435 research outputs found

    ON CONSTRUCTION OF A RELIABLE GROUND TRUTH FOR EVALUATION OF VISUAL SLAM ALGORITHMS

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    In this work we are concerning the problem of localization accuracy evaluation of visual-based Simultaneous Localization and Mapping (SLAM) techniques. Quantitative evaluation of the SLAM algorithm performance is usually done using the established metrics of Relative pose error and Absolute trajectory error which require a precise and reliable ground truth. Such a ground truth is usually hard to obtain, while it requires an expensive external localization system. In this work we are proposing to use the SLAM algorithm itself to construct a reliable ground-truth by offline frame-by-frame processing. The generated ground-truth is suitable for evaluation of different SLAM systems, as well as for tuning the parametrization of the on-line SLAM. The presented practical experimental results indicate the feasibility of the proposed approach

    Diagnostic indices for vertiginous diseases

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    <p>Abstract</p> <p>Background</p> <p>Vertigo and dizziness are symptoms which are reported frequently in clinical practice. We aimed to develop diagnostic indices for four prevalent vertiginous diseases: benign paroxysmal positional vertigo (BPPV), Menière's disease (MD), vestibular migraine (VM), and phobic postural vertigo (PPV).</p> <p>Methods</p> <p>Based on a detailed questionnaire handed out to consecutive patients presenting for the first time in our dizziness clinic we preselected a set of seven questions with desirable diagnostic properties when compared with the final diagnosis after medical workup. Using exact logistic regression analysis diagnostic scores, each comprising of four to six items that can simply be added up, were built for each of the four diagnoses.</p> <p>Results</p> <p>Of 193 patients 131 questionnaires were left after excluding those with missing consent or data. Applying the suggested cut-off points, sensitivity and specificity were 87.5 and 93.5% for BPPV, 100 and 87.4% for MD, 92.3 and 83.7% for VM, 73.7 and 84.1% for PPV, respectively. By changing the cut-off points sensitivity and specificity can be adjusted to meet diagnostic needs.</p> <p>Conclusions</p> <p>The diagnostic indices showed promising diagnostic properties. Once further validated, they could provide an ease to use and yet flexible tool for screening vertigo in clinical practice and epidemiological research.</p

    Design of aerodynamic elements for student formulas

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    Tato bakalářská práce se zabývá návrhem aerodynamických prvků pro tým FS TUL Racing. V~teoretické části jsou popsány vlastnosti reálných tekutin, silové působení na těleso v~proudu reálné tekutiny a vlastnosti leteckých profilů a křídel. Na závěr této části jsou zmíněny vlivy na dynamiku vozidel. V~praktické částí je navrhnut dvouprvkový profil zadního křídla, který je následně analyzován pomocí 2D CFD analýzy pro tři rychlosti a pět úhlů náběhu. Výsledky této analýzy jsou využity pro řešení rovnováhy předního a zadního křídla na vozidle. Z~navržených rozměrů je vyhotoven 3D CAD model sestavy kompletního křídla. Ve zbytku práce jsou zmíněny efekty aerodynamických prvků na vozidlo, konkrétně přidaná hmotnost, silové zatížení křídla a rovnoměrný pohyb vozu při zatáčení.This bachelor thesis deals with a design of aerodynamic elements for the FS TUL Racing team. The theoretical part describes the properties of a real fluid, force effects on the body in the flow of a real fluid and the properties of airfoils and wings. At the end of the theoretical part, effects on vehicle dynamics are mentioned. The practical part describes a design process of a two-piece profile of the rear wing, which is subsequently analyzed by a 2D CFD analysis for three values of speed and five angles of attack. The results of this analysis are used to solve the equilibrium of the front and rear wing of the vehicle. A~3D CAD model of a complete wing assembly is designed from the proposed dimensions. In the rest of the work, the effects of aerodynamic elements on the vehicle are mentioned, namely the added weight, forces acting on the wing and a uniform motion of the car when cornering

    Petri Nets Virtual Machine Persistency

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    Tato bakalářská práce se věnuje problematice perzistence v jazyce Java. Představuje a porovnává existující standardy a systémy, a zabývá se návrhem a implementací perzistenčního prostředí pro platformu Java SE s výstupem ve formě XML souborů.This Bachelor's thesis deals with persistence for Java language. It presents and compares already existing standards and systems, and introduces a design and implementation of persistence for Java SE platform with object data stored in XML files. 

    Rectification properties of conically shaped nanopores: consequences of miniaturization

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    Nanopores attracted a great deal of scientific interest as templates for biological sensors as well as model systems to understand transport phenomena at the nanoscale. The experimental and theoretical analysis of nanopores has been so far focused on understanding the effect of the pore opening diameter on ionic transport. In this article we present systematic studies on the dependence of ion transport properties on the pore length. Particular attention was given to the effect of ion current rectification exhibited for conically shaped nanopores with homogeneous surface charges. We found that reducing the length of conically shaped nanopores significantly lowered their ability to rectify ion current. However, rectification properties of short pores can be enhanced by tailoring the surface charge and the shape of the narrow opening. Furthermore we analyze the relationship of the rectification behavior and ion selectivity for different pore lengths. All simulations were performed using MsSimPore, a software package for solving the Poisson-Nernst-Planck (PNP) equations. It is based on a novel finite element solver and allows for simulations up to surface charge densities of -2 e/nm^2. MsSimPore is based on 1D reduction of the PNP model, but allows for a direct treatment of the pore with bulk electrolyte reservoirs, a feature which was previously used in higher dimensional models only. MsSimPore includes these reservoirs in the calculations; a property especially important for short pores, where the ionic concentrations and the electric potential vary strongly inside the pore as well as in the regions next to pore entrance

    Co-morbidities of vertiginous diseases

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    <p>Abstract</p> <p>Background</p> <p>Co-morbidities of vertiginous diseases have so far not been investigated systematically. Thus, it is still unclear whether the different vertigo syndromes (e.g. benign paroxysmal positional vertigo (BPPV), Meniere's disease (MD), vestibular migraine and phobic vertigo (PPV)) have also different spectrums of co-morbidities.</p> <p>Methods</p> <p>All patients from a cohort of 131 participants were surveyed using a standardised questionnaire about the co-morbidities hypertension, diabetes mellitus, BMI (body mass index), migraine, other headache, and psychiatric diseases in general and the likelihood of a depression in particular.</p> <p>Results</p> <p>We noted hypertension in 29.0% of the cohort, diabetes mellitus in 6.1%, migraine in 8.4%, other headache in 32.1%, psychiatric diseases in 16.0%, overweight and obesity in 33.6% and 13.7% respectively, as well as a clinical indication for depression in 15.9%.</p> <p>Conclusion</p> <p>In general, we did not detect an increased prevalence of the co-morbidities diabetes mellitus, arterial hypertension, migraine, other headache and obesity compared to the general population. There was an increased prevalence of psychiatric co-morbidity in patients with PPV, and the prevalence of hypertension was elevated in patients with MD.</p

    Genome-Wide Association Study of Genetic Control of Seed Fatty Acid Biosynthesis in Brassica napus

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    Fatty acids and their composition in seeds determine oil value for nutritional or industrial purposes and also affect seed germination as well as seedling establishment. To better understand the genetic basis of seed fatty acid biosynthesis in oilseed rape (Brassica napus L.) we applied a genome-wide association study, using 91,205 single nucleotide polymorphisms (SNPs) characterized across a mapping population with high-resolution skimgenotyping by sequencing (SkimGBS). We identified a cluster of loci on chromosome A05 associated with oleic and linoleic seed fatty acids. The delineated genomic region contained orthologs of the Arabidopsis thaliana genes known to play a role in regulation of seed fatty acid biosynthesis such as Fatty acyl-ACP thioesterase B (FATB) and Fatty Acid Desaturase (FAD5). This approach allowed us to identify potential functional genes regulating fatty acid composition in this important oil producing crop and demonstrates that this approach can be used as a powerful tool for dissecting complex traits for B. napus improvement programs

    Location and distribution of micro-inclusions in the EDML and NEEM ice cores using optical microscopy and in situ Raman spectroscopy

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    Impurities control a variety of physical properties of polar ice. Their impact can be observed at all scales – from the microstructure (e.g., grain size and orientation) to the ice sheet flow behavior (e.g., borehole tilting and closure). Most impurities in ice form micrometer-sized inclusions. It has been suggested that these μ inclusions control the grain size of polycrystalline ice by pinning of grain boundaries (Zener pinning), which should be reflected in their distribution with respect to the grain boundary network. We used an optical microscope to generate high-resolution large-scale maps (3 μm pix^-1, 8 x 2 cm^2) of the distribution of micro-inclusions in four polar ice samples: two from Antarctica (EDML, MIS 5.5) and two from Greenland (NEEM, Holocene). The in situ positions of more than 5000 μ inclusions have been determined. A Raman microscope was used to confirm the extrinsic nature of a sample proportion of the mapped inclusions. A superposition of the 2-D grain boundary network and μ-inclusion distributions shows no significant correlations between grain boundaries and μ inclusions. In particular, no signs of grain boundaries harvesting μ inclusions could be found and no evidence of μ inclusions inhibiting grain boundary migration by slow-mode pinning could be detected. Consequences for our understanding of the impurity effect on ice microstructure and rheology are discussed

    Location and composition of micro-inclusions in deep ice from the EDML ice core (Antarctica) using optical microscope and cryo-Raman spectroscopy

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    The impurity content in meteoric ice from polar regions is relatively low compared to other natural materials. However, it controls a variety of physical properties of ice - from dielectric response to its mechanical behaviour. Links between impurity concentration, changes in ice micro-structure and deformation rate have been reported on several scales. In order to approach the responsible mechanisms, a better understanding is needed regarding the in-situ form, location, and distribution of the different species within the polycrystal. We used an optical microscope to generate high-resolution 2D-maps of micro-inclusions in deep ice from the EDML ice core (Antarctica). Superposition of the grain boundary network and micro-inclusion distributions shows no significant correlations between grain boundaries and micro-inclusions. Implications for the relevance of Zener pinning during grain boundary migration and redistribution of impurities by grain boundary drag are discussed. Raman spectra of micro-inclusions in selected regions were obtained using a confocal cryo-Raman system. Comparison with ion chromatography shows that most of the available ions in ice precipitate in form of micro-inclusions. However, indications were found that some of the residual components could coexist in form of solid solution
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