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Wyszukujesz frazę "medium" wg kryterium: Temat


Tytuł:
Wpływ dodatku nanocząstek do medium grzewczego na współczynnik wnikania ciepła w parowaczu płytowym
Autorzy:
Wlaźlak, A.
Powiązania:
https://bibliotekanauki.pl/articles/1818150.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
nanociecze
medium grzewcze
wymiennik ciepła
Opis:
W artykule przedstawiono rezultaty symulacji pracy parowacza płytowego, w którym zastosowano nanociecze (woda - Cu, woda - Al2 O3 i woda - TiO2) o stężeniach 0-5% w celu poprawy efektywności wnikania ciepła po stronie medium grzewczego. Do obliczeń wymienników ciepła wykorzystano równania opisujące własności wybranych nanocieczy. Analizie poddano liczbę płyt wymiennika wymaganą do osiągniecia założonej mocy, zmianę przewodności cieplnej nanocieczy, zależność liczby Prandtla od stężenia zastosowanych nanoczastek oraz wymaganą moc pompy. Otrzymane wyniki wskazują na 15% poprawę współczynnika wnikania ciepła po stronie nośnika ciepła oraz 28% spadek wymaganej mocy pompy, co prowadzi do zmniejszenia gabarytów wymiennika oraz obniżenia zużycia energii.
Źródło:
Zeszyty Energetyczne; 2016, 3; 13--22
2658-0799
Pojawia się w:
Zeszyty Energetyczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improvement of accuracy of simple methods for design and analysis of a blazed phase grating microstructure
Autorzy:
Wang, W.
Jing, X.
Zhao, J.
Li, Y.
Tian, Y.
Powiązania:
https://bibliotekanauki.pl/articles/173533.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
grating
effective medium theory
scalar diffraction theory
Opis:
In order to precisely analyze and design the transmittance characteristics of a blazed grating, the validity of both the scalar diffraction theory and the effective medium theory is quantitatively demonstrated. By making a comparison of diffraction efficiencies calculated by the two simplified methods and Fourier modal method, the accuracy can be obtained. It is found that when the normalized period is more than three wavelengths of the incident light, the scalar diffraction theory is useful to calculate the transmittance of the blazed grating within the error of less than 3%. The validity of the scalar diffraction theory increases when the normalized period increases. Importantly, by considering the Fresnel reflection effect, the validity of scalar diffraction theory can be significantly enhanced. Furthermore, when no higher-order diffraction waves appear and only zeroth order diffraction wave propagates, the effective medium theory is accurate to compute the diffraction efficiency within the difference of less than 1% between the zeroth order effective medium theory and Fourier modal method. The polarization characteristics of the validity of effective medium theory are also quantitatively demonstrated. The validity of the two simplified theories is dependent on not only the normalized period of surface microstructure but also the normalized groove depth.
Źródło:
Optica Applicata; 2017, 47, 2; 183-198
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Model of spatial dependence of the transport coefficient of photons scattered in a tissue
Autorzy:
Kosobutskyy, P.
Kovalchuk, A.
Powiązania:
https://bibliotekanauki.pl/articles/173558.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Monte Carlo simulation
turbid medium
transport photon
Opis:
The paper presents the modeling of scattering of light photons in turbid medium, in which the relative change in light intensity by an elementary plane-parallel layer is proportional to the superposition of spatially homogeneous and spatially inhomogeneous summands. Taking into account the light intensity attenuation by a plane-parallel layer of the spatial nonlinearity transport coefficient of photons, the interaction with the scattering centers in the integral law does not significantly affect the anisotropy scattering regularity and statistical regularities, in which the transport coefficient is spatially inhomogeneous.
Źródło:
Optica Applicata; 2017, 47, 1; 111-117
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preconcentration of a low-grade betafite ore by dense medium cyclone
Autorzy:
Lv, Zihu
Wei, Min
Zhao, Dengkui
Wu, Dongyin
Liu, Changmiao
Cheng, Hongwei
Powiązania:
https://bibliotekanauki.pl/articles/2146943.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
preconcentration
betafite
dense medium cyclone
uranium
niobium
Opis:
In order to find an economical and feasible short process for betafite preconcentrating and to provide a reference for the development of similar low-grade uranium deposits, preconcentration of the betafite ore was investigated based on mineralogical characterization study, float-sink tests, and dense medium cyclone (DMC) separation experiments. The float-sink test results revealed that the gravity separation of the betafite ore was feasible, and the expected particle size range was chosen to be 3~0.3 mm. The effect of important parameters of the DMC experiment such as particle size, grade of the feed, separation density, and inlet pressure on the separation performance of betafite ore was studied. Under the optimal experimental conditions, the expanded experiments were performed and the heavy minerals contained 4557 ppm U and 5200 ppm Nb2O5 with a recovery of 88.86% and 79.73%, respectively, were obtained. Besides, the enrichment ratio (E) values of U and Nb2O5 were 14.24 and 12.78 severally, and the tailings discarding ratio (R) value was 93.76%. The results demonstrate that the preconcentration of low-grade betafite by DMC can remove a large number of tailings and obtain a high-grade uranium concentrate.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 1; 1--14
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Znaczenie medium w sztuce i architekturze
The importance of medium in art and architecture
Autorzy:
Bujak, H.
Powiązania:
https://bibliotekanauki.pl/articles/293546.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
medium
tworzywo
twórczość
rzeźba
material
creativity
sculpture
Opis:
W artykule w sposób subiektywny i syntetyczny przedstawiono kilka kluczowych problemów związanych z pojęciem twórczości w odniesieniu do medium rozumianego jako tworzywo oraz materia dzieła sztuki. Zawarto tu refleksje oraz wnioski zdobyte na styku działalności dydaktycznej na Wydziale Architektury Politechniki Wrocławskiej z niezależną działalnością artystyczną na polu malarstwa oraz rzeźby. Podstawowym założeniem i celem artykułu jest podkreślenie czynnika materialnego w twórczości oraz wykazanie w tym kontekście dużego znaczenia samej twórczości jako procesu mającego cechy uniwersalne dla działalności związanej z projektowaniem. W kontekście omawianych zjawisk zostały przytoczone fragmenty myśli estetycznej, ukazano wybrane zjawiska z obszaru historii sztuki oraz konkretne przykłady prac własnych i studenckich realizowanych na zajęciach z rzeźby na Wydziale Architektury PWr.
The article in a subjective and at the same time synthetic way presents a point of view on several key problems related to the concept of creativity in relation to the medium understood as a material and the matter of a work of art. It contains the reflections and conclusions gained thanks to the combination of didactic activity at the Faculty of Architecture Wrocław University of Science and Technology with the independent artistic activity in the field of painting and sculpture. The basic assumption and purpose of the article is to emphasize the material factor in the artistic work and to demonstrate the great importance of the creativity as a process that has universal features for activities related to design. In the context of the discussed problems, fragments of aesthetic thought, selected phenomena in the area of art history and specific examples of own works as well as student works created during the sculpture classes at the Faculty of Architecture are quoted here.
Źródło:
Architectus; 2018, 2 (54); 83-94
1429-7507
2084-5227
Pojawia się w:
Architectus
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of separation performance of dense medium cyclone using computer simulation
Autorzy:
Umucu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/110863.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
coal
dense medium cyclone
washability
float-sink test
Opis:
Dense medium coal processing technology has been widely used in coal preparation industries in the world since it is the most accurate and efficient coal preparation process to obtain clean coal with a highest possible yield. Separation of coal and impurities using this technology is based on density differences. In literature, a number of mathematical models exist for dense medium cyclones. One of the most widely used model in the coal industry was developed by Mineral Technologies, Inc. This model consists of the equation which predicts the operating performance of a well maintained dense medium separator for a given cyclone geometry (including cyclone diameter) and separation density. In this study, MODSIM© (education/demo version) dense medium cyclone model was applied to coal preparation plant owned by Soma Uyar Mining Co. As a result, the float-sink test results at separation density of the dense medium cyclone were predicted.
Źródło:
Physicochemical Problems of Mineral Processing; 2015, 51, 1; 303-314
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of crosslinking conditions on the dynamic viscosity of organosilicon polymers
Autorzy:
Nowacka, Agnieszka
Klepka, Tomasz
Powiązania:
https://bibliotekanauki.pl/articles/109560.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
abrasive flow machining
organosilicon polymers
abrasive medium
crosslinking conditions
Opis:
This study presents research concerning the development of an organosilicon polymer medium (polymethylhydroborosiloxane), that allows for the optimal selection of viscosity in the medium, for use as an admixture abrasive paste for abrasive flow machining. Based on the results of actual dynamic viscosity medium measurements, the influence of changes in temperature (25 °C, 50 °C and 75 °C) and in the concentration of the crosslinking solution (anhydrite boric acid – 2 wt.%, 4 wt.% and 6 wt.%) were studied. A number of crosslinking medium experiments were carried out, in which the characteristics of storage modulus G' and loss modulus G" of the medium containing different concentrations of crosslinking solutions at different temperature were determined. Due to the results obtained, it was possible to select the parameters of the crosslinking solution optimally both in terms of the temperature (50 °C) as well as its concentration (4 wt.%).
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 6; 1557-1567
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Beneficiation of oxide ores using dense medium cyclones. A simulation study
Autorzy:
Aghlmandi Harzanagh, A.
Ergun, S. L.
Gulcan, E.
Powiązania:
https://bibliotekanauki.pl/articles/110337.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
heavy medium cyclone
heavy liquid
simulation
iron ores
manganese
chromite
Opis:
Recent investigations of particle behavior and segregation phenomena in a cyclone underline that little is known about particle distribution within a heavy medium separation. For this purpose, density profiles in a heavy medium cyclone (HMC) is measured with techniques such as computational fluid dynamics (CFD) in combination with discrete element modelling (DEM), electrical resistance tomography (ERT), X-ray tomography, particle dynamics analyzer (PDA) etc. Along with these modern efforts of determining the performance of HMC, traditional methods depending on empirical inferences based on experimental data are still important and in progress. The aim of this research was to investigate the possibility of using HMC for the concentration of problematic ores which are not coarsely aggregated. Towards this purpose, current empirical methods were applied to experimental data which were derived from float-sink tests of selected heavy minerals and Fe, Mn, and Cr ore samples. Low density difference between particles made the enrichment difficult using other gravity methods like jigs and shaking tables. After determining physical and mineralogical properties of the samples, appropriate size fractions were prepared for float-sink tests. Combination of sodium polytungstate and tungsten carbide powder were used to prepare non-toxic heavy liquids with density up to 3.5 g/cm3. Using the sink-float test results and existing empirical models for high-density DMC plants simulations were performed. The results of the simulations followed by experimental studies showed that HMCs are applicable to process Fe, Mn, and Cr ores with acceptable grade and recovery.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 1; 379-393
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Controllable propagation of Pearcey–Gaussian beams in photorefractive media with fractional Schrödinger equation
Autorzy:
Guo, Teng
Gao, Ru
Ren, Shumin
Wang, Pengxiang
Xiao, Yan
Powiązania:
https://bibliotekanauki.pl/articles/2172852.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Pearcey-Gaussian beam
fractional Schrödinger equation
photorefractive medium
breathing soliton
Opis:
Taking the fractional Schrödinger equation as the theoretical model, the evolution behavior of the Pearcey–Gaussian beam in the photorefractive medium is studied. The results show that breathing solitons are generated when the nonlinear effect and the diffraction effect are balanced with each other. Nonlinear coefficients, Lévy index and beams amplitude affect breathing period of the soliton and maximum peak intensity. Within a certain range, the breathing period of the soliton decreases with the increase of the nonlinear coefficient and the Lévy index. However when the beams amplitude increases, the breathing period and the maximum peak intensity of the soliton increase. Under the photorefractive effect, due to the bidirectional self-acceleration property of the Pearcey beam, the solitons formed will propagate vertically. These properties can be used to manipulate the beam and have potential applications in optical switching, plasma channeling, particle manipulation, etc.
Źródło:
Optica Applicata; 2022, 52, 4; 627--638
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Light waves scattering from an anisotropic semi-soft boundary medium with spectral dependence
Autorzy:
Huang, Zhiru
Dai, Qihang
Ji, Xiaoling
Wang, Tao
Powiązania:
https://bibliotekanauki.pl/articles/1835777.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
light scattering
spectral dependent medium
spectral density
spectral degree of coherence
Opis:
The far-zone behavior of polychromatic light waves on scattering from an anisotrophic semi-soft boundary medium with spectral dependence was considered, and the spectral density and the spectral degree of coherence of the far-zone scattered field were investigated. It is shown that the distributions of the spectral density and the spectral degree of coherence of scattered field are closely related with the rms width, the center wavelength, and the maximum value of the center wavelength of the scattering potential of the scattering medium.
Źródło:
Optica Applicata; 2021, 51, 2; 271-280
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magneto-rotatory compressible couple-stress fluid heated from below in porous medium
Autorzy:
Mehta, C. B.
Powiązania:
https://bibliotekanauki.pl/articles/178540.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
compressible couple-stress fluid
thermal convection
porous medium
rotation
magnetic field
Opis:
The study is aimed at analysing thermal convection in a compressible couple stress fluid in a porous medium in the presence of rotation and magnetic field. After linearizing the relevant equations, the perturbation equations are analysed in terms of normal modes. A dispersion relation governing the effects of rotation, magnetic field, couple stress parameter and medium permeability have been examined. For a stationary convection, the rotation postpones the onset of convection in a couple stress fluid heated from below in a porous medium in the presence of a magnetic field. Whereas, the magnetic field and couple stress postpones and hastens the onset of convection in the presence of rotation and the medium permeability hastens and postpones the onset of convection with conditions on Taylor number. Further the oscillatory modes are introduced due to the presence of rotation and the magnetic field which were non-existent in their absence, and hence the principle of exchange stands valid. The sufficient conditions for nonexistence of over stability are also obtained.
Źródło:
Studia Geotechnica et Mechanica; 2016, 38, 1; 55-63
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Facilitated transport of germanium from acidic medium through supported liquid membrane using Cyanex 301 as mobile carrier
Autorzy:
Kamran Haghighi, Hossein
Irannajad, Mehdi
Moradkhani, Davood
Powiązania:
https://bibliotekanauki.pl/articles/110625.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
germanium
supported liquid membrane
Cyanex 301
mass transfer model
acidic medium
Opis:
In this research, a flat sheet supported liquid membrane (FSSLM) system was used to transfer germanium from the acidic medium. The poly-tetra fluoro ethylene (PTFE) membrane filter with the hydrophobic nature and Cyanex 301 were selected as the support and the mobile carrier, respectively. The influence of various parameters being pH of the feed solution (1.5-5), germanium concentration (10-40 mg/dm3), carrier concentration in the solid membrane (10-40 vol%), and sulfuric acid concentration of the receiving phase (100-400 g/dm3) was investigated on the transport of germanium. Under the optimum condition being pH of 1.5, the germanium concentration of 40 mg/dm3, the carrier concentration of 1.18 mol/dm3, and the sulfuric acid concentration of 400 g/dm3, a mass transfer model was developed. Based on this model, the transport mechanism, diffusion of species to the feed-membrane interface, the chemical reaction of species and Cyanex 301, and diffusion of germanium-Cyanex 301 complexes across SLM were explained. According to the obtained model, the values of 6.57 and 738.6 s/cm were achieved for the aqueous and organic diffusion resistances, respectively.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 1; 225-236
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dry beneficiation and cleaning of chinese high-ash coarse coal utilizing a dense-medium gas-solid fluidized bed separator
Autorzy:
He, J.
Tan, M.
Zhu, R.
Luo, Z.
Powiązania:
https://bibliotekanauki.pl/articles/110808.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
coal cleaning
dense-medium fluidized bed
density distribution
segregation
separation performance
Opis:
Dry dense-medium fluidized bed separation provides a new alternative approach for coal beneficiation and cleaning. An indicator of segregation degree Sash was proposed to evaluate the stratified performance of coal samples by bed density. Fluidization stability of the bed was greatly enhanced by mixing a certain amount (21.53%) of fine magnetite powder (< 0.15 mm) into the fluidized media, which indicated a uniform density distribution as well as slight fluctuations in bed. It was found that the favorable density-segregation performance of 3–13 mm coarse coal occurred with a static bed height of 80 mm and a superficial gas velocity of 11.84 cm/s. The optimal segregation degree values of 0.67, 0.74 and 0.76 were obtained for 3–6, 6–10 and 10–13 mm coal samples, respectively. Low-ash clean coal with yields of 50.79, 56.83 and 61.24% were effectively acquired by the dry separation for various coal size fractions, respectively. Probable error values of 0.07, 0.055 and 0.05 g/cm3 were achieved, indicating good separation performance.
Źródło:
Physicochemical Problems of Mineral Processing; 2016, 52, 2; 662-675
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of a biconical dense medium cyclone to pre-treat a low-grade Pb-Zn sulfide ore
Autorzy:
Jian, Sheng
Sun, Wei
Zheng, Yong-xing
Powiązania:
https://bibliotekanauki.pl/articles/110536.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Pb-Zn sulfide ore
Low-grade ore
Pretreatment
Biconical dense medium cyclone
Opis:
A biconical dense medium cyclone (BDMC) was applied to reject the gangue from a low-grade Pb-Zn sulfide ore for the first time. Based on mineralogy and heavy liquid separation tests, it was found that the rejection of gangue by the BDMC prior to grinding and flotation was promising. The results revealed that the particle size clearly affected the heavy liquid separation process. The effects of several parameters, such as medium specific gravity (SG), spigot diameter, tilt angle, cone angle and medium/ore mass ratio, on the yield of floats and on the metal recoveries in the floats were examined and the optimal parameters were determined. The results showed that 51.22% of floats were obtained with a lead recovery of 7.92% and a zinc recovery of 12.50%. The extended tests were further carried out with the BDMC being capable of throughputs about 3 t/h, which verified the results obtained in the laboratory experiments. The use of this equipment to pre-treat the refractory ore is promising.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 4; 981-990
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Personalisation of production in the era of Industry 4.0 as a challenge for inventory management in small and medium-sized production enterprises
Autorzy:
Grabowska, Sandra
Powiązania:
https://bibliotekanauki.pl/articles/406434.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
inventory
personalisation
customisation
Industry 4.0
small and medium-sized enterprises (SMEs)
Opis:
Industry 4.0 is the result of the development of cyber-physical generation systems as a part of the fourth industrial revolution. Industry 4.0 sets new areas for change in the sphere of production and management but also influences various aspects of society. Industry 4.0 is focused on continuous improvement of production processes. This is a turnaround in the production control methodology, as the growing expectations of customers in the modern market cause, along with the increase in production efficiency, customisation of the product. In this trend, the customer decides about the product, personalising it as much as possible and in the best possible way. These are new challenges in the field of inventory management. The article aims to present a method of calculating the optimal amount of the cost of a rotating stock in a production enterprise with an unevenly distributed demand, which is the case with personalised orders.
Źródło:
Operations Research and Decisions; 2020, 30, 2; 29-37
2081-8858
2391-6060
Pojawia się w:
Operations Research and Decisions
Dostawca treści:
Biblioteka Nauki
Artykuł

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