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Abstract

The paper presents a short description of the model of the phenomenon of droplet spreading in presence of a liquid film, as well as the experimental facility, calculations methodology and results of experimental research concerning determination of the boundary angle at which droplet begins to slide on the horizontal or inclined surface of the plate. Values of boundary angle have been applied to estimate the microscopic dynamic advanced angle of the droplet on the flat surface in presence of a liquid film.
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Authors and Affiliations

Zbigniew Zapałowicz
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Abstract

Determination of the physico-chemical interactions between liquid and solid substances is a key technological factor in many industrial processes in metallurgy, electronics or the aviation industry, where technological processes are based on soldering/brazing technologies. Understanding of the bonding process, reactions between materials and their dynamics enables to make research on new materials and joining technologies, as well as to optimise and compare the existing ones. The paper focuses on a wetting force measurement method and its practical implementation in a laboratory stand – an integrated platform for automatic wetting force measurement at high temperatures. As an example of using the laboratory stand, an analysis of Ag addition to Cu-based brazes, including measurement of the wetting force and the wetting angle, is presented.

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Authors and Affiliations

Marcin Bąkała
Rafał Wojciechowski
Dominik Sankowski
Adam Rylski
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Abstract

This paper presents a method for quantitative assessment of the mechanisms of nucleation and granules growth by layering in the process of bed wetting during periodic disc granulation. This study included two initial, consecutive stages of a process with defined time courses. The first phase was a time period, in which only formation of new nuclei took place, while in the second stage simultaneous nucleation and growth of granules as a result of sticking raw material grains to pre-existing nuclei occurred. Different kinds of binding liquid were used for bed wetting in each phase. In the first phase, an aqueous solution of dye was used, and pure distilled water in the second stage. The contribution of particular mechanisms to the formation of agglomerates at different time points within the second phase of the process was determined in this study. To do that the results of bed granulometric analysis, mass balance of size fractions and the analysis of contents of a marker (dye) delivered to the bed with the binding liquid during the first phase in agglomerates were used. To assess the concentration of the dye in different size fractions of the batch, spectrophotometric analysis was utilised. The study was performed using UV-VIS JASCO V-630 spectrophotometer equipped with an integrating sphere. The sieve analysis, spectrophotometric studies and mass balance were used to determine changes in the weight of the dye containing nuclei and of the nuclei containing no dye. The aforementioned analyses were also used to assess changes in the weight of formed granules and of raw material particles attached to nuclei during simultaneous nucleation and growth of granules.

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Authors and Affiliations

Andrzej Obraniak
Tadeusz Gluba
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Abstract

In the paper, an attempt was made to evaluate the effect of preliminary wetting of high-silica base during preparation of moulding sands

containing a selected grade of sodium water-glass, designed for hardening by traditional drying or by electromagnetic microwaves at 2.45

GHz. In the research, some water was dosed during stirring the sandmix before adding 1.5 wt% of the binder that was unmodified sodium

water-glass grade 137, characterised by high molar module within 3.2 to 3.4. Scope of the examinations included determining the effect of

wetting the base on mechanical parameters like compression, bending and tensile strength, as well as on technological parameters like

permeability, abrasion resistance and apparent density. The research revealed a significant positive effect of adding water to wet surfaces

of high-silica base grains on mechanical properties and quality of moulding sands hardened by physical methods, in particular by

microwave heating

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Authors and Affiliations

M. Stachowicz
K. Granat
Ł. Pałyga
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Abstract

The work presents investigation on the water droplet impingement at a substrate with three different surface coating. The experiments are carried out for two temperatures of the surface: 23ºC (room temperature) and -10ºC. The water droplet contact is recorded via ultra-fast camera and simultaneously via fast thermographic camera. The wetting properties are changing for subzero temperatures of substrates.

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Bibliography

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[9] B.B.J. Stapelbroek, H.P. Jansen, E.S. Kooij, J.H. Snoeijer, and A. Eddi. Universal spreading of water drops on complex surfaces. Soft Matter, 10(15):2641–2648, 2014. doi: 10.1039/c3sm52464g.
[10] M. Remer, M. Psarski, K. Gumowski, J. Rokicki, G. Sobieraj, M. Kaliush, D. Pawlak, and G. Celichowski. Dynamic water contact angle during initial phases of droplet impingement. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 508:57–69, 2016. doi: 10.1016/j.colsurfa.2016.08.028.
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[12] C. Stanley, R. Jackson, N. Karwa, and G. Rosengarten. The effects of surface wettability on droplet fingering. In The Proceedings of the 19th Australasian Fluid Mechanics Conference, Melbourne, Australia, 8-11 December 2014. Paper No. 49.
[13] A. Latka, A. Strandburg-Peshkin, M.M. Driscoll, C.S. Stevens, and S.R. Nagel. Creation of prompt and thin-sheet splashing by varying surface roughness or increasing air pressure. Physical Review Letters, 109(5):054501, 2012. doi: 10.1103/PhysRevLett.109.054501.
[14] T.G. Myers, J.P.F. Charpin, and C.P. Thompson. Slowly accreting ice due to supercooled water impacting on a cold surface. Physics of Fluids, 14(1):240–256, 2002. doi: 10.1063/1.1416186.
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Authors and Affiliations

Tomasz Lizer
1
Michał Remer
1
Grzegorz Sobieraj
1
Maciej Psarski
2
Daniel Pawlak
2
Grzegorz Celichowski
2

  1. Institute of Aeronautics and Applied Mechanics, Warsaw University of Technology, Poland.
  2. Faculty of Chemistry, Department of Materials Technology and Chemistry, University of Lodz, Poland.
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Abstract

In this work, a highly effective catalyst (MoO3) is synthesized and applied for catalytic wet air oxidation (CWAO) treatment of pharmaceutical wastewater. The catalyst is systematically characterized to investigate the morphology, crystal structure and chemical composition, and the findings demostrated that MoO3 catalyst is successfully synthesized. The degradation mechanism is also illustrated by the density functional theory (DFT) calculation. The degradation experiments confirm that MoO3 catalyst exhibits excellent catalytic performance in CWAO, and the removal rate of TOC (Total Organic Carbon) and COD (Chemical Oxygen Demand) is achieved to more than 93%. The catalyst doses, reaction temperature and reaction time have a significant impact on the removal of pollutants. The degradation process of pollutants in CWAO could be satisfactorily fitted by the second-order kinetics. Besides, MoO3 displays a favorable stability as CWAO catalyst. DFT calculation illustrates that MoO3 catalyst is a typical indirect band gap semiconductor. Moreover, the high temperature environment provides the thermal excitation energy, which favors to the free electrons nearing Fermi level to escape the material surface, and excites them to the conduction band, then directly reduces the pollutants in CWAO. These findings demonstrate that MoO3 can be used as an efficient and excellent catalyst for CWAO of pharmaceutical wastewater.
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Bibliography

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Authors and Affiliations

Chen Chen
1
Ting Cheng
2
Lei Wang
1
ORCID: ORCID
Yuan Tian
1
Qin Deng
1
Yisu Shi
1

  1. School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, China
  2. School of Environmental Ecology, Jiangsu City Vocational College, China
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Abstract

The grain boundary wetting phase transition in an industrial EZ33A cast alloy is studied. 12% of the grain boundaries are completely wetted at the temperature slightly higher than the eutectic transformation temperature (530°C). The fraction of wetted grain boundaries increases with temperature, reaches a maximum of 85% at 570°C, and does not change further until the alloy melts. In the as-cast state, the alloy has low ductile properties at the ambient temperature. The microstructure in the as-cast state corresponds to the wetting state at about 560°C, which indicates that the cooling rate in casting is almost equal to that in quenching. The volume and the surface fraction of the second phase and the hardness measured at the least wetted state of samples point to its good machinability. The wetting data are used to suggest a sequence of heat treatment and machining for processing EZ33A alloy parts.

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Authors and Affiliations

A.B. Straumal
K.V. Tsoy
I.A. Mazilkin
A.N. Nekrasov
K. Bryła
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Abstract

Some materials-related microstructural problems calculated using the phase-field method are presented. It is well known that the phase field method requires mesh resolution of a diffuse interface. This makes the use of mesh adaptivity essential especially for fast evolving interfaces and other transient problems. Complex problems in 3D are also computationally challenging so that parallel computations are considered necessary. In this paper, a parallel adaptive finite element scheme is proposed. The scheme keeps the level of node and edge for 2D and level of node and face for 3D instead of the complete history of refinements to facilitate derefinement. The information is local and exchange of information is minimized and also less memory is used. The parallel adaptive algorithms that run on distributed memory machines are implemented in the numerical simulation of dendritic growth and capillary-driven flows.

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Authors and Affiliations

M. Do-Quang
W. Villanueva
I. Singer-Loginova
G. Amberg
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Abstract

One of the parameters which enables the evaluation of carbonaceous material is the thermal effect of wetting. The value of the heat of wetting provides information about the surface energy and the texture of the materials immersed in the wetting liquid. Knowledge of the heat of wetting of the carbonaceous materials is used to research their sorption properties, to characterize the structure and to determine the surface area. A method of me asuring the wetting of the carbonaceous materials as one of the methods to evaluate the carbonaceous materials was proposed. On the basis of research which was conducted, one determined the heat of wetting black coal from the Brzeszcze mine by methyl alcohol and lignites from the Turów and Bełchatów mine. One of activated carbons furnished by the Gryfskand company (WD-extra) was selected for the purpose of the comparison. The enthalpy of immersion was calculated on the basis of the results, the surface of the carbonaceous materials that were studied. It was revealed that the energetic effects of wetting depend both upon the microporous structure and the chemical nature of the adsorbent. The greatest heat of wetting calculated per 1g of the carbonaceous material, which has the most developed surface area and micropore volume, was obtained for the activated carbon. However, the heat of wetting does not increase proportionally to the surface area. The study revealed that the thermal effects of wetting for fossil coal decreases with the increasing of the surface area. The linear relationship was obtained for the three samples which were studied. The highest thermal effects (ΔT) and heat of wetting (Q) among the fossil coals was determined for the lignite from the Bełchatów mine, even though this coal had the least-developed porous structure. One may discern a clear influence of the swelling process upon the measured thermal effects on the basis of this sample.

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Authors and Affiliations

Eliza Wolak
Bronisław Buczek
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Abstract

In this work we report on fabrication of quantum wires and quantum point contacts from the modulation doped CdMgTe/Cd(Mn)Te structures, with the application of a high-resolution electron-beam lithography. We emphasize on methods which were not yet utilized for these substrate materials. In particular, we describe the so-called shallow-etching approach, which allows for the fabrication of quantum constrictions of a physical width down to 100 nm, which are characterized by the smoother confining potential as compared to the deep-etched devices. For that purpose, a single-line exposure mode of electron-beam lithography has been used. We demonstrate also, how to combine the etching of separating grooves with the thermal evaporation of metal side-gates into a single post-processing stage of a quantum point contact fabrication.

This article is an expanded version of the scientific reports presented at the International Conference on Semiconductor Nanostructures for Optoelectronics and Biosensors 2016 ICSeNOB2016, May 22–25, 2016, Rzeszow, Poland.

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Authors and Affiliations

Joanna Wróbel
E. Bobko
Dariusz Płoch
ORCID: ORCID
M. Wiater
T. Wojtowicz
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Abstract

Wet shotcrete technology is being gradually used in roadway support in frigid mining areas. Thus, problems such as low strength, fragility, and high repair rate have also emerged. This study focuses on low strength, cracking, and other problems in the wet shotcrete support of a mine. It introduced the fishbone diagram to investigate the effects of temperature, cement content, and water-cement ratio (W/C) on the strength of the shotcrete layer. The microscopic morphology of wet shotcrete based on scanning electron microscopy (SEM) is observed. Results demonstrated that temperature was the main influencing factor of wet shotcrete in frigid mining areas. When the curing temperature was lower than 10°C, the early strength of wet shotcrete dropped significantly. Temperatures above 15°C were favorable for later gain in strength. W/C was of a complementary relationship with strength development at different ages. Temperature was the essential factor that influenced the microscopic morphology of wet shotcrete. Furthermore, internal initial porosity and aggregate interface bonding strength had a direct effect on macro-mechanical properties of wet shotcrete.

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Authors and Affiliations

Wei Sun
ORCID: ORCID
Zhang Shengyou
Xinglong Feng
Kepeng Hou
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Abstract

The paper deals with the wet steam flow in a steam turbine operating in a nuclear power plant. Using a pneumatic and an optical probe, the static pressure, steam velocity, steam wetness and the fine water droplets diameter spectra were measured before and beyond the last turbine low-pressure stage. The results of the experiment serve to understand better the wet steam flow and map its liquid phase in this area. The wet steam data is also used to modify the condensation model used in computational fluid dynamics simulations. The condensation model, i.e. the nucleation rate and the growth rate of the droplets, is adjusted so that results of the numerical simulations are in a good agreement with the experimental results. A 3D computational fluid dynamics simulations was performed for the lowpressure part of the turbine considering non-equilibrium steam condensation. In the post-processing of the of the numerical calculation result, the thermodynamic wetness loss was evaluated and analysed. Loss analysis was performed for the turbine outputs of 600, 800, and 1100 MW, respectively.
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Bibliography

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Authors and Affiliations

Gukchol Jun
1 2
Michal Kolovratník
2
Michal Hoznedl
1

  1. Czech Technical University in Prague, Technická 4, 160 00, Prague, Czech Republic
  2. Doosan Škoda Power s.r.o., Tylova 1/57, 301 28, Pilsen, Czech Republic
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Abstract

The aim of the study was to assess the profile of EC (elemental carbon) and OC (organic carbon) temperature fractions in PM1 and PM2.5 samples and in wet deposition samples (material collected on a filter). The research was conducted at the urban background station in Zabrze (southern Poland) in the period of Oct 2020–Oct 2021. PM samples were collected with high-volume samplers; the automatic precipitation collector NSA 181 by Eigenbrodt was used to collect the deposition samples. Concentrations of EC and OC were determined using thermal-optical method (carbon analyzer from Sunset Laboratory Inc., “eusaar_2” protocol). Regardless of the type of research material, organic carbon constituted the dominant part of the carbonaceous matter, and this dominance was more visible in the non-heating season. The profile of temperature fractions of OC and EC was clearly different for dust washed out by precipitation. Noteworthy is a much lower content of pyrolytic carbon (PC) in OC, which can be explained by the fact that PC is most often combined with the water soluble organic carbon. In addition, a high proportion of the OC3 fraction was observed, followed by OC4, which may indicate that these fractions are of a more regional origin. With regard to the EC fractions, the differences are less visible and concern, in particular, the higher share of EC4 and the lower EC2. The obtained results may be a valuable source of information about the actual status of the carbonaceous matter and its transformation in the atmosphere.
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Authors and Affiliations

Barbara Błaszczak
1
Barbara Mathews
1
Krzysztof Słaby
1
Krzysztof Klejnowski
1

  1. Institute of Environmental Engineering Polish Academy of Sciences, Zabrze, Poland
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Abstract

Recently, significant progress has been made in experimental studies on the flow of wet steam, measuring techniques based on recording the phenomenon of extinction of light and ultrasound have been elaborated or improved. The basic value experimentally determined in the final stage was the content of the liquid phase defined as the wetness fraction. The methodology of tests and experimental investigations was presented, as well as the applied and developed measurement systems. Next, some developed designs of new ultrasonic and light extinction measuring probe and their modifications are described. The article presents also some examples of applications of the developed measurement techniques in application to experimental research conducted on wet steam. Examples of comparison between experimental and numerical tests for the extinction method are also provided.

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Authors and Affiliations

Mirosław Majkut
Sławomir Dykas
Krystian Smołka
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Abstract

In the present paper, elemental Fe, Cr and Ni powders were used to fabricate nano-structured duplex and ferritic stainless steel powders by using high energy planetary ball milling. We have studied the effect of milling atmosphere like wet (toluene) and dry (argon) milling of elemental Fe-18Cr-13Ni (duplex) and Fe-17Cr-1Ni (ferritic) powders for 10 h in a dual drive planetary mill. Stearic acid of 1wt. % was added during milling to avoid agglomeration. The dry and wet milled duplex and ferritic stainless steel powders were characterized by XRD, SEM and particle size analysis techniques. We have found that both the milling atmospheres have great influence in controlling the final particle morphology, size and phase evolution during milling. It was reported that dry milling is more effective in reducing particle size than the wet milling. The Nelson-Riley method of extrapolation was used to calculate the precise lattice parameter and Williamson-Hall method was used to calculate the crystallite size and lattice strain of both the stainless steel milled in argon atmosphere. Dry milled duplex and ferritic stainless steel were then consolidated by conventional sintering method at 1100, 1200 and 1300°C temperatures under argon atmosphere for 1 hour.

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Authors and Affiliations

R. Shashanka
Orhan Uzun
D. Chaira
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Abstract

The goal of this paper is to measure the non-wetting to wetting transition temperatures of liquid tin on surfaces of different steel samples in vacuum with residual pressure of 10–8 bar. The experiments were conducted on four steels (C45, S103, CK60 and EN1.4034) of varying compositions using pure tin (99.99%) by the sessile drop method. Non-wetting to wetting transition (contact angle decreasing below 90°) by liquid tin was observed as function of increasing temperature in the range of 820-940 K for low alloyed steels C45, S103 and CK60, while it was considerably higher (around 1130 K) for high chromium EN1.4034 steel. It is concluded that at about the same temperatures, the surfaces of the steel samples are spontaneously deoxidized due to the combined effect of high temperature, low vacuum and C-content of steels. After the oxide layer is removed, the contact angles of liquid tin on steel surfaces were found in the range of 45-80° for low alloyed C45, S103 and CK60 steels and around 20° for high chromium EN1.4034 steel. These relatively high contact angle values compared to other metal/metal couples (such as liquid Cu on steels) are due to the formation of not fully metallic intermetallic compounds (FeSn and FeSn2) at the interface (such do not form in the Cu/Fe system).
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Authors and Affiliations

D. Varanasi
1
K.E. Aldawoudi
1
P. Baumli
1
D. Koncz-Horvath
1
G. Kaptay
1

  1. University of Miskolc, Institute of Physical Metallurgy, Metal Forming and Nanotechnology, 3515 Miskolc-Egyetemvaros, Hungary
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Abstract

At present, many studies have been carried out on the fatigue mechanical properties of conventional rocks, but there are few studies on the mechanical properties of rocks after water rock interaction. The aim is to better study the fatigue mechanical characteristics of sandstone after dry wet cycle and the research object we take was sandstone samples after a certain number of drying and wetting cycles. The WAW-2000 electro-hydraulic servo pressure system was used to carry out uniaxial fatigue cyclic loading and unloading tests with different amplitudes and different upper limit stresses. The test found that: when the sample is damaged under fatigue load, the stress-strain curve shows a sharp downward trend and a sudden instability failure occurred in the sample.With the increase of the upper limit stress and amplitude, the life of the sample decreases gradually which also conforms to the change of power function. Then the relationship between fatigue life and stress is obtained. The fatigue stress-strain curve is characterized by sparse-dense-sparse. With the increase of cycle time, the axial strain of the sample shows an inverted “S” shape. The strain change can be divided into three stages: initial stage, constant velocity stage and acceleration stage.
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Authors and Affiliations

Jin-Song Zhang
1
ORCID: ORCID
Yu Lu
1
ORCID: ORCID
Heng-Liang Zhang
2
ORCID: ORCID
Yu-Di Yang
1
ORCID: ORCID
Yi-Shun Bu
1
ORCID: ORCID

  1. Anhui University of Science and Technology, No. 168, Taifeng street, Huainan City, Anhui Province, China
  2. First Design and Research Institute MI China Co, No. 12550, bustling Avenue, Hefei Economic and Technological Development Zone, Anhui Province, China
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Abstract

Water resources are the main component of natural systems affected by climate change in the Middle East. Due to a lack of water, steam power plants that use wet cooling towers have inevitably reduced their output power. This article investigates the replacement of wet cooling towers in Isfahan Thermal Power Plant (ITPP) with Heller natural dry draft cooling towers. The thermodynamic cycle of ITPP is simulated and the effect of condenser temperature on efficiency and output power of ITPP is evaluated. For various reasons, the possibility of installing the Heller tower without increasing in condenser temperature and without changing the existing components of the power plant was rejected. The results show an increase in the condenser temperature by removing the last row blades of the low-pressure turbine. However, by replacing the cooling tower without removing the blades of the last row of the turbine, the output power and efficiency of the power plant have decreased about 12.4 MW and 1.68 percent, respectively.
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Authors and Affiliations

Mohamad Hasan Malekmohamadi
1 2
Hossein Ahmadikia
1
ORCID: ORCID
Siavash Golmohamadi
2
Hamed Khodadadi
3

  1. University of Isfahan, Isfahan, Iran
  2. Isfahan Thermal Power Plant, Isfahan, Iran
  3. Department of Electrical Engineering, Khomeinishahr Branch, Islamic Azad University, Isfahan, Iran
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Abstract

104 algal taxa (31 blue-green algae, 48 diatoms and 25 green algae) were identified from 18 stands of tundra soils in the Kaffiöyra Plain (Oscar II Land, NW Spitsbergen). Basing on numerical analysis by the reciprocal averaging method and on hierarchic classification based on ."distinguishing species", two groups of stands were distinguished: moist and wet ones characterized by diatoms, and dry and drying ones characterized by blue-green algae.

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Authors and Affiliations

Andrzej S. Oleksowicz
Marta Luścińska
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Abstract

In this study, a series of destructive and non-destructive tests were performed on sandstone samples subjected to wetting-drying cycles. A total of 25 Wet-Dry cycles were provided to investigate any significant change in the engineering properties of sandstones in terms of their porosity, permeability, water absorption, density, Q-factor, elastic modulus (E), and unconfined compressive strength (UCS). The overall reduction in the values of density, E, Q-factor, and UCS was noted as 3-4%, 42-71%, 34-62%, and 26-70% respectively. Whereas, the overall appreciation in the values of porosity, permeability, and water absorption was recorded as 24-50%, 31-64%, and 25-50% respectively. The bivariate analysis showed that the physical parameters had a strong relationship with one another and their Pearson’s correlation value (R) ranged from 0.87-0.99. In prediction modeling, Q-factor and E were regressed with the contemplated physical properties. The linear regression models did not provide satisfactory results due to their multicollinearity problem. Their VIF (variance inflation factor) value was found much greater than the threshold limit of 10. To overcome this problem, the cascade-forward neural network technique was used to develop significant prediction models. In the case of a neural network modeling, the goodness of fit between estimated and predicted values of the Q-factor (R2 = 0.86) and E (R2 = 0.91) was found much better than those calculated for the Q-factor (R2 = 0.30) and E (R2 = 0.36) in the regression analysis.
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Authors and Affiliations

Hafiz Muhammad Awais Rashid
1
Muhammad Ghazzali
1
Umer Waqas
1
Adnan Anwar Malik
2
Muhammad Zubair Abubakar
3

  1. University of Engineering and Technology, Department of Geological Engineering, Lahore, Pakistan
  2. Saitama University, Department of Civil and Environmental Engineering, Japan
  3. University of Engineering and Technology, Dean Faculty of Earth Sciences and Engineering, Lahore, Pakistan
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Abstract

The runoff coefficient is one of the fundamental hydrological characteristics of a catchment. It indicates a share of the precipitation water that runs off from the catchment.

The results of the runoff coefficient calculation based on measurements carried out continuously in the Cerhovický Stream catchment over a considerable period of time, i.e. from 1988 up to 2006 are presented. The precipitation and runoff data in the catchment were used. Mean value of the runoff coefficient and the runoff coefficients for the agricultural and forest parts of the catchment are presented. The total mean runoff coefficient for the Cerhovický Stream is 0.19 with the standard deviation of 0.06. Mean runoff coefficient for the forest part is 0.13 and for the agricultural part – 0.24.

Differences between the years with a higher and a lower precipitation were followed as well. We also statistically evaluated possible hydrological changes caused by the construction of the highway and the market centre. For another possible explanation of quite high standard deviation of the mean annual runoff coefficient we followed the monthly runoff coefficient dependence on water temperature and of ground water table depth.

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Authors and Affiliations

Martina Vlčková
Marek Nechvátal
Mojmír Soukup
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Abstract

A multiple regression model approach was developed to estimate buffering indices, as well as biogas and methane productions in an upflow anaerobic sludge blanket (UASB) reactor treating coffee wet wastewater. Five input variables measured (pH, alkalinity, outlet VFA concentration, and total and soluble COD removal) were selected to develop the best models to identify their importance on methanation. Optimal regression models were selected based on four statistical performance criteria, viz. Mallow’s Cp statistic (Cp), Akaike information criterion ( AIC), Hannan– Quinn criterion ( HQC), and Schwarz–Bayesian information criterion ( SBIC). The performance of the models selected were assessed through several descriptive statistics such as measure of goodness-of-fit test (coefficient of multiple determination, R2; adjusted coefficient of multiple determination, Adj-R2; standard error of estimation, SEE; and Durbin–Watson statistic, DWS), and statistics on the prediction errors (mean squared error, MSE; mean absolute error, MAE; mean absolute percentage error, MAPE; mean error, ME and mean percentage error, MPE). The estimated model reveals that buffering indices are strongly influenced by three variables (volatile fatty acids (VFA) concentration, soluble COD removal, and alkalinity); while, pH, VFA concentration and total COD removal were the most significant independent variables in biogas and methane production. The developed equation models obtained in this study, could be a powerful tool to predict the functionability and stability for the UASB system.
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Authors and Affiliations

Yans Guardia-Puebla
1
ORCID: ORCID
Edilberto Llanes-Cedeño
2
ORCID: ORCID
Ana Velia Domínguez-León
3
Quirino Arias-Cedeño
1
ORCID: ORCID
Víctor Sánchez-Girón
4
ORCID: ORCID
Gert Morscheck
5
Bettina Eichler-Löbermann
5
ORCID: ORCID

  1. University of Granma, Study Center for Applied Chemistry, Cuba
  2. Faculty of Architecture and Engineering, International SEK University, Quito, Ecuador
  3. Language Center, University of Granma, Cuba
  4. College of Agricultural, Food and Biosystems Engineering, Technical University of Madrid, Spain
  5. Faculty of Agronomy and Crop Science, University of Rostock, Germany
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Abstract

In this study, a SUS316L membrane having double layered pore structures was fabricated, and the pore characteristics were analyzed after coating with a spherical powder and a flake-shaped powder on a disk-shaped SUS316L support using a wet powder spraying process. The thickness of the coated layer was checked using an optical microscope, and air permeability was measured using a capillary flow porometer. When the coating amount was similar, the fine porous layer prepared using flake powder was thicker and showed higher porosity. In the case of a similar thickness, the case of using flake powder was half of the amount of spherical powder used. Therefore, it was confirmed that it is possible to manufacture a metal membrane having a high filter efficiency even with a small coating amount when using the flake powder.
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Authors and Affiliations

Min-Jeong Lee
1 2
ORCID: ORCID
Hyeon-Ju Kim
1
ORCID: ORCID
Manho Park
3
ORCID: ORCID
Jung-Yeul Yun
1
ORCID: ORCID

  1. Korea Institute of Materials Science (KIMS), Metal Powder Department, Changwon 51508, Republic of Korea
  2. Pusan National University Department of Materials Science and Engineering, Republic of Korea
  3. R&D Center, ASFLOW Co. Ltd, Suwon, Republic of Korea

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