Failure regime in (1+1) dimensions in fibrous materials

In this paper, we introduce a model for fracture in fibrous materials that takes into account the rupture height of the fibers, in contrast with previous models. Thus, we obtain the profile of the fracture and calculate its roughness, defined as the variance around the mean height. We investigate the relationship between the fracture roughness and the fracture toughness.Comment: 4 pages, 4 figures.eps, Revte

Efeito do expurgo sobre a preservação do alho armazenado

Stored garlic (Allium sativum L.) is damaged by she insects Plodia interpunctella (Huber), Ephestia cautela (Walker), Ephestia alutella (Hubner) (Lepidoptera, Phycitidae), and Araecerus fasciculatus (De Geer) (Coleoptera, Anthribidae), and the mite Eriophyes tulipae (Keifer 1938) (Acariformes, Eriophyidae). Phosphin and methyl bromide fumigants were tested at four dosage levels and three applications for protection of stored garlic. One sample treated with 4% malathion powder after fumigation and one untreated sample were included as checks. Fumigation plus malathion application showed to be efficient to protect stored garlic from moths and mites. Phosphin was as efficient as methyl bromide for the control of both insects and mites. Damage was less in the malathion treated sample (34.9% damaged bulbils by moths and 45% by mites). Both fumigants were effective in protecting stored garlic. However, methyl bromide at the dosage level of 15 cm3/m3 decreased bulbing of garlic.O alho (Allium sativum L.) armazenado é praguejado pelos insetos Plodia interpunctella (Hubner), Ephestia cautella (Walker), Ephestia elutella (Hubner), (Lepidoptera, Phycitidae), Araecerus fasciculatus (De Geer) (Coleoptera, Anthribidae), e pelo ácaro Eriophyes tulipae (Keifer 1938) (Acariformes, Eriophyidae). Testou-se o expurgo com brometo de metila e fosfina em quatro dosagens diferentes e três aplicações. Todas as parcelas expurgadas foram tratadas com malation 4% após o expurgo. Usaram-se duas testemunhas não expurgadas: uma, tratada com malation, pó, 4%, e outra, sem defensivo. O expurgo + malation demonstrou ser uma prática eficaz para proteger o alho armazenado dos ataques das traças e do ácaro. A fosfina e o brometo de meta igualaram-se no controle destas pragas; as dosagens de 5 cm3/m3 para o brometo e de uma pastilha/m3 para a fosfina foram suficientes numa única aplicação, no primeiro caso, e em três aplicações (outubro, dezembro e fevereiro) no segundo caso. Estas dosagens não prejudicaram a brotação, mas quando a dosagem de brometo de metila foi elevada para 15 cm3/m3, observou-se prejuízo na brotação. O malation, isoladamente, se bem que dando um controle superior à testemunha sem tratamento, não foi eficaz no controle das traças e do ácaro. A presença destas pragas nos bulbos não influenciou o número de brotos resultantes nem o seu peso

Irrigação da cultura do alho no Distrito Federal.

bitstream/item/107323/1/CNPH-DOCUMENTOS-01.IRRIGACAO-DA-CULTURA-DO-ALHO-NO-DISTRITO-FEDERAL-FL-07769-.pd

Bursts in a fiber bundle model with continuous damage

We study the constitutive behaviour, the damage process, and the properties of bursts in the continuous damage fiber bundle model introduced recently. Depending on its two parameters, the model provides various types of constitutive behaviours including also macroscopic plasticity. Analytic results are obtained to characterize the damage process along the plastic plateau under strain controlled loading, furthermore, for stress controlled experiments we develop a simulation technique and explore numerically the distribution of bursts of fiber breaks assuming infinite range of interaction. Simulations revealed that under certain conditions power law distribution of bursts arises with an exponent significantly different from the mean field exponent 5/2. A phase diagram of the model characterizing the possible burst distributions is constructed.Comment: 9 pages, 11 figures, APS style, submitted for publicatio