No abstract

The performance of particle accelerators depends highly on the relative alignment between their components. The position and orientation of the magnetic lenses that form the trajectory of the charged beam is kept to micrometric tolerances in a range of hundreds of meters of the length of the machines. Therefore, the alignment problem is fundamentally of a dimensional metrology nature. There is no common way of expressing these tolerances in terms of terminology and alignment concept. The alignment needs for a certain machine is normally given in terms of deviations between the position of any magnet in the accelerator and the fitted line that relates the actual position of the magnets’ assembly. Root mean square errors and standard deviations are normally used interchangeably and measurement uncertainty is often neglected. Although some solutions have been employed successfully in several accelerators, there is no off-the-shelf solution to perform the alignment. Also, each alignment campaign makes use of different measuring instruments to achieve the desired results, which makes the alignment process a complex measurement chain. This paper explores these issues by reviewing the tolerances specified for the alignment of particle accelerators, and proposes a metric to assess the quality of the alignment. The metric has the advantage of fully integrating the measurement uncertainty in the process.

-The last four decades have been significant for Brazil"s highway network development. The country received financial incentives for its expansion and created various structural solutions for bridges and overpasses. Concurrent to this development, in recent years these structures have increasingly shown advanced deterioration stages due to the lack of preventive maintenance programs. Thus, this paper proposes the use of a GPS in a short-term monitoring plan to oversee the structural behavior of a curved reinforced concrete highway bridge already in service. Accordingly, this article presentsthe first research results with the L1 carrier and recorded data at 100 Hz in order to monitor the dynamic behavior of the central span of a small curved concrete bridge, the bridge over the Jaguari River in Extrema, Minas Gerais. The problem is that such structures exhibitsmall peak-to-peak amplitude vertical deflections-up to 5 mm.The challenge lies in the fact that the vast majority of Brazil"s highway network is characterized by small and medium sized concrete bridges. The bridge monitored in the study consists of two traffic lanes and a total length of 134 m, located in the Fernão Dias highway-BR 381, km 946 + 300m, Extrema, Minas Gerais. The bridge under study is significant to this work because this type of structure is largely found throughout the country. Thus, the line of work to be presented will contribute to implementing other monitoring actions forthese types of structures throughout Brazil -quickly and effectively,which will serve as a strategythat can beadded to the conventional monitoring methods. Therefore, GPS data observations were conductedfor two days using two GPS receivers with data sampling intervals of 0.01 seconds-100 Hz. The Continuous Wavelet Transform (CWT) was used as filtering model to analyze the frequency response of the bridge generated by the residues of the L1 double difference through the highest GPS satellite constellation.

No abstract

The physical heights definition of heights, proposed by Helmert in 1890 is one of the commonly used heights systems in practice. In Helmert’s definition, the mean value of gravity along plumbline is computed by simplifying the topography with a Bouguer shell containing masses with mean density value. Although this approximation might be accurate enough many purposes, a more rigorous definition can be determined by considering the effects of terrain, topographic mass density variation, and masses contained in the geoid the mean gravity value along the plumbline. The purpose of this paper is to compute the corrections for the Helmert’s definition of the orthometric heights to obtain the rigorous orthometric heights in the state of São Paulo and adjacent states and to evaluate these corrections. The heights system used in Brazil (until July 2018) and some South American countries is normal-orthometric heights, therefore the corrections needs to be applied accordingly. Our numerical results show that there are significant differences between the normal-orthometric and rigorous orthometric heights, with maximum values of ~ 0.4 m, minimum of ~ -0.8 m and mean value of ~ -0.32 m. There are larger differences between normal-orthometric and normal height than the ones between normal and rigorous definition of orthometric heights.

Há diversos métodos para a realização do posicionamento com o GNSS, dentre elas encontra-se o PPP, que na atualidade, é um método de posicionamento, que vislumbra como uma grande potencialidade para obtenção de coordenadas com um alto nível de qualidade, utilizando apenas um receptor. Podendo assim, ser utilizado em aplicações precisas, como a geodinâmica, especificamente em monitoramento da crosta terrestre. O presente trabalho tem como objetivo a análise da influência da carga hídrica na altitude geométrica obtida através do processamento PPP da estação da rede de monitoramento contínuo, denominada MGIN. Nestas análises utilizaram-se dados de temporada de seca e cheia do Rio Mogi-Guaçu e dados de altitude geométrica. A relação entre estes dados mostrou as implicações da carga hídrica sobre as altitudes geométricas, acentuando o soerguimento da crosta. Estes deslocamentos da crosta causados pela influência hídrica, afetam de forma direta as estações GNSS. Isto implica que mesmo com uma distância de 484 metros e uma diferença de nível de 35 metros do rio, o carregamento hídrico influência diretamente na altitude geométrica. PALAVRAS-CHAVE:Altitude Geométrica. Carga Hídrica. Deslocamento da Crosta. PPP.

ABSTRACT. In gravimetric surveys, the determination of the gravity at a specific point depends on field measurements and on the removal of the influence of the tide...Keywords: earth tide correction, gravimetric factor, gravimetry, gravimetric surveys. RESUMO. Em levantamentos gravimétricos a determinação da gravidade de um ponto depende de medições em campo, bem como da remoção da influência da maré...Palavras-chave: correção da maré, fator gravimétrico, gravimetria, levantamento gravimétrico.

Resumo:As últimas quatro décadas foram importantes para o desenvolvimento da malha rodoviária brasileira. O país recebeu incentivos financeiros para a sua expansão e diversas soluções estruturais para pontes e viadutos foram criadas. Em paralelo a este desenvolvimento, houve nos últimos anos um crescimento significativo dessas estruturas em estágio avançado de deterioração devido à ausência de programas de manutenção preventiva. Dessa maneira, este trabalho propõe o uso de receptores GPS num plano de monitoramento de curta duração para acompanhar o comportamento estrutural de uma ponte rodoviária curva de concreto armado já em serviço. E apresenta os primeiros resultados da pesquisa com a portadora L1 do sistema GPS e dados gravados com taxa de 100 Hz, no monitoramento do vão central de ponte de concreto de pequeno porte situada sobre o Rio Jaguari, na cidade de Extrema, divisa entre os Estados de Minas Gerais e São Paulo. O desafio reside no fato de que estruturas como estas -pontes de concreto de pequeno e médio porte -respondem pela grande maioria das obras de arte da malha rodoviária brasileira e por serem