Marine Target Detection Using Dual-polarimetric SAR Imagery

In this study,we provide a summary of research advances in the field of maritime target detection using DP(dualpolarimetric)SAR(Synthetic Aperture Radar)imagery,accomplished during the European and China collaboration in the framework of the Dragon-4 program ID 32235.The main innovative contribution is twofold:(1)We addressed ship detection proposing an improved GP-PNF(Geometrical Perturbation-Polarimetric Notch Filter),termed as IGP-PNF,that is characterized by a new feature vector that includes three new scattering features;(2)We addressed oil platform detection by contrasting singlepolarization SAR methods with polarimetric ones in order to quantify the extra-benefit carried on polarimetric information.The proposed theoretical framework is tested against actual multi-polarization SAR data.In particular,ship detection methods are verified against a Sentinel-1 SAR scene where a large number of ships is present;while,oil platform detection is discussed using Terra SAR-X SAR data.Experimental analysis shows that:(1)The IGP-PNF method performs best in terms of clutter-to-target ratio;(2)Coherent polarimetric information significantly outperforms single-polarization SAR measurements in highlighting targets in challenging cases.

SAR Azimuth Cut-off to Estimate Wind Speed under High Wind Regimes

In this study,the azimuth cut-off method,typically used for SAR moderate wind speed estimation purposes,is analyzed under high wind regimes.Firstly,the importance of the pixel spacing,the size of the boxes selected for Synthetic Aperture Radar(SAR)image partitioning and the image texture in terms of homogeneities are discussed by considering their influence on the azimuth cut-off(λc)estimation.Secondly,a quality control analysis of the reliability ofλc is carried out by evaluating the distance between the autocorrelation functions(ACF)and their correspondent fittings.This analysis points out the importance of filtering out the unreliable and unfeasibleλc values in order to improve the wind speed estimation.The quality control procedure is based on a x2 test,applied on a large Sentinel-1 A dataset.The soundness of the test is verified by an increment in terms of correlation betweenλc estimations and wind speed values.This approach is,then,applied under high wind regimes,i.e.,tropical cyclones.

Fluid dynamic and thermal comfort analysis in an actual operating room with unidirectional airflow system

Air velocity and temperature distributions inside operating rooms (ORs) play a crucial role to reduce the risk of infections and to ensure adequate comfort conditions for patient and medical staff. In this work, the authors have developed a three-dimensional thermo-fluid dynamic model to simulate airflow and thermal comfort in an actual OR equipped with High-Efficiency Particulate Air (HEPA) filters. The model takes into account the presence of surgical lights, people and equipment within the room. An experimental campaign is carried out inside the actual OR to measure velocity and temperature, to be employed as boundary conditions for the numerical model. The experimental data have also been used to validate the numerical results. The validated model has been used to analyze the effects of human shape, thermal boundary conditions and buoyancy forces on the main thermal and fluid dynamic quantities in the OR. The thermal comfort is evaluated based on Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD) indices. The results prove that the present experimental-numerical approach is useful to analyze and improve the thermal comfort conditions for medical staff and patient.