79 research outputs found
Applying GMDH-Type Neural Network and Genetic Algorithm for Stock Price Prediction of Iranian Cement Sector
The cement industry is one of the most important and profitable industries in Iran and great content of financial resources are investing in this sector yearly. In this paper a GMDH-type neural network and genetic algorithm is developed for stock price prediction of cement sector. For stocks price prediction by GMDH type-neural network, we are using earnings per share (EPS), Prediction Earnings Per Share (PEPS), Dividend per share (DPS), Price-earnings ratio (P/E), Earnings-price ratio (E/P) as input data and stock price as output data. For this work, data of ten cement companies is gathering from Tehran stock exchange (TSE) in decennial range (1999-2008). GMDH type neural network is designed by 80% of the experimental data. For testing the appropriateness of the modeling, reminder of primary data were entered into the GMDH network. The results are very encouraging and congruent with the experimental result
Hydrodynamic electron pumping in two-dimensional electron systems as a signature of viscous transport
Hydrodynamic effects arising from electron-electron interactions can have a
significant influence on transport dynamics in ultra-clean two-dimensional
electron systems in the solid state. A growing interest in electron
hydrodynamics in the solid state has been noted due to the development of new
materials systems. Hence signatures of this hydrodynamic regime, where the rate
of momentum conserving collisions exceed that of momentum relaxing collisions,
are increasingly being explored. Here, we experimentally study a hydrodynamic
pumping phenomenon using a transverse magnetic focusing geometry, whereby a
ballistic electron jet sweeping past a lithographic aperture can extract (pump)
electrons from this aperture. This phenomenon highlights the importance of
electron-electron interactions and concomitant hydrodynamic phenomena in
mesoscopic ballistic transport, delivers an experimentally supported
explanation of nonlocal negative resistances observed in transverse magnetic
focusing as signatures of the hydrodynamic regime, and indicates that the
Coulombic repulsive interaction can result in a net attractive force.Comment: 13 page
Symmetric Operation of the Resonant Exchange Qubit
We operate a resonant exchange qubit in a highly symmetric triple-dot
configuration using IQ-modulated RF pulses. At the resulting three-dimensional
sweet spot the qubit splitting is an order of magnitude less sensitive to all
relevant control voltages, compared to the conventional operating point, but we
observe no significant improvement in the quality of Rabi oscillations. For
weak driving this is consistent with Overhauser field fluctuations modulating
the qubit splitting. For strong driving we infer that effective voltage noise
modulates the coupling strength between RF drive and the qubit, thereby
quickening Rabi decay. Application of CPMG dynamical decoupling sequences
consisting of up to n = 32 {\pi} pulses significantly prolongs qubit coherence,
leading to marginally longer dephasing times in the symmetric configuration.
This is consistent with dynamical decoupling from low frequency noise, but
quantitatively cannot be explained by effective gate voltage noise and
Overhauser field fluctuations alone. Our results inform recent strategies for
the utilization of partial sweet spots in the operation and long-distance
coupling of triple-dot qubits.Comment: 6 pages, 5 figure
Negative spin exchange in a multielectron quantum dot
By operating a one-electron quantum dot (fabricated between a multielectron
dot and a one-electron reference dot) as a spectroscopic probe, we study the
spin properties of a gate-controlled multielectron GaAs quantum dot at the
transition between odd and even occupation number. We observe that the
multielectron groundstate transitions from spin-1/2-like to singlet-like to
triplet-like as we increase the detuning towards the next higher charge state.
The sign reversal in the inferred exchange energy persists at zero magnetic
field, and the exchange strength is tunable by gate voltages and in-plane
magnetic fields. Complementing spin leakage spectroscopy data, the inspection
of coherent multielectron spin exchange oscillations provides further evidence
for the sign reversal and, inferentially, for the importance of non-trivial
multielectron spin exchange correlations.Comment: 8 pages, including 4 main figures and 2 supplementary figurure
- …