Report on "Scheduling in a factory"

In order to carry out their orders of shoe soles, this company has a number of tasks T_1, ..., T_n of different lengths to be assigned to groups of machines. Each group is operated by one worker (two in one case), and an operation cycle corresponds to injection, cooling, and removal of the sole. The time taken at each step varies from one order to another, and when starting a new task a machine needs to be tuned, which takes some extra time. Machines are working in parallel. At the moment the assignment is carried out empirically, and the problem proposed is to optimize the procedure

Effect of Level Statistics on Local Magnetism in Nanoscale Metallic Grains

Effect of level statistics on local electronic states and local magnetism in nanoscale metallic grains with transition-metal impurity in the ballistic regime is studied. It is shown that the mean occupation of local electron and the local magnetic moment in nanoscale metallic grains with odd conduction electrons are larger than those with even conduction electrons. The effect of even-odd parity on the condition for the occurrence of local magnetic moment is also discussed, it is found that the critical value $\rho_{d}(0)U_{c}$ for the formation of local moment in nanoscale metallic grains is much smaller than that in bulks. The dependences of the local spin susceptibility on size and the Coulomb interaction are obtained. These results show that the level statistics plays an important role for the local magnetism, it distinguishes the properties of nanoscale metallic grains from those of small clusters and bulks.Comment: Latex, 6 figures in Postscrip

Inhomogeneous Superconductivity in Comb-Shaped Josephson Junction Networks

We show that some of the Josephson couplings of junctions arranged to form an inhomogeneous network undergo a non-perturbative renormalization provided that the network's connectivity is pertinently chosen. As a result, the zero-voltage Josephson critical currents $I_c$ turn out to be enhanced along directions selected by the network's topology. This renormalization effect is possible only on graphs whose adjacency matrix admits an hidden spectrum (i.e. a set of localized states disappearing in the thermodynamic limit). We provide a theoretical and experimental study of this effect by comparing the superconducting behavior of a comb-shaped Josephson junction network and a linear chain made with the same junctions: we show that the Josephson critical currents of the junctions located on the comb's backbone are bigger than the ones of the junctions located on the chain. Our theoretical analysis, based on a discrete version of the Bogoliubov-de Gennes equation, leads to results which are in good quantitative agreement with experimental results.Comment: 4 pages, 2 figures, revte

Lixiviação de atrazina em solo em área de recarga do Aquífero Guarani.

No Aqüífero Guarani, o maior e mais importante lençol de água subterrânea de toda a região centro-sul do país, encontra-se a microbacia do Córrego do Espraiado, um dos seus pontos de recarga. Nesta área, existe predomínio de culturas, nas quais são utilizados herbicidas da família das triazinas e a presença de solo arenoso, que tornam a área vulnerável à lixiviação. Entre os produtos aplicados encontra-se a atrazina (2-chloro-4-(ethylamino)-6-(isopropylamino)-S-triazine). Devido as suas características físico-químicas, esse herbicida tem alto potencial de risco de movimentar-se para água subterrânea. Para avaliar a lixiviação da atrazina foram feitas amostragens de solo para análise física e de água superficial e subterrânea, durante os anos de 2000 a 2002, para análise de resíduo através de cromatografia líquida HPLC (High Performance Liquid Chromatography), e confirmadas com GC-MS (Gas chromatography-mass spectrometry). Apenas quatro amostras de água superficial apresentaram resíduos de atrazina. Destas, duas com 0,04; e as outras com 0,05 e 0,09 ug/L. Nas amostras de água subterrânea os resultados indicaram uma amostra contendo 0,03 ug/L de atrazina. Entretanto, nenhuma delas foi confirmada pelo GC-MS, não indicando resíduos. A presente avaliação contou também com o uso do simulador de sistemas CMLS-94 (Chemical Movement in Layered Soils). O simulador também mostrou que a atrazina não atinge profundidades comprometedoras para a qualidade do aquífero

Proposta de Boas Práticas Agrícolas para as áreas de afloramento do Aqüífero Guarani em Ribeirão Preto, SP.

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Herbicide leaching on a recharge área of Guarany Aquifer, Brazil.

The region of Ribeirao Preto city, located in Southeast of Brazil, Sao Paulo State, is an important sugarcane, soybean, and corn producing area with a high level of pesticide utilization. This region is also an important recharge area for groundwater supply of the Guarany aquifer. A survey has shown the following herbicides as the most commonly used in the area: atrazine, simazine, ametryn, tebuthiuron, diuron, and 2,4-D. In order to study a possible leaching of the herbicides into the aquifer, surface and ground water samples were collected during the years of 1996 to 2003 from different points. Groundwater samples were collected from sites near the river during the same period. It was used a GC-MS to detect and quantify the herbicides (gas chromatograph/mass spectrometry). The method was linear over the range of 0.02 to 2.0 ?g/L. Analysis of tebuthiuron, diuron, atrazine, simazine and ametryn residues showed no significance amount of these products in ground water. Only two out of nine points of surface water collected in one year, presented ametryn concentrations above (0.17 and 0.23 ug/L) the allowable 0.1 ug/L, European safety level. It was also used the simulator model CMLS-94, ?Chemical Movement Layered Soil? which indicated no leaching to the depths of the water table at 40m

Presence of Atrazine in Water in a Recharge Area of Guarany Aquifer in Brazil

The region of Ribeirao Preto City located in Sao Paulo State, southeastern Brazil, is an important sugarcane, soybean and corn producing area. This region is also an important recharge area for groundwater of the Guarany aquifer, a water supply source of the city and region. The cultivation of grain and sugar cane in thes area demands the frequent use of the herbicide atrazine (2-chloro-4- (ethylamino)-6-(isopropylamino)-S-triazine). This research was conducted to characterize the potential contamination of groundwater with atrazine. Surface water samples were collected in the Espraiado stream in a selected watershed on the area, during the years of 1995-1998. Groundwater was also collected in wells located at the edge of the watershed during the years of 1999 to 2002. The water samples were analyzed by HPLC (High Performance Liquid Chromatography) procedure followed by GC-MS form confirmation. To predict the atrazine leaching in the area, the CMLS-94 (Chemical Movement Layered Soil) simulation model was also used. Only four atrazine detections in surface water were found, however, none of them were confirmed with GC-MS. No atrazine was detected in groundwater samples. The results obtained by the CMLS-94 simulations predicted that atrazine, after four years from the application date, would not have reached the depth of the confined aquifer (40m)

Uso de Métodos Espectroscópicos para Avaliar o Seqüestro de Carbono em Área de Rotação de Culturas Cana-de-açúcar/Amendoim Sob Diferentes Sistemas de Plantio.

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Herbicide and nitrate residues in surface and groundwater from sugarcane area in Brazil.

Various studies have demonstrated the presence at high levels of pesticides and nitrate in soil, surface, and groundwater. Prior studies have identified a watershed area in Brazil with a high risk of soil, surface, and groundwater contamination by pesticides at the region of Riberao Preto, SP. Surface and groundwater were collected at the area during the period of October 1995 to November 1998. By means of gas chromatography-mass spectrometry (GC-MS) technique the herbicides tebuthiuron, diuron, simazine, atrazine, and ametryne, and nitrate were analyzed according to the protocols established in literature. The recovery obtained in the extraction procedure was higher than 95% for all herbicides except simazine for which the recovery was 85,6%. Due to the enrichment in the extraction procedure and the sensitive detection at two wavelengths it was possible to obtain a quantification limit of 0.02 ug/L for the herbicides studied. The method was linear over the range of 0.02 to 2.0 ug/L. Soil data showed a higher level of the herbicide tebuthiuron, at the levels of 59.6 ppb; than the other applied during all the months. The results have shown the hercicide tebuthiuron as the one with higher concentrations in groundwater and in January of 1996 the concentration found was 0.08 ug/L, close to the maximum allowed, 0.1 ug/L, but this fact was not consistent during the other months. No residue of the other herbicides was detected. In case of nitrates, with maximum level allowed of 10 mg/L, it was found the maximum of 0.9 mg/l, but in a shallow well inside the area. Commercial wells at the edge of the watershed showed low levels of nitrate, below the risk level, but with potential for dangerous contamination.bitstream/item/199623/1/Cerdeira-Herbicide.pd