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  • 151.
    Bakhshi Valojerdi, Zeinab
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Rodriguez-Navas, Guillermo
    Hansson, Hans
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Verifying the timing of a persistent storage for stateful fog applications2022In: 6th International Conference on Computer, Software and Modeling (ICCSM), Institute of Electrical and Electronics Engineers Inc. , 2022, p. 1-8Conference paper (Refereed)
    Abstract [en]

    In this paper, we analyze the failure semantics of a persistent fault-tolerant storage solution for stateful fog applications. This storage system is a container-based solution that provides data availability and consistency in a distributed container-based fog architecture. We evaluate the behavior of this storage system with a formal model that includes all the important time parameters and temporal aspects of the solution. This allows us to verify data consistency and other fault-tolerance properties of our system model while considering application startup latency, together with synchronization intervals and delays. We prove that the solution can tolerate failures at application, node, communication and storage level with the ability to automatically recover from failures and provides data consistency within the synchronization delay defined as t time units, which we can calculate for a given system configuration.

  • 152.
    Bakhshi, Zeinab
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Najafabadi, Zahra
    Distributed and parallel system group, University of Innsbruck, Austria.
    Rodriguez-Navas, Guillermo
    Hansson, Hans
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Prodan, Radu
    Department of Information Technology, University of Klagenfurt, Austria.
    Storage placement in continuum computing for a robotic applicationManuscript (preprint) (Other academic)
    Abstract [en]

    This paper analyzes the timing performance of a persistent storage designed for distributed containerbased architectures in industrial control applications. The storage ensures data availability andconsistency while accommodating faults. The analysis considers four aspects: 1. placement strategy,2. design options, 3. data size, and 4. evaluation under faulty conditions. Experimental results considering the timing constraints in industrial applications indicate that the storage solution can meet criticaldeadlines, particularly under specific failure patterns. Moreover, this evaluation method is applicablefor assessing other container-based critical applications with timing constraints that require persistentstorage. Further comparison results reveal that, while the method may underperform current centralized solutions under fault-free conditions, it outperforms the centralized solutions in failure scenarios

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  • 153.
    Bakhshi, Zeinab
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Rodriguez-Navas, Guillermo
    Nokia, Israel.
    Hansson, Hans
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Analyzing the performance of persistent storage for fault-tolerant stateful fog applications2023In: Journal of systems architecture, ISSN 1383-7621, E-ISSN 1873-6165, Vol. 144, article id 103004Article in journal (Refereed)
    Abstract [en]

    In this paper, we analyze the scalability and performance of a persistent, fault-tolerant storage approach that provides data availability and consistency in a distributed container-based architecture with intended use in industrial control applications. We use simulation to evaluate the performance of this storage system in terms of scalability and failures. As the industrial applications considered have timing constraints, the simulation results show that for certain failure patterns, it is possible to determine whether the storage solution can meet critical deadlines. The presented approach is applicable for evaluating timing constraints also of other container-based critical applications that require persistent storage.

  • 154.
    Bakhshi, Zeynab
    et al.
    RighTel, Iran.
    Balador, Ali
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. RISE SICS, Västerås, Sweden.
    Mustafa, Jawad
    RISE SICS, Västerås, Sweden.
    Industrial IoT Security Threats and Concerns by Considering CISCO and Microsoft IoT reference Models2018In: IEEE WCNCW 2018 IEEE WCNCW 2018: 2018 IEEE Wireless Communications and Networking Conference Workshops, 2018, p. 173-178Conference paper (Refereed)
    Abstract [en]

    This paper investigates security concerns and issues for Industrial Internet of Things (IIoT). The IIoT is an emerging transformation, bringing great values to every industry. Although this rapid alter in industries create values, but there are concerns about security issues, most of which would be still unknown due to the novelty of this platform. In order to provide a guideline for those who want to investigate IoT security and contribute to its improvement, this paper attempts to provide a list of security threats and issues on the cloud-side layer of IoT, which consists of data accumulation and abstraction levels. For this reason, we choose Cisco and Microsoft Azure IoT Architecture as reference models. Then, two layers of Cisco reference architecture model have been chosen to be investigated for their security issues. Finally, consideration of security issues has been briefly explained.

  • 155.
    Balador, Ali
    et al.
    SICS Swedish ICT Västerås AB, Sweden.
    Böhm, Annette
    Halmstad University, Sweden.
    Calafate, Carlos T.
    Universitat Politecnica de Valencia, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de Valencia, Spain.
    A Reliable Token-Based MAC Protocol for V2V Communication in Urban VANET2016In: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications PIMRC 16, Valencia, Spain, 2016Conference paper (Refereed)
    Abstract [en]

    Safety applications developed for vehicular environments require every vehicle to periodically broadcast its status information (beacon) to all other vehicles, thereby avoiding the risk of car accidents in the road. Due to the high requirements on timing and reliability posed by traffic safety applications, the current IEEE 802.11p standard, which uses a random access Medium Access Control (MAC) protocol, faces difficulties to support timely and reliable data dissemination in vehicular environments where no acknowledgement or RTS/CTS (Request-to-Send/Clear-to-Send) mechanisms are adopted. In this paper, we propose the Dynamic Token-Based MAC (DTB-MAC) protocol. It implements a token passing approach on top of a random access MAC protocol to prevent channel contention as much as possible, thereby improving the reliability of safety message transmissions. Our proposed protocol selects one of the neighbouring nodes as the next transmitter; this selection accounts for the need to avoid beacon lifetime expiration. Therefore, it automatically offers retransmission opportunities to allow vehicles to successfully transmit their beacons before the next beacon is generated whenever time and bandwidth are available. Based on simulation experiments, we show that the DTB-MAC protocol can achieve better performance than IEEE 802.11p in terms of channel utilization and beacon delivery ratio for urban scenarios.

  • 156.
    Balador, Ali
    et al.
    SICS Swedish ICT Västerås AB, Sweden.
    Böhm, Annette
    Halmstad University, Sweden.
    Uhlemann, Elisabeth
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Calafate, Carlos T.
    Universitat Politecnica de Valencia, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de Valencia, Spain.
    A Reliable and Efficient Token-Based MAC Protocol for Platooning Applications2016In: 12th Swedish National Computer Networking Workshop SNCNW 2016, 2016Conference paper (Refereed)
    Abstract [en]

    Platooning is both a challenging and rewarding application. Challenging since strict timing and reliability requirements are imposed by the distributed control system required to operate the platoon. Rewarding since considerable fuel reductions are possible. As platooning takes place in a vehicular ad hoc network, the use of IEEE 802.11p is close to mandatory. However, the 802.11p medium access method suffers from packet collisions and random delays. Most ongoing research suggests using TDMA on top of 802.11p as a potential remedy. However, TDMA requires synchronization and is not very flexible if the beacon frequency needs to be updated, the number of platoon members changes, or if retransmissions for increased reliability are required. We therefore suggest a token-passing medium access method where the next token holder is selected based on beacon data age. This has the advantage of allowing beacons to be re-broadcasted in each beacon interval whenever time and bandwidth are available. We show that our token-based method is able to reduce the data age and considerably increase reliability compared to pure 802.11p.

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  • 157.
    Balador, Ali
    et al.
    Polytechnic University of Valencia, Valencia, Spain.
    Böhm, Annette
    Halmstad Universit, Sweden.
    Uhlemann, Elisabeth
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Calafate, Carlos T.
    Polytechnic University of Valencia, Valencia, Spain.
    Ji, Yusheng
    National Institute of Informatics, Tokyo, Japan.
    Cano, Juan-Carlos
    Polytechnic University of Valencia, Valencia, Spain.
    Manzoni, Pietro
    Polytechnic University of Valencia, Valencia, Spain.
    An Efficient MAC Protocol for vehicle platooning in automated highway systems2015In: Jornadas Sarteco 2015 JS 2015, Cordoba, Spain, 2015Conference paper (Refereed)
    Abstract [en]

    Lately, all the top truck manufacturers are investing considerable resources in the research and development of platooning systems which would allow vehicles to save fuel and improve safety by travelling in a close-following manner. The platoon-ing system requires frequent and reliable vehicle-to-vehicle communications. As platooning takes place in a vehicular ad hoc network, the use of IEEE 802.11p is close to mandatory. However, the 802.11p medium access method suffers from packet collisions and random delays. Most ongoing research suggests using TDMA on top of 802.11p as a potential remedy. However , TDMA requires synchronization and is not very flexible if the beacon frequency needs to be updated, the number of platoon members changes, or if re-transmissions for increased reliability are required. We therefore suggest a token-passing medium access method where the next token holder is selected based on beacon data age. This has the advantage of allowing beacons to be re-broadcasted in each beacon interval whenever time and bandwidth are available. We show that our token-based method is able to reduce the data age and considerably increase reliability considerably compared to pure 802.11p.

  • 158.
    Balador, Ali
    et al.
    Universitat Politecnica de Valencia, Spain.
    Calafate, Carlos T.
    Universitat Politecnica de Valencia, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de Valencia, Spain.
    Manzoni, Pietro
    Universitat Politecnica de Valencia, Spain.
    A Density-Based Contention Window Control Scheme for Unicast Communications in Vehicular Ad Hoc Networks2015In: International Journal of Ad Hoc and Ubiquitous Computing, ISSN 1743-8225, E-ISSN 1743-8233, Vol. 24, p. 65-75Article in journal (Refereed)
    Abstract [en]

    Achieving a well-designed medium access control MAC protocol is a challenging issue to improve communications efficiency due to the dynamic nature of vehicular ad hoc networks VANETs. IEEE 802.11p standard was selected as the best choice for vehicular environments considering its availability, maturity, and cost. The common problem in all IEEE 802.11 based protocols is scalability, exhibiting performance degradation in highly variable network scenarios. Experimental results for the IEEE 802.11-based MAC protocol show the importance of contention window adjustment on communications performance; however the vehicular communications community has not yet addressed this issue in unicast communication environments. This paper proposes a novel contention window control scheme for VANET environments based on estimating the network density, which is then used to dynamically adapt the CW size. Analysis and simulation results show that our proposal provides better overall performance compared with previous proposals, even in high network density scenarios.

  • 159. Balador, Ali
    et al.
    Calafate, Carlos T.
    Universitat Politecnica de Valencia, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de Valencia, Spain.
    Manzoni, Pietro
    Universitat Politecnica de Valencia, Spain.
    A Novel 802.11 Contention Window Control Scheme for Vehicular Environments2013In: Jornadas Sarteco 2013 JS 2013, 2013, p. 98-103Conference paper (Refereed)
    Abstract [en]

    Intelligent Transportation Systems (ITS) have attractive potential in order to decrease the ordi- nary traffic jams and avoid transportation disasters. Also, they are able to provide various infotainment services like browsing, reading e-mail or using social networks that makes a trip more interesting. In or- der to make it more efficient in real vehicular envi- ronments, achieving a well-designed Medium Access Control (MAC) protocol is a challenging issue due to the dynamic nature of VANETs, scalability issues, and the variety of application requirements. Differ- ent standardization organizations have selected IEEE 802.11 as the first choice for VANET environments considering its availability, maturity, and cost. The research results for IEEE 802.11 MAC protocol show the importance of contention window adjustment on the communications performance. The impact of ad- justing the contention window has been studied in MANETs, but the vehicular communication commu- nity has not yet addressed this issue thoroughly. This paper proposes e-HBCWC, a new contention window control scheme for VANET environments based on estimating the network condition. Analy- sis and simulation results using OMNeT++ in urban scenarios show that e-HBCWC clearly outperforms 802.11 DCF, even in very high network density, by increasing the packet delivery rate while decreasing the number of collisions and the end-to-end delay for unicast applications.

  • 160.
    Balador, Ali
    et al.
    Universitat Politecnica de Valencia, Spain.
    Calafate, Carlos T.
    Universitat Politecnica de Valencia, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de Valencia, Spain.
    Manzoni, Pietro
    Universitat Politecnica de Valencia, Spain.
    Congestion Control for Vehicular Environments by Adjusting IEEE 802.11 Contention Window Size2013In: 13th International Conference on Algorithms and Architectures for Parallel Processing ICA3PP-2013, 2013, p. 259-266Conference paper (Refereed)
    Abstract [en]

    Medium access control protocols should manage the highly dynamic nature of Vehicular Ad Hoc Networks (VANETs) and the variety of application requirements. Therefore, achieving a well-designed MAC protocol in VANETs is a challenging issue. The contention window is a critical element for handling medium access collisions in IEEE 802.11, and it highly affects the communications performance. This paper proposes a new contention window control scheme, called DBM-ACW, for VANET environments. Analysis and simulation results using OMNeT++ in urban scenarios show that DBM-ACW provides better overall performance compared with previous proposals, even with high network densities.

  • 161.
    Balador, Ali
    et al.
    Universitat Politecnica de Valencia, Spain.
    Calafate, Carlos T.
    Universitat Politecnica de Valencia, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de Valencia, Spain.
    Manzoni, Pietro
    Universitat Politecnica de Valencia, Spain.
    DTB-MAC: Dynamic Token-Based MAC Protocol for Reliable and Efficient Beacon Broadcasting in VANETs2016In: The 13th Annual IEEE Consumer Communications & Networking Conference CCNC 2016, 2016, p. 109-114Conference paper (Refereed)
    Abstract [en]

    Most applications developed for vehicular environments rely on broadcasting as the main mechanism to disseminate their messages. However, in IEEE 802.11p, which is the most widely accepted Medium Access Control (MAC) protocol for vehicular communications, all transmissions remain unacknowledged if broadcasting is used. Furthermore, safety message transmission requires a strict delay limit and a high reliability, which is an issue for random access MAC protocols like IEEE 802.11p. Therefore, transmission reliability becomes the most important issue for broadcast-based services in vehicular environments. In this paper, we propose a hybrid MAC protocol, referred as Dynamic Token-Based MAC Protocol (DTB-MAC). DTB-MAC uses both a token passing mechanism and a random access MAC protocol to prevent channel contention as much as possible, and to improve the reliability of safety message transmissions. Our proposed protocol tries to select the best neighbouring node as the next transmitter, and when it is not possible, or when it causes a high overhead, the random access MAC protocol is used instead. Based on simulation experiments, we show that the DTB-MAC protocol can achieve better performance compared with IEEE 802.11p in terms of channel utilization and beacon delivery ratio.

  • 162. Balador, Ali
    et al.
    Calafate, Carlos T.
    Universitat Politecnica de Valencia, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de Valencia, Spain.
    Manzoni, Pietro
    Performance Evaluation of Realistic Vehicular Networks: A MAC Layer Perspective2014In: Simulation Technologies in Networking and Communications: Selecting the Best Tool for the Test / [ed] Al-Sakib Khan Pathan, Muhammad Mostafa Monowar, Shafiullah Khan, CRC Press, Taylor & Francis Group , 2014Chapter in book (Other academic)
  • 163.
    Balador, Ali
    et al.
    Univ. Politec. de Valencia, Valencia, Spain.
    Calafate, Carlos T.
    Univ. Politec. de Valencia, Valencia, Spain.
    Cano, Juan-Carlos
    Univ. Politec. de Valencia, Valencia, Spain.
    Manzoni, Pietro
    Univ. Politec. de Valencia, Valencia, Spain.
    Reducing Channel Contention in Vehicular Environments Through an Adaptive Contention Window Solution2013In: IFIP Wireless Days WD 2013, 2013Conference paper (Refereed)
    Abstract [en]

    Intelligent Transportation Systems (ITS) are attracting growing attention both in industry and academia due to the advances in wireless communication technologies, and a significant demand for a wide variety of applications targeting this kind of environments are expected. In order to make it usable in real vehicular environments, achieving a well-designed Medium Access Control (MAC) protocol is a challenging issue due to the dynamic nature of Vehicular Ad Hoc Networks (VANETs), scalability issues, and the variety of application requirements. Different standardization organizations have selected IEEE 802.11 as the first choice for VANET environments considering its availability, maturity, and cost. The contention window is a critical parameter for handling medium access collisions by the IEEE 802.11 MAC protocol, and it highly affects the communications performance. The impact of adjusting the contention window has been studied in Mobile Ad-Hoc Networks (MANETs), but the vehicular communications community has not yet addressed this issue thoroughly. This paper proposes a new contention window control scheme, called DBM-ACW, for VANET environments. Analysis and simulation results using OMNeT++ in a highway scenario show that DBM-ACW provides better overall performance compared with previous proposals, even with high network densities.

  • 164.
    Balador, Ali
    et al.
    RISE SICS Västerås, Sweden.
    Ericsson, Niclas
    RISE SICS Västerås, Sweden.
    Bakhshi, Zeynab
    RighTel, Iran.
    Communication Middleware Technologies for Industrial Distributed Control Systems: A Literature Review2018In: International Conference on Emerging Technologies And Factory Automation ETFA'17, 2018Conference paper (Refereed)
    Abstract [en]

    Industry 4.0 is the German vision for the future of manufacturing, where smart factories use information and communication technologies to digitise their processes to achieve improved quality, lower costs, and increased efficiency. It is likely to bring a massive change to the way control systems function today. Future distributed control systems are expected to have an increased connectivity to the Internet, in order to capitalize on new offers and research findings related to digitalization, such as cloud, big data, and machine learning. A key technology in the realization of distributed control systems is middleware, which is usually described as a reusable software layer between operating system and distributed applications. Various middleware technologies have been proposed to facilitate communication in industrial control systems and hide the heterogeneity amongst the subsystems, such as OPC UA, DDS, and RT-CORBA. These technologies can significantly simplify the system design and integration of devices despite their heterogeneity. However, each of these technologies has its own characteristics that may work better for particular applications. Selection of the best middleware for a specific application is a critical issue for system designers. In this paper, we conduct a survey on available standard middleware technologies, including OPC UA, DDS, and RT-CORBA, and show new trends for different industrial domains.

  • 165.
    Balador, Ali
    et al.
    Islamic Azad University, Tehran, Iran.
    Movaghar, Ali
    Sharif University of Technology, Tehran, Iran.
    Jabbehdari, Sam
    North Tehran Branch, Islamic Azad University, Tehran, Iran.
    History Based Contention Window Control (HBCWC) in IEEE 802.11 Mac Protocol in Error Prone Channel2010In: Journal of Computer Science, ISSN 1549-3636, E-ISSN 1552-6607, Vol. 6, no 2, p. 205-209Article in journal (Refereed)
    Abstract [en]

    Problem statement: IEEE 802.11 Medium Access Control (MAC) protocol is one of the most implemented protocols in this network. The IEEE 802.11 controls the access to the share wireless channel within competing stations. The IEEE 802.11 DCF doubles the Contention Window (CW) size for decreasing the collision within contending stations and to improve the network performances but it is not good for error prone channel because the sudden CW rest to CWmin may cause several collisions. Approach: The research to date has tended to focus on the current number of active stations that needs complex computations. A novel backoff algorithm is presented that optimizes the CW size with take into account the history of packet lost. Results: Finally, we compare the HBCWC with IEEE 802.11 DCF. The simulation results have shown 24.14, 56.71 and 25.33% improvement in Packet Delivery Ratio (PDR), average end to end delay and throughput compared to the IEEE 802.11 DCF. Conclusion: This study showed that monitoring the last three channel statuses achieve better delay and throughput that can be used for multimedia communications.

  • 166.
    Balador, Ali
    et al.
    Universitat Pompeu Fabra, Barcelona, Spain.
    Movaghar, Ali
    Sharif University of Technology, Tehran, Iran.
    Jabbehdari, Sam
    North Tehran Branch, Islamic Azad University, Tehran, Iran.
    Kanellopoulos, Dimitris
    University of Patras, Greece.
    A novel contention window control scheme for IEEE 802.11 WLANs2012In: IETE Technical Review, ISSN 0256-4602, E-ISSN 0974-5971, Vol. 30, no 4, p. 202-212Article in journal (Refereed)
    Abstract [en]

    In the IEEE 802.11 standard, network nodes experiencing collisions on the shared medium need a mechanism that can prevent collisions and improve the throughput. Furthermore, a backoff mechanism is used that uniformly selects a random period of time from the contention window (cw) that is dynamically controlled by the Binary Exponential Backoff (BEB) algorithm. Prior research has proved that the BEB scheme suffers from a fairness problem and low throughput, especially under high traffic load. In this paper, we present a new backoff control mechanism that is used with the IEEE 802.11 distributed coordination function (DCF). In particular, we propose a dynamic, deterministic contention window control (DDCWC) scheme, in which the backoff range is divided into several small backoff sub-ranges. In the proposed scheme, several network levels are introduced, based on an introduced channel state vector that keeps network history. After successful transmissions and collisions, network nodes change their cw based on their network levels. Our extensive simulation studies show that the DDCWC scheme outperforms four other well-known schemes: Multiplicative Increase and Linear Decrease, Double Increment Double Decrement, Exponential Increase Exponential Decrease, and Linear/Multiplicative Increase and Linear Decrease. Moreover, the proposed scheme, compared with the IEEE 802.11 DCF, gives 30.77% improvement in packet delivery ratio, 31.76% in delay, and 30.81% in throughput.

  • 167.
    Balasubramanian, S. M. N.
    et al.
    Technische Universiteit Eindhoven, Eindhoven, Netherlands.
    Afshar, Sara
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Gai, P.
    Evidence Srl, Pisa, Italy.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    J. Bril, Reinder
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Practical challenges for FSLM2018In: Proceedings - 2018 IEEE 24th International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2018, Institute of Electrical and Electronics Engineers Inc. , 2018, p. 238-239, article id 8607257Conference paper (Refereed)
    Abstract [en]

    The flexible spin-lock model (FSLM) unifies suspension-based and spin-based resource access protocols for partitioned fixed-priority preemptive scheduling based real-time multi-core platforms. Recent work has been done in defining the protocol for FSLM, providing schedulability analysis, and investigating the practical consequences of the theoretical model. FSLM complies to the AUTOSAR standard for the automotive industry, and prototype implementations of FSLM in the OSEK/VDX-complaint Erika Enterprise Real-Time Operating System have been realized. In this paper, we briefly describe some practical challenges to improve efficiency and generality. 

  • 168.
    Balasubramanian, S.M.N
    et al.
    Technische Universiteit Eindhoven, Eindhoven, The Netherlands.
    Afshar, Sara Zargari
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Gai, Paolo
    Evidence Srl, Pisa, Italy.
    Bril, Reinder J.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. Technische Universiteit Eindhoven, Eindhoven, The Netherlands.
    A dual shared stack for FSLM in Erika enterprise2017In: The 23rd IEEE International Conference on Embedded and Real-Time Computing Systems and Applications - WiP Session RTCSA'17, 2017Conference paper (Refereed)
    Abstract [en]

    Recently, the flexible spin-lock model (FSLM) has been introduced, unifying spin-based and suspension-based resource sharing protocols for real-time multi-core platforms. Unlike the multiprocessor stack resource policy (MSRP), FSLM doesn’t allow tasks on a core to share a single stack, however. In this paper, we present a hypothesis claiming that for a restricted range of spin-lock priorities, FSLM requires only two stacks. We briefly describe our implementation of a dual stack for FSLM in the Erika Enterprise RTOS as instantiated on an Altera Nios II platform using 4 soft-core processors.

  • 169.
    Balasubramanian, S.M.N
    et al.
    Tech Univ Eindhoven, Eindhoven, Netherlands.
    Afshar, Sara Zargari
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Gai, Paolo
    Evidence Srl, Pisa, Italy.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    J. Bril, Reinder
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. Tech Univ Eindhoven, Eindhoven, Netherlands.
    Incorporating implementation overheads in the analysis for the flexible spin-lock model2017In: IECON 2017 - 43RD ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY, 2017, p. 411-8418Conference paper (Refereed)
    Abstract [en]

    The flexible spin-lock model (FSLM) unifies suspension-based and spin-based resource sharing protocols for partitioned fixed-priority preemptive scheduling based real-time multiprocessor platforms. Recent work has been done in defining the protocol for FSLM and providing a schedulability analysis without accounting for the implementation overheads. In this paper, we extend the analysis for FSLM with implementation overheads. Utilizing an initial implementation of FSLM in the OSEK/VDX-compliant Erika Enterprise RTOS on an Altera Nios II platform using 4 soft-core processors, we present an improved implementation. Given the design of the implementation, the overheads are characterized and incorporated in specific terms of the existing analysis. The paper also supplements the analysis with measurement results, enabling an analytical comparison of FSLM with the natively provided multiprocessor stack resource policy (MSRP), which may serve as a guideline for the choice of FSLM or MSRP for a specific application.

  • 170.
    Balatinac, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Radosevic, Iva
    Mälardalen University, School of Innovation, Design and Engineering.
    Architecting for the cloud2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Cloud Computing is an emerging new computing paradigm which is developed out of service-orientation, grid computing, parallel computing, utility computing, autonomic computing, and virtualization paradigms. Both industry and academia have experienced its rapid growth and are exploring full usage of its potentials to maintain their services provided to customers and partners. In this context, a key aspect to investigate is how to architect or design cloud-based application that meet various system requirements of customers’ needs. In this thesis, we have applied the systematic literature review method to explore the main concerns when architecting for the cloud. We have identified, classified, and extracted existing approaches and solutions for specific concerns based on the existing research articles that focus on planning and providing cloud architecture or design for different concerns and needs. The main contribution of the thesis is a catalogued architecture solutions for managing specific concerns when architecting for the cloud.

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    Architecting for the cloud
  • 171.
    Ballesteros, Joaquin
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Tudela, Alberto J.
    University of Malaga, Malaga, Spain.
    Caro-Romero, J. R.
    University of Malaga, Malaga, Spain.
    Urdiales, C.
    University of Malaga, Malaga, Spain.
    Weight-Bearing Estimation for Cane Users by Using Onboard Sensors2019In: Sensors, E-ISSN 1424-8220, Vol. 19, no 3Article in journal (Refereed)
    Abstract [en]

    Mobility is a fundamental requirement for a healthy, active lifestyle. Gait analysis is widely acknowledged as a clinically useful tool for identifying problems with mobility, as identifying abnormalities within the gait profile is essential to correct them via training, drugs, or surgical intervention. However, continuous gait analysis is difficult to achieve due to technical limitations, namely the need for specific hardware and constraints on time and test environment to acquire reliable data. Wearables may provide a solution if users carry them most of the time they are walking. We propose to add sensors to walking canes to assess user's mobility. Canes are frequently used by people who cannot completely support their own weight due to pain or balance issues. Furthermore, in absence of neurological disorders, the load on the cane is correlated with the user condition. Sensorized canes already exist, but often rely on expensive sensors and major device modifications are required. Thus, the number of potential users is severely limited. In this work, we propose an affordable module for load monitoring so that it can be widely used as a screening tool. The main advantages of our module are: (i) it can be deployed in any standard cane with minimal changes that do not affect ergonomics; (ii) it can be used every day, anywhere for long-term monitoring. We have validated our prototype with 10 different elderly volunteers that required a cane to walk, either for balance or partial weight bearing. Volunteers were asked to complete a 10 m test and, then, to move freely for an extra minute. The load peaks on the cane, corresponding to maximum support instants during the gait cycle, were measured while they moved. For validation, we calculated their gait speed using a chronometer during the 10 m test, as it is reportedly related to their condition. The correlation between speed (condition) and load results proves that our module provides meaningful information for screening. In conclusion, our module monitors support in a continuous, unsupervised, nonintrusive way during users' daily routines, plus only mechanical adjustment (cane height) is needed to change from one user to another.

  • 172.
    Bankarusamy, Sudhangathan
    Mälardalen University, School of Innovation, Design and Engineering.
    Towards hardware accelerated rectification of high speed stereo image streams2017Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    The process of combining two views of a scene in order to obtain depth information is called stereo vision. When the same is done using a computer it is then called computer stereo vision. Stereo vision is used in robotic application where depth of an object plays a role. Two cameras mounted on a rig is called a stereo camera system. Such a system is able to capture two views and enable robotic application to use the depth information to complete tasks. Anomalies are bound to occur in such a stereo rig, when both the cameras are not parallel to each other. Mounting of the cameras on a rig accurately has physical alignment limitations. Images taken from such a rig has inaccurate depth information and has to be rectified. Therefore rectification is a pre-requisite to computer stereo vision. One such a stereo rig used in this thesis is the GIMME2 stereo camera system. The system has two 10 mega-pixel cameras with on-board FPGA, RAM, processor running Linux operating system, multiple Ethernet ports and an SD card feature amongst others. Stereo rectification on memory constrained hardware is a challenging task as the process itself requires both the images to be stored in the memory. The FPGA on the GIMME2 systems must be used in order to achieve the best possible speed. Programming a system that does not have a display and for used for a specific purpose is called embedded programming. The purpose of this system is distance estimation and working with such a system falls in the Embedded Systems program. This thesis presents a method that makes rectification a step ahead for this particular system. The functionality of the algorithm is shown in MATLAB and using VHDL and is compared to available tools and systems.

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  • 173.
    Barkah, Dani
    et al.
    Volvo Construction Equipment AB, Eskilstuna, Sweden.
    Ermedahl, Andreas
    Mälardalen University, Department of Computer Science and Electronics.
    Gustafsson, Jan
    Mälardalen University, Department of Computer Science and Electronics.
    Lisper, Björn
    Mälardalen University, Department of Computer Science and Electronics.
    Sandberg, Christer
    Mälardalen University, Department of Computer Science and Electronics.
    Evaluation of Automatic Flow Analysis for WCET Calculation on Industrial Real-Time System Code2008In: Proceedings - Euromicro Conference on Real-Time Systems, 2008, 2008, p. 331-340Conference paper (Refereed)
    Abstract [en]

    A static Worst-Case Execution Time (WCET) analysis derives upper bounds for the execution times of programs. Such analysts requires information about the possible program flows. The current practice is to provide this information manually, which can be laborious and error-prone. An alternative is to derive this information through an automated flow analysis. In this article, we present a case study where an automatic flowanalysis method was tested on industrial real-time system code. The same code was the subject of an earlier WCET case study, where it was analysed using manual annotations for the flow information. The purpose of the current study was to see to which extent the same flow information could be found automatically. The results show that for the most part this is indeed possible, and we could derive comparable WCET estimates using the automatically generated flow information. In addition, valuable insights were gained on what is needed to make flow analysis methods work on real production code. 

  • 174.
    Barua, Shaibal
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahmed, Mobyen Uddin
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Begum, Shahina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Classifying drivers' cognitive load using EEG signals2017In: Studies in Health Technology and Informatics, ISSN 0926-9630, E-ISSN 1879-8365, Vol. 237, p. 99-106Article in journal (Refereed)
    Abstract [en]

    A growing traffic safety issue is the effect of cognitive loading activities on traffic safety and driving performance. To monitor drivers' mental state, understanding cognitive load is important since while driving, performing cognitively loading secondary tasks, for example talking on the phone, can affect the performance in the primary task, i.e. driving. Electroencephalography (EEG) is one of the reliable measures of cognitive load that can detect the changes in instantaneous load and effect of cognitively loading secondary task. In this driving simulator study, 1-back task is carried out while the driver performs three different simulated driving scenarios. This paper presents an EEG based approach to classify a drivers' level of cognitive load using Case-Based Reasoning (CBR). The results show that for each individual scenario as well as using data combined from the different scenarios, CBR based system achieved approximately over 70% of classification accuracy. 

  • 175.
    Barua, Shaibal
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahmed, Mobyen Uddin
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Begum, Shahina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Drivers' Sleepiness Classification using Machine Learning with Physiological and Contextual data2019In: First International Conference on Advances in Signal Processing and Artificial Intelligence ASPAI' 2019, 2019Conference paper (Refereed)
    Abstract [en]

    Analysing physiological parameters together with contextual information of car drivers to identify drivers’ sleepiness is a challenging issue. Machine learning algorithms show high potential in data analysis and classification tasks in many domains. This paper presents a use case of machine learning approach for drivers’ sleepiness classification. The classifications are conducted based on drivers’ physiological parameters and contextual information. The sleepiness classification shows receiver operating characteristic (ROC) curves for KNN, SVM and RF were 0.98 on 10-fold cross-validation and 0.93 for leave-one-out (LOO) for all classifiers.

  • 176.
    Barua, Shaibal
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahmed, Mobyen Uddin
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Begum, Shahina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Towards Intelligent Data Analytics: A Case Study in Driver Cognitive Load Classification2020In: Brain Sciences, ISSN 2076-3425, E-ISSN 2076-3425, Vol. 10, no 8, article id 526Article in journal (Refereed)
    Abstract [en]

    One debatable issue in traffic safety research is that cognitive load by secondary tasks reduces primary task performance, i.e., driving. In this paper, the study adopted a version of the n-back task as a cognitively loading secondary task on the primary task i.e., driving; where drivers drove in three different simulated driving scenarios. This paper has taken a multimodal approach to perform ‘intelligent multivariate data analytics’ based on machine learning (ML). Here, k-nearest neighbour (k-NN), support vector machine (SVM) and random forest (RF) are used for driver cognitive load classification. Moreover, physiological measures have proven to be sophisticated in cognitive load identification, yet it suffers from confounding factors and noise. Therefore, this work uses multi-component signals, i.e., physiological measures and vehicular features to overcome that problem. Both multiclass and binary classifications have been performed to distinguish normal driving from cognitive load tasks. To identify the optimal feature set, two feature selection algorithms, i.e., Sequential Forward Floating Selection (SFFS) and Random Forest have been applied where out of 323 features, a sub-set of 42 features has been selected as the best feature subset. For the classification, the RF has shown better performance with F1-score of 0.75 and 0.80 than two other algorithms. Also, the result shows that using multicomponent features classifiers could classify better than using features from a single source.

  • 177.
    Barua, Shaibal
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Begum, Shahina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahmed, Mobyen Uddin
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Clustering based Approach for Automated EEG Artifacts Handling2015In: Frontiers in Artificial Intelligence and Applications, vol. 278, 2015, p. 7-16Conference paper (Refereed)
    Abstract [en]

    Electroencephalogram (EEG), measures the neural activity of the central nervous system, which is widely used in diagnosing brain activity and therefore plays a vital role in clinical and Brain-Computer Interface application. However, analysis of EEG signal is often complex since the signal recoding often contaminates with noises or artifacts such as ocular and muscle artifacts, which could mislead the diagnosis result. Therefore, to identify the artifacts from the EEG signal and handle it in a proper way is becoming an important and interesting research area. This paper presents an automated EEG artifacts handling approach, where it combines Independent Component Analysis (ICA) with a 2nd order clustering approach. Here, the 2nd order clustering approach combines the Hierarchical and Gaussian Picture Model clustering algorithm. The effectiveness of the proposed approach has been examined and observed on real EEG recording. According to result, the artifacts in the EEG signals are identified and removed successfully where the clean EEG signal shows acceptable considering visual inspection.

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  • 178.
    Barua, Shaibal
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Begum, Shahina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahmed, Mobyen Uddin
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Intelligent Automated EEG Artifacts Handling Using Wavelet Transform, Independent Component Analysis and Hierarchical clustering2015Conference paper (Refereed)
    Abstract [en]

    Billions of interconnected neurons are the building block of human brain. For each brain activity these neurons produce electrical signals or brain waves that can be obtained by the Electroencephalogram (EEG) recording. Due to the characteristics of EEG signal, recorded signal often contaminate with undesired physiological signals other than cerebral signal that refers to as EEG artifacts such as ocular or muscle artifacts. Therefore, identification of artifacts from the EEG signal and handle it in a proper way is becoming an important research area. This paper presents an automated EEG artifacts handling approach, where it combines Wavelet transform, Independent Component Analysis (ICA) with Hierarchical clustering method. The effectiveness of the proposed approach has been examined and observed on real EEG recording. According to result, the artifacts in the EEG signals are identified and removed successfully where after handling artifacts EEG signals show acceptable considering visual inspection.

  • 179.
    Barua, Shaibal
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Begum, Shahina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahmed, Mobyen Uddin
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Scalable Framework for Distributed Case-based Reasoning for Big data analytics2018In: Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST, Volume 225, 2018, p. 111-114Conference paper (Refereed)
    Abstract [en]

    This paper proposes a scalable framework for distributed case-based reasoning methodology to provide actionable knowledge based on historical big amount of data. The framework addresses several challenges, i.e., promptly analyse big data, cross-domain, use-case specific data processing, multi-source case representation, dynamic case-management, uncertainty, check the plausibility of solution after adaptation etc. through its’ five modules architectures. The architecture allows the functionalities with distributed data analytics and intended to provide solutions under different conditions, i.e. data size, velocity, variety etc.

  • 180.
    Barua, Shaibal
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Begum, Shahina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahmed, Mobyen Uddin
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Supervised Machine Learning Algorithms to Diagnose Stress for Vehicle Drivers Based on Physiological Sensor Signals2015In: Studies in Health Technology and Informatics, Volume 211: Proceedings of the 12th International Conference on Wearable Micro and Nano Technologies for Personalized Health, 2–4 June 2015, Västerås, Sweden, 2015, Vol. 211, p. 241-248Conference paper (Refereed)
    Abstract [en]

    Machine learning algorithms play an important role in computer science research. Recent advancement in sensor data collection in clinical sciences lead to a complex, heterogeneous data processing and analysis for patient diagnosis and prognosis. Diagnosis and treatment of patients based on manual analysis of these sensor data is difficult and time consuming. Therefore, development of Knowledge-based systems to support clinicians in decision-making is important. However, it is necessary to perform experimental work to compare performances of different machine learning methods to help to select appropriate method for a specific characteristic of data sets. This paper compares classification performance of three popular machine learning methods i.e., case-based reasoning, neutral networks and support vector machine to diagnose stress of vehicle drivers using finger temperature and heart rate variability. The experimental results show that case-based reasoning outperforms other two methods in terms of classification accuracy. Case-based reasoning has achieved 80% and 86% accuracy to classify stress using finger temperature and heart rate variability. On contrary, both neural network and support vector machine have achieved less than 80% accuracy by using both physiological signals.

  • 181.
    Barua, Shaibal
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Begum, Shahina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahmed, Mobyen Uddin
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Towards Distributed k-NN similarity for Scalable Case Retrieval2018In: ICCBR 2018: The 26th International Conference on Case-Based Reasoning July, 09th-12th 2018 in Stockholm, Sweden, Workshop Proceedings, 2018, p. 151-160Conference paper (Refereed)
    Abstract [en]

    In Big data era, the demand of processing large amount of data posing several challenges. One biggest challenge is that it is no longer possible to process the data in a single machine. Similar challenges can be assumed for case-based reasoning (CBR) approach, where the size of a case library is increasing and constructed using heterogenous data sources. To deal with the challenges of big data in CBR, a distributed CBR system can be developed, where case libraries or cases are distributed over clusters. MapReduce programming framework has the facilities of parallel processing massive amount of data through a distributed system. This paper proposes a scalable case-representation and retrieval approach using distributed k-NN similarity. The proposed approach is considered to be developed using MapReduce programming framework, where cases are distributed in many clusters.

  • 182.
    Barua, Shaibal
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Begum, Shahina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahmed, Mobyen Uddin
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahlström, Christer
    The Swedish National Road and Transport Research Institute (VTI), Sweden.
    AUTOMATED EEG ARTIFACTS HANDLING FOR DRIVER SLEEPINESS MONITORING2016In: 2nd International Symposium on Somnolence, Vigilance, and Safety SomnoSafe2016, 2016Conference paper (Refereed)
  • 183.
    Barzegaran, Mohammadreza
    et al.
    Technical University of Denmark, Dtu Compute, Kongens Lyngby, Denmark.
    Desai, Nitin
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Qian, Jia
    Technical University of Denmark, Dtu Compute, Kongens Lyngby, Denmark.
    Tange, Koen
    Technical University of Denmark, Dtu Compute, Kongens Lyngby, Denmark.
    Zarrin, Bahram
    Technical University of Denmark, Dtu Compute, Kongens Lyngby, Denmark.
    Pop, Paul
    Technical University of Denmark, Dtu Compute, Kongens Lyngby, Denmark.
    Kuusela, Juha
    Danfoss Power Electronics A/S, Gråsten, Denmark.
    Fogification of Electric Drives: An industrial use case2020In: The 25th International Conference on Emerging Technologies and Factory Automation ETFA2020, 2020Conference paper (Refereed)
    Abstract [en]

    Electric drives are used to control electric motors, which are pervasive in industrial applications. In this paper we propose enhancing the electric drives to fulfil the role of fog nodes within a Fog Computing Platform (FCP). Fog Computing is envisioned as a realization of future distributed architectures in Industry 4.0. We identify the system-level requirements of such an FCP, including requirements that are extracted from the current architecture of drives, which we consider as a baseline. These requirements are then used to design a system-level architecture, which we model using the Architecture Analysis & Design Language (AADL). We identify the “technology bricks” (components such as hardware, software, middleware, services, methods and tools) needed to implement the FCP. The proposed fog-based architecture is then used to implement a Conveyor Belt industrial use case. We evaluate the resulting use case on several aspects, demonstrating the usefulness of the proposed fogbased approach. By developing the electric drives as fog nodes, new offerings like programmability, analytics and connectivity to customer Clouds are expected to increase the added value. Increased flexibility allows drives to assume a larger role in industrial and domestic control systems, instrumenting thus also legacy systems by using drives as the data source.

  • 184.
    Bashir, Shariq
    et al.
    Mohammad Ali Jinnah University, Islamabad, Pakistan.
    Afzal, Wasif
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Baig, Rauf
    Al Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia.
    Opinion-based entity ranking using learning to rank2016In: Applied Soft Computing, ISSN 1568-4946, E-ISSN 1872-9681, Vol. 38, no 1, p. 151-163Article in journal (Refereed)
    Abstract [en]

    As social media and e-commerce on the Internet continue to grow, opinions have become one of the most important sources of information for users to base their future decisions on. Unfortunately, the large quantities of opinions make it difficult for an individual to comprehend and evaluate them all in a reasonable amount of time. The users have to read a large number of opinions of different entities before making any decision. Recently a new retrieval task in information retrieval known as Opinion-Based Entity Ranking (OpER) has emerged. OpER directly ranks relevantentities based on how well opinions on them are matched with a user's preferences that are given in the form of queries. With such a capability, users do not need to read a large number of opinions available for the entities. Previous research on OpER does not take into account the importance and subjectivity of query keywords in individual opinions of an entity. Entity relevance scores are computed primarily on the basis of occurrences of query keywords match, by assuming all opinions of an entity as a single field of text. Intuitively, entities that have positive judgments and strong relevance with query keywords should be ranked higher than those entities that have poor relevance and negative judgments. This paper outlines several ranking features and develops an intuitive framework for OpER in which entities are ranked according to how well individual opinions of entities are matched with the user's query keywords. As a useful ranking model may be constructed from many rankingfeatures, we apply learning to rank approach based on genetic programming (GP) to combine features in order to develop an effective retrieval model for OpER task. The proposed approach is evaluated on two collections and is found to be significantly more effective than the standard OpER approach.

  • 185.
    Baumgart, Stephan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Safety Analysis of Systems-of-Systems2022Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Safety-critical systems may fail dangerously with severe consequences to the health of the involved humans, costly equipment, the environment, or other valuable assets of a stakeholder. For these classes of systems, the developers are obliged to analyze each potentially hazardous situation thoroughly. In addition, any identified hazardous situation needs to be considered for risk reduction measures, including adjustments of the system's design, additional safeguards if the hazards cannot entirely be removed by design, or warning information to users.  

    An essential activity in the development process is the safety analysis, where hazards related to the system under development are identified, and the risks are evaluated and classified. This classification stipulates the rigor of complying with safety standard requirements and directing the development and verification activities. Several techniques for safety analysis have been identified in the literature and are applied in industrial development processes.

    The technical evolution enables moving from developing single systems with specific features towards attaching several independent systems to a system-of-systems.On top of the trend towards connectedness, there is also a trend towards more and more automation. In the vehicle domain, autonomous vehicles can collaborate to achieve specific goals, like transporting goods in warehouses, transporting containers in automated ports, or transporting material in off-road environments.

    Autonomy brings in new challenges when ensuring product safety and functional safety for single systems due to the lack of a human operator as a fallback solution.Further, when autonomous vehicles collaborate in a fleet, the safety analysis becomes more complex since their interaction and interoperability bring forth new hazards not identifiable with a safety analysis of a single system. Our research aims to bridge this gap and provide solutions for specifying a system-of-systems and finding and developing suitable safety analysis methods.

    To understand the challenges and current practices, we have studied industrial projects where systems-of-systems are developed. We have applied safety analysis methods to our industrial cases and found limitations of finding hazards related to a system-of-systems. As part of our research, we have developed extensions to the safety analysis methods to support the analysis of a system-of-systems. We have developed the Safe System-of-Systems (SafeSoS) method which is a structured and hierarchical process to discover and document a system-of-systems characteristics on three primary abstraction levels. Additionally, we utilize model-based formalism to describe the System-of-Systems’ characteristics on each level. Our research results support engineers in the industry when designing a safety-critical system-of-systems.

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  • 186.
    Baumgart, Stephan
    et al.
    Volvo Autonomous Solut, Eskilstuna, Sweden..
    Chen, Yin
    ABB, Vasteras, Sweden..
    Hamren, Rasmus
    Nordic Elect Partner, Vasteras, Sweden..
    Punnekkat, Sasikumar
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    A Model-Based Approach to Document Software Toolchains for Supporting a Safety Analysis2021In: 2021 15TH ANNUAL IEEE INTERNATIONAL SYSTEMS CONFERENCE (SYSCON 2021), IEEE , 2021Conference paper (Refereed)
    Abstract [en]

    The increasing use of embedded systems to provide new functionality and customer experience requires developing the embedded systems carefully. As a new challenge, autonomous systems are developed to be working in a fleet to provide production workflows. Developing such a system-of-systems requires utilizing various software tools to manage the complexity. One task in developing safety-critical products, in general, is to analyze if the applied tools can introduce failures into the final product. Today's functional safety standards consider only single software tools for analysis. In our industrial work, we can observe a trend towards supporting product lines. A common configurable platform is developed to support a range of different products. Developing such a platform and supporting variability, a toolchain is created where software tools are glued together using scripts to support product lines and automatically generate compiled code. The current functional safety standards do not straight forward support this. This paper discusses how software tools need to support functional safety and show limitations by providing an industrial case. We provide a model-based approach to describe a toolchain and show its application to an industrial case. To analyze potential failures in the toolchain, we utilize the HAZOP method and show its application.

  • 187.
    Baumgart, Stephan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Fröberg, Joakim
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. SICS Swedish ICT, Sweden.
    Punnekkat, Sasikumar
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    A Process to Support Safety Analysis for a System-of-Systems2020In: 31st International Symposium on Software Reliability Engineering ISSRE 2020, Coimbra, Portugal, 2020Conference paper (Refereed)
    Abstract [en]

    Autonomous vehicles grow importance in many domains and depending on the domain and user needs, autonomous vehicles can be designed as stand-alone solutions as in the automotive domain or as part of a fleet with a specific purpose as in the earth moving machinery domain. Contemporary hazard analysis methods primarily focus on analyzing hazards for single systems. Such an analysis requires knowledge about typical usage of a product, and it is evaluated among others if an operator is able to handle a critical situation. Each hazard analysis method requires specific information as input in order to conduct the method. However, for system-of-systems it is not yet clear how to analyze hazards and provide the required information. In this paper we describe a use case from the earth moving machinery domain where autonomous machines collaborate as a system-of-systems to achieve the mission. We propose a hierarchical process to document a system-of-systems and propose the use of model-based development methods. In this work we discuss how to utilize the provided details in a hazard analysis. Our approach helps to design a complex system-of-systems and supports hazard analysis in a more effective and efficient manner.

  • 188.
    Baumgart, Stephan
    et al.
    Volvo Construction Equipment, Eskilstuna, Sweden.
    Fröberg, Joakim
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. RISE ICT/SICS Västerås, Sweden.
    Punnekkat, Sasikumar
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    A State-based Extension to STPA for Safety-Critical System-of-Systems2019In: 4th International Conference on System Reliability and Safety ICSRS-2019, 2019, p. 246-254Conference paper (Refereed)
    Abstract [en]

    Automation of earth moving machinery enables improving existing production workflows in various applications like surface mines, material handling operations or material transporting. Such connected and collaborating autonomous machines can be seen as a system-of-systems. It is not yet clear how to consider safety during the development of such systemof- systems (SoS). One potentially useful approach to analyze the safety for complex systems is the System Theoretic Process Analysis (STPA). However, STPA is essentially suitable to static monolithic systems and lacks the ability to deal with emergent and dysfunctional behaviors in the case of SoS. These behaviors if not identified could potentially lead to hazards and it is important to provide mechanisms for SoS developers/integrators to capture such critical situations. In this paper, we present an approach for enriching STPA to provide the ability to check whether the distributed constituent systems of a SoS have a consistent perspective of the global state which is necessary to ensure safety. In other words, these checks must be capable at least to identify and highlight inconsistencies that can lead to critical situations. We describe the above approach by taking a specific case of state change related issues that could potentially be missed by STPA by looking at an industrial case. By applying Petri nets, we show that possible critical situations related to state changes are not identified by STPA. In this context we also propose a modelbased extension to STPA and show how our new process could function in tandem with STPA.

  • 189.
    Baumgart, Stephan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Fröberg, Joakim
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Punnekkat, Sasikumar
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    A Structured Safety Analysis Process for Systems-of-Systems (SafeSoS)2022Manuscript (preprint) (Other academic)
    Abstract [en]

    Automation is gaining importance in many domains, such as vehicle platoons, smart manufacturing, smart cities, and defense applications. However, the automated system must guarantee safe operation in any critical situation without humans in the loop as a fall-back solution. Additionally, autonomy can cause new types of hazards that need to be identified and analyzed.This paper studies cases from the transportation domain where autonomous vehicles are integrated into workflows in an open-surface mine for efficient material  transportation. In this application many individual systems collaborate to form a system-of-system (SoS) to achieve the mission goals. The complexity of such an SoSand the dependencies between the constituent systems complicate the safety analysis. In an SoS there exist several causes leading to new emergent hazards, failure of identification of which could lead to catastrophes.

    In this paper, we describe an SoS-centric process called 'SafeSoS', capable of identifying emergent hazards, through  structuring the complex characteristics of an SoS  on three hierarchical levels to enable better comprehension and analysis. We describe the process in detail and apply the process to an industrial transportation system from the earth-moving machinery domain.As part of the SafeSoS process, we utilize model-based formalisms to describe the characteristics of the application and the constituent systems, which form the input for analyzing the safety of the resulting SoS.We apply the safety analysis methods HiSoS, SMM, FTA, FMEA and Hazop to the industrial SoS with the purpose to identify emergent hazards. As a result of our work, we show how to identify and analyze emergent hazards by the help of our SafeSoS approach. 

  • 190.
    Baumgart, Stephan
    et al.
    Volvo Construction Equipment, Eskilstuna, Sweden.
    Fröberg, Joakim
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. RISE ICT/SICS Västerås, Sweden.
    Punnekkat, Sasikumar
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Can STPA be used for a System-of-Systems? Experiences from an Automated Quarry Site2018In: 4th IEEE International Symposium on Systems Engineering, ISSE 2018 - Proceedings, 2018, no 4, article id 8544433Conference paper (Refereed)
    Abstract [en]

    Automation is becoming prevalent in more and more industrial domains due to the potential benefits in cost reduction as well as the new approaches/solutions they enable. When machines are automated and utilized in system-of-systems, a thorough analysis of potential critical scenarios is necessary to derive appropriate design solutions that are safe as well. Hazard analysis methods like PHA, FTA or FMEA help to identify and follow up potential risks for the machine operators or bystanders and are well-established in the development process for safety critical machinery. However, safety certified individual machines can no way guarantee safety in the context of system-of-systems since their integration and interactions could bring forth newer hazards. Hence it is paramount to understand the application sce- narios of the system-of-systems and to apply a structured method to identify all potential hazards. In this paper, we 1) provide an overview of proposed hazard analysis methods for system-of- systems, 2) describe a case from construction equipment domain, and 3) apply the well-known System-Theoretic Process Analysis (STPA)f to our case. Our experiences during the case study and the analysis of results clearly point out certain inadequacies of STPA in the context of system-of-systems and underlines the need for the development of improved techniques for safety analysis of system-of-systems.

  • 191.
    Baumgart, Stephan
    et al.
    Volvo Construction Equipment, Eskilstuna, Sweden.
    Fröberg, Joakim
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. SICS Swedish ICT, Sweden.
    Punnekkat, Sasikumar
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Defining a Method to Perform Effective Hazard Analysis for a Directed SoS Based on STPA2018In: Third Swedish Workshop on the Engineering of Systems-of-Systems 2018 SWESoS 2018, 2018Conference paper (Refereed)
    Abstract [en]

    —Automating a quarry site as developed within the electric site research project at Volvo Construction Equipment is an example of a directed system-of-systems (SoS). In our case automated machines and connected smart systems are utilized to improve the work-flow at the site. We currently work on conducting hazard and safety analyses on the SoS level. Performing a hazard analysis on a SoS has been a challenge in terms of complexity and work effort. We elaborate on the suitability of methods, discuss requirements on a feasible method, and propose a tailoring of the STPA method to leverage complexity.

  • 192.
    Baumgart, Stephan
    et al.
    Volvo Construction Equipment, Eskilstuna, Sweden.
    Fröberg, Joakim
    Mälardalen University, School of Innovation, Design and Engineering, Innovation and Product Realisation.
    Punnekkat, Sasikumar
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. BIT-Pilani KK Birla Goa Campus, India.
    Enhancing Model-Based Engineering of Product Lines by Adding Functional Safety2015In: CEUR Workshop Proceedings, vol. 1487, 2015, p. 53-62Conference paper (Refereed)
    Abstract [en]

    Today's industrial product lines in the automotive and construction equipment domain face the challenge to show functional safety standard compliance and argue for the absence of failures for all derived product variants. The product line approaches are not su cient to support practitioners to trace safety-related characteristics through development. We aim to provide aid in creating a safety case for a certain con guration in a product line such that overall less e ort is necessary for each con guration. In this paper we 1) discuss the impact of functional safety on product line development, 2) propose a model-based approach to capture safety-related characteristics during concept phase for product lines and 3) analyze the usefulness of our proposal.

  • 193.
    Baumgart, Stephan
    et al.
    Volvo Construction Equipment, Eskilstuna, Sweden.
    Fröberg, Joakim
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Punnekkat, Sasikumar
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    How to Analyze the Safety of Concepts for a System-of-Systems?2021In: 7TH IEEE INTERNATIONAL SYMPOSIUM ON SYSTEMS ENGINEERING, 2021, p. 1-8Conference paper (Refereed)
    Abstract [en]

    Developing safety-critical products like cars, trains, or airplanes requires rigor in following development processes, and evidence for product safety must be collected. Safety needs to be considered during each development step and traced through the development life cycle. The current standards and approaches focus on single human-operated products. The technical evolution enables integrating existing products and new autonomous products into system-of-systems to automate workflows and production streams. Developing safety-critical systems-of-systems requires similar processes and mapping to safety-related activities. However, it is unclear how to consider safety during different development steps for a safety-critical system-of-systems. The existing hazard analysis methods are not explicitly mapped to developing a system-of-systems and are vague about the required information on the intended behavior. This paper focuses on the concept phase for developing a system-of-systems, where different technical concepts for a specific product feature are evaluated. Specifically, we concentrate on the evaluation of the safety properties of each concept. We present a process to support the concept phase and apply a model-driven approach to capture the system-of-systems’ relevant information. We then show how this knowledge is used for conducting an FMEA and HAZOP analysis. Lastly, the results from the analysis are mapped back into the sequence diagrams. This information is made available during the next development stages. We apply the method during the concept phase for designing an industrial system-of-systems. Our approach helps to design complex system-of-systems and supports concept evaluation considering the criticality of the concept under consideration.

  • 194.
    Baumgart, Stephan
    et al.
    Volvo Construction Equipment, Eskilstuna, Sweden.
    Fröberg, Joakim
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Punnekkat, Susikumar
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Analyzing Hazards in System-of-Systems: Described in a Quarry Site Automation Context2017In: 11th Annual IEEE International Systems conference SysCon, 2017, p. 544-551Conference paper (Refereed)
    Abstract [en]

    Methods for analyzing hazards related to individual systems are well studied and established in industry today. When system-of-systems are set up to achieve new emergent behavior, hazards specifically caused by malfunctioning behavior of the complex interactions between the involved systems may not be revealed by just analyzing single system hazards. A structured process is required to reduce the complexity to enable identification of hazards when designing system-of-systems. In this paper we first present how hazards are identified and analyzed using hazard and risk assessment (HARA) methodology by the industry in the context of single systems. We describe systems-of-systems and provide a quarry site automation example from the construction equipment domain. We propose a new structured process for identifying potential hazards in systems-of-systems (HISoS), exemplified in the context of the provided example. Our approach helps to streamline the hazard analysis process in an efficient manner thus helping faster certification of system-of-systems.

  • 195.
    Baumgart, Stephan
    et al.
    Volvo Construction Equipment, Eskilstuna, Sweden.
    Parmeza, Ditmar
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Predicting the Effort for Functional Safety in Product Lines2015In: The 41st Euromicro Conference on Software Engineering and Advanced Applications SEAA'15, 2015Conference paper (Refereed)
  • 196.
    Baumgart, Stephan
    et al.
    Volvo Autonomous Solutions, Eskilstuna, Sweden.
    Punnekkat, Sasikumar
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    A Model-Based Approach to Document a System-of-Systems2021In: 2021 IEEE International Systems Conference (SysCon), 2021, p. 1-8Conference paper (Refereed)
    Abstract [en]

    The technical evolution enables the development and application of autonomous systems in various domains. In the on-road and off-road vehicle domains, autonomous vehicles are applied in different contexts. Autonomous cars are designed as single system solutions, while in other scenarios, multiple autonomous or semi-autonomous vehicles are integrated into a system-of-systems. We utilize a case from the earth-moving machinery domain, where a fleet of autonomous vehicles is used for transporting material in off-road environments. The traditional industrial development processes in the earth-moving machinery domain focus on single human-operated systems and lack clear support for autonomous system-of-systems. From our studies of industrial development of system-of-systems, we recognize the demand for guidance on how to document a system-of-systems. The goal of this work is to provide a framework using different model-based formalisms. As a structural background, we utilize the SafeSoS process, where each step specifies details about the targeted system-of-systems. Specifically, we apply model-based systems engineering to describe the structure and behavior of each SoS level. We utilize an industrial case to exemplify how model-based concepts can be applied to capture relevant information needed for designing the system-of-systems. This work provides guidelines for practitioners in developing safe system-of-systems.

  • 197.
    Becker, Matthias
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Dasari, Dakshina
    Robert Bosch GmbH, Renningen, Germany.
    Mubeen, Saad
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Analyzing end-to-end delays in automotive systems at various levels of timing information2017In: ACM SIGBED Review, E-ISSN 1551-3688, Vol. 14, no 4, p. 8-13Article in journal (Refereed)
    Abstract [en]

    Software design for automotive systems is highly complex due to the presence of strict data age constraints for event chains in addition to task specific requirements. These age constraints define the maximum time for the propagation of data through an event chain consisting of independently triggered tasks. Tasks in event chains can have different periods, introducing over- and under-sampling effects, which additionally aggravates their timing analysis. Furthermore, different functionality in these systems, is developed by different suppliers before the final system integration on the ECU. The software itself is developed in a hardware agnostic manner and this uncertainty and limited information at the early design phases may not allow effective analysis of end-to-end delays during that phase. In this paper, we present a method to compute end-to-end delays given the information available in the design phases, thereby enabling timing analysis throughout the development process. The presented methods are evaluated with extensive experiments where the decreasing pessimism with increasing system information is shown.

  • 198.
    Becker, Matthias
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Dasari, Dakshina
    Research and Technology Centre, Robert Bosch, India.
    Mubeen, Saad
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    MECHAniSer - A Timing Analysis and Synthesis Tool for Multi-Rate Effect Chains with Job-Level Dependencies2016In: 7th International Workshop on Analysis Tools and Methodologies for Embedded and Real-time Systems WATERS'16, 2016Conference paper (Refereed)
    Abstract [en]

    Many industrial embedded systems have timing con- straints on the data propagation through a chain of independent tasks. These tasks can execute at different periods which leads to under and oversampling of data. In such situations, understand- ing and validating the temporal correctness of end-to-end delays is not trivial. Many industrial areas further face distributed development where different functionalities are integrated on the same platform after the development process. The large effect of scheduling decisions on the end-to-end delays can lead to expensive redesigns of software parts due to the lack of analysis at early design stages. Job-level dependencies is one solution for this challenge and means of scheduling such systems are available. In this paper we present MECHAniSer, a tool targeting the early analysis of end-to-end delays in multi-rate cause effect chains with specified job-level dependencies. The tool further provides the possibility to synthesize job-level dependencies for a set of cause-effect chains in a way such that all end-to-end requirements are met. The usability and applicability of the tool to industrial problems is demonstrated via a case study.

  • 199.
    Becker, Matthias
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Dasari, Dakshina
    Robert Bosch GmbH, Renningen, Germany.
    Mubeen, Saad
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Timing Analysis and Synthesis of Mixed Multi-Rate Effect Chains in MECHAniSer2016In: Open Demo Session of Real-Time Systems located at Real Time Systems Symposium (RTSS) RTSS@Work 2016, 2016Conference paper (Refereed)
    Abstract [en]

    The majority of embedded control systems are modeled with several chains of independently triggered tasks, also known as multi-rate effect chains. These chains have often stringent end-to-end timing requirements that should be satisfied before running the system. MECHAniSer is one of the tools that supports end-to-end timing analysis of such chains. In addition, the tool provides the possibility to synthesize job-level dependencies for these chains such that all end-to-end timing requirements are satisfied. In this paper we showcase an extension of MECHAniSer that supports the analysis of mixed chains that contain a mix of independent and dependent tasks.

  • 200.
    Becker, Matthias
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Dasari, Dakshina
    Research and Technology Centre, Robert Bosch, India.
    Nicolic, Borislav
    CISTER, INESC-TEC, ISEP, Portugal .
    Åkesson, Benny
    CISTER, INESC-TEC, ISEP, Portugal .
    Nélis, Vincent
    CISTER/INESC-TEC, ISEP, Portugal.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Contention-Free Execution of Automotive Applications on a Clustered Many-Core Platform2016In: 28th Euromicro Conference on Real-Time Systems ECRTS'16, Toulouse, France, 2016, p. 14-24Conference paper (Refereed)
    Abstract [en]

    Next generations of compute-intensive real-time applications in automotive systems will require more powerful computing platforms. One promising power-efficient solution for such applications is to use clustered many-core architectures. However, ensuring that real-time requirements are satisfied in the presence of contention in shared resources, such as memories, remains an open issue. This work presents a novel contention-free execution framework to execute automotive applications on such platforms. Privatization of memory banks together with defined access phases to shared memory resources is the backbone of the framework. An Integer Linear Programming (ILP) formulation is presented to find the optimal time-triggered schedule for the on-core execution as well as for the access to shared memory. Additionally a heuristic solution is presented that generates the schedule in a fraction of the time required by the ILP. Extensive evaluations show that the proposed heuristic performs only 0.5% away from the optimal solution while it outperforms a baseline heuristic by 67%. The applicability of the approach to industrially sized problems is demonstrated in a case study of a software for Engine Management Systems.

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