In order to simulate the recovery of groundwater funnels under the condition of reducing groundwater abstraction, hydrogeological conditions of recoverability construction of Shijiazhuang groundwater funnel were analy...In order to simulate the recovery of groundwater funnels under the condition of reducing groundwater abstraction, hydrogeological conditions of recoverability construction of Shijiazhuang groundwater funnel were analyzed, and a numerical simulation method was used based on the change of various parameters. The results show that the groundwater flow model can accurately reflect groundwater hydrogeological characteristics, and can guarantee the reliability of groundwater restoration prediction. The research has set up four schemes for rural water-saving, planting structure adjustment, urban reducing abstraction and integrated method. The effect of four restoration schemes on the restoration of groundwater funnels was compared with water table variations of two observation well. Comparison results show that the level changes of plan Three and Four are different from the other two kinds of exploitation and the drop trend of water table in the funnel area is flat. So we can conclude that Plan Three and Four have significant effect on the groundwater funnel restoration of Shijiazhuang.展开更多
This study examines the Carolina Bays and Nebraska Rainwater Basins,using high-resolution LiDAR elevation models to analyze their unique shapes.The research reveals that well-preserved Bays exhibit precise elliptical ...This study examines the Carolina Bays and Nebraska Rainwater Basins,using high-resolution LiDAR elevation models to analyze their unique shapes.The research reveals that well-preserved Bays exhibit precise elliptical geometry,distinguishing them from various oriented lakes they are often compared to.While the timing of their formation is discussed,the primary goal of this paper is to establish a repeatable method for quantifying the elliptical nature of these dominant geomorphic landforms.By applying the least squares method to points selected along the perimeters of these extraordinary basins,the study confirms their elliptical geometry with an error margin of less than 3%.This rigorous mathematical approach sets a high standard for any hypothesis attempting to explain the origin of these depressions using natural environmental conditions.Notably,the long axes of these elliptical basins converge near the Great Lakes region,and since ellipses can be described as conic sections,this finding supports the plausibility of a cosmic impact origin.The study suggests that these basins may be secondary impact features formed during a past glacial cycle of the Laurentide Ice Sheet.This research establishes a strong mathematical foundation to support future studies on the possible impact origin of the Carolina Bays and Nebraska Rainwater Basins.展开更多
Finding ways to cool buildings by natural,passive techniques is crucial in the context of global warming.For centuries,wind towers(traditi onal win dcatchers)have been used in the Middle East for cooling purposes.In t...Finding ways to cool buildings by natural,passive techniques is crucial in the context of global warming.For centuries,wind towers(traditi onal win dcatchers)have been used in the Middle East for cooling purposes.In this study,the use of funnels at the openings of wind towers for wind ingress and egress is proposed primarily to increase the mass flow captured by the wind tower.The use of funnels in the wind in gress openings in creases the inlet area,improving the capture of wind.In parallel,the use of funnels in the egress openings modifies the wake of the tower,which aims to ease the exit of the flow from inside the building.Several design configurations are presented,where the length and width of the funnels are changed and tested separately by computational fluid dynamics(CFD).Results of over 120 CFD simulations are presented and compared.The volumetric flow entering the wind towers in creases by 10.7% in several cases.These results in dicate that adding funnels to wind towers could positively in fluence their performance.Changing the dimensions of the funnels affects their efficacy and can increase or decrease the airflow entering the tower.展开更多
Man-made superheavy elements(SHE)are produced as energetic recoils in complete-fusion reactions and need to be thermalized in a gas-filled chamber for chemical studies.The ever-shorter half-lives and decreasing produc...Man-made superheavy elements(SHE)are produced as energetic recoils in complete-fusion reactions and need to be thermalized in a gas-filled chamber for chemical studies.The ever-shorter half-lives and decreasing production rates of the elements beyond Fl(atomic number Z=114)-the heaviest element chemically studied today-require the development of novel techniques for quantitative thermalization and fast extraction efficiency.The Universal high-density gas stopping Cell(UniCell),currently under construction,was proposed to achieve this.Within this work,we propose an Ion Transfer by Gas Flow(ITGF)device,which serves as a UniCell ejector to interface with a gas chromatography detector array for chemical studies.Detailed parameter optimizations,using gas dynamics and Monte Carlo ion-trajectory simulations,promise fast(within a few ms)and highly efficient(up to 100%)ion extraction across a wide mass range.These ions can then be transmitted quantitatively through the ITGF into the high-pressure environment needed for further chemical studies.展开更多
In this paper, the multi-agent systems(MASs) typically with heterogeneous unknown nonlinearities and nonidentical unknown control coefficients are studied. Although the model information of MASs is coarse, the leader-...In this paper, the multi-agent systems(MASs) typically with heterogeneous unknown nonlinearities and nonidentical unknown control coefficients are studied. Although the model information of MASs is coarse, the leader-following consensus is still pursued, with a prescribed performance and zero consensus errors. Leveraging a powerful funnel control strategy, a fully distributed and completely relative-state-dependent protocol is designed. Distinctively, the time-varying function characterizing the performance boundary is introduced, not only to construct the funnel gains but also as an indispensable part of the protocol,enhancing the control ability and enabling the consensus errors to converge to zero(rather than a residual set). Remark that when control directions are unknown, coexisting with inherent system nonlinearities, it is essential to incorporate an additional compensation mechanism while imposing a hierarchical structure of communication topology for the control design and analysis. Simulation examples are given to illustrate the effectiveness of the theoretical results.展开更多
Theory predicts that males and females of dioecious species typically engage in an evolutionary sexual conflict over the frequency and choice of mating partner.Female sexual cannibalism,a particularly dramatic illustr...Theory predicts that males and females of dioecious species typically engage in an evolutionary sexual conflict over the frequency and choice of mating partner.Female sexual cannibalism,a particularly dramatic illustration of this conflict,is widespread in certain animal taxa including spiders.Nevertheless,females of some funnel weaving spiders that are generally aggressive to conspecifics enter a cataleptic state after male courtship,ensuring the males can mate without risk of attack.In this study,we demonstrated that the physical posture and duration,metabo-lites,and central neurotransmitters of females of Aterigena aculeata in sexual catalepsy closely resemble females in thanatosis but are distinct from those in anesthesia,indicating that the courted females feign death to eliminate the risk of potentially aggressive responses and thereby allow preferred males to mate.Unlike the taxonomically widespread thanatosis,which generally represents a deceptive visual signal that acts against the interest of the receivers,sexual catalepsy of females in the funnel weaving spiders may deliver a sexual-receptive signal to the courting males and thereby benefit both the signal senders and receivers.Therefore,sexual catalepsy in A.aculeata may not reflect a conflict butrather a confluence of interest betweenthe sexes.展开更多
In this article, an unknown system dynamics estimator-based impedance control method is proposed for the lower limb exoskeleton to stimulate the tracking flexibility with the terminal target position when suffering pa...In this article, an unknown system dynamics estimator-based impedance control method is proposed for the lower limb exoskeleton to stimulate the tracking flexibility with the terminal target position when suffering parametric inaccuracies and unexpected disturbances. To reinforce the robust performance, via constructing the filtering operation-based dynamic relation, i.e., invariant manifold, the unknown system dynamics estimators are employed to maintain the accurate perturbation identification in both the hip and knee subsystem. Besides, a funnel control technique is designed to govern the convergence process within a minor overshoot and a higher steady-state precision. Meanwhile, an interactive complaint result can be obtained with the aid of the impedance control, where the prescribed terminal trajectory can be adjusted into the interaction variable-based target position by the force–position mapping, revealing the dynamic influence between the impedance coefficient (stiffness and damping) and the adjusted position magnitude. A sufficient stability analysis verifies the ultimately uniformly bounded results of all the error signals, and even the angle errors can be regulated within the predefined funnel boundary in the whole convergence. Finally, some simulations are provided to demonstrate the validity and superiority including the enhanced interaction flexibility and robustness.展开更多
Supersonic Tailless Aerial Vehicles(STAVs)will become an essential force in Penetrating Counter Air(PCA),but STAVs do not have the traditional horizontal and vertical tails,making pitch and yaw control difficult.The a...Supersonic Tailless Aerial Vehicles(STAVs)will become an essential force in Penetrating Counter Air(PCA),but STAVs do not have the traditional horizontal and vertical tails,making pitch and yaw control difficult.The attack angle and the sideslip angle need to be limited to ensure that the engine inlet and the aerodynamic rudder at the rear of the vehicle can work properly,which is the so-called security constraints.In addition,the tracking error of the aerodynamic angle needs to be limited to achieve effective attitude control or high-accuracy tracking of trajectories,which is the so-called performance constraints.To this end,an attitude control method that meets the needs of PCA has been devised,based on constraint definition,coupled constraints handling,and control law design.Firstly,mathematical descriptions of the security constraints,performance constraints,and control constraints are given.Secondly,two treatment methods,coupled command filter and coupled funnel control are proposed for the aerodynamic angle coupled constraint problem.Finally,based on Nonlinear Dynamic Inverse(NDI)design,the coupled funnel controller is designed and validated by simulation for two typical mission scenarios,high-altitude penetration and low-altitude surprise defence.The proposed control method not only satisfies the security and performance constraints of STAV attitude control but also is highly robust.展开更多
This study consists to the detection of cavities that could be present over abandoned mines of Albania with the use of SP （self potential） and ERT （electrical resistance tomography）. In general, natural and artifi...This study consists to the detection of cavities that could be present over abandoned mines of Albania with the use of SP （self potential） and ERT （electrical resistance tomography）. In general, natural and artificial cavities represent an important investigation target in geotechnical, environmental and scientific studies. These studies could be engineering, archaeological or speleological. For the detection and localization of such cavities during the last 20 years, several geophysical studies have been used worldwide. In this field study, several geophysical methods could be used such as electrical, electromagnetic, gravimetric and seismic ones. Now days, the ground penetrating radar technique and ERT are widely used. Depending on geological formation conditions every used method is more or less effective. As a result of actual conditions of works on ore mines, the dynamic regime of the surroundings areas has undergone changes creating superficial cavities and funnels and as consequence the geological risk to the community is present. The detection of cavities is a challenge for geophysicists and in these cases the ambiguity on interpretation of geophysical data has to be solved properly. The simultaneous application of different geophysical methods and monitoring in time are necessary in order that the field data interpretation could be significant. Geophysical investigations were carried out as tests over galleries of ore mines of Albania. In this study, we present the SP and ERT results in two sites, in Dhrovjan and Perrenjas region. The effectiveness of the used geophysical methods was present.展开更多
基金supported by Public Welfare Project of Ministry of Water Resources(201501008)Natural Science Foundation of Hebei Province(D2015504019)
文摘In order to simulate the recovery of groundwater funnels under the condition of reducing groundwater abstraction, hydrogeological conditions of recoverability construction of Shijiazhuang groundwater funnel were analyzed, and a numerical simulation method was used based on the change of various parameters. The results show that the groundwater flow model can accurately reflect groundwater hydrogeological characteristics, and can guarantee the reliability of groundwater restoration prediction. The research has set up four schemes for rural water-saving, planting structure adjustment, urban reducing abstraction and integrated method. The effect of four restoration schemes on the restoration of groundwater funnels was compared with water table variations of two observation well. Comparison results show that the level changes of plan Three and Four are different from the other two kinds of exploitation and the drop trend of water table in the funnel area is flat. So we can conclude that Plan Three and Four have significant effect on the groundwater funnel restoration of Shijiazhuang.
文摘This study examines the Carolina Bays and Nebraska Rainwater Basins,using high-resolution LiDAR elevation models to analyze their unique shapes.The research reveals that well-preserved Bays exhibit precise elliptical geometry,distinguishing them from various oriented lakes they are often compared to.While the timing of their formation is discussed,the primary goal of this paper is to establish a repeatable method for quantifying the elliptical nature of these dominant geomorphic landforms.By applying the least squares method to points selected along the perimeters of these extraordinary basins,the study confirms their elliptical geometry with an error margin of less than 3%.This rigorous mathematical approach sets a high standard for any hypothesis attempting to explain the origin of these depressions using natural environmental conditions.Notably,the long axes of these elliptical basins converge near the Great Lakes region,and since ellipses can be described as conic sections,this finding supports the plausibility of a cosmic impact origin.The study suggests that these basins may be secondary impact features formed during a past glacial cycle of the Laurentide Ice Sheet.This research establishes a strong mathematical foundation to support future studies on the possible impact origin of the Carolina Bays and Nebraska Rainwater Basins.
文摘Finding ways to cool buildings by natural,passive techniques is crucial in the context of global warming.For centuries,wind towers(traditi onal win dcatchers)have been used in the Middle East for cooling purposes.In this study,the use of funnels at the openings of wind towers for wind ingress and egress is proposed primarily to increase the mass flow captured by the wind tower.The use of funnels in the wind in gress openings in creases the inlet area,improving the capture of wind.In parallel,the use of funnels in the egress openings modifies the wake of the tower,which aims to ease the exit of the flow from inside the building.Several design configurations are presented,where the length and width of the funnels are changed and tested separately by computational fluid dynamics(CFD).Results of over 120 CFD simulations are presented and compared.The volumetric flow entering the wind towers in creases by 10.7% in several cases.These results in dicate that adding funnels to wind towers could positively in fluence their performance.Changing the dimensions of the funnels affects their efficacy and can increase or decrease the airflow entering the tower.
基金This work was supported by the German BMBF (No.05P21UMFN2)
文摘Man-made superheavy elements(SHE)are produced as energetic recoils in complete-fusion reactions and need to be thermalized in a gas-filled chamber for chemical studies.The ever-shorter half-lives and decreasing production rates of the elements beyond Fl(atomic number Z=114)-the heaviest element chemically studied today-require the development of novel techniques for quantitative thermalization and fast extraction efficiency.The Universal high-density gas stopping Cell(UniCell),currently under construction,was proposed to achieve this.Within this work,we propose an Ion Transfer by Gas Flow(ITGF)device,which serves as a UniCell ejector to interface with a gas chromatography detector array for chemical studies.Detailed parameter optimizations,using gas dynamics and Monte Carlo ion-trajectory simulations,promise fast(within a few ms)and highly efficient(up to 100%)ion extraction across a wide mass range.These ions can then be transmitted quantitatively through the ITGF into the high-pressure environment needed for further chemical studies.
基金supported in part by the National Natural Science Foundation of China(61821004,62033007)Major Fundamental Research Program of Shandong Province(ZR2023ZD37)
文摘In this paper, the multi-agent systems(MASs) typically with heterogeneous unknown nonlinearities and nonidentical unknown control coefficients are studied. Although the model information of MASs is coarse, the leader-following consensus is still pursued, with a prescribed performance and zero consensus errors. Leveraging a powerful funnel control strategy, a fully distributed and completely relative-state-dependent protocol is designed. Distinctively, the time-varying function characterizing the performance boundary is introduced, not only to construct the funnel gains but also as an indispensable part of the protocol,enhancing the control ability and enabling the consensus errors to converge to zero(rather than a residual set). Remark that when control directions are unknown, coexisting with inherent system nonlinearities, it is essential to incorporate an additional compensation mechanism while imposing a hierarchical structure of communication topology for the control design and analysis. Simulation examples are given to illustrate the effectiveness of the theoretical results.
基金supported by Natural Science Foundation of China(no.32160243,no.32000301,no.32070429,no.31772423,no.82173799)the Science and Technology Foundation of Jiangxi Provincial Department of Education(no.GJJ190543).
文摘Theory predicts that males and females of dioecious species typically engage in an evolutionary sexual conflict over the frequency and choice of mating partner.Female sexual cannibalism,a particularly dramatic illustration of this conflict,is widespread in certain animal taxa including spiders.Nevertheless,females of some funnel weaving spiders that are generally aggressive to conspecifics enter a cataleptic state after male courtship,ensuring the males can mate without risk of attack.In this study,we demonstrated that the physical posture and duration,metabo-lites,and central neurotransmitters of females of Aterigena aculeata in sexual catalepsy closely resemble females in thanatosis but are distinct from those in anesthesia,indicating that the courted females feign death to eliminate the risk of potentially aggressive responses and thereby allow preferred males to mate.Unlike the taxonomically widespread thanatosis,which generally represents a deceptive visual signal that acts against the interest of the receivers,sexual catalepsy of females in the funnel weaving spiders may deliver a sexual-receptive signal to the courting males and thereby benefit both the signal senders and receivers.Therefore,sexual catalepsy in A.aculeata may not reflect a conflict butrather a confluence of interest betweenthe sexes.
基金supported in part by the Young Talent Fund of Association for Science and Technology in Shaanxi,China(No.20230126).
文摘In this article, an unknown system dynamics estimator-based impedance control method is proposed for the lower limb exoskeleton to stimulate the tracking flexibility with the terminal target position when suffering parametric inaccuracies and unexpected disturbances. To reinforce the robust performance, via constructing the filtering operation-based dynamic relation, i.e., invariant manifold, the unknown system dynamics estimators are employed to maintain the accurate perturbation identification in both the hip and knee subsystem. Besides, a funnel control technique is designed to govern the convergence process within a minor overshoot and a higher steady-state precision. Meanwhile, an interactive complaint result can be obtained with the aid of the impedance control, where the prescribed terminal trajectory can be adjusted into the interaction variable-based target position by the force–position mapping, revealing the dynamic influence between the impedance coefficient (stiffness and damping) and the adjusted position magnitude. A sufficient stability analysis verifies the ultimately uniformly bounded results of all the error signals, and even the angle errors can be regulated within the predefined funnel boundary in the whole convergence. Finally, some simulations are provided to demonstrate the validity and superiority including the enhanced interaction flexibility and robustness.
基金supported by the National Natural Science Foundation of China(No.62103439)the China Postdoctoral Science Foundation(No.2020M683716)+1 种基金the National Key Laboratory of Unmanned Aerial Vehicle Technology,Chinathe Youth Innovation Team of Shaanxi University,China.
文摘Supersonic Tailless Aerial Vehicles(STAVs)will become an essential force in Penetrating Counter Air(PCA),but STAVs do not have the traditional horizontal and vertical tails,making pitch and yaw control difficult.The attack angle and the sideslip angle need to be limited to ensure that the engine inlet and the aerodynamic rudder at the rear of the vehicle can work properly,which is the so-called security constraints.In addition,the tracking error of the aerodynamic angle needs to be limited to achieve effective attitude control or high-accuracy tracking of trajectories,which is the so-called performance constraints.To this end,an attitude control method that meets the needs of PCA has been devised,based on constraint definition,coupled constraints handling,and control law design.Firstly,mathematical descriptions of the security constraints,performance constraints,and control constraints are given.Secondly,two treatment methods,coupled command filter and coupled funnel control are proposed for the aerodynamic angle coupled constraint problem.Finally,based on Nonlinear Dynamic Inverse(NDI)design,the coupled funnel controller is designed and validated by simulation for two typical mission scenarios,high-altitude penetration and low-altitude surprise defence.The proposed control method not only satisfies the security and performance constraints of STAV attitude control but also is highly robust.
基金Supported by National Natural Science Foundation of China(61403343)Scientific Research Foundation of the Education Department of Zhejiang Province,China(Y201329260)Natural Science Foundation of Zhejiang University of Technology(1301103053408)
文摘This study consists to the detection of cavities that could be present over abandoned mines of Albania with the use of SP （self potential） and ERT （electrical resistance tomography）. In general, natural and artificial cavities represent an important investigation target in geotechnical, environmental and scientific studies. These studies could be engineering, archaeological or speleological. For the detection and localization of such cavities during the last 20 years, several geophysical studies have been used worldwide. In this field study, several geophysical methods could be used such as electrical, electromagnetic, gravimetric and seismic ones. Now days, the ground penetrating radar technique and ERT are widely used. Depending on geological formation conditions every used method is more or less effective. As a result of actual conditions of works on ore mines, the dynamic regime of the surroundings areas has undergone changes creating superficial cavities and funnels and as consequence the geological risk to the community is present. The detection of cavities is a challenge for geophysicists and in these cases the ambiguity on interpretation of geophysical data has to be solved properly. The simultaneous application of different geophysical methods and monitoring in time are necessary in order that the field data interpretation could be significant. Geophysical investigations were carried out as tests over galleries of ore mines of Albania. In this study, we present the SP and ERT results in two sites, in Dhrovjan and Perrenjas region. The effectiveness of the used geophysical methods was present.
