Applications of sketches in network traffic measurement: A survey

Accurate and timely network traffic measurement is essential for network status monitoring, network fault analysis, network intrusion detection, and network security management. With the rapid development of the network, massive network traffic brings severe challenges to network traffic measurement. However, existing measurement methods suffer from many limitations for effectively recording and accurately analyzing big-volume traffic. Recently, sketches, a family of probabilistic data structures that employ hashing technology for summarizing traffic data, have been widely used to solve these problems. However, current literature still lacks a thorough review on sketch-based traffic measurement methods to offer a comprehensive insight on how to apply sketches for fulfilling various traffic measurement tasks. In this paper, we provide a detailed and comprehensive review on the applications of sketches in network traffic measurement. To this end, we classify the network traffic measurement tasks into four categories based on the target of traffic measurement, namely cardinality estimation, flow size estimation, change anomaly detection, and persistent spreader identification. First, we briefly introduce these four types of traffic measurement tasks and discuss the advantages of applying sketches. Then, we propose a series of requirements with regard to the applications of sketches in network traffic measurement. After that, we perform a fine-grained classification for each sketch-based measurement category according to the technologies applied on sketches. During the review, we evaluate the performance, advantages and disadvantages of current sketch-based traffic measurement methods based on the proposed requirements. Through the thorough review, we gain a number of valuable implications that can guide us to choose and design proper traffic measurement methods based on sketches. We also review a number of general sketches that are highly expected in modern network systems to simultaneously perform multiple traffic measurement tasks and discuss their performance based on the proposed requirements. Finally, through our serious review, we summarize a number of open issues and identify several promising research directions.     

How do project management competencies change within the project management career model in large Chinese construction companies?

Due to the increasing complexity and flexibility of business activities, project-based organizations have become common. In such organizations, project management competencies, which refer to a collection of knowledge, personal attitudes, skills, and relevant experience, are core assets that must be taken seriously. Formalized project management career paths have been widely implemented in the construction industry. However, most recent studies treat project management competencies as static constructs and fail to consider their dynamic changes as a career path advances. To fill this gap in the literature, this study conducted an empirical examination of project management competencies integrated with a career model for the construction industry. First, key project management competencies are identified through a literature review. Then, a project management career model for large Chinese construction companies is developed based on an empirical investigation of six large Chinese construction companies from various sectors. Moreover, a quantitative analysis is performed to explore how these competencies dynamically change as position levels rise in the career model. The research findings indicate that significant differences in project management competencies exist at different levels of the career model. However, the distribution remains steady at different project management position levels for conceptual and organizational competencies, human competencies, and technical competencies.     

Evaluation of small-scale combustion of an insensitive high explosive formulation containing 3-nitro-1,2,4-triazol-5-one (NTO), 2,4-dinitroanisole (DNAN), and 1,3,5-trinitroperhydro-1,3,5-triazine (RDX)

ABSTRACT

Energetic materials are often disposed by open-burning or open-detonation as it is a cost-effective and efficient means of destroying explosive material, and often minimizes the need to transport hazardous explosives to treatment facilities. This practice is often scrutinized for the negative environmental impact of the odorous and unsightly toxic gaseous emissions as well as the resulting deposition residues, which often contain unburned energetic materials. With the increasing use of Insensitive High Explosive compositions in munitions, it is essential that the potential environmental impact of their disposal is assessed before their extensive use to prevent the kind of contamination incidents experienced with legacy explosives. Therefore, the aim of this work was to develop a controlled laboratory experiment to identify the gaseous emissions and the energetic material residues that are generated through the combustion of the IHE components 3-nitro-1,2,4-triazol-5-one (NTO), 2,4-dinitroanisole (DNAN), and 1,3,5-trinitroperhydro-1,3,5-triazine (RDX). A sealed vial containing small (mg) quantities of energetic material was heated until the energetic material combusted. Gas chromatography/mass spectrometry (GCMS) was used to calculate the oxygen consumption and to identify the gases that were generated. The solid residues were analyzed by high-performance liquid chromatography (HPLC) to quantify unburned energetic material. Results showed that DNAN was the most resistant to burning, thus leaving significant quantities of unreacted starting material in the vial. An interesting observation for the IHE formulation was that DNAN also inhibited the combustion of NTO and RDX. The gases emitted during the open burning of IHE components and mixtures included CO, CO₂, and N₂O as expected, but the proportions differed when the components and mixture were compared, reflecting the influence of DNAN on the burning behavior. From our data, we concluded that open-burning DNAN-based formulations is an environmentally unfavorable waste-management practice for the disposal of IHEs mainly due to generation of solid residues as well as unburnt DNAN.     

Supporting comprehensible presentation of clone candidates through two-dimensional maximisation

Duplicated code detection has been an active research field for several decades. Although many algorithms have been proposed, only a few researches have focussed on the comprehensive presentation of the detected clones. During the evaluation of clone detectors developed by the authors, it was observed that the results of the clone detectors were hard to comprehend. Therefore, in this paper a broadly suitable grouping method with which clone pairs can be easily grouped together to provide a more compact result is presented. The grouping algorithm is examined and a more precise revised algorithm is proposed to present all of the candidates to the user.     

Recent Developments in Integrated Solar Combined Cycle Power Plants

Global concern for depleting fossil fuel reserves have been compelling for evolving power generation options using renewable energy sources. The solar energy happens to be a potential source for running the power plants among renewable energy sources. Integrated Solar Combined Cycle(ISCC) power plants have gained popularity among the thermal power plants. Traditional ISCC power plants use Direct Steam Generation(DSG) approach. However, with the DSG method, the ISCC plant’s overall thermal efficiency does not increase significantly due to variations in the availability of solar energy. Thermal Energy Storage(TES) systems when integrated into the solar cycle can address such issues related to energy efficiency, process flexibility, reducing intermittency during non-solar hours. This review work focuses and discusses the developments in various components of the ISCC system including its major cycles and related parameters. The main focus is on CSP technologies, Heat Transfer Fluid(HTF), and Phase Change Material(PCM) used for thermal energy storage. Further, study includes heat enhancement methods with HTF and latent heat storage system. This study will be beneficial to the power plant professionals intending to modify the solar-based Combined Cycle Power Plant(CCPP) and to retrofit the existing Natural Gas Combined Cycle(NGCC) plant with the advanced solar cycle.     

云南沿边境地带小流域LUCC遥感监测试验研究

通过对1990年和2004年两期Landsat TM影像LUCC信息提取方法的处理,揭示了14年间畹町河流域土地利用/土地覆盖的动态变化情况,并对其数量变化和空间特征进行了分析。研究表明,1990-2004年间流域内林地和水域面积显著减少,城镇沿公路大量向外扩张,耕地和未利用土地面积有所增加,草地面积相对持平。     

企业实施ERP的基础性工作研究

在知识经济时代，实施ERP是中国企业的发展趋势。而ERP系统的实施是一项投人大、风险大、实施难度大的系统工程。本文针对企业实施ERP出现的瓶颈问题，提出了几项基础性的准备工作，以提高ERP实施的成功率。     

给排水管道工程施工及验收规范简述

经建设部审批后《给水排水管道工程施工及验收规范》已于１９９７年颁布，本规范是在１９５６年《建筑安装工程施工及验收暂行技术规范》第１２篇“外部管道工程”基础上改编制订的，反映了目前国内管道工程的现况，总结了多年的经验、吸纳了国内多种规范的先进技术和经验，在原有基础上进行全面和重要的补充。本文对该规范的重点内容及编制过程作了简明的介绍。     

工业建筑文化传承与社会节约——旧工业厂房的改造与再利用

产业升级及城市的快速发展使很多制造业企业往郊区、经济后发地区迁移,城市留下了大量的空置厂房.拆除这些旧建筑,再建新建筑,既是一种巨大的浪费,又会割断城市的历史文脉.城市中空置的旧工业厂房可以被改造和再利用,关键是要对其进行功能转换和创意提升,发展新产业,提升城市活力.