Estimating van Genuchten Model Parameters of Undisturbed Soils Using an Integral Method

The van Genuchten model is the most widely used soil water retention curve （SWRC） model. Two undisturbed soils （clay and loam） were used to evaluate the accuracy of the integral method to estimate van Genuchten model parameters and to determine SWRCs of undisturbed soils. SWRCs calculated by the integral method were compared with those measured by a high speed centrifuge technique. The accuracy of the calculated results was evaluated graphically, as well as by root mean square error （RMSE）, normalized root mean square error （NRMSE） and Willmott＇s index of agreement （1）. The results obtained from the integral method were quite similar to those by the centrifuge technique. The RMSEs （4.61 ×10^-5 for Eum-Orthic Anthrosol and 2.74 × 10^-4 for Los-Orthic Entisol） and NRMSEs （1.56 × 10^-4 for Eum- Orthic Anthrosol and 1.45 ×10^-3 for Los-Orthic Entisol） were relatively small. The 1 values were 0.973 and 0.943 for Eum-Orthic Anthrosol and Los-Orthic Entisol, respectively, indicating a good agreement between the integral method values and the centrifuge values. Therefore, the integral method could be used to estimate SWRCs of undisturbed clay and loam soils.

基于DSSAT模型不同灌水模式滇中水稻生长模拟

为探讨DSSAT水稻模型对滇中稻田淹水灌溉和控制灌溉模式的模拟精度,采用2017~2018两年云南寻甸县的水稻田间实测数据进行了分析。通过GLUE模块对2017年水稻淹水灌溉试验数据进行调参,得到一组精度较高的滇禾优34生长的遗传特性系数,并采用2018年淹水灌溉和控制灌溉试验数据进行验证。淹水灌溉和控制灌溉处理下开花期模拟值较实测值均提前了1 d,成熟期分别提前了1和2 d;颗粒重的相对误差分别为2.4%和6.6%;干物质(地上物质)的NRMSE值分别为10.1%和8.9%;叶面积指数的NRMSE值分别为10.40%和11.74%;分蘖数的NRMSE值分别为13.2%和15.2%。各生长指标模拟结果较好,DSSAT可作为滇中地区水稻不同灌水模式生长模拟和产量预测的一种方法。

CARRIER FREQUENCY OFFSET ESTIMATION FOR INTERLEAVED OFDMA UPLINK BASED ON SUBSPACE PROCESSING

This paper investigates Carrier Frequency Offset (CFO) estimation in the uplink of the Orthogonal Frequency-Division Multiple Access (OFDMA) systems with the interleaved subcarrier assignment. CFOs between the transmitters and the uplink receiver will destroy orthogonality among different subcarriers, hence resulting in inter-carrier interference and multiuser interference. A two-stage frequency offset estimation algorithm based on subspace processing is proposed. The main advantage of the proposed method is that it can obtain the CFOs of all users simultaneously using only one OFDMA block. Compared with the previously known methods, it not only has a relatively low implementation complexity but is also suitable for random subchannel assignment.

Interleaved-OFDMA中基于子空间的上行链路载波频偏估计方法

在OFDMA系统中,通过为每个用户分配不同的子载波可以实现并行数据传输.采用Interleaved子载波分配方法可以提高频率分集和系统容量,但是发射机和接收机之间的载波频率偏移会破坏子载波间的正交性,从而导致本用户的载波间干扰(ICI)以及用户间干扰(MUI).本文提出了一种基于子空间的两阶段频偏搜索方法,该方法只采用一个OFDMA符号块就可以实现Interleaved-OFDMA上行链路多个用户频偏的联合估计,并且不需要知道接入的用户个数及用户所占用的子信道,因此适用于随机分配子信道的情况.仿真结果验证了算法的精确度和有效性.

Bertalanffy-Pütter Models for the Growth of Tropical Trees and Stands

The Bertalanffy-Pütter (BP) five-parameter growth model provides a versatile framework for the modeling of growth. Using data from a growth experiment in literature about the average size-at-age of 24 species of tropical trees over ten years in the same area, we identified their best-fit BP-model parameters. While different species had different best-fit exponent-pairs, there was a model with a good fit to 21 (87.5%) of the data (“Good fit” means a normalized root-mean-squared-error NRMSE below 2.5%. This threshold was the 95% quantile of the lognormal distribution that was fitted to the NRMSE values for the best-fit models for the data). In view of the sigmoidal character of this model despite the early stand we discuss whether the setting of the growth experiment may have impeded growth.

基于烟草热解差异度分析的烟叶替代方法

为便于卷烟配方维护,基于热重分析手段,建立120种烟叶的热重数据库,采用标准均方根误差NRMSE评价烟草样品之间的热解差异度。在配方烟叶间开展烟叶替代实验,针对某牌号卷烟A中9种需要被替代的单等级烟叶,通过热解差异度计算,在120种烟叶中选择与被替代单等级烟叶热解差异度最小的烟叶,形成基于热解差异度替代方案,并与人工替代方案进行对比。结果表明:(1)基于热解差异度替代方案的卷烟与原始配方卷烟热解差异度更为接近,NRMSE为3.44%,而人工替代方案的卷烟热解差异度NRMSE为4.88%。(2)基于热解差异度替代方案的卷烟与人工替代方案的卷烟相比,其与原始配方卷烟的常规化学成分和感官特性更接近,两种替代方案的卷烟与原始配方卷烟的物理指标以及焦油、烟碱和CO释放量较接近。(3)在验证实验中,针对某牌号卷烟B中5种需要被替代的单等级烟叶,通过热解差异度计算形成3种替换方案,其感官评吸和烟气分析结果表明,最佳替代方案可满足应用要求,进一步说明基于热解差异度的替代方法可达到人工替代的水平。

基于热重的烟草热解差异度分析

为了研究不同年份、不同区域以及不同部位之间烟草热解差异度,应用热重分析技术绘制了20种具有代表性的烟草微分热重曲线图,采用标准均方根误差NRMSE评价烟草样品之间的热解差异度,并利用SPSS软件的多因素方差分析研究年份、区域和部位对烟草热解差异度的影响程度。结果表明:在所研究的20种代表性烟草样品范围内,部位和省级对烟草热解差异度存在极显著的影响,县级、年份和市级对烟草热解差异度的影响不显著。

一种无参数的微阵列缺失值填补方法(英文)

微阵列数据中的缺失值会对随后的数据分析造成影响。因此,正确地估计这些缺失值是很必要的。将一个k值选取算法结合到有序的局部最小二乘填补算法中,提出了一种无参数的缺失值填补方法(SLLSkimpute)。该方法的三个特点是:第一,无需事先确定参数;第二,针对不同的目标基因使用不同数目的邻居基因;第三,有序地估计缺失值,并有选择地将已得到的估计值应用到后续的估计过程中。实验结果证实了该算法的有效性,其估计性能优于其它一些常用的填补方法。

基于子空间的交织OFDMA上行载波频偏估计

为了实现采用交织子载波分配方法的正交频分多址(orthogonal frequency division multiplexing access,OFDMA)上行链路多个用户频偏的联合估计,提出一种基于子空间的两阶段频偏搜索方法。由于多重信号分类法(multiple signal characteristic,MUSIC)的采用,使得该方法具有较高的精确度,并且该方法不需要知道接入的用户个数及用户所占用的子信道;因此适用于随机分配子信道的情况。仿真结果表明:当信噪比大于5 dB时,其标准均方根误差小于子载波间隔的1%,满足宽带无线接入系统关于载波频率偏差应小于子载波间隔2%的频率同步要求。

基于热重的卷烟纸质量稳定性研究

为研究卷烟纸的质量稳定性,跟踪某牌号卷烟35个月份的卷烟纸和烟丝的热重DTG曲线,引入标准均方根误差NRMSE(Normalized root mean squared error)计算不同样品DTG曲线中热解峰(400～625K)和氧化峰(625～800 K)的差异度,并将NRMSE结合焦油和CO的释放量波动来评价卷烟纸的质量稳定性。结果表明:(1)此牌号卷烟焦油和CO的波动主要来自于卷烟纸的质量波动;(2)卷烟纸DTG曲线上热解峰NRMSE<10%以及氧化峰NRMSE<20%所对应卷烟的焦油和CO释放量接近,差值≤0.5 mg;(3)热解峰NRMSE>10%以及氧化峰NRMSE>20%时,氧化峰NRMSE对焦油和CO释放量呈显著性影响;(4)卷烟纸常规指标(定量,透气度,助剂含量,Na、K和Ca的含量)接近的卷烟纸样品,其热重DTG曲线依然存在较大的差异,并对焦油和CO的释放量造成明显的影响;(5)将某个月份卷烟纸的DTG曲线与标准卷烟纸的DTG曲线进行配对来预测焦油和CO的释放量,预测相对偏差均小于5%。