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The permanent magnet flux is an important model parameter that determines the operation of the line start permanent magnet synchronous motor. It is degraded with operating time due to the permanent magnet demagnetization which is principally caused by the armature magnetic field interaction and operating temperature. This paper introduces an observer design study aimed at estimating the permanent magnet flux of the line start permanent magnet synchronous motor from the measurement of stator currents. Derived from the mathematical description in the dq0 reference frame, a model of the motor with state variables of stator currents, magnetic fluxes and rotor angular frequency is considered. Model analysis and with a new flux variable setting allow an estimation of the rotor flux through the open loops from the stator currents. The observer is then designed with a constant gain for the system with states of stator currents and permanent magnet flux. Simulation confirms the efficiency and robustness of the designed observer.

Background: The under-representation of Vietnamese ethnic groups in existing genetic databases and studies have undermined our understanding of the genetic variations and associated traits or diseases in the population. Cost and technology limitations remain the challenges in performing large-scale genome sequencing projects in Vietnam and many developing countries. Non-invasive prenatal testing (NIPT) data offers an alternative untapped resource to study genetic variations in the Vietnamese population. Results: We analyzed the low-coverage genomes of 2,683 pregnant Vietnamese women using their NIPT data and identified a comprehensive set of 8,054,515 single-nucleotide polymorphisms, among which 8.2% were new to the Vietnamese population. Our study also revealed 24,487 disease-associated genetic variants and their allele frequency distribution, especially five pathogenic variants for prevalent genetic disorders in Vietnam. We also observed major discrepancies in the allele frequency distribution of disease-associated genetic variants between the Vietnamese and other populations, thus highlighting a need for genome-wide association studies dedicated to the Vietnamese population. Conclusions: We have demonstrated a successful analysis of NIPT data to reconstruct the Vietnamese genetic profiles. This application provides a powerful yet cost-effective approach for large-scale population genetic studies.

Bài viết giới thiệu nghiên cứu “Paintings Can Be Forged, But Not Feeling”: Vietnamese Art—Market, Fraud, and Value về thực trạng tranh giả tại Việt Nam.