Numerical study on mixing of sprayed liquid in an LNG storage tank

This paper presents a numerical method to simulate the mixing of heavier LNG sprayed on lighter layer. Numerical results for evolutions of flow field and density field are obtained in a rectangular computational domain which includes the vicinity of the liquid surface. At the surface boundary, uniform distributions of the fluid velocity and the density are assumed. Detail structure of flow caused by impingements of liquid drops are neglected. But, to trigger a realistic motion, a series of random numbers is employed. It is used as an initial distribution of the density near the surface. This method successfully gives a realistic simulation of the mixing process. Numerical results for mixing velocity shows good agreement with experimental data

Estimation of cardiovascular indices by analysis of the arterial blood pressure signal

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 175-177).This thesis introduces novel mathematical algorithms that track changes in stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR) by analysis of the arterial blood pressure (ABP) signal. The algorithms incorporate cardiovascular physiology within the framework of a generalized Windkessel model, which is a widely accepted cardiovascular model. Algorithms to identify end systole were also developed and implemented in the new and existing SV, CO, and TPR estimation algorithms. The algorithms were validated by applying them to previously recorded Yorkshire swine data sets that include directly measured aortic blood flow (ABF), SV, CO, as well as central and peripheral ABP. Among the algorithms using the end systole identification algorithms, Parabolic Method, Modified Herd's Method, Kouchoukos Correction Method, and Corrected Impedance Method achieved low root normalized mean squared errors (RNMSEs). This thesis also introduces and validates a novel algorithm to reconstruct instantaneous ABF waveforms from the ABP signal. The algorithm utilizes an auto-regressive with exogenous input (ARX) model to describe the filter between ABF and ABP. Because ABF (the exogenous input to the peripheral circulation) is approximately zero during diastole, the diastolic ABP waveforms can be regarded as auto-regressive (AR). By the AR analysis of multiple diastolic ABP waveforms, the AR parameters are obtained. The AR parameters were applied to the ABP waveforms (both systolic and diastolic) to compute beat-to-beat ABF waveforms. The errors of skewness and kurtosis of the estimated ABF waveforms were statistically smaller than those estimated by the standard Windkessel model. The estimated ABF waveforms were further processed to estimate SV, CO, and TPR. The algorithm achieved RNMSEs of 15.3, 19.6, and 21.8% in SV estimation; 12.7, 15.2, and 15.8% in CO estimation; and 14.3, 20.9, and 19.4 % in TPR estimation derived from central, femoral, and radial ABP, respectively.by Tatsuya Arai.Ph.D

The construction of P-expansive maps of regular continua: A geometric approach

AbstractIn this paper, we prove the following: Let G be a graph, f:G→G a continuous map and P a finite subset of G such that f(P)⊂P. Then there exist a regular continuum Z, a continuous map g:Z→Z and a semi-conjugacy π:G→Z such that(1) g is π(P)-expansive, and(2) if p,q∈P and Q is a subset of P with A∩Q≠∅ for any arc A in G between p and q, then A′∩π(Q)≠∅ for any arc A′ in Z between π(p) and π(q).In addition, f is point-wise P-expansive if and only if π|P is one-to-one.In this paper we are especially interested in the geometrical structure of Z. Actually we can see the complicated construction of Z

Estimation of changes in instantaneous aortic blood flow by the analysis of arterial blood pressure

The purpose of this study was to introduce and validate a new algorithm to estimate instantaneous aortic blood flow (ABF) by mathematical analysis of arterial blood pressure (ABP) waveforms. The algorithm is based on an autoregressive with exogenous input (ARX) model. We applied this algorithm to diastolic ABP waveforms to estimate the autoregressive model coefficients by requiring the estimated diastolic flow to be zero. The algorithm incorporating the coefficients was then applied to the entire ABP signal to estimate ABF. The algorithm was applied to six Yorkshire swine data sets over a wide range of physiological conditions for validation. Quantitative measures of waveform shape (standard deviation, skewness, and kurtosis), as well as stroke volume and cardiac output from the estimated ABF, were computed. Values of these measures were compared with those obtained from ABF waveforms recorded using a Transonic aortic flow probe placed around the aortic root. The estimation errors were compared with those obtained using a windkessel model. The ARX model algorithm achieved significantly lower errors in the waveform measures, stroke volume, and cardiac output than those obtained using the windkessel model (P < 0.05)

MIXED MODES INTERLAMINAR FRACTURE TOUGHNESS OF CFRP LAMINATES TOUGHENED WITH CNF INTERLAYER

In the present paper, the influence of carbon nanofiber on interlaminar fracture toughness of CFRP investigated using MMB(Mixed Mode Bending) tests. Vapor grown carbon fiber VGCF and VGCF-S, and multi-walled carbon nanotube MWNT-7 has been employed for the toughener of the interlayer on the CFRP laminates. In order to evaluate the fracture toughness and mixed mode ratio of it, double cantilever beam (DCB) tests, end notched fracture (ENF) tests and mixed mode bending (MMB) tests have been carried out. Boundary element analysis was applied to the CFRP model to compute the interlaminar fracture toughness, where extrapolation method was used to determine the fracture toughness and mixed mode ratio. The interlaminar fracture toughness and mixed mode ratio can be extrapolated by stress distribution in the vicinity of the crack tip of the CFRP laminate. It was found that the interlaminar fracture toughness of the CFRP laminates was improved inserting the interlayer made by carbon nanofiber especially in the region where shear mode deformation is dominant.ArticleACTA MECHANICA SOLIDA SINICA. 25(3):321-330 (2012)journal articl