Data and Service Security of GNSS Sensors Integrated with Cryptographic Module

Navigation and positioning are of increasing importance because they are becoming a new form of infrastructure. To ensure both development and security, this study designed a technical innovation structure to upgrade the GNSS (Global Navigation Satellite System) data transmission and real-time differential correction service system and proposed a new multiple cryptographic fusion algorithm to achieve the encryption and decryption of GNSS data and services. First, a GNSS station encrypts GNSS data with an encryption key and obtains a public key from a GNSS data center to encrypt the GNSS data encryption key. After that, identity authentication of a GNSS station is carried out, and an SSL VPN is established between the GNSS station and a GNSS data center before GNSS data are transmitted to the GNSS data center. Then, the GNSS data center decrypts the received GNSS data. The process of an intelligent terminal for real-time differential corrections is similar to that of the GNSS station and the GNSS data center. A GNSS sensor integrated with a cryptographic module was developed to validate the structure in an open environment. The results showed that the developed GNSS sensor was successful in encrypting the data, and the GNSS data center was able to decrypt the data correctly. For the performance test, a cryptography server was able support the requirements of GNSS applications. However, a cryptography server was optimal in supporting 40~50 GNSS stations simultaneously, whereas a cluster was suggested to be configured if the number of GNSS stations was more than 60. In conclusion, the method was able to ensure the validity, confidentiality, integrity, and non-repudiation of GNSS data and services. The proposed upgrading technology was suitable for coordinating GNSS development and security

Resolving stellar surfaces with binary gravitational microlensing

Binary gravitational microlensing has demonstrated excellent prospects for studying the surface brightness distribution of stars. In this work we study the extended-source eects that aect the amplication of the source ux. We identify regions in the geometry that are sensitive to the extended source and nd previously unknown areas between facing cusps of multi-part caustics. We nd out that the probability of detecting the extended-source eect can be as much as two times higher than the probability of observing pure caustic crossing. We explore the chromaticity of binary microlensing and compare two classes of models of limb darkening. We describe spectral changes during binary microlensing and compare their amplitude to the point-lens case. Finally, we investigate the linear fold approximation and nd signicant residuals even in cases favorable for the method

Diabetes mellitus - complication of blood vessels.

All annotated unigenes. (XLS 29890 kb

Pressure-Induced Phase Transformation, Reversible Amorphization, and Anomalous Visible Light Response in Organolead Bromide Perovskite

Hydrostatic pressure, as an alternative of chemical pressure to tune the crystal structure and physical properties, is a significant technique for novel function material design and fundamental research. In this article, we report the phase stability and visible light response of the organolead bromide perovskite, CH₃NH₃PbBr₃ (MAPbBr₃), under hydrostatic pressure up to 34 GPa at room temperature. Two phase transformations below 2 GPa (from <i>Pm</i>3̅<i>m</i> to <i>Im</i>3̅, then to <i>Pnma</i>) and a reversible amorphization starting from about 2 GPa were observed, which could be attributed to the tilting of PbBr₆ octahedra and destroying of long-range ordering of MA cations, respectively. The visible light response of MAPbBr₃ to pressure was studied by in situ photoluminescence, electric resistance, photocurrent measurements and first-principle simulations. The anomalous band gap evolution during compression with red-shift followed by blue-shift is explained by the competition between compression effect and pressure-induced amorphization. Along with the amorphization process accomplished around 25 GPa, the resistance increased by 5 orders of magnitude while the system still maintains its semiconductor characteristics and considerable response to the visible light irradiation. Our results not only show that hydrostatic pressure may provide an applicable tool for the organohalide perovskites based photovoltaic device functioning as switcher or controller, but also shed light on the exploration of more amorphous organometal composites as potential light absorber

Pressure-Induced Amorphization in Single-Crystal Ta₂O₅ Nanowires: A Kinetic Mechanism and Improved Electrical Conductivity

Pressure-induced amorphization (PIA) in single-crystal Ta₂O₅ nanowires is observed at 19 GPa, and the obtained amorphous Ta₂O₅ nanowires show significant improvement in electrical conductivity. The phase transition process is unveiled by monitoring structural evolution with <i>in situ</i> synchrotron X-ray diffraction, pair distribution function, Raman spectroscopy, and transmission electron microscopy. The first principles calculations reveal the phonon modes softening during compression at particular bonds, and the analysis on the electron localization function also shows bond strength weakening at the same positions. On the basis of the experimental and theoretical results, a kinetic PIA mechanism is proposed and demonstrated systematically that amorphization is initiated by the disruption of connectivity between polyhedra (TaO₆ octahedra or TaO₇ bipyramids) at the particular weak-bonding positions along the <i>a</i> axis in the unit cell. The one-dimensional morphology is well-preserved for the pressure-induced amorphous Ta₂O₅, and the electrical conductivity is improved by an order of magnitude compared to traditional amorphous forms. Such pressure-induced amorphous nanomaterials with unique properties surpassing those in either crystalline or conventional amorphous phases hold great promise for numerous applications in the future