Research Status and Trends of Indoor Positioning and Navigation Technology in China

As an essential component of future comprehensive Positioning,Navigation,and Timing(PNT)system,indoor positioning technology has extensive application demands,making it a focal point of attention in both academia and industry.This article comprehensively reviews the research status of indoor positioning technology in China,with a focus on highlighting representative achievements and application validations from major research institutions in recent years.It addresses the challenges and issues faced in promotion and application of large-scale,high-precision indoor positioning.Furthermore,a universal and seamless indoor-outdoor positioning system architecture is proposed,along with a technical roadmap and key technologies to achieve this architecture.Finally,an analysis and outlook on future technological trends are presented.

Underlying mechanism of protection from hypoxic injury seen with n-butanol extract of Potentilla anserine L. in hippocampal neurons

The alcohol and n-butanol extract of Potentilla anserine L. significantly protects myocardium from acute ischemic injury. However, its effects on rat hippocampal neurons and the mechanism of protection remain unclear. In this study, primary cultured hippocampal neurons from neonatal rats were incubated in 95% N2 and 5% CO2 for 4 hours. Results indicated that hypoxic injury decreased the viability of neurons, increased the expression levels of caspase-9 and caspase-3 mRNA, as well as cytochrome c, Caspase-9, and Caspase-3 protein. Pretreatment with 0.25, 0.062 5, 0.015 6 mg/mL n-butanol extract of Potentilla anserine L. led to a significant increase in cell viability. Expression levels of caspase-9 and caspase-3 mRNA, as well as cytochrome c, Caspase-9, and Caspase-3 protein, were attenuated. The neuroprotective effect of n-butanol extract of Potentilla anserine L. was equivalent to tanshinone IIA. Our data suggest that the n-butanol extract of Potentilla anserine L. could protect primary hippocampal neurons from hypoxic injury by deactivating mitochondrial cell death.

Differential protein expression in rat cortical astrocytes following fluid percussion injury Two-dimensional gel electrophoresis and mass-spectrum detection

BACKGROUND： The Glasgow Coma Scale, computer tomography, and nuclear magnetic resonance imaging have been frequently used to diagnose brain injury. However, these methods do not accurately and quantitatively evaluate injury degree. However, proteomics displays some advantages. To date, there are few proteomics studies based on primary astrocyte cultures from a fluid percussion injury model. OBJECTIVE： To detect differential protein expression in rat cerebral cortical astrocytes following fluid percussion injury using two-dimensional gel electrophoresis and mass spectrum and to determine specific biological markers of brain injury. DESIGN, TIME AND SETTING： Complete, randomized grouping and proteomics experiments were performed at the Molecular Pathological Laboratory, Central Laboratory and Tianjin Key Laboratory for Biomarkers of Occupational and Environmental Hazard of Medical College of Chinese People＇s Armed Police Force from October 2007 to May 2008. MATERIALS： Inverted phase-contrast microscope was purchased from Olympus, Japan. PROTEAN IEF Cell isoelectric focusing electrophoresis system and PROTEAN II Xi-Cell vertical electrophoresis system were purchased from Bio-Rad, USA. Autofiex MALDI-TOF mass spectrometer was purchased from Bruker, Germany. METHODS： A total of 90 culture dishes, fully coated with Sprague Dawley rat cortical astrocytes, were randomly divided into control （n = 30） and injury （n = 60） groups. Astrocytes in the injury group were subjected to fluid percussion and subdivided into 4-hour （n = 30） and 48-hour injury （n = 30） groups. MAIN OUTCOME MEASURES： Cell morphology was observed using inverted phase-contrast microscopy. Cell total protein was extracted from each group, followed by two-dimensional gel electrophoresis and silver staining, and the differential protein expression was analyzed using PDQuest 7.0 software. Protein peptide mass fingerprinting of differential protein spots was obtained by matrix assisted laser desorption/ionization-time of flight mass spectrometry. The National Center for Biotechnology Information （NCBI） protein database was retrieved by Mascot to primarily identify protein type, Finally, differential protein expression was detected by Western blot analysis. RESULTS： Following fluid percussion injury, astrocytes displayed obvious swelling and increased intercellular space, with some cell detachment; the number of dead cells was significantly greater than the control group （P 〈 0.05）. Expression intensity of 114 protein spots was significantly greater in the injury group compared with the control group （P〈 0.05）; 9 of the 114 protein spots were identified and peptJde matching scores of 8 spots were 〉 61 （P 〈 0.05）. Protein types were identified and included cellular retinol binding protein, brain fatty acid binding protein 7, $100 calcium binding protein All, 60S acidic ribosomal protein P2, calponin 3, breast carcinoma amplified sequence 2 homolog, eukaryotic translation initiation factor 1A, and hypothetical protein LOC685814. Western blot detection revealed brain fatty acid binding protein 7 expression in cortical astrocytes, which increased with injury time compared with the control group （P 〈 0.05）. CONCLUSION： Results from this study showed morphological and proteomic changes in cortical astrocytes following fluid percussion injury. Brain fatty acid binding protein 7 was expressed in astrocytes and possibly played an important role in injury repair. Mass-spectrum identified differentially expressed proteins that correlated with cell metabolism regulation, signal transduction, and translation initiation, and could serve as specific biological markers of brain injury.

In-flight performance analysis of the navigation augmentation payload on LEO communication satellite:a preliminary study on WT01 mission

With the development of the Low Earth Orbit(LEO)communication constellations,it has become a hot area of research to provide additional navigation augmentation services.Limited by volume,weight,power consumption,and running time,the in-flight performance of navigation augmentation payload remains to be investigated.In this paper,we analyze the data quality of on-board GNSS observation and evaluate the precision of short-arc dynamic Precise Orbit Determination(POD)performance based on the WangTong-01(WT01)mission.Furthermore,the downlink navigation measurement data of WT01 satellites are analyzed and compared with the GNSS observations.The results show that the average multipath errors of the WT01 on-board GPS L1,L2 and BeiDou Satellite Navigation System(BDS)B1,B2 code observation are 0.54,0.74,0.65,and 0.58 m,respectively.The short-arc dynamic POD three-dimensional(3D)overlapping accuracy is 7.1 cm.The average multipath errors of downlink navigation signal Z1 and Z2 are 0.81 and 0.80 m,respectively,which at the same order of magnitude as GNSS signals.The maximum Carrier-to-Noise Ratio(C/N0)value of WT01 downlink measurement data can reach 60 dB Hz,which is much stronger than GNSS and indicates the navigation signals of LEO satellites can meet the basic requirement of navigation augmentation.

Supplementary open dataset for WiFi indoor localization based on received signal strength

Several Wireless Fidelity(WiFi)fingerprint datasets based on Received Signal Strength(RSS)have been shared for indoor localization.However,they can’t meet all the demands of WiFi RSS-based localization.A supplementary open dataset for WiFi indoor localization based on RSS,called as SODIndoorLoc,covering three buildings with multiple floors,is presented in this work.The dataset includes dense and uniformly distributed Reference Points(RPs)with the average distance between two adjacent RPs smaller than 1.2 m.Besides,the locations and channel information of pre-installed Access Points(APs)are summarized in the SODIndoorLoc.In addition,computer-aided design drawings of each floor are provided.The SODIndoorLoc supplies nine training and five testing sheets.Four standard machine learning algorithms and their variants(eight in total)are explored to evaluate positioning accuracy,and the best average positioning accuracy is about 2.3 m.Therefore,the SODIndoorLoc can be treated as a supplement to UJIIndoorLoc with a consistent format.The dataset can be used for clustering,classification,and regression to compare the performance of different indoor positioning applications based on WiFi RSS values,e.g.,high-precision positioning,building,floor recognition,fine-grained scene identification,range model simulation,and rapid dataset construction.