传媒多元化意涵:政治、经验与规范三个维度的分析

传媒多元化是一个多元、开放的概念,在不同语境、不同维度、不同层次下言说具有不同的意涵和意义。在政治维度下,传媒多元化对应民主的三种模式发展出意见的自由市场、公共领域以及权力竞争的场域等三种理论原型;在传媒表现评价的经验维度下,传媒多元化包含数量多元、种类多元、反映多元、开放多元、近用多元等众多内涵和外延混杂的概念;而在规范的维度下,传媒多元化又对应着市场模式和社会价值模式两种政策模式,并发展出一套基于结构/内容区分逻辑的规制路径。在整合政治、经验与规范三个理论维度的探讨并充分借鉴前人研究的基础上,本研究最后归纳出一个传媒多元化的基本分析框架。

基于经验Rademacher复杂度的频繁项集发现随机抽样方法

提出一个方法,从数据集随机样本中提取高质量的近似频繁项集,具有较高概率保证该近似项集是数据集内真实频繁项集的超集。方法利用统计学习理论中的经验Rademacher复杂度,结合集中不等式,来获得一个基于数据集样本经验Rademacher复杂度的上界,随后应用项集的近似来推导出一个满足条件的样本大小,并根据该样本大小来挖掘近似频繁项集。实验采用T10I4D100K数据集来评估不同参数组合下的样本大小返回结果的正确率以及运行时间。实验结果表明基于抽样的研究方法具有一定的有效性和正确性,相比现有的基于VC维边界方法获得的样本大小更加紧凑。

基于数字相机、ASTER和MODIS影像综合测量植被盖度

选择我国北方温带典型草原作为研究对象,基于Bottom-up方法,采用地表实测和多尺度遥感综合测量的方法,建立基于地表实测与多尺度遥感数据综合测量的两阶段植被盖度经验模型。此外,还将该模型与常用的亚像元分解模型相比较,结果表明:1)两阶段经验模型可以较好地实现将地面数据扩展到中尺度空间范围,从而完成数据空间尺度的转换,提高大区域草地植被盖度的测量精度;2)MODIS遥感影像数据,结合地面数据和ASTER遥感影像数据可以较好地在区域范围内对北方典型草原的植被盖度进行估测;3)目前常用的亚像元分解模型,应用于中空间分辨率的MODIS影像,估测北方温度典型草原植被盖度的精度不够理想。

大学生学习投入影响因素分析

利用2013年"中国大学生学习与发展追踪调查"的随机抽样数据,以某二本院校学生为研究对象,通过因子分析和二元Logistic回归分析模型对学生学习投入提高的影响因素进行定量分析。研究结果表明,教育性因素比先赋性因素对学生学习投入的影响更为显著,学生主动合作学习度、学习经验丰富度和学业挑战度对本科学生学习投入起主导作用。

体育训练数据管理规则挖掘ID3算法的属性增益优化

针对标准ID3算法在数据规则挖掘的应用中还存在运算时间长、规则挖掘效果不好等问题。本文提出了一种基于属性增益优化ID3算法的体育训练数据规则挖掘模型,首先利用凸函数的性质来改进信息量公式,通过对数据集中属性选择标准的改变从而降低决策树的计算成本,减少决策树的生成时间,之后计算取值较多且不重要的属性信息时,将经验知识度参数引入从而避免取值少的属性被抛弃。此后又进行了专门的仿真实验,实验结果表明,与传统的算法相比,本文设计的经过改进的ID3算法在建树时间和规则数目这两个方面都具有更好的性能。

暴雨重现期的外推极限研究

置信区间常常可以给出相应于R年重现期重现水平的一个区间范围。这便存在一个问题,即使是基于很少的降雨数据,也可以估计无限大重现期的设计暴雨,而且此时的设计暴雨量会有很大的置信区间。因此,工程师们所关心的并不是这些置信区间的宽窄与否,而是基于有限的降雨数据,多大重现期的重现水平的估计是合理的,即多大程度的外推年限才是合理的。采用广义极值分布来进行年最大降雨量的模拟,并通过经验度理论给出一个合理的外推年限范围。应用结果表明:基于60 a的降雨数据,最大的外推年限为49.2 a。该结果与轮廓似然估计和delta估计得出的最大外推年限不超过50 a基本一致,因此该理论方法具有较高的可靠性与实用性。

暴雨极值分析

自然界中的降雨由于受到季风、台风等影响会表现出非季节性,因而不符合常规极值模型的假定。因此通过似然比检验,本文采取季度模型,将降雨分分组为四个季度,采用广义极值分布来进行月最大降雨量的模拟。另外采用经验度来进行最大重现期的估计,即多大程度的外推时段内是合理的。应用结果表明:基于90个月的降雨数据,夏季的降雨近似服从Gumbel分布,计算中存在一定的误差,而春、秋、冬最大的外推时段分别为54.2、68.6、84.6个月。该理论方法具有较高的可靠性与实用性。

Trust model based on individual experience

To improve the accuracy of node trust evaluation in a distributed network, a trust model based on the experience of individuals is proposed, which establishes a new trust assessment system by introducing the experience factor and the comparative experience factor. The new evaluation system considers the differences between individuals and interactive histories between nodes, which solves the problem that nodes have inaccurate assessments due to the asymmetry of nodes to a certain extent. The algorithm analysis indicates that the new model uses different deviating values of tolerance evaluation for different individuals and uses different updating values embodying node individuation when updating feedback credibility of individuals, which evaluates the trust value more reasonably and more accurately. In addition, the proposed algorithm can be used in various trust models and has a good scalability.

REGRESSION OF ACTIVITY COEFFICIENTS OF 1-1 TYPE POTASSIUM SALT AQUEOUS SOLUTIONS AT 25 ℃ AND OVER WHOLE CONCENTRATION RANGE

The Clegg Pitzer semi empirical thermodynamic equations were applied to the calculation of 1 1 type potassium salt aqueous solution.At 25 ℃ and over the whole concentration range,from 8 single electrolyte solutions (KF,KCl,KBr,KI,KOH,KNO 3,KClO 3,KBrO 3),the parameters W H 2O,KX ,U H 2O,KX ,and B KX were calculated,and then 8 solubility products were calculated.From 9 bi salt saturated aqueous solutions,the parameters W KXY ,U XY ,and Q H 2O,KXY were regressed,the F test was passed.

Springback and tensile strength of 2A97 aluminum alloy during age forming

The analysis of variance(ANOVA), multiple quadratic regression and radial basis function artificial neural network(RBFANN) methods were used to study the springback and tensile strength in age forming of 2A97 aluminum alloy based on orthogonal array. The ANOVA analysis indicates that the springback reaches the minimum value when age forming is performed at 210 °C for 20 h using a single-curvature die with a radius of 400 mm, and the tensile strength reaches the maximum value when age forming is performed at 180 °C for 15 h using a single-curvature die with a radius of 1000 mm. The orders of the importance for the three factors of pre-deformation radius, aging temperature and aging time on the springback and tensile strength were determined. By analyzing the predicted results of the multiple quadratic regression and RBFANN methods, the prediction accuracy of the RBFANN model is higher than that of the regression model.

Empirical Bayes Estimation for the Parameter of Two-dimen sional One-side Truncated Distribution Families with Linex Loss

In this paper, we construct the EB estim ation for the parameter of the two-dimensional one side truncat ed distribution fam ilies using Linex loss. The convergence rate of EB estimation is given and it is shown that the proposed empirical Bayes estimaiton can be arbitrarily close to 1 under certain conditions.

快速随机多核学习分类算法

多核学习是整合多个子核在一个优化框架内,从而寻求到多个子核之间的一个最佳线性组合,而且多核学习可以获得比单核学习更好的分类性能.受极限学习思想的启发,提出了快速随机多核学习分类方法.当满足极限学习的理论框架时,可以在构造核的过程中,对参数随机赋值,构造一种随机核.可以缩减子核的规模,加快了多核学习的计算时间,并且节省了内存空间,使得多核学习可以处理更大规模的问题.另外,通过使用经验Rademacher复杂度来分析多核学习的一般性误差,从而获得比原有多核学习更高的分类精度.结果表明,与经典的快速多核学习算法相比,文中提供的算法计算更快,占用内存空间更小,分类精度更高.

A new nonlinear empirical strength criterion for rocks under conventional triaxial compression

The failure criterion of rocks is a critical factor involved in reliability design and stability analysis of geotechnical engineering.In order to accurately evaluate the triaxial compressive strength of rocks under different confining pressures,a nonlinear empirical strength criterion based on Mohr-Coulomb criterion was proposed in this paper.Through the analysis of triaxial test strength of 11 types of rock materials,the feasibility and validity of proposed criterion was discussed.For a further verification,six typical strength criteria were selected,and the prediction results of each criterion and test results were statistically analyzed.The comparative comparison results show that the prediction results obtained by applying this new criterion to 97 conventional triaxial compression tests of 11 different rock materials are highly consistent with the experimental data.Statistical analysis was executed to assess the application of the new criterion and other classical criteria in predicting the failure behavior of rock.This proposed empirical criterion provides a new reference and method for the determination of triaxial compressive strength of rock materials.

Large Deviation Theorem for Empirical Measures of Degenerate Diffusion Processes

A class of multi dimensional degenerate diffusion processes X ε(t) in R r(r≥2) are considered and the asymptotic properties of empirical measures are investigated; here X ε(t) saitisfies the stochastic differential equation dX ε(t)=σ(X ε(t)) d W(t)+B(X ε(t)) d t+ εσ～(X ε(t)) d W(t),ε>0. X ε(t) are small random perturbations of the degenerate diffusion process X(t), which satisfies the stochastic differential equation dX(t)=σ(X(t)) d W(t)+B(X(t)) d t. A large deviation theorem for projection measures ν on R r-n (n<r) of empirical measures μ are proved

Establishing empirical relationships to predict grain size and tensile strength of friction stir welded AA 6061-T6 aluminium alloy joints

AA 6061-T6 aluminium alloy(Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high specific strength and good corrosion resistance.Compared with the fusion welding processes that are routinely used for joining structural aluminium alloys,friction stir welding(FSW) process is an emerging solid state joining process in which the material welded does not melt and recast.Joint strength is influenced by the grain size and tensile strength of the weld nugget region.Hence,an attempt was made to develop empirical relationships to predict grain size and tensile strength of friction stir welded AA 6061-T6 aluminium alloy joints.The empirical relationships are developed by response surface methodology(RSM) incorporating FSW tool and process parameters.A linear regression relationship was also established between grain size and tensile strength of the weld nugget of FSW joints.

Spatiotemporal characteristics of wind energy resources from 1960 to 2016 over China

In the paper,daily near-surface wind speed data from 462 stations are used to study the spatiotemporal characteristics of the annual and seasonal mean wind speed(MWS)and effective wind energy density(EWED)from 1960 to 2016,through the methods of kriging interpolation,leastsquares,correlation coefficient testing,and empirical orthogonal function(EOF)analysis.The results show that the annual MWS is larger than 3 m s-1 and the EWED is larger than 75 W m-2 in northern China and parts of coastal areas.However,the MWS and EWED values in southern China are all smaller than in northern China.Over the past 50 years,the annual and seasonal MWS in China has shown a significant decreasing trend,with the largest rate of decline in spring for northern China and winter for coastal areas.The annual MWS in some areas of Guangdong has an increasing trend,but it shows little change in southwestern China,South China,and west of Central China.Where the MWS is high,the rate of decline is also high.The main spatial distributions of the annual MWS and the annual EWED show high consistency,with a decreasing trend year by year.The decreasing trend of wind speed and wind energy resources in China is mainly related to global warming and land use/cover change.

Community Participation in Forest Resource Management in Nepal

Livelihood of the people in Nepal hills depends much upon forest resources in addition to farming as forest plays a critical role in the well being of the farming households where access to alternative sources, such as energy for cooking, nutrition for animals, materials for fertilizer and constructing materials for shelter, are limited. Thus, the well being of the people in the hills is directly affected by the management of these forest resources. This issue was addressed in this paper by examining the forest resource management practices and its effect on well being of rural people in two different stages in a village lying in the steep hill of Mahabharat Range in the southern hills of Kathmandu valley, Lalitpur District. The main ethnic/caste groups in the village are Brahmin/Chhetri (high Hindu caste), Magar/Tamang (Tibeto Burmans) and Kami (occupational caste: cobbler). Currently there are four community forest users groups, with mixed ethnic membership, organized to manage the forest resources. The endowments, weak institutional settings, before 1990 helped the Bhramins, Magars and Tamangs to get access into the private forest endowment, which made them easy to get access to the forest resources, mainly fuel wood, fodder and timber in 1990 and enhanced their well beings. But the socially backward Kami could not get benefit from the institutions that existed during that time and had less chance to enhance their well beings. After the set up of different endowments during late 1990s, i.e., hand over of forest management to usersgroupsin line with the concept of community forest, environment to use the forest resources became better for all the groups, along with the management of the forest. This enhanced the well beings of all the groups in the study village. However, the ability of Kami to use the forest resources to enhance their well beings was still lacking behind. The reason was partially due to the difference in endowments carried over from the endowments before 1990, and partly due to their occupational work and location of their settlements.

Effective forecast of Northeast Pacific sea surface temperature based on a complementary ensemble empirical mode decomposition–support vector machine method

The sea surface temperature （SST） has substantial impacts on the climate; however, due to its highly nonlinear nature, evidently non-periodic and strongly stochastic properties, it is rather difficult to predict SST. Here, the authors combine the complementary ensemble empirical mode decomposition （CEEMD） and support vector machine （SVM） methods to predict SST. Extensive tests from several different aspects are presented to validate the effectiveness of the CEEMD-SVM method. The results suggest that the new method works well in forecasting Northeast Pacific SST at a 12-month lead time, with an average absolute error of approximately 0.3℃ and a correlation coefficient of 0.85. Moreover, no spring predictability barrier is observed in our experiments.

Solubility of Emodin in Alcohols

Emodin is a kind of anthraquiones with pharmaceutical activities.The solubilities of emodin in ethanol,1-octanol,and ethanol+1-octanol at different temperatures were measured using an analytical method.The solubility of emodin in these solvents increased with an increase in temperature.With the temperature deviating from room temperature,the dependence of the solubility of emodin on temperature became a lot more remarkable.The solubility of emodin in ethanol was more sensitive to temperature than that in 1-octanol.The solubility data of emodin in the same species of solvent at different temperatures was correlated with an empirical equation.The calculated results agreed with the experimental data well.

A new model to predict roadheader performance using rock mass properties

Prediction of roadheader performance plays a significant role in the plan of tunnel construction, which is influenced by different key parameters, including rock strength, discontinuity in rock mass, type and specifications of roadheader machine, and brittleness. The main aim of this study is to build a robust empirical equation based on rock mass properties for the roadheader performance prediction. For achieving the aim, a dataset composed of roadheader performance rate and rock properties is established using the dataset compiled from an underground coal mine located in a remote rugged desert environment some 85 km south of Tabas City in mid east Iran. By using gathered data, the statistical analyses are conducted between rock mass properties and roadheader performance to find whether there is a significant relationship between input variables and roadheader performance. The results show that rock mass properties have a considerable impact on the rate of the roadheader performance. It is demonstrated that the proposed model can accurately predict the roadheader performance as a function of rock mass properties.