Search

Research was conducted to study steam injection in a water-saturated two-dimensional reservoir utilizing a two-phase mixture model. Numerical analyses were based on the two-phase mixture model wherein boundary conditions were given in relation to the mixture pressure. Results showed that the cumulative displaced mass per unit of cross sectional area for various injection fluxes was directly proportional to time. They also indicated that superheated steam can help mobilize residual liquid to achieve complete recovery.

A method for the estimation of the regression coefficients in an assumed mean function was developed by using different estimates for selection probabilities. The nonparametric smoothing of the selection probabilities was a useful tool for large sampling sizes with limited data on probability density and mean function. Furthermore, the proposed weighted semiparametric estimation in regression analysis with missing covariates was designed mainly for continuous data.

In this paper we discuss the estimation of a logit binary response model. The sampling is choice-based and is done in two stages. We investigate a likelihood-based estimator which reduces to the usual logistic estimator when there is no measurement error and which takes into account the constraints imposed by the structure of the problem. Estimated standard errors obtained by formulae for prospective analysis are asymptotically correct. A robust estimation procedures is proposed and an asymptotic covariance matrix obtained. Several bootstrap methods are applied to this retrospective problem. Numerical results are presented to illustrate useful properties of the methods. Key words: Binary logit; Bootstrap; Choice-based sampling; Measurement error; Robustness

The efficient method of eigenfunction expansion and point match is used to solve the Stokes flow through a channel with transverse fins. Both in-phase and staggered fins are considered. Streamlines and resistances are found in terms of fin height and fin spacing. Extrapolating to large spacings, the added resistances due to a single pair of aligned fins and that of a single fin in a channel are obtained.

The boundary layer analysis of buoyancy-driven two-phase flow in capillary porous media reveals that the boiling boundary layer is wider than the condensing boundary layer. A two-phase crossflow pattern represents both the boiling and the condensing flow. The unsaturated flow theory is invalid for the condensing flow, and a two-phase model predicts the capillary effect on film condensation heat transfer.

Solutions to the Stokes equation for the rotation of finite, coaxial cylinders are achievable by integrating the concepts of domain decomposition, collocation, and eigenfunctions. A solid cylinder rotates within a larger, fluid-filled cylindrical enclosure. The method requires lesser computations compared to direct integrations and is useful for designing rotating cylinders at low Reynolds number. The case of a finite cylinder rotating in an infinite fluid is discussed.

The absence of a general theory for classical prospective logistic regression analysis with covariate values is examined. Such a theory is developed where consistent estimates and standard errors are applied to case-control studies. It is shown that sufficient conditions can be set such that prospective errors are asymptotically correct and minimized. The theory also allowed for applications in case-control studies with missing data., [Mathematical Expression Omitted]. Let [[Psi].sub.12] = [[Psi].sub.22]([center dot], [Theta]) be the vector of size 2M whose (dM + m)th element equals I(D = d) {I(Z = m) - [[Theta].sub.2,md]}. Let [...]

The laminar, viscous flow between parallel plates with evenly spaced longitudinal ribs is solved by an eigenfunction expansion and point-match method. The ribs on both plates may be symmetrically placed or staggered. For a given pressure gradient, the mean velocity is plotted as a function of the geometric parameters. We find the wetted perimeter and the friction factor - Reynolds number product are unsuitable parameters for the flow through ducts of complex geometry.

A two-dimensional porous chamber which has a horizontal baffle extending from the side wall, exhibits convective unsteadiness. Steady low and high temperatures are reflected in the top and bottom respectively, but the side walls are insulated. The assumed steady baffle temperature affects the constancy of the chamber. A longer baffle does not guarantee steadiness but closeness of the center results in constancy. The upper part of the chamber reveals the beginning of the convection. The single cell is penetrated by increased baffle length, leading to four replicated cells indicating the beginning of the convection.

A viscous shear flow moves parallel to a wavy plate. Partial slip occurs on the wavy surface. The problem is solved by perturbation about a small amplitude parameter, namely, the amplitude to wavelength ratio. It is found that the interaction of waviness and slip decreases the apparent slip coefficient. [DOI: 10.1115/1.4002197] Keywords: viscous flow, slip, wavy, shear

X-ray double-crystal diffraction and x-ray grazing incidence diffraction were used to study the Si1-xGex/Si strained-layer superlattices grown by molecular beam epitaxy on Si substrates. It was shown that growth parameters influence superlattice structural parameters such as composition fraction and layer thickness ratio. Furthermore, the findings suggest that a combination of high-resolution double-crystal diffraction and computer simulation can characterize detailed structures of superlattices.

THE THIRD HYPERVARIABLE REGION ([V.sub.3.)] of the human immunodeficiency virus-1 (HIV-1) external envelope glycoprotein (gp120) contains a cysteine loop that constitutes the PND [1-6]. A relatively conserved GPGR [7] sequence [...]

Blood flow in a small tube (30-1000 [micro]m) can be successfully modeled by the two-fluid model. The fully developed, constant heat flux convective heat transfer problem is studied. The velocity and temperature profiles are determined in closed form. Formulas for friction-factor-Reynolds number product, axial temperature gradient, and Nusselt number are found. [DOI: 10.1115/1.2898722] Keywords: blood flow, two fluid, heat