To study the influence of silicon(Si)on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20),NC/CL-20 composite explosives and Si/NC/CL-20 composite explosives were prepared by the electrostatic spraying ...To study the influence of silicon(Si)on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20),NC/CL-20 composite explosives and Si/NC/CL-20 composite explosives were prepared by the electrostatic spraying method.The morphology,structure and thermal decomposition properties of the samples were analyzed using scanning electron microscopy(SEM),X-ray energy spectroscopy(EDS),infrared spectroscopy(FT-IR),and simultaneous thermal analyzer(TG-DSC).Additionally,the combustion process of the samples was tested using a high-speed camera.The results show that the addition of nano-Si contributes to the formation of composite explosives with regular morphology and smaller particle size.The Si/NC/CL-20 composite explosive has better and more uniform sphericity,with an average particle size of 73.4 nm,compared to the NC/CL-20 composite explosive.The Si/NC/CL-20 composite explosive which produced by the electrostatic spraying method,achieves physically uniform distribution of the components including NC,CL-20,Si.The addition of Si promotes the thermal decomposition of CL-20.In comparison to the NC/CL-20 composite explosive,the activation energy of the Si/NC/CL-20 composite explosive decreases by 16.78 kJ/mol,and the self-accelerated decomposition temperature and the critical temperature of thermal explosion decreases by 3.12 K and 2.61 K,respectively.Furthermore,Si/NC/CL-20 composite explosive has shorter ignition delay time and faster combustion rate compared to the NC/CL-20 composite explosive,which shows that Si can improve the combustion performance of CL-20.展开更多
To investigate the process optimizationof Cu-en/AP composite microspheres preparation via electrostatic spraying,and to reveal the effects of droplet properties and flow rate variations on the experimental results dur...To investigate the process optimizationof Cu-en/AP composite microspheres preparation via electrostatic spraying,and to reveal the effects of droplet properties and flow rate variations on the experimental results during the electrostatic spraying process,the prepared process parameters of Cu-en/AP composite microspheres by electrostatic spray method under the orthogonal experimental design simulated by ANSYS(Fluent).The influence of flow rate,solvent ratio,and solid mass on the experimental results is examined using a controlled variable method.The results indicate that under the conditions of a flow rate of 2.67×10^(-3)kg/s an acetone-to-deionized water ratio of 1.5∶1.0,and a solid mass of 200 mg,the theoretical particle size of the composite microspheres can reach e nanoscale.Droplet trajectories in the electric field remain stable without significant deviation.The simulation results show that particle diameter decreases with increasing flow rate,with the trend leveling off around a flow rate of 1×10^(-3)kg/s.As the solvent ratio increases(with higher acetone content),particle diameter initially decreases,reaching a minimum around a ratio of 1.5∶1.0 before gradually increasing.Increasing the solid mass also reduces the particle diameter,with a linear increase in diameter observed at around 220 mg.Cu-en/AP composite microspheres with nanoscale dimensions were confirmed under these conditions by the final SEM images.展开更多
The electrostatic discharge(ESD)protection circuit widely exists in the input and output ports of CMOS digital circuits,and fast rising time electromagnetic pulse(FREMP)coupled into the device not only interacts with ...The electrostatic discharge(ESD)protection circuit widely exists in the input and output ports of CMOS digital circuits,and fast rising time electromagnetic pulse(FREMP)coupled into the device not only interacts with the CMOS circuit,but also acts on the protection circuit.This paper establishes a model of on-chip CMOS electrostatic discharge protection circuit and selects square pulse as the FREMP signals.Based on multiple physical parameter models,it depicts the distribution of the lattice temperature,current density,and electric field intensity inside the device.At the same time,this paper explores the changes of the internal devices in the circuit under the injection of fast rising time electromagnetic pulse and describes the relationship between the damage amplitude threshold and the pulse width.The results show that the ESD protection circuit has potential damage risk,and the injection of FREMP leads to irreversible heat loss inside the circuit.In addition,pulse signals with different attributes will change the damage threshold of the circuit.These results provide an important reference for further evaluation of the influence of electromagnetic environment on the chip,which is helpful to carry out the reliability enhancement research of ESD protection circuit.展开更多
Nitrogen-rich heterocyclic energetic compounds(NRHECs)and their salts have witnessed widespread synthesis in recent years.The substantial energy-density content within these compounds can lead to potentially dangerous...Nitrogen-rich heterocyclic energetic compounds(NRHECs)and their salts have witnessed widespread synthesis in recent years.The substantial energy-density content within these compounds can lead to potentially dangerous explosive reactions when subjected to external stimuli such as electrical discharge.Therefore,developing a reliable model for predicting their electrostatic discharge sensitivity(ESD)becomes imperative.This study proposes a novel and straightforward model based on the presence of specific groups(-NH_(2) or-NH-,-N=N^(+)-O^(-)and-NNO_(2),-ONO_(2) or-NO_(2))under certain conditions to assess the ESD of NRHECs and their salts,employing interpretable structural parameters.Utilizing a comprehensive dataset comprising 54 ESD measurements of NRHECs and their salts,divided into 49/5 training/test sets,the model achieves promising results.The Root Mean Square Error(RMSE),Mean Absolute Error(MAE),and Maximum Error for the training set are reported as 0.16 J,0.12 J,and 0.5 J,respectively.Notably,the ratios RMSE(training)/RMSE(test),MAE(training)/MAE(test),and Max Error(training)/Max Error(test)are all greater than 1.0,indicating the robust predictive capabilities of the model.The presented model demonstrates its efficacy in providing a reliable assessment of ESD for the targeted NRHECs and their salts,without the need for intricate computer codes or expert involvement.展开更多
The friction sensitivity(FS) of five aliphatic linear and eight cyclic nitramines has been determined and correlated with DFT B3LYP/6-31-G(d,p) // 6-311+G(d,p) positive(VS,max) and negative(VS,min) extremes of molecul...The friction sensitivity(FS) of five aliphatic linear and eight cyclic nitramines has been determined and correlated with DFT B3LYP/6-31-G(d,p) // 6-311+G(d,p) positive(VS,max) and negative(VS,min) extremes of molecular surface electrostatic potentials VS(r).While there is an ambiguous relationship between the VS,max values and FS values,the decrease of FS is connected(more or less) with increase in VS,min values.展开更多
To improve the dust removal performance of the wet electrostatic precipitator(WESP), a flow field optimization scheme was proposed via CFD simulation in different scales. The simplified models of perforated and collec...To improve the dust removal performance of the wet electrostatic precipitator(WESP), a flow field optimization scheme was proposed via CFD simulation in different scales. The simplified models of perforated and collection plates were determined firstly. Then the model parameters for the resistance of perforated and collection plates, obtained by small-scale flow simulation, were validated by medium-scale experiments. Through the comparison of the resistance and velocity distribution between simulation results and experimental data, the simplified model is proved to present the resistance characteristics of perforated and collection plates accurately. Numerical results show that after optimization, both the flow rate and the pressure drop in the upper room of electric field regions are basically equivalent to those of the lower room, and the velocity distribution in flue inlet of WESP becomes more uniform. Through the application in practice, the effectiveness and reliability of the optimization scheme are proved, which can provide valuable reference for further optimization of WESP.展开更多
In the present study,electrostatic atomization(EA)behavior of several test liquids having much higher viscosities(1 400 mPa·s)than have previously been studied was investigated by spraying at a series of applied ...In the present study,electrostatic atomization(EA)behavior of several test liquids having much higher viscosities(1 400 mPa·s)than have previously been studied was investigated by spraying at a series of applied voltages and flow rates.The results showed that to obtain stable cone-jet mode spraying and hence gain better monodispersity of droplets,electrical conductivity,viscosity and surface tension of the liquid are important controlling factors.The stable cone-jet mode could be easily established for liquids having shear viscosities in the range from 80 to 1 400 mPa·s and surface tensions below 65 mN·m-1.In contrast,methylcellulose aqueous solutions with shear viscosities ranging from 10 to 540 mPa·s and moderate surface tensions(50~56 mN·m-1)generated more complicated spraying modes.However,fine TiO2 powder(a few micrometers in size)could be prepared using the EA method from its precursor solutions.展开更多
Molecular surface electrostatic potentials V_S(r) ( ESP) of seventeen nitramines have been calculated. As a criterion of the imbalance between the maximum positive,V_(S,max) and minimum negative,V_(S,min),values of mo...Molecular surface electrostatic potentials V_S(r) ( ESP) of seventeen nitramines have been calculated. As a criterion of the imbalance between the maximum positive,V_(S,max) and minimum negative,V_(S,min),values of molecular surface electrostatic potentials their sum was derived and used as a new simple characteristic for ESPs-V_(S,Σ). These V_(S,Σ) values have close relationships with the Arrhenius parameters,activation energy E_a and preexponent log A,of thermal decomposition of the nitramines studied. The correlation between the V_(S,Σ) values and heats of fusion of the nitramines studied is described. These findings suggested analyzing the physico-chemical behavior of the nitramine crystals during this decomposition; in this connection an investigation was carried out using isothermal thermogravimetry and scanning electron microscopy of thermally exposed crystals of cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5-d]imidazole( sintering of its crystal surfaces),of β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane( cracking of its crystals during β !δ transition) and of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane. The results suggest a need to study the pre-decomposition states on thermal decomposition of the nitramines' molecule's crystals.展开更多
This paper presents recent progress on the velocity measurement of pulverised coal in pneumatic pipelines using electrostatic sensors in combination with correlation signal processing techniques.A comparative study of...This paper presents recent progress on the velocity measurement of pulverised coal in pneumatic pipelines using electrostatic sensors in combination with correlation signal processing techniques.A comparative study of electrostatic sensors with circular and probe electrodes was conducted on a 94 mm bore horizontal pipeline in a 4 MW furnace.The advantages and limitations of both sensors are discussed.Experimental results demonstrate that both sensors are capable of providing pulverised coal velocity measurement with excellent repeatability and dynamic response.展开更多
In order to clear the activated area in electrostatic accelerator facilities,four accelerator facilities were selected and typical neutron emission experiments were performed.Neutron flux during operation and induced ...In order to clear the activated area in electrostatic accelerator facilities,four accelerator facilities were selected and typical neutron emission experiments were performed.Neutron flux during operation and induced activity caused by charged particles on the accelerator and its surrounding area after irradiation were measured.Also the monitored neutron flux and calculated value by Monte Carlo calculation using PHITS code were compared.It was confirmed that the results between calculated data and measured data showed the good agreement with each other.Finally,it was concluded that we have to take care the activation of beam line and target.But,it is not necessary to treat accelerator tank,surrounding materials,and building concrete as radioactive materials in case of decommissioning.展开更多
Due to its extremely low electrostatic sensitivity,copper azide primary explosive is greatly limited in practical applications.In this study,a composite film with Cu-MOF in-situ growth on carbon nanofilm was prepared ...Due to its extremely low electrostatic sensitivity,copper azide primary explosive is greatly limited in practical applications.In this study,a composite film with Cu-MOF in-situ growth on carbon nanofilm was prepared by electrospinning and solvothermal methods,and CNF@Cu-N3film with electrostatic safety was obtained by carbonization and azide later.Its electrostatic sensitivity(E50)was greatly increased from 0.05 mJ of raw materials to 4.06 mJ,and still maintained a good detonation performance which could successfully detonate the CL-20 secondary explosive.This is mainly due to the synergistic effect of the carbon film and the MOF structure,which greatly improves the conductivity of the entire system and the uniform distribution of copper particles,providing a new preparation strategy for metal azide film that is suitable for the micro-initiator device.展开更多
A certain number of charges are deposited on the surface of high-voltage solar array because of effects of space plasma,high-energy charged particles,and solar illumination,hence the surface is charged.Phenomena of el...A certain number of charges are deposited on the surface of high-voltage solar array because of effects of space plasma,high-energy charged particles,and solar illumination,hence the surface is charged.Phenomena of electrostatic discharge(ESD) occur on the surface when the deposited charges exceed a threshold amount.In this paper,the mechanism of this ESD is discussed.The ground simulation experiment of the ESD using spacecraft material under surface charging is described,and a novel ESD protecting method for high-voltage solar array,i.e.an active protecting method based on the local strong electric field array is proposed.The results show that the reversal potential gradient field between the cover surface and the substrate materials of high-voltage solar array is a triggering factor for the ESD on the array.The threshold voltage for the ESD occurring on the surface is about 500 V.The charged particles could be deflected using the electric field active protecting method,and hence the ESD on the surface is avoided even when the voltage on the conductor array increases to a certain value.These results pave the way for further developing the protecting measures for high-voltage solar arrays.展开更多
基金National Natural Science Foundation of China(No.22275150)。
文摘To study the influence of silicon(Si)on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20),NC/CL-20 composite explosives and Si/NC/CL-20 composite explosives were prepared by the electrostatic spraying method.The morphology,structure and thermal decomposition properties of the samples were analyzed using scanning electron microscopy(SEM),X-ray energy spectroscopy(EDS),infrared spectroscopy(FT-IR),and simultaneous thermal analyzer(TG-DSC).Additionally,the combustion process of the samples was tested using a high-speed camera.The results show that the addition of nano-Si contributes to the formation of composite explosives with regular morphology and smaller particle size.The Si/NC/CL-20 composite explosive has better and more uniform sphericity,with an average particle size of 73.4 nm,compared to the NC/CL-20 composite explosive.The Si/NC/CL-20 composite explosive which produced by the electrostatic spraying method,achieves physically uniform distribution of the components including NC,CL-20,Si.The addition of Si promotes the thermal decomposition of CL-20.In comparison to the NC/CL-20 composite explosive,the activation energy of the Si/NC/CL-20 composite explosive decreases by 16.78 kJ/mol,and the self-accelerated decomposition temperature and the critical temperature of thermal explosion decreases by 3.12 K and 2.61 K,respectively.Furthermore,Si/NC/CL-20 composite explosive has shorter ignition delay time and faster combustion rate compared to the NC/CL-20 composite explosive,which shows that Si can improve the combustion performance of CL-20.
基金National Natural Science Foundation of China(No.2275150)。
文摘To investigate the process optimizationof Cu-en/AP composite microspheres preparation via electrostatic spraying,and to reveal the effects of droplet properties and flow rate variations on the experimental results during the electrostatic spraying process,the prepared process parameters of Cu-en/AP composite microspheres by electrostatic spray method under the orthogonal experimental design simulated by ANSYS(Fluent).The influence of flow rate,solvent ratio,and solid mass on the experimental results is examined using a controlled variable method.The results indicate that under the conditions of a flow rate of 2.67×10^(-3)kg/s an acetone-to-deionized water ratio of 1.5∶1.0,and a solid mass of 200 mg,the theoretical particle size of the composite microspheres can reach e nanoscale.Droplet trajectories in the electric field remain stable without significant deviation.The simulation results show that particle diameter decreases with increasing flow rate,with the trend leveling off around a flow rate of 1×10^(-3)kg/s.As the solvent ratio increases(with higher acetone content),particle diameter initially decreases,reaching a minimum around a ratio of 1.5∶1.0 before gradually increasing.Increasing the solid mass also reduces the particle diameter,with a linear increase in diameter observed at around 220 mg.Cu-en/AP composite microspheres with nanoscale dimensions were confirmed under these conditions by the final SEM images.
基金National Natural Science Foundation of China(61974116)。
文摘The electrostatic discharge(ESD)protection circuit widely exists in the input and output ports of CMOS digital circuits,and fast rising time electromagnetic pulse(FREMP)coupled into the device not only interacts with the CMOS circuit,but also acts on the protection circuit.This paper establishes a model of on-chip CMOS electrostatic discharge protection circuit and selects square pulse as the FREMP signals.Based on multiple physical parameter models,it depicts the distribution of the lattice temperature,current density,and electric field intensity inside the device.At the same time,this paper explores the changes of the internal devices in the circuit under the injection of fast rising time electromagnetic pulse and describes the relationship between the damage amplitude threshold and the pulse width.The results show that the ESD protection circuit has potential damage risk,and the injection of FREMP leads to irreversible heat loss inside the circuit.In addition,pulse signals with different attributes will change the damage threshold of the circuit.These results provide an important reference for further evaluation of the influence of electromagnetic environment on the chip,which is helpful to carry out the reliability enhancement research of ESD protection circuit.
文摘Nitrogen-rich heterocyclic energetic compounds(NRHECs)and their salts have witnessed widespread synthesis in recent years.The substantial energy-density content within these compounds can lead to potentially dangerous explosive reactions when subjected to external stimuli such as electrical discharge.Therefore,developing a reliable model for predicting their electrostatic discharge sensitivity(ESD)becomes imperative.This study proposes a novel and straightforward model based on the presence of specific groups(-NH_(2) or-NH-,-N=N^(+)-O^(-)and-NNO_(2),-ONO_(2) or-NO_(2))under certain conditions to assess the ESD of NRHECs and their salts,employing interpretable structural parameters.Utilizing a comprehensive dataset comprising 54 ESD measurements of NRHECs and their salts,divided into 49/5 training/test sets,the model achieves promising results.The Root Mean Square Error(RMSE),Mean Absolute Error(MAE),and Maximum Error for the training set are reported as 0.16 J,0.12 J,and 0.5 J,respectively.Notably,the ratios RMSE(training)/RMSE(test),MAE(training)/MAE(test),and Max Error(training)/Max Error(test)are all greater than 1.0,indicating the robust predictive capabilities of the model.The presented model demonstrates its efficacy in providing a reliable assessment of ESD for the targeted NRHECs and their salts,without the need for intricate computer codes or expert involvement.
基金the project of the Ministry of Education,Youth and Sports of the Czech Republic No.MSM 0021627501
文摘The friction sensitivity(FS) of five aliphatic linear and eight cyclic nitramines has been determined and correlated with DFT B3LYP/6-31-G(d,p) // 6-311+G(d,p) positive(VS,max) and negative(VS,min) extremes of molecular surface electrostatic potentials VS(r).While there is an ambiguous relationship between the VS,max values and FS values,the decrease of FS is connected(more or less) with increase in VS,min values.
文摘To improve the dust removal performance of the wet electrostatic precipitator(WESP), a flow field optimization scheme was proposed via CFD simulation in different scales. The simplified models of perforated and collection plates were determined firstly. Then the model parameters for the resistance of perforated and collection plates, obtained by small-scale flow simulation, were validated by medium-scale experiments. Through the comparison of the resistance and velocity distribution between simulation results and experimental data, the simplified model is proved to present the resistance characteristics of perforated and collection plates accurately. Numerical results show that after optimization, both the flow rate and the pressure drop in the upper room of electric field regions are basically equivalent to those of the lower room, and the velocity distribution in flue inlet of WESP becomes more uniform. Through the application in practice, the effectiveness and reliability of the optimization scheme are proved, which can provide valuable reference for further optimization of WESP.
文摘In the present study,electrostatic atomization(EA)behavior of several test liquids having much higher viscosities(1 400 mPa·s)than have previously been studied was investigated by spraying at a series of applied voltages and flow rates.The results showed that to obtain stable cone-jet mode spraying and hence gain better monodispersity of droplets,electrical conductivity,viscosity and surface tension of the liquid are important controlling factors.The stable cone-jet mode could be easily established for liquids having shear viscosities in the range from 80 to 1 400 mPa·s and surface tensions below 65 mN·m-1.In contrast,methylcellulose aqueous solutions with shear viscosities ranging from 10 to 540 mPa·s and moderate surface tensions(50~56 mN·m-1)generated more complicated spraying modes.However,fine TiO2 powder(a few micrometers in size)could be prepared using the EA method from its precursor solutions.
文摘Molecular surface electrostatic potentials V_S(r) ( ESP) of seventeen nitramines have been calculated. As a criterion of the imbalance between the maximum positive,V_(S,max) and minimum negative,V_(S,min),values of molecular surface electrostatic potentials their sum was derived and used as a new simple characteristic for ESPs-V_(S,Σ). These V_(S,Σ) values have close relationships with the Arrhenius parameters,activation energy E_a and preexponent log A,of thermal decomposition of the nitramines studied. The correlation between the V_(S,Σ) values and heats of fusion of the nitramines studied is described. These findings suggested analyzing the physico-chemical behavior of the nitramine crystals during this decomposition; in this connection an investigation was carried out using isothermal thermogravimetry and scanning electron microscopy of thermally exposed crystals of cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5-d]imidazole( sintering of its crystal surfaces),of β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane( cracking of its crystals during β !δ transition) and of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane. The results suggest a need to study the pre-decomposition states on thermal decomposition of the nitramines' molecule's crystals.
文摘This paper presents recent progress on the velocity measurement of pulverised coal in pneumatic pipelines using electrostatic sensors in combination with correlation signal processing techniques.A comparative study of electrostatic sensors with circular and probe electrodes was conducted on a 94 mm bore horizontal pipeline in a 4 MW furnace.The advantages and limitations of both sensors are discussed.Experimental results demonstrate that both sensors are capable of providing pulverised coal velocity measurement with excellent repeatability and dynamic response.
文摘In order to clear the activated area in electrostatic accelerator facilities,four accelerator facilities were selected and typical neutron emission experiments were performed.Neutron flux during operation and induced activity caused by charged particles on the accelerator and its surrounding area after irradiation were measured.Also the monitored neutron flux and calculated value by Monte Carlo calculation using PHITS code were compared.It was confirmed that the results between calculated data and measured data showed the good agreement with each other.Finally,it was concluded that we have to take care the activation of beam line and target.But,it is not necessary to treat accelerator tank,surrounding materials,and building concrete as radioactive materials in case of decommissioning.
基金financial support from the National Natural Science Foundation of China(Grant No.12102051)the State Key Laboratory of Explosion Science and Technology(Grant No.QNKT2022-04)。
文摘Due to its extremely low electrostatic sensitivity,copper azide primary explosive is greatly limited in practical applications.In this study,a composite film with Cu-MOF in-situ growth on carbon nanofilm was prepared by electrospinning and solvothermal methods,and CNF@Cu-N3film with electrostatic safety was obtained by carbonization and azide later.Its electrostatic sensitivity(E50)was greatly increased from 0.05 mJ of raw materials to 4.06 mJ,and still maintained a good detonation performance which could successfully detonate the CL-20 secondary explosive.This is mainly due to the synergistic effect of the carbon film and the MOF structure,which greatly improves the conductivity of the entire system and the uniform distribution of copper particles,providing a new preparation strategy for metal azide film that is suitable for the micro-initiator device.
基金Project supported by National Natural Science Foundation of China（51177173）, Elec- tromagnetic Environment Effect Key Laboratory Foundation（9140C87010313 JB34004）.
文摘A certain number of charges are deposited on the surface of high-voltage solar array because of effects of space plasma,high-energy charged particles,and solar illumination,hence the surface is charged.Phenomena of electrostatic discharge(ESD) occur on the surface when the deposited charges exceed a threshold amount.In this paper,the mechanism of this ESD is discussed.The ground simulation experiment of the ESD using spacecraft material under surface charging is described,and a novel ESD protecting method for high-voltage solar array,i.e.an active protecting method based on the local strong electric field array is proposed.The results show that the reversal potential gradient field between the cover surface and the substrate materials of high-voltage solar array is a triggering factor for the ESD on the array.The threshold voltage for the ESD occurring on the surface is about 500 V.The charged particles could be deflected using the electric field active protecting method,and hence the ESD on the surface is avoided even when the voltage on the conductor array increases to a certain value.These results pave the way for further developing the protecting measures for high-voltage solar arrays.
