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  • 1.
    Ahlin, Eddie
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Implementation and standardization of vibration measurements in strip production processes2023Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    Within the era of the fourth industrial revolution the steel production industry is faced with demands of lower environmental impact and more cost-effective production are some of the challenges faced. To achieve more sustainable and efficient manufacturing processes companies try to digitalize and automate their production to a greater extent. Creating more robust, energy-efficient and adaptable solutions to increase the competitiveness of their company.

    This master thesis is about reverse engineering an existing solution for vibration measurements used at Alleima Strip. The goal was to create a new in-house solution for vibration measurements according to local programming standards using an ABB AC500v2 CPU paired with a FM502-CMS module. Using vibration measurements as a health indicator Alleima Strip hopes to progress their way of working with maintenance towards being more condition based.

    The result is a solution for vibration measurements customized for Alleima Strip. The report contains suggestions for improvements of the developed solution as well as ideas for future work.

    Fulltekst (pdf)
    fulltext
  • 2.
    Ahlin, Eddie
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Presentation och lagring av data från vibrationsmätning utförd i ett kallvalsverk2020Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Digitaliseringen innebär att stålindustrin idag står inför stora utmaningar, där krav på minskad miljöpåverkan i kombination med hög konkurrens ställer höga förväntningar på stålindustrins tillverkningsmetoder. För att erhålla en mer hållbar tillverkningsprocess och höja sin konkurrenskraft väljer många industrier att försöka digitalisera sin verksamhet i allt större utsträckning. Som ett steg i sin digitaliseringsprocess har Sandvik SMT Strip utökat ett befintligt styrsystem med en CMS-modul och givare för vibrationsmätning.

    Detta examensarbete ämnar presentera ett proof of concept för lagring och visning av data från vibrationsmätning i ett kallvalsverk vid Sandvik SMT Strip. Arbetet har bedrivits som en del av ett pilotprojekt hos Sandvik SMT Strip. Målsättningen med pilotprojektet är att uppnå en välfungerande implementering av vibrationsmätning för att kunna börja arbeta mer prediktivt med underhåll som idag sker helst proaktivt, men också reaktivt. Om en omställning kan göras där mer underhåll kan ske prediktivt är förväntningarna att kunna spara tid och resurser.

    Metoden för arbetet har varit av experimentell utvecklings-karaktär där det önskade resultatet varit styrande. Resultatet som presenteras i detta examensarbete är ett lösningsförslag på hur datalagring och presentation av vibrationsmätning med tillhörande frekvensanalys kan komma att se ut. Vidare har vissa delar av lösningsförslaget påbörjats med målet att visa upp ett proof of concept.

    Den slutsats som kan dras av arbetet är att en implementation för lagring och presentation av data med efterfrågad hård- och mjukvara är möjlig, men vidare arbete behövs för att erhålla ett proof of concept.

    Fulltekst (pdf)
    fulltext
  • 3.
    Ahmed, Rijon
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Evaluation, Design & Development of a Prototype 3-Link Mini Robot Manipulator2022Independent thesis Advanced level (degree of Master (Two Years)), 80 poäng / 120 hpOppgave
    Abstract [en]

    A 3-link robotic arm was designed, constructed, and tested as part of the thesis work. This prototype will assist students in applying their robotics and control system theory knowledge to real results. The kinematic equations are created to help with trajectory planning. Evaluation of different parameters was determined like (angles at which the servo motor operated, link length at which the servo can carry, spatial velocity, DH parameter, and Homogeneous transformation matrix). An Arduino-based closed-loop control system is built. Four Servo motors were used which are being controlled by Arduino UNO and Leonardo. The Arduino IDE is used to write proper codes. The main aim of the study was to apply the knowledge of robotics and control systems to develop a functional mini robot from scratch. Specifically, the thesis presents how to build a robotic arm that can move and lift objects. And, this task is done by using different controlling techniques where potentiometer, Bluetooth Module, and IR senor were used and compared which technique gives better results. The structural components had several issues. The project's linkages foundation and gripper are all 3-D printed pieces that are being designed using Autodesk Inventor Professional 2021 software. Although they did not cause any problems with strength, there were some difficulties with properly tightening the gears onto the shaft. To overcome these difficulties glue is being used so that all servo motors hold with the link properly. In a broad sense, the robot can position and orient the end-effector to pick and place the object accurately from a distance.

    Fulltekst (pdf)
    fulltext
  • 4.
    Ali, ZAKI
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Självbalansering av MinSeg2019Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
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  • 5.
    Alizadeh, Mahmoud
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik. KTH, Teknisk informationsvetenskap.
    Characterisation, Modelling and Digital Pre-Distortion Techniques for RF Transmitters in Wireless Systems2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Wireless systems have become an inevitable part of modern technologies serving humankind. The rapid growth towards large dimensional systems, e.g. 5th generation (5G) technologies, incurs needs for improving the performance of the systems and considering aspects to make them as far as possible environmentally friendly in terms of power efficiency, cost, and so on. One of the key parts of every wireless communication system is the radio frequency (RF) power amplifier (PA), which consumes the largest percentage of the total energy. Hence, accurate models of RF PAs can be used to optimize their design and to compensate for signal distortions. This thesis starts with two methods for frequency-domain characterisation to analyse the dynamic behaviour of PAs in 3rd-order non-linear systems. Firstly, two-tone signals superimposed on large-signals are used to analyse the frequency-domain symmetry properties of inter-modulation (IM) distortions and Volterra kernels in different dynamic regions of RF PAs in a single-input single-output (SISO) system. Secondly, three-tone signals are used to characterise the 3rd-order self- and cross-Volterra kernels of RF PAs in a 3 × 3 multiple-input multiple-output (MIMO) system. The main block structures of the models are determined by analysing the frequency-domain symmetry properties of the Volterra kernels in different three-dimensional (3D) frequency spaces. This approach significantly simplifies the structure of the 3rd-order non-linear MIMO model.

    The following parts of the thesis investigate techniques for behavioural modelling and linearising RF PAs. A piece-wise modelling technique is proposed to characterise the dynamic behaviour and to mitigate the impairments of non-linear RF PAs at different operating points (regions). A set of thresholds decompose the input signal into several sub-signals that drive the RF PAs at different operating points. At each operating point, the PAs are modelled by one sub-model, and hence, the complete model consists of several sub-models. The proposed technique reduces the model errors compared to conventional piece-wise modelling techniques.

    A block structure modelling technique is proposed for RF PAs in a MIMO system based on the results of the three-tone characterisation technique. The main structures of the 3rd- and higher-order systems are formulated based on the frequency dependence of each block. Hence, the model can describe more relevant interconnections between the inputs and outputs than conventional polynomial-type models.

    This thesis studies the behavioural modelling and compensation techniques in both the time and the frequency domains for RF PAs in a 3 × 3MIMO system. The 3D time-domain technique is an extension of conventional 2D generalised memory polynomial (GMP) techniques. To reduce the computational complexity, a frequency-domain technique is proposed that is efficient and feasible for systems with long memory effects. In this technique, the parameters of the model are estimated within narrow sub-bands. Each sub-band requires only a few parameters, and hence the size of the model for each sub-band is reduced.

  • 6.
    Alizadeh, Mahmoud
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik. KTH, Teknisk informationsvetenskap.
    Händel, Peter
    KTH, Teknisk informationsvetenskap.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Behavioral modeling and digital pre-distortion techniques for RF PAs in a 3 × 3 MIMO system2019Inngår i: International journal of microwave and wireless technologies, ISSN 1759-0795, E-ISSN 1759-0787, Vol. 11, nr 10, s. 989-999Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Modern telecommunications are moving towards (massive) multi-input multi-output systems in 5th generation (5G) technology, increasing the dimensionality of the system dramatically. In this paper, the impairments of radio frequency (RF)power amplifiers (PAs) in a 3x3 MIMO system are compensated in both time and frequency domains. A three-dimensional(3D) time-domain memory polynomial-type model is proposed as an extension of conventional 2D models. Furthermore, a 3D frequency-domain technique is formulated based on the proposed time-domain model to reduce the dimensionality of the model, while preserving the performance in terms of model errors. In the 3D frequency-domain technique, the bandwidth of a system is split into several narrow sub-bands, and the parameters of the system are estimated for each subband. This approach requires less computational complexity, and also the procedure of the parameters estimation for each sub-band can be implemented independently. The device-under-test (DUT) consists of three RF PAs including input and output cross-talk channels. The proposed techniques are evaluated in both behavioural modelling and digital pre-distortion(DPD) perspectives. The results show that the proposed DPD technique can compensate the errors of non-linearity and memory effects by about 23.5 dB and 7 dB in terms of the normalized mean square error and adjacent channel leakage ratio, respectively.

  • 7.
    An, Siwen
    et al.
    Mittuniversitet.
    Reza, Salim
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Norlin, Börje
    Mittuniversitet.
    Fröjdh, Christer
    Mittuniversitet.
    Thungström, Göran
    Mittuniversitet.
    Signal-to-noise ratio optimization in X-ray fluorescence spectrometry for chromium contamination analysis2021Inngår i: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 230, artikkel-id 122236Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In most cases, direct X-ray fluorescence (XRF) analysis of solutions entails technical difficulties due to a high X-ray scattering background resulting in a spectrum with a poor signal-to-noise ratio (SNR). Key factors that determine the sensitivity of the method are the energy resolution of the detector and the amount of scattered radiation in the energy range of interest. Limiting the width of the primary spectrum by the use of secondary targets, or filters, can greatly improve the sensitivity for specific portions of the spectrum. This paper demonstrates a potential method for SNR optimization in direct XRF analysis of chromium (Cr) contamination. The suggested method requires minimal sample preparation and achieves higher sensitivity compared to existing direct XRF analysis. Two states of samples, fly ash and leachate from municipal solid waste incineration, were investigated. The effects of filter material, its absorption edge and filter thickness were analyzed using the combination of Monte Carlo N-Particle (MCNP) code and energy-dispersive XRF spectrometry. The applied filter removes primary photons with energies interfering with fluorescence photons from the element of interest, thus results in lower background scattering in the spectrum. The SNR of Cr peak increases with filter thickness and reaches a saturation value when further increased thickness only increases the measurement time. Measurements and simulations show that a Cu filter with a thickness between 100 μm and 140 μm is optimal for detecting Cr by taking into account both the SNR and the exposure time. With direct XRF analysis for solutions, the limit of quantitation (LOQ) of the achieved system was 0.32 mg/L for Cr, which is well below the allowed standard limitation for landfills in Sweden. This work shows that XRF can gain enough sensitivity for direct monitoring to certify that the Cr content in leachate is below environmental limits.

    Fulltekst (pdf)
    fulltext
  • 8.
    Andersson, Rabé
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    The Robustness and Energy Evaluation of a Linear Quadratic Regulator for a Rehabilitation Hip Exoskeleton2022Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The implications of gait disorder, muscle weakness, and spinal cord injuries for work and age-related mobility degradation have increased the need for rehabilitation exoskeletons. Specifically, the hip rehabilitation exoskeletons due to a high percentage of the mechanical power is generated by this join during the gait cycle. Additionally, the prolonged hospitalisation after hip replacement and acetabular surgeries that affect human mobility, the social-economic impacts and the quality of life. For these reasons, a hip rehabilitation exoskeleton was our focus in this research, as it will contribute being a sustainable solution to take over the burden of physiotherapy and let patients perform their rehabilitation at home or outdoors. 

    This thesis details an approach of creating a hip rehabilitation exoskeleton, starting with modelling, simulating, and controlling the rehabilitation hip joint in a based-simulation environment. The mathematical model and the reason for using a series elastic actuator in the hip joint to execute the movement in a sagittal plane are more detailed. Because trajectory tracking is commonly used for controlling rehabilitation exoskeletons to ensure safe and reliable motion tracking methods; therefore, two desired torque signals were tested and analysed with the optimal linear quadratic regulator (LQR). The experiments were performed using two torque signals of a healthy hip joint—representing the sit-to-stand (STS) and the walking activity for their importance in lower limb movements. However, the mathematical model used as a basis of the optimal control strategy is usually influenced by multiple sources of uncertainties. Therefore, four case studies of various optimal control strategies were tested for a twofold reason: to choose the most optimal control strategy, and to test the energy consumption of these cases during the STS and walking movements, because the long-term goal is to produce a lightweight and reliable rehabilitation hip exoskeleton.

    The research showed compelling evidence that tuning the control strategy will not influence the robustness of an optimal controller only, but affect the energy consumption during the STS and walking activity, which needs to be considered in exoskeleton control design regarding its applications.

    Fulltekst (pdf)
    fulltext
  • 9.
    Andersson, Rabé
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    The Energy Consumption and Robust Case Torque Control of a Rehabilitation Hip Exoskeleton2022Inngår i: Applied Sciences, E-ISSN 2076-3417, Vol. 12, nr 21, artikkel-id 11104Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gait disorders, muscle weakness, spinal cord injuries (SCIs) and other work-related disorders have increased the need for rehabilitation exoskeletons—specifically, for the hip because a huge percentage of mechanical power comes from the hip joint. However, realising a lightweight rehabilitation hip exoskeleton for mobility and at-home use with reliable control is challenging. The devices developed are restricted by a joint actuator and energy source design and tend to have various uncertainties. Thus, this study tested the robustness of four optimal controller cases in a simulation-based environment. We sought to determine whether the most robust optimal controller consumed less energy and demonstrated better performance in tracking the desired signal. The robustness of the optimal cases was tested with the hip torque signals of healthy subjects. The number of sit-to-stand (STS) instances and the walking distance at various speeds were calculated. The results showed that the most robust case controller was more energy efficient for STS, but not for walking activity. Furthermore, this study provides compelling evidence that various optimal controllers have different degrees of robustness and effects on energy consumption.

    Fulltekst (pdf)
    fulltext
  • 10.
    Andersson, Rabé
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    The MATLAB Simulation and the Linear Quadratic Regulator Torque Control of a Series Elastic Actuator for a Rehabilitation Hip Exoskeleton2022Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Almost the half of mechanical energy of a human gait cycle is generated by a hip joint. Therefore, this paper discusses a rehabilitation hip exoskeleton, starting with the modeling, simulation and ending with controlling its hip joints. A MATLAB based simulation environment with the use of Simscape Multibody toolbox was utilized to design and control the robotic hip exoskeleton. More details of adding a series elastic actuators (SEA) to the hip joints with the mathematical model are presented. However, the linearised mathematical model of the entire exoskeleton was found in simulation software which establish the basic need of controlling hip joints. The trajectory tracking is commonly used of controlling rehabilitation exoskeleton and to ensure a safe and reliable motion tracking methods, two desired torque signals were tested and analysed with the optimal linear quadratic regulator (LQR). The experiments with two torque signals–representing the sit-to-stand (STS) and the walking activity, demonstrated good performance of the motion gait tracking based on torque signals of a healthy person, which is carried out in the simulation environment. Furthermore, some studies in a human robot interaction are also mentioned in this paper.

  • 11.
    Andersson, Rabé
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    The Technical Challenges in Orthotic Exoskeleton Robots with Future Directions: a Review Paper2023Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The robotic wearable exoskeletons have been developed due to various advantages offered by these devices. These advantages are manifested by integrating the human and a robot into one system under the user's control, which motivated researchers to develop different exoskeletons through years. However, several advances in exoskeleton; still, dealing with the various technical challenges in designing these impressive devices is inevitably. This paper aims to introduce informative resources and quick guidance of various technical challenges as such information is critical for exoskeleton development. The constructive discussion is intended to encourage researchers, innovators and academia to be aware of these challenges. Finally, the contemporary research gaps with various challenges have been highlighted, which remain to be solved as well as some future directions in this field that will have far-reaching effects on developing exoskeletons.

  • 12.
    Andersson, Rabé
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Robots are a promising investment to fight pandemics2021Inngår i: 2021 8th International Conference on Signal Processing and Integrated Networks (SPIN), IEEE , 2021, s. 458-463Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Coronavirus caused pandemics as many viruses did through human history. The current pandemic causes overwhelmed healthcare system, locked down cities, and massive fatality among humans. Thus, different robots have been used since the COVID outbreak worldwide to reduce spreading infectious diseases and support frontline healthcare workers. This paper sets out the different robots implemented for hospital, non-hospital use, and possible use that can be deployed amidst the pandemic. A literature survey of versatile robots during COVID-19 is introduced. Roboticists contributed with wheeled and drone robots with various applications to assist medical care systems and society during the ongoing crisis. Pandemics are common throughout human history and difficult to avoid or prevent; thus, we intend to encourage societies, academia, engineers and innovators to invest more in robots that cannot catch the virus and consequently introduce beneficial solutions to fight such pandemic in the future.

  • 13.
    Argume, A.
    et al.
    Universidad Privada de Tacna, Peru.
    Coaguila, R.
    Universidad Católica de Santa María, Peru.
    Yanyachi, P. R.
    Universidad Nacional San Agustin de Arequipa, Peru.
    Chilo, José
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    NOAA Image Data Acquisition to Determine Soil Moisture in Arequipa - Perú2021Inngår i: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 68, nr 8, s. 1933-1936Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In recent years, irrigations have been built on dry areas in Majes-Arequipa. Over time, the irrigations water forms moist areas in lower areas, which can have positive or negative consequences. Therefore, it is important to know in advance where the water from the new irrigation will appear. The limited availability of real-time satellite image data is still a hindrance to some applications. Data from environmental satellites NOAA (National Oceanic and Atmospheric Administration) are available fee and license free. In order to receive data, users must obtain necessary equipment. In this work we present a satellite data acquisition system with an RTL SDR receiver, two 137-138 Mhz designed antennas, Orbitron, SDRSharp, WXTolmag and MatLab software. We have designed two antennas, a Turnstile Crossed dipole antenna with Balun and a quadrifilar helicoidal antenna. The antennas parameter measurements show very good correspondence with those obtained by simulation. The RTL SDR RTL2832U receiver, combined with our antennas and software, forms the system for recording, decoding, editing and displaying Automatic Picture Transmission (APT) signals. The results show that the satellite image receptions are sufficiently clear and descriptive for further analysis.

  • 14.
    Argume, Abel
    et al.
    Universidad Privada de Tacna, Peru.
    Coaguila, Ronald
    Universidad Nacional de San Agustin, Arequipa, Peru.
    Yanyachi, Pablo
    Universidad Nacional de San Agustin, Arequipa, Peru.
    Chilo, José
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Design of Turnstile, Quadrifilar Helical and V-Dipole Antennas to Obtain NOAA Images2020Inngår i: 2020 IEEE Congreso Bienal de Argentina (ARGENCON), IEEE , 2020Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Satellite image processing of an ecosystem allows us to understand it and know, prevent, and investigate the events that take place in the environment. For this we need cheap and simple image reception systems, which include antennas, receivers and hardware/software for signal processing. In this work a turnstile antenna, a quadrifilar helical antenna and a V-dipole antenna were designed, constructed and used to obtain automatic NOAA image transmission signal and convert to a NOAA satellite image.

  • 15.
    Axelsson, Patrik
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Analys och underhåll av komponenter i tuff kemisk miljö2021Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Examensarbetet som rapporten redovisar utfördes i ett av Volvo Group Truck Operation:s (GTO) gjuterier på motorfabriken i Skövde. Här används sandgjutning för att tillverka komponenter till lastbilsmotorer av gjutjärn. I gjutprocessentillverkas sandkärnor enligt Epoxy-SO2-metoden. Sandkärnorna hanteras av robotar i slutna celler. Underhållsavdelningen upplever att komponenter på robotverktygensom förflyttar kärnorna har kort livslängd. En teori är att detta beror påexponeringen för SO2. Forskning visar på att vissa material som exponeras för svaveldioxid (SO2) bland annat korrodera eller bli spröda. Korrosionsprocessen för metaller kan öka om SO2 reagerar tillsammans med vatten och syrgas och bildar svavelsyrlighet (H2SO3) eller svavelsyra (H2SO4). För att den här kemiska processen ska påbörjas krävs en relativluftfuktighet om minst 60%. Polymerer som plast och gummi kan svälla, lösas uppeller bli spröda vid exponering för SO2 , H2SO3 eller H2SO4. Slutmålet med examensarbetet är att definiera lämpliga komponenter åtunderhållsavdelningen som ska användas vid renovering av robotverktygen. Innan detta kan utföras behöver verktygen brytas ner på komponentnivå ochdokumenteras i ett underhållssystem. Vidare kommer mätningar på koncentrationav svaveldioxid, luftfuktighet samt temperatur utföras i robotcellerna. Resultatet från mätningarna används som underlag för att ta reda på om det finns liknande komponenter som tål miljön i robotcellen bättre. När verktygen slutligen renoverats kommer förhoppningsvis de oplanerade stoppen minska. Om de oplanerade stoppen minskar kommer underhållskostnaderna kopplat till robotcellerna också minska. Enligt mätningarna var inte luftfuktigheten tillräckligt hög för att komponenterna i robotcellerna ska riskera att korrodera på grund av exponering för SO2. Däremot ärmånga pneumatiska komponenter delvis tillverkade av plast som inte tål SO2. Många av de här komponenterna finns som alternativ tillverkade av till exempel nickel-pläterad mässing eller rostfritt stål som tål gasen. Examensarbetet har gett svar på frågeställningarna och lett fram till konkretaförbättringar. Det har även skapat nya idéer till fortsatt förbättringsarbete.

    Fulltekst (pdf)
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  • 16.
    Azizi, Hadi
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Simulerad nivåreglering av vattenkraftverk2022Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Vattenkraften är en viktig del av den svenska elförsörjningen och tillgodoser cirka 45 % av det årliga elbehovet i landet. Vattenkraften utnyttjar höjdskillnaden mellan inflödet och utflödet för att driva turbiner och producera el. I Sverige finns omkring 200 dammar med en fallhöjd större än 15 m och för höga nivåer vid någon av dessa skulle leda till ett dammbrott med omfattande konsekvenser. Ett viktigt område som det investeras mycket i idag är dammsäkerhet vilket går ut på att undvika okontrollerade översvämningar av dammen.

    Kännedom av fallhöjd och flöde är nödvändiga inom vattenkraft för att kunna beräkna producerad effekt och även vid dimensionering av dammar, vattenvägar och generatorer. Mättningar på inflödet till ett vattendrag anses vara mycket komplicerat och tidskrävande däremot kan utflödet genom utskoven beräknas med matematiska samband. Utskov avser öppningar i dammen som används för att avbörda vatten. Det finns således olika typer av utskov och det som påverkar valen är aspekter som kostnad, väderförhållanden, avbördningsförmåga, etc. För att undvika en möjlig överströmning av en damm dimensioneras ofta utskoven med avseende på vilken mängd vatten de bör avbörda. Ett krav som ofta ställs är att det ska vara möjligt att avbörda en vattendrags högsta vattennivå (HHQ). Några av de mest förekommande varianter av kontrollerade utskov i Sverige är valsdammar, luckdammar och bottenutskov.  

    Nivån i vattenmagasinet mäts upp med hjälp av sensorer som är placerade på olika platser vid dammen och uppmätta höga nivåer leder till att olika larmfunktioner löser ut. Regleringen av vattennivån sker då genom att avbörda vatten på ett kontrollerat sätt genom utskoven. 

    Genom att simulera regleringsprocessen av vattennivån i en virtuell miljö kan olika scenarier som kan uppstå vid magasinhantering testas på ett ekonomiskt sätt och hitta lämpliga reglerstrategier. Simuleringar är också en av de verktyg lyft fram inom industri 4.0 vilket kan bidra till framtidens lösningar inom automatiseringsprojekt. I arbetet studeras de olika beståndsdelar i ett vattenkraftverk och en tilltänkt metod presenteras för skapning av en virtuell modell av nivåregleringsprocessen i Siemens SIMIT, styrning av modellen via en virtuell PLC-enhet och visualisering av processen på en HMI-skärm.

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  • 17.
    Bai, S.
    et al.
    Department of Materials and Production, Aalborg University, Aalborg, Denmark.
    Christensen, S.
    Department of Materials and Production, Aalborg University, Aalborg, Denmark.
    Islam, M.
    Department of Materials and Production, Aalborg University, Aalborg, Denmark.
    Rafique, Sajid
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Masud, Nauman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Mattsson, Per
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    O’Sullivan, L.
    University of Limerick, Limerick, Ireland.
    Power, V.
    University of Limerick, Limerick, Ireland.
    Development and testing of full-body exoskeleton AXO-SUIT for physical assistance of the elderly2019Inngår i: Wearable Robotics: Challenges and Trends: Proceedings of the 4th International Symposium on Wearable Robotics, WeRob2018, October 16-20, 2018, Pisa, Italy / [ed] Maria Chiara Carrozza, Silvestro Micera, José L. Pons, Cham: Springer, 2019, Vol. 22, s. 180-184Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents the design and preliminary testing of a full-body assistive exoskeleton AXO-SUIT for older adults. AXO-SUIT is a system of modular exoskeletons consisting of lower-body and upper-body modules, and their combination as full body as well to provide flexible physical assistance as needed. The full-body exoskeleton comprises 27 degrees of freedom, of which 17 are passive and 10 active, which is able to assist people in walking, standing, carrying and handling tasks. In the paper, design of the AXO-SUIT is described. End-user testing results are presented to show the effectiveness of the exoskeleton in providing flexible physical assistance.

  • 18.
    Barron, Paul
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Data Analysis for Predictive Maintenance of a Straightening Machine in the Steel Industry2023Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The availability of industrial machinery is crucial to any business operating in the manufacturingsector. Mechanical failures halt production and unplanned downtime canbe disruptive and costly. Small failures can compound to serious failures which exponentiallyincreases downtime and repair costs. Therefore Identifying a degradationcondition before reaching failure is key to maintaining machine availability. On theother hand, it’s undesirable to spend resources performing maintenance that is notrequired. For these reasons a large field of academic work is dedicated to analyzingthe health of a machine, it’s remaining life and in turn preventing failures.

    This thesis analyses data from a tube straightening machine used in the steel industrywith the goal of implementing a condition monitoring strategy. The data comes froma real world application provided by a multinational manufacturer of steel products.It was obtained using the existing sensors and data acquisition system. The projectserves as a study of the existing infrastructure (available sensors) and it’s suitability forimplementing a condition monitoring strategy. The work is the first step in a largerstudy and does not attempt to perform any implementation or fault identification. Ina broad sense the aim of the project is to identify relationships and patterns in the datathat could be varying with time as the machine degrades.

    The data consists of twelve channels taken over a two week duration. It is prepossessedto isolate periods where the machine is operating and separated into cycles. Each ofthese is then further processed to extract time and frequency domain features. Thefeatures within each channel are compared with each other using the R2 coefficientof determination to find combinations that are correlated. A semi automated processis used to select the feature combinations. The same process is performed betweensignals for each feature.

    A number of linear regression models are created based on the results from the correlatedfeatures as well as some multivariate models. These are then compared usinga goodness of fit metric, Normalized Root Mean Square Error (NRMSE). Potentialclustering of machine states are highlighted based on observations in the feature combinations.The conclusions drawn from this study include identification of correlationsbetween signals, potential non-linear relationships and suggestions for future data collectionand analysis going forward. No one feature was identified as correlated betweenall signals.

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  • 19.
    Bautista Gonzalez, Oscar
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Integration of a Wireless Sensor Network and IoT in the HiG university2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The number of Internet of Things applications for Wireless Sensor Networks is increasing every year due to the emerging of new brands such as Big Data and Industry 4.0. With the rise of new technologies related to these fields, new opportunities have become possible with a reasonable cost, but the requirements of WSNs still being the same, where energy efficiency, robustness, scalability and others must be accomplished. The commercial hardware developed by companies can be configured through different programs to be compatible among them, taking into account multiple variables, protocols, mechanisms and options provided by new solutions. Therefore, the configuration of different devices and choosing the optimum configuration can become quite challenging due to the number of paths. In this thesis, the configuration of commercial devices provided is carried out to be able to apply this hardware in different Internet of Things applications for Wireless Sensor Networks. Transceivers, sensors of temperature, relative humidity and CO2, a gateway, and different development kits are provided on this work, where the selection of the software to set these devices is made. Repeaters are configured to be compatible with the sensors and perform under the TDMA protocol and the request-response pattern, which synchronize the communication on the network, and under the flooding mechanism, which allows to route packets through the nodes due to the short range of RF low power technologies. The connection between the WSN and the Internet is made through the GW, which is also connected to the WSN, under the TCP/IP protocol, which is configured to provide Message Queue Telemetry Transport and SecureSHell services to access the GW remotely through the Internet and send requests to the WSN automatically. Node-Red is the programming tool installed upon the GW to implement data processing, storage and visualization, via the JavaScript programming language, where the user can deploy the data, which is stored in a CSV file, to make an analysis and visualize the data and the status of the network through a live data dashboard. Finally, an experiment is carried out over the HiG university where sensors are placed to measure different halls of the university and integrate an Internet of Things application for a Wireless Sensor Network. Due to the followed process, we have been able to measure data of temperature, relative humidity and CO2 concentration levels, creating a WSN, where this data has been saved in a connected USB to the gateway. Having a performance of 90% of messages received by the GW, and we have also been able to connect the GW to the Internet, creating a system that can be accessed remotely via the MQTT broker and providing different services such as data visualization. 

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  • 20.
    Bautista Gonzalez, Oscar
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Chilo, José
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    WSN IoT Ambient Environmental Monitoring System2020Inngår i: 2020 IEEE 5th International Symposium on Smart and Wireless Systems within the Conferences on Intelligent Data Acquisition and Advanced Computing Systems (IDAACS-SWS), IEEE , 2020, s. 1-4Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Environmental monitoring plays a very important role for the health of people and the quality of life in daily places such as home, schools, offices and industries. The temperature, humidity and carbon dioxide concentration levels have to be limited in these environments. In this work, a system web-based environmental monitoring based on WSN technology is presented. Sensors, repeaters and a gateway form the WSN IoT system, where user-friendly interfaces are used to decrease the complexity of the set up. The control of the WSN and the gateway, and the data monitoring can be done through the web server running over the gateway along the software that provides user-friendly interfaces. The data visualization is displayed on a live data dashboard. The system is tested in a university and two industry environments.

  • 21.
    Bautista Gonzalez, Oscar
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    A Study of OBF-ARMAX Performance for Modelling of a Mechanical System Excited by a Low Frequency Signal for Condition Monitoring2023Inngår i: Recent Developments in Model-Based and Data-Driven Methods for Advanced Control and Diagnosis / [ed] Janusz Kacprzyk, Springer , 2023, s. 73-82Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    A digital twin of a mechanical system (a pair of axial rolls in a ring mill used in a steel plant) with poles close to the unit circle and the real axis in the discrete pole-zero map was built. The system was excited by a signal concentrated in the low-frequency band. For this particular case, it is shown that the ad-hoc combination of ARMAX and orthonormal basis filter model structures outperform model structures based on either ARMAX or orthonormal basis functions when estimating the poles of the basis by analyzing the data in the frequency domain. The followed modelling methodology of the system is described in detail to help replicate the work for similar systems in the steel industry. Real production data from a steel plant were used in contrast to previous studies, where the combination of ARX and ARMAX with orthonormal basis filter model structures was evaluated using simulated data instead of real data. We believe that the resultant model can be used when having systems with poles close to the unit circle and real axis and poor excited input signal concentrated in the low frequency band. The resultant model can be used for condition monitoring and failure detection.

  • 22.
    Bautista Gonzalez, Oscar
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Time series modelling of a radial-axial ring rolling system2023Inngår i: International journal of Modeling, identification and control, ISSN 1746-6172, E-ISSN 1746-6180, Vol. 43, nr 1, s. 13-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present work, a digital twin of a radial-axial ring rolling machine was built by modelling the time series of the positions of the tools and control signals rather than the metrics of the produced rings, as performed in previous studies. Real data from the industry was used for modelling. The used model selection methodology is shown in detail to replicate such work for similar systems in the steel industry. The modelling results of ARX, ARMAX and orthonormal basis model structures are shown; additionally, they were validated considering SISO and MIMO systems. The modelling results were better when the subsystems considered were ARMAX and MISO than when ARX and SISO were taken into consideration. The best modelling results were obtained when physical knowledge was included in the model structure. Lastly, it was found that the model error of the horizontal subsystem could be used for predictive maintenance.

  • 23.
    Bemani, Ali
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Collaborative Predictive Maintenance for Smart Manufacturing: From Wireless Control to Federated Learning2024Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Industry 4.0 represents a significant shift in the industrial landscape, aimed at improving efficiency, productivity, and competitiveness. This shift involves the digitalization of industries, impacting manufacturing and maintenance processes. A pivotal element of this transformation is the development of Cyber-Physical Systems (CPS) that seamlessly connect the physical factory floor with the digital realm. These systems monitor real-time data from the physical world and prepare feedback from the digital space, necessitating the harmonious integration of computation and communication, especially through wireless technology. Simultaneously, Machine Learning (ML) methods are advancing across various domains. The proliferation of wireless sensors and the Internet of Things, particularly within the CPS framework, generates substantial data. To address challenges such as latency, device resource limitations, and privacy concerns associated with centralized cloud processing, there is a shift towards edge computing, enabling distributed learning algorithms.

    This dissertation tackles these challenges with four innovative methods that combine wireless technology, control systems, and distributed ML in the context of Industry 4.0. These methods aim to harness the potential of this digital transformation, making Predictive Maintenance (PdM) in industries smarter and more efficient. The first method, parallel event-triggering, is designed for multi-agent systems in industrial environments. It utilizes distributed event-based state estimation to enhance control performance and reduce network resource consumption. The second and third methods are developed for collaborative PdM using wireless communication in a federated approach. The second method focuses on real-time anomaly detection while preserving asset privacy at the edge level, and the third method optimizes remaining useful life prediction from sequential data within a federated learning framework. Both federated approaches enhance efficiency, simplify communication, and improve local model convergence. The fourth method introduces an innovative approach to collaborative PdM, utilizing over-the-air computation at the edge level. This approach offers low latency and improved spectral efficiency. The optimization challenges at the edge level are addressed by using a modified gradient descent approach, which effectively handles noisy communication channels and improves the convergence of ML algorithms. All four methods proposed in this thesis underwent a comprehensive evaluation,and the experimental findings demonstrate their effectiveness in achieving their intended objectives.

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  • 24.
    Bemani, Ali
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Aggregation Strategy on Federated Machine Learning Algorithm for Collaborative Predictive Maintenance2022Inngår i: Sensors, E-ISSN 1424-8220, Vol. 22, nr 16, artikkel-id 6252Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Industry 4.0 lets the industry build compact, precise, and connected assets and also has made modern industrial assets a massive source of data that can be used in process optimization, defining product quality, and predictive maintenance (PM). Large amounts of data are collected from machines, processed, and analyzed by different machine learning (ML) algorithms to achieve effective PM. These machines, assumed as edge devices, transmit their data readings to the cloud for processing and modeling. Transmitting massive amounts of data between edge and cloud is costly, increases latency, and causes privacy concerns. To address this issue, efforts have been made to use edge computing in PM applications., reducing data transmission costs and increasing processing speed. Federated learning (FL) has been proposed a mechanism that provides the ability to create a model from distributed data in edge, fog, and cloud layers without violating privacy and offers new opportunities for a collaborative approach to PM applications. However, FL has challenges in confronting with asset management in the industry, especially in the PM applications, which need to be considered in order to be fully compatible with these applications. This study describes distributed ML for PM applications and proposes two federated algorithms: Federated support vector machine (FedSVM) with memory for anomaly detection and federated long-short term memory (FedLSTM) for remaining useful life (RUL) estimation that enables factories at the fog level to maximize their PM models’ accuracy without compromising their privacy. A global model at the cloud level has also been generated based on these algorithms. We have evaluated the approach using the Commercial Modular Aero-Propulsion System Simulation (CMAPSS) dataset to predict engines’ RUL Experimental results demonstrate the advantage of FedSVM and FedLSTM in terms of model accuracy, model convergence time, and network usage resources. 

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  • 25.
    Bemani, Ali
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Cyber-Physical Control of Indoor Multi-vehicle Testbed for Cooperative Driving2020Inngår i: 2020 IEEE Conference on Industrial Cyberphysical Systems (ICPS), IEEE , 2020, s. 371-377Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The system of connected vehicle to vehicle and vehicle to infrastructure can be considered as a wireless cyber-physical system of systems (Wireless CPSoS), which will be provided with the high ability of adaptive control on system of systems, cooperative scenarios to control of a Wireless CPSoSand adaptive wireless networked control system (WNCS). In this paper we present our multi-vehicle testbed based on the cyber-physical system that was designed for verification and validation of cooperative driving algorithm involving WNCStesting. Vehicles were developed as the physical prototype equipped with Raspberry-pi microprocessor and other sensing elements. This testbed consists of a fleet of 4 robot vehicles. An indoor positioning system (IPS) based on particle filter is purposed by using an inertial measurement unit (IMU) and iBeacon that is built upon Bluetooth Low Energy. Some typical cooperative driving scenarios can be implemented on this testbed under indoor laboratory. The method used to realize the objective statement was Model Predictive Control (MPC) with a state observer based on a Kalman Filter (KF). Because the wireless control systems can be severely affected by the imperfections of the wireless communication link. Our experimental testbed paves the way for testing and evaluating more intelligent cooperative driving scenario with the use new wireless technology and control system in the future.

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  • 26.
    Bemani, Ali
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Distributed Event Triggering Algorithm for Multi-Agent System over a Packet Dropping Network2021Inngår i: Sensors, E-ISSN 1424-8220, Vol. 21, nr 14, artikkel-id 4835Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The availability of wireless networked control systems (WNCSs) has increased the interest in controlling multi-agent systems. Multiple feedback loops are closed over a shared communication network in such systems. An event triggering algorithm can significantly reduce network usage compared to the time triggering algorithm in WNCSs, however, the control performance is insecure in an industrial environment with a high probability of the packet dropping. This paper presents the design of a distributed event triggering algorithm in the state feedback controller for multi-agent systems, whose dynamics are subjected to the external interaction of other agents and under a random single packet drop scenario. Distributed event-based state estimation methods were applied in this work for designing a new event triggering algorithm for multi-agent systems while retaining satisfactory control performance, even in a high probability of packet drop condition. Simulation results for a multi-agent application show the main benefits and suitability of the proposed event triggering algorithm for multi-agent feedback control in WNCSs with packet drop imperfection.

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  • 27.
    Bemani, Ali
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Distributed Event-Triggered Control of Vehicular Networked System with Bursty Packet Drops2021Inngår i: 2021 7th International Conference on Event-Based Control, Communication, and Signal Processing (EBCCSP), Krakow, Poland: IEEE , 2021, s. 1-7Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper investigates the distributed event-triggered control of leader-follower consensus problem with harsh environmental conditions such as a high probability of burst packet drops occurs in the communication channels between the vehicles. The main objective in the vehicular platoons is to ensure that all follower vehicles are traveling at the same speed as the leader while maintaining a desired inter-vehicular distance with considering the minimum communication resource usage. To achieve the object, a novel distributed event-triggered communication strategy based on the estimation and prediction of self-states and other agents’ states in each vehicle is proposed which includes two parallel algorithms. The first one is based on comparing the state estimation and prediction of the vehicle itself, and the second one is based on comparing the state estimation and prediction of other vehicles which have interaction in their process with the active vehicle. Collision avoidance, speed convergence, and limited communication resource usage of each vehicle are simultaneously considered in the design of the event-triggered mechanism in a harsh packet drops environment. Numerical simulations are presented to show that the proposed event triggering algorithm under three scenarios of burst packet drops can converge the consensus problem of vehicular platooning.

  • 28.
    Bemani, Ali
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Low-Latency Collaborative Predictive Maintenance: Over-the-Air Federated Learning in Noisy Industrial Environments2023Inngår i: Sensors, E-ISSN 1424-8220, Vol. 23, nr 18, artikkel-id 7840Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The emergence of Industry 4.0 has revolutionized the industrial sector, enabling the development of compact, precise, and interconnected assets. This transformation has not only generated vast amounts of data but also facilitated the migration of learning and optimization processes to edge devices. Consequently, modern industries can effectively leverage this paradigm through distributed learning to define product quality and implement predictive maintenance (PM) strategies. While computing speeds continue to advance rapidly, the latency in communication has emerged as a bottleneck for fast edge learning, particularly in time-sensitive applications such as PM. To address this issue, we explore Federated Learning (FL), a privacy-preserving framework. FL entails updating a global AI model on a parameter server (PS) through aggregation of locally trained models from edge devices. We propose an innovative approach: analog aggregation over-the-air of updates transmitted concurrently over wireless channels. This leverages the waveform-superposition property in multi-access channels, significantly reducing communication latency compared to conventional methods. However, it is vulnerable to performance degradation due to channel properties like noise and fading. In this study, we introduce a method to mitigate the impact of channel noise in FL over-the-air communication and computation (FLOACC). We integrate a novel tracking-based stochastic approximation scheme into a standard federated stochastic variance reduced gradient (FSVRG). This effectively averages out channel noise's influence, ensuring robust FLOACC performance without increasing transmission power gain. Numerical results confirm our approach's superior communication efficiency and scalability in various FL scenarios, especially when dealing with noisy channels. Simulation experiments also highlight significant enhancements in prediction accuracy and loss function reduction for analog aggregation in over-the-air FL scenarios.

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  • 29.
    Bergroth, Simon
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Implementering av MPPT-enhet med återkoppling: avsedd för solceller2019Independent thesis Basic level (university diploma), 180 hpOppgave
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  • 30.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Hosseinzadeh Dadash, Amirhossein
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Finite Horizon Degradation Control of Complex Interconnected Systems2021Inngår i: Proceedings of the 17th IFAC Symposium on Information Control Problems in Manufacturing Budapest, Hungary, June 7-9, 2021, Elsevier , 2021, s. 319-324Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In industrial production, it is of great importance to have high availability in its production equipment. Well-functioning maintenance is a significant factor for a high level of availability. This can be achieved by minimizing the number of reactive maintenance stops and optimizing scheduled maintenance. New methods for predictive maintenance provide a good opportunity for this, but most technologies that are available today are designed for individual sub-systems and they are rarely designed for a complex, interconnected machine. In the process industry, raw materials are rocessed into a finished product in a continuous flow through several subsystems and if one subsystem stops, the entire process flow stops. For these processes, it is more important to optimize the maintenance efforts for subsystems so maintenance can take place synchronized. This paper describes a method of supervised control that includes maintenance aspects; health parameters indicating deterioration are included in a MIMO controller. The method is verified in a simulation of a rolling mill with three rollers. The results show that it is possible to optimize the whole complex process including several subprocesses by using a health parameter as a control parameter and broadening the controllability of the system by dividing the workload in a way that all the subsystems reach the desired degradation level for maintenance in a desired optimum time. 

  • 31.
    Budak, Sinan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Systemmodellering av demonstrationsutrusning: Visualisering och simulering med avseende på Cyber-fysiska system2021Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    The digitalization trend is popular in the industrial world because of the efficiency of the monotonous working standards and conditions. Industry 4.0 is frequently brought up and discussed in the industries, more precisely, how the new genera- tion's working methods will be carried out in the industry. In the industrial sectors, there is a strong confidence that digitalization will gain a strong foothold in the near future.The University of Gävle (“University”) will develop the robot lab during the spring of 2020 with several different activities, including visiting, research and education. The reason for the project is that the laboratory has more than 400 visitors per year, an increased demand for flexible learning, automation robotics and digitalization are areas of rapid development and the volume of research in the subject is growing. The development work aims to visualize and simulate automation solutions in the laboratory. In addition, a hardware control system, ABB (AC 800), will be con- nected to the Human-Machine Interface ("HMI"). This project aims to create a pro- ject in a simulation environment and connect it to the physical environment, i.e., to connect it to PLC.To achieve the purpose of this project, examples and development trends in Cyber- physical Systems (“CPS”) regarding simulation and visualization of automation solu- tions will be discussed and an evaluation of system identification methods that can be used in system modeling of the demonstration equipment will be made.In this project, a system will be modelling so that product demonstration in the ro- bot laboratory at the University can be controlled remotely or via remote. To be able to demonstrate the entire chain from simulation environment to physical envi- ronment, it is necessary to program the PLC via the TIA portal. Programming lan- guage for the PLC should Ladder Diagram (“LD”) be used, which is the most com- mon and graphical PLC programming method. System identification and errors of the system should be checked by visualizing via Factory I/O or the University’s own software, where all equipment is implemented.Creating intelligent machines requires sensor units and actuators such as RFID, vi- sion units and robotic arms. All of these elements require further research as well as careful examination of the content of international standards and specifications. The hope is that researchers will continue to explore the extensive breadth and depth of this topic. Factory I /O has built-in robot arm processes that are pre-programmed and grouped into the software (which not only allows the use of robot arms, but also a machine center included in a robot arm is used). In this respect, there are exciting research opportunities that can contribute to the development.

    The result of this research is that the entire chain from simulation environment to physical environment was estimated in a good way with the help of Factory I /O and Tia portal so that the PLC works as a cyber-twin equipment. Using the demonstra- tion equipment system creates a uniform standard for control and monitoring of the system.Keywords: Industry 4.0, Cyber physical system, Programmable logical Controller, Smart Manufacturing, Digital twin, Virtual commissioning.

    Fulltekst (pdf)
    sinanbudak
  • 32.
    Carlsson, Oscar
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Fjärrstyrningav industriell robot: En jämförande studie av fjärrstyrningslösningar2023Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Fjärrstyrning av industrirobotar är en efterfrågan som ökar inom den svenska industrin. Detta är en efterfrågan dels för att följa mål 9 i Agenda 2030 att hålla personal borta från farlig arbetsmiljö. Studien kommer att genomföras på företaget IndustriAutomation (IA) i Sandviken och framöver vara ett underlag för arbetsuppdrag.Lösningar som togs upp i studien gäller både mjuk- och hårdvara med fokus på lösningar som fungerar med KUKA som robotleverantör. KUKA UK har tidigare tagit fram en joystick-lösning som har ett högt pris, den ligger som grund till tanken bakom studien där det bland annat undersöks om den ekonomiska kostnaden är hållbar kontra andra alternativ.Intervjuer med företag, en undersökning av marknaden och samtal med kunder genomförs för att ta fram de lösningar som används i studien. Fokus läggs på lösningar som innebär att roboten kan fjärrstyras i drift.Lösningarna som studien tar upp håller sig mycket lägre i pris än KUKAs joystick och dessutom erbjuds det flera olika lösningar som kan komma att passa olika kunder bättre. Styrdon med haptisk feedback till användare för ett billigare inköpspris återfinns bland alternativen. Kostnadsberäkningen är genomförd på inköpspris och tar inte hänsyn till de arbetstimmar som kan tillkomma för att leverera lösningen till kund, vilket innebär att det i slutändan kan vara mer lönsamt med KUKAs joystick. Den lösningen innefattar allting, installation och setup. I stort sett en plug-in lösning för en robotcell att komma åt fjärrstyrning.

    Fulltekst (pdf)
    fulltext
  • 33.
    Choudhary, Vipin
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Ottosson, Patrik
    Radarbolaget AB.
    Andersson, Daniel
    Radarbolaget AB.
    Ronnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    A Non-destructive Testing Method in Industrial Processes to Determine the Complex Refractive Index Using Ultra-Wide Band Radio2022Inngår i: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 22, nr 8, s. 7752-7762Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An ultra-wide band measurement method for determining the complex refractive index of large-volume objects is presented. The method is intended for industrial non-destructive testing. It uses a frequency-domain technique in which transmitted radio pulses are analyzed and the effects of near field and coupling on the determined refractive index are compensated. Measurements were performed in an industrial setup with electromagnetic sensors buried in the object. The results are presented for woodchips as an object. The refractive index was experimentally determined in the frequency range 0.5-3.0 GHz. Additionally, we designed and manufactured planar quasi-differential elliptical-antennas as electromagnetic sensors. The results from the industrial measurement setup were compared with the results of the laboratory setup, in which the sensors were placed outside the test box and near field and coupling effects could be neglected. The complex refractive index determined for the two setups was in good agreement, which corroborates the proposed method for compensating for coupling and near-field effects. The complex refractive index of woodchips changes with the moisture content. It is experimental verified using the industrial setup that the moisture content can be determined with a 2 percent error.

    Fulltekst (pdf)
    fulltext
  • 34.
    Choudhary, Vipin
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik. KTH.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    A Nondestructive Testing Method for the Determination of the Complex Refractive Index Using Ultra Wideband Radar in Industrial Applications2020Inngår i: Sensors, E-ISSN 1424-8220, Vol. 20, nr 11, artikkel-id 3161Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An ultra-wide band radar reflection measurement technique for industrial applications is introduced. A new method for determining the complex refractive index (or equivalently the relative permittivity) of objects with planar interfaces is presented. The object thickness can also be obtained experimentally. The method is a combination of time and frequency domain techniques. The objects can be finite in size and at a finite distance. The limits in size and distance for the method to be valid are experimentally investigated. The method is relatively insensitive to hardware impairments such as frequency dependence of antennas and analog front end. The method is designed for industrial in-line measurements on objects on conveyor belts. Results are presented for solid wood and wood chips; the complex refractive index is determined in the frequency range 0.5 to 2.0 GHz for the moisture content of 3.6–10% for solid wood and 30–50% for wood chips. Polarimetric measurements are used; wood and wood chips are anisotropic.

  • 35.
    Choudhary, Vipin
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik. KTH.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Jansson, Magnus
    KTH.
    A Singular Value Decomposition Based Approach for Classifying Concealed Objects in Short Range Polarimetric Radar Imaging2019Inngår i: 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring), 2019, s. 4109-4115, artikkel-id 9017334Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In current research one of the main challenges in short range synthetic aperture radar (SAR) is electrically small structures and objects, which tend to unclear reinforced or through the wall objects, object orientation angle, and obscure contribution to extract the position of concealed multiple small objects. In this paper, ultra-wide-band (UWB) polarimetric radar was used to study reinforced objects and for estimation of object angle at short range. Electrically small 1D periodic mesh, 2D periodic meshes and differently oriented small objects or meshes could not be distinguished in conventional SAR images. A radar system with transmit and receive antennae mounted on a two dimensional scanning grid was used. The aim is non-destructive testing of built structures, in concrete slab manufacturing and for use in the renovation process. UWB short range radar data and images corresponding to different polarization states were analysed by using singular value decomposition (SVD). To perform decomposition, the proposed approach applies SVD to image data matrices produced from the back projection algorithm (BPA) to classify the different objects and identify the object angle. Then, sets of singular-components of different polarization states are analysed to classify objects. Also, the BPA algorithm is performed to construct the object images from the polarimetric radar signals. The object reflection varied with the polarimetric state of the UWB radar, which contributes to different object signatures (i.e., object intensity) since the object signature depends on the orientation, the size, and the number of objects. Object orientation with respect to the radar system and object anisotropy could be determined from the ratio of the different polarimetric singular-components. This proposed complex data analysis method demonstrates the usefulness of the SVD using BPA in extracting more information about and for classifying an object.

  • 36.
    Choudhary, Vipin
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Tripathy, Malay Ranjan
    Amity University Noida, India.
    A printed lens in antenna’s aperture to improve the performance of UWB-radar system2023Inngår i: International Journal of Systems Assurance Engineering and Management, ISSN 0975-6809, E-ISSN 0976-4348, Vol. 14, s. 603-609Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a printed lens for radar applications. The structure of the presented lens consists of an array of modified micro-strip lines, which is positioned in the antenna’s aperture on the same planar substrate. Simulations show that the gain and directivity increase with the proposed lens in a wide band frequency band. The proposed design is insensitive to rotation of the antenna. This paper focuses on real industrial applications and problems. Further, we show that the lens can be used to improve the object detection ability of an ultrawide band radar system, which is used in industrial applications such as non-destructive monitoring of built-structures and for use in the renovation process. The signal to noise ratio is improved. Furthermore, we show how the microwave lens can also be used to reduce the clutter in applications where the complex refractive index of objects is determined. Further, different simulated results (for different cases) are compared, presented and concluded.

    Fulltekst (pdf)
    fulltext
  • 37.
    Choudhary, Vipin
    et al.
    KTH.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Tripathy, Malay Ranjan
    Amity University, India.
    Metamaterial-based-absorber to improve the performance of S and X band radar systems2020Inngår i: 2020 7th International Conference on Signal Processing and Integrated Networks (SPIN), IEEE , 2020, s. 126-129Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present a metamaterial-based dual band microwave-absorber for radar applications, the structure of which consists of an array of closed ring resonators on a low profile substrate. Simulations show high absorption (absorptance > 90%) at dual frequencies i.e. 3 GHz and 9 GHz. The proposed absorber is insensitive to polarization (i.e., absorptance taking into account both co- and cross-polarization of reflected waves). Further, we show how the microwave absorber can be used to improve the performance of a radar system for short range applications, when positioned between the transmit and receive antennas. The error in estimated target distance is reduced and clutter reduction is improved.

  • 38.
    Christensen, Simon
    et al.
    Aalborg University, Aalborg, Denmark.
    Bai, Shaoping
    Aalborg University, Aalborg, Denmark.
    Rafique, Sajid
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    O'Sullivan, Leonard
    University of Limrick, Limerick, Ireland.
    Power, Valerie
    University of Limrick, Limerick, Ireland.
    Virk, Gurvinder Singh
    Innovative Technology and Science Limited, Cambridge, United Kingdom.
    AXO-SUIT: A Modular Full-Body Exoskeleton for Physical Assistance2019Inngår i: Mechanism Design for Robotics: Proceedings of the 4th IFToMM Symposium on Mechanism Design for Robotics / [ed] Alessandro Gasparetto and Marco Ceccarelli, Cham: Springer Netherlands, 2019, Vol. 66, s. 443-450Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    This paper presents the design of a modular full-body assistive exoskeleton (FB-AXO) for older adults which was developed with funding under the AAL funded AXO-SUIT project. Processes used to formulate a prioritized set of functional and design requirements via close-end-user involvement are outlined and used in realizing the exoskeleton. Design of the resulting mechanics and electronics details for the lower and upper-body subsystems (LB-AXO and (UB-AXO)) are described. Innovative designs of shoulder and spine mechanisms are presented. TheFB-AXO system comprises 27 degrees of freedom, of which 17 are passive and 10 active. The exoskeleton assists full-body motions such as walking, standing, bending, as well as performing lifting and carrying tasks to assist older users performing tasks of daily living.

  • 39.
    Christensen, Simon
    et al.
    Aalborg University, Denmark.
    Rafique, Sajid
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Bai, Shaoping
    Aalborg University, Denmark.
    Design of a powered full-body exoskeleton for physical assistance of elderly people2021Inngår i: International Journal of Advanced Robotic Systems, ISSN 1729-8806, E-ISSN 1729-8814, Vol. 18, nr 6, s. 1-15Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The development of full-body exoskeletons has been limited due to design complexities, mechanical integration intricacies, and heavier weight, among others. Consequently, very few full-body powered exoskeletons were developed to address these challenges, in spite of increasing demand for physical assistance at full-body level. This article presents an overall design and development of a powered full-body exoskeleton called “FB-AXO.” Primarily, FB-AXO consists of two main subsystems, a lower-body and an upper-body subsystem connected together through waist and spine modules. FB-AXO is developed for the support of weaker ageing adults so that they can continue functioning their daily activities. At the onset of the project, a set of functional and design requirements has been formulated with an extensive end-user involvement and then used in realizing the FB-AXO. The final FB-AXO design comprises of 27 degrees of freedom, of which 10 are active and 17 are passive, having a total system weight of 25 kg. Overall, the article elaborates comprehensively the design, construction, and preliminary testing of FB-AXO. The work effectively addresses design challenges including kinematic compatibility and modularity with innovative solutions. The details of the mechanics, sensors, and electronics of the two subsystems along with specifics of human-exoskeleton interfaces and ranges of motion are also provided. The FB-AXO exoskeleton effectively demonstrated to assist full-body motions such as normal walking, standing, bending as well as executing lifting and carrying tasks to meet the daily living demands of older users.

    Fulltekst (pdf)
    fulltext
  • 40.
    Cordova, Italo
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik. Högskolan i Gävle.
    Optimering av systemspecifika PID-parametrar för processer designade på Cytiva2021Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Optimeringen av PID-parametrarna har varit en utmaning sedan uppfinningen avPID-regulatorer. Många olika optimeringsmetoder har tagits fram sedan 1940-talet,i detta arbete testades och jämfördes Ziegler-Nichols stegsvarmetoden, Lambdametoden och AMIGO-metoden.Målsättningen med detta examensarbete var att kunna utse vilken optimeringsmetodsom lämpade sig bäst för processinstrumenten som designats på avdelningen Custimized Bioprocess Solutions (CBS) på Cytiva. Optimeringsmetoden som utses kommer att föreslås som en som en del i en arbetsprocess att följa när ett system behöveroptimeras.Testerna genomfördes med hjälp av stegsvarsmetoden, där de förinställda PIDparametrarna på ett processinstrument användes som referens. Utifrån tre parametrarmodellen kunde nödvändiga data samlas in, sedan beräknades nya PID-parametrarmed de valda optimeringsmetodernas beräkningsregler. De nya PID-parametrarnaanvändes sedan för att generera nya stegsvar. Slutligen jämfördes de nya stegsvarenmot stegsvaret från de förinställda PID-parametrarna för att kunna utse den mestlämpade optimeringsmetoden.Detta arbete resulterade i slutsatsen att fler tester behöver utföras, men att beräkningsverktyget som användes under examensarbetet skall ingå som en del av den efterfrågade arbetsprocessen. 

    Fulltekst (pdf)
    fulltext
  • 41.
    Cronhjort, Mikael
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Matematik.
    Nobuoka, Jakob
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för industriell ekonomi, industridesign och maskinteknik, Industriell ekonomi.
    Ängskog, Per
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Haga, Andreas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Miljövetenskap.
    Mårtensson, Gunilla
    Efforts to improve attractiveness of lower level engineering education (concept)2022Inngår i: SEFI 2022 - 50th Annual Conference of the European Society for Engineering Education, Proceedings, 2022, s. 1104-1112Konferansepaper (Fagfellevurdert)
    Abstract [en]

    There are nine study programmes awarding the degree bachelor in engineering (högskoleingenjör) at the University of Gävle. Some of these have only a few applicants, even though the graduates are appreciated by a relatively large regional primary and secondary sector industry. A major revision of the programmes is planned. One objective is to increase the attractiveness of the programmes. In the revised programmes, students are proposed to study most courses together during the first year of study, even if they belong to different engineering specializations. This is intended to improve the study environment. Students in programmes with low numbers of applicants will become part of a richer and livelier student collective. However, the attractiveness could further be problematized by asking to whom higher education is attractive. A special focus will be on increasing the admission of students from groups in society that have been underrepresented in higher education. More specifically this may be linked to individual factors such as the educational level of parents, family income, immigrational background and geography. There may also be societal explanations in traditions of gendered professions. Engineering programmes, and especially some of the specializations at the university, are dominated by male students. This study focuses on how universities can take action to further increase the attractiveness of the engineering programmes, with a special regard to groups that are known to be underrepresented among the students.

  • 42.
    Estebring, Hannes
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Undersökning om applicerbarhet av Module Type Package för bioprocess-system designade på Cytiva2023Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    PLC-system har funnits ute i industrin sedan sent 1970-tal och appliceras på miljontals olika processer. Företag inom processindustrin står idag inför stora utmaningar då en instabil marknad ställer krav på en mer hållbar och flexibel infrastruktur. Krav på ökad produktion, bättre kvalité och lägre kostnader har fått fler företag att försöka gå över till modulära automationssystem.

    Syftet med detta examensarbete är att undersöka applicerbarheten av Module Type Package (MTP) på Cytivas UNICORN-styrsystem och därefter ta fram en arbetsmetod samt eventuell mjukvara som gör detta möjligt.

    Arbetet valdes att utföras på Cytivas nya automationsplattform för UNICORN™-styrsystemet genom praktisk undersökning av instrumentkonfigurationer på en specifik grupp av deras bioprocesssystem. Med specifikationer och datablad som blev tillförsedda från de tekniska organen NAMUR och VDI/VDE som utvecklar MTP undersöktes en instrumentkonfiguration med fokus på struktur och uppbyggnad. Utifrån dessa undersökningar designades och utvecklades en mjukvara som kunde ta fram MTP-kompatibla data för validering och test med mjukvaruverktyg utvecklade av COPADATA.

    Arbetet resulterade i slutsatsen att MTP är möjligt att applicera på Cytivas bioprocesssystem med ny automationsplattform. Fortsatt arbete krävs för att ta fram en arbetsmetod samt att mjukvara i framtiden bör utvecklas vidare.

    Fulltekst (pdf)
    fulltext
  • 43.
    Hassan, Muhammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Production 4.0 of Ring Mill 4 Ovako AB2020Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Cyber-Physical System (CPS) or Digital-Twin approach are becoming popular in industry 4.0 revolution. CPS not only allow to view the online status of equipment, but also allow to predict the health of tool. Based on the real time sensor data, it aims to detect anomalies in the industrial operation and prefigure future failure, which lead it towards smart maintenance. CPS can contribute to sustainable environment as well as sustainable production, due to its real-time analysis on production.

    In this thesis, we analyzed the behavior of a tool of Ringvalsverk 4, at Ovako with its twin model (known as Digital-Twin) over a series of data. Initially, the data contained unwanted signals which is then cleaned in the data processing phase, and only before production signal is used to identify the tool’s model. Matlab’s system identification toolbox is used for identifying the system model, the identified model is also validated and analyzed in term of stability, which is then used in CPS. The Digital-Twin model is then used and its output being analyzed together with tool’s output to detect when its start deviate from normal behavior.

    Fulltekst (pdf)
    fulltext
  • 44.
    Hassan, Muhammad
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Svadling, Marcus
    Ovako AB.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Experience from implementing digital twins for maintenance in industrial processes2024Inngår i: Journal of Intelligent Manufacturing, ISSN 0956-5515, E-ISSN 1572-8145, Vol. 35, s. 875-884Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The capability of estimating future maintenance needs in advance and in a timely manner is a prerequisite for reliable manufacturing with high availability in a production unit. Additionally, conducting planned maintenance efforts regularly and prematurely increases the service lifetimes and utilization rates of parts, which leads to more sustainable production. The benefits of predictive maintenance are obvious, but introducing it into a facility poses various challenges. In this study, digital twins of well-functioning machines are used for predictive maintenance. The discrepancies between each physical unit and its digital twin are used to detect the maintenance needs. A thorough evaluation of the method over a period of 18 months by comparing digital twin detection results with maintenance and control system logs shows promising results. The method is successful in detecting discrepancies, and the paper describes the techniques that are used. However, not all discrepancies are related to the maintenance needs, and the evaluation identifies and discusses the most common sources of error. These are often the results of human interaction, such as parameter changes, maintenance activities and component replacement. 

    Fulltekst (pdf)
    fulltext
  • 45.
    Hernández, Esmeralda
    et al.
    IGIC Institute, Campus Gandia, Universitat Politècnica de València, 46730 Gandia, Spain.
    Pelegrí-Sebastiá, José
    IGIC Institute, Campus Gandia, Universitat Politècnica de València, 46730 Gandia, Spain.
    Sogorb, Tomás
    IGIC Institute, Campus Gandia, Universitat Politècnica de València, 46730 Gandia, Spain.
    Chilo, José
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Evaluation of Red Wine Acidification Using an E-Nose System with Venturi Tool Sampling2023Inngår i: Sensors, E-ISSN 1424-8220, Vol. 23, nr 6, artikkel-id 2878Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The quality of wine is checked both during the production process and upon consumption. Therefore, manual wine-tasting work is still valuable. Due to the nature of wine, many volatile components are released, and it is therefore difficult to determine which elements need to be controlled. Acetic acid is one of the substances found in wine and is a crucial substance for wine quality. Gas sensor systems may be a potential alternative for manual wine tasting. In this work, we have developed a TGS2620 gas sensor module to analyze acetic acid levels in red wine. The gas sensor module was refined according to the Venturi effect along with signal slope analysis, providing promising results. The example included in this paper demonstrates that there is a direct relationship between the slope of the MOS gas sensor response and the acetic acid concentration. This relationship is useful to evaluate the ethanol oxidation in acetic acid in red wine during its production process.

    Fulltekst (pdf)
    fulltext
  • 46.
    Horastani, Zahra Karami
    et al.
    Islamic Azad University, Shiraz, Iran.
    Horestani, Fatemeh Karami
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Hajiani, Saber Jamali
    Islamic Azad University, Shiraz, Iran.
    Safaiee, Rosa
    Shiraz University, Iran.
    Hashemifar, S. Javad
    Isfahan University of Technology, Iran.
    First-Principle Investigation of CH4 Adsorption on a Singly and Doubly Decorated (8,0) Single Wall Carbon Nanotube with Palladium/Oxygen Species2021Inngår i: IEEE Access, E-ISSN 2169-3536, Vol. 9, s. 122951-122958Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We employ dispersion-corrected density functional theory to study adsorption of CH4 molecule on a singly and doubly decorated (8,0) single wall carbon nanotube (CNT80) with palladium atom and oxygen molecule. The obtained optimized energies indicate that double decoration with palladium atom and oxygen molecules significantly enhance adsorption of methane on the CNT80, while single decoration with oxygen molecules give rise to a weak physical bonding for methane molecule. Moreover, we observe that methane adsorption decreases the bandgap and the distance of the Fermi level to the top of the valance band of the doubly decorated CNT80. The calculated charge density plots and energy band diagrams demonstrate a charge transfer from doubly decorated CNT80 to CH4. Regarding the p-type nature of the structure, our results support increment of the conductance of the doubly decorated CNT80 after methane adsorption, in agreement with a real measurement in the ambient conditions. This observation underlines the importance of the ambient oxygen in the real performance of CNT based gas sensors.

    Fulltekst (pdf)
    fulltext
  • 47.
    Horestani, Fatemeh Karami
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Horastani, Zahra Karami
    Department of Electrical Engineering, Shiraz Branch, Islamic Azad University, Shiraz 74731-71987, Iran.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    A Band-Pass Instrumentation Amplifier Based on a Differential Voltage Current Conveyor for Biomedical Signal Recording Applications2022Inngår i: Electronics, E-ISSN 2079-9292, Vol. 11, nr 7, artikkel-id 1087Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recently, due to their abundant benefits, current-mode instrumentation amplifiers have received considerable attention in medical instrumentation and read-out circuit for biosensors. This paper is focused on the design of current-mode instrumentation amplifiers for portable, implantable, and wearable electrocardiography and electroencephalography applications. To this end, a CMOS differential voltage second-generation current conveyor (DVCCII) based on a linear transconductor is presented. A new band-pass instrumentation amplifier, based on the designed DVCCII, is also implemented in this paper. The concept of the proposed differential voltage current conveyor and instrumentation amplifier is validated numerically and their predicted performance is presented. The simulation results of the presented circuits were tested for 0.18 µm TSMC CMOS technology in a post layout simulation level using the Cadence Virtuoso tool with a ±0.9 V power supply, and demonstrated that the designed DVCCII has a wide dynamic range of ±400 mV and ±0.85 mA and a power consumption of 148 µW. The layout of the DVCCII circuit occupies a total area of 0.378 µm2 . It is shown that the designed DVCCII benefits from good linearity over a wide range of input signals and provides a low input impedance at terminal X. Two versions of the proposed band-pass instrumentation amplifier using pseudo resistances were designed with different specifications for two different applications, namely for EEG and ECG signals. Numerical analyses of both designs show proper outputs and frequency responses by eliminating the undesired artifact and DC component of the EEG and ECG input signals.

    Fulltekst (pdf)
    fulltext
  • 48.
    Horestani, Fatemeh Karami
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Rosa, Jose M. de la
    Institute of Microelectronics of Seville, IMSECNM (CSIC/University of Seville), Sevilla, Spain.
    Ultra-High-Resistance Pseudo-Resistors with Small Variations in a Wide Symmetrical Input Voltage Swing2023Inngår i: IEEE Transactions on Circuits and Systems - II - Express Briefs, ISSN 1549-7747, E-ISSN 1558-3791, Vol. 70, nr 8, s. 2794-2798Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a new strategy and circuit configuration composed of serially-connected PMOS devices operating in the subthreshold region for implementing ultra-highvalue resistors required in very low-frequency active-RC filters and bio-amplifiers. Depending on the application, signal bandwidth for instance in bio-amplifiers may vary from a few mHz up to a maximum of 10 kHz. Three different resistor structures are proposed to achieve ultra-high resistance. While ranging in the order of several TY, the proposed ultra-high-resistance pseudoresistors occupy a small on-chip silicon area, which is one of the main issues in the design of analog front-end circuits in ultra-low power implantable biomedical microsystems. In addition, these ultra-high-value resistors lead to the use of a small capacitance to create a very small cut-off frequency. Therefore, the large area to implement capacitances is also considerably reduced. The proposed resistor structures have very small variations about 7% and 12% in a wide input voltage range (-0.5 V +0.5 V), thus significantly improving the total harmonic distortion of bioamplifiers and the analog front-end of the system. Simulation results of different circuits designed in a 180nm CMOS technology, are shown to demonstrate the advantages of the proposed ultra-high-resistance pseudo-resistors.

  • 49.
    Hosseinzadeh Dadash, Amirhossein
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Adaptive Finite Horizon Degradation-Aware Regulator2023Inngår i: Recent Developments in Model-Based and Data-Driven Methods for Advanced Control and Diagnosis / [ed] Janusz Kacprzyk, Springer , 2023, s. 123-132Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Predicting the failure and estimating the machine’s state of health is information that supports the production planning and maintenance management systems to increase productivity and reduce maintenance and downtime costs. However, controlling the degradation in the machines will improve the system’s reliability and resilience and make high-level decisions more accurate and reliable. To control the degradation in the machines, time should be included in the cost function as a variable, which alters the markovian properties of the system dynamic. In this article, we include the degradation cost in the quadratic cost function of the infinite horizon controller and calculate the optimal feedback according to the dynamics of the degradation using dynamic programming. It will be shown that the infinite horizon control will convert to the finite horizon, and the controller will be able to control the degradation according to the desired degradation at the desired time. In the end, with the help of simulation, we show that the degradation controller can control the degradation in the MIMO systems.

  • 50.
    Hosseinzadeh Dadash, Amirhossein
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Adaptive Finite Horizon Degradation-Aware Regulator2023Inngår i: 16th European Workshop on Advanced Control and Diagnosis (ACD 2022), Nancy, France, November 16-18, 2022 / [ed] Prof. Didier Theilliol, 2023Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Predicting the failure and estimating the machine's state of health is information that supports the production planning and maintenance management systems to increase productivity and reduce maintenance and downtime costs. However, controlling the degradation in the machines will improve the system's reliability and resilience and make high-level decisions more accurate and reliable. To control the degradation in the machines, time should be included in the cost function as a variable, which alters the markovian properties of the system dynamic. In this article, we include the degradation cost in the quadratic cost function of the infinite horizon controller and calculate the optimal feedback according to the dynamics of the degradation using dynamic programming. It will be shown that the infinite horizon control will convert to the finite horizon, and the controller will be able to control the degradation according to the desired degradation at the desired time. In the end, with the help of simulation, we show that the degradation controller can control the degradation in the MIMO systems.

    Fulltekst (pdf)
    Degradation Feedback
123 1 - 50 of 137
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