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Tytuł:
Numerical analysis of stress intensity factor and T-stress in pipeline of steel P264GH submitted to loading conditions
Autorzy:
Moustabchir, H.
Arbaoui, J.
Zitouni, A.
Hariri, S.
Dmytrakh, I.
Powiązania:
https://bibliotekanauki.pl/articles/281034.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
T-stres
Stress Intensity Factor (SIF)
Finite Element Method (FEM)
Stress Difference Method (SDM)
volumetric method
Opis:
Stress singularities occur at crack tips, corners and material interfaces. The stress intensity factors and T-stresses are coefficients of structural components where the active stress singular and first regular stress terms, respectively, are denoted by William’s eigen function expansion series. A finite element analysis by CASTEM 2000 have been undertaken in order to determine the evolution of the T-stress and stress intensity factor terms in mode I for an arc of pipeline specimens with an external surface crack. A stress difference method described by Moustabchir et al. (2012) are adapted and, in the following step, the volumetric method is then embedded to compute the SIFs and T-stress near the crack tip. Different crack geometries combined with different length-to-thickness ratios are examined for the T-stress and stress-intensity factor. The revisited stress difference method employed here shows to be an accurate and robust scheme for evaluating the T-stress/SIFs in an arc of the pipeline.
Źródło:
Journal of Theoretical and Applied Mechanics; 2015, 53, 3; 665-672
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigation of mechanical behavior of cracked cruciform specimens in aluminum alloy 6082-T6 subjected to different biaxial loading conditions
Autorzy:
Khelil, Foudil
Aour, Benaoumeur
Talha, Abderrahim
Benseddiq, Noureddine
Powiązania:
https://bibliotekanauki.pl/articles/281224.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
fracture mechanics
6082-T6 aluminum alloy
cruciform specimen
finite element analysis
stress intensity factor
T-stress
biaxiality
Opis:
Analysis of cracked cruciform specimens under biaxial loading conditions is very important and closer to reality in the study of behavior of marine, naval, aeronautical and railway structures. The aim of this work is to examine the evolution of fracture parameters in a combined mixed mode of an aluminum alloy A6082-T6 cruciform specimen as a function of the biaxial loading with different ratios. To this end, the effects of main parameters, such as load ratio, crack length, crack orientation and non-proportional loading coefficient have been analyzed and discussed in order to highlight fracture toughness of the studied material. The results show that the finite element method is a useful tool for calculation of crack characteristics in the mechanics of biaxial fracture. According to the obtained results, a non-proportional evolution of the fracture parameters, namely, the SIFs KI and KII , T-stress, and the biaxiality parameter was observed. Indeed, the latter depends considerably on the crack length, the angle of crack orientation and the applied biaxial loading. Detailed concluding remarks are presented at the end of this work.
Źródło:
Journal of Theoretical and Applied Mechanics; 2019, 57, 4; 1021-1037
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of fracture parameters for crack problems in fgm by a meshless method
Wyznaczanie parametrów pękania dla szczelin w materiałach funkcjonalnie gradientowych metodą bezsiatkową
Autorzy:
Sladek, J.
Sladek, V.
Zhang, C.
Tan, C.-L.
Powiązania:
https://bibliotekanauki.pl/articles/280798.pdf
Data publikacji:
2006
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
parametry pękania
analiza szczelin
naprężenia T
materiały funkcjonalnie gradientowe
stress intensity factors
T-stress
meshless methods
hermoelasticity
nonhomogenity
orthotropic materials
Opis:
A meshless method based on the local Petrov-Galerkin approach is proposed for crack analysis in two-dimensional (2D), anisotropic and linear elastic solids with continuously varying material properties. Both quasi-static thermal and transient elastodynamic problems are considered. For time-dependent problems, the Laplace transform technique is utilized. The analyzed domain is divided into small subdomains of circular shapes. A unit step function is used as the test function in the local weak form. It leads to Local Integral Equations (LIE) involving a domain-integral only in the case of transient dynamic problems. The Moving Least Squares (MLS) method is adopted for approximating the physical quantities in the LIE. Efficient numerical methods are presented to compute the fracture parameters, namely, the stress intensity factors and the T-stress, for a crack in Functionally Graded Materials (FGM). The path-independent integral representations for stress intensity factors and T-stresses in continuously non-homogeneous FGM are presented.
Przedstawiono bezsiatkową metodę analizy szczelin opartą na podejściu Petrova-Galerkina dla dwuwymiarowych liniowo-sprężystych i anizotropowych ośrodków o zmieniających się własnościach materiałowych. Rozważono zarówno kwazistatyczne problemy naprężeń cieplnych, jak i zagadnienia elastodynamiki, w których zastosowano aparat transformacji Laplace'a. Badany obszar podzielono na małe podobszary kołowe. Jako funkcję testową w lokalnej, słabej postaci zastosowano jednostkową funkcję schodkową, co prowadzi do lokalnych równań całkowych (LIE). Metodę ruchomych najmniejszych kwadratów (MLS) zastosowano do przybliżenia wielkości fizycznych w LIE. Przedstawiono efektywne metody numeryczne wyznaczania parametrów pękania, a w szczególności współczynników koncentracji naprężeń oraz naprężeń T dla szczelin w materiałach funkcjonalnie gradientowych (FGM). Przedstawiono niezależne od drogi całkowania reprezentacje tych parametrów w materiałach FGM o kontynualnie zmieniającej się niejednorodności.
Źródło:
Journal of Theoretical and Applied Mechanics; 2006, 44, 3; 603-636
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new BEM for modeling and simulation of 3T MDD laser-generated ultrasound stress waves in FGA smart materials
Autorzy:
Fahmy, Mohamed A.
Powiązania:
https://bibliotekanauki.pl/articles/29520102.pdf
Data publikacji:
2021
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
oundary element method
modeling and simulation
three-temperature
memory-dependent derivative
laser ultrasonic
nonlinear thermal stress waves
functionally graded anisotropic
smart materials
Opis:
The goal of this study is to present a new theory known as the three-temperature memory-dependent derivative (MDD) of ultrasound stress waves in functionally graded anisotropic (FGA) smart materials. It is extremely difficult to address the difficulties related to this theory analytically due to its severe nonlinearity. As a result, we suggest a new boundary element method (BEM) to solve such equations. The suggested BEM technique incorporates the benefits of both continuous and discrete descriptions. The numerical results are visually represented to demonstrate the impacts of MDD three temperatures and anisotropy on the ultrasound stress waves in FGA smart materials. The numerical findings verify the proposed methodology’s validity and accuracy. We may conclude that the offered results are useful for comprehending the FGA smart materials. As a result, our findings contribute to the advancement of the industrial applications of FGA smart materials.
Źródło:
Computer Methods in Materials Science; 2021, 21, 2; 95-104
2720-4081
2720-3948
Pojawia się w:
Computer Methods in Materials Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fatigue life estimation for selected materials in multiaxial stress states with mean stress
Autorzy:
Kluger, K.
Łagoda, T.
Powiązania:
https://bibliotekanauki.pl/articles/949216.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
multiaxial fatigue
mean stress
stress model
Opis:
This paper proposes a model for estimating fatigue life under multiaxial stress states, based on critical plane concepts, taking into account the effect of mean shear stress. The fatigue life test results calculated on the basis of the proposed model are compared to the experimental ones related to 2017A-T4 and 6082-T6 aluminium alloy, S355J0 alloy steel under constant-amplitude bending, torsion and proportional combinations of bending and torsion; Ti-6Al-4V alloy under tension-compression, torsion and combination tension-compression – torsion. For the results obtained, statistical analysis is performed by comparing the calculation results proposed by Findley and Dang Van criteria with the experimental data.
Źródło:
Journal of Theoretical and Applied Mechanics; 2016, 54, 2; 385-396
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Asymptotic stress field at the tip of an inclined crack terminating to an interface
Autorzy:
Marsavina, L.
Sadowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/390224.pdf
Data publikacji:
2008
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
crack
bi-material interface
asymptotic stress field
stress intensity factor
Opis:
This paper presents the numerical results for the asymptotic stress field and the fracture parameters at the tip of an inclined cracks terminating to a bi-material ceramic interface. The numerical analysis was carried out using FRANC2D/L fracture analysis code. A biaxial specimen was modeled for producing different mixed mode loads and two materials combinations of Al2O3 and ZrO2 were considered. The influence of the material combination and applied mixed mode load on the singularity orders, stress distributions and stress intensity factors is highlighted.
Źródło:
Budownictwo i Architektura; 2008, 2, 1; 111-124
1899-0665
Pojawia się w:
Budownictwo i Architektura
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Molecular mechanism of chloroplastic H2O2-mediated stress response in Arabidopsis
Autorzy:
Maruta, T.
Noshi, M.
Toida, E.
Tamoi, M.
Yamato, K.
Sawa, Y.
Ishikawa, T.
Shigeoka, S.
Powiązania:
https://bibliotekanauki.pl/articles/80030.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
conference
hydrogen peroxide
molecular mechanism
stress response
thylakoid membrane
ascorbate peroxidase
Arabidopsis
plant
photooxidative stress
oxidative stress
salicylic acid
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2013, 94, 2
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Life with oxidative stress
Autorzy:
Gurda, D.
Kietrys, A.M.
Szopa, A.
Twardowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/185377.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ROS
oxidative stress
antioxidants
oxidative stress response
stres oksydacyjny
przeciwutleniacze
reakcja na stres oksydacyjny
Opis:
Incomplete oxygen reduction gives rise to reactive oxygen species (ROS). For a long time they have been considered unwelcome companions of aerobic metabolism. Organisms using oxygen developed several systems of ROS scavenging with enzymatic and non enzymatic antioxidants, which allow them control the cellular level of oxygen derived from free radicals. It is well established nowadays that ROS are not necessarily negative byproducts, but they also play an important role in cellular mechanisms. They are involved in many regular cellular processes in all aerobic organisms. When the antioxidant system is overcome and the balance between ROS production and scavenging is disrupted, oxidative stress occurs. It has been reported that oxidative stress may be linked to some human diseases and is also involved in biotic and abiotic stress response in plants.
Źródło:
Chemical and Process Engineering; 2012, 33, 4; 509-528
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of titanium application on lettuce growth under Mn stress
Autorzy:
Kleiber, T.
Powiązania:
https://bibliotekanauki.pl/articles/960152.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie / Polskie Towarzystwo Magnezologiczne im. Prof. Juliana Aleksandrowicza
Opis:
Titanium (Ti) is classified as a beneficial element for plants. The aim of this study was to determine the effect of various Ti concentrations in nutrient solution on the alleviation of Mn-stress in hydroponically grown lettuce (Lactuca sativa L. cv. Zeralda). Plants were fertigated with nutrient solution of the following chemical composition (mg dm-3): N-NH4 < 10, N-NO3150, P-PO4 50, K 150, Ca 150, Mg 50, Fe 3.00, Mn 19.2, Zn 0.44, Cu 0.03, B 0.01, pH 5.50, EC 1.8 mS cm-1. The following Ti levels were tested (in mg Ti dm-3 of nutrient solution): 0 (control), 0.36; 0.72; 1.09 (denoted as Ti-I, Ti-II, Ti-III). The Ti source was Ti4+ ascorbate (Tytanit®). Ti had a positive effect on plant yielding: significantly the highest mean weight of a lettuce head and also the highest percentage of dry matter in leaves were found at Ti-II (+24.1% and 36.6%, respectively when compared with the control). Increasing Ti nutrition positively influenced the chlorophyll content (which was the highest at Ti-II and Ti-III), while it did not modify the Relative Water Content (RWC) in leaves. Despite the improved plant yielding, there were no differences in concentrations of macroelements (N, P, K, Ca, Mg) and some metallic microelements (Fe and Mn) in leaves. In turn, Ti nutrition significantly modified the nutrient uptake by aerial parts of plants, which increased up to Ti-II, while decreasing at Ti-III. The highest uptake of nutrients was recorded at Ti-II. Given the significant improvement in yield, Ti nutrition could be considered as an effective method to alleviate Mn-stress in lettuce.
Źródło:
Journal of Elementology; 2017, 22, 1
1644-2296
Pojawia się w:
Journal of Elementology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reactive oxygen species as second messengers? Induction of the expression of yeast catalase T gene by heat and hyperosmotic stress does not require oxygen.
Autorzy:
Krawiec, Zdzisława
Biliński, Tomasz
Schüller, Christoph
Ruis, Helmut
Powiązania:
https://bibliotekanauki.pl/articles/1044432.pdf
Data publikacji:
2000
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
yeast.
osmotic stress
thermotolerance
catalase T
oxygen
Saccharomyces cerevisiae
stress response
heat shock
Opis:
It is shown that oxygen is not absolutely needed for stress-induced synthesis of catalase T in the yeast Saccharomyces cerevisiae. Yeast cells develop heat resistance after exposure to elevated temperatures in anoxia. The levels of catalase activity and thermotolerance are comparable to those in aerobically stressed cells. While these results obviously do not exclude a stress signaling role of reactive oxygen species in some systems, as postulated by other authors, they suggest that the question of the obligatory requirement for reactive oxygen species in other stress signaling systems should be rigorously re-investigated.
Źródło:
Acta Biochimica Polonica; 2000, 47, 1; 201-207
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of shear stress distribution in a 90 degree channel bend
Autorzy:
Lee, S. K.
Dang, T. A.
Le, V. T.
Powiązania:
https://bibliotekanauki.pl/articles/265109.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
zginanie
naprężenie ścinające
erozja
experimental channel
90 degree bend
shear stress
erosion
deposition
Opis:
Shear stress is a key parameter that plays an important role in sediment transport mechanisms; therefore, understanding shear stress distribution in rivers, and especially in river bends, is necessary to predict erosion, deposition mechanisms and lateral channel migration. The aim of this study is to analyze the shear stress distribution near a river bed at 90-degree channel bend using a depth-average method based on experimental measurement data. Bed shear stress distribution is calculated using the depth-averaged method based on velocity components data has been collected from a 3D-ADV device (three-dimensional acoustic doppler velocity) at different locations of a meandering channel. Laboratory experiments have been made at the hydraulic laboratory of the RCRFIDF (Research Center for River Flow Impingement and Debris Flow), Gangneung-Wonju National University, South Korea to provide data for simulating the incipient motion of the riverbed materials and then predicting the river morphological changes in the curved rivers. The calculated results show that the maximum value of shear stress distribution near the riverbed in the different cross sections of the surveyed channel occurs in a 70-degree cross section and occurs near the outer bank. From the beginning of a 40-degree curved channel section, the maximum value of the shear stress occurs near the outer bank at the end of the channel.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 1; 213-220
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The role of miRNAs upon metal stress in Arabidopsis thaliana
Autorzy:
Gielen, H.
Remans, T.
Vangronsveli, J.
Cuypers, A.
Powiązania:
https://bibliotekanauki.pl/articles/80906.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
conference
microRNA
metal stress
plant
Arabidopsis thaliana
reactive oxygen species
gene expression
oxidative stress
signal transduction
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2013, 94, 2
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vigour of naked and husked oat cultivars under drought stress conditions
Autorzy:
Zielinski, A.
Simlat, M.
Wojtowicz, T.
Mos, M.
Powiązania:
https://bibliotekanauki.pl/articles/80585.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
conference
seed vigor
husked oat
naked oat
oat cultivar
drought stress
water stress
thermal condition
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2013, 94, 3
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of temperature on oxidative stress induced by lead in the leaves of Plantago major L.
Autorzy:
Balakhnina, T.I.
Borkowska, A.
Nosalewicz, M.
Nosalewicz, A.
Wlodarczyk, T.M.
Kosobryukhov, A.A.
Fomina, I.R.
Powiązania:
https://bibliotekanauki.pl/articles/24178.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
temperature effect
oxidative stress
lead
heat stress
oxidative destruction
leaf
Plantago major
ascorbate peroxidase
glutathione reductase
Źródło:
International Agrophysics; 2016, 30, 3
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Fusarium culmorum infection on survivability of a T-DNA tagged mutant of Arabidopsis thaliana harboring a mutation in the peptide transporter gene At5g46050
Autorzy:
Warzecha, T.
Lundh, D.
Mandal, A.
Powiązania:
https://bibliotekanauki.pl/articles/80558.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
abiotic stress
abscisic acid
Arabidopsis thaliana
biotic stress
disease resistance
ethylene
Fusarium culmorum
infection
jasmonic acid
mitogen-activated protein kinase
reactive oxygen species
stress condition
T-DNA tagging
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2011, 92, 1
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Barkhausen Noise Stress Characteristic of P265GH Boiler Steel
Autorzy:
Garstka, T.
Powiązania:
https://bibliotekanauki.pl/articles/1431792.pdf
Data publikacji:
2012-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.60.Ej
Opis:
In this paper characterization of internal mechanical stress state in boiler steel plate by the Barkhausen effect based method was presented. The affecting of calibration functions shape by tensile and compressive residual stress was observed. Beside of the significant residual stress anisotropy in sub-surface layers, unfavorable location of main directions of stress was revealed on both sides of the plate. The new method of calibration function without heat treatment of calibration specimens was elaborated and presented also. The investigations of Barkhausen noise as function of applied stress for different intensity and frequency of magnetization current were performed. Based on this, optimal magnetization conditions of doing measurement were estimated. Own construction of measuring apparatus for experiments was used.
Źródło:
Acta Physica Polonica A; 2012, 121, 4; 954-958
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stress among Finnish farm entrepreneurs
Autorzy:
Kallioniemi, M K
Simola, A.J.K.
Kymalainen, H.R.
Vesala, H.T.
Louhelainen, J.K.
Powiązania:
https://bibliotekanauki.pl/articles/50025.pdf
Data publikacji:
2008
Wydawca:
Instytut Medycyny Wsi
Tematy:
agriculture
risk factor
statistical method
mental health
antrepreneurship
stress prevalence
association
Finnish working population
farm
stress
Źródło:
Annals of Agricultural and Environmental Medicine; 2008, 15, 2
1232-1966
Pojawia się w:
Annals of Agricultural and Environmental Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The role of ascorbate during cadmium-induced oxidative stress in Arabidopsis thaliana
Autorzy:
Bielen, A.
Remans, T.
Vangronsveld, J.
Cuypers, A.
Powiązania:
https://bibliotekanauki.pl/articles/79901.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
conference
cadmium
oxidative stress
reactive oxygen species
cellular level
antioxidant defense system
stress condition
ascorbate peroxidase
Arabidopsis thaliana
ascorbate-glutathione cycle
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2013, 94, 2
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of true stress in engineering materials using optical deformation measurement methods
Autorzy:
Bogusz, P.
Popławski, A.
Morka, A.
Niezgoda, T.
Powiązania:
https://bibliotekanauki.pl/articles/241743.pdf
Data publikacji:
2012
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
true stress
optical deformation measurement
experimental studies
FEM
steel
Opis:
The aim of the paper is to evaluate a method of determining true stress in the steel sample subjected to static axial tensile on a universal testing machine. The tensile specimens were made of steel ST3, which was chosen because of its relatively high plastic deformations. Strain measurement was performed using traditional extensometers and additionally a non-contact optical deformation measuring system. Material properties were obtain by the extensometer measurements. The optical equipment registered the investigated sample through the optical system composed of two cameras and calculated a three-dimensional model of the material deformation in time. Displacement fields in axial and radial directions were determined with Digital Image Correlation method (DIC). Then the logarithmic axial strain map and radius shrinkage map in the area of the neck were obtained. Characteristic dimensions of the neck: curvature and width were also measured. It allowed determination of cross-section area changes in the real time, and in the result, calculation of actual true stress in the material during failure process. In this case Bridgman's and other scientists' formulas of stress distribution in the neck were applied. A numerical model, where material properties of finite elements were described by the Johnson-Cooke material model, was developed in LS-PrePost software. The FEM model was computed in LS-DYNA solver. The output tensile curve and neck curvature radius were compared with relevant data obtained from the optical measuring system.
Źródło:
Journal of KONES; 2012, 19, 4; 53-64
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Various biochemical changes of African marigold seedlings under sugar mill effluent stress
Autorzy:
Vaithiyanathan, T.
Sundaramoorthy, P.
Powiązania:
https://bibliotekanauki.pl/articles/10922.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Opis:
Sugar mill is one of the agro based industry and great significant in rural economy of developing countries. It creates environmental pollution by produced waste during sugar production. In the present work deals with the analysis of various change of biochemical in African marigold (Tagetes erecta L.) at 15 DAS under the different concentrations (control, 10, 25, 50, 75 and 100%) of sugar mill effluent. Results of this study determined that the lower concentration (10%) of sugar mill effluent increased photosynthetic pigment and biochemical contents of African marigold and it decreased at higher concentrations of the sugar mill effluent. The lower concentrations of sugar mill effluent used for irrigation.
Źródło:
International Letters of Natural Sciences; 2016, 50
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of salinity stress on growth and phenolics of rice (Oryza sativa L.)
Autorzy:
Minh, L.T.
Khang, D.T.
Ha, P.T.T.
Tuyen, P.T.
Minh, T.N.
Quan, N.V.
Xuan, T.D.
Powiązania:
https://bibliotekanauki.pl/articles/11459.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Opis:
This study was conducted to determine the correlation between of salinity stress on growth and phenolic compounds in rice. It was observed that salinity stress caused a significant decrease in shoot lengths, fresh and dry weights of all rice varieties. Under salinity stress, changes of chemical contents also differed among phenolic compounds and rice cultivars. Total phenolics and flavonoids, and contents of vanillin and protocatechuic acid in tolerant varieties were strongly increased, whereas in contrast, they were markedly reduced in the susceptible cultivar. Ferulic acid and p-coumaric acid were detected only in tolerance rice. Vanillin and protocatechuic acid may play a role, but ferulic acid and p-coumaric acid may be much involved in the tolerant mechanism against salinity stress. Ferulic acid and p-coumaric acid and their derivatives are potent to be exploited as promising agents to reduce detrimental effects of salinity stress on rice production.
Źródło:
International Letters of Natural Sciences; 2016, 57
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coupled wave-equation and eddy-current model for modelling and measuring propagating stress-waves
Autorzy:
Peussa, T.
Belahcen, A.
Powiązania:
https://bibliotekanauki.pl/articles/140923.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
coupled model
eddy currents
finite element method
magnetostriction
stress wave
Opis:
The coupling of the propagating stress wave with the eddy current model is presented. The applied stress produces magnetization in the sample that can be measured outside the sample by measuring the resulting magnetic flux density. The stress and flux density measurements are made on a mechanically excited steel bar. The problem is modelled with the finite element method for both the propagating wave and the eddy current. Three aspects are considered: eddy current model using magnetization from the measurements, coupled wave and eddy current models, and coupled different dimensions in the wave model. The measured stress can be reproduced from the measured flux density by modelling. The coupled models work both for stress and flux couplings as well as for the different dimensionality couplings.
Źródło:
Archives of Electrical Engineering; 2015, 64, 2; 215-226
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A numerical analysis of selected elastic-plastic fracture parameters for DEN(T) plates under plane strain conditions
Autorzy:
Graba, M.
Powiązania:
https://bibliotekanauki.pl/articles/264508.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
fracture mechanics
Q-stress
maximum stress
J-integral
CTOD
load-line displacement
limit loads
DEN(T)
mechanika pękania
maksymalne naprężenie
obciążenie
Opis:
This paper provides a numerical analysis of selected parameters of fracture mechanics for double-edge notched specimens in tension, DEN(T), under plane strain conditions. The analysis was performed using the elastic-plastic material model. The study involved determining the stress distribution near the crack tip for both small and large deformations. The limit load solution was verified. The J-integral, the crack tip opening displacement, and the load line displacement were determined using the numerical method to propose the new hybrid solutions for calculating these parameters. The investigations also aimed to identify the influence of the plate geometry and the material characteristics on the parameters under consideration. This paper is a continuation of the author’s previous studies and simulations in the field of elastic-plastic fracture mechanics.
Źródło:
International Journal of Applied Mechanics and Engineering; 2017, 22, 1; 49-80
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical study of the influence of shape imperfections on residual stress fields in a rivet hole
Autorzy:
Sławiński, G.
Niezgoda, T.
Szymczyk, E.
Jachimowicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/246398.pdf
Data publikacji:
2010
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
FEM
riveted joints
imperfections
residual stress
Opis:
The paper deals with the numerical analysis on residua! stress and strain fields in a rivet hole. This stage of study concerns improving of the fatigue performance of riveted joints in an airframe. Riveting, particularly in aviation, is a traditional but still commonly used method of joining sheet metal components. Aircraft structures are thin-walled ones, with coverings made of thin sheets stiffened by stringers, frames or ribs. Sheets are typically assembled by a multiple rivet or bolt joints. Rivets and bolts are also used to joint sheets and stiffeners. Therefore, fatigue resistance of the aircraft structure depends on tens of thousands or even hundreds of thousands r ivet joints, which are used to build it. The local numerical models of the joint are considered with regard to the aim introduced in the paper. Numerical FE simulations of an upsetting process are carried out using the LS-DYNA code. Three-dimensional numerical models are used to determine the resulting stress and strain fields at the mushroom rivet and around the hole. This type of problem requires the use of contact between the elements assembled and non-linear geometrie and elasto-plastic multilinear materiał models to simulate the behaviour of the rivet and sheets. The influence of shape imperfection on strain and stress states is studied.
Źródło:
Journal of KONES; 2010, 17, 2; 427-434
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Proteome responses to herbicidal stress in maize
Autorzy:
Tyczewska, A.
Bielinska, I.
Gracz, J.
Sikora, M.
Twardowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/951291.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
abiotic stress
plant response
maize
proteomic analysis
gene expression
two dimensional gel electrophoresis
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2015, 96, 1
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The response of hydroponically grown lettuce under Mn stress to differentiated application of silica sol
Autorzy:
Kleiber, T.
Krzesinski, W.
Przygocka-Cyna, K.
Spizewski, T.
Powiązania:
https://bibliotekanauki.pl/articles/15095.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie / Polskie Towarzystwo Magnezologiczne im. Prof. Juliana Aleksandrowicza
Tematy:
plant response
hydroponic cultivation
lettuce
Lactuca sativa
fertigation
foliar spray
macroelement
microelement
silicon
manganese
stress
Opis:
A way to alleviate excessive Mn nutrition of plants is through silicon application. The aim of the present study was to examine the effect of different Si concentrations in a nutrient solution and Si plant spraying treatments (in the form of silica sol) on the yielding and nutritional status of hydroponically grown lettuce under Mn-stress. The experiments were conducted under controlled conditions in a phytotron. The influence of the following Si levels in the nutrient solution (5.5 – control; 15.5; 23.25 and 31 mg Si dm-3) and foliar sprays (distilled water; Si solution) were investigated. Silicon supplied through fertigation significantly affected the plant’s nutrient status and alleviated the Mn stress, increasing fresh matter production, RWC (Relative Water Content) and the number of leaves per plants, while decreasing the share of dry matter. The Si nutrition did not change the content of Mn in the leaves, but caused a significant increase in N, P, Na, Fe and Si concentrations with a simultaneous decrease of Zn and Cu levels. The content of Ca, Mg and K was relatively stable (except for the treatment with the most intensive Si nutrition). Generally, the concentrations of N, P, K, Ca, Mg, Na and Fe within the tested Si range were higher than in the control, while being lower in the case of Zn and Cu. Overall, the foliar application of Si did not change plant yielding, the number of leaves on plants and most macro- and microelement concentration in leaves, but modified significantly the RWC as well as the Cu and Na content. The dry matter content under Si nutrition was varied. In summary, an effective method to alleviate Mn-stress is to apply silica sol to a nutrient solution used for plant fertigation.
Źródło:
Journal of Elementology; 2015, 20, 3
1644-2296
Pojawia się w:
Journal of Elementology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Changes in DNA methylation in maize under herbicide stress conditions
Autorzy:
Tyczewska, A.
Gracz, J.
Szymkowiak, J.
Twardowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/951318.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
DNA methylation
chromatin modification
gene silencing
gene transcription
maize
herbicide stress
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2015, 96, 1
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The relation of actual to potential evapotranspiration as an indicator of plant water stress for meadow plant cover
Autorzy:
Baranowski, P.
Mazurek, W.
Walczak, R.T.
Powiązania:
https://bibliotekanauki.pl/articles/1402606.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
root system
temperature measurement
soil water
thermography
meadow
crop water stress
evapotranspiration
plant cover
Penman-Monteith method
water stress
plant
Źródło:
Acta Agrophysica; 2001, 53
1234-4125
Pojawia się w:
Acta Agrophysica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oxidative stress development in the leaves of Amaranthus cruentus L. containing amaranthine under conditions of nighttime low temperatures, soil hypoxia and the combined effects of both stress factors
Autorzy:
Balakhnina, T.
Gins, M.
Fomina, I.
Powiązania:
https://bibliotekanauki.pl/articles/2082639.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
Amaranthus cruentus L.
night hypothermia
oxidative stress
peroxide processes
soil flooding
Opis:
The investigation of the effect of night chilling up to 4±2oC, soil flooding at the optimal day and night temperature, and the combined effect of these stress factors on the adaptive potential of Amaranthus cruentus L. cv “Krepysh” containing amaranthine showed that changes in the intensity of the peroxide oxidation of lipids and superoxide dismutase activity, varied in antiphase to each other, both in the control and in experimental plants. Due to night chilling, unlike hypoxia, the content of amaranthine decreased shaply at the beginning of the stress period and then increased and significantly exceeded the control level until the end of the experiment. It has been suggested that lowering the temperature induces amaranthine synthesis, whereas with the development of hypoxic stress due to the reactions of reactive oxygen species neutralization, constitutive amaranthine is used. The suppression of plant growth during periods of hypothermia was more pronounced than it was due to soil hypoxia, this phenomenon may be associated with a decrease in the overall level of metabolism under conditions of hypothermia and is another example of the adaptive reactions of plants. It was found that the negative effects of the combined activity of soil hypothermia and soil hypoxia on plants, were greater than the negative effects of each stressor applied separately.
Źródło:
International Agrophysics; 2019, 33, 4; 511-516
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Predicting Specific Stress of Cotton Staple Ring Spun Yarns: Experimental and Theoretical Results
Przewidywanie naprężeń przędzy bawełnianej z włókien ciętych: porównanie wyników eksperymentalnych z teoretycznymi
Autorzy:
Zubair, M.
Neckář, T. B.
Malik, Z. A.
Powiązania:
https://bibliotekanauki.pl/articles/233840.pdf
Data publikacji:
2017
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
fiber stress utilisation
yarn specific stress
fiber specific stress
carded and combed cotton yarns
przędza bawełniana
włókno zgrzebne
włókno czesane
krzywa naprężenia włókna
Opis:
The aim of this research is to predict the yarn specific stress from fiber specific stress and fiber stress utilisation. In this paper a new approach is introduced to predict the specific stress-strain curves of cotton carded and combed yarns. The force on single fiberis worked out and these fiber forces are combined together to obtain forces acting on yarn. The theoretical model introduces the utilisation of fiber stress on the basis of the fiber specific stress-strain curve, twist angle, fiber directional distribution parameter C and contraction ratio. A comparison of experimental results suggests that the specific stress-strain curves predicted have reasonable agreement with the experimental yarn specific stress-strain curves for all types of yarns. Thus this model is valid to predict the specific stress-strain curves for carded and combed cotton ring spun yarns.
W pracy przedstawiono sposób przewidywania krzywych naprężeń przędzy bawełnianej. Siły oddziaływujące na pojedyncze włókna pozwalają określić siły działające na przędzę. Model teoretyczny opiera się na krzywej naprężenia włókna, kącie skrętu, współczynnikach podziału kierunkowego włókna i kontrakcji. Porównanie wyników eksperymentalnych wskazuje, że przewidywane specyficzne krzywe naprężenia dobrze korelują z danymi eksperymentalnymi dla wszystkich typów przędzy. Przedstawiony model może być stosowany w przewidywaniu krzywych naprężeń dla przędz bawełnianych.
Źródło:
Fibres & Textiles in Eastern Europe; 2017, 2 (122); 43-47
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Biomechanical Loads and Subjective Stress Exposure to Lumber Graders in Sawmill Industry
Autorzy:
Jones, T.
Kumar, S.
Powiązania:
https://bibliotekanauki.pl/articles/90791.pdf
Data publikacji:
2011
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
job analysis
lumber graders
wood product manufacturing
repetitive strain
upper extremity
physical and psychophysical stress
Opis:
The aim of this study was to determine biomechanical loads and subjective stresses on lumber graders and associated morbidity in a high risk and repetitive sawmill occupation. The exposures of all 29 male sawmill worker volunteers were recorded. Motion and posture were studied with electrogoniometers, muscle loads were recorded with surface electromyography, and psychophysical stresses were assessed with subjective responses. Fifty-nine percent of the participants reported greater than moderate discomfort in their taskdominant upper extremity. Job performance required an average range of motion of 44º, 21º, and 52º in flexion/extension, radial/ulnar deviations, and pronation/supination respectively. It also required an average of 9% maximum voluntary contraction force and was repeated an average of 34 times/min. This repetitive exertion over an 8-h shift was deemed to be a significant risk factor associated with prevalent upper extremity morbidity.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2011, 17, 1; 87-97
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Influence of the Geometrical Parameters for Stress Distribution in Wire Raceway Slewing Bearing
Autorzy:
Gunia, D.
Smolnicki, T.
Powiązania:
https://bibliotekanauki.pl/articles/139896.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
wire race bearing
Hertz stress
slewing bearing
łożysko drutowe
naciski Hertza
łożysko ślizgowe
Opis:
This paper presents the current study of the distribution of stresses for fourpoint contact wire race ball bearing. The main aim of this article is to define the most important geometrical rules in a wire-race bearing. The results for bearings of different geometrical parameters are presented. In the study, one also estimates the distribution of internal pressure in particular bearing elements.
Źródło:
Archive of Mechanical Engineering; 2017, LXIV, 3; 315-326
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of cyclic hardening on stress relaxation in SUS316HTP under creep-fatigue loading at 700ºC: experiments and simulations nobutada
Autorzy:
Ohno, N.
Sasaki, T.
Shimada, T.
Tokuda, K.
Yoshida, K.
Okumura, D.
Powiązania:
https://bibliotekanauki.pl/articles/949134.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
creep-fatigue loading
cyclic hardening
stress relaxation
SUS316
constitutive model
Opis:
Cyclic hardening and stress relaxation experiments of SUS316HTP were performed under creep-fatigue loading with tensile strain holding at 700ºC. Experiments revealed that under strain holding, the slow stress-relaxation stage satisfying Norton’s law with slight cyclic hardening followed a rapid stress-relaxation stage that was noticeably affected by cyclic hardening. This suggests that in the slow stress-relaxation stage, inelastic deformation mechanisms different from that of viscoplasticity occurred. Experiments were simulated using a cyclic viscoplastic-creep model in which the inelastic strain-rate was decomposed into viscoplastic and creep components that were affected differently by cyclic hardening. The simulation accurately reproduced the experiments.
Źródło:
Journal of Theoretical and Applied Mechanics; 2018, 56, 2; 497-510
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reakcja roślin ziemniaka napromieniowanych mikrofalami na symulowany stres suszy
Reaction of potato plants irradiated with microwaves to simulated drought stress
Autorzy:
Jakubowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/287054.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Inżynierii Rolniczej
Tematy:
ziemniak
stres wodny
promieniowanie mikrofalowe
plonowanie
potato
water stress
microwave radiation
cropping
Opis:
W pracy przedstawiono wyniki trzyletniego doświadczenia dotyczącego reakcji roślin ziemniaka bardzo wczesnej odmiany Felka Bona, których sadzeniaki napromieniowano mikrofalami, na symulowany stres wodny w warunkach tunelu foliowego. Wyniki badań wskazują, że promieniowanie mikrofalowe istotnie modyfikuje strukturę plonu roślin ziemniaka w warunkach stresu suszy.
The paper presents results of a three-year experiment on the reaction of potato plants belonging to a very early variety - Felka Bona, to simulated water stress in foil tunnel conditions. Seed potatoes of the plants were irradiated with microwaves. Research results indicate that microwave radiation substantially modifies the structure of potato plant crop in drought stress conditions.
Źródło:
Inżynieria Rolnicza; 2009, R. 13, nr 8, 8; 15-21
1429-7264
Pojawia się w:
Inżynieria Rolnicza
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Correlation among agro-morphological variation and genetic diversity of rice (Oryza sativa L.) under drought stress
Autorzy:
Thu Ha, P.T.
Khang, D.T.
Tuyen, P.T.
Minh, L.T.
Minh, T.N.
Thi Lang, N.
Buu, B.C.
Xuan, T.D.
Powiązania:
https://bibliotekanauki.pl/articles/11160.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Opis:
In this study, the correlation coefficients among agro-morphological variation, genetic diversity, and drought tolerance in 44 rice cultivars were analyzed. The drought tolerance at seeding stage (DTS) was significantly proportional to drought tolerance at vegetative stage (DTV) (r = 0.60). In addition, DTS and DTV had strong significant positive correlation to leaf roll (r = 0.87 and 0.54, respectively). Means of unfilled grains and tilling per panicle were proportionally correlated to DTS (r = 0.22 and 0.25, respectively), and DTV (r = 0.20 and 0.36, respectively). However, weight of 1000 grains and filled grains were recorded no correlation to DTS and DTV. At a homologous coefficient of 16.85 integrated from cluster analysis of agro-morphological, quantitative characteristics and drought tolerant scores, the rice cultivars were divided into five groups. Maximum polymorphic information content (PIC) values were detected in three markers including RM11125, RM21, and RM5629, which were from 0.78 to 0.79. Cluster analysis of microsatellite markers revealed that by a genetic distance of 0.63, the rice varieties were separated into three clusters. The results provide valuable information for rice breeders to select donors in breeding rice integrated with drought tolerance and good agronomic characteristics.
Źródło:
International Letters of Natural Sciences; 2016, 58
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Influence of Geometry of the Specimen and Material Properties on the Q-Stress Value Near the Crack Tip for SEN(T) Specimen
Autorzy:
Graba, M.
Powiązania:
https://bibliotekanauki.pl/articles/387300.pdf
Data publikacji:
2011
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
właściwości materiałów
obciążenie
geometria
material properties
stress
geometry
Opis:
In the paper the short theoretical backgrounds about elastic-plastic fracture mechanics were presented and the O’Dowd-Shih theory was discussed. Using ADINA System program, the values of the Q-stress determined for various elastic-plastic materials for SEN(T) specimen – single edge notched plates in tension – were presented. The influence of kind of the specimen, crack length and material properties (work-hardening exponent and yield stress) on the Q-parameter were tested. The numerical results were approximated by the closed form formulas. Presented in the paper results are complementary of the two papers published in 2007 (Graba, 2007) and in 2010 (Graba, 2010), which show and describe influence of the material properties and crack length for the Q-stress value for SEN(B) and CC(T) specimens respectively. Presented and mentioned papers show such catalogue of the Q-stress value, which may be used in engineering analysis for calculation of the real fracture toughness.
Źródło:
Acta Mechanica et Automatica; 2011, 5, 2; 27-34
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Acoustic Emission Method to Determine Critical Stress in Fibre Reinforced Mortar Beams
Autorzy:
Ranachowski, Z.
Jóźwiak-Niedźwiedzka, D.
Brandt, A. M.
Dębowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/176697.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
critical stress
acoustic emission
microcracking
self-healing
concrete microstructure
fly ash
Opis:
The objective of this investigation was to test the effectiveness of the Acoustic Emission (AE) mea- surements in determining the critical stresses during four-point bending of mortar beams. Within the measuring procedure the parameter σcr/σ300 was calculated and analysed. Additionally, the influence of cement replacement by high calcium fly ash (HCFA) on the process of crack healing was discussed. Mortar beams with different content of HCFA and reinforced by steel microfibres were prepared for tests. After curing in standard conditions the beams were subjected to four-point bending test in order to introduce the pre-cracking. Thereafter the beams were cured in the lime water and loaded after 56 and 112 days in the same way as for the first time. Additionally the microstructure of mortars was studied in a stereo optical microscope as well in an electron scanning microscope including the Energy Dispersive X-ray analysis (EDX). The results of microstructural characterization of mortar containing HCFA from lignite combustion are presented. The applied load level slightly exceeded the critical stress, producing intense crack growth processes however did not significant affected the load capacity of the beams. During the consecutive loading the decreasing tendency of σcr/σ300 ratio was noted. The obtained results confirm that the latter parameter can be applied as a measure of the composite degradation level for the elements carrying the repeated loads of amplitude close to the critical stress of the structure and also that the cement replacement with HCFA influences the process of crack healing.
Źródło:
Archives of Acoustics; 2012, 37, 3; 261-268
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A preliminary study of estimating a mental workload with web-browsing using stress biomarkers
Autorzy:
Nomura, S.
Fujita, M.
Sakamoto, T.
Powiązania:
https://bibliotekanauki.pl/articles/332981.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Śląski. Wydział Informatyki i Nauki o Materiałach. Instytut Informatyki. Zakład Systemów Komputerowych
Tematy:
stress
web browsing
immunoglobulin A
cortisol
psychophysiology
stres
przeglądanie stron WWW
immunoglobuliny A
kortyzol
psychofizjologia
Opis:
The Recent rapid growth of the information technology aid people to improve the performance in processing their job activities. These changes, in turn, force them to carry out their job activities using computers in the workplace; that results in the increase of somatic and/or mental stresses. In this study, we conducted a preliminary experiment to estimate an impact of web-browsing on human mind and body. Two types of web-browsing tasks, which are a 18-minuetes of continuous web-browsing and an intermittent web-browsing (first 45 second of each 1-minutes interval), were given to the subjects (10 healthy male aged from 20-23) with within-subjects experimental design. With regard to physiological measures, two prominent stress biomarkers, salivary immunoglobulin A (IgA) and cortisol, were employed. Comparing among the task conditions, relatively larger and long-lasting increase of IgA and smaller decrease of cortisol was observed with an intermittent web-browsing despite there was no difference in the psychological state. These results illustrate the difficulty of estimating the mental workload caused by web-browsing and the importance of employing physiological indices.
Źródło:
Journal of Medical Informatics & Technologies; 2015, 24; 53-58
1642-6037
Pojawia się w:
Journal of Medical Informatics & Technologies
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of stress state in coal seam based on inverse problem solution using acoustic sounding data
Autorzy:
Kudaibergenov, Mels K.
Iskakov, Kazizat T.
Kudaibergenova, Bakytzhan S.
Powiązania:
https://bibliotekanauki.pl/articles/88885.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Wydział Geoinżynierii, Górnictwa i Geologii. Instytut Górnictwa
Tematy:
coal seam
stress
elasticity theory
biharmonic equation
inverse problem
Opis:
The paper presents an algorithm for calculating the horizontal, vertical and tangential stresses in a horizontal coal seam lying between galleries. These stresses are expressed in terms of the Airy function, which satisfies a homogeneous biharmonic equation. For its numerical solution it is necessary to set boundary conditions. Practical limitations do not allow us to determine the tangential stresses on horizontal boundaries of the coal seam. Calculations of stresses are proposed to be carried out in two steps. The first step is to solve the inverse problem for the biharmonic equation to find unknown tangential stresses on horizontal boundaries of the coal seam. The inverse problem is solved by minimizing the residual functional. Its strong convexity is proved, which implies the existence and uniqueness of the solution of the inverse problem. The second step is to solve the boundary value problem for the biharmonic equation to calculate stresses in the coal seam. The result of a numerical experiment is presented.
Źródło:
Mining Science; 2019, 26; 173-187
2300-9586
2353-5423
Pojawia się w:
Mining Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stress concentration on the contour of a plate opening: analytical, numerical and experimental approach
Autorzy:
Momcilovic, N.
Motok, M.
Maneski, T
Powiązania:
https://bibliotekanauki.pl/articles/279564.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
stress concentration factor (SCF)
digital image correlation (DIC)
plate opening
small radius of curvature
Opis:
The objective of the paper is to analyze the stress concentration factor (SCF) in the corner of a rectangular plate opening with small radii of curvature and various methods for its derivation. Besides the finite element method, as the most used approach today, there are some analytical and experimental procedures that can obtain stress concentration results in such spots. An analytical approach can deliver prediction of the SCF around the corner but cannot illustrate the stress field opposite to the finite element method. On the other hand, finite element analysis needs much computation time to deal with very sensitive and fine mesh generation around concentration zones. Experimental devices, such as strain gauges are not able to perform measurements on areas where high gradient of stress occurs due to their lack of sensitiveness and larger dimensions compared to the measured part of a structure. The paper presents Digital Image Correlation (DIC) technique that obtains not only stress concentration, where other devices fail, but also provides full displacement, strain and stress field’s even where a high gradient of stress exists. These three methods are discussed, compared and illustrated on the model of a plate with rectangular opening subjected to tension.
Źródło:
Journal of Theoretical and Applied Mechanics; 2013, 51, 4; 1003-1012
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Carbonylation-targeted proteomics of NaCl-stressed plants revealing early oxidative events in various cellular compartments
Autorzy:
Mano, J.
Nagata, M.
Okamura, S.
Shiraya, T.
Mitsui, T.
Powiązania:
https://bibliotekanauki.pl/articles/80594.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
conference
lipid peroxide
reactive carbonyl species
reactive oxygen species
plant environment
stress response
Arabidopsis thaliana
4-hydroxynonenal
immunoblotting
sodium chloride stress
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2013, 94, 2
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zmniejszenie stresu wśród pracowników obiektu gastronomicznego poprzez uprawianie aktywności fizycznej
Reducing stress among employees of a gastronomic industry through physical activity
Autorzy:
Wodecki, T.
Babicz, W.
Powiązania:
https://bibliotekanauki.pl/articles/109087.pdf
Data publikacji:
2017
Wydawca:
Stowarzyszenie Menedżerów Jakości i Produkcji
Tematy:
aktywność fizyczna
gastronomia
redukcja stresu
physical activity
gastronomy
stress reduction
Opis:
W artykule wykorzystano wyniki badań zrealizowanych na grupie osób pracujących w obiekcie gastronomicznym, które dotyczyły redukcji stresu poprzez uprawianie wybranej aktywności fizycznej. Na podstawie otrzymanych wyników wyciągnięte zostały odpowiednie wnioski, które mają pomóc pracownikom w radzeniu sobie ze zjawiskiem stresu w pracy.
In the article were used the results of research carried out on the group of people working in a gastronomic facility, which focused on reducting stress by practicing selected physical activity. Based on these results have drawn the appropriate conclusions, to help workers cope with the phenomenon of stress at work.
Źródło:
Archiwum Wiedzy Inżynierskiej; 2017, 2, 1; 3-5
2544-2449
Pojawia się w:
Archiwum Wiedzy Inżynierskiej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of urban pollution on 4-coumarate: CoA ligase and flavonoid accumulation in Berberis thunbergii
Autorzy:
Pietrowska-Borek, M.
Chadzinikolau, T.
Kozlowska, M.
Powiązania:
https://bibliotekanauki.pl/articles/41035.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Tematy:
urban pollution
4-coumarate-CoA ligase
flavonoids
accumulation
Berberis thunbergii
anthocyanin
environmental stress
plant stress
Opis:
Flavonoids are polyphenolic compounds commonly found in plants and they play an important role in stress tolerance. They have the capacity to chelate heavy metals andscavenge free radicals. Urban pollution causes oxidative stress in plants and flavonoids may protect cells against the negative effect of free radicals. In this study levels of anthocyanins andflavonols and4-coumarate:CoA ligase (4CL) activity were determinedin Berberis thunbergii (DC.) plants grown in pollutedandresid ential areas in the city of Poznań. The results showedsignificantly higher accumulation of anthocyanins andstimulation of 4CL activity in plants from the contaminatedsites in comparison to the control plants. Probably the activation of the phenylpropanoidpathway was a response to stress caused by urban pollution.
Źródło:
Dendrobiology; 2010, 64
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Thermal Stress Treadmill Walk for Clinic Evaluation of Candidates for Hazardous Materials (HazMat) Duty
Autorzy:
Raymond, L. W.
Barringer, T. A.
Powiązania:
https://bibliotekanauki.pl/articles/90850.pdf
Data publikacji:
2014
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
heat stress
hazardous materials
medical evaluation
fitness for duty
electrocardiography
stres cieplny
materiały niebezpieczne
elektrokardiografia
Opis:
U.S. guidance for examining hazmat workers recommends stress testing be considered when heat stress is expected. However, the most common stress test—Bruce protocol treadmill electrocardiography (BPTE) wearing gym clothes—creates little thermal stress. Objective. Evaluate a novel thermal stress treadmill walk (TSTW). Methods. Body temperatures and heart rates during BPTE in 93 current and potential hazmat workers wearing gym clothes were compared with later values in 35 of these subjects while they were wearing thermally-restrictive “sauna suits” during a 45-min TSTW. Physiological strain index (PSI) was calculated from temperature and heart rate changes and compared with PSI values from hazmat simulations and climatic chamber exercises. Results. Tympanic temperature (TT) rose 0.5 °C (SD 0.5) during BPTE lasting 12.4 min (SD 2.9). PSI reached 6.0 (SD 1.3). TT rose 1.0 °C (SD 0.5) during TSTW, p < .01. PSI averaged 6.6 (SD 1.9) in 29 subjects who completed TSTW, versus 5.7 (SD 5.7) in the 6 subjects who did not. Ingested thermistor temperatures increased more than did TT during TSTW, yielding PSI of 7.0 (SD 1.5), equal to PSI values from climatic chamber exercises, i.e., 7.0 (SD 1.0). Conclusion. TSTW increased body temperature and PSI in 29 of the 35 subjects who completed it to levels matching those of operational simulations in climatic chambers and during hazmat exercises. This TSTW may be useful for evaluating candidates for hazmat duty.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2014, 20, 2; 281-293
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of selected parameters of photosynthesis as herbicide stress indicators on the example of glyphosate
Autorzy:
Wysocki, K.
Banaszkiewicz, T.
Olszewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/65181.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
physiological parameter
photosynthesis
herbicide
ornamental plant
Mexican marigold
Tagetes erecta
plant stress
glyphosate
sublethal dose
Opis:
This study was aimed at evaluating the effect of sublethal doses of glyphosate on physiological parameters of a common ornamental plant Mexican marigold (Tagetes erecta). The herbicide was applied in the following doses: 720 g ⋅ ha–1 (standard field dose), 144 g ⋅ ha–1, 28.8 g ⋅ ha–1, and 14.4 g ⋅ ha–1, in the form of a spraying treatment of plants in a specialist spraying chamber. The net assimilation rate and leaf greenness index were then determined. Herbicide application in the sublethal doses, i.e. below 720 g ⋅ ha–1, caused disorders in both analyzed physiological parameters of plants. The glyphosate dose of 144 g ⋅ ha–1 elicited transient disorders in the leaf greenness index. In turn, the use of the lower doses (28.8 g ⋅ ha–1 and 14.4 g ⋅ ha–1) caused a short-term increase in the net photosynthesis rate in the plants which was accompanied by a decreased value of the leaf greenness index. Study results demonstrated the effect of sublethal doses of glyphosate as a stress factor in parameters associated with the process of photosynthesis in plants.
Źródło:
Journal of Plant Protection Research; 2018, 58, 3
1427-4345
Pojawia się w:
Journal of Plant Protection Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of biostimulants on chlorophyll fluorescence parameters of broccoli (Brassica oleracea var. italica) under drought stress and rewatering
Autorzy:
Kałużewicz, A.
Bączek-Kwinta
Krzesiński, W.
Spiżewski, T.
Zaworska, A.
Powiązania:
https://bibliotekanauki.pl/articles/11879855.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Przyrodniczy w Lublinie. Wydawnictwo Uniwersytetu Przyrodniczego w Lublinie
Tematy:
plant cultivation
broccoli
Brassica oleracea
chlorophyll fluorescence
biostimulant
drought stress
Opis:
The aim of the research was to determine the influence of biostimulants amino acids and amino acids + Ascophyllum nodosum filtrate on two broccoli cultivars ‘Agassi’ and ‘Tiburon’ and their response to soil drought. The plants were watered with Ascophyllum nodosum filtrate before planting and sprayed with amino acids after planting three times. Chlorophyll fluorescence measurements were performed before, during and after stress. They showed a considerable difference in cultivars’ response to stress, with ‘Agassi’ being more sensitive. Application of biostimulants enhanced the tolerance to drought stress. Maximum photochemical efficiency of PSII was unchanged, whereas the quantum yield of electron transport and photochemical fluorescence quenching values increased and the non-photochemical fluorescence quenching decreased. Moreover, the apparent photosynthetic electron transport rate rose. Chlorophyll content index was affected by the cultivar and application of biostimulants.
Źródło:
Acta Scientiarum Polonorum. Hortorum Cultus; 2018, 17, 1; 97-106
1644-0692
Pojawia się w:
Acta Scientiarum Polonorum. Hortorum Cultus
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Novel Modeling of the Work-Hardening Curve
Autorzy:
Pluta, P.
Hryniewicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/411581.pdf
Data publikacji:
2013
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Hardening curve
yield stress
Relative deformation
Relative deformation constant;
Absolute strain constant
Stress potential fields
Strain potential fields
Yield force
Plastic rigidity
Plastic energy
Yield work
Opis:
The paper aims at a critical analysis of the existent description of plastic strengthening/ work-hardening curve. The adequate description of the curve, having a physical sense, has been proposed. The description begins from the very source which is the primary, general differential equation. That source was used to formulate the characteristics of the studied system. Then the analytical solution of the dependence between the yield stress and the relative deformation is provided. The description of the work-hardening curve has been developed to further form a proper dependence of the yield force on the absolute yield strain. Other functional characteristics, namely the coefficient of the plastic rigidity, yield work, and the plastic potentials, have also been formed.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2013, 4; 73-90
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Redox-mediated regulation of wheat seed dormancy revealed through modification-specific proteomics
Autorzy:
Bykova, N.
Hoehn, B.
Rampitsch, C.
Hu, J.
Fan, T.
Powiązania:
https://bibliotekanauki.pl/articles/80787.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
conference
seed dormancy
wheat
Triticum aestivum
reactive oxygen species
hormonal balance
cysteine
proteomics
abiotic stress
biotic stress
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2013, 94, 2
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analytical determination of the order of stress field singularity in some configurations of multiwedge systems for the case of antiplane deformation
Autorzy:
Makhorkin, M.
Makhorkina, T.
Powiązania:
https://bibliotekanauki.pl/articles/411440.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Oddział w Lublinie PAN
Tematy:
multi-wedge system
antiplane deformation
order of the stress singularities
analytical solutions
composite wedge
Opis:
In this paper, the possibility of constructing the analytical expressions to determine the order of the stress singularities in multi-wedge composites of the most prevalent geometric configurations for the case of antiplane deformation is considered. Particularly, the analytical solutions of the corresponding characteristic equations are constructed for three-wedge systems whose components have such geometric characteristics [wzór] is а half-plane and attached to it wedges with the such apical angles: (in the presence and absence of a slit) [wzór] is а half-plane and attached to it wedges with such apical angles [wzór] (in the presence and absence of the slit with outlet angle to the linear materials interface) [wzór] is а half-plane and attached to it wedges with such apical angles [wzór]. The analytical solutions of characteristic equations for composite wedges composed of [wzór] elements with identical apical angles are constructed as well. Additional studies, the results of which have not been included in the materials of the article due to their inconvenience, indicate to that there are analytical solutions of the characteristic equation for a composite of this type with more elements. The obtained results make it possible to study the stress-strain state in multi-wedge systems of the considered configurations not restricting ourselves only to the vicinity of the wedges convergence point. In addition, the use of analytical solutions of characteristic equations in systems with a large number of wedges having the same apical angles gives the additional possibilities for analysis the angularly functionally graded materials.
Źródło:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes; 2017, 6, 3; 45-51
2084-5715
Pojawia się w:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-50 z 253

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