MONITORING AND EVALUATION OF A LONG-SPAN RAIWAY BRIDGE USING SENTINEL-1 DATA

This paper is focused on displacement monitoring of a bridge, which is one of the key aspects of its structural health monitoring. A simplified Persistent Scatterer Interferometry (PSI) approach is used to monitor the displacements of the Nanjing Dashengguan Yangtze River High-speed Railway Bridge (China). This bridge is 1272 m long and hosts a total of 6 railway lines. The analysis was based on a set of twenty-nine Sentinel-1A images, acquired from April 2015 to August 2016. A dense set of measurement points were selected on the bridge. The PSI results show a maximum longitudinal displacement of 150 mm, on each side of the bridge. The displacements are strongly correlated with the temperature, showing that they are due to thermal expansion. Using the PSI results, the Coefficient of Thermal Expansion (CTE) of the whole bridge was estimated. The result agrees well with the CTE of the bridge materials. Using a regression model, the PSI-measured displacements were compared with in-situ measurements. The paper proposes a procedure to assess the performance of the movable bearings of the bridge, which is based on the PSI measurements

Sentinel-1A/B imagery for terrain deformation monitoring: a strategy for Atmospheric Phase Screening (APS) estimation

This work focus on terrain deformation monitoring by means of C-band Synthetic Aperture Radar (SAR) Sentinel-1A/B imagery exploiting the Persistent Scatterer Interferometry (PSI) technique. The deformation monitoring strategy described in this article is related to a specific monitoring scenario where a relatively small urban area is potentially affected by deformation and its surroundings are stable. In the case study considered in this work, the scenario corresponds to an area of potential subsidence induced by underground water pumping covering an area of interest with a radius of approximately 1 km. The proposed monitoring strategy takes advantage of the specific scenario at hand and, in particular, of the availability of stable areas in the vicinity of the area potentially affected by ground deformation, to estimate the Atmospheric Phase Screen (APS), i.e. signal propagation delay caused by the Earth's atmosphere, in an attempt to minimize the underestimation of the deformation rate

Histological study of the sex-change in the skunk clownfish <i>Amphiprion akallopisos</i>

Sex change in the protandrous fish Amphiprion akallopisos Bleeker, 1853 (F.Pomacentridae) has been analysed. Experiments consisted of placing males together after being separated from their mates, and observe changes in gonad histology at different periods, in order to identify signs of the sex change process. The presence of a first invagination on the male gonad wall, and the observation of the first cortical alveoli oocytes as an indication of the beginning of the vitellogenesis process, was the first symptom of the sex change, which has been detected after 18 days in one of the males. Period needed for the sex changing process was size independent. The process by which wall invagination is converted into ovarian lumen in the future mature ovary is also described

ANALYSIS OF X-BAND VERY HIGH RESOLUTION PERSISTENT SCATTERER INTERFEROMETRY DATA OVER URBAN AREAS

Persistent Scatterer Interferometry (PSI) is a satellite-based Synthetic Aperture Radar (SAR) remote sensing technique used to measure and monitor land deformation from a stack of interferometric SAR images. This work concerns X-band PSI and, in particular, PSI based on very high resolution (VHR) StripMap CosmoSkyMed and TerraSAR-X SAR imagery. In fact, it mainly focuses on the technical aspects of deformation measurement and monitoring over urban areas. A key technical aspect analysed in this paper is the thermal expansion component of PSI observations, which is a result of temperature differences in the imaged area between SAR acquisitions. This component of PSI observations is particularly important in the urban environment. This is an interesting feature of PSI, which can be surely used to illustrate the high sensitivity of X-band PSI to very subtle displacements. Thermal expansion can have a strong impact on the PSI products, especially on the deformation velocity maps and deformation time series, if not properly handled during the PSI data processing and analysis, and a comprehensive discussion of this aspect will be provided in this paper. The importance of thermal expansion is related to the fact that the PSI analyses are often performed using limited stacks of images, which may cover a limited time period, e.g. several months only. These two factors (limited number of images and short period) make the impact of a non-modelled thermal expansion particularly critical. This issue will be illustrated considering different case studies based on TerraSAR-X and CosmoSkyMed PSI data. Besides, an extended PSI model which alleviates this problem will be described and case studies from the Barcelona metropolitan area will demonstrate the effectiveness of the proposed strategy

Formulación de estrategias de marketing mix a partir del estudio del comportamiento del consumidor de leche en la ciudad de Riobamba/Formulation of marketing mix strategies based on the study of milk consumer behavior in the city of Riobamba

El estudio económico de la conducta del consumidor supone teorías de enfoque positivista y normativo. En este contexto las decisiones de consumo se basan no siempre en un modelo racional, considerando además factores de tipo emocional, experiencias que determinan la decisión de compra. El objetivo de este artículo fue formular estrategias de marketing mix a partir del estudio del comportamiento del consumidor de leche en la ciudad de Riobamba. La metodología utilizada se fundamentó en un estudio cuasi experimental que tomó como base un modelo predeterminado que sirvió para diseñar una encuesta que permitiese identificar y evaluar variables determinantes en la conducta de los consumidores. La investigación permitió determinar las preferencias de marcas de leche, nivel de aceptación del precio, tipo de empaque, medios de comunicación y frecuencia de consumo. Los resultados de la investigación permitieron formular estrategias que contribuyen a incentivar el consumo de leche en la población local. The economic study of consumer behavior supposes theories of positivist and normative approach. In this context, consumer decisions are not always based on a rational model, considering factors of an emotional nature, experiences that determine the purchase decision. The objective of this article was to formulate marketing mix strategies based on the study of milk consumer behavior in the city of Riobamba. The methodology used was based on a quasi-experimental study that took as a basis a predetermined model that served to design a survey that would identify and evaluate determinant variables in the behavior of consumers. The investigation allowed to determine the preferences of milk brands, level of acceptance of the price, type of packaging, means of communication and frequency of consumption. The results of the research allowed to formulate strategies that contribute to encourage the consumption of milk in the local population. Palabras clave: comportamiento del consumidor, neuroeconomía, marketing mix. Keywords: consumer behavior, neuroeconomics, marketing mix

Mapping and monitoring geomorphological processes in mountainous areas using PSI data: Central Pyrenees case study

In this paper the Stable Point Network technique, an established Persistent Scatterer InSAR (PSI) technique, (SPN), has been applied for the first time to the analysis of several geomorphological processes present in the Gállego river basin (Central Pyrenees, Spain). The SPN coherence based approach has been used to process three different SAR images datasets covering two temporal periods: 1995 to 2001 and 2001 to 2007. This approach has permitted the detection of more than 40 000 natural ground targets or Persistent Scatterers (PSs) in the study area, characterised by the presence of vegetation and a low urban density. Derived displacement maps have permitted the detection and monitoring of deformations in landslides, alluvial fans and erosive areas. In the first section, the study area is introduced. Then the specifics of the SPN processing are presented. The deformation results estimated with the SPN technique for the different processed datasets are compared and analysed with previous available geo-information. Then several detailed studies are presented to illustrate the processes detected by the satellite based analysis. In addition, a comparison between the performance of ERS and ENVISAT satellites with terrestrial SAR has demonstrates that these are complementary techniques, which can be integrated in order to monitor deformation processes, like landslides, that over the same monitoring area may show very different ranges of movement. The most relevant conclusions of this work are finally discussed

A persistent scatterer interferometry procedure to monitor urban subsidence

This paper describes a Persistent Scatterer Interferometry procedure for deformation monitoring. Its more original part concerns an approach to estimate the atmospheric phase component. The procedure can be used to monitor deformation areas that are relatively small and are surrounded by stable areas. The proposed procedure is described step by step. The procedure can be applied using SAR data coming from different sensors. However, in this work we discuss results obtained using Sentinel-1 data. A case study is described, where the deformation is caused by water pumping associated with construction works. In this case study, a stack of 78 Sentinel-1 images were analysed. The main part of the paper concerns the analysis of the atmospheric component. A comprehensive characterization of this component is first described, considering the original non-filtered phases. This is followed by the characterization of the residual filtered phases. This analysis highlights the goodness of the proposed procedure. This is further confirmed by the analysis of two deformation time series. The procedure can work with any type of deformation phenomena, provided that its spatial extension is sufficiently small

Satellite interferometric data for landslide intensity evaluation in mountainous regions

Multi-Temporal Interferometric Synthetic Aperture Radar (MTInSAR) data offer a valuable support to landslide mapping and to landslide activity estimation in mountain environments, where in situ measures are sometimes difficult to gather. Nowadays, the interferometric approach is more and more used for wide-areas analysis, providing useful information for risk management actors but at the same time requiring a lot of efforts to correctly interpret what satellite data are telling us. In this context, hot-spot-like analyses that select and highlight the fastest moving areas in a region of interest, are a good operative solution for reducing the time needed to inspect a whole interferometric dataset composed by thousands or millions of points. In this work, we go beyond the concept of MTInSAR data as simple mapping tools by proposing an approach whose final goal is the quantification of the potential loss experienced by an element at risk hit by a potential landslide. To do so, it is mandatory to evaluate landslide intensity. Here, we estimate intensity using Active Deformation Areas (ADA) extracted from Sentinel-1 MTInSAR data. Depending on the localization of each ADA with respect to the urban areas, intensity is derived in two different ways. Once exposure and vulnerability of the elements at risk are estimated, the potential loss due to a landslide of a given intensity is calculated. We tested our methodology in the Eastern Valle d'Aosta (north-western Italy), along four lateral valleys of the Dora Baltea Valley. This territory is characterized by steep slopes and by numerous active and dormant landslides. The goal of this work is to develop a regional scale methodology based on satellite radar interferometry to assess the potential impact of landslides on the urban fabric