摘要 :
In this review we describe the kinetics of non-equilibrium discharge plasma when the ion composition is dominated by water or hydrocarbon ions. Plasmas with water ions are formed in atmospheric discharges and discharges in the pre...
展开
In this review we describe the kinetics of non-equilibrium discharge plasma when the ion composition is dominated by water or hydrocarbon ions. Plasmas with water ions are formed in atmospheric discharges and discharges in the presence of liquid water or water vapor, including plasma applications for air purification, medicine and combustion. Reactions with hydrocarbon ions play an important role in interstellar chemistry, plasma enhanced chemical vapor deposition, synthetic diamond film deposition and plasma assisted combustion. The modeling of water ion chemistry and chemistry of hydrocarbon-containing plasmas requires large amount of data on the rates of ion formation and loss. This review provides the core database for the rate coefficients describing the kinetics of charged particles in plasmas with water and hydrocarbon ions as a function of temperature, pressure, and local electric field. Particular attention is given to cluster ions, which are important at not-too-low gas pressures, whereas the majority of studies of ion-molecule reactions have been performed at low pressures in the absence of cluster ions. To illustrate importance of the described processes, the development of streamer discharges in long humid air gaps are discussed and the influence of water ions on the streamer properties is demonstrated. In addition, the decay of non-equilibrium plasma with water and hydrocarbon ions is analyzed in combustible gaseous mixtures excited by a repetitively pulsed nanosecond discharge.
收起
摘要 :
In this review we describe the kinetics of non-equilibrium discharge plasma when the ion composition is dominated by water or hydrocarbon ions. Plasmas with water ions are formed in atmospheric discharges and discharges in the pre...
展开
In this review we describe the kinetics of non-equilibrium discharge plasma when the ion composition is dominated by water or hydrocarbon ions. Plasmas with water ions are formed in atmospheric discharges and discharges in the presence of liquid water or water vapor, including plasma applications for air purification, medicine and combustion. Reactions with hydrocarbon ions play an important role in interstellar chemistry, plasma enhanced chemical vapor deposition, synthetic diamond film deposition and plasma assisted combustion. The modeling of water ion chemistry and chemistry of hydrocarbon-containing plasmas requires large amount of data on the rates of ion formation and loss. This review provides the core database for the rate coefficients describing the kinetics of charged particles in plasmas with water and hydrocarbon ions as a function of temperature, pressure, and local electric field. Particular attention is given to cluster ions, which are important at not-too-low gas pressures, whereas the majority of studies of ion-molecule reactions have been performed at low pressures in the absence of cluster ions. To illustrate importance of the described processes, the development of streamer discharges in long humid air gaps are discussed and the influence of water ions on the streamer properties is demonstrated. In addition, the decay of non-equilibrium plasma with water and hydrocarbon ions is analyzed in combustible gaseous mixtures excited by a repetitively pulsed nanosecond discharge.
收起
摘要 :
Process mining techniques aim to analyze and improve con-formance and performance of processes using event data. Process discovery is the most prominent process-mining task: A process model is derived based on an event log. The pr...
展开
Process mining techniques aim to analyze and improve con-formance and performance of processes using event data. Process discovery is the most prominent process-mining task: A process model is derived based on an event log. The process model should be able to capture causalities, choices, concurrency, and loops. Process discovery is very challenging because of trade-offs between fitness, simplicity, precision, and generalization. Note that event logs typically only hold example behavior and cannot be assumed to be complete (to avoid overfitting). Dozens of process discovery techniques have been proposed. These use a wide range of approaches, e.g., language- or state-based regions, genetic mining, heuristics, expectation maximization, iterative log-splitting, etc. When models or logs become too large for analysis, the event log may be automatically decomposed or traces may be clustered before discovery. Clustering and decomposition are done automatically, i.e., no additional information is used. This paper proposes a different approach where a localized event log is assumed. Events are localized by assigning a nonempty set of regions to each event. It is assumed that regions can only interact through shared events. Consider for example the mining of software systems. The events recorded typically explicitly refer to parts of the system (components, services, etc.). Currently, such information is ignored during discovery. However, references to system parts may be used to localize events. Also in other application domains, it is possible to localize events, e.g., communication events in an organization may refer to multiple departments (that may be seen as regions). This paper proposes a generic process discovery approach based on localized event logs. The approach has been implemented in ProM and experimental results show that location information indeed helps to improve the quality of the discovered models.
收起
摘要 :
A 2D numerical simulation of the positive streamer properties was performed in 9-12 cm plane-to-plane air gaps for various pressures and water vapor contents. It was shown that an increase in air humidity leads to hampering the st...
展开
A 2D numerical simulation of the positive streamer properties was performed in 9-12 cm plane-to-plane air gaps for various pressures and water vapor contents. It was shown that an increase in air humidity leads to hampering the streamer development and to increasing the average critical electric field required for bridging the discharge gap. The effect of humidity was most profound at atmospheric pressure and decreased with decreasing pressure. The influence of water content on the streamer properties was explained by a decrease in the streamer channel conductivity due to dissociative recombination of electrons with positive hydrated ions and enhanced three-body electron attachment to O_2 molecules. The calculated critical electric field in humid air gaps was compared with available experimental data.
收起
摘要 :
We used technology of making high-efficiency superconducting single-photon detectors as a basis for improvement of photon-number-resolving devices. By adding optical cavity and using an improved NbN superconducting film, we enhanc...
展开
We used technology of making high-efficiency superconducting single-photon detectors as a basis for improvement of photon-number-resolving devices. By adding optical cavity and using an improved NbN superconducting film, we enhanced previously reported system detection efficiency at telecom range for such detectors. Our results show that implementation of optical cavity helps to develop four-section device with quantum efficiency over 50% at 1.55 μm. Performed experimental studies of detecting multi-photon optical pulses showed irregularities over defining multi-photon through single-photon quantum efficiency.
收起
摘要 :
Numerical characterization of nanosecond pulsed discharges has been conducted in a strong magnetic field environment. Streamer discharge development and plasma generation in pure CO_2 was analyzed when magnetic field was directed ...
展开
Numerical characterization of nanosecond pulsed discharges has been conducted in a strong magnetic field environment. Streamer discharge development and plasma generation in pure CO_2 was analyzed when magnetic field was directed along the axis of the discharge cell. Numerical simulations were based of a two-dimensional fluid model. It is shown that strong magnetic field affect dramatically on the plasma formation. The NS streamer diameter decreases significantly, plasma density increases. Calculations were carried out for different magnetic field values for fixed CO_2 pressure P = 50 Torr and fixed NS pulse voltage U = 20 kV.
收起
摘要 :
Changes in the pulse amplitude, and voltage rise time do not cause a significant change in the field in the streamer channel, which remains at the level E_(ch) ～ 5 kV/cm in the range from 5 kV to 1000 kV. The length of the stream...
展开
Changes in the pulse amplitude, and voltage rise time do not cause a significant change in the field in the streamer channel, which remains at the level E_(ch) ～ 5 kV/cm in the range from 5 kV to 1000 kV. The length of the streamer propagation essentially depends on the anode radius (through velocity). The field in the channel depends on the electrode radius only at small distances. The pulse rise time has practically no effect on the field in the channel, streamer velocity and propagation distance. The kinetics of ionization and recombination significantly change both the electric field in the channel and the propagation distance of the streamer.
收起
摘要 :
Changes in the pulse amplitude, and voltage rise time do not cause a significant change in the field in the streamer channel, which remains at the level E_(ch) ～5 kV/cm in the range from 5 kV to 1000 kV. The length of the streame...
展开
Changes in the pulse amplitude, and voltage rise time do not cause a significant change in the field in the streamer channel, which remains at the level E_(ch) ～5 kV/cm in the range from 5 kV to 1000 kV. The length of the streamer propagation essentially depends on the anode radius (through velocity). The field in the channel depends on the electrode radius only at small distances. The pulse rise time has practically no effect on the field in the channel, streamer velocity and propagation distance. The kinetics of ionization and recombination significantly change both the electric field in the channel and the propagation distance of the streamer.
收起
摘要 :
This paper develops the concept of possibility of using nanoconductive dielectrics in printed circuit boards instead of traditional ones. The symmetrical multivibrator was taken as an example of typical digital device and the comp...
展开
This paper develops the concept of possibility of using nanoconductive dielectrics in printed circuit boards instead of traditional ones. The symmetrical multivibrator was taken as an example of typical digital device and the computer simulations were performed using the LTspice software. Nanoconductive dielectrics have less electrificability, thus provide fewer electrostatic discharges (ESD) caused by the action of electron irradiation. Based on the results of computer simulations and calculations the dielectric parameters of the printed circuit board for which ESD are physically impossible were determined. It was shown that the change in the output parameters of the multivibrator does not exceed 5\%. Therefore, it is possible and necessary to use nanoconductive dielectrics in the on-board radio electronic systems and equipment of space vehicles. According to our data, such dielectrics discharge-free, also conductivity raised to 10
-9
Ω
-
Ω
-1
does not affect the operation of the electronics.
收起
摘要 :
This paper develops the concept of possibility of using nanoconductive dielectrics in printed circuit boards instead of traditional ones. The symmetrical multivibrator was taken as an example of typical digital device and the comp...
展开
This paper develops the concept of possibility of using nanoconductive dielectrics in printed circuit boards instead of traditional ones. The symmetrical multivibrator was taken as an example of typical digital device and the computer simulations were performed using the LTspice software. Nanoconductive dielectrics have less electrificability, thus provide fewer electrostatic discharges (ESD) caused by the action of electron irradiation. Based on the results of computer simulations and calculations the dielectric parameters of the printed circuit board for which ESD are physically impossible were determined. It was shown that the change in the output parameters of the multivibrator does not exceed 5\%. Therefore, it is possible and necessary to use nanoconductive dielectrics in the on-board radio electronic systems and equipment of space vehicles. According to our data, such dielectrics discharge-free, also conductivity raised to 10
-9
Ω
-
Ω
-1
does not affect the operation of the electronics.
收起
原文获取