Autonomous Mobile Mapping Robots: Key Software Components

This chapter discusses key software components of autonomous mobile mapping robots equipped with an inertial measurement unit (IMU) and light detection and ranging (LiDAR). In recent years, new LiDARs with nonrepetitive scanning pattern have appeared in the market. They are also equipped with an IMU; thus, the front end of simultaneous localization and mapping (SLAM)—a robust LiDAR-inertial odometry framework—significantly improves unmanned ground vehicles (UGVs) and unmanned aerial vehicles (UAV) in 3D mapping scenarios. Our study incorporates FAST-LIO as the front end of SLAM. The main focus is a lightweight back-end implementation of pose graph simultaneous localization and mapping (SLAM). It is an alternative solution to state-of-the-art g2o or GTSAM implementations. We also elaborate on iterative closest point, normal distributions transform, and their extension for multiview 3D data registration/refinement. It is based on C++ using Eigen library. This chapter also discusses path planning in already mapped environment. All software components are available as open-source projects

The Ekman-Hartmann layer in MHD Taylor-Couette flow

We study magnetic effects induced by rigidly rotating plates enclosing a cylindrical MHD Taylor-Couette flow at the finite aspect ratio $H/D=10$. The fluid confined between the cylinders is assumed to be liquid metal characterized by small magnetic Prandtl number, the cylinders are perfectly conducting, an axial magnetic field is imposed \Ha \approx 10, the rotation rates correspond to \Rey of order $10^2-10^3$. We show that the end-plates introduce, besides the well known Ekman circulation, similar magnetic effects which arise for infinite, rotating plates, horizontally unbounded by any walls. In particular there exists the Hartmann current which penetrates the fluid, turns into the radial direction and together with the applied magnetic field gives rise to a force. Consequently the flow can be compared with a Taylor-Dean flow driven by an azimuthal pressure gradient. We analyze stability of such flows and show that the currents induced by the plates can give rise to instability for the considered parameters. When designing an MHD Taylor-Couette experiment, a special care must be taken concerning the vertical magnetic boundaries so they do not significantly alter the rotational profile.Comment: 9 pages, 6 figures; accepted to PR

Experiments on the magnetorotational instability in helical magnetic fields

The magnetorotational instability (MRI) plays a key role in the formation of stars and black holes, by enabling outward angular momentum transport in accretion disks. The use of combined axial and azimuthal magnetic fields allows the investigation of this effect in liquid metal flows at moderate Reynolds and Hartmann numbers. A variety of experimental results is presented showing evidence for the occurrence of the MRI in a Taylor-Couette flow using the liquid metal alloy GaInSn.Comment: 15 pages, 13 figures, submitted to New Journal of Physic

Experimental evidence for magnetorotational instability in a helical magnetic field

A recent paper [R. Hollerbach and G. Rudiger, Phys. Rev. Lett. 95, 124501 (2005)] has shown that the threshold for the onset of the magnetorotational instability (MRI) in a Taylor-Couette flow is dramatically reduced if both axial and azimuthal magnetic fields are imposed. In agreement with this prediction, we present results of a Taylor-Couette experiment with the liquid metal alloy GaInSn, showing evidence for the existence of the MRI at Reynolds numbers of order 1000 and Hartmann numbers of order 10.Comment: 4 pages, 4 figure

Designing of Elastoplastic Adaptive Truss Structures with the Use of Particle Swarm Optimization

In the paper we demonstrate how Particle Swarm Optimization (PSO) can be employed to solve the Adaptive Impact Absorption (AIA) problem. We consider a truss structure which is subjected to impact loads. Stiff bars can be replaced by elastoplastic fuses which control theirs dynamical response. The point of optimization is to maximize or minimize a given objective function by redesigning the structure. This is realized by redistributing the initial mass, finding proper fuse localizations and adjusting, in real-time, the elastoplastic limits. Comparing to the previous results, we show that PSO is capable of achieving results at least as good as gradient-based optimization, having at the same time much larger flexibility regarding the definition of the objective function. This gives significantly broader field of potential applications. In particular, we present how PSO can be used to solve the simultaneous optimization problem: mass redistribution and fuse positioning for a set of expected, various impacts

Controversies over the shape of Polish electoral administration

W pracy przeanalizowano dane liczbowe dotyczące wyników wyborów do sejmików wojewódzkich, które odbyły się w Polsce w listopadzie 2014. Badania korelacji pomiędzy frekwencja wyborczą, odsetkiem głosów nieważnych oraz wynikami danego komitetu wyborczego, a także porównanie częstości występowania poszczególnych cyfr w wynikach wyborczych z prawem Benforda nie wykazały oczywistych anomalii statystycznych, które mogłyby dostarczyć argumentów za tezą o masowych nieprawidłowościach lub oszustwach. Z drugiej strony porównanie wyników wyborów z lat 2010 i 2014 oraz analiza modelu matematycznego symulującego zarejestrowane wyniki pozwala potwierdzić „efekt pierwszej strony”’: głosowanie przy pomocy broszury wyborczej mogło przynieść wymierne korzyści komitetowi wyborczemu, który w wyborach wylosował numer 1.We perform statistical analysis of results of local elections, which took place in Poland in November 2014. Investigating data concerning voivodeship sejmik (provincial-level assembly) we studied correlations between participation in elections, percentage of invalid votes and results of a given party. Furthermore, the frequency, with which a given digit appeared in the numbers provided by the electoral commission was analyzed and compared with the law of Benford. Our results did not reveal significant statistical irregularities, which could possibly confirm an allegated electoral fraud. However, our investigations do confirm the “first page” effect: as in these elections several-page brochures were used as ballot papers, the party which started with number one and their candidates were listed in the first page of the ballot paper had a substantial advantage over the competitors

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