多元函数未知参数的区间估计

Ｆ（ｘ，ｙ，ｕ；ａ１，ａ２，…ａｍ）＝０中仅ａ１，ａ，…ａｍ未知时参考文献「１」给出了ａｊ（ｊ＝１，２，…ｍ）的一种估计，它反映了函数类型确定后合理的选取函数中某些未知参数，使函数在一定意义下表现出最佳的观测结果，但在实际观测中，ａ＾２常常也是未知的，同样需要估计，本文给出ａ＾２的点估计ａｊ（ｊ＝１，２，…ｍ）的区间估计。     

利用极大似然估计值评定饲料营养价值

本文作者提出了利用极大似然估计值评定饲料营养价值的方法，并说明了这种估计值是最佳线性无偏估计值和用于评定饲料营养价值的可行性，举出实例说明了方法的应用。     

浅谈建设工程设计阶段的造价管理

本文主要论述了建设工程设计阶段的造价管理的重要意义及在实际工作中所存在的一些问题。浅谈对设计阶段造价管理的认识,提出做好设计阶段的造价管理的建议性意见。     

关于多项式Julia集的几何估计

主要讨论几类具有高拓扑度的多项式Ｐ的Ｊｕｌｉａ集Ｊ（Ｐ）的性质，包括（Ⅰ）对Ｊ（Ｐ）的范围的估计：（Ⅱ）一类特殊的具有相同Ｊｕｌｉａ集且同度的多项式间的共轭性。     

概率P（X〉E（X））的估计问题

Let X_1, X_2,...X_n be independent and identically distributed samples deawn from a population x with distribution F. The estimation of the probability P(X> E(X))=1-F(E(X)) is discussed in this article. Some strong consistent estimators are proposed, and     

Validation of an efficient visual method for estimating leaf area index in clonal Eucalyptus plantations

Leaf area index (LAI) is a key ecophysiological parameter in forest stands because it characterises the interface between atmospheric processes and plant physiology. Several indirect methods for estimating LAI have been developed. However, these methods have limitations that can affect the estimates. This study aimed to evaluate the accuracy and applicability of a visual method for estimating LAI in clonal Eucalyptus grandis × E. urophylla plantations and to compare it with hemispherical photography, ceptometer and LAI-2000^® estimates. Destructive sampling for direct determination of the actual LAI was performed in 22 plots at two geographical locations in Brazil. Actual LAI values were then used to develop a field guide with photographic images representing an LAI range of 1.0–5.0 m² m^?2 (leaf area/ground area). The visual LAI estimation guide was evaluated with 17 observers in the field. The average difference between actual LAI and visual LAI estimation was 12% and the absolute difference between the two methods was less than or equal to 0.5 m² m^?2 in 77% of plots. Pearson’s correlation coefficients were high between actual LAI and hemispherical photographs (0.8), visual estimation (0.93) and LAI-2000^® (0.99) and low for the ceptometer (0.18). However, absolute values differed among methods, with the average difference between the actual and estimated LAI of [12]% for visual estimation, 28% for the LAI-2000^®, 37% for the ceptometer and ?43% for hemispherical photographs. The LAI-2000^® and ceptometer overestimated LAI in all plots, whereas hemispherical photographs underestimated the values in all measurements, showing that these methods need calibration to be used. No differences were observed between actual LAI and visual estimates across stand ages of 2–8 years and LAI of 1.5–5.3 m² m^?2 (P > 0.05). The results show that visual estimation of LAI in Eucalyptus stands is a practical method that is unaffected by atmospheric characteristics and can be used on an operational scale.     

Stand-scale transpiration estimates in a Moso bamboo forest: (I) Applicability of sap flux measurements

The applicability of sap flux (F_d) measurements to bamboo forests has not been studied. This study was undertaken to establish an optimal and effective design for stand-scale transpiration (E) estimates in a Moso bamboo forest. To this aim, we validated F_d measurements in Moso bamboos in a cut bamboo experiment. In addition, we analyzed how sample sizes affect the reliability of E estimates calculated from F_d and conducting culm area (A_{S_b}). In the cut bamboo experiments, we found that F_d measurement using a 10 mm probe was a valid means of determining the water-use behavior of a Moso bamboo, although a specific correction was needed. Furthermore, we calculated E from stand A_{S_b} (A_{S_stand}) and mean stand F_d (J_S). Employing Monte Carlo analysis, we examined potential errors associated with sample size in E, A_{S_stand}, and J_S using an original dataset with A_{S_b} and F_d measured for 40 and 16 individuals, respectively. Consequently, we determined the optimal sample size for both A_{S_stand} and J_S estimates as 11. The optimal sample sizes for J_S were almost the same under different vapor pressure deficit and soil moisture conditions. The optimal sample size for J_S at the study site was less than that of a coniferous plantation in the same region probably owing to small individual-to-individual variations in sap flux in the Moso bamboo forest. Our study concludes that sap flux measurements are an applicable technique for assessing water use in Moso bamboo forests.     

差分GPS技术在谷物测产系统中的应用

目前，在谷物测产系统中，开始应用动态差分GPS技术建立产量计算模型和小区产量分布图，以获得农作物小区产量信息。为此，介绍了GPS定位原理、方法以及动态差分GPS技术，并进行了差分定位试验和分析。差分GPS在谷物产量图生成中的应用表明，差分GPS技术能满足田间谷物测产的需要。     

巨尾桉树皮率估测模型的研究

利用巨尾桉(EUCALYP GRANDIS×UROPHYLLA)实测数据,采用数学模型模拟的手段,研究、分析树皮体积率和树皮干重率的估计方法。结果表明,用胸径估计树皮体积率和树皮干重率的效果与用树干带皮材积估计树皮体积率和树皮干重率的效果相近,树皮体积率的估计精度优于树皮干重率的估计精度。     

Effects of estimation length on parameter estimates of geometric Brownian motion for log price dynamics

We investigated an effect of the estimation length of the time-series data on the parameter estimates of geometric Brownian motion for log prices. This is to examine how much the estimates vary depending upon the estimation length of the data for the simulation purpose of stochastic modeling. Using the monthly time-series data for akamatsu, sugi, and hinoki from January 1975 to December 2000, our analysis shows that the longer the estimation length, the more stable the estimated value of the drift coefficient and the volatility coefficient of geometric Brownian motion become, implying less variability in the estimates needed for the simulation analysis. On the other hand, the shorter estimation length would tend to reflect such a sudden change in the data as the oil shock or the short-term decreasing or increasing tendency, which results in the large degree of variability in parameter estimates. This stems from the fact that the long estimation length regards a short-term price changes as an intrinsic part of price volatility. These results imply that when conducting a scenario analysis under stochastic environments, for the shorter estimation length, the wider range of parameter settings should be incorporated into the analysis.