2,568 research outputs found
Cold HI in faint dwarf galaxies
We present the results of a study of the amount and distribution of cold
atomic gas, as well its correlation with recent star formation in a sample of
extremely faint dwarf irregular galaxies. Our sample is drawn from the Faint
Irregular Galaxy GMRT Survey (FIGGS) and its extension, FIGGS2. We use two
different methods to identify cold atomic gas. In the first method,
line-of-sight HI spectra were decomposed into multiple Gaussian components and
narrow Gaussian components were identified as cold HI. In the second method,
the brightness temperature (T_B) is used as a tracer of cold HI. We find that
the amount of cold gas identified using the T_B method is significantly larger
than the amount of gas identified using Gaussian decomposition. We also find
that a large fraction of the cold gas identified using the T_B method is
spatially coincident with regions of recent star formation, although the
converse is not true. That is only a small fraction of the regions with recent
star formation are also covered by cold gas. For regions where the star
formation and the cold gas overlap, we study the relationship between the star
formation rate density and the cold \HI column density. We find that the star
formation rate density has a power law dependence on the HI column density, but
that the slope of this power law is significantly flatter than that of the
canonical Kennicutt-Schmidt relation.Comment: Accepted for publication in MNRA
Leptogenesis bound on neutrino masses in left-right symmetric models with spontaneous D-parity violation
We study the baryogenesis via leptogenesis in a class of left-right symmetric
models, in which -parity is broken spontaneously. We first discuss the
consequence of the spontaneous -parity breaking on the neutrino masses. Than
we study the lepton asymmetry in various cases, from the decay of right handed
neutrino as well as the triplet Higgs, depending on their relative masses they
acquire from the symmetry breaking pattern. The leptogenesis bound on their
masses are discussed by taking into account the low energy neutrino oscillation
data. It is shown that a TeV scale leptogenesis is viable if there are
additional sources of CP violation like domain wall originating from the
spontaneous -parity violation.Comment: 32 pages (revtex), 12 eps figures, clarifications are added in
  section VII, A new section VIII is added, useful references are added.
  Journal version, To appear in Phys. Rev. 
Neural Modeling and Control of Diesel Engine with Pollution Constraints
The paper describes a neural approach for modelling and control of a
turbocharged Diesel engine. A neural model, whose structure is mainly based on
some physical equations describing the engine behaviour, is built for the
rotation speed and the exhaust gas opacity. The model is composed of three
interconnected neural submodels, each of them constituting a nonlinear
multi-input single-output error model. The structural identification and the
parameter estimation from data gathered on a real engine are described. The
neural direct model is then used to determine a neural controller of the
engine, in a specialized training scheme minimising a multivariable criterion.
Simulations show the effect of the pollution constraint weighting on a
trajectory tracking of the engine speed. Neural networks, which are flexible
and parsimonious nonlinear black-box models, with universal approximation
capabilities, can accurately describe or control complex nonlinear systems,
with little a priori theoretical knowledge. The presented work extends optimal
neuro-control to the multivariable case and shows the flexibility of neural
optimisers. Considering the preliminary results, it appears that neural
networks can be used as embedded models for engine control, to satisfy the more
and more restricting pollutant emission legislation. Particularly, they are
able to model nonlinear dynamics and outperform during transients the control
schemes based on static mappings.Comment: 15 page
LOW ALTITUDE AIRSHIPS FOR SEAMLESS MOBILE COMMUNICATION IN AIR TRAVEL
The Aviation Administration policy prohibits the use of mobile phones in Aircraft during transition for the reason it may harm their communication system due to Electromagnetic interference. In case the user wants to access cellular network at higher altitudes, base station
access is a problem. Large number of channels are allocated to a single user moving at high speed by various Base Stations in the vicinity to service the request requiring more resources. Low Altitude Platforms (LAPs) are provided in the form of Base stations in the Airships with antennas projected upwards which has direct link with the Ground Station. LAPs using LongEndurance
Multi-Intelligence Vehicle (LEMVs) equipped with an engine for mobility and stable positioning against rough winds are utilized. This paper proposes a system that allows the passengers to use their mobiles in Aircraft using LAPs as an intermediate system between
Aircraft and Ground station. As the Aircraft is dynamic, it has to change its link frequently with the Airships, MANETs using AODV protocol is established in the prototype using NS2 to provide the service and the results are encouraging
Effect of different modes of pollination on yield parameters of summer squash (Cucurbita pepo L.) in India
Effect of different modes of pollination, viz., without insect pollination, hand-pollination, open-pollination and open-pollination + hand-pollination on yield parameters of 4 summer squash (Cucurbita pepo L.) hybrids viz., Parikrama, Chandra, Chamatkar and Gold Queen was studied at Research Farm of the Department of Entomology, CCS Haryana Agricultural University, Hisar during 2014. Irrespective of different hybrids, the treatment openpollination + hand-pollination and open-pollination produced the maximum number of fruits per plant (73.50 and 71.25%, respectively) followed by hand-pollination (59.08%) and no fruits were observed (0% fruit set) under without insect pollination treatment. Average fruit weight, fruit polar diameter and equatorial diameter were maximum (135.30 g, 3.74 cm and 3.47 cm, respectively) under open-pollination + hand-pollination, while these were minimum (94.81 cm, 2.14cm and 2.48 cm, respectively) under hand-pollination treatment. These results indicate that honey bees as well as wild pollinators are utmost essential for pollination of summer squash flowers and thus increasing fruit size and yield. Therefore pollinators conservation practices should be followed in summer squash growing areas for getting higher yield and returns
Inflation in minimal left-right symmetric model with spontaneous D-parity breaking
We present a simplest inflationary scenario in the minimal left-right
symmetric model with spontaneous D-parity breaking, which is a well motivated
particle physics model for neutrino masses. This leads us to connect the
observed anisotropies in the cosmic microwave background to the sub-eV neutrino
masses. The baryon asymmetry via the leptogenesis route is also discussed
briefly.Comment: (v1) 4 pages, 1 figure; (v2) typos corrected; (v3) title and abstract
  changed, numerical estimates given, minor changes; (v4) 5 pages, relations
  between the neutrino masses and the CMB fluctuations become more explicit,
  miscellaneous changes, to appear in Physical Review 
Dynamic Adaptive Control of Mobile Robot UsingRBF Networks
In this paper, an adaptive neuro-control systemwith two levels is proposed for the motion control of anonholonomic mobile robot. In the first level, a PD controller is designed to generate linear and angular velocities, necessary to tracka reference trajectory. In the second level, a neural network converts the desired velocities, provided by the first level, intoa torque control. The advantage of the control approach is that, no knowledge about the dynamic model is required, and no synaptic weight changing is needed in presence of robot’s parameter’s variation (mass or inertia).By introducing appropriate Lyapunovfunctions asymptotic stability of state variables and stability of system is guaranteed. The tracking performance of neural controller under disturbances is compared with PD controller. Sinusoidal trajectory and lamniscate trajectories are considered for this comparison
Z(2)-Singlino Dark Matter in a Portal-Like Extension of the Minimal Supersymmetric Standard Model.
We propose a Z2-stabilized singlino () as a dark matter candidate in extended and R-parity violating versions of the supersymmetric standard model. interacts with visible matter via a heavy messenger field S, which results in a supersymmetric version of the Higgs portal interaction. The relic abundance of can account for cold dark matter if the messenger mass satisfies GeV. Our model can be implemented in many realistic supersymmetric models such as the next-to-minimal supersymmetric (SUSY) standard model and nearly minimal SUSY standard model
Decentralized multi-tasks distribution in heterogeneous robot teams by means of ant colony optimization and learning automata
This paper focuses on the general problem of coordinating
multiple robots. More specifically, it addresses the self-election of heterogeneous specialized tasks by autonomous robots. In this paper we focus on a specifically distributed or decentralized approach as we are particularly
interested on decentralized solution where the robots themselves autonomously and in an individual manner, are responsible of selecting a particular task so that all the existing tasks are optimally distributed and executed. In this regard, we have established an experimental scenario to solve the corresponding multi-tasks distribution problem and we propose a solution using two different approaches by applying Ant Colony Optimization-based deterministic algorithms as well as Learning Automata-based probabilistic algorithms. We have evaluated the robustness of the algorithm, perturbing the number of pending loads to simulate the robot’s error in estimating the real number of pending tasks and also the dynamic generation of loads through time. The paper ends with a critical discussion of experimental results
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