Design and Performance Estimation of a Photonic Integrated Beamforming Receiver for Scan-On-Receive Synthetic Aperture Radar

Synthetic aperture radar is a remote sensing technology finding applications in a wide range of fields, especially related to Earth observation. It enables a fine imaging that is crucial in critical activities, like environmental monitoring for natural resource management or disasters prevention. In this picture, the scan-on-receive paradigm allows for enhanced imaging capabilities thanks to wide swath observations at finer azimuthal resolution achieved by beamforming of multiple simultaneous antenna beams. Recently, solutions based on microwave photonics techniques demonstrated the possibility of an efficient implementation of beamforming, overcoming some limitations posed by purely electronic solutions, offering unprecedented flexibility and precision to RF systems. Moreover, photonics-assisted RF beamformers can nowadays be realized as integrated circuits, with reduced size and power consumption with respect to digital beamforming approaches. This paper presents the design analysis and the challenges of the development of a hybrid photonic-integrated circuit as the core element of an X-band scan-on-receive spaceborne synthetic aperture radar. The proposed photonic-integrated circuit synthetizes three simultaneous scanning beams on the received signal, and performs the frequency down-conversion, guaranteeing a compact 15 cm2-form factor, less than 6 W power consumption, and 55 dB of dynamic range. The whole photonics-assisted system is designed for space compliance and meets the target application requirements, representing a step forward toward a deeper penetration of photonics in microwave applications for challenging scenarios, like the observation of the Earth from space

Thoracoscopic-assisted repair of a bochdalek hernia in an adult: a case report

<p>Abstract</p> <p>Introduction</p> <p>Bochdalek hernia is a congenital defect of the diaphragm that usually presents in the neonatal period with life-threatening cardiorespiratory distress. It is rare for Bochdalek hernias to remain silent until adulthood. Once a Bochdalek hernia has been diagnosed, surgical treatment is necessary to avoid complications such as perforation and necrosis.</p> <p>Case presentation</p> <p>We present a 17-year-old Japanese boy with left-upper-quadrant pain for two months. Chest radiography showed an elevated left hemidiaphragm. Computed tomography revealed a congenital diaphragmatic hernia. The spleen and left colon had been displaced into the left thoracic cavity through a left posterior diaphragmatic defect. We diagnosed a Bochdalek hernia. Surgical treatment was performed via a thoracoscopic approach. The boy was placed in the reverse Trendelenburg position and intrathoracic pressure was increased by CO₂gas insufflations. This is a very useful procedure for reducing herniated contents and we were able to place the herniated organs safely back in the peritoneal cavity. The diaphragmatic defect was too large to close with thoracoscopic surgery alone. Small incision thoracotomy was required and primary closure was performed. His postoperative course was uneventful and there has been no recurrence of the diaphragmatic hernia to date.</p> <p>Conclusion</p> <p>Thoracoscopic surgery, performed with the boy in the reverse Trendelenburg position and using CO₂gas insufflations in the thoracic cavity, was shown to be useful for Bochdalek hernia repair.</p

Open Carbon Frameworks (OCF) - a Potential Solution for Hydrogen Storage

International audienceOne of potential perspectives for clean fueling of cars is the use of hydrogen-powered fuel cells. A major challenge in the massif implementation of hy-drogen-fuelled vehicles still consist in designing hydrogen storage systems that are reversible, light, cheap and able of delivering a driving range of few hundreds of kilometers. Between the possible hydrogen adsorbents carbon porous structures with locally slit-shaped pore geometry remain the most promising ones.From the analysis of the computer simulations of adsorption properties of the new structures, a rich spectrum of relations between structural characteristics of OCFs and ensuing hydrogen adsorption (structure-function relations) emerges: (i) storage capacities higher than in slit-shaped pores can be obtained by fragmentation/truncation of graphene sheets, which creates additional surface areas (with respect to infinite graphene sheets), carried mainly by edge sites; ii) for OCFs with a ratio of in-plane to edge sites approximately equal 1 and surface areas of 3800-6500 m2/g, we found at 77 K record maximum excess adsorption of 75-85 g H2/kg C, and record storage capacity of 100-260 g H2/kg C (at 100 bar); (iii) additional increase of hydrogen uptake could potentially be achieved by chemical substitution and/or intercalation of OCF structures, in order to increase the energy of adsorption. In consequence we conclude that OCF structures, if synthesized, will allow the hydrogen uptake at the level required for vehicular applications

Open Carbon Frameworks (OCF) – a potential solution for hydrogen storage”,

International audience-

Open Carbon Frameworks (OCF) - a Potential Solution for Hydrogen Storage

International audienceOne of potential perspectives for clean fueling of cars is the use of hydrogen-powered fuel cells. A major challenge in the massif implementation of hy-drogen-fuelled vehicles still consist in designing hydrogen storage systems that are reversible, light, cheap and able of delivering a driving range of few hundreds of kilometers. Between the possible hydrogen adsorbents carbon porous structures with locally slit-shaped pore geometry remain the most promising ones.From the analysis of the computer simulations of adsorption properties of the new structures, a rich spectrum of relations between structural characteristics of OCFs and ensuing hydrogen adsorption (structure-function relations) emerges: (i) storage capacities higher than in slit-shaped pores can be obtained by fragmentation/truncation of graphene sheets, which creates additional surface areas (with respect to infinite graphene sheets), carried mainly by edge sites; ii) for OCFs with a ratio of in-plane to edge sites approximately equal 1 and surface areas of 3800-6500 m2/g, we found at 77 K record maximum excess adsorption of 75-85 g H2/kg C, and record storage capacity of 100-260 g H2/kg C (at 100 bar); (iii) additional increase of hydrogen uptake could potentially be achieved by chemical substitution and/or intercalation of OCF structures, in order to increase the energy of adsorption. In consequence we conclude that OCF structures, if synthesized, will allow the hydrogen uptake at the level required for vehicular applications