In the future power-electronics-dominated power systems,grid-forming(GFM)converters have been regarded as important devices to actively establish frequency and voltage,so as to provide essential grid support.However,d...In the future power-electronics-dominated power systems,grid-forming(GFM)converters have been regarded as important devices to actively establish frequency and voltage,so as to provide essential grid support.However,due to their voltage source behavior and emulated swing dynamics,GFM converters may encounter low-frequency oscillations(LFOs)when connected to strong grids,which belongs to the self-stability problem of GFM converters.Moreover,GFM converters will also interact with grid-following(GFL)converters and thus impact the mid-frequency oscillations(MFOs)induced by phase-locked loops(PLLs).It has been preliminarily shown in the literature that GFM converters can help stabilize the PLL-induced MFOs,but currently,there is a lack of systematic design methods to coordinate the self-stability and stabilizing ability of GFM converters.This paper addresses this gap by revisiting the impedance model of a typical GFM converter and briefly analyze the oscillations caused by converters.Based on our analysis,we propose a frequency-partitioned synthesis design framework to enable dynamic virtual impedance(DVI)in GFM converters,aiming to enhance their self-stability and stabilizing ability simultaneously.Particularly,a self-stabilizing module is designed to ensure robust device-level damping,with control parameters auto-tuned using H∞methods.In parallel,a stabilizing module is introduced to stabilize GFL converters and enhance the system-level stability,which utilizes a perceive-and-optimize tuning strategy.Simulation results validate the effectiveness of the proposed synthesis DVI framework.展开更多
Background:In 2021,the American College of Medical Genetics and Genomics(ACMG)recommended reporting actionable genotypes in 73 genes associated with diseases for which preventive or therapeutic measures are available....Background:In 2021,the American College of Medical Genetics and Genomics(ACMG)recommended reporting actionable genotypes in 73 genes associated with diseases for which preventive or therapeutic measures are available.Evaluations of the association of actionable genotypes in these genes with life span are currently lacking.展开更多
In this paper,a class of semilinear parabolic equations with cross coupling of power and exponential functions and large initial values are studied.By constructing and solving ordinary differential equations,the upper...In this paper,a class of semilinear parabolic equations with cross coupling of power and exponential functions and large initial values are studied.By constructing and solving ordinary differential equations,the upper and lower bounds on the solution life span of the equations areobtained.展开更多
Significant two-way shape memory effect(TWSME)was achieved in single crystals of single-phase multielement Ni42-x Cu8 Cox Mn37 Ga13(8≤x≤12)alloys by performing thermomechanical training.However,anomalous dependence ...Significant two-way shape memory effect(TWSME)was achieved in single crystals of single-phase multielement Ni42-x Cu8 Cox Mn37 Ga13(8≤x≤12)alloys by performing thermomechanical training.However,anomalous dependence of the martensitic transformation temperature span on Co content was observed.Before training,quite a narrow temperature span of the martensitic transformation,nearly independent of the Co content,was observed in all single crystals.After training the temperature span was still narrow for 8≤x≤10.9 but was obviously expanded for 10.9<x≤12.High-resolution transmission electron microscopy revealed that at the atomic scale,there exists incommensurate modulated structure in the single phase single crystals,as evidenced by nonperiodic satellite spots in the selected area electronic diffraction patterns.Moreover,the modulated wave vector of the satellite spots was increased by higher Co contents.Combining first principal calculations it was considered that the incommensurate modulated structure originates from the formation of Co-Co pairs.After training arrays of ordered dislocations with the same Burgers vector were introduced for 8≤x≤10.9 but the network of dislocations was formed for 10.9<x≤12.Based on analysis of transmission electron microscopy,geometric phase,thermodynamics,and Landau theory,it was considered that the austenite/martensite phase interface was pinned by the network of dislocations,expanding the temperature span of the martensitic transformation.This work supplies new insights for understanding the microstructure and martensitic transformation of Ni-Mn-Ga-based alloys.展开更多
Background:In 2021,the American College of Medical Genetics and Genomics(ACMG)recommended reporting actionable genotypes in 73 genes associated with diseases for which preventive or therapeutic measures are available....Background:In 2021,the American College of Medical Genetics and Genomics(ACMG)recommended reporting actionable genotypes in 73 genes associated with diseases for which preventive or therapeutic measures are available.Evaluations of the association of actionable genotypes in these genes with life span are currently lacking.Methods:We assessed the prevalence of coding and splice variants in genes on the ACMG Secondary Findings,version 3.0(ACMG SF v3.0),list in the genomes of 57,933 Icelanders.We assigned pathogenicity to all reviewed variants using reported evidence in the ClinVar database,the frequency of variants,and their associations with disease to create a manually curated set of actionable genotypes(variants).We assessed the relationship between these genotypes and life span and further examined the specific causes of death among carriers.展开更多
基金supported by National Natural Science Foundation of China(U24B6008,U22B6008)State Grid Zhejiang Electric Power Co.,Ltd.Science,and Technology Project(B311DS240015).
文摘In the future power-electronics-dominated power systems,grid-forming(GFM)converters have been regarded as important devices to actively establish frequency and voltage,so as to provide essential grid support.However,due to their voltage source behavior and emulated swing dynamics,GFM converters may encounter low-frequency oscillations(LFOs)when connected to strong grids,which belongs to the self-stability problem of GFM converters.Moreover,GFM converters will also interact with grid-following(GFL)converters and thus impact the mid-frequency oscillations(MFOs)induced by phase-locked loops(PLLs).It has been preliminarily shown in the literature that GFM converters can help stabilize the PLL-induced MFOs,but currently,there is a lack of systematic design methods to coordinate the self-stability and stabilizing ability of GFM converters.This paper addresses this gap by revisiting the impedance model of a typical GFM converter and briefly analyze the oscillations caused by converters.Based on our analysis,we propose a frequency-partitioned synthesis design framework to enable dynamic virtual impedance(DVI)in GFM converters,aiming to enhance their self-stability and stabilizing ability simultaneously.Particularly,a self-stabilizing module is designed to ensure robust device-level damping,with control parameters auto-tuned using H∞methods.In parallel,a stabilizing module is introduced to stabilize GFL converters and enhance the system-level stability,which utilizes a perceive-and-optimize tuning strategy.Simulation results validate the effectiveness of the proposed synthesis DVI framework.
文摘Background:In 2021,the American College of Medical Genetics and Genomics(ACMG)recommended reporting actionable genotypes in 73 genes associated with diseases for which preventive or therapeutic measures are available.Evaluations of the association of actionable genotypes in these genes with life span are currently lacking.
基金Supported by Key Project Funding for Shaanxi Higher Education Teaching Reform Research (23BZ078)Shaanxi Provincial Education Science Planning Project (SGH24Y2782)+4 种基金Shaanxi Provincial Social Science Foundation Program(2024D008)Key Projects of the Second Huang Yanpei Vocational Education Thought Research Planning Project (ZJS2024ZN026)Shaanxi Higher Education Society Key Projects(XGHZ2301)2024 Annual Planning Project of the China Association for Non-Government Education (School Development Category)(CANFZG24095)the Youth Innovation Team of Shaanxi Universities。
文摘In this paper,a class of semilinear parabolic equations with cross coupling of power and exponential functions and large initial values are studied.By constructing and solving ordinary differential equations,the upper and lower bounds on the solution life span of the equations areobtained.
基金support from the National Key Research and Development Program of China(Grant No.2021YFB3501402)the National Natural Science Foundation of China(Grant Nos.52250313 and 52121001)Yang Liu and Chen Si acknowledge financial support from the National Natural Science Foundation of China(Grant No.12274013).
文摘Significant two-way shape memory effect(TWSME)was achieved in single crystals of single-phase multielement Ni42-x Cu8 Cox Mn37 Ga13(8≤x≤12)alloys by performing thermomechanical training.However,anomalous dependence of the martensitic transformation temperature span on Co content was observed.Before training,quite a narrow temperature span of the martensitic transformation,nearly independent of the Co content,was observed in all single crystals.After training the temperature span was still narrow for 8≤x≤10.9 but was obviously expanded for 10.9<x≤12.High-resolution transmission electron microscopy revealed that at the atomic scale,there exists incommensurate modulated structure in the single phase single crystals,as evidenced by nonperiodic satellite spots in the selected area electronic diffraction patterns.Moreover,the modulated wave vector of the satellite spots was increased by higher Co contents.Combining first principal calculations it was considered that the incommensurate modulated structure originates from the formation of Co-Co pairs.After training arrays of ordered dislocations with the same Burgers vector were introduced for 8≤x≤10.9 but the network of dislocations was formed for 10.9<x≤12.Based on analysis of transmission electron microscopy,geometric phase,thermodynamics,and Landau theory,it was considered that the austenite/martensite phase interface was pinned by the network of dislocations,expanding the temperature span of the martensitic transformation.This work supplies new insights for understanding the microstructure and martensitic transformation of Ni-Mn-Ga-based alloys.
文摘Background:In 2021,the American College of Medical Genetics and Genomics(ACMG)recommended reporting actionable genotypes in 73 genes associated with diseases for which preventive or therapeutic measures are available.Evaluations of the association of actionable genotypes in these genes with life span are currently lacking.Methods:We assessed the prevalence of coding and splice variants in genes on the ACMG Secondary Findings,version 3.0(ACMG SF v3.0),list in the genomes of 57,933 Icelanders.We assigned pathogenicity to all reviewed variants using reported evidence in the ClinVar database,the frequency of variants,and their associations with disease to create a manually curated set of actionable genotypes(variants).We assessed the relationship between these genotypes and life span and further examined the specific causes of death among carriers.
