21 research outputs found

    System-on-a-Chip Based Nano Star Tracker and Its Real-Time Image Processing Approach

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    The star tracker is one of the most accurate components for satellite attitude determination. With the development of the nano star tracker, it is compatible for application on small satellites. However, the drawback in dynamic property of nano star tracker has limited its extensive applications. The principal objective of this study is to introduce a system-on-a-chip (SOC) based nano star tracker with enhanced dynamic property. A morphology based image processing approach was realized based on single FPGA to achieve real-time star extraction, even from a blurred image. Such nano star tracker has been developed and tested, and field experiment results indicated that its dynamic range was up to 4Ā°/s with a data update rate of 30Hz. Moreover, the orientation of the satellite with developed nano star tracker on board has been analyzed based on the telemetry data. Thus, such nano star tracker could promote its applications on small or agile satellites

    Genetic Relatedness of Indigenous Ethic Groups in Northern Borneo to Neighboring Populations from Southeast Asia, as inferred from Genome-wide SNP Data

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    The region of northern Borneo is home to the current state of Sabah, Malaysia. It is located closest to the southern Philippine islands and may have served as a viaduct for ancient human migration onto or off of Borneo Island. In this study, five indigenous ethnic groups from Sabah were subjected to genome-wide SNP genotyping. These individuals represent the "North Borneo"-speaking group of the great Austronesian family. They have traditionally resided in the inland region of Sabah. The dataset was merged with public datasets, and the genetic relatedness of these groups to neighboring populations from the islands of Southeast Asia, mainland Southeast Asia and southern China was inferred. Genetic structure analysis revealed that these groups formed a genetic cluster that was independent of the clusters of neighboring populations. Additionally, these groups exhibited near-absolute proportions of a genetic component that is also common among Austronesians from Taiwan and the Philippines. They showed no genetic admixture with Austro-Melanesian populations. Furthermore, phylogenetic analysis showed that they are closely related to non-Austro-Melansian Filipinos as well as to Taiwan natives but are distantly related to populations from mainland Southeast Asia. Relatively lower heterozygosity and higher pairwise genetic differentiation index (FST ) values than those of nearby populations indicate that these groups might have experienced genetic drift in the past, resulting in their differentiation from other Austronesians. Subsequent formal testing suggested that these populations have received no gene flow from neighboring populations. Taken together, these results imply that the indigenous ethnic groups of northern Borneo shared a common ancestor with Taiwan natives and non-Austro-Melanesian Filipinos and then isolated themselves on the inland of Sabah. This isolation presumably led to no admixture with other populations, and these individuals therefore underwent strong genetic differentiation. This report contributes to addressing the paucity of genetic data on representatives from this strategic region of ancient human migration event(s)

    Genetic relatedness of indigenous ethnic groups in northern Borneo to neighboring populations from Southeast Asia, as inferred from genome-wide SNP data

    Get PDF
    The region of northern Borneo is home to the current state of Sabah, Malaysia. It is located closest to the southern Philippine islands and may have served as a viaduct for ancient human migration onto or off of Borneo Island. In this study, five indigenous ethnic groups from Sabah were subjected to genome-wide SNP genotyping. These individuals represent the ā€œNorth Borneoā€-speaking group of the great Austronesian family. They have traditionally resided in the inland region of Sabah. The dataset was merged with public datasets, and the genetic relatedness of these groups to neighboring populations from the islands of Southeast Asia, mainland Southeast Asia and southern China was inferred. Genetic structure analysis revealed that these groups formed a genetic cluster that was independent of the clusters of neighboring populations. Additionally, these groups exhibited near-absolute proportions of a genetic component that is also common among Austronesians from Taiwan and the Philippines. They showed no genetic admixture with Austro-Melanesian populations. Furthermore, phylogenetic analysis showed that they are closely related to nonā€“Austro-Melansian Filipinos as well as to Taiwan natives but are distantly related to populations from mainland Southeast Asia. Relatively lower heterozygosity and higher pairwise genetic differentiation index (FST) values than those of nearby populations indicate that these groups might have experienced genetic drift in the past, resulting in their differentiation from other Austronesians. Subsequent formal testing suggested that these populations have received no gene flow from neighboring populations. Taken together, these results imply that the indigenous ethnic groups of northern Borneo shared a common ancestor with Taiwan natives and nonā€“Austro- Melanesian Filipinos and then isolated themselves on the inland of Sabah. This isolation presumably led to no admixture with other populations, and these individuals therefore underwent strong genetic differentiation. This report contributes to addressing the paucity of genetic data on representatives from this strategic region of ancient human migration event(s)

    An Analysis of the Microstructure of the Melting Layer of a Precipitating Stratiform Cloud at the Dissipation Stage

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    In this study, we investigated the macro- and microstructures of layered precipitation clouds in spring in Jilin Province, China. The premise of the campaign was to observe cloud particles in the melting layer (ML). The weather was developed under the influence of the Mongolia cyclone, which brought a large range of precipitation to the northeast. Combining the Droplet Measurement Technology (DMT) and Particle Measuring Systems (PMS) data, small particles accounted for the majority of all particles at each level above and below the ML. In our observations, both ice crystals (50ā€“300 Ī¼m) and snowflakes (>300 Ī¼m) had two peaks between āˆ’5 and āˆ’2 Ā°C. The high concentration of ice crystals at a temperature of āˆ’2.65 Ā°C (4865 m) attained a maximum value of 287 Lāˆ’1 and snowflakes with 47 Lāˆ’1, which was similar to the previous studies. The Hallettā€“Mossop ice multiplication process operated most effectively at the temperature of āˆ’5 Ā°C in this study. Even at the cloud dissipation stage, new droplets were still generated between āˆ’5 and āˆ’6 Ā°C, providing abundant liquid water content (LWC) for the upper cloud. Although irregulars were observed, needles and spheres dominated in the observed cloud region of low LWC (āˆ’3) at temperatures of āˆ’6 to āˆ’3 Ā°C. These cloud conditions fit into the Hallettā€“Mossop criteria
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