Search results for "POLARIZATION"

A Dialysis Photocatalytic Reactor for the Green Production of Vanillin

2020

In the present work, dialysis was used to recover vanillin while being produced by partial photocatalytic oxidation of ferulic acid in an aqueous solution at ambient temperature. The relatively high value of the permeate flux through a dense polyether-block amide membrane allowed continuously extracting vanillin from the reacting solution, thus avoiding its successive oxidation. The rate of vanillin formation was improved, compared to other reactor configurations, because intermediate compounds permeated from the reacting solution and did not hinder the reaction, while ferulic acid permeated in the opposite direction to partially replenish the reactor with the substrate. The photocatalytic …

Domain Wall Spin Structures in Mesoscopic Fe Rings probed by High Resolution SEMPA

2016

We present a combined theoretical and experimental study of the energetic stability and accessibility of different domain wall spin configurations in mesoscopic magnetic iron rings. The evolution is investigated as a function of the width and thickness in a regime of relevance to devices, while Fe is chosen as a material due to its simple growth in combination with attractive magnetic properties including high saturation magnetization and low intrinsic anisotropy. Micromagnetic simulations are performed to predict the lowest energy states of the domain walls, which can be either the transverse or vortex wall spin structure, in good agreement with analytical models, with further simulations …

The cost of an action potential.

2000

Neuronal modules, or 'cell-assemblies', comprising millions of mutually interconnected cells have been postulated to form the basis of many functions of the brain, such as mood, sleep, hunger, vigilance, and more. Depending on the extent of the module, neurocommunication in cell-assemblies might exceed metabolic resources. A medium-size (10000 neurons) module would require at least 10 J per l of brain, based on a calculated cost of an isolated action potential (AP) of 10(11)-10(12) molecules of ATP per cm(2) of cell membrane, with an absolute minimum of 10(6) ATP at a node of Ranvier. The figure matches the cost of depolarizing the unmyelinated axon of the large monopolar cell in the blowfl…

New materials with high spin polarization: half-metallic Heusler compounds

2007

Active Lighting Applied to Shape from Polarization

2006

We present a new way of solving the ambiguity that appears in the shape from polarization method. This ambiguity, concerning the normals orientation of the surface, was previously solved thanks to a propagation algorithm. In this paper, the ambiguity is solved thanks to a special active lighting. This method is less time computing and is more robust to noise acquisition. We first demonstrate how to compute the right normals on the whole surface. Then, we show an application on the 3D reconstruction of a specular metallic object made by stamping and polishing.

Radiation in the Atmosphere - A Course in Theoretical Meteorology

2007

This book presents the theory and applications of radiative transfer in the atmosphere. It is written for graduate students and researchers in the fields of meteorology and related sciences. The book begins with important basic definitions of the radiative transfer theory. It presents the hydrodynamic derivation of the radiative transfer equation and the principles of variance. The authors examine in detail various quasi-exact solutions of the radiative transfer equation and give a thorough treatment of the radiative perturbation theory. A rigorous treatment of Mie scattering is given, including Rayleigh scattering as a special case, and the important efficiency factors for extinction, scat…

Shaded-mask filtering: novel strategy for improvement of resolution in radial-polarization scanning microscopy

2006

Radially polarized illumination produces, in combination with annular pupil filtering, the sharpest focal spot. However, the enhanced sidelobes produce an effective deterioration of spatial resolution. This study shows that if one substitutes the annular filter by one, adequately designed, shaded-mask filter, the sidelobes' strength is strongly reduced, and an important, effective improvement of resolution is achieved.

Microscope system with on axis programmable Fourier transform filtering

2017

Abstract We propose an on-axis microscope optical system to implement programmable optical Fourier transform image processing operations, taking advantage of phase and polarization modulation of a liquid crystal on silicon (LCOS) display. We use a Hamamatsu spatial light modulator (SLM), free of flickering, which therefore can be tuned to fully eliminate the zero order component of the encoded diffractive filter. This allows the realization of filtering operation on axis (as opposed to other systems in the literature that require operating off axis), therefore making use of the full space bandwidth provided by the SLM. The system is first demonstrated by implementing different optical proce…

Polarization Modulation Instability in All-Normal Dispersion Microstructured Optical Fibers With Quasi-Continuous Pump

2019

We report the experimental observation of the polarization modulation instability (PMI) effect in all-normal dispersion (ANDi) microstructured optical fibers (MOFs) with quasi-continuous pumping. The small unintentional birefringence (~10-5), that any realistic non-polarization maintaining MOF exhibits, contributes to this nonlinear effect. PMI can produce two sidebands whose polarization state is orthogonal to the polarization of the pump. In this work, only one type of PMI process is observed, i.e., when the pump is polarized along the slow axis of the fiber and sidebands are generated in the fast axis mode. This PMI process was studied experimentally in two ANDi fibers with different dis…

Polarization stereoscopic imaging prototype

2011

The polarization of light was introduced last ten years ago in the field of imaging system is a physical phenomenon that can be controlled for the purposes of the vision system. As that found in the human eyes, in general the imaging sensors are not under construction which is sensitive to the polarization of light. These properties can be measured by adding optical components on a conventional camera. The purpose of this thesis is to develop an imaging system that is sensitive both to the stereoscopic and to the state of polarization. As well as the visual system on a various of insects in nature such as bees, that are have capability to move in space by extracted relevant information from…