振冲碎石桩与固结灌浆在下坂地大坝 坝基加固中的应用

1工程概况 下坂地水利枢纽工程位于新疆塔里木河源流叶尔羌河主要支流之一的塔什库尔干河中下游.该工程是塔里木河流域近期综合治理中唯一的山区水库枢纽工程,主要任务是以生态补水及春旱供水为主,结合发电的综合性大(2)型Ⅱ等工程.枢纽建筑物由拦河坝、导流泄洪洞、引水发电洞和电站厂房组成.大坝为沥青混凝土心墙砂砾石坝,水库正常蓄水位2 960 m,总库容8.67亿m3,电站总装机150 MW.     

Ⅱ级粉煤灰高性能混凝土的长期抗硫酸盐侵蚀性能

按高性能混凝土配比制配不同水胶比、不同Ⅱ级粉煤灰掺量的普通水泥胶砂试件,浸泡在不同浓度的硫酸盐溶液中,进行长达2年的侵蚀试验。结果表明:短龄期养护条件下较低粉煤灰掺量(30%)试件在高浓度硫酸盐侵蚀环境中的长期抗蚀能力有限。而随养护龄期和Ⅱ级粉煤灰掺量的增加以及水胶比的降低,试件的抗蚀能力大幅度提高,体现出优越的长期抗侵蚀能力。     

Understanding knowledge sharing activities in free/open source software projects: An empirical study

Free/Open Source Software (F/OSS) projects are people-oriented and knowledge intensive software development environments. Many researchers focused on mailing lists to study coding activities of software developers. How expert software developers interact with each other and with non-developers in the use of community products have received little attention. This paper discusses the altruistic sharing of knowledge between knowledge providers and knowledge seekers in the Developer and User mailing lists of the Debian project. We analyze the posting and replying activities of the participants by counting the number of email messages they posted to the lists and the number of replies they made to questions others posted. We found out that participants interact and share their knowledge a lot, their positing activity is fairly highly correlated with their replying activity, the characteristics of posting and replying activities are different for different kinds of lists, and the knowledge sharing activity of self-organizing Free/Open Source communities could best be explained in terms of what we called “Fractal Cubic Distribution” rather than the power-law distribution mostly reported in the literature. The paper also proposes what could be researched in knowledge sharing activities in F/OSS projects mailing list and for what purpose. The research findings add to our understanding of knowledge sharing activities in F/OSS projects.     

Software process improvement success factors for small and medium Web companies: A qualitative study

Context

The context of this research is software process improvement (SPI) in small and medium Web companies.

Objective

The primary objective of this paper is to identify software process improvement (SPI) success factors for small and medium Web companies.

Method

To achieve this goal, we conducted semi-structured, open-ended interviews with 21 participants representing 11 different companies in Pakistan, and analyzed the data qualitatively using the Glaserian strand of grounded theory research procedures. The key steps of these procedures that were employed in this research included open coding, focused coding, theoretical coding, theoretical sampling, constant comparison, and scaling up.

Results

An initial framework of key SPI success factors for small and medium Web companies was proposed, which can be of use for small and medium Web companies engaged in SPI. The paper also differentiates between small and medium Web companies and analyzes crucial SPI requirements for companies operating in the Web development domain.

Conclusion

The results of this work, in particular the use of qualitative techniques - allowed us to obtain rich insight into SPI success factors for small and medium Web companies. Future work comprises the validation of the SPI success factors with small and medium Web companies.     

Design and Performance Analysis of Fractal Regular Slotted-Patch Antennas for Ultra-Wideband Communication Systems

Wireless Personal Communications - This paper presents design of fractal regular slots patch antennas for Ultra-wideband (UWB) systems. The reference antenna is an UWB monopole rectangular patch...     

掺Ⅱ级粉煤灰胶砂试件在高浓度硫酸盐侵蚀下的破坏特征与破坏机理分析

按高性能混凝土配比方法制作不同水胶比、Ⅱ级粉煤灰不同掺量的胶砂试件,进行硫酸盐侵蚀试验.采用扫描电镜( SEM)和能谱(EDS)对试件进行微观观测、分析,结果表明:在低水胶比情况下,掺粉煤灰的胶砂试件受高浓度硫酸盐侵蚀破坏的类型是石膏型破坏,未产生钙矾石(Aft)型侵蚀破坏;侵蚀破坏发生在试件表层,侵蚀破坏层的厚度主要...