bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantum states from mixtures of equilibrium distributions
Authors: Mintchev Mihail 
Published: April 2022

Abstract
We construct and explore a family of states for quantum systems in contact with two or more heath reservoirs. The reservoirs are described by equilibrium distributions. The interaction of each reservoir with the bulk of the system is encoded in a probability, which characterises the particle exchange among them and depends in general on the particle momentum. The convex combination of the reservoir distributions, weighted with the aforementioned probabilities, defines a new distribution. We establish the existence of an emission–absorption regime in which the new distribution generates a non-equilibrium quantum state. We develop a systematic field theory framework for constructing this state and illustrate its physical properties on a simple model. In this context we derive the particle current full counting statistics, the heat current and the Lorenz number. The entropy production and the relative quantum fluctuations are also determined.
Effect of rear wall inclination on cavity acoustic characteristics at high Mach numbers
Authors: Tang Yin , Luo Lei , Zhang Peihong , Ma Mingsheng 
Published: April 2022

Abstract
Cavity flow has been a research hotspot in aerodynamics. Cavities with low Mach numbers have been extensively investigated, while those with high Mach numbers have been less explored. In this study, a flow control method specific to the acoustic characteristics of an open-type cavity with a high Mach number was studied through the improved delayed detached eddy simulation (IDDES). Next, the rear wall of the cavity was inclined to mitigate the impact strength formed by the airflow on the rear wall surface, thus reaching the goal of reducing the aerodynamic noise in the cavity. The Mach number and length-to-depth ratio of the cavity were calculated as 3.51 and 4.5, respectively. The calculation results manifested that under a high Mach number, the sound pressure level (SPL) at the bottom of the cavity and that at its front wall surface could be obviously reduced by inclining the rear wall, and the reduction amplitude increased with the increase in the inclination angle. At the inclination angle of 60°, the SPL at the bottom could be reduced by 24 dB at maximum.
Belt grinding method considering outer profile and inner wall thickness
Authors: Huang Yun , Wei Ming , Xiao GuiJian , Liu Shuai 
Published: April 2022

Abstract
Increasing thrust-to-weight ratio is the goal pursued by aero-engines. Aero-engine blades are the core components of aero-engines. In order to reduce the weight and improve the thrust-to-weight ratio, the cavity structure is gradually applied to aero-engine blades. The constraints of the outer contour and the inner wall thickness of the cavity structure blade make its trajectory planning difficult, which seriously affects its surface roughness and profile accuracy. In this study, proposes a titanium alloy blade surface machining method based on belt grinding, which is constrained by two dimensions of contour and wall thickness, and the process parameters of titanium alloy material specimens are studied. The obtained parameters are applied to the blade grinding process, the grinding trajectory is planned, and finally parameters of the blade are tested. The processing and testing results verify the effectiveness of the method in this paper.
Analysis of retraction performance of aircraft landing gear in high and low temperature environment
Authors: Wu JingTao , Tian PeiQiang , Cheng Zhu , Deng WenLiang 
Published: April 2022

Abstract
In order to solve the problem that the internal mechanism parameters of the aircraft landing gear are difficult to measure and retractable, the retractable performance of the landing gear under high and low temperature environments is studied. This paper simplifies the retractable mechanism of the landing gear by analyzing the motion mechanism of the aircraft landing gear. The degree of freedom of the retractable mechanism is calculated to verify the accuracy of the simplified rear landing gear retraction mechanism. The simulation model of landing gear retraction mechanism under high and low temperature environment is constructed by Patran. The component deformation and shaft clearance of the retractable mechanism under low temperature (-55°C) and high temperature (74°C) environments are analyzed from the overall and detail dimensions. The quantitative effect of ambient temperature on the deformation of the retractable mechanism of the landing gear is studied. Then Adams is used to establish the kinematics simulation model of the retractable mechanism, and the friction coefficient of the kinematic pair under different ambient temperatures is incorporated. Based on the historical data of the high and low temperature environmental test of the landing gear, the correctness of the model is verified. The influence of the environmental temperature on the driving torque, movement angle and movement time of the retractable mechanism is quantified. The problem that the deformation parameters and motion characteristics of the retractable mechanism of the landing gear are difficult to measure is solved, and the research method of retractable performance of the landing gear mechanism under different ambient temperatures is formed.
Investigation on impact resistance of hierarchical lightweight lattice structure
Authors: Gan Jiakang , Ji E , Li Bing 
Published: April 2022

Abstract
This paper is majorly discussing the impact resistance of hierarchical lightweight lattice structure. Firstly, the unit cells of hierarchical pyramidal lattice structure and traditional single-stage hollow pyramidal lattice structure are designed. At the same time, the concept of relative density is introduced to better demonstrate the impact resistance of hierarchical structure. In this paper, ABAQUS/Explicit software is used to simulate the drop hammer impact simulation of hierarchical structure and hollow structure. The result shows that the impact resistance of hierarchical structure is better than hollow structure. Meanwhile, the samples are prepared by 3D printing, and then quasi-static compression experiment and drop hammer impact experiment are carried out. It is concluded that the bearing and impact resistance performance of the hierarchical structure has obvious improvement than the hollow structure under both quasi-static compression and low-speed drop hammer impact.
Design of Wireless Charging Coils for Aero-engine Telemetry Information Transmission System
Authors: Li Ze , Ouyang Yunfang , Huang Zhou , Zhang Quanxin 
Published: April 2022

Abstract
In order to meet the need of non-contact transmission of aero-engine telemetry information, first of all, a rotor disk and a stator disk suitable for near field communication are designed in this paper, then, the coil design of wireless charging system suitable for high centrifugal force load is carried out. The designed single charging coil can charge two receiving coils at the same time. In order to eliminate the influence of aluminum alloy rotor disk and stator disk on charging performance, concave ferrite slots are installed on rotor disk and stator disk respectively to shield charging coil and receiving coil. The designed charging coils are fabricated and integrated with rotor disk and stator disk respectively. Finally, the designed charging coil and receiving coils are connected into the charging system for testing. The test results show that the charging coil and receiving coils are completely matched with the charging circuit and receiving circuit, and their performance can fully meet the use requirements of aeroengine telemetry information transmission system.
Design of Transmitting Antenna for Aero-engine Telemetry Information Transmission System
Authors: Li Ze , Ouyang Yunfang , Huang Zhou , Zhang Quanxin 
Published: April 2022

Abstract
The demand of aero-engine for non-contact telemetry information transmission is very urgent. Based on the analysis of the characteristics of aero-engine telemetry information transmission system, the rotor disk and stator disk suitable for near-field communication under high centrifugal load are designed in this paper. In order to ensure the stable transmission of telemetry information under large angular displacement between rotor disk and stator disk, two circular arc-shaped dipole antennas are designed to be symmetrically installed on rotor disk for telemetry information transmission. The designed pair of arc-shaped dipole antennas are fabricated and measured. The measurement results show that the two transmitting antennas resonate at 2.19GHz and 2.27GHz respectively, and their impedance bandwidth of -10dB is 35MHz and 34mhz respectively. In their operating frequency band, the isolation between them is greater than 38dB, and their performance fully meets the needs of aeroengine telemetry information transmission.
Performance Analysis of Satellite Navigation Positioning Service under Ionospheric Scintillation
Authors: Zhu Wendan , Zhong Lunlong , Li Yupeng 
Published: April 2022

Abstract
Satellite navigation signals may be affected by ionospheric anomalies such as ionospheric scintillation and ionospheric storms. These anomalies will lead to fluctuations and delays of signals, and thus affecting the performance of satellite navigation service. How to evaluate the performance of satellite navigation service under the influence of ionospheric anomaly is one of the key issues to ensure the safety of satellite navigation aviation service. To solve this problem, the simulation of satellite navigation signals under scintillation and the performance evaluation of positioning service are studied in this paper. Firstly, the scintillation sequence is simulated based on Cornell model. Then, the influence of scintillation on satellite signal parameters is modeled and a generation approach of intermediate frequency satellite navigation signals under scintillation is proposed. Finally, the performance indicators of normal signal and scintillating signal are quantitatively analyzed by solving the navigation parameters and evaluating the performance indicators of the receiver. Simulation results show that the ionospheric scintillation affects the satellite navigation service performance, with reference to the standard specification requirements. Performance of satellite navigation positioning service is severely affected even only one satellite signal is affected by a common moderate scintillation level.
Research on Aerodynamic Modeling of Axisymmetric Aircraft Based on Orthogonal Least Squares
Authors: Wang Jianqi , Wang Dongmei , Zhang Yunyuan 
Published: April 2022

Abstract
Aerodynamic modeling is of great importance for design of axisymmetric aircraft control system. In this paper, an axisymmetric aircraft aerodynamic model selection method is constructed, which involves an orthogonal least squares algorithm using in model structure selection, and the method based on it is selected for determining the aerodynamic coefficients. Then the method is tested in three axis coefficient modeling of a certain axisymmetric aircraft, and the modeling result is consistent with the wind tunnel test data.
Research on visualization and diagnosis method of civil aircraft WQAR data
Authors: Ren Chenhui , Ma Linlong , Yang Xu , Wan Junlong 
Published: April 2022

Abstract
WQAR data has the characteristics of large scale, high dimension and many random interference factors, which makes it extremely difficult to use WQAR operational data for flight quality monitoring, expert unknown anomaly detection and PHM. This paper proposes a civil aircraft WQAR data visualization display scheme and the overall framework of fault diagnosis adopts a two-stage cycle to research and recycle and improve the data preprocessing requirements, visualization and diagnostic process methods, etc., and use the civil aircraft operation data to verify the proposed theoretical model and diagnose the failure status. Results shown that the theoretical framework and method can accurately predict the health status of aircraft engines, and can effectively solve the problems of high dimension and many interference factors of WQAR data.
Design of Aeronautical Digital Video and Communication Bus Processing System
Authors: Zhu Pengcheng , Li Haojie 
Published: April 2022

Abstract
With the development of avionics systems, Avionics Digital Video Bus (ARINC 818) and Digital Information Transmission System (Arinc429) have become a new generation of aviation video transmission and communication bus standard respectively. Aiming at the characteristics of ARINC 818 and Arinc429, an aeronautical digital video and communication bus processing system is designed. First, the ARINC 818 aviation video transmission bus and the Arinc429 communication bus standard are introduced. Then, the design principles of the aeronautical digital video and communication bus processing system are described according to this standard, and the design scheme of each system component is introduced in detail. Finally, build a hardware test platform for testing and verification. The system development follows an integrated and modular design, with the Application Processing Unit (APU) main processor and Field Programmable Gate Array (FPGA) as the core, which realizes the superposition of 1-channel input ARINC 818 video with internally generated characters, and then outputs 1-channel ARINC 818 to the function displayed on the display. At the same time, it supports 7-channel Electronic Industries Association-422 (EIA-422) and 4-channel Arinc429 bus communication. In addition, the system supports the processing of 22 input discrete quantities and 7 input analog quantities. The design has been successfully used in a certain type of aircraft display control management system.
Aviation application of dual-weighted neural network based on biomimetic pattern recognition
Authors: Zhao Xue 
Published: April 2022

Abstract
In order to solve the difficult problem of fault diagnosis in aviation equipment, this paper uses a biomimetic pattern recognition method. Compared to traditional pattern recognition, biomimetic pattern recognition is able to construct closed, complex geometries to cover all kinds of samples. Biomimetic pattern recognition is a “cognitive” approach, where the process between two similar things is considered asymptotic. It mathematically means that all similar samples in the feature space are continuously indistinguishable. The paper establishes a dual-weighted neural network model of an aircraft auxiliary power unit. Comparing the diagnostic process and results with traditional manual neural networks. The results show that biomimetic pattern recognition is a feasible and efficient diagnostic method for the fault diagnosis of aviation equipment. It provides a new way of thinking and method for the practical application of aviation equipment fault diagnosis.
Laminar Flow Control using an Optimised Forward-Facing Step - An Experimental Approach
Authors: Gao Chunyi , Yadav Devinder Kumar , Bhatia Dinesh 
Published: April 2022

Abstract
With the rapid increase of global aviation emissions, biomimetics has proven to be a promising avenue to achieve greener aviation. This paper aims to explore the influence of the shark skin denticle inspired two-dimensional Forward-Facing Steps (FFS) on boundary-layer transition delay and drag reduction. Previous computation simulations indicate that the presence of FFS inside the laminar boundary layer can damp disturbances and lead to transition delay and drag reduction. The purpose of this paper is to find the optimal configuration of the FFS through experimental tests and correlate results to previously concluded simulations. Conditional results indicate that the presence of the FFS within the laminar boundary layer is effective in transition delay and drag reduction.
Probabilistic Collision-free Pattern Control For Large-Scale Spacecraft Swarms Around Circular Orbits
Authors: Chen Lin , Wang Chi , Yang Chihang , Deng Hong , Zhang Hao 
Published: April 2022

Abstract
This work considers controlling large-scale spacecraft swarms to achieve complex spatial configuration. A novel distributed guidance algorithm is proposed based on Inhomogeneous Markov Chains, Probabilistic Density Guidance and Voronoi partition (IMC-PDG-Voronoi) algorithms. The physical space is partitioned into multiple bins and the density distribution of the swarm is controlled via a probabilistic approach. Then the modified Voronoi partition method is used to generate a collision-free trajectory for each agent. To apply the probabilistic control algorithm to circular Earth orbit, the periodic solution of the Clohessy-Wiltshire (C-W) equation in configuration space is transformed into a parameter space. Then a convex optimization open-loop controller with minimum fuel consumption in LVLH coordinates is designed to control the swarm to expected positions. Numerical simulations show that the algorithm can effectively guide and control large-scale spacecraft swarms to form complex configurations on circular orbits, with high precision and little cost.
Global environmental controls on wildfire burnt area, size, and intensity
Authors: Haas Olivia , Prentice Iain Colin , Harrison Sandy P 
Published: April 2022

AbstractFire is an important influence on the global patterns of vegetation structure and composition. Wildfire is included as a distinct process in many dynamic global vegetation models but limited current understanding of fire regimes restricts these models’ ability to reproduce more than the broadest geographic patterns. Here we present a statistical analysis of the global controls of remotely sensed burnt area (BA), fire size (FS), and a derived metric related to fire intensity (FI). Separate generalized linear models were fitted to observed monthly fractional BA from the Global Fire Emissions Database (GFEDv4), median FS from the Global Fire Atlas, and median fire radiative power from the MCD14ML dataset normalized by the square root of median FS. The three models were initially constructed from a common set of 16 predictors; only the strongest predictors for each model were retained in the final models. It is shown that BA is primarily driven by fuel availability and dryness; FS by conditions promoting fire spread; and FI by fractional tree cover and road density. Both BA and FS are constrained by landscape fragmentation, whereas FI is constrained by fuel moisture. Ignition sources (lightning and human population) were positively related to BA (after accounting for road density), but negatively to FI. These findings imply that the different controls on BA, FS and FI need to be considered in process-based models. They highlight the need to include measures of landscape fragmentation as well as fuel load and dryness, and to pay close attention to the controls of fire spread.
A Swanson-like Hamiltonian and the inverted harmonic oscillator
Authors: Bagarello Fabio 
Published: April 2022

Abstract
We deduce the eigenvalues and the eigenvectors of a parameter-dependent Hamiltonian H

θ
which is closely related to the Swanson Hamiltonian, and we construct bi-coherent states for it. After that, we show how and in which sense the eigensystem of the Hamiltonian H of the inverted quantum harmonic oscillator can be deduced from that of H

θ
. We show that there is no need to introduce a different scalar product using some ad hoc metric operator, as suggested by other authors. Indeed we prove that a distributional approach is sufficient to deal with the Hamiltonian H of the inverted oscillator.
Dynamic control of Fano resonances in a coupled dual microring resonator system
Authors: Lu Chunyu , Alaydrus Musa , Nikbakht Hamed , Akca B Imran 
Published: April 2022

Abstract
We propose a coupled optical microresonator system that can be used as a new and flexible platform to form asymmetric Fano-like resonances and dynamically control their line shapes and frequencies. The coupled microresonator system was formed using two microring resonators coupled via a 3 × 3 coupler. The upper microring resonator is the add-drop type, whereas the lower one is the all-pass type, providing the (semi-) continuum and discrete states, respectively. We simulated the behavior of the coupled system using the finite-difference time-domain method and observed asymmetric Fano line shapes in the transmission spectra. We demonstrated that the line shapes and frequencies of Fano resonances can be controlled by dynamically varying the refractive index of a small region of the upper or lower microring resonators. We also introduced a small gap in the upper microring resonator to control the continuum state more efficiently. The proposed coupled microresonator concept is simple, easy to fabricate and sufficiently flexible to be engineered for different applications.
Recent advances in wearable exoskeletons for human strength augmentation
Authors: Lee Jinwoo , Kwon Kangkyu , Yeo Woon-Hong 
Published: April 2022

AbstractThe decline in muscular strength and control due to age or stroke-related side-effect has afflicted many individuals with neuromotor disorders because it affects essential motor functions to perform everyday activities and restrains their functional independence. In this regard, a myriad of wearable exoskeletons and functional components have been developed to deliver mechanical force for assisting the movements of different human body parts. However, many of the reported wearable exoskeletons suffer from several critical drawbacks that limit functional usage and practicality despite the significant technological advance of general wearable exoskeletons. Here, this review offers a comprehensive summary of the recent advances of wearable exoskeletons and their constituting functional components. In addition, we discuss the essential challenges that need to be tackled to enhance the functional practicality of the next-generation wearable exoskeletons in assisting the strength and control of individuals with neuromotor disorders.