长牡蛎F3 代快速生长选育群体生长特性的研究

采用模型拟合方法研究了长牡蛎(Crassostrea gigas)F3代快速生长选育群体不同时期各生长性状的发育规律。结果表明,长牡蛎幼虫期壳高(SH)、壳长(SL)对日龄(t)的回归遵循Logistic模型,生长方程分别为SH=455.612/(1+9.500e-0.142t),R2=0.999;SL=462.476/(1+8.026e-0.108t),R2=0.996。幼虫期壳高与壳长成直线相关,回归方程为SL=0.76SH+18.82,R2=0.994。长牡蛎养成期各生长性状呈现明显的季节变化,壳高(SH)、壳长(SL)、壳宽(SW)和总质量(TW)对月龄(X)的多项式回归方程分别为SH=-0.0297X4+1.0365X3-12.0220X2+57.6500X-68.9260,R2=0.985;SL=-0.0173X4+0.5893X3-6.5702X2+30.2420X-34.4150,R2=0.986;SW=-0.0068X4+0.2620X3-3.2806X2+16.9170X-22.1410,R2=0.956;TW=-0.0219X4+0.8234X3-10.1680X2+50.7040X-85.4110,R2=0.972。壳高、壳长、壳宽与总质量均呈幂函数相关,回归方程分别为SH=23.645TW0.3213,R2=0.998;SL=12.337TW0.3776,R2=0.995;SW=6.611TW0.3589,R2=0.981。     

一种迭代法的圆曲线拟合方法

针对在实际测量工作中量测圆心坐标及半径时存在的问题,该文基于迭代法的思想,推导了一种圆曲线拟合的方法,并用实例数据进行了检验。结果显示,该方法在离散点均匀采集或非均匀采集的情况下均具有良好的拟合效果,与目前在圆曲线拟合方法中普遍采用的最小二乘法相比,具有同样高的拟合精度,验证了该拟合方法的正确性与可行性。     

岩石疲劳损伤模型的参数估计方法研究

岩石是一种非均质的复杂地质材料,其疲劳损伤演化具有明显的3阶段发展规律。倒S型非线性疲劳累积损伤模型可以很好地描述这一规律。应用倒S型模型开展损伤计算和疲劳寿命分析的先决条件是确定出不同应力水平下的模型参数,而运用Levenberg-Marquardt法进行倒S型曲线拟合的结果表明,不用任何优化方法而随意选取参数初始值时迭代收敛到最优解的概率很低。因此,提出运用有限组合法估算初始值,即在参数可行域中均匀布点,以这些点为起始点分别实施一次Levenberg-Marquardt优化计算,取残差平方和最小的一组参数作为第2次Levenberg-Marquardt拟合计算的初始值。试验结果表明,以有限组合法估算参数初始值,Levenberg-Marquardt迭代计算总能收敛到最优解。     

GPS高程测量在也门Block69中的应用分析

GPS高程测量代替常规水准测量的技术和方法已经成为这些年来许多大地测量学者们研究的热门课题之一,本文简单地介绍了GPS高程测量的模型及其适用范围,并通过在也门Block 69的应用分析,说明了在高程异常值变化平缓的平坦地区,只需测定少量（不少于3个）较均匀分布于测区的已知高程控制点,采用平面拟合法,拟合精度就能够达到测区测量精度的要求。     

球面小波分析技术及在全球重力模型中的应用

在介绍球面小波理论的基础上,推导和比较了几种球面小波,分析了最新地球重力模型——EGM96,以此为依据,把球面小波多分辨分析用于计算全球自由空气异常及重力大地水准面,并对处理结果做出解释。     

时域反射仪（TDR）测定土壤含水量标定曲线评价与方案推荐

时域反射仪（Time Domain Reflectometry）可用于室内和田间快速、 准确、 自动测定土壤含水量, 是目前应用最广泛的土壤含水量测定方法之一。适宜的土壤含水量标定曲线（即土壤表观介电常数和土壤含水量之间的关系）是TDR准确测定土壤含水量的关键。目前文献中存在大量的土壤含水量标定曲线, 但尚未有研究对这些标定曲线进行系统的验证和分析评价。因此, 它们的准确性和适用范围尚不明晰, 严重影响到与土壤含水量测定相关的研究。通过查阅大量国内外文献, 收集整理了一系列土壤含水量标定曲线的经验公式（19个）和半经验半物理模型（5个）, 并利用大量的文献实测数据对其进行综合评价。同时运用均方根差（RMSE）, 平均误差（AD）, 纳什效率系数（NSE）等三个指标对比分析和评价这些标定曲线的准确性和可靠性。研究结果表明： 经验公式中Topp、 Roth（1992）2、 Jacobosen、 Yoshikawa2、 Alharathi模型和半经验模型中Malicki1公式及其修订模型综合性能较好。研究成果可为利用TDR准确测定土壤含水量及土壤含水量标定曲线的选择提供参考和指导。     

Flood‐based analysis of high‐magnitude sediment transport using a non‐parametric method

Upland erosion and the resulting reservoir siltation is a serious issue in the Isábena catchment (445 km² Central Spanish Pyrenees). During a three‐month period, water and sediment fluxes have been monitored at the catchment outlet (Capella), two adjacent subcatchments (Villacarli, 41 km²; Cabecera, 145 km²) and the elementary badland catchment Torrelaribera (8 ha). This paper presents the results of the monitoring, a method for the calculation of a sedigraph from intermittent measurements and the derived sediment yields at the monitored locations. The observed suspended sediment concentrations (SSCs) demonstrate the role of badlands as sediment sources: SSCs of up to 280 g l^?1 were encountered for Villacarli, which includes large badland areas. SSCs at the Cabecera catchment, with great areas of woodland, barely exceeded 30 g l^?1. SSCs directly at the sediment source (Torrelaribera) were comparable to those at Villacarli, suggesting a close connection within this subcatchment. At Capella, SSCs of up to 99 g l^?1 were observed. For all sites, SSC displayed only a loose correlation with discharge, inhibiting the application of a simple sediment rating curve. Instead, ancillary variables acting as driving forces or proxies for the processes (rainfall energy, cumulative discharge, rising/falling limb data) were included in a quantile regression forest model to explain the variability in SSC. The variables with most predictive power vary between the sites, suggesting the predominance of different processes. The subsequent flood‐based calculation of sediment yields attests high specific sediment yields for Torrelaribera and Villacarli (6277 and 1971 t km^?2) and medium to high yields for Cabecera and Capella (139 and 410 t km^?2) during the observation period. In all catchments, most of the sediment was exported during intense storms of late summer. Later flood events yield successively less sediment. Relating upland sediment production to yield at the outlet suggests considerable effects of sediment storage within the river channel. Copyright © 2008 John Wiley & Sons, Ltd.     

大洋调查中海山地磁测量的静日变化校正方法

针对大洋调查中海山地磁测量时难以设立静日变化观测站的问题,提出了一种基于多项式拟合最小二乘算法的日变校正方法,即假设静日变化磁场可以用一个关于时间的高阶多项式来拟合,利用主测线和联络测线交点误差的最小二乘估计求得多项式的系数,从而得到静日变化曲线。从调查测得的磁场中减掉静日变化磁场即可得消除静日变化影响后的海山地磁异常。理论模型和实际资料处理都表明,这种方法不仅可以较好地消除静日变化的影响,而且用计算机实现也简单。为了提高静日变化校正结果,讨论了为提高静日变化校正效果,在大洋调查中测量海山地磁时应注意的几个问题。     

An interconnect width and spacing optimization model considering scattering effect

As the feature size of the CMOS integrated circuit continues to shrink, the more and more serious scattering effect has a serious impact on interconnection performance, such as delay and bandwidth. Based on the impact of the scattering effect on latency and bandwidth, this paper first presents the quality-factor model which optimises latency and bandwidth effectively with the consideration of the scattering effect. Then we obtain the analytical model of line width and spacing with application of curve-fitting method. The proposed model has been verified and compared based on the nano-scale CMOS technology. This optimisation model algorithm is simple and can be applied to the interconnection system optimal design of nano-scale integrated circuits.     

砂土的抗剪强度与干密度的曲线拟合

利用曲线拟合的最小二乘法原理，确定砂土在某垂直压力下的抗剪强度与干密度的关系，并绘制曲线图，可避免人工处理数据的随意性，减小了误差。