A well-balanced flow equation for noise removal and edge detection

In this paper, an anisotropic nonlinear diffusion equation for image restoration is presented. The model has two terms: the diffusion and the forcing term. The balance between these terms is made in a selective way, in which boundary points and interior points of the objects that make up the image are treated differently. The optimal smoothing time concept, which allows for finding the ideal stop time for the evolution of the partial differential equation is also proposed. Numerical results show the proposed model's high performance.

A two phase flow nonlinear parameter estimation for capillary tube-suction line heat exchanger

Here we present two-phase flow nonlinear parameter estimation for HFC's flow through capillary tube-suction line heat exchangers, commonly used as expansion devices in small refrigeration systems. The simplifying assumptions adopted are: steady state, pure refrigerant, one-dimensional flow, negligible axial heat conduction in the fluid, capillary tube and suction line walls. Additionally, it is considered that the refrigerant is free from oil and both phases are assumed to be at the same pressure, that is, surface tension effects are neglected. Metastable flow effects are also disregarded, and the vapor is assumed to be saturated at the local pressure. The so-called homogeneous model, involving three, first order, ordinary differential equations is applied to analyze the two-phase flow region. Comparison is done with experimental measurements of the mass flow rate and temperature distribution along capillary tubes working with refrigerant HFC-134a in different operating conditions.

Ultrasound evaluation of common carotid artery blood flow in the Labrador retriever

Background: Doppler ultrasound (DUS) examination provides quantitative and qualitative information concerning the blood flow in veins and arteries, enabling their morphological evaluation and the collection of hemodynamic data. Dogs and cats as well as humans may display neurological signs of brain hypoperfusion secondary to common carotid alterations. Hence, DUS examination might aid in the differential diagnosis of neurological disorders of ischemic origin, among other causes. The objective of this study was to register normal values for systolic peak velocity, minimum diastolic velocity, diameter and resistance index of both common carotid arteries of 12 healthy Labrador retriever dogs between 2 and 5 years of age. By gathering these values, we might be able to improve the sensitivity of hemodynamic studies in clinically important brain disorders. Results: There were no statistical differences between the values for the right and left vessels: the systolic peak velocity was 75.8 ± 16 cm/s, minimum diastolic velocity was 12.2 ± 4 cm/s, common carotid diameter was 0.545 ± 0.063 cm, and resistance index was 0.83 ± 0.07. Conclusions: The results of this study might be used to establish normal parameters for Labrador retriever dogs and thus help in the diagnosis of neurological disorders associated with alterations of the carotid arteries. Similar studies must be performed to evaluate the same parameters in other dog breeds of different sizes and skull conformations. © 2013 Svicero et al.; licensee BioMed Central Ltd.

Measurement of four-jet production in proton-proton collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Measurement of differential cross sections for the production of a pair of isolated photons in pp collisions at root s=7TeV

A measurement of differential cross sections for the production of a pair of isolated photons in proton-proton collisions at root s = 7 TeV is presented. The data sample corresponds to an integrated luminosity of 5.0 fb(-1) collected with the CMS detector. A data-driven isolation template method is used to extract the prompt diphoton yield. The measured cross section for two isolated photons, with transverse energy above 40 and 25 GeV respectively, in the pseudorapidity range vertical bar eta vertical bar < 2.5, vertical bar eta vertical bar (sic) [1.44, 1.57] and with an angular separation Delta R > 0.45, is 17.2 +/-0.2 (stat) +/-1.9 (syst) +/- 0.4 (lumi) pb. Differential cross sections are measured as a function of the diphoton invariant mass, the diphoton transverse momentum, the azimuthal angle difference between the two photons, and the cosine of the polar angle in the Collins-Soper reference frame of the diphoton system. The results are compared to theoretical predictions at leading, next-to-leading, and next-to-next-to-leading order in quantum chromodynamics.

Modeling of continuous thermal processing of a non-Newtonian liquid food under diffusive laminar flow in a tubular system

The classic conservative approach for thermal process design can lead to over-processing, especially for laminar flow, when a significant distribution of temperature and of residence time occurs. In order to optimize quality retention, a more comprehensive model is required. A model comprising differential equations for mass and heat transfer is proposed for the simulation of the continuous thermal processing of a non-Newtonian food in a tubular system. The model takes into account the contribution from heating and cooling sections, the heat exchange with the ambient air and effective diffusion associated with non-ideal laminar flow. The study case of soursop juice processing was used to test the model. Various simulations were performed to evaluate the effect of the model assumptions. An expressive difference in the predicted lethality was observed between the classic approach and the proposed model. The main advantage of the model is its flexibility to represent different aspects with a small computational time, making it suitable for process evaluation and design. (C) 2012 Elsevier Ltd. All rights reserved.

The Li-8(p, alpha)He-5 reaction at low energies, and Be-9 spectroscopy around the proton threshold

We present a direct measurement of the low-energy Li-8(p, alpha)He-5 cross section, using a radioactive Li-8 beam impinging on a thick target. With four beam energies, we cover the energy range between E-c.m. = 0.2 and 2.1 MeV. An R-matrix analysis of the data is performed and suggests the existence of two broad overlapping resonances (5/2(+) at E-c.m. = 1.69 MeV and 7/2(+) at E-c.m. = 1.76 MeV). At low energies our data are sensitive to the properties of a subthreshold state (E-x = 16.67 MeV) and of two resonances above threshold. These resonances were observed in previous experiments. The R-matrix fit confirms spin assignments, and provides partial widths. We propose a new Li-8(p, alpha)He-5 reaction rate and briefly discuss its influence in nuclear astrophysics. DOI: 10.1103/PhysRevC.86.064321

Continuous enzymatic interesterification of lard and soybean oil blend: Effects of different flow rates on physical properties and acyl migration

Continuous enzymatic interesterification is an alternative to chemical interesterification for lipid modification technology which is economically viable for large scale use. A blend of 70% lard and 30% soybean oil was submitted to continuous enzymatic interesterification in a glass tubular bioreactor at flow rate ranging from 0.5 to 4.5 mL/min. The original mixture and the reaction products obtained were examined to determine melting and crystallization behavior by DSC, and analyzed for regiospecific fatty acid distribution. Continuous enzymatic interesterification changed the mixture, forming a new triacylglycerol composition, verified by DSC curves and variation in enthalpy of melting values. The regiospecific distribution of fatty acids was changed by flow variations in the reactor. In the continuous enzymatic interesterification reaction the flow rate of 4.5 mL/min, was more advantageous than slower flow rates, reducing acyl migration and increasing process productivity. (C) 2011 Elsevier B.V. All rights reserved.

Neutral pion and eta meson production in proton-proton collisions at root s=0.9 TeV and root s=7 TeV

The first measurements of the invariant differential cross sections of inclusive pi(0) and eta meson production at mid-rapidity in proton-proton collisions root s = 0.9 TeV and root s = 7 TeV are reported. The pi(0) measurement covers the ranges 0.4 < p(T) < 7 GeV/c and 0.3 < p(T) < 25 GeV/c for these two energies, respectively. The production of eta mesons was measured at root s = 7 TeV in the range 0.4 < p(T) < 15 GeV/c. Next-to-Leading Order perturbative QCD calculations, which are consistent with the pi(0) spectrum at root s = 0.9 TeV, overestimate those of pi(0) and eta mesons at root s = 7 TeV, but agree with the measured eta/pi(0) ratio at root s = 7 TeV. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.

Pion, Kaon, and Proton Production in Central Pb-Pb Collisions at root s(NN)=2.76 TeV

In this Letter we report the first results on pi(+/-), K-+/-, p, and (p) over bar production at midrapidity (vertical bar y vertical bar < 0.5) in central Pb-Pb collisions at root s(NN) = 2.76 TeV, measured by the ALICE experiment at the LHC. The p(T) distributions and yields are compared to previous results at root s(NN) = 200 GeV and expectations from hydrodynamic and thermal models. The spectral shapes indicate a strong increase of the radial flow velocity with root s(NN), which in hydrodynamic models is expected as a consequence of the increasing particle density. While the K/pi ratio is in line with predictions from the thermal model, the p/pi ratio is found to be lower by a factor of about 1.5. This deviation from thermal model expectations is still to be understood.

D-S(+) meson production at central rapidity in proton-proton collisions at root s=7 TeV

The P-T-differential inclusive production cross section of the prompt charm-strange meson D-s(+) in the rapidity range vertical bar y vertical bar < 0.5 was measured in proton-proton collisions at root s = 7 TeV at the LHC using the ALICE detector. The analysis was performed on a data sample of 2.98 x 10(8) events collected with a minimum-bias trigger. The corresponding integrated luminosity is L-int = 4.8 nb(-1). Reconstructing the decay D-s(+) -> phi pi(+) with phi -> K-K+, and its charge conjugate, about 480 D-s(+/-) mesons were counted, after selection cuts, in the transverse momentum range 2 < P-T < 12 GeV/c. The results are compared with predictions from models based on perturbative QCD. The ratios of the cross sections of four D meson species (namely D-0, D+, D*+ and D-s(+)) were determined both as a function of p(T) and integrated over p(T)after extrapolating to full p(T) range, together with the strangeness suppression factor in charm fragmentation. The obtained values are found to be compatible within uncertainties with those measured by other experiments in e(+)e(-), ep and pp interactions at various centre-of-mass energies. (C) 2012 CERN. Published by Elsevier By. All rights reserved.

Temporal constraints in large optical flow estimation

[EN] The aim of this work is to propose a model for computing the optical flow in a sequence of images. We introduce a new temporal regularizer that is suitable for large displacements. We propose to decouple the spatial and temporal regularizations to avoid an incongruous formulation. For the spatial regularization we use the Nagel-Enkelmann operator and a newly designed temporal regularization. Our model is based on an energy functional that yields a partial differential equation (PDE). This PDE is embedded into a multipyramidal strategy to recover large displacements. A gradient descent technique is applied at each scale to reach the minimum.

Reliable estimation of dense optical flow fields with large displacements

[EN] In this paper we show that a classic optical flow technique by Nagel and Enkelmann can be regarded as an early anisotropic diffusion method with a diffusion tensor. We introduce three improvements into the model formulation that avoid inconsistencies caused by centering the brightness term and the smoothness term in different images use a linear scale-space focusing strategy from coarse to fine scales for avoiding convergence to physically irrelevant local minima, and create an energy functional that is invariant under linear brightness changes.  Applying a gradient descent method to the resulting energy functional leads to a system of diffusion-reaction equations. We prove that this system has a unique solution under realistic assumptions on the initial data, and we present an efficient linear implicit numerical scheme in detail. Our method creates flow fields with 100% density over the entire image domain, it is robust under a large range of parameter variations, and it can recover displacement fields that are far beyond the typical one-pixel limits which are characteristic for many differential methods for determining optical flow. We show that it performs better than the classic optical flow methods with 100%  density that are evaluated by Barron et al. (1994). Our software is available from the Internet.

A scale-space aproach to nonlocal optical flow calculations

[EN] This paper presents an interpretation of a classic optical flow method by Nagel and Enkelmann as a tensor-driven anisotropic diffusion approach in digital image analysis. We introduce an improvement into the model formulation, and we establish well-posedness results for the resulting system of parabolic partial differential equations. Our method avoids linearizations in the optical flow constraint, and it can recover displacement fields which are far beyond the typical one-pixel limits that are characteristic for many differential methods for optical flow recovery. A robust numerical scheme is presented in detail. We avoid convergence to irrelevant local minima by embedding our method into a linear scale-space framework and using a focusing strategy from coarse to fine scales. The high accuracy of the proposed method is demonstrated by means of a synthetic and a real-world image sequence.

Photoproduktion neutraler Pionen am Proton mit linear polarisierten Photonen im Bereich der Schwelle

Diese Arbeit beschreibt ein Experiment zur Photoproduktionneutraler Pionen am Proton im Schwellenbereich. DurchVerwendung linear polarisierter Photonen konnte neben dentotalen und differentiellen Wirkungsquerschnitten zum erstenMal die Photonasymmetrie nahe der Schwelle gemessen werden.Besonderes Interesse galt dem aus diesen physikalischenObservablen bestimmbaren s-Wellen-Multipol E0+ sowie der erstmaligen Bestimmung aller drei p-Wellen-KombinationenP1, P2 und P3 im Bereich der Schwelle.Das Experiment wurde 1995/1996 am ElektronenbeschleunigerMAMI (Mainzer Mikrotron) der Universität Mainz durchgeführt.Durch Verwendung eines Diamanten als Bremsstrahltarget fürdie Elektronen wurden über den Prozeß der kohärentenBremsstrahlung linear polarisierte Photonen erzeugt. DieEnergie der Photonen wurde über die Messung der Energie der gestreuten Elektronen in der MainzerPhotonenmarkierungsanlage bestimmt. Der Detektor TAPS, eineAnordnung aus 504 BaF2-Modulen, war um einFlüssigwasserstofftarget aufgebaut. In den Modulen wurdendie im Target produzierten neutralen Pionen über ihrenZerfall in zwei Photonen nachgewiesen.Die totalen und differentiellen Wirkungsquerschnitte wurdenim Energiebereich zwischen der Schwelle von 144.7 MeV und168 MeV gemessen. Die erstmals gemessene Photonasymmetriefür 159.5 MeV ist positiv und hat einen Wert von+0.217+/-0.046 für einen Polarwinkel von 90 Grad. Der Multipol E0+ und die drei p-Wellen-Kombinationen wurden andie physikalischen Observablen über zwei unterschiedlicheMethoden angepaßt, die übereinstimmende Ergebnisselieferten. Die Vorhersagen der Niederenergietheoreme derchiralen Störungstheorie für P1 und P2 stimmen beiEinbeziehung der statistischen und systematischen Fehler mitden experimentellen Werten überein.