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日光温室墙体一维导热的MATLAB模拟与热流分析 总被引:1,自引:0,他引:1
为探明日光温室墙体层间温度变化及热量传递动态规律,采用有限差分法建立墙体一维非稳态导热模型,利用MATLAB编制相应的模拟程序,计算出日光温室墙体各点的温度和热流。结果表明:该模型能够比较准确模拟日光温室土墙的温度。墙体内侧存在有效蓄热层,它对日光温室室内热环境有积极的作用。墙体有效蓄热层的热流白天指向墙体外侧,夜间指向墙体内侧,因此它的厚度直接根据热流的方向确定。有效蓄热层与天气、墙体总厚度以及墙体热特性参数有关。2012-12—2013-01期间有效蓄热层厚度为0.26~0.45m不等,最大值出现在连续雪天。同时从理论上验证了3.0m厚的温室土墙内部存在热流相对稳定的"热稳定层"。 相似文献
53.
植物生长模拟研究,是利用计算机仿真技术来模拟现实中植物的生长状态。论文以胡杨生长数据为基础,通过实验分析,推出了胡杨树高与胸径之间的关系,提出一种基于三维结构的胡杨茎生长模型,并运用3DMax技术实现胡杨茎生长模拟的可视化,同时给出了从不同角度模拟胡杨茎生长的状态图,从而全面反映了胡杨茎的生长模拟。 相似文献
54.
Genomic best linear unbiased prediction method reflecting the degree of linkage disequilibrium 下载免费PDF全文
The degree of linkage disequilibrium (LD) between markers differs depending on the location of the genome; this difference biases genetic evaluation by genomic best linear unbiased prediction (GBLUP). To correct this bias, we used three GBLUP methods reflecting the degree of LD (GBLUP‐LD). In the three GBLUP‐LD methods, genomic relationship matrices were conducted from single nucleotide polymorphism markers weighted according to local LD levels. The predictive abilities of GBLUP‐LD were investigated by estimating variance components and assessing the accuracies of estimated breeding values using simulation data. When quantitative trait loci (QTL) were located at weak LD regions, the predictive abilities of the three GBLUP‐LD methods were superior to those of GBLUP and Bayesian lasso except when the number of QTL was small. In particular, the superiority of GBLUP‐LD increased with decreasing trait heritability. The rates of QTL at weak LD regions would increase when selection by GBLUP continues; this consequently decreases the predictive ability of GBLUP. Thus, the GBLUP‐LD could be applicable for populations selected by GBLUP for a long time. However, if QTL were located at strong LD regions, the accuracies of three GBLUP‐LD methods were lower than GBLUP and Bayesian lasso. 相似文献
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简要分析了有限元法和边界元法在梁类零件振动仿真分析中的优点和缺点.梁是常用的机械结构件,在工程机械中的应用非常广泛.应用边界元法对矩形梁弯曲振动进行了仿真分析,当梁的弹性常数不变而横截面的高宽比改变时.其固有振动频率会相应地改变,为通过改变结构参数来改善梁结构的动力学性能进行理论探索. 相似文献
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This study develops an analytical method that enables the simulation of the deformation of timber-framed plywood panel dome
structures, of which strength is largely governed by the rigidity of joints. A hybrid truss structure model was employed to
analyze this structure. In this model, we aimed to incorporate the mechanical properties of bolted and nailed joints, which
were employed to build the structures, although the present investigation focused on the deformation characteristics of a
dome in which the panel elements were connected mutually by elastic springs. The results of the theoretical analysis are compared
with those obtained by experiments. The simulated results were found to be in good agreement with the results of the experiments
under similar loading conditions. 相似文献
60.
Bijan Payandeh 《New Forests》1988,2(3):145-160
Drainage and fertilization of an existing peatland black spruce (Picea mariana (Mill.) B.S.P.) stand and 24 possible methods of planting a clear-cut area near Cochrane, Ontario were evaluated by means of a recently developed forestry investment decision model, FIDME.Results indicate that, on the basis of the cost estimates used and assumptions made, drainage of the existing stand is the most economical treatment if it can reduce the rotation age by 30 years or more. Drainage combined with fertilization is the second best alternative if this treatment can reduce the rotation age by 40 years or more. Fertilization of the undrained site ranks a distant third, and then only if it reduces the rotation age by 10 years; otherwise, it will be uneconomical to apply.In the case of the clear-cut area, planting bare-root stock on a mechanically prepared but undrained site without weed control ranked first among the 24 alternatives considered; the same treatment, but with weed control included, ranked second. Planting containerized seedlings on a mechanically prepared but undrained site with weed control ranked third, followed by planting bare-root stock on a mechanically prepared and drained site with weed control. In contrast, planting containerized seedlings on an unprepared site and with no weed control ranked as the least cost-effective method considered. 相似文献