近红外光谱的选择比率竞争群体分析的变量选择算法

光谱分析是化学计量学的一个重要应用方向,并已被广泛应用到各个领域,其中光谱变量选择又是光谱分析的重要环节。研究不同的变量选择方法客观地识别有用的信息变量和消除无关或干扰变量十分关键。提出了一种新的变量选择方法,命名选择比率的竞争性群体分析法(SRCMPA)。该算法采用选择比率,自适应加权采样和模型群体分析的思想,并结合了变量排列和指数递减函数方法。关键波长定义为多元线性回归模型中得分值较大的波长,将线性模型PLS下的选择比率的得分值作为评价各波长重要性的指标,然后,根据每个波长的重要性, SRCMPA依次从蒙特卡罗采样中选择N个波长子集,以迭代和竞争的方式运行。在每一次采样运行中,以固定比率的样品以建立校准的PLS模型并计算每个变量的选择比率值,基于排序选择比率的得分值和作为权重的归一化的SR(选择比率)得分值,采用指数递减函数的强制选择和自适应加权采样竞争选择的两步过程来选择关键变量。最后,应用交叉验证(CV)方法来选择具有最低交叉验证均方根(RMSECV)的子集作为最优子集。该算法已在小麦蛋白数据集和啤酒数据集上进行了测试,并使用三种高效算法作对比。通过对实验结果来评估算法优越性,该算法能够找到数据集的关键波长变量的最佳组合,并能用于解释感兴趣的化学特性,通过建模后的评价结果也是最佳的。该算法在啤酒光谱数据集的运行结果,相较于啤酒数据集的全光谱PLS模型,变量个数由567个减少到42个左右。并且模型的RMSECV由0.622下降到0.115, RMSEP由0.823减少到了0.263左右,预测精度分别提高了81.5%和68.1%。Q2_CV和Q2_test也分别由0.940, 0.852提高到了0.994和0.995。在小麦蛋白数据集的运行结果,相较于于小麦蛋白光谱数据集的全光谱PLS模型,变量个数由175个减少到18个左右。并且模型的RMSECV由0.607下降到0.292, RMSEP由0.519减少到了0.234左右,预测精度分别提高了51.9%和54.9%。Q2_CV和Q2_test也分别由0.748, 0.774提高到了0.931和0.839。

An adaptive learning rate GMM for background extraction

The rapidness and stability of background extraction from image sequences are incompatible,that is,when a conventional Gaussian mixture models (GMM)is used to rebuild the background,if the background regions of the scene are changed,the extracted background becomes bad until the transition is over. A novel adaptive method is presented to adjust the learning rate of GMM in a Hilbert space. The background extraction is treated as a process of approaching to a certain point in the Hilbert space,so the real-time learning rate can be obtained by calculating the distance between the two adjacent extracted background images,and a judgment method of the stability of background is got too. Compared with conventional GMM,the method has both high rapidness and good stability at the same time,and it can adjust the learning rate online. The experiment shows that it is better than conventional GMM,especially in the transition process of background extraction.

Microorganism Selection and Determination of Mixing Ratio of Selected Strains in the ＂Chao＂ Production

The paper presents the research for the purpose of selecting microorganisms into the production process of ＂chao＂ to improve the quality of ＂chao＂ products and ensure food safety. Several analytical methods such as determination of formal nitrogen, determination of the protease hydrolysis activity, sensory evaluation method, experimental procedure, methods of analysis and processing of empirical data were used in this study. The findings showed that two out of four selected microorganism strains （one strain of fungi and three strains of bacteria denoted NM1, VK1, VK2, VK3, respectively） were the most appropriate for the cooperation among them and the production of %hao＂, which were coded NM1 and VK1. The suitable mixing proportion of strains of NM1 and VK1 was determined at 1：1.25, compatible with the 1：100 ratio of the varieties of microorganisms （in powder form） to tofu.

Peak-to-average power ratio reduction using selective mapping with unequal power distribution

A new approach for peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) systems was proposed.This approach is based on assigning powers to the different subcarriers of OFDM using an unequal power distribution strategy.In addition,a reduced complexity selective mapping (RC-SLM) scheme was proposed.The proposed scheme is based on partitioning the frequency domain symbol sequence into several sub-blocks,and then each sub-block is multiplied by different phase sequences whose length is shorter than that used in the conventional SLM scheme.Then,a kind of low complexity conversions is used to replace the IFFT blocks.The performance of the proposed RC-SLM scheme along with the new approach was studied with computer simulation.The obtained results show that the proposed RC-SLM scheme is able to achieve the lowest computational complexity when compared with other low complexity schemes proposed in the literature while at the same time improves the PAPR reduction performance by about 0.3 dB.

Multiple Recursive Generator-Based Method for Peak-to-Average Power Ratio Reduction in Selected Mapping Without Side Information

Orthogonal Frequency Division Multiplexing(OFDM)has been used for many wireless communication systems.However,the main drawback of this method is the high Peak-to-Average Power Ratio(PAPR).Selected Mapping(SLM)is a technique used for solving the high PAPR problem in OFDM systems.In SLM,the original data sequence is multiplied by a set of predetermined phase sequences and multiple signals with different PAPRs are generated.Then,the one with the lowest PAPR is selected for transmission.The SLM method requires sending of some bits as Side Information(SI)for each data block,which is of critical importance to the receiver for decoding.The SI bits cause a decrease in the bandwidth efficiency;furthermore,incorrect SI detection leads to the loss of an entire data block.In this paper,we exhibit a new SLM technique by using a Multiple Recursive Generator(MRG),a method of generating pseudo random sequences,to send data without explicit SI bits.We show that the proposed technique performs very well in terms of the Bit Error Rate(BER),Probability of detection failure(Pdf)and PAPR reduction.

自然生境下盐角草的离子吸收-运输特征

通过对自然生境下盐角草的离子及部分重金属元素吸收-运输特性的分析，结果表明：①盐角草地上部Cl^-，Na^＋，K^＋含量显著（P≤0．05）大于地下部；②盐角草的离子吸收选择顺序为K^＋〉Mg^2＋〉Cl^-〉Na^＋〉SO4^2-〉Ca^2＋，而运输选择顺序为Na^＋〉Cl^-〉K^＋〉Mg^2＋〉SO4^2-〉Ca^2＋，反映了盐角草对离子（特别是K^＋，Na^＋，Cl^-）的优先选择性在吸收和运输方面的不同；③选择性比率SK,Na〉SMg，Na〉SCa，Na，说明稳定体内K^＋／Na^＋是盐角草耐盐的重要机制；④盐角草的离子吸收和运输存在一个梯度：根系相对于土壤介质，离子的吸收倍数为3．7～129．4；地上部相对于根的运输倍数为1．1～2．8，这种从土壤→根系→地上部离子转运成倍数的累积，既保证营养吸收的需求，又保证了低水势的维持；⑤污灌区盐角草的重金属含量除Cu外，Cd，Pb，As均是地下部含量〉地上部；Cu在地上部的富集系数〉1，As在地下部的富集系数为2．6，反映了盐角草对Cu，As的不同富集能力，因此，盐角草可用于盐渍化土壤重金属污染后的修复。

Effects of a sex ratio gradient on female mate-copying and choosiness in Drosophila melanogaster

In many sexually reproducing species, individuals can gather information about potential mates by observing their mating success. This behavioral pattern, that we call mate-copying, was reported in the fruit fly Drosophila rnelanogaster where females choosing between 2 males of contrasting phenotypes can build a preference for males of the phenotype they previously saw being chosen by a demonstrator female. As sex ratio is known to affect mate choice, our goal was to test whether mate-copying is also affected by encountered sex ratios. Thus, we created a gradient of sex ratio during demonstrations of mate-copying experiments by changing the number of females observ- ing from a central arena 6 simultaneous demonstrations unfolding in 6 peripheral compartments of a hexagonal device. We also tested whether the sex ratio experienced by females during demon- strations affected their choosiness （male courtship duration and double courtship rate） in subse- quent mate-choice tests. Experimental male：female sex ratio during demonstrations did not affect mate-copying indices, but positively affected the proportion of both males courting the female during mate-choice tests, as well as male courtship duration, the latter potentially explaining the for- mer relationship. As expected, the sex ratio affected female choosiness positively, and Drosophila females seem to have evolved a mate-copying ability independently of sex ratio, and a capacity to adapt their choosiness to male availability. This suggests that, as in many animal species, individuals, especially females, can adapt their mate choice depending on the current sex ratio.