Space systems have become a key enabler for a wide variety of applications that are vital to the functioning of advanced societies. The trend is one of quantitative and qualitative increase of this dependence, so much...Space systems have become a key enabler for a wide variety of applications that are vital to the functioning of advanced societies. The trend is one of quantitative and qualitative increase of this dependence, so much so that space systems have been described as a new example of critical infrastructure. This article argues that the existence of critical space infrastructures implies the emergence of a new category of disasters related to disruption risks. We inventory those risks and make policy recommendations for what is, ultimately, a resilience governance issue.展开更多
Traditionally, the analysis of sector interdependencies has involved the characterization of all infrastructure-to-infrastructure interconnections and some of the main infrastructure integrals that, once lost or be ta...Traditionally, the analysis of sector interdependencies has involved the characterization of all infrastructure-to-infrastructure interconnections and some of the main infrastructure integrals that, once lost or be tampered with, will compromise the performance and security issues with the other interconnected infrastructures. Therefore, the paper dwells much on the security implications which may be associated with these infrastructure sector interdependencies. This paper also discusses some of the major risk considerations, analytical approaches, researches and the necessary developments needed as well as the interdisciplinary ranges through which the necessary skills are required in the construction of comprehensive sector interdependencies.展开更多
The major challenge to increase the decentralized generation share in distribution grids is the maintenance of the voltage within the limits. The inductive power injection is widely used as a remedial measure. The mai...The major challenge to increase the decentralized generation share in distribution grids is the maintenance of the voltage within the limits. The inductive power injection is widely used as a remedial measure. The main aim of this paper is to study the effect of the reactive power injection (by what-ever means) on radial grid structures and their impact on the voltage of the higher voltage-level grids. Various studies have shown that, in addition to the major local effect on the voltage at the injection point, the injection of the reactive power on a feeder has a global effect, which cannot be neglected. The reactive power flow and the voltage on the higher voltage level grid are significantly affected. In addition, a random effect is introduced by the DGs which are connected through inverters (using wind or PVs). Although their operation is in accordance with the grid code, a volatile reactive power flow circulates on the grid. Finally, this study proposes the implementation of the “Volt/var secondary control” interaction chain in order to increase the distributed generation share at every distribution voltage level, be it medium or low voltage, and at the same time to guarantee a stable operation of the power grid. Features of Volt/var secondary control loops ensure a resilient behavior of the whole chain.展开更多
The performance model proposed by this study represents an innovative approach to deal with performance assessment in ATM （air traffic management）. It is based on Bayesian networks methodology, which presents severa...The performance model proposed by this study represents an innovative approach to deal with performance assessment in ATM （air traffic management）. It is based on Bayesian networks methodology, which presents several advantages but also some drawbacks as highlighted along the paper. We illustrate the main steps required for building the model and present a number of interesting results. The contribution of the paper is two-fold： （1） It presents a new methodological approach to deal with a problem which is of strategic importance for ANSPs （air navigation service providers）; （2） It provides insights on the interdependencies between factors influencing performance. Both results are considered particularly important nowadays, due to the SES （Single European Sky） performance scheme and its related target setting process.展开更多
The severe drought that Australia has endured over the past few years has impacted adversely on the environment and is the major cause of the reduction of water levels in the Coorong and Lower Lakes. The over-allocati...The severe drought that Australia has endured over the past few years has impacted adversely on the environment and is the major cause of the reduction of water levels in the Coorong and Lower Lakes. The over-allocation and over-use of water in the MDB （Murray-Darling Basin） has caused the system to endure the longest period ever of reduced freshwater inflows and levels. The environmental state of Coorong and Lower Lakes is an issue that requires immediate action by governments and the surrounding community. This article will explore current data regarding the social and planning implications of the degradation of the Coorong and Lower Lakes. It primarily focuses on the social impacts that will occur if the Coorong and Lower Lakes area is significantly environmentally degraded. Drawing on Beck＇s risk theory, this paper analyses the adaptive capacity of settlements in the Coorong and Lower Lakes area and how they respond to the stresses and risks caused by environmental degradation. Economic and environmental implications will also be explored to provide an understanding of the interdependencies, This article provides a foundation and theoretical structure for further investigative research to be undertaken.展开更多
基金supported by a grant of the Program for Research,Development and Innovation for Space Technology and Advanced Research(STAR)administered by the Romanian Space Agency,project number 191/2017
文摘Space systems have become a key enabler for a wide variety of applications that are vital to the functioning of advanced societies. The trend is one of quantitative and qualitative increase of this dependence, so much so that space systems have been described as a new example of critical infrastructure. This article argues that the existence of critical space infrastructures implies the emergence of a new category of disasters related to disruption risks. We inventory those risks and make policy recommendations for what is, ultimately, a resilience governance issue.
文摘Traditionally, the analysis of sector interdependencies has involved the characterization of all infrastructure-to-infrastructure interconnections and some of the main infrastructure integrals that, once lost or be tampered with, will compromise the performance and security issues with the other interconnected infrastructures. Therefore, the paper dwells much on the security implications which may be associated with these infrastructure sector interdependencies. This paper also discusses some of the major risk considerations, analytical approaches, researches and the necessary developments needed as well as the interdisciplinary ranges through which the necessary skills are required in the construction of comprehensive sector interdependencies.
文摘The major challenge to increase the decentralized generation share in distribution grids is the maintenance of the voltage within the limits. The inductive power injection is widely used as a remedial measure. The main aim of this paper is to study the effect of the reactive power injection (by what-ever means) on radial grid structures and their impact on the voltage of the higher voltage-level grids. Various studies have shown that, in addition to the major local effect on the voltage at the injection point, the injection of the reactive power on a feeder has a global effect, which cannot be neglected. The reactive power flow and the voltage on the higher voltage level grid are significantly affected. In addition, a random effect is introduced by the DGs which are connected through inverters (using wind or PVs). Although their operation is in accordance with the grid code, a volatile reactive power flow circulates on the grid. Finally, this study proposes the implementation of the “Volt/var secondary control” interaction chain in order to increase the distributed generation share at every distribution voltage level, be it medium or low voltage, and at the same time to guarantee a stable operation of the power grid. Features of Volt/var secondary control loops ensure a resilient behavior of the whole chain.
文摘The performance model proposed by this study represents an innovative approach to deal with performance assessment in ATM （air traffic management）. It is based on Bayesian networks methodology, which presents several advantages but also some drawbacks as highlighted along the paper. We illustrate the main steps required for building the model and present a number of interesting results. The contribution of the paper is two-fold： （1） It presents a new methodological approach to deal with a problem which is of strategic importance for ANSPs （air navigation service providers）; （2） It provides insights on the interdependencies between factors influencing performance. Both results are considered particularly important nowadays, due to the SES （Single European Sky） performance scheme and its related target setting process.
文摘The severe drought that Australia has endured over the past few years has impacted adversely on the environment and is the major cause of the reduction of water levels in the Coorong and Lower Lakes. The over-allocation and over-use of water in the MDB （Murray-Darling Basin） has caused the system to endure the longest period ever of reduced freshwater inflows and levels. The environmental state of Coorong and Lower Lakes is an issue that requires immediate action by governments and the surrounding community. This article will explore current data regarding the social and planning implications of the degradation of the Coorong and Lower Lakes. It primarily focuses on the social impacts that will occur if the Coorong and Lower Lakes area is significantly environmentally degraded. Drawing on Beck＇s risk theory, this paper analyses the adaptive capacity of settlements in the Coorong and Lower Lakes area and how they respond to the stresses and risks caused by environmental degradation. Economic and environmental implications will also be explored to provide an understanding of the interdependencies, This article provides a foundation and theoretical structure for further investigative research to be undertaken.
