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Accurately localizing multiple sources is a critical task with various applications in wireless communications, such as emergency services including natural post-disaster search and rescue operations. However, the scenarios where the receiver is moving, are not addressed by recent studies. This paper tackles the angle of arrival (AOA) 3D-localization problem for multiple sparse signal sources with a moving receiver having limited antennas, potentially outnumbered by the sources. First, an energy detector algorithm is proposed to exploit the sparsity of the signal to eliminate the noisy samples of the signals. Subsequently, elevation and azimuth AOAs of sources are roughly estimated using two dimensional multiple signal classification (2D-MUSIC) method. Next, an algorithm is proposed to refine and estimate the elevation and azimuth AOAs more accurately. To this end, we propose a sparse recovery algorithm to exploit the sparsity feature of the signals. Then, we propose a phase smoothing algorithm to refine the estimations in the output of sparse recovery algorithm. Finally, K-SVD algorithm is employed to find the accurate elevation and azimuth AOAs of sources. For localization, a new multi-source 3D-localization algorithm is proposed to estimate the positions of sources in a sequence of time windows. Extensive simulations are carried out to demonstrate the effectiveness of the proposed framework.

The main properties of the logamediate inflation driven by a non-canonical scalar field in the framework of DGP braneworld gravity are investigated. Considering high energy conditions we calculate the slow-roll parameters, analytically. Then, we deal with the perturbation theory and calculate the most important respective parameters such as the scalar spectral index and the tensor-to-scalar ratio. We find that the spectrum of scalar fluctuations is always red-tilted. Also, we understand that the running in the scalar spectral index is nearly zero. Finally, we compare this inflationary scenario with the latest observational results from Planck 2018.

In this article we study a constant-roll inflationary model in the context of the DGP brane-world cosmology caused by a quintessence scalar field. We determine an analytical solution for the Friedman equation coupled to the equation of motion of the scaler field. The evolution of the primordial scalar and tensor perturbations is also studied. To check the viability of the model we use numerical approaches and plot some figures. Our results for the scalar spectral index and the tensor to scaler ratio show good consistency with observations for given values of model parameters., Comment: arXiv admin note: text overlap with arXiv:2201.02666

In this article we study a constant-roll inflationary model in the context of brane-world cosmology caused by a quintessence scalar field for warm inflation with a constant dissipative parameter Q =$\Gamma$/3H. We determine the analytical solution for the Friedman equation coupled to the equation of motion of the scaler field. The evolution of the primordial scalar and tensor perturbations is also studied using the modified Langevin equation. To check the viability of the model we use numerical approaches and plot some figures. Our results for the scalar spectral index and the tensor to scaler ratio show good consistency with observations.

Multi-agent interaction is a fundamental aspect of autonomous driving in the real world. Despite more than a decade of research and development, the problem of how to competently interact with diverse road users in diverse scenarios remains largely unsolved. Learning methods have much to offer towards solving this problem. But they require a realistic multi-agent simulator that generates diverse and competent driving interactions. To meet this need, we develop a dedicated simulation platform called SMARTS (Scalable Multi-Agent RL Training School). SMARTS supports the training, accumulation, and use of diverse behavior models of road users. These are in turn used to create increasingly more realistic and diverse interactions that enable deeper and broader research on multi-agent interaction. In this paper, we describe the design goals of SMARTS, explain its basic architecture and its key features, and illustrate its use through concrete multi-agent experiments on interactive scenarios. We open-source the SMARTS platform and the associated benchmark tasks and evaluation metrics to encourage and empower research on multi-agent learning for autonomous driving. Our code is available at https://github.com/huawei-noah/SMARTS., Comment: 20 pages, 11 figures. Paper accepted to CoRL 2020

In this manuscript we use the dynamical system approach to study the linear dynamics of a Randall-Sundrum braneworld model with a tachyon scalar field confined to the brane. We recognize that the form of the tachyon potential plays a significant role in the evolution of the universe. For the case of an inverse square potential we find that one of our new variables, $\lambda$, is constant. We obtain critical points of the system in this situation and investigate their stability using the linear perturbation method. Then we turn to a Gaussian potential in which $\lambda$ is not constant. Using the idea of instantaneous critical points we study the behavior of the universe and its possible fates. One of the interesting results of this manuscript is that our universe will probably experience another phase transition from acceleration to deceleration in the future.

In this paper, we consider a normal branch of the DGP cosmological model with a quintessence scalar field on the brane as the dark energy component. Using the dynamical system approach, we study the stability properties of the model. We find that {\lambda}, as one of our new dimensionless variables which is defined in terms of the quintessence potential, has a crucial role in the history of the universe. We divide our discussion into two parts: a constant {\lambda} and a varying {\lambda}. In the case of a constant {\lambda}, we calculate all the critical points of the model even those at infinity and then assume all of them as instantaneous critical points in the varying {\lambda} situation which is the main part of this paper. We find that the effect of the extra dimension in such a model is independent of the value of {\lambda}. Then, we consider a Gaussian potential for which {\lambda} is not constant but varies from zero to infinity. We discuss the evolution of the dynamical variables of the model and conclude that their asymptotic behaviors follow the trajectories of the moving critical points. Also, we find two different possible fates for the universe. In one of them, it could experience an accelerated expansion, but then enters a decelerating phase and finally reaches a stable matter-dominated solution. In the other scenario, the universe could approach the matter-dominated critical point without experiencing any accelerated expansion. We argue that the first scenario is more compatible with observations.

A proposal to study the effect of interaction in an agegraphic dark energy model in DGP brane-world cosmology is presented in this manuscript. After explaining the details, we proceed to apply the dynamical system approach to the model to analyze its stability. We first, constrain model parameters with a variety of independent observational data such as cosmic microwave background anisotropies, baryon acoustic oscillation peaks and observational Hubble data. Then, we obtain the critical points related to different cosmological epochs. In particular, we conclude that in the presence of interaction, dark energy dominated era could be a stable point if model parameters $n$ and $\beta$, obey a given constraint. Also, big rip singularity is avoidable in this model.

In this manuscript we use the dynamical system approach to study the linear dynamics of a normal DGP brane-world model with a tachyon field as the dark energy component. Our focus is on a Gaussian tachyonic potential in which the parameter $\lambda=-V_\phi/V^{3/2}$, goes to infinity. One of the most important results of this study is that we find critical submanifolds which indicate the effect of extra dimension.

In this paper we study continuous time adaptive extremum localization of an arbitrary quadratic function $F(\cdot)$ based on Hessian estimation, using measured the signal intensity by a sensory agent. The function $F(\cdot)$ represents a signal field as a result of a source located at the maximum point of $F(\cdot)$ and is decreasing as moving away from the source location. Stability of the proposed adaptive estimation and localization scheme is analyzed and the Hessian parameter and location estimates are shown to asymptotically converge to the true values. Moreover, the stability and convergence properties of algorithm are shown to be robust to drift in the extremum location. Simulation test results are displayed to verify the established properties of the proposed scheme as well as robustness to signal measurement noise.

The aim of this work is to apply the dynamical system approach to study the linear dynamics of the normal DGP brane-world model with agegraphic dark energy. The stability analysis of the model will be investigated and the phase plane portrait will be illustrated. The nature of critical points will be analyzed by evaluating the eigenvalues of a linearized Jacobi matrix. Also, the statefinder diagnostic procedure will be applied to show the slight deviation from the {\Lambda}CDM model. One of the most interesting results of this work is the great alleviation of the coincidence problem.

Applications of Discrete Fracture Network (DFN) modeling are becoming increasingly prevalent in engineering analyses involving fractured rock masses. For example, kinematic evaluations of slope or underground excavation stability and the modeling of fluid flow in fractured rock have been shown to benefit significantly from the explicit representation of DFN realizations in the simulations. In practice, due to high computing costs, namely time, a balance must be struck that limits analyses to the consideration of only a few realizations as input. As a stochastic representation, a single realization is only one possibility. It is therefore critical that the selected realizations (possibilities) are able to summarize the range of variations present in the input parameters adequately for the purpose of study or practice. That is, the significance of diversity (dissimilarity) in the generated fracture networks is of great importance and should be assessed prior to further often time-consuming processing stages. We demonstrate here a novel development in the analysis of the similarity between three-dimensional fracture networks, which provides an accurate, efficient and practical solution with comprehensive coverage of model variations. Several examples are presented together with a comparison between the proposed three-dimensional method and existing methods limited to two-dimensional assumptions. It is shown that the two-dimensional similarity methods despite their popularity are heavily biased and poorly represent the reality., Comment: 20 pages, 14 figures, original research

The varying speed of light (VSL) has been used in cosmological models in which the physical constants vary over time. On the other hand, the Dvali, Gabadadze and Porrati (DGP) brane world model, especially its normal branch has been extensively discussed to justify the current cosmic acceleration. In this article we show that the normal branch of DGP in VSL cosmology leads to a self-accelerating behavior and therefore can interpret cosmic acceleration. Applying statefinder diagnostics demonstrate that our result slightly deviates {\Lambda}CDM model.

In this article we study cosmic dynamics in the context of normal branch of DGP braneworld model. Using the current Planck data, we best fit the model and cosmological parameters in non-flat $\Lambda$DGP. With the transition redshift as a basic variable and statefinder parameters, our result shows that the Universe starts its accelerated expansion phase, slightly earlier than expected in $\Lambda$CDM cosmology. The result also alleviates the coincidence problem of the $\Lambda$CDM model.

A proposal to study the original and new agegraphic dark energy in DGP braneworld cosmology is presented in this work. To verify our model with the observational data, the model is constrained by a variety of independent measurements such as Hubble parameter, cosmic microwave background anisotropies, and baryon acoustic oscillation peaks. The best fitting procedure shows the effectiveness of agegraphic parameter $n$ in distinguishing between the original and new agegraphic dark energy scenarios and subsequent cosmological findings. In particular, the result shows that in both scenarios, our universe enters an agegraphic dark energy dominated phase., Comment: With little modifications in the text with respect to the published version

In this article we study an intermediate inflationary model in the context of Dvali-Gabadadze-Porrati (DGP) cosmology caused by a tachyon scalar field. Considering slow-roll inflation we discuss the dynamics of the Universe. Using perturbation theory, we estimate some of the model parameters numerically and compare them with the recent results from Planck satellite.

Scalar-field dark energy models for tachyon fields are often regarded as an effective description of an underlying theory of dark energy. In this paper, we propose the agegraphic dark energy model in tachyon cosmology by interaction between the components of the dark sectors. In the formalism, the interaction term emerges from the tachyon field nonminimally coupled to the matter Lagrangian in the model rather than being inserted into the formalism as an external source. The model is constrained by the observational data. Based on the best fitted parameters in both original and new agegraphic dark energy scenarios, the model is tested by Sne Ia data. The tachyon potential and tachyon field are reconstructed and coincidence problem is revisited., Comment: 11 pages, 10 figures. Published in PLB (contains some changes in the text with respect to the first version); arXiv admin note: text overlap with arXiv:1106.2659 by same authors

We propose in this paper an interacting holographic dark energy (IHDE) model in chameleon--tachyon cosmology by interaction between the components of the dark sectors. In the formalism, the interaction term emerges from the scalar field coupling matter lagrangian in the model rather than being inserted into the formalism as an external source for the interaction. The correspondence between the tachyon field and the holographic dark energy (HDE) densities allows to reconstruct the tachyon scalar field and its potential in a flat FRW universe. The model can show the accelerated expansion of the universe and satisfies the observational data., Comment: 12 pages, 12 figures; will be published in Astrophys. Space Sci

Recently, the tachyon cosmology has been represented as dark energy model to support the current acceleration of the universe without phantom crossing. In this paper, we study the dynamics of the tachyon cosmology in which the field plays the role of tachyon field and also non--minimally coupled to the matter lagrangian. The model shows current universe acceleration and also phantom crossing in the future. Two cosmological tests are also performed to validate the model; the difference in the distance modulus and the model independent Cosmological Redshift Drift (CRD) test., Comment: 14 pages, 11 figures