英语试卷的编排

要让学生考出真实水平 ,有很多因素可以促成这一目标的达到 ,其中一个因素为试卷的编排。试卷的编排涉及到试卷的总体编排和试卷题目各部分的编排。编排顺序或方式不当皆可导致分数的无效差异 ,所以应引起注意。     

数字图像多重水印及容量分析

利用CDMA系统多址复用的特点,提出了一种基于CDMA的多重水印算法,在小波变换域中同时嵌入多个水印。对多个原始水印进行卷积编码和交织编码后,采用Gold码组进行正交扩频,经CDMA编码的水印信息被叠加嵌入在除HH1以外的其他小波子带中。水印嵌入的幅值根据Watson小波域视觉感知模型确定。嵌入位置取决于一个PN序列随机发生器,检测时不需要原始图像。在此基础上对多重水印容量进行了分析,结果表明当嵌入两个水印时,其容量大于任何一个单一水印的容量,但小于两个单一水印容量之和。     

LDPC编码自适应加载MIMO-OFDM系统性能分析

介绍了LDPC校验阵的构造及编译码算法,采用了随机法构造LDPC校验阵,编码基于高斯消去直接进行译码采用无穷阶量化时的置信传播算法;讨论了OFDM自适应加载技术与多输入多输出技术,结合自适应比特功率分配算法与基于多载波调制的比特分配方案实现了该加载分配技术;给出了LDPC编码的自适应加载MIMO-OFDM系统的模型。经仿真分析得出,二元域上非规则LDPC编码的系统性能优于多元域上的,自适应加载MIMO-OFDM技术大大提高了系统传输速率,有效增强了系统抗衰落性。     

A Parallel between Regret Theory and Outranking Methods for Multicriteria Decision Making Under Imprecise Information

Incorporation of the behavioral issues of the decision maker (DM) is among the aspects that each Multicriteria Decision Making (MCDM) method implicitly or explicitly takes into account. As postulated by regret theory, the feelings of regret and rejoice are among the behavioral issues associated with the entire decision making process. Within the context of MCDM, the DM may feel regret, when the chosen alternative is compared with another one having at least one better criterion value. PROMETHEE II is a widely known MCDM method that makes no explicit incorporation of regret attitude of the DM. In this paper, we elaborate on the applicability of regret theory to MCDM context. In particular, we investigate the findings of regret theory and explore the parallel between regret theory and PROMETHEE II method. Relying on the concepts of regret theory, we demonstrate how a decision that is made using a PROMETHEE II based outranking method conforms to the regret attitude of the DM.     

Sovereignty at What Scale? An Inquiry into Multiple Dimensions of Food Sovereignty

Abstract

Food sovereignty has struggled to make inroads into changing the structures and processes underlying the corporate food regime. One reason is that scale is still underspecified in the politics, strategies, and theories of food sovereignty. We suggest that much can be learned from examining the multiple dimensions of scale inherent in ongoing food sovereignty struggles. A gap exists between these in vivo experiments and the maturing academic theory of scale. The concept of ‘sovereignty’ can be opened up to reveal that movements, peoples, and communities, for example, are creating multiple sovereignties and are exercising sovereignty in more relational ways. Relational scale can aid movements and scholars to map and evaluate how spatial and temporal processes at and among various levels work to reinforce dominant agri-food systems but could also be reconfigured to support progressive alternatives. Finally, we apply relational scale to suggest practical strategies for realizing food sovereignty, using examples from the Potato Park in the Peruvian Andes.     

Translating the Politics of Food Sovereignty: Digging into Contradictions,Uncovering New Dimensions

Abstract

Food sovereignty, as a movement and a set of ideas, is coming of age. Rooted in resistance to free trade and the globalizing force of neoliberalism, the concept has inspired collective action across the world. We examine what has changed since food sovereignty first emerged on the international scene and reflect on insight from new terrain where the movement has expanded. We argue that to advance the theory and practice of food sovereignty, new frameworks and analytical methods are needed to move beyond binaries—between urban and rural, gender equality and the family farm, trade and localism, and autonomy and engagement with the state. A research agenda in food sovereignty must not shy away from the rising contradictions in and challenges to the movement. The places of seeming contradiction may in fact be where the greatest insights are to be found. We suggest that by taking a relational perspective, scholars can begin to draw insight into the challenges and sticking points of food sovereignty by training their lens on shifts in the global food regime, on the efforts to construct sovereignty at multiple scales, and on the points of translation where food sovereignty is articulated through historical memory, identity, and everyday life.     

Parental constructions of masculinity at the transition to parenthood: the division of parental leave among Austrian couples

Men and masculinity are considered a key factor in changing gender inequality at the transition to parenthood. Prior research on gendered division of parental leave concentrated on fathers’ perspectives. This paper includes perspectives of fathers and mothers who make use of parental leave in different ways and asks how masculinity is jointly constructed, how these constructions are linked to the use of parental leave, and if and how they are oriented towards hegemonic masculinity. The analysis is based on 44 qualitative interviews with 11 Austrian couples before and after birth when decisions concerning parental leave were made. Our case reconstructions reveal that parents considered parental leave a central element of masculinity as long as it suited fathers’ needs and circumstances permitted. The decisions for sharing parental leave were father-centred as both partners valued father’s leave higher than mother’s.     

Handling Missing Values in Longitudinal Panel Data With Multiple Imputation

This article offers an applied review of key issues and methods for the analysis of longitudinal panel data in the presence of missing values. The authors consider the unique challenges associated with attrition (survey dropout), incomplete repeated measures, and unknown observations of time. Using simulated data based on 4 waves of the Marital Instability Over the Life Course Study (n = 2,034), they applied a fixed effect regression model and an event‐history analysis with time‐varying covariates. They then compared results for analyses with nonimputed missing data and with imputed data both in long and in wide structures. Imputation produced improved estimates in the event‐history analysis but only modest improvements in the estimates and standard errors of the fixed effects analysis. Factors responsible for differences in the value of imputation are examined, and recommendations for handling missing values in panel data are presented.     

A survey on multivariate chi-square distributions and their applications in testing multiple hypotheses

We are concerned with three different types of multivariate chi-square distributions. Their members play important roles as limiting distributions of vectors of test statistics in several applications of multiple hypotheses testing. We explain these applications and consider the computation of multiplicity-adjusted p-values under the respective global hypothesis. By means of numerical examples, we demonstrate how much gain in level exhaustion or, equivalently, power can be achieved with corresponding multivariate multiple tests compared with approaches which are only based on univariate marginal distributions and do not take the dependence structure among the test statistics into account. As a further contribution of independent value, we provide an overview of essentially all analytic formulas for computing multivariate chi-square probabilities of the considered types which are available up to present. These formulas were scattered in the previous literature and are presented here in a unified manner.     

Robust pairwise multiple comparisons under short-tailed symmetric distributions

In one-way ANOVA, most of the pairwise multiple comparison procedures depend on normality assumption of errors. In practice, errors have non-normal distributions so frequently. Therefore, it is very important to develop robust estimators of location and the associated variance under non-normality. In this paper, we consider the estimation of one-way ANOVA model parameters to make pairwise multiple comparisons under short-tailed symmetric (STS) distribution. The classical least squares method is neither efficient nor robust and maximum likelihood estimation technique is problematic in this situation. Modified maximum likelihood (MML) estimation technique gives the opportunity to estimate model parameters in closed forms under non-normal distributions. Hence, the use of MML estimators in the test statistic is proposed for pairwise multiple comparisons under STS distribution. The efficiency and power comparisons of the test statistic based on sample mean, trimmed mean, wave and MML estimators are given and the robustness of the test obtained using these estimators under plausible alternatives and inlier model are examined. It is demonstrated that the test statistic based on MML estimators is efficient and robust and the corresponding test is more powerful and having smallest Type I error.