共查询到19条相似文献,搜索用时 62 毫秒
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提出基于四叉树的LOD实时绘制方法,对LOD模型中的节点评价因子进行了改进,提高了图像的真实感,采取“几何形变“消除“跳跃“现象;提出一种新的动态场景调度和快速扫描裁剪的方法,实现了大规模地形漫游的实时性和画面流畅性;引入“Ver-tical Skirt“技术用于块间裂缝现象的消除,实现了地形块LOD绘制的独立操作;最后在VC++6.0平台上利用OpenGL实现了基于本文算法的地形可视化系统,验证了本文提出的方法可行性。 相似文献
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周光明 《湖南环境生物职业技术学院学报》2002,8(3):186-188
为了提高施工企业的中标概率,获取更多的利润,减少决策失误.本文对决策树法的基本理论、适用条件、绘制方法及选取最佳方案进行了探索. 相似文献
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用剪力图面积法绘制弯矩图 总被引:1,自引:0,他引:1
在建筑力学中,弯矩图的绘制是结构设计的基础和依据.通过对梁上外荷载与内力间微积分关系及函数图形的研究,找到了剪力图与弯矩图的内在规律,得到一种绘制弯矩图的新方法——剪力图面积法,应用这种方法可大大提高作图速度和效率.图1,表1,参6. 相似文献
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植被-侵蚀动力学模型参数的确定及在黄土高原的应用 总被引:3,自引:0,他引:3
植被-侵蚀动力学是研究流域植被与侵蚀在人类活动影响下演变规律的一门新的边缘学科。由植被-侵蚀动力学模型可绘制植被-侵蚀状态图,以预测停止人为干扰后植被及侵蚀变化趋势,评价水土保持措施成效,提出小流域优化治理方略。植被-侵蚀动力学模型4个参数a、c、b、f是流域重要特征参数,其值的确定是进行植被-侵蚀动力学模拟及绘制植被-侵蚀状态图的前提和基础。它们依赖于流域气候、土壤和地形地貌。本文以黄土高原典型小流域为例,采用试算法确定了它们的取值,通过相关分析发现参数a与P、T,参数c、b、f与D50、S之间存在明显的相关关系,并得到了相关关系式。将其用于吕二沟小流域植被-侵蚀动力学模拟,结果与实际情况符合较好。绘制了各参数的取值分布图。最后以燕儿沟小流域为例,将以上相关关系式用于植被-侵蚀状态图的绘制,及小流域自然状况、植被-侵蚀状态及水土保持效果的评价。 相似文献
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空间插值是各种地学、生态学研究中经常遇到的问题。文章以中国1950年至1998年160个测站年均降水量数据为例,介绍采用空间插值绘图软件Win-Surfer绘制等值线图的基本方法与步骤,并对软件中几种常用的空间插值方法的优缺点进行简要的对比分析。 相似文献
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大气气溶胶中多环芳烃的定量分析 总被引:40,自引:1,他引:40
参照美国EPA610方法,超声抽提气溶胶样品,抽提物经硅胶层析柱分离,用毛细管柱气相色谱与GC-MSD鉴定多环芳烃,使用16种多环节烃混合标准样品绘制校正曲线,以外标法对PAHs进行了定量分析。 相似文献
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新疆喀什地区地下水氟的空间分布规律及其富集因素分析 总被引:1,自引:0,他引:1
高氟地下水严重影响当地居民的身体健康.基于新疆喀什地区571个地下水样的氟离子实测含量,运用Mapgis软件绘制研究区地下水氟含量分布图,结果表明,研究区地下水氟含量呈西部、北部高于东部、南部,中部最低的特点;山麓斜坡冲洪积砾质平原区氟含量表现为浅层潜水高于深层潜水,中下游河流冲积平原区地下水氟含量表现为潜水浅层承压水深层承压水.采用绘制Gibbs图、Piper三线图、离子比例图等方法对研究区水化学环境特征及地下水氟的富集因素进行研究,结果表明,研究区地下水氟源于山前含氟基岩;受地下水径流条件影响,研究区地下水氟含量平均值表现为中下游河流冲积平原区山麓斜坡冲洪积砾质平原区;蒸发浓缩作用使F~-浓度进一步增大;研究区高氟地下水水化学类型主要为HCO_3-Na和Cl·SO_4-Na型,地下水弱碱性环境有助于F~-的富集. 相似文献
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铜锰钴复合氧化物催化剂对环己烷或苯深度氧化的催化活性 总被引:1,自引:0,他引:1
本文应用了研究相图与床层温差评价催化活性的方法,研究了在催化深度氧化环己烷或苯的反应中,铜、锰、钴三元氧化物催化剂体系的组成与催化活性的关系。用反应物在催化剂上起燃温度的等温图,描绘出该体系氧化物催化剂对环己烷或苯的催化氧化活性的分布。所得结果指导了用于净化苯系物废气所需催化剂的研制。 相似文献
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A 3-D version of the MECCA model (Model of Estuarine and Coastal Circulation Assessment) is used to simulate the dynamics of the Eastern part of the English Channel. This area is characterized by a strong tidal turbulent regime and a frontal zone identified near the French coast by a low-salinity band. The model uses the upwind scheme to approximate the advective terms. Results show that the model overestimates the band width of the frontal zone and that this anomaly is definitely caused by the numerical diffusion introduced by the so-called upwind scheme (first-order approximation). In this paper, we study the flux-limiter schemes as an alternative to the upwind method in order to reduce this non-physical diffusion. To illustrate the improvements provided by this type of schemes, a comparison in 2-D schematic cases is made between the upwind and centered scheme with more recent higher-order schemes combined with limiter namely Minmod, Superbee, Van Leer and Monotonized Centered (MC) (called also MUSCL scheme). Respecting the CFL condition, our numerical simulations show that the flux-limiter schemes reduce the numerical diffusion and eliminate the oscillations caused by the non-limited higher-order schemes. For the schematic and realistic cases, the Superbee limiter is a good compromise between shape preservation and computational cost. 相似文献
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The Hiatt growth diagram for crustacea 总被引:3,自引:0,他引:3
J. Mauchline 《Marine Biology》1976,35(1):79-84
The Hiatt growth diagram relates post-moult to pre-moult size in crustaceans. Size in this context is most frequently defined by a linear measurement of length or width. Linear regression analysis of data on the Hiatt growth diagram is used to define growth constants. This assumes that growth factors (percentage increase in body size) at successive moults remain constant over the length of the line. Growth factors, however, decrease logarithmically at successive moults. Consequently, points on a Hiatt growth diagram are fitted better by a hyperbola than a straight line. The method of fitting an equation for a hyperbola is given. The best growth constant is the moult slope factor which is the factor by which the growth factor decreases at each successive moult. This is comparable with the intermoult period slope factor, the factor by which the intermoult period increases at each successive moult. These constants can be used to determine the moulting and growth sequences throughout the life of a crustacean. 相似文献
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废水处理新技术中的超临界水氧化法 总被引:20,自引:1,他引:19
超临界水氧化法是一种有效处理有机废水的方法,本文在总结超临界水的特点和优点的基础上,着重介绍了超临界水氧化的基本原理,工艺流程及应用状况,探讨该项技术的前景与发展趋势。、 相似文献
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This study provides a method for assessing a multiplicity of environmental factors in red spruce growth in the Great Smoky Mountains National Park (GSMNP) of Southeastern USA. Direct and indirect factors in the annual growth increment are first organized into a schematic input-output envirogram (ARIRS), and this information is then used to construct a simulation model (ARIM). The envirogram represents a structured conceptualization of most environmental factors involved in growth, as developed from relevant literature. This interdisciplinary synthesis distinguishes direct vs. indirect factors in growth and takes account of the systems ecology concept that indirect factors may be as important as or more important than direct ones in regulating growth. The ARIRS envirogram summarizes hierarchically organized, within- and cross-scale, local-to-global interactions, and its construction makes it obvious that growth is influenced by many cross-scale spatiotemporal interactions. More research on genecology is still needed to clarify the role of phenotypic plasticity and adaptive capacity in nutrient cycling, global change, and human disturbance. 相似文献
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Turbulence closures are fundamental for modelling the atmospheric diffusion in numerical codes and the resulting eddy diffusivities are key parameters in describing the transport and dispersion in the boundary layer. In this work, four turbulence closure schemes have been applied for reproducing a neutral flow over schematic complex terrain using the meteorological model RAMS. Two of the closures, a one-equation (E-l) and a two-equations (E-) model, have been implemented in RAMS in alternative to the ones originally available. In these cases, an analytical method based on the similarity theory for the atmospheric surface layer and boundary layer is adopted to calculate the empirical constants of the turbulence closures. Some examples of numerical studies performed to simulate the flow and turbulence over a 3-D hill in wind-tunnel experiment in neutral stratification are presented and discussed. An intercomparison of simulations related to different closures is considered by analysing the main features of the flow over the hill and by comparing calculated vertical profiles of turbulent kinetic energy with measured ones. 相似文献
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化学方法降低城市污泥的重金属含量及其前景分析 总被引:5,自引:0,他引:5
城市污泥含有丰富的氛、磷、河和有机质,农用前景广阔。但其中重金属含量常超标而受到限制。利用化学试剂如酸、有机物、表面活性剂等与污泥中的重金属发生作用,形成溶解性的金属离子或金属-试剂络合物,再通过淋滤.可以剔除污泥中大量的重金属,使其降低到符合农用标准。本文介绍了化学方法去除污泥事金属的原理和效果,分析了影响因素,包括重金属种类、污泥特性、操作方法、剔除时间等。并对该法的应用前景进行了讨论。 相似文献
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Kristina Voigt Gerhard Welzl Rainer Brüggemann Stefan Pudenz 《Environmental Sciences Europe》2002,14(1):58-64
Comprehensive data on environmental monitoring programs concerned with air pollutants like ozone (O3), nitrogen dioxide (NO2), nitrogen oxide (NO), carbon dioxide (CO2) und carbon monoxide (CO), and occassionally suspended dust, benzene and other environmental chemicals, are available on the free Internet. As different monitoring information systems exist in most states or big cities of the Federal Republic of Germany, a comparison of these systems with their pros and cons is of great interest to the public. Environmental air pollutant monitoring systems in 16 states of Germany are listed and evaluated by applying 5 evaluation criteria for the differentiation of these systems. Different data-analysis methods will be applied, the Hasse diagram technique, a method derived from discrete mathematics and the partially Ordered Scalogram Analysis with Coordinates (POSAC) method, a multivariate statistical approach. The important objects, the so-called maximal or minimal objects, are detected in both methods. The Internet-based environmental monitoring systems of the states of Berlin, Bremen, Saxony-Anhalt, Baden-Wurttemberg are rated good in the evaluation approaches, whereas the information systems of the states of Brandenburg, North Rhine-Westphalia, Saxony received a rather poor ranking. The attributes of DA, way of data presentation on the Internet, and ME, type and length of measurements, were pointed out in the data-analysis methods. Multivariate explorative statistical methods offer a comprehensive tool for the graphical analysis of data-matrices. The ranking of objects is given in an effective and graphically comprehensible manner using the Hasse diagram technique. The choice and preference of the methods is problem-driven. A combination of these different methods is envisaged in the authors’ future research. 相似文献