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  • 1. Alaves, Dimas
    et al.
    Machado, Renato
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    da Costa, Daniel Benevides
    Legg, Andrei Piccinini
    Uchoa-Filho, Bartolomeu F.
    A dynamic hybrid antenna/relay selection scheme for the multiple-access relay channel2014In: 2014 11TH INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATIONS SYSTEMS (ISWCS), IEEE , 2014, p. 594-599Conference paper (Refereed)
    Abstract [en]

    We propose a dynamic hybrid antenna/relay selection scheme for multiple-access relay systems. The proposed scheme aims to boost the system throughput while keeping a good error performance. By using the channel state information, the destination node performs a dynamic selection between the signals provided by the multi-antenna relay, located in the inter-cell region, and the relay nodes geographically distributed over the cells. The multi-antenna relay and the single-antenna relay nodes employ the decode-remodulate-and-forward and amplify-and-forward protocols, respectively. Results reveal that the proposed scheme offers a good tradeoff between spectral efficiency and diversity gain, which is one of the main requirements for the next generation of wireless communications systems.

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  • 2. Alves, Dimas I.
    et al.
    Machado, Renato
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Legg, Andrei P.
    Uchoa-Filho, Bartolomeu F.
    Cooperative multiple-access scheme with antenna selection and incremental relaying2014In: 2014 INTERNATIONAL TELECOMMUNICATIONS SYMPOSIUM (ITS), São Paulo: IEEE , 2014Conference paper (Refereed)
    Abstract [en]

    A cooperative multiple-access scheme for wireless communications systems with antenna selection and incremental relaying is proposed. The scheme aims to improve the system throughput while preserving good performance in terms of bit error rate. The system consists of N nodes which send their information to both the destination node and the multiple-antenna relay station. Based on the channel state information, the destination node decides whether or not relaying will be performed. When the relaying is performed, the decode-remodulate-and-forward protocol is used with the best antenna. Results reveal that the proposed scheme achieves a good tradeoff between throughput and bit error rate, which makes suitable to be considered for multi-user networks.

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  • 3.
    Alves, Dimas I
    et al.
    Fed Univ Pampa UNIPAMPA, BRA.
    Palm, Brna
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Pettersson, Mats
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Vu, Viet Thuy
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Machado, Renato
    Aeronaut Inst Technol ITA, BRA.
    Uchoa-Filho, Bartolomeu F.
    Fed Univ Santa Catarina UFSC, BRA.
    Dammert, Patrik
    Saab Elect Def Syst, SWE.
    Hellsten, Hans
    Saab Elect Def Syst, SWE.
    A Statistical Analysis for Wavelength-Resolution SAR Image Stacks2020In: IEEE Geoscience and Remote Sensing Letters, ISSN 1545-598X, E-ISSN 1558-0571, Vol. 17, no 2, p. 227-231Article in journal (Refereed)
    Abstract [en]

    This letter presents a clutter statistical analysis for stacks of wavelength-resolution synthetic aperture radar (SAR) images. Each image stack consists of SAR images generated by the same sensor, using the same flight track illuminating the same scene but with a time separation between the illuminations. We test three candidate statistical distributions for time changes in the stack, namely, Rician, Rayleigh, and log-normal. The tests results reveal that the Rician distribution is a very good candidate for modeling stack of wavelength-resolution SAR images, where 98.59 & x0025; of the tested samples passed the Anderson-Darling (AD) goodness-of-fit test. Also, it is observed that the presence of changes in the ground scene is related to the tested samples that have failed in the AD test for the Rician distribution hypothesis.

  • 4.
    Anco, S.
    et al.
    Brock Univ, Dept Math & Stat, St Catharines, ON L2S 3A1, Canada..
    Avdonina, E. D.
    Ufa State Aviat Tech Univ, Lab Grp Anal Math Models Nat & Engn Sci, Ufa 450000, Russia..
    Gainetdinova, A.
    Ufa State Aviat Tech Univ, Lab Grp Anal Math Models Nat & Engn Sci, Ufa 450000, Russia..
    Galiakberova, L. R.
    Ufa State Aviat Tech Univ, Lab Grp Anal Math Models Nat & Engn Sci, Ufa 450000, Russia..
    Ibragimov, Nail
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Wolf, T.
    Brock Univ, Dept Math & Stat, St Catharines, ON L2S 3A1, Canada..
    Symmetries and conservation laws of the generalized Krichever-Novikov equation2016In: Journal of Physics A: Mathematical and Theoretical, ISSN 1751-8113, E-ISSN 1751-8121, Vol. 49, no 10, article id 105201Article in journal (Refereed)
    Abstract [en]

    A computational classification of contact symmetries and higher-order local symmetries that do not commute with t, x, as well as local conserved densities that are not invariant under t, x is carried out for a generalized version of the Krichever-Novikov (KN) equation. Several new results are obtained. First, the KN equation is explicitly shown to have a local conserved density that contains t, x. Second, apart from the dilational point symmetries known for special cases of the KN equation and its generalized version, no other local symmetries with low differential order are found to contain t, x. Third, the basic Hamiltonian structure of the KN equation is used to map the local conserved density containing t, x into a nonlocal symmetry that contains t, x. Fourth, a recursion operator is applied to this nonlocal symmetry to produce a hierarchy of nonlocal symmetries that have explicit dependence on t, x. When the inverse of the Hamiltonian map is applied to this hierarchy, only trivial conserved densities are obtained.

  • 5. Anco, S.
    et al.
    Ibragimov, Nail
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Imamutdinova, K.V.
    Karimova, E.N.
    Solutions of gasdynamic equations associated with classical and new conservation laws2015In: Applied Mathematics and Computation, ISSN 0096-3003, E-ISSN 1873-5649, Vol. 268, p. 52-58Article in journal (Refereed)
    Abstract [en]

    Exact solutions of the one-dimensional gasdynamic equations are constructed by applying the method of conservation laws to all point-wise conserved vectors of the equations under consideration. © 2015 Elsevier Inc.

  • 6.
    Barbosa, Ludwig
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Rasch, J.
    Molflow, Gothenburg, SWE.
    Carlstrom, A.
    RUAG Space AB, SWE.
    Pettersson, Mats
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Vu, Viet Thuy
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    A Simulation Study of the Effect of Ionospheric Vertical Gradients on the Neutral Bending Angle Error for GNSS Radio Occultation2017In: Progress in Electromagnetics Research Symposium, IEEE , 2017, p. 1540-1545Conference paper (Refereed)
    Abstract [en]

    Radio Occultation based on Global Navigation Satellite System signals (GNSS RO) is an increasingly important remote sensing technique. Its measurements are used to derive parameter of the Earth's atmosphere, e.g., pressure, temperature and humidity, with good accuracy. The systematic residual error present on the data processing is related to ionospheric conditions, such as the distribution of electrons and the resultant vertical gradient. This study investigates the relationship between these parameters and the residual ionospheric error (RIE) on the retrieved bending angle in the stratosphere. Chapman function combined to sinusoidal perturbations are used to model electron density profiles and compared to RO retrievals of the ionosphere to perform the investigation. The results confirmed that the major ionospheric influence on the retrieval error is related to the F-layer electron density peak, whereas small-scale vertical structures play a minor role.

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  • 7. Barbosa, V.L.
    et al.
    E.R., Schlosser
    Machado, Renato
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    F. G., Ferreira
    S. M., Tolfo
    M. V. T., Heckler
    Linear Array Design with Switched Beams for Wireless Communications Systems2015In: International Journal of Antennas and Propagation, ISSN 1687-5869, E-ISSN 1687-5877, Vol. 2015, article id 278160Article in journal (Refereed)
  • 8.
    Bechter, Jonathan
    et al.
    Ulm Univ, DEU.
    Rameez, Muhammad
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Waldschmidt, Christian
    Ulm Univ, DEU.
    Analytical and Experimental Investigations on Mitigation of Interference in a DBF MIMO Radar2017In: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 65, no 5, p. 1727-1734Article in journal (Refereed)
    Abstract [en]

    As driver assistance systems and autonomous driving are on the rise, radar sensors become a common device for automobiles. The high sensor density leads to the occurrence of interference, which decreases the detection capabilities. Here, digital beamforming (DBF) is applied to mitigate such interference. A DBF system requires a calibration of the different receiving channels. It is shown how this calibration completely changes the DBF beam pattern required to cancel interferences, if the system has no IQ receiver. Afterward, the application of DBF on a multiple-input multiple-output (MIMO) radar is investigated. It is shown that only the real aperture and not the virtual one can be used for interference suppression, leading to wide notches in the pattern. However, for any target the large virtual aperture can be exploited, even if interferers are blinded out. Moreover, the wide notches for interference suppression of the real aperture appear narrow in the virtual aperture for target localization. The results are verified by measurements with time-multiplexing MIMO radar.

  • 9.
    Berner, Jessica
    et al.
    Blekinge Institute of Technology, Faculty of Health Sciences, Department of Health.
    Rennemark, Mikael
    Blekinge Institute of Technology, Faculty of Health Sciences, Department of Health.
    Jogreus, Claes
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Anderberg, Peter
    Blekinge Institute of Technology, Faculty of Health Sciences, Department of Health.
    Sköldunger, Anders
    Wahlberg, Maria
    Elmståhl, Sölve
    Berglund, Johan
    Blekinge Institute of Technology, Faculty of Health Sciences, Department of Health.
    Factors influencing Internet usage in older adults (65 years and above) living in rural and urban Sweden2015In: Health Informatics Journal, ISSN 1460-4582, E-ISSN 1741-2811, Vol. 21, no 3, p. 237-249Article in journal (Refereed)
    Abstract [en]

    Older adults living in rural and urban areas have shown to distinguish themselves in technology adoption; a clearer profile of their Internet use is important in order to provide better technological and health-care solutions. Older adults' Internet use was investigated across large to midsize cities and rural Sweden. The sample consisted of 7181 older adults ranging from 59 to 100 years old. Internet use was investigated with age, education, gender, household economy, cognition, living alone/or with someone and rural/urban living. Logistic regression was used. Those living in rural areas used the Internet less than their urban counterparts. Being younger and higher educated influenced Internet use; for older urban adults, these factors as well as living with someone and having good cognitive functioning were influential. Solutions are needed to avoid the exclusion of some older adults by a society that is today being shaped by the Internet.

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  • 10.
    Beuter, Viviane
    et al.
    Universidade Federal de Santa Catarina, BRA.
    Gonçalves, Daniel
    Universidade Federal de Santa Catarina, BRA.
    Öinert, Johan
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Royer, Danilo
    Universidade Federal de Santa Catarina, BRA.
    Simplicity of skew inverse semigroup rings with applications to Steinberg algebras and topological dynamics2019In: Forum mathematicum, ISSN 0933-7741, E-ISSN 1435-5337, Vol. 31, no 3, p. 543-562Article in journal (Refereed)
    Abstract [en]

    Given a partial action π of an inverse semigroup S on a ring A {\mathcal{A}}, one may construct its associated skew inverse semigroup ring A π S {\mathcal{A}\rtimes-{\pi}S}. Our main result asserts that, when A {\mathcal{A}} is commutative, the ring A π S {\mathcal{A}\rtimes-{\pi}S} is simple if, and only if, A {\mathcal{A}} is a maximal commutative subring of A π S {\mathcal{A}\rtimes-{\pi}S} and A {\mathcal{A}} is S-simple. We apply this result in the context of topological inverse semigroup actions to connect simplicity of the associated skew inverse semigroup ring with topological properties of the action. Furthermore, we use our result to present a new proof of the simplicity criterion for a Steinberg algebra A R (g) {A-{R}(\mathcal{G})} associated with a Hausdorff and ample groupoid g {\mathcal{G}}. © 2018 Walter de Gruyter GmbH, Berlin/Boston.

  • 11.
    Bjorklund, Svante
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Johansson, Tommy
    Swedish Def Res Agcy FOI, SE-58111 Linkoping, Sweden..
    Petersson, Henrik
    Swedish Def Res Agcy FOI, SE-58111 Linkoping, Sweden..
    Target Classification in Perimeter Protection with a Micro-Doppler Radar2016In: 2016 17TH INTERNATIONAL RADAR SYMPOSIUM (IRS), 2016Conference paper (Refereed)
    Abstract [en]

    In security surveillance at the perimeter of critical infrastructure, such as airports and power plants, approaching objects have to be detected and classified. Especially important is to distinguish between humans, animals and vehicles. In this paper, micro-Doppler data (from movement of internal parts of the target) have been collected with a small radar of a low complexity and cost-effective type. From time-velocity diagrams of the data, some physical features have been extracted and used in a support vector machine classifier to distinguish between the classes "human", "animal" and "man-made object". Both the type of radar and the classes are suitable for perimeter protection. The classification result are rather good, 77% correct classification. Particularly interesting is the surprisingly good ability to distinguish between humans and animals. This also indicates that we can choose to have limitations in the radar and still solve the classification task.

  • 12.
    Bjorklund, Svante
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Petersson, Henrik
    Swedish Def Res Agcy FOI, SE-58111 Linkoping, Sweden..
    Hendeby, Gustaf
    Swedish Def Res Agcy FOI, SE-58111 Linkoping, Sweden.;Linkoping Univ, SE-58183 Linkoping, Sweden..
    Features for micro-Doppler based activity classification2015In: IET radar, sonar & navigation, ISSN 1751-8784, E-ISSN 1751-8792, Vol. 9, no 9, p. 1181-1187Article in journal (Refereed)
    Abstract [en]

    Safety and security applications benefit from better situational awareness. Radar micro-Doppler signatures from an observed target carry information about the target's activity, and have potential to improve situational awareness. This article describes, compares, and discusses two methods to classify human activity based on radar micro-Doppler data. The first method extracts physically interpretable features from the time-velocity domain such as the main cycle time and properties of the envelope of the micro-Doppler spectra and use these in the classification. The second method derives its features based on the components with the most energy in the cadence-velocity domain (obtained as the Fourier transform of the time-velocity domain). Measurements from a field trial show that the two methods have similar activity classification performance. It is suggested that target base velocity and main limb cadence frequency are indirect features of both methods, and that they do often alone suffice to discriminate between the studied activities. This is corroborated by experiments with a reduced feature set. This opens up for designing new more compact feature sets. Moreover, weaknesses of the methods and the impact of non-radial motion are discussed.

  • 13.
    Björklund, Svante
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Clutter Properties for a Side-Looking Radar with Planar Regular and Irregular Subarrays2015In: 2015 16TH INTERNATIONAL RADAR SYMPOSIUM (IRS), 2015, p. 730-735Conference paper (Refereed)
    Abstract [en]

    The effect of the subarray design in a side-looking moving radar with a planar antenna on some clutter properties which are important for suppressing the clutter with STAP (Space-Time Adaptive Processing) is investigated by simulations. These properties are interference DOA Doppler Spectrum (DDS) and clutter rank. The conclusions from the work is that irregular antennas give less clutter in the DDS and that larger subarrays give lower clutter rank.

  • 14.
    Björklund, Svante
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences. Swedish Defence Research Agency (FOI ).
    Signal Processing for Radar with Array Antennas and for Radar with Micro-Doppler Measurements2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Radar (RAdio Detection And Ranging) uses radio waves to detect the presence of a target and measure its position and other properties. This sensor has found many civilian and military applications due to advantages such as possible large surveillance areas and operation day and night and in all weather. The contributions of this thesis are within applied signal processing for radar in two somewhat separate research areas: 1) radar with array antennas and 2) radar with micro-Doppler measurements.

    Radar with array antennas: An array antenna consists of several small antennas in the same space as a single large antenna. Compared to a traditional single-antenna radar, an array antenna radar gives higher flexibility, higher capacity, several radar functions simultaneously and increased reliability, and makes new types of signal processing possible which give new functions and higher performance.

    The contributions on array antenna radar in this thesis are in three different problem areas. The first is High Resolution DOA (Direction Of Arrival) Estimation (HRDE) as applied to radar and using real measurement data. HRDE is useful in several applications, including radar applications, to give new functions and improve the performance. The second problem area is suppression of interference (clutter, direct path jamming and scattered jamming) which often is necessary in order to detect and localize the target. The thesis presents various results on interference signal properties, antenna geometry and subarray design, and on interference suppression methods. The third problem area is measurement techniques for which the thesis suggests two measurement designs, one for radar-like measurements and one for scattered signal measurements.

    Radar with micro-Doppler measurements: There is an increasing interest and need for safety, security and military surveillance at short distances. Tasks include detecting targets, such as humans, animals, cars, boats, small aircraft and consumer drones; classifying the target type and target activity; distinguishing between target individuals; and also predicting target intention. An approach is to employ micro-Doppler radar to perform these tasks. Micro-Doppler is created by the movement of internal parts of the target, like arms and legs of humans and animals, wheels of cars and rotors of drones.

    Using micro-Doppler, this thesis presents results on feature extraction for classification; on classification of targets types (humans, animals and man-made objects) and human gaits; and on information in micro-Doppler signatures for re-identification of the same human individual. It also demonstrates the ability to use different kinds of radars for micro-Doppler measurements. The main conclusion about micro-Doppler radar is that it should be possible to use for safety, security and military surveillance applications.

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  • 15.
    Björklund, Svante
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences. Swedish Defence Research Agency (FOI ).
    Three-Dimensional DPCA with Rotating Antenna for Clutter Cancellation2015In: 2015 IEEE Radar Conference (RadarCon), Institute of Electrical and Electronics Engineers (IEEE), 2015, p. 1579-1583Conference paper (Refereed)
    Abstract [en]

    In moving radar, e.g. airborne radar, the clutter from land and sea needs to be suppressed in order to detect the target. One approach to total cancellation of the clutter is Displaced Phase Center Antenna (DPCA). DPCA assumes that the antenna elements are positioned on a line parallel to the velocity vector of the radar platform so that the elements can take each others positions at different points of times. In a previous paper we saw that it is possible with other antenna element positions, e.g. in three dimensions, for a total cancellation of the clutter. We arrived at a theoretical condition for this. In this new paper we extend the condition with rotating array antennas. We also formulate an optimization problem for, besides the clutter cancellation, also maximizing the target signal.

  • 16.
    Björklund, Svante
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Grahn, Per
    Nelander, Anders
    Pettersson, Mats
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Measurement of Rank and Other Properties of Direct and Scattered Signals2016In: International Journal of Antennas and Propagation, ISSN 1687-5869, E-ISSN 1687-5877, Vol. 2016, article id 5483547Article in journal (Refereed)
    Abstract [en]

    We have designed an experiment for low-cost indoor measurements of rank and other properties of direct and scattered signals with radar interference suppression in mind. The signal rank is important also in many other applications, for example, DOA (Direction of Arrival) estimation, estimation of the number of and location of transmitters in electronic warfare, and increasing the capacity in wireless communications. In real radar applications, such measurements can be very expensive, for example, involving airborne radars with array antennas. We have performed the measurements in an anechoic chamber with several transmitters, a receiving array antenna, and a moving reflector. Our experiment takes several aspects into account: transmitted signals with different correlation, decorrelation of the signals during the acquisition interval, covariance matrix estimation, noise eigenvalue spread, calibration, near-field compensation, scattering in a rough surface, and good control of the influencing factors. With our measurements we have observed rank, DOA spectrum, and eigenpatterns of direct and scattered signals. The agreement of our measured properties with theoretic and simulated results in the literature shows that our experiment is realistic and sound. The detailed description of our experiment could serve as help for conducting other well-controlled experiments. © Copyright 2016 Svante Björklund et al.

  • 17.
    Björklund, Svante
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Nelander, Anders
    Swedish Def Res Agcy FOI, SWE.
    Pettersson, Mats
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences. Blekinge Inst Technol, Karlskrona, Sweden..
    Fast-Time and Slow-Time Space-Time Adaptive Processing for Bistatic Radar Interference Suppression2015In: 2015 IEEE INTERNATIONAL RADAR CONFERENCE (RADARCON), IEEE Communications Society, 2015, p. 674-678Conference paper (Refereed)
    Abstract [en]

    In bistatic radar with transmitter and receiver geographically separated the interference from ground clutter and the direct path signal transmitter-receiver will be strong and must be suppressed in order to detect the target. We apply FT-STAP (Fast-Time Space Time Adaptive Processing) to the suppression, which is unusual, and compare with conventional ST-STAP (Slow-Time STAP) by simulations in order to see whether FT-STAP is an alternative to ST-STAP. The performance of FT-STAP is much worse than of ST-STAP. We give an explanation for this, which also may be the basis for large improvements of FT-STAP. Moreover, we suggest two new performance measures.

  • 18. Björklund, Svante
    et al.
    Pettersson, Mats
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    A three-dimensional displaced phase center antenna condition for clutter cancellation2014In: Proceedings of the IEEE Sensor Array and Multichannel Signal Processing Workshop, IEEE , 2014, p. 305-308Conference paper (Refereed)
    Abstract [en]

    In moving radar, e.g. airborne radar, the clutter from land and sea needs to be suppressed in order to detect the target. One approach to total cancellation of the clutter is Displaced Phase Center Antenna (DPCA). DPCA assumes that the antenna elements are positioned on a line parallel to the velocity vector of the radar platform so that the elements can take each others positions at different points of times. This paper theoretically investigates if it is possible with other antenna element positions, e.g. in three dimensions, for a total cancellation of the clutter. We arrive at a condition which conforms to the principle that the elements should take each others positions at different times but allows other antennas than the single line parallel to the velocity vector. Our condition could be used as constraints in an optimization problem where the target signal performance is optimized. The multipulse DPCA condition is one solution to our condition.We also give two examples of non-linear antennas fulfilling our condition.

  • 19.
    Björklund, Svante
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Rydell, Joakim
    Totalforsvarets forskningsinstitut, SWE.
    Micro-doppler classification with boosting in perimeter protection2017In: IET Conference Publications, Institution of Engineering and Technology , 2017, no CP728Conference paper (Refereed)
    Abstract [en]

    In security surveillance at the perimeter of critical infrastructure, such as airports and power plants, approaching objects have to be detected and classified. Especially important is to distinguish between humans, animals and vehicles. In this paper, micro-Doppler data (from movement of internal parts of the target) have been collected with a small radar. From time-velocity diagrams of the data, physical features have been extracted and used in a Boosting classifier to distinguish between the classes "human", "animal" and "man-made object". This type of classifier has received much attention lately, but not in radar micro-Doppler classification. The classification result on the current data reaches 90% correct classification with this classifier. The ability to distinguish between humans and animals is good on this data. This classifier type gives insight into the classifier and the utilized features, and is easy to use. A comparison with a SVM (Support Vector Machine) classifier, which is common for micro-Doppler, has also been performed. © 2017 Institution of Engineering and Technology. All rights reserved.

  • 20. Boszhkov, Yuri
    et al.
    Freire, Igor
    Ibragimov, Nail H.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Group analysis of the Novikov equation2014In: Computational and Applied Mathematics, ISSN 2238-3603, E-ISSN 1807-0302, Vol. 33, no 1, p. 193-202Article in journal (Refereed)
    Abstract [en]

    We find the Lie point symmetries of the Novikov equation and demonstrate that it is strictly self-adjoint. Using the self-adjointness and the recent technique for constructing conserved vectors associated with symmetries of differential equations, we find the conservation law corresponding to the dilation symmetry and show that other symmetries do not provide nontrivial conservation laws. Then we investigate the invariant solutions.

  • 21.
    Bäck, Per
    et al.
    Mälardalen University, SWE.
    Richter, Johan
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    On the hom-associative Weyl algebras2020In: Journal of Pure and Applied Algebra, ISSN 0022-4049, E-ISSN 1873-1376, Vol. 224, no 9, article id 106368Article in journal (Refereed)
    Abstract [en]

    The first (associative) Weyl algebra is formally rigid in the classical sense. In this paper, we show that it can however be formally deformed in a nontrivial way when considered as a so-called hom-associative algebra, and that this deformation preserves properties such as the commuter, while deforming others, such as the center, power associativity, the set of derivations, and some commutation relations. We then show that this deformation induces a formal deformation of the corresponding Lie algebra into what is known as a hom-Lie algebra, when using the commutator as bracket. We also prove that all homomorphisms between any two purely hom-associative Weyl algebras are in fact isomorphisms. In particular, all endomorphisms are automorphisms in this case, hence proving a hom-associative analogue of the Dixmier conjecture to hold true. © 2020 Elsevier B.V.

  • 22.
    Dahl, Mattias
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Javadi, Mohammad Saleh
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Analytical Modeling for a Video-Based Vehicle Speed Measurement Framework2020In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 20, no 1, article id 160Article in journal (Refereed)
    Abstract [en]

     Traffic analyses, particularly speed measurements, are highly valuable in terms of road safety and traffic management. In this paper, an analytical model is presented to measure the speed of a moving vehicle using an off-the-shelf video camera. The method utilizes the temporal sampling rate of the camera and several intrusion lines in order to estimate the probability density function (PDF) of a vehicle’s speed. The proposed model provides not only an accurate estimate of the speed, but also the possibility of being able to study the performance boundaries with respect to the camera framerate as well as the placement and number of intrusion lines in advance. This analytical modelis verified by comparing its PDF outputs with the results obtained via a simulation of the corresponding movements. In addition,as aproof-of-concept, the proposed model is implemented for avideo-based vehicle speed measurement system. The experimental results demonstrate the model’s capability in terms of taking accurate measurements of the speed via a consideration of the temporal sampling rate and lowering the deviation by utilizing more intrusion lines. The analytical model is highly versatile and can be used as the core of various video-based speed measurement systems in transportation and surveillance applications.

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  • 23.
    Dahl, Mattias
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Pettersson, Mats
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Verifiering av mätmetoder, Yttäckande mätningar med SAR2017Report (Other academic)
    Abstract [sv]

    Inom ARENA, den svenska kunskapsplattformen för vägavgifter,har vi tidigare föreslagit satellitbase-rad Syntetisk Apertur Radar (SAR) för att göra effektutvärderingsmätningar av lastbilstrafik över stora områden av Sverige. Denna nya mätmetod är mycket lovande och syftet med detta delprojekt har varit att studera hur ett urval avmätområden kan ske om man avser att genomföra trafikmätningar ur ett effektutvärderingsperspektiv. Som utgångspunkt för rapporten används resultatetfrån de mätningar som inom ramen för ARENA tidigarehar genomförts och avrapporterats, det vill sägaenserie avmätning över södra Sverige där satellitsystemetTerraSAR-X användes för att mäta trafik. Motiveringen till att använda ett satellitsy-stemmed SAR är kostnadseffektivitetenoch förmåganatt mäta trafik på samma sättöver hela Sve-rige och dessutomunder allaåretsdagaroavsett väderlek. Beräkningarna för var man skall eller bör mäta baserar sig på underlag från Nationell vägdata-bas(NVDB) som ärTrafikverketsdatabas över vägnätet i Sverige. Detta underlagi form av trafikflö-denhar i sin tur fått utgöra ett underlag tillhur satellitmätningar kan skei olika landsändar det vill sägaförmågan att observeralastbilstrafiki de aktuella områdena.Avsikten med en mätning av detta slag är att den härledda informationen ska levereras till slutanvän-darevars syfte är att utvärdera effekterna av en Vägslitageskatt. Idenna rapport presenteras kartor ur vilka intressanta områden ur olika aspekter kan väljas ur och inte minst var man i sådant fall skall eller bör mäta.Rapporten avslutas med ett mer teoretiskt resonemang kring hur effektiva skatt-ningar av medeltrafikur ett satellitperspektiv skulle kunna betraktas ochi någon meninghur mät-ningar och den efterföljande statistiska databehandlingendärigenomblir så effektiv som möjligt.

  • 24.
    Dahl, Mattias
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Pettersson, Mats
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Sjögren, Thomas
    Yttäckande mätningar med satellit - Studie avmätmetoder och datafångst2017Report (Other academic)
    Abstract [sv]

    Avståndsbaserade vägavgiftssystem införs successivt i många länder världen över. Effekten av ett systems implementering kan i många delar vara svårt att analysera, inte minst ur ett mer övergri-pande perspektiv. Denna rapport är en studierörande en helt ny typ av satellitbaserad,yttäckande mätteknik som har genomförts inom ARENA, den svenska kunskapsplattformen för brukaravgifter i transportsektorn. Den yttäckande trafikmätningen sker med avancerad radarteknik som blivit tillgänglig under de sen-aste åren och där vi idag befinner oss i ett stort skifte på så sätt att tillgängligheten av data kommer att öka betydande de närmsta åren. Rapporten innehåller resultat från ett fältförsök över södra Sverige där det tyska satellitsystemet TerraSAR-X användes. Syftet är också att få en uppfattning över hur metodiken, som krävs vid en fullskalig satellitmätning, ser ut. Det vill säga hur man skall välja ut mätområdet, beställning av mät-ning över mätområdet, nedladdning av satellitdatauttag samt en verifiering av hur mätningarna på olika sätt kan bidra till före-och efteranalyser vid ett eventuellt införande av ett vägavgiftssystem.Rapporten har ett övergripande mål att knyta an till de inom ARENAidentifierade domäner, faktorer och nyckeltal som i sin tur ansetts vara relevanta för att utvärdera effekterna av ett införande av en vägslitageskatt för tung trafik. Rapportens huvudsakliga fokus är vad som möjligt att mäta från satel-litbaserade system men även i någon mening översiktligt uppskatta förmågan hos andra yttäckande system såsom drönare och flygburna system. Det vill säga vad systemen kan förväntas leverera uti-från en analys kring tillgänglighet, kvalitet, kostnad och användbarhet.

  • 25.
    Danielsson, Max
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Technology and Aesthetics.
    Grahn, Håkan
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Sievert, Thomas
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Rasmusson, Jim
    Sony Mobile Communications AB, SWE.
    Comparing Two Generations of Embedded GPUs Running a Feature Detection AlgorithmManuscript (preprint) (Other academic)
    Abstract [en]

    Graphics processing units (GPUs) in embedded mobile platforms are reaching performance levels where they may be useful for computer vision applications. We compare two generations of embedded GPUs for mobile devices when run- ning a state-of-the-art feature detection algorithm, i.e., Harris- Hessian/FREAK. We compare architectural differences, execu- tion time, temperature, and frequency on Sony Xperia Z3 and Sony Xperia XZ mobile devices. Our results indicate that the performance soon is sufficient for real-time feature detection, the GPUs have no temperature problems, and support for large work-groups is important.

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  • 26. Danielsson, Max
    et al.
    Sievert, Thomas
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Grahn, Håkan
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Rasmusson, Jim
    Sony Mobile Communications AB.
    Feature Detection and Description using a Harris-Hessian/FREAK Combination on an Embedded GPU2016Conference paper (Refereed)
    Abstract [en]

    GPUs in embedded platforms are reaching performance levels comparable to desktop hardware, thus it becomes interesting to apply Computer Vision techniques. We propose, implement, and evaluate a novel feature detector and descriptor combination, i.e., we combine the Harris-Hessian detector with the FREAK binary descriptor. The implementation is done in OpenCL, and we evaluate the execution time and classification performance. We compare our approach with two other methods, FAST/BRISK and ORB. Performance data is presented for the mobile device Xperia Z3 and the desktop Nvidia GTX 660. Our results indicate that the execution times on the Xperia Z3 are insufficient for real-time applications while desktop execution shows future potential. Classification performance of Harris-Hessian/FREAK indicates that the solution is sensitive to rotation, but superior in scale variant images.

  • 27.
    Eriksson, Mattias
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Lennerstad, Håkan
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    A new formula for the statistical weight for a sequence of Rydberg levels in an atom or ion2017In: Journal of Physics: Conference Series / [ed] Majeed T.,Egilmez M.,Alnaser A.S.,Abdel-Naby S.,Hamdan N.,Guessoum N.,Salamin Y.,El-Khatib S.,Sakhi S.,Syed R., Institute of Physics Publishing , 2017, Vol. 869, no 1, article id UNSP 012010Conference paper (Refereed)
    Abstract [en]

    We present a new formula for the total statistical weight of all Rydberg levels Gion (nl, nh ) for which the principal quantum number n is between higher, nh , and a lower, nl , limits. This formula can be used for all atoms in the periodic table and for all corresponding ions.

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  • 28.
    Fabrin, Ana
    et al.
    Universidade Federal de Santa Maria, BRA.
    Molin, Ricardo
    Universidade Federal de Santa Maria, BRA.
    Alves, Dimas Irion
    Universidade Federal do Pampa, BRA.
    Machado, Renato
    Universidade Federal de Santa Maria, BRA.
    Bayer, Fabio
    Universidade Federal de Santa Maria, BRA.
    Pettersson, Mats
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    A CFAR optimization for low frequency UWB SAR change detection algorithms2017In: International Geoscience and Remote Sensing Symposium (IGARSS), Institute of Electrical and Electronics Engineers Inc. , 2017, p. 1071-1074Conference paper (Refereed)
    Abstract [en]

    This paper presents a study on the constant false alarm rate (CFAR) filter design for change detection algorithms (CDA). More specifically, we are interested in CFAR filters used in CDA for low frequency ultra-wideband (UWB) synthetic aperture radar (SAR) systems. The filter design performance was evaluated in terms of false alarm rate (FAR) and probability of detection (PD). For evaluation purposes, we considered a set of SAR images obtained with the CARABAS-II system. The results are compared with the ones presented in [1], where the same CDA was considered, except for the CFAR filter. The results show that relevant FAR performance improvements can be obtained by just modifying the CFAR filter parameters taking into account the image resolution and target characteristics. © 2017 IEEE.

  • 29.
    Fredriksson, Henrik
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Dahl, Mattias
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Holmgren, Johan
    Malmö Högskola, SWE.
    Optimal placement of charging stations for electric vehicles in large-scale transportation networks2019In: Procedia Computer Science / [ed] Shakshuki, E; Yasar, A; Malik, H, Elsevier B.V. , 2019, Vol. 160, p. 77-84Conference paper (Refereed)
    Abstract [en]

    This paper presents a new practical approach to optimally allocate charging stations in large-scale transportation networks for electric vehicles (EVs). The problem is of particular importance to meet the charging demand of the growing fleet of alternative fuel vehicles. Considering the limited driving range of EVs, there is need to supply EV owners with accessible charging stations to reduce their range anxiety. The aim of the Route Node Coverage (RNC) problem, which is considered in the current paper, is to find the minimum number of charging stations, and their locations in order to cover the most probable routes in a transportation network. We propose an iterative approximation technique for RNC, where the associated Integer Problem (IP) is solved by exploiting a probabilistic random walk route selection, and thereby taking advantage of the numerical stability and efficiency of the standard IP software packages. Furthermore, our iterative RNC optimization procedure is both pertinent and straightforward to implement in computer coding and the design technique is therefore highly applicable. The proposed optimization technique is applied on the Sioux-Falls test transportation network, and in a large-scale case study covering the southern part of Sweden, where the focus is on reaching the maximum coverage with a minimum number of charging stations. The results are promising and show that the flexibility, smart route selection, and numerical efficiency of the proposed design technique, can pick out strategic locations for charging stations from thousands of possible locations w ithout numerical difficulties. ©2019 Hie Authors. Published by Elsevier B.V.

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    Optimal placement of Charging Stations for Electric Vehicles inlarge-scale Transportation Networks
  • 30.
    G Palm, Bruna
    et al.
    Universidade Federal de Pernambuco, BRA.
    Alves, Dimas
    Universidade Federal do Pampa, BRA; .
    Pettersson, Mats
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Vu, Viet Thuy
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Machado, Renato
    Aeronautics Institute of Technology (ITA), BRA.
    J Cintra, Renato
    University of Calgary, CAN.
    M Bayer, Fabio
    Universidade Federal de Santa Maria, BRA.
    Dämmert, Patrik B. G.
    Saab Electronic Defence Systems, SWE.
    Hellsten, Hans
    Saab Electronic Defence Systems, SWE.
    Wavelength-Resolution SAR Ground Scene Prediction Based on Image Stack2020In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 20, no 7Article in journal (Refereed)
    Abstract [en]

    This paper presents five different statistical methods for ground scene prediction (GSP) in wavelength-resolution synthetic aperture radar (SAR) images. The GSP image can be used as a reference image in a change detection algorithm yielding a high probability of detection and low false alarm rate. The predictions are based on image stacks, which are composed of images from the same scene acquired at different instants with the same flight geometry. The considered methods for obtaining the ground scene prediction include (i) autoregressive models; (ii) trimmed mean; (iii) median; (iv) intensity mean; and (v) mean. It is expected that the predicted image presents the true ground scene without change and preserves the ground backscattering pattern. The study indicates that the the median method provided the most accurate representation of the true ground. To show the applicability of the GSP, a change detection algorithm was considered using the median ground scene as a reference image. As a result, the median method displayed the probability of detection of 97 % and a false alarm rate of 0 . 11 / km 2 , when considering military vehicles concealed in a forest.

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    Wavelength-Resolution SAR Ground Scene Prediction Based on Image Stack
  • 31. Gazizov, R. K.
    et al.
    Ibragimov, N. H.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Lukashchuk, S. Yu.
    Nonlinear self-adjointness, conservation laws and exact solutions of time-fractional Kompaneets equations2015In: Communications in nonlinear science & numerical simulation, ISSN 1007-5704, E-ISSN 1878-7274, Vol. 23, no 1-3, p. 153-163Article in journal (Refereed)
    Abstract [en]

    Four time-fractional generalizations of the Kompaneets equation are considered. Group analysis is performed for physically relevant approximations. It is shown that all approximations have nontrivial symmetries and conservation laws. The symmetries are used for constructing group invariant solutions, whereas the conservation laws allow to find non-invariant exact solutions. (C) 2014 Elsevier B.V. All rights reserved.

  • 32.
    Gomes, Natanael Rodrigues
    et al.
    Federal University of Santa Maria, BRA.
    Dammert, Patrik
    Saab Surveillance AB, SWE.
    Pettersson, Mats
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Vu, Viet Thuy
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Hellsten, Hans
    Saab Surveillance AB, SWE.
    Comparison of the Rayleigh and K-Distributions for Application in Incoherent Change Detection2019In: IEEE Geoscience and Remote Sensing Letters, ISSN 1545-598X, E-ISSN 1558-0571, Vol. 16, p. 756-760Article in journal (Refereed)
    Abstract [en]

    The aim of this letter is to compare two incoherent change-detection algorithms for target detection in low-frequency ultrawideband (UWB) synthetic aperture radar (SAR) images. The considered UWB SAR operates in the frequency range from 20 to 90 MHz. Both approaches employ a likelihood ratio test according to the Neyman–Pearson criterion. First, the bivariate Rayleigh probability distribution is used to implement the likelihood ratio test function. This distribution is well known and has been used for change-detection algorithms in low-frequency UWB SAR with good results. Aiming to minimize the false alarm rate and taking into consideration that low-frequency UWB SAR images have high resolution compared to the transmitted wavelength, the second approach implements the test by using a bivariate K-distribution. This distribution has scale and shape parameters that can be used to adjust it to the data. No filter is applied to the data set images, and the results show that with a good statistical model, it is not needed to rely on filtering the data to decrease the number of false alarms. Therefore, we can have a better tradeoff between resolution and detection performance.

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  • 33.
    Gradolewski, Dawid
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Maslowski, Dawid
    Intema Sp Zoo, POL.
    Dziak, Damian
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Jachimczyk, Bartosz
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Mundlamuri, Siva Teja
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences. Intema Sp Zoo, Siennicka 25a, POL.
    Prakash, Chandran G.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences. Intema Sp Zoo, Siennicka 25a, POL.
    Kulesza, Wlodek
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    A Distributed Computing Real-Time Safety System of Collaborative Robot2020In: ELEKTRONIKA IR ELEKTROTECHNIKA, ISSN 1392-1215, Vol. 26, no 2, p. 4-14Article in journal (Refereed)
    Abstract [en]

    Robotization has become common in modern factories due to its efficiency and cost-effectiveness. Lots of robots and manipulators share their workspaces with humans what could lead to hazardous situations causing health damage or even death. This article presents a real-time safety system applying the distributed computing paradigm for a collaborative robot. The system consists of detection/sensing modules connected with a server working as decision-making system. Each configurable sensing module pre-processes vision information and then sends to the server the images cropped to new objects extracted from a background. After identifying persons from the images, the decision-making system sends a request to the robot to perform pre-defined action. In the proposed solution, there are indicated three safety zones defined by three different actions on a robot motion. As identification method, state-of-the-art of Machine Learning algorithms, the Histogram of Oriented Gradients (HOG), Viola-Jones, and You Only Look Once (YOLO), have been examined and presented. The industrial environment tests indicated that YOLOv3 algorithm outperformed other solutions in terms of identification capabilities, false positive rate and maximum latency.

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    A Distributed Computing Real-Time Safety System of Collaborative Robot
  • 34. Hellisten, Hans
    et al.
    Machado, Renato
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Pettersson, Mats I.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Vu, Viet Thuy
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Dammert, Patrik
    EXPERIMENTAL RESULTS ON CHANGE DETECTION BASED ON BAYES PROBABILITY THEOREM2015In: 2015 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS), IEEE Communications Society, 2015, p. 318-321Conference paper (Refereed)
    Abstract [en]

    In this paper we propose a new change detection (CD) algorithm based on the Bayes theorem and probability assignments. Differently from any kind of likelihood ratio test (LRT) algorithms, the proposed algorithm does not present target alarms, but the probability of certain image position is a target position. In other words, the proposed method leads to quantitative estimates on the probability of a target at any pixel, whereas LRT algorithms can only be used as a figure of merit for any pixel to contain a target.

  • 35. Hjälmdahl, Magnus
    et al.
    Clemedthson, Per-Olof
    Dahl, Mattias
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Fastén, Gunnar
    Mbiydzenyuy, Gideon
    Pettersson, Mats
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Sundberg, Jonas
    Effektutvärdering av kilometerskatt: Slutrapport. Slutsats och rekommendation2017Report (Other academic)
    Abstract [sv]

    Urinsikten om behovet av brukaravgifter inom transportsektornföddes idén att skapa en arena för den samlade kompetenseni Sverige. Detta blev ARENA-projektet, vars första fas,2006-2008,hade som mål attutveckla ett koncept för ett vägavgiftssystem för lastbilar.Den andra fasen avslutades2011 med syftet att verifiera det utvecklade vägavgiftskonceptet genom praktiska demonstrationer. Projektet lade även grunden för en innovationsmiljö inom ITS, som är knuten till NetPort Science Park och Blekinge Tekniska Högskola.I den tredje fasen breddades anslaget till att stödja utveckl-ingen av samverkan och interoperabilitet mellan olika system för exempelvis trängselskatt, infra-strukturavgifter eller kilometerskatt, såväl i Sverige som internationellt.Från 2015 har ARENA övergått till att vara en långsiktig nationell kunskapsplattform för brukaravgif-ter inom transportsektorn. Inom ARENA drivs olika projekt beroende på de problemställningar som är aktuella i samhället. Ett av dessa handlar om att utveckla metodik för effektutvärdering av kilome-terskatt för tunga fordonDetta projekt har löpt parallellt med Vägslitageskattekommitténarbete och som ARENAsamverkat medoch stöttat.Arbetet inom ARENA fokuserarpå attutreda vilka effekterav en kilometerskatt som är troliga/möj-liga och vilka av dessa som i sin tur är möjliga att observeraoch hur de kan observeras. Detta har gjorts genom bl.a. inventeringar av andra liknande initiativ och hur de har utvärderats, litteraturge-nomgångar och workshops. Rapporter från detta arbete återfinns på projektets hemsida (http://www.arena-ruc.se/). Denna avslutande rapport fokuserar framförallt på övergripande slutsat-ser baserat på arbetet inom ARENA,samt de rekommendationer om datainsamling och utvärdering som projekt-och styrgruppen för ARENA anser är relevanta att nu gå vidare med, baserat på att ett beslut om införande av kilometerskatt inte har tagits och det är oklart huruvida beslut kommer att tas inom de närmaste åren. ARENA anser, med utgångspunkt i ovanstående, att en systematisk föremätning(ex-ante)bör ge-nomföras först när beslut om att införa skatten har tagits och det finns detaljerad information om hur skatten är utformad.ARENA anser dock att kunskapsnivån om godstransporter på väg generellt sett är bristfällig varför det är motiverat att inleda datafångst inom vissa utpekade områden för att stärka kunskapen. Den data som bör samlas in är värdefull också i samband med utvärdering av ef-fekterna av t.ex. förändrade cabotageregler, ändrade gränser för lastbilars mått och vikt, ändrad energi-och koldioxidbeskattning etc.Det pågår idag flera nationella initiativ kring förbättrat kunskapsunderlag om yrkestrafiken och gods-transporter på väg. ARENAs rekommendationer ligger i linje med dessa och arbetet kring att öka kun-skapsnivån bör fortgå.

  • 36.
    Ibragimov, Nail
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Conservation laws and non-invariant solutions of anisotropic wave equations with a source2018In: Nonlinear Analysis, ISSN 1468-1218, Vol. 40, p. 82-94Article in journal (Refereed)
    Abstract [en]

    Linear and nonlinear waves in anisotropic media are used in various fields, e.g. in biomechanics, biomedical acoustics, etc. The present paper is devoted to discussion of nonlinear anisotropic wave equations with a source from point of view of their conservation laws and exact solutions associated with conservation laws. Nonlinearly self-adjoint wave equations with special source terms are singled out. The conservation laws associated with symmetries of the nonlinearly self-adjoint wave equations are computed and used for constructing exact solutions. The obtained solutions are different from group invariants solutions, in particular, from steady state and traveling wave solutions. The paper is designed for the application oriented readers. Its main goal is to introduce readers, interested in solutions of mathematical models having real world applications, to the recent method of conservation laws for constructing exact solutions of partial differential equations using conservation laws. © 2017 Elsevier Ltd

  • 37.
    Ibragimov, Nail
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Integration of dynamical systems admitting nonlinear superposition2016In: JOURNAL OF COUPLED SYSTEMS AND MULTISCALE DYNAMICS, ISSN 2330-152X, Vol. 4, no 2, p. 91-106Article, review/survey (Refereed)
    Abstract [en]

    A method of integration of non-stationary dynamical systems admitting nonlinear superpositions is presented. The method does not require knowledge of symmetries of the differential equations under consideration. The integration procedure is based on classification of Vessiot-Guldberg-Lie algebras associated with nonlinear superpositions. It is shown that the systems associated with one-and two-dimensional Lie algebras can be integrated by quadrature upon introducing Lie's canonical variables. It is not necessary to know symmetries of a system in question in this approach. Two-dimensional non-stationary dynamical systems with three-dimensional Vessiot-Guldberg-Lie algebras are classified into thirteen standard forms. Ten of them are integrable by quadrature. The remaining three standard forms lead to the Riccati equations. Integration of perturbed dynamical systems possessing approximate nonlinear superposition is discussed.

  • 38.
    Ibragimov, Nail
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Selected Works: Volume 52014Book (Refereed)
    Abstract [en]

    Advanced topics to be added to my textbook "A Practical Course in Differential Equations and Mathematical Modelling".

    This volume is dedicated to the memory of my teacher and friend Lev Vasilyevich Ovsyannikov (22.04.1919{23.05.2014).

    Volume V contains preprints written during 2008-2014 as advanced topics to be added to the textbook.  They include, e.g. a discussion of a wide class of linear ordinary differential equations whose integration is reducible to solution of algebraic equations. This class contains the constant coefficient equations and Euler’s equations as particular cases. The recent method of nonlinear self-adjointness for constructing conservations laws associated with symmetries of partial differential equations is also presented in this volume.

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  • 39.
    Ibragimov, Nail
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Gainetdinova, A. A.
    Ufa State Aviat Tech Univ, Rus.
    Three-dimensional dynamical systems admitting nonlinear superposition with three-dimensional Vessiot-Guldberg-Lie algebras2016In: Applied Mathematics Letters, ISSN 0893-9659, E-ISSN 1873-5452, Vol. 52, p. 126-131Article in journal (Refereed)
    Abstract [en]

    The recent method of integration of non-stationary dynamical systems admitting nonlinear superpositions is applied to the three-dimensional dynamical systems associated with three-dimensional Vessiot-Guldberg-Lie algebras L-3. The investigation is based on Bianchi's classification of real three-dimensional Lie algebras and realizations of these algebras in the three-dimensional space. Enumeration of the Vessiot-Guldberg-Lie algebras L-3 allows to classify three-dimensional dynamical systems admitting nonlinear superpositions into thirty one standard types by introducing canonical variables. Twenty four of them are associated with solvable Vessiot-Guldberg-Lie algebras and can be reduced to systems of first-order linear equations. The remaining seven standard types are nonlinear. Integration of the latter types is an open problem. (C) 2015 Elsevier Ltd. All rights reserved.

  • 40.
    Ibragimov, Nail
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Gainetdinova, Aliya
    Ufimskij Gosudarstvennyj Aviacionnyj Tehniceskij Universitet, RUS.
    Three-dimensional dynamical systems with four-dimensional vessiot-guldberg-lie algebras2017In: The Journal of Applied Analysis and Computation, ISSN 2156-907X, E-ISSN 2158-5644, Vol. 7, no 3, p. 872-883Article in journal (Refereed)
    Abstract [en]

    - Dynamical systems attract much attention due to their wide applications. Many significant results have been obtained in this field from various points of view. The present paper is devoted to an algebraic method of integration of three-dimensional nonlinear time dependent dynamical systems admitting nonlinear superposition with four-dimensional Vessiot-Guldberg-Lie algebras L4. The invariance of the relation between a dynamical system admitting nonlinear superposition and its Vessiot-Guldberg-Lie algebra is the core of the integration method. It allows to simplify the dynamical systems in question by reducing them to standard forms. We reduce the three-dimensional dynamical systems with four-dimensional Vessiot-Guldberg-Lie algebras to 98 standard types and show that 86 of them are integrable by quadratures.

  • 41.
    Ibragimov, Nail
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Gainetdinova, Aliya. A.
    Ufa State Aviation Technical University, RUS.
    Classification and integration of four-dimensional dynamical systems admitting non-linear superposition2017In: International Journal of Non-Linear Mechanics, ISSN 0020-7462, Vol. 90, p. 50-71Article in journal (Refereed)
    Abstract [en]

    The method of integration of dynamical systems admitting non-linear superpositions is applied to four-dimensional non-linear dynamical systems. All four-dimensional dynamical systems admitting non-linear superpositions with four-dimensional Vessiot-Guldberg-Lie algebras are classified into 160 standard forms. The integration method is described and illustrated.

  • 42.
    Ibragimov, Nail
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Gandarias, M.L.
    Galiakberova, L.R.
    Bruzon, M.S.
    Avdonina, E.D.
    Group classification and conservation laws of anisotropic wave equations with a source2016In: Journal of Mathematical Physics, ISSN 0022-2488, E-ISSN 1089-7658, Vol. 57, no 8, article id 083504Article in journal (Refereed)
    Abstract [en]

    Linear and nonlinear waves in anisotropic media are useful in investigating complex materials in physics, biomechanics, biomedical acoustics, etc. The present paper is devoted to investigation of symmetries and conservation laws for nonlinear anisotropic wave equations with specific external sources when the equations in question are nonlinearly self-adjoint. These equations involve two arbitrary functions. Construction of conservation laws associated with symmetries is based on the generalized conservation theorem for nonlinearly self-adjoint partial differential equations. First we calculate the conservation laws for the basic equation without any restrictions on the arbitrary functions. Then we make the group classification of the basic equation in order to specify all possible values of the arbitrary functions when the equation has additional symmetries and construct the additional conservation laws.

  • 43.
    Ibragimov, Nail H.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Comments on the paper "Conservation laws of the (2+1)-dimensional KP equation and Burgers equation with variable coefficients and cross terms" by Li-Hua Zhang2014In: Applied Mathematics and Computation, ISSN 0096-3003, E-ISSN 1873-5649, Vol. 226, p. 1-2Article in journal (Refereed)
    Abstract [en]

    The recent paper mentioned in the title contains a confusing statement on computing conservation laws corresponding to symmetries of nonlinearly self-adjoint differential equations. The present brief article contains clarifying comments.

  • 44.
    Ibragimov, Nail H.
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Gazizov, Rafail H.
    Approximate symmetries and solutions of the Kompaneets equation2014In: Communications in nonlinear science & numerical simulation, ISSN 1007-5704, E-ISSN 1878-7274, Vol. 55, no 2, p. 220-224Article in journal (Refereed)
    Abstract [en]

    Different approximations of the Kompaneets equation are studied using approximate symmetries, which allows consideration of the contributions of all terms of this equation previously neglected in the analysis of the limiting cases.

  • 45.
    Ibragimov, Nail H.
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Ibragimov, Ranis N.
    Galiakberova, L. R.
    Symmetries and Conservation Laws of a Spectral Nonlinear Model for Atmospheric Baroclinic Jets2014In: Mathematical Modelling of Natural Phenomena, ISSN 0973-5348, E-ISSN 1760-6101, Vol. 9, no 5, p. 111-118Article in journal (Refereed)
    Abstract [en]

    In this paper, we shall obtain the symmetries of the mathematical model describing spontaneous relaxation of eastward jets into a meandering state and use these symmetries for constructing the conservation laws. The basic eastward jet is a spectral parameter of the model, which is in geostrophic equilibrium with the basic density structure and which guarantees the existence of nontrivial conservation laws.

  • 46.
    Ibragimov, Nail H.
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Kovalev, V. F.
    Meleshko, S. V.
    Bychenkov, V. Yu.
    Group analysis of kinetic equations in a non-linear thermal transport problem2015In: International Journal of Non-Linear Mechanics, ISSN 0020-7462, E-ISSN 1878-5638, Vol. 71, p. 1-7Article in journal (Refereed)
    Abstract [en]

    An application of modern group analysis to electron kinetic equations in non-linear thermal transport problem is discussed. The admitted symmetry group is calculated, and the optimal system of one and two-dimensional subalgebras is constructed. Representations of invariant solutions are presented.

  • 47.
    Ibragimov, Nail
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Ibragimov, Ranis N.
    Univ Wisconsin Parkside, USA.
    Kovalev, Vladimir F.
    Russian Acad Sci, RUS.
    INVARIANT SOLUTIONS AND SHOCK ATMOSPHERIC WAVES IN A THIN CIRCULAR LAYER2018In: Mathematical Modelling of Natural Phenomena, ISSN 0973-5348, E-ISSN 1760-6101, Vol. 13, no 2, article id UNSP 19Article in journal (Refereed)
    Abstract [en]

    The objective of this paper is to investigate the nonlinear mathematical model describing equatorial waves from Lie group analysis point of view in order to understand the nature of shallow water model theory, which is associated to planetary equatorial waves. Such waves correspond to the Cauchy-Poisson free boundary problem on the nonstationary motion of a perfect incompressible fluid circulating around a solid circle of a large radius.

  • 48.
    Ibragimov, Nail
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Karimova, E. N.
    Ufa State Aviat Tech Univ, Lab Grp Anal Math Models Nat & Engn Sci, Ufa 450000, Russia..
    Galiakberova, L. R.
    Ufa State Aviat Tech Univ, Lab Grp Anal Math Models Nat & Engn Sci, Ufa 450000, Russia..
    Chaplygin gas motions associated with nonlocal conservation laws2017In: JOURNAL OF COUPLED SYSTEMS AND MULTISCALE DYNAMICS, ISSN 2330-152X, Vol. 5, no 2-4, p. 63-68Article in journal (Refereed)
    Abstract [en]

    The recent method of conservation laws for constructing exact solutions of partial differential equations is applied to the nonlocal conservation laws of the Chaplygin gas. The nonlocal conservation laws provide twenty different types of exact solutions. They are listed in three tables. Seven types of these solutions describe isentropic flows satisfying Chaplygin's relation between the pressure and density. All solutions are written in the explicit form and contain either arbitrary functions or arbitrary constants.

  • 49.
    Ibragimov, Nail
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Khamitova, Raisa
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Avdonina, E. D.
    Galiakberova, L. R.
    Conservation laws and solutions of a quantum drift-diffusion model for semiconductors2015In: International Journal of Non-Linear Mechanics, ISSN 0020-7462, E-ISSN 1878-5638, Vol. 77, p. 69-73Article in journal (Refereed)
    Abstract [en]

    A non-linear system of partial differential equations describing a quantum drift-diffusion model for semiconductor devices is investigated by methods of group analysis. An infinite number of conservation laws associated with symmetries of the model are found. These conservation laws are used for representing the system of equations under consideration in the conservation form. Exact solutions provided by the method of conservation laws are discussed. These solutions are different from invariant solutions. (C) 2015 Published by Elsevier Ltd.

  • 50.
    Ibragimov, Nail
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Khamitova, Raisa
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Avdonina, E. D.
    Galiakberova, L.R.
    Group analysis of the drift–diffusion model for quantum semiconductors2015In: Communications in nonlinear science & numerical simulation, ISSN 1007-5704, E-ISSN 1878-7274, Vol. 20, no 1, p. 74-78Article in journal (Refereed)
    Abstract [en]

    In the present paper a quantum drift–diffusion model describing semi-conductor devices is considered. New conservation laws for the model are computed and used to construct exact solutions.

1234 1 - 50 of 170
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