921 research outputs found
Removing zero Lyapunov exponents in volume-preserving flows
Baraviera and Bonatti proved that it is possible to perturb, in the c^1
topology, a volume-preserving and partial hyperbolic diffeomorphism in order to
obtain a non-zero sum of all the Lyapunov exponents in the central direction.
In this article we obtain the analogous result for volume-preserving flows.Comment: 10 page
COMPARISON OF FLOW PATTERNS IN THE RADIOCEPHALIC ARTERIOVENOUS FISTULA THROUG IN VITRO AND IN SILICO STUDY
The vascular accesses to hemodialysis patients usually are through arteriovenous fistula (AVF) or synthetic grafts. The analyses of recirculation zones, stagnation points, secondary flow and low and high shear stress are very important points to study for understand the hemodynamic local in arteriovenous fistula. In this work, it was analyzed through computational fluid dynamics the streamlines in AVF and it was compared with the literature results. The flow patterns were visualized under steady and unsteady condition with Reynolds number ranging from 100 up 600. The results obtained from CFD were very similar with the literature results. The flow becomes more chaotic when the Reynolds number increases. Vortex can be seen in anastomosis region, occupying all transversal section of the artery. Thus, the results obtained using CFD look like the results obtained experimentally
Effective potential in the BET formalism
We calculate the one-loop effective potential at finite temperature for a
system of massless scalar fields with quartic interaction in
the framework of the boundary effective theory (BET) formalism. The calculation
relies on the solution of the classical equation of motion for the field, and
Gaussian fluctuations around it. Our result is non-perturbative and differs
from the standard one-loop effective potential for field values larger than
.Comment: 10 pages, 3 figure
Distribuição de Salmonella typhimurium em órgãos de suínos após inoculação oral.
Projeto/Plano de Ação: 02.06.60.400-02
Pressure of massless hot scalar theory in the boundary effective theory framework
We use the boundary effective theory (BET) approach to thermal field theory
in order to calculate the pressure of a system of massless scalar fields with
quartic interaction. The method naturally separates the infrared physics, and
is essentially non-perturbative. To lowest order, the main ingredient is the
solution of the free Euler-Lagrange equation with non-trivial (time) boundary
conditions. We derive a resummed pressure, which is in good agreement with
recent calculations found in the literature, following a very direct and
compact procedure.Comment: 10 pages, 4 figure
Verification of Magnitude and Phase Responses in Fixed-Point Digital Filters
In the digital signal processing (DSP) area, one of the most important tasks
is digital filter design. Currently, this procedure is performed with the aid
of computational tools, which generally assume filter coefficients represented
with floating-point arithmetic. Nonetheless, during the implementation phase,
which is often done in digital signal processors or field programmable gate
arrays, the representation of the obtained coefficients can be carried out
through integer or fixed-point arithmetic, which often results in unexpected
behavior or even unstable filters. The present work addresses this issue and
proposes a verification methodology based on the digital-system verifier
(DSVerifier), with the goal of checking fixed-point digital filters w.r.t.
implementation aspects. In particular, DSVerifier checks whether the number of
bits used in coefficient representation will result in a filter with the same
features specified during the design phase. Experimental results show that
errors regarding frequency response and overflow are likely to be identified
with the proposed methodology, which thus improves overall system's
reliability
Biological removal processes in aerobic granular sludge exposed to diclofenac
Diclofenac is a worldwide consumed drug included in the watch list of substances to be monitored according to the European Union Water Framework Directive (Directive 2013/39/EU). Aerobic granular sludge sequencing batch reactors (AGS-SBR) are increasingly used for wastewater treatment but there is scant information on the fate and effect of micropollutants to nutrient removal processes. An AGS-SBR fed with synthetic wastewater containing diclofenac was bioaugmented with a diclofenac degrading bacterial strain and performance and microbial community dynamics was analysed. Chemical oxygen demand, phosphate and ammonia removal were not affected by the micropollutant at 0.03 mM (9.54 mg L-1). The AGS was able to retain the degrading strain, which was detected in the sludge throughout after augmentation. Nevertheless, besides some adsorption to the biomass, diclofenac was not degraded by the augmented sludge given the short operating cycles and even if batch degradation assays confirmed that the bioaugmented AGS was able to biodegrade the compound. The exposure to the pharmaceutical affected the microbial community of the sludge, separating the two first phases of reactor operation (acclimatization and granulation) from subsequent phases. The AGS was able to keep the bioaugmented strain and to maintain the main functions of nutrient removal even through the long exposure to the pharmaceutical, but combined strategies are needed to reduce the spread of micropollutants in the environment.info:eu-repo/semantics/acceptedVersio
- …