Thermocline Circulation Driven at Surface Outcrops of Isopycnal Surfaces

Potential vorticity (PV) defined as: q = Δθ .(fk + Ω) where θ is density anomaly, Ω (Δ x u) is relative vorticity, k is unit vertical vector and f the coriolis parameter, is used as a dynamical tracer to study the interior thermocline circulation. Using the generalized flux form of PV equation (Haynes and McIntyre, 1987), wind stress and buoyancy fluxes at surface outcrops of isopycnal surface are translated into PV fluxes. The PV flux condition so derived considers seasonal movement of the isopycnal outcrops and geostrophic turbulence. A constant layer depth model, forced by the above flux condition, is used to study its influence on the interior circulation. The impermeability theorem of Haynes and McIntyre (1987), justifies treatment of a single isopycnic layer in isolation. Non-linear, quasi-geostrophic equations are used to study the dynamics on a rectangular basin model. The model is forced by PV at the northern boundary of the domain, which represents the location where the PV flux enters the thermocline interior. PV input at the northern boundary allows the circulation to build up until opposite PV input at some other boundaries limits the process. The model simulation shows active northern, eastern and western boundary layers, and an interior circulation pattern with properties similar to those inferred by the homogenization theory of Rhines and Young (1982a). However, in the present study, the boundary layers control the key features of the circulation unlike in the classical models driven by Ekman pumping. The results show that the anticyclonic gyre forming in response to negative PV input on the northern boundary, has a strength depending on the intensity of the forcing, lateral diffusivity and the eastern boundary condition. In the case of an upwelled isopycnal (free slip eastern wall), the eastern boundary layer is stable and penetrates to a considerable distance south. On the contrary, for isopycnal intersecting the eastern boundary (no-slip wall), the eastern boundary layer separates at a short distance from the northeast corner, injecting massive amounts of positive vorticity into the basin. Cyclonic eddies are shed at a constant frequency near the eastern boundary, in the no-slip case, propagate towards the west and dissipate near the western boundary. Experiments with realistic subduction rates show that the PV transport due to the total pressure gradient along the isopycnal outcrop dwarfs the transport due to subduction. The results obtained mimic to a certain extent features of subtropical gyre circulation near eastern boundaries, notably in the Azores frontal area

Geographical distribution of typhoid risk factors in low and middle income countries

Overdispersion. Appendix 2. Full specification of regression outputs. Appendix 3. TRF index (type 5) by sub-national boundary. Appendix 4. Final TRF index values by sub-national boundary. Appendix 5. TRF index in Bangladesh. (ZIP 1995 kb

Three-dimensional flow measurements in a vaneless radial turbine scroll

The flow behavior in a vaneless radial turbine scroll was examined experimentally. The data was obtained using the slant sensor technique of hot film anemometry. This method used the unsymmetric heat transfer characteristics of a constant temperature hot film sensor to detect the flow direction and magnitude. This was achieved by obtaining a velocity vector measurement at three sensor positions with respect to the flow. The true magnitude and direction of the velocity vector was then found using these values and a Newton-Raphson numerical technique. The through flow and secondary flow velocity components are measured at various points in three scroll sections

Relation between outgoing longwave radiation and findlater jet over Arabian Sea during summer monsoon and influence on Indian monsoon rainfall

428-435This work analyses the relationship between outgoing Longwave radiation (OLR) and Findlater jet (FLJ) intensities at 850 hPa pressure level and also their relation with Indian summer monsoon rainfall (ISMR; June-September) for a period of 1997-2010 over Arabian Sea and India. FLJ is a low-level jet (LLJ) which can be observed during southwest monsoon months. This LLJ generally supports the large-scale moisture and momentum transport from ocean to atmosphere, which results in rainfall over India. FLJ and OLR are associated during the monsoon months. However FLJ (positively) and OLR (negatively) are related with ISMR. Monthly and seasonal correlation coefficients among FLJ, OLR and ISMR presented and the deviations during El Nino/La Nina are discussed. Based on this analysis we recommend that the variations in FLJ should include interannual variability in atmospheric dynamics

Use of fly ash admixed concrete for pavement construction

The portland cement used for construction of rigid pavements is an energy intensive material and hence efforts are being made to find substitute materials for partial replacement of cement in concrete, and conserve energy. On the other hand, utilisation of coal for generation of power is increasing rapidly. This has resulted in production of large quantities of fly ash from coal burning power plants. Fly ash from thermal power plants can be used as an admixture to concrete for saving cement as well as to provide solutions for its disposal problems. Use of fly ash in concrete would be an environmentally friendly way of utilising a waste material like fly ash. Currently fly ash finds application in road pavement structure,mainly for sub-base /base course and embankment. Fly ash admixed concrete can be a very good material for construction of pavement. It is generally designed as a partial replacement of cement or aggregate or both. This paper describes the different methods of using fly ash in concrete as a paving material, advantages gained by using fly ash in concrete and mechanism of durability increase in fly ash admixed concrete. The experiences of CRRI for using fly ash admixed concrete are also highlighted

Determination of generator groupings for an islanding scheme in the Manitoba Hydro system using the method of normal forms

This paper deals with the application of the method of normal forms in the analysis of a specific aspect of system dynamic behavior in the Manitoba Hydro system. Following a major loss of transmission capacity on the Manitoba Hydro HVDC system (Nelson River system), and the subsequent operation of protection systems, there is a major deficit of generation in the remaining system, comprising Manitoba and Saskatchewan. The method of normal forms is applied to determine the natural groupings which are formed by the machines in Manitoba Hydro due to nonlinear interaction. This grouping then provides a basis for developing a systematic procedure to island the remaining system.published_or_final_versio

Identification of genes differentially expressed between benign and osteopontin transformed rat mammary epithelial cells

<p>Abstract</p> <p>Background</p> <p>Osteopontin is a secreted, integrin-binding and phosphorylated acidic glycoprotein which has an important role in tumor progression.</p> <p>Findings</p> <p>In this study, we have utilized suppressive subtractive hybridization (SSH) to evaluate OPN regulated gene expression, using the Rama 37 benign non-invasive rat mammary cell line and a subclone, Rama 37-OPN. Rama 37-OPN was produced by stably transfecting Rama 37 with an OPN expression vector and it demonstrates increased malignant properties <it>in vitro</it>. Sequence and expression array analysis of the respective cDNA libraries of over 1600 subtracted cDNA fragments revealed 982 ESTs, 45 novel sequences and 659 known genes. The known up-regulated genes in the Rama 37-OPN library code for proteins with a variety of functions including those involved in metabolism, cell adhesion and migration, signal transduction and in apoptosis. Four of the most differentially expressed genes between the benign and <it>in vitro </it>malignant rat mammary cell lines are tumor protein translationally controlled I (TPTI), aryl hydrocarbon receptor nuclear translocator (ARNT), ataxia telangiectasia mutated (ATM) and RAN GTPase (RAN). The largest difference (ca 10,000 fold) between the less aggressively (MCF-7, ZR-75) and more aggressively malignant (MDA MB 231, MDA MB 435S) human breast cancer cell lines is that due to RAN, the next is that due to osteopontin itself.</p> <p>Conclusion</p> <p>The results suggest that enhanced properties associated with the malignant state <it>in vitro </it>induced by osteopontin may be due to, in part, overexpression of RAN GTPase and these biological results are the subject of a subsequent publication <abbrgrp><abbr bid="B1">1</abbr></abbrgrp>.</p

Inclusion of higher order terms for small-signal (modal) analysis: Committee report - task force on assessing the need to include higher order terms for small-signal (modal) analysis

© 2005 IEEE.This paper summarizes the work done by the Task Force on Assessing the Need to Include Higher Order Terms for Small-Signal (Modal) Analysis. This Task Force was created by the Power System Dynamic Performance Committee to investigate the need to include higher order terms for small signal (modal) analysis. The focus of the work reported here is on establishing and documenting the practical significance of these terms in stability analysis using the method of Normal Forms. Special emphasis was placed on determining and describing conditions when higher order terms need to be included to accurately describe modal interactions. Test cases were developed on a standard test system to demonstrate the application of appropriate indices to detect the occurrence of nonlinear interaction and hence the need for higher order terms in stability analyzes. The use of the higher order terms in the site selection for a damping controller is also documented.Sanchez-Gasca, Juan J.,Vittal, Vijay; Gibbard, Michael J.; Messina, Arturo Roman; Vowles, David J.; Liu, Shu; Annakkage, Udaya D

Transient Stability Test Systems for Direct Stability Methods

A standard set of power system data with benchmark results are presented against which direct stability techniques to assess transient stability can be compared and tested. The test systems have been selected to display a wide range of dynamic characteristics to provide a robust test of the efficacy and accuracy of the various analytical techniques to analyze transient stability. Transient stability test system data and benchmark results obtained from two commercially available time-domain stability analysis packages are presente