Effect of fuels on the piston rings of the flexfuel engines / Efeito dos combustíveis nos anéis de pistão dos motores de combustível

This study describes the wear in piston rings of the internal combustion engines. The objective was to investigate, the rings wear between two engine groups, as gasoline, alcohol or blend fuel. The piston rings were acquired in a motor parts store and engine reconditioner, cataloged, identified, and chosen the samples with high mileage. The first step involved the measurement of height, thickness and ring outer diameter, to compare them with the original measurements of the manufacturers and make comparison between the groups, gasoline and flexfuel engine. In the second step, the rugosimetric parameters of the surface of the samples were checked with a rugosimeter. In the third step, a microscopic analysis was performed by a SEM for analysis of the contact surface coating of the piston rings. It was found that differences between the two groups of piston ring in respect to the wear. So, it was concluded that the wear of the rings of the two groups of engines are similar quantitatively, however, as for the rugosimetric analysis, a great variation was observed in the rings of the flexfuel motors qualitatively, when compared with the gasoline engines rings.

Population Genetics, Evolutionary Genomics, and Genome-Wide Studies of Malaria: A View Across the International Centers of Excellence for Malaria Research.

The study of the three protagonists in malaria-the Plasmodium parasite, the Anopheles mosquito, and the human host-is key to developing methods to control and eventually eliminate the disease. Genomic technologies, including the recent development of next-generation sequencing, enable interrogation of this triangle to an unprecedented level of scrutiny, and promise exciting progress toward real-time epidemiology studies and the study of evolutionary adaptation. We discuss the use of genomics by the International Centers of Excellence for Malaria Research, a network of field sites and laboratories in malaria-endemic countries that undertake cutting-edge research, training, and technology transfer in malarious countries of the world

A System for the Synchronized Recording of Sonomyography, Electromyography and Joint Angle

Ultrasound and electromyography (EMG) are two of the most commonly used diagnostic tools for the assessment of muscles. Recently, many studies reported the simultaneous collection of EMG signals and ultrasound images, which were normally amplified and digitized by different devices. However, there is lack of a systematic method to synchronize them and no study has reported the effects of ultrasound gel to the EMG signal collection during the simultaneous data collection. In this paper, we introduced a new method to synchronize ultrasound B-scan images, EMG signals, joint angles and other related signals (e.g. force and velocity signals) in real-time. The B-mode ultrasound images were simultaneously captured by the PC together with the surface EMG (SEMG) and the joint angle signal. The deformations of the forearm muscles induced by wrist motions were extracted from a sequence of ultrasound images, named as Sonomyography (SMG). Preliminary experiments demonstrated that the proposed method could reliably collect the synchronized ultrasound images, SEMG signals and joint angle signals in real-time. In addition, the effect of ultrasound gel on the SEMG signals when the EMG electrodes were close to the ultrasound probe was studied. It was found that the SEMG signals were not significantly affected by the amount of the ultrasound gel. The system is being used for the study of contractions of various muscles as well as the muscle fatigue

Pulmonary hemorrhage syndrome associated with dengue fever, High-resolution computed tomography findings: a case report

Dengue hemorrhagic fever is an acute infectious disease caused by dengue virus. We described the high-resolution CT findings in a 70-year-old male with the disease, which was diagnosed by clinical examination and confirmed by serological methods. High-resolution CT demonstrated bilateral areas of consolidation with air bronchogram and ground glass opacities, as well as small bilateral pleural effusions. Dengue hemorrhagic fever should be considered in the differential diagnosis of diffuse pulmonary hemorrhage

Understanding Phase Transitions with Local Optima Networks: Number Partitioning as a Case Study

Phase transitions play an important role in understanding search difficulty in combinatorial optimisation. However, previous attempts have not revealed a clear link between fitness landscape properties and the phase transition. We explore whether the global landscape structure of the number partitioning problem changes with the phase transition. Using the local optima network model, we analyse a number of instances before, during, and after the phase transition. We compute relevant network and neutrality metrics; and importantly, identify and visualise the funnel structure with an approach (monotonic sequences) inspired by theoretical chemistry. While most metrics remain oblivious to the phase transition, our results reveal that the funnel structure clearly changes. Easy instances feature a single or a small number of dominant funnels leading to global optima; hard instances have a large number of suboptimal funnels attracting the search. Our study brings new insights and tools to the study of phase transitions in combinatorial optimisation

Mecânica da fratura aplicada em juntas soldadas do aço astm A672 GR B em tubulações de processo / Fracture mechanics applied to welded joints in astm A672 GR B steel in process pipes

Este trabalho avaliou a geração de trincas internas em juntas soldadas em tubulações industriais de aço ASTM A672 grau B. Nessa abordagem foi utilizado o Diagrama de Falhas – FAD, que avaliou descontinuidades planares da estrutura da solda através de ensaios não destrutivos. Foram estudados parâmetros envolvendo mecânica da fratura e os efeitos micro estruturais que contribuem para a avaliação da integridade estrutural. As amostras foram obtidas do Sistema de Flare Geral da Unidade de Hidrotratamento de Diesel localizada no Complexo Petroquímico do Estado do Rio de Janeiro – COMPERJ. Os resultados mostraram que, em juntas soldadas, novos critérios podem ser inseridos na avaliação de defeitos em relação às propriedades mecânicas do material. Após analisar as tensões por difração de raios X, foi possível se avaliar as condições de operação da tubulação, posição, geometria da trinca e as tensões atuantes que contribuem para a análise de peças que seriam reprovadas em testes. Os resultados mostraram também que as tensões geradas sempre relacionam as condições operacionais na linha, envolvendo pressão e temperatura, resultou em posicionamento no diagrama de falhas, em regiões seguras que demonstraram a inexistência de probabilidade de falha do material. 

Foundations of Black Hole Accretion Disk Theory

This review covers the main aspects of black hole accretion disk theory. We begin with the view that one of the main goals of the theory is to better understand the nature of black holes themselves. In this light we discuss how accretion disks might reveal some of the unique signatures of strong gravity: the event horizon, the innermost stable circular orbit, and the ergosphere. We then review, from a first-principles perspective, the physical processes at play in accretion disks. This leads us to the four primary accretion disk models that we review: Polish doughnuts (thick disks), Shakura-Sunyaev (thin) disks, slim disks, and advection-dominated accretion flows (ADAFs). After presenting the models we discuss issues of stability, oscillations, and jets. Following our review of the analytic work, we take a parallel approach in reviewing numerical studies of black hole accretion disks. We finish with a few select applications that highlight particular astrophysical applications: measurements of black hole mass and spin, black hole vs. neutron star accretion disks, black hole accretion disk spectral states, and quasi-periodic oscillations (QPOs).Comment: 91 pages, 23 figures, final published version available at http://www.livingreviews.org/lrr-2013-