications.     

有限m重非齐次马氏链随机变换的一个强极限定理

将赌博系统的随机变换概念推广到有限优重非齐次马氏链情形,采用鞅方法研究了有限m重非齐次马氏链函数的强极限定理,作为推论得到有限m重非齐次马氏链随机变换的若干强极限定理。     

基于 Lidar 数据和倾斜摄影的城市三维模型构建

针对传统建模方式建模效率低、模型纹理不够丰富真实等缺点,阐述一种以机载Lidar技术来获取地面点高精度的三维坐标、用倾斜摄影测量为三维建模提供纹理的一种新兴的三维建模方式。实验表明,该建模方式不仅工作效率高、真实反应城市空间布局,而且定位精度高、具备可量测分析功能等,同时提供DOM,DEM,点云数据,倾斜影像等数据。