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21.
基于高光谱成像的生鲜猪肉细菌总数预测建模方法研究 总被引:8,自引:0,他引:8
生鲜猪肉中细菌总数(TVC)超标会直接危害大众,为此研究验证高光谱成像技术结合相应的建模方法预测生鲜猪肉中TVC的可行性。针对非线性、小样本问题, 以及光谱维和空间维的大数据量问题,在综合比较偏最小二乘回归(PLSR)、人工神经网络(ANNs)和最小二乘支持向量机(LS-SVM)3种建模方法的基础上,最终选取了LS-SVM方法组建模型。3种建模方法综合比较的结果表明,LS-SVM同时兼顾了训练精度和泛化能力两方面的性能,使其都能做到最优,与标准平板菌落计数法所检测TVC的决定系数分别为0.987 2和0.942 6,校正均方根误差和预测标准均方根误差分别为0.207 1和0.217 6,其建模性能优于其他方法。研究结果表明,高光谱成像技术结合LS-SVM预测建模方法可作为快速、非破坏预测生鲜猪肉TVC的有效手段。 相似文献
22.
Radical benzenoid structures, i.e., those which cannot have all electrons paired, are known to possess much larger structure counts than closed-shell benzenoids of similar size. Building on our previous work, we report methods for calculating eigenvectors, eigenvalues, and structure counts for benzenoid radicals, diradicals, and radicals of higher multiplicity. When a series of such species is constructed by repeated addition of an aufbau unit, structure counts can usually be expressed as a polynomial in one or two variables. Structure counts for radical series generated by repeated circumscribing, however, cannot. 相似文献
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Pakawat Chammanee Kwannate Sombatsompop Apisit Kositchaiyong Narongrit Sombatsompop 《Journal of Macromolecular Science: Physics》2013,52(4):755-765
The anti-bacterial efficacy of medium-density polyethylene (MDPE) with various contents of different anti-bacterial agents was studied with respect to the effects of the anti-bacterial concentration, size and form of MDPE test-specimen, and the contact time. The three anti-bacterial agents used were carbendazim and zinc dimethyl dithiocarbamate (TROYSAN-S88), 2-hydroxypropyl3-piperazinyl-quinoline carboxylic acid methacrylate (HPQM), and silver substituted zeolite (ZEOMIC). The halo and plate-count-agar (PCA) tests were employed to assess the efficacies of the anti-bacterial performance. It was found that the inhibition zone from the halo test was most visible for the HPQM agent; the higher the HPQM content, the greater the inhibition zone. ZEOMIC exhibited no inhibition zone. The PCA test results suggested that after incorporating HPQM agent in the MDPE matrix, the% reductions of E. coli and S. aureus bacteria were as successfully high as 99.9% for all HPQM loadings. 相似文献
25.
蛋白质定量是探索疾病发生发展状况和寻找新药靶标的重要手段。在shotgun蛋白组学中,目前常用定量方法包括综合同位素标记后的质谱峰强度方法和无标记定量方法。根据数据类型无标记定量方法可以分为两类:基于鉴定蛋白的质谱数的方法和基于质谱峰强度的方法。本研究主要用EM算法改进基于鉴定蛋白质谱数的定量方法,并用免疫印迹实验获得的酵母全蛋白的丰度来验证EM算法改进后定量的有效性结果表明,改进后的质谱数和蛋白丰度的相关性比改进前有一定的提高。同时,利用这些数据对主要的几种基于鉴定蛋白的质谱数的模型进行了比较,发现PAI模型最好,SpS模型次之,emPAI模型最不适合于蛋白质定量。 相似文献
26.
In this paper we study varying‐coefficient models for count data. A Bayesian approach is taken to model the variability of the regression parameters. Based on a Kalman filter procedure the varying coefficients are estimated as the mode of the posterior distribution. All hyperparameters, including an overdispersion parameter in the negative binomial varying‐coefficient model (NBVC), are estimated as ML‐estimators using an EM‐type algorithm. A bootstrapping test of the fixed‐coefficient hypothesis against a varying‐coefficient alternative is proposed, which is evaluated running a simulation study. The study shows that the choice of a suitable count data model is of special importance in the framework of varying‐coefficient models. The methodology is illustrated analysing the determinants of the number of individual doctor visits. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
27.
We analyze the concept of credibility in claim frequency in two generalized count models–Mittag-Leffler and Weibull count models–which can handle both underdispersion and overdispersion in count data and nest the commonly used Poisson model as a special case. We find evidence, using data from a Danish insurance company, that the simple Poisson model can set the credibility weight to one even when there are only three years of individual experience data resulting from large heterogeneity among policyholders, and in doing so, it can thus break down the credibility model. The generalized count models, on the other hand, allow the weight to adjust according to the number of years of experience available. We propose parametric estimators for the structural parameters in the credibility formula using the mean and variance of the assumed distributions and a maximum likelihood estimation over a collective data. As an example, we show that the proposed parameters from Mittag-Leffler provide weights that are consistent with the idea of credibility. A simulation study is carried out investigating the stability of the maximum likelihood estimates from the Weibull count model. Finally, we extend the analyses to multidimensional lines and explain how our approach can be used in selecting profitable customers in cross-selling; customers can now be selected by estimating a function of their unknown risk profiles, which is the mean of the assumed distribution on their number of claims. 相似文献
28.
We study a noisy graph isomorphism problem, where the goal is to perfectly recover the vertex correspondence between two edge‐correlated graphs, with an initial seed set of correctly matched vertex pairs revealed as side information. We show that it is possible to achieve the information‐theoretic limit of graph sparsity in time polynomial in the number of vertices n. Moreover, we show the number of seeds needed for perfect recovery in polynomial‐time can be as low as in the sparse graph regime (with the average degree smaller than ) and in the dense graph regime, for a small positive constant . Unlike previous work on graph matching, which used small neighborhoods or small subgraphs with a logarithmic number of vertices in order to match vertices, our algorithms match vertices if their large neighborhoods have a significant overlap in the number of seeds. 相似文献
29.
Thomas Zaslavsky 《Geometriae Dedicata》2003,98(1):63-80
The ideal dimension of a real affine set is the dimension of the intersection of its projective topological closure with the infinite hyperplane. We obtain a formula for the number of faces of a real hyperplane arrangement having given dimension and ideal dimension. We apply the formula to the plane, to plaids, which are arrangements of parallel families in general position, and to affinographic arrangements. We compare two definitions of ideal dimension and ask about a complex analog of the enumeration. 相似文献
30.