bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical study on how advection delays and removes singularity formation in the Navier–Stokes equations
Authors: Ohkitani Koji 
Published: March 2024

Abstract
We numerically study a distorted version of the Euler and Navier–Stokes equations, which are obtained by depleting the advection term systematically. It is known that in the inviscid case some solutions blow up in finite time when advection is totally discarded, Constantin (1986 Commun. Math. Phys.
104 311–26). Taking a pair of orthogonally offset vortex tubes and the Taylor–Green vortex as initial data, we show the following. (1) Blowup persists even with viscosity when advection is discarded, and (2) for small viscosity, the time of blowup increases logarithmically as we reinstate advection using a continuous parameter, which would be consistent with the regularity of the Navier–Stokes equations. A tiny mismatch in the coefficient of the advection term, as minute as parts per trillion, throws the system out of compactness and leads to blowup.
Generating spokes in direct current magnetron sputtering discharges by an azimuthal strong-to-weak magnetic field strength transition
Authors: Rudolph Martin , Diyatmika Wahyu , Rattunde Oliver , Schuengel Edmund , Kalanov Dmitry , Patscheider Jörg , Anders André 
Published: March 2024

Abstract
Spokes are regions of enhanced ionization in magnetron sputtering discharges that are interesting because of their role for magnetron operation and their potential effect on deposition processes. Here, we show that spokes can intentionally be generated by introducing a strong-to-weak magnetic field strength transition along the racetrack. Spokes are triggered at the transition point from an accelerating electron drift when weakening the magnetic field strength. The spokes are then propagating against the electron drift into the strong magnetic field strength section of the racetrack. At the weak-to-strong magnetic field transition, we observe the inverse effect. The electron drift is decelerated at this point, creating a region of enhanced optical emission. From rectangular racetracks this is known as the cross-corner effect. Here, we show that a corner is not necessary for observing that effect. Pronounced spokes at low working gas pressure of 0.2 Pa exhibit a substructure that could be caused by the diocotron instability previously predicted by computer simulations.
Two-photon coherence in a DROP-FWM medium
Authors: Shukla Vinay , Ray Ayan 
Published: March 2024

Abstract
In this work, we report experimental studies on coherence in a medium exhibiting DROP (Double Resonance Optical Pumping)-FWM (Four Wave Mixing). Here 5S1/2(F) → 5P3/2(F/) → 5D (F//) two photon transition of hot 87Rb atoms is used. The 5S→5P connection is modified by introducing an additional beam phase coupled to the original beam linking F = 2 → F/ transition. The frequency of the additional beam is offset from that of the original beam by ≈ +10Γ (Γ is natural linewidth). Such a two-beam configuration in F→F/ manifold effectively satisfies conditions of Vee (V) linkage or degenerate two-level connection (DTLC), depending on the detuning of the 780nm laser. This transformation profoundly affects the behavior of the ensuing Ladder (Ξ) system. While the (I) Ξ +V condition is favorable for Electromagnetically Induced Transparency (EIT), the (ii) Ξ + DTLC brings in the effect of Electromagnetically Induced Absorption (EIA). The EIT-dominated situation is helpful for FWM to take place, and the EIA effect augments the stronger presence of DROP. This condition is verified by monitoring the blue fluorescence emanating from the 5D→6P3/2→5S1/2 decay route. The DROP effect follows the Amplified Spontaneous Emission (ASE) pattern in the media. The origin of blue photons is also due to FWM under EIT conditions. In the case of EIA, the dominant condition increment in blue fluorescence is due to increased stimulated emission. The blue photons mainly contributed by (i) FWM and (ii) increased participation of stimulated emission are directional in nature and phase coherent.
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.
Shear Alfvén waves within magnetic islands
Authors: Könies Axel , Cao Jinjia , Kleiber Ralf 
Published: March 2024

Abstract
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.
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

Abstract
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

Abstract
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.