bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computing first-passage times with the functional renormalisation group
Authors: Rigopoulos G. , Wilkins A. 
Published: April 2023

Abstract
We use Functional Renormalisation Group (FRG) techniques to analyse the behaviour of a spectator field, σ, during inflation that obeys an overdamped Langevin equation. We briefly review how a derivative expansion of the FRG can be used to obtain Effective Equations of Motion (EEOM) for the one- and two-point function and derive the EEOM for the three-point function. We show how to compute quantities like the amplitude of the power spectrum and the spectral tilt from the FRG. We do this explicitly for a potential with multiple barriers and show that in general many different potentials will give identical predictions for the spectral tilt suggesting that observations are agnostic to localised features in the potential. Finally we use the EEOM to compute first-passage time (FPT) quantities for the spectator field. The EEOM for the one- and two-point function are enough to accurately predict the average time taken 〈𝒩〉 to travel between two field values with a barrier in between and the variation in that time δ𝒩
2. It can also accurately resolve the full PDF for time taken ρ(𝒩), predicting the correct exponential tail. This suggests that an extension of this analysis to the inflaton can correctly capture the exponential tail that is expected in models producing Primordial Black Holes.
Study on the filters of atmospheric contamination in ground based CMB observation
Authors: Wu Yi-Wen , Li Si-Yu , Liu Yang , Zhang Zirui , Liu Hao , Li Hong 
Published: April 2023

Abstract
The atmosphere is one of the most significant sources of contamination in ground-based Cosmic Microwave Background (CMB) observations. Atmospheric emission increases the additional optical loading on the detector, resulting in higher photon noise. Additionally, atmospheric fluctuations cause spatial and temporal variations in detected power, leading to additional correlations between detectors and in the time stream of individual detectors. This correlated signal, known as the 1/f noise, can interfere with the detection of CMB signals, severely hindering the probing of CMB signals.
In this paper, we study three types of filters: the polynomial fitting, high-pass filter, and Wiener filter. We evaluate the filters based on their ability to remove atmospheric noise, and investigate the impact of the filters on the data analytic process through end-to-end simulations of CMB experiments. We track their performance by analyzing the response of different components of the data, including both signal and noise. In the time domain, the high-pass filter is found to have the smallest root mean square error and achieves high filtering efficiency, followed by the Wiener filter and polynomial fitting. We adopt two map making methods, namely naive map making and Minimum Variance map making, to study the effects of filters on the map level. The results show that the polynomial fitting gives a high noise residual at low frequency, resulting in significant leakage to small scales in the map domain, while the high-pass and Wiener filters do not have significant leakage.
We compare the filters' effects on the power spectra domain by estimating the angular power spectra of residual noise and input signal, and estimating the standard deviation of the signal recovered power spectra. At low noise level, the three filters give almost comparable standard deviations on medium and small scales. However, at high noise level, the standard deviation of the polynomial fitting is significantly larger. These studies can be used for reducing atmospheric noise in future ground-based CMB data processing.
Monopole effects and high-spin levels in neutron-rich 132Te*
Authors: Wang Han-Kui , Jalili Amir , Li Ge-Xing , Wang You-Bao 
Published: April 2023

Abstract
The neutron-rich nuclei near doubly magic

Sn have attracted considerable interest in both nuclear physics and nuclear astrophysics. For the particle-hole nuclei in this region, the low-lying and high core excitations have been well described by shell model calculations using the extended pairing plus multipole-multipole force model. However, there is a significant difference between experiment and theory in the high-spin level 17

of

Te. We intend to illustrate this difference through monopole interactions. For this purpose, the monopole corrections between

and

are investigated in

Te,

Sb, and

Sn. Some theoretical levels are connected to the (17

) state of

Te with the monopole correction (Mc) of

and the quadruple-quadruple force between the proton and neutron, i.e., levels 3

(8

) in

Sn, level 14

in

Te, and level 23/2

in

Sb. Their observations at lower energies can confirm the datum of level (17

) in

Te with an illustration of monopole effects and quadruple-quadruple force.
Superradiance of massive scalar particles around rotating regular black holes*
Authors: Yang Hao , Miao Yan-Gang 
Published: April 2023

Abstract
Regular black holes, as part of an important attempt to eliminate the singularities in general relativity, have been of wide concern. Because the superradiance associated with rotating regular black holes plays an indispensable role in black hole physics, we calculate the superradiance related effects, i.e., the superradiance instability and the energy extraction efficiency, for a scalar particle with a small mass around a rotating regular black hole, where the rotating regular black hole is constructed by the modified Newman-Janis algorithm. We analytically give the eigenfrequency associated with instability and the amplification factor associated with energy extraction. For two specific models, i.e., the rotating Hayward and Bardeen black holes, we investigate how their regularization parameters affect the growth of instability and the efficiency of energy extraction from the two rotating regular black holes. We find that the regularization parameters give rise to different modes of the superradiance instability and the energy extraction when the rotation parameters vary. There are two modes for the growth of superradiance instability and four modes for the energy extraction. Our results show the diversity of superradiance in the competition between the regularization parameter and the rotation parameter for rotating regular black holes.
The effect of plasma beta on error-field penetration in radio-frequency wave heated plasmas in EAST
Authors: Ye Cheng , Sun You-Wen , Wang Hui-Hui , Liu Yue-Qiang , Shi Tong-Hui , Zang Qing , Jia Tian-Qi , Ma Qun , Gu Shuai , Chu Nan , He Kai-Yang , Jia Man-Ni , Wu Xue-Min , Xie Peng-Cheng , Sheng Hui , Yang Hua , Huang Lian-Sheng , Shen Biao , Li Miao-Hui , Qian Jin-Ping 
Published: April 2023

Abstract
The plasma-beta effect on the n = 1 resonant magnetic perturbation (RMP) field penetration in purely radio-frequency (RF) wave heated discharges has been investigated in EAST. The experimental results show that the dependence of the threshold RMP coil current for field penetration,

I

RMP,th

, on the total absorbed power P
tot scales as approximately

I

RMP,th

∝

P

tot

0.30

, indicating that the error-field tolerance is improved with increasing RF power. This is benefited by the increased electron perpendicular flow dominated by a counter-current electron diamagnetic flow with increasing RF power. However, theoretical scaling in cylindrical geometry overestimates the power index. Assuming an additional term

β

N

α

β

N

for the normalized beta in the scaling, it is shown that the fitted

α

β

N

from the experimental observation is around −1, indicating a degradation effect of plasma beta. To clarify the underlying physics of the plasma-beta effect that was not included in the theoretical scaling in cylindrical geometry, the MARS-Q code with full toroidal geometry is employed for simulation of nonlinear field penetration (Liu et al 2013 Phys. Plasmas
20 042503). The MARS-Q simulation results reproduce the

β

N

dependence well, and hence the P
tot scaling of the threshold current in experimental observations. The main reason for this is that the net total torque, which is mainly contributed by the neoclassical toroidal viscosity (NTV), increases with increasing plasma

β

N

. The results demonstrate that the nonlinear toroidal coupling effect via NTV torque plays an important role in determining field penetration, even in cases with relatively low

β

N

∈
[
0.3
,
0.6
]

, which is far less than the no-wall beta limit.
Vibration and Noise Analysis for an Interior Permanent Magnet Synchronous Motor with Improved Structure
Authors: Wu Qi , Zhang Chi , Qiu Yiming , Zhu Falong , Kong Siqi 
Published: April 2023

Abstract
An interior permanent magnet synchronous motor with a skew-slot and improved rotor structure is proposed in the paper. The source and main order of the noise of the motor are analyzed. The electromagnetic characteristics of the motor before and after utilizing the new structure are analyzed and compared. In addition, the vibration and noise tests of the prototype are done. The results show that the main source of noise of the 8-pole 48-slot motor is the 0-order electromagnetic force, and the motor with low vibration noise can be achieved with the proposed structure in this paper.
Study on output power oscillation characteristics of a doubly-fed unit when operating parameters change
Authors: Cao Na , Su Yani 
Published: April 2023

Abstract
To study the power propagation of wind turbines in the doubly-fed unit and the output power oscillation characteristics of the doubly-fed unit after transformation. Firstly, the damping of the doubly-fed unit was changed when the wind velocity was lower than the rated wind velocity and higher than the rated wind velocity respectively, considering the tower shadow effect and wind shear, and the oscillation characteristics of the output power of the doubly-fed unit were studied. Finally, modeling and simulation were carried out on PSCAD/EMTDC platform. Through the analysis of power fluctuation and spectrum change of the unit, it is concluded that when the wind turbine input wind velocity is greater than or less than the rated wind velocity of the unit, the wind turbine power through the doubly-fed unit has different effects on the output power oscillation characteristics of the unit. The output power oscillation characteristics of doubly-fed units are different with and without the tower shadow effect and wind shear. When the doubly-fed unit is negatively damped and the tower shadow effect and wind shear are taken into account, the output power of the unit contains both low-frequency and sub-synchronous oscillations, and the magnitude and frequency of the oscillation components are related to the control parameters of the unit.
Structural Design of Small-size At-bit Azimuthal Gamma Geosteering Tool Based on Axiomatic Design
Authors: Xi Wenkui , Sun Dongxin , Jia Chao 
Published: April 2023

Abstract
To revitalize old wells and reduce costs, sidetracking has become an effective technical means to excavate the remaining oil reservoirs of old wells. The small-size at-bit azimuthal gamma geosteering tool designed in this paper is used for sidetracking. First, according to axiomatic design, we determine each functional module. Second, according to the function module, we design the structure of the geosteering tool. Finally, we conduct finite element strength analysis on the geosteering tool. The results are as follows: the geosteering tool realizes the structural design under limited space; its maximum stress is lower than the yield strength of the non-magnetic drill collar under the actual working conditions. The structure meets the strength requirements. The research method based on the axiomatic design proposed in this paper makes a beneficial exploration of the structural design of geosteering tools in the petroleum industry.
Analysis of Motion Characteristics of General Mobile Buoy
Authors: Yang Tianxiang , Song Wushuai , Lei Xiaobo 
Published: April 2023

Abstract
This thesis proposes a new type of general mobile buoy used in the South China Sea. The free motion of the buoy in still water is analyzed theoretically, and the theoretical estimate of the buoy natural period is obtained. A three-dimensional model is established to simulate the buoy, and the buoy motion amplitude response Rao curve is obtained. The results show that it can meet the requirement that the motion angle is always less than 15° in the range of 3~20 s in the wave period under the level 2 sea state.
Structural Design and Analysis of New Electromagnetic Actuator
Authors: Zhang Qingwei , Sun Mingwei , Zhu Liangming 
Published: April 2023

Abstract
active vibration control can effectively restrain low-frequency line spectrum vibration. As an output end of control force, an electromagnetic actuator has the problem of low precision of output force and zero drift. Therefore, a new type of electromagnetic actuator is designed in this paper. The parametric modeling of the magnetic circuit structure is carried out, and it is verified that the magnetostatic attraction in direct current (DC) magnetic circuit is zero. Then, a calculation method of electromagnetic force in alternating current/direct current (AC/DC) magnetic circuit is deduced. The mechanical-electrical-magnetic-thermal multi-physical coupling field simulation of the electromagnetic actuator is carried out, which shows that the improved magnetic circuit structure effectively solves the zero drift, improves the precision of output force of the actuator, and allows the actuator to have lower electromagnetic heat output and electromagnetic loss.
Research on Transformer Fault Based on Grey System Theory
Authors: Zhang Ni 
Published: April 2023

Abstract
A transformer is a kind of power distribution equipment, which plays a vital role in the power system. The concentration of dissolved gas in the oil can predict the fault. Because the prediction accuracy of the classical GM (1, 1) model is not high, a new optimization formula is given according to the reconstruction of its original value and background value. Through the experimental data, it is proved that compared with the original GM (1, 1) model, the average relative error and error fluctuation of the optimized GM (1, 1) model is significantly reduced, and the accuracy is greatly improved.
Research On The Daily Electricity Forecast Model Based On LightGBM
Authors: Wu Shanshan , Zheng Haifeng , Chen Chi , Zhang Kun 
Published: April 2023

Abstract
Short-term electricity demand forecast is of great significance for guiding the Power Grid Company production operation, but the existing forecast mainly concentrated on load forecast, and most of them only use meteorological and date factors as input features, ignoring the economic factors as a basis to support the growth of electricity, also doesn’t take into account the influence of recent significant events. To improve the accuracy and rationality of short-term electricity demand forecast, based on the Light Gradient Boosting Machine (LightGBM) model, in addition to the common meteorological and date factors, all kinds of economic and significant events are introduced into the model to forecast the daily electricity in this paper. The results show that economic and significant events provide useful information, making our model more accurate than previous short-term electricity demand forecasts. Moreover, due to the adoption of machine learning algorithms, our model is more stable and accurate than traditional measurement models with the same factors.
Parametric study on circularly abrupt magnetic flux density changes of electromagnetic energy harvesters via simulation
Authors: Peng Yan , Xu Wanqing , Gong Ying , Jiang Xiaomeng , Li Zhongjie 
Published: April 2023

Abstract
Energy harvesting has long been widely studied. In this paper, we systematically investigate the output performances of rotating electromagnetic energy harvesters (EMEHs) with different magnetic pole pairs and coil parameters via simulations. Different numbers of magnetic pole pairs obviously affect the abrupt magnetic flux density (MFD) change and the further output voltage. Hence, we set up finite element (FEM) models of proposed harvesters to compare the output voltage under different numbers of the magnetic pole pairs p in the same coil parameters conditions. Subsequently, to further study how the coil parameters affect the voltage and power of EMEHs, we conduct simulations using different coil heights h and wire diameters d with the same magnet array. The results of the magnet simulation indicate that in a certain volume, EMEHs yield a maximal output voltage of about 12.2 V in the case of p=4. In the best contrast, EMEHs produce a peak output power of about 26.36 W under the excitation of 180 rad/s. This study will be of great significance in improving power in the field of harvesting electromagnetic energy.
Design of analog front-end readout circuit for capacitive silicon micro gyroscope
Authors: Zhou XiangQi , Duan QuanZhen 
Published: April 2023

Abstract
To design a high-performance analog front-end readout circuit for capacitive silicon micromachined gyroscope, this paper presents electrical modeling of the silicon micromachined gyroscope according to its working characteristics, proposes to construct the amplitude and frequency range of the silicon micromachined gyroscope signal in the form of a capacitor array, and designs the capacitance readout circuit of the gyroscope based on this model. Based on the SMIC 0.18 um CMOS process, the electrical model and its capacitance readout circuit are designed and simulated in this paper. The results indicate that the capacitance readout circuit can accurately detect the equivalent variable capacitance signal of the gyroscope electrical model and transform it linearly into a voltage signal. The equivalent output noise of the overall analog front-end readout circuit is 80.11 nV/√Hz@6.4kHZ. The system resolution can reach 0.29 aF. As a result, the silicon micro gyroscope analog front-end circuit has a wide range of capacitive applications, high linearity, low noise, and broad market and application prospects. Hence, this topic is of great scientific significance.
Error Analysis for Shipborne-based-based Single Band LiDAR Point Cloud Data
Authors: Zhou Guoqing , Sun Zhibiao 
Published: April 2023

Abstract
A new measuring technique called a ship-based single band LiDAR system is utilized to swiftly capture underwater terrain to employ dense and precise point cloud data on a vast region for bathymetry. The accuracy of point clouds is strongly impacted by the ease with which numerous error sources might affect shipborne single-band lidar measurement systems. Shipborne-based single-band LiDAR point cloud errors are mostly caused by GPS, attitude angle, range, and integration errors. This research explores and examines the impact of the scanning angle and attitude angle on bathymetry because they can fluctuate significantly throughout the actual measurement process. The point cloud errors resulting from numerous sets of scanning angle and attitude-angle data sets are calculated. The linear relationship and positioning accuracy between the three are intuitively depicted by comparable curves, presuming that other error causes are quantifiable. Analysis reveals that the error will also rise as the scanning angle increases.
Additionally, the roll angle inaccuracy in the attitude angle has a minimal impact on the accuracy of the plane but a substantial impact on the accuracy of the elevation. Elevation error significantly impacts plane positioning accuracy but less on elevation accuracy. Positioning is only minimally affected by yaw angle inaccuracy.
A Grid Fault Diagnosis Method Based on Stacking Algorithm
Authors: Du Mingxuan , Wang Zirui , Zhang Ziqi , Zhang Xu 
Published: April 2023

Abstract
Power grid dispatching is developing towards digitalization and intellectualization. Using the data generated in power grid operations to diagnose faults through artificial intelligence technology directly has become the development trend of the power grid. However, traditional machine learning algorithms often need help to achieve good diagnostic results in practical applications. Therefore, a fusion model based on the Stacking integration algorithm is proposed, and four commonly used machine learning algorithms are selected for fusion. Furthermore, the model is trained using the fault alarm information features extracted from the SCADA system. Then, by comparing and analyzing the diagnostic effect of four single algorithms and the Stacking model for various fault types, the conclusion that the Stacking model has a better overall effect than other algorithms in the diagnosis of various fault types is obtained, and the advantage of the stacking fusion algorithm is proved.
Research on the Relationship between Scatter Ray and Image Signal to Noise Ratio in CR Detection
Authors: Chen Le 
Published: April 2023

Abstract
The signal-to-noise ratio is the most important indicator for the quality evaluation of digital radiographic testing images, and scattering is the most common phenomenon in the radiographic testing process. Is the signal-to-noise ratio affected by scattered rays? How to evaluate the influence of scattered rays in digital radiographic testing? These questions are rarely mentioned in studies in the past. And this is a problem that needs to be clarified in the research of digital radiographic testing. This article answers the above question based on the experimental data detected by CR technology. The scattering ratio changing with different transillumination arrangements does not affect the signal-to-noise ratio of the CR image. Therefore, it is believed that the change in the scattering ratio does not basically affect the digital image signal-to-noise ratio. This leads to another problem. The signal-to-noise ratio cannot fully evaluate all the factors that affect the detection of defects. The influence of scattered rays on the detection of defects must be evaluated by another index-contrast sensitivity.
Research on High Harmonic Amplification of 10kV Series Static Var Generator
Authors: Li Guoxin , Qi Biao , Ding Hao , Pan Shiyao , Yu Zhiyuan 
Published: April 2023

Abstract
With the continuous development of power electronic devices and science and technology, cables and rectifiers, inverters, DC transmission equipment, and other nonlinear loads have been widely used in power systems. However, this causes harmonic pollution and large capacitive reactive power, which can affect the safe and stable operation of the power system. Based on the analysis of the reasons for the use of static var generator in the power grid and the existing conditions of even harmonic, the impedance analysis method was used to analyze the abnormal noise event of a transformer in a substation. Firstly, the equivalent impedance model diagram is drawn by the equivalent circuit method, and the equivalent impedance value of the system is calculated. A number of harmonic amplifications and the positions of the resonance point are calculated by MATLAB software. Secondly, the correctness of the above theoretical analysis is verified by field test and simulation model built in ETAP software. Finally, because of the abnormal noise of the transformer in a substation caused by harmonic amplification, three harmonic suppression measures are given.