基于加权α优势关系的多属性决策排序方法*

α优势粗糙集模型利用简单平均法赋权多个阈值α的排序结果,忽视数据集本身信息,导致不同数据集的排序质量差异性较大.针对此问题,文中提出基于加权α优势关系的优势度排序方法.首先运用α优势粗糙集方法详细分析决策对象.在此基础上,为了克服α主观赋权导致多属性决策排序结果中“并列”决策现象存在的不足,依据排序结果采用2种准则赋权α,并融合2种准则下所有对象的综合优势度,进一步细化排序结果.最后在具体算例中对比分析其它排序方法,验证文中方法的可行性和有效性.     

Analysis of driver and passenger crash injury severity using partial proportional odds models

The question of whether crash injury severity should be modeled using an ordinal response model or a non-ordered (multinomial) response model is persistent in traffic safety engineering. This paper proposes the use of the partial proportional odds (PPO) model as a statistical modeling technique that both bridges the gap between ordered and non-ordered response modeling, and avoids violating the key assumptions in the behavior of crash severity inherent in these two alternatives. The partial proportional odds model is a type of logistic regression that allows certain individual predictor variables to ignore the proportional odds assumption which normally forces predictor variables to affect each level of the response variable with the same magnitude, while other predictor variables retain this proportional odds assumption. This research looks at the effectiveness of this PPO technique in predicting vehicular crash severities on Connecticut state roads using data from 1995 to 2009. The PPO model is compared to ordinal and multinomial response models on the basis of adequacy of model fit, significance of covariates, and out-of-sample prediction accuracy. The results of this study show that the PPO model has adequate fit and performs best overall in terms of covariate significance and holdout prediction accuracy. Combined with the ability to accurately represent the theoretical process of crash injury severity prediction, this makes the PPO technique a favorable approach for crash injury severity modeling by adequately modeling and predicting the ordinal nature of the crash severity process and addressing the non-proportional contributions of some covariates.     

Distinguishing nanowire and nanotube formation by the deposition current transients

ABSTRACT: High aspect ratio Ni nanowires (NWs) and nanotubes (NTs) were electrodeposited inside ordered arrays of self-assembled pores (approximately 50 nm in diameter and approximately 50 um in length) in anodic alumina templates by a potentiostatic method. The current transients monitored during each process allowed us to distinguish between NW and NT formation. The depositions were long enough for the deposited metal to reach the top of the template and form a continuous Ni film. The overfilling process was found to occur in two steps when depositing NWs and in a single step in the case of NTs. A comparative study of the morphological, structural, and magnetic properties of the Ni NWs and NTs was performed using scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometry, respectively.     

Can human disturbance promote nestedness? Songbirds and noise in urban parks as a case study

Several explanations have been proposed to understand the existence of nested subset patterns in biological communities, including selective extinction, differential colonization, nested species-habitat relationships, random placement from a common species pool, and human disturbance. We study if songbird assemblages inhabiting urban parks in the Puebla-Cholula Metropolitan Area (Mexico, an urbanizing country) exhibit a nested subset pattern, and apply information-theoretic (IT) methods to rank the likelihood of the abovementioned processes as competing hypotheses explaining nestedness. A total of 21 study sites were considered, where 38 Passeriformes species were retained for nestedness analyses (13 species with preferences for forest habitats, and 25 for non-forest habitats). Neither the number of species per site nor the number of sites per species followed expectations from the random placement hypothesis. In addition, using the NODF index for measuring nestedness and different null models for generating random matrices, we found that songbird assemblages inhabiting urban parks were significantly more nested than expected. The IT approaches we followed evidenced that the two most important ecological processes promoting nestedness were selective extinction and human disturbance: site richness orderly increased according to area, and decreased according to background noise levels. Results are discussed taking into account habitat-related sound degradation and transmission properties, and differential susceptibility to anthropogenic noise among songbirds with preferences for forest versus non-forest habitats. To the best of our knowledge, this is the first time that noise pollution, a pervasive kind of human disturbance in modern cities, is acknowledged as a factor promoting nestedness in bird communities.     

Ordered mesoporous silica prepared by quiescent interfacial growth method - effects of reaction chemistry

Acidic interfacial growth can provide a number of industrially important mesoporous silica morphologies including fibers, spheres, and other rich shapes. Studying the reaction chemistry under quiescent (no mixing) conditions is important for understanding and for the production of the desired shapes. The focus of this work is to understand the effect of a number of previously untested conditions: acid type (HCl, HNO₃, and H₂SO₄), acid content, silica precursor type (TBOS and TEOS), and surfactant type (CTAB, Tween 20, and Tween 80) on the shape and structure of products formed under quiescent two-phase interfacial configuration. Results show that the quiescent growth is typically slow due to the absence of mixing. The whole process of product formation and pore structuring becomes limited by the slow interfacial diffusion of silica source. TBOS-CTAB-HCl was the typical combination to produce fibers with high order in the interfacial region. The use of other acids (HNO₃ and H₂SO₄), a less hydrophobic silica source (TEOS), and/or a neutral surfactant (Tweens) facilitate diffusion and homogenous supply of silica source into the bulk phase and give spheres and gyroids with low mesoporous order. The results suggest two distinct regions for silica growth (interfacial region and bulk region) in which the rate of solvent evaporation and local concentration affect the speed and dimension of growth. A combined mechanism for the interfacial bulk growth of mesoporous silica under quiescent conditions is proposed.     

A Nafion-based self-humidifying membrane with ordered dispersed Pt layer

A double-layer Nafion-based membrane consisting of a pure Nafion layer and an ordered dispersed Pt particles layer was investigated. The Pt particles were dispersed under the anode graphite ribs, which provide the sites for the recombination of the permeating _H2${\mathrm{H}}_2$ and _O2${\mathrm{O}}_2$ into water. The electrochemical performances of the ordered Pt particles dispersed membrane in proton exchange membrane fuel cell (PEMFC) were studied and compared with those of the common Pt particles dispersed membrane and the pure Nafion membrane. The results indicate that the ordered Pt dispersed membrane reduces the amount of Pt dosage than the common Pt dispersed membrane and improves the performance of PEMFC operated under dry conditions than the pure Nafion membrane as well.     

几种经典网格细分算法的比较*

曲面造型方法由于其局部性好、计算量小、算法简单、响应速度高等优点,已经广泛应用于计算机图形学、CAGD、计算机动画以及虚拟现实等领域。网格细分是一种离散造型方法,可以从数字化仪等设备直接获得数据。介绍了近年来提出的一些细分算法,对其中几种比较经典的算法进行了简单的分类和比较,并论述了各自的适用范围。     

民航货运量IOWHA算子组合预测

收集我国民航货运量及其影响要素（职工平均工资、人均GDP、GDP、人均消费支出、航线里程、全社会固定资产投资和人口数量）的统计数据为基础,应用多元回归模型和GM（1,1）模型对样本数据进行分别预测,以此为基础,指出引入诱导有序调和加权平均算子（IOWHA）进行组合预测的必要性,基于该算子的优化组合模型进行预测,并构建误差评价指标体系。结果表明,基于诱导有序调和加权平均算子的民航货运量预测的各项误差指标值均低于任一单项预测值,说明该组合预测模型的预测效果更佳,预测精度更高,可应用于实际预测。     

基于IOWC-GOWA算子的区间组合预测模型

在连续区间数广义有序加权平均（C-GOWA）算子基础上,将IOWA算子和C-GOWA算子相结合,提出诱导有序加权连续区间广义有序加权平均（IOWC-GOWA）算子的概念。以指数支撑度作为相关性指标,构建新的组合预测模型。通过实例分析说明该模型能有效提高预测精度。     

有序样本聚类方法在水土保持分区中的应用

阐述了有序样本聚类方法在流域规划、水土保持分区中的应用,对提高分区的合理性、科学性具有很高的实用价值。