自变量也含误差的非线性模型拟合

该文用最小平方距离法详细推导了部分或全部自变量也含随机误差的非线性回归模型的参数估计方法。方差已知和方差未知两种情况都进行了讨论。     

Experimental osteoarthritis in the rabbit. II. A new method to estimate the oxygen consumption and diffusion capacity in the synovial membrane of the knee

The oxygen supply to the joint cartilage depends on the oxygen transport from the capsular arteries to the capillaries, the oxygen diffusion across the synovial membrane and the oxygen transport through the synovia. In osteoarthritis the resistance to transport across all 3 barriers may be increased because of the joint effusion, the elevated intraarticular pressure and the inflammatory changes of the synovial membrane.In the present study we describe a method to determine 2 important parameters affecting the oxygen transport through the synovial membrane: the oxygen consumption and diffusion capacity of the membrane. The principle of the method is to perfuse the joint cavity of the knee by saline saturated with air and to record the relationship between the oxygen partial pressure in the outflowing perfusate and the perfusion rate.The values found for the diffusion capacity and oxygen consumption were 0.039 ± 0.013 μl O₂/min/Torr and 0.93 ± 0.90 μl O₂/min (mean ± s).     

基于最小二乘支持向量机的车用铂电阻温度传感器非线性校正

依据铂电阻温度传感器样本,提出了一种采用最小二乘支持向量机辨识传感器逆模特征的校正铂电阻温度传感器非线性误差的原理和方法.该方法不需逆模型函数形式的先验知识,能够保证找到的极值解就是局最优解,具有较好的泛化能力.实例应用表明,其检测精度可达到0.1 ℃,铂电阻温度传感器非线性校正效果好.     

基于偏最小二乘的无线传感网多跳定位算法

提出了一种基于偏最小二乘的多跳定位算法(ML-PLS)。算法借助偏最小二乘对已知节点间的跳数与真实距离的建模,通过跳数、距离两者间的最大协方差共同推动节点位置的估计。ML-PLS算法对复杂部署环境具有较强的适应性,克服了传统算法只适用于各向同性网络的不足。仿真结果表明,ML-PLS算法定位精确度高且性能较稳定,并能适应不同网络环境。     

我国棉花品种区域试验精确度的演变分析

农作物区域试验精确度分析是品种和试验环境科学评价的基础。本研究分析了2000―2014年期间长江流域、黄河流域和西北内陆棉区国家棉花区试的试验精确度分布与演变动态,并分析比较了棉花12个主要性状的精确度差异,旨在全面分析和评价我国棉花品种区域试验精确度的发展水平和演变规律,为全国棉花品种区域试验的合理布局和优化设计提供参考依据。研究结果表明:(1)单年单点棉花区域试验能鉴别出5%、8%、10%、12%、15%和20%品种间差异的比率分别约为20%、50%、70%、83%、92%和98%。(2)单年多点棉花区域试验精确度呈逐年提高的演变趋势,RLSD0.05(RLSD,relative least significant difference)由2000年的11.43%下降到2014年的7.1%,其中长江流域的RLSD0.05已经连续9年、黄河流域棉区的RLSD0.05连续4年稳定在5%以下,可以稳定地鉴别品种间5%的差异;西北内陆棉区的RLSD0.05也呈逐年下降趋势,目前可以可靠鉴别品种间10%的差异。(3)棉花12个主要性状的试验精确度差异显著,其中皮棉产量和结铃数的精确度较低,霜前花率、衣分、纤维长度和生育期的精确度较高,其余性状精确度中等。     

Rapid prediction of wood crystallinity in <Emphasis Type="Italic">Pinus elliotii</Emphasis> plantation wood by near-infrared spectroscopy

Crystallinity is an important property of woody materials; it responds to tree growth traits, structure, and chemical composition, and has a significant effect on Young’s modulus, dimensional stability, density, and hardness, etc. The ability of near-infrared (NIR) spectroscopy coupled with multivariate analysis to rapidly predict the crystallinity of slash pine (Pinus elliotii) plantation wood was investigated. The results showed that the NIR data could be correlated with the X-ray diffraction (XRD)-determined crystallinity of slash pine wood by use of partial least squares (PLS) regression, producing excellent coefficients of determination, r ², and root mean square error of calibration, RMSEC. The use of either reduced spectral ranges or the selection of certain wavelengths consistent with known chemical absorptions did not have any detrimental effect on the quality of PLS models allowing the use of inexpensive, small, and portable spectrometers. These studies show that NIR spectroscopy can be used to rapidly predict the crystallinity of slash pine wood.     

基于不同预处理的椴树木材基本密度近红外光谱估测及模型优化

【目的】木材的基本密度在木材质量等级评定中起着重要的作用,是木材分流及精细化利用的重要依据。利用近红外光谱技术,实时监测木材性质,掌握木材性质的变化,为进一步制定和改善林木培育方法提供理论依据。【方法】借助树木生长锥对椴树活立木取样,以椴树样品基本密度真值和近红外光谱数据为输入,分别通过卷积平滑、一阶导数和二阶导数预处理方法来实现近红外光谱数据的预处理,建立了基于偏最小二乘法(PLS)的椴树木材基本密度的近红外估测模型。【结果】在350~2 500 nm波段范围内,一阶导数预处理的椴树木材基本密度模型是最优的,校正集相关系数为0.964 8,校正均方根误差为0.002 7,验证集相关系数为0.943 2,预测均方根误差为0.003 3。在对近红外光谱数据进行去噪优化处理,构建椴树木材基本密度模型后,在500~2 300 nm波段范围内,一阶导数预处理椴树木材基本密度模型依旧最优,其校正集相关系数为0.987 1,校正均方根误差为0.001 6,验证集的相关系数是0.948 6,预测的均方根误差是0.002 1。【结论】选择特定的预处理方法,结合样本特征,建立椴树木材基本密度模型,可以显著降低建模成本,提高模型预测精度,快速测定椴树木材的基本密度。     

橡胶树立木材积表的编制研究

在雷州半岛地区，对幼龄、中龄和老龄橡胶林进行了调查，按径级测定了５０株标准木的材积，应用加权最小二乘法拟合了在材积方程建造上常用的１６个方程。采用ＦＩ（Ｆｕｒｎｉｖａｌ′ｓｉｎｄｅｘ）指数选择最佳拟合方程，橡胶树单木带皮、去皮材积最佳拟合方程分别为：Ｖｄ＝３．８×１０－５Ｄ２Ｈ－０．００００６３；Ｖｑ＝３．１×１０－５Ｄ２Ｈ－０．０００１０２。两模型总的系统偏差都小于±３％，满足编制材积表要求，并利用模型编制了橡胶树立木材积表，可供生产中应用、参考。     

System Identification on Small-scale Unmanned Helicopter

This paper presents a fading memory based least squares identification method. Compared with the traditional system identification method applied on small scale unmanned helicopter, this method can reduce processing load and improve processing stability during identification. ARMAX model and MIMO model of small scale unmanned helicopter are sonstructed in this way and then do simulation on the models. The result shows that model of MIMO is more precise on representing the helicopter system.