著者

Muhammad Sajid Chenguang Bai Muhammad Aamir Zhixiong You Zhiming Yan Xueming Lv

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.59, no.7, pp.1153-1166, 2019-07-15 (Released:2019-07-13)

参考文献数

96

被引用文献数

37

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Evolving knowledge of the structure and physical properties of metallurgical slags is summarized in current review. Slag structure, compositional effects, role of cations in structural modifications, parameters used to represent the structure, structural analysis techniques and effects of structure on properties of blast furnace slag (BFS) studied in details. The basicity, polymerization (Q) or depolymerization (NBO/T), optical basicity, Qn values, concentrations of bridging O’s (Oo), non-bridging O’s (O−) and free O’s (O2−) in slag are useful to represent the structure of slag. Methods and techniques utilized to study the slags are also discussed. The BFS is characterized by using X-ray Diffraction and Spectroscopy, Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Photoelectron Spectroscopy (XPS) and Nuclear Magnetic Resonance (NMR) Spectroscopy. The physical properties such as surface tension, viscosity, density, thermal expansion and diffusion, electrical conductivity and resistivity of slags are reviewed thoroughly which are heavily dependent on structure of slag. Viscosity is affected by polymerization or depolymerization of slag structure and cation size; electrical resistivity depends on Q, size of cations and number of available cations; thermal expansion depends on Q and cation field strength (i.e. z/r2); thermal conductivity is linked with rigidity of slag network which is also dependent on Q and metal-oxygen (M–O) bond strength. Degree of polymerization or depolymerization of slag structure also effect the surface and interfacial tension, it decreases as metal-oxygen (M–O) bond strengths (i.e. z/r2, cation field strength) decrease.

著者

Muhammad AAMIR Mustafa Ali ZAIDI

出版者

東北大学大学院情報科学研究科ジャーナル編集委員会

雑誌

Interdisciplinary Information Sciences (ISSN:13409050)

巻号頁・発行日

vol.19, no.2, pp.173-200, 2013 (Released:2013-11-22)

参考文献数

157

被引用文献数

1 22

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Distributed Denial of Service (DDoS) attacks exhaust victim's bandwidth or services. Traditional architecture of Internet is vulnerable to DDoS attacks and an ongoing cycle of attack & defense is observed. A recent attack report of year 2013 –- `Quarter 1' from Prolexic Technologies identifies that 1.75 percent increase in total number of DDoS attacks has been recorded as compared to similar attacks of previous year's last quarter. In this paper, different types and techniques of DDoS attacks and their countermeasures are surveyed. The significance of this paper is the coverage of many aspects of countering DDoS attacks including new research on the topic. We survey different papers describing methods of defense against DDoS attacks based on entropy variations, traffic anomaly parameters, neural networks, device level defense, botnet flux identifications, application layer DDoS defense and countermeasures in wireless networks, CCN & cloud computing environments. We also discuss some traditional methods of defense such as traceback and packet filtering techniques, so that readers can identify major differences between traditional and current techniques of defense against DDoS attacks. We identify that application layer DDoS attacks possess the ability to produce greater impact on the victim as they are driven by legitimate-like traffic, making it quite difficult to identify and distinguish from legitimate requests. The need of improved defense against such attacks is therefore more demanding in research. The study conducted in this paper can be helpful for readers and researchers to recognize better techniques of defense in current times against DDoS attacks and contribute with more research on this topic in the light of future challenges identified in this paper.