14,142 research outputs found

    Mean-Field-Type Games in Engineering

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    A mean-field-type game is a game in which the instantaneous payoffs and/or the state dynamics functions involve not only the state and the action profile but also the joint distributions of state-action pairs. This article presents some engineering applications of mean-field-type games including road traffic networks, multi-level building evacuation, millimeter wave wireless communications, distributed power networks, virus spread over networks, virtual machine resource management in cloud networks, synchronization of oscillators, energy-efficient buildings, online meeting and mobile crowdsensing.Comment: 84 pages, 24 figures, 183 references. to appear in AIMS 201

    Split and Migrate: Resource-Driven Placement and Discovery of Microservices at the Edge

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    Microservices architectures combine the use of fine-grained and independently-scalable services with lightweight communication protocols, such as REST calls over HTTP. Microservices bring flexibility to the development and deployment of application back-ends in the cloud. Applications such as collaborative editing tools require frequent interactions between the front-end running on users\u27 machines and a back-end formed of multiple microservices. User-perceived latencies depend on their connection to microservices, but also on the interaction patterns between these services and their databases. Placing services at the edge of the network, closer to the users, is necessary to reduce user-perceived latencies. It is however difficult to decide on the placement of complete stateful microservices at one specific core or edge location without trading between a latency reduction for some users and a latency increase for the others. We present how to dynamically deploy microservices on a combination of core and edge resources to systematically reduce user-perceived latencies. Our approach enables the split of stateful microservices, and the placement of the resulting splits on appropriate core and edge sites. Koala, a decentralized and resource-driven service discovery middleware, enables REST calls to reach and use the appropriate split, with only minimal changes to a legacy microservices application. Locality awareness using network coordinates further enables to automatically migrate services split and follow the location of the users. We confirm the effectiveness of our approach with a full prototype and an application to ShareLatex, a microservices-based collaborative editing application

    GUARDIANS final report

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    Emergencies in industrial warehouses are a major concern for firefghters. The large dimensions together with the development of dense smoke that drastically reduces visibility, represent major challenges. The Guardians robot swarm is designed to assist fire fighters in searching a large warehouse. In this report we discuss the technology developed for a swarm of robots searching and assisting fire fighters. We explain the swarming algorithms which provide the functionality by which the robots react to and follow humans while no communication is required. Next we discuss the wireless communication system, which is a so-called mobile ad-hoc network. The communication network provides also one of the means to locate the robots and humans. Thus the robot swarm is able to locate itself and provide guidance information to the humans. Together with the re ghters we explored how the robot swarm should feed information back to the human fire fighter. We have designed and experimented with interfaces for presenting swarm based information to human beings

    Robotic Wireless Sensor Networks

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    In this chapter, we present a literature survey of an emerging, cutting-edge, and multi-disciplinary field of research at the intersection of Robotics and Wireless Sensor Networks (WSN) which we refer to as Robotic Wireless Sensor Networks (RWSN). We define a RWSN as an autonomous networked multi-robot system that aims to achieve certain sensing goals while meeting and maintaining certain communication performance requirements, through cooperative control, learning and adaptation. While both of the component areas, i.e., Robotics and WSN, are very well-known and well-explored, there exist a whole set of new opportunities and research directions at the intersection of these two fields which are relatively or even completely unexplored. One such example would be the use of a set of robotic routers to set up a temporary communication path between a sender and a receiver that uses the controlled mobility to the advantage of packet routing. We find that there exist only a limited number of articles to be directly categorized as RWSN related works whereas there exist a range of articles in the robotics and the WSN literature that are also relevant to this new field of research. To connect the dots, we first identify the core problems and research trends related to RWSN such as connectivity, localization, routing, and robust flow of information. Next, we classify the existing research on RWSN as well as the relevant state-of-the-arts from robotics and WSN community according to the problems and trends identified in the first step. Lastly, we analyze what is missing in the existing literature, and identify topics that require more research attention in the future

    Essays on the nature and dynamics of higher-order organizational capabilities

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    Today’s business environments have become fast-moving, involving frequent, rapid and unpredictable change. As such, firms are struggling to (find new ways to) create and sustain competitive advantage. Scholars in organization science, and strategic management in particular, have shifted focus towards competing on higher-order (i.e. meta-)organizational capabilities in fast-moving business environments; organizational capabilities that may define a firm strategically as being key drivers of long-term business performance. However, the main question that needs to be answered refers to what the key dimensions of such higher-order organizational capabilities in dynamic business environments are. This doctoral dissertation therefore examines the following central research question: What are the key dimensions of higher-order organizational capabilities in addressing situations of changing market and competitive conditions? This dissertation builds upon the notions of dynamic capability and ambidexterity. The notion of dynamic capability explains how organizations may develop competitive advantage in fast-moving business environments, by focusing on the dynamic processes of assembling, deploying and integrating a firm’s resource base. Dynamic capabilities stress the importance of the history of a firm’s current capabilities, and the importance of revising and reconfiguring these in the future. As such, firms are able to address changing environments and/or create market change. However, in situations of changing market and competitive conditions, firms need to demonstrate the ability to timely response to new circumstances, along with the ability to address existing environments. In this respect, scholars introduced the notion of ambidexterity, which refers to performing different and often competing challenges. Here, competitive advantage may result from being efficient in managing today’s business demands, while at the same time being effective in adapting to changing business environments and/or in creating market change. As such, firms need a focus on both exploitation and exploration; that is, on their current activities in existing domains along with developing new activities in non-existing domains. The current literature comprises a variety of conceptualizations and interpretations of dynamic capability and ambidexterity, providing a significant challenge for both scholars and practitioners to understand and develop these meta-organizational capabilities. In order to assess the collective understanding of both concepts, Chapter 2 introduces a systematic literature review approach. Such an approach involves a comprehensive search of all potentially relevant papers and books of dynamic capability and ambidexterity, and the use of explicit, reproducible criteria in the selection of papers and books for review. Drawing on systematic literature reviews, the foundations, antecedents and consequences of dynamic capability and ambidexterity are explored in terms of definitions, operationalizations and measurements of their key dimensions. As a result, a (re-)definition of dynamic capability and ambidexterity is proposed. These definitions point at ways in which dynamic capability and ambidexterity can be operationalized and measured more effectively in future research. As such, Chapter 2 develops a definition and operationalization of dynamic capability and ambidexterity in terms of their key dimensions. Chapter 2 therefore contributes to the development of a theoretical understanding of the key dimensions of dynamic capability and ambidexterity, providing a starting point for future theoretical and empirical studies that advance our collective understanding of dynamic capability and ambidexterity. The insights from the systematic literature reviews provide a theoretical basis for the empirical studies in this dissertation. The empirical studies in Chapter 3 and 4 extend our empirical understanding of the dynamics entailed in the way ambidexterity is performed in service firms. Empirically studying ambidexterity in the service industries contributes to previous studies that have mainly been conducted in manufacturing firms, whereas relatively less attention has been paid to the challenges of exploitation versus exploration in service firms. Moreover, ambidexterity is particularly challenging for service firms, because new service development requires integrating the needs of new service operations and processes with existing business activities. As such, this dissertation extends and builds (new) theory in the field of dynamic capability, and ambidexterity in particular, which lead to main findings and implications that are of general scientific value for scholars and provide valuable insights for practitioners (in service firms). The empirical study in Chapter 3 studies ambidexterity from an organization design perspective by examining the relationship between decentralization and ambidexterity. As such, this study provides an in-depth understanding of the impact of decentralization on the dynamics entailed in the way ambidexterity is organized, balanced and connected in large service firms, incorporating the role of timing and interdependencies. Recently, scholars have suggested that a decentralized structure facilitates ambidexterity. However, comparative case studies of two service innovations in a large decentralized retail bank in the Netherlands paint a more complex picture. First, a literature review implies that decentralization may activate highly different generative mechanisms. Subsequently, the case study findings show that the activation of these generative mechanisms depends on the actual use of the decentralized structure. Moreover, these generative mechanisms and their outcomes gain and lose dominance in different phases of the innovation process. In particular, the effectiveness of the decentralized structure depend on the interdependence of exploitation and exploration activities. A decentralized structure appears to be of limited help for ambidexterity if exploration involves complex service innovation that needs to be integrated into the exploitative core of the organization. In other words, a decentralized structure does not support ambidexterity when exploitation and exploration activities are strongly interdependent. Overall, the main contribution of chapter 3 is to elaborate and extend existing theory. In this respect, Chapter 3 contributes to the literature by combining the literature on ambidexterity, organizational design and service innovation. The empirical study in Chapter 4 studies ambidexterity from a managerial perspective by examining the relationship between an organization’s founding conditions and the degree of ambidexterity in organizational practices in small-to-medium sized service firms. As such, this study extends our understanding of the dynamics entailed in the way competing priorities are performed, especially when these priorities demand both continuity and renewal. More specifically, this study explores the way founding conditions impact organizational practices, and in particular the capability to change these practices. The findings of comparative case studies of two practices in three management consulting SME’s in the USA, the Netherlands and the UK reveal how founding conditions affect the way competing demands of continuity and renewal are addressed. The case study findings primarily suggest the importance of founders’ blueprints, embedded in their employment models. These blueprints are difficult to alter, and as such mark the firm’s future path by impacting the level of ambidexterity in practices over an extended period of time. Overall, the main contribution of Chapter 4 is to build new theory. In this respect, Chapter 4 contributes to the literature by combining the literature on ambidexterity, founding conditions and practice-based research. Finally, Chapter 5 summarizes the main findings and (practical) implications of the studies described in previous chapters of this dissertation. Subsequently, a general conclusion regarding the central research question is given. In this respect, by drawing on the systematic literature reviews and empirical studies, this chapter describes a taxonomy of key dimensions of ambidexterity as a higher-order organizational capability. As such, this taxonomy integrates the previous chapters, and serves to answer the central research question in this dissertation. Finally, this chapter describes the main limitations of this dissertation and makes suggestions for future research

    Federated Learning for Iot/Edge/Fog Computing Systems

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    With the help of a new architecture called Edge/Fog (E/F) computing, cloud computing services can now be extended nearer to data generator devices. E/F computing in combination with Deep Learning (DL) is a promisedtechnique that is vastly applied in numerous fields. To train their models, data producers in conventional DL architectures with E/F computing enable them to repeatedly transmit and communicate data with third-party servers, like Edge/Fog or cloud servers. Due to the extensive bandwidth needs, legal issues, and privacy risks, this architecture is frequently impractical. Through a centralized server, the models can be co-trained by FL through distributed clients, including cars, hospitals, and mobile phones, while preserving data localization. As it facilitates group learning and model optimization, FL can therefore be seen as a motivating element in the E/F computing paradigm. Although FL applications in E/F computing environments have been considered in previous studies, FL execution and hurdles in the E/F computing framework have not been thoroughly covered. In order to identify advanced solutions, this chapter will provide a review of the application of FL in E/F computing systems. We think that by doing this chapter, researchers will learn more about how E/F computing and FL enable related concepts and technologies. Some case studies about the implementation of federated learning in E/F computing are being investigated. The open issues and future research directions are introduced.Comment: 21 pages, 4 figures, Book chapte
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