Gravitational resonances on f(R)f(R)-brane

In this paper, we investigate various $f(R)$-brane models and compare their gravitational resonance structures with the corresponding general relativity (GR)-branes. {Starting from some known GR-brane solutions}, we derive thick $f(R)$-brane solutions such that the metric, scalar field, and scalar potential coincide with those of the corresponding GR-branes. {We find that for branes generated by a single or several canonical scalar fields, there is no obvious distinction between the GR-branes and corresponding $f(R)$-branes in terms of gravitational resonance structure.} Then we discuss the branes generated by K-fields. In this case, there could exist huge differences between GR-branes and $f(R)$-branes.Comment: 17 pages, 14 figures, published versio

The structure of f(R)f(R)-brane model

Recently, a family of interesting analytical brane solutions were found in $f(R)$ gravity with $f(R)=R+\alpha R^2$ in Ref. [Phys. Lett. B 729, 127 (2014)]. In these solutions, inner brane structure can be turned on by tuning the value of the parameter $\alpha$. In this paper, we investigate how the parameter $\alpha$ affects the localization and the quasilocalization of the tensorial gravitons around these solutions. It is found that, in a range of $\alpha$, despite the brane has an inner structure, there is no graviton resonance. However, in some other regions of the parameter space, although the brane has no internal structure, the effective potential for the graviton KK modes has a singular structure, and there exists a series of graviton resonant modes. The contribution of the massive graviton KK modes to the Newton's law of gravity is discussed shortly.Comment: v2: 10 pages, 8 figures, to be published in EPJ

Joint Power Splitting and Secure Beamforming Design in the Wireless-powered Untrusted Relay Networks

In this work, we maximize the secrecy rate of the wireless-powered untrusted relay network by jointly designing power splitting (PS) ratio and relay beamforming with the proposed global optimal algorithm (GOA) and local optimal algorithm (LOA). Different from the literature, artificial noise (AN) sent by the destination not only degrades the channel condition of the eavesdropper to improve the secrecy rate, but also becomes a new source of energy powering the untrusted relay based on PS. Hence, it is of high economic benefits and efficiency to take advantage of AN compared with the literature. Simulation results show that LOA can achieve satisfactory secrecy rate performance compared with that of GOA, but with less computation time.Comment: Submitted to GlobeCom201

Phenomenological relationship between eccentric and quasi-circular orbital binary black hole waveform

Eccentricity, an important parameter of gravitational waves, has been paid more and more attention because it can reflect the dynamics of compact object mergers. Obtaining an accurate and fast gravitational waveform template is of great significance for the estimation of gravitational wave parameters. This paper aims to do an extended study of the phenomenological fitting model proposed by Setyawati and Ohme for adding eccentricity to quasi-circular orbital waveforms. It can be applied to higher eccentricity up to e = 0.4. But the higher the eccentricity, the less the accuracy. For e in [0, 0.1], it gives an overlap of more than 99.99%. For e in [0.1, 0.2], it gives an overlap of more than 99.9%. For e in [0.2, 0.3], it gives an overlap of more than 99%. For e in [0.3, 0.4], it gives an overlap of more than 90%. The reason for these phenomena is that the larger the eccentricity, the larger the deviation of the eccentricity estimator from the cosine function due to the large change in the morphology of the eccentric waveform, and the worse the fitting effect of the model. It can be applied to higher-order modes and gives the same overlap behavior. After adding a shift parameter, it can be applied to spin-aligned or spin-antialigned waveforms. After obtaining spin-precessing effect, it can be applied to the spin-precessing case. In summary, non-spining, spin-aligned, spin-antialigned or spin-precessing waveforms with eccentricity can be constructed from quasi-circular non-spining waveforms by the phenomenological model, which is not only helpful for us to quickly construct phenomenological gravitational wave templates, but also reveals a phenomenological and universal relationship between eccentric waveform and quasi-circular orbital waveform.Comment: 19 pages, 18 figure