Search results for "ER stress"

A Study on the Effects of Clearance and Interference Fits in a Pin-Loaded Cross-Ply FGRP Laminate

1998

The elastic behavior of a cross-ply fiber glass-reinforced epoxy laminate loaded in tension through a pin fitted with clearance and interference is examined. A nonlinear contact analysis using the Finite Element Method and an experimental study by Speckle Interferometry are performed, showing fairly good correlation. An interesting comparison is performed between FEM results and Hertzian contact theory. Major conclusions are: (I) clearance causes high compressive stress in the bearing area, and does not influence the peak tensile stress; (2) interference has beneficial effects on the joint, as (a) it lowers the peak circumferential stress, and (b) it decreases the change of stress due to t…

Hot carrier effects in n-MOSFETs with SiO2/HfO2/HfSiO gate stack and TaN metal gate

2009

Charge trapping and trap generation in field-effect transistors with SiO2/HfO2/HfSiO gate stack and TaN metal gate electrode are investigated under uniform and non-uniform charge injection along the channel. Compared to constant voltage stress (CVS), hot carrier stress (HCS) exhibits more severe degradation in transconductance and subthreshold swing. By applying a detrapping bias, it is demonstrated that charge trapping induced degradation is reversible during CVS, while the damage is permanent for hot carrier injection case. © 2008 Elsevier B.V. All rights reserved.

Conservation tillage in a semiarid Mediterranean environment: results of 20 years of research

2014

Conservation tillage techniques are becoming increasingly popular worldwide as they have the potential to generate environmental, agronomic, and economic benefits. In Mediterranean areas, studies performed on the effects of conservation tillage [in comparison with the conventional tillage technique (CT)] on grain yield of cereal crops have reported contradictory results as well as considerable year-to-year variation, demonstrating how the impact of different soil tillage techniques on crop productivity is strongly site-specific. The present paper summarises the main results from a set of experiments carried out in Sicily during the last 20 years in which we compared no tillage (NT) to CT in…

Monitoring water stress in Mediterranean semi-natural vegetation with satellite and meteorological data

2014

In arid and semi-arid environments, the characterization of the inter-annual variations of the light use efficiency ε due to water stress still relies mostly on meteorological data. Thus the GPP estimation based on procedures exclusively driven by remote sensing data has not found yet a widespread use. In this work, the potential to characterize the water stress in semi-natural vegetation of three spectral indices (NDWI, SIWSI and NDI7) – from MODIS broad spectral bands – has been analyzed in comparison to a meteorological factor (Cws). The study comprises 70 sites (belonging to 7 different ecosystems) uniformly distributed over Tuscany, and three eddy covariance tower sites. An operational…

Daily GPP estimates in Mediterranean ecosystems by combining remote sensing and meteorological data

2015

The accurate representation of terrestrial CO2 uptake (GPP) using Monteith's approach requires a frequent and site-specific parameterization of the model inputs. In this work, an optimization of this approach has been carried out by adjusting the inputs (f(APAR), PAR and epsilon) for the study area, peninsular Spain, a typical Mediterranean region. The daily GPP images have been calculated for 2008 and 2011 with a 1-km spatial resolution and validated by comparison with in situ GPP estimates from the eddy covariance data (direct validation) and by inter-comparison with the MODIS GPP product. The direct validation has evidenced an excellent agreement with correlations up to 0.98 in 2008 and …

Assessing AQUACROP water stress function to evaluate the transpiration reductions of olive tree.

2012

Quantitative evaluation of the drought adaptation processes of crops is an important prerequisite for efficient irrigation management. Modeling the plant response under water stress conditions is crucial to identify the exact irrigation timing. Assessment of any water stress function requires the knowledge of its shape and then the estimation of critical thresholds of the soil water status, below which a strong reduction of plant transpiration occurs. In this work, the macroscopic approach is used to assess the water stress function implemented in AQUACROP for mature olive tree. In particular, after discussing about the function shape, the critical thresholds of soil water status are propos…

Modeling olive orchard response to water stress and definition of critical thresholds of soil water status.

2011

Shakedown optimal design of reinforced concrete structures by evolution strategies

2000

Approaches the shakedown optimal design of reinforced concrete (RC) structures, subjected to variable and repeated external quasi‐static actions which may generate the well‐known shakedown or adaptation phenomenon, when constraints are imposed on deflection and/or deformation parameters, in order to simulate the limited flexural ductility of the material, in the presence of combined axial stress and bending. Within this context, the classical shakedown optimal design problem is revisited, using a weak upper bound theorem on the effective plastic deformations. For this problem a new computational algorithm, termed evolution strategy, is herein presented. This algorithm, derived from analogy …

Left Ventricle Biomechanics of Low-Flow, Low-Gradient Aortic Stenosis: A Patient-Specific Computational Model

2022

This study aimed to create an imaging-derived patient-specific computational model of low-flow, low-gradient (LFLG) aortic stenosis (AS) to obtain biomechanics data about the left ventricle. LFLG AS is now a commonly recognized sub-type of aortic stenosis. There remains much controversy over its management, and investigation into ventricular biomechanics may elucidate pathophysiology and better identify patients for valve replacement. ECG-gated cardiac computed tomography images from a patient with LFLG AS were obtained to provide patient-specific geometry for the computational model. Surfaces of the left atrium, left ventricle (LV), and outflow track were segmented. A previously validated …

Forced Flowering in Mandarin Trees Under Phytotron Conditions

2019

[EN] Phytotron has been widely used to assess the effect of numerous parameters on the development of many species. However, less information is available on how to achieve fast profuse flowering in young fruit trees with this plant growth chamber. This study aimed to outline the design and performance of a fast clear methodology to force flowering in young mandarin trees (cv. Nova and cv. Clemenules) and to analyze the influence of induction intensity on inflorescence type. The combination of a short water stress period with simulated spring conditions (day 13 h, 22 °C, night 11 h, 12 °C) in the phytotron allowed flowers to be obtained only after 68-72 days from the time the experiment beg…