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
The growth and development of Jingjiang Taro [Colocasia esculenta（L.） Schott] were observed, laying foundation for highly-yielding cultivation technology system of Xiangsha taro. The results indicate that germinatio...The growth and development of Jingjiang Taro [Colocasia esculenta（L.） Schott] were observed, laying foundation for highly-yielding cultivation technology system of Xiangsha taro. The results indicate that germination of the second taro happened from 46 d after sprouting （7-8 leaves）; the first taro began to expand, from 125 d after sprouting （12 leaves） when the the second taro was been formed; the third taro began to form from 141 to 150 d after sprouting （15-16 leaves）. The fresh weight of the second and third taros quickly increased from the time of 15 leaves to harvest. Early September is a transformation term of Xiangsha taro from vegetative body dominant to corm growth dominant.展开更多
To explore the high-yield cultivation methods of Zhuliangyou 4024 and H You 159 when planted as double-cropping rice, the effects of two cultivation meth- ods, i.e., seedling broadcasting and transplanting, were studi...To explore the high-yield cultivation methods of Zhuliangyou 4024 and H You 159 when planted as double-cropping rice, the effects of two cultivation meth- ods, i.e., seedling broadcasting and transplanting, were studied on SPAD value, photosynthetic rate, grain yield and yield components. The results showed that the seedling broadcasting cultivation was conducive to Zhuliangyou 4024 and H You 159 to obtain higher yield. The higher chlorophyll content and photosynthetic rate and their slower decrease of flag leaf after full heading of the seedling broadcasting cultivation were thought to be the physiological basis of high yield.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
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
The different physical states of saturated sand, including shear elasticity, positive dilatancy, and negative dilatancy (preliminary negative dilatancy, secondary negative dilatancy and reversal negative dilatancy) ar...The different physical states of saturated sand, including shear elasticity, positive dilatancy, and negative dilatancy (preliminary negative dilatancy, secondary negative dilatancy and reversal negative dilatancy) are revealed based on the pore water pressure response of saturated sand in undrained dynamic torsional tests of thin cylinder samples and also checked by the drained cyclic triaxial tests under a given mean effective normal stress. According to the effective stress path of different physical states under the undrained cyclic torsional tests the physical state transformation surface, stress history boundary and yield surface are determined, and the state boundary surface is also determined by the range of effective frictional stress state movement. Based on the moving yield surface without rotation, and the expanding stress history boundary surface relevant to the stress path variations under different physical states in 3D stress space, a physical state model is proposed to provide a new approach to calculating the transient pore water pressure under the undrained condition, and the volume strain of dilatation under drained condition in this paper.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 Jiangsu Self-innovation Fund for Agricultural Science and Technology[CX(12)2008]~~
文摘The growth and development of Jingjiang Taro [Colocasia esculenta（L.） Schott] were observed, laying foundation for highly-yielding cultivation technology system of Xiangsha taro. The results indicate that germination of the second taro happened from 46 d after sprouting （7-8 leaves）; the first taro began to expand, from 125 d after sprouting （12 leaves） when the the second taro was been formed; the third taro began to form from 141 to 150 d after sprouting （15-16 leaves）. The fresh weight of the second and third taros quickly increased from the time of 15 leaves to harvest. Early September is a transformation term of Xiangsha taro from vegetative body dominant to corm growth dominant.
基金Supported by National Agricultural Science Technology Achievement Transformation Fund(2010GB2D200314)Natural Science Foundation of China(31101134)~~
文摘To explore the high-yield cultivation methods of Zhuliangyou 4024 and H You 159 when planted as double-cropping rice, the effects of two cultivation meth- ods, i.e., seedling broadcasting and transplanting, were studied on SPAD value, photosynthetic rate, grain yield and yield components. The results showed that the seedling broadcasting cultivation was conducive to Zhuliangyou 4024 and H You 159 to obtain higher yield. The higher chlorophyll content and photosynthetic rate and their slower decrease of flag leaf after full heading of the seedling broadcasting cultivation were thought to be the physiological basis of high yield.
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.
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.
基金Project supported by the National Natural Science Foundation of China (No.10172071) the Natural Science Foundation of Shaanxi Province.
文摘The different physical states of saturated sand, including shear elasticity, positive dilatancy, and negative dilatancy (preliminary negative dilatancy, secondary negative dilatancy and reversal negative dilatancy) are revealed based on the pore water pressure response of saturated sand in undrained dynamic torsional tests of thin cylinder samples and also checked by the drained cyclic triaxial tests under a given mean effective normal stress. According to the effective stress path of different physical states under the undrained cyclic torsional tests the physical state transformation surface, stress history boundary and yield surface are determined, and the state boundary surface is also determined by the range of effective frictional stress state movement. Based on the moving yield surface without rotation, and the expanding stress history boundary surface relevant to the stress path variations under different physical states in 3D stress space, a physical state model is proposed to provide a new approach to calculating the transient pore water pressure under the undrained condition, and the volume strain of dilatation under drained condition in this paper.
