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Wyszukujesz frazę "size effect" wg kryterium: Temat


Tytuł:
Size effect at testing strength properties of concrete
Autorzy:
Akram, Amanda
Powiązania:
https://bibliotekanauki.pl/articles/1955920.pdf
Data publikacji:
2021
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
concrete
size effect
tensile strength
Opis:
Various strength characteristics of concrete are considered as fracture parameters. The compressive strength of concrete is of paramount importance when designing concrete structures, whereas tensile strength of concrete is the basic property when estimating cracking resistance of a structure and analysing fracture processes in concrete. When testing the compressive strength of concrete, the results are dependent on the shape and dimensions of used specimens. Some findings reported in the literature suggest that size effect exists also when testing such fracture properties of concrete as tensile strength. Unfortunately this problem is much less recognized and described compared to size effect in compressive test results. In this paper, the experimental investigation is presented on how the length of cylindrical specimens influences the tensile splitting strength of concrete obtained by means of the Brazilian method. Additional variable parameters were: type of aggregate (natural gravel and crushed granite) and cement-water ratio (C/W = 1.8 and C/W = 2.6). In conducted laboratory experiments a higher splitting tensile strength of concrete was noted for all specimens with nominal dimensions of 150×150 mm, compared to specimens 150×300 mm in size, regardless of type of aggregate or cement-water ratio.
Źródło:
Budownictwo i Architektura; 2021, 20, 4; 37-45
1899-0665
Pojawia się w:
Budownictwo i Architektura
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Importance of the Size of Local Government in Avoiding the Fiscal Distress - Empirical Evidence on Communes in Poland
Autorzy:
Galiński, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/16729115.pdf
Data publikacji:
2023
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
fiscal distress
local government
size effect
Opis:
Theoretical background: In the literature on finance there are findings which examine reasons for the fiscal distress of units of the public sector, including local governments. However, this distress might be differently defined. Therefore, it determines both the approach to identify this phenomenon and the types of explanatory variables. Nevertheless, in the field of the business sector in the econometric models concerning the financial distress the size of the unit is considered. In this case there are also some possibilities to apply the correct proxy variable. This results from the fact that the size of local government might determine its fiscal capability as well as the level and structure of expenditures, which affect fiscal distress. Purpose of the article: The aim of this paper is to examine the influence of the size of the local government on the probability of the decrease of the exposure to the fiscal distress. Research methods: The author reviewed the literature in the field of the fiscal distress and introduced a multi-criteria decision analysis as well as a logistic regression modelling to examine this. The research procedure also required the use of the linear ordering to construct the dependent variable of the fiscal distress in order to analyse the “size effect” on the fiscal distress. Main findings: Fiscal distress of local governments is a core issue, which should be constantly analysed. It depends on the financial, economic, social and even political aspects. To identify exposure to this distress the TOPSIS method can be used. However, the fiscal distress can be affected by the size of the unit, which influences lots of budgetary categories. Due to the specificity of dependent and independent variables in the econometric models the “size effect” might be represented through the level of the population or the assets. Using the ordinal logistic regression in the research, the authors should consider that this effect can differ between the units with the disparate exposure. So, the partial proportional odds models can be required. Thus, the growth of the size of the unit, measured by the population, increases the odds of reaching very low exposure to fiscal distress. Simultaneously, there are some other important issues which should be included in this type of research.
Źródło:
Annales Universitatis Mariae Curie-Skłodowska, sectio H – Oeconomia; 2022, 56, 5; 101-113
0459-9586
2449-8513
Pojawia się w:
Annales Universitatis Mariae Curie-Skłodowska, sectio H – Oeconomia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ubiquitiformal fracture energy
Autorzy:
Ou, Z.-C.
Yang, M.
Li, G.-Y.
Duan, Z.-P.
Huang, F-L.
Powiązania:
https://bibliotekanauki.pl/articles/280189.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
fractal
ubiquitiform
fracture energy
size effect
Opis:
The ubiquitiformal fracture energy is proposed in the paper and its explicit expression is obtained. Moreover, the numerical results for concrete are found to be in good agreement with those for the critical strain energy release rate. The discrepancy between the numerical results of the traditional fracture energy and the critical strain energy release rate can be explained reasonably, which implies that the ubiquitiformal fracture energy should be taken as an available fracture parameter of materials. Finally, it is numerically found for some concrete that there is not size effect for the ubiquitiformal fracture energy.
Źródło:
Journal of Theoretical and Applied Mechanics; 2017, 55, 3; 1101-1108
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inner Size Effect in Layered Films with Eutectic Interaction of Components
Autorzy:
Dukarov, S.
Petrushenko, S.
Sukhov, V.
Churilov, I.
Samsonik, A.
Skryl, O.
Powiązania:
https://bibliotekanauki.pl/articles/1030004.pdf
Data publikacji:
2018-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
inner size effect
multilayer films
interfacial energy
Opis:
The results of the study of melting of Bi-Sn and Pb-Sn polycrystalline layered film systems with the thickness of 200-400 nm on a substrate with temperature gradient are given. Multilayer (each layer is of 10-20 nm) and bilayer films (layers are of 100-200 nm) of the same total thickness have been investigated. Broadening of the melting range in all films and lowering of melting point in multilayer samples compared to the bilayer ones have been observed. The observed phenomena are discussed within existing thermodynamic concepts in consideration of interfacial energy of contacting layers of components and energy of grain boundaries in polycrystalline films.
Źródło:
Acta Physica Polonica A; 2018, 133, 5; 1186-1190
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On some problems in determining tensile parameters of concrete model from size effect tests
Autorzy:
Marzec, Ireneusz
Bobiński, Jerzy
Powiązania:
https://bibliotekanauki.pl/articles/260481.pdf
Data publikacji:
2019
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
concrete
size effect
fracture energy
elasto-plasticity
XFEM
Opis:
The paper presents results of numerical simulations of size effect phenomenon in concrete specimens. The behaviour of in-plane geometrically similar notched and unnotched beams under three-point bending is investigated. In total 18 beams are analysed. Concrete beams of four different sizes and five different notch to depth ratios are simulated. Two methods are applied to describe cracks. First, an elasto-plastic constitutive law with a Rankine criterion and an associated flow rule is defined. In order to obtain mesh independent results, an integral non-local theory is used as a regularisation method in the softening regime. Alternatively, cracks are described in a discrete way within Extended Finite Element Method (XFEM). Two softening relationships in the softening regime are studied: a bilinear and an exponential curve. Obtained numerical results are compared with experimental outcomes recently reported in literature. Calculated maximum forces (nominal strengths) are quantitatively verified against experimental values, but the force – displacement curves are also examined. It is shown that both approaches give results consistent with experiments. Moreover, both softening curves with different initial fracture energies can produce similar force-displacement curves.
Źródło:
Polish Maritime Research; 2019, 2; 115-125
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of dynamic growth of a micro-scaled void based on strain gradient elasto-plasticity
Autorzy:
Ma, Xinbing
Liu, Jinxing
Wang, Jiadong
Pan, Hao
Powiązania:
https://bibliotekanauki.pl/articles/1839598.pdf
Data publikacji:
2020
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
dynamic void growth
size effect
inertia
thermal softening
Opis:
Void initiation and growth serve as an important mechanism in ductile failures in metals. Particularly, on the micron-level, the extra hardening effect associated with strain gradient is accounted for by adopting strain gradient elasto-plasticity instead of the conventional plasticity. Effects of inertial, strain gradient hardening and thermal softening are formulated analytically for the case where a spherical void expands under external hydrostatic stress. As demonstrated by our results, the inertia effect firstly tends to hinder but then promotes the void growth. The threshold stress required for rapid void growth is lifted due to extra hardening of strain gradient so that the growth of a smaller void is delayed more remarkably. A considerable thermal softening phenomenon is observed here, which is caused by plastic work during the deformation process. The final void growth rate is mainly related to the maximum loading, which is consistent with the prediction based on the classical plastic theory.
Źródło:
Journal of Theoretical and Applied Mechanics; 2020, 58, 4; 927-941
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of particle size and feed rate on coal cleaning in a dry separator
Autorzy:
Kademli, M.
Gulsoy, O. Y.
Powiązania:
https://bibliotekanauki.pl/articles/110339.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
dry coal cleaning
particle size effect
air separator
Opis:
This research is concerned with the effects of particle size distribution and feed rate of feed on the coal cleaning performance of table type air separator. In tests, the lignite and hard coal samples from Mugla and Zonguldak districts in Turkey were used. The samples were tested in three different size distributions such as –38 + 6 mm, –19 + 6 mm and –9.5 + 6 mm. The effect of particle size was investigated together with the feed rate 2 Mg/(hm2), 1.68 Mg/(hm2) and 1.32 Mg/(hm2) and very important physical parameters of table type air separator such as, riffle height, table slope and table frequency. Results were analyzed by using the Tromp curve for indicating the effects in detail. Consequently, the results revealed that the particle size had remarkable effect on separation efficiency. The separation efficiency was, however, inversely affected as the particle size distribution became finer, and the best results were obtained in particle size distribution was –38 + 25 mm in both sample tested. The Ep value was 0.11 for the hard coal samples while it was 0.13 for the lignite samples.
Źródło:
Physicochemical Problems of Mineral Processing; 2016, 52, 1; 204-213
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of pre-tension on torsion of microscale Cu wires: a study via strain gradient theory
Autorzy:
Ma, Xinbing
Liu, Jinxing
Powiązania:
https://bibliotekanauki.pl/articles/280360.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
nonproportional loading
strain gradient plasticity
size effect
cyclic response
Opis:
Nonproportional plastic deformations on the microscale are an emerging topic. A simplified theory of strain gradient elasto-plasticity is developed to study the evolution of yield strength in a copper wire sequentially experiencing tension and torsion. The pre-tension deformation and stress are inherited to the upcoming torsion process, resulting in a nonproportional loading condition. With consideration of the extra hardening effect due to strain gradient, pre-tension weakens the extra hardening effect of the strain gradient and the dependence on the wire radius. Cyclic torsion behavior is also investigated. Anomalous Bauschinger effect and plastic softening are found.
Źródło:
Journal of Theoretical and Applied Mechanics; 2019, 57, 4; 1055-1065
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fatigue life prediction of aluminium profiles for mechanical engineering
Autorzy:
Tomaszewski, T.
Sempruch, J.
Powiązania:
https://bibliotekanauki.pl/articles/281070.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
aluminium profile
high-cycles fatigue
mini specimen
size effect
Opis:
The study presents a method to determine the σa − N curve (high cycle fatigue) for profiles made of AW-6063 T6 aluminium alloy. Experimental material data for a mini specimen taken directly from the tested item and selected empirical correlations allowing for a size effect have been used. A model yielding the lowest relative error of estimating the fatigue life is presented.
Źródło:
Journal of Theoretical and Applied Mechanics; 2017, 55, 2; 497-507
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on optimization method of flotation kinetic model based on molybdenite particle size effect
Autorzy:
Wan, He
An, Yanni
Qu, Juanping
Zhang, Chonghui
Xue, Jiwei
Wang, Sen
Bu, Xianzhong
Powiązania:
https://bibliotekanauki.pl/articles/24085892.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
particle size effect
molybdenite
mathematical model
method of correction
Opis:
Flotation kinetic models can be applied to describe the flotation process and to predict mineral recoveries. However, the size composition of the target minerals in the feed ore fluctuates considerably, resulting in insufficient accuracy with flotation kinetic models. There have been many studies that focus on the investigation of flotation kinetics with different particle sizes, while the optimization methods for flotation kinetic models based on particle size effects have not been reported. In this paper, flotation tests, optical microscope observations, and particle size analysis were used to identify the reasons for the decrease in accuracy of the flotation kinetic model due to changes in the composition of molybdenite particle size. Additionally, an optimization method for the flotation kinetic model was developed based on the particle size effect. The test results show that the accuracy of the flotation kinetic model for fixed particle size minerals is very high, but the predicted results for flotation recoveries of different particle size mineral mixtures have large deviations. The poor accuracy might be due to the autogenous carrier effect caused by the particle size composition fluctuating considerably. The optimization method for the flotation kinetic model is based on the particle size effect. The model can accurately describe the flotation process of molybdenite with different size compositions of molybdenite and predict the flotation recovery of molybdenite.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 2; art. no. 163004
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł

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