Search results for "TRES"
showing 10 items of 6927 documents
Detección de estrés hídrico en olivar mediante datos hiperespectrales y térmicos del sensor AHS
2005
En: XI Congreso Nacional de Teledetección, Teledetección, Avances en la Observación de la Tierra, M. Arbelo, A. González, J.C. Pérez (Eds.), pág.: 53-56, Tenerife, 21-23/9/2005.
Fatigue fracture plane under Multiaxial Random Loadings - prediction by variance of equivalent stress based on the maximum shear and normal stresses
1992
It is assumed that the plane in which the maximum variance of the equivalent stress appears is critical for a material and the fatigue fracture should be expected in this plane. The equivalent stress is calculated according to the fatigue criterion of maximum shear and normal stresses in the fracture plane. It was demonstrated that for each stationary random stress state there is one or more critical planes where the fatigue fracture plane can be expected. The variance method together with the discussed fatigue criterion give good results for three analysed types of carbon steels under multiaxial cyclic loadings.
Fracture Plane of Cruciform Specimen in Biaxial Low Cycle Fatigue—Estimate by Variance Method and Experimental Verification
1995
This paper presents the variance method of determining the fracture plane under random multiaxial stress states. The fracture plane was estimated analytically by the variance method with the three fatigue criteria. The estimated fracture planes were compared with experimental results using type SUS 304 and 1Cr-1Mo-1/4V steel cruciform specimens. The variance method with the maximum normal strain criterion, by neglecting the strain in direction in which no external forces act, could estimate the actual fracture planes of cruciform specimens in high temperature biaxial low cycle fatigue.
ESTIMATED AND EXPERIMENTAL FATIGUE LIVES OF 30CrNiMo8 STEEL UNDER IN-AND OUT-OF-PHASE COMBINED BENDING AND TORSION WITH VARIABLE AMPLITUDES
2007
Abstract— Calculated fatigue lives, based on three criteria for multiaxial random fatigue, were compared with lives obtained from tests on cylindrical specimens of 30CrNiMo8 steel subjected to in- and out-of-phase bending and torsion at variable amplitudes. In the chosen fatigue criteria the expected position of the fracture plane, determined from a variance method for the equivalent stress, were taken into account. The equivalent stress history was related to the rain flow method and fatigue damage was evaluated from the Palmgren–Miner hypothesis. It has been shown that the expected fatigue fracture planes agree with those determined by experiments. The most realistic estimations of fatigu…
Fatigue life estimation for 30CrNiMo8 steel under in- and out-of-phase combined bending and torsion with variable amplitudes
1996
Fatigue life successively calculated according to three criteria of multiaxial fatigue for randomly varying loading is compared with fatigue life obtained by Sanetra and Zenner in testing cylindrical specimens of 30CrNiMo8 steel by in- and out-of-phase bending and torsion with variable amplitudes. The position of the plane of fatigue fracture is determined using the variance method. The histories of equivalent stresses are schematically represented by the Monte Carlo method. Fatigue damage was computed using the Palmgren-Miner hypothesis. The most realistic estimates of fatigue life in the scatter band of the results with a factor of 3 are obtained on the basis of the criterion of maximum t…
Simulation investigations of the position of Fatigue Fracture Plane in materials with biaxial loads
1989
In the paper three methods of determination of the expected fatigue fracture plane position under random triaxial stress state have been presented. They are: weight function method, variance method and damage cumulation method. The weight function method for biaxial cyclic loadings has been analysed with digital simulation. The fatigue fracture plane position has been determined with mean values of the direction cosines of principal stress axes. Averaging has been done at angle values with use of weights. Eleven various weights have been presented and their usability has been analysed on the basis of experimental results obtained by Rotvel, and Nishihara-Kawamoto. The weights with good agre…
Oxidative stress in vascular disease: causes, defense mechanisms and potential therapies
2007
Endothelial cells control vascular homeostasis by generating paracrine factors that regulate vascular tone, inhibit platelet function, prevent adhesion of leukocytes, and limit proliferation of vascular smooth muscle. The dominant factor responsible for many of those effects is endothelium-derived nitric oxide (NO). Endothelial dysfunction characterized by enhanced inactivation or reduced synthesis of NO, alone or in combination, is seen in conjunction with risk factors for cardiovascular disease. Endothelial dysfunction can promote vasospasm, thrombosis, vascular inflammation, and proliferation of the intima. Vascular oxidative stress and increased production of reactive oxygen species con…
Organic Nitrate Therapy, Nitrate Tolerance, and Nitrate-Induced Endothelial Dysfunction: Emphasis on Redox Biology and Oxidative Stress
2015
Abstract Organic nitrates, such as nitroglycerin (GTN), isosorbide-5-mononitrate and isosorbide dinitrate, and pentaerithrityl tetranitrate (PETN), when given acutely, have potent vasodilator effects improving symptoms in patients with acute and chronic congestive heart failure, stable coronary artery disease, acute coronary syndromes, or arterial hypertension. The mechanisms underlying vasodilation include the release of •NO or a related compound in response to intracellular bioactivation (for GTN, the mitochondrial aldehyde dehydrogenase [ALDH-2]) and activation of the enzyme, soluble guanylyl cyclase. Increasing cyclic guanosine-3′,-5′-monophosphate (cGMP) levels lead to an activation of…
Pro-inflammatory effects of interleukin-17A on vascular smooth muscle cells involve NAD(P)H- oxidase derived reactive oxygen species.
2010
T cells are known for their contribution to the inflammatory element of atherosclerosis. Recently, it has been demonstrated that the Th17 derived cytokine IL-17 is involved in the pro-inflammatory response of vascular smooth muscle cells (VSMC). The aim of the present study was to examine whether reactive oxygen species (ROS) might be involved in this context. The effect of IL-17A on ROS generation was examined using the fluorescent dye 2′7′-dichlorodihydrofluorescein (H<sub>2</sub>DCF) in primary murine VSMC. IL-17A induced an increase in H<sub>2</sub>DCF fluorescence in VSMC, and this effect was blocked by the NAD(P)H-oxidase inhibitor apocynin and siRNA targeting …
Heparin–polynitroxide derivatives: a platform for new diagnostic and therapeutic agents in cardiovascular disease?
2013
Vascular wall extracellular oxidative stress Cardiovascular disease (CVD; mainly atherosclerosis, hypertension and diabetes mellitus) remains a major cause of death in western society [1]. Despite substantial progress achieved, the diagnosis of CVD often comes too late, when the disease has already advanced to therapeutically incurable stages. The development of efficient diagnostic probes allowing early non-invasive diagnostics, as well as drugs which can prevent or reverse CVD and/or its complications (e.g., myocardium infarctus and stroke) are highly desired tasks of the modern cardiovascular medicinal chemistry.