Based on the scheme of damped harmonic oscillator quantization and thermo-field dynamics （TFD）, the quantization of mesoscopic damped double resonance RLC circuit with mutual capacitance-inductance coupling is propo...Based on the scheme of damped harmonic oscillator quantization and thermo-field dynamics （TFD）, the quantization of mesoscopic damped double resonance RLC circuit with mutual capacitance-inductance coupling is proposed. The quantum fluctuations of charge and current of each loop in a squeezed vacuum state are studied in the thermal excitation case. It is shown that the fluctuations not only depend on circuit inherent parameters, but also rely on excitation quantum number and squeezing parameter. Moreover, due to the finite environmental temperature and damped resistance, the fluctuations increase with the temperature rising, and decay with time.展开更多
In recent years,several failures of double circuit transmission line on the same tower due to lightning were happened in Beijing power grid.Although it can be reclosed successful,the lightning strike caused a grave th...In recent years,several failures of double circuit transmission line on the same tower due to lightning were happened in Beijing power grid.Although it can be reclosed successful,the lightning strike caused a grave threat to the power grid security.The cause of the accident and the accident process were studied for the sake of further understanding of the impact of lightning on power grid.As an example,110 kV double circuit transmission line(Xilong-line) was analyzed.At first,the system topology was given.Through the analysis on relay protection actions and the fault recorder data,over voltage on the insulator strings was calculated.Based on the analysis and the calculation,accident cause and the process were presented respectively.Secondly,it comes to the conclusion that the lightning failure was caused by counterattack.The wave of the lightning over voltage would spread to the not grounded neutral point of the transformers,and make the neutral protective gap breakdown,then cause freewheeling with the frequency of 50 Hz.As results of the relay protection,the double circuit transmission line all tripped out.Finally,the causes of the accident were proposed that included terrain features,large corner towers,strong thunderstorm weather and poor grounded contact of the tower.展开更多
In the de-icing process of double-circuit direct current(DC)transmission lines on the same tower,an operational condition exists in which one circuit is de-energised and utilised as part of the de-icing current path,s...In the de-icing process of double-circuit direct current(DC)transmission lines on the same tower,an operational condition exists in which one circuit is de-energised and utilised as part of the de-icing current path,specifically designed for grounding line de-icing purposes.Accurate calculation of the floating potential of the out-of-service line is crucial for the design of de-icing devices.This study employs the upstream finite element method combined with a potential prediction correction approach to determine the floating potential of de-energised conductors.A field-circuit model is proposed for calculating conductor floating potentials under single-circuit outage conditions in double-circuit DC transmission lines.The charge dissipation process through grounding resistors with varying values is also analysed.In a�500 kV case study,the relative errors between the circuit model and electric field model calculations for the positive and negative conductor floating potentials are merely 3.66%and 0.89%,respectively,verifying the validity of the circuit model.The equivalent resistance of ion flow fields reaches magnitudes of 106Ω,significantly exceeding the intrinsic resistance of the conductors.When using voltage-limiting resistors,conductor voltages decrease significantly with a 0.5-MΩresistor,and the calculated floating potentials become 8.702 kV and−5.849 kV,reflecting reductions of 84.8%and 88.4%,respectively.This research demonstrates that the proposed method provides an effective solution for floating potential calculation during single-circuit outages in double-circuit DC lines.The analysis of charge dissipation through voltage-limiting resistors offers technical support for designing DC de-icing devices.展开更多
In this paper, the authors discuss the upper bound for the genus of strong embeddings for 3-connected planar graphs on higher surfaces. It is shown that the problem of determining the upper bound for the strong embedd...In this paper, the authors discuss the upper bound for the genus of strong embeddings for 3-connected planar graphs on higher surfaces. It is shown that the problem of determining the upper bound for the strong embedding of 3-connected planar near-triangulations on higher non-orientable surfaces is NP-hard. As a corollary, a theorem of Richter, Seymour and Siran about the strong embedding of 3-connected planar graphs is generalized to orientable surface.展开更多
Through the monitoring of mcs-400 mine intrinsically safe anchor cable dynamometer, it is found that after the anchor cable is stretched in place, and the actual displayed data of the dynamometer deviates greatly from...Through the monitoring of mcs-400 mine intrinsically safe anchor cable dynamometer, it is found that after the anchor cable is stretched in place, and the actual displayed data of the dynamometer deviates greatly from the theoretical value, and large prestress loss is caused by factors such as anchor cable relaxation, coal and rock compression creep, water and temperature, dynamic load influence, tunnel friction, group anchor effect and construction quality. The prestress plays a decisive role in the ability of anchor bolt support to control the deformation of surrounding rock. Through detailed cause analysis and test and measurement, the quality of locks and the matching of locks and jacks are determined, which has a serious impact on the prestress loss of anchor cable. And put forward the patent double circuit secondary tension jack of the utility model to further release the mechanical connection between the top anchor pipe (inner ring) of the tension jack and the top presser body (outer ring), and expand the lock ring and lock core of the anchor cable lock twice, which can further eliminate the influence of the matching problem between the lock and the jack top, improve the effective prestress, and ensure the safety and quality of the roof support.展开更多
Rechargeable lithium-metal batteries that are operated based on reversible metal plating and stripping during the charge/discharge process are known for their high energy density far beyond the conventional,graphite-a...Rechargeable lithium-metal batteries that are operated based on reversible metal plating and stripping during the charge/discharge process are known for their high energy density far beyond the conventional,graphite-anode-based Li-ion batteries[1].However,the hostless structural evolution of Li metal during the anode process easily forms dendrites and could lead to a hazardous short circuit of batteries[2].In addition.展开更多
A near-triangulation is such a connected planar graph whose inner faces are all triangles but the outer face may be not. Let G be a near-triangulation of order n and C be an SCDC (small circuit double cover)[2] of G. ...A near-triangulation is such a connected planar graph whose inner faces are all triangles but the outer face may be not. Let G be a near-triangulation of order n and C be an SCDC (small circuit double cover)[2] of G. Let Then, C0 is said to he an equilibrium SCDC of G. In this paper, we show that if G is an outer planar graph, δ(C0)≤2, otherwiseδ(C0) ≤4.展开更多
X-band accelerators for multi-bunches are a new way to produce high luminosity and energy efficiency bunches. The smaller the size and the more bunches, the more severe is the wakefield in the X-band accelerators, unl...X-band accelerators for multi-bunches are a new way to produce high luminosity and energy efficiency bunches. The smaller the size and the more bunches, the more severe is the wakefield in the X-band accelerators, unless some means of strongly suppressing the transverse wakefield is adopted in the design of the accelerating structure. Here, the derivation of the wakefield function of the double circuit model and its application to the designed accelerator structure have been demonstrated.展开更多
基金Project supported by the Natural Science Foundation of Heze University of Shandong Province, China （Grant No XY05WL01）, the University Experimental Technology Foundation of Shandong Province, China （Grant No S04W138）, the Natural Science Foundation of Shandong Province, China （Grant No Y2004A09） and the National Natural Science Foundation of China （Grant No 10574060）.
文摘Based on the scheme of damped harmonic oscillator quantization and thermo-field dynamics （TFD）, the quantization of mesoscopic damped double resonance RLC circuit with mutual capacitance-inductance coupling is proposed. The quantum fluctuations of charge and current of each loop in a squeezed vacuum state are studied in the thermal excitation case. It is shown that the fluctuations not only depend on circuit inherent parameters, but also rely on excitation quantum number and squeezing parameter. Moreover, due to the finite environmental temperature and damped resistance, the fluctuations increase with the temperature rising, and decay with time.
文摘In recent years,several failures of double circuit transmission line on the same tower due to lightning were happened in Beijing power grid.Although it can be reclosed successful,the lightning strike caused a grave threat to the power grid security.The cause of the accident and the accident process were studied for the sake of further understanding of the impact of lightning on power grid.As an example,110 kV double circuit transmission line(Xilong-line) was analyzed.At first,the system topology was given.Through the analysis on relay protection actions and the fault recorder data,over voltage on the insulator strings was calculated.Based on the analysis and the calculation,accident cause and the process were presented respectively.Secondly,it comes to the conclusion that the lightning failure was caused by counterattack.The wave of the lightning over voltage would spread to the not grounded neutral point of the transformers,and make the neutral protective gap breakdown,then cause freewheeling with the frequency of 50 Hz.As results of the relay protection,the double circuit transmission line all tripped out.Finally,the causes of the accident were proposed that included terrain features,large corner towers,strong thunderstorm weather and poor grounded contact of the tower.
基金supported by the Science and Technology Project of State Grid Corporation of China(5200-202455431A-3-6-RW).
文摘In the de-icing process of double-circuit direct current(DC)transmission lines on the same tower,an operational condition exists in which one circuit is de-energised and utilised as part of the de-icing current path,specifically designed for grounding line de-icing purposes.Accurate calculation of the floating potential of the out-of-service line is crucial for the design of de-icing devices.This study employs the upstream finite element method combined with a potential prediction correction approach to determine the floating potential of de-energised conductors.A field-circuit model is proposed for calculating conductor floating potentials under single-circuit outage conditions in double-circuit DC transmission lines.The charge dissipation process through grounding resistors with varying values is also analysed.In a�500 kV case study,the relative errors between the circuit model and electric field model calculations for the positive and negative conductor floating potentials are merely 3.66%and 0.89%,respectively,verifying the validity of the circuit model.The equivalent resistance of ion flow fields reaches magnitudes of 106Ω,significantly exceeding the intrinsic resistance of the conductors.When using voltage-limiting resistors,conductor voltages decrease significantly with a 0.5-MΩresistor,and the calculated floating potentials become 8.702 kV and−5.849 kV,reflecting reductions of 84.8%and 88.4%,respectively.This research demonstrates that the proposed method provides an effective solution for floating potential calculation during single-circuit outages in double-circuit DC lines.The analysis of charge dissipation through voltage-limiting resistors offers technical support for designing DC de-icing devices.
文摘In this paper, the authors discuss the upper bound for the genus of strong embeddings for 3-connected planar graphs on higher surfaces. It is shown that the problem of determining the upper bound for the strong embedding of 3-connected planar near-triangulations on higher non-orientable surfaces is NP-hard. As a corollary, a theorem of Richter, Seymour and Siran about the strong embedding of 3-connected planar graphs is generalized to orientable surface.
文摘Through the monitoring of mcs-400 mine intrinsically safe anchor cable dynamometer, it is found that after the anchor cable is stretched in place, and the actual displayed data of the dynamometer deviates greatly from the theoretical value, and large prestress loss is caused by factors such as anchor cable relaxation, coal and rock compression creep, water and temperature, dynamic load influence, tunnel friction, group anchor effect and construction quality. The prestress plays a decisive role in the ability of anchor bolt support to control the deformation of surrounding rock. Through detailed cause analysis and test and measurement, the quality of locks and the matching of locks and jacks are determined, which has a serious impact on the prestress loss of anchor cable. And put forward the patent double circuit secondary tension jack of the utility model to further release the mechanical connection between the top anchor pipe (inner ring) of the tension jack and the top presser body (outer ring), and expand the lock ring and lock core of the anchor cable lock twice, which can further eliminate the influence of the matching problem between the lock and the jack top, improve the effective prestress, and ensure the safety and quality of the roof support.
基金supported by the National Natural Science Foundation of China(22279028,22179018)the Natural Science Foundation of Hebei Province(B2021205019)the 333 Project of Hebei Province(C20231106).
文摘Rechargeable lithium-metal batteries that are operated based on reversible metal plating and stripping during the charge/discharge process are known for their high energy density far beyond the conventional,graphite-anode-based Li-ion batteries[1].However,the hostless structural evolution of Li metal during the anode process easily forms dendrites and could lead to a hazardous short circuit of batteries[2].In addition.
基金Supported by the National Natural Science Foundation of China (69973001)
文摘A near-triangulation is such a connected planar graph whose inner faces are all triangles but the outer face may be not. Let G be a near-triangulation of order n and C be an SCDC (small circuit double cover)[2] of G. Let Then, C0 is said to he an equilibrium SCDC of G. In this paper, we show that if G is an outer planar graph, δ(C0)≤2, otherwiseδ(C0) ≤4.
文摘X-band accelerators for multi-bunches are a new way to produce high luminosity and energy efficiency bunches. The smaller the size and the more bunches, the more severe is the wakefield in the X-band accelerators, unless some means of strongly suppressing the transverse wakefield is adopted in the design of the accelerating structure. Here, the derivation of the wakefield function of the double circuit model and its application to the designed accelerator structure have been demonstrated.
