Davood Khodadad

Dr. Davood Khodadad

Umeå University, Umeå, Västerbotten, Sweden
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Research Focus & Metrics

Academic Career Length

11Years (2016-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 September 2018 in Physiological Measurement
Verified
Journal Article
Open access
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Davood KhodadadDavood Khodadad
Davood Khodadad
SNSven Nordebo
Sven Nordebo
BMB Müller
B Müller
AWA Waldmann
A Waldmann
RYR Yerworth
R Yerworth
RBR Bayford
R Bayford
Objective : This paper defines a method for optimizing the breath delineation algorithms used in electrical impedance tomography (EIT). In lung EIT the identification of the breath phases is central for generating tidal impedance variation images, subsequent data analysis and clinical evaluation. The optimisation of these algorithms is particularly important in neonatal care since the existing breath detectors developed for adults may give insufficient reliability in neonates due to their very irregular breathing pattern. Approach : Our approach is generic in the sense that it relies on the definition of a gold standard and the associated definition of detector sensitivity and specificity, an optimisation criterion and a set of detector parameters to be investigated. The gold standard has been defined by 11 clinicians with previous experience with EIT and the performance of our approach is described and validated using a neonatal EIT dataset acquired within the EU-funded CRADL project. Main results : Three different algorithms are proposed that improve the breath detector performance by adding conditions on (1) maximum tidal breath rate obtained from zero-crossings of the EIT breathing signal, (2) minimum tidal impedance amplitude and (3) minimum tidal breath rate obtained from time-frequency analysis. As a baseline a zero-crossing algorithm has been used with some default parameters based on the Swisstom EIT device. Significance : Based on the gold standard, the most crucial parameters of the proposed algorithms are optimised by using a simple exhaustive search and a weighted metric defined in connection with the receiver operating characterics. This provides a practical way to achieve any desirable trade-off between the sensitivity and the specificity of the detectors.

7 July 2023 in Mathematics
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Mahmoud MoradiMahmoud Moradi
Mahmoud Moradi
MKMojtaba Karamimoghadam
Mojtaba Karamimoghadam
MMMohammad Saleh Meiabadi
Mohammad Saleh Meiabadi
Giuseppe CasalinoGiuseppe Casalino
Giuseppe Casalino
MGMohammad Ghaleeh
Mohammad Ghaleeh
Davood KhodadadDavood Khodadad
Davood Khodadad
This paper explores the 3D printing of poly vinyl alcohol (PVA) using the fused deposition modeling (FDM) process by conducting statistical modeling and optimization. This study focuses on varying the infill percentage (10–50%) and patterns (Cubic, Gyroid, tri-hexagon and triangle, Grid) as input parameters for the response surface methodology (DOE) while measuring modulus, elongation at break, and weight as experimental responses. To determine the optimal parameters, a regression equation analysis was conducted to identify the most significant parameters. The results indicate that both input parameters significantly impact the output responses. The Design Expert software was utilized to create surface and residual plots, and the interaction between the two input parameters shows that increasing the infill percentage (IP) leads to printing heavier samples, while the patterns do not affect the weight of the parts due to close printing structures. On the contrary, the discrepancy between the predicted and actual responses for the optimal samples is below 15%. This level of error is deemed acceptable for the DOE experiments.

14 December 2023 in International Journal of Engineering Pedagogy (iJEP)
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Davood KhodadadDavood Khodadad
Davood Khodadad
Engineering education requires a strong emphasis on problem-solving, critical thinking, and practical application of knowledge. To achieve the highest quality of teaching, educators must create a trusting environment that allows students to feel comfortable asking questions and performing to the best of their abilities. This paper outlines the teaching philosophy and practices of an engineering lecturer who has adapted his pedagogical approach across several universities in Sweden and abroad. The author emphasizes the importance of being flexible and responsive to student needs, offering early and constructive feedback, and providing students a safe and supportive learning environment with opportunities to develop programming skills. The paper also includes comments from students that reflect the author’s effectiveness as an educator in creating a supportive and challenging learning environment for engineering students.

20 September 2016 in Applied Optics
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Closed access
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Davood KhodadadDavood Khodadad
Davood Khodadad
ASAlok Kumar Singh
Alok Kumar Singh
GPGiancarlo Pedrini
Giancarlo Pedrini
MSMikael Sjödahl
Mikael Sjödahl
The objective of this paper is to describe a full-field deformation measurement method based on 3D speckle displacements. The deformation is evaluated from the slope of the speckle displacement function that connects the different reconstruction planes. For our experiment, a symmetrical arrangement with four illuminations parallel to the planes (x,z) and (y,z) was used. Four sets of speckle patterns were sequentially recorded by illuminating an object from the four directions, respectively. A single camera is used to record the holograms before and after deformations. Digital speckle photography is then used to calculate relative speckle displacements in each direction between two numerically propagated planes. The 3D speckle displacements vector is calculated as a combination of the speckle displacements from the holograms recorded in each illumination direction. Using the speckle displacements, problems associated with rigid body movements and phase wrapping are avoided. In our experiment, the procedure is shown to give the theoretical accuracy of 0.17 pixels yielding the accuracy of 2×10−3 in the measurement of deformation gradients.

13 April 2021 in International Journal of Automation and Computing
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Satyam PaulSatyam Paul
Satyam Paul
AAAjay Arunachalam
Ajay Arunachalam
Davood KhodadadDavood Khodadad
Davood Khodadad
HAHenrik Andreasson
Henrik Andreasson
Olena RubanenkoOlena Rubanenko
Olena Rubanenko
The implementation of image-based phenotyping systems has become an important aspect of crop and plant science research which has shown tremendous growth over the years. Accurate determination of features using images requires stable imaging and very precise processing. By installing a camera on a mechanical arm driven by motor, the maintenance of accuracy and stability becomes non-trivial. As per the state-of-the-art, the issue of external camera shake incurred due to vibration is a great concern in capturing accurate images, which may be induced by the driving motor of the manipulator. So, there is a requirement for a stable active controller for sufficient vibration attenuation of the manipulator. However, there are very few reports in agricultural practices which use control algorithms. Although, many control strategies have been utilized to control the vibration in manipulators associated to various applications, no control strategy with validated stability has been provided to control the vibration in such envisioned agricultural manipulator with simple low-cost hardware devices with the compensation of non-linearities. So, in this work, the combination of proportional-integral-differential (PID) control with type-2 fuzzy logic (T2-F-PID) is implemented for vibration control. The validation of the controller stability using Lyapunov analysis is established. A torsional actuator (TA) is applied for mitigating torsional vibration, which is a new contribution in the area of agricultural manipulators. Also, to prove the effectiveness of the controller, the vibration attenuation results with T2-F-PID is compared with conventional PD/PID controllers, and a type-1 fuzzy PID (T1-F-PID) controller.

24 July 2023 in Energies
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Younes MohammadiYounes Mohammadi
Younes Mohammadi
Aleksey PaltsevAleksey Paltsev
Aleksey Paltsev
Boštjan PolajžerBoštjan Polajžer
Boštjan Polajžer
Seyed Mahdi MiraftabzadehSeyed Mahdi Miraftabzadeh
Seyed Mahdi Miraftabzadeh
Davood KhodadadDavood Khodadad
Davood Khodadad
This paper presents a comprehensive study of winter temperatures in Norway and northern Sweden, covering a period of 50 to 70 years. The analysis utilizes Singular Spectrum Analysis (SSA) to investigate temperature trends at six selected locations. The results demonstrate an overall long-term rise in temperatures, which can be attributed to global warming. However, when investigating variations in highest, lowest, and average temperatures for December, January, and February, 50% of the cases exhibit a significant decrease in recent years, indicating colder winters, especially in December. The study also explores the variations in Atlantic Meridional Overturning Circulation (AMOC) variations as a crucial climate factor over the last 15 years, estimating a possible 20% decrease/slowdown within the first half of the 21st century. Subsequently, the study investigates potential similarities between winter AMOC and winter temperatures in the mid to high latitudes over the chosen locations. Additionally, the study examines another important climatic index, the North Atlantic Oscillation (NAO), and explores possible similarities between the winter NAO index and winter temperatures. The findings reveal a moderate observed lagged correlation for AMOC-smoothed temperatures, particularly in December, along the coastal areas of Norway. Conversely, a stronger lagged correlation is observed between the winter NAO index and temperatures in northwest Sweden and coastal areas of Norway. Thus, NAO may influence both AMOC and winter temperatures (NAO drives both AMOC and temperatures). Furthermore, the paper investigates the impact of colder winters, whether caused by AMOC, NAO, or other factors like winds or sea ice changes, on electrical power and energy systems, highlighting potential challenges such as reduced electricity generation, increased electricity consumption, and the vulnerability of power grids to winter storms. The study concludes by emphasizing the importance of enhancing the knowledge of electrical engineering researchers regarding important climate indices, AMOC and NAO, the possible associations between them and winter temperatures, and addressing the challenges posed by the likelihood of colder winters in power systems.