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    Wyświetlanie 1-15 z 15
    Tytuł:
    Three-Axis Attitude Estimation Of Satellite Through Only Two-Axis Magnetometer Observations Using LKF Algorithm
    Autorzy:
    Mehrjardi, M. F.
    Sanusi, H.
    Ali, M. A. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/221622.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    satellite three-axis attitude estimation
    two-axis magnetometer
    observations
    LKF
    PD controller
    Opis:
    Estimation of satellite three-axis attitude using only one sensor data presents an interesting estimation problem. A flexible and mathematically effective filter for solving the satellite three-axis attitude estimation problem using two-axis magnetometer would be a challenging option for space missions which are suffering from other attitude sensors failure. Mostly, magnetometers are employed with other attitude sensors to resolve attitude estimation. However, by designing a computationally efficient discrete Kalman filter, full attitude estimation can profit by only two-axis magnetometer observations. The method suggested solves the problem of satellite attitude estimation using linear Kalman filter (LKF). Firstly, all models are generated and then the designed scenario is developed and evaluated with simulation results. The filter can achieve 10e-3 degree attitude accuracy or better on all three axes.
    Źródło:
    Metrology and Measurement Systems; 2015, 22, 4; 577-590
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Change of Easy Magnetization Axis and Frequency of Reflection Loss by Co-Ti Substitution in Barium Ferrite
    Autorzy:
    Yang, Su-Won
    Kim, Jeong-Gon
    Jeong, Kwang-Pil
    Shim, Han-Ul
    Cho, Seong-Il
    Kim, Min-Young
    Powiązania:
    https://bibliotekanauki.pl/articles/354821.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    barium ferrite
    Co-Ti substitution
    easy magnetization axis
    Opis:
    In this study, BaFe12-2xCoxTixO19 (X : 0 to 2.0, 0.2) powders were synthesized by sol-gel process. TG-DTA, XRD, SEM, VSM, and Network analyzer were measured in order to influence easy magnetization axis change on the wave absorption frequency range change. The easy magnetization axis change of the annealed powder at 900°C and 1200°C was confirmed by the coercive force decreased 4,800 and 3,870 Oe to 260 and 269 Oe, respectively, at the substitution ratio of 0.8 and 1.0. And it was confirmed that the change of the easy magnetization axis affected the change of the wave absorption frequency. The wave absorption frequency of substituted Barium Ferrite was less than 10 GHz range after the easy magnetization axis of Barium ferrite changed to a-b plan direction. It was confirmed the BaFe12-2xCoxTixO19(x=0.8 to 1.6) was synthesized by the sol-gel process and it was annealed at 900°C and 1200°C, which could be used as a wave absorber in the X-band region of 10 GHz less.
    Źródło:
    Archives of Metallurgy and Materials; 2019, 64, 3; 835-839
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dual manipulator system calibration based on virtual constraints
    Autorzy:
    Zhu, Q.
    Xie, X.
    Li, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/200227.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    dual manipulators
    calibration
    virtual constraint
    optical axis
    robot-robot
    hand-eye
    Opis:
    Calibration is necessary for dual manipulator to complete operational tasks. This paper proposes an effective robot-robot and hand-eye calibration method based on virtual constraints. Firstly, a rotational error model and a translational error model are established based on the relationships between the transformation matrices of the dual manipulator calibration system. Then a poses-alignment method is designed to make the poses of the two robots satisfy the constructed virtual constraints. At the aligned positions, the joint angles of the two robots are saved and used to calculate the values of the variables in the error models. Finally, the robot-robot and hand-eye rotational errors are estimated by an iterative algorithm. These errors are then used to calculate translational errors based on the SVD (singular value decomposition) method. To show the feasibility and effectiveness of the proposed method, experiments of robot-robot and hand-eye calibration for dual manipulators are performed. The experiment results demonstrate that the accuracy of the dual manipulator system is improved greatly.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2019, 67, 6; 1149-1159
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Changes in DNA methylation of embryonic axes of seeds of oak and beech during in vitro culture and cryopreservation
    Autorzy:
    Nuc, K.
    Marszalek, M.
    Pukacki, P.M.
    Powiązania:
    https://bibliotekanauki.pl/articles/80269.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    conference
    DNA methylation
    plant growing
    embryonic axis
    seed
    oak
    beech
    in vitro culture
    cryopreservation
    Źródło:
    BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2013, 94, 3
    0860-7796
    Pojawia się w:
    BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Area collapse algorithm computing new curve of 2D geometric objects
    Autorzy:
    Buczek, M. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/145607.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    shape analysis
    Polygon collapse
    medial axis
    geometry processing
    spatial database
    analiza kształtu
    geometria
    przestrzenna baza danych
    Opis:
    The processing of cartographic data demands human involvement. Up-to-date algorithms try to automate a part of this process. The goal is to obtain a digital model, or additional information about shape and topology of input geometric objects. A topological skeleton is one of the most important tools in the branch of science called shape analysis. It represents topological and geometrical characteristics of input data. Its plot depends on using algorithms such as medial axis, skeletonization, erosion, thinning, area collapse and many others. Area collapse, also known as dimension change, replaces input data with lower-dimensional geometric objects like, for example, a polygon with a polygonal chain, a line segment with a point. The goal of this paper is to introduce a new algorithm for the automatic calculation of polygonal chains representing a 2D polygon. The output is entirely contained within the area of the input polygon, and it has a linear plot without branches. The computational process is automatic and repeatable. The requirements of input data are discussed. The author analyzes results based on the method of computing ends of output polygonal chains. Additional methods to improve results are explored. The algorithm was tested on real-world cartographic data received from BDOT/GESUT databases, and on point clouds from laser scanning. An implementation for computing hatching of embankment is described.
    Źródło:
    Geodesy and Cartography; 2017, 66, 1; 23-44
    2080-6736
    2300-2581
    Pojawia się w:
    Geodesy and Cartography
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Deflection of Steel Reinforced Concrete Beam Prestressed with CFRP Bar
    Autorzy:
    Selvachandran, P.
    Anandakumar, S.
    Muthuramu, K. L.
    Powiązania:
    https://bibliotekanauki.pl/articles/353032.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    cracked moment of inertia
    deformability
    effective moment of inertia
    neutral axis
    Partial Prestressig Ratio
    yielding point
    Opis:
    Carbon Fiber Reinforced polymer (CFRP) bars are weak in yielding property which results in sudden failure of structure at failure load. Inclusion of non-pretensioned steel reinforcement in the tension side of CFRP based prestressed concrete beam will balance the yielding requirements of member and it will show the definite crack failure pattern before failure. Experimental investigation has been carried out to study the deflection behavior of partially prestressed beam. Experimental works includes four beam specimens stressed by varying degree of prestressing. The Partial Prestressing Ratio (PPR) of specimen is considered for experimental works in the range of 0.6 to 0.8. A new deflection model is recommended in the present study considering the strain contribution of CFRP bar and steel reinforcement for the fully bonded member. New deflection model converges to experimental results with the error of less than 5% .
    Źródło:
    Archives of Metallurgy and Materials; 2017, 62, 3; 1915-1922
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    O wartościach przestrzennych Osi Saskiej Warszawy
    On the spatial values of the Saxon Axis in Warsaw
    Autorzy:
    Kłosek-Kozłowska, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/146034.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Oś Saska
    Warszawa
    wielkoprzestrzenne założenie urbanistyczne
    wartości przestrzenne
    Saxon Axis
    Warsaw
    large-scale urban composition
    spatial values
    Opis:
    Jeśli spojrzymy na strukturę urbanistyczną Warszawy poprzez ocenę wartości historycznych założeń przestrzennych, tych które wiążą miasto z najcenniejszymi osiągnięciami urbanistyki europejskiej, to niewątpliwie w środowiskach profesjonalnych barokowe założenie Osi Saskiej znajdzie się wśród najczęściej dostrzeganych i wymienianych. Jak wiadomo, w swojej koncepcji nawiązuje ono bezpośrednio do Wersalu, gdzie rezydencja królewska, kompozycja ogrodowa i nowo rozplanowane elementy struktury miasta tworzą współosiową, wielkoprzestrzenną kompozycję o nieskończonych, dalekich zasięgach. Badania historyczne potwierdzające związek obu tych założeń, właśnie na ich wspólne odniesienia ideowe i formalne zwracają szczególną uwagę. Podkreślają "nieskończony", zachodni zasięg kompozycyjny Osi Saskiej przedłużony w układzie ról dalekiej Woli, oraz równie dalekie otwarcie w kierunku wschodnim, którego kontynuację przekraczającą wnętrze Krakowskiego Przedmieścia i skarpę dostrzega się w przedłużeniu koryta starorzecza Wisły i związkach z otwartym krajobrazem brzegu Pragi, wówczas jeszcze słabo na tym odcinku zurbanizowanym.
    Considering the urban structure of Warsaw from the point of view of the value of its historical layouts that can be classified among the pinnacles of European urban planning, the baroque composition of the Saxon Axis (Oś Saska) would undoubtedly be the one most often mentioned and admired by the professionals. The concept is known to have been directly inspired by Versaille, where the royal residence, gardens and newly planned urban structures create a large-scale composition along a common axis with a far-reaching impact. Historical research confirms the relation between these two layouts, paying particular attention to the ideological and formal references they share. It emphasises the „Infinite” westbound reach of the Saxon Axis, prolonged by the arrangement of the fields in the remote Wola district, and the equally distant opening towards the east, continued across the interior of Krakowskie Przedmieście street, crossing the escarpment, and extending into an oxbow of the Vistula river to finally dissolve in the open landscape of the riverbank in the Praga district, poorly urbanized at the time.
    Źródło:
    Kwartalnik Architektury i Urbanistyki; 2017, 62, 3; 5-42
    0023-5865
    Pojawia się w:
    Kwartalnik Architektury i Urbanistyki
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical modeling and preliminary validation of drag-based vertical axis wind turbine
    Autorzy:
    Krysiński, T.
    Buliński, Z.
    Nowak, A. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/240209.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    numerical modeling
    numerical axis wind turbine
    computational fluid dynamics (CFD)
    modelowanie numeryczne
    turbina wiatrowa
    komputerowa mechanika płynów
    Opis:
    The main purpose of this article is to verify and validate the mathematical description of the airflow around a wind turbine with vertical axis of rotation, which could be considered as representative for this type of devices. Mathematical modeling of the airflow around wind turbines in particular those with the vertical axis is a problematic matter due to the complex nature of this highly swirled flow. Moreover, it is turbulent flow accompanied by a rotation of the rotor and the dynamic boundary layer separation. In such conditions, the key aspects of the mathematical model are accurate turbulence description, definition of circular motion as well as accompanying effects like centrifugal force or the Coriolis force and parameters of spatial and temporal discretization. The paper presents the impact of the different simulation parameters on the obtained results of the wind turbine simulation. Analysed models have been validated against experimental data published in the literature.
    Źródło:
    Archives of Thermodynamics; 2015, 36, 1; 19-38
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Morphology and symbolism of trees. General habit
    Autorzy:
    Galera, Halina
    Powiązania:
    https://bibliotekanauki.pl/articles/703226.pdf
    Data publikacji:
    2007
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    plant structure
    world record holders among plants
    symbolic plant motifs
    arbor mundi
    axis mundi
    the Tree of Life
    Opis:
    Morphology is the study of the form, shape and structure of an organism. The connection between the morphology and symbolism of trees is associated with the spirituals bonds existing between humans and trees. The common terms, such as „tree”, „trunk”, „branch”, „root”, „fruit”, „flower”, „leaf” have a specific meaning in botany. In addition these terms carry various symbolic meanings. This article attempts to analyse symbolic plant motifs which were based on the morphological structure of trees. The symbolic significance of trees is associated with their specific structure: the crown represents the mystical heaven, the trunk symbolizes the earthly world, the roots extend deep into the underworld. Possibly the best known cosmic tree (arbor mundi) is the Scandinavian Ash or Yggdrasil. It also represents the axis mundi – the centre of the world. Tree-like diagrams which graphically illustrate genealogies refer to the structure of trees as well (e.g. the tree of Jesse). Trees are the largest and longest living organisms on our planet. Among the tallest trees in the world are: Sequoia sempervirens „Hyperion” from California (measuring 115,5 m), and Eucalyptus regnans „Icarus Dream” from Tasmania (97 m high). The largest tree in terms of total volume is Sequoiadendron giganteum „General Sherman” in California (1500 cubic meters). The myth of the Ultimate Lotus Tree Sidrat al-Muntaha – that marks the end of the seventh heaven is a reference to a very large tree (probably Zizyphus lotus, however its specimen are not so large). The oldest known living specimen is the „Methuselah”, a bristle cone pine Pinus longaeva in California, which is estimated to be about 5000 years old. Taxus baccata from Henryków Lubański is the oldest tree (1250 years-old) on record in Poland. Due to their long life span, trees can be seen as “monuments”, which remind the world of important events in history, eg. the sycamore tree destroyed during the terrorist attack on the World Trade Centre on September 11, 2001, whose roots were used in preparation for the sculpture honoring St. Paul’s Church. Tree symbolism also relates to changes in the appearance of trees that result from their life cycle and phenology. Trees, which lose their leaves in winter and produce new ones in spring, symbolize rebirth after death. Therefore, the cosmic tree is also called the Tree of Life. In Japanese culture the seasonal changes in the appearance of trees indicated the passage of time. In many cultures around the world trees were held sacred because they were believed to be the homes of certain gods (e.g. Ficus sycomorus in ancient Egipt, oak trees in Slavic and German legends). It should be noted, however, that the trees themselves were not the objects of worship but the gods who were thought to dwell in these trees. Nowadays the respect people have for trees stems from other reasons.
    Źródło:
    Nauka; 2007, 2
    1231-8515
    Pojawia się w:
    Nauka
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical Analysis of a Small-Size Vertical-Axis Wind Turbine Performance and Averaged Flow Parameters Around the Rotor
    Autorzy:
    Rogowski, K.
    Maroński, R.
    Piechna, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/140198.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    vertical-axis wind turbine
    aerodynamics
    computational fluid dynamics
    turbina wiatrowa o pionowej osi obrotu
    aerodynamika
    obliczeniowa dynamika płynów
    Opis:
    Small-scale vertical-axis wind turbines can be used as a source of electricity in rural and urban environments. According to the authors’ knowledge, there are no validated simplified aerodynamic models of these wind turbines, therefore the use of more advanced techniques, such as for example the computational methods for fluid dynamics is justified. The paper contains performance analysis of the small-scale vertical-axis wind turbine with a large solidity. The averaged velocity field and the averaged static pressure distribution around the rotor have been also analyzed. All numerical results presented in this paper are obtained using the SST k- ω turbulence model. Computed power coefficients are in good agreement with the experimental results. A small change in the tip speed ratio significantly affects the velocity field. Obtained velocity fields can be further used as a base for simplified aerodynamic methods.
    Źródło:
    Archive of Mechanical Engineering; 2017, LXIV, 2; 205-218
    0004-0738
    Pojawia się w:
    Archive of Mechanical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Quartz c-axis fabrics in constrictionally strained orthogneisses: implications for the evolution of the Orlica-Śnieżnik Dome, the Sudetes, Poland
    Autorzy:
    Żelaźniewicz, A.
    Kromuszczyńska, O.
    Biegała, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/138798.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    quartz c-axis
    constriction
    Augen orthogneiss
    microfabric
    Stretching Lineation
    rodding gneiss
    pseudo-girdle
    Bohemian Massif
    Masyw Czeski
    kurczenie
    gnejs
    Opis:
    The Orlica-Śnieżnik Dome (OSD), NE Bohemian Massif, contains in its core several gneiss variants with protoliths dated at ~500 Ma. In the western limb of the OSD, rodding augen gneisses (Spalona gneiss unit) are mainly L>S tectonites with a prominent stretching lineation. The few quartz LPO studies have produced somewhat discrepant results. Reexamination of these rocks revealed that texture formation was a protracted, multistage process that involved strain partitioning with changing strain rate and kinematics in a general shear regime at temperatures of the amphibolite facies (450–600°C). Quartz c-axis microfabrics show complex yet reproducible patterns that developed under the joint control of strain geometry and temperature; thus the LPOs are mixed features represented by pseudogirdle patterns. Domainal differences in quartz microfabrics (ribbons, tails, quartzo-feldspathic aggregate) are common in the Spalona orthogneisses but uncommon in the sheared migmatitic gneisses. In the latter rocks, the constrictional strain was imposed on the originally planar fabric defined by high-temperature migmatitic layering. The constrictional fabric of the Spalona gneisses may have developed in the hinge zones of kilometer-scale folds, where the elongation occurred parallel to the fold axes. Other occurrences of rodding gneisses throughout the Orlica-Śnieżnik Dome are thought to occupy similar structural positions, which would point to the significance of large-scale folds in the tectonic structure of the dome.
    Źródło:
    Acta Geologica Polonica; 2013, 63, 4; 697-722
    0001-5709
    Pojawia się w:
    Acta Geologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Six-axis control joystick based on tensometric beam
    Sześcioosiowa manetka sterująca zbudowana na belkach tensometrycznych
    Autorzy:
    Herbin, P.
    Pajor, M.
    Stateczny, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/951467.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    dynamometer
    manual control
    strain gauge beam
    multi-axis force sensor
    strain gauge sensor
    dynamometr
    manualne sterowanie
    belka tensometryczna
    wieloosiowy sensor siły
    czujnik tensometryczny
    Opis:
    Manual programming of machine tools is realized by buttons located on control panels. Currently used tools allow simultaneous movement in only one axis of the machine resulting in inefficient and unintuitive motion control. In robotics special teaching programing is used which allows the robot to memorize the coordinates and orientations during providing an effector according to defined trajectory. It is necessary to develop a multi-axis sensor with a high rigidity in order to control machines. It could allow control over the movement of group components according to the intention of the operator. This article presents the control system, which takes into account the six-axis control joystick. The paper is focused on joystick design, as well as the calibration procedure.
    Programowanie manualne maszyn technologicznych jest realizowane poprzez przyciski umiejscowione na panelach operatorskich. Stosowane narzędzia umożliwiają jednoczesny ruch tylko jedną osią maszyny. Skutkuje to nieefektywnym i nieintuicyjnym sterowaniem jej ruchem. Obecnie w robotyce stosowane jest programowanie przez nauczanie za pomocą manualnego prowadzenia robota po trajektorii i wprowadzanie współrzędnych punktów trajektorii do pamięci. Do sterowania maszyną konieczne jest opracowanie wieloosiowego sensora o dużej sztywności. Umożliwi to kontrolę ruchu zespołów maszyny zgodnie z intencją operatora. W pracy przedstawiono system kontroli, który uwzględnia manetkę sześcioosiową. Przedstawiono także proces projektowania oraz kalibracji urządzenia.
    Źródło:
    Advances in Manufacturing Science and Technology; 2016, 40, 4; 33-41
    0137-4478
    Pojawia się w:
    Advances in Manufacturing Science and Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Location-optimized aerodynamic rotor design studies and development of small wind turbines
    Autorzy:
    Lehser-Pfeffermann, Daniel
    Hamman, Alexander
    Rückert, Frank Ulrich
    Powiązania:
    https://bibliotekanauki.pl/articles/2091356.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    small wind turbine
    fluid
    energy machines
    vertical axis wind turbine
    additive manufacturing
    fibre-reinforced composites
    computational fluid dynamics
    large eddy simulation
    turbulence
    simulation
    Opis:
    Local wind conditions can vary strongly depending on the landmark and vegetation, as well as on the skyline of the buildings in an urban surrounding. Weather, season and time of day influence the yield of electric power. In order to promote the use of small wind turbines as an alternative to photovoltaic power generation, design optimization for location-optimized small wind turbines was carried out. In this work, we want to concentrate on vertical axis wind turbines. Experimental studies, as well as numerical simulations, have been conducted. On the one hand, bionically optimized core structures will be integrated and implemented in the hybrid material of the turbine blades. Several optimization attempts have been examined for single blades. Detailed simulative investigations with large eddy simulations improve the aerodynamic behaviour of the new rotor design. Finally, based on the results of the studies and investigations, a new rotor will be manufactured and tested experimentally in the wind tunnel. A comparison with the reference system from the first part of the paper shows the improvements and effectiveness of the measures and processes investigated.
    Źródło:
    Archives of Thermodynamics; 2022, 43, 1; 3--19
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Three-dimensional air velocity distributions in the vicinity of a mine heading’s sidewall
    Trójwymiarowe rozkłady wektora prędkości powietrza w strefie przyociosowej wyrobiska górniczego
    Autorzy:
    Skotniczny, P.
    Ostrogórski, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/218826.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    sonda termoanemometryczna trójwłóknowa
    pomiar profilu prędkości w wyrobisku górniczym
    walidacja rozwiązania numerycznego
    3-axis thermoanemometric probe
    velocity profile measurement in mine heading
    numerical solution validation
    Opis:
    The presented paper describes the results of an experiment determining the instantaneous values of velocity vector components of the air stream at selected spots of the boundary layer formed at the sidewalls of the mine heading in the ŁP type steel arch support. The experiment was carried out in a mine heading in an active hard coal mine. A 3-axis thermoanemometric probe was used to obtain three-dimensional distributions of the velocity and turbulent values, such as turbulence intensity and turbulent kinetic energy of the flowing ventilation air stream. The analysis of the measurement results was aided by a numerical solution of the discussed case of flow. The research results presented in this paper provide a basis for extensive studies of the description of velocity distribution and other turbulent quantities within the near-sidewall structures of a mine heading. The objective of these tasks is to improve the accuracy and reliability of numerical calculations relating to air flow in mine headings.
    W artykule opisano wyniki eksperymentu polegającego na wyznaczeniu chwilowych wartości składowych wektora prędkości strugi powietrza w wybranych punktach warstwy przyściennej tworzącej się przy ociosach wyrobiska górniczego prowadzonego w obudowie typu ŁP. Eksperyment przeprowadzono w wyrobisku górniczym w czynnej kopalni węgla kamiennego. Przy pomocy trójwłókowej sondy termoanemometrycznej uzyskano trójwymiarowe rozkłady prędkości oraz rozkłady wielkości turbulentnych takich jak intensywność turbulencji i energia kinetyczna turbulencji przepływającej strugi powietrza wentylacyjnego. Analiza wyników pomiarów została wzbogacona rozwiązaniem numerycznym omawianego przypadku przepływowego. Przedstawione w artykule wyniki badań stanowią podstawę rozbudowanych studiów nad opisem rozkładu prędkości oraz pozostałych wielkości turbulentnych w obrębie struktur przyociosowych wyrobiska górniczego. Celem podjętych prac jest poprawa dokładności i rzetelności obliczeń numerycznych przepływu powietrza w wyrobiskach górniczych.
    Źródło:
    Archives of Mining Sciences; 2018, 63, 2; 335-352
    0860-7001
    Pojawia się w:
    Archives of Mining Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Determining horizontal curvature of railway track axis in mobile satellite measurements
    Autorzy:
    Koc, Władysław
    Wilk, Andrzej
    Specht, Cezary
    Karwowski, Krzysztof
    Skibicki, Jacek
    Czaplewski, Krzysztof
    Judek, Sławomir
    Chrostowski, Piotr
    Szmagliński, Jacek
    Dąbrowski, Paweł
    Specht, Mariusz
    Grulkowski, Sławomir
    Licow, Roksana
    Powiązania:
    https://bibliotekanauki.pl/articles/2086882.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    GNSS measurements
    railway track axis
    horizontal curvature
    moving chord method
    application
    accuracy assessment
    pomiary GNSS
    tor kolejowy
    oś
    krzywizna pozioma
    metoda ruchomej cięciwy
    zastosowanie
    ocena dokładności
    Opis:
    The article discusses the applicability of a novel method to determine horizontal curvature of the railway track axis based on results of mobile satellite measurements. The method is based on inclination angle changes of a moving chord in the Cartesian coordinate system. In the presented case, the variant referred to as the method of two virtual chords is applied. It consists in maneuvering with only one GNSS (Global Navigation Satellite System) receiver. The assumptions of the novel method are formulated, and an assessment of its application in the performed campaign of mobile satellite measurements is presented. The shape of the measured railway axis is shown in the national spatial reference system PL-2000, and the speed of the measuring trolley during measurement is calculated based on the recorded coordinates. It has been observed that over the test section, the curvature ordinates differ from the expected waveform, which can be caused by disturbances of the measuring trolley trajectory. However, this problem can easily be overcome by filtering the measured track axis ordinates to obtain the correct shape – this refers to all track segments: straight sections, circular arcs and transition curves. The virtual chord method can also constitute the basis for assessing the quality of the recorded satellite signal. The performed analysis has shown high accuracy of the measuring process.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 6; e139204, 1--10
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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