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37 results on '"dependable"'

1. CRITERIA FOR ASSESSING AND ENSURING THE TRUSTWORTHINESS IN QUALITATIVE RESEARCH

Author

Zia Ul Haq Kakar, Rizwana Rasheed, Aamir Rashid, and Salma Akhter

Subjects
credibility, dependable, neutrality, transferability, trustworthiness, guba model, Business, HF5001-6182, Management. Industrial management, HD28-70
Abstract

The trustworthiness of qualitative data has been debatable, yet it has strong support from its supporters. However, the importance and worth of qualitative data cannot be undermined. This paper presents a critical review of the trustworthiness of the qualitative data. The degree of trustworthiness of qualitative research can be measured by ensuring the credibility, transferability, dependability, and conformability of research design, process, and action. The guarantee of trustworthiness in qualitative research is more complex than in quantitative research due to its subjective nature. Many researchers and experts denied the generalizability of qualitative research. However, few researchers, like Guba (1985), developed a widely accepted model and strategies to ensure the trustworthiness and generalizability of qualitative research. Credibility is like internal validity in quantitative analysis and provides the actual data about the phenomenon. Transferability shows the degree of application of the research finding in other exact natures of context, people, groups, and settings. If the findings of one study are replicated in a similar population, condition, or context, then the findings are dependable. Neutrality is the degree of fairness of results consisting of purity of initial responses and bias-free.

Published
2023
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2. Synchronization and Scheduling of Tasks in Fault-Tolerant Computer Systems with Graceful Degradation

Author

Drabowski, Mieczyslaw, Kacprzyk, Janusz, Series Editor, Pal, Nikhil R., Advisory Editor, Bello Perez, Rafael, Advisory Editor, Corchado, Emilio S., Advisory Editor, Hagras, Hani, Advisory Editor, Kóczy, László T., Advisory Editor, Kreinovich, Vladik, Advisory Editor, Lin, Chin-Teng, Advisory Editor, Lu, Jie, Advisory Editor, Melin, Patricia, Advisory Editor, Nedjah, Nadia, Advisory Editor, Nguyen, Ngoc Thanh, Advisory Editor, Wang, Jun, Advisory Editor, Zamojski, Wojciech, editor, Mazurkiewicz, Jacek, editor, Sugier, Jarosław, editor, and Walkowiak, Tomasz, editor

Published
2021
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3. Examples of Applications of CAD Methods in the Design of Fault Tolerant Systems

Author

Drabowski, Mieczyslaw, Kacprzyk, Janusz, Series Editor, Pal, Nikhil R., Advisory Editor, Bello Perez, Rafael, Advisory Editor, Corchado, Emilio S., Advisory Editor, Hagras, Hani, Advisory Editor, Kóczy, László T., Advisory Editor, Kreinovich, Vladik, Advisory Editor, Lin, Chin-Teng, Advisory Editor, Lu, Jie, Advisory Editor, Melin, Patricia, Advisory Editor, Nedjah, Nadia, Advisory Editor, Nguyen, Ngoc Thanh, Advisory Editor, Wang, Jun, Advisory Editor, Zamojski, Wojciech, editor, Mazurkiewicz, Jacek, editor, Sugier, Jarosław, editor, and Walkowiak, Tomasz, editor

Published
2020
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4. Short-Term and Long-Term Memory in Tabu Search Algorithm for CAD of Complex Systems with Higher Degree of Dependability

Author

Drabowski, Mieczyslaw, Kacprzyk, Janusz, Series Editor, Pal, Nikhil R., Advisory Editor, Bello Perez, Rafael, Advisory Editor, Corchado, Emilio S., Advisory Editor, Hagras, Hani, Advisory Editor, Kóczy, László T., Advisory Editor, Kreinovich, Vladik, Advisory Editor, Lin, Chin-Teng, Advisory Editor, Lu, Jie, Advisory Editor, Melin, Patricia, Advisory Editor, Nedjah, Nadia, Advisory Editor, Nguyen, Ngoc Thanh, Advisory Editor, Wang, Jun, Advisory Editor, Zamojski, Wojciech, editor, Mazurkiewicz, Jacek, editor, Sugier, Jarosław, editor, and Walkowiak, Tomasz, editor

Published
2019
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5. Comparison of Results Computations of Meta-Heuristic CAD Algorithms for Complex Systems with Higher Degree of Dependability

Author

Drabowski, Mieczyslaw, Kacprzyk, Janusz, Series Editor, Pal, Nikhil R., Advisory Editor, Bello Perez, Rafael, Advisory Editor, Corchado, Emilio S., Advisory Editor, Hagras, Hani, Advisory Editor, Kóczy, László T., Advisory Editor, Kreinovich, Vladik, Advisory Editor, Lin, Chin-Teng, Advisory Editor, Lu, Jie, Advisory Editor, Melin, Patricia, Advisory Editor, Nedjah, Nadia, Advisory Editor, Nguyen, Ngoc Thanh, Advisory Editor, Wang, Jun, Advisory Editor, Zamojski, Wojciech, editor, Mazurkiewicz, Jacek, editor, Sugier, Jarosław, editor, and Walkowiak, Tomasz, editor

Published
2019
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6. Peroneus Brevis Muscle Flap as a Tissue Cover for Defect over Lower Mid Leg and Ankle Defects: A Case Series.

Author

VAGHANI, SANJAY GORDHANBHAI and CHAUDHARI, GANESH SADASHIV

Subjects
*ANKLE, *SURGICAL flaps, *FREE flaps, *FRACTURE fixation, *TISSUES, *INTERNAL fixation in fractures
Abstract

Mid leg and ankle area are more vulnerable for post-traumatic full thickness soft tissue loss. Implants used in osteosynthesis in this region are also at risk of exposure as its placement is in subcutaneous plane as well as precarious blood supply in shin region. Various options like local flap to free flap are described for reconstruction of small and medium size defects in this region. Peroneus brevis is also well described in literatures. In this case series which was done over the period of six years that includes 10 patients with post-traumatic as well as post orthopaedics surgical intervention defects in lower mid leg, ankle region. Patients were selected for proximally based and distally based peroneus brevis muscle flap according to the location of defects. Data regarding age, sex, aetiological factor, size of defect, type of flap, survival of flap, donor site complications were recorded. Out of 10 patients, eight were males and two were females. Major aetiological factor was two wheeler road traffic accident. Majority of the patient had orthopaedic surgical intervention for fracture fixation prior to or along with flap surgery. Only one patient, in this series had marginal flap necrosis. Rest of flaps survived well without any donor site complications. In authors experience peroneus brevis muscle flap is dependable for medium size defects over lower leg and ankle. [ABSTRACT FROM AUTHOR]

Published
2021
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7. Peroneus Brevis Muscle Flap as a Tissue Cover for Defect over Lower Mid Leg and Ankle Defects: A Case Series

Author

Sanjay Gordhanbhai Vaghani and ganesh Sadashiv chaudhari

Subjects
dependable, implant exposure, post-traumatic, proximally based, Medicine
Abstract

Mid leg and ankle area are more vulnerable for post-traumatic full thickness soft tissue loss. Implants used in osteosynthesis in this region are also at risk of exposure as its placement is in subcutaneous plane as well as precarious blood supply in shin region. Various options like local flap to free flap are described for reconstruction of small and medium size defects in this region. Peroneus brevis is also well described in literatures. In this case series which was done over the period of six years that includes 10 patients with post-traumatic as well as post orthopaedics surgical intervention defects in lower mid leg and ankle region. Patients were selected for proximally and distally based peroneus brevis muscle flap according to the location of defects. Data regarding age, sex, aetiological factor, size of defect, type of flap, survival of flap, donor site complications were recorded. Out of 10 patients, eight were males and two were females. Major aetiological factor was two wheeler road traffic accident. Majority of the patient had orthopaedic surgical intervention for fracture fixation prior to or along with flap surgery. Only one patient, in this series had marginal flap necrosis. Rest of flaps survived well without any donor site complications. In authors experience peroneus brevis muscle flap is dependable for medium size defects over lower leg and ankle.

Published
2021
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8. Adaptation of Ant Colony Algorithm for CAD of Complex Systems with Higher Degree of Dependability

Author

Drabowski, Mieczyslaw, Kacprzyk, Janusz, Series editor, Pal, Nikhil R., Advisory editor, Bello Perez, Rafael, Advisory editor, Corchado, Emilio S., Advisory editor, Hagras, Hani, Advisory editor, Kóczy, László T., Advisory editor, Kreinovich, Vladik, Advisory editor, Lin, Chin-Teng, Advisory editor, Lu, Jie, Advisory editor, Melin, Patricia, Advisory editor, Nedjah, Nadia, Advisory editor, Nguyen, Ngoc Thanh, Advisory editor, Wang, Jun, Advisory editor, Zamojski, Wojciech, editor, Mazurkiewicz, Jacek, editor, Sugier, Jarosław, editor, and Walkowiak, Tomasz, editor

Published
2018
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11. Towards Dependable IoT via Interface Selection: Predicting Packet Delivery at the End Node in LoRaWAN Networks

Author

Marc Guerrero, Cristina Cano, Xavier Vilajosana, and Pascal Thubert

Subjects
IoT, LoRaWAN, dual-band, dependable, estimation, Chemical technology, TP1-1185
Abstract

Estimating channel conditions to predict packet delivery can be exploited as a powerful tool to ensure wireless networks dependability. In this article we explore the practical application of this idea from the end-device perspective, using the LoRaWAN protocol stack. We aim to understand if packet delivery can be estimated considering different levels of feedback at the end-device. For that, an extensive data collection campaign is carried out. Through an analysis of the obtained traces, we establish correlations between connectivity metrics at the end node and the fact that a packet is received at the gateway. The study is complemented considering different levels of feedback: (i) No feedback, (ii) enabling acknowledgements frames, and (iii) considering application/control plane data about the channel status at the gateway side. The results show that it is possible to estimate packet delivery in all the evaluated cases.

Published
2021
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14. A Dataset to Evaluate IEEE 802.15.4g SUN for Dependable Low-Power Wireless Communications in Industrial Scenarios

Author

Pere Tuset-Peiró, Ruan D. Gomes, Pascal Thubert, Eva Cuerva, Eduard Egusquiza, and Xavier Vilajosana

Subjects
IEEE 802.15.4g, smart utility networks, low-power, wireless, communications, dependable, Bibliography. Library science. Information resources
Abstract

This article presents a dataset obtained from the deployment of an IEEE 802.15.4g SUN (Smart Utility Network) single-hop network (11 nodes) in a large industrial scenario (110,044 m 2 ) for a long period of time (99 days). The dataset contains ∼11 M entries with RSSI (Received Signal Strength Indicator), CCA (Clear Channel Assessment), and PDR (Packet Delivery Ratio) values. The analyzed results show a high variability in the average RSSI (i.e., between −82.1 dBm and −101.7 dBm) and CCA (i.e., between −111.2 dBm and −119.9 dBm) values, which is caused by the effects of multi-path propagation and external interference. Despite being above the sensitivity limit for each modulation, these values result in poor average PDR values (i.e., from 65.9% to 87.4%), indicating that additional schemes are needed to meet the link reliability requirements of industrial applications. Hence, the presented dataset will allow researchers and practitioners to propose novel mechanisms and evaluate their performance using realistic conditions, enabling the dependability vision of the RAW (Reliable and Available Wireless) WG (Working Group) at the IETF (Internet Engineering Task Force).

Published
2020
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16. DSO: Dependable Signing Overlay

Author

Gu, Guofei, Fogla, Prahlad, Lee, Wenke, Blough, Douglas, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Dough, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Zhou, Jianying, editor, Yung, Moti, editor, and Bao, Feng, editor

Published
2006
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17. Towards Dependable IoT via Interface Selection: Predicting Packet Delivery at the End Node in LoRaWAN Networks

Author

Cristina Cano, Xavier Vilajosana, Marc Guerrero, Pascal Thubert, and Universitat Oberta de Catalunya (UOC)

Subjects
IoT, Computer science, 02 engineering and technology, lcsh:Chemical technology, Biochemistry, Article, Analytical Chemistry, Protocol stack, Perspective (geometry), Default gateway, 0202 electrical engineering, electronic engineering, information engineering, Dependability, lcsh:TP1-1185, Electrical and Electronic Engineering, Instrumentation, estimation, Network packet, Wireless network, business.industry, Node (networking), dependable, 020206 networking & telecommunications, Atomic and Molecular Physics, and Optics, LoRaWAN, dual-band, 020201 artificial intelligence & image processing, business, Computer network, Communication channel
Abstract

first_pagesettings Open AccessArticle Towards Dependable IoT via Interface Selection: Predicting Packet Delivery at the End Node in LoRaWAN Networks by Marc Guerrero 1,*,Cristina Cano 1ORCID,Xavier Vilajosana 1ORCID andPascal Thubert 2ORCID 1 Computer Science, Multimedia and Telecommunications Department, Universitat Oberta de Catalunya, 08018 Barcelona, Spain 2 Cisco Systems France S.à.r.l., 92130 Issy-les-Moulineaux, France * Author to whom correspondence should be addressed. Academic Editor: David Plets Sensors 2021, 21(8), 2707; https://doi.org/10.3390/s21082707 Received: 10 March 2021 / Revised: 28 March 2021 / Accepted: 3 April 2021 / Published: 12 April 2021 (This article belongs to the Special Issue Dependable IoT Networking) Download PDF Browse Figures Review Reports Citation Export Abstract Estimating channel conditions to predict packet delivery can be exploited as a powerful tool to ensure wireless networks dependability. In this article we explore the practical application of this idea from the end-device perspective, using the LoRaWAN protocol stack. We aim to understand if packet delivery can be estimated considering different levels of feedback at the end-device. For that, an extensive data collection campaign is carried out. Through an analysis of the obtained traces, we establish correlations between connectivity metrics at the end node and the fact that a packet is received at the gateway. The study is complemented considering different levels of feedback: (i) No feedback, (ii) enabling acknowledgements frames, and (iii) considering application/control plane data about the channel status at the gateway side. The results show that it is possible to estimate packet delivery in all the evaluated cases.

Published
2021

18. A dataset to evaluate IEEE 802.15.4g sun for dependable low-power wireless communications in industrial scenarios

Author

Universitat Politècnica de Catalunya. Departament d'Enginyeria de Projectes i de la Construcció, Universitat Politècnica de Catalunya. GRIC - Grup de Recerca i Innovació de la Construcció, Tuset Peiro, Pere, Cuerva Contreras, Eva, Egusquiza Estévez, Eduard, Vilajosana Guillén, Xavier, Universitat Politècnica de Catalunya. Departament d'Enginyeria de Projectes i de la Construcció, Universitat Politècnica de Catalunya. GRIC - Grup de Recerca i Innovació de la Construcció, Tuset Peiro, Pere, Cuerva Contreras, Eva, Egusquiza Estévez, Eduard, and Vilajosana Guillén, Xavier

Abstract

This article presents a dataset obtained from the deployment of an IEEE 802.15.4g SUN (Smart Utility Network) single-hop network (11 nodes) in a large industrial scenario (110,044 m 2 ) for a long period of time (99 days). The dataset contains ~11 M entries with RSSI (Received Signal Strength Indicator), CCA (Clear Channel Assessment), and PDR (Packet Delivery Ratio) values. The analyzed results show a high variability in the average RSSI (i.e., between -82.1 dBm and -101.7 dBm) and CCA (i.e., between -111.2 dBm and -119.9 dBm) values, which is caused by the effects of multi-path propagation and external interference. Despite being above the sensitivity limit for each modulation, these values result in poor average PDR values (i.e., from 65.9% to 87.4%), indicating that additional schemes are needed to meet the link reliability requirements of industrial applications. Hence, the presented dataset will allow researchers and practitioners to propose novel mechanisms and evaluate their performance using realistic conditions, enabling the dependability vision of the RAW (Reliable and Available Wireless) WG (Working Group) at the IETF (Internet Engineering Task Force)., Peer Reviewed, Postprint (published version)

Published
2020

19. Applying Architectural Reflection on Dependable Software.

Author

Li Xiaojian, Ying Shi, Zheng Ying, and Xie Dan

Subjects
COMPUTER reliability, COMPUTER software, SOFTWARE engineering, SOFTWARE architecture, METADATA
Abstract

At present, how to improve software dependability is a common problem to academia and industry of software engineering. This paper presents an approach based on architecture reflection mechanism to achieve the goal. We divide software architecture into two levels: meta-level and base-level. Meta-level mainly includes metaobjects and base-level includes application components. First, we explicitly express the meta information at meta-level and construct the metamodel. All metaobjects are reified by the components at base-level. Meta-level act as the interface for outside software, some requests will be intercepted by the meta-level according to dependability strategy. This method prevents the software from being destroyed involuntarily or maliciously. [ABSTRACT FROM AUTHOR]

Published
2007

20. A dataset to evaluate IEEE 802.15.4g sun for dependable low-power wireless communications in industrial scenarios

Author

Eva Cuerva, Xavier Vilajosana, Eduard Egusquiza, Ruan Delgado Gomes, Pascal Thubert, Pere Tuset-Peiró, Universitat Politècnica de Catalunya. Departament d'Enginyeria de Projectes i de la Construcció, and Universitat Politècnica de Catalunya. GRIC - Grup de Recerca i Innovació de la Construcció

Subjects
low-power, Information Systems and Management, industrial, Computer science, Reliability (computer networking), Real-time computing, communications, smart utility networks, Interference (communication), Reliable, Informàtica [Àrees temàtiques de la UPC], available, Dependable, predictable, Low-power, dataset, Wireless, Dependability, reliable, IEEE 802.15, Smart utility networks, business.industry, Network packet, dependable, Available, IEEE 802.15.4g, Predictable, lcsh:Z, Communications, Computer Science Applications, Power (physics), lcsh:Bibliography. Library science. Information resources, Wireless communication systems, wireless, Comunicació sense fil, Sistemes de, The Internet, Industrial, business, Information Systems, Dataset
Abstract

This article presents a dataset obtained from the deployment of an IEEE 802.15.4g SUN (Smart Utility Network) single-hop network (11 nodes) in a large industrial scenario (110,044 m 2 ) for a long period of time (99 days). The dataset contains &sim, 11 M entries with RSSI (Received Signal Strength Indicator), CCA (Clear Channel Assessment), and PDR (Packet Delivery Ratio) values. The analyzed results show a high variability in the average RSSI (i.e., between &minus, 82.1 dBm and &minus, 101.7 dBm) and CCA (i.e., between &minus, 111.2 dBm and &minus, 119.9 dBm) values, which is caused by the effects of multi-path propagation and external interference. Despite being above the sensitivity limit for each modulation, these values result in poor average PDR values (i.e., from 65.9% to 87.4%), indicating that additional schemes are needed to meet the link reliability requirements of industrial applications. Hence, the presented dataset will allow researchers and practitioners to propose novel mechanisms and evaluate their performance using realistic conditions, enabling the dependability vision of the RAW (Reliable and Available Wireless) WG (Working Group) at the IETF (Internet Engineering Task Force).

Published
2020
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21. Adapting grid computing environments dependable with virtual machines: design, implementation, and evaluations.

Author

Shi, Xuanhua, Jin, Hai, Wu, Song, Zhu, Wei, and Qi, Li

Subjects
*GRID computing, *VIRTUAL machine systems, *SYSTEMS design, *APPLICATION software, *PERFORMANCE evaluation, *COMPUTER reliability
Abstract

Due to its potential, using virtual machines in grid computing is attracting increasing attention. Most of the researches focus on how to create or destroy a virtual execution environments for different kinds of applications, while the policy of managing the virtual environments is not widely discussed. This paper proposes the design, implementation, and evaluation of an adaptive and dependable virtual execution environment for grid computing, ADVE, which focuses on the policy of managing virtual machines in grid environments. To build a dependable virtual execution environments for grid applications, ADVE provides an set of adaptive policies managing virtual machine, such as when to create and destroy a new virtual execution environment, when to migrate applications from one virtual execution environment to a new virtual execution environment. We conduct experiments over a cluster to evaluate the performance of ADVE, and the experimental results show that ADVE can improve the throughput and the reliability of grid resources with the adaptive management of virtual machines. [ABSTRACT FROM AUTHOR]

Published
2013
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22. DUO: Integration of dependable undervolting in operating systems

Subjects
Reliablity, Dependable, Secure Instance, Energy Harvesting, Undervolting, Operating System, Robustness, Co-Processor
Abstract

DUO is a co-processor-based energy harvesting solution that integrates the existing undervolting approach IdealVolting into the RIOT operating system. By integrating the existing approach into an operating system, the benefits of undervolting can be used in regular applications. The user can use IdealVolting along with existing applications and take advantage of an active undervolting approach. Especially in energy harvesting applications, that already use an energy harvesting chip with adjustable output voltage, the approach can be easily integrated. Our evaluation compares a duty-cycle sample application within RIOT OS with and without IdealVolting. It shows that DUO can save up to 20 % compared to the plain application only by adding IdealVolting to the application. Our poster highlights important aspects of our implementation and motivates the benefits of a co-processor in such a system.

Published
2019

23. Dependable interference-aware time-slotted channel hopping for wireless sensor networks

Author

Tavakoli, R., Nabi, M., Basten, T., Goossens, K.G.W., Tavakoli, R., Nabi, M., Basten, T., and Goossens, K.G.W.

Abstract

IEEE 802.15.4 Time-Slotted Channel Hopping (TSCH) aims to improve communication reliability in Wireless Sensor Networks (WSNs) by reducing the impact of the medium access contention, multipath fading, and blocking of wireless links. While TSCH outperforms single-channel communications, cross-technology interference on the license-free ISM bands may affect the performance of TSCH-based WSNs. For applications such as in-vehicle networks for which interference is dynamic over time, it leads to non-guaranteed reliability of the communications over time. This article proposes an Enhanced version of the TSCH protocol together with a Distributed Channel Sensing technique (ETSCH+DCS) that dynamically detects good quality channels to be used for communication. The quality of channels is extracted using a combination of a central and a distributed channel-quality estimation technique. The central technique uses Non-Intrusive Channel-quality Estimation (NICE) technique that proactively performs energy detections in the idle part of each timeslot at the coordinator of the network. NICE enables ETSCH to follow dynamic interference, while it does not reduce throughput of the network. The distributed channel quality estimation technique is executed by all the nodes in the network, based on their communication history, to detect interference sources that are hidden from the coordinator. We did two sets of lab experiments with controlled interferers and a number of simulations using real-world interference datasets to evaluate ETSCH. Experimental and simulation results show that ETSCH improves reliability of network communications, compared to basic TSCH and the state-of-the-art solution. In some experimental scenarios NICE itself has been able to increase the average packet reception ratio by 22% and shorten the length of burst packet losses by half, compared to the plain TSCH protocol. Further experiments show that DCS can reduce the effect of hidden interference (which is not det

Published
2018

24. Dependable interference-Aware time-Slotted channel hopping for wireless sensor networks

Author

Twan Basten, Majid Nabi, Rasool Tavakoli, Kees Goossens, Electronic Systems, Cyber-Physical Systems Center Eindhoven, Networked Embedded Systems Lab, and CompSOC Lab- Predictable & Composable Embedded Systems

Subjects
IEEE 802.15.4, Computer Networks and Communications, Computer science, Reliability (computer networking), HOL - Holst, Throughput, 02 engineering and technology, Information Society, 01 natural sciences, Interference (communication), Wireless co-existence, TSCH, Dependable, 0202 electrical engineering, electronic engineering, information engineering, Wireless, Infostructures, TS - Technical Sciences, business.industry, Network packet, Blocking (radio), 010401 analytical chemistry, ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS, 020206 networking & telecommunications, Time-slotted channel hopping, In-vehicle wireless sensor networks, 0104 chemical sciences, Nano Technology, Channel quality estimation, business, Interference, Wireless sensor network, Multipath propagation, Computer network
Abstract

IEEE 802.15.4 Time-Slotted Channel Hopping (TSCH) aims to improve communication reliability in Wireless Sensor Networks (WSNs) by reducing the impact of the medium access contention, multipath fading, and blocking of wireless links. While TSCH outperforms single-channel communications, cross-technology interference on the license-free ISM bands may affect the performance of TSCH-based WSNs. For applications such as in-vehicle networks for which interference is dynamic over time, it leads to non-guaranteed reliability of the communications over time. This article proposes an Enhanced version of the TSCH protocol together with a Distributed Channel Sensing technique (ETSCH+DCS) that dynamically detects good quality channels to be used for communication. The quality of channels is extracted using a combination of a central and a distributed channel-quality estimation technique. The central technique uses Non-Intrusive Channel-quality Estimation (NICE) technique that proactively performs energy detections in the idle part of each timeslot at the coordinator of the network. NICE enables ETSCH to follow dynamic interference, while it does not reduce throughput of the network. The distributed channel quality estimation technique is executed by all the nodes in the network, based on their communication history, to detect interference sources that are hidden from the coordinator. We did two sets of lab experiments with controlled interferers and a number of simulations using real-world interference datasets to evaluate ETSCH. Experimental and simulation results show that ETSCH improves reliability of network communications, compared to basic TSCH and the state-of-the-art solution. In some experimental scenarios NICE itself has been able to increase the average packet reception ratio by 22% and shorten the length of burst packet losses by half, compared to the plain TSCH protocol. Further experiments show that DCS can reduce the effect of hidden interference (which is not detectable by NICE) on the packet reception ratio of the affected links by 50%.

Published
2018

25. Dependable interference-Aware time-Slotted channel hopping for wireless sensor networks

Subjects
IEEE 802.15.4, Infostructures, TS - Technical Sciences, TSCH, Dependable, ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS, Nano Technology, HOL - Holst, Channel quality estimation, Information Society, Time-slotted channel hopping, Interference, In-vehicle wireless sensor networks
Abstract

IEEE 802.15.4 Time-Slotted Channel Hopping (TSCH) aims to improve communication reliability in Wireless Sensor Networks (WSNs) by reducing the impact of the medium access contention, multipath fading, and blocking of wireless links. While TSCH outperforms single-channel communications, cross-technology interference on the license-free ISM bands May affect the performance of TSCH-based WSNs. For applications such as in-vehicle networks for which interference is dynamic over time, it leads to non-guaranteed reliability of the communications over time. This article proposes an Enhanced version of the TSCH protocol together with a Distributed Channel Sensing technique (ETSCH+DCS) that dynamically detects good quality channels to be used for communication. The quality of channels is extracted using a combination of a central and a distributed channel-quality estimation technique. The central technique uses Non-Intrusive Channel-quality Estimation (NICE) technique that proactively performs energy detections in the idle part of each timeslot at the coordinator of the network. NICE enables ETSCH to follow dynamic interference, while it does not reduce throughput of the network. The distributed channel quality estimation technique is executed by all the nodes in the network, based on their communication history, to detect interference sources that are hidden from the coordinator. We did two sets of lab experiments with controlled interferers and a number of simulations using real-world interference datasets to evaluate ETSCH. Experimental and simulation results show that ETSCH improves reliability of network communications, compared to basic TSCH and the state-of-the-art solution. In some experimental scenarios NICE itself has been able to increase the average packet reception ratio by 22% and shorten the length of burst packet losses by half, compared to the plain TSCH protocol. Further experiments show that DCS can reduce the effect of hidden interference (which is not detectable by NICE) on the packet reception ratio of the affected links by 50%.

Published
2018

26. Towards Dependable IoT via Interface Selection: Predicting Packet Delivery at the End Node in LoRaWAN Networks.

Author

Guerrero, Marc, Cano, Cristina, Vilajosana, Xavier, Thubert, Pascal, and Plets, David

Subjects
*METADATA, *INTERNET of things, *TRACE analysis, *GATEWAYS (Computer networks)
Abstract

Estimating channel conditions to predict packet delivery can be exploited as a powerful tool to ensure wireless networks dependability. In this article we explore the practical application of this idea from the end-device perspective, using the LoRaWAN protocol stack. We aim to understand if packet delivery can be estimated considering different levels of feedback at the end-device. For that, an extensive data collection campaign is carried out. Through an analysis of the obtained traces, we establish correlations between connectivity metrics at the end node and the fact that a packet is received at the gateway. The study is complemented considering different levels of feedback: (i) No feedback, (ii) enabling acknowledgements frames, and (iii) considering application/control plane data about the channel status at the gateway side. The results show that it is possible to estimate packet delivery in all the evaluated cases. [ABSTRACT FROM AUTHOR]

Published
2021
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30. Developing dependable software for a system-of-systems

Author

Caffall, Dale Scott, Michael, James Bret, and Department of Computer Science

Subjects
Kernel, Model checking, Trustworthy, Assertions, Contracts, Real-time system, Dependable, Formal methods, Architecture, Component-based software engineering, Distributed system, ComputerApplications_COMPUTERSINOTHERSYSTEMS, System-of-systems
Abstract

Capturing and realizing the desired system-of-systems behavior in the traditional natural language development documents is a complex issue given that the legacy systems in a system-of-systems exhibit independent behaviors. As a result of a development strategy of interconnecting systems, the emergent behavior of the system-of-systems cannot be predicted. In our consideration of dependable software for a system-of-systems, we used our case study of the Ballistic Missile Defense System to study the development of architectural views, distributed-system and real-time design considerations, components, contract interfaces, and the application of formal methods in system-of-systems specifications. We developed a prototype of a battle manager and demonstrated a slice of the formal model of the battle manager. Given the technical contributions of this research, we conclude that it is possible to develop an architecture from which we can reason about the controlling software for a system-of-systems. Furthermore, we can realize the controlling software for a system-of-systems through the concepts of component-based software engineering. Finally, we can apply formal methods in the design and development of the controlling software for a system-of-systems by specifying the requirements for the software components with assertions and employing a runtime-verification tool to verify the desired behavior as specified by the assertions. http://archive.org/details/developingdepend1094510039 Civilian, United States Missile Defense Agency Approved for public release; distribution is unlimited.

Published
2005

32. MORE THAN A NURSE.

Author

Waters, Adele

Subjects
*PATIENT satisfaction, *PATIENTS, *NURSE-patient relationships, *JOB enrichment, *PERSONNEL management, *EMPLOYEE motivation, WORK & psychology
Abstract

Patients pay tribute to nurses who have fulfilled their role with compassion and rigour. [ABSTRACT FROM AUTHOR]

Published
2008
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33. Disaster-tolerant dependable wireless network.

Author

Miura, Ryu, Inoue, Masugi, Owada, Yasunori, Tsuji, Hiroyuki, and Hara, Shinsuke

Abstract

The Great East Japan Earthquake reminded us of the significance to secure communication network under disasters. Wireless technologies would play a most significant role in the devastating disasters such as one by Tsunami. We need to have rapidly deployable communication network in addition to, or alternative to, damaged or congested cellular networks. Studies to establish the disaster-tolerant private wireless access network are undergoing. We present the architecture of dependable wireless network characterized by decentralized mesh topology and relay system using unmanned aerial systems (UAS). [ABSTRACT FROM PUBLISHER]

Published
2012

34. Finding George Bailey: Wonderful leaders, wonderful lives

Author

Light, Mark

Subjects
leadership, change, purposeful, servant leadership, self-sacrifice, trustworthy, vision, visionary, results driven, decisive, determined, dependable, adaptive, alert, aligned, allied, empowerment, nonprofit
Abstract

He is underpaid and overworked, his organization lives from payroll to payroll with an overtaxed and underpowered staff and a contentious board of directors. He sacrifices for the mission, but is frustrated about forgone personal dreams. He is George Bailey, the central character in Frank Capra's film It's a Wonderful Life and he practices Leadership for Good by being a mission centered, visionary, results driven, and adaptive difference maker. Through a construct-building non-generalizable mixed methods study with two concurrent, but independent phases—instrumental case study and Delphi—this study searched for real-life Baileys, to test whether or not Leadership for Good extends beyond the silver screen, to see whether or not life imitates art. The results supported all five propositions, although certain elements within the propositions were refuted and new elements substantiated. In addition to gaining a deeper understanding of the Leadership for Good construct, enriching the literature about nonprofit leadership, and reinforcing the usefulness of mixed methods research including Delphi technique, the study suggested that there were two primary types of leaders—those with a bias for growth and those with a bias for execution—who delivered equally superior financial results to the bottom line. As part of this finding, it appeared that these leaders practiced situational leadership in the here-and-now, but used contingency leadership over the long run to gravitate to preferred contexts—growth or execution—that corresponded roughly to periods of evolution and revolution. Other implications of the study were the reinforcement of the centrality of mission at the personal and organization levels, a more comprehensive understanding about what causes stress for those who practice Leadership for Good, and the ways in which leaders think about change. The electronic version of the dissertation is accessible at the OhioLINK ETD center http://www.ohiolink.edu/etd/.

Published
2007

35. Design of low-cost dependable systems for distributed embedded applications.

Author

Kandasamy, Nagarajan

Subjects
Applications, Cost, Dependable, Design, Distributed Systems, Embedded Systems, Failure Diagnosis, Low
Abstract

Distributed computers systems are increasingly being embedded in complex products such as automobiles which are aimed at cost-sensitive consumer markets, and so must be both highly dependable and cheap. The overall goal of our research is to develop low-cost methods to improve the dependability of such systems. This thesis develops software-based methods for implementing predictable and low-cost diagnosis and recovery in distributed embedded systems. We first show how to integrate time-redundant recovery policies such as task retry and primary/backup in a time triggered or statically scheduled system. Our method enables a processor to recover from transient and intermittent task failures without disrupting ongoing operations on other processors, and with moderate performance overhead, as confirmed by our experimental results. We also address distributed failure diagnosis under deadline and resource constraints and present a diagnosis scheme to identify faulty actuators in a steer-by-wire control application. Using software-implemented diagnostic tests, we formulate and solve the test-scheduling problem guaranteeing actuator diagnosis within a specified deadline while meeting the performance goals of the application. Finally, we address the design of low-cost communication networks that guarantee to meet both performance and dependability requirements of the distributed applications under consideration. We propose a design method for time-triggered communication protocols where processors use a static and global schedule to exchange messages. We also present a technique for fault-tolerant message allocation and scheduling which provides jitter-free and predictable transmission in such protocols using the minimum number of buses.

Published
2003

36. Constructing scalable dependable distributed systems.

Author

Iekel-Johnson, Scott Douglas

Subjects
Constructing, Dependable, Distributed Systems, Fault Tolerance, Real-time Communication, Scalable
Abstract

In recent years, the study of distributed systems has become an increasingly important focus of computer science research. One class of distributed system that has become widely used is the dependable, or fault-tolerant distributed system. Building a dependable distributed system requires addressing a number of important issues, such as communication reliability, message ordering, quality of service, shared state maintenance, and failure detection and recovery. Central to all of these concerns is the issue of scalability, which is becoming increasingly important as the focus of distributed system development moves toward large-scale, wide-area, heterogeneous systems. One popular paradigm which has been developed for structuring dependable distributed systems is the group communication model. Unfortunately, experience has shown that group communication often does not scale well for large systems. Scalability issues typically manifest themselves in two ways: decreasing performance as the system grows larger, and great increases in the time and effort required to design and implement the system. Consequently, our research has focused on two complementary areas: enabling predictable and timely group communication, and new high-level communication abstractions. With predictable and timely group communication, we can alleviate the performance impact of increasing system size and complexity while still taking advantage of the message delivery and fault-tolerance guarantees provided by process groups. By developing new communication abstractions, we believe we can simplify a distributed system's design and construction by bridging the gap between the low-level services typically offered by group communication middleware and the high-level needs of the applications that use it.

Published
2001

37. Developing dependable software for a system-of-systems

Author

Michael, James Bret, Department of Computer Science, Caffall, Dale Scott, Michael, James Bret, Department of Computer Science, and Caffall, Dale Scott

Abstract

Capturing and realizing the desired system-of-systems behavior in the traditional natural language development documents is a complex issue given that the legacy systems in a system-of-systems exhibit independent behaviors. As a result of a development strategy of interconnecting systems, the emergent behavior of the system-of-systems cannot be predicted. In our consideration of dependable software for a system-of-systems, we used our case study of the Ballistic Missile Defense System to study the development of architectural views, distributed-system and real-time design considerations, components, contract interfaces, and the application of formal methods in system-of-systems specifications. We developed a prototype of a battle manager and demonstrated a slice of the formal model of the battle manager. Given the technical contributions of this research, we conclude that it is possible to develop an architecture from which we can reason about the controlling software for a system-of-systems. Furthermore, we can realize the controlling software for a system-of-systems through the concepts of component-based software engineering. Finally, we can apply formal methods in the design and development of the controlling software for a system-of-systems by specifying the requirements for the software components with assertions and employing a runtime-verification tool to verify the desired behavior as specified by the assertions., http://archive.org/details/developingdepend1094510039, Civilian, United States Missile Defense Agency, Approved for public release; distribution is unlimited.

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