To elucidate the effect of calcite-regulated activated carbon(AC)structure on low-temperature denitrification performance of SCR catalysts,this work prepared a series of Mn-Ce/De-AC-xCaCO_(3)(x is the calcite content ...To elucidate the effect of calcite-regulated activated carbon(AC)structure on low-temperature denitrification performance of SCR catalysts,this work prepared a series of Mn-Ce/De-AC-xCaCO_(3)(x is the calcite content in coal)catalysts were prepared by the incipient wetness impregnation method,followed by acid washing to remove calcium-containing minerals.Comprehensive characterization and low-temperature denitrification tests revealed that calcite-induced structural modulation of coal-derived AC significantly enhances catalytic activity.Specifically,NO conversion increased from 88.3%of Mn-Ce/De-AC to 91.7%of Mn-Ce/De-AC-1CaCO_(3)(210℃).The improved SCR denitrification activity results from the enhancement of physicochemical properties including higher Mn^(4+)content and Ce^(4+)/Ce^(3+)ratio,an abundance of chemisorbed oxygen and acidic sites,which could strengthen the SCR reaction pathways(richer NH_(3)activated species and bidentate nitrate active species).Therefore,NO removal is enhanced.展开更多
With the rapid development of large-scale offshore wind farms,efficient and reliable power transmission systems are urgently needed.Hybrid high-voltage direct current(HVDC)configurations combining a diode rectifier un...With the rapid development of large-scale offshore wind farms,efficient and reliable power transmission systems are urgently needed.Hybrid high-voltage direct current(HVDC)configurations combining a diode rectifier unit(DRU)and a modular multilevel converter(MMC)have emerged as a promising solution,offering advantages in cost-effectiveness and control capability.However,the uncontrollable nature of the DRU poses significant challenges for systemstability under offshore AC fault conditions,particularly due to its inability to provide fault current or voltage support.This paper investigates the offshore AC fault characteristics and fault ride-through(FRT)strategy of a hybrid offshore wind power transmission system based on a diode rectifier unit DRU and MMC.First,the dynamic response of the hybrid system under offshore symmetrical three-phase faults is analyzed.It is demonstrated that due to the unidirectional conduction nature of the DRU,its AC current rapidly drops to zero during faults,and the fault current is solely contributed by the wind turbine generators(WTGs)and wind farm MMC(WFMMC).Based on this analysis,a coordinated FRT strategy is proposed,which combines a segmented current limiting control for the wind-turbine(WT)grid-side converters(GSCs)and a constant AC current control for the WFMMC.The strategy ensures effective voltage support during the fault and prevents MMC current saturation during fault recovery,enabling fast and stable system restoration.Electromagnetic transient simulations in PSCAD/EMTDC verify the feasibility of the proposed fault ride-through strategy.展开更多
Severe acute pancreatitis(SAP)can induce acute respiratory distress syndrome(ARDS)and abdominal compartment syndrome(ACS).Although prone position ventilation(PPV)can improve outcomes in patients with ARDS,there is sig...Severe acute pancreatitis(SAP)can induce acute respiratory distress syndrome(ARDS)and abdominal compartment syndrome(ACS).Although prone position ventilation(PPV)can improve outcomes in patients with ARDS,there is significant controversy regarding its concurrent use with ACS owing to concerns of increased risk of intra-abdominal pressure(IAP).[1]We present a case of successful PPV application without adverse eff ects.展开更多
单级式双有源桥(dual active bridge,DAB)DC/AC变换器控制自由度多,变压器匝比、漏感、开关频率等参数相互耦合,导致变换器效率优化面临多重制约。该文分析变压器匝比、漏感与软开关范围、漏感电流有效值、漏感电流峰值之间的约束关系,...单级式双有源桥(dual active bridge,DAB)DC/AC变换器控制自由度多,变压器匝比、漏感、开关频率等参数相互耦合,导致变换器效率优化面临多重制约。该文分析变压器匝比、漏感与软开关范围、漏感电流有效值、漏感电流峰值之间的约束关系,提出直接表征DAB-DC/AC变换器效率的物理量:效率敏感因子。通过研究效率敏感因子对系统损耗的影响机理,实现变换器效率最优的硬件参数设计,为多参数耦合的单级式DAB-DC/AC变换器效率优化提供理论指导。最后通过一台450 W样机验证所提理论的正确性。展开更多
Single-phase 25 kV traction networks of electrified alternating current(AC)railways create electromagnetic fields(EMFs)with significant levels of intensity.The most intense magnetic fields occur when short circuits ex...Single-phase 25 kV traction networks of electrified alternating current(AC)railways create electromagnetic fields(EMFs)with significant levels of intensity.The most intense magnetic fields occur when short circuits exist between the contact wire and rails or ground.Despite the short duration of exposure,they can adversely affect electronic devices and induce significant voltages in adjacent power lines,which is dangerous for operating personnel.Although numerous investigations have focused on modeling the EMF of traction networks and power lines,the challenge of determining the three-dimensional electromagnetic fields near metal supports during the flow of a short-circuit current through them is yet to be resolved.In this case,the field has a complex spatial structure that significantly complicates the calculations of intensities.This study proposes a methodology,algorithms,software,and digital models for determining the EMF in the described emergency scenarios.During the modeling process,the objects being studied were represented by segments of thin wires to analyze the distribution of the electric charge and calculate the intensities of the electric and magnetic fields.This approach was implemented in the Fazonord software,and the modeling results show a substantial increase in EMF levels close to the support,with a noticeable decrease in the levels as the distance from it increases.The procedure implemented in the commercial software Fazonord is universal and can be used to determine electromagnetic fields at any electrical power facility that includes live parts of limited length.Based on the proposed procedure,the EMF near the supports of overhead power lines and traction networks of various designs could be determined,the EMF levels at substations can be calculated,and the influence of metal structures located near traction networks,such as pedestrian crossings at railway stations,can be considered.展开更多
【目的】基于猪极端饲料报酬表型,利用靶向切割标签技术(cleavage under targets and tagmentation,CUT&Tag)构建H3K27ac差异图谱,鉴定关联的启动子、增强子和关联候选基因,为猪饲料报酬解析提供基础数据。【方法】从209头杜洛克猪...【目的】基于猪极端饲料报酬表型,利用靶向切割标签技术(cleavage under targets and tagmentation,CUT&Tag)构建H3K27ac差异图谱,鉴定关联的启动子、增强子和关联候选基因,为猪饲料报酬解析提供基础数据。【方法】从209头杜洛克猪中筛选饲料报酬表型差异最大的4头个体分别组成低剩余采食量组(L组,n=2)和高剩余采食量组(H组,n=2)。利用CUT&Tag技术,以H3K27ac作为活性启动子和增强子的表观遗传标记对4头个体的肝脏组织进行全基因组扫描,鉴定关联启动子、增强子和候选基因,并进一步采用real-time quantitative PCR(RT-qPCR)对重要基因进行验证。【结果】共鉴定出47271个H3K27ac峰,包括15739个潜在启动子和31532个推定增强子,大部分的H3K27ac峰位于近端启动子区域。根据H3K27ac全基因的分布情况和作用特点,发现3087个差异峰(对应2188个基因),其中867个H3K27ac峰(对应664个基因)富集在H组,2220个H3K27ac峰(对应1575个基因)富集在L组。GO和KEGG结果发现H3K27ac增强子可能是通过影响胆汁酸代谢、淋巴细胞代谢和NF-κB通路来调节饲料报酬。RT-qPCR结果显示,与H组相比,DIAPH3、DPYD、FTO、TCF7L2、ABCC2、ABCC11、RXRA和ABCG8在L组中显著上调(P<0.05),而PAX5、GRHPR、NFATC1、CARD11、BLNK和LYN在L组中显著下调(P<0.05)。【结论】本研究成功生成了具有极端RFI差异的杜洛克猪肝脏组织中的H3K27ac差异图谱以及相关数据。基于该图谱鉴定和验证了关联候选基因,为进一步解析启动子和增强子调控饲料报酬的分子机制提供了基础数据。展开更多
基金Supported by the Science and Technology Cooperation and Exchange special project of Cooperation of Shanxi Province(202404041101014)the Fundamental Research Program of Shanxi Province(202403021212333)+3 种基金the Joint Funds of the National Natural Science Foundation of China(U24A20555)the Lvliang Key R&D of University-Local Cooperation(2023XDHZ10)the Initiation Fund for Doctoral Research of Taiyuan University of Science and Technology(20242026)the Outstanding Doctor Funding Award of Shanxi Province(20242080).
文摘To elucidate the effect of calcite-regulated activated carbon(AC)structure on low-temperature denitrification performance of SCR catalysts,this work prepared a series of Mn-Ce/De-AC-xCaCO_(3)(x is the calcite content in coal)catalysts were prepared by the incipient wetness impregnation method,followed by acid washing to remove calcium-containing minerals.Comprehensive characterization and low-temperature denitrification tests revealed that calcite-induced structural modulation of coal-derived AC significantly enhances catalytic activity.Specifically,NO conversion increased from 88.3%of Mn-Ce/De-AC to 91.7%of Mn-Ce/De-AC-1CaCO_(3)(210℃).The improved SCR denitrification activity results from the enhancement of physicochemical properties including higher Mn^(4+)content and Ce^(4+)/Ce^(3+)ratio,an abundance of chemisorbed oxygen and acidic sites,which could strengthen the SCR reaction pathways(richer NH_(3)activated species and bidentate nitrate active species).Therefore,NO removal is enhanced.
基金funded by the Science and Technology Projects of State Grid Zhejiang Electric Power Co.,Ltd.(5211DS24000G).
文摘With the rapid development of large-scale offshore wind farms,efficient and reliable power transmission systems are urgently needed.Hybrid high-voltage direct current(HVDC)configurations combining a diode rectifier unit(DRU)and a modular multilevel converter(MMC)have emerged as a promising solution,offering advantages in cost-effectiveness and control capability.However,the uncontrollable nature of the DRU poses significant challenges for systemstability under offshore AC fault conditions,particularly due to its inability to provide fault current or voltage support.This paper investigates the offshore AC fault characteristics and fault ride-through(FRT)strategy of a hybrid offshore wind power transmission system based on a diode rectifier unit DRU and MMC.First,the dynamic response of the hybrid system under offshore symmetrical three-phase faults is analyzed.It is demonstrated that due to the unidirectional conduction nature of the DRU,its AC current rapidly drops to zero during faults,and the fault current is solely contributed by the wind turbine generators(WTGs)and wind farm MMC(WFMMC).Based on this analysis,a coordinated FRT strategy is proposed,which combines a segmented current limiting control for the wind-turbine(WT)grid-side converters(GSCs)and a constant AC current control for the WFMMC.The strategy ensures effective voltage support during the fault and prevents MMC current saturation during fault recovery,enabling fast and stable system restoration.Electromagnetic transient simulations in PSCAD/EMTDC verify the feasibility of the proposed fault ride-through strategy.
文摘Severe acute pancreatitis(SAP)can induce acute respiratory distress syndrome(ARDS)and abdominal compartment syndrome(ACS).Although prone position ventilation(PPV)can improve outcomes in patients with ARDS,there is significant controversy regarding its concurrent use with ACS owing to concerns of increased risk of intra-abdominal pressure(IAP).[1]We present a case of successful PPV application without adverse eff ects.
文摘单级式双有源桥(dual active bridge,DAB)DC/AC变换器控制自由度多,变压器匝比、漏感、开关频率等参数相互耦合,导致变换器效率优化面临多重制约。该文分析变压器匝比、漏感与软开关范围、漏感电流有效值、漏感电流峰值之间的约束关系,提出直接表征DAB-DC/AC变换器效率的物理量:效率敏感因子。通过研究效率敏感因子对系统损耗的影响机理,实现变换器效率最优的硬件参数设计,为多参数耦合的单级式DAB-DC/AC变换器效率优化提供理论指导。最后通过一台450 W样机验证所提理论的正确性。
文摘Single-phase 25 kV traction networks of electrified alternating current(AC)railways create electromagnetic fields(EMFs)with significant levels of intensity.The most intense magnetic fields occur when short circuits exist between the contact wire and rails or ground.Despite the short duration of exposure,they can adversely affect electronic devices and induce significant voltages in adjacent power lines,which is dangerous for operating personnel.Although numerous investigations have focused on modeling the EMF of traction networks and power lines,the challenge of determining the three-dimensional electromagnetic fields near metal supports during the flow of a short-circuit current through them is yet to be resolved.In this case,the field has a complex spatial structure that significantly complicates the calculations of intensities.This study proposes a methodology,algorithms,software,and digital models for determining the EMF in the described emergency scenarios.During the modeling process,the objects being studied were represented by segments of thin wires to analyze the distribution of the electric charge and calculate the intensities of the electric and magnetic fields.This approach was implemented in the Fazonord software,and the modeling results show a substantial increase in EMF levels close to the support,with a noticeable decrease in the levels as the distance from it increases.The procedure implemented in the commercial software Fazonord is universal and can be used to determine electromagnetic fields at any electrical power facility that includes live parts of limited length.Based on the proposed procedure,the EMF near the supports of overhead power lines and traction networks of various designs could be determined,the EMF levels at substations can be calculated,and the influence of metal structures located near traction networks,such as pedestrian crossings at railway stations,can be considered.
文摘【目的】基于猪极端饲料报酬表型,利用靶向切割标签技术(cleavage under targets and tagmentation,CUT&Tag)构建H3K27ac差异图谱,鉴定关联的启动子、增强子和关联候选基因,为猪饲料报酬解析提供基础数据。【方法】从209头杜洛克猪中筛选饲料报酬表型差异最大的4头个体分别组成低剩余采食量组(L组,n=2)和高剩余采食量组(H组,n=2)。利用CUT&Tag技术,以H3K27ac作为活性启动子和增强子的表观遗传标记对4头个体的肝脏组织进行全基因组扫描,鉴定关联启动子、增强子和候选基因,并进一步采用real-time quantitative PCR(RT-qPCR)对重要基因进行验证。【结果】共鉴定出47271个H3K27ac峰,包括15739个潜在启动子和31532个推定增强子,大部分的H3K27ac峰位于近端启动子区域。根据H3K27ac全基因的分布情况和作用特点,发现3087个差异峰(对应2188个基因),其中867个H3K27ac峰(对应664个基因)富集在H组,2220个H3K27ac峰(对应1575个基因)富集在L组。GO和KEGG结果发现H3K27ac增强子可能是通过影响胆汁酸代谢、淋巴细胞代谢和NF-κB通路来调节饲料报酬。RT-qPCR结果显示,与H组相比,DIAPH3、DPYD、FTO、TCF7L2、ABCC2、ABCC11、RXRA和ABCG8在L组中显著上调(P<0.05),而PAX5、GRHPR、NFATC1、CARD11、BLNK和LYN在L组中显著下调(P<0.05)。【结论】本研究成功生成了具有极端RFI差异的杜洛克猪肝脏组织中的H3K27ac差异图谱以及相关数据。基于该图谱鉴定和验证了关联候选基因,为进一步解析启动子和增强子调控饲料报酬的分子机制提供了基础数据。
