Creat membership Creat membership
Sign in

Forgot password?

Confirm
  • Forgot password?
    Sign Up
  • Confirm
    Sign In
home > search

Now showing items 1 - 15 of 15

  • Estimation filtering for Deep Water Navigation

    Costanzi, Riccardo   Fenucci, Davide   Caiti, Andrea   Micheli, Michele   Vermeij, Arjan   Tesei, Alessandra   Munafo, Andrea  

    The navigation task for Unmanned Underwater Vehicles is made difficult in a deep water scenario because of the lack of bottom lock for Doppler Velocity Log (DVL). This is due to the operating altitude that, for this kind of applications, is typically greater than the sensor maximum range. The effect is that the velocity measurements are biased by sea currents resulting in a rapidly increasing estimation error drift. The solution proposed in this work is based on a distributed, cooperative strategy strongly relying on an acoustic underwater network. According to the distributed philosophy, an instance of a specifically designed navigation filter (named DWNF - Deep Water Navigation Filter) is executed by each vehicle. Each DWNF relies on different Extended Kalman Filters (EKFs) running in parallel on-board: one for own navigation state estimation (AUV-EKF), the other ones for the navigation state of the remaining assets (Asset-EKF). The AUV-EKF is designed to simultaneously estimate the vehicle position and the sea current for more reliable predictions. The DWNF builds in real-time a database of past measurements and estimations; in this way it can correctly deal with delayed information. An outlier detection and rejection policy based on the Mahalanobis distance associated to each measurement is implemented. The experimental validation of the proposed approach took place in a deep water scenario during the Dynamic Mongoose'17 exercise off the South coast of Iceland (June-July 2017); preliminary analysis of the results is presented. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.
    Download Collect
  • Cooperative robotic networks for underwater surveillance: an overview

    Ferri, Gabriele   Munafo, Andrea   Tesei, Alessandra   Braca, Paolo   Meyer, Florian   Pelekanakis, Konstantinos   Petroccia, Roberto   Alves, Joao   Strode, Christopher   LePage, Kevin  

    Underwater surveillance has traditionally been carried out by means of surface and undersea manned vessels equipped with advanced sensor systems. This approach is often costly and manpower intensive. Marine robotics is an emerging technological area that enables the development of advanced networks for underwater surveillance applications. In contrast with the use of standard assets, these advanced networks are typically composed of small, low-power, and possibly mobile robots, which have limited endurance, processing and wireless communication capabilities. When deployed in a region of interest, these robots can cooperatively form an intelligent network achieving high performance with significant features of scalability, adaptability, robustness, persistence and reliability. Such networks of robots can be the enabling technology for a wide range of applications in the maritime domain. However, they also introduce new challenges for underwater distributed sensing, data processing and analysis, autonomy and communications. The main thrust of this study is to review the underwater surveillance scenario within a framework of four research areas: (i) underwater robotics, (ii) acoustic signal processing, (iii) tracking and distributed information fusion, and (iv) underwater communications networks. Progress in each of these areas as well as future challenges is presented.
    Download Collect
  • Survey on Serious Games Applied to Security, Safety and Crisis Management

    Tesei, Alessandra   Barbieri, Alessandra   Kessel, Ronald  

    This work reports the results of a survey recently conducted in the community of serious games applied to security, safety and crisis management. The survey aims at understanding user needs, available solutions and their possible weaknesses. (C) 2012 The Authors. Published by Elsevier B. V. Selection and/or peer-review under responsibility of the scientific programme committee of VS-Games 2012
    Download Collect
  • Mental health and coping strategies in families of children and young adults with muscular dystrophies

    Tesei, Alessandra   Nobile, Maria   Colombo, Paola   Civati, Federica   Gandossini, Sandra   Mani, Elisa   Molteni, Massimo   Bresolin, Nereo   D'Angelo, Grazia  

    Background Living with a progressive disease as muscular dystrophy (MD) can be challenging for the patient and the entire family from both emotional and practical point of view. We aimed to extend our previously published data about mental health in patients with MDs, also investigating coping profiles of both themselves and their parents. Furthermore, we wanted to verify whether psychological adaptation of patients can be predicted by coping strategies, taking also into account physical impairment, cognitive level and socioeconomic status. Methods 112 patients with MDs, aged 2-32 were included. Their emotional and behavioural features were assessed through parent- and self-report Achenbach System for Empirically Based Assessment questionnaires and Strength and Difficulties Questionnaires. Development and Well-Being Assessment or Autism Diagnostic Observation Schedule were administered to confirm suspected diagnoses. Coping profile of both parents and patients was assessed through the self-administered New Italian Version of the Coping Orientation to the Problems Experienced questionnaire and its relationship with emotional/behavioural outcome was examined in linear regression analyses. Results High prevalence of intellectual disability and autism spectrum disorders was confirmed in Duchenne MD. Despite the high rate of internalizing symptomatology, we did not report higher rate of psychopathological disorders compared to general population. Parents tend to rely more on positive reinterpretation and less on disengagement coping. Avoidance coping, whether used by parents or patients, and ID, predicted increased emotional/behavioural problems. Conclusions Psychosocial interventions should address problems of anxiety and depression that people with MDs frequently experience, even through fostering parents' and childrens' engagement coping over disengagement coping.
    Download Collect
  • Tank measurements of scattering from a resin-filled fiberglass spherical shell with internal flaws

    Tesei, Alessandra   Guerrini, Piero   Zampolli, Mario  

    This paper presents results of acoustic inversion and structural health monitoring achieved by means of low to midfrequency elastic scattering analysis of simple, curved objects, insonified in a water tank. Acoustic elastic scattering measurements were conducted between 15 and 100 kHz on a 60-mm-radius fiberglass spherical shell, filled with a low-shear-speed epoxy resin. Preliminary measurements were conducted also on the void shell before filling, and on a solid sphere of the same material as the filler. These data were used to estimate the constituent material parameters via acoustic inversion. The objects were measured in the backscatter direction, suspended at midwater, and insonified by a broadband directional transducer. From the inspection of the response of the solid-filled shell it was possible to detect and characterize significant inhomogeneities of the interior (air pockets), the presence of which were later confirmed by x-ray CT scan and ultrasound measurements. Elastic wave analysis and a model-data comparison study support the physical interpretation of the measurements. (C) 2008 Acoustical Society of America.
    Download Collect
  • Tank measurements of scattering from a resin-filled fiberglass spherical shell with internal flaws

    Tesei, Alessandra   Guerrini, Piero   Zampolli, Mario  

    This paper presents results of acoustic inversion and structural health monitoring achieved by means of low to midfrequency elastic scattering analysis of simple, curved objects, insonified in a water tank. Acoustic elastic scattering measurements were conducted between 15 and 100 kHz on a 60-mm-radius fiberglass spherical shell, filled with a low-shear-speed epoxy resin. Preliminary measurements were conducted also on the void shell before filling, and on a solid sphere of the same material as the filler. These data were used to estimate the constituent material parameters via acoustic inversion. The objects were measured in the backscatter direction, suspended at midwater, and insonified by a broadband directional transducer. From the inspection of the response of the solid-filled shell it was possible to detect and characterize significant inhomogeneities of the interior (air pockets), the presence of which were later confirmed by x-ray CT scan and ultrasound measurements. Elastic wave analysis and a model-data comparison study support the physical interpretation of the measurements. (C) 2008 Acoustical Society of America.
    Download Collect
  • HOS-based generalized noise pdf models for signal detection optimization

    Tesei, Alessandra   Regazzoni, Carlo S.  

    Download Collect
  • Effect of family structure and TPH2 G-703T on the stability of dysregulation profile throughout adolescence

    Nobile, Maria   Bianchi, Valentina   Monzani, Dario   Beri, Silvana   Bellina, Monica   Greco, Andrea   Colombo, Paola   Tesei, Alessandra   Caldirola, Daniela   Giorda, Roberto   Perna, Giampaolo   Molteni, Massimo  

    Background: Two different polymorphisms (TPH2 G-703T and 5-HTTLPR) involved in the serotonergic pathway have been reported to play a role, both alone and in interaction with the environment, in early and adult emotion regulation. As most of these studies are cross-sectional, we know little about the impact of these polymorphisms over time, particularly during adolescence. Methods: Because we were interested in the effects of these polymorphisms and environment (i.e., family structure) at different time-points on the emotional dysregulation profile, we performed a path analysis model in a general adolescent population sample of a five-year follow-up study. Results: We found a high stability of Dysregulation Profile problems independently from the examined allelic variants. We also found that early family structure directly influences the levels of dysregulation problems in early adolescence, both alone and in interaction with TPH2, suggesting the presence of a gene-environment interaction effect. Furthermore, we found that in adolescents homozygous for the TPH2 G allele, the effect of the early family structure remains active during late adolescence, albeit mediated by earlier emotional problems. Limitations: The high attrition rate, the use of only one source on behavioral problems of adolescents, and the focus on a single polymorphism in the investigated genes could limit the generalizability of the present results. Conclusions: These results suggest that early family structure could play a significant role in the development and maintenance of emotional and behavioral problems not only in early adolescence but also in late-adolescence, although this effect was mediated and moderated by behavioral and genetic variables. (C) 2015 Elsevier B.V. All rights reserved.
    Download Collect
  • Benchmark problems for acoustic scattering from elastic objects in the free field and near the seafloor

    Zampolli, Mario   Jensen, Finn B.   Tesei, Alessandra  

    Results from a workshop organized in 2006 to assess the state of the art in target scatter modeling are presented. The problem set includes free-field scenarios as well as scattering from targets that are proud, half-buried, or fully buried in the sediment. The targets are spheres and cylinders, of size O(1 m), which are insonified by incident plane waves in the low-frequency band 0.1-10 kHz. In all cases, the quantity of interest is the far-field target strength. The numerical techniques employed fall within three classes: (i) finite-element (FE) methods and (ii) boundary-element (BE) techniques, with different approaches to computing the far field via discretizations of the Helmholtz-Kirchhoff integral in each case, and (iii) semianalytical methods. Reference solutions are identified for all but one of the seven test problems considered. Overall, FE- and BE-based models emerge as those being capable of treating a wider class of problems in terms of target geometry, with the FE method having the additional advantage of being able to deal with complex internal structures without much additional effort. These capabilities are of value for the study of experimental scenarios, which can essentially be envisioned as variations of the problem set presented here.
    Download Collect
  • The Role of Omega-3 Fatty Acids in Developmental Psychopathology: A Systematic Review on Early Psychosis, Autism, and ADHD.

    Agostoni, Carlo   Nobile, Maria   Ciappolino, Valentina   Delvecchio, Giuseppe   Tesei, Alessandra   Turolo, Stefano   Crippa, Alessandro   Mazzocchi, Alessandra   Altamura, Carlo A   Brambilla, Paolo  

    In this systematic review, we will consider and debate studies that have explored the effects of omega-3 polyunsaturated fatty acids (PUFAs) in three major, and somehow related, developmental psychiatric disorders: Autism, Attention Deficit and Hyperactivity disorder and Psychosis. The impact of omega-3 PUFAs on clinical symptoms and, if possible, brain trajectory in children and adolescents suffering from these illnesses will be reviewed and discussed, considering the biological plausibility of the effects of omega-3 fatty acids, together with their potential perspectives in the field. Heterogeneity in study designs will be discussed in the light of differences in results and interpretation of studies carried out so far.=20
    Download Collect
  • The potential relevance of docosahexaenoic acid and eicosapentaenoic acid to the etiopathogenesis of childhood neuropsychiatric disorders

    Tesei, Alessandra   Crippa, Alessandro   Ceccarelli, Silvia Busti   Mauri, Maddalena   Molteni, Massimo   Agostoni, Carlo   Nobile, Maria  

    Download Collect
  • A computationally efficient finite element model with perfectly matched layers applied to scattering from axially symmetric objects

    Zampolli, Mario   Tesei, Alessandra   Jensen, Finn B.   Malm, Nils   Blottman, John B., III  

    A frequency-domain finite-element (FE) technique for computing the radiation and scattering from axially symmetric fluid-loaded structures subject to a nonsymmetric forcing field is presented. The Berenger perfectly matched layer (PML), applied directly at the fluid-structure interface, makes it possible to emulate the Sommerfeld radiation condition using FE meshes of minimal size. For those cases where the acoustic field is computed over a band of frequencies, the meshing process is simplified by the use of a wavelength-dependent rescaling of the PML coordinates. Quantitative geometry discretization guidelines are obtained from a priori estimates of small-scale structural wavelengths, which dominate the acoustic field at low to mid frequencies. One particularly useful feature of the PML is that it can be applied across the interface between different fluids. This makes it possible to use the present tool to solve problems where the radiating or scattering objects are located inside a layered fluid medium. The proposed technique is verified by comparison with analytical solutions and with validated numerical models. The solutions presented show close agreement for a set of test problems ranging from scattering to underwater propagation. (c) 2007 Acoustical Society of America.
    Download Collect
  • Computing the far field scattered or radiated by objects inside layered fluid media using approximate, Green's functions RID E-6554-2011

    Zampolli, Mario   Tesei, Alessandra   Canepa, Gaetano   Godin, Oleg A.  

    A numerically efficient technique is presented for computing the field radiated or scattered from three-dimensional objects embedded within layered acoustic media. The distance between the receivers and the object of interest is supposed to be large compared to the acoustic wavelength. The method requires the pressure and normal particle displacement on the surface of the object or on an arbitrary circumscribing surface, as an input, together with a knowledge of the layered medium Green's functions. The numerical integration of the full wave number spectral representation of the Green's functions is avoided by employing approximate formulas which are available in terms of elementary functions. The pressure and normal particle displacement on the surface of the object of interest, on the other hand, may be known by analytical or numerical means or from experiments. No restrictions are placed on the location of the object, which may lie above, below, or across the interface between the fluid media. The proposed technique is verified through numerical examples, for-which the near field pressure and the particle displacement are computed via a finite-element method. The results are compared to validated reference models, which are based on the full wave number spectral integral Green's function. (c) 2008 Acoustical Society of America.
    Download Collect
  • Behavioral and cognitive effects of docosahexaenoic acid in drug-naive children with attention-deficit/hyperactivity disorder:a randomized,placebo-controlled clinical trial

    Crippa, Alessandro   Tesei, Alessandra   Sangiorgio, Federica   Salandi, Antonio   Trabattoni, Sara   Grazioli, Silvia   Agostoni, Carlo   Molteni, Massimo   Nobile, Maria  

    This study aimed to investigate the efficacy of docosahexaenoic acid (DHA) dietary supplementation on behavior and cognition in school-aged, drug-naive children with attention-deficit/hyperactivity disorder (ADHD). A total of 50 participants with ADHD aged 7 to 14 were enrolled in a 6-month randomized, placebo-controlled clinical trial and received either DHA or placebo. The primary outcome measure was the change in the ADHD rating scale IV Parent Version-Investigator (ADHD-RS-IV) after 4 and 6months. Secondary outcome measures included Conners Parent Rating Scale-revised, other behavioral rating scales including quality of life and global functioning, and computerized cognitive tasks. Baseline assessment also addressed the blood fatty acids profile. No superiority of DHA supplement to placebo was observed on ADHD-RS-IV, the a priori primary outcome. DHA supplementation showed a significant, nonetheless quite small, effect on children's psychosocial functioning, emotional problems, and focused attention. Neither major nor minor adverse events were reported throughout the trial. This study shows that 6-month DHA supplementation has no beneficial effect on the symptoms of ADHD in school-aged, drug-naive children with an established diagnosis of ADHD. Nevertheless, the 6months treatment with supplemental DHA appears to have small positive effects on other behavioral and cognitive difficulties, which, in light of the absence of side-effects, could be reasonably followed up in future intervention studies. (https://clinicaltrials.gov/ct2/show/NCT01796262: The Effects of DHA on Attention Deficit and Hyperactivity Disorder (DADA)).
    Download Collect
  • [AIP HIGH FREQUENCY OCEAN ACOUSTICS: High Frequency Ocean Acoustics Conference - La Jolla, California (USA) (1-5 March 2004)] AIP Conference Proceedings - A High-Frequency Active Underwater Acoustic Barrier Experiment Using a Time Reversal Mirror; Model-Data Comparison

    Tesei, Alessandra  

    Download Collect
1

Contact

If you have any feedback, Please follow the official account to submit feedback.

Turn on your phone and scan

Submit Feedback