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Tytuł:
Wyznaczanie składki netto na podstawie próby dla różnych rozkładów wielkości szkód w ubezpieczeniach komunikacyjnych
Setting of the Net Premium on the Base of the Sample for Different Damage Size Distribution in the Community Insurance
Autorzy:
Szymańska, Anna
Powiązania:
https://bibliotekanauki.pl/articles/907435.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
net premium
damage size distribution
Opis:
In the insurance theory a lot of methods of the net premium setting can be found. In the paper chosen theoretical methods of the net premiums setting in property insurance are presented. The influence of the damage size distribution on the size of the net premiums in community insurance estimated by different methods has been examined. Three size distributions of the damage size have been considered: the Pareto distribution, the logarithmic-normal distribution and the gamma distribution
Źródło:
Acta Universitatis Lodziensis. Folia Oeconomica; 2012, 274
0208-6018
2353-7663
Pojawia się w:
Acta Universitatis Lodziensis. Folia Oeconomica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultrasonic Properties of Magnetic Nanoparticles with an Additional Biocompatible Dextrane Layer
Autorzy:
Dąbek, L.
Hornowski, T.
Józefczak, A.
Skumiel, A.
Powiązania:
https://bibliotekanauki.pl/articles/176605.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
magnetic nanoparticles
ultrasound
particle size distribution
Opis:
The temperature dependence of the particle size distribution (PSD) of the magnetic fluid with an additional biocompatible dextran layer was studied using a ultrasonic method. The measurements of the ultrasound velocity and attenuation were carried out as a function of the volume concentration of magnetite particles at temperatures ranging from 15°C to 40°C. In order to extract the PSD from ultrasonic measurements, the theoretical model of Vinogradov-Isakovich was used. The extraction of PSD from the ultrasonic data requires also the measurements the density and viscosity of the ferrofluid samples. The calculated PSD of the magnetic fluid with an additional biocompatible layer shows a greater thermal stability than that of a magnetic fluid with a single surfactant layer.
Źródło:
Archives of Acoustics; 2013, 38, 1; 93-98
0137-5075
Pojawia się w:
Archives of Acoustics
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:
Does Zipfs law hold for Polish cities?
Autorzy:
Cieślik, Andrzej
Teresiński, Jan
Powiązania:
https://bibliotekanauki.pl/articles/2040370.pdf
Data publikacji:
2017-02-10
Wydawca:
Uniwersytet Warszawski. Wydział Geografii i Studiów Regionalnych
Tematy:
Zipf's law
rank-size rule
city size distribution
Polska
Opis:
In this paper we study Zipf's law, which postulates that the product of a city's population and its rank (the number of cities with a larger or equal population) is constant for every city in a given region. We show that the empirical literature indicates that the law may not always hold, although its general form, the rank-size rule, could be a good first approximation of city size distribution. We perform our own empirical analysis of the distribution of the population of polish cities on the largest possible sample to find that Zipf's law is rejected for poland as the city sizes are less evenly distributed than it predicts.
Źródło:
Miscellanea Geographica. Regional Studies on Development; 2016, 20, 4; 5-10
0867-6046
2084-6118
Pojawia się w:
Miscellanea Geographica. Regional Studies on Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation into particulate size distributions in the exhaust gas of diesel engines fuelled with biodiesel blends
Autorzy:
Chuepeng, S.
Theinnoi, K.
Xu, H. M.
Wyszynski, M. L.
York, A. P. E.
Hartland, J. C.
Qiao, J.
Powiązania:
https://bibliotekanauki.pl/articles/248072.pdf
Data publikacji:
2008
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
biodiesel
PM
combustion
diesel
PM size distribution
Opis:
Particulate matter (PM) size distributions in the exhaust gas of biodiesel blend fuelled diesel engines have been studied by experimenting firstly on a single cylinder equipped with a pump-line-injector injection system and secondly for comparison on a V6 DI engine equipped with a common rail fuel injection system. Both engines were operated with a biodiesel (RME) blend of B30 and ultra low sulphur diesel fuel (ULSD). Several engine load conditions with and without exhaust gas recirculation (EGR) were selected. Particulate number concentrations vs. the electrical mobility equivalent diameter were examined using a fast differential mobility spectrometer. The effect of engine operating conditions including EGR rates on particulate emissions has been investigated. It is found that PM sizes from combustion of B30 without EGR operation are generally smaller than those from ULSD while number concentrations are higher. This can result in lower PM mass estimates for the B30 case if due care is not taken. When EGR is applied to control nitrogen oxides emissions, both the total PM number and mass are increased and shifted toward the larger sizes for both fuels used in the test. The calculated total PM mass from B30 combustion is lower than in the ULSD case for all the tested engine operating conditions.
Źródło:
Journal of KONES; 2008, 15, 3; 75-82
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Studies on the Tailoring of Particle Size and Micromeritic Properties of Reduced Shock Sensitivity RDX (RSS-RDX)
Autorzy:
Ramavat, V.
Sarangapani, R.
Reddy, S. T.
Patil, R. S.
Gore, G. M.
Sikder, A. K.
Powiązania:
https://bibliotekanauki.pl/articles/951500.pdf
Data publikacji:
2013
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
crystallization
RSS-RDX
micromeritics
particle size distribution
Opis:
The microstructure of explosive particles, as well as formulations, has a significant influence on the shock sensitivity of various energetic formulations. Particle shape and specific size distributions are always important considerations in explosives processing in order to realize better process parameters. The present study aimed to explore crystallization variables required to achieve a specific particle size of Reduced Shock Sensitivity RDX (RSS-RDX). Crystallization process factors such as cooling rate, agitator speed and configuration, etc. have been systematically studied to understand their effect on the particle size. The study also established the crystallization process parameters required to tightly control a specific particle size distribution ranging from 50 to 500 μm by cooling crystallization. Fine particles ranging from 15 to 30 μm were prepared by an ultrasonication technique. Ultrasonic process parameters, including temperature, time and ultrasonic frequency, were studied and the process conditions were optimized. Micromeritic characterization of RSS-RDX revealed the nature of flowability, which in-turn is useful in identifying the ease of processability. Overall, our interest stemmed from an investigation which showed that careful optimization of crystallization variables can lead to a specific particle size distribution.
Źródło:
Central European Journal of Energetic Materials; 2013, 10, 4; 581-592
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improving the carbon dioxide uptake efficiency of activated carbons using a secondary activation with potassium hydroxide
Autorzy:
Zgrzebnicki, M.
Michalczyszyn, E.
Wrobel, R. J.
Powiązania:
https://bibliotekanauki.pl/articles/778515.pdf
Data publikacji:
2018
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
activated carbon
activation
pore size distribution
DFT
Opis:
Secondary activation of commercial activated carbon (AC) ORGANOSORB 10-CO was carried out at 600, 700 and 800°C with mass ratios of potassium to AC (K/AC) in range 1–3. Crucial samples have shown following CO2  uptakes and SSA – 3.90 mmol/g and 1225 m2/g, 4.54 mmol/g and 1546 m2/g, 4.28 and 1717 m2/g for pristine material and samples obtained at 700°C with K/AC = 2 and at 800°C with K/AC = 3 respectively. Last sample also indicated significant mesopore volume increase in diameter range 2–5 nm, from 0.11 to 0.24 cm3/g. CO2 uptake increase was explained by formation of micropores up to diameter of 0.8 nm, which distribution was established from CO2  sorption using DFT. Surface chemistry of all samples has not changed during modification, what was proven by XPS. Moreover, deeper incorporation of potassium ions into graphite at higher temperatures was observed as confirmed with EDS, XPS and XRD.
Źródło:
Polish Journal of Chemical Technology; 2018, 20, 3; 87-94
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical models of particle size distribution in simulation analysis of high-pressure grinding roll operations
Autorzy:
Saramak, D.
Powiązania:
https://bibliotekanauki.pl/articles/110253.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
HPGR
comminution
particle size distribution
ore processing
Opis:
The high-pressure grinding roll (HPGR) technology is currently one of the most efficient methods of hard ore comminution from the scope of the energy consumption. Throughput and energetic models of performance are quite well developed, but technological models predicting the comminution effects still needs an in-depth research. In the paper author presents the method of modeling of HPGR products’ particle size distribution by using suitable mathematical models. A basis of the HPGR perfor-mance assessment and HPGR-based crushing circuits design is a product’s particle size distribution. In order to precisely determine the particle size distribution of a HPGR product, parameters of product’s particle size distributions should be conditional on the main technical parameters of the roller press like operating pressure and the speed of rolls. The most accurate approximation of a distribution of size parti-cle appears to be Weibull’s truncated distribution and it is possible to obtain significant relationships between the approximation formula and the value of operating pressure, or feed characteristics. It makes possible a determination of mass recoveries of the product’s respective size fractions and the productivity planning. Instead of pressure, the other HPGR operating parameters can be applied, but the pressure value appears to produce the most relevant relationship. A determination of HPGR product’s particle size dis-tribution is a basis of the press operation simulation analysis.
Źródło:
Physicochemical Problems of Mineral Processing; 2013, 49, 1; 121-131
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A study of selected properties of rhenium sulphide dispersion
Autorzy:
Pawlak, D. W.
Parus, J. L.
Skwarek, E.
Janusz, W.
Powiązania:
https://bibliotekanauki.pl/articles/951830.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
rhenium sulphide
particle size distribution
zeta potential
Opis:
Due to potential application of rhenium sulphide in medicine and industry, this study is focused on the properties of synthetic and commercial rhenium sulphide. The main reaction of rhenium sulphide preparation involves potassium perrhenate and sodium thiosulphate in the acidic environment giving a mixture of rhenium sulphide and sulphur. The next step is removing sulphur by its dissolution in ether. Stabilization by Povidone K-25 is needed to obtain rhenium sulphide dispersed with the grain size of 0.5–4 m. The extrapolated value of pHiep for synthesised rhenium sulphide is 2.3 whereas for commercial samples this value is lower than 2. For synthetic sample a dependence of zeta potential on the carrier electrolyte concentration is found. It is larger than that for the commercial sample, probably due to surface oxidation during synthesis or purification.
Źródło:
Physicochemical Problems of Mineral Processing; 2014, 50, 1; 387-397
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sediment transport in the coastal zone
Autorzy:
Sawczyński, S.
Kaczmarek, L.M.
Powiązania:
https://bibliotekanauki.pl/articles/298420.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie
Tematy:
sediment transport
graded sediment
grain size distribution changes
Opis:
The paper provides basic information on the description of sediment transport in the coastal zone of the sea. It explains the mechanisms of sediment movement under the influence of the waves and currents interactions, characteristic for the coastal zone. It presents models describing the movement of sediment in the regime of flat bottom, making their divided in accordance with the method of description of vertical structure of sediments transport. Particular emphasis is placed on modeling of graded sediment transport. It presents basis for the three-layer model of graded sediment transport. This allows, among others, the analysis of the variability of particle size distribution in the whole area of sediment movement. The model assumes that the movement of sediment is divided into three layers: bedload layer, contact load layer and outer flow region, as a result of the shear stress influence on the bottom.
Źródło:
Technical Sciences / University of Warmia and Mazury in Olsztyn; 2014, 17(2); 165-180
1505-4675
2083-4527
Pojawia się w:
Technical Sciences / University of Warmia and Mazury in Olsztyn
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surface probability model for estimation of size distribution on a conveyor belt
Autorzy:
Zhang, Z
Yang, J.
Dou, D.
Powiązania:
https://bibliotekanauki.pl/articles/109982.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
size distribution
surface probability model
conveyor belt
particles
Opis:
Estimation of size distribution by image analysis is a key issue in mineral engineering. However, only the surface information of ore piles can be captured, which is a headache problem in this field while only a few researchers pay attention to this problem. A new surface probability model was proposed for estimation of size distribution on a conveyor belt based on the Chavez Model in this investigation. This model was tested and verified to have smaller errors in single size fraction but have bigger errors in multiple size fractions. Several error trends were found and a correction factor was introduced to correct the higher errors. A series of linear equations were developed to calculate this specific correction factor according to Dm (average particle size) and the height of pile. Therefore, empirical probability can be estimated by the specific correction factor and calculated probability, and the surface information of ore piles can be converted into the global information of piles.
Źródło:
Physicochemical Problems of Mineral Processing; 2014, 50, 2; 591-606
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Soil physical properties affected by biochar addition at different plant phaenological phases. Part II
Autorzy:
Mako, A.
Barna, G.
Horel, A.
Powiązania:
https://bibliotekanauki.pl/articles/2082863.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
biochar
aggregate size distribution
hydraulic
conductivity
bulk density
Opis:
A great emphasis has been placed on biochar addition to soils to improve its physical, chemical, and biological properties in recent times in order to achieve improved crop growth and yields. The present study explored to soil physical changes through different plant growth stages caused by biochar addition to silt loam soil in a pot-experiment. Our research focused on changes in soil bulk density, aggregate size distribution, and saturated hydraulic conductivity. The soils were amended with different amounts of biochars (control with 0, BC0.5 with 0.5%, BC2.5 with 2.5%, and BC5.0 with 5.0% biochar, by weight). Capsicum annuum L. were planted at a two-four leaf stage. Soil samples were taken at 6, 10 and 12 weeks after planting. The biochar amendment resulted in a significant decrease in soil bulk density values. Soil saturated hydraulic conductivity values ranged between 5.5 and 7.9 times higher for all treatments compared to the controls.
Źródło:
International Agrophysics; 2020, 34, 1; 1-7
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical sizing of cement particles
Autorzy:
Gorsky, M. P.
Maksimyak, P. P.
Powiązania:
https://bibliotekanauki.pl/articles/174679.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
transverse coherence
polarization interferometer
cement
size distribution function
Opis:
We represent the optical correlation technique of cement particle sizing based on the transverse coherency function measurement using a polarization transverse shearing interferometer. It is shown that a set of particles with random shapes and orientations produces a coherence function, which is the same as a function of the set of spherical particles. The proposed technique of experimental data processing decreases the dependence of the result on interferometer noise, emission source intensity fluctuations and differences in the refraction index of isolated cement particles. The described technique allows fast and high reliable determining of the size distribution function parameters for a set of cement particles.
Źródło:
Optica Applicata; 2017, 47, 4; 511-519
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evolution of droplet size distribution in selected nebulizers
Autorzy:
Dobrowolska, Katarzyna
Sosnowski, Tomasz R.
Powiązania:
https://bibliotekanauki.pl/articles/1450682.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
spraying
liquid atomization
aerosol dynamics
particle size distribution
Opis:
Nebulizers are the class of atomizing devices used to disperse liquids to fine droplets. They found their application in selected technological (typically: small-scale) processes, but their most common use is related to the generation of medicinal aerosols for inhalation. In this work we present the experimental data on the evolution of the size distributions of water droplets generated by two nebulizers (pneumatic and vibrating-mesh) as a result of aerosol mixing with the ambient air. Such a process reflects the real situation, where aerosol emitted from a nebulizer is diluted by additional air sucked by a patient during inhalation. Droplet size distribution was determined by laser diffraction, and these results were further discussed including the data of the aerosol velocity measured by the Laser Doppler Anemometry (LDA). It was demonstrated – as expected - that dilution with the ambient air with moderate humidity results in the intense evaporation of the smallest droplets. However, larger droplet may be saved to a different degree depending on the velocity and geometry of the aerosol cloud emitted from the nebulizer, and on the volume of the diluting air. These parameters have an influence on the droplet coalescence which is another process shaping the droplet size distribution in the studied conditions. The results can deepen the understanding of the mist dynamics which can be applied in various fields of colloidal science and technology.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 6; 32-40
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Iron ore benefication processes optimization
Optimizacija processov obogashhenija zheleznojj rudy
Autorzy:
Morkun, V.
Goncharov, S.
Pikilnyak, A.
Krivenko, A.
Powiązania:
https://bibliotekanauki.pl/articles/792347.pdf
Data publikacji:
2012
Wydawca:
Komisja Motoryzacji i Energetyki Rolnictwa
Tematy:
mineral processing
iron ore
beneficiation process
particle size distribution
fuzzy model
process optimization
size distribution
solid phase
technological process
Źródło:
Teka Komisji Motoryzacji i Energetyki Rolnictwa; 2012, 12, 4
1641-7739
Pojawia się w:
Teka Komisji Motoryzacji i Energetyki Rolnictwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aerosol Generation and Identification for Model Studies of Particle–Lung Interactions
Autorzy:
Kondej, D.
Sosnowski, T. R.
Powiązania:
https://bibliotekanauki.pl/articles/90513.pdf
Data publikacji:
2010
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
industrial aerosols
generation
concentration
size distribution
metal elements
Opis:
This article discusses the idea and set-up of a laboratory system for generating reproducible concentrated occupational aerosols containing metal compounds. Dust representatives for 2 metal-machining workstations (an electric grinder and an electric disc cutter) were released from a fluidized-bed generator, and then sampled and compared in respect to concentration, particle size distribution, particle morphology and the content of metal elements (Fe, Al, Cu, Mn, Cr, Ni, Pb, Zn, Mg). The results indicate the presence of a significant number of irregularly-shaped respirable particles. Those particles contained mainly Fe and Al, and their composition was shown to depend on particle size. The proposed system of aerosol generation and collection can be used in studies of interactions between airborne particles and a model lung surfactant.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2010, 16, 1; 41-48
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Soil types and their relations with radon concentration levels in Middle Governorate of Gaza Strip, Palestine
Autorzy:
Ubeid, Khalid Fathi
Ramadan, Khaled Ahmed
Powiązania:
https://bibliotekanauki.pl/articles/2088223.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
grain-size distribution
radon
pollution
Gaza Strip
Palestine
Opis:
Determination of natural radioactivity has been carried out in surface and core agricultural soil samples collected from various sites in the Middle Governorate – Gaza Strip, Palestine. Mechanical and chemical analysis has been done to determine soil characteristics. Radon activity concentration measurements were carried out using solid state nuclear tracks detectors, Cr-39. The mechanical analysis results show that they belong to two classes, sandy loam and loamy sand. The sandy loam soil was observed in the eastern side of the study area, whereas the loamy sand was observed in western and middle parts. The radon concentration levels were higher in core samples and were proportionate to the soil depth. Also they were higher in sandy loam than loamy sand soil samples. The radon concentration levels had a positive correlation with fine grains (clay- to silt-size) of soil sample which translocated from upper to lower horizons of soil during its development. Additionally, there was a positive correlation with pH and water content, whereas a negative correlation was observed with organic matter and potassium contents. The positive correlation referred to a large specific surface of fine grains which were located in lower horizons of soil and were able to adsorb more water and consequently led to high radon concentration levels.
Źródło:
Polish Journal of Soil Science; 2020, 53, 1; 55-72
0079-2985
Pojawia się w:
Polish Journal of Soil Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Soil types and their relations with radon concentration levels in Middle Governorate of Gaza Strip, Palestine
Autorzy:
Ubeid, K.F.
Ramadan, K.A.
Powiązania:
https://bibliotekanauki.pl/articles/971260.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
grain-size distribution
radon
pollution
gaza strip
palestine
Opis:
Determination of natural radioactivity has been carried out in surface and core agricul- tural soil samples collected from various sites in the Middle Governorate – Gaza Strip, Palestine. Mechanical and chemical analysis has been done to determine soil characteristics. Radon activity concentration measurements were carried out using solid state nuclear tracks detectors, Cr-39. The mechanical analysis results show that they belong to two classes, sandy loam and loamy sand. The sandy loam soil was observed in the eastern side of the study area, whereas the loamy sand was observed in western and middle parts. The radon concentration levels were higher in core samples and were proportionate to the soil depth. Also they were higher in sandy loam than loamy sand soil samples. The radon concentration levels had a positive correlation with fine grains (clay- to silt-size) of soil sample which translocated from upper to lower horizons of soil during its development. Additionally, there was a positive correlation with pH and water content, whereas a negative correlation was observed with organic matter and potassium contents. The positive cor- relation referred to a large specific surface of fine grains which were located in lower horizons of soil and were able to adsorb more water and consequently led to high radon concentration levels.
Źródło:
Polish Journal of Soil Science; 2020, 53, 1
0079-2985
Pojawia się w:
Polish Journal of Soil Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of the sand particle shape on particle size distribution measured by laser diffraction method
Autorzy:
Polakowski, C.
Sochan, A.
Bieganowski, A.
Ryzak, M.
Foldenyi, R.
Toth, J.
Powiązania:
https://bibliotekanauki.pl/articles/25877.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
sand
particle shape
particle size distribution
laser diffraction
Opis:
The aim of this paper was to show how the shape of sand particles affects the results of particle size distribution obtained by the laser diffraction method. On the basis of the results obtained one can conclude: the shape of the investigated particles influences particle size distribution obtained by the laser diffraction method. This phenomenon occurs in the sand fraction, as shown in our investigation. The importance of this effect depends on the type of the measured material and on the aim of the investigations. For most researchers in soil science and sedimentology who investigate sand fractions, this impact can be negligible. Further investigations with other soil and sediment fractions are needed.
Źródło:
International Agrophysics; 2014, 28, 2
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of two-stage thermal disintegration on particle size distribution in sewage sludge
Autorzy:
Kaczmarek, A. M.
Gaca, J.
Powiązania:
https://bibliotekanauki.pl/articles/777862.pdf
Data publikacji:
2013
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
laser diffraction
particle size distribution
sludge
thermal hydrolysis
Opis:
The effect of two-stage thermal disintegration of sewage sludge on the particle size distribution using laser diffraction method has been studied. The sludge was sampled from municipal sewage treatment plant after each stage of disintegration. The first stage of disintegration known as homogenization proceeds at temperature of 70-90°C and pressure of 3 bar, the second stage called thermal hydrolysis was performed at temperature of 160-170°C and pressure of 6 bar. It was found that the first stage of disintegration has the strongest impact on the reduction of the sludge particle size and changes in chemical properties. The maximum size of the particles from raw sewage before disintegration was 310 μm. After first stage of the process average size of the particles was 250 μm, and during the second stage it was reduced to 226 μm. Sludge disintegration degree (DDCOD) of 59% confirms high effectiveness of the process. We established that the redox potential (Eh) of sludge effluents was changed after each step of the studied process. Furthermore, chemical oxygen demand (COD) increases which leads to the conclusion that resizing of floccules is accompanied by hydrolysis.
Źródło:
Polish Journal of Chemical Technology; 2013, 15, 3; 69-73
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An evaluation of a modified product size distribution model based on t-family curves for three different crushers
Autorzy:
Umucu, Y.
Deniz, V.
Unal, N.
Powiązania:
https://bibliotekanauki.pl/articles/110242.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
crusher
drop weight tests
t-family
size distribution
Opis:
Crushing is a process which is widely used in mineral processing plants, cement factories, aggregates plants and some other industrial plants. Specific fracture energy of the particles is not the only fundamental property that is important: the particle strength also plays a significant role in determining the overall comminution properties of the material. In the drop weight test, a known mass falls through a given height onto a single particle providing an event that allows characterization of the ore under impact breakage. It is known that there are many difficulties and problems in the drop weight and twin pendulum test methods such as being laborious, requiring long test time and requiring a special apparatus. In this study, breakage behavior of slag in different laboratory crushers was investigated. A new size distribution model equation was developed by a t-family value evaluation approach, and the validity of equation was tested.
Źródło:
Physicochemical Problems of Mineral Processing; 2013, 49, 2; 473-480
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mineral matter in municipal solid waste
Autorzy:
Sniadecka, N.
Tonderski, A.
Hanel, A.
Wojda-Gburek, J.
Hupka, J.
Powiązania:
https://bibliotekanauki.pl/articles/110706.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
mineral matter
municipal waste
separation technologies
size distribution
Opis:
Municipal solid waste (MSW) contains mineral materials which are seldom considered as a potential resource. Currently, the waste management sector pays attention to recyclable parts, biodegradable material, waste-to-energy fraction, and residues after waste reuse and recycle. In contrast, this study focus as on the mineral matter in MSW. The aim was to analyze and discuss the sources of mineral matter in MSW, the impact which the minerals have on waste management technologies, and finally, the possibility to recycle the mineral matter. The contribution of inorganic matter in the MSW stream is significant (about 20 wt.%). In the years 2012–2015, the average content of mineral matter in mixed MSW in Poland ranged from 16 wt.% to 36 wt.%, and the content of organic in MSW ranged from 20 wt.% to 42 wt.%. Minerals in MSW have rather negative impact on waste management technologies and their final products, and can be sorted out from the MSW stream, either in the households or in a central sorting line. However, in central collection and separation systems it is difficult to obtain a mineral matter fraction in subsequent processing steps due to technological limitations (inefficiency of devices), high degree of waste fragmentation and pollution of mineral matter with other waste. This indicates a hampered ability to separate minerals in a form available for reuse, so an effective system should be based on improved segregation at the source.
Źródło:
Physicochemical Problems of Mineral Processing; 2016, 52, 2; 973-990
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Main determinants of the grain size distribution of overbank deposits in Poland : an overview of literature on models of sedimentation
Autorzy:
Szmańda, J. B.
Powiązania:
https://bibliotekanauki.pl/articles/2060079.pdf
Data publikacji:
2018
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
sedimentology
overbank deposits
grain size distribution
models of deposition
Opis:
The article describes the most important features of the grain size distribution of overbank deposits (madas) of Polish rivers. The most important characteristics of their deposition and the factors determining the variability of the grain size distribution of overbank deposits are indicated. Almost all grain fractions distinguished in nature, i.e. cobbles, gravels, sands, silts, and clays, occur in the overbank deposits of Polish rivers. The sandy fraction dominates in overbank sediments, which contradicts their widespread recognition as silty-clayey (mud) sediments. The change in the proportion of these fractions (the formation of different types of lithological overbank deposits) is caused by a change in the conditions of sediment transport dependent on six factors: (1) decrease in water flow velocity over a floodplain along with an increase in the distance from the river channel, (2) change in water flow velocity during a single flood (stages of a flood), (3) the diversity of the floodplain relief, (4) changes in the forest cover of the river basin (catchment), (5) change in the longitudinal slope and (6) width of floodplains.
Źródło:
Geological Quarterly; 2018, 62, 4; 873--880
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selected mineral materials grinding rate and its effect on product granulometric composition
Autorzy:
Olejnik, T. P.
Powiązania:
https://bibliotekanauki.pl/articles/110220.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
ball mill
specific grinding rate
contact points
size distribution
Opis:
The article presents investigation on the grinding rate constant. A selection function was measured for different raw materials using a ball mill, and effects of the grinding ball diameter and feed particle sizes on the materials grinding rate constant were investigated. The study was conducted for the mill on a semi-technical scale. The process was carried out periodically using several sets of grinding media. Relations for all investigated materials were expressed by the modified Snow equation. Additionally, the descriptions of the grinding rate was examined. The tendency in the variation of the grinding rate constant with the particle size was similar for all materials used, and was independent of the ball diameter. The author used two selection functions derived theoretically by Tanaka.
Źródło:
Physicochemical Problems of Mineral Processing; 2013, 49, 2; 407-418
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-25 z 232

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