Contribution of sugar-cane harvesting season to atmospheric contamination by polycyclic aromatic hydrocarbons (PAHs) in Araraquara city, Southeast Brazil

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

Voltammetric Determination of Phosphate in Brazilian Biodiesel Using Two Different Electrodes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The Chemical Percolation Devolatilization Model Applied to the Devolatilization of Coal in High Intensity Acoustic Fields

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Desempenho de um motor de trator agrícola em bancada dinamométrica com biodiesel de óleo de frango e misturas binárias com óleo diesel

O Brasil, terceiro maior produtor de biodiesel do mundo e terceiro maior produtor mundial de frango, pode incrementar, na sua matriz energética, o uso de óleo oriundo de aves como alternativa aos combustíveis fósseis e à redução da dependência do óleo de soja para esse fim. O país dispõe de mais de 350 milhões de litros de óleo de frango por ano. Considerando a aplicação dos combustíveis alternativos para os motores a diesel, em máquinas agrícolas, o trabalho teve por objetivo avaliar o desempenho do motor de um trator agrícola de 53kW acoplado pela TDP em bancada dinamométrica, operando com biodiesel metílico de óleo de frango e misturas com óleo diesel, sendo: B5 (testemunha), B20, B40, B60, B80 e B100. Avaliaram-se a potência, o torque, a reserva de torque, o consumo de combustível, o consumo de energia e a eficiência térmica do motor. O ensaio foi instalado com delineamento inteiramente casualizado (DIC) em esquema fatorial com seis tratamentos. Os resultados foram submetidos à análise de variância e as médias ajustadas por equações de regressão. Foram observadas perdas na geração de potência e torque, aumento no consumo de combustível, redução do consumo energético e melhoria na eficiência térmica do motor, de acordo com o aumento da proporção de biodiesel na mistura.

Reducing the gap between mobile and intelligent software agents

This paper presents an approach to integrate an artificial intelligence (AI) technique, concretely rule-based processing, into mobile agents. In particular, it focuses on the aspects of designing and implementing an appropriate inference engine of small size to reduce migration costs. The main goal is combine two lines of agent research, First, the engineering oriented approach on mobile agent architectures, and, second, the AI related approach on inference engines driven by rules expressed in a restricted subset of first-order predicate logic (FOPL). In addition to size reduction, the main functions of this type of engine were isolated, generalized and implemented as dynamic components, making possible not only their migration with the agent, but also their dynamic migration and loading on demand. A set of classes for representing and exchanging knowledge between rule-based systems was also proposed.

Simultaneous determination of quinoline and pyridine compounds in gasoline and diesel by differential pulse voltammetry

The presence of trace basic organonitrogen compounds such as quinoline and pyridine in derivative petroleum fuels plays an important role in maintaining the engines of vehicles. However, these substances can contaminate the environment and so must be controlled because most of them are potentially carcinogenic and mutagenic. For these reasons, a reliable and sensitive method was developed for the determination of basic nitrogen compounds in fuel samples such as gasoline and diesel. This method utilizes preconcentration on an ion-exchange resin (Amberlyte IR - 120 H) followed by differential pulse voltammetry (DPV) on a glassy carbon electrode. The electrochemical behavior of quinoline and pyridine as studied by cyclic voltammetry (CV) suggests that their reduction occurs via a reversible electron transfer followed by an irreversible chemical reaction. Very well resolved diffusion-controlled voltammetric peaks were obtained in dimethylformamide (DMF) with tetrabutylammonium tetrafluoroborate (TBAF(4) 0.1 mol L-1) for quinoline (-1.95 V) and pyridine (-2.52 V) vs. Ag vertical bar AgCl vertical bar KClsat reference electrode. The proposed DPV method displayed a good linear response from 0.10 to 300 mg L-1 and a limit of detection (LOD) of 5.05 and 0.25 mu g L-1 for quinoline and pyridine, respectively. Using the method of standard additions, the simultaneous determination of quinoline and pyridine in gasoline samples yielded 25.0 +/- 0.3 and 33.0 +/- 0.7 mg L-1 and in diesel samples yielded 80.3 +/- 0.2 and 131 +/- 0.4 mg L-1, respectively. Spike recoveries were 94.4 +/- 0.3% and 10 +/- 0.5% for quinoline and pyridine, respectively, in the fuel determinations. This proposed method was also compared with UV-vis spectrophotometric measurements. Results obtained for the two methods agreed well based on F and t student's tests.

Pb-210-derived chronology in sediment cores evidencing the anthropogenic occupation history at Corumbata River basin, Brazil

Activity profiles of excess Pb-210 combined with chemical data determined in two sediment cores from Corumbatai River basin, São Paulo State, Brazil, provided new insights into the reconstruction of historical inputs of anthropogenic constituents, contributing to improving management strategies of the hydrological resources in the basin since most of the municipalities extensively utilize the waters of Corumbatai River and tributaries for drinking purposes, among other uses. Excellent significant relationships between loss on ignition (LOI) and organic matter were found for sediments of both analyzed profiles. Silica was found to be inversely related to organic matter at both analyzed profiles: its decrease accompanied an increase in the specific surface of the sediments. This relationship was confirmed by a great number of inverse significant correlations among silica and oxides Na2O, K2O, CaO, MgO, Al2O3, P2O5, Fe2O3, MnO, and TiO2. It was possible to identify the role of organic matter on adsorption of several oxides/elements in the core sediments profiles. Apparent sediment mass accumulation rates corresponding to 224 and 802 mg cm(-2) year(-1) were obtained, and are compatible with field evidence, indicating a higher value associated with sand mining activities interfering with the natural/normal sedimentation process, due to modifications of the channel drainage.

A case study of compact cogeneration using various fuels

A method for studying the technical and economic feasibility of absorption refrigeration systems in compact cogenerators is presented. The system studied consists of an internal combustion engine, an electric generator and a heat exchanger to recover residual heat from the refrigeration water and exhaust gases. As an application, a computer program simulates the cogeneration system in a building which already has 75 kW of installed electric power. The maximum electric and refrigeration demands are 45 kW and 76 kW respectively. This study simulates the system performance, utilizing diesel oil, sugar cane alcohol and natural gas as possible fuels. (C) 1997 Elsevier B.V. Ltd.

Comparative study of cogeneration systems in a chemical industry

With the large penetration of the natural gas into the Brazilian energy structure, industries such as paper mills and chemical plants are analyzing the feasibility of implementing cogeneration schemes appropriate to this fuel. The analysis of the energy demand patterns of a chemical company from the photographic sector revealed the possibility of using combined cycles or diesel engine cogeneration schemes keeping the existing compression refrigeration units and steam or gas cycle cogeneration systems with absorption refrigeration units. In terms of economic attractiveness, an analysis based on the method of the internal rate of return was performed. The results indicated that the schemes composed by reciprocating engines and combined cycle with compression chillers, as well as the gas cycle scheme with absorption chiller, present return periods of up to 3 years, showing that the investment in cogeneration could be of interest for this plant. (C) 2000 Elsevier B.V. Ltd. All rights reserved.

Flammability limits: A review with emphasis on ethanol for aeronautical applications and description of the experimental procedure

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

Cogeneration for small users: case studies for Brazilian tertiary sector

In this paper we present technical and economic studies of cogeneration systems utilizing combustion engines and gas turbines, applied in two establishments of the tertiary sector, regarding Brazilian conditions (according to Silveria, 1994). In the first step cogeneration systems utilizing combustion engines associated to absorption refrigeration systems are studied, in which electricity and cold air for a university building rate produced. In the second step some possibilities of the use of the gas turbine in cogeneration systems for a hospital are shown. In this case, the exhaust gases are utilized for the production of steam in a heat recovery steam generator (HRSG) or cold water in an absorption refrigeration system (for air conditioning) for the hospital building. The dynamic increment of the energy demand of Brazilian tertiary sector in last years can increase the installation of these cogeneration system (in compact version) as well as strengthen the development of the decentralized energy generation in Brazil.

An attack signature model to computer security intrusion detection

Internal and external computer network attacks or security threats occur according to standards and follow a set of subsequent steps, allowing to establish profiles or patterns. This well-known behavior is the basis of signature analysis intrusion detection systems. This work presents a new attack signature model to be applied on network-based intrusion detection systems engines. The AISF (ACME! Intrusion Signature Format) model is built upon XML technology and works on intrusion signatures handling and analysis, from storage to manipulation. Using this new model, the process of storing and analyzing information about intrusion signatures for further use by an IDS become a less difficult and standardized process.

Dimmable electronic ballast with high power-factor SEPIC preregulator, for multiple tubular fluorescent lamps

An electronic ballast for multiple tubular fluorescent lamps is presented in this paper. The proposed structure features high power-factor, dimming capability, and soft-switching to the semiconductor devices operated in high frequencies. A Zero-Current-Switching - Pulse-Width-Modulated (ZCS-PWM) SEPIC converter composes the rectifying stage, controlled by the instantaneous average input current technique, performing soft-commutations and high input power factor. Regarding the inverting stage, it is composed by a classical resonant Half-Bridge converter, associated to Series Parallel-Loaded Resonant (SPLR) filters. The dimming control technique employed in this Half-Bridge inverter is based on the phase-shift in the current processed through the sets of filter + lamp. In addition, experimental results are shown in order to validate the developed analysis.

Preliminary Overview of the Economies of Latin America and the Caribbean 2004

Includes bibliography

Preliminary Overview of the Economies of Latin America and the Caribbean 2010

Includes bibliography