A Dynamic Memory Allocation Optimization Mechanism Based on Spark

Spark is a distributed data processing framework based on memory. Memory allocation is a focus question of Spark research. A good memory allocation scheme can effectively improve the efficiency of task execution and memory resource utilization of the Spark. Aiming at the memory allocation problem in the Spark2.x version, this paper optimizes the memory allocation strategy by analyzing the Spark memory model, the existing cache replacement algorithms and the memory allocation methods, which is on the basis of minimizing the storage area and allocating the execution area according to the demand. It mainly including two parts: cache replacement optimization and memory allocation optimization. Firstly, in the storage area, the cache replacement algorithm is optimized according to the characteristics of RDD Partition, which is combined with PCA dimension. In this section, the four features of RDD Partition are selected. When the RDD cache is replaced, only two most important features are selected by PCA dimension reduction method each time, thereby ensuring the generalization of the cache replacement strategy. Secondly, the memory allocation strategy of the execution area is optimized according to the memory requirement of Task and the memory space of storage area. In this paper, a series of experiments in Spark on Yarn mode are carried out to verify the effectiveness of the optimization algorithm and improve the cluster performance.     

A critical narrative approach to openness: The impact of open development on structural transformation

Openness has become an important, all‐encompassing term denoting activities facilitated by sharing, using, producing, and redistributing information and communication resources within digital information systems. We compare theoretical advancements that emphasize processes and characteristics of openness with the limitations of extant approaches that have largely focused on improvements to productivity and efficiency. Based on Foucault and Bruner's ideas, this paper contributes a new critical narrative approach to understanding openness explicitly focused on structural transformation and power. The analysis focuses on the case of open development, examining 20 key studies based primarily on developing countries. The critical narrative approach unpacked the production of power/knowledge across actors, intentions, and outcomes of openness research and practice. We find that discursive formations are reliant on technocentric and normative ideals of researchers, leading to narratives of hypothetical outcomes that exclude marginalized perspectives. We propose hermeneutic composability and contesting normative narratives of openness as analytical techniques for an integrated, mutually constitutive conception of interactions between individuals, open artefacts, and open social praxis.     

淮河入江水道行洪能力分析

入江水道是淮河下游最大的泄洪河道,承担着淮河上中游70%以上的洪水泄入长江。根据1961—2018年大洪水期间的实测资料,利用水位流量法计算分析入江水道的泄洪能力和防洪能力。结果表明:因历史客观条件限制以及4个梯级控制河段整治的难度与复杂性,在不同时期各控制河段的行洪能力呈现各自不同的特点;经过多年持续有效治理,河道行洪能力整体得到提高;由近年来实测资料推算,各控制河段的行洪能力基本达到设计要求。对入江水道行洪能力的分析为淮河下游区的防汛抗洪和降低特大洪水威胁提供借鉴和参考,对区域经济社会又好又快发展具有现实意义。     

胶带斜井在冶金矿山深井开拓中的应用探讨

针对某在建矿山深井开拓方案探索需求，通过对胶带运输系统发展应用情况介绍和胶带运输系统运输特性影响因素分析，并结合深井开拓胶带斜井方案与竖井加胶带斜井方案投资经济性比较，以及对胶带运输系统在运行过程中关键问题的分析和讨论，得出随着胶带运输技术的不断发展，在大规模深井开拓中，胶带斜井开拓将大有可为，为冶金矿山深井开拓方案选择提供决策支持。     

核电厂聚乙烯管道设计方法及标准简介

随着聚乙烯管道在三门核电厂、大亚湾核电厂中的试应用成功，大量的新建核电厂及核电厂改造项目均将聚乙烯管道作为海水冷却水管道系统的首选管材，自主研制核电厂聚乙烯管技术标准迫在眉睫。本文介绍了核电聚乙烯管道的发展历史和应用现状，对比了核安全3级聚乙烯管道和非核安全相关聚乙烯管道、城市燃气与给水聚乙烯管道技术标准的设计方法及适用范围，探讨了中国目前聚乙烯管技术标准与核3级聚乙烯管道技术标准的差异与差距，为核电厂聚乙烯管道的设计制造与标准研制提供参考。     

水泥辊压机终粉磨系统的工业化应用

介绍了水泥辊压机终粉磨系统及运行情况,与辊压机联合粉磨系统生产的水泥以及所配制的混凝土进行了对比,水泥辊压机终粉磨系统电耗大幅降低,两种水泥所配制的混凝土性能相当。     

罗河铁矿采空区三维激光扫描及应用分析研究

针对传统采空区探测依靠全站仪测量存在劳动强度大、测量结果不准确等问题,采用BLSS-PE矿用三维激光扫描系统对罗河铁矿45-3^#和47-3^#采空区进行了现场扫描,构建了采空区三维实体模型,并在此基础上计算了采空区体积,说明了传统统计方式存在的不足;计算了矿房的超欠挖体积,为准确量化矿房损失率和贫化率提供了基础数据;基于采空区边界进行了二步骤回采设计,说明了采空区边界对于降低矿房损失贫化的重要意义。     

热仿真技术在加固显示器热设计中的应用

根据某型加固显示器的应用环境及内部功能模块的热特性,选择强迫风冷的散热方式,并通过热仿真计算指导风扇选型,根据仿真结果验证散热方案的可行性。最终,依据试验结果验证仿真结果的准确性,为加固显示器的热设计提供思路。     

5G基站供配电勘察设计思路的调整分析

针对5G基站设备相对于以往2G/3G/4G设备的变化,面向一线勘察设计人员,阐述5G基站在供配电需求方面功耗增大、供电方式多样化、供配电改造工作量和难度加大等相应变化,归纳相应的勘察前期准备工作要点,分析在实际工作中可能面临的外市电引入改造、供电方式选择的多样性、新型锂电池应用等重点、难点,介绍理想的5G供配电模式及发展方向,最后提出5G基站供配电勘察设计工作思路调整的建议。     

浅析小型水电站厂用电节约的优化措施

水电站厂用电指标使用综合厂用率,反映电站厂用电消耗的实际情况,可通过厂用电率合理性分析电站厂用耗电情况以及节能降耗挖潜的空间,促进厂用电的合理管理,提高电站效益。文章结合华能甘肃水电开发有限公司管控的6座小型水电站厂用电管理实践,分析了影响水电厂用电损耗的相关因素,提出了厂用电节能降耗的应对措施。