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Wyświetlanie 1-15 z 67
Tytuł:
Experimental research on energy-size distribution model of coal particle bed comminution
Autorzy:
Zhou, Qiang
Guo, Qing
Pan, Yongtai
Zhu, Changyong
Wei, Yinghua
Powiązania:
https://bibliotekanauki.pl/articles/1845226.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
coal
particle bed comminution
extended G-S distribution
JK size-dependent breakage model
mathematical modelling
Opis:
In order to accurately predict the particle size distribution (PSD) of coal particle bed comminution under different applied pressures, the tests of two kinds of coal with four size fractions under five different applied pressures were carried out by TAW-3000 hydraulic servo testing machine. The Gaudin-Schumann(G-S) distribution is extended by the fractal theory and the JK size-dependent breakage model is discussed. Two mathematical models for predicting PSD of crushing products in coal particle bed comminution are proposed. Results show that the relationship between the mass-specific energy and applied pressure is linear. Because of the protective effect of fine particles, the change of particle size modulus d0 in G-S distribution is not significant, while the distribution parameter α decreases logarithmically with the increase of mass-specific energy. With the decrease of size fraction, the crushability of coal particle bed decreases, and a master curve can be used to fit the comminution characteristics of coal particle bed with different size fractions. The extended G-S distribution model and the JK size-dependent breakage model have better fit the results of coal particle bed comminution. This research provides a useful reference for the mathematical modelling of coal particle bed comminution.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 5; 772-783
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Remediation of acid generating colliery spoil using steel slag – case studies
Autorzy:
Ghataora, G. S.
Ghazireh, N.
Hall, N.
Powiązania:
https://bibliotekanauki.pl/articles/178856.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
colliery spoil
steel slag
limestone quarry fines
remediation of acidity
Opis:
One of the legacies of the coal mining industry is the existence of numerous colliery spoil mounds. Run-off waters from some of these mounds result in oxidation of sulphur compounds causing pH to drop to perhaps as low as 2.5. At this pH, mobility for metals increases and it results in destruction of both flora and fauna. In order to reduce acidity, a number of solutions have been investigated with varying degree of success. A recent study to reduce acidity in spoil run-off water included the use of Basic Oxygen Steel slag. Its slow release of lime resulted in longer term remediation compared with other techniques. In addition to this, steel slag contains elements which are essential for plant growth and can be regarded as a weak fertiliser. This was substantiated in two field trials, which had the aim of not only remediating acidity from two different types of colliery spoils, but also to develop a composition that supports grass growth. The objectives were achieved at both sites and some of the results of over 5000 chemical tests conducted during these studies are reported in this paper.
Źródło:
Studia Geotechnica et Mechanica; 2015, 37, 2; 75-84
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Physical and mathematical model of the digital coherent optical spectrum analyser
Autorzy:
Kolobrodov, V. G.
Tymchyk, G. S.
Mykytenko, V. I.
Kolobrodov, M. S.
Powiązania:
https://bibliotekanauki.pl/articles/174296.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
optical spectrum analyzer
optical correlator
spatial light modulator
matrix detector
Opis:
A physical and mathematical model of digital coherent optical spectrum analyzers is discussed. In digital coherent optical spectrum analyzers the input signal is forming as a two-dimensional transparency by means of a spatial light modulator. After Fourier transformation with a lens, multiplication by a spatial filter and second Fourier transformation, the signal is captured by a matrix detector for further computer processing. A lot of digital coherent optical spectrum analyzers and their components (laser, lighting system, spatial light modulator, Fourier lens and matrix detector) models were developed to calculate the signal at the matrix detector output. They use the impulse response and transfer function to evaluate the effectiveness of digital coherent optical spectrum analyzers. The analysis of mathematical relationships shows that the use of a discrete spatial light modulator for the signal input and a matrix detector for light field registration in the spectral domain when combined with computer technology greatly extends the functionality of digital coherent optical spectrum analyzer. The formulas for impulse response and transfer function calculations were obtained, which allows to analyze and optimize the digital coherent optical spectrum analyzer basic characteristics.
Źródło:
Optica Applicata; 2017, 47, 2; 273-282
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of temperature during ultrasonic conditioning in quartz-amine flotation
Autorzy:
Gungoren, C.
Ozdemir, O.
Ozkan, S. G.
Powiązania:
https://bibliotekanauki.pl/articles/110129.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
quartz
amine
flotation
ultrasound
temperature effect
Opis:
In this study, the effect of ultrasound on flotation recovery of quartz-amine flotation was investigated in terms of temperature influence. For this purpose, an ultrasonic probe was used for conditioning quartz surfaces in presence of dodecylamine hydrochloride (DAH), and the change in the temperature was recorded. The temperature-controlled ultrasonic conditioning tests were also carried out at various ultrasonic powers (30, 90, and 150 W) to investigate the effect of increasing temperature on the quartz-DAH flotation. The results showed that temperature of the suspension sharply increased from 23 up to 75 °C at the end of 10 min of conditioning at 150 W ultrasonic power. The flotation results for the temperature controlled and uncontrolled samples indicated that the flotation recovery increased from 45 to 65% by 90 W ultrasonic power. However, higher ultrasonic power levels affected the flotation recovery negatively. On the other hand, the ultrasonic application decreased the flotation recovery at all ultrasonic power levels in the temperature-controlled tests. Finally, the shape analysis was also performed for the particles treated with the ultrasound at various ultrasonic powers. As a conclusion, the positive effect of ultrasound on the quartz-amine flotation recovery could be related to temperature increase during conditioning.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 2; 687-698
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Recovery of trace elements with uranium and thorium from yatagan thermal power plant fly ashes by leaching
Autorzy:
Kursun, I.
Ozkan, S. G.
Kilic, A.
Terzi, M.
Enkhtaivan, N.
Powiązania:
https://bibliotekanauki.pl/articles/110591.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
uranium
thorium
leaching
fly ash
Opis:
In this paper, characterization of fly ashes obtained from the Yatagan Thermal Power plant, Mugla, Turkey was performed in order to determine their radioactive element contents, especially uranium and thorium. The representative fly ash samples were subjected to hydrochloric acid (HCl) leaching considering solid concentration, acid dosage, leaching time and temperature in order to reach certain uranium and thorium recoveries. The obtained results showed that the optimum conditions for leaching tests were: 30% solid concentration, 2.36 mmol/dm3 HCl addition, 240 min leaching time and 40 oC temperature. Dissolution efficiencies for uranium and thorium from the Yatagan Thermal Power Plant fly ashes were calculated as 90.12 and 81.18%, respectively.
Źródło:
Physicochemical Problems of Mineral Processing; 2016, 52, 2; 588-596
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Disparity servoing based fast autofocusing method for stereomicroscope
Autorzy:
Liu, Y.
Yu, M.
Cui, L.
Jiang, G.
Wang, G.
Fan, S.
Powiązania:
https://bibliotekanauki.pl/articles/174449.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
autofocusing
stereomicroscope
stereomicroscopic images
disparity
Opis:
A disparity servoing based fast autofocusing method is proposed for stereomicroscopes according to linear relationship between the disparity change in stereomicroscopic images and the move distance of a motorized translation stage. For a certain stereomicroscope, the calibration of a disparity range of clear images at each magnification is implemented offline. After that, the disparity of the stereomicroscopic image is used as an index to represent the sharpness of an arbitrary image. If the disparity does not satisfy the requirement, move steps and direction of a step motor are calculated by utilizing the linear relationship between the disparity change and the move distance of the stage. The iteration will be continued until the disparity of the captured stereomicroscopic image approximates to the clearest disparity. The experimental results show that the proposed method only requires a few iterations and less time to reach the focus position, and the disparity error is less than 0.5 pixel.
Źródło:
Optica Applicata; 2016, 46, 4; 651-663
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of operating pressure and stand-off distance on coal comminution by waterjet
Autorzy:
Li, Y.
Galecki, G.
Şen, G. A.
Şen, S.
Powiązania:
https://bibliotekanauki.pl/articles/110840.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
coal
waterjet
comminution
particle size distribution
Opis:
Comminution of coal to ultrafine sizes by high-pressure waterjet coupled with cavitation cell provides a novel method for preparation of coal-water fuels for next generation, near-zero emission electric power generation. To establish the fundamental performance of the waterjet mill, the effects of the operating pressure and stand-off distance were comprehensively investigated using a high ash bituminous coal. The comminution products were evaluated in terms of the particle size, particle size distribution, and surface area change. The experimental results indicated that the waterjet-mediated comminution of coal was strongly affected by all these operating parameters. Higher operating pressure led to finer products, while the efficiency of the waterjet mill in terms of particle size strongly depended on the stand-off distance. This research provides a deeper insight into the high-pressure waterjet for coal comminution and a basis for process parameter optimization.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 1; 394-401
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Drainage adits in Upper Silesia – industrial technology heritage and important elements of the hydrotechnical infrastructure
Autorzy:
Duży, S.
Dyduch, G.
Preidl, W.
Stacha, G.
Powiązania:
https://bibliotekanauki.pl/articles/178184.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
heading
drainage adit
hydrotechnical infrastructure
heading stability
Opis:
Adits played an important role in the hydrotechnical infrastructure for centuries. Initially, they were used mainly to drain wetland and supply water to the population. There were also inherent in the conduct of mining activities. They were used as exploratory, development and supply headings. Their usual function was to drain, ventilate and transport, and after the cessation of mining they became important elements of the hydrotechnical infrastructure in the transformed mining areas. The article presents issues related to the revitalization of the Main Key Hereditary Adit and Friedrich Adit as essential for the areas in which they are located. Both are hydraulic structures with the possibility of adaptation for tourism purposes. The need to consider some technical activities to be undertaken in this type of objects was pointed out, not only including aspects related to their proper protection so that they can continue to safely perform their function, but also to the preservation of their historical values. Due to their age and the method of drilling used in them, those headings are often included in the list of monuments and protected by law.
Źródło:
Studia Geotechnica et Mechanica; 2017, 39, 4; 25-34
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of viscosity on the far-field diffraction pattern of spatial self-phase modulation
Autorzy:
Nibu, A. G.
Silpa, S. S.
Ardra, S. N.
Anisha, M. M.
Ambika, D.
Powiązania:
https://bibliotekanauki.pl/articles/174699.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
self-phase modulation
nonlinear refractive index
chlorophyll
engine oil
Opis:
Effect of viscosity of a liquid on the far-field diffraction pattern due to spatial self-phase modulation is investigated. Chlorophyll extract in acetone at different concentrations is used as the low viscous nonlinear samples and commercial engine oils, synthetic and natural. It is also used as high viscous media. In the case of chlorophyll solution, the self-induced diffraction ring pattern in the far-field is a series of circular rings at the beginning; but later it is transformed to half circular symmetry. But for the high viscous engine oils we have observed circular fringes and there is no time dependent structural variation in the pattern. The coefficient of the intensity dependent nonlinear refractive index for all the liquid samples is evaluated.
Źródło:
Optica Applicata; 2017, 47, 4; 591-599
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stochastic finite element analysis using polynomial chaos
Autorzy:
Drakos, S.
Pande, G. N.
Powiązania:
https://bibliotekanauki.pl/articles/178732.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
foundation settlements
stochastic finite element
polynomial chaos
Opis:
This paper presents a procedure of conducting Stochastic Finite Element Analysis using Polynomial Chaos. It eliminates the need for a large number of Monte Carlo simulations thus reducing computational time and making stochastic analysis of practical problems feasible. This is achieved by polynomial chaos expansion of the displacement field. An example of a plane-strain strip load on a semi-infinite elastic foundation is presented and results of settlement are compared to those obtained from Random Finite Element Analysis. A close matching of the two is observed.
Źródło:
Studia Geotechnica et Mechanica; 2016, 38, 1; 33-43
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanical properties of the brain–skull interface
Autorzy:
Mazumder, M. M. G.
Bunt, S.
Mostayed, M.
Joldes, G.
Day, R.
Hart, R.
Wittek, A.
Powiązania:
https://bibliotekanauki.pl/articles/307196.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
biomechanics
brain-skull
interface
mechanical properties
FEM
biomechanika
metoda elementów skończonych
właściwości mechaniczne
Opis:
Knowledge of the mechanical properties of the brain-skull interface is important for surgery simulation and injury biomechanics. These properties are known only to a limited extent. In this study we conducted in situ indentation of the sheep brain, and proposed to derive the macroscopic mechanical properties of the brain–skull interface from the results of these experiments. To the best of our knowledge, this is the first ever analysis of this kind. When conducting in situ indentation of the brain, the reaction force on the indentor was measured. After the indentation, a cylindrical sample of the brain tissue was extracted and subjected to uniaxial compression test. A model of the brain indentation experiment was built in the Finite Element (FE) solver ABAQUSTM. In the model, the mechanical properties of the brain tissue were assigned as obtained from the uniaxial compression test and the brain-skull interface was modeled as linear springs. The interface stiffness (defined as sum of stiffnesses of the springs divided by the interface area) was varied to obtain good agreement between the calculated and experimentally measured indentor force–displacement relationship. Such agreement was found to occur for the brain-skull interface stiffness of 11.45 (mm [to -1]/ Nmm [to 2].). This allowed identification of the overall mechanical properties of the brain–skull interface.
Źródło:
Acta of Bioengineering and Biomechanics; 2013, 15, 2; 3-11
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A computational evaluation of sedentary lifestyle effects on carotid hemodynamics and atherosclerotic events incidence
Autorzy:
Caruso, M. V.
Serra, R.
Perri, P.
Buffone, G.
Calio, F. G.
Franciscis, S.
Fragomeni, G.
Powiązania:
https://bibliotekanauki.pl/articles/307512.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
siedzący tryb życia
pozycja siedząca
komputerowa mechanika płynów
CFD
miażdżyca
sedentary lifestyle
sitting
computational fluid dynamics
carotid bifurcation
atherosclerosis
standing
Opis:
Purpose: Hemodynamics has a key role in the atheropathogenesis. Indeed, atherosclerotic phenomena occur in vessels characterized by complex geometry and flow pattern, like the carotid bifurcation. Moreover, the lifestyle is a significant risk factor. The aim of this study is to evaluate the hemodynamic effects due to two sedentary lifestyles -sitting and standing positions- in the carotid bifurcation in order to identify the worst condition and to investigate the atherosclerosis incidence. Methods: The computational fluid dynamics (CFD) was chosen to carry out the analysis, in which in-vivo non-invasive measurements were used as boundary conditions. Furthermore, to compare the two conditions, one patient-specific 3D model of a carotid bifurcation was reconstructed starting from computer tomography. Different mechanical indicators, correlated with atherosclerosis incidence, were calculated in addition to flow pattern and pressure distribution: the time average wall shear stress (TAWSS), the oscillatory shear index (OSI) and the relative residence time (RRT). Results: The results have highlighted that the bulb and the external carotid artery emergence are the most probable regions in which atherosclerotic events could happen. Indeed, low velocity and WSS values, high OSI and, as a consequence, areas with chaotic-swirling flow, with stasis (high RRT), occur. Moreover, the sitting position is the worst condition: considering a cardiac cycle, TAWSS is less than 17.2% and OSI and RRT are greater than 17.5% and 21.2%, respectively. Conclusions: This study suggests that if a person spends much time in the sitting position, a high risk of plaque formation and, consequently, of stenosis could happen.
Źródło:
Acta of Bioengineering and Biomechanics; 2017, 19, 3; 43-52
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diagnostic moiré image evaluation in spinal deformities
Autorzy:
Balla, P.
Manhertz, G.
Antal, A.
Powiązania:
https://bibliotekanauki.pl/articles/173236.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Moiré method
image processing
Scheuermann’s disease
curve determination
Opis:
This paper deals with moiré picture evaluation in case of a very frequent spinal deformity, called the Scheuermann’s disease. Spinal deformities often occur in the group of 10–17 year-old children. This Scheuermann-type of spinal deformity is more frequent (11%) than the well-known scoliosis (2–4%), but because of the incorrect diagnosis it often remains without a right treatment. Now the accepted medical diagnostic method is using frontal and lateral X-ray pictures from patients’ back. Our already presented method uses moiré pictures to establish the right diagnosis. This optical method is fast, non-contact and arbitrarily repeatable. In our former paper we presented two computer algorithms to produce the shape of the patients’ spine. These methods showed good agreement with the traditional medical diagnosis, but the extreme search method returned better results. In this paper we are demonstrating our new results using the extreme search method and the improved computer program.
Źródło:
Optica Applicata; 2016, 46, 3; 375-385
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization of a dual-slot waveguide for a refractive index biosensor
Autorzy:
Sahu, S.
Ali, J.
Singh, G.
Powiązania:
https://bibliotekanauki.pl/articles/173377.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
biosensor
evanescent field
eigenmode
dispersion
Opis:
The present article illustrates the modeling and optimization of a dual-slot waveguide for the application of a refractive index biosensor. The nanometer scale waveguide structure uses the silicon-on-insulator platform for the consideration of higher sensitivity and compactness of a resonator biosensor. The modal analysis is performed using the finite difference method based on full vector eigenmode calculation. The maximum field penetration in the lower index region is found for the quasi-TE mode. The sensitivity is maximized through the optimization of the waveguide dimension by relating effective refractive index with the dispersion of a waveguide. The biosensor showed the maximum calculated sensitivity of 461.327 nm/RIU and a limit-of-detection of 2.601 × 10–6 RIU (where RIU denotes refractive index unit).
Źródło:
Optica Applicata; 2018, 48, 1; 161-167
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On unsaturated soil mechanics – personal views on current research
Autorzy:
Pande, G. N.
Pietruszczak, S.
Powiązania:
https://bibliotekanauki.pl/articles/178676.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
unsaturated soil
suction
microstructure of saturation
constitutive relation
Opis:
This paper presents the authors’ personal views on current research being conducted by various research groups around the world in the broad area of mechanics of unsaturated geomaterials in general and soils in particular. The topic is of interest to a wide spectrum of scientists and engineers working in diverse areas such as geology and geophysics, powder technology, agricultural, petroleum, chemical, geotechnical, civil, environmental and nuclear engineering. Even if we restrict ourselves to civil, geotechnical and environmental engineering, it is noted that a plethora of hypotheses as well as a number of empirical and semiempirical relations have been introduced for describing the mechanics of unsaturated porous media. However, many of these proposed advances as well as methods of testing may lack sound theoretical basis.
Źródło:
Studia Geotechnica et Mechanica; 2015, 37, 3; 73-84
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
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