Academic literature on the topic 'Two-Time scales systems'
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Journal articles on the topic "Two-Time scales systems":
1
Agarwal, G. S., and J. Banerji. "Fractional revivals in systems with two time scales." Physical Review A 57, no. 5 (May 1, 1998): 3880–84. http://dx.doi.org/10.1103/physreva.57.3880.
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Borkar, Vivek S. "Stochastic approximation with two time scales." Systems & Control Letters 29, no. 5 (February 1997): 291–94. http://dx.doi.org/10.1016/s0167-6911(97)90015-3.
3
Choi, Sung Kyu, and Namjip Koo. "ASYMPTOTIC EQUIVALENCE BETWEEN TWO LINEAR DYNAMIC SYSTEMS ON TIME SCALES." Bulletin of the Korean Mathematical Society 51, no. 4 (July 31, 2014): 1075–85. http://dx.doi.org/10.4134/bkms.2014.51.4.1075.
4
Gomez-Exposito, Antonio, Catalina Gomez-Quiles, and Izudin Dzafic. "State Estimation in Two Time Scales for Smart Distribution Systems." IEEE Transactions on Smart Grid 6, no. 1 (January 2015): 421–30. http://dx.doi.org/10.1109/tsg.2014.2335611.
5
Xu, Youjun, and Zhiting Xu. "Oscillation criteria for two-dimensional dynamic systems on time scales." Journal of Computational and Applied Mathematics 225, no. 1 (March 2009): 9–19. http://dx.doi.org/10.1016/j.cam.2008.06.010.
6
Hassan, Taher. "Oscillation criterion for two-dimensional dynamic systems on time scales." Tamkang Journal of Mathematics 44, no. 3 (October 18, 2012): 227–32. http://dx.doi.org/10.5556/j.tkjm.44.2013.1189.
Abstract:
The purpose of this paper is to prove oscillation criterion for dynamic system \begin{equation*} u^{\Delta }=pv,\qquad v^{\Delta }=-qu^{\sigma }, \end{equation*}% where $p>0$ and $q$ are rd-continuous functions on a time scale such that $% \sup \mathbb{T=\infty }$ without explicit sign assumptions on $q$ and also without restrictive conditions on the time scale $\mathbb{T}.$
7
Hilscher, Roman Šimon, and Petr Zemánek. "Limit circle invariance for two differential systems on time scales." Mathematische Nachrichten 288, no. 5-6 (October 7, 2014): 696–709. http://dx.doi.org/10.1002/mana.201400005.
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Öztürk, Özkan, and Elvan Akın. "Nonoscillation Criteria for Two-Dimensional Time-Scale Systems." Nonautonomous Dynamical Systems 3, no. 1 (January 30, 2016): 1–13. http://dx.doi.org/10.1515/msds-2016-0001.
Abstract:
AbstractWe study the existence and nonexistence of nonoscillatory solutions of a two-dimensional systemof first-order dynamic equations on time scales. Our approach is based on the Knaster and Schauder fixed point theorems and some certain integral conditions. Examples are given to illustrate some of our main results.
9
Baoguo, Jia. "A new oscillation criterion for two-dimensional dynamic systems on time scales." Tamkang Journal of Mathematics 42, no. 2 (April 14, 2011): 237–44. http://dx.doi.org/10.5556/j.tkjm.42.2011.656.
Abstract:
Consider the linear dynamic system on time scales\begin{equation}u^\Delta=pv, \quad\quad v^\Delta=-qu^\sigma\end{equation}where $p>0$ and $q$ are rd-continuous functions on a time scale $\mathbb T$ such that $\sup\mathbb T=\infty$. When $p(t)$ is allowed to take on negative values, we establish an oscillation criterion for system (0.1). Our result improves a main result of Fu and Lin [S. C. Fu and M. L. Lin, Oscillation and nonoscillation criteria for linear dynamic systems on time scales, Computers and Mathematics with Applications, 59(2010), 2552-2565].
10
Fu, Zhi-Jun, and Xiao-Yang Dong. "H∞ optimal control of vehicle active suspension systems in two time scales." Automatika 62, no. 2 (April 3, 2021): 284–92. http://dx.doi.org/10.1080/00051144.2021.1935610.
Dissertations / Theses on the topic "Two-Time scales systems":
1
Adhikari, Bikash. "Time-scale phenomena in the synchronization of multi-agent systems." Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0079.
Abstract:
La synchronisation des systèmes multi-agents a reçu une attention significative dans la littérature en raison de applications dans différents domaines tels que la physique, la biologie, l'économie ou les télécommunications. Ces systèmes multi-agents peuvent être homogènes ou hétérogènes. Les principales difficultés qui surgissent dans le contrôle et l'analyse des systèmes multi-agents sont dues à l'hétérogénéité des dynamiques et à la taille du réseau. Les systèmes hétérogènes en réseau ont un comportement dynamique plus complexe et la synchronisation asymptotique n'est pas toujours garantie. La grande taille des réseaux augmente la charge de calcul nécessaire pour étudier leur comportements asymptotiques. En outre, la structure de communication entre les agents peut varier dans le temps, ce qui rend le problème encore plus complexe. Dans ce manuscrit, nous abordons ces problèmes en utilisant les phénomènes d'échelle de temps dans la synchronisation du système multi-agent. Nous proposons un modèle d'ordre réduit qui approxime le comportement synchronisé du réseau avec des topologies fixes et variables dans le temps et fournit une stratégie de conception de contrôle efficace en termes de calcul, basée sur la séparation d'échelles de temps dans le réseau. Le premier résultat présente l'approximation fondée sur la dynamique émergente des systèmes multi-agents linéaires hétérogènes connectés avec des topologies variant dans le temps. En utilisant une transformation de coordonnée, la dynamique du réseau en boucle fermée est reformulée en termes de dynamique moyenne et dynamique de l'erreur. Ensuite, en choisissant un gain de couplage suffisamment grand, nous représentons la dynamique dans les nouvelles coordonnées sous forme standard de perturbation singulière. Cela permet de découpler les dynamiques lentes et rapides en utilisant la séparation des échelles de temps. De plus, la synchronisation pratique des systèmes est garantie par l'utilisation d'un grand gain, et son comportement synchronisé peut être approximé par une dynamique lente d'ordre réduit, indépendante des gains de contrôle. Les résultats sont assurés pour les réseaux fortement connectés sous des hypothèses faibles, en introduisant un temps de maintien minimum entre deux commutations consécutives du graphe d'interaction. Le deuxième résultat propose une nouvelle modélisation à trois échelles de temps des réseaux de clusters. À l'aide d'une transformation de coordonnées en deux étapes, la dynamique du réseau est reformulée dans de nouvelles coordonnées, à savoir la dynamique moyenne, l'erreur intra-cluster et l'erreur inter-cluster. Ensuite, avec un choix approprié des paramètres, nous montrons que la dynamique du réseau peut être représentée sous une forme de perturbation singulière standard à deux paramètres dans les nouvelles coordonnées. La dynamique moyenne qui est le comportement à long terme du réseau, évolue sur l'échelle de temps la plus lente. La dynamique des erreurs intra-clusters, qui caractérise la synchronisation à l'intérieur des clusters évolue sur l'échelle de temps la plus rapide. Enfin, la dynamique d'erreur inter-cluster, qui caractérise la synchronisation entre les clusters, est rapide par rapport à la dynamique moyenne et lente par rapport à la dynamique intra-clusters. Dans le résultat final, nous présentons une stratégie de contrôle efficace en termes de calcul pour le réseau de clusters. La synchronisation est garantie par un contrôleur composé avec deux termes : l'un responsable de la synchronisation intra-clusters (interne) et l'autre de la synchronisation entre les clusters (externe). Le contrôleur interne ne requiert pas beaucoup d'effort de calcul puisqu'une expression analytique le décrit. Le contrôleur externe est conçu à travers une approche d'équilibre de satisfaction. En d'autres termes, les contrôleurs interne et externe sont conçus indépendamment, et ils assurent un coût satisfaisant garanti pour chaque clusterSynchronization of multi-agent systems has received significant attention in the literature due to applications in different domains such as physics, biology, economics, medicine, telecommunication, etc. These multi-agent systems can be homogeneous (identical dynamics) or heterogeneous (non-identical dynamics). The major difficulties that arise in the control and analysis of the multi-agent systems are due to the heterogeneity and the network size. Heterogeneous networked systems have more complex dynamic behavior, and asymptotic synchronization may not be guaranteed. At the same time, the large network size increases the computational effort required to study the asymptotic behavior of the network. Also, the communication structure between the agents, which is important for synchronization, can be time-varying, adding more complexity to the problem. In this manuscript, we address these problems utilizing the time-scale phenomena in the synchronization of the multi-agent system. We propose a reduced-order model that approximates the synchronized behavior of the network with both fixed and time-varying topologies and provides a computationally efficient control design strategy based on the time-scale behavior of the networks. The first result presents the emergent dynamic based approximation of the heterogeneous linear multi-agent systems connected over time-varying topology. Using a coordinate transformation, the closed-loop network dynamics is reformulated into mean-field and error dynamics. Then by choosing a sufficiently large coupling gain, we represent the dynamics in new coordinates in standard singular perturbation form. This allows decoupling into reduced-order slow and fast dynamics using time-scale separation. Moreover, due to high gain, the network is practically synchronized, and its synchronized behavior can be approximated by reduced-orderslow dynamics independent of the control gains. The results are ensured for strongly connected networks under fairly mild assumptions by introducing a minimum dwell time between two consecutive switches.The second result proposes a novel three time-scale modeling of the clustered networks. Using a two-stage coordinate transformation, the network dynamics is reformulated into new coordinates, namely, mean-field, intra-cluster error, and inter-cluster error dynamics. Then with a suitable choice of parameters, we show that the network dynamics can be represented in a two-parameter standard singular perturbation form in the new coordinate system. The mean-field dynamics, which is the network's long-term behavior, evolve on the slowest time- scale. The intra-cluster error dynamics, which characterize the synchronization inside clusters, evolve on the fastest time scale. Finally, the inter-cluster error dynamics, which characterizes the synchronization between clusters, is fast with respect to the mean-field one and slow with respect to the intra-cluster one.In the final result, we present a computationally efficient control design strategy for the clustered network. We design a composite synchronizing controller with two terms: one responsible for the intra-cluster synchronization (internal) and the other achieving the synchronization between clusters (external). The internal controller does not require much computational effort since an analytic expression describes it. The external controller, however, is designed through a satisfaction equilibrium approach. In other words, the internal and external controllers are independently designed, and they ensure a guaranteed satisfactory cost for each cluster
2
Topley, Kevin James. "Average-consensus in a two-time-scale Markov system." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/51262.
Abstract:
In a spatially distributed network of sensors or mobile agents it is often required to compute the average of all local data collected by each member of the group. Obtaining the average of all local data is, for example, sufficient to conduct robust statistical inference; identify the group center of mass and direction of motion; or evenly assign a set of divisible tasks among processors. Due to the spatial distribution of the network, energy limitations and geographic barriers may render a data fusion center to be infeasible or highly inefficient in regard to averaging the local data. The problem of distributively computing the network average - also known as the average-consensus problem - has thus received significant attention in the signal processing and control research communities. Efforts in this direction propose and study distributed algorithms that allow every agent in the network to compute the global average via communication with only a subset of fellow agents.
The thesis will present a framework in which to analyze distributed algorithms for both dynamic and static consensus formation. For dynamic consensus we consider a two-time-scale Markov system wherein each sensor node can observe the state of a local Markov chain. Assuming each Markov chain has a stationary distribution with slowly switching regime, we show that a local stochastic approximation algorithm in conjunction with linear distributed averaging can imply that each node estimate converges weakly to the current average of all stationary distributions. Each node can thus track the average of all stationary distributions, provided the regime switching is sufficiently slow. We then consider static consensus formation when the inter-node communication pattern is a priori unknown and signals possess arbitrarily long time-delays. In this setting, four distributed algorithms are proposed and shown to obtain average-consensus under a variety of general communication conditions.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
3
Sun, Chuili. "Model reduction of systems exhibiting two-time scale behavior or parametric uncertainty." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4993.
Abstract:
Model reduction is motivated by the fact that complex process models may pre-
vent the application of model-based process control. While extensive research on
model reduction has been done in the past few decades, model reduction of systems
exhibiting two-time scale behavior as well as parametric uncertainty has received little
attention to date. This work addresses these types of problems in detail.
Systems with two-time scale behavior can be described by differential-algebraic
equations (DAEs). A new technique based on projections and system identification
is presented for reducing this type of system. This method reduces the order of the
differential equations as well as the number and complexity of the algebraic equations.
Additionally, the algebraic equations of the resulting system can be replaced by an
explicit expression for the algebraic variables such as a feed-forward neural network
or partial least squares. This last property is important insofar as the reduced model
does not require a DAE solver for its solution, but system trajectories can instead be
computed with regular ordinary differential equation (ODE) solvers.
For systems with uncertain parameters, two types of problems are investigated,
including parameter reduction and parameter dependent model reduction. The pa-
rameter reduction problem is motivated by the fact that a large number of parameters
exist in process models while some of them contribute little to a system's input-output behavior. This portion of the work presents three novel methodologies which include
(1) parameter reduction where the contribution is measured by Hankel singular val-
ues, (2) reduction of the parameter space via singular value decomposition, and (3)
a combination of these two techniques.
Parameter dependent model reduction investigates how to incorporate the influ-
ence of parameters in the procedure of conventional model reductions. An approach
augmenting the input vector to include the parameters are developed to solve this
problem.
Finally, a nonlinear model predictive control scheme is developed in which the
reduced models are used for the controller.
Examples are investigated to illustrate these techniques. The results show that
excellent performance can be obtained for the reduced models.
4
Theodoro, Edson Aparecido Rozas. "Contribuição à análise de estabilidade transitória, em duas escalas de tempo, de sistemas elétricos de potência via métodos diretos." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-09052013-151230/.
Abstract:
O presente trabalho tem como objetivo investigar a presença de diferentes escalas de tempo nos modelos matemáticos que descrevem a dinâmica dos sistemas elétricos de potência (SEPs), em particular a existência de duas escalas de tempo distintas: lenta e rápida, e explorá-las no estudo de estabilidade transitória destes sistemas através da utilização de métodos diretos (funções energia). Em particular, o método do Ponto de Equilíbrio Instável de Controle (CUEP) para modelos com duas escalas de tempo será estudado e aplicado na análise de estabilidade transitória de SEPs. As bases teóricas para a análise de estabilidade transitória, de sistemas com duas escalas de tempo, serão apresentadas, assim como funções energia e novos algoritmos numéricos para o cálculo do CUEP nestes sistemas, a fim de evidenciar as melhorias e possíveis limitações deste novo método CUEP em duas escalas de tempo quando comparado ao método CUEP tradicional. Explorando as escalas de tempo lenta e rápida na análise de estabilidade transitória, espera-se que novos algoritmos numéricos mais robustos para o cálculo do CUEP sejam obtidos, assim como a diminuição do conservadorismo dos resultados.The main objective of this work is to investigate the existence of several time-scales in the mathematical models of electric power systems, in particular the existence of two-time scales: slow and fast, and exploit these features in the direct transient stability assessment. In particular, the Controlling Unstable Equilibrium Point (CUEP) method is studied for two-time scale models of power systems and applied to transient stability analysis. In order to accomplish this aim, a sound theoretical basis for two-time scale transient stability analysis of electric power system models will be provided, as well as energy functions and new numerical algorithms for proper two-time scale CUEP calculations, with the purpose of investigating improvements and possible limitations of this method when compared with the traditional CUEP method. Exploiting the two-time scale features of power system models, it is intended to obtain new robust numerical algorithms for transient stability analysis, as well as to diminish the conservativeness of the results.
5
LI, ZHEN-XING, and 李振興. "Robust stabilizing control of two-time-scale discrete-time systems." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/92869013550851564295.
6
Gong, Fei. "Fault detection and isolation of two time-scaled singularly perturbed systems." Thesis, 2006. http://spectrum.library.concordia.ca/8766/1/MR14257.pdf.
Abstract:
Singular perturbations technique is a means of taking into account neglected high-frequency and parasitic phenomena into modeling systems by decoupling the representation into separate slow and fast time-scales. The practical advantages of a singular perturbation in model order are significant, since the order of every real dynamical system is higher than that of the model used to represent the system. This thesis focus is emphasized on the fault diagnosis of two time-scaled singularly perturbed systems. By decoupling the original full-order system into higher-order slow and fast subsystem models, our goal is to design a composite diagnoser based on diagnosers designed for the two subsystems to detect and isolate the faults in the original full-order system. Based on a power series expansion of the exact slow manifold associated with the original model around [varepsilon] = 0 , higher-order corrections of the manifold are obtained. Conditions are formulated for which a composite diagnoser can be designed for the original full-order system. Satisfying the conditions of a geometric approach, this composite diagnoser is used to diagnose the faults in the original full-order system. The illustrated methodology is applied to a two time-scale aircraft longitudinal dynamical model as well as the four degree of freedom gyroscope.
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LI, ZU-SHEN, and 李祖聖. "Stabilization and model-following control of linear two-time-scale systems." Thesis, 1989. http://ndltd.ncl.edu.tw/handle/16217723716775044638.
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李振興. "Output feedback control of singular perturbation and two-time-scale systems: theory and applications." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/91920959271949170309.
Books on the topic "Two-Time scales systems":
1
D, Moerder Daniel, Langley Research Center, and United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch., eds. Two time scale output feedback regulation for ill-conditioned systems. [Washington, D.C.]: National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1986.
2
Zhang, Qing, and G. George Yin. Discrete-Time Markov Chains: Two-Time-Scale Methods and Applications. Springer New York, 2010.
3
Zhang, Qing, and G. George Yin. Discrete-Time Markov Chains: Two-Time-Scale Methods and Applications (Stochastic Modelling and Applied Probability Book 55). Springer New York, 2006.
4
Chhibber, Pradeep K., and Rahul Verma. State Formation and Ideological Conflict in Multiethnic Countries. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190623876.003.0002.
Abstract:
The standard narrative of what defines an ideological conflict for electoral politics is not applicable to multiethnic countries like India. We develop two alternative ideological scales, the politics of statism and the politics of recognition, which we argue frame the Indian party system. Debates around class conflict, and about divisions between church and state, cities and rural areas, and the center and the periphery, were less central to the formation of the Indian state than were the state’s role in development and its efforts to accommodate marginalized groups. An ideological divide should not merely be the province of a political elite but should also be stable over time—it must be found in partisan differences across decades and there must be a mechanism by which the ideas associated with this divide are transmitted from the elite to the voters.
5
Knight, Andrew P. Innovations in unobtrusive methods. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198796978.003.0004.
Abstract:
Andrew P. Knight explores developments in unobtrusive research methods using unconventional sources of data from computer-based systems and tools. These generate novel measures of behaviour based on the digital trace data that we all generate, online access to public and personal archives, wearable sensors, and the automatic coding of text, and audio and video recordings. Smartphones and wristbands are just two of the growing range of connected devices that are capable of capturing and sharing multimedia information in real-time. Devices such as these offer new ways in which researchers can gather data at low cost, avoiding reactance effects, allowing the study of how phenomena change over time, and expanding the scale of research, given the wide dissemination of the technology. Before adopting these methods, researchers need to consider whether they have the expertise, and the ethical issues raised by using information (which may be in the public domain) without informed consent.
6
Holdaway, Simon, and Patricia Fanning. Geoarchaeology of Aboriginal Landscapes in Semi-arid Australia. CSIRO Publishing, 2014. http://dx.doi.org/10.1071/9780643108950.
Abstract:
This book provides readers with a unique understanding of the ways in which Aboriginal people interacted with their environment in the past at one particular location in western New South Wales. It also provides a statement showing how geoarchaeology should be conducted in a wide range of locations throughout Australia.
One of the key difficulties faced by all those interested in the interaction between humans and their environment in the past is the complex array of processes acting over different spatial and temporal scales. The authors take account of this complexity by integrating three key areas of study – geomorphology, geochronology and archaeology – applied at a landscape scale, with the intention of understanding the record of how Australian Aboriginal people interacted with the environment through time and across space.
This analysis is based on the results of archaeological research conducted at the University of New South Wales Fowlers Gap Arid Zone Research Station between 1999 and 2002 as part of the Western New South Wales Archaeology Program. The interdisciplinary geoarchaeological program was targeted at expanding the potential offered by archaeological deposits in western New South Wales, Australia.
The book contains six chapters: the first two introduce the study area, then three data analysis chapters deal in turn with the geomorphology, geochronology and archaeology of Fowlers Gap Station. A final chapter considers the results in relation to the history of Aboriginal occupation of Fowlers Gap Station, as well as the insights they provide into Aboriginal ways of life more generally. Analyses are well illustrated through the tabulation of results and the use of figures created through Geographic Information System software.
Winner of the 2015 Australian Archaeology Association John Mulvaney Book Award
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Lane, Christel. Publicans Between the State and the Brewers: A Subordinate Relationship. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198826187.003.0006.
Abstract:
Throughout most of the period covered in this book, establishments that sell alcohol consumed on the premises have had regulation imposed on them. Regulation and control have weighed more heavily on pubs than on the other two types of hostelries and, given their chief customer base, on the working class. Another state instrument to weaken pubs has been high taxation. The conditions for running pubs and publicans’ livelihoods were just as strongly influenced by the giant breweries as they were by state regulation and taxation. Particular attention is paid to the ‘tied houses’ system from the early eighteenth century onwards and to the more recent Beer Orders Act (1989). Over time, this Act had the effect of substituting the tie of pubs to breweries with that of pub companies. The ensuing dependence of tenants and the adverse effect on their livelihoods is viewed as contributing to the large-scale pub closures in the twenty-first century.
8
Hangan, Horia, and Ahsan Kareem, eds. The Oxford Handbook of Non-Synoptic Wind Storms. Oxford University Press, 2020. http://dx.doi.org/10.1093/oxfordhb/9780190670252.001.0001.
Abstract:
This handbook is currently in development, with individual articles publishing online in advance of print publication. At this time, we cannot add information about unpublished articles in this handbook, however the table of contents will continue to grow as additional articles pass through the review process and are added to the site. Please note that the online publication date for this handbook is the date that the first article in the title was published online. For more information, please read the site FAQs. Wind storms impact human lives, their built as well as natural habitat. During the last century, society’s vulnerability to wind storms has been reduced by enhanced knowledge of their impact and by controlling exposure through better design. However, only two of the wind systems have so far been considered in the design of buildings and structures, i.e., synoptic winds resulting from macroscale weather systems spanning thousands of kilometers, e.g., extratropical storms, and mesoscale tropical storms spanning hundreds of kilometers and traveling fast, e.g., hurricanes/typhoons/cyclones. During the last two decades, enough evidence has surfaced to support that a third type of very localized wind storms, the non-synoptic winds, are the most damaging in some regions of the world. Thus far there are no design provisions established for the codification of these wind storms. Their characterization in terms of climatology, wind field and intensity, frequency and occurrence, as well as their impact on the built environment, is slowly developing. This handbook presents the state-of-the-art of knowledge related to all these features including their risk, insurance issues, and economics. The research in this area is on the one hand more arduous given the reduced scale, the three-dimensionality, and nonstationary aspects of these non-synoptic winds while, at the same time, its understanding and modeling are being aided by the emergence of novel modeling and simulation techniques which are addressed in this handbook. This will serve as a guiding resource for those interested in learning about and contributing to the advancement of the field.
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Golann, Bret. Navigating the Whitewater Rapids of Entrepreneurial Success. ABC-CLIO, LLC, 2016. http://dx.doi.org/10.5040/9798400690266.
Abstract:
This book provides entrepreneurs with a clear, specific road map to successful business and growth management, explaining the vital details of techniques for executing changes in day-to-day business operations to handle rapid business growth. For many entrepreneurs, the transition from start-up to rapid growth is the most difficult and risky time for them and their companies. Failure to manage business growth occurs not because entrepreneurs choose the wrong growth strategy; it’s because leaders and employees fail to execute the right internal strategies to scale up business operations to handle market success. This book explains how to overcome the two fundamental challenges facing successful entrepreneurs as their businesses grow: how to develop the efficiency, reliability, and cost control of a successful company given the common constraints of too little time and too few resources, such as money and people, and how to achieve these essential attributes of business performance without losing the entrepreneurial creativity and spirit that made them successful in the first place. Readers will learn why so many smart entrepreneurs fail in managing business success and growth, as well as how to change day-to-day leadership approaches and techniques in moving from fledgling start-up to the rapid growth stage that involves many more expectations from employees, customers, and investors. The book serves as a “how-to” guide for leading growth that demonstrates how to execute internal growth strategies to develop the needed flexible systems, performance measures, management techniques, and rewards and risk management strategies.
10
McGreavy, Bridie, and David Hart. Sustainability Science and Climate Change Communication. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.563.
Abstract:
Direct experience, scientific reports, and international media coverage make clear that the breadth, severity, and multiple consequences from climate change are far-reaching and increasing. Like many places globally, the northeastern United States is already experiencing climate change, including one of the world’s highest rates of ocean warming, reduced durations of winter ice cover on lakes, a marked increase in the frequency of extreme precipitation events, and climate-mediated ecological disruptions of invasive species. Given current and projected changes in ecosystems, communities, and economies, it is essential to find ways to anticipate and reduce vulnerabilities to change and, at the same time, promote sustainable economic development and human well-being.The emerging field of sustainability science offers a promising conceptual and analytic framework for accelerating progress towards sustainable development. Sustainability science aims to be use-inspired and to connect basic and applied knowledge with solutions for societal benefit. This approach draws from diverse disciplines, theories, and methods organized around the broad goal of maintaining and improving life support systems, ecosystem health, and human well-being. Partners in New England have been using sustainability science as a framework for stakeholder-engaged, interdisciplinary research that has generated use-inspired knowledge and multiple solutions for more than a decade. Sustainability science has helped produce a landscape-scale approach to wetland conservation; emergency response plans for invasive species that threaten livelihoods and cultures; decision support tools for improved water quality management and public health for beach use and shellfish consumption; and the development of robust partnership networks across disciplines and institutions. Understanding and reducing vulnerability to climate change is a central motivating factor in this portfolio of projects because linking knowledge about social-ecological systems with effective policy action requires a holistic view that addresses complex intersecting stressors.One common theme in these varied efforts is the way that communication fundamentally shapes collaborative research and social, technical, and policy outcomes from sustainability science. Communication as a discipline has, for more than two thousand years, sought to understand how environments and symbols shape human life, forms of social organization, and collective decision making. The result is a body of scholarship and practical techniques that are diverse and well adapted to meet the complexity of contemporary sustainability challenges. The complexity of the issues that sustainability science aspires to solve requires diversity and flexibility to be able to adapt approaches to the specific needs of a situation. Long-term, cross-scale, and multi-institutional sustainability science collaborations show that communication research and practice can help build communities and networks, and advance technical and policy solutions to confront the challenges of climate change and promote sustainability now and in future.
Book chapters on the topic "Two-Time scales systems":
1
Dragan, Vasile, and Aristide Halanay. "Stabilization of Linear Systems with Two Time Scales." In Systems & Control: Foundations & Applications, 91–132. Boston, MA: Birkhäuser Boston, 1999. http://dx.doi.org/10.1007/978-1-4612-1570-7_3.
2
Liu, Xinzhi, and Kexue Zhang. "Stability in Terms of Two Measures of Impulsive Systems on Time Scales." In Impulsive Systems on Hybrid Time Domains, 213–59. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-06212-5_8.
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Zhang, B. X., J. L. Huang, and W. D. Zhu. "Incremental Harmonic Balance with Two Time Scales for a Nonlinear Quasi-Periodic Mathieu Equation." In Advances in Nonlinear Dynamics and Control of Mechanical and Physical Systems, 39–52. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-7958-5_3.
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Arnold, Ludwig. "Linear and Nonlinear Diffusion Approximation of the Slow Motion in Systems with Two Time Scales." In Solid Mechanics and Its Applications, 5–18. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-010-0179-3_1.
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Trémon, Anne-Christine. "Scales of Change and Diagnostic Contradictions: Shifting Relations Between an Emigrant Community and Its Diaspora." In Methodological Approaches to Societies in Transformation, 33–59. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-65067-4_2.
Abstract:
AbstractThe specific question this chapter addresses is how to account ethnographically for change that unfolds on spatial and temporal scales larger than those of the ethnographic field study without opposing the local site to global forces. My research engages a processual approach which examines the effects of China’s transformations and the creation of the Shenzhen Special Economic Zone on the relationship between the members of a former emigrant community and their diaspora. I propose an analytical distinction between two relational dimensions of scale in which social action can be considered: scale as the scope of social systems or chains of interdependence that extend in space and time and in which actions and interactions take place, and scale as valence, i.e., the desirability of scale defined relative to other scales, generating “scalar projects.” I focus on how contradictions in the collected field materials are telling signs of accelerated change that generate conflicts of scale, and use such “diagnostic contradictions” as a starting point for understanding how people attempt to make sense of rapid change and reconceptualize the valence of local and global scales.
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Tesfaye, Bezaye, Nikolaus Augsten, Mateusz Pawlik, Michael H. Böhlen, and Christian S. Jensen. "An Efficient Index for Reachability Queries in Public Transport Networks." In Advances in Databases and Information Systems, 34–48. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-54832-2_5.
Abstract:
AbstractComputing path queries such as the shortest path in public transport networks is challenging because the path costs between nodes change over time. A reachability query from a node at a given start time on such a network retrieves all points of interest (POIs) that are reachable within a given cost budget. Reachability queries are essential building blocks in many applications, for example, group recommendations, ranking spatial queries, or geomarketing. We propose an efficient solution for reachability queries in public transport networks. Currently, there are two options to solve reachability queries. (1) Execute a modified version of Dijkstra’s algorithm that supports time-dependent edge traversal costs; this solution is slow since it must expand edge by edge and does not use an index. (2) Issue a separate path query for each single POI, i.e., a single reachability query requires answering many path queries. None of these solutions scales to large networks with many POIs. We propose a novel and lightweight reachability index. The key idea is to partition the network into cells. Then, in contrast to other approaches, we expand the network cell by cell. Empirical evaluations on synthetic and real-world networks confirm the efficiency and the effectiveness of our index-based reachability query solution.
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Carstens, Niko, Maik-Ivo Terasa, Pia Holtz, Sören Kaps, Thomas Strunskus, Abdou Hassanien, Rainer Adelung, Franz Faupel, and Alexander Vahl. "Memristive Switching: From Individual Nanoparticles Towards Complex Nanoparticle Networks." In Springer Series on Bio- and Neurosystems, 219–39. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-36705-2_9.
Abstract:
AbstractNovel hardware concepts in the framework of neuromorphic engineering are intended to overcome fundamental limits of current computer technologies and to be capable of efficient mass data processing. To reach this, research into material systems which enable the implementation of memristive switching in electronic devices, as well as into analytical approaches helping to understand fundamental mechanisms and dynamics of memristive switching is inevitable. In this chapter, memristive switching based on Ag metal filament formation is discussed throughout different scales, providing insights on the stability of metal filaments and the onset of collective behaviour. An unconventional cAFM approach, which intends to integrate the memristive system directly on the apex of the cantilever instead of usual contacting is presented. This facilitates the nanoscale probing of filamentary memristive switching dynamics on long time scales for the purpose of basic research, which is demonstrated by an archetypical electrochemical metallization (ECM) based system consisting of Ag/Si3N4/Au. Further, the application of AgAu and AgPt noble metal alloy nanoparticles (NPs) for memristive devices is discussed with special focus on the device scalability. For the smallest scale it is shown, that a single AgPt-NP encapsulated in SiO2 operates via stable diffusive switching. Finally, two concepts for the self-assembled fabrication of NP-based memristive switch networks are evaluated regarding to collective switching dynamics: A sub-percolated CNT network decorated with AgAu-NPs and a Ag-NP network poised at the percolation threshold. The hybrid CNT/AgAu-NPs networks exhibit a mixed form of diffusive and bipolar switching, which is very interesting for tailoring the retention time, while the networks dynamics of percolated Ag-NP networks are governed by ongoing transitions between a multitude of metastable states, which makes them interesting for reservoir computing and other neuromorphic computation schemes.
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Champion, David C., and David L. Huston. "Applications of Neodymium Isotopes to Ore Deposits and Metallogenic Terranes; Using Regional Isotopic Maps and the Mineral Systems Concept." In Isotopes in Economic Geology, Metallogenesis and Exploration, 123–54. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-27897-6_5.
Abstract:
AbstractAlthough radiogenic isotopes historically have been used in ore genesis studies for age dating and as tracers, here we document the use of regional- and continental-scale Sm–Nd isotope data and derived isotopic maps to assist with metallogenic interpretation, including the identification of metallogenic terranes. For the Sm–Nd system, calculated Nd model ages, which are time independent, are of most value for small-scale isotopic maps. Typically, one- or two-stage depleted mantle model ages (TDM, T2DM) are used to infer age when the isotope characteristics of the rock were in isotopic equilibrium with a modelled (mantle) reservoir. An additional advantage is that Nd model ages provide, with a number of assumptions, an estimate of the approximate age of continental crust in a region. Regional- and continental-scale Nd model age maps, constructed from rocks such as granites, which effectively sample the middle to lower crust, therefore, provide a proxy to constrain the nature of the crust within a region. They are of increasing use in metallogenic analysis, especially when combined with a mineral systems approach, which recognizes that mineral deposits are the result of geological processes, at a scales from the ore shoot to the craton. These maps can be used empirically and/or predictively to identify and target large parts of mineral systems that may be indicative, or form part of, metallogenic terranes. Examples presented here include observed spatial relationships between mineral provinces and isotopic domains; the identification of old and/or thick cratonic blocks; determination of tectonic regimes favorable for mineralization; identification of isotopically juvenile zones that may indicate rifts or primitive arcs; recognition of crustal breaks that define metallogenic terrane boundaries or delineate fluid pathways; and, as baseline maps. Of course, any analysis of Sm–Nd and similar isotopic maps are predicated on integration with geological, geochemical and geophysical information data. In the future, research in this area should focus on the spatial and temporal evolution of the whole lithosphere at the province- to global-scales to more effectively targeting mineral exploration. This must involve integration of radiogenic isotopic data with other data, in particular, geophysical data, which has the advantage of being able to directly image the crust and lithosphere and being of a more continuous nature as compared to invariably incomplete isotopic data sets.
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Tellili, A., N. Abdelkrim, A. Challouf, A. Elghoul, and M. N. Abdelkrim. "Fault-Tolerant Control of Two-Time-Scale Systems." In Studies in Systems, Decision and Control, 235–64. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-1746-4_12.
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Gu, Mengqi, Guo-ping Jiang, Juan Qian, and Yayong Wu. "Controllability of Two-Time-Scale Continuous-Time Multi-agent Systems with Switching Topology." In Proceedings of 2021 5th Chinese Conference on Swarm Intelligence and Cooperative Control, 1303–14. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-3998-3_122.
Conference papers on the topic "Two-Time scales systems":
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Shen, Zuojun, and Ping Lu. "Control of nonlinear systems with two time scales." In AIAA Guidance, Navigation, and Control Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2001. http://dx.doi.org/10.2514/6.2001-4166.
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Gomez-Exposito, Antonio, Catalina Gomez-Quiles, and Izudin Dzafic. "State estimation in two time scales for smart distribution systems." In 2015 IEEE Power & Energy Society General Meeting. IEEE, 2015. http://dx.doi.org/10.1109/pesgm.2015.7286249.
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Wang, Peng, Guangyuan Zhang, Cui Ni, and Kefeng Li. "A Two Time-Scales Network Bandwidth Measurement for Video Transmission." In 2016 International Conference on Network and Information Systems for Computers (ICNISC). IEEE, 2016. http://dx.doi.org/10.1109/icnisc.2016.022.
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Xia, Zhengwei. "Strict Stability of Dynamic Systems in Terms of Two Measurements on Time Scales." In 2008 ISECS International Colloquium on Computing, Communication, Control, and Management. IEEE, 2008. http://dx.doi.org/10.1109/cccm.2008.36.
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Fu, Zhi-Jun, W. F. Xie, and S. Liu. "Adaptive nonlinear systems identification via dynamic multilayer neural networks with two-time scales." In 2013 IEEE International Conference on Control Applications (CCA). IEEE, 2013. http://dx.doi.org/10.1109/cca.2013.6662884.
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Chen, Jia-Rui, Wu Yang, and Xiao-Kang Liu. "Robust fault-tolerant consensus for two time-scales agent systems with sensor faults*." In 2022 IEEE 17th International Conference on Control & Automation (ICCA). IEEE, 2022. http://dx.doi.org/10.1109/icca54724.2022.9831938.
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Wang, Weixuan, Alejandro I. Maass, Dragan Nešić, Ying Tan, Romain Postoyan, and W. P. M. H. Heemels. "Stability of Nonlinear Systems with Two Time Scales Over a Single Communication Channel." In 2023 62nd IEEE Conference on Decision and Control (CDC). IEEE, 2023. http://dx.doi.org/10.1109/cdc49753.2023.10383875.
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Radisavljevic-Gajic, Verica. "A Simplified Two-Stage Design of Linear Discrete-Time Feedback Controllers With Applications to Systems With Slow and Fast Modes." In ASME 2014 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/dscc2014-6278.
Abstract:
In this paper we have shown how to simplify an algorithm for the two stage design of linear feedback controllers by reducing computational requirements. The algorithm is further simplified for linear discrete-time systems with slow and fast modes (multi-time scale systems or singularly perturbed systems) providing independent and accurate designs in slow and fast time scales. The simplified design procedure and its very high accuracy are demonstrated on the eigenvalue assignment problem of a steam power system.
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Plohl, Gregor, and Günter Brenn. "Measurement of polymeric time scales from linear drop oscillations." In ILASS2017 - 28th European Conference on Liquid Atomization and Spray Systems. Valencia: Universitat Politècnica València, 2017. http://dx.doi.org/10.4995/ilass2017.2017.4686.
Abstract:
The oscillating drop method allows material properties of liquids to be measured from damped drop oscillations. Theliterature discusses, e.g., the measurement of the liquid dynamic viscosity and the surface tension against the ambient medium, predominantly for Newtonian liquids. We use this method for measuring pairs of material properties of polymeric liquids. Pairs of properties may be measured, since the quantity measured is a complex frequency with a real and an imaginary part. For the measurements, individual drops are levitated in air by an ultrasonic levitator and imaged with a high-speed camera. Amplitude modulation of the ultrasound drives shape oscillations of the levitated drop. When the modulation is switched off, with the levitating force maintained, the drop performs free oscillations which are damped due to the liquid viscosity. The data acquired from the images recorded are the angular frequency and the damping rate which are used as an input into the characteristic equation of the oscillating drop. Our measurements intend to yield either two viscoelastic time scales with the zero-shear viscosity known, or one time scale and the zero-shear viscosity, with the other time scale known. The two time scales are the stress relaxation and the deformation retardation times. The latter is difficult to get for polymer solutions.The present contribution presents results from a large set of measurements of the deformation retardation time. Liquids studied are aqueous solutions of poly(acryl-amides) at varying concentration. The corresponding values of the zero-shear viscosity agree well with the values from shear rheometry. Values of the deformation retardation time differ substantially from the values commonly used in viscoelastic flow simulations. Furthermore, the measured values disagree with the predictions from the viscous-elastic stress splitting approach in linear viscoelasticity. With our study we will provide a consistent set of material properties for the Oldroyd-B model in linear viscoelasticity. This will beimportant for material modelling in viscoelastic spray simulations.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4686
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Papáček, Štěpán, and Ctirad Matonoha. "Testing the method of multiple scales and the averaging principle for model parameter estimation of quasiperiodic two time-scale models." In Programs and Algorithms of Numerical Mathematics 21. Institute of Mathematics, Czech Academy of Sciences, 2023. http://dx.doi.org/10.21136/panm.2022.15.
Abstract:
Some dynamical systems are characterized by more than one time-scale, e.g. two well separated time-scales are typical for quasiperiodic systems. The aim of this paper is to show how singular perturbation methods based on the slow-fast decomposition can serve for an enhanced parameter estimation when the slowly changing features are rigorously treated. Although the ultimate goal is to reduce the standard error for the estimated parameters, here we test two methods for numerical approximations of the solution of associated forward problem: (i) the multiple time-scales method, and (ii) the method of averaging. On a case study, being an under-damped harmonic oscillator containing two state variables and two parameters, the method of averaging gives well (theoretically predicted) results, while the use of multiple time-scales method is not suitable for our purposes.
Reports on the topic "Two-Time scales systems":
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Collins, Clarence O., and Tyler J. Hesser. altWIZ : A System for Satellite Radar Altimeter Evaluation of Modeled Wave Heights. Engineer Research and Development Center (U.S.), February 2021. http://dx.doi.org/10.21079/11681/39699.
Abstract:
This Coastal and Hydraulics Engineering Technical Note (CHETN) describes the design and implementation of a wave model evaluation system, altWIZ, which uses wave height observations from operational satellite radar altimeters. The altWIZ system utilizes two recently released altimeter databases: Ribal and Young (2019) and European Space Agency Sea State Climate Change Initiative v.1.1 level 2 (Dodet et al. 2020). The system facilitates model evaluation against 1 Hz1 altimeter data or a product created by averaging altimeter data in space and time around model grid points. The system allows, for the first time, quantitative analysis of spatial model errors within the U.S. Army Corps of Engineers (USACE) Wave Information Study (WIS) 30+ year hindcast for coastal United States. The system is demonstrated on the WIS 2017 Atlantic hindcast, using a 1/2° basin scale grid and a 1/4° regional grid of the East Coast. Consistent spatial patterns of increased bias and root-mean-square-error are exposed. Seasonal strengthening and weakening of these spatial patterns are found, related to the seasonal variation of wave energy. Some model errors correspond to areas known for high currents, and thus wave-current interaction. In conjunction with the model comparison, additional functions for pairing altimeter measurements with buoy data and storm tracks have been built. Appendices give information on the code access (Appendix I), organization and files (Appendix II), example usage (Appendix III), and demonstrating options (Appendix IV).
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Karstensen, Johannes, Alexandra Andrae, Ludwig Bitzan, Jakob Deutloff, Christiane Lösel, Paul J. Witting, Nils O. Niebaum, et al. Student cruise: Observing techniques for Physical Oceanographers Cruise No. AL529. GEOMAR, 2020. http://dx.doi.org/10.3289/cr_al529.
Abstract:
Oct. 07 2019 – Oct. 10, 2019 Kiel (Germany) – Kiel (Germany) MNF-Pher-110The main purpose of the ALKOR cruise AL529 was the training of students in observational techniques applied by physical oceanographers. The students who participated in the trip attend the module "Measurement Methods of Oceanography" which is offered in the Bachelor program "Physics of the Earth System" at CAU Kiel. During the AL529 the students were instructed in instrument calibration and in the interpretation of measurement data at sea. In addition, the students had the opportunity to learn about working and living at sea and to explore and study the impact of physical processes in the western Baltic Sea, the sea at their doorstep. The observations show a quasi-synoptic picture of the hydrography and currents in the western Baltic Sea. Twice-repeated hydrographic and current sections across the Fehmarn Belt show well the short time scales where significant changes occur. A zonal section along the deepest topography, from about 10°40'E to 014°21'E, shows very nicely the two-layer system of outflowing low salinity and inflowing North Sea water. A bottom shield anchorage shows the currents in the water column and the near-bottom temperature and salinity variations in the Fehmarnbelt area.
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Fourrier, Marine. Integration of in situ and satellite multi-platform data (estimation of carbon flux for trop. Atlantic). EuroSea, 2023. http://dx.doi.org/10.3289/eurosea_d7.6.
Abstract:
This report presents the results of task 7.3 on “Quantification of improvements in carbon flux data for the tropical Atlantic based on the multi-platform and neural network approach”. To better constrain changes in the ocean’s capture and sequestration of CO2 emitted by human activities, in situ measurements are needed. Tropical regions are considered to be mostly sources of CO2 to the atmosphere due to specific circulation features, with large interannual variability mainly controlled by physical drivers (Padin et al., 2010). The tropical Atlantic is the second largest source, after the tropical Pacific, of CO2 to the atmosphere (Landschützer et al., 2014). However, it is not a homogeneous zone, as it is affected by many physical and biogeochemical processes that vary on many time scales and affect surrounding areas (Foltz et al., 2019). The Tropical Atlantic Observing System (TAOS) has progressed substantially over the past two decades. Still, many challenges and uncertainties remain to require further studies into the area’s role in terms of carbon fluxes (Foltz et al., 2019). Monitoring and sustained observations of surface oceanic CO2 are critical for understanding the fate of CO2 as it penetrates the ocean and during its sequestration at depth. This deliverable relies on different observing platforms deployed specifically as part of the EuroSea project (a Saildrone, and 5 pH-equipped BGC-Argo floats) as well as on the platforms as part of the TAOS (CO2-equipped moorings, cruises, models, and data products). It also builds on the work done in D7.1 and D7.2 on the deployment and quality control of pH-equipped BGC-Argo floats and Saildrone data. Indeed, high-quality homogeneously calibrated carbonate variable measurements are mandatory to be able to compute air-sea CO2 fluxes at a basin scale from multiple observing platforms. (EuroSea Deliverable, D7.6)
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Akinleye, Taiwo, Idil Deniz Akin, Amanda Hohner, Indranil Chowdhury, Richards Watts, Xianming Shi, Brendan Dutmer, James Mueller, and Will Moody. Evaluation of Electrochemical Treatment for Removal of Arsenic and Manganese from Field Soil. Illinois Center for Transportation, June 2021. http://dx.doi.org/10.36501/0197-9191/21-019.
Abstract:
Soils containing inorganic compounds are frequently encountered by transportation agencies during construction within the right-of-way, and they pose a threat to human health and the environment. As a result, construction activities may experience project delays and increased costs associated with management of inorganic compounds containing soils required to meet environmental regulations. Recalcitrance of metal-contaminated soils toward conventional treatment technologies is exacerbated in clay or organic content-rich fine-grained soils with low permeability and high sorption capacity because of increased treatment complexity, cost, and duration. The objective of this study was to develop an accelerated in situ electrochemical treatment approach to extract inorganic compounds from fine-grained soils, with the treatment time comparable to excavation and off-site disposal. Three reactor experiments were conducted on samples collected from two borehole locations from a field site in Illinois that contained arsenic (As)(~7.4 mg/kg) and manganese (Mn)(~700 mg/kg). A combination of hydrogen peroxide (H2O2) and/or citrate buffer solution was used to treat the soils. A low-intensity electrical field was applied to soil samples using a bench-scale reactor that resembles field-scale in situ electrochemical systems. For the treatment using 10% H2O2 and citrate buffer solution, average removal of 23% and 8% were achieved for Mn and As, respectively. With 4% H2O2 and citrate buffer, 39% and 24% removal were achieved for Mn and As; while using only citrate buffer as the electrolyte, 49% and 9% removal were achieved for Mn and As, respectively. All chemical regimes adopted in this study reduced the inorganic compound concentrations to below the maximum allowable concentration for Illinois as specified by the Illinois Environmental Protection Agency. The results from this work indicate that electrochemical systems that leverage low concentrations of hydrogen peroxide and citrate buffer can be effective for remediating soils containing manganese and arsenic.
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Hammad, Ali, and Mohamed Moustafa. Seismic Behavior of Special Concentric Braced Frames under Short- and Long-Duration Ground Motions. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, December 2019. http://dx.doi.org/10.55461/zont9308.
Abstract:
Over the past decade, several long-duration subduction earthquakes took place in different locations around the world, e.g., Chile in 2010, Japan in 2011, China in 2008, and Indonesia in 2004. Recent research has revealed that long-duration, large-magnitude earthquakes may occur along the Cascadia subduction zone of the Pacific Northwest Coast of the U.S. The duration of an earthquake often affects the response of structures. Current seismic design specifications mostly use response spectra to identify the hazard and do not consider duration effects. Thus, a comprehensive understanding of the effect of the duration of the ground motion on structural performance and its design implications is an important issue. The goal of this study was to investigate how the duration of an earthquake affects the structural response of special concentric braced frames (SCBFs). A comprehensive experimental program and detailed analytical investigations were conducted to understand and quantify the effect of duration on collapse capacity of SCBFs, with the goal of improving seismic design provisions by incorporating these effects. The experimental program included large-scale shake table tests, and the analytical program consisted of pre-test and post-test phases. The pre-test analysis phase performed a sensitivity analysis that used OpenSees models preliminarily calibrated against previous experimental results for different configuration of SCBFs. A tornado-diagram framework was used to rank the influence of the different modeling parameters, e.g., low-cycle fatigue, on the seismic response of SCBFs under short- and long-duration ground motions. Based on the results obtained from the experimental program, these models were revisited for further calibration and validation in the post-test analysis. The experimental program included three large-scale shake-table tests of identical single-story single-bay SCBF with a chevron-brace configuration tested under different ground motions. Two specimens were tested under a set of spectrally-matched short and long-duration ground motions. The third specimen was tested under another long-duration ground motion. All tests started with a 100% scale of the selected ground motions; testing continued with an ever-increasing ground-motion scale until failure occurred, e.g., until both braces ruptured. The shake table tests showed that the duration of the earthquake may lead to premature seismic failure or lower capacities, supporting the initiative to consider duration effects as part of the seismic design provisions. Identical frames failed at different displacements demands because of the damage accumulation associated with the earthquake duration, with about 40% reduction in the displacement capacity of the two specimens tested under long-duration earthquakes versus the short-duration one. Post-test analysis focused first on calibrating an OpenSees model to capture the experimental behavior of the test specimens. The calibration started by matching the initial stiffness and overall global response. Next, the low-cycle fatigue parameters were fine-tuned to properly capture the experimental local behavior, i.e., brace buckling and rupture. The post-test analysis showed that the input for the low-cycle fatigue models currently available in the literature does not reflect the observed experimental results. New values for the fatigue parameters are suggested herein based on the results of the three shake-table tests. The calibrated model was then used to conduct incremental dynamic analysis (IDA) using 44 pairs of spectrally-matched short- and long-duration ground motions. To compare the effect of the duration of ground motion, this analysis aimed at incorporating ground-motion variability for more generalized observations and developing collapse fragility curves using different intensity measures (IMs). The difference in the median fragility was found to be 45% in the drift capacity at failure and about 10% in the spectral acceleration (Sa). Using regression analysis, the obtained drift capacity from analysis was found to be reduced by about 8% on average for every additional 10 sec in the duration of the ground motion. The last stage of this study extended the calibrated model to SCBF archetype buildings to study the effect of the duration of ground motion on full-sized structures. Two buildings were studied: a three-story and nine-story build that resembled the original SAC buildings but were modified with SCBFs as lateral support system instead of moment resisting frames. Two planer frames were adopted from the two buildings and used for the analysis. The same 44 spectrally-matched pairs previously used in post-test analysis were used to conduct nonlinear time history analysis and study the effect of duration. All the ground motions were scaled to two hazard levels for the deterministic time history analysis: 10% exceedance in 50 years and 2% exceedance in 50 years. All analysis results were interpreted in a comparative way to isolate the effect of duration, which was the main variable in the ground-motion pairs. In general, the results showed that the analyzed SCBFs experienced higher drift values under the long-duration suite of ground motions, and, in turn, a larger percentage of fractured braces under long-duration cases. The archetype SCBFs analysis provided similar conclusions on duration effects as the experimental and numerical results on the single-story single-bay frame.
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Job, Jacob. Mesa Verde National Park: Acoustic monitoring report. National Park Service, July 2021. http://dx.doi.org/10.36967/nrr-2286703.
Abstract:
In 2015, the Natural Sounds and Night Skies Division (NSNSD) received a request to collect baseline acoustical data at Mesa Verde National Park (MEVE). Between July and August 2015, as well as February and March 2016, three acoustical monitoring systems were deployed throughout the park, however one site (MEVE002) stopped recording after a couple days during the summer due to wildlife interference. The goal of the study was to establish a baseline soundscape inventory of backcountry and frontcountry sites within the park. This inventory will be used to establish indicators and thresholds of soundscape quality that will support the park and NSNSD in developing a comprehensive approach to protecting the acoustic environment through soundscape management planning. Additionally, results of this study will help the park identify major sources of noise within the park, as well as provide a baseline understanding of the acoustical environment as a whole for use in potential future comparative studies. In this deployment, sound pressure level (SPL) was measured continuously every second by a calibrated sound level meter. Other equipment included an anemometer to collect wind speed and a digital audio recorder collecting continuous recordings to document sound sources. In this document, “sound pressure level” refers to broadband (12.5 Hz–20 kHz), A-weighted, 1-second time averaged sound level (LAeq, 1s), and hereafter referred to as “sound level.” Sound levels are measured on a logarithmic scale relative to the reference sound pressure for atmospheric sources, 20 μPa. The logarithmic scale is a useful way to express the wide range of sound pressures perceived by the human ear. Sound levels are reported in decibels (dB). A-weighting is applied to sound levels in order to account for the response of the human ear (Harris, 1998). To approximate human hearing sensitivity, A-weighting discounts sounds below 1 kHz and above 6 kHz. Trained technicians calculated time audible metrics after monitoring was complete. See Methods section for protocol details, equipment specifications, and metric calculations. Median existing (LA50) and natural ambient (LAnat) metrics are also reported for daytime (7:00–19:00) and nighttime (19:00–7:00). Prominent noise sources at the two backcountry sites (MEVE001 and MEVE002) included vehicles and aircraft, while building and vehicle predominated at the frontcountry site (MEVE003). Table 1 displays time audible values for each of these noise sources during the monitoring period, as well as ambient sound levels. In determining the current conditions of an acoustical environment, it is informative to examine how often sound levels exceed certain values. Table 2 reports the percent of time that measured levels at the three monitoring locations were above four key values.
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Derbentsev, V., A. Ganchuk, and Володимир Миколайович Соловйов. Cross correlations and multifractal properties of Ukraine stock market. Politecnico di Torino, 2006. http://dx.doi.org/10.31812/0564/1117.
Abstract:
Recently the statistical characterizations of financial markets based on physics concepts and methods attract considerable attentions. The correlation matrix formalism and concept of multifractality are used to study temporal aspects of the Ukraine Stock Market evolution. Random matrix theory (RMT) is carried out using daily returns of 431 stocks extracted from database time series of prices the First Stock Trade System index (www.kinto.com) for the ten-year period 1997-2006. We find that a majority of the eigenvalues of C fall within the RMT bounds for the eigenvalues of random correlation matrices. We test the eigenvalues of C within the RMT bound for universal properties of random matrices and find good agreement with the results for the Gaussian orthogonal ensemble of random matrices—implying a large degree of randomness in the measured cross-correlation coefficients. Further, we find that the distribution of eigenvector components for the eigenvectors corresponding to the eigenvalues outside the RMT bound display systematic deviations from the RMT prediction. We analyze the components of the deviating eigenvectors and find that the largest eigenvalue corresponds to an influence common to all stocks. Our analysis of the remaining deviating eigenvectors shows distinct groups, whose identities correspond to conventionally identified business sectors. Comparison with the Mantegna minimum spanning trees method gives a satisfactory consent. The found out the pseudoeffects related to the artificial unchanging areas of price series come into question We used two possible procedures of analyzing multifractal properties of a time series. The first one uses the continuous wavelet transform and extracts scaling exponents from the wavelet transform amplitudes over all scales. The second method is the multifractal version of the detrended fluctuation analysis method (MF-DFA). The multifractality of a time series we analysed by means of the difference of values singularity stregth (or Holder exponent) ®max and ®min as a suitable way to characterise multifractality. Singularity spectrum calculated from daily returns using a sliding 250 day time window in discrete steps of 1. . . 10 days. We discovered that changes in the multifractal spectrum display distinctive pattern around significant “drawdowns”. Finally, we discuss applications to the construction of crushes precursors at the financial markets.
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Galili, Naftali, Roger P. Rohrbach, Itzhak Shmulevich, Yoram Fuchs, and Giora Zauberman. Non-Destructive Quality Sensing of High-Value Agricultural Commodities Through Response Analysis. United States Department of Agriculture, October 1994. http://dx.doi.org/10.32747/1994.7570549.bard.
Abstract:
The objectives of this project were to develop nondestructive methods for detection of internal properties and firmness of fruits and vegetables. One method was based on a soft piezoelectric film transducer developed in the Technion, for analysis of fruit response to low-energy excitation. The second method was a dot-matrix piezoelectric transducer of North Carolina State University, developed for contact-pressure analysis of fruit during impact. Two research teams, one in Israel and the other in North Carolina, coordinated their research effort according to the specific objectives of the project, to develop and apply the two complementary methods for quality control of agricultural commodities. In Israel: An improved firmness testing system was developed and tested with tropical fruits. The new system included an instrumented fruit-bed of three flexible piezoelectric sensors and miniature electromagnetic hammers, which served as fruit support and low-energy excitation device, respectively. Resonant frequencies were detected for determination of firmness index. Two new acoustic parameters were developed for evaluation of fruit firmness and maturity: a dumping-ratio and a centeroid of the frequency response. Experiments were performed with avocado and mango fruits. The internal damping ratio, which may indicate fruit ripeness, increased monotonically with time, while resonant frequencies and firmness indices decreased with time. Fruit samples were tested daily by destructive penetration test. A fairy high correlation was found in tropical fruits between the penetration force and the new acoustic parameters; a lower correlation was found between this parameter and the conventional firmness index. Improved table-top firmness testing units, Firmalon, with data-logging system and on-line data analysis capacity have been built. The new device was used for the full-scale experiments in the next two years, ahead of the original program and BARD timetable. Close cooperation was initiated with local industry for development of both off-line and on-line sorting and quality control of more agricultural commodities. Firmalon units were produced and operated in major packaging houses in Israel, Belgium and Washington State, on mango and avocado, apples, pears, tomatoes, melons and some other fruits, to gain field experience with the new method. The accumulated experimental data from all these activities is still analyzed, to improve firmness sorting criteria and shelf-life predicting curves for the different fruits. The test program in commercial CA storage facilities in Washington State included seven apple varieties: Fuji, Braeburn, Gala, Granny Smith, Jonagold, Red Delicious, Golden Delicious, and D'Anjou pear variety. FI master-curves could be developed for the Braeburn, Gala, Granny Smith and Jonagold apples. These fruits showed a steady ripening process during the test period. Yet, more work should be conducted to reduce scattering of the data and to determine the confidence limits of the method. Nearly constant FI in Red Delicious and the fluctuations of FI in the Fuji apples should be re-examined. Three sets of experiment were performed with Flandria tomatoes. Despite the complex structure of the tomatoes, the acoustic method could be used for firmness evaluation and to follow the ripening evolution with time. Close agreement was achieved between the auction expert evaluation and that of the nondestructive acoustic test, where firmness index of 4.0 and more indicated grade-A tomatoes. More work is performed to refine the sorting algorithm and to develop a general ripening scale for automatic grading of tomatoes for the fresh fruit market. Galia melons were tested in Israel, in simulated export conditions. It was concluded that the Firmalon is capable of detecting the ripening of melons nondestructively, and sorted out the defective fruits from the export shipment. The cooperation with local industry resulted in development of automatic on-line prototype of the acoustic sensor, that may be incorporated with the export quality control system for melons. More interesting is the development of the remote firmness sensing method for sealed CA cool-rooms, where most of the full-year fruit yield in stored for off-season consumption. Hundreds of ripening monitor systems have been installed in major fruit storage facilities, and being evaluated now by the consumers. If successful, the new method may cause a major change in long-term fruit storage technology. More uses of the acoustic test method have been considered, for monitoring fruit maturity and harvest time, testing fruit samples or each individual fruit when entering the storage facilities, packaging house and auction, and in the supermarket. This approach may result in a full line of equipment for nondestructive quality control of fruits and vegetables, from the orchard or the greenhouse, through the entire sorting, grading and storage process, up to the consumer table. The developed technology offers a tool to determine the maturity of the fruits nondestructively by monitoring their acoustic response to mechanical impulse on the tree. A special device was built and preliminary tested in mango fruit. More development is needed to develop a portable, hand operated sensing method for this purpose. In North Carolina: Analysis method based on an Auto-Regressive (AR) model was developed for detecting the first resonance of fruit from their response to mechanical impulse. The algorithm included a routine that detects the first resonant frequency from as many sensors as possible. Experiments on Red Delicious apples were performed and their firmness was determined. The AR method allowed the detection of the first resonance. The method could be fast enough to be utilized in a real time sorting machine. Yet, further study is needed to look for improvement of the search algorithm of the methods. An impact contact-pressure measurement system and Neural Network (NN) identification method were developed to investigate the relationships between surface pressure distributions on selected fruits and their respective internal textural qualities. A piezoelectric dot-matrix pressure transducer was developed for the purpose of acquiring time-sampled pressure profiles during impact. The acquired data was transferred into a personal computer and accurate visualization of animated data were presented. Preliminary test with 10 apples has been performed. Measurement were made by the contact-pressure transducer in two different positions. Complementary measurements were made on the same apples by using the Firmalon and Magness Taylor (MT) testers. Three-layer neural network was designed. 2/3 of the contact-pressure data were used as training input data and corresponding MT data as training target data. The remaining data were used as NN checking data. Six samples randomly chosen from the ten measured samples and their corresponding Firmalon values were used as the NN training and target data, respectively. The remaining four samples' data were input to the NN. The NN results consistent with the Firmness Tester values. So, if more training data would be obtained, the output should be more accurate. In addition, the Firmness Tester values do not consistent with MT firmness tester values. The NN method developed in this study appears to be a useful tool to emulate the MT Firmness test results without destroying the apple samples. To get more accurate estimation of MT firmness a much larger training data set is required. When the larger sensitive area of the pressure sensor being developed in this project becomes available, the entire contact 'shape' will provide additional information and the neural network results would be more accurate. It has been shown that the impact information can be utilized in the determination of internal quality factors of fruit. Until now,
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Roberts, Tony, Judy Gitahi, Patrick Allam, Lawrence Oboh, Oyewole Oladapo, Gifty Appiah-Adjei, Amira Galal, et al. Mapping the Supply of Surveillance Technologies to Africa: Case Studies from Nigeria, Ghana, Morocco, Malawi, and Zambia. Institute of Development Studies, September 2023. http://dx.doi.org/10.19088/ids.2023.027.
Abstract:
African governments are spending over 1US$bn per year on digital surveillance technologies which are being used without adequate legal protections in ways that regularly violate citizens’ fundamental human rights. This report documents which companies, from which countries, are supplying which types of surveillance technology to African governments. Without this missing detail, it is impossible to adequately design measures to mitigate and overcome illegal surveillance and violations of human rights. Since the turn of the century, we have witnessed a digitalisation of surveillance that has enabled the algorithmic automation of surveillance at a scale not previously imaginable. Surveillance of citizens was once a labour and time-intensive process. This provided a practical limit to the scope and depth of state surveillance. The digitalisation of telephony has made it possible to automate the search for keywords across all mobile and internet communications. For the first time, state surveillance agencies can do two things: (a) conduct mass surveillance of all citizens’ communications, and (b) micro-target individuals for in-depth surveillance that draws together in real-time data from mobile calls, short message service (SMS), internet messaging, global positioning system (GPS) location, and financial transactions. This report was produced by qualitative analysis of open-source data in the public domain. The information presented is drawn from a diverse range of sources, including open government data sets, export licence portals, procurement notices, civil society databases of surveillance contracts, press releases from surveillance companies, academic articles, reports, and media coverage. The research is organised using a typology of five categories of surveillance technology. We did not set out to detail every technology available, every company, or every supply contract. Instead, we document the main companies and countries selling digital surveillance technologies to African governments. Rather than focus on the technical functionality distinguishing each product offering, we highlight five of the most important types of surveillance technology: internet interception, mobile interception, social media surveillance, ‘safe city’ technologies for the surveillance of public spaces, and biometric identification technologies.
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Greinert, Jens. Mine Monitoring in the German Baltic Sea 2020; Dumped munition monitoring AL548, 03rd – 16th November 2020, Kiel (Germany) – Kiel (Germany) „MineMoni-II 2020“. GEOMAR Helmholtz Centre for Ocean Research Kiel, 2021. http://dx.doi.org/10.3289/cr_al548.
Abstract:
ALKOR cruise AL548 took place as part of the EMFF (European Maritime and Fisheries Fund)-funded project BASTA (Boost Applied munition detection through Smart data inTegration and AI workflows; https://www.basta-munition.eu) and as continuation of the munition monitoring started within the BMBF-funded project UDEMM (Environmental Monitoring for the Delaboration of Munition in the Sea; https://udemm.geomar.de/). In October 2018, a first cruise (POS530 MineMoni2018) was conducted, to gather data for a broad baseline study in the German Baltic Sea. Results show a moderate contamination level on regional and coastal scale, but indicate higher levels for specific local areas. Within UDEMM, expertise was developed to detect, exactly locate and monitor munition (e.g. torpedoes, sea mines, ground mines) on the seafloor using optical and hydroacoustic means. In addition, chemical analyses of dissolved contaminants in the water and sediments was performed. Data acquired during this cruise are used in BASTA, which aims for enhanced munition detection via AUV-based artificial intelligence applied on multi-sensor datasets. At the same time, the project ExPloTect (Ex-situ, near-real-time exPlosive compound deTection in seawater) (also EMFF-funded) addresses the need for an innovative approach to detect explosive compounds in seawater. A prototype system was used and successfully tested for the first time during this cruise. The main focus was placed onto the two already known dumpsites Kolberger Heide and Lübeck Bight. Additionally, new areas Falshöft (Schleswig-Holstein) and Cadet Channel, Trollegrund and Großklützhöved (Mecklenburg-Vorpommern) were explored. In each area high-resolution multibeam mapping was performed and contact lists, indicating potential munition objects were produced on board. AUV surveys were conducted to ground-truth possible contacts via detailed photograph and magnetometer mapping. This was complemented with towed video (TV)-CTD profiles. The transits to and between those sites were planned along former constraint routes during WWII. These routes were main targets of the British Air Force and mines and bombs can be expected along these ways. During transits water samples were taken with on a CTD- (conductivity, temperature, depth) rosette-mounted Niskin bottles in regular distances, in order to obtain a comprehensive understanding munition compounds (inter alia trinitrotoluene (TNT)) measurements across the German Baltic Sea.