On the basis of the structural and electronic properties of 14 different cyclic nitramine molecules, two types of formulas are employed to predict their electric spark sensitivity. One contains the minimum Mulliken ch...On the basis of the structural and electronic properties of 14 different cyclic nitramine molecules, two types of formulas are employed to predict their electric spark sensitivity. One contains the minimum Mulliken charges of nitro group, the ratio of hydrogen to oxygen, and the ratio of carbon to oxygen; the other contains the lowest unoccupied molecular orbital energy, the ratio of hydrogen to oxygen, and the ratio of carbon to oxygen. Using these two types of formulas, we calculate the electric spark sensitivity of these 14 cyclic nitramine molecules, and compare them with the experimental data and previous theoretical values. And our investigations show that the former type of formula is better than the latter on predicting the electric spark sensitivity for cyclic nitramine molecules.展开更多
An ESZ KTTV instrument of a new,relatively simple construction has been applied to determination of electric spark sensitivity of 29 polynitro arenes,expressed as spark energy,EES,required for 50-percent initiation pr...An ESZ KTTV instrument of a new,relatively simple construction has been applied to determination of electric spark sensitivity of 29 polynitro arenes,expressed as spark energy,EES,required for 50-percent initiation probability.The thermal stability thresholds,Tmax,were calculated from the published Arrhenius parameters of monomolecular thermal decomposition of the studied compounds,predominantly obtained under the conditions of the Russian manometric method.An approximate relationship has been found between the ln EES values and threshold Tmax values.In the sense of this relationship,the compounds studied fall into several sub-groups.The reason of the said diversification lies in the decomposition reaction rate at the temperature of onset of their thermal decomposition.It has been found that in each sub-group increasing thermal stability of polynitro arenes is accompanied by increasing electric spark sensitivity of these substances.This fact must be taken into account if we deal with the problem of electric spark energy transfer into the reaction centre of the molecule.展开更多
Distribution systems operators are often confronted with declined power quality, which can cause substantial economical losses. The problem analyzed in paper concerns thyristor controlled direct current motor used for...Distribution systems operators are often confronted with declined power quality, which can cause substantial economical losses. The problem analyzed in paper concerns thyristor controlled direct current motor used for ski-lift in ski resort as a source of disturbances with negative impact on sensitive electric equipment, which is then unable to operate correctly. To solve mentioned problems, series of measurements of voltage quality parameters were carried out according to the respective valid standards. Crucial power quality parameters necessary for parallel power active filter design were then analyzed. Power active filter compensates power factor and filters characteristic current harmonics. After power active filter was put into operation, power quality problems were eliminated. Payback period is estimated up to four years.展开更多
Requirements of the Internet of things for the network includes the ability to monitor the equipment and devices.Nowadays,the reliability of a power electronics converter has raised concerns of both academia and indus...Requirements of the Internet of things for the network includes the ability to monitor the equipment and devices.Nowadays,the reliability of a power electronics converter has raised concerns of both academia and industry.In particular,power semiconductor devices are continuously exposed to excessive stress while being designed with high power handling capability and are considered as the most fragile component in power converters suffering from a high failure rate.Aiming to find an effective monitoring method which is also helpful for the Internet of Things and improve the reliability of a three-level neutral-point-clamped power inverter,an in-situ health monitoring method is proposed by harnessing the inverter operational characteristics and degradation sensitive electrical parameters to address the IGBT wire bonding faults.The zero voltage state provides an inherent redundant feature that allows for a power switch to be diagnosed during its normal operation in a neutralpoint-clamped power inverter.The proposed prognostic approach obtains both the wire bonding failure features and junction temperature from the terminals of an IGBT module,which is regarded as non-invasive on-line health monitoring.The system performance can be affected by the designated testing point and testing window,which is discussed and experimentally validated.The proposed technique allows unhealthy wire bonding in IGBT modules online monitoring during the operational period of the inverter.And the proposed in-situ health monitoring of IGBT modules can be used for the industrial Internet of things.展开更多
Pb0：97La0：02（Zr0：75Sn0：25x Ti x/O3（x D0.10, 0.105, 0.11）（PLZST） antiferroelectric ceramics with highly preferred-（110） orientation were successfully fabricated via the conventional solid-state reaction meth...Pb0：97La0：02（Zr0：75Sn0：25x Ti x/O3（x D0.10, 0.105, 0.11）（PLZST） antiferroelectric ceramics with highly preferred-（110） orientation were successfully fabricated via the conventional solid-state reaction method.The antiferroelectric nature of PLZST ceramics induced by electric field was demonstrated by the dielectric constant-temperature（D-T） and the polarization-electric field（P-E） measurement. Typical phase transition from ferroelectric（FE） to antiferroelectric（AFE）, and then to paraelectric（PE） is obtained. The results indicate that the phase transition behavior is suppressed with increasing of x, and T c is remarkably shifted to higher temperature of168 ℃, 170 ℃ and 174 ℃, respectively. Besides, high phase transition current（110 6A, 810 7A and 610 7A, respectively） is obtained with temperature induced. Consequently, the excellent electric properties and the restraint between temperature and electric field would provide basis on the application of PLZST antiferroelectric ceramics in microelectronic integrated systems and sophisticated weapons systems.展开更多
基金the National Natural Science Foundation of China (Nos. 11176020 and 10976019)
文摘On the basis of the structural and electronic properties of 14 different cyclic nitramine molecules, two types of formulas are employed to predict their electric spark sensitivity. One contains the minimum Mulliken charges of nitro group, the ratio of hydrogen to oxygen, and the ratio of carbon to oxygen; the other contains the lowest unoccupied molecular orbital energy, the ratio of hydrogen to oxygen, and the ratio of carbon to oxygen. Using these two types of formulas, we calculate the electric spark sensitivity of these 14 cyclic nitramine molecules, and compare them with the experimental data and previous theoretical values. And our investigations show that the former type of formula is better than the latter on predicting the electric spark sensitivity for cyclic nitramine molecules.
基金The research was carried out under the auspices of the Ministry of Education,Youth & Sports of the Czech Republic as a part of its research project No.MSM0021627501
文摘An ESZ KTTV instrument of a new,relatively simple construction has been applied to determination of electric spark sensitivity of 29 polynitro arenes,expressed as spark energy,EES,required for 50-percent initiation probability.The thermal stability thresholds,Tmax,were calculated from the published Arrhenius parameters of monomolecular thermal decomposition of the studied compounds,predominantly obtained under the conditions of the Russian manometric method.An approximate relationship has been found between the ln EES values and threshold Tmax values.In the sense of this relationship,the compounds studied fall into several sub-groups.The reason of the said diversification lies in the decomposition reaction rate at the temperature of onset of their thermal decomposition.It has been found that in each sub-group increasing thermal stability of polynitro arenes is accompanied by increasing electric spark sensitivity of these substances.This fact must be taken into account if we deal with the problem of electric spark energy transfer into the reaction centre of the molecule.
文摘Distribution systems operators are often confronted with declined power quality, which can cause substantial economical losses. The problem analyzed in paper concerns thyristor controlled direct current motor used for ski-lift in ski resort as a source of disturbances with negative impact on sensitive electric equipment, which is then unable to operate correctly. To solve mentioned problems, series of measurements of voltage quality parameters were carried out according to the respective valid standards. Crucial power quality parameters necessary for parallel power active filter design were then analyzed. Power active filter compensates power factor and filters characteristic current harmonics. After power active filter was put into operation, power quality problems were eliminated. Payback period is estimated up to four years.
基金This work was supported by National Natural Science Foundation of China(U1834204).
文摘Requirements of the Internet of things for the network includes the ability to monitor the equipment and devices.Nowadays,the reliability of a power electronics converter has raised concerns of both academia and industry.In particular,power semiconductor devices are continuously exposed to excessive stress while being designed with high power handling capability and are considered as the most fragile component in power converters suffering from a high failure rate.Aiming to find an effective monitoring method which is also helpful for the Internet of Things and improve the reliability of a three-level neutral-point-clamped power inverter,an in-situ health monitoring method is proposed by harnessing the inverter operational characteristics and degradation sensitive electrical parameters to address the IGBT wire bonding faults.The zero voltage state provides an inherent redundant feature that allows for a power switch to be diagnosed during its normal operation in a neutralpoint-clamped power inverter.The proposed prognostic approach obtains both the wire bonding failure features and junction temperature from the terminals of an IGBT module,which is regarded as non-invasive on-line health monitoring.The system performance can be affected by the designated testing point and testing window,which is discussed and experimentally validated.The proposed technique allows unhealthy wire bonding in IGBT modules online monitoring during the operational period of the inverter.And the proposed in-situ health monitoring of IGBT modules can be used for the industrial Internet of things.
基金Project supported by the National Natural Science Foundation of China(No.51175483)the National Science Fund for Distinguished Young Scholars(No.51225504)+1 种基金the Programf or New Century Excellent Talents in University(No.[2012]80)the Functional Materials Research Laboratory,Tongji University,China
文摘Pb0：97La0：02（Zr0：75Sn0：25x Ti x/O3（x D0.10, 0.105, 0.11）（PLZST） antiferroelectric ceramics with highly preferred-（110） orientation were successfully fabricated via the conventional solid-state reaction method.The antiferroelectric nature of PLZST ceramics induced by electric field was demonstrated by the dielectric constant-temperature（D-T） and the polarization-electric field（P-E） measurement. Typical phase transition from ferroelectric（FE） to antiferroelectric（AFE）, and then to paraelectric（PE） is obtained. The results indicate that the phase transition behavior is suppressed with increasing of x, and T c is remarkably shifted to higher temperature of168 ℃, 170 ℃ and 174 ℃, respectively. Besides, high phase transition current（110 6A, 810 7A and 610 7A, respectively） is obtained with temperature induced. Consequently, the excellent electric properties and the restraint between temperature and electric field would provide basis on the application of PLZST antiferroelectric ceramics in microelectronic integrated systems and sophisticated weapons systems.
