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    Wyświetlanie 1-8 z 8
    Tytuł:
    Micaceous iron oxide production by application of magnetic separation
    Autorzy:
    Tanriverdi, M.
    Sen, S.
    Ciçek, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/110370.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    micaceous iron oxide (MIO)
    magnetic separation
    belt type high gradient magnetic separator
    high gradient magnetic separator
    pulsating high gradient magnetic separator
    Opis:
    In this study, different flowsheet options were evaluated to achieve the best upgrading conditions for a micaceous iron oxide ore. The first option included the recovery of micaceous iron oxide particles using a double stage magnetic separation circuit after the grinding and classifying of the ore into coarse (-1000+106 μm) and fine (-106 μm) size fractions. A belt type dry high gradient magnetic separator (BHGMS) was used to beneficiate the coarse fraction. The concentrate of the BHGMS was ground to -106 μm, and combined with the fine fraction produced at screening stage, and subjected to high gradient magnetic separation (HGMS) at 1.2 T. A concentrate grading about 61.33% Fe with 60.3% recovery was obtained applying the separation process incorporating BHGMS and HGMS. A single stage separation circuit considering the use of HGMS after the grinding the ore below 106 μm was employed as the second concentration option. A concentrate having 63.80% Fe with 37.1% weight recovery was obtained in this test. As the highest Fe grade and the lowest S concentration was obtained by application of HGMS after the grinding the ore below 106 μm, and it was decided to conduct a pilot scale study using pulsating HGMS. A concentrate assaying 69.45% Fe with 60.1% weight recovery was produced by operating the pulsating HGMS at 0.6 T. The results showed that it was possible to obtain a micaceous iron oxide concentrate to be used in pigment production using magnetic separation method.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 2; 546-553
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Different approaches to phase restoration of distant complex optical fields
    Autorzy:
    Zenkova, C. Y.
    Gorsky, M P
    Ryabiy, P A
    Gruia, I
    Powiązania:
    https://bibliotekanauki.pl/articles/173605.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    phase skeleton
    saddle points
    gradient lines
    Opis:
    The paper presents principal approaches to diagnosing the structure forming skeleton of the complex optical field. An analysis of optical field singularity algorithms depending on intensity discretization and image resolution has been carried out. An optimal approach is chosen, which allows to bring much closer the solution of the phase problem of localization of speckle-field special points. A possible approach to diagnosing the signs of zero amplitudes has been offered.
    Źródło:
    Optica Applicata; 2015, 45, 2; 139-150
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modelling of vertical-cavity surface-emitting laser beam collimation using a nanostructured gradient index microlens
    Autorzy:
    Nowosielski, J M
    Waddie, A. J.
    Taghizadeh, M. R.
    Buczynski, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/174429.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    gradient index optics
    microlens
    soft glass
    Opis:
    In this paper we show that the recently developed nanostructured gradient index (nGRIN) rod microlens can be utilised for the collimation of the beam generated by a vertical-cavity surface-emitting laser (VCSEL). The modelling of the nanostructured lens structure is performed using the finite difference time domain (FDTD) method with realistic nGRIN parameters and a Gaussian model of the light source. The large refractive index gradient of the nanostructured microlens allows the final microlens thickness to be only 70 μm with a diameter of 10 μm. Successful collimation of a single-mode VCSEL beam with a waist half-width of 1.53 μm is presented with a reduction in divergence half-angle from 10.1° to 3.3°. We show that the linear polarisation of the incident beam is preserved as well as presenting the tolerance of this type of lens to variations in overall thickness.
    Źródło:
    Optica Applicata; 2013, 43, 4; 761-772
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Global stability for double-diffusive convection in a couple-stress fluid saturating a porous medium
    Autorzy:
    Choudhary, Shalu
    -, Sunil
    Powiązania:
    https://bibliotekanauki.pl/articles/949858.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    couple-stress parameter
    solute gradient
    Brinkman number
    Opis:
    We show that the global non-linear stability threshold for convection in a double-diffusive couplestress fluid saturating a porous medium is exactly the same as the linear instability boundary. The optimal result is important because it shows that linearized instability theory has captured completely the physics of the onset of convection. It is also found that couple-stress fluid saturating a porous medium is thermally more stable than the ordinary viscous fluid, and the effects of couple-stress parameter (F ) , solute gradient (S f ) and Brinkman number (Da ) on the onset of convection is also analyzed.
    Źródło:
    Studia Geotechnica et Mechanica; 2019, 41, 1; 13-20
    0137-6365
    2083-831X
    Pojawia się w:
    Studia Geotechnica et Mechanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optical gradient force of cosh-Gaussian with sine-azimuthal and half-space phase modulation
    Autorzy:
    Fu, R.
    Gao, X.
    Shen, H.
    Xin, Q
    Lu, X.
    Guo, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/173789.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    optical gradient force
    cosh-Gaussian beams
    wavefront modulation
    Opis:
    The optical gradient force distributions in focal plane of cosh-Gaussian beams with sine-azimuthal variation wavefront and half space phase modulation were investigated. Results show that optical gradient force distributions can be affected considerably by the phase retardation of half-space phase modulation, of a phase parameter that indicates the phase change frequency on an increasing azimuthal angle, and beam parameters in cosh terms of the incident beams. Many gradient force patterns occur, including cross-shape, multiple optical trap arrays, multiple-trap wheel, and many kinds of gradient force lines and curves. Symmetry of the whole gradient force pattern can also be altered remarkably. Above results may find wide applications in optical trapping systems.
    Źródło:
    Optica Applicata; 2013, 43, 4; 719-730
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Gradient composite materials for artificial intervertebral discs
    Autorzy:
    Migacz, K.
    Chłopek, J.
    Morawska-Chochół, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/306718.pdf
    Data publikacji:
    2014
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    kompozyty
    materiał gradientowy
    krążek międzykręgowy
    composite
    gradient material
    intervertebral disc replacement
    Opis:
    Composites with the gradient of the Young’s modulus constitute a new group of biomimetic materials which affect the proper distribution of stresses between the implant and the bone. The aim of this article was to examine the mechanical properties of gradient materials based on carbon fibre-polysulfone composite, and to compare them to the properties of a natural intervertebral disc. Gradient properties were provided by different orientation or volume fraction of carbon fibres in particular layers of composites. The results obtained during in vitro tests displayed a good durability of the gradient materials put under long-termstatic load. However, the configuration based on a change in the volume fraction of the fibres seems more advantageous than the one based on a change of the fibres’ orientation. Studied materials were designed to replace the intervertebral disc. The effect of the Young’s modulus of the material layers on the stress distribution between the tissue and the implant was analyzed and the biomimetic character of the gradient composites was stated. Unlike gradient materials, the pure polysulfone and the non-gradient composite resulted in the stress concentration in the region of nucleus pulposus, what is highly disadvantageous and does not occur in the stress distribution of natural intervertebral discs.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2014, 16, 3; 3-12
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of the Collapse Gradient of Deep Water Horizontal Wellbore and the Effects of Mud Chemical Activity and Variation in Water Depth
    Autorzy:
    Dosunmu, Adewale
    Nwonodi, Roland I.
    Ekeinde, Evelyn
    Powiązania:
    https://bibliotekanauki.pl/articles/1845117.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    Mogi-Coulomb criterion
    collapse gradient
    horizontal well
    deep water
    chemical activity
    Opis:
    Wellbore collapse is an instability-event that occurs at low mud density and leads to unfavorable economic project, reaching billions of US dollars. Thus, it is important to accurately determine its value, especially in deepwater horizontal wellbores. The main reasons for nontrivial problems with such wellbores are evident: the shale encountered are anisotropic in nature and possess planes of weakness; they react with water-based mud, generate osmotic stresses, swell, and fall unto the wellbore bottom, thereby increasing the non-productive time. To this end, salts are added to reduce the collapse tendency, but it is not currently known what amount of salt addition maintains stability, and does not lead to wellbore fracture; in deepwater, the current trend in global warming means there is a future concern to the industry. As the climate temperature increases, more ice melts from the polar region, the seawater expands and the sea level rises. How to incorporate the corresponding effect on collapse gradient is scarcely known. This study captures the major concerns stated above into wellbore stability analysis. Following the classical approach for geomechanical analysis, Mogi-Coulomb criterion was combined with a constitutive stress equation comprising contributions from mechanical and osmotic potentials of mud and shale. A sophisticated industry model was used to consider the deepwater effect. The results show significant reduction in collapse gradient as the water depth increases, also, larger difference between the mud and shale chemical activities represents higher complexities in the wellbore. In addition, the reduction in the chemical activities of mud limited to 37.5% of the initial value can be practically safe.
    Źródło:
    Studia Geotechnica et Mechanica; 2020, 42, 3; 232-241
    0137-6365
    2083-831X
    Pojawia się w:
    Studia Geotechnica et Mechanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fiber diameter influence on optical transport of dielectric particles along subwavelength optical fibers
    Autorzy:
    Zhang, Y.
    Lei, H.
    Li, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/173195.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    optical transport
    optical scattering force
    optical gradient force
    subwavelength optical fiber
    evanescent field
    Opis:
    We investigate a fiber diameter influence on optical transport of dielectric particles along subwavelength optical fibers using a near infrared laser of 1.55 μm wavelength. Theoretical analysis indicates that at 1.55 μm, the evanescent field at the fiber surface increases at first and then decreases with an increase of the fiber diameter from 600 nm to 1.6 μm, exhibiting a maximum at the fiber diameter of 950 nm. Based on three-dimensional finite-difference time-domain simulations, optical scattering forces acted on the dielectric particles and transport velocities of the particles were calculated for two fibers in the diameters of 930 nm and 1.5 μm. To support the theoretical analysis, experiments were performed using the two fibers to transport SiO2 particles (sizes of 530 nm and 1.5 μm) and TiO2 particles (size of 1.5 μm). The results show that with the same laser power launched into the two fibers, larger transport velocities can be obtained along the 930 nm diameter fiber.
    Źródło:
    Optica Applicata; 2013, 43, 4; 707-718
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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