As a crucial parameter for a few-cycle laser pulse, the carrier envelope phase(CEP) substantially determines the laser waveform. We propose a method to directly describe the CEP of an isolated attosecond pulse(IAP) by...
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As a crucial parameter for a few-cycle laser pulse, the carrier envelope phase(CEP) substantially determines the laser waveform. We propose a method to directly describe the CEP of an isolated attosecond pulse(IAP) by the vortex-shaped momentum pattern, which is generated from the tunneling ionization of a hydrogen atom by a pair of time-delayed, oppositely and circularly polarized IAP-IR pulses. Superior to the angular streaking method that characterizes the CEP in terms of only one streak, our method describes the CEP of an IAP by the features of multiple streaks in the vortex pattern. The proposed method may open the possibility of capturing sub-cycle extreme ultraviolet dynamics.
The spider structure in the photoelectron momentum distributions(PMDs)of ionized electrons from the hydrogen atom is simulated by solving the time-dependent Schrodinger equation(TDSE).We find that the spider structure...
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The spider structure in the photoelectron momentum distributions(PMDs)of ionized electrons from the hydrogen atom is simulated by solving the time-dependent Schrodinger equation(TDSE).We find that the spider structure exhibits sensitive dependence on carrier envelope phase(CEP)of the few-cycle *** elucidate the striking CEP dependence of the spider structure,we select three physical parameters IL,IR,and IR/IL to quantitatively characterize the variations of the spider structure induced by altering the *** is the sum of the left half panel of the transverse cut curves(i.e.,the sum of all the negative momenta along the laser polarization direction),IR is the sum of the right half panel of the transverse cut curves(i.e.,the sum of all the positive momenta along the laser polarization direction),and IR/IL is the ratio between the two *** parameters are shown to have monotonic relation with the CEP value,which is exploited to extract the *** anticipate that our method will be useful for obtaining CEPs encoded in the spider structure of PMDs.
The photoionization by two elliptically polarized, time delayed attosecond pulses is investigated to display a momentum distribution having the helical vortex or ring structuresi The results are obtained by the strong...
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The photoionization by two elliptically polarized, time delayed attosecond pulses is investigated to display a momentum distribution having the helical vortex or ring structuresi The results are obtained by the strong field approximation method and analyzed by the pulse decomposition. The ellipticities and time delay of the two attosecond pulses are found to determine the rotational symmetry and the number of vortex arms. For observing these vortex patterns, the energy bandwidth and temnoral duration of the attosecond pulses are ideal.
This paper discusses estimation of returns to scale (RTS) of Weak BCC inefficient DMUs in DEA. RTS generally has an ambiguous meaning if DMU is not on Weak BCC efficient frontier. Researchers adopt projection method f...
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Considering the important role AMDB takes in the future airtrafficmanagement system, an AMDB data modeling method has been proposed, which is followed by a display technique. In this paper, first,the UML and XML sch...
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Considering the important role AMDB takes in the future airtrafficmanagement system, an AMDB data modeling method has been proposed, which is followed by a display technique. In this paper, first,the UML and XML schema model of AMDB data are constructed on which the aerodrome mapping database is based. Secon, the electronic airport map is drawn by the Auto CAD according to the AIP, NAIP, and airport design chart, which is then be rendered by 3ds MAX and checked by GLClayer. Finally, Qt is used to link the aerodrome mapping database and electronic airport map that aims to visualize the aerodrome mapping *** program presented in this paper can be used as a prototype system of commercial AMDB product.
The carrier envelope phase(CEP) has a direct impact on the physical properties of an isolated attosecond pulse(IAP) and many strong field processes,but it is difficult to measure in *** at obtaining more accurate ...
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The carrier envelope phase(CEP) has a direct impact on the physical properties of an isolated attosecond pulse(IAP) and many strong field processes,but it is difficult to measure in *** at obtaining more accurate and complete characterization of CEP,we numerically investigate the annular photoelectron momentum spectra of the hydrogen atom ionized by overlapped fields of an IAP and an infrared(IR) *** defining an overlapping parameter,the momentum patterns are classified and optimized for unambiguously measuring the rotation angle of a momentum pattern versus the CEP value.A series of simulations verify its robustness.
The establishment of an automated risk early warning mechanism closely linked to the airtraffic flow management system and information management system plays a positive role in ATM risk management. In this study, a ...
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A point-to-point iterative learning control method with the current-cycle feedback is proposed to enable aircraft to achieve an accurate four-dimensional(4D) trajectory tracking. To this end,the 4D trajectory tracking...
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A point-to-point iterative learning control method with the current-cycle feedback is proposed to enable aircraft to achieve an accurate four-dimensional(4D) trajectory tracking. To this end,the 4D trajectory tracking control problem is formulated into a point-to-point tracking control issue with an external disturbance. Then,the optimal point-to-point iterative learning control law is derived based on the successive projection method. Further,the current-cycle feedback error is added to the control law,so that the tracking error is reduced in both time and iteration domains. Finally,a numerical simulation is carried out using the kinematic model of an unmanned aerial vehicle and 4D trajectory data. Obtained results demonstrate that the proposed method can quickly reduce the trajectory tracking error even in the presence of gust interferences. Compared with the commonly used average velocity method and the velocity correction method,the proposed method makes full use of the past and current running data,and can continuously improve the accuracy of 4D trajectory tracking with the repetitive operation of aircraft between city pairs.
Runway incursion has become an important factor affecting the safe operation of the airport. This article focused on the changes of several objective factors that lead to the changes of the runway incursion risk proba...
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Runway incursion has become an important factor affecting the safe operation of the airport. This article focused on the changes of several objective factors that lead to the changes of the runway incursion risk probability. These factors are the initial position of the aircraft, aircrafts' type, and initial velocity of the aircraft and friction coefficient of the runway in different weather conditions. These factors obey different probability distributions, by using the Monte Carlo method to evaluate and eventually gave the effect of different factors on the risk of runway incursion under different weather conditions, by contrasting with the actual operation, the results showed that the assessment is feasible.
Along with the rapid development of airtraffic, the contradiction between conventional airtrafficmanagement(ATM)and the increasingly complex airtraffic situations is more severe,which essentially reduces the opera...
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Along with the rapid development of airtraffic, the contradiction between conventional airtrafficmanagement(ATM)and the increasingly complex airtraffic situations is more severe,which essentially reduces the operational efficiency of air transport systems. Thus,objectively measuring the airtraffic situation complexity becomes a concern in the field of ATM. Most existing studies focus on airtraffic complexity assessment,and rarely on the scientific guidance of complex traffic situations. According to the projected time of aircraft arriving at the target sector boundary,we formulated two control strategies to reduce the airtraffic complexity. The strategy of entry time optimization was applied to the controllable flights in the adjacent upstream sectors. In contrast,the strategy of flying dynamic speed optimization was applied to the flights in the target sector. During the process of solving complexity control models,we introduced a physical programming method. We transformed the multi-objective optimization problem involving complexity and delay to single-objective optimization problems by designing different preference function. Actual data validated the two complexity control strategies can eliminate the high-complexity situations in reality. The control strategy based on the entry time optimization was more efficient than that based on the speed dynamic optimization. A basic framework for studying airtraffic complexity management was preliminarily established. Our findings will help the implementation of a complexity-based ATM.
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