WD+MS Systems as the Progenitors of Type Ia Supernovae with Different Metallicities

The single-degenerate model for the progenitors of type Ia supernovae (SNe Ia) is one of the two most popular models, in which a carbon-oxygen white dwarf (CO WD) accretes hydrogen-rich material from its companion, increases its mass to the Chandrasekhar mass limit, and then explodes as a SN Ia. Incorporating the prescription of Hachisu et al. (1999a) for the accretion efficiency into Eggleton's stellar evolution code and assuming that the prescription is valid for \emph{all} metallicities, we carried out a detailed binary evolution study with different metallicities. We show the initial and final parameter space for SNe Ia in a ($\log P-M_{\rm 2}$) plane. The positions of some famous recurrent novae in the ($\log P-M_{\rm 2}$) plane, as well as a supersoft X-ray source (SSS), RX J0513.9-6951 are well explained by our model, and our model can also explain the space velocity and mass of Tycho G, which is now suggested to be the companion star of Tycho's supernova . Our study indicates that the SSS, V Sge, is a potential progenitor of supernovae like SN 2002ic if the delayed dynamical-instability model in Han & Podsiadlowski (2006) is appropriate.Comment: 10 pages, 12 figures, accepted for publication in PAS

Codes Cross-Correlation Impact on S-curve Bias and Data-Pilot Code Pairs Optimization for CBOC Signals

The aim of this paper is to analyze the impact of spreading codes cross-correlation on code tracking performance, and to optimize the data-pilot code pairs of Galileo E1 Open Service (OS) Composite Binary Offset Carrier (CBOC) signals. The distortion of the discriminator function (i.e., S-curve), due to data and pilot spreading codes cross-correlation properties, is evaluated when only the data or pilot components of CBOC signals are tracked, considering the features of the modulation schemes. Analyses show that the S-curve bias also depends on the receiver configuration (e.g., the tracking algorithm and correlator spacing). In this paper, two methods are proposed to optimize the data-pilot code pairs of Galileo E1 OS. The optimization goal is to obtain minimum average S-curve biases when tracking only the pilot components of CBOC signals for the specific correlator spacing. The S-curve biases after optimization processes are analyzed and compared with the un-optimized results. It is shown that the optimized data-pilot code pairs could significantly mitigate the intra-channel (i.e., data and pilot) codes cross-correlation，and then improve the code tracking performance of CBOC signals

Joint Probabilistic Data Association-Feedback Particle Filter for Multiple Target Tracking Applications

This paper introduces a novel feedback-control based particle filter for the solution of the filtering problem with data association uncertainty. The particle filter is referred to as the joint probabilistic data association-feedback particle filter (JPDA-FPF). The JPDA-FPF is based on the feedback particle filter introduced in our earlier papers. The remarkable conclusion of our paper is that the JPDA-FPF algorithm retains the innovation error-based feedback structure of the feedback particle filter, even with data association uncertainty in the general nonlinear case. The theoretical results are illustrated with the aid of two numerical example problems drawn from multiple target tracking applications.Comment: In Proc. of the 2012 American Control Conferenc

Cascade Protector for Hardening Electronic Devices against High Power Microwaves

Since the increasing front part of incident microwave pulses may pass through plasma limiter before it generates plasma (the breakdown time of low pressure Xe in plasma limiter is 10 ns), single plasma limiters are not adequate for protecting sensitive electronic components against high power microwaves (HPM). A cascade protector, which consists of a plasma limiter and a PIN limiter in waveguide, is proposed. The numerical results show that under HPM attack (10 GW, 1GHz, and 100 ns pulse width), the microwave power leakage through the cascade protector is about 0.4 W. In the same electromagnetic environment, the power leakage through single plasma limiter is approximate 347 W.Defence Science Journal, 2009, 59(1), pp.55-57, DOI:http://dx.doi.org/10.14429/dsj.59.148