Practical unicast and convergecast scheduling schemes for cognitive radio networks

Cognitive Radio Networks (CRNs) have paved a road for Secondary Users (SUs) to opportunistically exploit unused spectrum without harming the communications among Primary Users (PUs). In this paper, practical unicast and convergecast schemes, which are overlooked by most of the existing works for CRNs, are proposed. We first construct a cell-based virtual backbone for CRNs. Then prove that SUs have positive probabilities to access the spectrum and the expected one hop delay is bounded by a constant, if the density of PUs is finite. According to this fact, we proposed a three-step unicast scheme and a two-phase convergecast scheme. We demonstrate that the induced delay from our proposed Unicast Scheduling (US) algorithm scales linearly with the transmission distance between the source and the destination. Furthermore, the expected delay of the proposed Convergecast Scheduling (CS) algorithm is proven to be upper bounded by $O(\log n + \sqrt{n/\log n})$ . To the best of our knowledge, this is the first study of convergecast in CRNs. Finally, the performance of the proposed algorithms is validated through simulations.     

Median rankit control chart by the quantile approach

It is desirable that the data for a statistical control chart be normally distributed. However, if the data are not normal, then a transformation can be used, e.g. Box-Cox transformations, to produce a suitable control chart. In this paper we will discuss a quantile approach to produce a control chart and to estimate median rankit for various non-normal distributions. We will also provide examples of logistic data to indicate how a quantile approach could be used to construct a control chart for a non-normal distribution using a median rankit.     

Axiomatic Based Decomposition for Conceptual Product Design

This paper describes a structured methodology for decomposing the conceptual design problem in order to facilitate the design process and result in improved conceptual designs that better satisfy the original customer requirements. The axiomatic decomposition for conceptual design method combines Alexander's network partitioning formulation of the design problem with Suh's Independence Axiom. The axiomatic decomposition method uses a cross‐domain approach in a House of Quality context to estimate the interactions among the functional requirements that are derived from a qualitative assessment of customer requirements. These interactions are used in several objective functions that serve as criteria for decomposing the design network. A new network partitioning algorithm is effective in creating partitions that maximize the within‐partition interactions and minimize the between‐partition interactions with appropriate weightings. The viability, usability, and value of the axiomatic decomposition method were examined through analytic comparisons and qualitative assessments of its application. The new method was examined using students in engineering design capstone courses and it was found to be useable and did produce better product designs that met the customer requirements. The student‐based assessment revealed that the process would be more effective with individuals having design experience. In a subsequent assessment with practicing industrial designers, it was found that the new method did facilitate the development of better designs. An important observation was the need for limits on partition size (maximum of four functional requirements.) Another issue identified for future research was the need for a means to identify the appropriate starting partition for initiating the design.     

Combining answers to direct and indirect questions: An implementation of Kuk’s randomized response model

Abstract

In this article, we propose a two folded approach for estimation of the population proportion of a sensitive attribute. The rationale of proposed technique is to give respondents choice if they want to avail randomized device or not. Thus, our technique is inherently capable of entertaining the responses attained through direct questioning and by employing randomization device, as well. We believe that free to choose policy will be helpful to develop a curtsy between interviewer and respondent (which is highly desirable, especially when sensitive issue is under consideration) and thus enhances the survey reliability. The proposed technique is developed for simple random sampling, at first, and then extended to stratified random sampling. The superior performance of proposed technique in comparison to the Kuk (1990 Kuk, A. Y. 1990. Asking sensitive questions indirectly. Biometrika 77 (2):436–8. doi:10.1093/biomet/77.2.436.[Crossref], [Web of Science ®] , [Google Scholar]) method is demonstrated throughout this article. We provide algebraic, graphical and numerical evidences in support of our proposed technique. Furthermore, we also offer cost analysis considering most commonly used cost functions in the literature of survey research.     

全球化与国家发展--当代政治经济思考上的未来派与怀旧派

把全球化与国家发展放在一起思考,表明了当代政治经济思考中的一种深刻矛盾.因为全球化与国家发展是相互干扰的.以自治和主权作为前提的国家发展观念会妨碍全球化的进展,在经济领域中尤其是这样;而全球化对于国家的侵蚀,也使得这种国家发展观变得毫无意义.第三世界的国家发展战略和当代分析家关于全球化背景下全球政治经济典型特征的分析,展现了对当代政治经济发展的两种不同描述.在全球化时代,不仅要密切注意经济中的技术问题,而且要注意全球经济组织中阶级的利益和权力问题.     

Social adversity in pregnancy and trajectories of women’s depressive symptoms: A longitudinal study

Background

Sound evidence has linked the experience of adversity with depression. Less is known about this association over time.

The distance between random points in rectangles

Since 1943, numerous papers have discussed the problem of the distribution of the distance between random points in rectangles, considering special cases such as two points in the same square, points in adjacent squares, two rectangles sharing a side and others. The problems arise in a variety of settings: operations research, population studies, urban planning, physical chemistry, chemical physics and materials science. Reported results are all of special cases with formulas specific to each case. It is possible to put such problems in a general setting with a single formula that handles all the particular cases. The method is well suited to computing and use of graphics. Now that computers and graphic output are commonplace it seems worthwhile to describe the general method and provide program outlines for computing and plotting the resulting distributions. We do that in this article.