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Wyświetlanie 1-15 z 155
Tytuł:
Parametric study of the earth dams behaviour subjected to earthquake
Autorzy:
Ayeche, H.
Zitouni, Z.
Limam, A.
Bouafia, A.
Powiązania:
https://bibliotekanauki.pl/articles/2172886.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
earth dam
earthquake
slope stability
block method
Sarma method
Opis:
Static stability of an earth dam can be established by estimating the static safety factor equal to the ratio of the shear strength to the shear stress along a critical sliding area. In contrast, it is more complicated to evaluate the dynamic stability during an earthquake. The water filling the interstices of the earth dams cannot drain during the short duration of an earthquake. An excess pore water pressure DU develops, and its role is predominant in the destabilisation of the dam. The pore water increase causes a decrease in the soil shear strength. It is, therefore, crucial to evaluate and take into consideration DU in the dam dynamic stability analysis. This research is a contribution to reach this objective. A parametric study was conducted by varying the physical and mechanical soil characteristics constituting the dam, as well as its geometrical values, in order to evaluate their effects on the dynamic safety factor. The dynamic safety factor is calculated using the pseudo-static method, taking into account the excess pore water pressure that develops during cyclic loading into the granular soil of the earth dam upstream face. The results of the parametrical analytical study were also compared to the results of numerical simulations of the dam seismic stability trough pseudo-static method. The numerical simulations were done with three different software: PLAXIS and ABAQUS (based on the finite element method) and GEOSTAB (deals with the problem at the limit equilibrium using the simplified Bishop method). At the end, on one hand, we were able to describe how and at what level of the dam upstream face the sliding occurs, and on the other hand, we were able to underline the adequate combination between the dam geometric parameters and the mechanical soil characteristics which may ensure seismic stability.
Źródło:
Studia Geotechnica et Mechanica; 2022, 44, 4; 267--281
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Random vortex method in numerical analysis of 2D flow around circular cylinder
Autorzy:
Kostecki, S.
Powiązania:
https://bibliotekanauki.pl/articles/178682.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
vorticity
vortex method
flow instability
circular cylinder
boundary element method
Opis:
A combination of the vortex method and the boundary element method is used here to predict the two-dimensional flow field around a circular cylinder. Cylindrical structures experience strong hydrodynamic loading, due to vortex detachment from the both sides of cylinder during the flow. Thus, the practical meaning of such calculation is significant particularly in offshore oil and gas engineering as well as in the bridge and hydraulic structure engineering. This paper presents the mathematical formulation of the vortex method for the velocity and vorticity field calculation. The calculated velocity and vorticity fields are then used to predict the pressure distribution on the cylinder surface by the boundary element method. The resulting pressure on the cylinder, the Strouhal number and the length of the base recirculation zone are compared with solutions of other numerical methods and experiments, and a good agreement is achieved.
Źródło:
Studia Geotechnica et Mechanica; 2014, 36, 4; 57-63
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on gas holdup characteristics of micro-bubble countercurrent contacting flotation column
Autorzy:
Han, Jikang
Wang, Weizhi
Li, Ran
Powiązania:
https://bibliotekanauki.pl/articles/1449071.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
column flotation
conductance method
pressure drop method
gas holdup
GE-609
Opis:
In order to explore the gas holdup distribution of the microbubble countercurrent contact flotation column in the hematite column cationic reverse flotation process, respectively using conductance method and pressure drop method for air and water as experimental medium characteristics research of flotation column, the research group carries on the gas holdup, examines the aeration quantity, the fill medium and cation collector alkyl polyamine ether (An amine collector―GE609 which consists of four elements: carbon, hydrogen, oxygen and nitrogen)within the column on the influence of the axial and radial gas holdup. The results show that the axial gas holdup from the bottom of the column to the top of the column increases with the increase of height in the range of 0.050.07dm3/s. The radial distribution of gas holdup generally shows the distribution law of “intermediate high, low on both sides”. After the filling medium is added into the column, the radial gas holdup is evenly distributed compared with the empty column, and the gas holdup is increased. Due to the high foaming performance of GE-609, the gas holdup in the column can be increased by changing the amount of aeration and the concentration of the reagent, which can exceed 60% at the maximum. Like other alcohol foaming agents, as time passes, the effect of GE-609 weakens and the gas holdup in the column gradually decreases. The addition of quantitative HCl can improve the foaming performance of GE-609, and the gas holdup in the column is significantly improved and the stability is enhanced.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 4; 665-675
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic response of three-layered annular plate with imperfections
Autorzy:
Pawlus, D.
Powiązania:
https://bibliotekanauki.pl/articles/178521.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
sandwich
annular plate
dynamic stability
imperfections
finite difference method
finite element method
Opis:
This paper presents the imperfection sensitivity of annular plate with three-layered structure. The plate composed of thin elastic facings and a thicker elastic core is loaded in facing plane. The classical issue of a three-layered plate was solved for dynamic deflection problem using the approximation methods: orthogonalization and finite difference. The solution includes the axisymmetric and asymmetric plate modes of the dynamic stability loss. The evaluation of the rate of plate sensitivity to imperfection of plate preliminary geometry has been enriched by the analysis of plate models built of finite elements. The ABAQUS program has been used. The numerous calculation results in the form of deflection characteristics, buckling modes, values of critical parameters create the view of response of dynamic plate structure with different rate of imperfection and linear in time loading growth, too.
Źródło:
Studia Geotechnica et Mechanica; 2014, 36, 4; 13-25
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selected Nature-Inspired Algorithms in Function of PM Synchronous Motor Cogging Torque Minimisation
Autorzy:
Cvetkovski, Goga Vladimir
Petkovska, Lidija
Powiązania:
https://bibliotekanauki.pl/articles/1955984.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
permanent magnet synchronous motor
optimisation method
cogging torque
genetic algorithm
finite element method
Opis:
Both permanent magnet brushless DC motors and permanent magnet synchronous motors have attracted wide attention and are increasingly used in industrial high-performance applications in recent years. Those motors are known for their good electrical, magnetic and performance characteristics, but there is one parameter known as cogging torque that has a negative influence on the performance characteristics of the motor. This pulsating torque is generated as a result of the interaction between the stator teeth and the permanent magnets. The minimisation of the ripple of this torque in those permanent magnet motors is of great importance and is generally achieved by a special motor design which in the design process involves a variety of many geometrical motor parameters. In this research work, a novel approach will be introduced where two different nature-inspired algorithms, such as genetic algorithm (GA) and cuckoo search (CS) algorithm are used as an optimisation tool, in which the defined equation for the maximum value of the cogging torque is applied as an objective function. Therefore, a proper mathematical presentation of the maximum value of the cogging torque for the analysed synchronous motor is developed and implemented in the research work. For a detailed analysis of the three different motor models, the initial motor and the two optimised motor models are modelled and analysed using a finite element method approach. The cogging torque is analytically and numerically calculated and the results for all the models are presented.
Źródło:
Power Electronics and Drives; 2021, 6, 41; 204-217
2451-0262
2543-4292
Pojawia się w:
Power Electronics and Drives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Satisfaction of the condition of order preservation : a simulation study
Autorzy:
Mazurek, Jiří
Kułakowski, Konrad
Powiązania:
https://bibliotekanauki.pl/articles/406465.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
pairwise comparisons
eigenvalue method
geometric mean method
condition of order preservation
numerical simulation
Opis:
We examine the satisfaction of the condition of order preservation (COP) concerning different levels of inconsistency for randomly generated multiplicative pairwise comparison matrices (MPCMs) of the order from 3 to 9, where a priority vector is derived both by the eigenvalue (eigenvector) method (EV) and the geometric mean (GM) method. Our results suggest that the GM method and the EV method preserve the COP almost identically, both for the less inconsistent matrices (with Saaty’s consistency index below 0.10), and the more inconsistent matrices (Saaty’s consistency index equal to or greater than 0.10). Further, we find that the frequency of the COP violations grows (almost linearly) with the increasing inconsistency of MPCMs measured by Koczkodaj’s inconsistency index and Saaty’s consistency index, respectively, and we provide graphs to illustrate these relationships.
Źródło:
Operations Research and Decisions; 2020, 30, 2; 77-89
2081-8858
2391-6060
Pojawia się w:
Operations Research and Decisions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design of the usability of ceramic sanitary ware waste in cement production using the Taguchi method
Autorzy:
Toker, Melis Derdiyok
Perek, K. Tahsin
Powiązania:
https://bibliotekanauki.pl/articles/24148646.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
cement
ceramic waste
Taguchi method
Opis:
The cement process is one of the industries where energy is consumed intensively. High levels the amount of carbon dioxide emission reaches since the nature of the raw materials used in its production. At this point, using industrial wastes and by-products containing oxides such as calcium, silica, alumina, and iron oxides blended cement reduces energy consumption and carbon dioxide emissions. In this study, the effects of using ceramic sanitary ware waste (CSW) instead of clinker on the cement grinding stage were investigated. The grinding tests were carried out with clinker in a ball mill, according to grinding parameters as ball filling ratio, ball diameter, and grinding time by using Taguchi method for optimization of cement grinding condition. The reference and blended cements with CSW were determined compressive strength.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 5; art. no. 168256
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulation of crater creating process in dynamic replacement method by smooth particle hydrodynamics
Autorzy:
Danilewicz, A.
Sikora, Z.
Powiązania:
https://bibliotekanauki.pl/articles/178657.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
dynamic replacement method
SPH
impact soil
Opis:
A theoretical base of SPH method, including the governing equations, discussion of importance of the smoothing function length, contact formulation, boundary treatment and finally utilization in hydrocode simulations are presented. An application of SPH to a real case of large penetrations (crater creating) into the soil caused by falling mass in Dynamic Replacement Method is discussed. An influence of particles spacing on method accuracy is presented. An example calculated by LS-DYNA software is discussed. Chronological development of Smooth Particle Hydrodynamics is presented. Theoretical basics of SPH method stability and consistency in SPH formulation, artificial viscosity and boundary treatment are discussed. Time integration techniques with stability conditions, SPH+FEM coupling, constitutive equation and equation of state (EOS) are presented as well.
Źródło:
Studia Geotechnica et Mechanica; 2014, 36, 3; 3-8
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Innovative Look at the 'General Method' of Assessing Buckling Resistance of Steel Structures
Autorzy:
Czepiżak, Dariusz
Powiązania:
https://bibliotekanauki.pl/articles/2037728.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
steel structure
stability
buckling
general method
Opis:
Stability checking is an essential element of the dimensioning of steel frame structures. One of the stability checking methods allowed by EN 1993-1-1 is the so-called general method of assessing structural stability, based on buckling curves and relative structure slenderness λ¯op usually determined through numerical analyses. But this method is not widely used because of the limited computing capabilities of the engineering programs dedicated to static load analyses and difficulties in interpreting the results of the computations. The commonly used computer programs enable one to determine the shape of buckling and critical load amplifier αcr, from which one cannot directly determine the risk of buckling of a real structure. This paper presents a modified and innovative approach to the general method of assessing structural stability, which uses only three parameters, that is, the type of cross section, cross-section strength utilisation and αcr, to determine a member’s/structure’s bearing capacity mobilisation from the stability condition. The problem solution is presented in the form of simple formulas and legible diagrams. Finally, synthetic conclusions are formulated.
Źródło:
Studia Geotechnica et Mechanica; 2021, 43, 4; 337-345
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization of optical uniformity factors of backlight module using robust design method
Autorzy:
Wang, Ju-Chi
Fan, Yu-Cheng
Fang, Te-Hua
Tran, Anh-Son
Cheng, Yu-Ting
Powiązania:
https://bibliotekanauki.pl/articles/2060680.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
backlight module
uniformity
Taguchi method
LightTools
Opis:
In order to meet the advent of the high-definition liquid crystal display (LCD) era, in addition to the high-quality panel manufacturing technology, how the backlight module can provide a uniform backlight with higher uniformity for a better experience in viewing, is a very important and urgent issue. In this study, the 15.6-inch side-in backlight module was used as the benchmark, and the Taguchi method was applied to find the high uniformity. The matching of the fishbone diagram affects the optical uniformity factor of the backlight module, such as the size of the light guide plate dot, the color of the plastic frame, the color of the fixed gel of the light guide plate, and the difference of the reflection surface. The optical analog software LightTools is used according to the orthogonal table. The signal-to-noise (S/N) ratio of the average uniformity characteristics is obtained, then it is converted into the best response factor of the factor response table and the factor reaction diagram. The homogeneity at 13 points is as high as 90.12%, which is 4.72% higher than the original design factor. The contribution of the four factors to the uniformity can be obtained by using the variance analysis. Finally, the influence of each factor level on the uniformity is discussed.
Źródło:
Optica Applicata; 2022, 52, 1; 5--20
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A comparative study of advanced oxidative processes. Degradation of chlorinated organic compounds in ultrafiltration fractions of kraft pulp bleaching effluent
Autorzy:
Fiskari, J.
Kakkonen, A.
Pakkanen, H.
Alén, R.
Powiązania:
https://bibliotekanauki.pl/articles/208297.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
photocatalysis
Fenton method
metoda Fentona
fotokataliza
Opis:
Oxidative pretreatment methods such as the Fenton oxidation, ozonation, and photocatalytic treatment have been compared in reducing adsorbable organic halogens (AOX) and chlorophenolic compounds in untreated kraft pulp bleaching effluent. Their efficiency was also studied on effluent ultrafiltration fractions. The Fenton treatment removed all analyzed chlorophenolic compounds from the effluent. Ozonation and photocatalysis appeared to be much less effective methods. The efficiency of the Fenton oxidation appeared to be more pronounced in higher molecular weight effluent fractions. This suggests a novel design, where the filtration stage can be placed after the oxidation, and the high-molecular weight fraction is returned to the Fenton treatment.
Źródło:
Environment Protection Engineering; 2016, 42, 4; 151-159
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pile load capacity – calculation methods
Autorzy:
Wrana, B.
Powiązania:
https://bibliotekanauki.pl/articles/178838.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
pile load capacity calculation
Eurocode 7
α – method
β – method
direct methods based on CPTu data
Opis:
The article is a review of the current problems of the foundation pile capacity calculations. The article considers the main principles of pile capacity calculations presented in Eurocode 7 and other methods with adequate explanations. Two main methods are presented: α – method used to calculate the short-term load capacity of piles in cohesive soils and β – method used to calculate the long- term load capacity of piles in both cohesive and cohesionless soils. Moreover, methods based on cone CPTu result are presented as well as the pile capacity problem based on static tests.
Źródło:
Studia Geotechnica et Mechanica; 2015, 37, 4; 83-93
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selective nickel-iron separation from atmospheric leach liquor of a lateritic nickel ore using the para-goethite method
Autorzy:
Basturkcu, H.
Acarkan, N.
Powiązania:
https://bibliotekanauki.pl/articles/110361.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
iron precipitation
nickel loss
para-goethite method
Opis:
The presence of iron in pregnant leach solutions (PLS) is a common problem, and is generally removed using jarosite, goethite, hematite or para-goethite precipitation methods. Although these methods are successfully applied, significant amounts of nickel can be lost. In this study, iron precipitation was performed on a PLS obtained from agitation leaching of a lateritic nickel ore under atmospheric conditions using the para-goethite method. The PLS contained 2.62 g/dm3 Ni, 54.28 g/dm3 Fe and 0.14 g/dm3 Co. During the precipitation tests the effect of pH, time, temperature, and metal concentration were investigated. The influence of the key points, temperature and metal concentration, on nickel loss was explained in reference to SEM and XRD analyses. Ultimately, selective nickel and iron separation was achieved with complete iron precipitation and only 1.2% Ni loss.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 1; 212-226
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A system consists of lifted steel tank and four assembly supports with variable assembly conditions
Autorzy:
Zamorowski, J.
Gremza, G.
Powiązania:
https://bibliotekanauki.pl/articles/178929.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
tank
method of erection
hydraulic jacking
disaster
Opis:
In the method of steel tank erection, consisting in assembling the roof and the next courses (segments) of the shell at the ground level, starting from the top one (the so-called hydraulic jacking-up method), the assembled part of the tank is lifted using assembly supports (towers, trestles), hydraulic jacks and ropes. Supports are located inside or outside the tank, and their bases are usually not anchored. During the assembly work, numerous contaminations can appear under the bases of the supports; therefore, boundary conditions of the system consisting of the elevated tank and assembly supports may change, influencing the field of displacements and stresses in the elements of this system. This article presents the results of numerical tests of an exemplary mounted tank – mounting support system – at various possible coefficients of friction between the bases of the supports and the ground. The influence of the support conditions on the effort of the essential elements of the system was assessed. Calculation difficulty was noted to determine the directions of horizontal responses of the supports. It was assumed that these directions did not change after exceeding the values of the friction forces. The analysed tank collapsed during its erection.
Źródło:
Studia Geotechnica et Mechanica; 2018, 40, 4; 263-269
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A comprehensive approach to the optimization of design solutions for dry anti-flood reservoir dams
Autorzy:
Łydżba, Dariusz
Różański, Adrian
Sobótka, Maciej
Pachnicz, Michał
Grosel, Szczepan
Rainer, Jakub
Powiązania:
https://bibliotekanauki.pl/articles/1845146.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
finite element method
stability
settlement
filtration
kriging
Opis:
The article proposes the methodology of designing dams of dry flood control reservoirs. The algorithm is developed so as to meet all the requirements given in the Eurocode 7 and, at the same time, to be efficient in terms of necessary calculation time. Furthermore, the presented numerical procedure enables the optimization of design solutions, e.g. the depth and length of the anti-filtration barrier, by means of parametric analyses. The approach assumes the use of numerical methods, in particular, finite element (FE) analysis. Three-dimensional (3D) reconstruction of the terrain topography and subsoil layer arrangement performed in step (1) sets the base for further analyses. In step (2), the filtration phenomena are assessed based on the 3D analysis of a transient groundwater flow. In step (3), the state of displacement is evaluated and the stability is verified for all the relevant phases of construction and operation of the facility, in particular, in the course of simulated flood detention. The analyses in step (3) are carried out on 2D models corresponding to the design cross-sections of the dam. This significantly reduces the computation time (compared to 3D analysis) and, at the same time, provides a safe estimate of factor of safety. The performance of the proposed algorithm is shown on the numerical examples of the computations concerning the dam of Szalejów Górny dry anti-flood reservoir located in Poland.
Źródło:
Studia Geotechnica et Mechanica; 2021, 43, 3; 270-284
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 155

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