ROAD TRANSPORT IN BRAZIL: SOME TYPES of VISCOSITY

The planning of the transportation sector in Brazil has long been the railroads as the main engineering system of the country. Thus, it was used to carry, in addition to the physical integration of the national territory, the consolidation of its domestic market. However, after entering in the 1980s, the planning of the sector is left out, and an inversion of the matrix of development is observed, with share gains in monoculture economy and on development of new areas where agricultural expansion advanced. This situation culminated in logistics blackouts in the 1990s and the resumption of sector planning in the early twenty-first century. At this time, it establishes a new institutional apparatus that ensures the participation of private capital in the sector, as well as a new principle for resolving bottlenecks concentrated regions (economically dynamic), from targeting investments to areas of primary economies that only in recent decades have been incorporated into the national economy.

Characteristics of Dielectric Barrier Discharge Reactor for Material Treatment

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Barrier and Mechanical Properties of Clay-Reinforced Polymeric Nanocomposites

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Selective Ablation of the Androgen Receptor in Mouse Sertoli Cells Affects Sertoli Cell Maturation, Barrier Formation and Cytoskeletal Development

The observation that mice with a selective ablation of the androgen receptor (AR) in Sertoli cells (SC) (SCARKO mice) display a complete block in meiosis supports the contention that SC play a pivotal role in the control of germ cell development by androgens. To delineate the physiological and molecular mechanism responsible for this control, we compared tubular development in pubertal SCARKO mice and littermate controls. Particular attention was paid to differences in SC maturation, SC barrier formation and cytoskeletal organization and to the molecular mediators potentially involved. Functional analysis of SC barrier development by hypertonic perfusion and lanthanum permeation techniques and immunohistochemical analysis of junction formation showed that SCARKO mice still attempt to produce a barrier separating basal and adluminal compartment but that barrier formation is delayed and defective. Defective barrier formation was accompanied by disturbances in SC nuclear maturation (immature shape, absence of prominent, tripartite nucleoli) and SC polarization (aberrant positioning of SC nuclei and cytoskeletal elements such as vimentin). Quantitative RT-PCR was used to study the transcript levels of genes potentially related to the described phenomena between day 8 and 35. Differences in the expression of SC genes known to play a role in junction formation could be shown from day 8 for Cldn11, from day 15 for Cldn3 and Espn, from day 20 for Cdh2 and Jam3 and from day 35 for ZO-1. Marked differences were also noted in the transcript levels of several genes that are also related to cell adhesion and cytoskeletal dynamics but that have not yet been studied in SC (Actn3, Ank3, Anxa9, Scin, Emb, Mpzl2). It is concluded that absence of a functional AR in SC impedes the remodeling of testicular tubules expected at the onset of spermatogenesis and interferes with the creation of the specific environment needed for germ cell development.

Theory of electrical characteristics for metal-oxide-insulator Schottky barrier and metal-insulator-metal structures

The metal-insulator or metal-amorphous semiconductor blocking contact is still not well understood. Here, the intimate metal-insulator and metal-oxide-insulator contact are discussed. Further, the steady-state characteristics of metal-oxide-insulator-metal structures are also discussed. Oxide is an insulator with wider energy band gap (about 50 Å thick). A uniform energetic distribution of impurities is considered in addition to impurities at a single energy level inside the surface charge region at the oxide-insulator interface. Analytical expressions are presented for electrical potential, field, thickness of the depletion region, capacitance, and charge accumulated in the surface charge region. The electrical characteristics are compared with reference to relative densities of two types of impurities. ln I is proportional to the square root of applied potential if energetically distributed impurities are relatively important. However, distribution of the electrical potential is quite complicated. In general energetically distributed impurities can considerably change the electrical characteristics of these structures.

Time and distance in acceleration of road commercial vehicles

The time and the distance traveled during the acceleration and the velocity retaking are parameters used for the comparison and the project of vehicles. In this paper equations for the calculation of those parameters are presented. Several criteria are presented for the shift gears. It is also verified the occurrence or not of total slip during the acceleration of the vehicle. The theoretical models were implemented in a developed computational system. Such system was applied in a Mercedes-Benz do Brazil sample vehicle, in order to facilitate comparisons between the simulate values and the experimental road tests. Copyright © 1997 Society of Automotive Engineers, Inc.

Fuel consumption of road commercial vehicles in the driving schedule

The fuel consumption is an important factor in the vehicle development due the fact that it has a direct effect on its trade aims. Besides that, it is known that the petrol is a scarce fuel. In this paper it is presented a procedure of fuel consumption calculation for a vehicle traveling in driving schedule. In such calculation it has been taken into account the operational conditions (load, pavement, climbing road, among others) and the building characteristics (map engine, transmission, frontal area, tire, among others) of road vehicles. There has also been an application of the theoretical model developed in a sample Mercedes-Benz do Brasil vehicle which has been compared with the values of experimental tests. Copyright © 1997 Society of Automotive Engineers, Inc.

Wasmannia spp. (Hym., Formicidae) and insect damages to cocoa in Brazilian farms

Diagnostic insect damage to cocoa tree leaves and fruits were compared in situations with and without the presence of the little fire ants, Wasmannia auropunctata and the closely related and sympatric W. cf rochai. No significant differences in thrips, lepidopteran, or chrysomelid beetle damage to fruits, or to young and old leaves, were associated with these ants. However, significant increases of pseudococcids Planococcus citrii, associated with areas dominated by W. auropunctata, and to a lesser degree with W. cf rochai, were present. W. auropunctata has been reported to be a canopy mosaic dominant in cocoa farms, but the lack of reduced herbivore incidences and its lack of spatial permanence do not support favoring its populations for the management of phytophagous insect control.

Georeferenced road extraction and formulation of hypotheses for new road segments

The acquisition and update of Geographic Information System (GIS) data are typically carried out using aerial or satellite imagery. Since new roads are usually linked to georeferenced pre-existing road network, the extraction of pre-existing road segments may provide good hypotheses for the updating process. This paper addresses the problem of extracting georeferenced roads from images and formulating hypotheses for the presence of new road segments. Our approach proceeds in three steps. First, salient points are identified and measured along roads from a map or GIS database by an operator or an automatic tool. These salient points are then projected onto the image-space and errors inherent in this process are calculated. In the second step, the georeferenced roads are extracted from the image using a dynamic programming (DP) algorithm. The projected salient points and corresponding error estimates are used as input for this extraction process. Finally, the road center axes extracted in the previous step are analyzed to identify potential new segments attached to the extracted, pre-existing one. This analysis is performed using a combination of edge-based and correlation-based algorithms. In this paper we present our approach and early implementation results.

A barrier method for constrained nonlinear optimization using a modified Hopfield network

The ability of neural networks to realize some complex nonlinear function makes them attractive for system identification. This paper describes a novel barrier method using artificial neural networks to solve robust parameter estimation problems for nonlinear model with unknown-but-bounded errors and uncertainties. This problem can be represented by a typical constrained optimization problem. More specifically, a modified Hopfield network is developed and its internal parameters are computed using the valid-subspace technique. These parameters guarantee the network convergence to the equilibrium points. A solution for the robust estimation problem with unknown-but-bounded error corresponds to an equilibrium point of the network. Simulation results are presented as an illustration of the proposed approach.

An investigation of electrolytic surface damages and electroplated crhomium effects on fatigue behavior of high strength steel

Fatigue crack initiation occurs at the surface, although sub surface nucleation has also been reported. Localized imperfections like inclusions close to surface and surface small pits can result in crack sources. Coatings are not always beneficial by fatigue point of view too. Mechanical properties of the covering material can change considerably the fatigue behavior of base metal due to residual surface stresses, to micro cracks or to hydrogen embrittlement. This paper is concerned with analysis of electrolytic etch on the fatigue resistance of a 35NCD16 high strength steel in a mechanical condition of (1760 - 1960) MPa, and analysis of electroplated hard chromium effects on the fatigue resistance in a strength condition of 989 MPa. Hardness impression was used as a reference parameter in case of electrolytic etch. In both cases, experimental data showed that fatigue strength of 35NCD16 steel was considerably reduced. Copyright © 2001 Society of Automotive Engineers, Inc.

Road segment delineation using active testing principle and an edge-based post-processing strategy

This paper presents a semi-automated method for extracting road segments from medium-resolution images based on active testing and edge analysis. The method is based on two sequential and independent stages. Firstly, an active testing method is used to extract an approximated road centreline which is based on a sequential and local exploitation of the image. Secondly, an iterative strategy based on edge analysis and the approximated centreline is used to measure precisely the road centreline. Based on the results obtained using medium-resolution test images, the method seems to be very promising. In general, the method proved to be very accurate whenever the roads are characterized by two well-defined anti-parallel edges and robust even in the presence of larger obstacles such as trees and shadows.

Damages occurrence and determination of dasineura Sp. (Díptera: Cecidomyiidae) in the pepper cultivars (Capsicum annuum L.) in piracicaba Sp.

The purpose of this study was to evaluate the damage potential of Dasineura sp. (Diptera: Cecidomyiidae) in the pepper cultivars and show its occurrence in Piracicaba, SP. This experiment was carried out from July to November 1998. The occurrence and damages pest in the fruits were determined by weekly evaluations of pepper hybrids, 'Magali R.' larvals were collected from floral buttons and adults were collected from the incubation of buttons in humidity chamber. Healthy and infested fruits were evaluated for damages caused by pest insects. The results indicated that the damages can reach 100% in some periods of evaluation and that the production losses are significantly high with no application of insecticides. The taxonomy study was performed at National Museum of Federal University of Rio de Janeiro (UFRJ). The insect species classification will be the object of study since there is a possibility of observing a specie not described yet.

Modified barrier method for optimal power flow problem

In this paper is presented a new approach for optimal power flow problem. This approach is based on the modified barrier function and the primal-dual logarithmic barrier method. A Lagrangian function is associated with the modified problem. The first-order necessary conditions for optimality are fulfilled by Newton's method, and by updating the barrier terms. The effectiveness of the proposed approach has been examined by solving the Brazilian 53-bus, IEEE118-bus and IEEE162-bus systems.