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Hansson, Jörgen
##### Publications (10 of 47) Show all publications
Rana, R., Staron, M., Berger, C., Hansson, J., Nilsson, M., Torner, F., . . . Hoglund, C. (2014). Selecting software reliability growth models and improving their predictive accuracy using historical projects data. Journal of Systems and Software, 98, 59-78
Open this publication in new window or tab >>Selecting software reliability growth models and improving their predictive accuracy using historical projects data
2014 (English)In: Journal of Systems and Software, ISSN 0164-1212, E-ISSN 1873-1228, Vol. 98, p. 59-78Article in journal (Refereed) Published
##### Abstract [en]

During software development two important decisions organizations have to make are: how to allocate testing resources optimally and when the software is ready for release. SRGMs (software reliability growth models) provide empirical basis for evaluating and predicting reliability of software systems. When using SRGMs for the purpose of optimizing testing resource allocation, the models ability to accurately predict the expected defect inflow profile is useful. For assessing release readiness, the asymptote accuracy is the most important attribute. Although more than hundred models for software reliability have been proposed and evaluated over time, there exists no clear guide on which models should be used for a given software development process or for a given industrial domain. Using defect inflow profiles from large software projects from Ericsson, Volvo Car Corporation and Saab, we evaluate commonly used SRGMs for their ability to provide empirical basis for making these decisions. We also demonstrate that using defect intensity growth rate from earlier projects increases the accuracy of the predictions. Our results show that Logistic and Gompertz models are the most accurate models; we further observe that classifying a given project based on its expected shape of defect inflow help to select the most appropriate model.

Elsevier, 2014
##### Keywords
Embedded software; Defect inflow; Software reliability growth models
##### National Category
Computer and Information Sciences
##### Identifiers
urn:nbn:se:liu:diva-112809 (URN)10.1016/j.jss.2014.08.033 (DOI)000344421900005 ()
##### Note

Funding Agencies|Vinnova; Volvo Cars [DIARIENR: 2011-04438]

Available from: 2015-01-08 Created: 2014-12-17 Last updated: 2018-01-11
Amirijoo, M., Gunnarsson, S., Hansson, J. & Son, S. H. (2008). Quantifying and Suppressing the Measurement Disturbance in Feedback Controlled Real-Time Systems. Real-time systems, 40(1), 44-76
Open this publication in new window or tab >>Quantifying and Suppressing the Measurement Disturbance in Feedback Controlled Real-Time Systems
2008 (English)In: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 40, no 1, p. 44-76Article in journal (Refereed) Published
##### Abstract [en]

In the control of continuous and physical systems, the controlled system is sampled sufficiently fast to capture the dynamics of the system. In general, this property cannot be applied to the control of computer systems as the measured variables are often computed over a data set, e.g., deadline miss ratio. In this paper we quantify the disturbance present in the measured variable as a function of the data set size and the sampling period, and we propose a feedback control structure that suppresses the measurement disturbance. The experiments we have carried out show that a controller using the proposed control structure outperforms a traditional control structure with regard to performance reliability.

Springer, 2008
##### Keywords
Adaptive scheduling, Feedback control, Measurement disturbance, System disturbance
##### National Category
Control Engineering
##### Identifiers
urn:nbn:se:liu:diva-12639 (URN)10.1007/s11241-008-9048-3 (DOI)
Available from: 2007-10-17 Created: 2007-10-17 Last updated: 2017-12-14
Tesanovic, A., Amirijoo, M., Nilsson, D., Norin, H. & Hansson, J. (2007). Dynamically Reconfigurable QoS-aware Embedded Systems (2ed.). In: Raj Kamal (Ed.), Embedded Systems: Status and Perspective: . USA: American Scientific Publisher
Open this publication in new window or tab >>Dynamically Reconfigurable QoS-aware Embedded Systems
2007 (English)In: Embedded Systems: Status and Perspective / [ed] Raj Kamal, USA: American Scientific Publisher , 2007, 2, p. -633Chapter in book (Other academic)
##### Abstract [en]

This book, equally applicable for a CSE or ECE course, gives an extensive account of Embedded Systems, keeping a balanced coverage of hardware and software concepts. Adhering to syllabus needs, this title is ‘microprocessor’ and ‘software design methodology’ specific, giving due weightage to architecture, programming and design aspects.

##### Place, publisher, year, edition, pages
USA: American Scientific Publisher, 2007 Edition: 2
##### Keywords
Embedded system, QoS, reconfigurable system
##### National Category
Computer Sciences
##### Identifiers
urn:nbn:se:liu:diva-38144 (URN)41945 (Local ID)978-0-07-340456-1 (ISBN)0-07-340456-X (ISBN)41945 (Archive number)41945 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2018-01-13Bibliographically approved
Gustafsson, T., Tesanovic, A., Du, Y. & Hansson, J. (2007). Engineering Active Behavior of Embedded Software to Improve Evolution and Performance: an Aspect-Oriented Approach. In: The 22nd Annual ACM Symposium on Applied Computing,2007: . Paper presented at ACM symposium on Applied computing. New York: ACM
Open this publication in new window or tab >>Engineering Active Behavior of Embedded Software to Improve Evolution and Performance: an Aspect-Oriented Approach
2007 (English)In: The 22nd Annual ACM Symposium on Applied Computing,2007, New York: ACM , 2007Conference paper, Published paper (Refereed)
##### Abstract [en]

In this paper we propose a novel aspect-oriented scheme for implementing active behavior in embedded software with requirements on data freshness. The scheme improves system performance by combining active behavior in terms of event-condition-action (ECA) rules and on-demand updating. We design and implement the scheme in terms of aspects, thereby exploiting aspect-oriented programming technology to efficiently handle crosscutting nature of active behavior. The benefits of our approach are demonstrated using a case study of an embedded database system called COMET. Namely, simulations on the COMET database indicate that its performance increases by incorporating our scheme. Furthermore, using the COMET example we show that aspect-oriented implementation of active behavior has benefits when it comes to easier evolution of the system.

##### Place, publisher, year, edition, pages
New York: ACM, 2007
##### National Category
Computer Sciences
##### Identifiers
urn:nbn:se:liu:diva-35576 (URN)10.1145/1244002.1244155 (DOI)27690 (Local ID)1-59593-480-4 (ISBN)27690 (Archive number)27690 (OAI)
##### Conference
ACM symposium on Applied computing
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2018-01-13
Amirijoo, M., Hansson, J., Son, S. H. & Gunnarsson, S. (2007). Experimental Evaluation of Linear Time-Invariant Models for Feedback Performance Control in Real-Time Systems. Real-time systems, 35(3), 209-238
Open this publication in new window or tab >>Experimental Evaluation of Linear Time-Invariant Models for Feedback Performance Control in Real-Time Systems
2007 (English)In: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 35, no 3, p. 209-238Article in journal (Refereed) Published
##### Abstract [en]

In recent years a new class of soft real-time applications operating in unpredictable environments has emerged. Typical for these applications is that neither the resource requirements nor the arrival rates of service requests are known or available a priori. It has been shown that feedback control is very effective to support the specified performance of dynamic systems that are both resource insufficient and exhibit unpredictable workloads. To efficiently use feedback control scheduling it is necessary to have a model that adequately describes the behavior of the system. In this paper we experimentally evaluate the accuracy of four linear time-invariant models used in the design of feedback controllers. We introduce a model (DYN) that captures additional system dynamics, which a previously published model (STA) fails to include. The accuracy of the models are evaluated by validating the models with regard to measured data from the controlled system and through a set of experiments where we evaluate the performance of a set of feedback control schedulers tuned using these models. From our evaluations we conclude that second order models (e.g., DYN) are more accurate than first order models (e.g. STA). Further we show that controllers tuned using second order models perform better than controllers tuned using first order models.

##### Keywords
Feedback control scheduling, Modeling, Model validation, System identification
##### National Category
Control Engineering
##### Identifiers
urn:nbn:se:liu:diva-12636 (URN)10.1007/s11241-006-9008-8 (DOI)
Available from: 2007-10-17 Created: 2007-10-17 Last updated: 2017-12-14
Gustafsson, T. & Hansson, J. (2007). Performance Evaluations and Estimations of Workload of On-Demand Updates in Soft Real-Time Systems. In: 13th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, 2007. Paper presented at 13th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications(RTCSA 2007), 21-24 August 2007, Daegu, South Korea (pp. 337-344). IEEE Computer Society
Open this publication in new window or tab >>Performance Evaluations and Estimations of Workload of On-Demand Updates in Soft Real-Time Systems
2007 (English)In: 13th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, 2007, IEEE Computer Society, 2007, p. 337-344Conference paper, Published paper (Refereed)
##### Abstract [en]

Data being used in real-time systems must be up-to-date to produce correct results. The use of outdated data can have catastrophic consequences since calculated control signals are based on stale data. Two distinct methods to update data exist: (i) dedicated tasks (DT) update data items, and (ii) on-demand (OD) updating being a conditioned part of the execution flow of tasks. On-demand updating has not been studied in terms of CPU utilization analysis for real-time systems. This paper studies on-demand updating in terms of (i) imposed workload and compares the workload to deferrable scheduling (DS), and (ii) analytical formula for estimating workload to be used in CPU utilization based schedulability tests. It is found that on-demand updating uses less workload for updates compared to DS, which suggests on-demand updating should be used for resource constrained systems. However, using on-demand updating makes the execution times of updates unpredictable, which currently gives two possibilities (i) be pessimistic and assume all updates always execute or (ii) be less pessimistic but estimate the times between executions of updates. This paper devises a formula for such estimates and compares their result to approach (i). Evaluations show the formula can be useful for soft real-time systems.

##### Place, publisher, year, edition, pages
IEEE Computer Society, 2007
##### National Category
Computer Sciences
##### Identifiers
urn:nbn:se:liu:diva-39314 (URN)10.1109/RTCSA.2007.55 (DOI)000250109000040 ()47888 (Local ID)978-0-7695-2975-2 (ISBN)47888 (Archive number)47888 (OAI)
##### Conference
13th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications(RTCSA 2007), 21-24 August 2007, Daegu, South Korea
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2018-01-13
Amirijoo, M., Son, S. H. & Hansson, J. (2007). QoD Adaptation for Achieving Lifetime Predictability of WSN Nodes Communicating over Satellite Links. In: International Conference on Networked Sensing Systems INSS,2007: . Paper presented at Networked Sensing Systems (pp. 19-26). IEEE
Open this publication in new window or tab >>QoD Adaptation for Achieving Lifetime Predictability of WSN Nodes Communicating over Satellite Links
2007 (English)In: International Conference on Networked Sensing Systems INSS,2007, IEEE , 2007, p. 19-26Conference paper, Published paper (Refereed)
##### Abstract [en]

In this paper we propose an architecture consisting of a particular type of node, namely a communication server that collects and aggregates data, and establishes a link between the users and the sensor nodes through satellite communication. A key challenge with satisfying a lifetime requirement of the communication server is the unpredictability of the sensor data volume arriving at the communication server and the transmission power of the satellite terminal. To provide lifetime predictability we propose an approach that automatically adjusts the quality of the data such that the specified lifetime if achieved. We have shown through an extensive evaluation that the approach manages to provide an actual lifetime within 2% of the specified lifetime despite variations in workload and communication link quality.

IEEE, 2007
##### Keywords
wireless sensor network
##### National Category
Computer Sciences
##### Identifiers
urn:nbn:se:liu:diva-37483 (URN)10.1109/INSS.2007.4297382 (DOI)36167 (Local ID)1-4244-1231-5 (ISBN)36167 (Archive number)36167 (OAI)
##### Conference
Networked Sensing Systems
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2018-01-13
Amirijoo, M., Brännström, P., Hansson, J., Gunnarsson, S. & Son, S. (2007). Toward Adaptive Control of QoS-Importance Decoupled Real-Time Systems. In: IEEE International Workshop on Feedback Control Implementation and Design in Computing Systems and Networks,2007.
Open this publication in new window or tab >>Toward Adaptive Control of QoS-Importance Decoupled Real-Time Systems
2007 (English)In: IEEE International Workshop on Feedback Control Implementation and Design in Computing Systems and Networks,2007, 2007Conference paper, Published paper (Refereed)
##### Abstract [en]

This paper deals with differentiated services in real-time systems. Tasks submitted to a real-time system are differentiated with respect to importance and QoS requirements. We use feedback control to enforce the requirements in QoS and ensure a hierarchical admission policy based on the importance of the tasks. The results show that the requirements are met during steady state when the workload is constant. The feedback control approach does not satisfactorily manage QoS when there is a sudden and significant workload change (transient state) due to the time-variant nature of the system. To address this, we present preliminary and promising results using adaptive control, and report on some challenges we are facing when applying the theory.

##### Keywords
real-time system, quality of service, QoS, control theory, system identification, differentiated services
##### National Category
Computer Sciences
##### Identifiers
urn:nbn:se:liu:diva-38143 (URN)41926 (Local ID)41926 (Archive number)41926 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2018-01-13
Gustafsson, T. & Hansson, J. (2006). Data Freshness and Overload Handling in Embedded Systems. In: 12th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, 2006. Paper presented at 12th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications(RTCSA 2006), 16-18 August 2006, Sydney, Australia (pp. 173-182). Los Alamitos, CA, USA: IEEE Computer Society
Open this publication in new window or tab >>Data Freshness and Overload Handling in Embedded Systems
2006 (English)In: 12th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, 2006, Los Alamitos, CA, USA: IEEE Computer Society, 2006, p. 173-182Conference paper, Published paper (Refereed)
##### Abstract [en]

In this paper we consider data freshness and overload handling in embedded systems. The requirements on data management and overload handling are derived from an engine control software. Data items need to be up-to-date, and to achieve this data dependencies must be considered, i.e., updating a data item requires other data items are up-to-date. We also note that a correct result of a calculation can in some cases be calculated using a subset of the inputs. Hence, data dependencies can be divided into required and not required data items, e.g., only a subset of data items affecting the fuel calculation in an engine control needs to be calculated during a transient overload in order to reduce the number of calculations. Required data items must always be up-to-date, whereas not required data items can be stale. We describe an algorithm that dynamically determines which data items need to be updated taking workload, data freshness, and data relationships into consideration. Performance results show that the algorithm suppresses transient overloads better than $(m,k)$- and skip-over scheduling combined with established algorithms to update data items. The performance results are collected from an implementation of a real-time database on the real-time operating system $\mu$C/OS-II. To investigate whether the system is occasionally overloaded an offline analysis algorithm estimating period times of updates is presented.

##### Place, publisher, year, edition, pages
Los Alamitos, CA, USA: IEEE Computer Society, 2006
##### National Category
Computer Sciences
##### Identifiers
urn:nbn:se:liu:diva-35575 (URN)10.1109/RTCSA.2006.25 (DOI)000240851900024 ()27689 (Local ID)0-7695-2676-4 (ISBN)27689 (Archive number)27689 (OAI)
##### Conference
12th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications(RTCSA 2006), 16-18 August 2006, Sydney, Australia
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2018-01-13
Gustafsson, T., Hansson, J., Göras, A., Gäddevik, J. & Holmberg, D. (2006). Database Functionality in Engine Management System. In: SAE World Congress,2006. Proceedings of Software/Hardware Systems SAE World Congress 2006: SAE
Open this publication in new window or tab >>Database Functionality in Engine Management System
2006 (English)In: SAE World Congress,2006, Proceedings of Software/Hardware Systems SAE World Congress 2006: SAE , 2006Conference paper, Published paper (Refereed)
##### Abstract [en]

Embedded systems of today need to manage more data than ever before. The main reasons for the increase in number of data items are increased functional requirements on the software. With a larger amount of data to manage comes the problems of storing data and its meta-information, sharing between programmers which data items exist, and ensuring freshness and consistency requirements of the data items. In this work we focus on efficient data management in embedded systems, and develop a database for such systems. The database has support for transactions, snapshots, and data freshness. We argue that the software maintenance efforts can be reduced using a database, and our performance results show that the performance can be increased without affecting consistency of data values.

##### Place, publisher, year, edition, pages
Proceedings of Software/Hardware Systems SAE World Congress 2006: SAE, 2006
##### National Category
Computer Sciences
##### Identifiers
urn:nbn:se:liu:diva-35574 (URN)27688 (Local ID)27688 (Archive number)27688 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2018-01-13

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