Search results for " NOISE"

Synthetic aperture superresolution by speckle pattern projection.

2009

We propose a method for increasing the resolution of an aperture limited optical system by illuminating the input with a speckle pattern. The high resolution of the projected speckle pattern demodulates the high frequencies of the sample and permits its passage through the system aperture. A decoding provides the superresolved image. The speckle pattern can be generated in a simple manner in contrast with other structured light superresolution methods. The method is demonstrated in microscopy test images.

Aiding phase unwrapping by increasing the number of residues in two-dimensional wrapped-phase distributions.

2015

In phase unwrapping residues are points of locally inconsistent phase that occur within a wrapped-phase map, which are usually regarded as being problematic for phase-unwrapping algorithms. Real phase maps typically contain a number of residues that are approximately proportional to the subsequent difficulty in unwrapping the phase distribution. This paper suggests the radical use of the discrete Fourier transform to actually increase the number of residues in 2D phase-wrapped images that contain discontinuities. Many of the additional residues that are artificially generated by this method are located on these discontinuities. For example, in fringe projection systems, such phase discontin…

Enabling quantum non-Markovian dynamics by injection of classical colored noise

2017

The non-Markovian nature of quantum systems recently turned to be a key subject for investigations on open quantum system dynamics. Many studies, from its theoretical grounding to its usefulness as a resource for quantum information processing and experimental demonstrations, have been reported in the literature. Typically, in these studies, a structured reservoir is required to make non-Markovian dynamics emerge. Here, we investigate the dynamics of a qubit interacting with a bosonic bath and under the injection of a classical stochastic colored noise. A canonical Lindblad-like master equation for the system is derived by using the stochastic wave function formalism. Then, the non-Markovia…

Accounting for operating environments in measuring water utilities’ managerial efficiency

2009

In this paper adjusted input-specific scores of technical efficiency are computed for a sample of Spanish water utilities. Performance is adjusted by netting out efficiency scores from the effect of operating environments and statistical noise. The results show that computation of adjusted efficiency scores at the input level manifestly improves the assessment of utilities’ performance in our sample of water utilities. In addition, several environmental variables capable of affecting input-specific technical management are discovered, ownership or demand seasonality among them. Finally, distributions of conventional and adjusted scores of technical performance are found to be statistically …

Analog Multiple Description Joint Source-Channel Coding Based on Lattice Scaling

2015

Joint source-channel coding schemes based on analog mappings for point-to-point channels have recently gained attention for their simplicity and low delay. In this paper, these schemes are extended either to scenarios with or without side information at the decoders to transmit multiple descriptions of a Gaussian source over independent parallel channels. They are based on a lattice scaling approach together with bandwidth reduction analog mappings adapted for this multiple description scenario. The rationale behind lattice scaling is to improve performance through bandwidth expansion. Another important contribution of this paper is the proof of the separation theorem for the communication …

Comparison of basis functions for 3D PET reconstruction using a Monte Carlo system matrix.

2012

In emission tomography, iterative statistical methods are accepted as the reconstruction algorithms that achieve the best image quality. The accuracy of these methods relies partly on the quality of the system response matrix (SRM) that characterizes the scanner. The more physical phenomena included in the SRM, the higher the SRM quality, and therefore higher image quality is obtained from the reconstruction process. High-resolution small animal scanners contain as many as 103?104 small crystal pairs, while the field of view (FOV) is divided into hundreds of thousands of small voxels. These two characteristics have a significant impact on the number of elements to be calculated in the SRM. …

Detuning effects in STIRAP processes in the presence of quantum noise

2011

The Stimulated Raman adiabatic passage (STIRAP) in three-state systems in the presence of quantum noise is considered. A comparison is made between different models, one based on a phenomenological introduction of decays, one traceable back to a microscopic description of the system-environment interaction. Effects related, to off-resonance in the coupling between the involved states are considered.

Discrete Tomography Reconstruction Through a New Memetic Algorithm

2008

Discrete tomography is a particular case of computerized tomography that deals with the reconstruction of objects made of just one homogeneous material, where it is sometimes possible to reduce the number of projections to no more than four. Most methods for standard computerized tomography cannot be applied in the former case and ad hoc techniques must be developed to handle so few projections.

Noisy dynamics in long and short Josephson junctions

The study of nonlinear dynamics in long Josephson junctions and the features of a particular kind of junction realized using a graphene layer, are the main topics of this research work. The superconducting state of a Josephson junction is a metastable state, and the switching to the resistive state is directly related to characteristic macroscopic quantities, such as the current the voltage across the junction, and the magnetic field through it. Noise sources can affect the mean lifetime of this superconducting metastable state, so that noise induced effects on the transient dynamics of these systems should be taken into account. The long Josephson junctions are investigated in the sine-Gor…

Transportation noise and risk of stroke: a nationwide prospective cohort study covering Denmark

2021

AbstractBackgroundStudies on transportation noise and incident stroke are few and inconclusive. We aimed to investigate associations between road-traffic and railway noise and the risk of incident stroke in the entire Danish population.MethodsWe estimated road-traffic and railway noise (Lden) at the most and least exposed façades for all residential addresses across Denmark (2.8 million) for the period 1990–2017. Based on this, we estimated the 10-year time-weighted mean noise exposure for 3.6 million Danes aged >35 years, of whom 184 523 developed incident stroke during follow-up from 2000 to 2017. Analyses were conducted using Cox proportional-hazards models, with adjustment for va…