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  • 1.
    Ahmad, Jawad
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Andersson, Henrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Sidén, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Screen Printed Piezoresistive Sensors for Monitoring Pressure Distribution in Wheelchair2019In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 19, no 6, p. 2055-2063Article in journal (Refereed)
    Abstract [en]

    Prolonged sitting inadequacies cause pressure ulcer to many individuals, especially to disadvantaged with reduced mobility. The measurement of distributed pressure and detection of irregular sitting postures is essential for preventing the risk of developing pressure ulcer. In this paper, a pressure sensing system capable of recognizing sitting postures by means of measuring interface pressure through printed pressure sensors is presented. A thin and flexible large area sensor is screen-printed using silver flake and carbon particle inks and comprises 16 sensing elements. For the evaluation of practical usability, the sensor characterization is carried out by conducting stability, repeatability, drift and bending tests. The performance of the sensor is checked under varying environmental conditions. Sitting posture detection accuracy above 80 % is achieved using a classification algorithm for four different sitting postures. Pressure distribution is monitored at a scanning rate of 10 Hz. A low power and small form factor of read-out electronics enables a compact packaging inside the seat cushion. The presented sensor design targets smart wheelchairs, but it is extendable to much larger areas, for example to be used in beds. The proposed sensing system would be of a great assistance for caregivers and health professionals.

  • 2.
    Alam, Mohammad Anzar
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Manuilskiy, Anatoliy
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thim, Jan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Real time surface measurement technique in a wide range of wavelengths spectrum2014In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 14, no 1, p. 285-294Article in journal (Refereed)
    Abstract [en]

    Real time surface topography measurement in the paper and paperboard industries is a challenging research field. The existing online techniques measure only a small area of paper surface and estimate topographical irregularities in a narrow scale as a single predictor. Considering the limitations and complications in measuring the surface at high speed, a laser line triangulation technique is explored to measure surface topography in a wide scale. The developed technique is new for the paper and paperboard application that scans a line onto the paper-web surface up to 210 mm in length in the cross machine direction. The combination of a narrow laser linewidth imaging, a subpixel resolution, and the selection of a unique measurement location has made it possible to measure roughness and simultaneously characterize paper surface topography from 0.1 to 30 mm spatial wavelength. This spatial range covers wide scale surface properties such as roughness, cockling, and waviness. The technique clearly distinguishes and characterizes the surface of newspaper, and lightweight coated, coated, and uncoated paperboard in real time during the paper manufacturing process. The system temporal noise for the average roughness is estimated as 37 dB. The signal to noise ratio found is from 5.4 to 8.1 in the short spatial wavelength up to 1 mm, whereas it is more than 75 in the long spatial wavelength from 5 to 10 mm.

  • 3.
    Alam, Mohammad Anzar
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Manuilskiy, Anatoliy
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thim, Jan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Westerlind, Christina
    Performance and Prototyping Laboratory, SCA AB, Research and Development Centre, Sundsvall 852 37, Sweden .
    Limitation of a line-of-light online paper surface measurement system2014In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 14, no 8, p. 2715-2724Article in journal (Refereed)
    Abstract [en]

    A new prototype device has been developed based on a laser triangulation principle to measure online surface topography in the paper and paperboard industries. It characterizes the surface in a wide spatial scale of topography from 0.09-10 mm. The prototype's technique projects a narrow line-of-light perpendicularly onto the moving paper-Web surface and scattered reflected light is collected at a low angle, low specular, and reduced coherent length onto the CCD sensors synchronized with the laser sources. The scattering phenomenon determines surface deviations in the z-direction. The full-width, at half-maximum of a laser line in cross section is sensitive in computation of the surface topography. The signal processing aspect of the image processing, for example, threshold and filtering algorithms are also sensitive in estimating the accurate surface features. Moreover, improper light illumination, intensity, reflection, occlusion, surface motion, and noise in the imaging sensor, and so forth, all contribute to deteriorate the measurements. Optical techniques measure the surface indirectly and, in general, an evaluation of the performance and the limitations of the technique are both essential and challenging. The paper describes the accuracy, uncertainty, and limitations of the developed technique in the raw profiles and in terms of the rms roughness. The achieved image subpixel resolution is 0.01 times a pixel. Statistically estimated uncertainty (2σ) in the laboratory environment was found 0.05 μm for a smooth sample, which provides a 95% confidence level in the rms roughness results. The depth of field of the prototype is ~2.4 mm.

  • 4.
    Andersson, Henrik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Bertilsson, Kent
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thungström, Göran
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Processing and Characterization of a MOS Type Tetra Lateral Position Sensitive Detector with Indium Tin Oxide Gate Contact2008In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 8, no 9-10, p. 1704-1709Article in journal (Refereed)
    Abstract [en]

    A 2-D tetra lateral position sensitive detector (PSD) based on the metal-oxide-semiconductor (MOS) principle has been manufactured and characterized. The active area of the device is 5 nun x 5 mm and the intention is to use the central 4 nun x 4 nun for low nonlinearity measurements. The gate contact is made of indium tin oxide (ITO) that is a degenerate electrically conducting semiconductor, which, in addition, is also transparent in the visible part of the spectrum. The use of a MOS structure results in a processing with no necessity to use implantation or diffusion in order to make the resistive p-layer as in a conventional p-n junction lateral effect PSD. Position measurements show good linearity in the middle 4 nun x 4 mm area. Within the middle 2.1 mm x 2.1 mm, the nonlinearity is within 1.7% of the active area with a position detection error of maximum 60 mu m. Measured MOS IV characteristics are compared to a level 3 spice model fit and show good agreement. The threshold voltage is determined to be -0.03 V. Responsivity measurements show a high sensitivity in the visible spectral region.

  • 5.
    Andersson, Henrik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Manuilskiy, Anatoliy
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Gao, Jinlan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Lidenmark, Cecilia
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Sidén, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Forsberg, Sven
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Unander, Tomas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design. Dewire AB, Sundsvall 85185, Sweden.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Investigation of Humidity Sensor Effect in Silver Nanoparticle Ink Sensors Printed on Paper2014In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 14, no 3, p. Art. no. 6615915-Article in journal (Refereed)
    Abstract [en]

    Thin inkjet-printed tracks of silver nanoparticles have previously been observed to show a non-reversible decrease in resistance when exposed to a high degree of relative humidity and thus providing sensor functionality with a memory effect. This paper provides a more in-depth explanation of the observed humidity sensor effect that originates from inkjet-printed silver nanoparticle sensors on a paper substrate. It is shown that the geometry of the sensor has a large effect on the sensor's initial resistance, and therefore also on the sensor's resistive dynamic range. The importance of the sensor geometry is believed to be due to the amount of solvent from the ink interacting with the coating of the paper substrate, which in turn enables the diffusion of salts from the paper coating into the ink and thus affecting the silver ink.

  • 6.
    Andersson, Henrik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Manuilskiy, Anatoliy
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Unander, Tomas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lidenmark, Cecilia
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Forsberg, Sven
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Inkjet printed silver nanoparticle humidity sensor with memory effect on paper2012In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 12, no 6, p. 1901-1905Article in journal (Other academic)
    Abstract [en]

    In this paper, the design and the manufacture of an inkjet printed resistive type humidity sensor on paper are reported. After having been exposed to humidity above a given threshold level, the resistance of the sensor decreases substantially and remains at that level even when thehumidity is reduced. It is possible to deduce the humidity level by monitoring the resistance. The main benefit of the printed sensor presented in this case is in relation to its very low production costs. It has also been shown that both the ink type and this paper combination used prove to be crucial in order to obtain the desired sensor effect. More research is required in order to fully understand the humidity sintering effect on the nano particle ink and the role of the substrate. However, the observed effect can be put to use in printed humidity sensors which possess a memoryfunction. The sensor can be used in various applications for environmental monitoring, for example, in situations where a large number of inexpensive and disposable humidity sensors are required which are able to detect whether they have been subjected to high humidity. This could be the checking of transportation conditions of goods or monitoring humidity within buildings. © 2001-2012 IEEE.

  • 7.
    Ashraf, Shakeel
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Mattsson, Claes
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thungström, Göran
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Fabrication and characterization of a SU8-epoxy membrane based thermopile detector with an integrated multilayered absorber structure for the mid-IR region2019In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 19, no 11, p. 4000-4007Article in journal (Refereed)
    Abstract [en]

    This paper reports on the fabrication and characterization of a thermopile detector with an integrated mid-infrared absorber structure. The fabricated absorber structure has shown an absorption of more than 95% in the wavelength range of 3.2 – 5.47 μm. The detector was fabricated with standard cleanroom process techniques and equipment. The serial resistance was measured at about 315 kΩ at room temperature. The photosensitivity of the detector was characterized for a signle wavelength (4.26 µm) and a band of wavelength ranging from 2.5 –5.5 µm through two different measurement setups. In the first measurement setup, the photosensitivity was estimated at 57.5 V·mm2·W-1 through a MEMS-based infrared radiation source and with an optical band-pass filter of wavelength 4.26µm. The following characterization was performed to characterise the photosensitivity of the detector in a broader wavelength range. This measurement was taken using a monochromator setup utilizing a reference photodetector for calculations of the optical power of the infrared source. The photosensitivity and the specific detectivity (D*) of the fabricated detector were measured to values of 30-92 V·W-1 and 8.0×107-2.4×108 cm·Hz1/2·W-1, respectively, in the wavelength range of 2.8 – 5 µm. The time constant was estimated to around 21 ms

  • 8.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Caiola, Stefano
    Natl Instruments Italy, I-20090 Milan, Italy.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Sisinni, Emiliano
    Univ Brescia, Dept Informat Engn, I-25123 Brescia, Italy.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Channel Diagnostics for Wireless Sensor Networks in Harsh Industrial Environments2014In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 14, no 11, p. 3983-3995Article in journal (Refereed)
    Abstract [en]

    Wireless sensor network communication in industrial environments is compromised by interference, multipath fading, and signal attenuation. In that respect, accurate channel diagnostics is imperative to selecting the adequate countermeasures. This paper presents the lightweight packet error discriminator (LPED) that infers the wireless link condition by distinguishing between errors caused by multipath fading and attenuation, and those inflicted by interfering wideband single-channel communication systems (e.g., IEEE 802.11b/g), based on the differences in their error footprints. The LPED uses forward error correction in a novel context, namely, to determine the symbol error density, which is then fed to a discriminator for error source classification. The classification criteria are derived from an extensive set of error traces collected in three different types of industrial environments, and verified on a newly collected set of error traces. The proposed solution is evaluated both offline and online, in terms of classification accuracy, speed of channel diagnostics, and execution time. The results show that in ≥91% of cases, a single packet is sufficient for a correct channel diagnosis, accelerating link state inference by at least 270%, compared with the relevant state-of-the-art approaches. The execution time of LPED, for the worst case of packet corruption and maximum packet size, is below 30 ms with ≤3% of device memory consumption. Finally, live tests in an industrial environment show that LPED quickly recovers from link outage, by losing up to two packets on average, which is only one packet above the theoretical minimum.

  • 9.
    Cheng, Peng
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Nazar Ul Islam, Muhammad
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Torque Sensor Based on Differential Air Pressure Using Volumetric Strain2017In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 17, no 11, p. 3269-3277, article id 7902159Article in journal (Refereed)
    Abstract [en]

    This paper proposes a torque sensor based on the differential air pressure measurement method using the volumetric strain of a mechanical sensing structure. A model of the measurement system based on the differential air pressure from the volumetric strain of the mechanical sensing structure is proposed and theoretically discussed. The error sources are identified and an error propagation model is presented for the proposed torque measurement method. Considering these error sources, a prototype torque sensor is presented as a case study for the method verification. Both the mechanical and readout electronics designs are discussed and analyzed. The mechanical sensitivity, resolution, and maximum stresses are analyzed using finite-element modeling. Based on the results from the simulation, a prototype torque sensor is manufactured and experimentally verified using a readout electronics design. For verification, the sensor prototype is measured under static torque to have a sensitivity of 0.04272V/N. m and a range of +/- 117N . m. Compared with the nominal mechanical sensitivity result from the FEM simulation, this measured sensitivity has a difference less than 6%. The noise analysis of the designed readout electronics shows that the resolution of 0.006% can be achieved with this design. Furthermore, hysteresis analysis shows an error of 0.012% of full scale. From these results, it is also shown that the actual performance of the sensor is mainly limited by the differential pressure sensor and the readout electronics design and is not by the mechanical design of the sensor.

  • 10.
    Cheng, Peng
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Yang, Yan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Stator-free RPM Sensor Using Accelerometers - A Statistical Performance Simulation by Monte Carlo Method2011In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 11, no 12, p. 3368-3376Article in journal (Refereed)
    Abstract [en]

    This paper presents an statistical performance simulation for rigid-body revolutions per minute (RPM) measurement based on two uni-axial accelerometers mounted on rotor. In comparison with other existing sensing methods that are based on two coupled parts, namely stator and rotor and which include conventional electro-magnetic RPM sensors and photo-electric RPM sensors, this new stator-free inertial sensing principle has the advantage of high bandwidth at low RPM, true contact-free sensing and flexible installation. The paper first focuses on the description of the operating principle and the common mode rejection (CMR) method of the stator-free RPM sensor, and then its error model is developed and the error sources are statistically simulated based on Monte Carlo method. The simulation result presents a most interesting property of this sensor, that is, it gives lower precision at lower RPM and higher precision at higher RPM. The conclusion summarizes the modeling analysis result and motivates potential application for this new RPM sensing method.

  • 11.
    Farag, Hossam
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Österberg, Patrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    A Delay-Bounded MAC Protocol for Mission- and Time-Critical Applications in Industrial Wireless Sensor Networks2018In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 18, no 6, p. 2607-2616Article in journal (Refereed)
    Abstract [en]

    Industrial Wireless Sensor Networks (IWSNs) designedfor mission- and time-critical applications require timelyand deterministic data delivery within stringent deadline bounds.Exceeding delay limits for such applications can lead to system malfunction or ultimately dangerous situations that can threaten human safety. In this paper, we propose SS-MAC, an efficient slot stealing MAC protocol to guarantee predictable and timely channel access for time-critical data in IWSNs. In the proposed SS-MAC, aperiodic time-critical traffic opportunistically steals time slots assigned to periodic non-critical traffic. Additionally, a dynamic deadline-based scheduling is introduced to provide guaranteed channel access in emergency and event-based situations where multiple sensor nodes are triggered simultaneously to transmit time-critical data to the controller. The proposed protocol is evaluated mathematically to provide the worst-case delay bound for the time-critical traffic. Performance comparisons are carried out between the proposed SS-MAC and WirelessHARTstandard and they show that, for the time-critical traffic, theproposed SS-MAC can achieve, at least, a reduction of almost 30% in the worst-case delay with a significant channel utilization efficiency.

  • 12.
    Farag, Hossam
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Sisinni, Emiliano
    Brescia University, Brescia, Italy.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Österberg, Patrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Priority-Aware Wireless Fieldbus Protocol for Mixed-Criticality Industrial Wireless Sensor Networks2019In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 19, no 7, p. 2767-2780Article in journal (Refereed)
    Abstract [en]

    Industrial wireless sensor networks are becoming popular for critical monitoring and control applications in industrial automation systems. For such type of applications, providing reliable real-time performance regarding data delivery is considered as a fundamental challenge. The problem becomes more prominent with mixed-criticality systems, where different data flow with different levels of criticality (importance) coexist and characterized by different requirements regarding delay and reliability. In this paper, we propose a wireless fieldbus protocol to enable real-time communication and service differentiation for cluster-based mixed-criticality networks. A process monitoring scenario of plastic extrusion is used to define the protocol requirements and elaborate the working principle of the proposed work. In our proposed protocol, each data flow is scheduled for channel access based on its criticality level using a distributed prioritized medium access mechanism that ensures a guaranteed channel access for the most critical traffic over other traffic types. The performance of the proposed protocol is analyzed analytically using a discrete-time Markov chain model to evaluate the performance in terms of delay and throughput. Moreover, the extensive simulations are conducted to prove the analytical claims and different performance assessments are provided, which also demonstrate the effectiveness of the proposed approach compared with the related existing work.

  • 13.
    Gao, Jinlan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Sidén, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design. Sensible Solutions, Sundsvall SE-851 70, Sweden .
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Gulliksson, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Media and Communication Science. Sensible Solutions, Sundsvall SE-851 70, Sweden .
    Printed Humidity Sensor with Memory Functionality for Passive RFID tags2013In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 13, no 5, p. 1824-1834Article in journal (Refereed)
    Abstract [en]

    This paper presents a printed UHF RFID sensor solution that indicates whether a passive RFID tag has been exposed to a certain degree of humidity. The printed sensor operates as a Write Once Read Many (WORM) resistive memory as it permanently changes its resistance from about 2 kÙ to less than 50 Ù after exposure to humidity or water. The change of the sensor resistance is used to modulate the properties of a UHF RFID tag antenna by changing antenna input impedance and also introducing or removing ohmic losses in the antenna structure. The final result is reflected in the change of the minimum transmit power required to power-up the RFID tag. Both the sensor and the tag antenna are printed horizontally on a paper substrate. Different geometric combinations of sensor and antenna structures are investigated. Typical applications include non-invasive methods for detecting wetness or humidity levels in hidden locations such as within construction structures. The sensor setup can also serve to provide information as to whether a package sent over a supply chain has exceeded a certain level of humidity during its route.

  • 14.
    Guntupalli, Lakshmikanth
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Ghose, Debasish
    University of Agder, Norway.
    Li, Frank
    University of Agder, Norway.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Energy Efficient Consecutive Packet Transmissions in Receiver-initiated Wake-up Radio Enabled WSNs2018In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 18, no 11, p. 4733-4745Article in journal (Refereed)
    Abstract [en]

    In wake-up radio (WuR)-enabled wireless sensor networks, data communication among nodes is triggered in an on-demand manner, by either a sender or a receiver. For receiver-initiated WuR (RI-WuR), a~receiving node wakes up sending nodes through a wake-up call. Correspondingly sending nodes transmit packets in a traditional way by competing with one another multiple times in a single operational cycle. In~this paper, we propose a receiver-initiated consecutive packet transmission WuR (RI-CPT-WuR) medium access control (MAC) protocol, which eliminates multiple competitions to achieve higher energy efficiency. Furthermore, we develop two associated discrete time Markov chains (DTMCs) for evaluating the performance of RI-CPT-WuR and an existing RI-WuR MAC protocol. Using the solutions from the DTMC models, closed-form expressions for network throughput, average delay, packet reliability ratio, energy consumption and lifetime, and energy efficiency for both protocols are obtained. Numerical results demonstrate the superiority of the RI-CPT-WuR protocol.

  • 15.
    Jason, Johan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Arvidsson, Bertil
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Larsson, Anders
    Experimental Study of an Intensity Modulated Fiber-Optic Position Sensor with a Novel Readout System2008In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 8, no 7, p. 1105-1113Article in journal (Refereed)
    Abstract [en]

    An intensity modulated fiber-optic position sensor, based on a fiber to bundle coupling and a readout system using a CMOS image camera together with fast routines for position extraction and calibration, is experimentally demonstrated. Further a simulation of the complete sensor system setup is made, and possible sources of error are analyzed experimentally. Our analysis indicates the theoretical limit of the system and identifies the causes of system errors. The results are encouraging for further development of the system setup.

  • 16.
    Jonsson, Patrik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Casselgren, Johan
    Division of Experimental Mechanics, Luleå University of Technology, Luleå, Sweden .
    Road surface status classification using spectral analysis of NIR camera images2015In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 15, no 3, p. 1641-1656Article in journal (Refereed)
    Abstract [en]

    There is a need for an automated road status classification system considering the vast number of weather-related accidents that occur every winter. Previous research has shown that it is possible to detect hazardous road conditions, including, for example, icy pavements, using single point infrared illumination and infrared detectors. In this paper, we extend this research into camera surveillance of a road section allowing for classification of area segments of weather-related road surface conditions such as wet, snow covered, or icy. Infrared images have been obtained using an infrared camera equipped with a set of optical wavelength filters. The images have primarily been used to develop multivariate data models and also for the classification of road conditions in each pixel. This system is a vast improvement on existing single spot road status classification systems. The resulting imaging system can reliably distinguish between dry, wet, icy, or snow covered sections on road surfaces.

  • 17.
    Ma, Xinyu
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Bader, Sebastian
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Characterization of Indoor Light Conditions by Light Source Classification2017In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 17, no 12, p. 3884-3891, article id 7914682Article in journal (Refereed)
    Abstract [en]

    The characterization of light conditions plays an important role in the estimation of available energy levels to ambient light energy harvesting systems. Indoor light conditions are commonly described by illuminance levels. The same illuminance levels, however, can be generated by different light source types, which radiate different spectral components. This means that based on their spectral response, solar panels can produce different output powers even though identical illuminance levels are observed. We propose a method to distinguish these conditions based on limited spectral information. Using low-cost sensors, spectral characteristics of the light condition can be acquired and used to classify the underlying light source type, which allows for a more accurate estimation of the solar panel response. The method was evaluated experimentally for a number of common indoor light sources and under different conditions. Evaluation results have shown that the method can be used to distinguish the light sources under test with very high classification accuracy. Moreover, the method can be used accurately in situations with limited interference. This makes it a low-cost alternative to the characterization of light conditions using spectrometers, the use of which is infeasible in spatially distributed characterization applications.

  • 18.
    Mattsson, Claes
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thungström, Göran
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Bertilsson, Kent
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Martin, Hans
    SenseAir AB.
    Design of a Micromachined Thermopile Infrared Sensor with a Self-Supported SiO2/SU-8 Membrane2008In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 8, no 12, p. 2044-2052Article in journal (Refereed)
    Abstract [en]

    In the infrared region of the spectrum thermoelectric detectors such as the thermopile, are extensively used. These detectors rely on the well-known Seebeck effect, in which there is a direct conversion of thermoelectric differentials into electrical voltage. The temperature difference over thermocouple junctions is in general, created by forming a thin membrane connected to the silicon bulk. In many existing thermopiles, materials such as Si and Si3N4 have been used as membrane. These materials suffer from relatively high thermal conductivity, which lowers the membrane temperature and reduces the sensitivity of the detector. A material such as SU-8 2002 has a much lower thermal conductivity and is applied using standard photolithographic processing steps. This work presents thermal simulations regarding the use of SU-8 2002 as a thermal insulating membrane as compared to Si and Si3N4. The simulation results presented show that the temperature increase in a 5 µm SiO2/SU-8 membrane is about 9% higher than in a 1 µm Si3N4 membrane, despite the membrane thickness being increased by a factor of 5. A thermopile consisting of 196 serially interconnected Ti/Ni thermocouples positioned on a 5 µm SiO2/SU-8 2002 membrane has been fabricated. The sensitivity of the fabricated device has been evaluated in the infrared region, using a 1.56 µm IR laser and a xenon arc lamp together with a monochromator. The measurement results show a sensitivity of approximately 5 V/W over the wavelength range between 900 - 2200 nm. Measurements performed in a vacuum chamber show that the sensitivity of the detector could be increased by more than a factor of 3 by mounting the detector in a vacuum sealed capsule.

  • 19.
    Mattsson, Claes
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thungström, Göran
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Rödjegård, Henrik
    SenseAir.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Martin, Hans
    SenseAir.
    Experimental evaluation of a thermopile detector with SU-8 membrane, in a carbon dioxide meter setup2009In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 9, no 12, p. 1633-1638Article in journal (Refereed)
    Abstract [en]

    Continuous control of the carbon dioxide levels in the ventilation systems in office buildings and public schools has been shown to increase productivity and save money. However, these measurement systems require further developments in order to be more cost effective. This paper presents an evaluation of an Al/Bi thermopile detector with a 4 µm thin SiO2/SU-8 membrane in a CO2 meter application using the NDIR (Non-Dispersive Infrared Technology). The system consists of an 11 cm aluminum tube, used as the sample chamber and in which a light source and a thermopile detector with a 4.26 µm optical bandpass filter are positioned on its opposite sides. The light source is pulsed with a frequency of 0.5 Hz. The voltage response of the Al/Bi thermopile is measured for different CO2 concentrations, and, as expected according to the Lambert-Beer law, there is an exponential decrease in the measured intensity. The absolute response is about 50 % lower than for a commercial HMS J21 thermopile from Heimann Sensor GmbH. In relative terms, on the other hand, the Al/Bi thermopile is more sensitive for changes in the CO2 concentration. At 7500 ppm, the voltage response has decreased to 40 % of the reference response measured in the nitrogen atmosphere.

  • 20.
    Nilsson, Hans-Erik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Andersson, Henrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Manuilskiy, Anatoliy
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Unander, Tomas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Hammarling, Krister
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Sidén, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Gulliksson, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Printed write once and read many sensor memories in smart packaging applications2011In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 11, no 9, p. 1759-1767Article in journal (Refereed)
    Abstract [en]

    A horizontal printed Write Once Read Many (WORM) resistive memory has been developed for use in wireless sensortags targeting single event detection in smart packaging applications. The WORM memory can be programmed using a 1.5 V printedbattery. An alternative programming method is to use chemical sintering which allows the development of exposure-time triggeredsingle event tags that can be accessed wirelessly. The new WORM memory has very low losses in the ON-state which allows directintegration into antenna structures.A sensor tag that utilizes the WORM memory functionality and the well established Electronic Article Surveillance (EAS)communication standard has been outlined. Both active and fully passive sensor tag solutions have been proposed.The role of printed electronics in smart packaging applications has been reviewed and discussed. Important enabling factors forthe future development have been highlighted, such as the need for hierarchical design and test tools, better printed interconnecttechnologies as well as better components that allow communication with existing information and communication technology (ICT)standards. This is illustrated and underlined by the presented smart packaging concept demonstrators.

  • 21.
    Rydblom, Staffan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Liquid Water Content and Droplet Sizing Shadowgraph Measuring System for Wind Turbine Icing Detection2016In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 16, no 8, p. 2714-2725, article id 7384444Article in journal (Refereed)
    Abstract [en]

    This study shows that the liquid water content (LWC) and the median volume diameter (MVD) can be derived from images of water droplets using a shadowgraph imaging system with incoherent LED illumination.

    Icing on structures such as a wind turbine is the result of a combination of LWC and MVD and other parameters like temperature, humidity and wind speed. Today, LWC and MVD are not commonly measured for wind turbines. Systems for measuring these properties are often expensive or impractical in terms of location or remote reading. The aim of this study is to gain knowledge about how to design a single instrument based on imaging that has the ability to measure these properties with enough precision and accuracy to detect icing conditions for wind turbines.

    A method to calculate both the LWC and the MVD from the same images is described in this paper. The size of one droplet is determined by measuring the shadow created by the droplet in background illumination. The concentration is calculated by counting the measured droplets and estimating the volumes in which these droplets can be observed.

    In the described study, the observation volume is shown to be dependent on the particle size and the signal to noise ratio (SNR) for each measured particle. An expected coefficient of variation of the LWC depending on the droplet size is shown to be 2.4 percent for droplets 10 µm in diameter and 1.6 percent for 25 µm droplets. This is based on an error estimation of the laboratory measurements calibrated using a micrometer dot scale.

  • 22.
    Shahzad, Khurram
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Cheng, Peng
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Architecture exploration for a high-performance and low-power wireless vibration analyzer2013In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 13, no 2, p. 670-682Article in journal (Refereed)
    Abstract [en]

    Vibration based condition monitoring is considered to be the most effective method for analyzing the performance of rotating machinery and for early fault detection. Traditional vibration analyzers used for this purpose provide wired interface(s) to connect sensors with the system that analyzes the vibration data. A wireless vibration analyzer can be useful to monitor and analyze the vibration of rotating as well as inaccessible parts of the machinery. However, for a wireless vibration analyzer, both the performance and power consumption are of major concern, especially for real-time tri-axes (horizontal, vertical, and axial) vibration data processing and analyses at a high sampling rate. To evaluate the performance of such an analyzer, we explore different architectures in order to realize a high-performance and low-power wireless vibration analyzer that can be used in addition to traditional analyzers. For this purpose, four different architectures have been implemented in order to evaluate them in terms of performance, power consumption, cost, and design complexity.

  • 23.
    Unander, Tomas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Characterization of Printed Moisture Sensors in Packaging Surveillance Applications2009In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 9, no 8, p. 922-928Article in journal (Refereed)
    Abstract [en]

    This work presents a study on the performance of printed low cost moisture sensors fabricated using conductive ink on paper substrates. The sensors are intended to add value to the surveillance of packages. Two different kinds of sensors are evaluated and characterized. The two sensors have similar geometrical shapes, but different measuring principles are employed. The first sensor is measuring the moisture content in cellulose based substrates, while the second is measuring high levels of relative humidity in the surroundings. The sensors have been developed so that they can be integrated into Radio Frequency Identification (RFID) systems for surveillance in logistic chains. A laboratory setup of a RFID tag with sensor capability based on an ordinary passive RFID tag has been shown.

  • 24.
    Unander, Tomas
    et al.
    SCA R&D Ctr, SE-85121 Sundsvall, Sweden.
    Sidén, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Designing of RFID based Sensor Solution for Packaging Surveillance Applications2011In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 11, no 11, p. 3009-3018Article in journal (Refereed)
    Abstract [en]

    In this work, a two-chip battery assisted Radio Frequency Identification (RFID) based sensor platform is presented. The radio frequency communication interface is based on the EPC Gen 2 standard. A laboratory setup of the platform has been shown and characterized for a moisture content sensor application. The laboratory setup of the sensor platform has a reading range of 3.4 meters which is in comparison to commercial available Gen 2 tags. The laboratory platform has an average power consumption of 2.1 μW operating at 3 V, which together with a printed battery gives an estimated lifetime for data logging of several years. The proposed RFID platform provides a tradeoff between, communication performance, compatibility with international standards, and flexibility in on-package customization including type and number of sensors. The proposed architecture separates the high-performance communication circuit and the low-frequency sensor interface logic. In the future, the sensor interface maybe integrated using printed logics to further enhance the flexibility and low-ost customization features of the architecture

  • 25.
    Xu, Ye
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Bader, Sebastian
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    A Survey on Variable Reluctance Energy Harvesters in Low-Speed Rotating Applications2018In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 18, no 8, p. 3426-3435Article in journal (Refereed)
    Abstract [en]

    Energy harvesting converts ambient energy to electrical energy that can be used to power, for example, sensors and sensor systems. Variable reluctance energy harvesting is a suitable candidate for the conversion of rotary kinetic motion, an energy form commonly found in industrial applications. The implementation of a variable reluctance energy harvester, however, has a significant effect on its performance and is not well studied. In this paper, we therefore conduct a survey on different structures of variable reluctance energy harvesters. Six existing structures, previously used in variable reluctance sensors, are presented and analyzed according to their approaches for magnetic flux change improvement. Together with a newly proposed structure, these structures are evaluated based on a finite element analysis, and their results are compared. It is demonstrated that the choice of structure considerably affects the power output of the harvester and is dependent on the improvement approaches the structure utilizes. The newly proposed structure outperforms all existing structures with respect to power output and power density, which comes at a cost of higher parasitic torque generation. A 53-fold power improvement over the reference and an 1.2-fold power improvement over the next best structure is observed. As a result, applications of variable reluctance energy harvesting become viable even at low angular velocities.

  • 26.
    Zhang, Weiting
    et al.
    Beijing Jiaotong Univ, Beijing, Peoples R China.
    Yang, Dong
    Beijing Jiaotong Univ, Beijing, Peoples R China.
    Wang, Hongchao
    Beijing Jiaotong Univ, Beijing, Peoples R China.
    Huang, Xuefeng
    Beijing Sheenline Technol, Beijing, Peoples R China.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    CarNet: A Dual Correlation Method for Health Perception of Rotating Machinery2019In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 19, no 16, p. 7095-7106, article id 8695784Article in journal (Refereed)
    Abstract [en]

    As a key component of rotating machinery, the health perception of hearings is essential to ensure the safe and reliable operation of industrial equipment. In recent years, research on equipment health perception based on data-driven methods has received extensive attention. Overall, most studies focus on several public datasets to verify the effectiveness of their algorithms. However, the scale of these datasets cannot completely satisfy the representation learning of deep models. Therefore, this paper proposes a novel method, called CarNet, to obtain a more robust model and ensure that the model is sufficiently trained on a limited dataset. Specifically, it is composed of a data augmentation method named equitable sliding stride segmentation (ESSS) and a hybrid-stacked deep model (HSDM). The ESSS not only amplifies the scale of the original dataset but also enables newly generated data with both spatial and temporal correlations. The HSDM can, therefore, extract shallow spatial features and deep temporal information from the strongly correlated 2-dimensional (2-D) sensor array using a CNN and a bi-GRU, respectively. Moreover, the integrated attention mechanism contributes to focusing limited resources on informative areas. The effectiveness of CarNet is evaluated on the CWRU dataset, and an optimal diagnostic accuracy of 99.92% is achieved.

  • 27.
    Zheng, Tao
    et al.
    Beijing Jiaotong Univ, Sch Elect & Informat Engn, Beijing 100044, Peoples R China.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Åkerberg, Johan
    ABB Corp Res, Forskargrand 7, S-72178 Västerås, Sweden.
    WirArb: A New MAC Protocol for Time Critical Industrial Wireless Sensor Network Applications2016In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 16, no 7, p. 2127-2139, article id 7343746Article in journal (Refereed)
    Abstract [en]

    Wireless sensor networks are typically designed for condition monitoring applications and to conserve energy but not for time-critical applications with strict real-time constraints that can be found in the industrial automation and avionics domain. In this paper, we propose a novel medium access control (MAC) protocol defined as wireless arbitration (WirArb) which grants each user channel access based on their different priority levels. The proposed MAC protocol supports multiple users and each user is pre-assigned a specific arbitration frequency which decides the order of channel access. With this mechanism, we can ensure that the user with the highest priority will immediately gain channel access and we can guarantee a deterministic behavior. To evaluate the proposed MAC, we use a discrete-time Markov chain model to mathematically formulate the WirArb protocol. Our results show that the proposed protocol provides high performance to ensure deterministic real-time communication and bandwidth efficiency.

1 - 27 of 27
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