1,786 research outputs found
Non-proportional loading for 3-D stress situations in sequentially linear analysis
No full textThis article presents a new non-proportional loading strategy for Sequentially Linear Analysis (SLA), which is a robust secant stiffness based procedure for nonlinear finite element analysis of quasi-brittle materials, like concrete and masonry. The strategy is based on finding the principal planes for a total strain based fixed cracking model, by searching for the critical plane where the normal stresses due to the scaled combination of two non-proportional loads is equal to the allowable strength. For a plane stress situation (2D), the scaling factor λ is ex-pressed as a function of θ, the inclination of an arbitrary plane to the reference coordinate system, and a one dimensional (θ) optimization of λ is done to determine the principal plane and the resulting fixed crack coordinate system. This approach has been illustrated to match up to the closed form solution, obtained previously based on the principal stress theory, using single element tests and a quasi-static test pushover test on a masonry shear wall. Finally, the concept for the 3-D stress situation is presented, where the optimization problem becomes two-dimensional, with respect to l and m (two-directional cosines).Applied MechanicsStructural Design & Mechanic
Shear-sliding behavior of masonry: Numerical micro-modeling of triplet tests
No full textMasonry is a composite material, whose behavior is strongly influenced by the presence of vertical and horizontal mortar joints, weak elements along which the shear failure usually occurs. The scope of the present work was to investigate factors that could affect the shear-sliding behavior of masonry, by performing numerical simulations of triplet tests conducted on calcium silicate brick masonry specimens with two different bond patterns. In the numerical analyses, a simplified micro-modeling strategy was adopted. A composite interface model was used, including a tension cut-off, a Coulomb friction criterion and a compressive cap. The numerical models were validated through comparisons with results from experimental tests, in terms of failure load, post-peak behavior and specimen deformability. Moreover, factors that could influence the shear-sliding behavior of masonry were analyzed by performing parametric studies. The simplified-micro modeling confirmed to be a very efficient strategy to capture the nonlinear behavior of masonry.Structural Design & MechanicsApplied Mechanic
Avirulent geotrichum candidum for biological control of postharvest rots on fruit
No full textA novel avirulent strain of Geotrichum candidum has been isolated which is effective to inhibit growth of postharvest pathogens on fruit. In use, protection from postharvest fruit-rots may be afforded by application of an effective amount of the strain onto the surface of fruit.U
The contribution of stone tool residues in reconstructing Late Pleistocene hominin stone tool behaviour at Grotta di Fumane, Italy
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Coordination dependence of hyperfine interactions at impurities on fcc metal surfaces. I. Electric-field gradient
No full textWe present a comparison between accurate ab initio calculations and a high-quality experimental data set (1986-2002) of electric-field gradients of Cd at different sites on Ni, Cu, Pd, and Ag surfaces. Experiments found a systematic rule to assign surface sites on (100) and (111) surfaces based on the main component of the electric-field gradient, a rule that does not work for (110) surfaces. Our calculations show that this particular rule is a manifestation of a more general underlying systematic behavior. When looked upon from this point of view, (100), (111) and (110) surfaces behave in precisely the same way. The physical mechanism behind the systematics of the EFG for other 5sp impurities (Cd-Ba) at different fcc surfaces sites is revealed, showing in a natural way why the first half of the 5p elements shows a coordination dependence that is opposite with respect to the second half
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The Etiology and Control of Root and Stem Rots of Peas in Washington
No full textTopics include: Introduction; Nature and importance of root and stem rots of peas; Cause of root and stem rots of peas; Control experiments; Discussion; Summary; Literature cite
Reduction of gray mold development in table grapes by preharvest sprays with ethanol and calcium chloride.
No full textPreharvest applications of a 16% ethanol (EtOH) solution, containing 1 % of calcium chloride (CaCl2), reduced gray mold development in ‘Chasselas’ table grapes picked at a late harvest date, the losses due to rotten clusters dropped from 15% in controls to 5% in grapes treated with EtOH+CaCl2. Then over a 6-week cold storage, the losses due to gray mold rots were reduced by 50% when storing EtOH+CaCl2 treated clusters, compared to untreated controls. Preliminary experiments had shown that a 2% EtOH solution was already inducing significant drop of gray mold growth. A range of concentrations up to 50% ethanol had been tested in preliminary trials without observing damages to the vines and clusters. The treatments did not induce significant changes to the fruit quality assessed by sensory analyses on healthy berries
Rots – Échangeur du Hamel
No full textLe diagnostic réalisé à Rots, préalablement à la construction d’un échangeur routier, porte sur une surface de 2,1 ha qui se compose de deux grandes parcelles cultivées de part et d’autre d’une petite route. La parcelle au nord-ouest de la petite route a subi une surélévation de 2 m de remblais limoneux issus de la construction de la quatre voies Caen-Bayeux. Les terrains naturels, très en deçà du fond de forme de l’aménagement routier, ont empêché un diagnostic classique. Des tranchées ont é..
Postharvest application of the yeast Cryptococcus laurentii reduces apple rots.
No full textRots might be responsible for substantial post-harvest losses on apples (Malus domestica). The blue mold caused by Penicillium expansum, the bitter rot caused by Glomerella cingulata and the ?bull?s-eye rot? induced by Pezicula malicorticis are among the most common rots. Great attention has been given to less environmental damaging alternatives for the control of post-harvest diseases. The post-harvest application of yeasts, such as Cryptococcus laurentii, is one of the options to control fruit rots. This study was carried out to test the efficiency of C. laurentii on fruit rots control in ?Fuji? and ?Gala? apples. After application of treatments by immersion, the fruits were stored in laboratory (15-20°C and 60-70% RH) or in cold storage (1°C and 90-95% RH). The pathogens were applied at the concentration of 102 conidia mL-1, the yeast at 107 cells mL-1 and the fungicides at 150 mg l-1. An isolate (36) of C. laurentii was as efficient as the fungicides (thiabendazole and iprodione) to reduce apple fruit rots (G. cingulata, P. expansum, and P. malicorticis). In cold storage trials, C. laurentii was as efficient as the fungicides (thiabendazole, iprodione, chlorhexidine digluconate, sodium dichloro-s-triazinetrione, sodium dicloroisocyanurate and sodium hypochlorite) to reduce P. expansum fruit rot. The application of C. laurentii did not affect flesh firmness and total soluble solids content of the fruits
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