D2S: Representing local descriptors and global scene coordinates for camera relocalization

State-of-the-art visual localization methods mostly rely on complex procedures to match local descriptors and 3D point clouds. However, these procedures can incur significant cost in terms of inference, storage, and updates over time. In this study, we propose a direct learning-based approach that utilizes a simple network named D2S to represent local descriptors and their scene coordinates. Our method is characterized by its simplicity and cost-effectiveness. It solely leverages a single RGB image for localization during the testing phase and only requires a lightweight model to encode a complex sparse scene. The proposed D2S employs a combination of a simple loss function and graph attention to selectively focus on robust descriptors while disregarding areas such as clouds, trees, and several dynamic objects. This selective attention enables D2S to effectively perform a binary-semantic classification for sparse descriptors. Additionally, we propose a new outdoor dataset to evaluate the capabilities of visual localization methods in terms of scene generalization and self-updating from unlabeled observations. Our approach outperforms the state-of-the-art CNN-based methods in scene coordinate regression in indoor and outdoor environments. It demonstrates the ability to generalize beyond training data, including scenarios involving transitions from day to night and adapting to domain shifts, even in the absence of the labeled data sources. The source code, trained models, dataset, and demo videos are available at the following link: https://thpjp.github.io/d2

Two Spot Coupled Ring Resonators

Abstract. We consider a model of two coupled ring waveguides with constant linear gain and nonlinear absorption with space-dependent coupling. This system can be implemented in various physical situations as optical waveguides, atomic Bose-Einstein condensates, polarization condensates, etc. It is described by two coupled nonlinear Schrödinger equation. For numerical simulations, we take local two-gaussian coupling.It is found in our previous papers that, depending on the values of involved parameters, we can obtain several interesting nonlinear phenomena, which include spontaneous symmetry breaking, modulational instability leading to generation of stable circular flows with various vorticities, stable inhomogeneous states with interesting structure of currents flowing between rings, as well as dynamical regimes having signatures of chaotic behavior. This research will be associated with experimental investigation planned in Freie Universität Berlin, in the group of prof. Michael Giersig

Spontaneous Symmetry Breaking of Solitons Trapped in a Double-Gauss Potentials

We consider an extended model of the model considered before with double-square potential, namely one-dimensional (1D) nonlinear Schrödinger equation (NLSE) with self-focusing nonlinearity and a 1D double-gauss potential. Spontaneous symmetry breaking has been presented in terms of the control parameter which is propagation constant in the case of optics and chemical potential in the of Bose-Einstein Condensate (BEC), correspondingly. The numerical simulations predict a bifurcation breaking the symmetry of 1D trapped in the double-gauss potential of the supercritical type as in the case of double-square potential. Furthermore we have constructed bifurcation diagrams considering the stability of solitons with three methods: the method using Vakhitov–Kolokolov (V-K) Stability Criterion, Pseudospectral Method and Method for Linear-Stability Eigenvalues. It will be shown that for our model the results obtained are the same for these three methods but the third one is the fastest

PRESENT DAY DEFORMATION IN THE EAST VIETNAM SEA AND SURROUNDING REGIONS

This paper presents velocities of present-day tectonic movement and strain rate in the East Vietnam Sea (South China Sea) and surroundings determined from GPS campaigns between 2007 and 2010. We determine absolute velocities of GPS stations in the ITRF05 frame. The result indicates that GPS stations in the North of East Vietnam Sea move eastwards with the slip rate of 30 - 39 mm/yr, southwards at the velocities of 8 - 11 mm/yr. Song Tu Tay offshore moves eastwards at the rate of ~24 mm/yr and southwards at ~9 mm/yr. GPS stations in the South of East Vietnam Sea move to the east at the rate of ~22 mm/yr and to the south at the velocities of 7 - 11 mm/yr. The effect of relative movement shows that the Western Margin Fault Zone activates as left lateral fault zone at the slip rate less than 4 mm/year.In Western plateau, the first result from 2012 - 2013 GPS measurement shows that the velocities to the east vary from 21.5 mm/yr to 24.7 mm/year. The velocities to the south vary from 10.5 mm/yr to 14.6 mm/year. GPS solutions determined from our campaigns are combined with data from various authors and international projects to determine the strain rate in the East Vietnam Sea. Principal strain rate changes from 15 nanostrain/yr to 9 nanostrain/yr in the East Vietnam Sea. Principal strain rate and maximum shear strain rate along the Red River Fault Zone are in order of 10 nanostrain/year. East Vietnam Sea is considered to belong to the Sunda block

Bulk Incorporation with 4‐Methylphenethylammonium Chloride for Efficient and Stable Methylammonium‐Free Perovskite and Perovskite‐Silicon Tandem Solar Cells

Methylammonium (MA)-free perovskite solar cells have the potential for better thermal stability than their MA-containing counterparts. However, the efficiency of MA-free perovskite solar cells lags behind due to inferior bulk quality. In this work, 4-methylphenethylammonium chloride (4M-PEACl) is added into a MA-free perovskite precursor, which results in greatly enhanced bulk quality. The perovskite crystal grains are significantly enlarged, and defects are suppressed by a factor of four upon the incorporation of an optimal concentration of 4M-PEACl. Quasi-2D perovskites are formed and passivate defects at the grain boundaries of the perovskite crystals. Furthermore, the perovskite surface chemistry is modified, resulting in surface energies more favorable for hole extraction. This facile approach leads to a steady state efficiency of 23.7% (24.2% in reverse scan, 23.0% in forward scan) for MA-free perovskite solar cells. The devices also show excellent light stability, retaining more than 93% of the initial efficiency after 1000 h of constant illumination in a nitrogen environment. In addition, a four-terminal mechanically stacked perovskite-silicon tandem solar cell with champion efficiency of 30.3% is obtained using this MA-free composition. The encapsulated tandem devices show excellent operational stability, retaining more than 98% of the initial performance after 42 day/night cycles in an ambient atmosphere

Electromagnetically induced transparency for a double Fano-profile system

A Λ-like model of atomic levels involving two auto-ionizing states is considered. The levels are irradiated by two external electromagnetic fields, a strong driving and a weak probing ones. The analytical formula for medium susceptibility shows an additional electromagnetically induced transparency window caused by the second auto-ionizing level. Characteristics of both transparency windows are analyzed depending on parameters of auto-ionizing levels and the external driving field. Manipulation of these characteristics seems to be very effective because of their large sensitivity with respect to the parameters involved in the problem. This manipulation becomes even more feasible when considered model is implemented in so-called laser-induced continuum structure

Self-powered wireless two-way relaying networks: model and throughput performance with three practical schemes

In this paper, we analyse the throughput performance for two, three and four time slot transmission schemes, (2TS, 3TS and 4TS) for two-way amplify-and-forward relaying networks, in which we use RF signal for the energy harvesting (EH) enabled relay node to assist the exchange of information. Most importantly, we derive expression for delay-limited throughput and the approximate expressions for outage probability, and we also compare these results in case of EH and non-EH. Additionally, the trade-off between the distance allocation between source to relay, and relay to destination is comprehensively investigated, in which the large scale path loss is considered to obtain the optimal throughput. Thanks to the numerical results, we consider a scenario in each scheme, where the throughput of 2TS is higher regardless of values of power splitting coefficients compared to other two schemes. Numerical results provide an interesting trade-off between the considered EH parameters in the system design, and reveal the improvement of bandwidth and power efficiency. The proposed schemes confirm that the appropriate placement of nodes can help achieve low outage probability and optimal throughput.Web of Science97163161

Imperfect channel state information of AF and DF energy harvesting cooperative networks

Wireless information and powered transfer networks (WIPT) has recently been implemented in 5th generation wireless networks. In this paper, we consider half-duplex relaying system in which the energy constrained relay node collects energy via radio frequency (RF) signals from the surrounding resources. Regarding energy harvesting protocol, we propose power time switching-based relaying (PTSR) architecture for both amplify-and-forward (AF) and decode-and-forward (DF). Especially, we reveal the analytical expressions of achievable throughput, ergodic capacity and energy-efficient in case of imperfect channel state information (CSI) for both AF and DF network. Through numerical analysis, we analyse the throughput performance, energy-efficient and ergodic capacity for different parameters, including power splitting ratio and energy harvesting time. Moreover, we also depict the performance comparison between AF and DF network with perfect and imperfect CSI. The results in numerical analysis reveal that the result of AF relaying network is less significant than DF relaying network in the various scenarios.Web of Science1310191