bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical properties of a generalized 2 × n resistor network
Authors: Zhou Shi , Wang Zhi-Xuan , Zhao Yong-Qi , Tan Zhi-Zhong
Published: May 2023

Any changes in resistor conditions will increase the difficulty of resistor network research. This paper considers a new model of a generalized 2 × n resistor network with an arbitrary intermediate axis that was previously unsolved. We investigate the potential function and equivalent resistance of the 2 × n resistor network using the RT-I theory. The RT-I method involves four main steps: (1) establishing difference equations on branch currents, (2) applying a matrix transform to study the general solution of the differential equation, (3) obtaining a current analysis of each branch according to the boundary constraints, and (4) deriving the potential function of any node of the 2 × n resistor network by matrix transformation, and the equivalent resistance formula between any nodes. The article concludes with a discussion of a series of special results, comparing and verifying the correctness of the conclusions. The work establishes a theoretical basis for related scientific research and application.
Saturable absorber based on tapered graded-index multimode fiber with ZnO coating for bound solitons generation
Authors: Jin N M , WANG D N , Cai S L , Peng Y Q , Chen H F
Published: May 2023

A passively mode-locked erbium-doped fiber laser with a saturable absorber (SA) based on a tapered graded-index multimode fiber with zinc oxide coating is proposed and demonstrated in this paper. The device is also a platform supporting various types of solitons outputs. The conventional solitons with center wavelength of 1558.86 nm, pulse width of 537 fs, and signal-to-noise ratio of 61.27 dB are generated at the repetition frequency of 18.37 MHz. By adjusting the polarization controller and increasing pump power, tightly and loosely bound solitons and two-fold solitons can be generated. The pulse trains of tightly bound solitons exhibit the separation of 1.91 ps, the pulse width of ∼707 fs, and centered at 1560 nm, whereas the pulse separation of loose bound solitons is 18.06 ps. Such a SA is easy in fabrication and highly stable in operation and can enrich the exploration of multi-soliton complexes.
A simple semiempirical model for the static polarizability of ions
Authors: Sharipov Alexander S , Loukhovitski Boris I
Published: May 2023

A concise analytical model for the static dipole polarizability of ionized atoms and molecules is created for the first time. As input, it requires, alongside the polarizability of neutral counterpart of a given ion, only the charge and elemental composition. This physically motivated semiempirical model is based on a number of established regularities in polarizability of charged monatomic and polyatomic compounds. In order to adjust it, the results of quantum chemistry calculations and gas-phase measurements available for a broad range of ionized multielectron species are employed. To counteract the appreciable bias in the literature data toward polarizability of monoatomic ions, for some molecular ions of general concern the results of the authors’ own density functional theory calculations are additionally invoked. A total of 541 data points are used to optimize the model. It is demonstrated that the model we suggested has reasonable (given the substantial uncertainties of the reference data) accuracy in predicting the static isotropic polarizability of arbitrarily charged ions of any size and atomic composition. The resulting polarizability estimates are found to achieve a coefficient of determination of 0.93 for the assembled data set. The created analytic tool is universally applicable and might be advantageous for some applications where there is an urgent need for rapid low-cost evaluation of the static gas-phase polarizability of ionized atoms and molecules. This is especially relevant to constructing the complex models of nonequilibrium chemical kinetics aimed at precisely describing the observable refractive index (dielectric permittivity) of plasma flows. The data sets that support the findings of this study are openly available in Science Data Bank at https://doi.org/10.57760/sciencedb.07526.
Activated dissociation of H2 on the Cu(001) surface: The role of quantum tunneling
Authors: Yu 于 Xiaofan 小凡 , Tong 童 Yangwu 洋武 , Yang 杨 Yong 勇
Published: May 2023

The activation and dissociation of hydrogen molecules (H2) on the Cu(001) surface are studied theoretically. Using first-principles calculations, the activation barrier for the dissociation of H2 on Cu(001) is determined to be ∼ 0.59 eV in height. It is found that the electron transfer from the copper substrate to H2 plays a key role in the activation and breaking of the H–H bond, and the formation of the Cu–H bonds. Two stationary states are identified at around the critical height of bond breaking, corresponding to the molecular and the dissociative states, respectively. Using the transfer matrix method, we also investigate the role of quantum tunneling in the dissociation process along the minimum energy pathway (MEP), which is found to be significant at or below room temperature. At a given temperature, the tunneling contributions due to the translational and the vibrational motions of H2 are quantified for the dissociation process. Within a wide range of temperature, the effects of quantum tunneling on the effective barriers of dissociation and the rate constants are observed. The deduced energetic parameters associated with the thermal equilibrium and non-equilibrium (molecular beam) conditions are comparable to experimental data. In the low-temperature region, the crossover from classical to quantum regime is identified.
Dynamic light storage based on controllable electromagnetically induced transparency effect
Authors: Zeng Liu-Ying , Wu Jun-Fang , Li Chao
Published: May 2023

We analytically and numerically investigate a signal light storing mechanism based on the controllable electromagnetically induced transparency (EIT) effect. We demonstrate that the isolation between the waveguide and the cavities cannot be achieved instantly as soon as the two cavities are tuned into resonance, no matter the index tuning rate is ultrafast or slow. We also investigate the temporal evolution features of the intracavity energy when the pulse during time is prolonged. We find many periodical oscillations of the trapped energy in both cavities, and they are entirely complementary. Our analysis shows that the adiabatic wavelength conversion in both cavities and a phase difference π between them play critical roles in this phenomenon.
Ultra-short laser structuring of 3D-microfabricated non-resorbable polystyrene polymer to anchor cellular adhesion
Authors: Angelova L , Filipov E , Aceti D M , Zhelyazkova Al , Buchvarov I , Daskalova A
Published: May 2023

Tissue engineering is emerging as a preferred choice for regeneration of irreversible bone tissue defects. It’s main “weapons” are the artificially created biocompatible three-dimensional cellular matrices that mimic the extracellular matrix’s structure and provide a mechanically stable inert substrate for the natural growth of cells. These porous scaffolds provide sufficient inner surface for cell adhesion, migration, proliferation and protrusion “inside” the temporal implant, facilitating in that way the natural bone ingrowth and vascularization. This leads, eventually, to overgrowing the outer and inner surface of the biomimetic implant with recipient self-formed bone tissue, thus avoiding a possible immune response.

In the current study 3D Polystyrene (PS) non-resorbable synthetic cellular bone scaffolds, produced by 3D microfabrication technology, were additionally structured by applying femtosecond (fs) laser radiation with variable parameters thus achieving optimal laser processing conditions, for creation of 3D matrix with enhanced fiber surface properties. The main aim is the establishment of surface structured microporous biomimetic scaffolds, providing improved cell adhesion, infiltration and formation of extracellular matrix. The 3D laser functionalized PS samples were investigated by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray analysis (EDX), confocal (optical profilometer) and roughness analyses for evaluation of their morphological and chemical properties before and after fs structuring was performed. Water contact angle (WCA) evaluation was also conducted. Future experimental work will include in vitro cellular studies for determining the optimal structuring laser parameters, providing osteoconductive and osteoinductive qualities of the 3D fs-microstructured PS scaffolds.
DFT simulation of the Raman spectrum of single layer graphene
Authors: Kolev S K , Trifonov D V , Aleksandrov H A , Atanasov V A , Popov V N , Milenov T I
Published: May 2023

Raman spectroscopy is one of the most suitable tools for studying few-layer graphene. The position of the G band and the defect-induced D and D' bands in the spectra of perfect single-layer graphene with sp2-hybridized carbon atoms and hydrogenated graphene with 27.7% sp3-hybridized carbon atoms are simulated using the Density Functional Theory (DFT) method with Perdew-Burke-Ernzerhof (PBE) functional. In the case of perfect graphene, the Raman G band is predicted at 1612 cm-1. In the case of the hydrogenated structure, a new feature appears. Namely, along with the G band, now shifted to 1591 cm-1, an additional feature, located at 1703 cm-1, is clearly seen. The latter is due to oscillations, involving six atomic benzene rings, containing two sp3-hybridized C atoms. According to our results, the presence of defects, related to sp3 hybridized carbon, gives rise to the appearance of the defect D' band in the Raman spectrum of defective graphene. This study shows that it is possible to simulate Raman spectra using the DFT method, with the results qualitatively matching the experimental data.
Diffraction-limited high-power master oscillator – power amplifier system oscillating in visible spectral range on copper atomic transitions for precise material micromachining
Authors: Kostadinov I K , Temelkov K A , Popova L T , Slaveeva S I , Yankov G P
Published: May 2023

A new considerably improved master oscillator–power amplifier copper bromide vapor system delivering diffraction-limited high-power laser radiation at the atomic copper 510.6- and 578.2-nm lines is developed and investigated. The highest beam quality achieved so far with laser systems oscillating on the metal self-terminating transitions is confirmed by two independent methods. Precise micromachining is realized on silica, ceramics, silicon, and stainless steel. Though the aspect ratio of the crater drilled in optical grade fused quartz through the wave-guide-assisted method is higher than the one obtained so to date, a new method is also developed to make the aspect ratio almost limitless.
Modification of microcrystaline graphites by pulsed laser ablation in a flow mode suspension
Authors: Dimov D A , Stankova N , Karaivanova D , Karashanova D , Georgieva B , Avramova I , Petrov M , Valcheva E , Avdeev G , Ivanov K , Milenov T
Published: May 2023

Here we present experimental results on the modification of graphite suspensions in bi-distilled water by laser irradiation in a flow mode system. The fundamental wavelength of a Nd:YAG laser system (λ= 1064 nm) was used in our experiments. The morphology of the sedimented and dried powders was studied by transmission electron microscopy (TEM). Their phase composition and structure were explored by Raman spectroscopy, GIXRD, as well as TEM.
SERS active substrates for neonicotinoids studies
Authors: Atanasov P A , Nedyalkov N N , Dikovska A O , Fukata N , Jevasuwan W
Published: May 2023

Different basic substrates, – Si wafers, (001) SiO2, printer paper, Al2O3, micro-processed (001) SiO2 or diamond abrasive films, have been used to create active Ag and Au nanostructures. In this lecture, we report the use of pulsed-laser deposition and thermal deposition both followed by pulsed-laser annealing; the results are compared. Advanced substrates of Au and Ag on Si were produced in view of surface-enhanced Raman spectroscopy (SERS) detection of the imidacloprid (Nuprid 200 SP) neonicotinoid insecticide in amounts much smaller than those ordinarily applied in agricultural medicine. The SERS peaks intensity rose by at least one order of magnitude after the pulsed-laser annealing of the metal films and nanoparticles arrays formation. The enhancement factor (EF) was estimated to be >5×104, the limit of detection (LOD) reached being < 0.5 nM. The properties of the advanced substrates were compared and discussed. The importance of SERS as a relatively inexpensive and simple method is emphasized in regulating, monitoring and controlling the level of such chemicals as environmental pollutants, thus precluding harming the human and, especially, honey bees’ health.
Laser-assisted synthesis of metallic composite nanostructures in aqueous solutions
Authors: Stankova N E , Nikolov A , Karashanova D , Nedyalkov N , Dikovska A
Published: May 2023

The method of pulsed laser ablation in liquids (PLAL) is applied for synthesis of composite nanostructures on the basis of TiOx and ZnO combined with noble metals like Au, Pt and Pd. The metallic plate immersed in water is laser ablated by nanosecond Nd:YAG pulsed laser irradiation. Its fundamental wavelength and the fourth harmonic are used, respectively, to produce and to modify the morphology and structure of the nano-objects. The synthesis procedure consists of two consecutive steps: laser ablation of the selected metal targets followed by unfocused laser beam irradiation of the initial colloids of nanostructures. The phase composition, structural and the shape and size morphological features were assessed by analytical method – transmission electron microscopy (TEM) in its main modes – Bright Field TEM (BF TEM), High Resolution TEM (HRTEM) and Selected Area Electron Diffraction (SAED). Formation of bimetallic polycrystalline alloys and Pt/Ti(TixOy) and Pd/Ti(TixOy) core-shell nanoparticles was founded.
Fluorescent study of wastewater and the effect of low quantity of disinfectant
Authors: Tsonkov L , Georgieva D , Vladimirova – Mihaleva L , Slavova V , Mihalev M
Published: May 2023

In the last few years due to the COVID-19 pandemic the pollution with large quantities of medicaments, disinfectants and essential oils raised the importance of their detection in wastewater. The research of new techniques for diagnostics continues. Some promising methods for finding contaminators of different origin are based on the optic and spectral characteristics of the examined water. Those could be used in determining the exact pollutant. The spectroscopic examination could also be conducted real-time under in vivo conditions. In this research, we use fluorescence spectroscopy to investigate the purity of water probes from the discharge of the Iskar River near the treatment plant in Samokov (Bulgaria) and the influence of small amounts of disinfectants (ethanol). The results show that fluorescence can be used to determine the purity of water probes and little amounts of alcohol in wastewater.
Applications of single laser pulse from Nd:doped lasers for cleaning of small diameter carious lesions. Modelling and analytical study
Authors: Uzunov T , Deneva M , Uzunova P , Nenchev M
Published: May 2023

We report on an analytical study with physical modelling, some additional experimental studies and computer programming of the cleaning of initial carious lesions (1 - 3 mm in diameter) with a single laser pulse from Nd:doped (Nd:YAG and Nd:Glass) lasers (wavelength 1.06 μm). The analysis is based on experimental data from our preliminary study and aims to develop a method to predetermine the necessary laser pulse parameters for reasonable cleaning. To obtain such laser pulse parameters, we considered the conversion of light energy into heat, the propagation of incident light and the resulting heating of the dental tissue, the induced ablation processes associated with lesion cleaning, and the formation of the necessary hole in combination with acceptable heating of the pulp chamber and prevention of enamel crack formation. Cleaning is naturally associated with the bactericidal effect. The study, except for the estimation, confirms that the use of single light pulses of the considered lasers with energies from 1.3 to 4.5 J, densities from 40 to 120 J/cm2, pulse duration from a few hundred microseconds to ~2 ms (i.e., in the simplest, natural, free mode of operation of the noted lasers) can be considered as a promising method to start caries treatment.
Rotation of the polarization ellipse for broad-band and narrow-band optical pulses. Analytical solutions
Authors: Kasapeteva Z , Dakova A , Slavchev V , Dakova D , Kovachev L
Published: May 2023

In present days the evolution of broad-band laser pulses, propagating in various types of waveguides, has been of a great interest among the scientists. Currently, it is easy for phase-modulated femtosecond pulses the condition Δω≈ω0
to be obtained. It is known that nowadays it is possible also to reach the attosecond region where the spectral bandwidth of the pulse happens to be of order of the carrier frequency also. Light pulses who fulfil this initial condition are called broad-band. On the other hand, the non-fulfilling pulses are the narrow-band ones.

In the present paper it is investigated the parametric interaction of two components of one optical pulse by using the Generalized System of Nonlinear Amplitude Equations (GSNAE). GSNAE was analytically solved. A difference in the period of oscillations of the energy exchange between the two components is found.
Influence of Transition Metal-Nitride Thin Films on the Electrical Contact Resistance of Copper Substrates
Authors: Kotlarski G , Ormanova M , Valkov S , Andreeva A , Bezdushnyi R , Mateev V , Marinova I , Petrov P
Published: May 2023

In the present study, TiN and VN surface coatings are applied on copper substrates, and their influence on the electrical contact resistance (ECR) of the primary material is studied. The coatings are deposited using reactive magnetron sputtering in an Ar/N2 environment. The formed TiN and VN thin films have a thickness of 600 nm and 350 nm, respectively. The preferred crystallographic orientation of both coatings is in the (311) plane. This corresponds to a high crystallite size, high plastic deformations, and high mobility of any structural defects. The I(200)/I(111) ratios of the coatings indicate that the deposited TiN coating is perfectly stoichiometric, and the VN one is hyper stoichiometric, resulting in its’ slightly higher electrical contact resistance. The electrical contact resistance of both coatings is significantly lower compared to that of the pure copper substrate due to their excellent corrosion resistance.
Hardness comparison between Co – Cr metal alloy specimens made by different methods
Authors: Galeva H , Uzunov T , Stoev Y , Sofronov Y , Todorov G
Published: May 2023

The aim of this study is to compare the hardness of Co–Cr metal alloy specimens made by different methods and how it is influenced by multiple temperature changes. Fifty-four samples are made by three different methods and are accordingly divided in three groups – group M (Milling), group LP (Laser Printing) and group LW (Lost Wax), with 18 samples each. All of them contain three subgroups with six samples – metal samples with no thermal cycles (subgroup 1), metal samples with one thermal cycle (subgroup 2) and metal samples with two thermal cycles (subgroup 3). Their Vickers hardness is evaluated by a weight of 1 kg applied for 20 s. The results are presented in tables. The average hardness is the highest for group LP – 509, followed by group M – 440, and for group LW it is 401. For the subgroups, the best results are exhibited by the samples of subgroup 2 – 430, followed by subgroup 3 – 457, and subgroup 1 – 450.
Multi-objective optimization configuration of wind-solar coupling hydrogen production system
Authors: Xu Mingjian , Wang Haocheng , Su Qian , Shi Jiaqi , Li Jiajun
Published: May 2023

The existing research on the wind solar coupling hydrogen generation system lacks the evaluation of factors such as the reliability of power supply to the microgrid system. This paper establishes a multi-objective optimization configuration model of wind-solar coupling hydrogen generation system under grid-connected operation mode for hydrogen generation. From the perspective of system economy and stability analysis, the model optimizes the capacity of the wind power unit, photovoltaic unit, energy storage unit, and hydrogen generation unit to improve the economy and reliability of microgrid operation, to minimize load loss rate, system annual cost, renewable energy power generation loss rate, and energy surplus rate.
Application Research of Power Battery System Fault Identification Method Based on Multi-Classifier Fusion
Authors: Jiang Lu
Published: May 2023

In this paper, a module fault identification method for a power battery system based on multi-classifier fusion is designed. Taking the inverter single tube open circuit fault of the power battery system as an example, the deep learning method of deep neural network and convolutional neural network is used to build the primary diagnosis layer. The fusion method of evidential reasoning rules is used to fuse the primary diagnosis results. The fault data are obtained through simulation of the simulation model, which verifies that the scheme avoids the disadvantage of unstable diagnosis results of a single classifier, and obtains more stable diagnostic results with higher diagnostic accuracy.
Stability Enhancement of Modular Multilevel Converter - High Voltage Direct Current Systems Interacted with Weak Power Grid Based on Current-mode Virtual Inertia Control
Authors: Lin Jinjiao , Kong Xiangping , Gao Lei , Zheng Mingzhong , Li Peng , Wang Chenqing
Published: May 2023

The extensive growth of large-scale flexible high voltage direct current (HVDC) transmission systems compromises the strength of the alternating current (AC) power grid. Sub-synchronous oscillations will likely arise within such flexible HVDC systems, which would significantly threaten the grand electric power system’s stable operation. A current-type enhanced virtual inertia control is proposed to suppress the sub-synchronous oscillations induced by a weak AC power grid in the modular multilevel converter (MMC)-based HVDC systems. Firstly, a small signal model of MMC is established to study the stability of the system under a weak power grid. Focally, a current-mode virtual inertial control is proposed to suppress the AC power grid’s sub-synchronous oscillation by directly taking the grid current as the virtual inertia control variable. Finally, the proposed virtual inertia control approach is verified using both offline and real-time simulation based on the Chongqing-Hubei flexible MMC-HVDC transmission system. The simulation results demonstrate that the proposed current-mode virtual inertia control strategy can efficiently suppress sub-synchronous oscillations in the MMC-HVDC system interacting with a weak AC grid, which enhances the stability and reliability of the power system.
Detection and Location of Series DC Arc Fault in Photovoltaic System Based on VMD
Authors: Guo Feng , Yao Shenghong , Zhang Neng , He Yuchao
Published: May 2023

A large number of connecting wires and electrical contact points exist in large photovoltaic power generation systems, which can easily cause the occurrence of an arc fault. Failure to detect and isolate faults in time will result in serious fire hazards. In the document, a new approach to fault arc monitoring and positioning built on variational mode decomposition is presented for a variety of series DC arc faults in photovoltaic systems. The time and frequency-domain properties of signals collected under different working conditions are obtained by the use of variational mode decomposition (VMD), and the detection of faults by matching changes in features under the same sub-mode. Finally, a 400KW photovoltaic system model is built by Matlab/Simulink for simulation verification. The outcome indicated that the technique is capable of accurately detecting and locating series DC arc faults.
Research on Control Strategy of Hybrid Reactive Power Compensation System for Wind Farms
Authors: Wang Qian , Wu Shouyuan
Published: May 2023

With the increasing scale of wind farms and the increasing proportion of wind power generation in the energy system, the grid has higher and higher requirements for the voltage stability of wind farms. In this paper, we propose a hybrid reactive power compensation system and its control strategy for weakly connected asynchronous wind farms, which can effectively control the compensation cost while improving the continuity of reactive power regulation. It also verifies the correctness and feasibility of the proposed hybrid reactive power compensation system and its control strategy through simulation.
AC and DC voltage control method for off-grid inverter based on matching control
Authors: Kang Pengpeng , Guo Xiaolong , Song Pengfei , Yang Guixing , Zhao Zhiyi
Published: May 2023

Matching control is a new kind of grid-forming control method, compared with droop control and VSM control, it is more stable in a hybrid grid where the synchronous machines and inverters coexist. We introduce the matching control’s concept and developing process briefly, and use the matching control as the inner loop. We propose the VF outer loops to control DC and AC voltage to realize voltage and frequency control in disturbances. Finally, we use Simulink to validate the effectiveness of designed outer loops.
Research on Coordinated Control Strategy Based on DC Bus Voltage of DC Microgrid
Authors: Zhang Meng , Li Jin , Huang Kun
Published: May 2023

DC microgrid is the trend of the future distribution grid. Coordinated control of different types of distributed generation units, energy storage systems, converters, and loads in the DC microgrid to ensure efficient system operation is the focus of current research on the DC microgrid. In this paper, by taking the renovation project of Liangzi Island Electric Hotel in Hubei Province as a case, a coordinated control strategy based on DC bus voltage is proposed for internal power balance and stable system operation of the DC microgrid. Firstly, the operation mode is divided according to the different working conditions of the DC microgrid. The hierarchical droop control is used to associate each operating mode with different DC bus voltage intervals. Then a multi-source coordinated strategy is proposed, and each unit switches its operation mode according to DC bus voltage to maintain bus voltage and ensure power balance. Finally, the simulation is built and run in MATLAB/Simulink to verify the feasibility of the proposed coordinated control strategy.
New High-strength Aluminum Alloy Used for Distribution Circuit Fittings
Authors: Liu Weike , Cao Xianhui , Xie Yi , Hu Yujing , Jiang Peng , Feng Chao , Huang Rong , Wang Jun , Chen Junjun , Li Wenbo
Published: May 2023

Traditional Q235A distribution circuit fittings have high operation energy consumption and galvanized pollution problems, which is not in line with our carbon peaking and carbon neutrality goals. A new type of high-strength aluminum alloy with tensile strength up to 407.3 MPa and elongation at break up to 11% is created. It can be used to replace the traditional Q235A in the preparation of distribution circuit fittings.
Volatility analysis of the flight block time based on the stochastic volatility model
Authors: Sun Ya , Wang Meiyi , Xie Hua
Published: May 2023

To effectively predict the volatility of flight block time, this paper constructs a stochastic volatility model based on actual flight block time data, solves the model parameters by the Markov chain Monte Carlo method, and uses the standard stochastic volatility (SV-N) model and thick-tailed stochastic volatility (SV-T) model to characterize the volatility of flight block time. The results show that the thick-tailed stochastic volatility model is better than the standard stochastic volatility model in describing the volatility of the segment runtime, and the thick-tailed stochastic volatility model is chosen to predict the volatility of the flight block time. Predicting the flight block time volatility in real time can provide a theoretical basis for traffic traveler planning.
Dynamic CFD/CSD Coupling Research for Flexible Micro Aircraft
Authors: Chen Lili , Yang Wenqing , Wang Wei
Published: May 2023

Bio-inspired flapping wing aircraft have made progress in recent years. Flying birds can fly in various low Reynolds numbers (103-105) with high flight stability and maneuvering ability by use of the flexible deformation of skeletal muscle structures or thin-film structure wings. Early studies mainly focused on the aerodynamics and kinematics of the flapping wings, with relatively little research on the flexible structure, and the aerodynamic structure coupling characteristics of micro flappings are still unclear. At present, the focus of research is to evaluate the impact of structural deformation on the aerodynamic characteristics of flexible micro-flapping wing. A CFD/CSD coupling solver are developed and several technical challenges related to the CFD/CSD interface are resolved in this study (CFD/CSD data exchange method and moving mesh generation). The aerodynamic characteristics of five flexible wings with different structural parameters are calculated and compared. The results show that structural parameters play an important role in aerodynamic performance, which also indicates that the potential aerodynamic performance can be improved by the optimal structural design.
Noise Attenuation by Half Flat tip Serrated Trailing Edge in Rotating Blades
Authors: Chen Jieyan , Xie Jinlong , Mun Lee Hsiao
Published: May 2023

Two rotating blade models with different half-flat tip trailing edge serrations were proposed. The flow characteristics and aerodynamic noise were simulated using the large-eddy simulation model and Ffowcs Williams and Hawking’s acoustic analogy, respectively. The effect of half-flat tip trailing edge serrations in reducing noise was investigated. Results showed that the proposed half-flat tip trailing edge serration designs can effectively reduce broadband noise, and the effectiveness of noise reduction was related to the wavelength-to-amplitude ratio of the half-flat tip trailing edge serrations. The Wide-serrated blade had better noise reduction performance, and the local noise reduction according to the simulations can be as high as 3.3 dBA. Besides, it was found that the aerodynamic performance of the rotating blades was not detrimentally affected by the introduction of half-flat tip serration.
The High-speed Aircraft Trajectory Prediction Method Based on Deep Learning Network
Authors: Hu Yu Chuan , Dai Jing , Yi Juan , Fan Zhong Hang
Published: May 2023

This paper applies deep learning technology to the trajectory prediction research of high-speed aircraft in order to predict the medium- and long-term trajectory. Hence, a hybrid model combining the time series convolution neural network (TSCNN) and the long short-term memory (LSTM) is put forward to predict position and velocity of high-speed aircraft. In the TSCNN, convolution operations are used to extract trajectory features of time and space to predict the future trajectory. However, the error will be generated during prediction the process, so the LSTM network can be tapped to correct it by analyzing why it is produced in a bid to address error accumulation. According to simulations conducted, the model can lead to high-precision prediction.
Nozzle Thrust Eccentricity Calculation Based on FLUENT Software
Authors: Hu Yongzheng , Chen Jun , Shen Xiaodong , Dang Jiantao
Published: May 2023

Thrust eccentricity refers to the phenomenon that the thrust vector deviates from the axis of symmetry. This phenomenon will produce lateral force and torque around the aircraft, which affects the normal flight of the aircraft, increases the required control torque, and reduces the density of uncontrolled rockets. There are three sources of thrust eccentricity: mass eccentricity, geometric eccentricity, and aerodynamic eccentricity. The aerodynamic eccentricity is caused by the asymmetrical flow of combustion gas in the nozzle. This paper uses FLUENT software to carry out a numerical simulation of a cone-shaped nozzle. By changing different factors such as the structure of the inner surface of the nozzle and the convergence radius, the influence law of the inner surface structure of different nozzles on the lateral force of the pneumatic eccentricity of the nozzle is explored. The following conclusions were drawn: With the expansion of the expansion half-angle, the second zero point moves toward the nozzle outlet. The relative radius of curvature has little effect on the main thrust of the nozzle but has a certain influence on the eccentricity of its thrust, and as the relative radius of curvature increases, the first and second zeros move toward the throat.
Simulink-Based Simulation of Gas Pilot Servo Actuator for Aviation Ejection Seat
Authors: Zhou Congcong , Chen Jun , Duan Jianing , Wu Ruiqiang
Published: May 2023

The ejection seat needs the ability of rapid attitude adjustment to save lives, and the gas servo steering engine is a feasible scheme for correcting the seat position. The three closed-loop control system of the permanent magnet synchronous motor is built to realize the rotor position loop control of the motor; the working principle of the gas steering gear is analyzed, and the mathematical model of the gas servo system is constructed; Simulink is used to simulate the position of the motor and gas valve; the simulation results show that the steering gear can respond quickly to the control command, and the torque to the rudder surface generated by gas is large enough to meet the needs of the rudder blade to overcome the torque generated by the erosion of the rudder surface and the timeliness of the ejection seat.
Dual-antenna GPS-based UAV Attitude Determination Method and Accuracy Analysis
Authors: Wu Yilun , Sun Chunsheng
Published: May 2023

Accurate attitude information of small-sized unmanned aerial vehicles (UAVs) is required to obtain absolute azimuth information of a target via an airborne electro-optical imaging system. The direct attitude solution method of dual-antenna Global Position System (GPS) is investigated in this paper to address this need. We analyzed the attitude measurement principle of the direct method, gave the error estimation model, and estimated the inner and outer precision through simulation. The simulation results demonstrated that to achieve the requirement of UAV yaw angle error within 1°, the baseline length should be no less than 1 m. The applicability of the model and algorithm was confirmed.
Research on Flight Schedule Optimization Based on Different Runway Operation Modes
Authors: Wang Shuce , Hu Minghua , Zhao Zheng , Shu Jie , Zhu Xuhao
Published: May 2023

The update and iteration of the airport facilities completed in the runway operation system raise a request for more scientific control operation restrictions. In the old, optimized method of flight slot, no consideration was given to the runway operation strategy. As a result, the flight slot failed to meet the operation restriction and would incur unavoidable delays. This paper sets the research objective as the system composed of an apron, runway entrance and exit, and parallel runway. It focuses on matching the corresponding relationship between time and space of flights in the studied system. It establishes three flight slot optimization models to meet the requirements of isolated operation, semi-mixed operation, and mixed operation, respectively. On a practical level, the computer simulation software AirTOp is employed for simulation verification in the example of Wuhan Tianhe Airport. The results show that the delay in the isolation operation mode is reduced by about 59%, the semi-mixed operating mode reduces delays by about 48%, and mixed operating mode delays are reduced by approximately 52%. Therefore, it proves its feasibility of effective reduction in overall delay and its ability to provide decision support for the allocation of the flight time resource in parallel dual runway airports.
The Design of Dynamic Channelization and Signal Control System
Authors: Wang Yanjun , Wang Bing
Published: May 2023

For a long time, the development of urban transportation promotes economic development, however, which brings many urban traffic problems. The significant fluctuation of daily traffic volume has caused serious congestion and queuing at some small or medium-sized intersections. In order to enhance the performance of the, this paper proposes a scheme of dynamic channelization and signal control system which can be adapted to flat and peak. The scheme realizes the conversion of different channelization schemes via LED light strips laid on the road. In order to avoid potential conflicts in the process of scheme transformation, this paper focuses on the transition process from flat peak scheme to peak scheme. This scheme can also realize the systematic adjustment of traffic capacity at intersection, and also has the function of dynamic lane adjustment.
Research on Energy-saving Calculation of Navigational Lighting System Powered by Low Current in Green Airport
Authors: Ma Xiaodan , Li Tuo , Chen Fei , Zhang Lihua
Published: May 2023

The airport navigation lighting system is an important energy-consuming system in the flight area. The annual energy consumption of large and medium-sized airports can reach millions of kilowatt hours. At present, the airport is replacing traditional halogen lamps with LED navigation lighting for energy conservation. For LED lighting under the traditional 6.6 A power supply system, the circuit loss is high, and the overall energy-saving effect of the system is not good. A low-current power supply energy-saving navigation lighting system is proposed. The primary cable, secondary cable, isolation transformer, and auxiliary lighting system in the navigation lighting circuit are studied by performing the energy-saving calculation of navigation lights under low currents. By building a set of navigation lighting systems to conduct energy consumption experiments and comparing them with theoretical calculations, a calculation model is proposed to provide a basis for energy-saving calculations for the application of a low-current power supply navigation lighting system.
Analysis of single-phase grounding fault and its protection in the medium and low voltage distribution system
Authors: Jiang Chongran , Huang Yixiang , Xue Jiangyu
Published: May 2023

The single-phase ground fault of the medium and low voltage distribution system occurs most frequently in the distribution network. The fault should be eliminated in a short time. The single-phase ground short circuit fault that occurs when the neutral point of the power supply is not directly grounded in the medium and low voltage distribution network should be simulated and analyzed. The study seeks to understand the trend of voltage and current as well as the changes of its amplitude and phase when the fault occurs, which are consistent with the theoretical calculation and analysis. According to the analysis of single-phase grounding fault based on the simulated data, the acquisition of zero sequence current, the protection configuration, and the method of setting the point are discussed.
Research on bridge high-resolution optical fiber temperature sensing technology suitable for the low-temperature environment
Authors: Li Chen , Zho Liguo , Fu Zhipeng
Published: May 2023

An improved bridge Fiber Bragg Grating (FBG) temperature sensor technology is presented in this paper. The sensitivity and stability of the material and structure on the wavelength of the FBG are studied theoretically and experimentally. Compared with the traditional bridge temperature monitoring technology, the new sensor technology can adapt to a low-temperature environment and has high resolution. In order to verify the technology, experimental verification is carried out on the basis of theoretical analysis. The results show that the sensitivity of the new optical fiber temperature sensor is about 22 pm/°C, twice that of the bare raster, and shows good stability.
Correlation filter tracking of channel response constraints
Authors: Yuan Heng , Jiang Chenlu , Qi Huan
Published: May 2023

To solve the problem of moving object loss and inaccurate localization caused by the rapid change of object appearance, partial occlusion, and scale change in the tracking process, the channel response constraints correlation filter was proposed, i.e., CRCCF. Firstly, the channel self-optimizing regularization is introduced on the background-aware correlation filter (BACF), reducing the interference of redundant channel information to adapt to the complex environment. Then, the different response error regularization was introduced, the work used differences of adjacent frames response figures to learn the object appearance changes, which can smooth the volatility of the response figure to alleviate the drift problem model. And the Alternating Direction Method of Multipliers (ADMM) is used to optimize the model. Finally, a large number of experiments were carried out on OTB50, and OTB100 datasets to verify that the proposed algorithm has better performance under the conditions of fast motion, background clutter, and motion blur.
Vacuum booster control system design and fault self-check strategies
Authors: Liu Rui , Yuan Hong , Lin Li , Liu Chang , Huang Kaisheng
Published: May 2023

In this paper, the software and hardware design of the vehicle vacuum pump control system was carried out based on single-chip microcomputer technology. Combined with the vacuum pump structure and control principle, the hardware design of the power supply, barometric pressure sensor, vacuum pressure sensor, current detection, and motor drive is carried out with the HS08 series single-chip microcomputer as the core. The software strategy design for barometric pressure signal acquisition, vacuum pressure signal acquisition, and vacuum pump driving has been completed, and the dual pressure vacuum pump control system for electric vehicles has been developed. The system can diagnose the common faults of the vacuum power system. Finally, the functional test of the control system is carried out. The results show that the system can work normally and that the design meets the expected requirements.
Thermal Insulation Structure Design and Simulation Analysis of Optical Measuring Device under Extremely Low-Temperature Based on Phase Change Temperature Control
Authors: Guo Hailong , Zhang Zhi
Published: May 2023

To meet the thermal insulation requirements of the measurement system in the liquid oxygen tank of the rocket, we designed the thermal insulation structure of the optical measuring device at an extremely low temperature based on phase change temperature control, selected neicosane as the phase change material, and used 15 mm phase change layer to combine with 9 mm polyurethane thermal insulation layer to achieve passive temperature control. Finally, a thermal simulation model is established for transient thermal analysis. The simulation results show that the internal temperature of the system decreases from the initial temperature of 50 °C to -13.9 °C after 2 hours, which proves that the design meets the requirements.
Numerical simulation of drag reduction effect on the surface of bionic fish-scales
Authors: Wu Xueting , Wang Yonghua , Xu Jinkai , Yu Huadong
Published: May 2023

With the development of marine transportation and underwater navigation technology, fluid drag reduction has become an international research hotspot as an important technical means to save energy and reduce environmental pollution. It has been found that the body surface structures of many organisms have unique drag-reduction properties. Therefore, it is feasible and important to replicate the morphological features of the body surface to the material surface. In this research, the structural features of biomimetic fish scales were summarized and extracted by observing the laminar arrangement features and morphology features of the surface scales of aquatic fish. Then, the arrangement features and morphology of fish-scales were abstracted into the oblique groove structure, and a three-dimensional model of the bionic fish-scale with a fan-shaped structure was constructed. The surface flow field of the bionic fish-scale was numerically simulated by COMSOL Multiphysics to revealing the mechanism of resistance reduction on the surface of the bionic fish-scale. The results indicate that the maximum drag reduction rate of the bionic fish scale surface is 8.40% compared with the smooth surface at a water speed of 0.6 m/s.
Simulation Calculation of the Support Column Deformation of the Precision Crane Based on Abaqus
Authors: Wang Shang , Peng Fei
Published: May 2023

The support columns of cranes can undergo minor deformations under heavy pressure, which poses a challenge to lifting sophisticated equipment, such as satellites. To improve the stability and accuracy of the crane, the small deformation of the support column was studied. Two methods, numerical simulation and calculus derivation, were adopted by the research team. The results show that the numerical value calculated by the finite element method is 12.43 μm, while the numerical value derived by integration is 12.50 μm. The relative error is within the acceptable range, which verifies the accuracy of the model. The finite element method can calculate the deformation of precision crane column to improve its accuracy and safety, and provide data support for the design and optimization of precision crane.
Research on indoor real-time positioning technology of LED visible light communication based on arbitrary three-axis rotation angle
Authors: Lv Liangliang , Liu Tingzhang , Yan Wenyi , Fan Ruijie
Published: May 2023

LED visible light communication indoor positioning system based on three-axis rotation angle of cell phone, including modulated signal LED downlight, rotation vector sensor and camera of smartphone, target tracking module and developed positioning method. The main processes are: the three-axis rotation angle of cell phone obtained from the rotation vector sensor, the position information of LED downlight image in pixel coordinate system obtained from the camera, the LED downlight position information obtained by decoding method, bring the above information into the positioning system. Meanwhile, the target tracking module based on Continuously Adaptive Mean-shift (CAMSHIFT) algorithm can effectively enhance the system operation speed and improve the real-time performance, and the three-axis rotation angle can effectively adapt to the cell phone pose transformation. This positioning system performs well in terms of positioning accuracy and real-time performance.
Intelligent Speech Garbage Classification Based on Deep Residual Network
Authors: Dong Duanni , Yu Jinjun , Shan Yihan , Zhou Zixuan
Published: May 2023

To solve the problem that there are many kinds of municipal solid waste and urban residents do not have a clear classification standard for garbage, an intelligent voice garbage classification system based on a deep residual neural network is designed. For the four kinds of common garbage in life, the voice commands of four kinds of typical garbage are collected. Through the speech endpoint detection algorithm, the silence and noise in the speech are removed, and the acoustic model based on the deep residual network is built to realize garbage classification. The experimental results show that after the model training is completed, the accuracy of the verification set reaches 98%, the accuracy of the test set reaches 96%, and the generalization ability is strong, which has a high application value.