Down-sampling of large lidar dataset in the context of off-road objects extraction

Nowadays, LiDAR (Light Detection and Ranging) is used in many fields, such as transportation. Thanks to the recent technological improvements, the current generation of LiDAR mapping instruments available on the market allows to acquire up to millions of three-dimensional (3D) points per second. On the one hand, such improvements allowed the development of LiDAR-based systems with increased productivity, enabling the quick acquisition of detailed 3D descriptions of the objects of interest. However, on the other hand, the extraction of the information of interest from such huge amount of acquired data can be quite challenging and time demanding. Motivated by such observation, this paper proposes the use of the Optimum Dataset method in order to ease and speed up the information extraction phase by significantly reducing the size of the acquired dataset while preserving (retain) the information of interest. This paper focuses on the data reduction of LiDAR datasets acquired on roads, with the goal of extraction the off-road objects. Mostly motivated by the need of mapping roads and quickly determining car position along a road, the development of efficient methods for the extraction of such kind of information is becoming a hot topic in the research community

Ferroelectric Dead Layer Driven by a Polar Interface

Based on first-principles and model calculations we investigate the effect of polar interfaces on the ferroelectric stability of thin-film ferroelectrics. As a representative model, we consider a TiO2-terminated BaTiO3 film with LaO monolayers at the two interfaces that serve as doping layers. We find that the polar interfaces create an intrinsic electric field that is screened by the electron charge leaking into the BaTiO3 layer. The amount of the leaking charge is controlled by the boundary conditions which are different for three heterostructures considered, namely Vacuum/LaO/BaTiO3/LaO, LaO/BaTiO3, and SrRuO3/LaO/BaTiO3/LaO. The intrinsic electric field forces ionic displacements in BaTiO3 to produce the electric polarization directed into the interior of the BaTiO3 layer. This creates a ferroelectric dead layer near the interfaces that is non-switchable and thus detrimental to ferroelectricity. Our first-principles and model calculations demonstrate that the effect is stronger for a larger effective ionic charge at the interface and longer screening length due to a stronger intrinsic electric field that penetrates deeper into the ferroelectric. The predicted mechanism for a ferroelectric dead layer at the interface controls the critical thickness for ferroelectricity in systems with polar interfaces.Comment: 33 Pages, 5 figure

Dickkopf-related protein 1 expression in bone marrow of multiple myeloma patients : correlation with bone disease and plasma cell malignancy type

Autoru afiliācijas atšķiras PDF versijā, žurnāla versijā, Pubmed un Web of Science datubāzēs.BACKGROUND: Previous studies have pointed out the role of dickkopf-related protein 1 (DKK 1) - Wnt inhibitor, which is essential for osteoblast functioning, in the development of osteolytic lesions in multiple myeloma (MM). AIM: To assess the DKK 1 expression displayed by myeloma cells in bone marrow trephine biopsies of patients with and without osteolytic lesions, and in different malignancy grades of the disease. METHODS: The expression level of DKK 1 was assessed immunohistochemically in bone marrow of 49 MM patients presented with and without osteolytic lesions (the 1st and the 2nd group, respectively). RESULTS: Levels of weak, moderate, and strong DKK 1 expression were distributed - as 43.33, 27.78 and 25.56%, and 63.91, 18.80, and 1.50%, respectively when evaluating the samples obtained from the 1st and the 2nd group. Statistically significant differences were found when the levels of DKK 1 expression in the 1st and the 2nd group were compared (χ2 = 51; df = 3; p < 0.001). CONCLUSIONS: DKK 1 contributes to the development of osteolytic lesions in MM. The present study provides morphological evidence that inhibition in Wnt signaling may lead to bone damage observed in the advanced stage of the disease.publishersversionPeer reviewe

Towards an optimization of turbulence effects on heat and mass transfer in evaporating and reacting gas turbine sprays

ABSTRACT In this paper, the way towards an optimization of turbulence effects on heat and mass transfer in evaporating and reacting GT-sprays is outlined. It is based on an accurate consideration of coupling between turbulence and turbulence modulation, swirl intensity and non-equilibrium effects during the vaporization. This is achieved by including a physically consistent modelling of turbulence modulation phenomena that allows to better retrieve mass and heat transport effects on the droplet surface, and therefore improves the prediction of processes, like evaporation and combustion, which in turn affect the turbulence. For this purpose, an Euler-Lagrangian method in conjunction with advanced models has been used in RANScontext and applied to the numerical study of a single gas turbine combustor configuration. a) To quantify, to control or to optimize the effects of turbulence along with the swirl intensity effects, a mixing parameter has been introduced. b) Under reacting conditions, it is shown how the evaporation characteristics, mixing rate and combustion process are influenced by turbulence. In particular, the turbulence modulation modifies the evaporation rate, which in turn influences the mixing and the species concentration distribution. It is demonstrated that this effect can not be neglected far from the nozzle for low swirl intensities (Sw.Nu.&lt;1) and close to the nozzle for high swirl number intensities. All these findings can well be used to optimize turbulence effects in evaporating and reacting sprays. INTRODUCTION The success of some promising approaches, such as the LPP-or the RQL-concept strategies, that can help to limit gas turbine emissions, depends on a suitable homogeneity of the air-fuel mixture in the reaction zone. To achieve this goal by means of numerical simulations, an accurate determination of droplet and vapour spatial distribution and a reliable control of the interaction between the evaporating and reacting spray with the surrounding turbulent gas flow are prerequisite. As pointed out in [1, 2] a considerable amount of works have been done including diverse parameter studies (e. g. [1-5, 8-15, 20-25, 34]. However, there are relatively few experimental and numerical results devoted to the effects of turbulence characteristics on spray combustio

Micro-Hall Magnetometry Studies of Thermally Assisted and Pure Quantum Tunneling in Single Molecule Magnet Mn12-Acetate

We have studied the crossover between thermally assisted and pure quantum tunneling in single crystals of high spin (S=10) uniaxial single molecule magnet Mn12-acetate using micro-Hall effect magnetometry. Magnetic hysteresis experiments have been used toinvestigate the energy levels that determine the magnetization reversal as a function of magnetic field and temperature. These experiments demonstrate that the crossover occurs in a narrow (~0.1 K) or broad (~1 K) temperature interval depending on the magnitude and direction of the applied field. For low external fields applied parallel to the easy axis, the energy levels that dominate the tunneling shift abruptly with temperature. In the presence of a transverse field and/or large longitudinal field these energy levels change with temperature more gradually. A comparison of our experimental results with model calculations of this crossover suggest that there are additional mechanisms that enhance the tunneling rate of low lying energy levels and broaden the crossover for small transverse fields.Comment: 5 pages, 5 figure

Coexistence of Magnetic Order and Two-dimensional Superconductivity at LaAlO3_3/SrTiO3_3 Interfaces

A two dimensional electronic system with novel electronic properties forms at the interface between the insulators LaAlO$_3$ and SrTiO$_3$. Samples fabricated until now have been found to be either magnetic or superconducting, depending on growth conditions. We combine transport measurements with high-resolution magnetic torque magnetometry and report here evidence of magnetic ordering of the two-dimensional electron liquid at the interface. The magnetic ordering exists from well below the superconducting transition to up to 200 K, and is characterized by an in-plane magnetic moment. Our results suggest that there is either phase separation or coexistence between magnetic and superconducting states. The coexistence scenario would point to an unconventional superconducting phase in the ground state.Comment: 10 pages, 4 figure

Evaluation of the flame propagation within an SI engine using flame imaging and LES

This work shows experiments and simulations of the fired operation of a spark ignition engine with port-fuelled injection. The test rig considered is an optically accessible single cylinder engine specifically designed at TU Darmstadt for the detailed investigation of in-cylinder processes and model validation. The engine was operated under lean conditions using iso-octane as a substitute for gasoline. Experiments have been conducted to provide a sound database of the combustion process. A planar flame imaging technique has been applied within the swirl- and tumble-planes to provide statistical information on the combustion process to complement a pressure-based comparison between simulation and experiments. This data is then analysed and used to assess the large eddy simulation performed within this work. For the simulation, the engine code KIVA has been extended by the dynamically thickened flame model combined with chemistry reduction by means of pressure dependent tabulation. Sixty cycles have been simulated to perform a statistical evaluation. Based on a detailed comparison with the experimental data, a systematic study has been conducted to obtain insight into the most crucial modelling uncertainties

Stochastic multiple mapping conditioning for a piloted, turbulent jet diffusion flame

A stochastic implementation of the multiple mapping conditioning (MMC) approach has been applied to a turbulent jet diffusion flame (Sandia Flame D). This implementation combines the advantages of the basic concepts of a mapping closure methodology with a probability density approach. A single reference variable has been chosen. Its evolution is described by a Markov process and then mapped to the mixture fraction space. Scalar micro-mixing is modelled by a modified “interaction by exchange with the mean” (IEM) mixing model where the particles mix with their -in reference space- conditionally averaged means. The formulation of the closure leads to localness of mixing in mixture fraction space and consequently improved localness in composition space. Results for mixture fraction and reactive species are in good agreement with the experimental data. The MMC methodology allows for the introduction of an additional “minor dissipation time scale” that controls the fluctuations around the conditional mean. A sensitivity analysis based on the conditional temperature fluctuations as a function of this time scale does not endorse earlier estimates for its modelling, but only relatively large dissipation time scales of the order of the integral turbulence time scale yield acceptable levels of conditional fluctuations that agree with experiments. With the choice of a suitable dissipation time scale, MMC-IEM thus provides a simple mixing model that is capable of capturing extinction phenomena, and it gives improved predictions over conventional PDF predictions using simple IEM mixing models