Viser treff 546-565 av 916

    • Non-directional Overcurrent Protection Relay Testing Using Virtual Hardware-in-the-Loop Device 

      Pham, Le Nam Hai; Wagle, Raju; Gonzalez-Longatt, Francisco; Acosta Montalvo, Martha Nohemi (Chapter; Bokkapittel, 2023-05-17)
      Protective relays are an integral part of the power grid, making it reliable and secure against abnormal conditions. Hardware-in-the-Loop (HIL) can be employed to test and validate digital protective relay devices in the real-time simulation comprising hardware and software before actual implementation. However, the HIL technique requires a complex and high-cost technical environment consisting of ...
    • Non-parametric Linear Technique for Measuring the Efficiency of Winter Road Maintenance in the Arctic Area 

      Hatamzad, Mahshid; Polanco Pinerez, Geanette (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-05)
      Improving the performance of Winter Road Maintenance (WRM) can increase the traffic safety and reduce the cost as well as environmental impacts. This study evaluates the efficiency of WRM technique, named salting, in the Arctic area by using Data Envelopment Analysis (DEA), which is a non-parametric linear method to measure the efficiencies of decision-making units (DMUs) based on handling multiple ...
    • Norwegian freshmen engineering students' self-efficacy, motivation, and view of mathematics in light of task performance 

      Rensaa, Ragnhild Johanne; Tossavainen, Timo (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-15)
      We report on 71 Norwegian freshmen engineering students' self-efficacy and motivation in mathematics. Students' responses to five-point Likert scales were analysed across three groups corresponding to different performance levels on a set of mathematical tasks. The groups were investigated to trace differences in self-efficacy, motivation, and the epistemological beliefs about the nature of mathematics. ...
    • Norwegian, Swedish, and Finnish first-year engineering students' motivational values and beliefs about the nature of mathematics 

      Tossavainen, Timo; Rensaa, Ragnhild Johanne; Haukkanen, Pentti (Chapter; Bokkapittel, 2022)
      We report from a Nordic research project that has investigated first-year engineering students in Norway, Sweden, and Finland, and the relationships between their task performance, motivational values, and beliefs about the nature of mathematics. The present paper focuses on the covariance between their motivational values and beliefs from the perspectives of gender and nationality. The results ...
    • A note about frequencies being close or amplitudes being small in frequency analysis 

      Rensaa, Ragnhild Johanne (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-10-10)
      In an earlier paper, an alternative method for how to solve the frequency analysis problem was offered. The object of the present paper is to bring about how to handle situations where the frequencies are close to each other or there is an amplitude that is really small.
    • A note on contributions concerning nonseparable spaces with respect to signal processing within Bayesian frameworks 

      Samko, Natasha Gabatsuyevna; Singh, Harpal (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-07-17)
      In this paper, we discuss the study of some signal processing problems within Bayesian frameworks and semigroups theory, in the case where the Banach space under consideration may be nonseparable. For applications, the suggested approach may be of interest in situations where approximation in the norm of the space is not possible. We describe the idea for the case of the abstract Cauchy problem ...
    • A note on the best constants in some hardy inequalities 

      Persson, Lars Erik; Samko, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2015)
      Abstract. The sharp constants in Hardy type inequalities are known only in a few cases. In this paper we discuss some situations when such sharp constants are known, but also some new sharp constants are derived both in one-dimensional and multi-dimensional cases.
    • A note on the maximal operators of Vilenkin-Nörlund means with non-increasing coefficients 

      Memić, Nacima; Persson, Lars Erik; Tephnadze, George; Kroo, A (Peer reviewed; Journal article; Tidsskriftsartikkel, 2016)
      In [14] we investigated some Vilenkin—Nörlund means with non-increasing coefficients. In particular, it was proved that under some special conditions the maximal operators of such summabily methods are bounded from the Hardy space H1/(1+α) to the space weak-L1/(1+α), (0 < α ≦ 1). In this paper we construct a martingale in the space H1/(1+α), which satisfies the conditions considered in [14], and so ...
    • A Novel Technique to Mitigate the Overlap-Time Effect in Current Source Inverters 

      Sohail, Umer; Østrem, Trond; Hoff, Bjarte (Chapter; Bokkapittel, 2023-08-31)
      Generally, the current source inverter is considered more reliable than the voltage source inverter due to the presence of inductor as an energy storage element on the DC link, but a disruption in the inductor current could significantly risk its reliability. To guarantee the reliable operation of current source inverter, an overlap time must be added to the gate signals of its switches. This ensures ...
    • Numerical conservative solutions of the Hunter–-Saxton equation 

      Grunert, Katrin; Nordli, Anders Samuelsen; Solem, Susanne (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-21)
      In the article a convergent numerical method for conservative solutions of the Hunter–Saxton equation is derived. The method is based on piecewise linear projections, followed by evolution along characteristics where the time step is chosen in order to prevent wave breaking. Convergence is obtained when the time step is proportional to the square root of the spatial step size, which is a milder ...
    • Numerical investigation of vibration and dynamic pressure of a vertical axis wind turbine 

      Erchiqui, Fouad; Souli, M; Moatamedi, Mojtaba; Albahkali, E (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-12-31)
      In the environmental field, the problems of vibration reduction have become a major preoccupation, particularly on the noise generated by the acoustic radiation pressure produced by wind turbines. This paper is aimed at presenting the investigation on the application of FEM element method for study the acoustic radiation pressure produced by vertical-axis wind turbine. For this initiative, we ...
    • Numerical sensitivity analysis of temperature-dependent reaction rate constants for optimized thermal conversion of high-density plastic waste into combustible fuels 

      Irfan, Muhammad; Un Nabi, Rao Adeel; Hussain, Hammad; Naz, Yasin; Shukrullah, Shazia; Khawaja, Hassan; Rahman, Saifur; Althobiani, Faisal (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-22)
      The use of experimental rate constants for producing a high yield of liquid fuels from the pyrolysis of plastic waste is not widely accepted owing to a lack of compatibility between the different kinetic rate constants responsible for successful conversion reactions. In R software, the Arrhenius law can forecast the ideal combination of reaction rate constants and frequency factors and then perform ...
    • Numerical Simulation of Non-normal Wind Load on Porous Fences 

      Xu, Yizhong; Mustafa, Mohamad; Calay, Rajnish K; Sørensen, Bjørn Reidar (Journal article; Peer reviewed; Tidsskriftartikkel, 2017)
      This paper presents a numerical simulation of non-normal wind loads on a porous fence. It was found that non-normal wind load has significant impact on the performance of the fence in terms. The performance of the fence was measured as the effective fence zone behind the fence where flow characteristics and normal drag coefficients were maintained within safe level. It is recommended the incidental ...
    • Numerical simulation of the dynamic response in pulse-loaded fibre–metal-laminated plates 

      Nwankwo, Ebuka; Fallah, Arash Soleiman; Moatamedi, Mojtaba; Louca, Luke A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-07-27)
      This article presents a three-dimensional constitutive model to replicate the dynamic response of blast-loaded fibre–metal laminates made of 2024-0 aluminium alloy and woven composite (glass fibre–reinforced polypropylene). Simulation of the dynamic response is challenging when extreme localised loads are of concern and requires reliable material constitutive models as well as accurate modelling ...
    • Numerical study of atmospheric ice accretion on rotating geometric cross sections with fins 

      Mughal, Umair Najeeb; Virk, Muhammad Shakeel (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-12)
      This paper describes the numerical study of atmospheric ice accretion on rotating geometric cross sections, circular, hexagon and square , all having fins, to select an optimum geometric cross section for use as a rotating part of a newly- proposed designed icing sensor. Computational fluid dynamics-based numerical analyses were carried out in this research work to understand and analyse the ...
    • Numerical Study of Atmospheric Ice Accretion on Various Geometric Cross-sections 

      Virk, Muhammad Shakeel (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
    • Numerical Study of Atmospheric Icing on Non Rotating Circular Cylinders in Tandem Arrangement 

      Virk, Muhammad Shakeel (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-03-01)
      Numerical study of atmospheric ice accretion on two non-rotating circular cylinders in tandem arrangement was carried out at different operating and geometric conditions. To validate the numerical model, initially the results of ice accretion on single circular cylinder were compared with the experimental data obtained from CIGELE atmospheric icing research wind tunnel (CAIRWT) [1, 2]. A good agreement ...
    • Numerical study of icing impact on the performance of pitch-regulated large wind turbine 

      Kangash, Aleksei; Virk, Muhammad Shakeel; Maryandyshev, Pavel (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-10-17)
      This paper presents a study of the impact of icing on the performance of a pitch-regulated large wind turbine. Numerical simulations of six blade sections of the NREL 5 MW wind turbine at various free stream velocities are performed. Blade Element Momentum (BEM) method along Computational Fluid Dynamics (CFD) bases multiphase numerical simulations are used for this study. Analysis shows that the ...
    • Numerical study on the ventilation performance of a livestock house built in porous panels in Cold Regions 

      Mustafa, Mohamad; Xu, Yizhong; Calay, Rajnish K; Sørensen, Bjørn Reidar (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11)
      This paper presents a numerical prediction on the assessment of natural ventilation on a livestock house built in porous panels, aided by Computational Fluid Dynamics techniques. A typical climatic environment in Cold Regions was taken into consideration. The ventilation performances have been assessed by the distribution of indoor air velocity, turbulence intensity and local mean age of air through ...
    • Numerical study on the ventilation performance of a livestock house built in porous panels in Cold Regions 

      Xu, Yizhong; Mustafa, Mohamad; Calay, Rajnish K; Sørensen, Bjørn Reidar (Journal article; Tidsskriftartikkel; Peer reviewed, 2019)
      This paper presents a numerical prediction on the assessment of natural ventilation on a livestock house built in porous panels, aided by Computational Fluid Dynamics techniques. A typical climatic environment in Cold Regions was taken into consideration. The ventilation performances have been assessed by the distribution of indoor air velocity, turbulence intensity and local mean age of air through ...