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Wyświetlanie 1-9 z 9
Tytuł:
Inclinometer monitoring system for stability analysis: the western slope of the Bełchatów field case study
Autorzy:
Cała, M.
Jakóbczyk, J.
Cyran, K.
Powiązania:
https://bibliotekanauki.pl/articles/178913.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
slope inclinometer
geotechnical monitoring
horizontal displacement analysis
exploitation influence
Bełchatów open pit mine
Opis:
The geological structure of the Bełchatów area is very complicated as a result of tectonic and sedimentation processes. The long-term exploitation of the Bełchatów field influenced the development of horizontal displacements. The variety of factors that have impact on the Bełchatów western slope stability conditions, forced the necessity of complex geotechnical monitoring. The geotechnical monitoring of the western slope was carried out with the use of slope inclinometers. From 2005 to 2013 fourteen slope inclinometers were installed, however, currently seven of them are in operation. The present analysis depicts inclinometers situated in the north part of the western slope, for which the largest deformations were registered. The results revealed that the horizontal displacements and formation of slip surfaces are related to complicated geological structure and intensive tectonic deformations in the area. Therefore, the influence of exploitation marked by changes in slope geometry was also noticeable.
Źródło:
Studia Geotechnica et Mechanica; 2016, 38, 2; 3-13
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of low-field NMR in the study of flocculant-aided filtration process of coal tailings
Autorzy:
Guo, Zhimin
Liang, Long
Hu, Pengfei
Powiązania:
https://bibliotekanauki.pl/articles/1447424.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
filtration
coal tailings
NMR
flocculation
inherent moisture
Opis:
Preconditioning of coal tailings with flocculants is a useful technology to improve filtration performance. In this study, anionic and cationic polyacrylamides were used for the pretreatment coal tailings before filtration. Nondestructive and rapid measurement of the filter cakes of coal tailings at different filtration stages was conducted using a nuclear magnetic resonance (NMR). The transverse relaxation time (T2) results of NMR provided the information concerned the state of water in filter cake, showing that free water entrapped in larger pores was removed mainly during coal tailings filtration, and the pressure in this study cannot remove the inherent moisture of filter cake of coal tailings. The significant increase in the amplitude of T2 value between 0.1 and 1.0 ms revealed that the flocs collapsed into smaller ones with water entrapped in them during filtration. Comparing the NMR results with different flocculants shows that anionic polyacrylamide of 800 g/Mg produced a larger structure in the initial stage of filter cake formation. The final filter cake entrapped more water. The NMR results well validated the filtration experiments.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 3; 1-7
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of prototype multi-pole non-salient field winding for high speed brushless synchronous generator
Autorzy:
Kutt, F.
Kostro, G.
Michna, M.
Ronkowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1813550.pdf
Data publikacji:
2012
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
synchronous generator
non-salient field winding
high speed
brushless excitation
autonomous electrical power system
Opis:
In this paper a non-salient field winding for a brushless synchronous generator working with high speed in an autonomous energy generation system (e.g. airplane power grid) has been presented. A conception of a six-pole cylindrical-rotor with distributed field winding has been proposed. Comparison study of salient and prototype non-salient field winding has been carried out. Chosen simulation and measurement results of the generator stator voltage and current waves have been presented.
Źródło:
Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały; 2012, 66, 32; 273-278
1733-0718
Pojawia się w:
Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental study of quartz classification in the enhanced gravity field using Falcon concentrator
Autorzy:
Zhang, Ling
Yang, Lu
Hou, Haochun
Zhao, Yan
Lin, Jun
Zhang, Zeliang
Bu, Caiyun
Zheng, Xinran
Fu, Dong
Powiązania:
https://bibliotekanauki.pl/articles/27323652.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
classification
enhanced gravity field
fine particles
fish-hook
Opis:
The classification and separation of minerals happen in the traditional gravity separation simultaneously. This paper focuses on the classification performance of quartz particles in the enhanced gravity field. The classification efficiency of single quartz particles decreased then increased with the increase of rotational angular velocity, while it decreased with the increase of backwash water pressure. The classification efficiency of -0.5 +0.25mm, -0.25 +0.125mm, -0.125 +0.074mm, -0.074 +0.045mm and -0.045mm quartz was higher than the corresponding narrow size of -0.5mm quartz in general. The “fish-hook” phenomenon appeared in the partition curve of -0.5mm quartz under small/large rotational angular velocity and small backwash water pressure, and the dip point could be found in fine particles region, which indicated that the “fish-hook” was closely related with operating parameters and particle size. A medium rotational angular velocity and larger backwash water pressure could be helpful to avoid the appearance of “fish-hook” in fine particles region and achieve a better classification performance. This investigation is beneficial to understand the regularity of particle migration in the enhanced gravity field.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 6; art. no. 175242
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental and numerical study on the classification of a cyclonic field in a flotation column
Autorzy:
Li, Xiaoheng
Li, Xiao
Yan, Xiaokang
Wang, Lijun
Zhang, Haijun
Powiązania:
https://bibliotekanauki.pl/articles/109487.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
computational fluid dynamics
cyclonic flow field
cyclonic-static micro-bubble flotation column
particle size distribution
Opis:
The cyclonic-static micro-bubble flotation column (FCSMC) performs well in fine mineral flotation. Compared to traditional flotation columns, its design innovatively introduces a cyclonic structure. The separation of middling and tailing occurs in the cyclonic flow field induced by a cyclonic reversal cone. In this study, the particle size distribution analysis and computational fluid dynamics (CFD) simulations were conducted to reveal the particle distribution law and the classification mechanism in cyclonic flow fields under different circulation pressures. The results showed that particle size showed the same distribution tendency as tangential velocity in the radial direction: both increase from the center and decrease around the wall. As circulation flux increased, the tangential velocity increased, and the particle size differences in the radial direction also increased. The position of the largest particles will move to outside as the largest value of tangential velocity migrates the outward in the radial direction. According to the particle size distribution of the feed, it can be adjusted to the flow field to change the particle distribution, thereby improving the efficiency of separation. This study has an important guiding significance for column design and adjustment of the operating parameters of the flotation process.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 3; 421-431
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on feature extraction and dynamic properties of bubbles in a liquid-phase flow field
Autorzy:
Peng, Deqiang
Dong, Xianshu
Fan, Yuping
Ma, Xiaomin
Powiązania:
https://bibliotekanauki.pl/articles/109400.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
bubbles
image processing
trajectory
probability distribution of diameter
terminal velocity
Opis:
To study the dynamic properties of bubbles generated at different air pressures in a liquid-phase flow field, this paper adopted high-speed camera technology and image processing techniques to extract and calculate the features of bubbles. The results showed that in a deionized water field, the bubbles generated at the air pressure of 0.1 MPa had an average diameter of 4.50 mm, and the bubbles generated at the air pressures of 0.2 MPa and 0.3 MPa had average diameters of 5.74 mm and 5.76 mm respectively; notwithstanding the insignificant differences in average data, the probability distribution of bubble diameter had significant differences with different pressures. During the rise of bubbles, their motion trajectory witnessed an increased amplitude of swing with the increase of air pressure; the bubbles generated at different air pressures did not show any significant differences in rising velocities though.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 1; 268-277
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on condition prediction and influencing factors of manganese carbonate recovery by high gradient pulse magnetic separation
Autorzy:
Wang, Zhenggang
Nie, Guanghua
Tang, Yun
Piao, Haishan
Chen, Jian
Powiązania:
https://bibliotekanauki.pl/articles/24085829.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
mineral particles
impulse
volume susceptibility
magnetic field strength
DLVO theory
Opis:
Manganese carbonate ore belongs to weakly magnetic minerals, and its co-associated minerals are mainly non-magnetic minerals, which can be separated from gangue minerals at high magnetic field intensity. However, manganese grade and recovery of magnetic separation concentrate of manganese carbonate ore are low in actual production. Therefore, the influences of manganese carbonate particle size, magnetic field intensity, volume susceptibility, pulse stroke, pH, and other factors were studied. The optimal test conditions for manganese carbonate ore recovery by high-gradient magnetic separation were predicted through the calculation results. The results show that the particle radius of manganese carbonate is 0.020 mm, the pulse impulse time is 200 r/min, and the magnetic field intensity is 0.9 T. The optimum condition test was carried out with Qianbei manganese carbonate ore as the material. The test results show that the optimum conditions are the particle radius of 0.074-0.019 mm, pulse impulse time of 200 r/min, and magnetic field intensity of 1.2 T. The reason for the deviation is that the actual ore has a fine distribution particle size, many associative bodies, complex composition, and serious agglomeration, resulting in variable particle volume susceptibility. The capture yield increases with the increase of magnetic field intensity and volume susceptibility but decreases with the increase of pulse. The lower the surface potential of manganese carbonate, the higher the recovery of manganese carbonate. The grade of manganese concentrate was 19.06% and the recovery was 76.85%. Mixed manganese concentrate with a grade of 18.04% and recovery of 87.14% was obtained by adding drugs and changing the grinding method.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 3; art. no. 168668
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on the floc-bubble adhesion behavior of hematite in static flow field
Autorzy:
Zhang, Jinxia
Feng, Hongjun
Niu, Fusheng
Sun, Weiguang
Zhao, Yawei
Powiązania:
https://bibliotekanauki.pl/articles/1449769.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
bubble
floc
adhesion
charge-coupled device (CCD) camera
Derjaguin-Landau-Verwey-Overbeek (DLVO) theory
Opis:
To investigate the adhesion of hematite flocs to gas bubbles in floc floatation, this paper develops an observation system for floc-bubble collision and adhesion with two charge-coupled device (CCD) cameras. The sizes of flocs and bubble were 45.36μm and 0.90mm, respectively, and the distance between a floc and the bubble center (sedimentation distance) was set to 0.25cm. Three surfactants, namely, sodium oleate, lauryl amine and sodium dodecyl sulfate (SDS), were selected for our research. Several experiments were conducted to disclose how surfactant concentration and pH affect the surface adhesion between hematite flocs and bubbles. Then, the adhesion mechanism was discussed in details based on the experimental results. The results show that the highest adhesion probability was achieved for the said floc and bubble at the lauryl amine concentration of 8mg/L, the sedimentation distance of 0.25cm and the pH of 9. After touching the bubble, the hermamite floc slid on the bubble surface, forming a stable three-phase interface after 67ms. Then, the radial position of the floc no longer changed, despite the floc motion on the bubble surface. According to the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and the potential energy of the van der Waals force, there was a repulsive force between the floc and the bubble in the absence of surfactant and an attractive force in the presence of the surfactant of lauryl amine. In addition, a thin solvation shell is conducive to the adhesion between the floc and the bubble.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 1; 124-133
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A field study to evaluate the runoff quantity and stormwater retention of a typical extensive green roof in Bahçeköy, Istanbul
Autorzy:
Ekşi, M.
Powiązania:
https://bibliotekanauki.pl/articles/207174.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
dachy
zielone dachy
architektura krajobrazu
retencja wód burzowych
obszar miejski
odpływ wód deszczowych
roofs
green roofs
landscape architecture
rainfall
stormwater retention
stormwater runoff
Opis:
mpervious surfaces in urban areas are increasing as a result of urbanization and development. Roof surfaces constitute a large portion of impervious cover in cities. Within the scope of the sustainability principle and urban policies in the world, water retention benefits of the green roofs to the urban environment have been assessed with various academic studies. In recent years, green roof systems are being used to reduce stormwater runoff in urban areas. In the research, main aim was to determine the rainfall-runoff relationship of a typical extensive green roof with 50 mm thick substrate and to perform comparisons with an unvegetated roof based on field measurements. Hydrological performance of green roofs such as water retention and runoff delay were investigated in local climate of Bahcekoy, Istanbul. Through comparative field measurements at Istanbul University Faculty of Forestry Landscape Architecture Department, Green Roof Research Station (IUGRRS), stormwater retention performance of green roofs was investigated in terms of sustainability. From the derived data, moisture changes in the substrate, outdoor environment interactions and the runoff characteristics of the green roofs were evaluated. According to rainfall characteristics, a typical extensive green roof system delayed the runoff between 1 to 23 h in several rain events and prevented the runoff between 12.8% and 100%. Overall, green roof systems may provide an alternative and sustainable solution for the impervious roof surfaces in cities.
Źródło:
Environment Protection Engineering; 2013, 39, 4; 79-89
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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