Disentangle Kinetic From Equilibrium Fractionation Using Primary (δ17O, δ18O, δD) and Secondary (Δ17O, dex) Stable Isotope Parameters on Samples From the Swiss Precipitation Network

Since 1971 water isotope measurements are being conducted by the Climate and Environmental Physics Division at the University of Bern on precipitation, river- and groundwater collected at several places within Switzerland. The water samples were stored in glass flasks for later analyses with improved instrumentation. Conventional isotope ratio measurements on precipitated water from all stations of the network are well correlated as expected. However, Δ17O as well as dex is anticorrelated to these isotope ratio. The combination of these parameters allow to investigate dependencies on temperature, turbulence factor, and humidity of these values as well as to look into the importance and relative contributions of kinetic to equilibrium fractionations. We used published temperature dependent fractionation factors in combination with a simple Rayleigh model approach to investigate the importance of the meteorological parameters on the isotope ratios. A direct comparison of measured and modeled isotope ratios for primary (δ17O, δ18O and (δD) as well as secondary isotope parameters (Δ17O and dex) is shown.

Intensity Distribution of Partially Coherent Array Finite Airy Beams Propagating in Atmospheric Turbulence

Based on the extended Huygens–Fresnel integral and the Rytov phase structure function, the closed-form expression of a partially coherent array finite Airy beams (PCAFABs) cutting through the Kolmogorov atmospheric turbulence is derived in the space domain under the paraxial approximation. The characteristics of the PCAFABs evoluting in the atmospheric environment are investigated in detail on the basis of the derived wave propagation formulae. We mainly illustrate the intensity profile of this beam changed with the truncation parameter, coherence length, and turbulence factor at several cross sections of the atmospheric space by means of numerical figures. It is convinced that the present concept and derived conclusions will provide useful exploration for learning the optical properties of the PCAFABs transmitting in the atmospheric turbulence, especially for free-space optical communication area.

Novel approach to analytical modelling of steady-state heat transfer from the exterior of TEFC induction motors

The purpose of this paper is to propose a novel approach to analytical modelling of steady-state heat transfer from the exterior of totally enclosed fan-cooled induction motors. The proposed approach is based on the geometry simplification methods, energy balance equation, modified correlations for forced convection, the Stefan-Boltzmann law, air-flow velocity profiles, and turbulence factor models. To apply modified correlations for forced convection, the motor exterior is presented with surfaces of elementary 3-D shapes as well as the air-flow velocity profiles and turbulence factor models are introduced. The existing correlations for forced convection from a short horizontal cylinder and correlations for heat transfer from straight fins (as well as inter-fin surfaces) in axial air-flows are modified by introducing the Prandtl number to the appropriate power. The correlations for forced convection from straight fins and inter-fin surfaces are derived from the existing ones for combined heat transfer (due to forced convection and radiation) by using the forced-convection correlations for a single flat plate. Employing the proposed analytical approach, satisfactory agreement is obtained with experimental data from other studies.

An approximate estimation of velocity profiles and turbulence factor models for air-flows along the exterior of TEFC induction motors

Compared to a number of other existing correlations for heat transfer, the empirical correlations for forced convection from a short horizontal cylinder in axial air-flows usually do not involve the effects of changes in air-flow velocity and/or air-flow turbulence. Therefore, a common analysis of the heat transfer by using only one energy balance equation for entire outer surface of a solid is considered insufficient for induction motor applications because it fails to include aforementioned effects. This paper presents a novel, empirically-based methodology to estimate approximately the values of air-flow velocities and turbulence factors, that is, velocity profiles and turbulence factor models for stationary horizontal cylinders with and without fins (frame and two end-shields) in axial air-flows. These velocity profiles and turbulence factor models can then be used in analytical modelling of steady-state heat transfer from the exterior of totally enclosed fan-cooled induction motors.

Domain-Based Dynamic Ranking

In this chapter a domain based ranking methodology is proposed in cloud environment. Web pages from the cloud are clustered as ‘Primary Domain' and ‘Secondary Domain'. ‘Primary' domain Web pages are fetched based on the direct matching with the keywords. ‘Primary Domain' Web pages are ranked based on Relevancy Factor (RF) and Turbulence Factor (TF). ‘Secondary Domain' is constructed by Nearest Keywords and Similar Web pages. Nearest Keywords are the keywords similar to the matched keywords. Similar Web pages are the Web pages having Nearest Keywords. Matched Web pages of ‘Primary' and ‘Secondary' domain are ranked separately. A wide range of Web pages from the cloud would be available and ranked more efficiently by this proposed approach.

On turbulent separation in the flow past a bluff body

The basic model problem of separation as predicted by the time-mean boundary-layer equations is studied, with the Cebeci-Smith model for turbulent stresses. The changes between laminar and turbulent flow are investigated by means of a turbulence ‘factor’ which increases from zero for laminar flow to unity for the fully turbulent regime. With an attached-flow starting point, a small increase in the turbulence factor above zero is found to drive the separation singularity towards the trailing edge or rear stagnation point for flow past a circular cylinder, according to both computations and analysis. A separated-flow starting point is found to produce analogous behaviour for the separation point. These findings lead to the suggestion that large-scale separation need not occur at all in the fully turbulent regime at sufficiently high Reynolds number; instead, separation is of small scale, confined near the trailing edge. Comments on the generality of this suggestion are presented, along with some supporting evidence from other computations. Further, the small scale involved theoretically has values which seem reasonable in practical terms.

ENTRAINMENT DUE TO MEAN FLOW IN TWO-LAYERED FLUID

The entrainment phenomena have been investigated across an interface between two-layered stratified flow induced by wind shear stress. The velocities of mean flow, turbulence and entrainment have been measured under three different conditions of water surface by using a wind-wave tank. When the entrainment velocity ue is expressed on the basis of the turbulent quantities at the interface, the turbulent entrainment coefficient E ( = ue/u) is given by E = A-(egl/u2)-3I1 ( A = 0.7). Here Eg, u and 1 are the effective buoyancy, the turbulence intensity and the integral lengthscale of turbulence at the interface, respectively. This result coincides with the relationship of entrainment due to oscillating grid turbulence, in which the mean flow does not exist. When, for the practical purpose, the estimation of ue is made by using the mean velocity Um and the depth h of mixed layer, Em ( - Ue/Um ) = Am•(egh/Um 2)"3/2 is derived from the transformation of E = A-(egl/u2)-3/2. There holds Am = A-Tf between Am and Tf, Tf being a turbulence factor given by (u/Um)4•(1/h)-3/2. It has been found that this relationship is also valid in various types of two-layered stratified flows as well as the wind-induced two-layered flows.