A priori knowledge-free fast positioning approach for BeiDou receivers

A Global Navigation Satellite System (GNSS) receiver usually needs a sufficient number of full pseudorange measurements to obtain a position solution. However, it is time-consuming to acquire full pseudorange information from only the satellite broadcast signals due to the navigation data features of GNSS. In order to realize fast positioning during a cold or warm start in a GNSS receiver, the existing approaches require an initial estimation of position and time or require a number of computational steps to recover the full pseudorange information from fractional pseudoranges and then compute the position solution. The BeiDou Navigation Satellite System (BDS) has a unique constellation distribution and a fast navigation data rate for geostationary earth orbit (GEO) satellites. Taking advantage of these features, we propose a fast positioning technique for BDS receivers. It simultaneously processes the full and fractional pseudorange measurements from the BDS GEOs and non-GEOs, respectively, which is faster than processing all full measurements. This method resolves the position solution and recovers the full pseudoranges for non-GEOs simultaneously within 1 s theoretically and does not need an estimate of the initial position. Simulation and real data experiments confirm that the proposed technique completes fast positioning without a priori position and time estimation, and the positioning accuracy is identical with the conventional single-point positioning approach using full pseudorange measurements from all available satellites

Nanoparticle-Based Vaccines against Zoonotic Viruses: A Review

Vaccines are the most promising tools for maintaining public health. Most emerging human infectious diseases are caused by viruses originating from an animal reservoir via zoonotic transmission. Therefore, zoonotic virus spillover and spread in humans have become global health threats. Nanoparticle-based vaccines are ideal for antigen delivery, as adjuvants, and as viral structure mimics. Nanoparticles benefit vaccine design and are utilized to protect the antigen cargo, and increase the immunogenicity and efficacy. Therefore, nanoparticle vaccines are a novel method of immunization by which optimal immune responses are elicited. Herein we review current approaches in the development of nanoparticle vaccines and highlight the role of nanoparticle vaccines against zoonotic viral diseases