Identification of flutter derivatives from full-scale ambient vibration measurements of the Clifton Suspension Bridge

Nikitas, Nikolaos,Macdonald, John H.G.,Jakobsen, Jasna B. Techno-Press 2011 Wind and Structures, An International Journal (WAS Vol.14 No.3

The estimated response of large-scale engineering structures to severe wind loads is prone to modelling uncertainties that can only ultimately be assessed by full-scale testing. To this end ambient vibration data from full-scale monitoring of the historic Clifton Suspension Bridge has been analysed using a combination of a frequency domain system identification method and a more elaborate stochastic identification technique. There is evidence of incipient coupling action between the first vertical and torsional modes in strong winds, providing unique full-scale data and making this an interesting case study. Flutter derivative estimation, which has rarely previously been attempted on full-scale data, was performed to provide deeper insight into the bridge aerodynamic behaviour, identifying trends towards flutter at higher wind speeds. It is shown that, as for other early suspension bridges with bluff cross-sections, single-degree-of-freedom flutter could potentially occur at wind speeds somewhat below requirements for modern designs. The analysis also demonstrates the viability of system identification techniques for extracting valuable results from full-scale data.

Identification of flutter derivatives from full-scale ambient vibration measurements of the Clifton Suspension Bridge

Nikolaos Nikitas,John H.G. Macdonald,Jasna B. Jakobsen 한국풍공학회 2011 Wind and Structures, An International Journal (WAS Vol.14 No.3

The estimated response of large-scale engineering structures to severe wind loads is prone to modelling uncertainties that can only ultimately be assessed by full-scale testing. To this end ambient vibration data from full-scale monitoring of the historic Clifton Suspension Bridge has been analysed using a combination of a frequency domain system identification method and a more elaborate stochastic identification technique. There is evidence of incipient coupling action between the first vertical and torsional modes in strong winds, providing unique full-scale data and making this an interesting case study. Flutter derivative estimation, which has rarely previously been attempted on full-scale data, was performed to provide deeper insight into the bridge aerodynamic behaviour, identifying trends towards flutter at higher wind speeds. It is shown that, as for other early suspension bridges with bluff crosssections, single-degree-of-freedom flutter could potentially occur at wind speeds somewhat below requirements for modern designs. The analysis also demonstrates the viability of system identification techniques for extracting valuable results from full-scale data.

A k-Tree-Based Resource(CU/PE) Allocation for Reconfigurable MSIMD/MIMD Multi-Dimensional Mesh-Connected Architectures

Jeeraporn Srisawat,Wanlop Surakampontom,Nikitas A. Alexandridis 대한전자공학회 2002 ITC-CSCC :International Technical Conference on Ci Vol.2002 No.7

Is Europe an Optimum Currency Area? Business Cycles in the EU

( Guglielmo Maria Caporale ),( Nikitas Pittis ),( Kyprianos Prodromidis ) 세종대학교 경제통합연구소(구 세종대학교 국제경제연구소) 1999 Journal of Economic Integration Vol.14 No.2

This paper aims to assess whether the EU is an optimum currency area (OCA) by examining synchronization of business cycles and long-run output linkages in the EU countries. We argue that a necessary condition for the desirability of EMU membership for national economies is that the degree of persistence of shocks affecting them should be similar Given the low power of unit root tests, we measure the relative importance of permanent versus transitory components in output. The existence of a "European business cycle" is confirmed by correlation and cointegration analysis respectively. Finally, it appears that monetary coordination, by reducing exchange rate volatility, results in more synchronised cycles. EMU is therefore likely to be a successful experience, since the benefits of monetary integration will outweigh the costs of surrendering the exchange rate instrument. (JEL Classification: E42, F36, F42)

Is Europe an Optimum Currency Area? Business Cycles In the EU

Caporale, Guglielmo Maria,Pittis, Nikitas,Peodromidis, Kyprianos 세종대학교 국제경제연구소 1999 Journal of Economic Integration Vol.14 No.2

This paper aims to assess whether the EU is an optimum currency area(OCA) by examining synchronization of business cycle and long-run output linkages in the EU countries. We argue that a necessary condition for the desirability of EMU membership for national economies is that the degree of persistence of shocks affecting them should be similar. Given the low power of unit root tests, we measure the relative importance of permanent versus transitory components in output. The existence of a "European business cycle" is confirmed by correlation and cointegration analysis respectively. Finally, it appears that monetary coordination, by reducing exchange rate volatility, results in more synchronised cycles. EMU is therefore likely to be a successful experience, since the benefits of monetary integration will outweigh the costs of surrendering the exchange rate instrument. (JEL Classification: E42, F36, F42)

Russia’s policy in the coal sector in the context of Energy Transition

Nikita Lomagin,Irina Mironova,Maxim Titov,Michael Oshchepkov 한국외국어대학교 국제지역연구센터 2024 International Area Studies Review Vol.27 No.1

Attacking and Repairing the Improved ModOnions Protocol-Tagging Approach

( Nikita Borisov ),( Marek Klonowski ),( Mirosław Kutyłowski ),( Anna Lauks-dutka ) 한국인터넷정보학회 2010 KSII Transactions on Internet and Information Syst Vol.4 No.3

In this paper, we present a new class of attacks against an anonymous communication protocol, originally presented in ACNS 2008. The protocol itself was proposed as an improved version of ModOnions, which exploits universal re-encryption in order to avoid replay attacks. However, ModOnions allowed the detour attack, introduced by Danezis to re-route ModOnions to attackers in such a way that the entire path is revealed. The ACNS 2008 proposal addressed this by using a more complicated key management scheme. The revised protocol is immune to detour attacks. We show, however, that the ModOnion construction is highly malleable and this property can be exploited in order to redirect ModOnions. Our attacks require detailed probing and are less efficient than the detour attack, but they can nevertheless recover the full onion path while avoiding detection and investigation. Motivated by this, we present modifications to the ModOnion protocol that dramatically reduce the malleability of the encryption primitive. It addresses the class of attacks we present and it makes other attacks difficult to formulate.

Menstruation in India

Nikita Arora 이화여자대학교 아시아여성학센터 2017 이화여자대학교 아시아여성학센터 학술대회자료집 Vol.2017 No.7

Menstruation is one of the oldest biological and social phenomenons that possess the potential to cut across continents and societies. Quite often, it has been associated with emotions of awe and fear, and worship and sacredness in primitive societies that had no means and knowledge of understanding the biology of menstruation. However, how it transformed into a taboo subject, particularly in India, where traces of celebrating menstruation can still be found, demands speculation. Considering menstrual taboos intrinsically related to their societies and practices, this paper tends to investigate and unravel the relationship between menstrual myths/stigmas, the Hindu religion, and the times of their origin and propagation. It attempts to establish a parallel relationship between the development of patriarchal economies and menstrual stigmas, between male domination and defamation of menstruation. Further, it tends to problematize the contemporary scenario, where despite significant medical interventions in reproductive and sexual health, menstrual taboos enjoy an upper hand in menstruators and non-menstruators knowledge about menstruation. The second aspect of this research paper focuses on the consequences of menstrual taboos, for which I will refer to the research conducted by Happy to Bleed as well as other secondary sources. The underlying logic and understanding is that the stigmas and silence surrounding menstruation, on one hand, foster a sense of inferiority and substandardness among women and other menstruators. Analyzed psychologically, menstrual taboos have the ability to play the role of a catalyst in persuading women to internalize the status of other been accorded to them by patriarchy; they can be and are in fact tools of silencing women and controlling their sexuality and mobility by means of religious beliefs. On the other hand, this silence and shame leads to a dangerous lack of awareness about menstrual health and a large scale absence of hygienic menstrual care products among menstruators. This is to say that while menstruation remains a taboo topic, market dominates menstrual health of individuals and while doing so, it not only retains the prejudices surrounding menstruation, but also puts at grave risk the health of menstruators as well as that of ecology. Therefore, the paper will attempt to bridge the gaps between menstrual taboos, its various manifestations, and its implications on individuals and society as a whole.

EU 청년보장제도의 강화 : 유럽 도시의 경험에서 얻은 교훈

Nikita Sanaullah 한국노동연구원 2021 국제노동브리프 Vol.19 No.12

Hardware Failure in Spinal Tumor Surgery: A Hallmark of Longer Survival?

Nikita Zaborovskii,Adam Schlauch,Dmitrii Ptashnikov,Dmitrii Mikaylov,Sergei Masevnin,Oleg Smekalenkov,John Shapton,Dimitriy Kondrashov 대한척추신경외과학회 2022 Neurospine Vol.19 No.1

Objective: Instrumentation failure in spine tumor surgery is a common reason for revision operation. Increases in patient survival demand a better understanding of the hardware longevity. The study objective was to investigate risk factors for instrumentation failure requiring revision surgery in patients with spinal tumors. Methods: A retrospective cohort from a single tertiary care specialty hospital from January 2005 to January 2021, for patients with spinal primary or metastatic tumors who underwent surgical intervention with instrumentation. Demographic and treatment data were collected and analyzed. Kaplan-Meier analysis was performed for overall survival, and separate univariate and multivariate regression analysis was performed. Results: Three hundred fifty-one patients underwent surgical intervention for spinal tumor, of which 23 experienced instrumentation failure requiring revision surgery (6.6%). Multivariate regression analysis identified pelvic fixation (odds ratio [OR], 10.9), spinal metastasis invasiveness index (OR, 1.11), and survival of greater than 5 years (OR, 3.6) as significant risk factors for hardware failure. One- and 5-year survival rates were 57% and 8%, respectively. Conclusion: Instrumentation failure after spinal tumor surgery is a common reason for revision surgery. Our study suggests that the use of pelvic fixation, invasiveness of the surgery, and survival greater than 5 years are independent risk factors for instrumentation failure.