The Experts below are selected from a list of 1380 Experts worldwide ranked by ideXlab platform
Leander B. Hormann - One of the best experts on this subject based on the ideXlab platform.
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M&N - Estimation of the harvestable power on wireless sensor nodes
2015 IEEE International Workshop on Measurements & Networking (M&N), 2015Co-Authors: Leander B. Hormann, Achim Berger, Peter Priller, Albert Potsch, Andreas SpringerAbstract:Wireless sensor networks (WSNs) are typically used to measure physical quantities of their environment at locations characterized by poor accessibility and lacking of Wired Infrastructure. To extend the operational time, energy harvesting systems (EHSs) support the power supply by transforming environmental energy into electrical energy. In the best case, a self-sufficient supply of the sensor node is possible. Information about the harvestable energy is necessary to design WSNs and EHSs properly. However, detailed information is often not available and special equipment is necessary to measure it. Therefore, this paper presents a simple method to estimate and track the harvestable power. The results can be used offline for design and simulations of nodes or networks, or online for work-load-distribution or energy aware network routing.
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An efficient start-up circuitry for de-energized ultra-low power energy harvesting systems
Smart Sensors Actuators and MEMS VII; and Cyber Physical Systems, 2015Co-Authors: Leander B. Hormann, Achim Berger, Lukas Salzburger, Peter Priller, Andreas SpringerAbstract:Cyber-physical systems often include small wireless devices to measure physical quantities or control a technical process. These devices need a self-sufficient power supply because no Wired Infrastructure is available. Their operational time can be enhanced by energy harvesting systems. However, the convertible power is often limited and discontinuous which requires the need of an energy storage unit. If this unit (and thus the whole system) is de-energized, the start-up process may take a significant amount of time because of an inefficient energy harvesting process. Therefore, this paper presents a system which enables a safe and fast start-up from the de-energized state.
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Wireless Days - Integration of a wireless sensor network into a reliable data flow process for slope monitoring
2013 IFIP Wireless Days (WD), 2013Co-Authors: Christian Steger, Stephan Gether, Hannes Mock, Marcus Dietl, Leander B. HormannAbstract:Slope monitoring in inner-alpine regions is important for early warning systems to detect potential landslides. Such slopes are often located at areas without Wired Infrastructure. Thus, wireless sensor networks (WSNs) can be used as measurement and communication system. Each sensor node is equipped with a GPS receiver and is placed in the monitored slope. After transmitting the raw GPS data to the base station, (near) real-time positioning algorithms determine the movement of each sensor node. To achieve accuracy in centimeter range, these algorithms need a continuous data flow of the received GPS signals. This paper presents the integration of an energy harvesting WSN into a reliable data flow process to enable a continuous slope monitoring.
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Using a remote lab for teaching energy harvesting enhanced wireless sensor networks
IEEE Global Engineering Education Conference, EDUCON, 2013Co-Authors: Leander B. Hormann, Michael Steinberger, Michael Kalcher, Christian KreinerAbstract:Teaching wireless sensor networks (WSNs) only theoretically is not sufficient to understand the complex interaction of these networks. WSNs consist of sensor nodes which measure physical quantities of their environment, preprocess the measured data, and transmit it towards a base station in a multi-hop manner. WSNs are typically used in application areas without Wired Infrastructure and so they must be powered by batteries or energy harvesting systems. Due to the influence of different factors on the behavior, practical exercises can enhance the learning process because the students can perform their experimentation independently. This work presents the use of a remote lab for teaching energy harvesting enhanced WSNs. Students can learn the behavior of WSNs and the influences of energy harvesting. Furthermore, practical aspects of WSNs are shown by using a realistic application scenario. This work is part of the European project Remotelabs Access in Internet-based Performance-centered Learning Environment for Curriculum Support. © 2013 IEEE.
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PerCom Workshops - Towards an on-site characterization of energy harvesting devices for wireless sensor networks
2012 IEEE International Conference on Pervasive Computing and Communications Workshops, 2012Co-Authors: Leander B. Hormann, Michael Steinberger, Philipp M Glatz, Karima B. Hein, Christian Steger, Reinhold WeissAbstract:Wireless sensor networks (WSNs) suffer from the lack of Wired Infrastructure. Each node needs its own power supply, e.g. batteries or energy harvesting systems (EHSs). Typically, EHSs can extend the lifetime of a sensor node or even enable perpetual operation. Due to the high variation of harvestable energy of the environment, the design of the EHSs has to be done very carefully. The design process can be enhanced by using simulation of the WSN including energy harvesting. However, a realistic simulation needs accurate data of the harvestable energy of the environment. This paper presents the concept of an on-site characterization instrument for different types of energy harvesting devices. These instruments can be connected like a WSN.
Yelena Yesha - One of the best experts on this subject based on the ideXlab platform.
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Collaborative joins in a pervasive computing environment
The VLDB Journal, 2005Co-Authors: Filip Perich, Anupam Joshi, Yelena Yesha, Timothy W FininAbstract:We present a collaborative query processing protocol based on the principles of Contract Nets. The protocol is designed for pervasive computing environments where, in addition to operating on limited computing and battery resources, mobile devices cannot always rely on being able to access the Wired Infrastructure. Devices, therefore, need to collaborate with each other in order to obtain data otherwise inaccessible due to the nature of the environment. Furthermore, by intelligently using answers cached by peers, devices can reduce their computation cost. We show the effectiveness of our approach by evaluating performance of devices querying for data while moving in a citylike environment.
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Service composition for mobile environments
Mob. Netw. Appl., 2005Co-Authors: Dipanjan Chakraborty, Timothy W Finin, Anupam Joshi, Yelena YeshaAbstract:Service Composition, that is, the development of customized services by discovering, integrating and executing existing services has received a lot of attention in the last couple of years with respect to Wired-Infrastructure or Internet web services. With the advancement in the wireless technology and rapid deployment of mobile devices, we envision that in the near future wirelessly connected mobile devices in a given vicinity will also provide services that can be leveraged in the composition process. This is particularly true of what have been described as "pervasive computing" environments. However, Wired-Infrastructure based service composition architectures are not designed to consider the various factors like mobility, device heterogeneity, resource variability and reliability in a mobile environment. In this paper, we describe the issues related to service composition in mobile environments and evaluate criteria for judging protocols that enable such composition. We present a distributed architecture and associated protocols for service composition in mobile environments that take into consideration mobility, dynamic changing service topology and device resources. The composition protocols are based on distributed brokerage mechanisms and utilize a distributed service discovery process over ad-hoc network connectivity. We present simulation results of our protocols, and compare them with a centralized service composition protocol traditionally used for Wired-Infrastructure environments. The results show that our approach clearly outperforms the existing centralized approaches, and that our protocols are able to adapt and better utilize the changing service topology and resources in a mobile environment.
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DEXA - Neighborhood-Consistent Transaction Management for Pervasive Computing Environments
Lecture Notes in Computer Science, 2003Co-Authors: Filip Perich, Anupam Joshi, Yelena Yesha, Timothy W FininAbstract:This paper examines the problem of transaction management in pervasive computing environments and presents a new approach to address them. We represent each entity as a mobile or static semi-autonomous device. The purpose of each device is to satisfy user queries based on its local data repository and interactions with other devices currently in its vicinity. Pervasive environments, unlike traditional mobile computing paradigm, do not differentiate between clients and servers that are located in a fixed, Wired Infrastructure. Consequently, we model all devices as peers. These environments also relax other assumptions made by mobile computing paradigm, such as the possibility of reconnection with a given device, support from Wired Infrastructure, or the presence of a global schema. These fundamental characteristics of pervasive computing environments limit the use of techniques developed for transactions in a “mobile” computing environments. We define an alternative optimistic transaction model whose main emphasis is to provide a high rate of successful transaction terminations and to maintain a neighborhood-based consistency. The model accomplishes this via the help of active witnesses and by employing an epidemic voting protocol. The advantage of our model is that it enables two or more peers to engage in a reliable and consistent transaction while in a pervasive environment without assuming that they can talk to each other via Infrastructure such as base stations. The advantage of using active witnesses and an epidemic voting protocol is that transaction termination does not depend on any single point of a failure. Additionally, the use of an epidemic voting protocol does not require all involved entities to be simultaneously connected at any time and, therefore, further overcomes the dynamic nature of the environments. We present the implementation of the model and results from simulations.
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A reactive service composition architecture for pervasive computing environments
IFIP Advances in Information and Communication Technology, 2003Co-Authors: Dipanjan Chakraborty, Timothy W Finin, Filip Perich, Anupam Joshi, Yelena YeshaAbstract:Development of customized services by integrating and executing existing ones (refered to as service composition) has received a lot of attention in the last few years with respect to Wired, infrastrutcure based web-services. With the advancement in the wireless technology and pervasive computing, we envison that in the near future, we will have such information or services embedded in various wireless devices in our vicinity. However, Wired Infrastructure-based service discovery and composition architectures do not take into consideration factors arising from the possible mobility of the service providers. In this paper, we present Anamika: a distributed, de-centralized and fault-tolerant design architecture for reactive service composition in pervasive environments.
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Neighborhood-consistent transaction management for pervasive computing environments
Lecture Notes in Computer Science, 2003Co-Authors: Filip Perich, Anupam Joshi, Yelena Yesha, Timothy W FininAbstract:This paper examines the problem of transaction management in pervasive computing environments and presents a new approach to address them. We represent each entity as a mobile or static semi-autonomous device. The purpose of each device is to satisfy user queries based on its local data repository and interactions with other devices currently in its vicinity. Pervasive environments, unlike traditional mobile computing paradigm, do not differentiate between clients and servers that are located in a fixed, Wired Infrastructure. Consequently, we model all devices as peers. These environments also relax other assumptions made by mobile computing paradigm, such as the possibility of reconnection with a given device, support from Wired Infrastructure, or the presence of a global schema. These fundamental characteristics of pervasive computing environments limit the use of techniques developed for transactions in a mobile computing environments. We define an alternative optimistic transaction model whose main emphasis is to provide a high rate of successful transaction terminations and to maintain a neighborhood-based consistency. The model accomplishes this via the help of active witnesses and by employing an epidemic voting protocol. The advantage of our model is that it enables two or more peers to engage in a reliable and consistent transaction while in a pervasive environment without assuming that they can talk to each other via Infrastructure such as base stations. The advantage of using active witnesses and an epidemic voting protocol is that transaction termination does not depend on any single point of a failure. Additionally, the use of an epidemic voting protocol does not require all involved entities to be simultaneously connected at any time and, therefore, further overcomes the dynamic nature of the environments. We present the implementation of the model and results from simulations.
Timothy W Finin - One of the best experts on this subject based on the ideXlab platform.
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Collaborative joins in a pervasive computing environment
The VLDB Journal, 2005Co-Authors: Filip Perich, Anupam Joshi, Yelena Yesha, Timothy W FininAbstract:We present a collaborative query processing protocol based on the principles of Contract Nets. The protocol is designed for pervasive computing environments where, in addition to operating on limited computing and battery resources, mobile devices cannot always rely on being able to access the Wired Infrastructure. Devices, therefore, need to collaborate with each other in order to obtain data otherwise inaccessible due to the nature of the environment. Furthermore, by intelligently using answers cached by peers, devices can reduce their computation cost. We show the effectiveness of our approach by evaluating performance of devices querying for data while moving in a citylike environment.
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Service composition for mobile environments
Mob. Netw. Appl., 2005Co-Authors: Dipanjan Chakraborty, Timothy W Finin, Anupam Joshi, Yelena YeshaAbstract:Service Composition, that is, the development of customized services by discovering, integrating and executing existing services has received a lot of attention in the last couple of years with respect to Wired-Infrastructure or Internet web services. With the advancement in the wireless technology and rapid deployment of mobile devices, we envision that in the near future wirelessly connected mobile devices in a given vicinity will also provide services that can be leveraged in the composition process. This is particularly true of what have been described as "pervasive computing" environments. However, Wired-Infrastructure based service composition architectures are not designed to consider the various factors like mobility, device heterogeneity, resource variability and reliability in a mobile environment. In this paper, we describe the issues related to service composition in mobile environments and evaluate criteria for judging protocols that enable such composition. We present a distributed architecture and associated protocols for service composition in mobile environments that take into consideration mobility, dynamic changing service topology and device resources. The composition protocols are based on distributed brokerage mechanisms and utilize a distributed service discovery process over ad-hoc network connectivity. We present simulation results of our protocols, and compare them with a centralized service composition protocol traditionally used for Wired-Infrastructure environments. The results show that our approach clearly outperforms the existing centralized approaches, and that our protocols are able to adapt and better utilize the changing service topology and resources in a mobile environment.
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DEXA - Neighborhood-Consistent Transaction Management for Pervasive Computing Environments
Lecture Notes in Computer Science, 2003Co-Authors: Filip Perich, Anupam Joshi, Yelena Yesha, Timothy W FininAbstract:This paper examines the problem of transaction management in pervasive computing environments and presents a new approach to address them. We represent each entity as a mobile or static semi-autonomous device. The purpose of each device is to satisfy user queries based on its local data repository and interactions with other devices currently in its vicinity. Pervasive environments, unlike traditional mobile computing paradigm, do not differentiate between clients and servers that are located in a fixed, Wired Infrastructure. Consequently, we model all devices as peers. These environments also relax other assumptions made by mobile computing paradigm, such as the possibility of reconnection with a given device, support from Wired Infrastructure, or the presence of a global schema. These fundamental characteristics of pervasive computing environments limit the use of techniques developed for transactions in a “mobile” computing environments. We define an alternative optimistic transaction model whose main emphasis is to provide a high rate of successful transaction terminations and to maintain a neighborhood-based consistency. The model accomplishes this via the help of active witnesses and by employing an epidemic voting protocol. The advantage of our model is that it enables two or more peers to engage in a reliable and consistent transaction while in a pervasive environment without assuming that they can talk to each other via Infrastructure such as base stations. The advantage of using active witnesses and an epidemic voting protocol is that transaction termination does not depend on any single point of a failure. Additionally, the use of an epidemic voting protocol does not require all involved entities to be simultaneously connected at any time and, therefore, further overcomes the dynamic nature of the environments. We present the implementation of the model and results from simulations.
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A reactive service composition architecture for pervasive computing environments
IFIP Advances in Information and Communication Technology, 2003Co-Authors: Dipanjan Chakraborty, Timothy W Finin, Filip Perich, Anupam Joshi, Yelena YeshaAbstract:Development of customized services by integrating and executing existing ones (refered to as service composition) has received a lot of attention in the last few years with respect to Wired, infrastrutcure based web-services. With the advancement in the wireless technology and pervasive computing, we envison that in the near future, we will have such information or services embedded in various wireless devices in our vicinity. However, Wired Infrastructure-based service discovery and composition architectures do not take into consideration factors arising from the possible mobility of the service providers. In this paper, we present Anamika: a distributed, de-centralized and fault-tolerant design architecture for reactive service composition in pervasive environments.
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Neighborhood-consistent transaction management for pervasive computing environments
Lecture Notes in Computer Science, 2003Co-Authors: Filip Perich, Anupam Joshi, Yelena Yesha, Timothy W FininAbstract:This paper examines the problem of transaction management in pervasive computing environments and presents a new approach to address them. We represent each entity as a mobile or static semi-autonomous device. The purpose of each device is to satisfy user queries based on its local data repository and interactions with other devices currently in its vicinity. Pervasive environments, unlike traditional mobile computing paradigm, do not differentiate between clients and servers that are located in a fixed, Wired Infrastructure. Consequently, we model all devices as peers. These environments also relax other assumptions made by mobile computing paradigm, such as the possibility of reconnection with a given device, support from Wired Infrastructure, or the presence of a global schema. These fundamental characteristics of pervasive computing environments limit the use of techniques developed for transactions in a mobile computing environments. We define an alternative optimistic transaction model whose main emphasis is to provide a high rate of successful transaction terminations and to maintain a neighborhood-based consistency. The model accomplishes this via the help of active witnesses and by employing an epidemic voting protocol. The advantage of our model is that it enables two or more peers to engage in a reliable and consistent transaction while in a pervasive environment without assuming that they can talk to each other via Infrastructure such as base stations. The advantage of using active witnesses and an epidemic voting protocol is that transaction termination does not depend on any single point of a failure. Additionally, the use of an epidemic voting protocol does not require all involved entities to be simultaneously connected at any time and, therefore, further overcomes the dynamic nature of the environments. We present the implementation of the model and results from simulations.
Christian Kreiner - One of the best experts on this subject based on the ideXlab platform.
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Using a remote lab for teaching energy harvesting enhanced wireless sensor networks
IEEE Global Engineering Education Conference, EDUCON, 2013Co-Authors: Leander B. Hormann, Michael Steinberger, Michael Kalcher, Christian KreinerAbstract:Teaching wireless sensor networks (WSNs) only theoretically is not sufficient to understand the complex interaction of these networks. WSNs consist of sensor nodes which measure physical quantities of their environment, preprocess the measured data, and transmit it towards a base station in a multi-hop manner. WSNs are typically used in application areas without Wired Infrastructure and so they must be powered by batteries or energy harvesting systems. Due to the influence of different factors on the behavior, practical exercises can enhance the learning process because the students can perform their experimentation independently. This work presents the use of a remote lab for teaching energy harvesting enhanced WSNs. Students can learn the behavior of WSNs and the influences of energy harvesting. Furthermore, practical aspects of WSNs are shown by using a realistic application scenario. This work is part of the European project Remotelabs Access in Internet-based Performance-centered Learning Environment for Curriculum Support. © 2013 IEEE.
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Educational remote lab concept for energy harvesting enhanced wireless sensor networks
EDERC 2012 - Proceedings of the 5th European DSP in Education and Research Conference, 2012Co-Authors: Leander B. Hormann, Michael Steinberger, Michael Kalcher, Christian KreinerAbstract:Wireless sensor networks (WSNs) are typically used in application areas without Wired Infrastructure. WSNs must be energy efficient, because they are powered by batteries or energy harvesting systems. Teaching of practical aspects of energy harvesting enhanced WSNs can be improved by integration of performance-centered tasks. This work presents an educational remote lab concept for energy harvesting enhanced WSNs. Students can learn how WSNs work and how energy harvesting influences their behavior. It is part of the European project Remote-labs Access in Internet-based Performance-centered Learning Environment for Curriculum Support.
Anupam Joshi - One of the best experts on this subject based on the ideXlab platform.
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Collaborative joins in a pervasive computing environment
The VLDB Journal, 2005Co-Authors: Filip Perich, Anupam Joshi, Yelena Yesha, Timothy W FininAbstract:We present a collaborative query processing protocol based on the principles of Contract Nets. The protocol is designed for pervasive computing environments where, in addition to operating on limited computing and battery resources, mobile devices cannot always rely on being able to access the Wired Infrastructure. Devices, therefore, need to collaborate with each other in order to obtain data otherwise inaccessible due to the nature of the environment. Furthermore, by intelligently using answers cached by peers, devices can reduce their computation cost. We show the effectiveness of our approach by evaluating performance of devices querying for data while moving in a citylike environment.
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Service composition for mobile environments
Mob. Netw. Appl., 2005Co-Authors: Dipanjan Chakraborty, Timothy W Finin, Anupam Joshi, Yelena YeshaAbstract:Service Composition, that is, the development of customized services by discovering, integrating and executing existing services has received a lot of attention in the last couple of years with respect to Wired-Infrastructure or Internet web services. With the advancement in the wireless technology and rapid deployment of mobile devices, we envision that in the near future wirelessly connected mobile devices in a given vicinity will also provide services that can be leveraged in the composition process. This is particularly true of what have been described as "pervasive computing" environments. However, Wired-Infrastructure based service composition architectures are not designed to consider the various factors like mobility, device heterogeneity, resource variability and reliability in a mobile environment. In this paper, we describe the issues related to service composition in mobile environments and evaluate criteria for judging protocols that enable such composition. We present a distributed architecture and associated protocols for service composition in mobile environments that take into consideration mobility, dynamic changing service topology and device resources. The composition protocols are based on distributed brokerage mechanisms and utilize a distributed service discovery process over ad-hoc network connectivity. We present simulation results of our protocols, and compare them with a centralized service composition protocol traditionally used for Wired-Infrastructure environments. The results show that our approach clearly outperforms the existing centralized approaches, and that our protocols are able to adapt and better utilize the changing service topology and resources in a mobile environment.
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DEXA - Neighborhood-Consistent Transaction Management for Pervasive Computing Environments
Lecture Notes in Computer Science, 2003Co-Authors: Filip Perich, Anupam Joshi, Yelena Yesha, Timothy W FininAbstract:This paper examines the problem of transaction management in pervasive computing environments and presents a new approach to address them. We represent each entity as a mobile or static semi-autonomous device. The purpose of each device is to satisfy user queries based on its local data repository and interactions with other devices currently in its vicinity. Pervasive environments, unlike traditional mobile computing paradigm, do not differentiate between clients and servers that are located in a fixed, Wired Infrastructure. Consequently, we model all devices as peers. These environments also relax other assumptions made by mobile computing paradigm, such as the possibility of reconnection with a given device, support from Wired Infrastructure, or the presence of a global schema. These fundamental characteristics of pervasive computing environments limit the use of techniques developed for transactions in a “mobile” computing environments. We define an alternative optimistic transaction model whose main emphasis is to provide a high rate of successful transaction terminations and to maintain a neighborhood-based consistency. The model accomplishes this via the help of active witnesses and by employing an epidemic voting protocol. The advantage of our model is that it enables two or more peers to engage in a reliable and consistent transaction while in a pervasive environment without assuming that they can talk to each other via Infrastructure such as base stations. The advantage of using active witnesses and an epidemic voting protocol is that transaction termination does not depend on any single point of a failure. Additionally, the use of an epidemic voting protocol does not require all involved entities to be simultaneously connected at any time and, therefore, further overcomes the dynamic nature of the environments. We present the implementation of the model and results from simulations.
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A reactive service composition architecture for pervasive computing environments
IFIP Advances in Information and Communication Technology, 2003Co-Authors: Dipanjan Chakraborty, Timothy W Finin, Filip Perich, Anupam Joshi, Yelena YeshaAbstract:Development of customized services by integrating and executing existing ones (refered to as service composition) has received a lot of attention in the last few years with respect to Wired, infrastrutcure based web-services. With the advancement in the wireless technology and pervasive computing, we envison that in the near future, we will have such information or services embedded in various wireless devices in our vicinity. However, Wired Infrastructure-based service discovery and composition architectures do not take into consideration factors arising from the possible mobility of the service providers. In this paper, we present Anamika: a distributed, de-centralized and fault-tolerant design architecture for reactive service composition in pervasive environments.
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Neighborhood-consistent transaction management for pervasive computing environments
Lecture Notes in Computer Science, 2003Co-Authors: Filip Perich, Anupam Joshi, Yelena Yesha, Timothy W FininAbstract:This paper examines the problem of transaction management in pervasive computing environments and presents a new approach to address them. We represent each entity as a mobile or static semi-autonomous device. The purpose of each device is to satisfy user queries based on its local data repository and interactions with other devices currently in its vicinity. Pervasive environments, unlike traditional mobile computing paradigm, do not differentiate between clients and servers that are located in a fixed, Wired Infrastructure. Consequently, we model all devices as peers. These environments also relax other assumptions made by mobile computing paradigm, such as the possibility of reconnection with a given device, support from Wired Infrastructure, or the presence of a global schema. These fundamental characteristics of pervasive computing environments limit the use of techniques developed for transactions in a mobile computing environments. We define an alternative optimistic transaction model whose main emphasis is to provide a high rate of successful transaction terminations and to maintain a neighborhood-based consistency. The model accomplishes this via the help of active witnesses and by employing an epidemic voting protocol. The advantage of our model is that it enables two or more peers to engage in a reliable and consistent transaction while in a pervasive environment without assuming that they can talk to each other via Infrastructure such as base stations. The advantage of using active witnesses and an epidemic voting protocol is that transaction termination does not depend on any single point of a failure. Additionally, the use of an epidemic voting protocol does not require all involved entities to be simultaneously connected at any time and, therefore, further overcomes the dynamic nature of the environments. We present the implementation of the model and results from simulations.
