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基于整体化理论的林木、林分生长模型模拟系统开发 总被引:1,自引:0,他引:1
以森林模型整体化理论思路为基础,利用vb6.0编程软件开发出独立的林木林分生长和收获模型模拟系统,在解决不同水平模型之间相容性、一致性及内部结构的问题,在生态模拟中有一定的应用价值。 相似文献
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指出了气携式液液旋流器是港区小型化、船载化洗舱、压仓含油废水预处理的关键设备.采用流固耦合数值模拟方法再现压缩机进气、油水旋流与设备本体的整体气浮—旋流—分离耦合计算模型 ,对其核心部件微孔旋流套管的构型、孔径、内外压差及腔内流场分布进行了三维数值模拟 ,得到了微孔旋流腔内汽、水、油三相的流场分布 ,合理确定了注气腔气—水平衡分压、溢流比和微孔孔径 ,并模拟了压缩机、潜水泵正常工况下进气、进水、出水、油污溢流的流量、流速波动范围 ,为该设备的一体化构型设计和加工选材提供了参考数据. 相似文献
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《中南林业科技大学学报(自然科学版)》2016,(11)
CITYgreen碳储量模型在国内虽然已有一些应用,但对其准确性一直缺乏验证。本研究选择中国科学院鹤山站40块10×10m人工林样地,分别通过CITYgreen模型模拟和生物量转换方法对其碳储量进行计算。并以准确度较高的生物量转换方法对CITYgreen模拟值进行验证。结果显示,CITYgreen较准确地计算出人工林的碳储量值,与生物量转换计算方法间并无显著差异(P0.05)。这说明CITYgreen模型不仅对城市森林,而且对各类人工林碳储量核算都具有重要的推广和应用价值。此外,文章还详细介绍了运用CITYgreen模型核算人工林碳储量的步骤和方法。 相似文献
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提出了适用于近岸水域的环境容量计算方法,通过构建三维水动力、三维生态动力模型对近岸水域的水动力、水质过程进行了模拟验证,结合水质功能分区,将容量计算归结为线性规划问题,求解在规划的水污染控制单元划分和排污口位置条件下的水环境容量.以大亚湾水域为实例求解与分析了CODMn环境容量,验证了计算方法的适用性和有效性. 相似文献
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为了对御道口沙地樟子松人工林密度效应进行量化比较,采用统计学及种群生态学方法对御道口沙地樟子松人工林自疏规律进行建模研究,探讨了2种不同自疏规律模型的构建方法并进行了对比分析。结果表明:通过比较Reineke密度模型和Yoda模型的预测值与实际值有一定的差异。Reineke模型模拟的结果与实际结果对比的平均误差为0.2%,Yoda模型与实际结果对比的平均误差为22.1%,Reineke自然稀疏模型的预测更接近实测值。该结果可以为沙地樟子松人工林在御道口地区的经营与管理提供参考。 相似文献
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【目的】环境因子是影响林木冠层水分利用的主要因素。本研究以黄土高原高寒区主要树种青海云杉为研究对象,对其蒸散发特征进行分析,以期探讨不同冠层导度模型的适用性。【方法】于2013年6月,采用热扩散技术对青海云杉蒸散量进行定位监测,监测步长15 min,并结合彭曼—蒙特斯方程反演气孔导度(g_c),在此过程中考虑了可能存在树干液流时滞的问题。选择饱和水汽压差(D),大气温度(T)和太阳辐射(R)等3个关键气象参数,采用6个不同形式的Jarvis模型和1个多元线性模型模拟g_c,所有模型的待定系数都采用1stOpt软件进行计算,并进行交叉验证。以奇数日数据计算g_c,用偶数日的数据进行验证。【结果】青海云杉基于液流计算的冠层蒸腾对环境因子变化的响应时滞为15 min。g_c与D和T呈显著的指数函数关系(P0.000 1),并随着其值的增大而减小,而冠层蒸散量(E_c)则与R呈显著的二次函数关系(P0.000 1)。多元线性模型模拟g_c的回归系数为0.90,略低于6个Jarvis模型(0.91~0.92),但用多元线性模型拟合的g_c计算的日E_c的精度最高。此外,7个模型模拟的g_c/E_c值都有较高的精度。【结论】R是青海云杉冠层蒸腾的主要驱动力,但其气孔的开合却主要受到D和T的控制。7个模型都具有较高的精度,但Jarvis模型的模式较多、使用复杂,部分模式的待定系数会出现有无穷组解的现象,且不同的解之间存在较大的差异。而多元线性模型的形式简单,精度高,是模拟g_c的较优选择。 相似文献
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将原《拱形断面暗沟》水力计算图表进行优化并压缩。其中谢才系数采用曼宁公式计算( 原为巴甫洛夫斯基公式) ,符合现行《室外排水设计规范》。另外,增加了“水力要素计算表”和“流量流速修正值表”。从而使该水力计算图表更趋完善。 相似文献
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本文结合河网平源地区的水文地理特点,提出了雨水管道设计中管径确定与管道埋设分别独立进行,水力计算采用统一的水力坡降,管道埋设采用统一的安装坡度,以及提倡管底平接等设计思想与计算方法。 相似文献
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《Forest Ecology and Management》1997,95(2):183-195
There is currently great interest in improving the applicability of forest gap models to changing environmental conditions, in order to facilitate the assessment of possible impacts of climatic change on forest ecosystems. Moreover, for the development of mitigation strategies, it is necessary to include forest management options in the models. Both the simulation of transient effects of climatic change and of forest management regimens require a realistic representation of stand structure in gap models, since tree species respond to variations in stand density in characteristic ways, depending on their ecological strategies.In this study, we compared the effect of five different height growth functions that are sensitive to stand density on simulated stand structure of the FORSKA forest gap model. We used long term observation data from a beech thinning trial at Fabrikschleichach, Bavaria, to test the alternative functions. First, we compared simulation results of the original FORSKA model with measured stand development from 1870 to 1990. Whereas simulated stand level variables (e.g. biomass, mean diameter and height) showed good correspondence with observations, individual tree dimensions and simulated stand structure were quite unrealistic. After calibrating parameters of the height growth functions with data from a lightly thinned plot at Fabrikschleichach, we ran the model with data from a heavily thinned plot for validation. All five functions considerably improved the simulation of height/diameter relationships and stand structure. However, there were distinct differences between functions. The best correspondence with measurements was shown by a function which uses the relative radiation intensity in the centre of a tree crown as an indicator of the competition status of the tree. This function is rather simple and needs only two growth parameters, which can be derived for different functional types of species, according to their shade tolerance.With the new, flexible height growth function it should be possible to extend the applicability of gap models to more realistic simulation experiments including forest management and natural disturbance. To our knowledge, this was the first attempt to employ long term forest observation data for the calibration and validation of a forest gap model. The results suggest that such data could be very useful in model testing and improvement. 相似文献
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The three-dimensional orientation distribution function (ODF), being a probability of the density of crystallographic orientations,
is widely used for describing internal arrangement of polycrystalline materials (especially metals and alloys). The application
of the ODF was enhanced in the paper for the monoclinic crystal symmetry. The algorithm of the crystallographic texture analysis
based on the arbitrarily defined cells method was presented together with the discussion of the input data required for analyzing
the space organization of the ultrastructure of materials with the monoclinic lattice symmetry. The test analysis was performed
for the model material of the same type of the crystallographic lattice as in wood cellulose. The obtained ODF was presented
and discussed. The results of the analysis were supplemented both with reconstructed complete pole figures and with the inverse
pole figures. 相似文献
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The topic of model complexity is fundamental to model developers and model users. In this study, we investigate how over- and under-fitting of a driving function in a simulation model influences the predictive ability of the model. Secondly, we investigate whether model selection approaches succeed in selecting driving functions with the best predictive ability. We address these issues through an example with the forest simulator SORTIE-ND. Utilizing maximum likelihood methods and individual tree growth data we parameterize five growth functions of increasing complexity. We then incorporate each growth function into the simulation model SORTIE-ND and test predicted growth against independent data. Compared to the independent data, the simplest and the most complex growth functions had the poorest predictive ability while functions of intermediate complexity had the best predictive ability. The poor predictive ability of the simplest model is caused by poor approximation of the system while the poor predictive ability of the most complex model is caused by biased parameter estimates. A growth function of intermediate complexity was the most parsimonious model where error due to approximation and error due to estimation were simultaneously minimized. The model selection criteria AIC and BIC were found to select complex functions that were over-fitted according to the independent data comparison. BIC was closer to choosing the model that minimized prediction error than AIC. In this example, BIC is the more appropriate model selection criterion. It is important that both model developers and models users remember that more complex models do not always result in better predictive models. 相似文献
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Emin Zeki Başkent Ali İhsan Kadıoğulları 《Scandinavian Journal of Forest Research》2014,29(7):121-131
Decision support systems (DSSs) are indispensable tools in preparing a forest management plan for a better combination of multiple forest values. This study attempted to develop and explain a stand-based forest management DSS (Ecosystem-based multiple-use forest planning [ETÇAP]) comprising a traditional simulation, linear programming (LP), metaheuristics and geographic information system. The model consists of five submodels; traditional management approach to handle inventory data, an empirical growth and yield model, a simulation to conceptualize management actions, a LP technique to optimize resource allocation and a simulated annealing approach to directly create a spatially feasible harvest schedule. The ETÇAP model has been implemented in a comparative two case study areas; Denizli–Honaz and Akseki–Ibrad?. Both simulation and optimization models outperformed to the traditional management plan. The periodical change of growing stock, allowable cuts, carbon sequestration and water production are used as performance indicators. The results showed that more amount of wood could be harvested over time compared to traditional level of harvesting. It could be concluded that various management strategies allowed managers to stimulate more decision options for better outputs through intertemporal trade-offs of management interventions as the model provided tools to quantify forest dynamics over time and space. Challenges exist to establish the functional relationships between forest structure and values for better quantification and integration into the management plans. 相似文献
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Katsushige Shiraki Yoshiki Shinomiya Hirofumi Shibano 《Journal of Forest Research》2006,11(6):439-447
Numerical experiments of soil water movement and bedrock infiltration based on a simplified simulation method were conducted
to analyze watershed-scale rainfall-runoff processes. To verify the model accuracy, it was applied to a Minamitani watershed
(0.45 ha). The simulation was performed with 2.5-m space grids horizontally and five cells vertically. Results of long-term
calculation of this model proved that this simulation model is robust and demonstrated good computational water mass conservation.
Calculation results showed the best agreement with observed hydrographs and the number of groundwater levels simultaneously
when laboratory-tested soil hydraulic characteristics for topsoil were used and infiltration into bedrock was included in
numerical calculations. Numerical experiments show that bedrock infiltration generated a stable base flow and suppressed the
secondary discharge peak. The reproducibility achieved by observed soil hydraulic characteristics with the assumption of bedrock
flow demonstrates the effectiveness of the simulation model used in this article for analyses of watershed-scale soil water
movements. 相似文献
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Stéphanie Schmid Andreas Zingg Peter Biber Harald Bugmann 《European Journal of Forest Research》2006,125(1):43-55
The semi-empirical single-tree model SILVA 2.2 has been developed and parameterised using forest research and inventory data
from Germany that range from the colline to the montane zone. The focus of the model evaluation presented in this study was
to test the applicability of the model for the main Swiss forest types and at elevations ranging from the colline to the upper
subalpine zone. To this end, SILVA was initialized using data from long-term forest yield research plots. The results at the
end of the 30-year simulation were compared with observed data. The analysis of the results at each test site showed that
there were no significant differences in model performance between forest types. However, the deviation between simulated
and observed growth depended strongly on the elevational zone, i.e., on climate. As expected, the best results were found
in the colline zone, for which the model had been calibrated, whereas the upper subalpine sites revealed the strongest differences.
The quality of the data regarding forest structure that were available for model initialization had a strong impact on the
simulation results, mainly at high-elevation zones (i.e., supalpine and upper subalpine). We conclude that SILVA 2.2 is a
suitable tool to estimate the development of single trees and standing volume for a large fraction of the forests in Switzerland.
However, extreme climate conditions should be avoided with the model, and the availability of detailed stand structure information
is a key priority that has a strong effect on the quality of the simulation results.
相似文献
Harald BugmannEmail: |
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Tong Zhai Rabi H. Mohtar Andrew R. Gillespie Guntram R. von Kiparski Keith D. Johnson Michael Neary 《Agroforestry Systems》2006,66(3):243-257
Tree effects on understory pasture growth in a silvopastoral system were modeled by explicit simulation of tree canopy light
and rainfall interception, evapotranspiration, and nutrient uptake. The algorithms to model these effects were incorporated
into a multispecies grazing simulation model, GRASIM, to form the Silvopasture GRASIM model (SGRASIM). The new model was evaluated
using forage biomass data and soil moisture data collected from a silvopasture field experiment with black walnut (Juglans nigra L.). The SGRASIM model performed well in simulating the growth of three competing dominant forage species (orchardgrass [Dactylis glomerata L.], Kentucky bluegrass [Poa pratensis L.], and tall fescue [Festuca arundinacea (Schreb.)] in the pasture both under tree canopy and in open pasture (linear regression of observed on simulated biomass
for the species gave r
2 values above 0.97). Model growth parameters for forage under tree canopy, compared with those for an open pasture, bear testament
to the shading effects from the forest canopy in terms of reduced photosynthetic efficiency, increased leaf area ratio, and
photosynthate partitioned to aboveground biomass. The new model reasonably followed the soil moisture time series in the upper
soil layer (0–30 cm), where the bulk of the forage roots reside. 相似文献