Development of Integrated and Intelligent Geodetic and Photogrammetry Satellites with Corresponding Key Technologies

Aerospace surveying and mapping has become the main method of global earth observation.It can be divided into the geodetic observation satellites and the topographic surveying satellites according to the disciplines.In this paper,the geodetic satellites and photographic satellites are introduced respectively.Then,the existing problems in Chinese earth observation satellites are analyzed,and the comprehensive satellite with integrated payloads,the intensive microsatellite constellation and the intelligent observation satellite are proposed as three different development ideas for the future earth observation satellites.The possibility of the three ideas is discussed in detail,as well as the related key technologies.

High-precision group-delay dispersion measurements of optical fibers via fingerprint-spectral wavelength-to-time mapping

The group-delay dispersion of an optical fiber was measured with the time-of-flight method, using fingerprint-like characteristic spectra from a mode-locked fiber laser source. To determine the group-delay dispersion up to the fourth order, least-squares fitting was applied to the overall time waveform mapped on the time axis for the fingerprint-spectral broadband pulses through a long optical fiber. The analysis of all 4003 data points reduced statistical uncertainty, and provided second-, third-, and fourth-order dispersion with uncertainties of 0.02%, 0.4%, and 4%,respectively.

An optical modulation format generation scheme based on spectral filtering and frequency-to-time mapping

An optical modulation format generation scheme based on spectral filtering and frequency-to-time mapping is experimentally demonstrated. Many modulation formats with continuously adjustable duty radio and bit rate can be formed by changing the dispersion of dispersion element and the bandwidth of shaped spectrum in this scheme. In the experiment, non-return-to-zero(NRZ) signal with bit rate of 29.41 Gbit/s and 1/2 duty ratio return-to-zero(RZ) signal with bit rate of 13.51 Gbit/s are obtained. The maximum bit rate of modulation format signal is also analyzed.

New Generations: Sequencing Machines and Their Computational Challenges

New generation sequencing systems are changing how molecular biology is practiced. The widely promoted $1000 genome will be a reality with attendant changes for healthcare, including personalized medicine. More broadly the genomes of many new organisms with large samplings from populations will be commonplace. What is less appreciated is the explosive demands on computation, both for CPU cycles and storage as well as the need for new computational methods. In this article we will survey some of these developments and demands.

A chromosome-level,haplotype-phased Vanilla planifolia genome highlights the challenge of partial endoreplication for accurate wholegenome assembly

Vanilla planifolia, the species cultivated to produce one of the world’s most popular flavors, is highly proneto partial genome endoreplication, which leads to highly unbalanced DNA content in cells. We report herethe first molecular evidence of partial endoreplication at the chromosome scale by the assembly and annotation of an accurate haplotype-phased genome of V. planifolia. Cytogenetic data demonstrated that thediploid genome size is 4.09 Gb, with 16 chromosome pairs, although aneuploid cells are frequentlyobserved. Using PacBio HiFi and optical mapping, we assembled and phased a diploid genome of 3.4 Gbwith a scaffold N50 of 1.2 Mb and 59 128 predicted protein-coding genes. The atypical k-mer frequenciesand the uneven sequencing depth observed agreed with our expectation of unbalanced genome representation. Sixty-seven percent of the genes were scattered over only 30% of the genome, putatively linkinggene-rich regions and the endoreplication phenomenon. By contrast, low-coverage regions (non-endoreplicated) were rich in repeated elements but also contained 33% of the annotated genes. Furthermore, this assembly showed distinct haplotype-specific sequencing depth variation patterns, suggesting complexmolecular regulation of endoreplication along the chromosomes. This high-quality, anchored assemblyrepresents 83% of the estimated V. planifolia genome. It provides a significant step toward the elucidationof this complex genome. To support post-genomics efforts, we developed the Vanilla Genome Hub, a userfriendly integrated web portal that enables centralized access to high-throughput genomic and other omicsdata and interoperable use of bioinformatics tools.