Shahram Dehdashti

Dr. Shahram Dehdashti

orcid

Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

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

Representative Publications

View All Publications
5 December 2022 in Cognitive Psychology
Verified
Journal Article
Closed access
PBPeter Bruza
Peter Bruza
LFLauren Fell
Lauren Fell
PHPamela Hoyte
Pamela Hoyte
SDShahram Dehdashti
Shahram Dehdashti
AOA. Obeid
A. Obeid
Catarina MoreiraCatarina Moreira
Catarina Moreira

9 August 2022 in Journal of Physics A: Mathematical and Theoretical
Verified
Journal Article
Closed access
Prayag TiwariPrayag Tiwari
Prayag Tiwari
SDShahram Dehdashti
Shahram Dehdashti
AOAbdul Karim Obeid
Abdul Karim Obeid
PMPekka Marttinen
Pekka Marttinen
PBPeter Bruza
Peter Bruza
In this paper, by mapping datasets to a set of non-linear coherent states, the process of encoding inputs in quantum states as a non-linear feature map is re-interpreted. As a result of the fact that the radial basis function is recovered when data is mapped to a complex Hilbert state represented by coherent states, non-linear coherent states can be considered as a natural generalisation of the associated kernels. In this paper, as an example of kernels based on non-linear coherent states, we propose kernel functions based on generalized hypergeometric functions, as orthogonal polynomial functions. The suggested kernel is implemented with the support vector machine (SVM) on two well known datasets (make_circles, and make_moons) and outperforms the baselines, even when the level of noise is high. In addition, we study the impact of the geometrical properties of the feature space, obtained by the non-linear coherent states, on the SVM classification task, by considering the Fubini–Study metric of the associated coherent states.

16 September 2020 in Neural Computing and Applications
Verified
Journal Article
Closed access
PDF file
Prayag TiwariPrayag Tiwari
Prayag Tiwari
SUSagar Uprety
Sagar Uprety
SDShahram Dehdashti
Shahram Dehdashti
MHMohammad Anwar Hossain
Mohammad Anwar Hossain

11 March 2020 in Behavioral and Brain Sciences
Verified
Journal Article
Closed access
PDF file
Catarina MoreiraCatarina Moreira
Catarina Moreira
LFLauren Fell
Lauren Fell
SDShahram Dehdashti
Shahram Dehdashti
PBPeter Bruza
Peter Bruza
Andreas WichertAndreas Wichert
Andreas Wichert
We propose an alternative and unifying framework for decision-making that, by using quantum mechanics, provides more generalised cognitive and decision models with the ability to represent more information compared to classical models. This framework can accommodate and predict several cognitive biases reported in Lieder & Griffiths without heavy reliance on heuristics or on assumptions of the computational resources of the mind.

22 July 2021 in Journal of Applied Physics
Verified
Journal Article
Closed access
PDF file
FYFirat Yasar
Firat Yasar
MKM. Kilin
M. Kilin
SDShahram Dehdashti
Shahram Dehdashti
ZYZ. Yu
Z. Yu
ZMZhenqiang Ma
Zhenqiang Ma
ZWZhehui Wang
Zhehui Wang
We study the self-collimation phenomenon in photonic crystals (PhC) of wide bandgap materials for ultra-fast and high spatial resolution x-ray detection. We work on various heavy inorganic scintillators: BaF2, GaN, ZnO, CsI:Tl, NaI:Tl, LYSO, WO4 compounds, and plastic scintillators. Conventional scintillator detectors do not rely on a direct detection mechanism; hence, they require intricate design and fabrication processes. We offer a PhC design to observe self-collimation phenomena and overcome the ongoing spatial resolution challenges with these types of materials. We investigate the photonic band diagrams and iso-frequency contours. Fourier transforms based on finite-difference time-domain and frequency domain simulations are done for verifying and analyzing the self-collimation with the selected material. Light extraction efficiency at the PhC–air interface, depending on the truncation distance from the excitation point, is measured. Beam divergence values are calculated at 1 mm propagation distance. The vertical field profiles are obtained to observe the confinement. For the spatial resolution analysis, cross-sectional beam profiles have been examined. Gaussian envelopes are fitted to beam profiles for a consistent data analysis, and full-width-at-half-maximum values are considered. As a result, we theoretically prove and demonstrate the spatially resolved x-ray detection at the sub-micrometer level for a wide range of scintillator materials.

4 February 2020 in Entropy
Verified
Journal Article
Open access
PDF file
SDShahram Dehdashti
Shahram Dehdashti
LFLauren Fell
Lauren Fell
PBPeter Bruza
Peter Bruza
This article presents a general framework that allows irrational decision making to be theoretically investigated and simulated. Rationality in human decision making under uncertainty is normatively prescribed by the axioms of probability theory in order to maximize utility. However, substantial literature from psychology and cognitive science shows that human decisions regularly deviate from these axioms. Bistable probabilities are proposed as a principled and straight forward means for modeling (ir)rational decision making, which occurs when a decision maker is in “two minds”. We show that bistable probabilities can be formalized by positive-operator-valued projections in quantum mechanics. We found that (1) irrational decision making necessarily involves a wider spectrum of causal relationships than rational decision making, (2) the accessible information turns out to be greater in irrational decision making when compared to rational decision making, and (3) irrational decision making is quantum-like because it violates the Bell–Wigner polytope.