Modal Analysis of Grid Connected Doubly-Fed Induction Generators

This paper presents the modal analysis of a gridconnected doubly fed induction generator (DFIG). The change in modal properties for different system parameters, operating points, and grid strengths are computed and observed. The results offer a better understanding of theDFIG intrinsic dynamics,which can also be useful for control design and model justification. Index Terms—Doubly fed induction generator, eigenvalue analysis, nonlinear dynamic model, small-signal stability.Published versio

Proton Decay and Related Processes in Unified Models with Gauged Baryon Number:

In unification models based on SU(15) or SU(16), baryon number is part of the gauge symmetry, broken spontaneously. In such models, we discuss various scenarios of important baryon number violating processes like proton decay and neutron-antineutron oscillation. Our analysis depends on the effective operator method, and covers many variations of symmetry breaking, including different intermediate groups and different Higgs boson content. We discuss processes mediated by gauge bosons and Higgs bosons parallely. We show how accidental global or discrete symmetries present in the full gauge invariant Lagrangian restrict baryon number violating processes in these models. In all cases, we find that baryon number violating interactions are sufficiently suppressed to allow grand unification at energies much lower than the usual $10^{16}$ GeV.Comment: (32 pages LATEX) [DOE-ER\,40757-022, CPP-93-22] {Small changes made and two references added. This version will appear in Phys. Rev. D

Gravitational decay of the Z-boson

We study the decay process of the Z boson to a photon and a graviton. The most general form of the on-shell amplitude, subject to the constraints due to the conservation of the electromagnetic and the energy-momentum tensor, is determined. The amplitude is expressed in terms of three form factors, two of which are CP-odd while one is CP-even. The latter, which is the only non-zero form factor at the one-loop level, is computed in the standard model and the decay rate is determined.Comment: 30 pages, Latex, uses Axodraw. (Some typographical errors corrected, and some references added in the new version.

Report on the 68-bus, 16-machine, 5-area system

The present report refers to a small-signal stability study carried over the 68-Bus, 16-Machine, 5-Area System and validated on a widely known software package: MATLAB-Simulink (ver. 2012b). The 68-bus system is a reduced order equivalent of the inter-connected New England test system (NETS) and New York power system (NYPS), with five geographical regions out of which NETS and NYPS are represented by a group of generators whereas, the power import from each of the three other neighboring areas are approximated by equivalent generator models. This report has the objective to show how the simulation of this system must be done using MATLAB in order to get results that are comparable (and exhibit a good match with respect to the electromechanical modes) with the ones obtained using other commercial software packages and presented on the PES Task Force website on Benchmark Systems for Stability Controls

Physical Properties of OSIRIS-REx Target Asteroid (101955) 1999 RQ36 derived from Herschel, ESO-VISIR and Spitzer observations

In September 2011, the Herschel Space Observatory performed an observation campaign with the PACS photometer observing the asteroid (101955) 1999 RQ36 in the far infrared. The Herschel observations were analysed, together with ESO VLT-VISIR and Spitzer-IRS data, by means of a thermophysical model in order to derive the physical properties of 1999 RQ36. We find the asteroid has an effective diameter in the range 480 to 511 m, a slightly elongated shape with a semi-major axis ratio of a/b=1.04, a geometric albedo of 0.045 +0.015/-0.012, and a retrograde rotation with a spin vector between -70 and -90 deg ecliptic latitude. The thermal emission at wavelengths below 12 micron -originating in the hot sub-solar region- shows that there may be large variations in roughness on the surface along the equatorial zone of 1999 RQ36, but further measurements are required for final proof. We determine that the asteroid has a disk-averaged thermal inertia of Gamma = 650 Jm-2s-0.5K-1 with a 3-sigma confidence range of 350 to 950 Jm-2s-0.5K-1, equivalent to what is observed for 25143 Itokawa and suggestive that 1999 RQ36 has a similar surface texture and may also be a rubble-pile in nature. The low albedo indicates that 1999 RQ36 very likely contains primitive volatile-rich material, consistent with its spectral type, and that it is an ideal target for the OSIRIS-REx sample return mission.Comment: Accepted for publication in Astronomy & Astrophysics, 9 pages, 7 figure

Effect of different spawn rates and substrate supplementation on yield of Indian Oyster mushroom, Pleurotus pulmonarius (Fr.) Quel.

A study was conducted to evaluate the effect of different spawn rates and substrate supplementation on yield of Pleurotus pulmonarius (Fr.) Quel. Among six spawn rates viz., 0.5%, 1%, 2%, 4%, 6% and 8%, respectively tried on wheat straw substrate, the spawn run was fastest (10.50 days) when spawn dose was 8%, followed by 6%, 4%, 2%, 1% and 0.5%, respectively. The pinheads appeared in 12.27 days by using spawn @ 8%, which proved to be the best spawn dose followed by 6%, 4%, 2%, 1% and 0.5%, respectively. Highest yield of 168.7 per 200g dry substrate was achieved @ 8% spawn rate. Lesser yields were recorded when spawn rate was reduced. The results also reveals the significantly highest biological efficiency of 84.33% at 8% spawn rate followed by 6%, 4%, 2%, 1% and 0.5%, respectively. It was concluded that spawn run was rapid at higher spawn rate but there was not much difference in yield when spawn dose was increased from 4 to 8%. Considering spawn cost and performance shown by different doses, 2-4% was found optimum dose for its cultivation.In case of substrate supplementation, wheat straw supplemented with cotton seed meal supported maximum mycelial growth (10.50 days of inoculation) and took mini-mum time for pinheads initiation (13.67 days). Similarly, maximum yield (155.3g) with biological efficiency of 77.65% was recorded on wheat straw supplemented with cotton seed meal followed by supplementation of saw dust, wheat straw (control), calcium ammonium nitrate (CAN), ammonium nitrateand urea, respectively. These studies will help to mushroom growers for selecting the most suitable spawn rate and also opens viable option of supplementation as wheat straw + cotton seed meal for better growth behaviour and optimum yield potential of Pleurotus pulmonarius as well as other oyster mushrooms cultivation

SU(16) grandunification: breaking scales, proton decay and neutrino magnetic moment

We give a detailed renormalization group analysis for the SU(16) grandunified group with general breaking chains in which quarks and leptons transform separately at intermediate energies. Our analysis includes the effects of Higgs bosons. We show that the grandunification scale could be as low as $\sim 10^{8.5}$ GeV and give examples where new physics could exist at relatively low energy ($\sim 250$ GeV). We consider proton decay in this model and show that it is consistent with a low grandunification scale. We also discuss the possible generation of a neutrino magnetic moment in the range of $10^{-11}$ to $10^{-10}\mu_B$ with a very small mass by the breaking of the embedded SU(2)$_\nu$ symmetry at a low energy.Comment: (16 pages in REVTEX + 6 figures not included) OITS-49

A Test System Model for Stability Studies of UK Power Grid

The paper presents a test system model to study the effect of variable wind power output on the stability of future power systems. The test system is built upon a future UK transmission system model and it contains different types of generators, HVDC transmission lines, and interconnections. A poorly damped inter-area mode is present in the test system that closely resembles the Scotland-England inter-area mode existing in the UK transmission system. The study system will help to analyze the impact of increased variability in power system operating conditions on the oscillatory mode. © 2013 IEEE

Charged particle rapidity distributions at RHIC

Using a multiphase transport model (AMPT), which includes both initial partonic and final hadronic scattering, we study the rapidity distributions of charged particles such as protons, antiprotons, pions and kaons in central Au+Au collisions at $\sqrt s$ = 56, 130, and 200 AGeV at RHIC. We find that present data at 56 and 130 AGeV by the PHOBOS collaboration are consistent with a rather weak jet quenching in the initial dense matter. We also find that the antiproton to proton ratio at mid-rapidity increases appreciably with $\sqrt s$, indicating the approach to a nearly baryon-antibaryon symmetric matter in high energy collisions. Furthermore, the $K^+/\pi^+$ ratio is almost constant within the energy range studied here, suggesting the approximate chemical equilibrium for strangeness production in these collisions