10 research outputs found

    Space-based Global Maritime Surveillance. Part I: Satellite Technologies

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    Maritime surveillance (MS) is crucial for search and rescue operations, fishery monitoring, pollution control, law enforcement, migration monitoring, and national security policies. Since the early days of seafaring, MS has been a critical task for providing security in human coexistence. Several generations of sensors providing detailed maritime information have become available for large offshore areas in real time: maritime radar sensors in the 1950s and the automatic identification system (AIS) in the 1990s among them. However, ground-based maritime radars and AIS data do not always provide a comprehensive and seamless coverage of the entire maritime space. Therefore, the exploitation of space-based sensor technologies installed on satellites orbiting around the Earth, such as satellite AIS data, synthetic aperture radar, optical sensors, and global navigation satellite systems reflectometry, becomes crucial for MS and to complement the existing terrestrial technologies. In the first part of this work, we provide an overview of the main available space-based sensors technologies and present the advantages and limitations of each technology in the scope of MS. The second part, related to artificial intelligence, signal processing and data fusion techniques, is provided in a companion paper, titled: "Space-based Global Maritime Surveillance. Part II: Artificial Intelligence and Data Fusion Techniques" [1].Comment: This paper has been submitted to IEEE Aerospace and Electronic Systems Magazin

    Function of bacteriophage G7C esterase tailspike in host cell adsorption.

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    Bacteriophages recognize and bind to their hosts with the help of receptor-binding proteins (RBPs) that emanate from the phage particle in the form of fibers or tailspikes. RBPs show a great variability in their shapes, sizes, and location on the particle. Some RBPs are known to depolymerize surface polysaccharides of the host while others show no enzymatic activity. Here we report that both RBPs of podovirus G7C - tailspikes gp63.1 and gp66 - are essential for infection of its natural host bacterium E. coli 4s that populates the equine intestinal tract. We characterize the structure and function of gp63.1 and show that unlike any previously described RPB, gp63.1 deacetylates surface polysaccharides of E. coli 4s leaving the backbone of the polysaccharide intact. We demonstrate that gp63.1 and gp66 form a stable complex, in which the N-terminal part of gp66 serves as an attachment site for gp63.1 and anchors the gp63.1-gp66 complex to the G7C tail. The esterase domain of gp63.1 as well as domains mediating the gp63.1-gp66 interaction is widespread among all three families of tailed bacteriophages.The work of the laboratory in the Winogradsky Institute was partially supported by Russian Science Foundation (RSF) grant #15–15‐0013

    Structural design of face fabrics and the core as a premise for compression behavior of 3D woven sandwich fabric

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    In this work, an experimental study on compression properties of two E-glass 3D woven fabrics, known as integrally woven sandwich fabrics, has been presented. Compression properties of 2D face fabrics and the core, as structural parts of integrally woven sandwich fabric, have also been investigated. Compression behavior of the samples (compressibility, compression work, and compressive resilience) was analyzed from the aspect of the weave design of face fabrics and the core structure (shape and density of the pile yarns). Results of the investigation showed that 8 shaped core structure, the greater surface density of the pile yarns, and the less compact structure of face fabrics ensure better compression properties of 3D fabrics. Specific weave design of face fabrics and the structure of the core significantly influence the behavior of 3D fabrics during successive increases, followed by a gradual decrease of pressure. During the loading of 3D woven structures, three regions of curves can clearly be seen compared to two regions which are registered at 2D face fabrics. Concerning 3D woven fabrics, the first region represents compression of the core, the second region is prolonged core compression and the third region refers to the simultaneous compression of pile yarns in the core and face fabrics. The density of pile yarns plays an important role in the region 1. In region 2, both the shape and density of the pile yarns are significant. Influence of the weave of face fabrics on compression behavior of 3D fabric can be noticed to a lesser extent in the region 2 and, especially in the region 3, where highly packed yarns assemblies are created
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