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Influence of thermal ageing on high-field polarisation characteristics and conductivity behaviour of submarine polymeric cables insulation

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High Voltage 2023年第1期8卷 138-148页

作者： Xize Dai Jian Hao gian carlo montanari Zheng Jian Ruijin Liao Xinlong Zheng State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqingChina Department of Energy Aalborg UniversityAalborgDenmark Center for Advanced Power Systems Florida State UniversityTallahasseeFloridaUSA Shinan Power Supply Branch Company of State Grid Chongqing Electric Power Company NananChina Zhoushan Power Supply Branch Company of State Grid Zhejiang Electric Power Company ZhoushanChina

Diagnosing insulation intrinsic ageing is essential for preventing insulation failure of submarine cables,and in case of failure,helping in any decision about maintenance actions.In this study,a novel aged cable diagnosis approach based on high-voltage frequency domain spectroscopy(HV-FDS)with broader frequency width is proposed to analyse the high-field polarisation characteristics and conductivity behaviour of 500 kV submarine polymeric cables insulation,aiming to support the evaluation of overall insulation ageing.The measurement principle of HV-FDS and relaxation mechanism are stated,and then focus is on studying the extent of change of polarisation and conduction properties of submarine cables insulation as a function of ageing stress and time.Moreover,the high-field polarisation characteristics and conductivity behaviour are discussed in-depth based on the carrier transport and trap properties.Finally,the novel diagnostic indicator based on the high-field characteristics is extracted to quantify the thermal ageing state of submarine cables insulation.Results show that the high-field polarisation characteristics and conductivity behaviour seem to become sensitive diagnostic quantities if measured at reasonably high voltage,which are able to reveal mechanisms associated with thermo-oxidative ageing as that generated in the testing procedure considered in this paper.Sensitivity is considerably higher than that experienced in typical dielectric spectroscopy approaches.

关键词： behaviour insulation characteristics

Pulse width modulation voltage source deadtime effect on partial discharge and lifetime of inverter‐fed motor insulation

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High Voltage 2022年第6期7卷 1185-1193页

作者： Shakeel Akram Peng Wang Pengfei Meng gian carlo montanari Farhan Hameed Malik College of Electrical Engineering Sichuan UniversityChengduChina Center for Advanced Power Systems Florida State UniversityTallahasseeFloridaUSA Department of Electromechanical Engineering Abu Dhabi PolytechnicAbu DhabiUnited Arab Emirates

This paper analyses the impact of square wave pulse voltage deadtime on the partial discharge(PD)and the lifetime of turn-to-turn insulation.A bipolar repetitive pulse voltage with a deadtime of 0–10μs is produced using double half-bridge solid-state switches having push–pull technology controlled by a field-programmable gate array.The mechanism of the discharge process at rising and falling edges of the pulse voltage before and after deadtime is analysed in detail.The discharge amplitude and PD probability at the rising/falling edges of the voltage waveform increase as the deadtime increases from 0 to 10μs due to the remanent charges.The number of PD and their intensity is higher at the first rising/falling edges of pulse voltage as compared to the second rising/falling edges for all deadtimes 0–10μs.As the deadtime increases beyond 2μs,the number of PDs increases and concentrates at a specific phase angle of rising/falling edges.These localise discharges degrade the insulation material and reduce its lifetime.This study helps to identify the inverter-fed motor insulation faults due to deadtime.It can provide guidelines to motor insulation designers to determine the limit value of deadtime to compensate PD and ensure the safer operation of such motors.

关键词： dead insulation inverter

An innovative approach to partial discharge measurement and analysis in DC insulation systems during voltage transient and in steady state

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High Voltage 2021年第4期6卷 565-575页

作者： gian carlo montanari Riddhi Ghosh Center for Advanced Power Systems Florida State UniversityTallahasseeFloridaUSA

Measuring partial discharges in DC insulation systems is an issue due to the lack of a reference relating the voltage waveform to the physics of discharge phenomena.Also,DC is not always steady state,due to voltage and load transients that generate electric field profile variations inside an insulation system,which can affect partial discharge inception likelihood and characteristics.Partial discharge measurement technology must be able to separate discharge pulses from noise and identify the type of sources generating partial discharge,which is related to condition assessment and maintenance.Eventually,measurement and analysis should be automatic and unsupervised,in order to get rid,partially or totally,of expert support.This study addresses a new approach to partial discharge measurements in DC insulation systems,presenting algorithms for separation,recognition and identification,which are effective both in DC steady state and during voltage(and load)transients.These algorithms are automatic and do not require expert support.Various cases of algorithm application on test objects consisting of multilayer polymeric specimens with an internal cavity and defective cable models are presented and discussed.Their effectiveness is proved,at least at a laboratory level,with effective noise separation and identification of discharge typology.

关键词： insulation state separation

Discovery of an unknown conduction mechanism in insulating polymers

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High Voltage 2020年第4期5卷 403-408页

作者： gian carlo montanari Paolo Seri Leonard A.Dissado Center for Advanced Power Systems Florida State University2000 Levy AvenueFL 32310USA DEI University of BolognaViale del Risorgimento2–40136BolognaItaly Department of Engineering University of LeicesterUniversity RoadLeicesterLE17RHUK

Polymer dielectrics are widely used in electrical and electronic apparatus and devices because of their capability to insulate conductors,withstand high fields and suffer negligible conductive losses.Their near-to-zero conductivity has been explained in terms of long-accepted theories of electronic and ionic transport that lead to the accumulation of local net charge regions at high electric fields.Here the authors describe a previously unknown conduction mechanism consisting of small bipolar ultra-fast charge pulses crossing the polymer with the mobility,as large as,4 to 5 orders of magnitude greater than that of the previously known.The authors show that this motion is a consequence of molecular relaxation processes triggered by the electric field locally enhanced by the pulses themselves.Pulse accumulation at the electrodes increases interface field and thus contributes substantially towards premature failure in insulating dielectrics in DC fields.

关键词： conduction mechanism negligible

Ageing and reliability of electrical insulation: the risk of hybrid AC/DC grids

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High Voltage 2020年第5期5卷 620-627页

作者： gian carlo montanari Peter Morshuis Paolo Seri Riddhi Ghosh CAPS Florida State UniversityTallahasseeUSA School of Electrical Engineering Xi'an Jiaotong UniversityXi'anPeople's Republic of China University of Bologna BolognaItaly

With an impetuous growth of DC links and future grids that will be often hybrid,providing AC and DC supply to nearby or the same customer,an important element is often neglected,that is,electrical insulation.There are no doubts that overhead lines will step back compared to insulated cables,for known reasons of environmental impact,right of way and reliability,especially in an urban or harsh environment.On the other hand,while AC insulation systems have been investigated and used for decades,there is no analogue experience for DC polymeric insulation,nor for insulation systems subjected to power electronics supply.This study aims at enhancing the attention on this topic,focusing on insulation ageing mechanisms and models of relevance for hybrid AC/DC assets and grids.Ageing and life models for AC,DC and power electronics supply are discussed and compared to experimental data,focusing on partial discharge and space charge.It is shown how these two phenomena affect lifetime for different AC,DC and transient operating conditions.The main drivers for insulation design and material selection are discussed,showing that insulation reliability can be achieved only if operating stresses,ageing mechanisms and life models are known and accounted for properly by insulation designers.

关键词： insulation electrical properly

Testing cable system reliability after commissioning and during operation life:in medio stat virtus?

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High Voltage 2021年第1期6卷 34-41页

作者： gian carlo montanari Paolo Seri Riddhi Ghosh Stefano Franchi Bononi Marco Albertini Center for Advanced Power Systems Florida State University2000 Levy Avenue FLUSA DEI University of BolognaViale del RisorgimentoBolognaItaly Prysmian S.p.A. Via ChieseMilanItaly

Quality control,commissioning and diagnostic tests on insulation systems of electrical apparatus are necessary to reduce the failure risk under operation,eliminate infant mortality failures and reduce the impact of ageing on insulation system reliability.This study tries to establish a path which,based on the statistical-phenomenological modelling of the hazard rate,or bathtub curve,drives in the choice of test overvoltage and procedures.The choice of the test voltage and its waveform should be made carefully to improve reliability(reduce failure hazard)in any section of the bathtub curve.This may require,however,different choices depending on the section which corresponds to the planned test.For example,large overvoltages could be acceptable to remove the infant mortality to ensure the highest reliability of newly commissioned apparatus,but they can incept highly energetic,and,thus,fast degradation mechanisms on apparatus operating on the field for a period of time,that can worsen,rather than improving,the insulation system reliability.Resorting to partial discharge measurement during any overvoltage test seems to be the optimal solution to find the most appropriate overvoltage for any type of testing need,leveraging the Latin concept that‘in medio stat virtus’.

关键词： apparatus insulation operation

Nutrient restriction-activated Fra-2 promotes tumor progression via IGF1R in miR-15a downmodulated pancreatic ductal adenocarcinoma

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Signal Transduction and Targeted Therapy 2024年第3期9卷 1132-1146页

作者： gian Luca Rampioni Vinciguerra Marina Capece Luca Reggiani Bonetti Giovanni Nigita Federica Calore Sydney Rentsch Paolo Magistri Roberto Ballarin Fabrizio Di Benedetto Rosario Distefano Roberto Cirombella Andrea Vecchione Barbara Belletti Gustavo Baldassarre Francesca Lovat carlo M.Croce Department of Cancer Biology and Genetics and Comprehensive Cancer Center The Ohio State UniversityColumbus 43210 OHUSA Department of Clinical and Molecular Medicine Faculty of Medicine and PsychologySant’Andrea HospitalUniversity of Rome“Sapienza”Rome 00189Italy Department of Diagnostic Clinic and Public Health MedicineUniversity of Modena and Reggio EmiliaModena 41100Italy Hepato-pancreato-biliary Surgery and Liver Transplantation Unit University of Modena and Reggio EmiliaModena 41100Italy Division of Molecular Oncology Centro di Riferimento Oncologico di Aviano(CRO)Istituto di Ricovero e Cura a Carattere Scientifico(IRCCS)National Cancer InstituteAviano 33081Italy

Pancreatic ductal adenocarcinoma(PDAC)is a lethal disease,characterized by an intense desmoplastic reaction that compresses blood vessels and limits nutrient supplies.PDAC aggressiveness largely relies on its extraordinary capability to thrive and progress in a challenging tumor microenvironment.Dysregulation of the onco-suppressor miR-15a has been extensively documented in PDAC.Here,we identified the transcription factor Fos-related antigen-2(Fra-2)as a miR-15a target mediating the adaptive mechanism of PDAC to nutrient deprivation.We report that the IGF1 signaling pathway was enhanced in nutrient deprived PDAC cells and that Fra-2 and IGF1R were significantly overexpressed in miR-15a downmodulated PDAC patients.Mechanistically,we discovered that miR-15a repressed IGF1R expression via Fra-2 targeting.In miR-15a-low context,IGF1R hyperactivated mTOR,modulated the autophagic flux and sustained PDAC growth in nutrient deprivation.In a genetic mouse model,Mir15aKO PDAC showed Fra-2 and Igf1r upregulation and mTOR activation in response to diet restriction.Consistently,nutrient restriction improved the efficacy of IGF1R inhibition in a Fra-2 dependent manner.Overall,our results point to a crucial role of Fra-2 in the cellular stress response due to nutrient restriction typical of pancreatic cancer and support IGF1R as a promising and vulnerable target in miR-15a downmodulated PDAC.

关键词： IGF1R Fra miR

Minimally invasive surgical therapies(MISTs)for lower urinary tract symptoms(LUTS):promise or panacea?

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Asian Journal of Andrology 2024年第2期26卷 135-143页

作者： gian Maria Busetto Andrea Checchia Marco Recchia Edoardo Tocci Ugo G Falagario Gennaro Annunziata Pasquale Annese Nicola d'Altilia Vito Mancini Matteo Ferro Felice Crocetto Octavian Sabin Tataru Luca Di gianfrancesco Angelo Porreca Francesco Del Giudice Ettore De Berardinis carlo Bettocchi Luigi Cormio Giuseppe Carrieri University of Foggia Foggia 71122Italy Department of Urology and Renal Transplantation Policlinico of FoggiaFoggia 71122Italy Urology Unit "G.Tatarlla"HospitalCerignola 71042Italy Urology Unit European Institute of Oncology(IE0)IRCcSMilan 20141Italy University of Naples Federico Il Naples 80126Italy G.E.Palade University of Medicine PharmacyScienceand Technology of Targu MuresTargu Mures 540142Romania Department of Oncological Urology Veneto Institute of Oncology(IOv)IRccSPadua 35128Italy Department of Maternal-Infant and Urological Sciences Sapienza Rome UniversityRoma 00161Italy Urology Unit "L.Bonomo"HospitalAndria 76123Italy

The increasing importance of treatment of lower urinary tract symptoms(LUTS),while avoiding side effects and maintaining sexual function,has allowed for the development of minimally invasive surgical therapies(MiSTs).Recently,the European Association of Urology guidelines reported a paradigm shift from the management of benign prostatic hyperplasia(BPH)to the management of nonneurogenic male LUTS.The aim of the present review was to evaluate the efficacy and safety of the most commonly used MisTs:ablative techniques such as aquablation,prostatic artery embolization,water vapor energy,and transperineal prostate laser ablation,and nonablative techniques such as prostatic urethral lift and temporarily implanted nitinol device(iTIND).MiSTs are becoming a new promise,even if clinical trials with longer follow-up are still lacking.Most of them are still under investigation and,to date,only a few options have been given as a recommendation for use.They cannot be considered as standard of care and are not suitable for all patients.Advantages and disadvantages should be underlined,without forgetting our objective:treatment of LUTS and re-treatment avoidance.

关键词： aquablation iTIND prostatic artery embolization prostatic urethral lift transperineal prostate laser ablation water vapor energy

Antioxidant treatment foroligoasthenoteratozoospermia and varicocele:aDBPC trial to evaluate the impact of age and bodymass index

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Asian Journal of Andrology 2024年第3期26卷 239-244页

作者： gian Maria Busetto Bernarde F Rodrigues Ashraf Virmani Andrea Checchia Antonella Ninivaggi Anna Ricapito Giovanni Barbieri Piero Fischetti Ugo G Falagario Pasquale Annese Nicola d’Altilia Vito Mancini Matteo Ferro Felice Crocetto Angelo Porreca carlo Bettocchi Luigi Cormio Ashok Agarwal Giuseppe Carrieri University of Foggia Foggia 71122Italy Department of Urology and Renal Transplantation Policlinico of FoggiaFoggia 71122Italy Department of Urology HumanReproduction SectionFederal University of Sao PauloSao Paulo 05403-000Brazil Alfasigma Healthscience Utrecht 3528 BGThe Netherlands Urology Unit “G.Tatarella”HospitalCerignola 71042Italy Urology Unit European Institute of Oncology(IEO)IRCCSMilan 20142Italy University of Naples Federico II Naples80126Italy Department of Oncological Urology Veneto Institute of Oncology(IOV)IRCCSPadua 35039Italy Urology Unit “L.Bonomo”HospitalAndria 70031Italy Global Andrology Forum Moreland HillsOH 44022USA

Oxidative stress is one of the main mechanisms responsible for male infertility.Various conditions such as varicocele,obesity,advanced age,and lifestyle can lead to an increase in reactive oxygen species,causing an oxidative imbalance in the reproductiveenvironment.Spermatozoa are sensitive to reactive oxygen species and require energy to carry out their main function of fertilizingthe egg.Excessive reactive oxygen species can affect sperm metabolism,leading to immobility,impaired acrosome reaction,and celldeath,thereby impairing reproductive success.This double-blind randomized study evaluated the effect of supplementation withL-carnitine,acetyl-L-carnitine,vitamins,and other nutrients on semen quality in 104 infertile patients with or without varicocele,while also investigating the impact of factors such as obesity and advanced age on treatment.Sperm concentration significantlyincreased in the supplemented group compared to the placebo group(P=0.0186).Total sperm count also significantly increasedin the supplemented group(P=0.0117),as did sperm motility(P=0.0120).The treatment had a positive effect on patients upto 35 years of age in terms of sperm concentration(P=0.0352),while a body mass index(BMI)above 25 kg m−2 had a negativeeffect on sperm concentration(P=0.0110).Results were not showing a net benefit in stratifying patients in accordance withtheir BMI since sperm quality increase was not affected by this parameter.In conclusion,antioxidant supplementation may bebeneficial for infertile patients and has a more positive effect on younger patients with a normal weight.

关键词： aging antioxidants body mass index oligoasthenoteratozoospermia varicocele