628 research outputs found

    The complete reducibility of some GF(2)A7-modules

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    It is proved that, if G is a finite group with a nontrivial normal 2-subgroup Q such that G/Q ∼= A 7 and an element of order 5 from G acts freely on Q, then the extension G over Q is splittable, Q is an elementary abelian group, and Q is the direct product of minimal normal subgroups of G each of which is isomorphic, as a G/Q-module, to one of the two 4-dimensional irreducible GF(2)A7-modules that are conjugate with respect to an outer automorphism of the group A7. © 2013 Pleiades Publishing, Ltd

    Machine learning technique for morphological classification of galaxies at z<0.1 from the SDSS

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    Methods. We used different galaxy classification techniques: human labeling, multi-photometry diagrams, Naive Bayes, Logistic Regression, Support Vector Machine, Random Forest, k-Nearest Neighbors, and k-fold validation. Results. We present results of a binary automated morphological classification of galaxies conducted by human labeling, multiphotometry, and supervised Machine Learning methods. We applied its to the sample of galaxies from the SDSS DR9 with redshifts of 0.02 < z < 0.1 and absolute stellar magnitudes of 24m < Mr < 19.4m. To study the classifier, we used absolute magnitudes: Mu, Mg, Mr , Mi, Mz, Mu-Mr , Mg-Mi, Mu-Mg, Mr-Mz, and inverse concentration index to the center R50/R90. Using the Support vector machine classifier and the data on color indices, absolute magnitudes, inverse concentration index of galaxies with visual morphological types, we were able to classify 316 031 galaxies from the SDSS DR9 with unknown morphological types. Conclusions. The methods of Support Vector Machine and Random Forest with Scikit-learn machine learning in Python provide the highest accuracy for the binary galaxy morphological classification: 96.4% correctly classified (96.1% early E and 96.9% late L types) and 95.5% correctly classified (96.7% early E and 92.8% late L types), respectively. Applying the Support Vector Machine for the sample of 316 031 galaxies from the SDSS DR9 at z < 0.1, we found 141 211 E and 174 820 L types among them.Comment: 10 pages, 5 figures. The presentation of these results was given during the EWASS-2017, Symposium "Astroinformatics: From Big Data to Understanding the Universe at Large". It is vailable through \url{http://space.asu.cas.cz/~ewass17-soc/Presentations/S14/Dobrycheva_987.pdf

    KiDS0239-3211: A new gravitational quadruple lens candidate

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    We report the discovery of a candidate to quadrupole gravitationally lensed system KiDS0239-3211 based on the public data release 3 of the KiDS survey and machine learning techniques

    Modeling startup and shutdown transient of the microlinear piezo drive via ANSYS

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    The article describes the construction-design of the micro linear piezo drive intended for a peripheral cord tensioner in the reflecting surface shape regulator system for large-sized transformable spacecraft antenna reflectors. The research target -the development method of modeling startup and shutdown transient of the micro linear piezo drive. This method is based on application software package ANSYS. The method embraces a detailed description of the calculation stages to determine the operating characteristics of the designed piezo drive. Based on the numerical solutions, the time characteristics of the designed piezo drive are determined

    Microlinear piezo drive experiments

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    The article embraces the experimental description of the micro linear piezo drive intended for the peripheral cord tensioner in the reflecting surface shape regulator system for large-sized transformable spacecraft antenna reflectors. The research target is the experimental investigation of the micro linear piezo drive to determine the stable oscillatory system operating modes which would include improved energy conversion parameters. The following points are briefly presented: test stand construction-design of the peripheral cord tensioner; the determined frequency characteristics and the identified resonant and actual frequencies of an oscillatory system under inertia load. A series of experiments has been conducted for both different preliminary voltages and inertia mass values

    Компьютерное моделирование ветровых нагрузок на высотные здания

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    The paper presents the results of numerical simulation of wind pressure on high rise buildings being under construction and planned in Yekaterinburg city (Russia). Simulation is performed in the program ANSYS. The simulated building is placed in a domain that is the numerical analogue of wind tunnel. Domain sizes are chosen in such a way that simulated buildings do not affect the flow of air on its boundaries. Shear stress transport (SST) turbulence model is used. In order to validate the numerical model the paper presents the results of experimental study and numerical simulation of external air flow around the cylindrical body with the diameter of 8 mm, placed on the way of free submerged jet of air. The cylinder which has simple geometry form was used due to the need to achieve the generality of the outcomes. A comparison of the results of calculation of wind pressure with the experimental data blasting building models in wind tunnels is done.В статье представлены результаты численного моделирования задачи определения ветровых давлений на строящиеся или проектируемые в г. Екатеринбурге (Россия) высотные здания. Задача решается в пакете ANSYS. Моделируемое здание и его окружение помещаются в домен, который является численным аналогом ветровой трубы. Размеры домена назначаются таким образом, чтобы объекты, входящие в домен, не влияли на движение воздуха у внешних границ домена. Для расчета используется модель SST. Для проверки правильности численной модели приводится сравнение результатов расчета с экспериментальными данными обдувки цилиндра диаметром 8 мм. Такая модель простой формы выбрана для удобства сравнения. Приведено сравнение численных результатов расчета давлений ветра на высотные здания с результатами обдувки в ветровых трубах

    In vivo Spectroscopy and Imaging of Nitroxide Probes

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    Book chapter from "Nitroxides - Theory, Experiment and Applications", edited by Alexander I. Kokorin, ISBN 978-953-51-0722-4, Hard cover, 436 pages, InTech, September 12, 2012. DOI: 10.5772/288

    VEXAS: VISTA EXtension to Auxiliary Surveys -- Data Release 2: Machine-learning based classification of sources in the Southern Hemisphere

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    We present the second public data release (DR) of the VISTA EXtension to Auxiliary Surveys (VEXAS), where we classify objects into stars, galaxies and quasars based on an ensemble of machine learning algorithms. The aim of VEXAS is to build the widest multi-wavelength catalogue, providing reference magnitudes, colours and morphological information for a large number of scientific uses. We apply an ensemble of 32 different machine learning models, based on three different algorithms and on different magnitude sets, training samples and classification problems on the three VEXAS DR1 optical+infrared (IR) tables. The tables were created in DR1 cross-matching VISTA near-IR data with WISE far-IR data and with optical magnitudes from the Dark Energy Survey (VEXAS-DESW), the Sky Mapper Survey (VEXAS-SMW), and the PanSTARRS (VEXAS-PSW). We assemble a large table of spectroscopically confirmed objects (415 628 unique objects), based on the combination of 6 different spectroscopic surveys that we use for training. We develop feature imputation to classify also objects for which magnitudes in one or more bands are missing. We classify in total ~90 million objects in the Southern Hemisphere. Among these,~62.9M (~52.6M) are classified as 'high confidence' ('secure') stars, ~920k (~750k) as 'high confidence' ('secure') quasars and ~34.8M (~34.1M) as 'high confidence' ('secure') galaxies, with probabilities pclass0.7p_{\rm class}\ge 0.7 (pclass0.9p_{\rm class}\ge 0.9). The density of high-confidence extragalactic objects varies strongly with the survey depth: at pclass0.7p_{\rm class}\ge 0.7, there are 111/deg2^2 quasars in the VEXAS-DESW footprint and 103/deg2^2 in the VEXAS-PSW footprint, while only 10.7/deg2^2 in the VEXAS-SM footprint. Improved depth in the midIR and coverage in the optical and nearIR are needed for the SM footprint that is not already covered by DESW and PSW.Comment: 25 pages, 18 figures, 8 tables. Accepted for publication on A&A. The VEXAS tables are publicly available through the ESO Phase 3 here: https://archive.eso.org/scienceportal/home?data_collection=VEXAS. The DR2 tables update the DR1 with the addition of imputed magnitudes and membership probabilities to each of the three classe

    Concurrent Longitudinal EPR Monitoring of Tissue Oxygenation, Acidosis, and Reducing Capacity in Mouse Xenograft Tumor Models

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    Tissue oxygenation, extracellular acidity and tissue reducing capacity are among crucial parameters of tumor microenvironment (TME) of significant importance for tumor pathophysiology. In this paper we demonstrate the complementary application of particulate lithium octa-n-butoxy-naphthalocyanine (LiNc-BuO) and soluble nitroxide (NR) paramagnetic probes for monitoring of these TME parameters using electron paramagnetic resonance (EPR) technique. Two different types of therapeutic interventions were studied: hypothermia and systemic administration of metabolically active drug. In summary, the results demonstrate utility of EPR technique for noninvasive concurrent longitudinal monitoring of physiologically relevant chemical parameters of TME in a mouse xenograft tumor models including that under therapeutic intervention
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