The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Marzia Rovere - One of the best experts on this subject based on the ideXlab platform.
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Layer Analysis of the structure of water confined in vycor glass
Journal of Chemical Physics, 2020Co-Authors: Paola Gallo, M. A. Ricci, Marzia RovereAbstract:A molecular dynamics simulation of the microscopic structure of water confined in a silica pore is presented. A single cavity in the silica glass has been modeled as to reproduce the main features of the pores of real Vycor glass. A Layer Analysis of the site–site radial distribution functions evidences the presence in the pore of two subsets of water molecules with different microscopic structure. Molecules which reside in the inner Layer, close to the center of the pore, have the same structure as bulk water but at a temperature of 30 K higher. On the contrary the structure of the water molecules in the outer Layer, close to the substrate, is strongly influenced by the water–substrate hydrophilic interaction and sensible distortions of the H-bond network and of the orientational correlations between neighboring molecules show up. Lowering the hydration has little effect on the structure of water in the outer Layer. The consequences on experimental determinations of the structural properties of water in confinement are discussed.A molecular dynamics simulation of the microscopic structure of water confined in a silica pore is presented. A single cavity in the silica glass has been modeled as to reproduce the main features of the pores of real Vycor glass. A Layer Analysis of the site–site radial distribution functions evidences the presence in the pore of two subsets of water molecules with different microscopic structure. Molecules which reside in the inner Layer, close to the center of the pore, have the same structure as bulk water but at a temperature of 30 K higher. On the contrary the structure of the water molecules in the outer Layer, close to the substrate, is strongly influenced by the water–substrate hydrophilic interaction and sensible distortions of the H-bond network and of the orientational correlations between neighboring molecules show up. Lowering the hydration has little effect on the structure of water in the outer Layer. The consequences on experimental determinations of the structural properties of water in ...
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Layer Analysis of the structure of water confined in vycor glass
Journal of Chemical Physics, 2002Co-Authors: Paola Gallo, M. A. Ricci, Marzia RovereAbstract:A Molecular Dynamics simulation of the microscopic structure of water confined in a silica pore is presented. A single cavity in the silica glass has been modeled as to reproduce the main features of the pores of real Vycor glass. A Layer Analysis of the site-site radial distribution functions evidence the presence in the pore of two subsets of water molecules with different microscopic structure. Molecules which reside in the inner Layer, close to the center of the pore, have the same structure as bulk water but at a temperature of 30 K higher. On the contrary the structure of the water molecules in the outer Layer, close to the substrate, is strongly influenced by the water-substrate hydrophilic interaction and sensible distortions of the H-bond network and of the orientational correlations between neighboring molecules show up. Lowering the hydration has little effect on the structure of water in the outer Layer. The consequences on experimental determinations of the structural properties of water in confinement are discussed.
Steve Goddard - One of the best experts on this subject based on the ideXlab platform.
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Cross-Layer Analysis of the End-to-End Delay Distribution in Wireless Sensor Networks
IEEE ACM Transactions on Networking, 2012Co-Authors: Yunbo Wang, Mehmet C. Vuran, Steve GoddardAbstract:Emerging applications of wireless sensor networks (WSNs) require real-time quality-of-service (QoS) guarantees to be provided by the network. Due to the nondeterministic impacts of the wireless channel and queuing mechanisms, probabilistic Analysis of QoS is essential. One important metric of QoS in WSNs is the probability distribution of the end-to-end delay. Compared to other widely used delay performance metrics such as the mean delay, delay variance, and worst-case delay, the delay distribution can be used to obtain the probability to meet a specific deadline for QoS-based communication in WSNs. To investigate the end-to-end delay distribution, in this paper, a comprehensive cross-Layer Analysis framework, which employs a stochastic queueing model in realistic channel environments, is developed. This framework is generic and can be parameterized for a wide variety of MAC protocols and routing protocols. Case studies with the CSMA/CA MAC protocol and an anycast protocol are conducted to illustrate how the developed framework can analytically predict the distribution of the end-to-end delay. Extensive test-bed experiments and simulations are performed to validate the accuracy of the framework for both deterministic and random deployments. Moreover, the effects of various network parameters on the distribution of end-to-end delay are investigated through the developed framework. To the best of our knowledge, this is the first work that provides a generic, probabilistic cross-Layer Analysis of end-to-end delay in WSNs.
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Cross-Layer Analysis of the End-to-End Delay Distribution in Wireless Sensor Networks
2009 30th IEEE Real-Time Systems Symposium, 2009Co-Authors: Yunbo Wang, Mehmet C. Vuran, Steve GoddardAbstract:Emerging applications of wireless sensor networks (WSNs) require real-time quality of service (QoS) guarantees to be provided by the network. However, designing real-time scheduling and communication solutions for these networks is challenging since the characteristics of QoS metrics in WSNs are not well known yet. Due to the nature of wireless connectivity, it is infeasible to satisfy worst-case QoS requirements in WSNs. Instead, probabilistic QoS guarantees should be provided, which requires the definition of probabilistic QoS metrics. To provide an analytical tool for the development of real-time solutions, in this paper, the distribution of end-to-end delay in multi-hop WSNs is investigated. Accordingly, a comprehensive and accurate cross-Layer Analysis framework, which employs a stochastic queueing model in realistic channel environments, is developed. This framework captures the heterogeneity in WSNs in terms of channel quality, transmit power, queue length, and communication protocols. A case study with the TinyOS CSMA/CA MAC protocol is conducted to show how the developed framework can analytically predict the distribution of end-to-end delay. Testbed experiments are provided to validate the developed model. The cross-Layer framework can be used to identify the relationships between network parameters and the distribution of end-to-end delay and accordingly, to design real-time solutions for WSNs. Our ongoing work suggests that this framework can be easily extended to model additional QoS metrics such as energy consumption distribution. To the best of our knowledge, this is the first work to investigate probabilistic QoS guarantees in WSNs.
Paola Gallo - One of the best experts on this subject based on the ideXlab platform.
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Layer Analysis of the structure of water confined in vycor glass
Journal of Chemical Physics, 2020Co-Authors: Paola Gallo, M. A. Ricci, Marzia RovereAbstract:A molecular dynamics simulation of the microscopic structure of water confined in a silica pore is presented. A single cavity in the silica glass has been modeled as to reproduce the main features of the pores of real Vycor glass. A Layer Analysis of the site–site radial distribution functions evidences the presence in the pore of two subsets of water molecules with different microscopic structure. Molecules which reside in the inner Layer, close to the center of the pore, have the same structure as bulk water but at a temperature of 30 K higher. On the contrary the structure of the water molecules in the outer Layer, close to the substrate, is strongly influenced by the water–substrate hydrophilic interaction and sensible distortions of the H-bond network and of the orientational correlations between neighboring molecules show up. Lowering the hydration has little effect on the structure of water in the outer Layer. The consequences on experimental determinations of the structural properties of water in confinement are discussed.A molecular dynamics simulation of the microscopic structure of water confined in a silica pore is presented. A single cavity in the silica glass has been modeled as to reproduce the main features of the pores of real Vycor glass. A Layer Analysis of the site–site radial distribution functions evidences the presence in the pore of two subsets of water molecules with different microscopic structure. Molecules which reside in the inner Layer, close to the center of the pore, have the same structure as bulk water but at a temperature of 30 K higher. On the contrary the structure of the water molecules in the outer Layer, close to the substrate, is strongly influenced by the water–substrate hydrophilic interaction and sensible distortions of the H-bond network and of the orientational correlations between neighboring molecules show up. Lowering the hydration has little effect on the structure of water in the outer Layer. The consequences on experimental determinations of the structural properties of water in ...
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Layer Analysis of the structure of water confined in vycor glass
Journal of Chemical Physics, 2002Co-Authors: Paola Gallo, M. A. Ricci, Marzia RovereAbstract:A Molecular Dynamics simulation of the microscopic structure of water confined in a silica pore is presented. A single cavity in the silica glass has been modeled as to reproduce the main features of the pores of real Vycor glass. A Layer Analysis of the site-site radial distribution functions evidence the presence in the pore of two subsets of water molecules with different microscopic structure. Molecules which reside in the inner Layer, close to the center of the pore, have the same structure as bulk water but at a temperature of 30 K higher. On the contrary the structure of the water molecules in the outer Layer, close to the substrate, is strongly influenced by the water-substrate hydrophilic interaction and sensible distortions of the H-bond network and of the orientational correlations between neighboring molecules show up. Lowering the hydration has little effect on the structure of water in the outer Layer. The consequences on experimental determinations of the structural properties of water in confinement are discussed.
Yunbo Wang - One of the best experts on this subject based on the ideXlab platform.
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Cross-Layer Analysis of the End-to-End Delay Distribution in Wireless Sensor Networks
IEEE ACM Transactions on Networking, 2012Co-Authors: Yunbo Wang, Mehmet C. Vuran, Steve GoddardAbstract:Emerging applications of wireless sensor networks (WSNs) require real-time quality-of-service (QoS) guarantees to be provided by the network. Due to the nondeterministic impacts of the wireless channel and queuing mechanisms, probabilistic Analysis of QoS is essential. One important metric of QoS in WSNs is the probability distribution of the end-to-end delay. Compared to other widely used delay performance metrics such as the mean delay, delay variance, and worst-case delay, the delay distribution can be used to obtain the probability to meet a specific deadline for QoS-based communication in WSNs. To investigate the end-to-end delay distribution, in this paper, a comprehensive cross-Layer Analysis framework, which employs a stochastic queueing model in realistic channel environments, is developed. This framework is generic and can be parameterized for a wide variety of MAC protocols and routing protocols. Case studies with the CSMA/CA MAC protocol and an anycast protocol are conducted to illustrate how the developed framework can analytically predict the distribution of the end-to-end delay. Extensive test-bed experiments and simulations are performed to validate the accuracy of the framework for both deterministic and random deployments. Moreover, the effects of various network parameters on the distribution of end-to-end delay are investigated through the developed framework. To the best of our knowledge, this is the first work that provides a generic, probabilistic cross-Layer Analysis of end-to-end delay in WSNs.
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Cross-Layer Analysis of the End-to-End Delay Distribution in Wireless Sensor Networks
2009 30th IEEE Real-Time Systems Symposium, 2009Co-Authors: Yunbo Wang, Mehmet C. Vuran, Steve GoddardAbstract:Emerging applications of wireless sensor networks (WSNs) require real-time quality of service (QoS) guarantees to be provided by the network. However, designing real-time scheduling and communication solutions for these networks is challenging since the characteristics of QoS metrics in WSNs are not well known yet. Due to the nature of wireless connectivity, it is infeasible to satisfy worst-case QoS requirements in WSNs. Instead, probabilistic QoS guarantees should be provided, which requires the definition of probabilistic QoS metrics. To provide an analytical tool for the development of real-time solutions, in this paper, the distribution of end-to-end delay in multi-hop WSNs is investigated. Accordingly, a comprehensive and accurate cross-Layer Analysis framework, which employs a stochastic queueing model in realistic channel environments, is developed. This framework captures the heterogeneity in WSNs in terms of channel quality, transmit power, queue length, and communication protocols. A case study with the TinyOS CSMA/CA MAC protocol is conducted to show how the developed framework can analytically predict the distribution of end-to-end delay. Testbed experiments are provided to validate the developed model. The cross-Layer framework can be used to identify the relationships between network parameters and the distribution of end-to-end delay and accordingly, to design real-time solutions for WSNs. Our ongoing work suggests that this framework can be easily extended to model additional QoS metrics such as energy consumption distribution. To the best of our knowledge, this is the first work to investigate probabilistic QoS guarantees in WSNs.
Mehmet C. Vuran - One of the best experts on this subject based on the ideXlab platform.
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Cross-Layer Analysis of the End-to-End Delay Distribution in Wireless Sensor Networks
IEEE ACM Transactions on Networking, 2012Co-Authors: Yunbo Wang, Mehmet C. Vuran, Steve GoddardAbstract:Emerging applications of wireless sensor networks (WSNs) require real-time quality-of-service (QoS) guarantees to be provided by the network. Due to the nondeterministic impacts of the wireless channel and queuing mechanisms, probabilistic Analysis of QoS is essential. One important metric of QoS in WSNs is the probability distribution of the end-to-end delay. Compared to other widely used delay performance metrics such as the mean delay, delay variance, and worst-case delay, the delay distribution can be used to obtain the probability to meet a specific deadline for QoS-based communication in WSNs. To investigate the end-to-end delay distribution, in this paper, a comprehensive cross-Layer Analysis framework, which employs a stochastic queueing model in realistic channel environments, is developed. This framework is generic and can be parameterized for a wide variety of MAC protocols and routing protocols. Case studies with the CSMA/CA MAC protocol and an anycast protocol are conducted to illustrate how the developed framework can analytically predict the distribution of the end-to-end delay. Extensive test-bed experiments and simulations are performed to validate the accuracy of the framework for both deterministic and random deployments. Moreover, the effects of various network parameters on the distribution of end-to-end delay are investigated through the developed framework. To the best of our knowledge, this is the first work that provides a generic, probabilistic cross-Layer Analysis of end-to-end delay in WSNs.
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error control in wireless sensor networks a cross Layer Analysis
IEEE ACM Transactions on Networking, 2009Co-Authors: Mehmet C. Vuran, Ian F. AkyildizAbstract:Error control is of significant importance for Wireless Sensor Networks (WSNs) because of their severe energy constraints and the low power communication requirements. In this paper, a cross-Layer methodology for the Analysis of error control schemes in WSNs is presented such that the effects of multi-hop routing and the broadcast nature of the wireless channel are investigated. More specifically, the cross-Layer effects of routing, medium access, and physical Layers are considered. This Analysis enables a comprehensive comparison of forward error correction (FEC) codes, automatic repeat request (ARQ), and hybrid ARQ schemes in WSNs. The validation results show that the developed framework closely follows simulation results. Hybrid ARQ and FEC schemes improve the error resiliency of communication compared to ARQ. In a multi-hop network, this improvement can be exploited by constructing longer hops (hop length extension), which can be achieved through channel-aware routing protocols, or by reducing the transmit power (transmit power control). The results of our Analysis reveal that for hybrid ARQ schemes and certain FEC codes, the hop length extension decreases both the energy consumption and the end-to-end latency subject to a target packet error rate (PER) compared to ARQ. This decrease in end-to-end latency is crucial for delay sensitive, real-time applications, where both hybrid ARQ and FEC codes are strong candidates. We also show that the advantages of FEC codes are even more pronounced as the network density increases. On the other hand, transmit power control results in significant savings in energy consumption at the cost of increased latency for certain FEC codes. The results of our Analysis also indicate the cases where ARQ outperforms FEC codes for various end-to-end distance and target PER values.
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Cross-Layer Analysis of the End-to-End Delay Distribution in Wireless Sensor Networks
2009 30th IEEE Real-Time Systems Symposium, 2009Co-Authors: Yunbo Wang, Mehmet C. Vuran, Steve GoddardAbstract:Emerging applications of wireless sensor networks (WSNs) require real-time quality of service (QoS) guarantees to be provided by the network. However, designing real-time scheduling and communication solutions for these networks is challenging since the characteristics of QoS metrics in WSNs are not well known yet. Due to the nature of wireless connectivity, it is infeasible to satisfy worst-case QoS requirements in WSNs. Instead, probabilistic QoS guarantees should be provided, which requires the definition of probabilistic QoS metrics. To provide an analytical tool for the development of real-time solutions, in this paper, the distribution of end-to-end delay in multi-hop WSNs is investigated. Accordingly, a comprehensive and accurate cross-Layer Analysis framework, which employs a stochastic queueing model in realistic channel environments, is developed. This framework captures the heterogeneity in WSNs in terms of channel quality, transmit power, queue length, and communication protocols. A case study with the TinyOS CSMA/CA MAC protocol is conducted to show how the developed framework can analytically predict the distribution of end-to-end delay. Testbed experiments are provided to validate the developed model. The cross-Layer framework can be used to identify the relationships between network parameters and the distribution of end-to-end delay and accordingly, to design real-time solutions for WSNs. Our ongoing work suggests that this framework can be easily extended to model additional QoS metrics such as energy consumption distribution. To the best of our knowledge, this is the first work to investigate probabilistic QoS guarantees in WSNs.
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Error Control in Wireless Sensor Networks: A Cross Layer Analysis
IEEE ACM Transactions on Networking, 2009Co-Authors: Mehmet C. Vuran, Ian F. AkyildizAbstract:Error control is of significant importance for wireless sensor networks (WSNs) because of their severe energy constraints and the low power communication requirements. In this paper, a cross-Layer methodology for the Analysis of error control schemes in WSNs is presented such that the effects of multi-hop routing and the broadcast nature of the wireless channel are investigated. More specifically, the cross-Layer effects of routing, medium access, and physical Layers are considered. This Analysis enables a comprehensive comparison of forward error correction (FEC) codes, automatic repeat request (ARQ), and hybrid ARQ schemes in WSNs. The validation results show that the developed framework closely follows simulation results.
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Cross-Layer Analysis of Error Control in Wireless Sensor Networks
2006 3rd Annual IEEE Communications Society on Sensor and Ad Hoc Communications and Networks, 2006Co-Authors: Mehmet C. Vuran, Ian F. AkyildizAbstract:Severe energy constraints and hence the low power communication requirements amplify the significance of the energy efficient and preferably cross-Layer error control mechanisms in wireless sensor networks (WSN). In this paper, a cross-Layer methodology for the Analysis of error control schemes in WSNs is presented such that the effects of multi-hop routing and the broadcast nature of the wireless channel are investigated. More specifically, the cross-Layer effects of routing, medium access and physical Layers are considered. This Analysis enables a comprehensive comparison of forward error correction (FEC) and automatic repeat request (ARQ) in WSNs. FEC schemes improve the error resiliency compared to ARQ. In a multi-hop network, this improvement can be exploited by reducing the transmit power (transmit power control) or by constructing longer hops (hop length extension), which can be achieved through channel-aware routing protocols. The results of our Analysis reveal that for certain FEC codes, the hop length extension decreases both the energy consumption and the end-to-end latency subject to a target PER compared to ARQ. Thus, FEC codes can be regarded as an important candidate for delay sensitive traffic in WSNs. On the other hand, transmit power control results in significant savings in energy consumption at the cost of increased latency. Moreover, the cases where ARQ outperforms FEC codes are indicated for various end-to-end distance and target PER values
