电压暂降是影响现代电网最为突出的电能质量问题之一,在进行大范围高压系统电压暂降监测时,必须考虑到含储能元件的电容式电压互感器(capacitor voltage transformer,CVT)所造成的不利影响。根据CVT结构推导了其测量电压暂降的误差并指...电压暂降是影响现代电网最为突出的电能质量问题之一,在进行大范围高压系统电压暂降监测时,必须考虑到含储能元件的电容式电压互感器(capacitor voltage transformer,CVT)所造成的不利影响。根据CVT结构推导了其测量电压暂降的误差并指出了影响该误差的内外部因素,而后构建了仿真模型,详细研究了暂降初相角、残余电压、CVT参数及负荷对电压暂降持续时间、暂降幅值以及相位跳变等特征量的影响及敏感度,最后提出一种基于虚拟阻抗补偿的CVT电压暂降测量误差校正方法,消除了电压暂降不确定性造成的测量误差多样性问题,仿真结果表明该方法的有效性,为普遍采用CVT的高压系统电压暂降准确测量提供了可行的校正方案。展开更多
Pr-doped metal oxide polycrystalline transparent ceramics are highly desirable for photothermal window systems served in extreme environments;however,obtaining efficient photoluminescence(PL)together with high transpa...Pr-doped metal oxide polycrystalline transparent ceramics are highly desirable for photothermal window systems served in extreme environments;however,obtaining efficient photoluminescence(PL)together with high transparency in these ceramics is still posing serious challenges,which undoubtedly limits their applications.Here,Pr-doped Y_(2)Zr_(2)O_(7)(YZO)transparent ceramics,as an illustrative example,are prepared by a solid-state reaction and vacuum sintering method.Owing to the elimination of defect clusters[Pr_(Y)^(4+)-O^(2-)Pr_(Y)^(4+)]and[Pr_(Y)^(4+)-e′]without the introduction of impurities and additional defects,the fabricated YZO:Pr ceramics exhibit high transparency(74%)and efficient PL(39-fold enhanced)after air annealing plus vacuum re-annealing treatment.Moreover,upon 295/450 nm excitation,the emission bands(blue,green,red,and dark red)from YZO:Pr ceramics present different temperature-dependent properties due to the thermalquenching channel generated by the intervalence charge transfer(IVCT)state between Pr_(Y)^(4+)and Zr^(4+)ions.Furthermore,a self-calibrated temperature feedback window with the same fluorescence intensity ratio(FIR)model(I_(613)/I_(503),where I represents the intensity)under different excitation light sources(295 and 450 nm)is designed.The developed photothermal window operated in a wide temperature range(303-663 K)shows relatively high sensitivities(absolute sensitivity(Sa)and relative sensitivity(S)reach 0.008 K^(-1)at 663 K and 0.47%K^(-1)at 363 K,respectively),high repeatability(>98%),and low temperature uncertainty(T<3.2 K).This work presents a paradigm for achieving enhanced PL along with elevated transparency of lanthanide(Ln)-doped ceramics through vacuum re-annealing treatment engineering and demonstrates their promising potential for photothermal window systems.展开更多
Ultraviolet(UV)radiation poses risks to both human health and organics.In response to the urgent demand for UV-shielding across various applications,extensive endeavors have been dedicated to developing UV-shielding m...Ultraviolet(UV)radiation poses risks to both human health and organics.In response to the urgent demand for UV-shielding across various applications,extensive endeavors have been dedicated to developing UV-shielding materials spanning from wide-bandgap semiconductors to organo-inorganic composite films.However,existing UV shielding materials,though suitable for daily use,cannot meet the demands of extreme conditions.In this work,we incorporated CeO_(2)as a UV absorber into Y_(2)O_(3)transparent ceramics for UV-shielding.The effect of CeO_(2)concentration on the optical,mechanical,and thermal properties of Y_(2)O_(3)ceramics was systematically investigated.These findings indicate that CeO_(2)serves not only as a UV absorber but also as an effective sintering aid for Y_(2)O_(3)transparent ceramics.The 5 at%Ce-doped Y_(2)O_(3)transparent ceramics exhibit the optimal optical quality,with in-line transmittance of~77%at 800 nm.The introduction of Ce shifted the UV cutoff edge of Y_(2)O_(3)transparent ceramics from 250 to 375 nm,which was attributed to the visible band absorption of Ce^(4+).This shift grants UV shielding capabilities to Y_(2)O_(3)transparent ceramics,resulting in 100%shielding for ultraviolet C(UVC,100-280 nm)and ultraviolet B(UVB,280-320 nm)and~95%shielding for ultraviolet A(UVA,320-400 nm).The service stability(optical properties)under various corrosive conditions(acid,alkali,UV irradiation,and high temperature)was investigated,confirming the excellent stability of this transparent ceramic UV-shielding material.A comparison of the performance parameters of transparent ceramics with those of traditional UV shielding materials such as glasses,films,and coatings was conducted.Our work provides innovative design concepts and an effective solution for UVshielding materials for extreme conditions.展开更多
This paper studies the method for measuring the loop resistance of GIS conductor pole based on the super capacitor producing impulse current up to several thousand amperes. This method overcomes the limitations of con...This paper studies the method for measuring the loop resistance of GIS conductor pole based on the super capacitor producing impulse current up to several thousand amperes. This method overcomes the limitations of conventional diagnostic method. Typical GIS conductor poles are chosen. Based on FEA and lab tests, the effect of different forms of current and contact condition, relationship between the temperature of contact and the loop resistance is researched. In full- scale testing under realistic operating conditions on the new 220 kV GIS using prototype instrumentation a very good sensitivity in an early stage was obtained.展开更多
Bacterial and chemical contaminations of drinking water imperil the health of people.A reactive species injection method is presented for sterilizing drinking water.To produce reactive species,a gas phase surface disc...Bacterial and chemical contaminations of drinking water imperil the health of people.A reactive species injection method is presented for sterilizing drinking water.To produce reactive species,a gas phase surface discharge reactor(SDR)is designed:a spiral stainless steel wire attached on the inside wall of a quartz glass tube is used as the high voltage electrode,and the drinking water is the ground electrode.The performance and mechanisms of the method in inactivating of Escherichia coli(E.coli)are analyzed.Experimental results show that 500 mL E.coli-contaminated drinking water(108CFU/mL)is completely sterilized within 4 min.Based on the scanning electron microscope(SEM)analysis,there were plasma-induced cell structure damages of the E.coli in the sterilized water,and the damage resulted in the leakage of protein,which was proved by chemical analyses.Meanwhile,the heating effect concomitantly generated by discharge plasma does not influence E.coli inactivation,and the contribution of direct ultraviolet(UV)irradiation could be neglected too.The ozone generated by SDR and the hydroxyl radicals(·OH)subsequently generated in drinking water play the decisive roles in E.coli inactivation because these reactive species cause the cell rupture.展开更多
Hetero-element doped lithium orthosilicates have been considered as advanced tritium breeders due to the superior performances.In this work,Li_(4)Si_(1-x)Ti_(x)O_(4) ceramics were prepared by proprietary hydrothermal ...Hetero-element doped lithium orthosilicates have been considered as advanced tritium breeders due to the superior performances.In this work,Li_(4)Si_(1-x)Ti_(x)O_(4) ceramics were prepared by proprietary hydrothermal process and multistage reactive sintering.The reaction mechanism of Li_(4)Si_(1-x)Ti_(x)O_(4) was put forward.XRD and SEM analyses indicate that insertion of Ti leads to lattice expansion,which promotes the grain growth and changes the fracture mode.The compressive tests show that the crush load increases almost four times by increasing x from 0 to 0.2.However,the thermal conductivity and ionic conductivity are the best when x=0.05 and x=0.1,respectively.Thermal cycling stability of Li_(4)Si_(1-x)Ti_(x)O_(4) pebbles was further appraised through investigating the changes of microstructure and crush load.After undergoing thermal cycling,the Li_(4)Si_(1-x)Ti_(x)O_(4) still show higher crush load compared with Li_(4)SiO_(4),despite Ti segregation in some samples.The x=0.05 sample exhibits excellent thermal cycling stability.In summary,proper amount of Ti doping can improve the crush load,thermal and ionic conductivity,and thermal cycling stability of Li_(4)SiO_(4).展开更多
文摘电压暂降是影响现代电网最为突出的电能质量问题之一,在进行大范围高压系统电压暂降监测时,必须考虑到含储能元件的电容式电压互感器(capacitor voltage transformer,CVT)所造成的不利影响。根据CVT结构推导了其测量电压暂降的误差并指出了影响该误差的内外部因素,而后构建了仿真模型,详细研究了暂降初相角、残余电压、CVT参数及负荷对电压暂降持续时间、暂降幅值以及相位跳变等特征量的影响及敏感度,最后提出一种基于虚拟阻抗补偿的CVT电压暂降测量误差校正方法,消除了电压暂降不确定性造成的测量误差多样性问题,仿真结果表明该方法的有效性,为普遍采用CVT的高压系统电压暂降准确测量提供了可行的校正方案。
基金supported by the National Natural Science Foundation of China(U21A20441)the Nuclear Power Development Programme,the Key Research and Development Program of Sichuan Province(2021YFG0375)+2 种基金the Key Science and Technology Project of Sichuan Province(2020ZDZX0012)the Science and Technology Planning Project of Dazhou(21DWHZ0005)the Cooperation Project of Sichuan University and Dazhou(2021CDDZ-02).
文摘Pr-doped metal oxide polycrystalline transparent ceramics are highly desirable for photothermal window systems served in extreme environments;however,obtaining efficient photoluminescence(PL)together with high transparency in these ceramics is still posing serious challenges,which undoubtedly limits their applications.Here,Pr-doped Y_(2)Zr_(2)O_(7)(YZO)transparent ceramics,as an illustrative example,are prepared by a solid-state reaction and vacuum sintering method.Owing to the elimination of defect clusters[Pr_(Y)^(4+)-O^(2-)Pr_(Y)^(4+)]and[Pr_(Y)^(4+)-e′]without the introduction of impurities and additional defects,the fabricated YZO:Pr ceramics exhibit high transparency(74%)and efficient PL(39-fold enhanced)after air annealing plus vacuum re-annealing treatment.Moreover,upon 295/450 nm excitation,the emission bands(blue,green,red,and dark red)from YZO:Pr ceramics present different temperature-dependent properties due to the thermalquenching channel generated by the intervalence charge transfer(IVCT)state between Pr_(Y)^(4+)and Zr^(4+)ions.Furthermore,a self-calibrated temperature feedback window with the same fluorescence intensity ratio(FIR)model(I_(613)/I_(503),where I represents the intensity)under different excitation light sources(295 and 450 nm)is designed.The developed photothermal window operated in a wide temperature range(303-663 K)shows relatively high sensitivities(absolute sensitivity(Sa)and relative sensitivity(S)reach 0.008 K^(-1)at 663 K and 0.47%K^(-1)at 363 K,respectively),high repeatability(>98%),and low temperature uncertainty(T<3.2 K).This work presents a paradigm for achieving enhanced PL along with elevated transparency of lanthanide(Ln)-doped ceramics through vacuum re-annealing treatment engineering and demonstrates their promising potential for photothermal window systems.
基金funded by the National Natural Science Foundation of China(Nos.U21A20441 and U22B2070).
文摘Ultraviolet(UV)radiation poses risks to both human health and organics.In response to the urgent demand for UV-shielding across various applications,extensive endeavors have been dedicated to developing UV-shielding materials spanning from wide-bandgap semiconductors to organo-inorganic composite films.However,existing UV shielding materials,though suitable for daily use,cannot meet the demands of extreme conditions.In this work,we incorporated CeO_(2)as a UV absorber into Y_(2)O_(3)transparent ceramics for UV-shielding.The effect of CeO_(2)concentration on the optical,mechanical,and thermal properties of Y_(2)O_(3)ceramics was systematically investigated.These findings indicate that CeO_(2)serves not only as a UV absorber but also as an effective sintering aid for Y_(2)O_(3)transparent ceramics.The 5 at%Ce-doped Y_(2)O_(3)transparent ceramics exhibit the optimal optical quality,with in-line transmittance of~77%at 800 nm.The introduction of Ce shifted the UV cutoff edge of Y_(2)O_(3)transparent ceramics from 250 to 375 nm,which was attributed to the visible band absorption of Ce^(4+).This shift grants UV shielding capabilities to Y_(2)O_(3)transparent ceramics,resulting in 100%shielding for ultraviolet C(UVC,100-280 nm)and ultraviolet B(UVB,280-320 nm)and~95%shielding for ultraviolet A(UVA,320-400 nm).The service stability(optical properties)under various corrosive conditions(acid,alkali,UV irradiation,and high temperature)was investigated,confirming the excellent stability of this transparent ceramic UV-shielding material.A comparison of the performance parameters of transparent ceramics with those of traditional UV shielding materials such as glasses,films,and coatings was conducted.Our work provides innovative design concepts and an effective solution for UVshielding materials for extreme conditions.
文摘This paper studies the method for measuring the loop resistance of GIS conductor pole based on the super capacitor producing impulse current up to several thousand amperes. This method overcomes the limitations of conventional diagnostic method. Typical GIS conductor poles are chosen. Based on FEA and lab tests, the effect of different forms of current and contact condition, relationship between the temperature of contact and the loop resistance is researched. In full- scale testing under realistic operating conditions on the new 220 kV GIS using prototype instrumentation a very good sensitivity in an early stage was obtained.
基金Project supported by Ministry of Science and Technology of China （2008AA06Z308）, National Natural Science Foundation of China （40901150）, Joint Fund of the National Natural Science Foundation of China （U0970166）, Doctoral Program Foundation of Institutions of Higher Education of China （20070141004）, Program for Liaoning Excel- lent Talents in University of China （2009R09）, Fundamental Research Fund for the Central Universities （DUT12RC（3）12）.
文摘Bacterial and chemical contaminations of drinking water imperil the health of people.A reactive species injection method is presented for sterilizing drinking water.To produce reactive species,a gas phase surface discharge reactor(SDR)is designed:a spiral stainless steel wire attached on the inside wall of a quartz glass tube is used as the high voltage electrode,and the drinking water is the ground electrode.The performance and mechanisms of the method in inactivating of Escherichia coli(E.coli)are analyzed.Experimental results show that 500 mL E.coli-contaminated drinking water(108CFU/mL)is completely sterilized within 4 min.Based on the scanning electron microscope(SEM)analysis,there were plasma-induced cell structure damages of the E.coli in the sterilized water,and the damage resulted in the leakage of protein,which was proved by chemical analyses.Meanwhile,the heating effect concomitantly generated by discharge plasma does not influence E.coli inactivation,and the contribution of direct ultraviolet(UV)irradiation could be neglected too.The ozone generated by SDR and the hydroxyl radicals(·OH)subsequently generated in drinking water play the decisive roles in E.coli inactivation because these reactive species cause the cell rupture.
基金supported by National Natural Science Foundation of China(No.51802257)Natural Science Foundation of Shaanxi Provincial Department of Education(18JK0570)China Postdoctoral Science Foundation(2019M663788).
文摘Hetero-element doped lithium orthosilicates have been considered as advanced tritium breeders due to the superior performances.In this work,Li_(4)Si_(1-x)Ti_(x)O_(4) ceramics were prepared by proprietary hydrothermal process and multistage reactive sintering.The reaction mechanism of Li_(4)Si_(1-x)Ti_(x)O_(4) was put forward.XRD and SEM analyses indicate that insertion of Ti leads to lattice expansion,which promotes the grain growth and changes the fracture mode.The compressive tests show that the crush load increases almost four times by increasing x from 0 to 0.2.However,the thermal conductivity and ionic conductivity are the best when x=0.05 and x=0.1,respectively.Thermal cycling stability of Li_(4)Si_(1-x)Ti_(x)O_(4) pebbles was further appraised through investigating the changes of microstructure and crush load.After undergoing thermal cycling,the Li_(4)Si_(1-x)Ti_(x)O_(4) still show higher crush load compared with Li_(4)SiO_(4),despite Ti segregation in some samples.The x=0.05 sample exhibits excellent thermal cycling stability.In summary,proper amount of Ti doping can improve the crush load,thermal and ionic conductivity,and thermal cycling stability of Li_(4)SiO_(4).
