Objective:Saccades accompanied by normal gain in video head impulse tests(vHIT)are often observed in patients with vestibular migraine(VM).However,they are not considered as an independent indicator,reducing their uti...Objective:Saccades accompanied by normal gain in video head impulse tests(vHIT)are often observed in patients with vestibular migraine(VM).However,they are not considered as an independent indicator,reducing their utility in diagnosing VM.To better understand clinical features of VM,it is necessary to understand raw saccades data.Methods:Fourteen patients with confirmed VM,45 patients with probable VM(p-VM)and 14 agematched healthy volunteers were included in this study.Clinical findings related to spontaneous nystagmus(SN),positional nystagmus(PN),head-shaking nystagmus(HSN),caloric test and vHIT were recorded.Raw saccades data were exported and numbered by their sequences,and their features analyzed.Results:VM patients showed no SN,PN or HSN,and less than half of them showed unilateral weakness(UW)on caloric test.The first saccades from lateral semicircular canal stimulation were the most predominant for both left and right sides.Neither velocity nor time parameters were significantly different when compared between the two sides.Most VM patients(86%)exhibited small saccades,around 35%of the head peak velocity,with a latency of 200e400 ms.Characteristics of saccades were similar in patients with p-VM.Only four normal subjects showed saccades,all unilateral and seemingly random.Conclusions:Small saccades involving bilateral semicircular canals with a scattered distribution pattern are common in patients with VM and p-VM.展开更多
In this study,a high specific impulse Hall thruster,HEP-140 MF,having a high discharge voltage,was used to accelerate ions.We aimed to obtain a high specific impulse and an acceleration zone moving downstream toward t...In this study,a high specific impulse Hall thruster,HEP-140 MF,having a high discharge voltage,was used to accelerate ions.We aimed to obtain a high specific impulse and an acceleration zone moving downstream toward the channel exit to reduce wall sputtering erosion of the walls of the discharge channel,hence ensuring an enhanced lifetime.To study the lifetime characteristics of the high specific impulse Hall thruster,a life test was performed on the HEP-140 MF thruster for the first time,and performance parameters,such as thrust,specific impulse,and efficiency,were measured.Changes in the performance parameters and evolutions in the surface profiles of the discharge channel wall were summarized.The reasons contributing to these changes during the life test were analyzed.Moreover,the accelerated life test method was validated on the HEP-140 MF.展开更多
Background:Saccades are often observed on video head impulse tests(vHIT)in patients with Meniere's Disease(MD)and Vestibular Migraine(VM).However,their saccadic features are not fully described.Objective:This stud...Background:Saccades are often observed on video head impulse tests(vHIT)in patients with Meniere's Disease(MD)and Vestibular Migraine(VM).However,their saccadic features are not fully described.Objective:This study aims to identify the saccades characteristics of MD and VM.Methods:75 VM patients and 103 definite unilateral MD patients were enrolled in this study.First raw saccades were exported and analyzed.The VM patients were divided into left and right based on their ears,while the MD patients were separated into affected and unaffected subgroups based on their audiograms and symptoms.Results:The MD patients have more saccades on the affected side(85%vs.69%),and saccade velocity is more consistent than the contralateral side(shown by the coefficient of variation).The saccades occurrence rates on both sides are similar in VM(77%vs.76%),as are other saccadic parameters.The MD patients have more significant inter-aural differences than the VM patients,manifested in higher velocity(p-value 0.000),earlier arriving(p-value 0.010),and more time-domain gathered(p-value 0.003)on the affected side.Conclusions:Bilateral saccades are commonly observed in MD and VM.In contrast to MD,saccades on VM are subtle,scattered,and late-arrived.Furthermore,the MD patients showed inconsistent saccadic distribution with more velocity-uniform saccades on the affected side.展开更多
Economically and effectively managing the risk of landslide-generated impulse waves(LGIWs)presents a significant challenge following the impoundment of newly constructed reservoirs in western China.To address this iss...Economically and effectively managing the risk of landslide-generated impulse waves(LGIWs)presents a significant challenge following the impoundment of newly constructed reservoirs in western China.To address this issue,we selected the Wangjiashan(WJS)landslide in the Baihetan Reservoir area as a case study to evaluate LGIW hazards and develop corresponding mitigation strategies.Using 2D physical model tests and 3D numerical simulations,we established a 3D hazard assessment method for LGIWs based on 2D experimental results.This method confirmed the effectiveness of slope-cutting engineering in mitigating LGIW hazards.Based on this assessment framework,we proposed a novel approach for LGIW risk reduction.The results showed that the maximum wave amplitude reached 19.64 m in the Jinsha River channel,and the maximum run-up was 11.5 m in the XiangBiLing(XBL)community,indicating a substantial LGIW threat to the area.By reducing the rear edge of the sliding mass to 920 m above sea level(asl),the LGIW risk to the XBL community could be lowered to a tolerable level.Compared with traditional landslide prevention and control measures,the proposed mitigation scheme can reduce excavation costs by approximately 37 million CNY,making it a more scientifically sound and economically feasible solution.We explored the concept and the implementation of LGIW risk mitigation in depth,offering new insights for global LGIW risk management.This case study enhances our understanding of LGIW hazard prevention and provides valuable guidance for policymaking and engineering practices in similar geological settings worldwide.展开更多
Objective To compare the performances among three different systems for video head impulse test(vHIT),and to identify an optimal target angle for precisely evaluating the function of vertical semicircular canals in vH...Objective To compare the performances among three different systems for video head impulse test(vHIT),and to identify an optimal target angle for precisely evaluating the function of vertical semicircular canals in vHIT.Methods A two-center prospective study was done.Participants were sit 1.2 m away from the wall in a noise-proved room that dedicated for vHIT experiments.During the comparison experiments,similar settings were ensured in both hospitals,with the same distance to wall and angle of staring.For each equipment,the procedures followed the developers’recommendations.The same examiner performed the comparison between two systems in one location.For the eye-position projects,targets were placed on the wall sequentially at the pre-marked lines for different angles.For the comparison projects,9 and 13 participants were recruited,respectively.Any participant with otologic or vestibular disorders was excluded.A total of 26 healthy participants were recruited in the eye-position experiments,16 of which were further involved in inter-examiner tests.Results Our evaluations of three different systems showed that a new vHIT system,VertiGoggles®ZT-VNG-I(VG)performed as good as the long-tested Otometrics®ICS impulse(Oto)and EyeSeeCam®(ESC).During the comparison,we validated 25-degree,instead of right ahead at 0 degree,is a better place to set the targets when torsion was applied at vertical semicircular canal planes.Conclusion The new VG system is good for clinical practices.Furthermore,we proposed a new protocol to set the targets 25 degrees from right ahead after tilting head 45 degrees to evaluate vertical canals during vHIT.展开更多
Transient over voltages due to lightning and switching surges cause steep build-up of voltage on transmission lines and other electrical apparatus,like circuit breakers,transformers,insulators etc.Therefore it is nece...Transient over voltages due to lightning and switching surges cause steep build-up of voltage on transmission lines and other electrical apparatus,like circuit breakers,transformers,insulators etc.Therefore it is necessary for the GIS also to withstand such voltages without breakdown of Insulation.The system has to be tested under these conditions.Usually the GIS system operates on power frequency.Lightning Impulse Voltage of 1050 kV and Switching Impulse Voltage of 750 kV superimposed on Power frequency voltages of 75 kV,100 kV and 132 kV are applied to Single Phase Gas Insulated Busduct and the maximum movement of Aluminum,Copper and Silver particles is determined.The movement patterns are also determined with and without Monte Carlo Simulation for movement of particle in axial and radial directions.The results show that there is a sudden jump in the movement at the application of impulse on sine wave.This is because of high magnitude voltage of 1050 kV during 1.2/50 μs.Similar movement patterns of reduced maximum movement is observed for Switching Impulse superimposed on sine wave.The results are presented and analyzed.展开更多
A prototype of impulse thruster for radial thrust trajectory correction munitions is designed. It adopts semiconductor bridge (SCB) as ignition element,Ti/KClO4 (TK) as ignition charge and ammonium perchlorate/alumini...A prototype of impulse thruster for radial thrust trajectory correction munitions is designed. It adopts semiconductor bridge (SCB) as ignition element,Ti/KClO4 (TK) as ignition charge and ammonium perchlorate/aluminium (NA) or potassium picate/RDX (KR) as main charge. A thrust test device of impulse thruster is also designed. The output performance of the impulse thruster prototype is tested by the device. The tested results show that it can meet the safety requirements of 1A1W/5 min no-fire level and produce 0.2-0.6 N·s thrust impulse within 3ms of action time under certain test conditions; the corresponding ignition delay time is less than 0.5 ms.展开更多
Respiratory diseases,especially asthma,are common in children.While spirometry contributes to asthma diagnosis and management in older children,it has a limited role in younger children whom are often unable to perfor...Respiratory diseases,especially asthma,are common in children.While spirometry contributes to asthma diagnosis and management in older children,it has a limited role in younger children whom are often unable to perform forced expiratory manoeuvre.The development of novel diagnostic methods which require minimal effort,such as forced oscillation technique(FOT)is,therefore,a welcome and promising addition.FOT involves applying external,small amplitude oscillations to the respiratory system during tidal breathing.Therefore,it requires minimal effort and cooperation.The FOT has the potential to facilitate asthma diagnosis and management in preschool children by faciliting the objective measurement of baseline lung function and airway reactivity in children unable to successfully perform spirometry.Traditionally the use of FOT was limited to specialised centres.However,the availability of commercial equipment resulted in its use both in research and in clinical practice.In this article,we review the available literature on the use of FOT in childhood asthma.The technical aspects of FOT are described followed by a discussion of its practical aspects in the clinical field including the measurement of baseline lung function and associated reference ranges,bronchodilator responsiveness and bronchial hyperresponsiveness.We also highlight the difficulties and limitations that might be encountered and future research directions.展开更多
目的建立民航飞行学员视频头脉冲试验(video head impulse test,vHIT)正常参考值,为民航飞行学员前庭功能的准确评估提供参考依据。方法随机选取40例尚处于飞行理论学习阶段的民航飞行学员进行vHIT检测,对前庭-眼反射(vestibulo-ocular ...目的建立民航飞行学员视频头脉冲试验(video head impulse test,vHIT)正常参考值,为民航飞行学员前庭功能的准确评估提供参考依据。方法随机选取40例尚处于飞行理论学习阶段的民航飞行学员进行vHIT检测,对前庭-眼反射(vestibulo-ocular reflex,VOR)的平均增益值及各半规管之间的不对称比进行比较。结果40例民航飞行学员右侧水平、前、后半规管VOR增益值分别为1.05±0.07、0.92±0.13、0.81±0.09,左侧水平、前、后半规管VOR增益值分别为1.00±0.06、0.85±0.10、0.86±0.10,所有受试者均未见补偿性扫视。双侧水平、左前-右后、右前-左后半规管VOR增益值不对称比分别为5.56%±3.64%、9.65%±4.74%、8.68%±7.07%。结论本研究建立了民航飞行学员vHIT正常参考值,为民航飞行学员的选拔及前庭功能鉴定提供了客观依据。展开更多
目的了解与把握国内外BPPV研究的发展趋势和前沿,为将来进一步研究提供参考。方法分别从中国知网、万方数据知识服务平台、维普网及Web of Science Core Collection数据库中收集2004年1月1日至2023年12月31日发表的关于BPPV的期刊文章,...目的了解与把握国内外BPPV研究的发展趋势和前沿,为将来进一步研究提供参考。方法分别从中国知网、万方数据知识服务平台、维普网及Web of Science Core Collection数据库中收集2004年1月1日至2023年12月31日发表的关于BPPV的期刊文章,用文献计量软件对该领域进行多维度计量及可视化分析,确定该领域的研究热点和新趋势,以及作者、机构和期刊之间的合作和影响。结果共有717篇中文论文和212篇SCI论文被用于分析。该领域的文献以12.8%的年平均增长率逐渐增加,其中《临床耳鼻咽喉头颈外科杂志》发表的文章最多(n=167,占23.3%),其次是《中华耳科学杂志》(n=94,占13.1%)和《听力学及言语疾病杂志》(n=76,占10.6%);SCI中发文量最多的期刊是《Frontiers in Neurology》(n=44,占20.8%)。作者和机构方面,庄建华发表的中文论文最多,杨旭发表SCI论文最多,上海交通大学是国内该领域发表SCI论文最早且最多的机构(n=21)。该领域近年来的研究主要关键词为视频头脉冲试验、前庭性偏头痛、残余症状、残余头晕及焦虑等。到2023年仍持续突现的关键词包括视频头脉冲试验、残余头晕、儿童、焦虑、残余症状。结论视频头脉冲试验、残余头晕、儿童、焦虑等方面是目前BPPV研究的热点与趋势。展开更多
In recent years,more than 6 million room temperature vulcanized(RTV)silicone rubber coated cap and pin insulators with high mechanical ratings were used in ultra-high voltage transmission lines in China to improve pol...In recent years,more than 6 million room temperature vulcanized(RTV)silicone rubber coated cap and pin insulators with high mechanical ratings were used in ultra-high voltage transmission lines in China to improve pollution performance.However,the unexpected puncture phenomena of RTV coated insulators were exposed during steep-front impulse voltage tests;for instance,the steep-front impulse voltage test pass rate decreased to less than 50% for 550 kN glass insulators with RTV coatings.The steep-front impulse voltage test is the most effective method used to check the insulation quality of cap and pin insulators・This unexpected phenomenon once caused serious concerns to power utilities.In this paper,several possible factors that affect the puncture of insulators were analyzed.Then,the extent of the decline in the breakdown of the 550 kN glass cap and pin insulators with and without RTV coatings were studied.The initial puncture location was then found,and the developmental process of the arc on the insulator surface in steep-front impulse voltage tests was observed with an ultra-high-speed intensified charge coupled device camera.Lastly,a breakdown mechanism is proposed.The puncture phenomena of a RTV coated insulator in a steep-front impulse voltage test is essentially an electrical breakdown of the internal insulation・The RTV coating induces the close adherence of the arc to the surface of the insulator.Such closeness changes the arc development path on the insulator surface and facilitates easy breakdown in the shed weak part.All these factors result in a significant increase in the breakdown probability of RTV coated insulators in steepfront impulse voltage tests.展开更多
文摘Objective:Saccades accompanied by normal gain in video head impulse tests(vHIT)are often observed in patients with vestibular migraine(VM).However,they are not considered as an independent indicator,reducing their utility in diagnosing VM.To better understand clinical features of VM,it is necessary to understand raw saccades data.Methods:Fourteen patients with confirmed VM,45 patients with probable VM(p-VM)and 14 agematched healthy volunteers were included in this study.Clinical findings related to spontaneous nystagmus(SN),positional nystagmus(PN),head-shaking nystagmus(HSN),caloric test and vHIT were recorded.Raw saccades data were exported and numbered by their sequences,and their features analyzed.Results:VM patients showed no SN,PN or HSN,and less than half of them showed unilateral weakness(UW)on caloric test.The first saccades from lateral semicircular canal stimulation were the most predominant for both left and right sides.Neither velocity nor time parameters were significantly different when compared between the two sides.Most VM patients(86%)exhibited small saccades,around 35%of the head peak velocity,with a latency of 200e400 ms.Characteristics of saccades were similar in patients with p-VM.Only four normal subjects showed saccades,all unilateral and seemingly random.Conclusions:Small saccades involving bilateral semicircular canals with a scattered distribution pattern are common in patients with VM and p-VM.
基金supported by Space Advance Research program (No. D010509)National Natural Science Foundation of China (No. 51806011)National Defense Pre-Research Foundation of China (No. JSZL2016203C006)。
文摘In this study,a high specific impulse Hall thruster,HEP-140 MF,having a high discharge voltage,was used to accelerate ions.We aimed to obtain a high specific impulse and an acceleration zone moving downstream toward the channel exit to reduce wall sputtering erosion of the walls of the discharge channel,hence ensuring an enhanced lifetime.To study the lifetime characteristics of the high specific impulse Hall thruster,a life test was performed on the HEP-140 MF thruster for the first time,and performance parameters,such as thrust,specific impulse,and efficiency,were measured.Changes in the performance parameters and evolutions in the surface profiles of the discharge channel wall were summarized.The reasons contributing to these changes during the life test were analyzed.Moreover,the accelerated life test method was validated on the HEP-140 MF.
基金supported by grants from National Key Research and Development Program of China-part3(2020YFC2005203)Capital's Funds for Health Improvement and Research(No.2022-1-2023).
文摘Background:Saccades are often observed on video head impulse tests(vHIT)in patients with Meniere's Disease(MD)and Vestibular Migraine(VM).However,their saccadic features are not fully described.Objective:This study aims to identify the saccades characteristics of MD and VM.Methods:75 VM patients and 103 definite unilateral MD patients were enrolled in this study.First raw saccades were exported and analyzed.The VM patients were divided into left and right based on their ears,while the MD patients were separated into affected and unaffected subgroups based on their audiograms and symptoms.Results:The MD patients have more saccades on the affected side(85%vs.69%),and saccade velocity is more consistent than the contralateral side(shown by the coefficient of variation).The saccades occurrence rates on both sides are similar in VM(77%vs.76%),as are other saccadic parameters.The MD patients have more significant inter-aural differences than the VM patients,manifested in higher velocity(p-value 0.000),earlier arriving(p-value 0.010),and more time-domain gathered(p-value 0.003)on the affected side.Conclusions:Bilateral saccades are commonly observed in MD and VM.In contrast to MD,saccades on VM are subtle,scattered,and late-arrived.Furthermore,the MD patients showed inconsistent saccadic distribution with more velocity-uniform saccades on the affected side.
基金supported by the National Natural Science Foundation of China(No.U23A2045)the China Three Gorges Corporation(YM(BHT)/(22)022).
文摘Economically and effectively managing the risk of landslide-generated impulse waves(LGIWs)presents a significant challenge following the impoundment of newly constructed reservoirs in western China.To address this issue,we selected the Wangjiashan(WJS)landslide in the Baihetan Reservoir area as a case study to evaluate LGIW hazards and develop corresponding mitigation strategies.Using 2D physical model tests and 3D numerical simulations,we established a 3D hazard assessment method for LGIWs based on 2D experimental results.This method confirmed the effectiveness of slope-cutting engineering in mitigating LGIW hazards.Based on this assessment framework,we proposed a novel approach for LGIW risk reduction.The results showed that the maximum wave amplitude reached 19.64 m in the Jinsha River channel,and the maximum run-up was 11.5 m in the XiangBiLing(XBL)community,indicating a substantial LGIW threat to the area.By reducing the rear edge of the sliding mass to 920 m above sea level(asl),the LGIW risk to the XBL community could be lowered to a tolerable level.Compared with traditional landslide prevention and control measures,the proposed mitigation scheme can reduce excavation costs by approximately 37 million CNY,making it a more scientifically sound and economically feasible solution.We explored the concept and the implementation of LGIW risk mitigation in depth,offering new insights for global LGIW risk management.This case study enhances our understanding of LGIW hazard prevention and provides valuable guidance for policymaking and engineering practices in similar geological settings worldwide.
基金supported by grants from the National Science Foundation for Outstanding Young People(No.81922018)the Transformation and Industrialization of Scientific and Technological Achievements in Shanghai(No.18441904000)+3 种基金the National Natural Science Foundation of China(No.81771011)the National Natural Science Foundation of China Young Investigator Program(No.81800907)the Development Fund for Shanghai Talents(No.2017046)the Excellent Personnel Training Plan for the Shanghai Health System(No.2017Q003).
文摘Objective To compare the performances among three different systems for video head impulse test(vHIT),and to identify an optimal target angle for precisely evaluating the function of vertical semicircular canals in vHIT.Methods A two-center prospective study was done.Participants were sit 1.2 m away from the wall in a noise-proved room that dedicated for vHIT experiments.During the comparison experiments,similar settings were ensured in both hospitals,with the same distance to wall and angle of staring.For each equipment,the procedures followed the developers’recommendations.The same examiner performed the comparison between two systems in one location.For the eye-position projects,targets were placed on the wall sequentially at the pre-marked lines for different angles.For the comparison projects,9 and 13 participants were recruited,respectively.Any participant with otologic or vestibular disorders was excluded.A total of 26 healthy participants were recruited in the eye-position experiments,16 of which were further involved in inter-examiner tests.Results Our evaluations of three different systems showed that a new vHIT system,VertiGoggles®ZT-VNG-I(VG)performed as good as the long-tested Otometrics®ICS impulse(Oto)and EyeSeeCam®(ESC).During the comparison,we validated 25-degree,instead of right ahead at 0 degree,is a better place to set the targets when torsion was applied at vertical semicircular canal planes.Conclusion The new VG system is good for clinical practices.Furthermore,we proposed a new protocol to set the targets 25 degrees from right ahead after tilting head 45 degrees to evaluate vertical canals during vHIT.
文摘Transient over voltages due to lightning and switching surges cause steep build-up of voltage on transmission lines and other electrical apparatus,like circuit breakers,transformers,insulators etc.Therefore it is necessary for the GIS also to withstand such voltages without breakdown of Insulation.The system has to be tested under these conditions.Usually the GIS system operates on power frequency.Lightning Impulse Voltage of 1050 kV and Switching Impulse Voltage of 750 kV superimposed on Power frequency voltages of 75 kV,100 kV and 132 kV are applied to Single Phase Gas Insulated Busduct and the maximum movement of Aluminum,Copper and Silver particles is determined.The movement patterns are also determined with and without Monte Carlo Simulation for movement of particle in axial and radial directions.The results show that there is a sudden jump in the movement at the application of impulse on sine wave.This is because of high magnitude voltage of 1050 kV during 1.2/50 μs.Similar movement patterns of reduced maximum movement is observed for Switching Impulse superimposed on sine wave.The results are presented and analyzed.
基金the Ministerial Level Advanced Research Foundation (51305080302)
文摘A prototype of impulse thruster for radial thrust trajectory correction munitions is designed. It adopts semiconductor bridge (SCB) as ignition element,Ti/KClO4 (TK) as ignition charge and ammonium perchlorate/aluminium (NA) or potassium picate/RDX (KR) as main charge. A thrust test device of impulse thruster is also designed. The output performance of the impulse thruster prototype is tested by the device. The tested results show that it can meet the safety requirements of 1A1W/5 min no-fire level and produce 0.2-0.6 N·s thrust impulse within 3ms of action time under certain test conditions; the corresponding ignition delay time is less than 0.5 ms.
文摘Respiratory diseases,especially asthma,are common in children.While spirometry contributes to asthma diagnosis and management in older children,it has a limited role in younger children whom are often unable to perform forced expiratory manoeuvre.The development of novel diagnostic methods which require minimal effort,such as forced oscillation technique(FOT)is,therefore,a welcome and promising addition.FOT involves applying external,small amplitude oscillations to the respiratory system during tidal breathing.Therefore,it requires minimal effort and cooperation.The FOT has the potential to facilitate asthma diagnosis and management in preschool children by faciliting the objective measurement of baseline lung function and airway reactivity in children unable to successfully perform spirometry.Traditionally the use of FOT was limited to specialised centres.However,the availability of commercial equipment resulted in its use both in research and in clinical practice.In this article,we review the available literature on the use of FOT in childhood asthma.The technical aspects of FOT are described followed by a discussion of its practical aspects in the clinical field including the measurement of baseline lung function and associated reference ranges,bronchodilator responsiveness and bronchial hyperresponsiveness.We also highlight the difficulties and limitations that might be encountered and future research directions.
文摘目的建立民航飞行学员视频头脉冲试验(video head impulse test,vHIT)正常参考值,为民航飞行学员前庭功能的准确评估提供参考依据。方法随机选取40例尚处于飞行理论学习阶段的民航飞行学员进行vHIT检测,对前庭-眼反射(vestibulo-ocular reflex,VOR)的平均增益值及各半规管之间的不对称比进行比较。结果40例民航飞行学员右侧水平、前、后半规管VOR增益值分别为1.05±0.07、0.92±0.13、0.81±0.09,左侧水平、前、后半规管VOR增益值分别为1.00±0.06、0.85±0.10、0.86±0.10,所有受试者均未见补偿性扫视。双侧水平、左前-右后、右前-左后半规管VOR增益值不对称比分别为5.56%±3.64%、9.65%±4.74%、8.68%±7.07%。结论本研究建立了民航飞行学员vHIT正常参考值,为民航飞行学员的选拔及前庭功能鉴定提供了客观依据。
文摘目的了解与把握国内外BPPV研究的发展趋势和前沿,为将来进一步研究提供参考。方法分别从中国知网、万方数据知识服务平台、维普网及Web of Science Core Collection数据库中收集2004年1月1日至2023年12月31日发表的关于BPPV的期刊文章,用文献计量软件对该领域进行多维度计量及可视化分析,确定该领域的研究热点和新趋势,以及作者、机构和期刊之间的合作和影响。结果共有717篇中文论文和212篇SCI论文被用于分析。该领域的文献以12.8%的年平均增长率逐渐增加,其中《临床耳鼻咽喉头颈外科杂志》发表的文章最多(n=167,占23.3%),其次是《中华耳科学杂志》(n=94,占13.1%)和《听力学及言语疾病杂志》(n=76,占10.6%);SCI中发文量最多的期刊是《Frontiers in Neurology》(n=44,占20.8%)。作者和机构方面,庄建华发表的中文论文最多,杨旭发表SCI论文最多,上海交通大学是国内该领域发表SCI论文最早且最多的机构(n=21)。该领域近年来的研究主要关键词为视频头脉冲试验、前庭性偏头痛、残余症状、残余头晕及焦虑等。到2023年仍持续突现的关键词包括视频头脉冲试验、残余头晕、儿童、焦虑、残余症状。结论视频头脉冲试验、残余头晕、儿童、焦虑等方面是目前BPPV研究的热点与趋势。
基金supported by the National Natural Science Foundation of China(51577099).
文摘In recent years,more than 6 million room temperature vulcanized(RTV)silicone rubber coated cap and pin insulators with high mechanical ratings were used in ultra-high voltage transmission lines in China to improve pollution performance.However,the unexpected puncture phenomena of RTV coated insulators were exposed during steep-front impulse voltage tests;for instance,the steep-front impulse voltage test pass rate decreased to less than 50% for 550 kN glass insulators with RTV coatings.The steep-front impulse voltage test is the most effective method used to check the insulation quality of cap and pin insulators・This unexpected phenomenon once caused serious concerns to power utilities.In this paper,several possible factors that affect the puncture of insulators were analyzed.Then,the extent of the decline in the breakdown of the 550 kN glass cap and pin insulators with and without RTV coatings were studied.The initial puncture location was then found,and the developmental process of the arc on the insulator surface in steep-front impulse voltage tests was observed with an ultra-high-speed intensified charge coupled device camera.Lastly,a breakdown mechanism is proposed.The puncture phenomena of a RTV coated insulator in a steep-front impulse voltage test is essentially an electrical breakdown of the internal insulation・The RTV coating induces the close adherence of the arc to the surface of the insulator.Such closeness changes the arc development path on the insulator surface and facilitates easy breakdown in the shed weak part.All these factors result in a significant increase in the breakdown probability of RTV coated insulators in steepfront impulse voltage tests.
