27,692 research outputs found
Local nonsimilarity method for the two-phase boundary layer in mixed convection laminar film condensation
The two-phase boundary layer in laminar film condensation was solved by Koh for the free convection regime and forced convection regime using the similarity method. But the problem on mixed convection does not admit similarity solutions. The current work develops a local nonsimilarity method for the full spectrum of mixed convection, with a generic boundary layer formulation reduced to two specific cases mathematically identical to Koh's formulations on the two limiting cases for either free or forced convection. Other solution methods for mixed convection in the literature are compared and critically evaluated to ensure a high level of accuracy in the current method. The current solution is used to extend Fujii's correlation for mixed convection to the region where the energy convection effect is significant but has been hitherto neglected. The modified Fujii correlation provides a practical engineering tool for evaluating laminar film condensation with a mixed convection boundary laye
A novel ingress node design for video streaming over optical burst switching networks
This paper introduces a novel ingress node design which takes advantage of video data partitioning in order to deliver enhanced video streaming quality when using H.264/AVC codec over optical burst switching networks. Ns2 simulations show that the proposed scheme delivers improved video traffic quality without affecting other traffic, such as best effort traffic. Although the extra network load is comparatively small, the average gain in video PSNR was 5 dB over existing burst cloning schemes, with a maximum end-to-end delay of 17 ms, and jitter of less than 0.35 ms
Hadronic fluctuations in the QGP
We analyze fluctuations of quark number and electric charge, in 2-flavour QCD
at finite temperature and vanishing net baryon number density. In the hadronic
phase we find that an enhancement of charge fluctuations arises from
contributions of doubly charged hadrons to the thermodynamics. The rapid
suppression of fluctuations seen in the high temperature phase suggests that in
the QGP quark number and electric charge are predominantly carried by
quasi-particles with the quantum numbers of quarks.Comment: 4 pages, 6 EPS-files, talk presented at Quark Matter 2005, Budapes
On the Convergence of the Expansion of Renormalization Group Flow Equation
We compare and discuss the dependence of a polynomial truncation of the
effective potential used to solve exact renormalization group flow equation for
a model with fermionic interaction (linear sigma model) with a grid solution.
The sensitivity of the results on the underlying cutoff function is discussed.
We explore the validity of the expansion method for second and first-order
phase transitions.Comment: 12 pages with 10 EPS figures included; revised versio
Investigation into O(N) Invariant Scalar Model Using Auxiliary-Mass Method at Finite Temperature
Using auxiliary-mass method, O(N) invariant scalar model is investigated at
finite temperature. This mass and an evolution equation allow us to calculate
an effective potential without an infrared divergence. Second order phase
transition is indicated by the effective potential. The critical exponents are
determined numerically.Comment: LaTex 8 pages with 3 eps figure
Flow Equations for U_k and Z_k
By considering the gradient expansion for the wilsonian effective action S_k
of a single component scalar field theory truncated to the first two terms, the
potential U_k and the kinetic term Z_k, I show that the recent claim that
different expansion of the fluctuation determinant give rise to different
renormalization group equations for Z_k is incorrect. The correct procedure to
derive this equation is presented and the set of coupled differential equations
for U_k and Z_k is definitely established.Comment: 5 page
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High-frequency oscillatory ventilation in pediatric acute hypoxemic respiratory failure: disease-specific morbidity survival analysis.
BackgroundMultiple ventilatory strategies for acute hypoxemic respiratory failure (AHRF) in children have been advocated, including high-frequency oscillatory ventilation (HFOV). Despite the frequent deployment of HFOV, randomized controlled trials remain elusive and currently there are no pediatric trials looking at its use. Our longitudinal study analyzed the predictive clinical outcome of HFOV in pediatric AHRF given disease-specific morbidity.MethodsA retrospective 8-year review on pediatric intensive care unit admissions with AHRF ventilated by HFOV was performed. Primary outcomes included survival, morbidity, length of stay (LOS), and factors associated with survival or mortality.ResultsA total of 102 patients underwent HFOV with a 66 % overall survival rate. Survivors had a greater LOS than nonsurvivors (p = 0.001). Mortality odds ratio (OR) for patients without bronchiolitis was 8.19 (CI = 1.02, 65.43), and without pneumonia it was 3.07 (CI = 1.12, 8.39). A lower oxygenation index (OI) after HFOV commencement and at subsequent time points analyzed predicted survival. After 24 h, mortality was associated with an OI > 35 [OR = 31.11 (CI = 3.25, 297.98)]. Sepsis-related mortality was associated with a higher baseline FiO(2) (0.88 vs. 0.65), higher OI (42 vs. 22), and augmented metabolic acidosis (pH of 7.25 vs. 7.32) evaluated 4 h on HFOV (p < 0.05).ConclusionHigh-frequency oscillatory ventilation may be safely utilized. It has a 66 % overall survival rate in pediatric AHRF of various etiologies. Patients with morbidity limited to the respiratory system and optimized oxygenation indices are most likely to survive on HFOV
Renormalization Group Approach to Field Theory at Finite Temperature
Scalar field theory at finite temperature is investigated via an improved
renormalization group prescription which provides an effective resummation over
all possible non-overlapping higher loop graphs. Explicit analyses for the
lambda phi^4 theory are performed in d=4 Euclidean space for both low and high
temperature limits. We generate a set of coupled equations for the mass
parameter and the coupling constant from the renormalization group flow
equation. Dimensional reduction and symmetry restoration are also explored with
our improved approach.Comment: 29 pages, can include figures in the body of the text using epsf.st
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MFN status and the choice of tariff regime
The gradualist approach to trade liberalization views the uniform tariffs implied by MFN status as an important step on the path to free trade. We investigate whether a regime of uniform tariffs will be preferable to discriminatory tariffs when countries engage in non-cooperative interaction in multilateral trade. The analysis includes product differentiation and asymmetric costs. We show that with the cost asymmetry the countries will disagree on the choice of tariff regime. When the choice of import tariffs and export subsidies is made sequentially the uniform tariff regime may not be sustainable, because of an incentive to deviate to a discriminatory regime. Hence, an international body is needed to ensure compliance with tariff agreement
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