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关键词： Android   Map data structure   Map implementations   CPU usage   Memory usage   Energy consumption  

摘要： A map is a data structure that is commonly used to store data as key-value pairs and retrieve data as keys, values, or key-value pairs. Although Java offers different map implementation classes, Android SDK offers other implementations supposed to be more efficient than HashMap: ArrayMap and SparseArray variants (SparseArray, LongSparseArray, SparseIntArray, SparseLongArray, and SparseBooleanArray). Yet, the performance of these implementations in terms of CPU time, memory usage, and energy consumption is lacking in the official Android documentation;although saving CPU, memory, and energy is a major concern of users wanting to increase battery life. Consequently, we study the use of map implementations by Android developers in two ways. First, we perform an observational study of 5713 Android apps in GitHub. Second, we conduct a survey to assess developers' perspective on Java and Android map implementations. Then, we perform an experimental study comparing HashMap, ArrayMap, and SparseArray variants map implementations in terms of CPU time, memory usage, and energy consumption. We conclude with guidelines for choosing among the map implementations: HashMap is preferable over ArrayMap to improve energy efficiency of apps, and SparseArray variants should be used instead of HashMap and ArrayMap when keys are primitive types.

关键词： Parallel programs   concurrent data structures   synchronization   performance   granularity control   algorithms  

摘要： To use the computational power of modern computing machines, we have to deal with concurrent programs. Writing efficient concurrent programs is notoriously difficult, primarily due to the need of harnessing synchronization costs. In this thesis, we focus on synchronization costs in parallel programs and concurrent data structures. First, we present a novel granularity control technique for parallel programs designed for the dynamic multithreading environment. Then in the context of concurrent data structures, we consider the notion of concurrency-optimality and propose the first implementation of a concurrency-optimal binary search tree that, intuitively, accepts a concurrent schedule if and only if the schedule is correct. Also, we propose parallel combining, a technique that enables efficient implementations of concurrent data structures from their parallel batched counterparts. We validate the proposed techniques via experimental evaluations showing superior or comparable performance with respect to state-of-the-art algorithms. From a more formal perspective, we consider the phenomenon of helping in concurrent data structures. Intuitively, helping is observed when the order of some operation in a linearization is fixed by a step of another process. We show that no wait-free linearizable implementation of stack using read, write, compare&swap and fetch&add primitives can be help-free, correcting a mistake in an earlier proof by Censor-Hillel et al. Finally, we propose a simple way to analytically predict the throughput of data structures based on coarse-grained locking.

关键词： 分层次教学   教学模式   数据结构  

摘要： 针对地方高校春季高考生和夏季高考生生源的不同情况,给高校开展教学活动带来了较大难度。在实际教学中,"数据结构"课程不但有很强的理论性,也有一定的抽象性、实践性,对不同基础的学生理解起来有不同的难度。为了有效提高课程教学效果,激发学生的学习兴趣,对我校计算机专业的春季高考生和夏季高考生的"数据结构"分层次教学模式进行探讨。

关键词： Beta diversity   Classification   Comparison   Ordination   Similarity   Simplex diagram  

摘要： Ecological studies may produce presence-absence data sets for different taxonomic groups, with varying spatial resolution and temporal coverage. Comparisons of these data are needed to extract meaningful information on the background ecological factors explaining community patterns, to improve our understanding of how beta diversity and its components vary among communities and biogeographical regions, and to reveal their possible implications for biodiversity conservation. A methodological difficulty is that the number of sampling units may be unequal: no method has been designed as yet to compare data matrices in such cases. The problem is solved by converting presence-absence data matrices to simplex plots based on the decomposition of Jaccard dissimilarity into species replacement and richness difference fractions used together with the complementary similarity function. Pairs of simplex plots representing different data matrices are then compared by quantifying, for each of them, the relative frequency of points in small, pre-defined subregions of the simplex, and then calculating a divergence function between the two frequency distributions. Given more than two data matrices, classification and ordination techniques may be used to obtain a synthetic and informative picture of meta community structure. We demonstrate the potential of our data analytical model by applying it to different case studies spanning different spatial scales and taxonomic levels (Mediterranean Island faunas;Finnish stream macroinvertebrate assemblages;Hungarian forest assemblages), and to a study of temporal changes in small islands (insect fauna in Florida). We conclude that, by accounting for various structural aspects simultaneously, the method permits a thorough ecological interpretation of presence-absence data. Furthermore, the examples illustrate succinctly how similarity, beta diversity and two of its additive components, species replacement and richness difference influence pre

关键词： 在线异构切换   数据迁移   数据结构   第三备  

摘要： 本文介绍了无锡电视台播出数据库由原来的Oracle向SQL Server异构迁移的过程,以及迁移的原因,并且为此建立的迁移方案和应急预案。还介绍了在数据迁移中遇到的困难和解决办法,为同行业播出系统在线异构切换核心数据库提供参考。

关键词： 精品课程   数据结构   教学资源   教学模式  

摘要： 本文按照数据结构精品资源共享课程的建设目标,秉承先进的教学理念,围绕数据结构课程体系、教学方法、教学团队、教学资源平台、课程考核评价等方面进行了建设与实践。课程借鉴CDIO工程教育理念,重构了课程教学组织与思维培养关系,设计了问题驱动的课程教学模式,构建了网络教学资源平台,建立了多元化过程性的课程评价体系,形成了鲜明的课程教学特色。发挥了精品课程建设经验和示范作用,并指出了数据结构课程建设进一步努力的方向。取得丰富的教学效果和教学成果表明,课程建设措施得当,成效明显。

关键词： 游戏   角色   数据结构  

摘要： 近几年,游戏产业的发展欣欣向荣,百家争鸣。游戏角色是游戏灵活性的构成部分,承载游戏的剧情,是一款游戏的灵魂。笔者通过基于C++的游戏角色的设计和开发方法,给出了游戏角色的基本特征、实现游戏角色的原理和若干要点及实际应用时的具体处理方式。

关键词： 微课   算法与数据结构   教学改革  

摘要： 综合"算法与数据结构"课程的教学现状和互联网技术的发展,利用微课这种新型教学资源的优势及特点,提出一种以微课作为辅助手段的"算法与数据结构"课程教学改革方法。论文首先分析了传统教学模式中存在的问题,然后阐述了引入微课来解决这些问题的可能性和必要性,最后,从关键算法演示和实践教学的微课设计,探讨了微课在课程改革中的具体应用。微课的引入不仅提高了学生的学习兴趣,培养学生逻辑分析和解决问题的能力,实现了从以教师为中心向以学生为中心的转变,而且有利于提高教学质量,对培养学生的创新实践能力起到了很好的作用。

关键词： 数据结构  

ISBN: (数字)9787302499442 ISBN: (纸本)9787302499442

摘要： 本书是数据结构课程的辅助教材，采用C和C++两种语言来描述数据结构，让学生在实验与习题中体会与掌握数据结构，同时培养编程能力和分析能力。主要内容包括实验与习题两大部分，用于巩固数据结构的理论知识，提高实践应用能力。 本书内容立足于高校教学的要求，适用于本科院校的课程和学生群体，可作为数据结构与算法课程的辅助教材，也可作为初学数据结构读者的自学读物。

关键词： 雨课堂   数据结构   教学互动   反思  

摘要： 本文主要探讨了雨课堂在数据结构课程教学互动中的应用,同时作者反思了雨课堂教学在使用和推广中存在的问题与瓶颈。