bluuebunny/crossref_metadata_2025 huggingface dataset:
Model-based spectral causality of cardiovascular variability interactions during head-down tilt
Authors: Porta Alberto , Cairo Beatrice , Bari Vlasta , Gelpi Francesca , De Maria Beatrice , Colombo Riccardo
Published: April 2023

Objective. Cardiovascular control mechanisms are commonly studied during baroreceptor unloading induced by head-up tilt. Conversely, the effect of a baroreceptor loading induced by head-down tilt (HDT) is less studied especially when the stimulus is of moderate intensity and using model-based spectral causality markers. Thus, this study computes model-based causality markers in the frequency domain derived via causal squared coherence and Geweke spectral causality approach from heart period (HP) and systolic arterial pressure (SAP) variability series. Approach. We recorded HP and SAP variability series in 12 healthy men (age: from 41 to 71 yrs, median: 57 yrs) during HDT at −25°. The approaches are compared by considering two different bivariate model structures, namely the autoregressive and dynamic adjustment models. Markers are computed in traditional frequency bands utilized in cardiovascular control analysis, namely the low frequency (LF, from 0.04 to 0.15 Hz) and high frequency (HF, from 0.15 to 0.4 Hz) bands. Main results. We found that: (i) the two spectral causality metrics are deterministically related but spectral causality markers exhibit different discriminative ability; (ii) HDT reduces the involvement of the baroreflex in regulating HP-SAP variability interactions in the LF band, while leaving unmodified the action of mechanical feedforward mechanisms in both LF and HF bands; (iii) this conclusion does not depend on the model structure. Significance. We conclude that HDT can be utilized to reduce the impact of baroreflex and to study the contribution of regulatory mechanisms different from baroreflex to the complexity of cardiovascular control in humans.
On gyrokinetic-fluid model for electromagnetic fluctuations in magnetized plasmas
Authors: Chen Haotian , Chen Liu , Viezzer Eleonora , Garcia-Munoz Manuel , Li Jiquan
Published: April 2023

The hybrid gyrokinetic-fluid model (termed as GK-E&B) for simulating low-frequency electromagnetic fluctuations (Chen et al 2021 Sci. China Phys. Mech. Astron.
64 245211) is revisited, with emphasis on the self-consistency between the gyrokinetic ordering and magnetohydrodynamic equations. It is found that, contrary to the previous results, the parallel electric field equation is a Poisson-like equation in general for the typical electromagnetic microturbulence with wavelengths of the order of the thermal ion Larmor radius. Although the GK-E&B suffers no conventional Ampère cancellation issue since it employs the gauge-free gyrokinetic equation formulated in terms of electromagnetic fields, the balance between parallel electric field and electron pressure gradient must be accurately captured. Furthermore, the ion parallel current correction is shown to be essential to the ion sound wave branch in the GK-E&B model, and the compressional component of magnetic field fluctuation should be computed from the perpendicular component of Ampère’s law, instead of the Faraday’s law.
Interfacial debonding detection of steel beams reinforced by CFRP plates based on percussion method
Authors: Wu Wenbin , Jiang Jian , Chen Yixuan , Li Heng
Published: April 2023

Steel structure reinforced engineering makes extensive use of carbon fiber reinforced plastic (CFRP) plates. Although it happens frequently, the interfacial debonding of CFRP plate-reinforced steel beams has been the main cause of failure in flexural strengthened steel beams, which results in the brittle failure of steel structures. This paper proposes a novel percussion method to locate and quantify the debonding area based on the Welch power spectrum density (PSD) estimate, mel frequency cepstral coefficient (MFCC), and convolutional neural network (CNN). According to our knowledge, this is the first attempt to use the percussion method to identify and measure the debonding defects of steel beams strengthened by CFRP plates. Additionally, this experiment takes into account how percussion instruments affect localization and quantification. To begin with, the debonding location is qualitatively detected using the Welch PSD estimate method. The presented percussion method can successfully and accurately detect the interfacial debonding of CFRP plate-reinforced steel beams, according to repeated results. Subsequently, a novel CNN model is constructed to classify the various debonding areas based on the MFCC feature. In the end, the experimental findings show that the localization and quantification of the hammer types vary only slightly. Overall, the percussion-based approach can offer a fresh line of inquiry into the debonding problem on steel beams reinforced with CFRP plates.
Manipulation of elastic wave by reconfigurable elastic topological waveguide
Authors: Gu Shuai , Zhang Min-yi , Ge Yong , Jia Ding , Yuan Shou-qi , Sun Hong-xiang
Published: April 2023

We report a numerical study of a reconfigurable topological waveguide based on honeycomb-lattice elastic phononic crystals (EPCs) which consist of two kinds of cavities filled with water. We can realize the EPCs with different symmetries by adjusting the water depth of the cavities, and obtain a Dirac cone for the EPCs composed of the cavities with the same water depth, in which the Dirac frequency can be modulated by adjusting the water depth. When the water depths of the cavities are different, the inversion symmetry of the EPC is broken, destroying the two-fold degeneracy of the Dirac point, and opening an omnidirectional bandgap. Based on EPC-I and EPC-II with opposite valley Hall phases, we design a valley topological waveguide of elastic wave, and obtain valley edge states in the domain wall (DW). Importantly, by adjusting the water depths, we can achieve the conversion between EPC-I and EPC-II, and realize arbitrary DWs for the propagations of elastic waves in the topological waveguide. Finally, we discuss an interesting application of a path-selective waveguide based on a linear interference mechanism. The designed reconfigurable topological waveguide provides an effective method to manipulate valley topological transports of elastic waves, and a theoretical basis for designing advanced topological devices.
High-field critical current density enhancement in GdBCO coated conductors by cooperative defects
Authors: Huang Daxing , Chen Di , Dong Hao , Wang Kai , Chu Wei-Kan , Wang Tongxin , Wang Meiqi , Zhu Kaigui , Gu Hongwei , Ren Zhifeng , Ding Fazhu
Published: April 2023

Irradiation can precisely control defects in, and improve the superconducting properties of, REBa2Cu3O7−δ
(REBCO, RE: rare earth) coated conductors (CCs). Here we report an effective approach for enhancing the in-field performance of GdBCO CCs. The critical current density (J
c) of GdBCO films was significantly improved through cooperative defects created by co-irradiation with O ions and protons, especially at low temperatures and high magnetic fields. Surprisingly, the in-field J
c of commercial CCs can be nearly doubled. The cooperative irradiation-induced defects are uniformly distributed throughout the GdBCO layer, which promotes the overall performance of the CC. Moreover, the dimensions of these irradiation-induced defects closely match the coherence length of REBCO. This simple and efficient method is a practical post-production solution to improve the in-field performance of commercial REBCO CCs.
Computing first-passage times with the functional renormalisation group
Authors: Rigopoulos G. , Wilkins A.
Published: April 2023

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
A Modular Hardware Design of an Intelligent Distributed Feeder Terminal Unit
Authors: Gao Yuan , Hu Yuanyuan , Wang Yonggui , Xing Yulong , Huang Luchao
Published: April 2023

The development of a new power system is proposing new requirements for the function of the feeder terminal unit (FTU), which is the core equipment of the distribution automation system. At the same time, the improvement of FTU intelligence brings a new solution to the problem of line loss calculation. Aiming at the problems of complex structure and low measurement accuracy of current FTU, a hardware scheme combining ADC sampling chip and high-performance MCU is proposed in this paper to realize the integrated application of energy measurement function. Moreover, it is equipped with a line loss calculation module to achieve high precision line loss calculation when the metering chip cannot meet the precision requirements. At the same time, the modular design effectively improves the operation reliability and function expansion of the terminal.
Wave Energy Output Power Design Based on Machine Learning
Authors: Shen Yi , Wu Yihang , Zhi Weimei
Published: April 2023

In recent years, with the excessive use of non-renewable energy sources, energy shortage has become a major problem for countries around the world, and the development of marine renewable energy has become urgent. As an important renewable energy source in the future, wave energy is one of our important research objects. This paper completes the design of the maximum wave energy output power and establishes the motion model of the float and the oscillator and the optimization model of the maximum average output power in the wave energy devices. This work helps people use wave energy reasonably and provides theoretical support for designing a new generation of wave energy equipment. In this paper, the motions of the float and oscillator in this wave energy device are modeled by Newton’s theorem and Lagrange’s equation, and then the displacement and velocity of the float and oscillator under the pendulum motion at different moments are solved by using the fourth-order Runge-Kutta method. The maximum average output power of the PTO system is solved by building an optimization model with a constant damping coefficient and a non-damping coefficient, followed by the traversal method and genetic algorithm.
Conditional GAN Empowered Channel Estimation and Pilot Design for Reconfigurable Intelligent Surfaces assisted Symbiotic Radio System
Authors: Zhou Yuan , Cao Kaitian , Cai Lianning , Feng Yu
Published: April 2023

Reconfigurable intelligent surfaces (RISs) has been proven to be a promising technology to improve the performance of symbiotic radio (SR) systems. To take full advantage of RIS-assisted communications, it is crucial to obtain accurate channel state information for high-gain beamforming. However, the statistical distribution of the cascaded channels in a RIS-assisted SR system is complex, which gives rise to a huge challenge for channel estimation tasks. To address this issue, we propose a joint optimization method of channel estimation for the RIS-assisted SR system with pilot design based on deep learning (JPCGAN) in this paper. The proposed scheme uses a fully connected network for pilot design and develops a conditional generative adversarial network (cGAN) to predict the true channels. cGAN is especially helpful in trainning the network model properly and enhance the system’s robustness with an adaptive loss function. It can be obtained by simulation that compared with current methods, the JPCGAN scheme proposed in this paper can significantly improve the accuracy of channel estimation under low signal-to-noise radios.
Signal recognition of a Fiber Bragg grating-based orbit monitoring system based on the convolutional neural network
Authors: Pan Jinjun , Hu Linfeng , Xiong Yihao
Published: April 2023

In order to adapt to the diversification of train and railway technology by combining the needs of rail transit and the advantages of a grating array fiber sensing system, this paper discusses an intelligent rail transit safety monitoring system based on grating array fiber. The vibration signal sensing system based on grating array fiber can accurately locate the time and place of vibration occurrence in real time by analyzing the train vibration signal obtained by the sensing system. The possible abnormal conditions and safety risks of the train or track can be judged. At the same time, in view of the problems of low processing efficiency, low accuracy, and high possibility of omission caused by resolving and processing vibration signals only by human resources or a single feature extraction technology, this paper introduces a data analysis and processing method in a deep learning framework to analyze the collected signal directly. Deep learning is conducted through the convolutional neural network to distinguish the normal vehicle crossing data from the abnormal data, and then the abnormal data are analyzed separately. The exception category is used according to the exception data upper opportunity.
Intelligent identification of radar active jamming type based on multi-domain information fusion
Authors: Cao Fei , Gao Zejun , He Chuan , Feng Xiaowei , Xu Jianfeng , Xue Chunling , Qin Jianqiang
Published: April 2023

Feature fusion is beneficial to improving the recognition rate of radar active jamming types, which usually costs a lot of computation and network complexity, however. Contrapose the disadvantage of low computational power and resource allocation of missile-borne radar, this paper introduces data enhancement theory into the feature fusion method and proposes an intelligent identification model of radar active jamming type based on multi-domain information fusion. The model first analyzes the time-frequency domain features of the signal and one-dimensional features such as its real part, imaginary part, frequency spectrum, and power spectrum, and then uses the Cutout&Patchup algorithm to fuse the one-dimensional and two-dimensional features into a new multi-domain information fusion matrix as the input of the recognition network. The simulation results show that this method greatly improves the recognition accuracy of active jamming types. Under the WideResNet28_2 classifier, the classification accuracy of active interference type reaches 88.06%, which is 0.79% higher than that before fusion.
Relay Protection Setting Calculation of Power Transformer Based on ETAP
Authors: Wei Jinguo
Published: April 2023

The conventional relay protection setting calculation method considers the internal interference of the transformer and obtains the setting value quickly, which leads to large harmonic interference of the transformer and affects the secondary setting calculation results. Therefore, the setting calculation method of the power transformer relay protection based on the Electrical Transient Analysis Program (ETAP) is designed. The harmonic transfer characteristics of the power transformer are extracted, and the harmonic interference of the power transformer is proposed. Then the ETAP software is adopted to establish the calculation principle of the power transformer relay protection setting and improve the calculation accuracy of the secondary setting. Through comparative experiments, it is verified that the second fixed value of the algorithm is close to the actual fixed value and can be applied to real life.
Economics and optics influence funding for ecological restoration in a nation-wide program
Authors: Engert Jayden E , Laurance Susan G W
Published: April 2023

Australia is a world leader in habitat loss and species extinction, and for many species, ecological restoration will be necessary for continued persistence. Between 2014 and 2018, the Australian federal government allocated a substantial portion of funding for threatened species recovery to a nation-wide ecological restoration program called ‘20 Million Trees Land-care Program’, which included a competitive grant round. By comparing successful and unsuccessful grant applications, we were able to identify factors associated with restoration funding allocation. We then assessed the Program’s ability to provide benefits to threatened species by analyzing the overlap between restoration projects and threatened species habitat. We found that funding allocation under the 20 Million Trees Program was primarily driven by ‘value for money’ factors, specifically ‘cost per tree’ and number of trees planted. Additionally, projects were more likely to be funded if they mentioned threatened species in the description, but less likely to be funded if they actually overlapped with areas of high threatened species richness. Of the 1960 threatened species assessed, we found that only 9 received funding for restoration projects covering more than 1% of their range. Conversely, we found that utilizing alternative project selection schemes, such as alternative ‘value for money’ metrics or spatial planning methods, could have delivered better outcomes for some of the threatened species most impacted by habitat loss. Our results show that inopportune selection criteria for awarding of funding for ecological restoration can significantly reduce the benefits delivered by programs.
Ag, Au and ZrO2@reduced graphene oxide nanocomposites; Pd free catalysis of suzuki-miyaura coupling reactions
Authors: Ameen Iqra , Iqbal Sadia , Hussain Murid , Alothman Asma A , Algahtani Huda A , Mushab Mohammed Sheikh Saleh , Iqbal Amjad , Perveen Shehla , Musaddiq Sara
Published: April 2023

Suzuki coupling is a widely used, well-studied and versatile method in synthetic chemistry for development of C–C bonds where palladium-based catalysts have been used extensively in the reaction to date. We report a Suzuki-cross-coupling reaction for C–C bonds formation between aryl halides and phenylboronic acid by using Metal/metal oxide@Reduced graphene oxide nanocomposites being efficient, simple and cost-effective. In this work, plant mediated synthesis of silver, gold and zirconia nanoparticles doped Reduced Graphene Oxide nanocomposites is reported where 30 mg of each of the catalysts resulted in C-C bond formation achieving percentage yield comparable to palladium-based catalyst used as standard in series of reactions, attaining highest yield with silver based catalyst. The catalysts demonstrated high catalytic activity over three cycles of recycling with no loss. Bromoaryl and phenylboronic acid are coupled together by the increased surface area of the reduced graphene oxide substrate, which also exhibits enhanced reactivity toward other chemical reactions. XRD, FTIR and UV–vis analyses were used to describe the synthesized catalyst. Using the devised technique, various substituted aryl halides have been used successfully with modest to high yields of the desired biphenyls.
177Lu SPECT imaging in the presence of 90Y: does 90Y degrade image quantification? a simulation study
Authors: Miller Cassandra , Uribe Carlos , Hou Xinchi , Rahmim Arman , Celler Anna
Published: April 2023

This work aims to investigate the accuracy of quantitative SPECT imaging of 177Lu in the presence of 90Y, which occurs in dual-isotope radiopharmaceutical therapy (RPT) involving both isotopes. We used the GATE Monte Carlo simulation toolkit to conduct a phantom study, simulating spheres filled with 177Lu and 90Y placed in a cylindrical water phantom that was also filled with activity of both radionuclides. We simulated multiple phantom configurations and activity combinations by varying the location of the spheres, the concentrations of 177Lu and 90Y in the spheres, and the amount of background activity. We investigated two different scatter window widths to be used with triple energy window (TEW) scatter correction. We also created multiple realizations of each configuration to improve our assessment, leading to a total of 540 simulations. Each configuration was imaged using a simulated Siemens SPECT camera. The projections were reconstructed using the standard 3D OSEM algorithm, and errors associated with 177Lu activity quantification and contrast-to-noise ratios (CNRs) were determined. In all configurations, the quantification error was within ± 6% of the no-90Y case, and we found that quantitative accuracy may slightly improve when 90Y is present because of reduction of errors associated with TEW scatter correction. The CNRs were not significantly impacted by the presence of 90Y, but they were increased when a wider scatter window width was used for TEW scatter correction. The width of the scatter windows made a small but statistically significant difference of 1%–2% on the recovered 177Lu activity. Based on these results, we can conclude that activity quantification of 177Lu and lesion detectability is not degraded by the presence of 90Y.
Six-qubit silicon quantum processor sets a record
Authors: Boerkamp Martijn
Published: April 2023

Researchers in the Netherlands have placed a record number of silicon spin qubits on a chip and showed that they could operate the new six-qubit chip with high fidelity.
Laughing gas could point to alien life on Earth-like planets
Authors: Jarman Sam
Published: April 2023

The presence of nitrous oxide in the atmospheres of Earth-like exoplanets could be a signature of the presence of extraterrestrial life.
Astronomer barred for misconduct
Authors: Banks Michael
Published: April 2023

Tim de Zeeuw from Leiden University has been banned from the institution’s campus and cannot supervise PhD students but keeps professorial title, as Michael Banks reports.
New Oak Ridge centre to boost US isotope production
Authors: Gwynne Peter
Published: April 2023

Construction has begun on a new facility in the US that will produce a wide range of isotopes including radioisotopes for medical applications.
ESO marks 60th anniversary with release of dramatic star factory image
Authors: Freeman Tami
Published: April 2023

The European Southern Observatory has released a spectacular new image of the Cone Nebula to mark its 60th anniversary.
New ground station to support NASA lunar missions
Authors: Makoni Munyaradzi
Published: April 2023

Officials gathered to break ground on a new facility in South Africa that will support human spaceflight missions to the Moon and possibly Mars.
The joy of solar panels
Authors: McKenzie James
Published: April 2023

Could a new solar cell with a record-breaking efficiency of 30.1% transform the commercial potential of solar panels, asks James Mckenzie.
It’s good to talk
Authors: Budden John
Published: April 2023

A response to the feature article by Imperial College undergraduate Clara Aldegunde entitled “Knitting space–time out of quantum entanglement”
Take a tour of the frontiers of printing
Authors: McEntee Joe
Published: April 2023

If you thought innovation in the world of printing was a thing of the past, think again. Joe McEntee goes for a multidisciplinary stroll around the UK’s Centre for Print Research.
Testing the limits of science
Authors: Johnston Hamish
Published: April 2023

Hamish Johnston reviews Existential Physics: a Scientist’s Guide to Life’s Biggest Questions by Sabine Hossenfelder.
The battle to reach for the stars
Authors: Commissariat Tushna
Published: April 2023

Tushna Commissariat reviews What Stars Are Made Of: the Life of Cecilia Payne-Gaposchkin by Donovan Moore.
Pursuing joy in an alien world
Authors: Palethorpe Larissa
Published: April 2023

As the first in her family to attend university, astrophysics PhD student Larissa Palethorpe explains why multiple sources of support are necessary to survive and thrive in academia.
A journey of joy and uncertainty in physics
Authors: Mdhluli Joyful
Published: April 2023

High-energy physicist Joyful Mdhluli describes the joy that a career in physics brings, even after hitting rock bottom during her PhD.
The floor is lava
Authors: Hellner-Mestelman Nathan
Published: April 2023

Ever played that game where you jump around inside your house trying not to touch the floor because it’s made of lava? Nathan Hellner-Mestelman wonders what would happen if the floor really were made of hot, molten rock.