An experimental system of AC arc discharge in water was designed with pole-pole electrodes and a peak voltage of 1500 V and a test circuit was set up using virtual instrument technology. The mechanism of an AC plasma ...An experimental system of AC arc discharge in water was designed with pole-pole electrodes and a peak voltage of 1500 V and a test circuit was set up using virtual instrument technology. The mechanism of an AC plasma arc generated in water was analyzed. The voltage- current characteristic of the AC plasma are was obtained from the waveform. The temperature characteristic was tested with a spectrum diagnosis system, and the effect of different electrode materials on the striking voltage and peak current was analyzed. The results show that when a power supply of 6 kW is applied on electrodes with a gap of 2 mm in water, the striking voltage is from 900 V to 1300 V, the arc voltage is from 40 V to 100 V, the arc current is from 2 A to 7 A, and the zero rest period is from 1 ms to 2 ms. In addition, the arc voltage and current are different for electrodes in aluminum, copper and stainless steel. The arc voltage is lower and the current is higher for an aluminum electrode than those for copper and stainless steel ones. The highest temperature of the arc is 7643 K.展开更多
Reduction of error due to the influence of temperature on the quartz flexible accelerometer without any heating device is a difficult task, and is also a tendency for research and application. In this paper, static an...Reduction of error due to the influence of temperature on the quartz flexible accelerometer without any heating device is a difficult task, and is also a tendency for research and application. In this paper, static and dynamic temperature compensation models are established in order to reduce the temperature influence on accelerometer measurement accuracy. Combined with the experiment data, the relationship between the accelerometer output accuracy, temperature and the magnitude of acceleration is analyzed. The data collected from the temperature experiment show that output value of the accelerometer varies with temperature. The method of uniaxial quadrature experiment is adopted and the accelerometer output value is gauged at temperature ranging from-20℃ to 50℃. Having used the static and the dynamic temperature compensation models, the accelerometer temperature error compensation experiment is conducted and the compensated errors by the two models are analyzed. The result shows that the compensated value meets the technical requirements. Two technical indicators, the zero bias K0 and the scaling factor K1, which are used to measure the degree of accelerometers, are both improved and their fluctuation ranges are reduced.展开更多
Generation characteristics of vacuum discharge plasma are very important for the applied research of metal plasma. The vacuum discharge electrode configuration and the cathode material affect the generation characteri...Generation characteristics of vacuum discharge plasma are very important for the applied research of metal plasma. The vacuum discharge electrode configuration and the cathode material affect the generation characteristics of the metal plasma which consists of metal ions coming from cathode and generated by vacuum discharge. In this research, the generation characteristics of the metal plasma generated by vacuum discharge are discussed for four patterns of electrode configurations, i.e. cone-mesh electrode setup, cone-cross line electrode setup, cone-line electrode setup and cone-ring electrode setup. Characteristics of the metal plasma, such as elec- tron density, electron temperature, space potential, ion energy, are measured by the probe method for discussing the impacts of different electrode configurations on the density of generated metal plasma. Moreover, the diffusion velocities of the metal plasma are measured for cathode materials of Pb, Al, and Cu, respectively. The experimental results indicate that the plasma generated by the discharge of cone-ring electrode configuration possesses the maximum density and the metal plasma generated by the Al cathode possesses the fastest diffusion velocity and the highest kinetic energy.展开更多
An individual＇s personal network is a basic object of study in sociology. This article analyzes and compares sina-weibo users＇ personal network size based on over 2 billion tweets gath- ered from over 1.3 million us...An individual＇s personal network is a basic object of study in sociology. This article analyzes and compares sina-weibo users＇ personal network size based on over 2 billion tweets gath- ered from over 1.3 million users in 2012. We propose a new measure method for the analysis of user interactions based on how an individual divides his attention across contacts and how user＇s characteristics affect the interactions. We find that the balance of attention of user with different age and gender is quite different in weibo. It displays interesting variation in both different groups of people and different modes of interaction.展开更多
he present paper covers tlie preparation and isolation of a series of monosub-stituted molybdophosphates Na_5 [PZ(H_2O)Mo_11 O_39]· 5H_2O (Z=Mn￣2+, Co￣2+,Ni￣2+, Cu￣2+, Zn￣2+)by an improved method. These comp...he present paper covers tlie preparation and isolation of a series of monosub-stituted molybdophosphates Na_5 [PZ(H_2O)Mo_11 O_39]· 5H_2O (Z=Mn￣2+, Co￣2+,Ni￣2+, Cu￣2+, Zn￣2+)by an improved method. These complexes were characterized byfull elemental analysis, IR spectra and UV-Vis. The studies show that the pre-pared products still keep Keggin structure and the substituting metal would belooated in coordination site. Based on this, their some pysico-cliemical propertiesrelated with their catalytic beliaviour,such as thermal stability and acidity proper-ty, were studied.展开更多
Rolling characteristics of the canard-controlled rocket with a free-spinning tail are researched based on 3-dimensional Navier–Stokes(N–S)equations.The slide mesh technology of computational fluid dynamics is used ...Rolling characteristics of the canard-controlled rocket with a free-spinning tail are researched based on 3-dimensional Navier–Stokes(N–S)equations.The slide mesh technology of computational fluid dynamics is used to numerically simulate the flow field when tails rotate relative to the rocket body and research the varying pattern of roll moment coefficients of the whole rocket,tail,and canard with Mach number.The comparison between the computation results and a part of experimental data shows that the simulation method is accurate.The convergence criterion during the numerical simulation is put forward;the induced rotation speed of the free-spinning tail and the roll moment coefficient of the rocket under this rotation in actual flight when the canard deflects by 10◦for roll control are obtained and the reason for the free-spinning tail being able to eliminate roll coupling is analyzed.The research provides a reference for the configuration design of canard-controlled rockets with a free-spinning tail and the numerical simulation of their aerodynamic characteristics.展开更多
We study how to achieve the state consensus of a whole multi-agent system after adding some new agent groups dynamically in the original multi-agent system.We analyze the feasibility of dynamically adding agent groups...We study how to achieve the state consensus of a whole multi-agent system after adding some new agent groups dynamically in the original multi-agent system.We analyze the feasibility of dynamically adding agent groups under differen t forms of net work topologies that are currently common,and obtain four feasible schemes in theory,including one scheme that is the best in actual industrial production.Then,we carry out dynamic modeling of multi-agent systems for the best scheme.Impulsive control theory and Lyapunov stability theory are used to analyze the conditions so that the whole multi-agent system with dynamic join characteristics can achieve state consensus.Finally,we provide a numerical example to verify the practicality and validity of the theory.展开更多
By mechanism transformation (anionic cationic) polymerization, diblock copolymer of butadiene and 2 ethyl 2 oxazoline (PBd b PEOx) was synthesized in two steps. The first step is the polymerization of butadiene bloc...By mechanism transformation (anionic cationic) polymerization, diblock copolymer of butadiene and 2 ethyl 2 oxazoline (PBd b PEOx) was synthesized in two steps. The first step is the polymerization of butadiene block capped with ethylene oxide and its tosylation; the second step is the cationic ring opening polymerization of 2 ethyl 2 oxazoline. The products were characterized by various methods, such as IR, 1HNMR, DMA, TEM and SAXS. The results show that the obtained copolymers possess high molecular weight and narrow molecular weight distribution, and that the content of 1,4 structure was controllable.展开更多
基金supported by National Natural Science Foundation of China (No. 50777014)
文摘An experimental system of AC arc discharge in water was designed with pole-pole electrodes and a peak voltage of 1500 V and a test circuit was set up using virtual instrument technology. The mechanism of an AC plasma arc generated in water was analyzed. The voltage- current characteristic of the AC plasma are was obtained from the waveform. The temperature characteristic was tested with a spectrum diagnosis system, and the effect of different electrode materials on the striking voltage and peak current was analyzed. The results show that when a power supply of 6 kW is applied on electrodes with a gap of 2 mm in water, the striking voltage is from 900 V to 1300 V, the arc voltage is from 40 V to 100 V, the arc current is from 2 A to 7 A, and the zero rest period is from 1 ms to 2 ms. In addition, the arc voltage and current are different for electrodes in aluminum, copper and stainless steel. The arc voltage is lower and the current is higher for an aluminum electrode than those for copper and stainless steel ones. The highest temperature of the arc is 7643 K.
基金supported by the Importation and Development of High-caliber Talents Project of Beijing Municipal Institutions(No.IT&TCD201304115)
文摘Reduction of error due to the influence of temperature on the quartz flexible accelerometer without any heating device is a difficult task, and is also a tendency for research and application. In this paper, static and dynamic temperature compensation models are established in order to reduce the temperature influence on accelerometer measurement accuracy. Combined with the experiment data, the relationship between the accelerometer output accuracy, temperature and the magnitude of acceleration is analyzed. The data collected from the temperature experiment show that output value of the accelerometer varies with temperature. The method of uniaxial quadrature experiment is adopted and the accelerometer output value is gauged at temperature ranging from-20℃ to 50℃. Having used the static and the dynamic temperature compensation models, the accelerometer temperature error compensation experiment is conducted and the compensated errors by the two models are analyzed. The result shows that the compensated value meets the technical requirements. Two technical indicators, the zero bias K0 and the scaling factor K1, which are used to measure the degree of accelerometers, are both improved and their fluctuation ranges are reduced.
文摘Generation characteristics of vacuum discharge plasma are very important for the applied research of metal plasma. The vacuum discharge electrode configuration and the cathode material affect the generation characteristics of the metal plasma which consists of metal ions coming from cathode and generated by vacuum discharge. In this research, the generation characteristics of the metal plasma generated by vacuum discharge are discussed for four patterns of electrode configurations, i.e. cone-mesh electrode setup, cone-cross line electrode setup, cone-line electrode setup and cone-ring electrode setup. Characteristics of the metal plasma, such as elec- tron density, electron temperature, space potential, ion energy, are measured by the probe method for discussing the impacts of different electrode configurations on the density of generated metal plasma. Moreover, the diffusion velocities of the metal plasma are measured for cathode materials of Pb, Al, and Cu, respectively. The experimental results indicate that the plasma generated by the discharge of cone-ring electrode configuration possesses the maximum density and the metal plasma generated by the Al cathode possesses the fastest diffusion velocity and the highest kinetic energy.
基金Supported by the National Natural Science Foundation of China(61272109)the Natural Science Foundation of Hubei Province of China(2014CFB289)
文摘An individual＇s personal network is a basic object of study in sociology. This article analyzes and compares sina-weibo users＇ personal network size based on over 2 billion tweets gath- ered from over 1.3 million users in 2012. We propose a new measure method for the analysis of user interactions based on how an individual divides his attention across contacts and how user＇s characteristics affect the interactions. We find that the balance of attention of user with different age and gender is quite different in weibo. It displays interesting variation in both different groups of people and different modes of interaction.
文摘he present paper covers tlie preparation and isolation of a series of monosub-stituted molybdophosphates Na_5 [PZ(H_2O)Mo_11 O_39]· 5H_2O (Z=Mn￣2+, Co￣2+,Ni￣2+, Cu￣2+, Zn￣2+)by an improved method. These complexes were characterized byfull elemental analysis, IR spectra and UV-Vis. The studies show that the pre-pared products still keep Keggin structure and the substituting metal would belooated in coordination site. Based on this, their some pysico-cliemical propertiesrelated with their catalytic beliaviour,such as thermal stability and acidity proper-ty, were studied.
文摘Rolling characteristics of the canard-controlled rocket with a free-spinning tail are researched based on 3-dimensional Navier–Stokes(N–S)equations.The slide mesh technology of computational fluid dynamics is used to numerically simulate the flow field when tails rotate relative to the rocket body and research the varying pattern of roll moment coefficients of the whole rocket,tail,and canard with Mach number.The comparison between the computation results and a part of experimental data shows that the simulation method is accurate.The convergence criterion during the numerical simulation is put forward;the induced rotation speed of the free-spinning tail and the roll moment coefficient of the rocket under this rotation in actual flight when the canard deflects by 10◦for roll control are obtained and the reason for the free-spinning tail being able to eliminate roll coupling is analyzed.The research provides a reference for the configuration design of canard-controlled rockets with a free-spinning tail and the numerical simulation of their aerodynamic characteristics.
基金Project supported by the National Natural Science Foundation of China(No.61873213)the Chongqing Graduate Research and Innovation Project in 2019,China(No.CYB19175)the Major Project of Science and Technology Research Program of Chongqing Education Commission of China(No.KJZDM201900601)。
文摘We study how to achieve the state consensus of a whole multi-agent system after adding some new agent groups dynamically in the original multi-agent system.We analyze the feasibility of dynamically adding agent groups under differen t forms of net work topologies that are currently common,and obtain four feasible schemes in theory,including one scheme that is the best in actual industrial production.Then,we carry out dynamic modeling of multi-agent systems for the best scheme.Impulsive control theory and Lyapunov stability theory are used to analyze the conditions so that the whole multi-agent system with dynamic join characteristics can achieve state consensus.Finally,we provide a numerical example to verify the practicality and validity of the theory.
文摘By mechanism transformation (anionic cationic) polymerization, diblock copolymer of butadiene and 2 ethyl 2 oxazoline (PBd b PEOx) was synthesized in two steps. The first step is the polymerization of butadiene block capped with ethylene oxide and its tosylation; the second step is the cationic ring opening polymerization of 2 ethyl 2 oxazoline. The products were characterized by various methods, such as IR, 1HNMR, DMA, TEM and SAXS. The results show that the obtained copolymers possess high molecular weight and narrow molecular weight distribution, and that the content of 1,4 structure was controllable.
