Simultaneous localization and mapping (SLAM) techniques are widely researched, since they allow the simultaneous creation of a map and the sensors’ pose estimation in an unknown environment. Visual-based SLAM techniques play a significant role in this field, as they are based on a low-cost and small sensor system, which guarantees those advantages compared to other sensor-based SLAM techniques. The literature presents different approaches and methods to implement visual-based SLAM systems. Among this variety of publications, a beginner in this domain may find problems with identifying and analyzing the main algorithms and selecting the most appropriate one according to his or her project constraints. Therefore, we present the three main visual-based SLAM approaches (visual-only, visual-inertial, and RGB-D SLAM), providing a review of the main algorithms of each approach through diagrams and flowcharts, and highlighting the main advantages and disadvantages of each technique. Furthermore, we propose six criteria that ease the SLAM algorithm’s analysis and consider both the software and hardware levels. In addition, we present some major issues and future directions on visual-SLAM field, and provide a general overview of some of the existing benchmark datasets. This work aims to be the first step for those initiating a SLAM project to have a good perspective of SLAM techniques’ main elements and characteristics.
Mass measurements with a relative precision of better than 1:5 10 ÿ8 were performed on 22 Mg and its reaction partners 21 Na and 22 Na with the ISOLTRAP Penning trap mass spectrometer at CERN, yielding the mass excesses D 22 Mg ÿ399:9227 keV, D 21 Na ÿ2184:7121 keV, and D 22 Na ÿ5181:5616 keV. The importance of these results is twofold. First, a comparative halflife (Ft value) has been obtained for the superallowed decay of 22 Mg to further test the conservedvector-current hypothesis. Second, the resonance energy for the 21 Na proton capture reaction has been independently determined, allowing direct comparisons of observable radiation in nova explosions with the yield expected from models. DOI: 10.1103/PhysRevLett.93.150801 PACS numbers: 21.10.Dr, 23.40.Bw, 26.30.+k, 27.30.+t The nuclear binding energy has a profound influence on a diversity of natural phenomena, ranging from the explosion of stars in the cosmos to the microscopic extreme of the interactions governing quarks. Mass differences between radioactive parent and daughter nuclides in the case of superallowed decays are critical for weak-interaction studies, in particular for a test of the conserved-vector-current (CVC) hypothesis and ultimately for the determination of the V ud element of the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing matrix. The binding energy also determines how much energy is available for a nuclear reaction, thus playing a fundamental role in the elaboration of models for stellar evolution and critical aspects of nucleosynthesis.The short-lived radionuclide 22 Mg (T 1=2 3:88 s) has recently been the subject of controversy on these latter two fronts: the superallowed decay of 22 Mg to 22 Na [1] and the 21 Nap; 22 Mg reaction rate in classical novae [2]. In both contexts, the authors concluded that there was conflicting information on the 22 Mg mass. The value tabulated in the recent atomic mass evaluation (AME 2003) [3] is derived from two discrepant 30-year-old reaction Q value measurements. Clearly, an independent and direct high-precision measurement of the 22 Mg mass with an uncertainty well below 1 keV was required. In this Letter, we report on such a measurement, which has recently been performed with the ISOLTRAP Penning trap mass spectrometer at ISOLDE/CERN.The CVC hypothesis holds that the (corrected) comparative half-lives Ft of all superallowed decays are equal as a consequence of the assumed independence of the vector-current part of the weak interaction from the strong force. The determination of Ft requires precision measurements of the decay energy and the partial decay half-life, as well as detailed calculations of the associated isospin-symmetry-breaking ( C ) and radiative corrections ( R ) [4,5]. The comparative half-lives for nine superallowed T 1 0 ! 0 decays have been determined to a precision of 10 ÿ4 or better [5]. They agree well with each other within their uncertainties and yield a weighted mean value of Ft 3072:20:91:1 s, where the second uncertainty term represents a deviation in the calculation...
The MOBISIC project, funded by the System@tic Paris-Region cluster, is being developed in the context of local crisis (attack bombing in urban environment, in confined space such as an underground train tunnel etc.) or specific event securing (soccer world cup, political meeting etc.). It consists in conceiving, developing and experimenting a mobile, modular ('plug and play') and multi-sensors securing system. In this project, CEA LIST has suggested different solutions for nuclear risks detection and identification. It results in embedding a CZT sensor and a gamma camera in an indoor drone. This article first presents the different modifications carried out on the UAV and different sensors, and focuses then on the experimental performances.
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