A directional random laser mediated by transverse Anderson localization in a disordered glass optical fiber is reported. Previous demonstrations of random lasers have found limited applications ...because of their multi-directionality and chaotic fluctuations in the laser emission. The random laser presented in this paper operates in the Anderson localization regime. The disorder induced localized states form isolated local channels that make the output laser beam highly directional and stabilize its spectrum. The strong transverse disorder and longitudinal invariance result in isolated lasing modes with negligible interaction with their surroundings, traveling back and forth in a Fabry-Perot cavity formed by the air-fiber interfaces. It is shown that if a localized input pump is scanned across the disordered fiber input facet, the output laser signal follows the transverse position of the pump. Moreover, a uniformly distributed pump across the input facet of the disordered fiber generates a laser signal with very low spatial coherence that can be of practical importance in many optical platforms including image transport with fiber bundles.
Recently, machine learning (ML) has been widely adopted for fingerprint-based indoor localization because of its potency in delineating relationships between received signal strength (RSS) ...information and labels accurately. Existing ML-based indoor localization systems are less robust because they only adopt the output with the highest probability. This affects the final location estimate, hence compromising accuracy due to the severity of RSS fluctuations. Since different ML algorithms (MLAs) yield different performances, it is therefore intuitive to fuse predictions from multiple MLAs to improve the positioning performance in the presence of signal fluctuation. In this article, we propose SmartLoc, a smart wireless indoor localization framework to enhance indoor localization. In the offline phase, multiple MLAs are trained by utilizing an offline database. We further apply probability alignment to guarantee the predicted probabilities of each MLA at the same confidence level. In the online phase, given a testing RSS sample of a user at an unknown location, we extract the labels with probabilities greater than a certain threshold from each MLA to construct the space of candidate labels (SCL). The size of SCL can be adaptively determined by using our proposed dynamic size determination algorithm. Based on the SCL, we propose a probabilistic model to intelligently estimate the user's location by evaluating the label credibility simultaneously. A high label credibility indicates that the frequently occurred label is more likely to be true. Experimental results in a real changing environment verify the superiority of SmartLoc, outperforming the best among comparative methods by 10.8% in 75th percentile accuracy.
The modulation effect manifests an encouraging potential to enhance the performance of single‐atom catalysts; however, the in‐depth study about this effect for the isolated diatomic sites (DASs) ...remains a great challenge. Herein, a proximity electronic effect (PEE) of Ni/Co DASs is proposed that is anchored in N‐doped carbon (N‐C) substrate (NiCo DASs/N‐C) for synergistic promoting electrocatalytic oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). Benefiting from the PEE of adjacent Ni anchored by four nitrogen (Ni‐N4) moiety, NiCo DASs/N‐C catalyst exhibits superior ORR and HER activity. In situ characterization results suggest Co anchored by four nitrogen (Co‐N4) as main active site for O2 adsorption‐activation process, which promotes the formation of key *OOH and the desorption of *OH intermediate to accelerate the multielectron reaction kinetics. Theoretical calculation reveals the adjacent Ni‐N4 site as a modulator can effectively adjust the electronic localization of proximity Co‐N4 site, promoting the *OH desorption and *H adsorption on Co‐N4 site, thereby boosting ORR and HER process significantly. This study opens a new opportunity for rationally regulating the electronic localization of catalytic active centers by proximity single‐atom moiety, as well as provides guidance for designing high‐efficiency bifunctional electrocatalysts for promising applications.
A proximity electronic effect of NiCo DASs that is anchored in N‐doped carbon substrate is proposed for synergistic promoting electrocatalytic ORR and HER. The adjacent Ni‐N4 site as a modulator can effectively adjust the electronic localization of the active Co‐N4 site, promoting the desorption of key *OH and adsorption of *H on Co‐N4 site, thereby significantly boosting the ORR and HER process.
As discovered by Philip Anderson in 1958, strong disorder can block propagation of waves and lead to the localization of wavelike excitations in space. Anderson localization of light is particularly ...exciting in view of its possible applications for random lasing or quantum information processing. We show that, surprisingly, Anderson localization of light cannot be achieved in a random three-dimensional ensemble of point scattering centers that is the simplest and widespread model to study the multiple scattering of waves. Localization is recovered if the vector character of light is neglected. This shows that, at least for point scatterers, the polarization of light plays an important role in the Anderson localization problem.
The nuclear translocation of YAP1 is significantly implicated in the proliferation, stemness, and metastasis of cancer cells. Although the molecular basis underlying YAP1 subcellular distribution has ...been extensively explored, it remains to be elucidated how the nuclear localization signal guides YAP1 to pass through the nuclear pore complex. Here, we define a globular type of nuclear localization signal composed of folded WW domains, named as WW-NLS. It directs YAP1 nuclear import through the heterodimeric nuclear transport receptors KPNA-KPNB1, bypassing the canonical nuclear localization signal that has been well documented in KPNA/KPNB1-mediated nuclear import. Strikingly, competitive interference with the function of the WW-NLS significantly attenuates YAP1 nuclear translocation and damages stemness gene activation and sphere formation in malignant breast cancer cells. Our findings elucidate a novel globular type of nuclear localization signal to facilitate nuclear entry of WW-containing proteins including YAP1.
The subcellular localization of long noncoding RNAs (lncRNAs) holds valuable clues to their molecular function. However, measuring localization of newly discovered lncRNAs involves time-consuming and ...costly experimental methods. We have created "lncATLAS," a comprehensive resource of lncRNA localization in human cells based on RNA-sequencing data sets. Altogether, 6768 GENCODE-annotated lncRNAs are represented across various compartments of 15 cell lines. We introduce relative concentration index (RCI) as a useful measure of localization derived from ensemble RNA-seq measurements. LncATLAS is accessible through an intuitive and informative webserver, from which lncRNAs of interest are accessed using identifiers or names. Localization is presented across cell types and organelles, and may be compared to the distribution of all other genes. Publication-quality figures and raw data tables are automatically generated with each query, and the entire data set is also available to download. LncATLAS makes lncRNA subcellular localization data available to the widest possible number of researchers. It is available at lncatlas.crg.eu.
Efficient charge‐carrier transport is critical to the success of emergent semiconductors in photovoltaic applications. So far, disorder has been considered detrimental for charge‐carrier transport, ...lowering mobilities, and causing fast recombination. This work demonstrates that, when properly engineered, cation disorder in a multinary chalcogenide semiconductor can considerably enhance the charge‐carrier mobility and extend the charge‐carrier lifetime. Here, the properties of AgBiS2 nanocrystals (NCs) are explored as a function of Ag and Bi cation‐ordering, which can be modified via thermal‐annealing. Local Ag‐rich and Bi‐rich domains formed during hot‐injection synthesis are transformed to induce homogeneous disorder (random Ag‐Bi distribution). Such cation‐disorder engineering results in a sixfold increase in the charge‐carrier mobility, reaching ≈2.7 cm2 V−1 s−1 in AgBiS2 NC thin films. It is further demonstrated that homogeneous cation disorder reduces charge‐carrier localization, a hallmark of charge‐carrier transport recently observed in silver‐bismuth semiconductors. This work proposes that cation‐disorder engineering flattens the disordered electronic landscape, removing tail states that would otherwise exacerbate Anderson localization of small polaronic states. Together, these findings unravel how cation‐disorder engineering in multinary semiconductors can enhance the efficiency of renewable energy applications.
Disorder is generally considered as detrimental for charge‐carrier transport, lowering mobilities, and causing fast recombination. However, this work demonstrates that, when properly engineered, cation disorder in the multinary chalcogenide semiconductor AgBiS2 considerably enhances charge‐carrier transport and reduces localization effects. Cation‐ disorder engineering is demonstrated as a powerful strategy to tune the optoelectronic properties of new semiconductors for renewable energy applications.
The increased potential and effectiveness of Real-time Locating Systems (RTLSs) substantially influence their application spectrum. They are widely used, inter alia, in the industrial sector, ...healthcare, home care, and in logistic and security applications. The research aims to develop an analytical method to customize UWB-based RTLS, in order to improve their localization performance in terms of accuracy and precision. The analytical uncertainty model of Angle of Arrival (AoA) localization in a 3D indoor space, which is the foundation of the customization concept, is established in a working environment. Additionally, a suitable angular-based 3D localization algorithm is introduced. The paper investigates the following issues: the influence of the proposed correction vector on the localization accuracy; the impact of the system's configuration and LS's relative deployment on the localization precision distribution map. The advantages of the method are verified by comparing them with a reference commercial RTLS localization engine. The results of simulations and physical experiments prove the value of the proposed customization method. The research confirms that the analytical uncertainty model is the valid representation of RTLS' localization uncertainty in terms of accuracy and precision and can be useful for its performance improvement. The research shows, that the Angle of Arrival localization in a 3D indoor space applying the simple angular-based localization algorithm and correction vector improves of localization accuracy and precision in a way that the system challenges the reference hardware advanced localization engine. Moreover, the research guides the deployment of location sensors to enhance the localization precision.
A Belief Propagation Algorithm for Multipath-Based SLAM Leitinger, Erik; Meyer, Florian; Hlawatsch, Franz ...
IEEE transactions on wireless communications,
2019-Dec., 2019-12-00, 20191201, 2019-12-01, Letnik:
18, Številka:
12
Journal Article
Recenzirano
Odprti dostop
We present a simultaneous localization and mapping (SLAM) algorithm that is based on radio signals and the association of specular multipath components (MPCs) with geometric features. Especially in ...indoor scenarios, robust localization from radio signals is challenging due to diffuse multipath propagation, unknown MPC-feature association, and limited visibility of features. In our approach, specular reflections at flat surfaces are described in terms of virtual anchors (VAs) that are mirror images of the physical anchors (PAs). The positions of these VAs and possibly also of the PAs are unknown. We develop a Bayesian model of the SLAM problem and represent it by a factor graph, which enables the use of belief propagation (BP) for efficient marginalization of the joint posterior distribution. The resulting BP-based SLAM algorithm detects the VAs associated with the PAs and estimates jointly the time-varying position of the mobile agent and the positions of the VAs and possibly also of the PAs, thereby leveraging the MPCs in the radio signal for improved accuracy and robustness of agent localization. The algorithm has a low computational complexity and scales well in all relevant system parameters. Experimental results using both synthetic measurements and real ultra-wideband radio signals demonstrate the excellent performance of the algorithm in challenging indoor environments.
This paper addresses the problem of bearing-based network localization, which aims to localize all the nodes in a static network given the locations of a subset of nodes termed anchors and inter-node ...bearings measured in a common reference frame. The contributions of the paper are twofold. Firstly, we propose necessary and sufficient conditions for network localizability with both algebraic and rigidity theoretic interpretations. Secondly, we propose and analyze a linear distributed protocol for bearing-based network localization. One novelty of our work is that the localizability analysis and localization protocol are applicable to networks in arbitrary dimensional spaces.
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