3篇
您的检索式：作者名="Prem Ranjan"
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| 1 | Propagation and localisation of partial discharge in transformer bushing based on ultra-high frequency technique显示文摘As an essential component of power transformers,the detection and diagnosis of incipient partial discharge(PD)activities of bushings are of great significance.A 35-kV oil-impregnated paper(OIP)bushing is investigated.The bushing is modelled by coaxial theory and electromagnetic(EM)simulation.As the paths of PD-induced ultra-high frequency(UHF)signal propagating in the bushing are OIPs and oil gap,small attenuation during signal propagation is seen.Since OIP is composed of het-erogeneous media compared with pure oil,there will be relatively less UHF signal leakage from OIPs,whereas more leakage from the oil gap.This leakage provides the possibility of non-contact detection outside the bushing by UHF method.PD mea-surements with UHF method are carried out on the bushing.Then,the minimum energy method is used to extract time-difference-of-arrival(TDOA),and Chan al-gorithm is adopted to locate points of UHF signal radiation.High accuracy locating with a small error of 15 cm has been achieved.The contactless UHF method-based tests have demonstrated the effectiveness of online monitoring and locating of bushing PD. | Jun Jiang Judong Chen Jiansheng Li Xiaoping Yang Ricardo Albarracín-Sánchez Prem Ranjan Chaohai Zhang | 2021 | High Voltage2021，6，4： | 1 |
| 2 | Contrast-enhanced multidetector computed tomography features and histogram analysis can differentiate ameloblastomas from central giant cell granulomas显示文摘BACKGROUND No qualitative or quantitative analysis of contrast-enhanced computed tomography(CT)images has been reported for the differentiation between ameloblastomas and central giant cell granulomas(CGCGs).AIM To describe differentiating multidetector CT(MDCT)features in CGCGs and ameloblastomas and to compare differences in enhancement of these lesions qualitatively and using histogram analysis.METHODS MDCT of CGCGs and ameloblastomas was retrospectively reviewed to evaluate qualitative imaging descriptors.Histogram analysis was used to compare the extent of enhancement of the soft tissue.Fisher’s exact tests and Mann–Whitney U test were used for statistical analysis(P<0.05).RESULTS Twelve CGCGs and 33 ameloblastomas were reviewed.Ameloblastomas had a predilection for the posterior mandible with none of the CGCGs involving the angle.CGCGs were multilocular(58.3%),with a mixed lytic sclerotic appearance(75%).Soft tissue component was present in 91%of CGCGs,which showed hyperenhancement(compared to surrounding muscles)in 50%of cases,while the remaining showed isoenhancement.Matrix mineralization was present in 83.3%of cases.Ameloblastomas presented as a unilocular(66.7%),lytic(60.6%)masses with solid components present in 81.8%of cases.However,the solid component showed isoenhancement in 63%.No matrix mineralization was present in 69.7%of cases.Quantitatively,the enhancement of soft tissue in CGCG was significantly higher than in ameloblastoma on histogram analysis(P<0.05),with a minimum enhancement of>49.05 HU in the tumour providing 100%sensitivity and 85%specificity in identifying a CGCG.CONCLUSION A multilocular,lytic sclerotic lesion with significant hyperenhancement in soft tissue,which spares the angle of the mandible and has matrix mineralization,should indicate prospective diagnosis of CGCG. | Adarsh Ghosh Meyyappan Lakshmanan Smita Manchanda Ashu Seith Bhalla Prem Kumar Ongkila Bhutia Asit Ranjan Mridha | 2022 | World Journal of Radiology2022，14，9： | 0 |
| 3 | A review on insulation challenges towards electrification of aircraft显示文摘Compared to the traditional aircraft,electrification of power system in aircraft has potential to revolutionise the aviation industry.Typically,more-electric aircraft(MEA),even all-electric aircraft has been developed and delivered to decrease the greenhouse gas emission and increase the energy efficiency.The next generation of MEA will operate at high voltage to facilitate the transfer of significant levels of electrical power in an electrified aircraft.However,the higher voltage inevitably leads to an increased risk to the insulation of the electrical components and power system.This study aims to provide a critical overview of the insulation challenges from the perspective of electrified aircraft,typically MEA application.The development of MEA and the special working conditions are explained at the beginning.Then the insulation challenges of power modules,electric machines,aeronautical cables etc.are discussed in detail.Finally,the existing technical barriers and future prospects of insulation for electrified aircraft are summarised.It provides a reference for the future design and test in power system of next generation MEA and related electrified air transportations. | Jun Jiang Zhi Li Wenyuan Li Prem Ranjan Xingdong Wei Xu Zhang Chaohai Zhang | 2023 | High Voltage2023，8，2： | 0 |
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