Voidage distribution around bubbles in a fluidized bed: influence on throughflow

In this work, a new method for measuring void fraction distribution around endogenous bubbles in a 2D fluidized bed is presented. The technique is based on illuminating a transparent-wall 2-dimensional bed with diffuse light from the rear and recording the distribution of light that penetrates the bed. The recording is made with a high speed video-camera, which gives frames with grey level corresponding to the light penetration and from which the voidage distribution around the bubbles can be determined. In this way, voidage distribution in the region very close to the bubble contour (r/Rb≲1.2) is obtained, which was not possible in previous studies due to limitations in spatial resolution. A correlation is proposed for the voidage at the contour of the bubble, with the voidage depending on the radial position and the polar angle ε(r, θ). In addition, the effect of the voidage distribution on the throughflow crossing the bubbles was studied and an increase of 20% was determined for the average bubble geometry of the more than 100 bubbles analysedPublicad

Game Theory Models for Multi-Robot Patrolling of Infraestructures

Abstract This work is focused on the problem of performing multi‐robot patrolling for infrastructure security applications in order to protect a known environment at critical facilities. Thus, given a set of robots and a set of points of interest, the patrolling task consists of constantly visiting these points at irregular time intervals for security purposes. Current existing solutions for these types of applications are predictable and inflexible. Moreover, most of the previous centralized and deterministic solutions and only few efforts have been made to integrate dynamic methods. Therefore, the development of new dynamic and decentralized collaborative approaches in order to solve the aforementioned problem by implementing learning models from Game Theory. The model selected in this work that includes belief‐based and reinforcement models as special cases is called Experience‐Weighted Attraction. The problem has been defined using concepts of Graph Theory to represent the environment in order to work with such Game Theory techniques. Finally, the proposed methods have been evaluated experimentally by using a patrolling simulator. The results obtained have been compared with previous availabl

Soil quality and agricultural sustainability in the Brazilian Cerrado.

The "Cerrado Region" - the acid savannas of Brazil, as many as thirty years ago, were considered as ecosystem unsuitable for agriculture crop production because environmental limitations. However, a burst in agricultural development has taken place in the area during last decades as a result of new technology mainly involving plant breeding and soil management. In spite of the great contribution made by the "Cerrado" region to the Brazilian agricultural production, over the past few years concerns have been raised about the issue of the high costs of this agriculture production and about the issue of soil quality degradation, and how it could affect the sustainability of the agriculture in the "Cerrado" ecosystem. The concept of sustainable agriculture is well recognized research, development, and productive segments of today's agriculture, however, the notion of how to measure and monitor sustainability of farming systems is much les understood. This paper proposes a system of measuring and monitoring the sustainability of farming systems using soil quality indicators in the acid savannas of Brazil. The methodology utilized and agroecological framework to examine the relations among natural resources and agriculture, selectiong one agroecological zone inserted in the cerrado ecosystem. This selected zone was subdivided into regions superimposing Census data, because policy and socioeconomic differences among regions have a considerable influence on land-use systems and options. Target areas were selected and participatory rural appraisal procedure was used to supplement voids in data, identify and characterize predominant farming systems, and to capture farmer knowledge. Using this farmer knowledge, research results already available and local observations, the mainly factors affecting soil quality were identified. Assuming that a management system is sustainable only when soil quality is maintained of improved, physical, chemical and biological properties, processes and characteristics were closen as indicators to make qualitative and quantitative assessment of the changes in soil quality. Based upon these evaluations, a general procedure or framework for sustainability assessment was developed. Using the procedure, it is possible to identify whether current management interventions are contributing towards or away from sustainable farming management, and to develop strategies to improve sustainability of those systems

Efisiensi Beberapa Substrat Dalam Pengujian Viabilitas Benih Berukuran Besar Dan Kecil (Efficiency of Several Substrates for Seed Viability Testing of Large and Small Seeds)

The quality of paper substrate for seed viability testing is determined mainly by the variety and amount of the papers. A study was conducted to find alternative paper and the optimum amount of paper for testing the viability of large and small seed with the rolled paper method. Two experiments were carried out at the Seed Science and Technology Laboratory, Bogor Agricultural University during April-September 2004 and July-December 2007. First experiment: large and small seeds represented by 5 plants (angled loofah, pumpkin, garden pea, bitter gourd, yam bean) and 7 plants (sorghum, cucumber, mungbean, soybean, horenzo, radish and wheat), respectively, were tested on 4 different paper substrates (straw, stencil, CD, and HVS) following the rolled paper method. Second experiment: large seeds of maize and ground nut, and small seeds of rice and mungbean were tested on paper substrates selected from the first experiment, straw, stencil, and CD, with different number of sheet, i.e. 2, 3, 4, and 5 sheets. Each plant seed was considered as an experiment and a randomized block design was applied to all experiments. The result indicated that for the large seeds, stencil and CD papers had equal and high similarity with the reference straw paper substrate, 100% and 80% for germination percentage and dry weight of normal seedlings, respectively. For the small seeds, only stencil paper showed high similarity for germination percentage variable, 86%, with the reference paper, whereas the other paper showed lower similarity, 57% for both CD and HVS papers. The second experiment showed that 2 sheets of straw, stencil or CD papers were enough for testing viability of large and small seeds to obtain germination percentage, but ground nut needs 4 sheets of straw paper. For vigor index variable, efficiency of substrate paper on large and small seeds varied from 2 to 4 sheets

Levantamento de ácaros Brevipalpus e viroses associadas em hospedeiros florestais, agrícolas e ornamentais.

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Primeiro registro de Platycorypha nigrivirga Burckhardt (Hemiptera: Psylloidea), em Tipuana tipu (Benth.), no Brasil.

The occurrence of Platycorypha nigrivirga Burckhardt (Hemiptera: Psyllidae, Acizzinae), is reported for the fi rst time, in Brazil. The psyllid was observed causing injuries on leaves and shoots of Tipuana tipu (Benth.), in urban areas of Paraná State. P. nigrivirga are tiny sap-sucking insects that feed on phloem and cause curling, stains and fall of leaves. The excrements of these insects accumulate on the leaves propitiating fungus growth on the leaves, or they fall in great amount on the cars dirtying them as if they were sparkling of white and sticky ink

Ocorrência de Platypus sulcatus em acácia-negra (Acacia mearnsii).

E reportada, pela primeira vez, a ocorrencia da broca do tronco, Platypus sulcatus Chapius, 1865, Coleoptera: Platypodidae (sinonimia P. plicatus Bretes, 1908) em plantios de Acacia-negra no Estado do Rio Grande do Sul. Esta broca foi observada causando galerias em troncos de arvores, caracterizando-se pela presenca de goma e de serragem no orificio de entrada da galeria.Notas tecnicas

Aplicação de lodo de ETE, oriundo da reciclagem de papel, no plantio de Pinus taeda e sua influência na fauna de solo.

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