bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of elastic loss of piezoelectric materials by impedance curve fitting using intelligent algorithms
Authors: Gao Yifeng , Xian Xiaojun , Chen Yinyin , Suo Zhipeng , Xu Jiang , Yang Zengtao
Published: March 2024

Understanding the loss parameters of piezoelectric materials is crucial for designing effective piezoelectric sensors. Traditional elastic loss parameter measurement techniques mainly rely on three methods: 3 dB bandwidth, impedance fitting, and ultrasonic attenuation. However, the elastic losses obtained through these methods are constant and frequency-independent, which does not align with the actual vibration characteristics of piezoelectric materials. Therefore, there is a need for a fast, accurate, and frequency-dependent method to obtain the elastic loss of piezoelectric materials. This paper introduces an approach that utilizes intelligent algorithms for fitting impedance curve to calculate elastic loss parameters. A frequency-dependent second-order energy loss model for piezoelectric materials is established. Then, a genetic algorithm is introduced to obtain the optimal elastic loss parameters. The results demonstrate a high consistency between theoretical and experimental impedances, with an error less than 5%. The elastic loss parameters obtained through intelligent algorithm-based impedance curve fitting match well with stress experiment results, with an error less than 6%. This method provides a rapid, accurate, and cost-effective way to obtain frequency-dependent second-order elastic loss parameters for piezoelectric materials.
Experimental study on ultrasonic-assisted electrochemical polishing of NiTi alloy
Authors: Che Jianwei , Shi Guangfeng , Xu Ying
Published: March 2024

NiTi alloy has a wide range of applications due to its unique superelasticity and shape memory, the superelastic function of NiTi alloy made it had been applied in building shock absorption, advanced bearings and other scenes, the shape memory function made it also applied in the fields of aerospace engine heat exchanger, cardiac medical stent and so on. In order to made NiTi alloy better applied in practice and improve its surface quality, it was crucial to polish it. In this paper, a new method of ultrasonic-assisted electrochemical polishing of NiTi alloy was innovatively proposed, and an ultrasonic electrochemical polishing device was built independently. The effects of ultrasonic amplitude, voltage and temperature on roughness were explored by Box-Behnken experimental design method. The results show that after ultrasonic-assisted electrochemical polishing, the roughness Ra had been reduced from about 2 μm to the minimum of 0.048 μm. The surface quality of NiTi alloy was improved. The impact of micro-jet of cavitation bubble on NiTi alloy mainly occurs in the early stage, and the equivalent stress on the surface of NiTi alloy was annular, showing an increasing and decreasing trend. In the whole ultrasonic electrochemical polishing solution, a large number of micro-jets will impact the surface of NiTi alloy, thus realizing the material removal. This study enhances traditional electrochemical polishing techniques by integrating ultrasonic energy fields, thus broadening the scope of electrochemical polishing applications. Additionally, it presents a novel approach and establishes a foundation for the polishing of NiTi alloys with intricate geometries in additive manufacturing.
Hosting exceptional point in all-lossy dual-core optical fiber and its exotic chiral light dynamics
Authors: Roy Arpan , Dey Sibnath , Biswas Abhijit , Ghosh Somnath
Published: March 2024

Exploration of exceptional points (EPs) and associated unique features in gain-loss assisted optical systems to develop future all optical devices have been a great interest in recent years. However, incorporation and adjustment of gain distribution in a system is quite challenging. Here, we design a fabrication feasible dual-core optical fiber where only the customized transverse loss profile controls the interaction between two coupled modes and results in hosting an EP. Parametric encirclement of the identified EP and corresponding chirality-driven asymmetric mode conversion phenomenon between the supported modes have been reported. The proposed structure features ease of fabrication using state-of-the-art techniques with possible applications in all-optical components for communication and all fiber photonic devices.
Implementation of a PAFV turbulence model for airfoil flow simulation on OpenFOAM
Authors: Yan Wenhui , Sun Zhaozheng , Sun Yifan , Tian Xiao
Published: March 2024

To further develop a more effective turbulence model and to improve the calculation accuracy of the flow around airfoil, a new PAFV turbulence model has here been constructed by using a deformation rate tensor and the grouping of an average fluctuation velocity. To evaluate the applicability of the PAFV turbulence model, the numerical calculations of flow around the airfoil have here been implemented, which was based on the OpenFOAM calculation platform. On the basis of grid independence research, the model was used to calculate the low-speed flow-around problem for the plano-convex airfoil NACA4412 and the symmetric airfoil NACA0012. It was also compared with the S-A (Spalart-Allmaras) and SST (Shear Stress Transport) k-ω turbulence models. Firstly, the maximum lift angle-of-attack case of the NACA4412 airfoil was calculated. Thereafter, numerical calculations were performed for the flow around the airfoil in the multi-angle-of-attack case of the NACA0012 airfoil. The results showed that the NACA4412 airfoil had an obviously separated vortex at the trailing edge of the airfoil at the maximum lift angle of attack. Also, there was a certain velocity loss downstream of the trailing edge, which was calculated by all three models. However, the results of the PAFV turbulence model were found to be better than those of the S-A and SST turbulence models. The three turbulence models showed comparable accuracies for the calculations of the surface pressure coefficients of the NACA0012 airfoil. However, the S-A and SST k-ω turbulence models were slightly better for the calculations of the mean velocity profiles of the NACA0012 airfoil. Also, the PAFV turbulence model was more accurate for the calculations of the lift and drag coefficients. In conclusion, the PAFV model can make effective predictions of the airfoil low-speed flow around the problem at hand, which in turn preliminarily verifies the applicability of this turbulence model for the low-speed flow around the airfoil problems.
Effect of emitter-base spacer design on the performance of InP/GaAsSb/InP DHBTs grown by MOCVD
Authors: Liu Zhen , Zhu Hong , Deng ShuQing , Pan XinYi , Huang Yong
Published: March 2024

Effect of spacer layer design between InP emitter and GaAsSb base in InP/GaAsSb/InP double heterojunction bipolar transistors (DHBTs) grown by MOCVD was investigated. A very thin tensile-strained GaAs layer, or a thin GaInP layer, or combination of both was inserted between InP emitter and GaAsSb base to mitigate Sb segregation and/or eliminate electron pile-up between emitter and base. With a base sheet resistances of ∼1800 ohm sq−1 for all devices, DHBTs with a GaAs spacer, a GaInP spacer and the combination demonstrate a current gain of 24, 49 and 64, respectively. The conduct band discontinuity ΔEc at InP/GaAsSb interfaces and the current blocking effect are effectively eliminated by employing the combination of GaAs and GaInP layers.
Potentials and fields of a charge set suddenly from rest into uniform motion
Authors: Hnizdo V , Vaman G
Published: March 2024

The fact that electromagnetic effects propagate at the speed of light suggests how the Lorenz-gauge scalar and vector potentials of a uniformly moving point charge must be modified when the charge was initially at rest and then set suddenly into uniform motion. The modified potentials are shown to satisfy the requisite inhomogeneous wave equations. The gauge function of the transformation of these potentials to the Coulomb gauge is calculated in closed form. It is validated by confirming that the Coulomb-gauge vector potential that is calculated using it yields together with the Coulomb-gauge scalar potential the same electric and magnetic fields as those calculated with the Lorenz-gauge potentials.
Implementation and measurement of quantum entanglement using IBM quantum platforms
Authors: Karimi Naser , Navid Elyasi Seyed , Yahyavi Marziyeh
Published: March 2024

The use of quantum entanglement has garnered increasing attention among researchers in recent years due to its wide range of applications, not only revolutionizing the field of information processing but also enhancing quantum-safe communications. Identifying the degree of entanglement present in quantum states is a crucial focus, and designing an algorithm capable of feasibly measuring entanglement is imperative. While theoretical calculations hold high regard, the ease of implementing these algorithms in a laboratory setting is essential to gauge their efficiency.In this context, IBM quantum computers stand out as discrete value NISQ (Noisy Intermediate-Scale Quantum) platforms These platforms are based on superconducting qubits, providing an opportunity to test our algorithms without the need for extravagant laboratory equipment. This paper proposes an algorithm designed to measure entanglement in a bipartite system. We will execute the algorithm on IBM’s 127-qubit backends to compare our calculations with real-world results. Furthermore, we aim to address and mitigate errors inherent in these devices by utilizing local mitigation technique available in the IBM Experiments Python package, aiming for more accurate and reliable outcomes.
Indoor positioning fingerprint database construction based on CSA-DBSCAN and RCVAE-GAN
Authors: Pan Lei , Zhang Hao , Zhang Liyang , Gao Rui , Zhang Qian
Published: March 2024

With the increasing size of buildings, in order to achieve high-precision indoor positioning services, it is a challenging task to build an offline fingerprint database with high quality, high density and less manpower and material consumption. Aiming to solve the problem of low-quality WiFi indoor positioning fingerprint inventory constructed by traditional methods, which affects positioning accuracy and incurs high costs, this paper proposes a method for indoor positioning fingerprint database construction based on Crow Search Algorithm Optimizes Density Clustering (CSA-DBSCAN) and Regressor Conditional VAE Generative Adversarial Network (RCVAE-GAN). Collecting only a tiny amount of sparse reference point position coordinates and RSS data makes it possible to construct a high-quality WiFi indoor positioning fingerprint database. Firstly, the method utilizes the density clustering method based on Crow Search Algorithm Optimization (CSA-DBSCAN) to process RSS data collected from the reference point. This helps minimize the impact of abnormal RSS data on creating the fingerprint database. Secondly, the RCVAE-GAN depth generation model was developed. The model consists of an encoder E, a generator G, a discriminator D, and a regressor R. After constructing the model, the data with abnormal RSS will be removed and input into the model for pre-training and joint training, resulting in a high-quality deep-generation model. Finally, a high-quality and high-density fingerprint database is constructed by combining the collected reference points with fingerprint data generated by the depth generation model. Experimental results show that the proposed method reduces the root mean square error (RMSE) deviation of the generated fingerprint data by 38% and 12% respectively, compared to the RBF interpolation method and the CVAE-GAN method in the same experimental scenario. The constructed fingerprint database is used for positioning, improving positioning accuracy by 70% and 65% respectively. The method described in this paper can construct a high-quality fingerprint database, effectively improving the efficiency of fingerprint database construction and reducing the costs associated with labor and time.
Beam quality evolution in large-mode-area specially doped laser fiber through bend-induced effective refractive index change
Authors: Chowdhury Sajib , Majumder Debparna , Akash Gomes Vincent , Pal Debasis , Dhar Anirban , Pal Atasi , Ghosh Debashri
Published: March 2024

The effect of bending in a specially doped large-mode-area (LMA) gain fiber on the beam quality of the laser and amplifier has been studied through simulation and experimentation. The effect on the overlap between the fundamental mode (FM) and the doping region due to bend-induced refractive index change was studied theoretically by varying the bend radius. Bend radius of the gain fiber in the range of 5–8 cm was used to study the evolution of beam quality at the amplified output. The numerical simulation of the overlap between the FM and the dopant distribution in the core of the gain fiber for different bending radii is well matched to the experimentally measured beam quality of the amplified output for the respective bending of the gain fiber. The master oscillator (having M
2 = 1.1) was successfully amplified to 35 W maintaining the near-diffraction-limited beam quality (M
2 = 1.05) using a confined doped LMA gain fiber with a bend radius of 8 cm. However, the use of a uniform doped LMA gain fiber with similar bend configuration degrades the beam quality (M
2 = 1.37) at the amplified output power of 31.3 W.
High brightness widely tunable, hundred picosecond mid-IR MgO:PPLN optical parametric oscillator with short cavity
Authors: Li Zhen-Ling , Zhang Ao-Nan , Wang Yun-Ping , Liu Ke , Wang Xiao-Jun
Published: March 2024

A high brightness hundred picosecond (ps) mid-infrared tunable optical parametric oscillator (OPO) based on MgO doped periodically poled lithium niobate (MgO: PPLN) was demonstrated. The pumping source was provided by a cascade amplified microchip laser at 10 kHz with pulse width of 466 ps. The idler wavelength tuning from 2.8 to 4.3 μm was achieved by the combination of period and temperature tuning. The maximum idler average output power was 262 mW at 2.8 μm with a pulse duration of 252 ps, corresponding to 6.7% conversion efficiency. The average beam quality factor was measured to be M
2 = 2.46, resulting in a brightness value of 0.55 MW sr cm−2. Pulse width of 209 ps at 4.3 μm, which was the shortest pulse width from a short cavity OPO to our best knowledge.
Investigating the impact of the universal function of the nuclear proximity potential in heavy-ion fusion cross sections
Authors: Gharaei R , Sarvari E
Published: March 2024

The fusion barriers and cross sections of 15 colliding systems with 320 ≤ Z
1
Z
2 ≤ 1512 are investigated in detail to understand the influence of the universal function of proximity potential formalism in the heavy-ion fusion mechanism. To realize this goal, we select three versions of the phenomenological proximity potentials, including Prox. 77, Zhang 2013, and Guo 2013, to calculate the nucleus–nucleus potential. The experimental fusion cross sections for the selected reactions are analyzed using the standard coupled-channel calculations, including couplings to the low-lying 2+ and 3− states in the target and projectile. The calculated results show that the universal functions of the Guo 2013 and Prox. 77 models provide the lowest and highest fusion barriers, respectively. In addition, it is found that the height of the fusion barriers is enhanced by increasing the mass number of the projectile from light to heavy ones. The highest sensitivity to the mass number of the projectile belongs to the results of Prox. 77. A discussion is also presented on the influence of the universal function on the radial behavior of the interaction potential in the allowed region for overlapping configurations. Our results reveal that the best fit to the experimental data of the fusion cross sections for the reactions involving light and medium nuclei is obtained using the universal function of the Zhang 2013 model. For the heavier systems, the results of the Guo 2013 model at sub-barrier energies provide a good description of the available data.
Design of a novel hybrid quantum deep neural network in INEQR images classification
Authors: Wang 王 Shuang 爽 , Wang 王 Ke-Han 柯涵 , Cheng 程 Tao 涛 , Zhao 赵 Run-Sheng 润盛 , Ma 马 Hong-Yang 鸿洋 , Guo 郭 Shuai 帅
Published: March 2024

We redesign the parameterized quantum circuit in the quantum deep neural network, construct a three-layer structure as the hidden layer, and then use classical optimization algorithms to train the parameterized quantum circuit, thereby propose a novel hybrid quantum deep neural network (HQDNN) used for image classification. After bilinear interpolation reduces the original image to a suitable size, an improved novel enhanced quantum representation (INEQR) is used to encode it into quantum states as the input of the HQDNN. Multi-layer parameterized quantum circuits are used as the main structure to implement feature extraction and classification. The output results of parameterized quantum circuits are converted into classical data through quantum measurements and then optimized on a classical computer. To verify the performance of the HQDNN, we conduct binary classification and three classification experiments on the MNIST (Modified National Institute of Standards and Technology) data set. In the first binary classification, the accuracy of 0 and 4 exceeds 98%. Then we compare the performance of three classification with other algorithms, the results on two datasets show that the classification accuracy is higher than that of quantum deep neural network and general quantum convolutional neural network.
Layered kagome compound Na2Ni3S4 with topological flat band
Authors: Ye 叶 Junyao 君耀 , Lin 林 Yihao 益浩 , Wang 王 Haozhe 浩哲 , Song 宋 Zhida 志达 , Feng 冯 Ji 济 , Xie 谢 Weiwei 韦伟 , Jia 贾 Shuang 爽
Published: March 2024

We report structural and electronic properties of Na2Ni3S4, a quasi-two-dimensional compound composed of alternating layers of [Ni3S4]2− and Na+. The compound features a remarkable Ni-based kagome lattice with a square planar configuration of four surrounding S atoms for each Ni atom. Magnetization and electrical measurements reveal a weak paramagnetic insulator with a gap of about 0.5 eV. Our band structure calculation highlights a set of topological flat bands of the kagome lattice derived from the rotated d
xz
-orbital with C
3 + T symmetry in the presence of crystal-field splitting.
Shear Alfvén waves within magnetic islands
Authors: Könies Axel , Cao Jinjia , Kleiber Ralf
Published: March 2024

We calculate Alfvén eigenmodes within a magnetic island (MiAE) which have been conjectured over a decade ago. Starting from a cylindrical plasma equilibrium, we calculate the complete metric of the island interior assuming an iota profile with a constant shear for Wendelstein 7-X parameters. Then, we solve the resulting Magneto-Hydrodynamic equations inside the island optionally considering Finite Larmor Radius corrections. We find various eigenmodes in the lowest gaps for n = 0. The eigenmode with the lowest frequency shows a weakly non-linear dependence on the island width which deviates considerably from an earlier estimate.
Corrigendum: PythonDAQ  A Python based measurement data acquisition and processing software (2023 Journal of Physics: Conference Series 2511 012016)
Authors: Jäger D , Gümmer V
Published: March 2024

Please see Article PDF for corrigendum text.
Automatic calibration of airborne LiDAR installation angle based on point cloud conjugate matching
Authors: Gu Qiuling , Zhou Yudi , Zhao Hongkai , Ma Shizhe , Sun Wenbo , Liu Dong
Published: March 2024

Airborne LiDAR plays an important role in island detection, shallow ocean topography mapping and intertidal zone detection. The installation angle error usually leads to deviation between overlapping strips, which affects the accuracy of LiDAR point cloud data. However, previous methods had complex requirements for routes and calibration field, leading to inefficient calibration. This paper proposes an automatic installation angle error calibration algorithm based on point cloud conjugate matching, which does not require strict route design and field selection. In the algorithm, the conjugated point cloud is extracted by selecting routes and processing point cloud, and the installation angle error is calculated by matching the conjugate point cloud. Airborne LiDAR data from Shanghai Institute of Optics and Fine Mechanics is utilized to verify the method which show that the overlap degree of conjugate point clouds can reach 90% in different routes. This method is expected to dramatically improve the efficiency of system calibration and the convenience of measurement.
Numerical simulation of immersion of a tunnel element - downscaling by CFD technology
Authors: Yin Tienan , Liu Xin , Wu Lunyu , Pan Qingqing
Published: March 2024

During the immersion process of tunnel elements in the sea, the surrounding currents would inevitably be changed. A large scale ocean circulation model, which can simulate the sea currents, usually do not solve underwater structures. Thus, in this chapter, we use a downscaling Computational Fluid Dynamics model to simulate the flow characteristics around an immersed tunnel element for Shenzhong Link in China, under different velocity inlets and at different depths. Since E1 element is shielded from diversion dike and the flow velocity around is small, this paper focus on simulation of the flow field during the immersion process of E2 element after the completion of E1.
Numerical Study on the Effect of Warm Ocean Anomalies in the South China Sea on the Heavy Rainfall Event on Hainan Island
Authors: Hao Sai , Peng Wei , Chen Li , Liu Xiaoyan , Liu Kewei
Published: March 2024

The previous work has found that the development of an extended TD, which resulted in an abnormally prolonged and heavy rainfall event on Hainan Island from 1 October to 9 October in 2010, was significantly influenced by warm oceanic anomalies from surface to subsurface layer in the SCS. Numerical experiments using the Weather Research and Forecast Model (WRF) were conducted to understand the mechanisms of TD development during this event. A control experiment with an observed warm SST pattern simulated a reasonably extended TD, while a sensitivity experiment using the climatological SST distribution reproduced only a weak and short-lived TD, thus highlighting the importance of air-sea interactions and persistent warm upper-ocean anomalies for the genesis and intensification of the TD.
A study of range dependent acoustical field based on the FVCOM model: A Case of typhoon NANMADOL
Authors: Wang Qianhui , Han Kaifeng , Shi Jian , Xiao Wenbin , Cao Xuhui
Published: March 2024

This study simulated the acoustical field in the western North Pacific (WNP) during typhoon NANMADOL, based on the FVCOM model and Range dependent Acoustic Model RAM. We implements a new approach, which helps to accurately characterize the energy distribution of acoustical field obtained by considering the range dependent ocean dynamical environment elements. The results show that, the sound speed profile in the upper-layer ocean of the sea water decreases to a certain extent on the day after the typhoon’s arrival, while the maximum decrease in the sound speed after the typhoon’s transit occurs 1∼2 days. The maximum decrease in the seawater sound speed can be up to 2-3 m/s 2 days after the typhoon’s transit. The passage of the typhoon mainly affects the far-field acoustical energy distribution when the sound source is located near the upper-layer ocean.
Feasibility of tide simulation using nesting module of FVCOM—a case study of Xiangshan Bay
Authors: Xu Yikai , Zhu Yuhang , Liu Zhe , Hu Song
Published: March 2024

The nesting module of FVCOM is widely utilized in numerical simulations for both nearshore and offshore. However, the details of the nesting module on computation accuracy and efficiency have not been quantitatively assessed. In this study, we take Xiangshan Bay as a case study area and design two groups of experiments to examine this issue on tide simulation. The results indicate that nesting module effectively incorporates all tidal information from the open ocean through the boundary. The nesting module experiment successfully simulates the tides almost exactly similar to the original tides, while achieving an efficiency improvement of approximately 48% by avoiding computations outside the high-resolution area.
Impacts of the Kuroshio Extension Stability on the Storm-track over the North Pacific
Authors: Jiang Y X , Sun J X , Wu X H , Wang H
Published: March 2024

The Kuroshio Extension (KE) modulates and influences the weather and climate over the North Pacific and even the entire earth through intense sea-air interactions. In this study, the seasonal responses of the North Pacific storm-track to the KE inter-annual variability are investigated by employing the lag regression approach. The results show that, there are significant seasonal variations in the storm-track responses to the KE stability variability. When the KE is stable in spring, the atmospheric low-level baroclinicity is intensified over the mid-latitudes of the North Pacific, resulting in the enhancement and upstream displacement of the storm-track. Similarly, the summer storm-track is also strengthened as a result of the stronger baroclinicity over the mid-latitudes of the North Pacific. In autumn and winter, the intensified baroclinicity in the upstream region of the storm-track, which is conducive for the development of synoptic eddies to the upstream of its climatological region, causes an upstream displacement of storm-track.
Motion Error Mechanism Analysis and Simulation Verification of Ocean Electric Field Sensor
Authors: Liu Junwei , Qiu Xiaotian , Chen Dixiang , Du Qingfa , Ding Zengquan , Pan Mengchun , Luo Huihui , Kuai Tao , Qin Yuhang
Published: March 2024

The electric field measurement based on Unmanned Underwater Vehicle (UUV) can monitor and evaluate real-time electric field of underwater targets in motion, which has the ability to adapt to harsh marine environments. However, electric field sensors generate new errors during underwater motion, and there is still absence of studies on the error theory and simulation. To address this, the error generation mechanism of Ag/AgCl electrodes induced by the flow field was analyzed in this paper. A coupled mathematical model of flow-chemical-electric multi-physical field was established for the first time, and finite element simulation analysis was carried out. The results show that the change value of electrode surface potential under the influence of flow rate is basically in agreement with the empirical formulae. R-squared value of the two fits reaches up to 0.968, and RMSE value is less than 0.003, confirming the robustness of the model and simulations. The multi-physical field coupling model and simulation method proposed in this paper can provide theoretical and methodological support for the design of electric field sensors and motion error correction.
Dynamic robust path-following control of UVMS subject to manipulator disturbance
Authors: Jiao Huifeng , Wang Guanhua , Wang Yintao , Mao Zhaoyong
Published: March 2024

This study addresses path-following control issue of underwater vehicle-manipulator systems (UVMS) in the presence of manipulator disturbances. It considers disturbance forces arising from manipulator position changes, including restorative forces and coupling forces, to achieve precise UVMS path-following control. By analysing the variations in the center of mass and buoyant center of manipulator links during motion, the corresponding restorative torque is deduced, and disturbance forces are calculated. Additionally, joint coupling forces generated during manipulator startup, braking, and rotation are taken into account. These aspects collectively yield the expression for disturbance forces. Subsequently, adaptive sliding mode control are employed to achieve accurate control of the UVMS system. This study effectively addresses the issue of UVMS body control under manipulator disturbances. By analysing the motion of manipulator links, the disturbance forces exerted by the manipulator on the UVMS are identified, offering insights for similar control challenges arising from manipulator disturbances. Simulation results are conducted to show the effectiveness of the proposed control method.
Fault Diagnosis of Wind Turbine Blades Based on Image Fusion and ResNet
Authors: Wu Sheng , Wang Guoliang , Jiang Nian , Zhang Shuai , Zhang Pingping , Liu Yang
Published: March 2024

In the diagnosis of wind turbine blade faults, the information provided by a single sensor is limited. To address this issue and take advantage of complementary features among multiple fault information sources, while enhancing fault diagnosis accuracy, a method for diagnosing wind turbine blade faults is proposed. This method combines Image Fusion Convolutional Neural Network (IFCNN) with the ResNet network. Firstly, the time-frequency representation of vibration data is obtained using wavelet transform. The time-frequency representation and blade fault images are input into the IFCNN to obtain fused images containing two categories of fault features. Next, the ResNet convolutional neural network is employed to automatically extract non-linear features from the fused images, establishing a classification model for blade fault images. Experimental results demonstrate that, with limited training data, the classification accuracy of this method can reach 86.7%, outperforming fault diagnosis models trained with single fault information. This approach offers a new perspective and method for the fusion of multiple fault information in the field of wind turbine blade fault diagnosis
Reconstruction of Thermocline Depth based on Machine Learning
Authors: Guan Zengxin , Bao Senliang , Wang Huizan , Zhang Ren , Chen Jian , Lyu Hailong
Published: March 2024

The thermocline, as a special structure in the ocean temperature field, has an important impact on sound propagation, material transport, and human underwater activities in the ocean. Using existing methods, the thermocline is distributed underwater and cannot be observed in real-time and with high spatiotemporal accuracy. It can only be calculated from measured data. In previous studies, it was demonstrated that the ocean thermocline is significantly correlated with its sea surface elements. Based on machine learning methods, this paper uses sea level anomaly, sea surface temperature, sea surface salinity, time, longitude and latitude, as well as the vertical gradient method to calculate the depth of the thermocline as data. By constructing a Random Forest model, the regression relationship between the thermocline and sea surface elements and spatiotemporal elements is obtained, this thermocline reconstruction model has a good fitting effect on thermocline depth, with a fitting coefficient of 0.85, and its accuracy has been evaluated. This paper also evaluated the feature importance of the six input data of the model. The results showed that the three sea surface parameters had similar importance, with sea surface temperature having the most significant impact on the depth of the thermocline. The final model can achieve rapid reconstruction of thermocline depth using sea surface information.
Research on Sound Source Localization of Multiple Fixed Targets Based on Machine Learning and Distributed Arrays
Authors: Liu Shuo , Li Heng , Yu Qiankun , Zhao Yun , Zhang Wen
Published: March 2024

This paper studies a sound source localization method of multiple fixed targets based on machine learning and distributed arrays. In an outdoor open field, a three-line array was applied to collect array data and calculate latency characteristics. Then multiple classification models were established and trained. Finally, the locations of the sound source points were predicted by those models, in which the support vector machine (SVM), the nearest node (KNN), and the naive Bayesian model achieved 100% localization accuracy. Compared to the conventional method, this method has three significant advantages: First, it does not rely on the microphone channel order and does not need to be calibrated in advance, which simplifies the localization process; Second, it can fulfill high accuracy requirements, especially suitable for the scene of multiple fixed targets; Third, it has the advantage of incremental learning, as the times of localization rises, the training set is continuously enriched and the localization results become more precise.
Seismo-acoustic anomalous interference pattern in shallow water
Authors: Dong Yang , Piao Shengchun
Published: March 2024

In shallow water layered leaky waveguide, the sound energy below the cut-off frequency is coupled to the seismic sound field. Very low frequency (VLF) sound is propagated in both water-borne and bottom-trapped modes. Under these circumstances, the interference characteristics of sound field and its application are different from those of medium and high frequency, which is the subject of this study. In a multi-channel seismic exploration experiment in the South Yellow Sea, an anomalous interference pattern for the VLF band, e.g., the waveguide invariant of interference striations changes from positive to negative with increase of frequency, was observed in the range-frequency domain. Numerical simulations and modal analyses show that the anomalous interference pattern corresponds to the interference between waterborne modes and bottom-trapped modes, because the group velocity for these two types normal modes change differently in the VLF band.
Effect of underwater vehicle wake on sound propagation characteristics in stratified medium
Authors: Feng Jiabao , Song Yang
Published: March 2024

Due to the uneven distribution of seawater temperature and salinity, the density distribution at different depths is different, thus forming a density step layer with a certain gradient. Acquiring the wake internal wave field generated by underwater vehicles passing through this layered structure and mastering its modulation characteristics for the sound field can provide new technical support for the tracking and identification of underwater vehicles. In this paper, the real size model of a certain type of underwater vehicle is taken as the research object to explore the characteristics of its wake internal wave field, and the influence of navigation parameters on the wake field and the change of winning characteristics under the influence of internal waves are simulated and analyzed. The results show that the navigation parameters of underwater vehicles have obvious influence on the wake field, and then have specific influence on the sound field structure in a certain range, especially on the sound signal of the sound field.
Modeling and simulation analysis of hydroacoustic field under ice
Authors: Wang K L , Chai Z G , Zhu H H , Wang H C
Published: March 2024

In order to study the effect of polar ice on sound propagation in seawater, the finite element method was used to establish a seawater sound propagation model with and without ice, and the influence of the presence of ice on the seawater sound propagation law was analyzed. The simulation results show that the energy of sound propagation in seawater has a certain loss when there is an ice layer compared with the case of no ice layer. Through frequency domain analysis, the propagation process of sound energy in seawater can be clearly seen. Normally, the sound energy generated by a point source at a suitable location will return to the seawater after passing through the sea surface, while after the addition of the ice layer, part of the sound energy generated by the point source will be lost to the air through the ice layer, resulting in a reduction of the acoustic energy returned to the seawater. As a result, there is less acoustic energy in the seawater than in the ice-free case.
Sound intensity fluctuations caused by internal solitary wave train in the South China Sea
Authors: Gao Fei , Xu Fanghua , Li Zhenglin , Qin Jixing , Ma Shuqing
Published: March 2024

Dynamic internal solitary wave (ISW) can cause significant underwater sound fluctuations. In this paper, the periodic characteristics of sound intensity fluctuations and related physical mechanisms are investigated in the scenario that an ISW train passing through the acoustic path from source to receivers. From simulation results and experimental data, it is shown that the sound intensity fluctuates quasi-periodically, and the predominant fluctuation frequency is associated with modal interference and modal intensity. The initial mode coefficients at the source and the mode coupling are responsible for the fluctuations of modal intensities, and one of the predominant fluctuation periods is the same as that of the ISWs.
Moving harmonic source depth estimation by MDFMD-v in a weakly range-depend waveguide
Authors: Xu Yangjin , Li Xiaolei , Gao Wei
Published: March 2024

To estimate the depth of a non-cooperative moving sound source in a range-depend waveguide, a passive depth estimation method combining depth-polarity search for a harmonic moving source is proposed in this paper. Firstly, the method obtains each mode parameters at the source and horizontal linear array (HLA) locations by utilizing the modal depth function constrained modal Doppler velocity estimation (MDFMD-v) and matrix pencil (MP) methods, respectively. Subsequently, mode amplitudes are calculated by compressive sensing. To determine the polarity of each mode amplitude, a depth-polarity search method is given in this paper. Finally, a depth ambiguity function with mode amplitude polarity is used to obtain the depth estimation results. Simulation results verify the effectiveness of the method.
DOA Estimation of Broadband Sources Using Dimension-Reduced Matrix Filter with Deep Nulling in a Strong Interference Environment
Authors: Bian Zhaoxiang , Wang Haozhong , Gao Wei , Song Penghua
Published: March 2024

To enhance the performance of the adaptive matrix filter with nulling, a dimension-reduced matrix filter with deep nulling (DR-MFDN) is proposed in this paper and used for direction of arrival (DOA) estimation of broadband sources in a strong interference environment. Consider the change of noise after filtering, the gaussian matrix is used for prewhitening to prevent the noise from converting into colored noise without affecting the response characteristics of the beam-space. Finally, the multiple measurement vector orthogonal matching pursuit (MOMP) algorithm is used for DOA estimation of weak targets after filtering, and the simulation results show a better DOA estimation performance compared to the OMP and MUSIC algorithms with short snapshots.
Source localization in deep ocean based on complex convolutional neural network
Authors: Yang Zhikai , Shen Tongsheng , Cui Mengda , Luo Zailei , Li Xionghui , Zhao Qiankun
Published: March 2024

To solve the problem that phase information cannot be used effectively in underwater acoustic localization, a deep learning network based on complex convolutional neural network is proposed in this paper. The complex convolution layer is used to effectively utilize the phase features favorable to the source localization problem, and the phase information is used to improve the feature extraction performance. Through simulation, the performance of the network for source localization in deep-sea direct arrival region under different SNR conditions is analyzed. The results show that the complex convolutional network proposed in this paper can locate the sound source with less computation and has better performance under the condition of low SNR.
Research on Sonar Motion Compensation Method Based on Acoustic Calibration System
Authors: Tang Wusheng , Liang Peihui , Wang Jun , Xu Pan , Lou Kang , Han Jingqi , Zhang Peng
Published: March 2024

The influence of sonar motion error restricts the improvement of sonar imaging resolution. High-precision sonar motion compensation is an important guarantee for high-quality imaging. In this paper, a sonar motion compensation method based on acoustic calibration system is proposed, and the imaging results are compared with those based on the traditional combined inertial guidance measurement method. Experimental results show that the sonar motion compensation method based on acoustic calibration system plays a crucial role in imaging, which proves that acoustic calibration method is an effective means to improve the resolution of sonar imaging.
Research on a kind of positioning anti-eccentric fixture for measuring thin wall gear with special big inner hole
Authors: He Min , Cai Dongyan , Gao Hongbo , Li Cui , Zhang Ke , Xing Rui
Published: March 2024

This paper mainly studies and designs the clamping tool which is installed in the measuring of big gears with big inner holes and thin walls. This paper analyzes the disadvantages of conventional clamping of large gears with special inner holes, and presents an example of the research and development of the Assembly of the mounting and positioning device of the special large inner hole gear based on the gear measuring instrument. At present, in the field of gear measurement, the measurement of large gears is always a technical problem. The technical ability of gear testing in our country is restricted by various factors. Most gear high-precision instruments and their accessories still depend on imports, which cannot be a good solution to the measurement of special gear installation and positioning problems from the economy and timeliness. Especially, large gears with large bores and thin walls face the problem of determining the position of the measuring device and the measured gears, that is, the measuring datum is difficult to determine [1]. This paper proposes how to use the existing gear measuring instrument to develop and use small accessories, so as to help the production enterprises and measuring institutions solve the problem of reference positioning in the actual production measurement process and determine the accuracy of special gear samples.
Evaluation of measurement uncertainty of drop hammer impact test for composite materials
Authors: Lei Li , Yao Zhang
Published: March 2024

Future aircraft structures are usually dominated by composites, and one of the key defects and forms of damage to composite structures is the impact damage caused by low-energy (especially low-speed) foreign matter. This kind of low-energy impact test is usually completed by the drop hammer testing machine, so accurately assessing the impact test of the falling hammer completed in accordance with the standard test method, and the reliability of the permissible value of the impact performance of the objective reaction composite is of great significance to the future aircraft structure design. Taking a standard composite test piece as an example, considering the key factors in the whole process of impact test, a mathematical model is constructed, and the measurement uncertainty of different configuration composite test pieces of different configurations is calculated according to the test data, which provides a basis for aircraft structural design.
Temperature error compensation method of fiber optic gyroscope based on deep learning
Authors: Wu Junjie , Wang Lei
Published: March 2024

This work provides an error compensation strategy based on deep learning to address the temperature error of a fiber optic gyroscope (FOG). The Attention structure was used to improve the Long Short-Term Memory Network (LSTM), and the improved network was utilized to establish the prediction and compensation model of FOG error. From the two perspectives of the learning ability of the neural network and the improvement of FOG performance, this paper selects three indicators: prediction accuracy, mean square error, and FOG bias stability to comprehensively evaluate the performance of the compensation model. Through comparison, the compensation effect is significantly enhanced.
Pipeline inertial measurement mileage correction method based on pipeline junction detection
Authors: Chen Xiaopan , Wang Ningbo , Chen Zhipeng , Yin Yu , Jia Peng , Yu Chuanyong , Wang Likui , Yu Jianwei , Lv Shiwang
Published: March 2024

A pipeline measurement robot(PMR) is an important tool for pipeline shape measurement and disease detection. Flexible pipelines in the horizontal plane inside dams are used for internal deformation monitoring, which is characterized by small caliber, no ground marking assistance, and higher accuracy requirements, so the accuracy of the data fusion algorithm needs to be improved. In this paper, we propose a pipeline inertial measurement odometry correction method based on pipeline junction detection, which establishes a reference model of pipeline junction locations, detects pipeline junction gap locations along the measurement route using k-mean clustering, corrects odometer data based on the difference between the detected and reference locations, fuses IMU and odometer data and evaluates the internal compliance accuracy. The proposed method is validated using the measured data of the internal pipeline of Tianchi Dam, and the results show that the method proposed in this paper reduces the root-mean-square error (RMSE) by about 46% compared with the results without detection correction and direct fusion. Therefore, the method has good results and practical applications.
Device for formaldehyde analysis in hydrogen energy
Authors: Tang Feng , Dang Xiaojing , Zhu Lei , Zhu Jin , Wang Jianjian , Sun Chao , Ren Li , Yu Guang , Fang Hua
Published: March 2024

In this paper, a calibration device for the analysis of formaldehyde in hydrogen energy is designed, and the standard formaldehyde gas of different concentrations is obtained by using the principle of osmotic tube, and the standard formaldehyde gas obtained by gas chromatograph analysis is combined. The results of the experiments show that the concentration of formaldehyde standard gas obtained by this calibration device has high accuracy and excellent stability. This overcomes the difficulty of formulating low-concentration standard gas due to the adsorption of formaldehyde gas, replaces the traditional method of formaldehyde standard gas preparation, and provides a quantitative basis for the calibration of formaldehyde analysis in hydrogen energy.
Investigate cosmic rays: Analysis of the air showers
Authors: Wen Chenglong , Li Yiqian , Feng Guanghai
Published: March 2024

In this lab report, the concept of cosmic rays and their components that can be detected on the earth’s surface is introduced. In this experiment, four CosmicWatch muon detectors were used to detect the components of cosmic rays. This report describes the setup of the experiment as well as the method and algorithms used to filter the true signals of cosmic rays out of the background radioactive noises. Some process of the algorithm is visualized using histograms. The rate of air showers was found to be 0.151 mHz ± 0.022 mHz for a separation of 6.73 cm ± 0.08 cm, and 0.096 mHz ± 0.015 mHz for a separation of 13.5 cm ± 0.1 cm. Other sources of uncertainties are also analyzed in this report.