This paper studies a geometric attitude tracking control problem of quadrotor unmanned aerial vehicles (UAVs) with adaptive extended state observers (AESOs). Through coordinate transformation, the error dynamic of AES...
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Coronavirus disease 2019 has brought a great challenge to the supply of daily necessities and medical items for home-quarantined people. Considering the unmanned operation, agility, and use of clean energy of drones, ...
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As a promising cathode material for aqueous zinc-ion batteries,1T-MoS_(2)has been extensively investigated because of its facile two-dimensional ion-diffusion channels and high electrical ***,the limited number of ava...
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As a promising cathode material for aqueous zinc-ion batteries,1T-MoS_(2)has been extensively investigated because of its facile two-dimensional ion-diffusion channels and high electrical ***,the limited number of available Zn storage sites,i.e.,limited capacity,hinders its application because the inserted Zn^(2+),which form strong electrostatic interactions with 1T-MoS_(2),preventing subsequent Zn^(2+)***,the approach of enlarging the interlayer distance to reduce electrostatic interactions has been commonly used to enhance the capacity and reduce Zn^(2+)migration ***,an enlarged interlayer spacing can weaken the van der Waals force between 1T-MoS_(2)monolayers,easily disrupting the structural ***,to address this issue,an effective strategy based on Fe doping is proposed for 1T-MoS_(2)(Fe-1T-MoS_(2)).The theoretical calculations reveal that Fe doping can simultaneously moderate the rate of decrease in the adsorption energy after gradually increasing the number of stored atoms,and enhance the electron delocalization on metal-O ***,the experiment results show that Fe doping can simultaneously activate more Zn storage sites,thus enhancing the capacity,and stabilize the structural stability for improved cycling ***,Fe-1T-MoS_(2)exhibits a larger capacity(189 mAh·g^(-1)at 0.1 A·g^(-1))and superior cycling stability(78%capacity retention after 400 cycles at 2 A·g^(-1))than pure 1T-MoS_(2).This work may open up a new avenue for constructing high-performance MoS_(2)-based cathodes.
The formulae for parameters of a negative electron affinity semiconductor(NEAS)with large mean escape depth of secondary electrons A(NEASLD)are *** methods for obtaining parameters such asλ,B,E_(pom)and the maximumδ...
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The formulae for parameters of a negative electron affinity semiconductor(NEAS)with large mean escape depth of secondary electrons A(NEASLD)are *** methods for obtaining parameters such asλ,B,E_(pom)and the maximumδandδat 100.0 keV≥E_(po)≥1.0 keV of a NEASLD with the deduced formulae are presented(B is the probability that an internal secondary electron escapes into the vacuum upon reaching the emission surface of the emitter,δis the secondary electron yield,E_(po)is the incident energy of primary electrons and E_(pom)is the E_(po)corresponding to the maximumδ).The parameters obtained here are analyzed,and it can be concluded that several parameters of NEASLDs obtained by the methods presented here agree with those obtained by other *** relation between the secondary electron emission and photoemission from a NEAS with large mean escape depth of excited electrons is investigated,and it is concluded that the presented method of obtaining A is more accurate than that of obtaining the corresponding parameter for a NEAS with largeλ_(ph)(λ_(ph)being the mean escape depth of photoelectrons),and that the presented method of calculating B at E_(po)>10.0 keV is more widely applicable for obtaining the corresponding parameters for a NEAS with largeλ_(ph).
Recent years have seen a rising interest in distributed optimization problems because of their widespread applications in power grids, multi-robot control, and regression *** the last few decades, many distributed alg...
Recent years have seen a rising interest in distributed optimization problems because of their widespread applications in power grids, multi-robot control, and regression *** the last few decades, many distributed algorithms have been developed for tackling distributed optimization problems. In these algorithms, agents over the network only have access to their own local functions and exchange information with their neighbors.
Challenged networks (CNs) contain resource-constrained nodes deployed in regions where human intervention is difficult. Opportunistic networks (OppNets) are CNs with no predefined source-to-destination paths. Due to t...
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Traditional knowledge graph entity extraction methods require expert knowledge and a large number of artificial features. Furthermore, deficiencies exist in the accuracy and efficiency of key word extraction based on ...
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The primary objective in aircraft transportation is to minimize turbulent drag, thereby conserving energy and reducing emissions. We propose a sector-shaped counter-flow dielectric barrier discharge plasma actuator, w...
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The primary objective in aircraft transportation is to minimize turbulent drag, thereby conserving energy and reducing emissions. We propose a sector-shaped counter-flow dielectric barrier discharge plasma actuator, which leverages jet synthesis for drag reduction. A drag control experiment was conducted in a low-speed wind tunnel with a controlled flow velocity of 9.6 m/s(Re = 1.445 × 10^(4)). This study investigated the effects of varying pulse frequencies and actuation voltages on the turbulent boundary layer. Using a hot-wire measurement system, we analyzed the pulsating and time-averaged velocity distributions within the boundary layer to evaluate the streamwise turbulent drag reduction. The results show that the local TDR decreases as the pulse frequency increases, reaching a maximum reduction of approximately 20.97% at a pulse frequency of 50 Hz. In addition, as the actuation voltage increases, the friction coefficient decreases, increasing the drag reduction rate. The maximum drag reduction of approximately 33.34% is achieved at an actuation voltage of 10 kV.
The accurate three-dimensional wind field obtained from a Doppler lidar not only helps to comprehend the refined structure of complex airflow but also provides important and valuable solutions for many ***,the underly...
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The accurate three-dimensional wind field obtained from a Doppler lidar not only helps to comprehend the refined structure of complex airflow but also provides important and valuable solutions for many ***,the underlying homogeneity assumption of the typical wind retrieval methods,such as Doppler Beam Swinging(DBS)and Velocity Azimuth Display(VAD)based on a single-lidar,will introduce the measurement uncertainty in complex *** this paper,a new design of a wind measurement campaign involving seven lidars was carried out,which contained the three-lidar-based Virtual Tower(VT)using a time-space synchroniza-tion technique and four single-lidars with different elevation *** study investigates the performance of VT and VAD measurements under various conditions and evaluates the sensitivity of wind measurement uncertainty of VAD to the horizontal spatial-and probe volume-average effects associated with elevation angles of the laser *** inter-comparison results between VT and four VADs show consistent trends with small relative errors under neutral atmospheric conditions with weak wind *** convective or high Turbulence Intensity(TI)conditions,the relative errors between VT and VAD become larger and more ***,it is found that the measurement uncertainty of VAD increases at a given elevation angle with the increasing measurement heights,which is caused by the horizontal homogeneity associated with the conical scanning ***,the simulated and measured results of four VADs indicate that a larger elevation angle corresponds to a lower measurement uncertainty for a given height.
The recently developed magic-intensity trapping technique of neutral atoms efficiently mitigates the detrimental effect of light shifts on atomic qubits and substantially enhances the coherence time. This technique re...
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The recently developed magic-intensity trapping technique of neutral atoms efficiently mitigates the detrimental effect of light shifts on atomic qubits and substantially enhances the coherence time. This technique relies on applying a bias magnetic field precisely parallel to the wave vector of a circularly polarized trapping laser field. However, due to the presence of the vector light shift experienced by the trapped atoms, it is challenging to precisely define a parallel magnetic field, especially at a low bias magnetic field strength, for the magic-intensity trapping of85Rb qubits. In this work, we present a method to calibrate the angle between the bias magnetic field and the trapping laser field with the compensating magnetic fields in the other two directions orthogonal to the bias magnetic field direction. Experimentally, with a constantdepth trap and a fixed bias magnetic field, we measure the respective resonant frequencies of the atomic qubits in a linearly polarized trap and a circularly polarized one via the conventional microwave Rabi spectra with different compensating magnetic fields and obtain the corresponding total magnetic fields via the respective resonant frequencies using the Breit–Rabi formula. With known total magnetic fields, the angle is a function of the other two compensating magnetic ***, the projection value of the angle on either of the directions orthogonal to the bias magnetic field direction can be reduced to 0(4)° by applying specific compensating magnetic fields. The measurement error is mainly attributed to the fluctuation of atomic temperature. Moreover, it also demonstrates that, even for a small angle, the effect is strong enough to cause large decoherence of Rabi oscillation in a magic-intensity trap. Although the compensation method demonstrated here is explored for the magic-intensity trapping technique, it can be applied to a variety of similar precision measurements with trapped neutral atoms.
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