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  • 101.
    Andersson, Martin
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Sjöström, Emil
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    COMPARISON OF TIME- AND EVENT-TRIGGERED STRATEGIES FOR WIRELESS COMMUNICATION IN EMBEDDED SYSTEMS: Design of a lab assignment for university level course on data communication in embedded systems2016Självständigt arbete på grundnivå (kandidatexamen), 180 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Embedded systems (ESs) and wireless technologies are in constant rapid development and therefore it is important to educate people in these subjects. This thesis work has the goal of developing a lab assignment for a university level course on data communication in embedded systems. Embedded systems have reliability and timeliness requirements that have to be fulfilled. These criteria pose problems to be addressed while ESs are used in conjunction with communication over wireless medium, which has some underlying limitations. These limitations come in the form of interference, degradation of signal strength with the distance and possible unwanted delays. This thesis work starts with a literature study on medium access control (MAC) methods and their possibilities for adoption of time-triggered and event-driven strategies for ESs with time constraints and continues with the lab assignment design, implementation and testing. Taking into account timing requirements brought by ESs and the specifics of the lab, i.e., limited time given to the students to solve the problem and compulsory usage of available lab equipment, a design with two communicating raspberry Pis was proposed. The system consists of a sensor node sending its readings to a controller, which is responsible for analyzing the data and actuating a set of LED lights as a response to the input data. The communication is done over a WiFi network and three different programs, organizing the communication in time-triggered, eventdriven or a combination of the two fashions are developed. Each program is tested under three environmental conditions and the results from these tests clearly show the limitation of the underlying CSMA/CA MAC adopted in WiFi and give a greater understanding of the advantages and disadvantages of different strategies for communication design.

  • 102.
    Andersson, Sebastian
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Carlstedt, Gustav
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Automated Testing of Robotic Systems in Simulated Environments2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    With the simulations tools available today, simulation can be utilised as a platform for more advanced software testing. By introducing simulations to software testing of robot controllers, the motion performance testing phase can begin at an earlier stage of development. This would benefit all parties involved with the robot controller. Testers at ABB would be able to include more motion performance tests to the regression tests. Also, ABB could save money by adapting to simulated robot tests and customers would be provided with more reliable software updates. In this thesis, a method is developed utilising simulations to create a test set for detecting motion anomalies in new robot controller versions. With auto-generated test cases and a similarity analysis that calculates the Hausdorff distance for a test case executed on controller versions with an induced artificial bug. A test set has been created with the ability to detect anomalies in a robot controller with a bug.

  • 103.
    Andersson, Tom
    et al.
    Mälardalens högskola.
    Persson, Niklas
    Mälardalens högskola.
    Fattouh, Anas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Martin C.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    A loop shaping method for stabilising a riderless bicycle2019Ingår i: 2019 European Conference on Mobile Robots, ECMR 2019 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2019, artikel-id 8870965Konferensbidrag (Refereegranskat)
    Abstract [en]

    Several control methods have been proposed to stabilise riderless bicycles but they do not have sufficient simplicity for practical applications. This paper proposes a practical approach to model an instrumented bicycle as a combination of connected systems. Using this model, a PID controller is designed by a loop shaping method to stabilise the instrumented riderless bicycle. The initial results show that the bicycle can be stabilised when running on a roller. The work presented in this paper shows that it is possible to self stabilise a riderless bicycle using cascade PI/PID controllers.

  • 104. Andreasson, Jens
    et al.
    Lönnblad, Jens
    Mälardalens högskola, Institutionen för datavetenskap och elektronik.
    Fard, Ali
    Mälardalens högskola, Institutionen för datavetenskap och elektronik.
    Castano, Javier García
    Mälardalens högskola, Institutionen för datavetenskap och elektronik.
    Johnson, Tord
    Remote system for patient monitoring using bluetooth2002Ingår i: Proceedings of IEEE SensorsVolume 1, Issue 1, 2002, 2002, s. 304-307Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The aim of this study is to design and develop a low-power wireless A/D-converter that should be easy to integrate with other technologies or infrastructures at a low cost. This transmitting unit should be able to replace many of the signal wires between biomedical sensors connecting the patient and the sampling unit or supervision equipment. The model of today is an embedded hardware solution with two processors (FPGA and Bluetooth). A twelve bit ADC with a 1 kHz-sampling rate then converts an analogue signal that simulates an ECG-signal with typical frequencies. The communication between the ADC and Bluetooth™ is serial and controlled by the FPGA. The remote PC runs a simple software that controls the Bluetooth™ and processes the received data. The results indicate that it is possible to continuously transmit an ECG-signal without loosing data.

  • 105.
    Aravind, Meera
    et al.
    Mälardalens högskola.
    Wiklander, G.
    Uppsala University, Uppsala, Sweden.
    Palmheden, J.
    Scania AB, Södertälje, Sweden.
    Dobrin, Radu
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    An Event-Based Messaging Architecture for Vehicular Internet of Things (IoT) Platforms2017Ingår i: Communications in Computer and Information Science, vol. 778, Springer Verlag , 2017, s. 37-46Konferensbidrag (Refereegranskat)
    Abstract [en]

    Internet of Things (IoT) has revolutionized transportation systems by connecting vehicles consequently enabling their tracking, as well as monitoring of driver activities. Such an IoT platform requires a significant amount of data to be send from the on-board vehicle to the off-board servers, contributing to high network usage. The data can be send at regular intervals or in an event-based manner whenever relevant events occur. In interval-based approach, the data is send even if it is not relevant for reporting leading to a wastage of network resources, e.g., when the data does not change considerably compared to the previously sent value. In this paper, we investigate the possibility of using an event-based architecture to send data from the on-board system to the off-board system. The results show that our event-based architecture improves the accuracy of data available at the off-board system, by a careful selection of events. Moreover, we found that our event based architecture significantly decreases the frequency of sending messages, particularly during highway driving, leading to reduced average data transfer rates. Our results enable a customer to perform trade-offs between accuracy and data transfer rates. 

  • 106. Argunsah, Ali Özgur
    et al.
    Çürüklü, Baran
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Cetin, Mujdat
    Detection of Eye Blinks from EEG using Hidden Markov Models2009Konferensbidrag (Refereegranskat)
  • 107.
    Argunsah, Ali Özgur
    et al.
    Sabanci University, Turkey.
    Çürüklü, Baran
    Sabanci University, Turkey.
    Cetin, Mujdat
    Sabanci University, Turkey.
    Ercil, Aytul
    Sabanci University, Turkey.
    A Novel Feature Extraction Method for Improving P300-Speller Performance2007Konferensbidrag (Refereegranskat)
  • 108.
    Arroyo Rubio, Fernando
    Mälardalens högskola, Akademin för innovation, design och teknik.
    A SIMULATION ENVIRONMENT FOR AUTOMATIC NIGHT DRIVING AND VISUAL CONTROL2012Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This project consists on developing an automatic night driving system in a simulation environment. The simulator I have used is TORCS. TORCS is an Open Source car racing simulator written in C++. It is used as an ordinary car racing game, as a IA racing game and as a research platform. The goal of this thesis is to implement an automatic driving system to control the car under night conditions using computer vision. A camera is implemented inside the vehicle and it will detect the reflective light-markers placed along the roadside. The car is oriented only with the lights the camera can see.

  • 109.
    Asadi, Nima
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Enhancing the Monitoring of Real-Time Performance in Linux2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    There is a growing trend in applying Linux operating system in the domain of embeddedsystems. This is due to the important features that Linux benets from, such as beingopen source, its light weight compared to other major operating systems, its adaptabilityto dierent platforms, and its more stable performance speed. However, there are up-grades that still need to be done in order to use Linux for real-time purposes. A numberof dierent approaches have been suggested in order to improve Linux's performance inreal-time environment. Nevertheless, proposing a correct-by-construction system is verydicult in real-time environment, mainly due to the complexity and unpredictability ofthem. Thus, run-time monitoring can be a helpful approach in order to provide the userwith data regarding to the actual timing behavior of the system which can be used foranalysis and modication of it. In this thesis work, a design for run-time monitoringis suggested and implemented on a real-time scheduler module that assists Linux withreal-time tasks. Besides providing crucial data regarding the timing performance of thesystem, this monitor predicts violations of timing requirements based on the currenttrace of the system performance.

  • 110.
    Ashjaei, Mohammad
    Mälardalens högskola, Akademin för innovation, design och teknik. Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Multi-Hop Real-Time Communication over Switched Ethernet Technology2014Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Switched Ethernet technology has been introduced to be exploited in real-time communication systems due to its features such as its high throughput and wide availability, hence being a cost-effective solution. Many real-time switched Ethernet protocols have been developed, preserving the profits of traditional Ethernet technology, to overcome the limitations imposed by using commercially available (COTS) switches. These limitations mainly originate from the non-deterministic behavior of the Ethernet switches inherent in the use of FIFO queues and a limited number of priority levels.

     

    In our research we focus on two particular real-time communication technologies, one based on COTS Ethernet switches named the FTT-SE architecture and the other using a modified Ethernet switch called the HaRTES architecture. Both architectures are based on a master-slave technique supporting different and temporally isolated traffic types including real-time periodic, real-time sporadic and non-real-time traffic. Also, they provide mechanisms implementing adaptivity as a response to the requirements imposed by dynamic real-time applications. Nevertheless, the two mentioned architectures were originally developed for a simple network consisting of a single switch, and they were lacking support for multi-hop communication. In industrial applications, multi-hop communication is essential as the networks comprise a high number of nodes, that is far beyond the capability of a single switch.

     

    In this thesis, we study the challenges of building multi-hop communication using the FTT-SE and the HaRTES architectures. We propose different architectures to provide multi-hop communication while preserving the key characteristics of the single-switch architecture such as timeliness guarantee, resource efficiency, adaptivity and dynamicity. We develop a response time analysis for each proposed architecture and we compare them to assess their corresponding benefits and limitations. Further, we develop a simulation tool to evaluate the solutions.

  • 111.
    Ashjaei, Mohammad
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Real-Time Communication over Switched Ethernet with Resource Reservation2016Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Due to the need for advanced computer-controlled functionality in distributed embedded systems the requirements on network communication are becoming overly intricate. This dissertation targets the requirements that are concerned with real-time guarantees, run-time adaptation, resource utilization and flexibility during the development. The Flexible Time-Triggered Switched Ethernet (FTT-SE) and Hard Real-Time Ethernet Switching (HaRTES) network architectures have emerged as two promising solutions that can cater for these requirements. However, these architectures do not support multi-hop communication as they are originally developed for single-switch networks. This dissertation presents a fundamental contribution in multi-hop real-time communication over the FTT-SE and HaRTES architectures targeting the above mentioned requirements. It proposes and evaluates various solutions for scheduling and forwarding the traffic through multiple switches in these architectures. These solutions preserve the ability of dynamic adaptation without jeopardizing real-time properties of the architectures. Moreover, the dissertation presents schedulability analyses for the timeliness verification and evaluation of the proposed solutions as well as several protocols to support run-time adaptation in the multi-hop communication. Finally, the work led to an end-to-end resource reservation framework, based on the proposed multi-hop architectures, to support flexibility during the development of the systems. The efficiency of the proposed solutions is evaluated on various case studies that are inspired from industrial systems.

  • 112.
    Ashjaei, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Behnam, Moris
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Almeida, Luis
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. University of Porto, Porto, Portugal .
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    MTU Configuration for Real-Time Switched Ethernet Networks2016Ingår i: Journal of systems architecture, ISSN 1383-7621, E-ISSN 1873-6165, Vol. 70, s. 15-25Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we show that in real-time switched Ethernet networks reducing the Maximum Transmission Unit (MTU) size may cause an increase or decrease in the response time of messages. This contradicting behavior arises an optimization problem for configuring the MTU size. We formulate the optimization problem in the context of the multi-hop HaRTES architecture, which is a hard real-time Ethernet protocol. As part of the solution, we propose a search-based algorithm to achieve optimum solutions. We modify the algorithm by presenting two techniques to reduce the search space. Then, we propose a heuristic algorithm with a pseudo-polynomial time complexity based on the search-based algorithm. We perform several experiments, and we show that the proposed heuristic results in an improvement regarding messages response times, compared with configuring the MTU to the maximum or minimum values. Moreover, we show in small network configurations that the heuristic performs as good as the search-based algorithm in many cases.

  • 113.
    Ashjaei, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Malardalen Univ, Malardalen Real Time Res Ctr MRTC, POB 883, SE-72123 Vasteras, Sweden..
    Behnam, Moris
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Malardalen Univ, Malardalen Real Time Res Ctr MRTC, POB 883, SE-72123 Vasteras, Sweden..
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Malardalen Univ, Malardalen Real Time Res Ctr MRTC, POB 883, SE-72123 Vasteras, Sweden..
    SEtSim: A modular simulation tool for switched Ethernet networks2016Ingår i: Journal of systems architecture, ISSN 1383-7621, E-ISSN 1873-6165, Vol. 65, s. 1-14Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Using high bandwidth network technologies in real-time applications, for example in automotive systems, is rapidly increasing. In this context, switched Ethernet-based protocols are becoming more popular due to their features such as providing a collision-free domain for transmission of messages. Moreover, switched Ethernet is a mature technology. Several protocols based on switched Ethernet have been proposed over the years, tuned for time critical applications. However, research for improving the features and performance of these protocols is still on-going. In order to evaluate the performance of early stage proposed protocols, the mathematical analysis and/or experiments are required. However, performing an experiment for complex network topologies with a large set of messages is not effortless. Therefore, using a simulation based approach for evaluating a protocol's performance and/or properties is highly useful. As a response to this we have developed a simulator, called SEtSim, for switched Ethernet networks. SEtSim is developed based on Simulink, and it currently supports different network topologies of the FIT-SE protocol as well as Ethernet AVB protocol. However, the kernel of SEtSim is designed such that it is possible to add and integrate other switched Ethernet-based protocols. In this paper, we describe the design of SEtSim and we show its scalability.

  • 114.
    Ashjaei, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik. Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Behnam, Moris
    Mälardalens högskola, Akademin för innovation, design och teknik. Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik. Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    SEtSim: A Modular Simulation Tool for Switched Ethernet Networks2014Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Using high bandwidth network technologies in real-time applications, for example in automotive systems, is rapidly increasing. In this context, switched Ethernet-based protocols are becoming more popular due to their features such as providing a collision-free domain for transmission of messages. Moreover, switched Ethernet is a mature technology. Several protocols based on switched Ethernet have been proposed over the years, tuned for time critical applications. However, research for improving the features and performance of these protocols is still on-going. In order to evaluate the performance of early stage proposed protocols, the mathematical analysis and/or experiments are required. However, performing an experiment for complex network topologies with a large set of messages is not effortless. Therefore, using a simulation based approach for evaluating a protocol's performance and/or properties is highly useful. As a response to this we have, based on Simulink, developed a simulator, called SEtSim, for switched Ethernet networks. SEtSim currently supports different network topologies of the FTT-SE protocol, a master-slave protocol designed for standard Ethernet switches, as well as Ethernet AVB protocol. However, the kernel of SEtSim is designed such that it is possible to add and integrate other switched Ethernet-based protocols. In this paper, we describe the design of SEtSim and we show its scalability.

  • 115.
    Ashjaei, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Du, Yong
    Almeida, L.
    University of Porto, Porto, Portugal .
    Behnam, Moris
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Dynamic reconfiguration in HaRTES switched ethernet networks2016Ingår i: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS, 2016, artikel-id Article number 7496510Konferensbidrag (Refereegranskat)
    Abstract [en]

    The ability of reconfiguring a system during runtime is essential for dynamic real-time applications in which resource usage is traded online for quality of service. The HaRTES switch, which is a modified Ethernet switch, holds this ability for the network resource, and at the same time it provides hard real-time support for both periodic and sporadic traffic. Although the HaRTES switch technologically caters this ability, a protocol to actually perform the dynamic reconfiguration is missing in multi-hop HaRTES networks. In this paper we introduce such a protocol that is compatible with the traffic scheduling method used in the architecture. We prove the correctness of the protocol using a model checking technique. Moreover, we conduct a set of simulation experiments to show the performance of the protocol and we also show that the reconfiguration process is terminated within a bounded time. 

  • 116.
    Ashjaei, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Khalilzad, Nima
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Mubeen, Saad
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. IS (Embedded Systems).
    Behnam, Moris
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Sander, Ingo
    Royal Institute of Technology, Sweden.
    Almeida, Luis
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Designing End-to-end Resource Reservations in Predictable Distributed Embedded Systems2017Ingår i: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 53, nr 6, s. 916-956Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Contemporary distributed embedded systems in many domains have become highly complex due to ever-increasing demand on advanced computer controlled functionality. The resource reservation techniques can be effective in lowering the software complexity, ensuring predictability and allowing flexibility during the development and execution of these systems. This paper proposes a novel end-to-end resource reservation model for distributed embedded systems. In order to support the development of predictable systems using the proposed model, the paper provides a method to design resource reservations and an end-to-end timing analysis. The reservation design can be subjected to different optimization criteria with respect to runtime footprint, overhead or performance. The paper also presents and evaluates a case study to show the usability of the proposed model, reservation design method and end-to-end timing analysis. 

  • 117.
    Ashjaei, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Mubeen, Saad
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Behnam, Moris
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Almeida, Luis
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    End-to-end Resource Reservations in Distributed Embedded Systems2016Ingår i: Proceedings - 2016 IEEE 22nd International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2016, 2016, s. 1-11, artikel-id 7579921Konferensbidrag (Refereegranskat)
    Abstract [en]

    The resource reservation techniques provide effective means to lower the software complexity, ensure predictability and allow flexibility during the development and execution of complex distributed embedded systems. In this paper we propose a new end-to-end resource reservation model for distributed embedded systems. The model is comprehensive in such a way that it supports end-to-end resource reservations on distributed transactions with various activation patterns that are commonly used in industrial control systems. The model allows resource reservations on processors and real-time network protocols. We also present timing analysis for the distributed embedded systems that are developed using the proposed model. The timing analysis computes the end-to-end response times as well as delays such as data age and reaction delays. The presented analysis also supports real-time networks that can autonomously initiate transmissions. Such networks are not supported by the existing analyses. We also include a case study to show the usability of the model and end-to-end timing analysis with resource reservations.

  • 118.
    Ashjaei, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Mubeen, Saad
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Behnam, Moris
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    End-to-end Resource Reservation Model2016Manuskript (preprint) (Övrigt vetenskapligt)
  • 119.
    Ashjaei, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Patti, Gaetano
    University of Catania, Italy.
    Behnam, Moris
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Alderisi, Giuliana
    University of Catania, Italy.
    Lo Bello, Lucia
    University of Catania, Italy.
    Schedulability Analysis of Ethernet Audio Video Bridging Networks with Scheduled Traffic Support2017Ingår i: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 53, nr 4, s. 526-577Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The IEEE Audio Video Bridging (AVB) technology is nowadays under consideration in several automation domains, such as, automotive, avionics, and industrial communications. AVB offers several benefits, such as open specifications, the existence of multiple providers of electronic components, and the real-time support, as AVB provides bounded latency to real-time traffic classes. In addition to the above mentioned properties, in the automotive domain, comparing with the existing in-vehicle networks, AVB offers significant advantages in terms of high bandwidth, significant reduction of cabling costs, thickness and weight, while meeting the challenging EMC/EMI requirements. Recently, an improvement of the AVB protocol, called the AVB ST, was proposed in the literature, which allows for supporting scheduled traffic, i.e., a class of time-sensitive traffic that requires time-driven transmission and low latency. In this paper, we present a schedulability analysis for the real-time traffic crossing through the AVB ST network. In addition, we formally prove that, if the bandwidth in the network is allocated according to the AVB standard, the schedulability test based on response time analysis will fail for most cases even if, in reality, these cases are schedulable. In order to provide guarantees based on analysis test a bandwidth over-reservation is required. In this paper, we propose a solution to obtain a minimized bandwidth over-reservation. To the best of our knowledge, this is the first attempt to formally spot the limitation and to propose a solution for overcoming it. The proposed analysis is applied to both the AVB standard and the AVB ST. The analysis results are compared with the results of several simulative assessments, obtained using OMNeT++, on both automotive and industrial case studies. The comparison between the results of the analysis and the simulation ones shows the effectiveness of the analysis proposed in this work.

  • 120.
    Ashjaei, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Pedreiras, P.
    University of Aveiro, Aveiro, Portugal .
    Behnam, Moris
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Almeida, L.
    University of Porto, Porto, Portugal.
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Evaluation of dynamic reconfiguration architecture in multi-hop switched ethernet networks2014Ingår i: 19th IEEE International Conference on Emerging Technologies and Factory Automation, ETFA 2014, 2014, s. Article number 7005322-Konferensbidrag (Refereegranskat)
    Abstract [en]

    On-the-fly adaptability and reconfigurability are recently becoming an interest in real-time communications. To assure a continued real-time behavior, the admission control with a quality-of-service mechanism is required, that screen all adaptation and reconfiguration requests. In the context of switched Ethernet networks, the FTT-SE protocol provides adaptive real-time communication. Recently, we proposed two methods to perform the online reconfiguration in multi-hop FTT-SE architectures. However, the methods lack the experimental evaluation. In this paper, we evaluate both methods in terms of the reconfiguration time. 

  • 121.
    Ashjaei, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. MRTC Malardalen Univ, Vasteras, Sweden..
    Silva, Luis
    DETI IT Univ Aveiro, Aveiro, Portugal..
    Behnam, Moris
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. MRTC Malardalen Univ, Vasteras, Sweden..
    Pedreiras, Paulo
    DETI IT Univ Aveiro, Aveiro, Portugal..
    Bril, Reinder J.
    Tech Univ Eindhoven TU E, Eindhoven, Netherlands..
    Almeida, Luis
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. MRTC Malardalen Univ, Vasteras, Sweden.;IT DEEC Univ Porto, Oporto, Portugal..
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. MRTC Malardalen Univ, Vasteras, Sweden..
    Improved Message Forwarding for Multi-Hop HaRTES Real-Time Ethernet Networks2016Ingår i: Journal of Signal Processing Systems, ISSN 1939-8018, E-ISSN 1939-8115, Vol. 84, nr 1, s. 47-67Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nowadays, switched Ethernet networks are used in complex systems that encompass tens to hundreds of nodes and thousands of signals. Such scenarios require multi-switch architectures where communications frequently occur in multiple hops. In this paper we investigate techniques to allow efficient multi-hop communication using HaRTES switches. These are modified Ethernet switches that provide real-time traffic scheduling, dynamic bandwidth management and temporal isolation between real-time and non-real-time traffic. This paper addresses the problem of forwarding traffic in HaRTES networks. Two methods have been recently proposed, namely Distributed Global Scheduling (DGS) that buffers traffic between switches, and Reduced Buffering Scheme (RBS), that uses immediate forwarding. In this paper, we discuss the design and implementation of RBS within HaRTES and we carry out an experimental validation with a prototype implementation. Then, we carry out a comparison between RBS and DGS using worst-case response time analysis and simulation. The comparison clearly establishes the superiority of RBS concerning end-to-end response times. In fact, with sample message sets, we achieved reductions in end-to-end delay that were as high as 80 %.

  • 122.
    Ashjaei, Seyed Mohammad Hossein
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Clegg, Kester
    Univ York, York, N Yorkshire, England..
    Corneo, Lorenzo
    Uppsala Univ, Uppsala, Sweden..
    Hawkins, Richard
    Univ York, York, N Yorkshire, England..
    Jaradat, Omar
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Gulisano, Vincenzo Massimiliano
    Chalmers Univ, Gothenburg, Sweden..
    Nikolakopoulos, Yiannis
    Chalmers Univ, Gothenburg, Sweden..
    Service Level Agreements for Safe and Configurable Production Environments2018Ingår i: 2018 IEEE 23RD INTERNATIONAL CONFERENCE ON EMERGING TECHNOLOGIES AND FACTORY AUTOMATION (ETFA), IEEE , 2018, s. 1252-1255Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper focuses on Service Level Agreements (SLAs) for industrial applications that aim to port some of the control functionalities to the cloud. In such applications, industrial requirements should be reflected in SLAs. In this paper, we present an approach to integrate safety-related aspects of an industrial application to SLAs. We also present the approach in a use case. This is an initial attempt to enrich SLAs for industrial settings to consider safety aspects, which has not been investigated thoroughly before.

  • 123.
    Ashjaei, Seyed Mohammad Hossein
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Clegg, Kester
    University of York, UK.
    Corneo, Lorenzo
    Uppsala University, Sweden.
    Hawkins, Richard
    University of York, UK.
    Jaradat, Omar
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Gulisano, Vincenzo
    Chalmers University of Technology, Göteborg, Sweden.
    Nikolakopoulos, Yiannis
    Chalmers University of Technology, Göteborg, Sweden.
    Service Level Agreements for Safe and Configurable Production Environments2018Ingår i: International Conference on Emerging Technologies and Factory Automation - Work in Progress Session ETFA-WiP'18, 2018, s. 1252-1255, artikel-id 8502568Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper focuses on Service Level Agreements (SLAs) for industrial applications that aim to port some of the control functionalities to the cloud. In such applications, industrial requirements should be reflected in SLAs. In this paper, we present an approach to integrate safety-related aspects of an industrial application to SLAs. We also present the approach in a use case. This is an initial attempt to enrich SLAs for industrial settings to consider safety aspects, which has not been investigated thoroughly before.

  • 124.
    Ashjaei, Seyed Mohammad Hossein
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Khalilzad, Nima
    Qamcom Research and Technology, Stockholm, Sweden.
    Mubeen, Saad
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Modeling, Designing and Analyzing Resource Reservations in Distributed Embedded Systems2018Ingår i: Real-Time Modelling and Processing for Communication Systems / [ed] Springer, Springer , 2018, s. 203-256Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 125.
    Ashjaei, Seyed Mohammad Hossein
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Mubeen, Saad
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Lundbäck, John
    Arcticus Systems AB, Sweden.
    Gålnander, Mattias
    Arcticus Systems AB, Sweden.
    Lundbäck, Kurt-Lennart
    Arcticus Systems AB, Sweden.
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Modeling and Timing Analysis of Vehicle Functions Distributed over Switched Ethernet2017Ingår i: IECON 2017 - 43RD ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY, 2017, s. 8419-8424Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper proposes an approach to model switched Ethernet communication within a model- and component-based software development framework for vehicular distributed embedded systems. The paper also presents a method to extract the network timing model from the systems that use switched Ethernet networks. In order to provide a proof of concept, an existing industrial component model and its tool suite, namely RCM and Rubus-ICE respectively, are extended by implementing the modeling technique, the timing model extraction method and response-time analysis of the Ethernet AVB protocol. The extensions to RCM are backward compatible with the modeling and end-to-end timing analysis of traditional in-vehicle networks and legacy (previously developed) vehicular distributed embedded systems. Furthermore, the paper discusses the implementation and test strategy used in this work. Finally, the usability of the modeling approach and implemented timing analysis is demonstrated by modeling and time analyzing a vehicular application case study with the extended component model and tool suite.

  • 126.
    Aslam, Mudassar
    Mälardalens högskola, Akademin för innovation, design och teknik. Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Bringing Visibility in the Clouds: using Security, Transparency and Assurance Services2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The evolution of cloud computing allows the provisioning of IT resources over the Internet and promises many benefits for both - the service users and providers. Despite various benefits offered by cloud based services, many users hesitate in moving their IT systems to the cloud mainly due to many new security problems introduced by cloud environments. In fact, the characteristics of cloud computing become basis of new problems, for example, support of third party hosting introduces loss of user control on the hardware; similarly, on-demand availability requires reliance on complex and possibly insecure API interfaces; seamless scalability relies on the use of sub-providers; global access over public Internet exposes to broader attack surface; and use of shared resources for better resource utilization introduces isolation problems in a multi-tenant environment. These new security issues in addition to existing security challenges (that exist in today's classic IT environments) become major reasons for the lack of user trust in cloud based services categorized in Software-as-a-Service (SaaS), Platform-as-a-Service (PaaS) or Infrastructure-as-a-Service (IaaS).

    The focus of this thesis is on IaaS model which allows users to lease IT resources (e.g. computing power, memory, storage, etc.) from a public cloud to create Virtual Machine (VM) instances. The public cloud deployment model considered in this thesis exhibits most elasticity (i.e. degree of freedom to lease/release IT resources according to user demand) but is least secure as compared to private or hybrid models. As a result, public clouds are not trusted for many use cases which involve processing of security critical data such as health records, financial data, government data, etc. However, public IaaS clouds can also be made trustworthy and viable for these use cases by providing better transparency and security assurance services for the user. In this thesis, we consider such assurance services and identify security aspects which are important for making public clouds trustworthy. Based upon our findings, we propose solutions which promise to improve cloud transparency thereby realizing trustworthy clouds.

    The solutions presented in this thesis mainly deal with the secure life cycle management of the user VM which include protocols and their implementation for secure VM launch and migration. The VM launch and migration solutions ensure that the user VM is always hosted on correct cloud platforms which are setup according to a profile that fulfills the use case relevant security requirements. This is done by using an automated platform security audit and certification mechanism which uses trusted computing and security automation techniques in an integrated solution. In addition to provide the assurance about the cloud platforms, we also propose a solution which provides assurance about the placement of user data in correct and approved geographical locations which is critical from many legal aspects and usually an important requirement of the user. Finally, the assurance solutions provided in this thesis increase cloud transparency which is important for user trust and to realize trustworthy clouds.

  • 127.
    Aslam, Mudassar
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Secure Service Provisioning in a Public Cloud2012Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The evolution of cloud technologies which allows the provisioning of IT resources over the Internet promises many benefits for the individuals and enterprises alike. However, this new resource provisioning model comes with the security challenges which did not exist in the traditional resource procurement mechanisms. We focus on the possible security concerns of a cloud user (e.g. an organization, government department, etc.) to lease cloud services such as resources in the form of Virtual Machines (VM) from a public Infrastructure-as-a-Service (IaaS) provider. There are many security critical areas in the cloud systems, such as data confidentiality, resource integrity, service compliance, security audits etc. In this thesis, we focus on the security aspects which result in the trust deficit among the cloud stakeholders and hence hinder a security sensitive user to benefit from the opportunities offered by the cloud computing. Based upon our findings from the security requirements analysis,we propose solutions that enable user trust in the public IaaS clouds. Our solutions mainly deal with the secure life cycle management of the user VM which include mechanisms for VM launch and migration. The VM launch and migration solutions ensure that the user VM is always protected in the cloud by only allowing it to run on the user trusted platforms. This is done by using trusted computing techniques that allow the users to remotely attest and hence rate the cloud platforms trusted or untrusted. We also provide a prototype implementation to prove the implementation feasibility of the proposed trust enabling principles used in the VM launch and migration solutions.

  • 128.
    Aslam, Mudassar
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Gehrmann, Christian
    Deploying Virtual Machines on Shared Platforms2011Rapport (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    In this report, we describe mechanisms for secure deployment of virtual machines on shared platforms looking into a telecommunication cloud use case, which is also presented in this report. The architecture we present focuses on the security requirements of the major stakeholders’ part of the scenario we present. This report comprehensively covers all major security aspects including different security mechanisms and protocols, leveraging existing standards and state-of-the art wherever applicable. In particular, our architecture uses TCG technologies for trust establishment in the deployment of operator virtual machines on shared resource platforms. We also propose a novel procedure for securely launching and cryptographically binding a virtual machine to a target platform thereby protecting the operator virtual machine and its related credentials.

  • 129. Aslam, Mudassar
    et al.
    Gehrmann, Christian
    Security Considerations for Virtual Platform Provisioning2011Ingår i: PROCEEDINGS OF THE 10TH EUROPEAN CONFERENCE ON INFORMATION WARFARE AND SECURITY, Reading, 2011, s. 283-290Konferensbidrag (Refereegranskat)
    Abstract [en]

    The concept of virtualization is not new but leveraging virtualization in different modes and at different layers has revolutionized its usage scenarios. Virtualization can be applied at application layer to create sandbox environment, operating system layer to virtualize shared system resources (e.g. memory, CPU), at platform level or in any other useful possible hybrid scheme. When virtualization is applied at platform level, the resulting virtualized platform can run multiple virtual machines as if they were physically separated real machines. Provisioning virtualized platforms in this way is often also referred to as Infrastructure-as-a-Service or Platform-as-a-Service when full hosting and application support is also offered. Different business models, like data-centers or telecommunication providers and operators, can get business benefits by using platform virtualization due to the possibility of increased resource utilization and reduced upfront infrastructure setup expenditures. This opportunity comes together with new security issues. An organization that runs services in form of virtual machine images on an offered platform needs security guarantees. In short, it wants evidence that the platforms it utilizes are trustworthy and that sensitive information is protected. Even if this sounds natural and straight forward, few attempts have been made to analyze in details what these expectations means from a security technology perspective in a realistic deployment scenario. In this paper we present a telecommunication virtualized platform provisioning scenario with two major stakeholders, the operator who utilizes virtualized telecommunication platform resources and the service provider, who offers such resources to operators. We make threats analysis for this scenario and derive major security requirements from the different stakeholders’ perspectives. Through investigating a particular virtual machine provisioning use case, we take the first steps towards a better understanding of the major security obstacles with respect to platform service offerings. The last couple of years we have seen increased activities around security for clouds regarding different usage and business models. We contribute to this important area through a thorough security analysis of a concrete deployment scenario. Finally, we use the security requirements derived through the analysis to make a comparison with contemporary related research and to identify future research challenges in the area.

  • 130.
    Aslam, Mudassar
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Gehrmann, Christian
    TCG Based Approach for Secure Management of Virtualized Platforms: state-of-the-art2010Rapport (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    There is a strong trend shift in the favor of adopting virtualization to get business benefits. The provisioning of virtualized enterprise resources is one kind of many possible scenarios. Where virtualization promises clear advantages it also poses new security challenges which need to be addressed to gain stakeholders confidence in the dynamics of new environment. One important facet of these challenges is establishing 'Trust' which is a basic primitive for any viable business model. The Trusted computing group (TCG) offers technologies and mechanisms required to establish this trust in the target platforms. Moreover, TCG technologies enable protecting of sensitive data in rest and transit. This report explores the applicability of relevant TCG concepts to virtualize enterprise resources securely for provisioning, establish trust in the target platforms and securely manage these virtualized Trusted Platforms.

  • 131.
    Aslam, Mudassar
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Gehrmann, Christian
    SICS Swedish ICT, Sweden.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    ASArP: Automated Security Assessment & Audit of Remote Platforms: using TCG-SCAP synergies2015Ingår i: Journal of Internet Services and Applications JISA-14, ISSN 1869-0238, Vol. 22, s. 28-39Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Many enterprise solutions today are built upon complex distributed systems which are accessible to the users globally. Due to this global access, the security of the host platforms becomes critical. The platform administrators use security automation techniques such as those provided by Security Content Automation Protocol (SCAP) standards to protect the systems from the vulnerabilities that are reported daily; furthermore, they are responsible for keeping their systems compliant to the relevant security recommendations (governmental or industrial). Additionally, third party audit and certification processes are used to increase user trust in enterprise solutions. However, traditional audit and certification mechanisms are not continuous, that is, not frequent enough to deal with the daily reported vulnerabilities, and for that matter even auditors expect platform administrators to keep the systems updated. As a result, the end user is also forced to trust the platform administrators about the latest state of the platform. In this paper we develop an automated security audit and certification system (ASArP) which can be used by platform users or by third party auditors. We use security automation techniques for continuous monitoring of the platform security posture and make the results trustworthy by using trusted computing (TCG) techniques. The prototype development of ASArP validates the implementation feasibility; it also provides performance benchmarks which show that the ASArP based audit and certification can be done much more frequently (e.g. daily or weekly). The feasibility of ASArP based continuous audits is significantly better than traditional platform audits which are dependent on the physical presence of the auditors, thus making frequent audits much more expensive and operationally infeasible.

  • 132.
    Aslam, Mudassar
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Gehrmann, Christian
    Swedish Institute of Computer Science, Kista.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Security and Trust Preserving VM Migrations in Public Clouds2012Ingår i: Proceedings of the 11th IEEE International Conference onTrust, Security and Privacy in Computingand Communications (TrustCom-2012), IEEE Computer Society Digital Library, 2012, s. 869-876Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we consider the security and trustimplications of virtual machine (VM) migration from one cloudplatform to the other in an Infrastructure-as-a-Service (IaaS) cloud service model. We show how to extend and complement previous Trusted Computing techniques for secure VM launchto also cover the VM migration case. In particular, we propose a Trust_Token based VM migration protocol which guarantees that the user VM can only be migrated to a trustworthy cloud platform. Different from previous schemes, our solution is not dependent on an active (on-line) trusted third party. We show how our proposed mechanisms fulfill major security and trust requirements for secure VM migration in cloud environments.

  • 133.
    Aslam, Mudassar
    et al.
    Swedish Institute of Computer Science, Kista.
    Gehrmann, Christian
    Swedish Institute of Computer Science, Kista.
    Rasmusson, Lars
    Swedish Institute of Computer Science, Kista.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Securely Launching Virtual Machines on Trustworthy Platforms in a Public Cloud2012Ingår i: CLOSER 2012 - Proceedings of the 2nd International Conference on Cloud Computing and Services Science, 2012, s. 511-521Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we consider the Infrastructure-as-a-Service (IaaS) cloud model which allows cloud users to run their own virtual machines (VMs) on available cloud computing resources. IaaS gives enterprises the possibility to outsource their process workloads with minimal effort and expense. However, one major problem with existing approaches of cloud leasing, is that the users can only get contractual guarantees regarding the integrity of the offered platforms. The fact that the IaaS user himself or herself cannot verify the provider promised cloud platform integrity, is a security risk which threatens to prevent the IaaS business in general. In this paper we address this issue and propose a novel secure VM launch protocol using Trusted Computing techniques. This protocol allows the cloud IaaS users to securely bind the VM to a trusted computer configuration such that the clear text VM only will run on a platform that has been booted into a trustworthy state. This capability builds user confidence and can serve as an important enabler for creating trust in public clouds. We evaluate the feasibility of our proposed protocol via a full scale system implementation and perform a system security analysis.

  • 134.
    Asplund, Lars
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Lundqvist, Kristina
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Safety Critical Systems Based on Formal Models2000Ingår i: ACM SIGAda Letters, ISSN 1094-3641, Vol. XX, nr 4, s. 32-39Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Ravenscar profile for high integrity systems using Ada 95 is well defined in all real-time aspects. The complexity of the run-time system has been reduced to allow full utilization of formal methods for applications using the Ravenscar profile. In the Mana project a tool set is being developed including a formal model of a Ravenscar compliant run-time system, a gnat compatible run-time system, and an ASIS based tool to allow for the verification of a system including both COTS and code that is reused.

  • 135.
    Asplund, Lars
    et al.
    Uppsala University, Sweden.
    Lundqvist, Kristina
    Massachusetts Institute of Technology, USA.
    Safety Critical Systems Based on Formal Models2000Ingår i: ACM SIGAda Ada Letters - special issue on presentations from SIGAda 2000, Vol. XX, Iss. 4, 2000Konferensbidrag (Övrigt vetenskapligt)
  • 136.
    Asplund, Lars
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Lundqvist, Kristina
    MIT, Cambridge, MA, United States .
    The Gurkh Project: A Framework for Verification and Execution of Mission Critical Applications2003Ingår i: AIAA/IEEE Digital Avionics Systems Conference - Proceedings, vol. 2, 2003, s. 10.B.1/1-10.B.1/9Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The paper contributes with three methods that together will make a complete tool-set for verification of mission critical applications. The first method is the transformation of existing Ada or VHDL code into an intermediate form. This form is used for verification by numerous different model checkers. The second method is a predictable runtime kernel that has both a verifiable formal model and is implemented in hardware to achieve full predictability. Finally, a method for transforming the intermediate form of the complete system into a hardware unit, the SafetyChip that performs runtime control of the system. This SafetyChip can catch 'out-of-state' behaviors.

  • 137.
    Astrand, Elaine
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Extraction of working memory load and the importance of understanding the temporal dynamics2017Ingår i: International IEEE/EMBS Conference on Neural Engineering, NER, IEEE Computer Society , 2017, s. 641-647, artikel-id 8008433Konferensbidrag (Refereegranskat)
    Abstract [en]

    Working memory processing is central for higher-order cognitive functions. Although the ability CP to access and extract working memory load has been proven feasible, the temporal resolution is low and cross-task generalization is poor. In this study, EEG oscillatory activity CP was recorded from sixteen healthy subjects while they performed two versions of the visual n-back task. Observed effects in the working memory-related EEG oscillatory activity CP, specifically in theta, alpha and low beta power, are significantly different in the two tasks (i.e. two categories of visual stimuli) and these differences are greatest after image onset. Furthermore, cross-task generalization can be obtained by concatenating both tasks and although similar performances are observed before and after image onset, this study highlights the complexity CP of working memory processing related to different categories of visual stimuli, particularly after image onset, that are crucial to understand, in order to interpret the extraction of working memory load.

  • 138. Avdagic, Zikrija
    et al.
    Boskovic, Dusanka
    Causevic, Aida
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Code Evaluation Using Fuzzy Logic2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents application of a fuzzy logic based system to automatically evaluate the

    maintainability of code. Code evaluation is accomplished by rating its quality provided with bad smells in

    code as inputs. Straightforward bad smells with existing software metrics tools are selected as inputs:

    duplicated code, long methods, large classes having a high cyclomatic complexity, or a large number of

    parameters and temporary fields. Removing these bad smells can result in significant code improvements

    concerning readability and maintainability. However, the precise definition of attributes like small, long, large

    or high is not clear, and their identification is rather subjective. Fuzzy logic values are suitable for capturing

    partial correspondence to attributes and fuzzy rules model have been used to describe the relation between bad

    smells and code quality. Model supporting the experimental evaluation of the fuzzy based code evaluation is

    implemented in Java.

    Key-Words: - Fuzzy Logic, Reasoning Systems, Refactoring, Bad Smells

  • 139.
    Avelin, Anders
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Widarsson, Björn
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Lilja, Reijo
    VTT, Espoo, Finland.
    Time based data reconciliation and decision support for a CFB boiler2009Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline), 2009 / [ed] Yrjö Majanne, Tampere: Tampere University Press , 2009, s. 338-343Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper covers a method for operator decision support, where physical simulation models are used to connect different physical variables to each other. By comparing energy and material balances for a larger process area inconsistencies in single process parts and sensor measurements can be detected, by following the development between single measurements and values predicted from the simulations. This information then can be used as input to e.g. a BN, Bayesian Network, for decision support. The application has been for a CFB boiler at Mälarenergi AB. The simulators have been made in Modelica respectively a more advanced model in APROS.

  • 140.
    Avni, G.
    et al.
    IST Austria, Klosterneuburg, Austria.
    Goel, S.
    IIT Bombay, Mumbai, India.
    Henzinger, T. A.
    IST Austria, Klosterneuburg, Austria.
    Rodriguez-Navas, Guillermo
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Computing scores of forwarding schemes in switched networks with probabilistic faults2017Ingår i: Lecture Notes in Computer Science, Volume 10206, Springer Verlag , 2017, s. 169-187Konferensbidrag (Refereegranskat)
    Abstract [en]

    Time-triggered switched networks are a deterministic communication infrastructure used by real-time distributed embedded systems. Due to the criticality of the applications running over them, developers need to ensure that end-to-end communication is dependable and predictable. Traditional approaches assume static networks that are not flexible to changes caused by reconfigurations or, more importantly, faults, which are dealt with in the application using redundancy. We adopt the concept of handling faults in the switches from non-real-time networks while maintaining the required predictability. We study a class of forwarding schemes that can handle various types of failures. We consider probabilistic failures. For a given network with a forwarding scheme and a constant ℓ, we compute the score of the scheme, namely the probability (induced by faults) that at least ℓ messages arrive on time. We reduce the scoring problem to a reachability problem on a Markov chain with a “product-like” structure. Its special structure allows us to reason about it symbolically, and reduce the scoring problem to #SAT. Our solution is generic and can be adapted to different networks and other contexts. Also, we show the computational complexity of the scoring problem is #P-complete, and we study methods to estimate the score. We evaluate the effectiveness of our techniques with an implementation.

  • 141.
    Avni, G.
    et al.
    IST Austria, Klosterneuburg, Austria..
    Guha, S.
    Hebrew Univ Jerusalem, Jerusalem, Israel.
    Rodriguez-Navas, Guillermo
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Synthesizing time-triggered schedules for switched networks with faulty links2016Ingår i: Proceedings of the 13th International Conference on Embedded Software, EMSOFT 2016, 2016, artikel-id a26Konferensbidrag (Refereegranskat)
    Abstract [en]

    Time-triggered (TT) switched networks are a deterministic communication infrastructure used by real-time distributed embedded systems. These networks rely on the notion of globally discretized time (i.e. time slots) and a static TT schedule that prescribes which message is sent through which link at every time slot, such that all messages reach their destination before a global timeout. These schedules are generated offline, assuming a static network with fault-free links, and entrusting all error-handling functions to the end user. Assuming the network is static is an over-optimistic view, and indeed links tend to fail in practice. We study synthesis of TT schedules on a network in which links fail over time and we assume the switches run a very simple error-recovery protocol once they detect a crashed link. We address the problem of finding a pk; qresistant schedule; namely, one that, assuming the switches run a fixed error-recovery protocol, guarantees that the number of messages that arrive at their destination by the timeout is at least no matter what sequence of at most k links fail. Thus, we maintain the simplicity of the switches while giving a guarantee on the number of messages that meet the timeout. We show how a pk; q-resistant schedule can be obtained using a CEGAR-like approach: find a schedule, decide whether it is pk; q-resistant, and if it is not, use the witnessing fault sequence to generate a constraint that is added to the program. The newly added constraint disallows the schedule to be regenerated in a future iteration while also eliminating several other schedules that are not pk; q-resistant. We illustrate the applicability of our approach using an SMT-based implementation.

  • 142.
    Avritzer, A
    et al.
    Siemens Corporate Research, USA.
    Weyuker, Elaine
    AT and T Labs - Research, USA.
    The Automated Generation of Test Cases using an Extended Domain Based Reliability Model2009Ingår i: Proceedings of the 2009 ICSE Workshop on Automation of Software Test, AST 2009, 2009, s. 44-52, artikel-id 5069040Konferensbidrag (Refereegranskat)
  • 143.
    Awada, Imad Alex
    et al.
    University Politehnica of Bucharest, Romania.
    Cramariuc, Oana
    IT Cenetr for Science and Technology, Romania.
    Mocanu, Irina
    University Politehnica of Bucharest.
    Seceleanu, Cristina
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Kunnappilly, Ashalatha
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Florea, Adina Magda
    University Politehnica of Bucharest, Romania.
    An end- user perspective on the CAMI Ambient and Assisted Living Project2018Ingår i: INTED2018 Proceedings, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we present the outcomes and conclusions obtained by involving seniors from three countries (Denmark, Poland and Romania) in an innovative project funded under the European Ambient Assisted Living (ALL) program. CAMI stands for "Companion with Autonomously Mobile Interface" in "Artificially intelligent ecosystem for self-management and sustainable quality of life in AAL". The CAMI solution enables flexible, scalable and individualised services that support elderly to self-manage their daily life and prolong their involvement in the society (sharing knowledge, continue working, etc). This also allows their informal caregivers (family and friends) to continue working and participating in society while caring for their loved ones. The solution is designed as an innovative architecture that allows for individualized, intelligent self-management which can be tailored to an individual's preferences and needs. A user-centred approach has ranked health monitoring, computer supervised physical exercises and voice based interaction among the top favoured CAMI functionalities. Respondents from three countries (Poland, Romania and Denmark) participated in a multinational survey and a conjoint analysis study.

  • 144.
    Axelsson, Jakob
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    A refined terminology on system-of-systems substructure and constituent system states2019Ingår i: 2019 14th Annual Conference System of Systems Engineering, SoSE 2019, Institute of Electrical and Electronics Engineers Inc. , 2019, s. 31-36Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the field of systems-of-systems (SoS) engineering, there is broad agreement on a few characterizations, and these are currently being standardized. However, many aspects in the field still lack an established terminology. In particular, there are unclarities related to the internal structure of an SoS, and on the internal states of constituent systems. In this paper, a refined terminology is therefore proposed, which covers the internal substructure of an SoS; the states of constituent systems in relation to those substructures; and how it relates to hierarchical levels. This terminology can also be used to classify the characteristics of an SoS through different metrics. The terminology is illustrated through three examples of SoS applications in various domains. 

  • 145.
    Axelsson, Jakob
    Software and Systems Engineering Laboratory, Swedish Institute of Computer Science (SICS), Kista, Sweden .
    A Systematic Mapping of the Research Literature on System-of-Systems Engineering2015Ingår i: 10th Annual Systems of Systems Engineering Conference SOSE, 2015, s. 18-23Konferensbidrag (Refereegranskat)
    Abstract [en]

    The research area systems-of-systems engineering has increased rapidly over the last decade and now contains a substantial body of literature. To get an overview of the field, a systematic mapping of the literature has been done, covering over 3000 papers. It revealed a field massively dominated by US researchers, with an emphasis on military and space systems. A large number of people are involved, but few researchers focus on the area, and citations are fairly low compared to other fields. Important research topics include architecture, modeling and simulation, integration and interoperability, communication, sustainability, and safety and security. There are signs of immaturity within the research area, and it is recommended that existing venues are complemented with an international scientific event with very high standards for submissions.

  • 146.
    Axelsson, Jakob
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. RISE Research Institutes of Sweden, Kista, Sweden.
    An initial analysis of operational emergent properties in a platooning system-of-systems2018Ingår i: 12th Annual IEEE International Systems Conference, SysCon 2018 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2018, s. 1-8Konferensbidrag (Refereegranskat)
    Abstract [en]

    As systems-of-systems start to be more common in commercial applications, an analysis of emergent properties related to utility and cost for all stakeholders becomes critical. This paper describes an approach for this based on network simulation and game theory, which is applied to truck highway platooning. The emergent properties of energy efficiency and transport efficiency are studied as a consequence of the strategies for platoon formation, and it is shown that having information about the route planning of other vehicles has a significant positive effect on the properties. This indicates the need for a mediator in the platooning system-of-systems architecture. Its role is to communicate plans of the constituent systems.

  • 147.
    Axelsson, Jakob
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Architectural Allocation Alternatives and Associated Concerns in Cyber-Physical Systems: A Case Study2015Ingår i: ECSAW '15 Proceedings of the 2015 European Conference on Software Architecture Workshops, 2015, Vol. Article No.15Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cyber-physical systems is an extension of traditional embedded systems, where communication to the outside world is given more emphasis. This leads to a new design space also for software development, allowing new allocation strategies for functionality. In traditional embedded systems, all functionality was inside the product, but now it becomes possible to partition the software between the embedded systems and IT systems outside the product. This paper investigates, through a case study from the automotive domain, possible new allocation alternatives where computation is offloaded from the embedded system to a server, and what additional architectural concerns this leads to, including performance, resource utilization, robustness, and lifecycle aspects. In addition, the paper addresses new opportunities created by allocating functionality outside the embedded systems, and thus making data available for extended services, as well as the larger concerns that result on the organizational level, including new competency in architecture and DevOps.

  • 148.
    Axelsson, Jakob
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Business models and roles for mediating services in a truck platooning system-of-systems2019Ingår i: 2019 14th Annual Conference System of Systems Engineering, SoSE 2019, Institute of Electrical and Electronics Engineers Inc. , 2019, s. 113-118Konferensbidrag (Refereegranskat)
    Abstract [en]

    Platooning of trucks on motorways has been proposed as a method of reducing fuel consumption. It requires communication between the trucks to control the distance between them. However, this system-of-systems (SoS) cannot only contain the trucks, but also needs to include mediating off-board services for match-making to find suitable constellations of trucks, and for creating platooning incentives by distributing the profit made equally among the constituent systems. This paper analyzes what actors in the SoS would be suitable to operate these services, and also business models that cover the cost for their implementation and operation. It concludes that the truck OEMs have a vital role in creating the mediating services, and that a suitable business model would be based on usage fees for the services rather than upfront payment for platooning equipment. 

  • 149.
    Axelsson, Jakob
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Experiences of Using Linked Data and Ontologies for Operational Data Sharing in Systems-of-Systems2019Ingår i: 13th Annual IEEE International Systems Conference SysCon2019, Orlando, Florida, United States, 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper addresses the problem of exchanging complex data between the constituent systems in a system-of-systems. This is necessary to ensure that they have compatible understandings of the world surrounding them and entails a need for semantic interoperability between the constituents. Through a case study of a road construction system-of-systems, the world wide web technologies of linked data and ontologies are explored as a framework for data representation and exchange. This data includes several broad categories, such as assets, interfaces, organizations, capabilities, missions, and observations, as well as various properties of those. It is also discussed how the constituents can use this data for reasoning and decision making. The results have been validated through a simulation-based research prototype of the road construction case, from which experiences are reported.

  • 150.
    Axelsson, Jakob
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. RISE Research Institutes of Sweden, Sweden.
    Game Theory Applications in Systems-of-Systems Engineering: A Literature Review and Synthesis2019Ingår i: Procedia Computer Science, ISSN 1877-0509, E-ISSN 1877-0509, Vol. 153, s. 154-165Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Systems-of-systems (SoS) are becoming increasingly common in more and more domains, spreading from the initial focus on government-controlled areas such as defense to open market industries. This implies that collaborative SoS are becoming more important, where the constituents need to be given incentives to join and remain within the SoS. Game theory has been proposed as a framework to model and analyze such SoS mechanisms. It aims at providing such incentives to the independently operated and managed constituents. This paper presents a systematic literature review on the applications of game theory to SoS engineering, together with a synthesis aiming at capturing the best practices for such an analysis. The main conclusions are that game theory can be applied to SoS in a wide range of application areas, and deal with problems related to acquisition, design, and operations. In particular, the operational formation of SoS are well suited for this kind of analysis, and this often requires the use of simulation techniques. However, most results in the field lack a validation in practice.

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