The recent access to GNSS (Global Navigation Satellite System) phase observations on smart devices, enabled by Google through its Android operating system, opens the possibility to apply precise ...positioning techniques using off-the-shelf, mass-market devices. The target of this work is to evaluate whether this is feasible, and which positioning accuracy can be achieved by relative positioning of the smart device with respect to a base station. Positioning of a Google/HTC Nexus 9 tablet was performed by means of batch least-squares adjustment of L1 phase double-differenced observations, using the open source goGPS software, over baselines ranging from approximately 10 m to 8 km, with respect to both physical (geodetic or low-cost) and virtual base stations. The same positioning procedure was applied also to a co-located u-blox low-cost receiver, to compare the performance between the receiver and antenna embedded in the Nexus 9 and a standard low-cost single-frequency receiver with external patch antenna. The results demonstrate that with a smart device providing raw GNSS phase observations, like the Nexus 9, it is possible to reach decimeter-level accuracy through rapid-static surveys, without phase ambiguity resolution. It is expected that sub-centimeter accuracy could be achieved, as demonstrated for the u-blox case, if integer phase ambiguities were correctly resolved.
This paper deals with the problem of geodetic monitoring of structures by means of permanent GNSS stations, with a focus on a specific project of monitoring a bridge by a small network of three ...stations. What is peculiar about this paper is that the stations used are endowed with low-cost GNSS receivers, and the data treated continuously cover a time-span of more than 4 years. The monitoring service GeoGuard, at work on the project, has proved to be reliable in terms of both hardware and software. The results display almost uniform accuracy at less than the 1 mm level for daily adjusted coordinates and at the level of ∼1–2 mm for hourly solutions. After a short review on the basics of positioning by GNSS phase observations, the error of the estimated coordinates is discussed in detail, and a procedure of warning/alarm is described. The experience in terms of hardware and software employed is then presented together with the results, which are mostly displayed in graphical form and with a few tables.
A prototype of a low-cost GNSS (Global Navigation Satellite System) monitoring system was installed on a deep-seated landslide in north-western Slovenia to test its performance under field ...conditions. The system consists of newly developed GNSS stations based on low-cost, dual-frequency receivers and open-source GNSS processing software. It automatically receives GNSS data and transmits them over the Internet. The system processes the data server-side and makes them available to the end user via a web portal. The detected surface displacements were evaluated through a comparison with the network of classic geodetic measurements. The results of a nine-month monitoring period using seven GNSS stations provided a detailed insight into the spatial and temporal pattern of deep-seated landslide surface movements. The displacement data were correlated with precipitation measurements at the site to reveal how different parts of the landslide react to rainfall. These data form the basis for the further development of an early-warning system which will help to manage the risk the landslide poses to the local population and infrastructure.
Dams are one of the most important engineering works of the current human society, and it is crucial to monitor and obtain analytical data to log their conditions, predict their behavior and, ...eventually, receive early warnings for planning interventions and maintenance activities. In this context, GNSS-based point displacement monitoring is nowadays a consolidated technique that is able to provide daily millimeter level accuracy, even with less sophisticated and less expensive single-frequency equipment. If properly designed, daily records of such monitoring systems produce time series that, when long enough, allow for an accurate reconstruction of the geometrical deformation of the structure, thus guiding semi-automatic early warning systems. This paper focuses on the procedure for the GNSS time series processing with a statistical approach. In particular, real-world times series collected from a dam monitoring test case are processed as an example of data filtering. A remove–restore technique based on a collocation approach is applied here. Basically, it consists of an initial deterministic modeling by polynomials and periodical components through least squares adjustment and Fourier transform, respectively, followed by a stochastic modeling based on empirical covariance estimation and a collocation approach. Filtered time series are interpreted by autoregressive models based on environmental factors such as air or water temperature and reservoir water level. Spatial analysis is finally performed by computing correlations between displacements of the monitored points, as well as by visualizing the overall structure deformation in time. Results positively validate the proposed data processing workflow, providing useful hints for the implementation of automatic early warning systems in the framework of structural monitoring based on continuous displacement measurements.
In the frame of deformation monitoring of structures, infrastructures and natural hazards, in this paper several examples are provided, that demonstrate how GNSS observations, even if taken by low ...cost receivers, are competitive in terms of accuracy with classic techniques. Moreover GNSS observations are able to provide a continuous determination of the position of N points in time, in a fully automated way, interconnecting points that are not visible each other, in all weather conditions. This work presents how a low cost GNSS monitoring system can be designed and implemented, both in terms of hardware and software solutions. Then the analysis of GNSS data is shown, describing the consecutive steps of preprocessing, processing and validation of the results. Because deformation monitoring basically means detecting anomalous changes in the time series of each GNSS station, an efficient alarm system is designed and described. In the end ten basic requirements are identified, which guarantee that the deformation monitoring performed with GNSS can be effective and convenient.
In the frame of deformation monitoring of structures, infrastructures and natural hazards, in this paper several examples are provided, that demonstrate how GNSS observations, even if taken by low ...cost receivers, are competitive in terms of accuracy with classic techniques. Moreover GNSS observations are able to provide a continuous determination of the position of N points in time, in a fully automated way, interconnecting points that are not visible each other, in all weather conditions. This work presents how a low cost GNSS monitoring system can be designed and implemented, both in terms of hardware and software solutions. Then the analysis of GNSS data is shown, describing the consecutive steps of preprocessing, processing and validation of the results. Because deformation monitoring basically means detecting anomalous changes in the time series of each GNSS station, an efficient alarm system is designed and described. In the end ten basic requirements are identified, which guarantee that the deformation monitoring performed with GNSS can be effective and convenient.
GNSS permanent networks materialize and distribute the reference frame. The continuous monitoring of the stations involves the daily adjustment of the network in order to obtain the daily estimates ...of the coordinates. Moreover, the resulting time series should be analyzed to estimate the time models of the coordinates. Many tasks precede and follow the raw data processing in order to prepare the data and to analyze the results: several tasks are purely technical, but some of them involve methodological choices and numerical analyses. A complete automation of all the processing flow is clearly useful in the network management. During the last 7 years, we have been involved in the monitoring of different permanent networks that are heterogeneous in the spatial scale, the number of stations, and the scope. The raw data processing is performed by the Bernese GPS Software 5.0. To automate all the pre-processing tasks and the post-processing analyses, a software package has been implemented: it is called RegNet, is based on C and Matlab source code, and will be freely distributed at the time of the paper publication. At first, the paper describes the RegNet structure and its output reports. One example of RegNet application to a permanent network of about 200 stations, based on more than 1 year of data, is presented. The adjustment of a large network requires its splitting into small subnetworks, the separate adjustment of all the subnetworks, and finally, the recombination of the solutions by the so-called Normal Equation Stacking. In the second part of the paper, different network splitting strategies are compared from a methodological point of view. All these strategies have been implemented in RegNet. A quite realistic case study, based on about 100 stations of the European Permanent Network, 1 month of data, is presented, and the results are compared.
Melatonin (MT) is a molecule of paramount importance in all living organisms, due to its presence in many biological activities, such as circadian (sleep-wake cycle) and seasonal rhythms ...(reproduction, fattening, molting, etc.). Unfortunately, it suffers from poor solubility and, to be used as a drug, an appropriate transport vehicle has to be developed, in order to optimize its release in the human tissues. As a possible drug-delivery system, β-cyclodextrin (βCD) represents a promising scaffold which can encapsulate the melatonin, releasing when needed. In this work, we present a computational study supported by experimental IR spectra on inclusion MT/βCD complexes. The aim is to provide a robust, accurate and, at the same time, low-cost methodology to investigate these inclusion complexes both with static and dynamic simulations, in order to study the main actors that drive the interactions of melatonin with β-cyclodextrin and, therefore, to understand its release mechanism.
Heart failure (HF) prevalence is increasing among the aging population, and the mortality rate remains unacceptably high despite improvements in therapy. Myocardial ischemia (MI) and, consequently, ...ischemia/reperfusion injury (IRI), are frequently the basis of HF development. Therefore, cardioprotective strategies to limit IRI are mandatory. Nanocarriers have been proposed as alternative therapy for cardiovascular disease. Controlled reoxygenation may be a promising strategy. Novel nanocarriers, such as cyclic nigerosyl-nigerose (CNN), can be innovative tools for oxygen delivery in a controlled manner. In this study we analyzed new CNN-based formulations as oxygen nanocarriers (O
-CNN), and compared them with nitrogen CNN (N
-CNN). These different CNN-based formulations were tested using two cellular models, namely, cardiomyoblasts (H9c2), and endothelial (HMEC) cell lines, at different concentrations. The effects on the growth curve during normoxia (21% O
, 5% CO
and 74% N
) and their protective effects during hypoxia (1% O
, 5% CO
and 94% N
) and reoxygenation (21% O
, 5% CO
and 74% N
) were studied. Neither O
-CNN nor N
-CNN has any effect on the growth curve during normoxia. However, O
-CNN applied before hypoxia induces a 15-30% reduction in cell mortality after hypoxia/re-oxygenation when compared to N
-CNN. O
-CNN showed a marked efficacy in controlled oxygenation, which suggests an interesting potential for the future medical application of soluble nanocarrier systems for MI treatment.
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