New tunnelling underneath could influence existing shield tunnels in underground spaces.The evaluation of the influences of tunnelling-induced ground movements on existing tunnels has been a major concern during urban...New tunnelling underneath could influence existing shield tunnels in underground spaces.The evaluation of the influences of tunnelling-induced ground movements on existing tunnels has been a major concern during urban construction.This paper presents a two-stage analytical method that considers the asymmetric ground settlement for investigating the longitudinal tunnel responses to new tunnelling.An improved semi-analytical solution considering the horizontal movement of the new tunnel is established for evaluating the tunnelling-induced asymmetric greenfield settlement.The proposed method is verified with field measurement data from a case study.A parametric analysis is conducted to study the influences of the input parameters on the tunnel responses.Results indicate that the horizontal movement of the new tunnel due to bias loading or asymmetric construction may lead to asymmetric responses of the existing tunnel.With increasing tunnel horizontal movement,the asymmetry of the tunnel responses becomes more obvious.An increase in the pillar depth and decreases in the tunnel horizontal movement and skew angle lower the internal forces induced by new tunnelling.展开更多
Two semi-asymmetric flow patterns of typhoons are chosen to qualitatively determine the effect of exchange of horizontal momentum between inflow and outflow layers and the environment on the motion of typhoons. The re...Two semi-asymmetric flow patterns of typhoons are chosen to qualitatively determine the effect of exchange of horizontal momentum between inflow and outflow layers and the environment on the motion of typhoons. The results show that only the asymmetric flow component (residual after azimuthal mean flow has been removed) could cause a net momentum input into or output from a typhoon and therefore contribute to the changes in speed and direction of the typhoon movement. A typhoon with major inflow and/or outflow channels on its right (left ) side would tend to accelerate and turn left (decelerate and turn right); On the other hand, a typhoon with major inflow and/or outflow channels in the rear (front) semicircle would tend to accelerate and turn right (decelerate and turn left).展开更多
We introduce a new class of partially coherent asymmetric array beams. When the beam propagates, the spectral density of each lobe and the corresponding degree of coherence have rotating behavior. Especially, not only...We introduce a new class of partially coherent asymmetric array beams. When the beam propagates, the spectral density of each lobe and the corresponding degree of coherence have rotating behavior. Especially, not only can array-like lattices revolve arbitrarily, but also they can move freely by controlling transverse plane shifts. Furthermore, we have generated this kind of beam experimentally, and the experimental phenomena are consistent with the numerical simulation results. Such a rotating beam with free movement and revolution may broaden the way for optical applications. More importantly, it inspires further studies in the field of asymmetric coherence gratings and lattices.展开更多
Multifaceted asymmetric radiation from the edge(MARFE) movement which can cause density limit disruption is often encountered during high density operation on many tokamaks. Therefore, identifying and predicting MARFE...Multifaceted asymmetric radiation from the edge(MARFE) movement which can cause density limit disruption is often encountered during high density operation on many tokamaks. Therefore, identifying and predicting MARFE movement is meaningful to mitigate or avoid density limit disruption for the steady-state high-density plasma operation. A machine learning method named random forest(RF) has been used to predict the MARFE movement based on the density ramp-up experiment in the 2022’s first campaign of Experimental Advanced Superconducting Tokamak(EAST). The RF model shows that besides Greenwald fraction which is the ratio of plasma density and Greenwald density limit, dβp/dt,H98and d Wmhd/dt are relatively important parameters for MARFE-movement prediction. Applying the RF model on test discharges, the test results show that the successful alarm rate for MARFE movement causing density limit disruption reaches ~ 85% with a minimum alarm time of ~ 40 ms and mean alarm time of ~ 700 ms. At the same time, the false alarm rate for non-disruptive and non-density-limit disruptive discharges can be kept below 5%. These results provide a reference to the prediction of MARFE movement in high density plasmas, which can help the avoidance or mitigation of density limit disruption in future fusion reactors.展开更多
基金The financial support from the National Natural Science Foundation of China(Grant No.51778575)Science and Technology Department of Zhejiang Province(Grant No.2019C03103)。
文摘New tunnelling underneath could influence existing shield tunnels in underground spaces.The evaluation of the influences of tunnelling-induced ground movements on existing tunnels has been a major concern during urban construction.This paper presents a two-stage analytical method that considers the asymmetric ground settlement for investigating the longitudinal tunnel responses to new tunnelling.An improved semi-analytical solution considering the horizontal movement of the new tunnel is established for evaluating the tunnelling-induced asymmetric greenfield settlement.The proposed method is verified with field measurement data from a case study.A parametric analysis is conducted to study the influences of the input parameters on the tunnel responses.Results indicate that the horizontal movement of the new tunnel due to bias loading or asymmetric construction may lead to asymmetric responses of the existing tunnel.With increasing tunnel horizontal movement,the asymmetry of the tunnel responses becomes more obvious.An increase in the pillar depth and decreases in the tunnel horizontal movement and skew angle lower the internal forces induced by new tunnelling.
文摘Two semi-asymmetric flow patterns of typhoons are chosen to qualitatively determine the effect of exchange of horizontal momentum between inflow and outflow layers and the environment on the motion of typhoons. The results show that only the asymmetric flow component (residual after azimuthal mean flow has been removed) could cause a net momentum input into or output from a typhoon and therefore contribute to the changes in speed and direction of the typhoon movement. A typhoon with major inflow and/or outflow channels on its right (left ) side would tend to accelerate and turn left (decelerate and turn right); On the other hand, a typhoon with major inflow and/or outflow channels in the rear (front) semicircle would tend to accelerate and turn right (decelerate and turn left).
基金This work was supported by the National Natural Science Foundation of China(Nos.12174338 and 11874321)。
文摘We introduce a new class of partially coherent asymmetric array beams. When the beam propagates, the spectral density of each lobe and the corresponding degree of coherence have rotating behavior. Especially, not only can array-like lattices revolve arbitrarily, but also they can move freely by controlling transverse plane shifts. Furthermore, we have generated this kind of beam experimentally, and the experimental phenomena are consistent with the numerical simulation results. Such a rotating beam with free movement and revolution may broaden the way for optical applications. More importantly, it inspires further studies in the field of asymmetric coherence gratings and lattices.
基金This work is supported by the National MCF Energy R&D Program of China(Grant Nos.2018YFE0302100 and 2019YFE03010003)the National Natural Science Foundation of China(Grant Nos.12005264,12105322,and 12075285)+3 种基金the National Magnetic Confinement Fusion Science Program of China(Grant No.2022YFE03100003)the Natural Science Foundation of Anhui Province of China(Grant No.2108085QA38)the Chinese Postdoctoral Science Found(Grant No.2021000278)the Presidential Foundation of Hefei institutes of Physical Science(Grant No.YZJJ2021QN12).
文摘Multifaceted asymmetric radiation from the edge(MARFE) movement which can cause density limit disruption is often encountered during high density operation on many tokamaks. Therefore, identifying and predicting MARFE movement is meaningful to mitigate or avoid density limit disruption for the steady-state high-density plasma operation. A machine learning method named random forest(RF) has been used to predict the MARFE movement based on the density ramp-up experiment in the 2022’s first campaign of Experimental Advanced Superconducting Tokamak(EAST). The RF model shows that besides Greenwald fraction which is the ratio of plasma density and Greenwald density limit, dβp/dt,H98and d Wmhd/dt are relatively important parameters for MARFE-movement prediction. Applying the RF model on test discharges, the test results show that the successful alarm rate for MARFE movement causing density limit disruption reaches ~ 85% with a minimum alarm time of ~ 40 ms and mean alarm time of ~ 700 ms. At the same time, the false alarm rate for non-disruptive and non-density-limit disruptive discharges can be kept below 5%. These results provide a reference to the prediction of MARFE movement in high density plasmas, which can help the avoidance or mitigation of density limit disruption in future fusion reactors.
