针对新能源并网的主动支撑应用需求问题,选取三相全桥AC-DC变换器加双有源桥(dual active bridge,DAB)变换器的两级式结构作为研究对象。在器件寄生电容的影响下,DAB变换器会面临软开关难以实现的问题;且在宽电压范围应用场合下,传统的...针对新能源并网的主动支撑应用需求问题,选取三相全桥AC-DC变换器加双有源桥(dual active bridge,DAB)变换器的两级式结构作为研究对象。在器件寄生电容的影响下,DAB变换器会面临软开关难以实现的问题;且在宽电压范围应用场合下,传统的拓展移相(extend phase shift,EPS)控制在远离单位电压增益点时会带来较大无功环流问题。因此,提出一种拓扑结构及其调制方法,通过添加激磁电感来注入额外的激磁电流,从而保证DAB变换器的全负载范围软开关实现,同时通过对传统EPS控制进行改进,保证宽电压范围下的高效率传能。最后搭建一个20 kW全SiC器件的实验样机,对装置进行稳态测试及软开关性能测试,验证了所提方法的有效性。展开更多
Photocatalytic degradation of volatile organic compounds(VOCs)is a significant applying aspect of pho-tocatalysis.Both the modulation of photocatalysts and the rational dispersion of them on supports are key for solar...Photocatalytic degradation of volatile organic compounds(VOCs)is a significant applying aspect of pho-tocatalysis.Both the modulation of photocatalysts and the rational dispersion of them on supports are key for solar-driven VOC degradation.Conventional batch-type photoreactors have low efficiency while continuous-flow photoreactors suffer from the problem of incomplete removal of VOCs.Herein,aiming for continuous and complete degradation of toluene gas as the target contaminant,continuous-flow pho-tocatalytic degradation reactors were made by adhering the vanadium and nitrogen codoped TiO_(2)on honeycomb ceramics(V/N-TiO_(2)@HC)by a simple sol-gel method.In such a reactor,the rich ordered pores in the HC accelerate mass transport of toluene,and the introduction of V/N dopants narrows the bandgap and widens the light absorption range of TiO_(2),together resulting in continuous and nearly-complete pho-tocatalytic degradation of toluene.The unique and stable structure of HC allows the photocatalysts to be reused.The degradation rate of toluene gas can reach 97.8%,and after 24 rounds of photocatalytic degra-dation,there is still a degradation rate of 96.7%.The impacts of loading times and gaseous flow rate on the photocatalytic performance of V/N-TiO_(2)@HC are studied in detail.Our study provides a practical so-lution for the continuous and complete photocatalytic degradation of VOCs and opens a new application field for HC.展开更多
WC-10Co cemented carbides with finer WC and narrower grain size distributions are produced by using(Cr,V)_(2)(C,N)as grain growth inhibitors.As a result,with the increase of(Cr_(0.9),V_(0.1))_(2)(C,N)and(V_(0.9),Cr_(0...WC-10Co cemented carbides with finer WC and narrower grain size distributions are produced by using(Cr,V)_(2)(C,N)as grain growth inhibitors.As a result,with the increase of(Cr_(0.9),V_(0.1))_(2)(C,N)and(V_(0.9),Cr_(0.1))_(2)(C,N),the grains size of WC and mean free path of Co phase decrease,and adjacency of WC increases.Refinement and homogenization of grains enhance the transverse rupture strength(TRS)and the hardness.Meanwhile,the deflection and bridging of cracks keep the fracture toughness at a respectable level.The WC-10Co-0.6(Cr_(0.9),V_(0.1))_(2)(C,N)-0.025(V_(0.9),Cr_(0.1))_(2)(C,N)cemented carbides exhibit excellent comprehensive mechanical properties with the TRS of 4602.6 MPa,hardness of 1835 kg/mm^(2),and fracture toughness of 10.39 MPa·m^(1/2),respectively.However,the large pores are caused by excess N larger than 0.03 wt%and deteriorates the mechanical properties.We provide a new approach to WC-Co cemented carbides preparation with a narrow grain size distribution by adding novel grain growth inhibitors.展开更多
蜂窝车联网(cellular vehicle to everything,C-V2X)是智能交通系统的关键技术之一,车辆通过与周围的信息实体实时交换信息以实现保障城市交通安全、提高城市交通效率等目的,实现V2X通信的基本需求。在NR-V2X定义的场景中,它还将支持自...蜂窝车联网(cellular vehicle to everything,C-V2X)是智能交通系统的关键技术之一,车辆通过与周围的信息实体实时交换信息以实现保障城市交通安全、提高城市交通效率等目的,实现V2X通信的基本需求。在NR-V2X定义的场景中,它还将支持自动驾驶、远程驾驶、车辆编队、扩展传感四大类先进V2X服务。通过OPNET搭建5G-V2X系统级仿真平台,针对基于PC5接口和Uu接口的车联网通信两大通信模式对5G蜂窝车联网的系统性能进行分析研究,给出相应的性能分析和评估结果,并提出改进建议,对5G蜂窝车联网的研究方向和实际系统部署都具有重要的指导作用。展开更多
A new complex[Ni(en) 2V 6O 14] n was hydrothermally synthesized and characterized by 2-dimensional vanadium oxide framework pillared by Ni(en) 2 group. Single crystal X-ray analysis indicates that this compound crysta...A new complex[Ni(en) 2V 6O 14] n was hydrothermally synthesized and characterized by 2-dimensional vanadium oxide framework pillared by Ni(en) 2 group. Single crystal X-ray analysis indicates that this compound crystallizes in monoclinic system, space group P2 1/c with a= 0.892 17(18) nm, b= 1.711 1(3) nm, c=0.662 73(13) nm, β=111.58(3)°, V=0.940 8(3) nm 3, Z=2, D c= 2.501 g/cm 3, R=0.042 3, wR=0.060 9, S=1.006.展开更多
基金financial support of this work from the Key Research and Development Project of Gansu Province(No.20YF3GA008)the Lanzhou Science and Technology Lanzhou Science and Technology Bureau Project(No.2022-2-15)+1 种基金Gansu Provincial Science and Technology Commissioner Special Project(No.22CX8GA106)Key Research and Development Project of Gansu Natural Energy Institute(No.2019YF-02).
文摘Photocatalytic degradation of volatile organic compounds(VOCs)is a significant applying aspect of pho-tocatalysis.Both the modulation of photocatalysts and the rational dispersion of them on supports are key for solar-driven VOC degradation.Conventional batch-type photoreactors have low efficiency while continuous-flow photoreactors suffer from the problem of incomplete removal of VOCs.Herein,aiming for continuous and complete degradation of toluene gas as the target contaminant,continuous-flow pho-tocatalytic degradation reactors were made by adhering the vanadium and nitrogen codoped TiO_(2)on honeycomb ceramics(V/N-TiO_(2)@HC)by a simple sol-gel method.In such a reactor,the rich ordered pores in the HC accelerate mass transport of toluene,and the introduction of V/N dopants narrows the bandgap and widens the light absorption range of TiO_(2),together resulting in continuous and nearly-complete pho-tocatalytic degradation of toluene.The unique and stable structure of HC allows the photocatalysts to be reused.The degradation rate of toluene gas can reach 97.8%,and after 24 rounds of photocatalytic degra-dation,there is still a degradation rate of 96.7%.The impacts of loading times and gaseous flow rate on the photocatalytic performance of V/N-TiO_(2)@HC are studied in detail.Our study provides a practical so-lution for the continuous and complete photocatalytic degradation of VOCs and opens a new application field for HC.
基金Funded by the 2021 Strategic Cooperation Project between Sichuan University and The People's Government of Zigong(No.2021CDZG-1)Major Science and Technology Research Projects of Panxi,Sichuan Province(No.2022PXZB-04)。
文摘WC-10Co cemented carbides with finer WC and narrower grain size distributions are produced by using(Cr,V)_(2)(C,N)as grain growth inhibitors.As a result,with the increase of(Cr_(0.9),V_(0.1))_(2)(C,N)and(V_(0.9),Cr_(0.1))_(2)(C,N),the grains size of WC and mean free path of Co phase decrease,and adjacency of WC increases.Refinement and homogenization of grains enhance the transverse rupture strength(TRS)and the hardness.Meanwhile,the deflection and bridging of cracks keep the fracture toughness at a respectable level.The WC-10Co-0.6(Cr_(0.9),V_(0.1))_(2)(C,N)-0.025(V_(0.9),Cr_(0.1))_(2)(C,N)cemented carbides exhibit excellent comprehensive mechanical properties with the TRS of 4602.6 MPa,hardness of 1835 kg/mm^(2),and fracture toughness of 10.39 MPa·m^(1/2),respectively.However,the large pores are caused by excess N larger than 0.03 wt%and deteriorates the mechanical properties.We provide a new approach to WC-Co cemented carbides preparation with a narrow grain size distribution by adding novel grain growth inhibitors.
文摘蜂窝车联网(cellular vehicle to everything,C-V2X)是智能交通系统的关键技术之一,车辆通过与周围的信息实体实时交换信息以实现保障城市交通安全、提高城市交通效率等目的,实现V2X通信的基本需求。在NR-V2X定义的场景中,它还将支持自动驾驶、远程驾驶、车辆编队、扩展传感四大类先进V2X服务。通过OPNET搭建5G-V2X系统级仿真平台,针对基于PC5接口和Uu接口的车联网通信两大通信模式对5G蜂窝车联网的系统性能进行分析研究,给出相应的性能分析和评估结果,并提出改进建议,对5G蜂窝车联网的研究方向和实际系统部署都具有重要的指导作用。
文摘A new complex[Ni(en) 2V 6O 14] n was hydrothermally synthesized and characterized by 2-dimensional vanadium oxide framework pillared by Ni(en) 2 group. Single crystal X-ray analysis indicates that this compound crystallizes in monoclinic system, space group P2 1/c with a= 0.892 17(18) nm, b= 1.711 1(3) nm, c=0.662 73(13) nm, β=111.58(3)°, V=0.940 8(3) nm 3, Z=2, D c= 2.501 g/cm 3, R=0.042 3, wR=0.060 9, S=1.006.
