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  • 1.
    Abbaspour, Saadeh
    et al.
    Mälardalen University, Sweden; University of Qom, Iran.
    Fotouhi, Faranak
    University of Qom, Iran.
    Sedaghatbaf, Ali
    RISE Research Institutes of Sweden.
    Fotouhi, Hossein
    Mälardalen University, Sweden.
    Vahabi, Maryam
    Mälardalen University, Sweden; ABB Corporate Research, Sweden.
    Linden, Maria
    Mälardalen University, Sweden.
    A comparative analysis of hybrid deep learning models for human activity recognition2020In: Sensors, E-ISSN 1424-8220, Vol. 20, no 19, article id 5707Article in journal (Refereed)
    Abstract [en]

    Recent advances in artificial intelligence and machine learning (ML) led to effective methods and tools for analyzing the human behavior. Human Activity Recognition (HAR) is one of the fields that has seen an explosive research interest among the ML community due to its wide range of applications. HAR is one of the most helpful technology tools to support the elderly’s daily life and to help people suffering from cognitive disorders, Parkinson’s disease, dementia, etc. It is also very useful in areas such as transportation, robotics and sports. Deep learning (DL) is a branch of ML based on complex Artificial Neural Networks (ANNs) that has demonstrated a high level of accuracy and performance in HAR. Convolutional Neural Networks (CNNs) and Recurrent Neural Networks (RNNs) are two types of DL models widely used in the recent years to address the HAR problem. The purpose of this paper is to investigate the effectiveness of their integration in recognizing daily activities, e.g., walking. We analyze four hybrid models that integrate CNNs with four powerful RNNs, i.e., LSTMs, BiLSTMs, GRUs and BiGRUs. The outcomes of our experiments on the PAMAP2 dataset indicate that our proposed hybrid models achieve an outstanding level of performance with respect to several indicative measures, e.g., F-score, accuracy, sensitivity, and specificity. © 2020 by the authors.

  • 2.
    Aghaeinezhadfirouzja, Saeid
    et al.
    Shanghai Jiao Tong University, China.
    Liu, Hui
    Shanghai Jiao Tong University, China.
    Balador, Ali
    RISE - Research Institutes of Sweden, ICT, SICS. Mälardalen University, Sweden.
    Practical 3-D beam pattern based channel modeling for multi-polarized massive MIMO systems2018In: Sensors, E-ISSN 1424-8220, Vol. 18, no 4, article id 1186Article in journal (Refereed)
    Abstract [en]

    In this paper, a practical non-stationary three-dimensional (3-D) channel models for massive multiple-input multiple-output (MIMO) systems, considering beam patterns for different antenna elements, is proposed. The beam patterns using dipole antenna elements with different phase excitation toward the different direction of travels (DoTs) contributes various correlation weights for rays related towards/from the cluster, thus providing different elevation angle of arrivals (EAoAs) and elevation angle of departures (EAoDs) for each antenna element. These include the movements of the user that makes our channel to be a non-stationary model of clusters at the receiver (RX) on both the time and array axes. In addition, their impacts on 3-D massive MIMO channels are investigated via statistical properties including received spatial correlation. Additionally, the impact of elevation/azimuth angles of arrival on received spatial correlation is discussed. Furthermore, experimental validation of the proposed 3-D channel models on azimuth and elevation angles of the polarized antenna are specifically evaluated and compared through simulations. The proposed 3-D generic models are verified using relevant measurement data.

  • 3.
    Alirezaie, Marjan
    et al.
    Örebro University, Sweden.
    Renoux, Jennifer
    Örebro University, Sweden.
    Köckemann, Uwe
    Örebro University, Sweden.
    Kristoffersson, Annica
    Örebro University, Sweden.
    Karlsson, Lars
    Örebro University, Sweden.
    Blomqvist, Eva
    RISE - Research Institutes of Sweden, ICT, SICS.
    Tsiftes, Nicolas
    RISE - Research Institutes of Sweden, ICT, SICS.
    Voigt, Thiemo
    RISE - Research Institutes of Sweden, ICT, SICS.
    Loutfi, A
    Örebro University, Sweden.
    An ontology-based context-aware system for smart homes: E-care@home2017In: Sensors, E-ISSN 1424-8220, Vol. 17, no 7, article id 1586Article in journal (Refereed)
    Abstract [en]

    Smart home environments have a significant potential to provide for long-term monitoring of users with special needs in order to promote the possibility to age at home. Such environments are typically equipped with a number of heterogeneous sensors that monitor both health and environmental parameters. This paper presents a framework called E-care@home, consisting of an IoT infrastructure, which provides information with an unambiguous, shared meaning across IoT devices, end-users, relatives, health and care professionals and organizations. We focus on integrating measurements gathered from heterogeneous sources by using ontologies in order to enable semantic interpretation of events and context awareness. Activities are deduced using an incremental answer set solver for stream reasoning. The paper demonstrates the proposed framework using an instantiation of a smart environment that is able to perform context recognition based on the activities and the events occurring in the home.

  • 4.
    Amer, Eynas
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Wozniak, Mikolaj
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Jönsson, Gustav
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Arrhén, Fredrik
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Evaluation of Shock Tube Retrofitted with Fast-Opening Valve for Dynamic Pressure Calibration2021In: Sensors, E-ISSN 1424-8220, Vol. 21, no 13, article id 4470Article in journal (Refereed)
    Abstract [en]

    Accurate dynamic pressure measurements are increasingly important. While traceability is lacking, several National Metrology Institutes (NMIs) and calibration laboratories are currently establishing calibration capacities. Shock tubes generating pressure steps with rise times below 1 µs are highly suitable as standards for dynamic pressures in gas. In this work, we present the results from applying a fast-opening valve (FOV) to a shock tube designed for dynamic pressure measurements. We compare the performance of the shock tube when operated with conventional single and double diaphragms and when operated using an FOV. Different aspects are addressed: shock-wave formation, repeatability in amplitude of the realized pressure steps, the assessment of the required driver pressure for realizing nominal pressure steps, and economy. The results show that using the FOV has many advantages compared to the diaphragm: better repeatability, eight times faster to operate, and enables automation of the test sequences.

  • 5.
    Araujo, Jefferson
    et al.
    Pontifical Catholic University of Rio de Janeiro, Brazil.
    Reis, Andre
    Observatório Nacional, Brazil.
    Oliveira, Vanderlei
    Observatório Nacional, Brazil.
    Santos, Amanda
    University of California, US.
    Luz-Lima, Cleaneo
    Universidade Federal do Piauí, Brazil.
    Yokoyama, Elder
    University of Brasília, Brazil.
    Mendoza, Leonardo
    Universidade Estadual do Rio de Janeiro, Brazil.
    Pereira, Joao
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Bruno, Antonio
    Pontifical Catholic University of Rio de Janeiro, Brazil.
    Characterizing complex mineral structures in thin sections of geological samples with a scanning hall effect microscope2019In: Sensors, E-ISSN 1424-8220, Vol. 19, no 7, article id 1636Article in journal (Refereed)
    Abstract [en]

    We improved a magnetic scanning microscope for measuring the magnetic properties of minerals in thin sections of geological samples at submillimeter scales. The microscope is comprised of a 200 µm diameter Hall sensor that is located at a distance of 142 µm from the sample; an electromagnet capable of applying up to 500 mT DC magnetic fields to the sample over a 40 mm diameter region; a second Hall sensor arranged in a gradiometric configuration to cancel the background signal applied by the electromagnet and reduce the overall noise in the system; a custom-designed electronics system to bias the sensors and allow adjustments to the background signal cancelation; and a scanning XY stage with micrometer resolution. Our system achieves a spatial resolution of 200 µm with a noise at 6.0 Hz of 300 nT rms /(Hz) 1/2 in an unshielded environment. The magnetic moment sensitivity is 1.3 × 10 −11 Am 2 . We successfully measured the representative magnetization of a geological sample using an alternative model that takes the sample geometry into account and identified different micrometric characteristics in the sample slice.

  • 6.
    Balador, Ali
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS. Mälardalen University, Sweden.
    Kouba, Anis
    Polytechnic Institute of Porto, Portugal.
    Cassioli, Dajana
    University of L’Aquila, Italy.
    Foukalas, Fotis T.
    DTU Technical University of Denmark, Denmark.
    Severino, Ricardo
    Polytechnic Institute of Porto, Portugal.
    Stepanova, Daria
    Finnish Meteorological Institute, Finland.
    Agosta, Giovanni
    Politecnico di Milano, Italy.
    Xie, Jing
    DNV GL, Norway.
    Pomante, Luigi
    DTU Technical University of Denmark, Denmark.
    Mongelli, Maurizio
    CNR-IEIIT, Italy.
    Pierini, Pierluigi
    Intecs S.p.A, Italy.
    Petersen, Stig
    SINTEF, Norway.
    Sukuvaara, Timo
    Finnish Meteorological Institute, Finland.
    Wireless communication technologies for safe cooperative cyber physical systems2018In: Sensors, E-ISSN 1424-8220, Vol. 18, no 11, article id 4075Article in journal (Refereed)
    Abstract [en]

    Cooperative Cyber-Physical Systems (Co-CPSs) can be enabled using wireless communication technologies, which in principle should address reliability and safety challenges. Safety for Co-CPS enabled by wireless communication technologies is a crucial aspect and requires new dedicated design approaches. In this paper, we provide an overview of five Co-CPS use cases, as introduced in our SafeCOP EU project, and analyze their safety design requirements. Next, we provide a comprehensive analysis of the main existing wireless communication technologies giving details about the protocols developed within particular standardization bodies. We also investigate to what extent they address the non-functional requirements in terms of safety, security and real time, in the different application domains of each use case. Finally, we discuss general recommendations about the use of different wireless communication technologies showing their potentials in the selected real-world use cases. The discussion is provided under consideration in the 5G standardization process within 3GPP, whose current efforts are inline to current gaps in wireless communications protocols for Co-CPSs including many future use cases.

  • 7.
    Balador, Ali
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS. Mälardalen University, Sweden.
    Uhlemann, Elisabeth
    Mälardalen University, Sweden.
    Calafate, Carlos T
    Universitat Politècnica de València, Spain.
    Cano, Juan-Carlos
    Universitat Politècnica de València, Spain.
    Supporting Beacon and Event-Driven Messages in Vehicular Platoons through Token-Based Strategies2018In: Sensors, E-ISSN 1424-8220, Vol. 18, no 4, article id E955Article in journal (Refereed)
    Abstract [en]

    Timely and reliable inter-vehicle communications is a critical requirement to support traffic safety applications, such as vehicle platooning. Furthermore, low-delay communications allow the platoon to react quickly to unexpected events. In this scope, having a predictable and highly effective medium access control (MAC) method is of utmost importance. However, the currently available IEEE 802.11p technology is unable to adequately address these challenges. In this paper, we propose a MAC method especially adapted to platoons, able to transmit beacons within the required time constraints, but with a higher reliability level than IEEE 802.11p, while concurrently enabling efficient dissemination of event-driven messages. The protocol circulates the token within the platoon not in a round-robin fashion, but based on beacon data age, i.e., the time that has passed since the previous collection of status information, thereby automatically offering repeated beacon transmission opportunities for increased reliability. In addition, we propose three different methods for supporting event-driven messages co-existing with beacons. Analysis and simulation results in single and multi-hop scenarios showed that, by providing non-competitive channel access and frequent retransmission opportunities, our protocol can offer beacon delivery within one beacon generation interval while fulfilling the requirements on low-delay dissemination of event-driven messages for traffic safety applications.

  • 8.
    Dejke, Valter
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Chemistry, Biomaterials and Textiles.
    Eng, Matthias
    RISE Research Institutes of Sweden.
    Brinkfeldt, Klas
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Charnley, Josephine
    Lusstech, UK.
    Lussey, David
    Lusstech, UK.
    Lussey, Chris
    Lusstech, UK.
    Development of prototype low-cost qtss™ wearable flexible more enviro-friendly pressure, shear, and friction sensors for dynamic prosthetic fit monitoring2021In: Sensors, E-ISSN 1424-8220, Vol. 21, no 11, article id 3764Article in journal (Refereed)
    Abstract [en]

    There is a current healthcare need for improved prosthetic socket fit provision for the masses using low-cost and simple to manufacture sensors that can measure pressure, shear, and friction. There is also a need to address society’s increasing concerns regarding the environmental impact of electronics and IoT devices. Prototype thin, low-cost, and low-weight pressure, shear, and loss of friction sensors have been developed and assembled for trans-femoral amputees. These flexible and conformable sensors are simple to manufacture and utilize more enviro-friendly novel magnetite-based QTSS™ (Quantum Technology Supersensor™) quantum materials. They have undergone some initial tests on flat and curved surfaces in a pilot amputee trial, which are presented in this paper. These initial findings indicate that the prototype pressure sensor strip is capable of measuring pressure both on flat and curved socket surfaces in a pilot amputee trial. They have also demonstrated that the prototype shear sensor can indicate increasing shear forces, the resultant direction of the shear forces, and loss of friction/slippage events. Further testing, amputee trials, and ongoing optimization is continuing as part of the SocketSense project to assist prosthetic comfort and fit. © 2021 by the authors

  • 9.
    Forssén, Clayton
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology. Umeå University, Sweden.
    Silander, Isak
    Umeå University, Sweden.
    Zakrisson, Johan
    Umeå University, Sweden.
    Amer, Eynas
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Szabo, David
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Bock, Thomas
    PTB Physikalisch-Technische Bundesanstalt, Germany.
    Kussike, Andre
    PTB Physikalisch-Technische Bundesanstalt, Germany.
    Rubin, Tom
    PTB Physikalisch-Technische Bundesanstalt, Germany.
    Mari, Domenico
    INRiM Istituto Nazionale di Ricerca Metrologica, Italy.
    Pasqualin, Stefano
    INRiM Istituto Nazionale di Ricerca Metrologica, Italy.
    Silvestri, Zaccaria
    Conservatoire National des Arts et Métiers Laboratoire Commun de Métrologie, France.
    Bentouati, Djilali
    LNE Laboratoire National de Métrologie et d’Essais, France.
    Axner, Ove
    Umeå University, Sweden.
    Zelan, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Demonstration of a Transportable Fabry–Pérot Refractometer by a Ring-Type Comparison of Dead-Weight Pressure Balances at Four European National Metrology Institutes2023In: Sensors, E-ISSN 1424-8220, Vol. 24, no 1, article id 7Article in journal (Refereed)
    Abstract [en]

    Fabry–Pérot-based refractometry has demonstrated the ability to assess gas pressure with high accuracy and has been prophesized to be able to realize the SI unit for pressure, the pascal, based on quantum calculations of the molar polarizabilities of gases. So far, the technology has mostly been limited to well-controlled laboratories. However, recently, an easy-to-use transportable refractometer has been constructed. Although its performance has previously been assessed under well-controlled laboratory conditions, to assess its ability to serve as an actually transportable system, a ring-type comparison addressing various well-characterized pressure balances in the 10–90 kPa range at several European national metrology institutes is presented in this work. It was found that the transportable refractometer is capable of being transported and swiftly set up to be operational with retained performance in a variety of environments. The system could also verify that the pressure balances used within the ring-type comparison agree with each other. These results constitute an important step toward broadening the application areas of FP-based refractometry technology and bringing it within reach of various types of stakeholders, not least within industry.

  • 10.
    Forssén, Clayton
    et al.
    RISE Research Institutes of Sweden. Umeå University, Sweden.
    Silander, Isak
    Umeå University, Sweden.
    Zakrisson, Johan
    Umeå University, Sweden.
    Axner, Ove
    Umeå University, Sweden.
    Zelan, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    The short-term performances of two independent gas modulated refractometers for pressure assessments2021In: Sensors, E-ISSN 1424-8220, Vol. 21, no 18, article id 6272Article in journal (Refereed)
    Abstract [en]

    Refractometry is a powerful technique for pressure assessments that, due to the recent redefinition of the SI system, also offers a new route to realizing the SI unit of pressure, the Pascal. Gas modulation refractometry (GAMOR) is a methodology that has demonstrated an outstanding ability to mitigate the influences of drifts and fluctuations, leading to long-term precision in the 10−7 region. However, its short-term performance, which is of importance for a variety of applications, has not yet been scrutinized. To assess this, we investigated the short-term performance (in terms of precision) of two similar, but independent, dual Fabry–Perot cavity refractometers utilizing the GAMOR methodology. Both systems assessed the same pressure produced by a dead weight piston gauge. That way, their short-term responses were assessed without being compromised by any pressure fluctuations produced by the piston gauge or the gas delivery system. We found that the two refractometer systems have a significantly higher degree of concordance (in the 10−8 range at 1 s) than what either of them has with the piston gauge. This shows that the refractometry systems under scrutiny are capable of assessing rapidly varying pressures (with bandwidths up to 2 Hz) with precision in the 10−8 range. © 2021 by the authors.

  • 11.
    Fu, Ying
    et al.
    Halmstad University, Sweden.
    Yager, Tom
    University of Latvia, Latvia.
    Chikvaidze, George
    University of Latvia, Latvia.
    Iyer, Srinivasan
    Senseair AB, Sweden.
    Wang, Qin
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Time-Resolved FDTD and Experimental FTIR Study of Gold Micropatch Arrays for Wavelength-Selective Mid-Infrared Optical Coupling2021In: Sensors, E-ISSN 1424-8220, Vol. 21, no 15, article id 5203Article in journal (Refereed)
    Abstract [en]

    Infrared radiation reflection and transmission of a single layer of gold micropatch two-dimensional arrays, of patch length ∼1.0μm and width ∼0.2μm, have been carefully studied by a finite-difference time-domain (FDTD) method, and Fourier-transform infrared spectroscopy (FTIR). Through precision design of the micropatch array structure geometry, we achieve a significantly enhanced reflectance (85%), a substantial diffraction (10%), and a much reduced transmittance (5%) for an array of only 15% surface metal coverage. This results in an efficient far-field optical coupling with promising practical implications for efficient mid-infrared photodetectors. Most importantly we find that the propagating electromagnetic fields are transiently concentrated around the gold micropatch array in a time duration of tens of ns, providing us with a novel efficient near-field optical coupling.

  • 12.
    Garnacho, F.
    et al.
    FFII-LCOE Fundación para el Fomento de la Innovación Industrial, Spain; Universidad Politécnica de Madrid, Spain.
    Álvarez, F.
    Universidad Politécnica de Madrid, Spain.
    Elg, Alf Peter
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Mier, C.
    Delft University of Technology, Netherlands.
    Lahti, K.
    Tampere University, Finland.
    Khamlichi, A.
    FFII-LCOE Fundación para el Fomento de la Innovación Industrial, Spain; Universidad Politécnica de Madrid, Spain.
    Arcones, E.
    Universidad Politécnica de Madrid, Spain.
    Klüss, Joni
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Rodrigo Mor, A.
    Universitat Politècnica de València, Spain.
    Pakonen, P.
    Tampere University, Finland.
    Vidal, J. R.
    FFII-LCOE Fundación para el Fomento de la Innovación Industrial, Spain.
    Camuñas, Á.
    Universidad Politécnica de Madrid, Spain.
    Rovira, J.
    FFII-LCOE Fundación para el Fomento de la Innovación Industrial, Spain.
    Vera, C.
    Universidad Politécnica de Madrid, Spain.
    Haider, Miran
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Metrological Qualification of PD Analysers for Insulation Diagnosis of HVDC and HVAC Grids2023In: Sensors, E-ISSN 1424-8220, Vol. 23, no 14, article id 6317Article in journal (Refereed)
    Abstract [en]

    On-site partial discharge (PD) measurements have turned out to be a very efficient technique for determining the insulation condition in high-voltage electrical grids (AIS, cable systems, GIS, HVDC converters, etc.); however, there is not any standardised procedure for determining the performances of PD measuring systems. In on-line and on-site PD measurements, high-frequency current transformers (HFCTs) are commonly used as sensors as they allow for monitoring over long distances in high-voltage installations. To ensure the required performances, a metrological qualification of the PD analysers by applying an evaluation procedure is necessary. A novel evaluation procedure was established to specify the quantities to be measured (electrical charge and PD repetition rate) and to describe the evaluation tests considering the measured influence parameters: noise, charge amplitude, pulse width and time interval between consecutive pulses. This procedure was applied to different types of PD analysers used for off-line measurements, sporadic on-line measurements and continuous PD monitoring. The procedure was validated in a round-robin test involving two metrological institutes (RISE from Sweden and FFII from Spain) and three universities (TUDelft from the Netherlands, TAU from Finland and UPM from Spain). With this round-robin test, the effectiveness of the proposed qualification procedure for discriminating between efficient and inappropriate PD analysers was demonstrated. Furthermore, it was shown that the PD charge quantity can be properly determined for on-line measurements and continuous monitoring by integrating the pulse signals acquired with HFCT sensors. In this case, these sensors must have a flat frequency spectrum in the range between several tens of kHz and at least two tens of MHz, where the frequency pulse content is more significant. The proposed qualification procedure can be useful for improving the future versions of the technical specification TS IEC 62478 and the standard IEC 60270. © 2023 by the authors.

  • 13.
    Gebremichael, Teklay
    et al.
    Mid Sweden University, Sweden.
    Gidlund, Mikael
    Mid Sweden University, Sweden.
    Hancke, Gerhard
    City University of Hong Kong,.
    Jennehag, Ulf
    RISE Research Institutes of Sweden, Digital Systems, Industrial Systems.
    Quantum-Safe Group Key Establishment Protocol from Lattice Trapdoors2022In: Sensors, E-ISSN 1424-8220, Vol. 22, no 11, article id 4148Article in journal (Refereed)
    Abstract [en]

    Group communication enables Internet of Things (IoT) devices to communicate in an efficient and fast manner. In most instances, a group message needs to be encrypted using a cryptographic key that only devices in the group know. In this paper, we address the problem of establishing such a key using a lattice-based one-way function, which can easily be inverted using a suitably designed lattice trapdoor. Using the notion of a bad/good basis, we present a new method of coupling multiple private keys into a single public key, which is then used for encrypting a group message. The protocol has the apparent advantage of having a conjectured resistance against poten-tial quantum-computer-based attacks. All functions—key establishment, session key update, node addition, encryption, and decryption—are effected in constant time, using simple linear-algebra operations, making the protocol suitable for resource-constrained IoT networks. We show how a cryptographic session group key can be constructed on the fly by a user with legitimate credentials, making node-capture-type attacks impractical. The protocol also incorporates a mechanism for node addition and session-key generation in a forward-and backward-secrecy-preserving manner. © 2022 by the authors. 

  • 14.
    Karlsson, Mikael
    et al.
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo. Pamitus AB, Sweden.
    Strandqvist, Carl
    Swedish National Forensic Centre, Sweden.
    Jussi, Johnny
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Öberg, Olof
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Petermann, Ingemar
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Elmlund, Louise
    Swedish National Forensic Centre, Sweden.
    Dunne, Simon
    Swedish National Forensic Centre, Sweden.
    Fu, Ying
    KTH Royal Institute of Technology, Sweden.
    Wang, Qin
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Chemical Sensors Generated on Wafer-Scale Epitaxial Graphene for Application to Front-Line Drug Detection2019In: Sensors, E-ISSN 1424-8220, Vol. 19, no 10, article id 2214Article in journal (Refereed)
    Abstract [en]

    Generation of large areas of graphene possessing high quality and uniformity will be a critical factor if graphene-based devices/sensors are to be commercialized. In this work, epitaxial graphene on a 2" SiC wafer was used to fabricate sensors for the detection of illicit drugs (amphetamine or cocaine). The main target application is on-site forensic detection where there is a high demand for reliable and cost-efficient tools. The sensors were designed and processed with specially configured metal electrodes on the graphene surface by utilizing a series of anchors where the metal contacts are directly connected on the SiC substrate. This has been shown to improve adhesion of the electrodes and decrease the contact resistance. A microfluidic system was constructed to pump solutions over the defined graphene surface that could then act as a sensor area and react with the target drugs. Several prototypic systems were tested where non-covalent interactions were used to localize the sensing components (antibodies) within the measurement cell. The serendipitous discovery of a wavelength-dependent photoactivity for amphetamine and a range of its chemical analogs, however, limited the general application of these prototypic systems. The experimental results reveal that the drug molecules interact with the graphene in a molecule dependent manner based upon a balance of π -stacking interaction of the phenyl ring with graphene (p-doping) and the donation of the amine nitrogens lone pair electrons into the π - π *-system of graphene (n-doping).

  • 15.
    Köckemann, Uwe
    et al.
    Örebro University, Sweden.
    Alirezaie, Marjan
    Örebro University, Sweden.
    Renoux, Jennifer
    Örebro University, Sweden.
    Tsiftes, Nicolas
    RISE Research Institutes of Sweden, Digital Systems, Data Science.
    Uddin Ahmed, Mobyen
    Mälardalen University, Sweden.
    Morberg, Daniel
    Mälardalen University, Sweden.
    Lindén, Maria
    Mälardalen University, Sweden.
    Loutfi, Amy
    Örebro University, Sweden.
    Open-Source Data Collection and Data Sets for Activity Recognition in Smart Homes2020In: Sensors, E-ISSN 1424-8220, Vol. 20, no 3, article id 879Article in journal (Refereed)
    Abstract [en]

    As research in smart homes and activity recognition is increasing, it is of ever increasing importance to have benchmarks systems and data upon which researchers can compare methods.While synthetic data can be useful for certain method developments, real data sets that are open and shared are equally as important. This paper presents the E-care@home system, its installation in a real home setting, and a series of data sets that were collected using the E-care@home system. Our first contribution, the E-care@home system, is a collection of software modules for data collection, labeling, and various reasoning tasks such as activity recognition, person counting, and configuration planning.It supports a heterogeneous set of sensors that can be extended easily and connects collected sensor data to higher-level Artificial Intelligence (AI) reasoning modules. Our second contribution is a series of open data sets which can be used to recognize activities of daily living. In addition to these data sets, we describe the technical infrastructure that we have developed to collect the data and the physical environment. Each data set is annotated with ground-truth information, making it relevant for researchers interested in benchmarking different algorithms for activity recognition.

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  • 16.
    Li, Yuhong
    et al.
    Beijing University of Posts and Telecommunications, China; Stockholm University, Sweden.
    Su, Xiang
    University of Helsinki, Finland; University of Oulu, Finland.
    Ding, Aaron Yi
    Delft University of Technology, The Netherlands.
    Lindgren, Anders
    RISE Research Institutes of Sweden, Digital Systems, Industrial Systems. Luleå University of Technology, Sweden.
    Liu, Xiaoli
    University of Helsinki, Finland.
    Prehofer, Christian
    DENSO Automotive Germany, Germany.
    Riekki, Jukka P.
    University of Oulu, Finland.
    Rahmani, Rahim
    Stockholm University, Sweden.
    Tarkoma, Sasu
    University of Helsinki, Finland.
    Hui, Pan
    University of Helsinki, Finland; The Hong Kong University of Science and Technology, Hong Kong.
    Enhancing the internet of things with knowledge-driven software-defined networking technology: Future perspectives2020In: Sensors, E-ISSN 1424-8220, Vol. 20, no 12, p. 1-20, article id 3459Article in journal (Refereed)
    Abstract [en]

    The Internet of Things (IoT) connects smart devices to enable various intelligent services. The deployment of IoT encounters several challenges, such as difficulties in controlling and managing IoT applications and networks, problems in programming existing IoT devices, long service provisioning time, underused resources, as well as complexity, isolation and scalability, among others. One fundamental concern is that current IoT networks lack flexibility and intelligence. A network-wide flexible control and management are missing in IoT networks. In addition, huge numbers of devices and large amounts of data are involved in IoT, but none of them have been tuned for supporting network management and control. In this paper, we argue that Software-defined Networking (SDN) together with the data generated by IoT applications can enhance the control and management of IoT in terms of flexibility and intelligence. We present a review for the evolution of SDN and IoT and analyze the benefits and challenges brought by the integration of SDN and IoT with the help of IoT data. We discuss the perspectives of knowledge-driven SDN for IoT through a new IoT architecture and illustrate how to realize Industry IoT by using the architecture. We also highlight the challenges and future research works toward realizing IoT with the knowledge-driven SDN.

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  • 17.
    Magalhães, Regina
    et al.
    University de Alcalá, Spain.
    Pereira, Joao
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Tarasenko, Oleksandr
    RISE Research Institutes of Sweden.
    Martin-Lopez, Sonia
    University de Alcalá, Spain.
    González-Herráez, Miguel
    University de Alcalá, Spain.
    Margulis, Walter
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware.
    Fidalgo Martins, Hugo
    CSIS Consejo Superior de Investigaciones Científicas, Spain.
    Towards Distributed Measurements of Electric Fields Using Optical Fibers: Proposal and Proof-Of-Concept Experiment.2020In: Sensors, E-ISSN 1424-8220, Vol. 20, no 16, article id E4461Article in journal (Refereed)
    Abstract [en]

    Nowadays there is an increasing demand for the cost-effective monitoring of potential threats to the integrity of high-voltage networks and electric power infrastructures. Optical fiber sensors are a particularly interesting solution for applications in these environments, due to their low cost and positive intrinsic features, including small size and weight, dielectric properties, and invulnerability to electromagnetic interference (EMI). However, due precisely to their intrinsic EMI-immune nature, the development of a distributed optical fiber sensing solution for the detection of partial discharges and external electrical fields is in principle very challenging. Here, we propose a method to exploit the third-order and second-order nonlinear effects in silica fibers, as a means to achieve highly sensitive distributed measurements of external electrical fields in real time. By monitoring the electric-field-induced variations in the refractive index using a highly sensitive Rayleigh-based CP-φOTDR scheme, we demonstrate the distributed detection of Kerr and Pockels electro-optic effects, and how those can assign a new sensing dimension to optical fibers, transducing external electric fields into visible minute disturbances in the guided light. The proposed sensing configuration, electro-optical time domain reflectometry, is validated both theoretically and experimentally, showing experimental second-order and third-order nonlinear coefficients, respectively, of χ(2) ~ 0.27 × 10-12 m/V and χ(3) ~ 2.5 × 10-22 m2/V2 for silica fibers.

  • 18.
    Seoane, Fernando
    et al.
    University of Borås, Sweden; Karolinska University hospital, Sweden; Karolinska Institutet, Sweden.
    Soroudi, Azadeh
    University of Borås, Sweden.
    Lu, Ke
    Chalmers University of Technology, Sweden.
    Nilsson, David
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Nilsson, Marie
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Abtahi, Farhad
    KTH Royal Institute of Technology, Sweden; Karolinska Institutet, Sweden.
    Skrifvars, Mikael
    University of Borås, Sweden.
    Textile-Friendly Interconnection between Wearable Measurement Instrumentation and Sensorized Garments-Initial Performance Evaluation for Electrocardiogram Recordings.2019In: Sensors, E-ISSN 1424-8220, Vol. 19, no 20, article id E4426Article in journal (Refereed)
    Abstract [en]

    The interconnection between hard electronics and soft textiles remains a noteworthy challenge in regard to the mass production of textile-electronic integrated products such as sensorized garments. The current solutions for this challenge usually have problems with size, flexibility, cost, or complexity of assembly. In this paper, we present a solution with a stretchable and conductive carbon nanotube (CNT)-based paste for screen printing on a textile substrate to produce interconnectors between electronic instrumentation and a sensorized garment. The prototype connectors were evaluated via electrocardiogram (ECG) recordings using a sensorized textile with integrated textile electrodes. The ECG recordings obtained using the connectors were evaluated for signal quality and heart rate detection performance in comparison to ECG recordings obtained with standard pre-gelled Ag/AgCl electrodes and direct cable connection to the ECG amplifier. The results suggest that the ECG recordings obtained with the CNT paste connector are of equivalent quality to those recorded using a silver paste connector or a direct cable and are suitable for the purpose of heart rate detection.

  • 19.
    Stöggl, Thomas Leonhard
    et al.
    University of Salzburg, Austria; Mid Sweden University, Sweden.
    Holst, Anders
    RISE, Swedish ICT, SICS. KTH Royal Institute of Technology, Sweden.
    Jonasson, Arndt
    RISE, Swedish ICT, SICS.
    Andersson, Erik Petrus
    Mid Sweden University, Sweden.
    Wunsch, Tobias
    University of Salzburg, Austria.
    Norström, Christer
    RISE, Swedish ICT, SICS.
    Holmberg, Hans Christer
    Mid Sweden University, Sweden; Swedish Olympic Committee, Sweden.
    Automatic classification of the Sub-Techniques (Gears) used in cross-country ski skating employing a mobile phone2014In: Sensors, E-ISSN 1424-8220, Vol. 14, no 11, p. 20589-20601Article in journal (Refereed)
    Abstract [en]

    The purpose of the current study was to develop and validate an automatic algorithm for classification of cross-country (XC) ski-skating gears (G) using Smartphone accelerometer data. Eleven XC skiers (seven men, four women) with regional-to-international levels of performance carried out roller skiing trials on a treadmill using fixed gears (G2left, G2right, G3, G4left, G4right) and a 950-m trial using different speeds and inclines, applying gears and sides as they normally would. Gear classification by the Smartphone (on the chest) and based on video recordings were compared. Formachine-learning, a collective database was compared to individual data. The Smartphone application identified the trials with fixed gears correctly in all cases. In the 950-m trial, participants executed 140 ± 22 cycles as assessed by video analysis, with the automatic Smartphone application giving a similar value. Based on collective data, gears were identified correctly 86.0% ± 8.9% of the time, a value that rose to 90.3% ± 4.1% (P < 0.01) with machine learning from individual data. Classification was most often incorrect during transition between gears, especially to or from G3. Identification was most often correct for skiers who made relatively few transitions between gears. The accuracy of the automatic procedure for identifying G2left, G2right, G3, G4left and G4right was 96%, 90%, 81%, 88% and 94%, respectively. The algorithm identified gears correctly 100% of the time when a single gear was used and 90% of the time when different gears were employed during a variable protocol. This algorithm could be improved with respect to identification of transitions between gears or the side employed within a given gear.

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