bluuebunny/crossref_metadata_2025 huggingface dataset:
Inverse Gertsenshtein effect as a probe of high-frequency gravitational waves
Authors: He Yutong , Giri Sambit K. , Sharma Ramkishor , Mtchedlidze Salome , Georgiev Ivelin
Published: May 2024

We apply the inverse Gertsenshtein effect, i.e., the graviton-photon conversion in the presence of a magnetic field, to constrain high-frequency gravitational waves (HFGWs).
Using existing astrophysical measurements, we compute upper limits on the GW energy densities ΩGW at 16 different frequency bands.
Given the observed magnetisation of galaxy clusters with field strength B ∼ μG correlated on 𝒪(10) kpc scales, we estimate HFGW constraints in the 𝒪(102) GHz regime to be ΩGW ≲ 1016 with the temperature measurements of the Atacama Cosmology Telescope (ACT).
Similarly, we conservatively obtain ΩGW ≲ 1013 (1011) in the 𝒪(102) MHz (𝒪(10) GHz) regime by assuming uniform magnetic field with strength B ∼ 0.1 nG and saturating the excess signal over the Cosmic Microwave Background (CMB) reported by radio telescopes such as the Experiment to Detect the Global EoR Signature (EDGES), LOw Frequency ARray (LOFAR), and Murchison Widefield Array (MWA), and the balloon-borne second generation Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE2)
with graviton-induced photons. The upcoming Square Kilometer Array (SKA) can tighten these constraints by roughly 10 orders of magnitude, which will be a step closer to reaching the critical value of ΩGW = 1 or the Big Bang Nucleosynthesis (BBN) bound of ΩGW ≃ 1.2 × 10-6.
We point to future improvement of the SKA forecast and estimate that proposed CMB measurement at the level of 𝒪(100-2) nK, such as Primordial Inflation Explorer (PIXIE) and Voyage 2050, are needed to viably detect stochastic backgrounds of HFGWs.
The imitation game reloaded: effective shadows of dynamically robust spinning Proca stars
Authors: Sengo Ivo , Cunha Pedro V.P. , Herdeiro Carlos A.R. , Radu Eugen
Published: May 2024

We analyse the lensing images by dynamically robust rotating (mini-)Proca stars surrounded by thin accretion disks. Due to their peculiar geodesic structure we show that these images exhibit striking similarities with the ones of BHs, for appropriately chosen disk intensity profile, when imposing a GRMHD-motivated emission cut off. Additionally, and unlike the non-rotating case, these similarities prevail even when considering equatorial observations. This example illustrates how a horizonless compact object without light rings, with a plausible formation mechanism and dynamically robust, could mimic detailed features of black hole imagiology.
Hawking–Page transition and the dual relations of anti-de Sitter black holes surrounded by dark energy in general dimensions
Authors: Xin Zhang , Wei Xu
Published: May 2024

Recently, a dual relationT0(n+ 1) =THP(n) between the minimum temperature (T0(n+ 1)) black hole phase and the Hawking–Page transition (THP(n)) black hole phase in two successive dimensions was introduced by Weiet al(2020Phys. Rev. D10210411); this was reminiscent of the anti-de Sitter/conformal field theory (AdS/CFT) correspondence, as the Hawking–Page transition temperature could be treated as the temperature of the dual physical quantity on the boundary and the latter corresponds to that in the bulk. In this paper, we discuss the Hawking–Page transition and the dual relations in AdS black holes surrounded by dark energy in general dimensions. Our findings reveal the occurrence of the Hawking–Page transition between the thermal AdS radiation and thermodynamically stable large AdS black holes, in both the spacetime surrounded by phantom dark energy and the spacetime surrounded by quintessence dark energy. We discuss the effects of the phantom dark energy and quintessence dark energy on the Hawking–Page transition temperature. For the dual relation in particular, it works well for the case of an AdS black holes surrounded by phantom dark energy. For the case of an AdS black hole surrounded by quintessence dark energy, the dual relation should be modified under an open assumption that the state parameter and the density parameter of the quintessence dark energy depend on the dimensions of the spacetime.
Consequences of a two-time relativistic Bohmian model
Authors: Raguní Giuseppe
Published: May 2024

Effects of a Bohmian type quantum-relativistic theory are explored. The model is obtained by introducing a new and independent time parameter whose relative motions are not directly observable and cause quantum uncertainties of the physical observables. Unlike the usual de Broglie–Bohm theories, the Quantum Potential does not directly affect the observable motion, but determines the one that is relative to the new time variable. It turns out that the Zitterbewegung of a free particle, of which a more general law is obtained, is the key example of these hidden motions and, through it, it seems possible to give physical reality to the Feynman’s paths. A relativistic revision of the uncertainty principle is also derived from the theory.
Cryo-EM combined with image deconvolution to determine ZIF-8 crystal structure
Authors: Wu 吴 Kang 抗 , Yang 杨 Baisong 柏松 , Xue 薛 Wenhua 文华 , Sun 孙 Dapeng 大鹏 , Ge 葛 Binghui 炳辉 , Wang 王 Yumei 玉梅
Published: May 2024

Metal–organic frameworks (MOFs) are crystalline porous materials with tunable properties, exhibiting great potential in gas adsorption, separation and catalysis.[1,2] It is challenging to visualize MOFs with transmission electron microscopy (TEM) due to their inherent instability under electron beam irradiation. Here, we employ cryo-electron microscopy (cryo-EM) to capture images of MOF ZIF-8, revealing inverted-space structural information at a resolution of up to about 1.7 Å and enhancing its critical electron dose to around 20 e
−/Å2. In addition, it is confirmed by electron-beam irradiation experiments that the high voltage could effectively mitigate the radiolysis, and the structure of ZIF-8 is more stable along the [100] direction under electron beam irradiation. Meanwhile, since the high-resolution electron microscope images are modulated by contrast transfer function (CTF) and it is difficult to determine the positions corresponding to the atomic columns directly from the images. We employ image deconvolution to eliminate the impact of CTF and obtain the structural images of ZIF-8. As a result, the heavy atom Zn and the organic imidazole ring within the organic framework can be distinguished from structural images.
Effect of the mixing of s-wave and chiral p-wave pairings on electrical shot noise properties of normal metal/superconductor tunnel junctions
Authors: Hu 胡 Yu-Chen 雨辰 , Hu 胡 Liang-Bin 梁宾
Published: May 2024

We study theoretically the electrical shot noise properties of tunnel junctions between a normal metal and a superconductor with the mixture of singlet s-wave and chiral triplet p-wave pairing due to broken inversion symmetry. We investigate how the shot noise properties vary as the relative amplitude between the two parity components in the pairing potential is changed. It is demonstrated that some characteristics of the electrical shot noise properties of such tunnel junctions may depend sensitively on the relative amplitude between the two parity components in the pairing potential, and some significant changes may occur in the electrical shot noise properties when the relative amplitude between the two parity components is varied from the singlet s-wave pairing dominated regime to the chiral triplet p-wave pairing dominated regime. In the chiral triplet p-wave pairing dominated regime, the ratio of noise power to electric current is close to 2e both in the in-gap and in the out-gap region. In the singlet s-wave pairing dominated regime, the value of this ratio is close to 4e in the inner gap region but may reduce to about 2e in the outer gap region as the relative amplitude of the chiral triplet pairing component is increased. The variations of the differential shot noise with the bias voltage also exhibit some significantly different features in different regimes. Such different features can serve as useful diagnostic tools for the determination of the relative magnitude of the two parity components in the pairing potential.
Optimal parameter space for stabilizing the ferroelectric phase of Hf0.5Zr0.5O2 thin films under strain and electric fields
Authors: Wang 王 Lvjin 侣锦 , Wang 王 Cong 聪 , Zhou 周 Linwei 霖蔚 , Zhou 周 Xieyu 谐宇 , Pan 潘 Yuhao 宇浩 , Wu 吴 Xing 幸 , Ji 季 Wei 威
Published: May 2024

Hafnia-based ferroelectric materials, like Hf0.5Zr0.5O2 (HZO), have received tremendous attention owing to their potentials for building ultra-thin ferroelectric devices. The orthorhombic(O)-phase of HZO is ferroelectric but metastable in its bulk form under ambient conditions, which poses a considerable challenge to maintaining the operation performance of HZO-based ferroelectric devices. Here, we theoretically addressed this issue that provides parameter spaces for stabilizing the O-phase of HZO thin-films under various conditions. Three mechanisms were found to be capable of lowering the relative energy of the O-phase, namely, more significant surface-bulk portion of (111) surfaces, compressive c-axis strain, and positive electric fields. Considering these mechanisms, we plotted two ternary phase diagrams for HZO thin-films where the strain was applied along the in-plane uniaxial and biaxial, respectively. These diagrams indicate the O-phase could be stabilized by solely shrinking the film-thickness below 12.26 nm, ascribed to its lower surface energies. All these results shed considerable light on designing more robust and higher-performance ferroelectric devices.
Research on finite element model of rotor aerodynamicnoise in hovering state
Authors: Huang Surui , Yang Kai , Sun Chengyuan , Shi Leilei
Published: May 2024

The helicopter has been widely used in many fields, and the rotor aerodynamic noise has gradually attracted attention. The non-homogeneous wave equation, Ffowcs Williams-Hawkings equation (FW-H equation) derived from hydrodynamic N-S equation, combined with RANS turbulence simulation, was used to simulate the sound field of NACA0012 airfoil-shape model in hovering state. On this basis, by changing the thickness and camber of the blade, the aerodynamic noise of the rotor under different airfoil profile thickness and camber is calculated. The results show that the change of airfoil thickness and camber will affect the aerodynamic noise of the rotor in hovering state.
Numerical investigation on the characteristics of underbody aerodynamic noise sources in electric vehicles
Authors: Yang Meng , Sun Zuokui , Hu Songyuan , Zhang Yongren
Published: May 2024

As the wind noise caused by the upper body is gradually controlled, the influence of high-speed underbody airflow on the interior noise of electric vehicles becomes increasingly prominent. The method involves the combined application of the Finite Volume Method (FVM) and Finite Element Analysis (FEA) to compute the aerodynamic noise inside a real vehicle model induced by high-speed airflow. A numerical simulation of the underbody wind noise in electric vehicles has been conducted to reveal the noise sources at the bottom of electric vehicles and cabin noise. Finally, the impact of side skirts and wind deflectors on chassis wind noise was evaluated.
Kalman filtering used for passive synthetic aperture
Authors: Liu Shijing , Gong Fusheng , Li Yuebo , Sun Xiangbo
Published: May 2024

In practice, beamforming-based bearing estimators typically fail to account for the impact of environmental factors on the estimating results, resulting in the so-called mismatch problem. To deal with this issue, this paper reconstructs the bearing estimation as a Kalman filter problem, which emphasizes the role of physical models in underwater acoustic signal processing. Since passive synthetic aperture (PSA) is a spatial process including the temporal evolution of a moving array, it fits a Kalman filtering structure. Kalman filter is applied directly to a lake-test dataset collected by an autonomous underwater vehicle (AUV) shell-mounted array, and the experimental findings demonstrate that the bearing estimation results’ variation is significantly decreased than the conventional beamforming (CBF).
Simulation of non-Newtonian fluid flow in a horizontal pipe
Authors: Bian Wenjing , Liu Dongren
Published: May 2024

Microchannel reactors exhibit distinct gas-liquid two-phase flow behaviors compared to macro-scale channels, offering advantages like efficient heat and mass transfer, compact size, and low energy consumption. Sodium carboxymethyl cellulose (CMC) emerges as a potent stabilizer, enhancing mixing, homogenization and pipeline transport. Its judicious application reduces equipment strain, amplifies homogenization efficiency and finds diverse utility in food processing and beyond. However, incorrect employment bears the risk of compromised outcomes, potentially leading to product wastage. Consequently, investigating N2-CMC solution flow in microchannels holds paramount significance for elevating efficacy, minimizing usage, refining product quality and bolstering yield. In this study, we simulated the N2-CMC solution flow dynamics within an interleaved T-shaped microchannel using FLUENT which is a numerical simulation software. The simulation delved into alterations in gas-liquid two-phase flow patterns and pressure drops. We examined the impacts of liquid concentration and gas-liquid flow rate ratio on flow patterns, pressure drops and bubble lengths. The simulation results exhibited congruence with experimental data. Notably, elevated liquid concentrations correlated with higher pressure drops and elongated bubble lengths. Conversely, augmenting the gas-liquid flow rate ratio led to diminished pressure drops while elongating bubble lengths. These findings furnish insights into flow patterns and pressure drop behaviors for gas-non-Newtonian fluids within microchannels, forming a pivotal reference for microfluidic system design.
Numerical simulation of the internal flow field for the new three-way changeover valve
Authors: Ren Xihang , Wu Shuai , Chen Dianjing
Published: May 2024

This article uses numerical simulation methods to simulate the internal flow field of a new three-way changeover valve structure, and verifies the simulation results through flow experiments. The results show that the flow coefficients on the handwheel side and opposite side of the new changeover valve obtained by the simulation method are within 10% of the experimental results, indicating that the results obtained by the simulation method can better match the experimental results. In addition, the flow coefficients on the handwheel side and opposite side of the new three-way changeover valve have increased by 49.6% and 64.3% respectively compared to the existing structure, indicating better flow capacity.
Analysis of the impact of different branching angles on the coronary flow field based on fluid-structure interaction
Authors: Bai Libo , Han Qingsong , Wang Xu
Published: May 2024

The bifurcation angle of the coronary artery can have an impact on blood flow velocity, especially in the narrow region, where the flow velocity becomes more pronounced, leading to further deterioration of the stenosis in that area. In order to investigate the effect of bifurcation angle on the coronary blood flow field, four bifurcation angle models were established in Solidworks, and a bidirectional fluid-solid coupling method was used to numerically simulate the blood distribution. The changes in the blood flow field at different periods were analyzed. The results showed that the blood flow velocity distribution was similar in the same model at different periods, with high flow velocity mainly concentrated in the coronary artery trunk and smooth branching flow velocity. The flow velocity was different at various periods, resulting in a large difference in the WSS range, which was most obvious during the peak diastolic period. The bifurcation angle had the most significant effect on TAWSS, and as the bifurcation angle increased, the area of the high TAWSS region continued to expand. A small amount of vortex at the bifurcation ridge affected the shear stress direction, resulting in a high OSI (>0.3) region in that area. In conclusion, the bifurcation angle has a significant effect on TAWSS, with the most significant fluctuation in the 37.5° to 42.5° range, and there may be a critical angle causing the fluctuation in between.
Study on the distribution characteristics of TBL fluctuating pressure of a submerged conical-cylindrical structure
Authors: Wang Hongfu , Guo Hanhui , Luan Chen , Zhou Quan , Gao Cong
Published: May 2024

The fluctuating pressure within turbulent boundary layers (TBL) has garnered significant attention as a pivotal factor in generating hydrodynamic noise for underwater vehicles. This study employs numerical simulations to investigate the fluctuating pressure of a submerged conical-cylindrical structure, utilizing the Improved Delayed Detached Eddy Simulation (IDDES) method. This research delves into the spatiotemporal distribution characteristics of wall fluctuating pressure across various Reynolds numbers. Notably, the power spectral density (PSD) curve of TBL fluctuating pressure exhibits relative stability at lower frequencies, whereas it undergoes a rapid decline in the high-frequency range, following an inverse proportional trend with the power-law exponent of frequency. Moreover, the dimensionless migration velocity in the parallel mid-body segment is consistent with the TBL over a flat plate, while it is slightly smaller in the outflow segment.
CFD for the optimization of spiral wound film assembly
Authors: Jin Wenchong , Qu Xingchuang
Published: May 2024

In this paper, a conventional mesh shim for a spiral wound membrane assembly is structurally optimized by adding jet holes to achieve the jet function, and the effect of curvature on fluid flow is investigated. The three different gaskets are compared with each other and the performance of the optimized gaskets is investigated by using computational fluid dynamics (CFD) techniques and analyzed parametrically. This knowledge can be supplemented by the use of CFD techniques for spacers, whereby the geometry of the spacer can be optimized and the corresponding performance of the spiral wound film assembly can be improved.
Numerical simulation of freak wave generation and evolution process based on SPH method
Authors: Hu Xuan , Halik Azhar
Published: May 2024

With the occurrence of maritime accidents all over the world, the study of extreme waves has been promoted. These extreme waves are often called freak waves in the scientific community. At present, a variety of mechanisms are proposed to explain freak waves in the marine environment, such as directional focusing, dispersive focusing, and nonlinear modulation instability. At first, a hydrodynamic model is established based on the Smoothed Particle Hydrodynamics (SPH) method in the C# environment, and the regular wave generated by the piston wave generator is numerically simulated. Secondly, the simulation results were analyzed and visualized by using Paraview software, compared with physical experimental datas to verify the reliability of this model. Then, the generation and evolution of freak waves were numerically simulated through the movement of piston wave generators on both sides of a 2D numerical wave flume, and the influence of frequency and amplitude was analyzed by using directional focusing. The results show that if the frequency is smaller and the amplitude is larger, it is more likely to generate freak waves and wave-breaking phenomena. This study lays a foundation for the research of freak waves in the future.
Key technologies and applications of cloud-edge collaborative integrated low and medium voltage distributed photovoltaic coordination control
Authors: Wang Xingnian , Zhang Jinshuai , Shang Bowen , Zhou Ning , Xu Mingming , Wang Peng , Song HongYan , Zhang Quanzhong
Published: May 2024

The large-scale distributed photovoltaic access leads to overvoltage, equipment overload, and difficulty in on-site consumption, which causes power to be sent back to the high voltage level, posing hidden dangers to the safe operation of the distribution network. This article proposes optimizing the medium-voltage distribution network at the cloud side with the goal of maximum consumption and operating cost, forming a rolling strategy adjustment based on load forecasting within the day. At the edge side, the distributed photovoltaic control in the low-voltage distribution network within the jurisdiction is adjusted based on the daily adjustment strategy issued by the cloud side, completing the optimization and regulation of distributed photovoltaics on a distribution substation unit basis to achieve the control and integration of distributed power sources and consumption, coordination between operation and side, and coordinated control in the integrated medium and low-voltage zoning, achieving autonomous distribution substations and feeder lines. Field applications have proven that this solution solves problems such as line and transformer overload, and voltage quality caused by distributed photovoltaic power generation.
Planning and design of an architectural energy supply system based on photovoltaic-thermal technology
Authors: Li Wen , Bu Fanpeng , Shi Guohua , Yuan Bin , Zhao Yuetian
Published: May 2024

China’s building energy consumption is growing and the energy consumption of the whole process of buildings accounts for more than 46.5% of the country’s total energy consumption, of which the proportion of energy consumption used for heating, ventilation and air conditioning is as high as 50%. Solar energy has the greatest potential to achieve energy conservation in buildings. Buildings are the best carrier for solar energy utilization because of the advantages of local collection and local application. The combination of solar energy and buildings can meet a variety of energy and health needs in buildings, among which solar photovoltaic and CSP building integration technology is an important way to reduce building energy consumption and improve indoor air quality. This article presents a PV/T-based thermal storage wall system that efficiently utilizes solar energy. It outlines the PV/T technology’s fundamental principles and provides a detailed description of the system’s construction and operation, highlighting critical components like the solid thermal storage medium and heat transfer via a heat pump. The analysis indicates improved energy utilization and favorable economic feasibility. This technology offers a practical solution for the construction industry, promoting sustainable energy practices and environmental conservation.
Multiple heating loads participate in the system power regulation control strategy
Authors: Li Weng’en , Guo Duange , Cao Zimin , Shi Xingyu
Published: May 2024

With the addition of a high proportion of new energy and power electronic equipment, the power system has shown characteristics such as low inertia and significant energy output fluctuation, which has brought great challenges to power/frequency regulation and control of the power system. Therefore, this article uses the inertia characteristics of heat energy on the load side and exerts reasonable start-stop control to play a positive and beneficial role in the power regulation of the power system. Firstly, the room temperature variation process was transformed into a lumped parameter equivalent model. A lumped parameter heat transfer model of a single typical load was built in Simulink, and its dynamic characteristics were analyzed by symbolic calculation. Based on this, a time-domain simulation was carried out to explore the influence of the law of system parameters and external input on the change of system state quantity. Based on time domain simulation, the behavior of the heating load is analyzed. Then, the effects of typical and multiple loads on system power regulation at different outdoor temperatures are studied. It is found that when the average outdoor temperature decreases, the sustainable time of system power upturn will increase, and the sustainable time of downturn will decrease. The power curve of multiple loads simultaneously is more stable, and the adjustment ability is stronger. The reasonable and flexible control method of load switch setting, namely the coherent characteristic load power regulation strategy, realizes the sustainable power optimization of the load to the system in the specified period.
Simulation of human risk scenarios for nuclear power plant operation based on finite state machine
Authors: Xue Jiaxin , Lu Yi , Xu Zhihui , Wu Guanyin , Yang Gaoguang , Fu Shan
Published: May 2024

This paper addresses risk scenarios caused by Human-Machine Interaction (HMI) during the Nuclear Power Plant (NPP) operation. A simulation method is proposed in this research based on a Finite State Machine (FSM) for analyzing human-related risk scenarios in NPP operations. The risk evolution mechanism between the physical system and operator is modeled by FSM to clarify how risk accumulation leads to accidents. It has the advantage of managing and simplifying the modeling process of complex relationships in NPP with the integration of human reliability analysis. The study focuses on the dynamic interaction between the physical system in the primary loop and the operators during the startup of NPP and evaluates human-related safety risk through simulation of the behavior of the operators handling the control rods. This research aims to present an FSM-based methodology for analyzing HMI-induced risks in NPP operations, which can be utilized to illustrate the risk evolution, especially human-related risk.
State inference for low-observable distribution system based on graph convolutional network
Authors: Xuan Yi , Sun Zhiqing , Li Qizhou , Liu Jian , Liang Yundan , Huang Jianping , Dai Tiechao , Liu Weihao , Huang Yi , Fan Libo , Liu Xingye , Zhang Jiansong , Chen Yifang , Jiang Jian
Published: May 2024

Distribution network state inference refers to the process of calculating the state variables of each node by using measurement data and network models in the operation of the distribution system. However, the uneven measurement layout and insufficient measurement accuracy in the distribution network have brought great challenges to the state inference of the distribution network. This paper proposes a low-observable distribution network state inference method based on a graph convolution network (GCN), which uses sparse measurement data to infer missing measurement information. Firstly, the observability of the distribution network is analyzed by the numerical probability analysis method. Secondly, the GCN is employed to extract feature information from measurement data and integrate these features. The state inference model of the distribution network based on the GCN is established. Subsequently, power flow constraints of the distribution network are incorporated into the GCN training process to enhance the precision of the generated data. Ultimately, the efficacy of the proposed method is validated using the IEEE 33-node distribution system.
Fault prevention strategy for coupled networks of power grids and transportation with the participation of electric vehicles
Authors: Chi Fang , Yang Jun , Wu Fuzhang , Ling Zaixun , Cui Yibo
Published: May 2024

The increasing number of electric vehicles (EVs) that are connected to the power grid has raised concerns about the security of both transportation and power grids. This paper presents a fault prevention strategy that involves the use of social networks to improve the performance of electric vehicle charging stations. Firstly, the goal of this strategy is to improve the electric vehicle charging station’s performance by developing an evolutionary game model that takes into account the various factors that affect the electric vehicle’s response and travel time. Secondly, a number of charging station sample data is generated and analyzed using a convolutional neural framework. The capacity of the stations is then calculated by taking into account the different incentive measures offered by the power grid.. Furthermore, an optimal power flow model considering fault risk constraints and charging and discharging capacity constraints is established in the power grid or power grid subsystem to adjust the generator output and charging station power to realize the safe dispatching of the power grid. The simulation example shows that this method can fully consider the influence of traffic networks in the participation of EVs in power grid fault prevention, which is more reasonable.
Detection and identification of bad data in AC/DC hybrid systems with LCC and MMC
Authors: Zhao Huashi , Huang Yaohui , Song Zhiqiang , Xu Jianzhong , Zheng Kexin , Liang Kangkang
Published: May 2024

Based on the CIM/XML and CIM/E documents exported from the regional dispatching system, this paper focuses on data generation and starts by converting the exported documents into raw input data for state estimation. Considering the interactions between the AC system, LCC, MMC, and LCC-MMC interfaces, a unified iterative method is proposed to model the state estimation of the 500 kV subnetwork. Subsequently, Gaussian noise is added to the original measurement data, and the maximum residual test method is employed for detecting and identifying bad data. Finally, the effectiveness of the proposed models for AC/DC state estimation and the detection and identification of bad data are validated through simulation data.
An online detection method for the mechanical fault of circuit breakers of rural distribution lines based on continuous wavelet transform and vibration signal characteristics
Authors: Li Xuejun , Cheng Ming , Chen Wei , Luo Yanxin
Published: May 2024

Rural distribution lines are widely distributed and dispersed, involving numerous circuit breaker equipment. Detecting mechanical faults on each circuit breaker requires significant time and human resources. It can bring significant interference and power outage risks to the operation of the line. Therefore, an online detection method is studied for mechanical faults in rural distribution line circuit breakers. Continuous wavelet transform technology is used to extract the characteristics of circuit breaker vibration signals. This feature is used to locate the faulty section. The PNN neural network is introduced to identify fault feature samples and achieve online detection of mechanical faults. To test the application performance of this method, a comparative experiment is designed. The results verified that when using this method to extract the vibration signal of circuit breaker mechanical faults, the error is low, and the fault detection accuracy is high.
Dual three-phase permanent magnet synchronous motors model predictive torque control based on zero common-mode voltage
Authors: Zhang Yangdong , Huang Qiaoliang
Published: May 2024

This article proposes a multi-vector model predictive torque control strategy based on zero common-mode voltage to suppress common-mode voltage and harmonic currents in a dual three-phase permanent magnet synchronous motor. Firstly, 20 zero common-mode voltage vectors are selected from the traditional 64 basic voltage vectors. By synthesizing these 20 vectors into 6 virtual voltage vectors (VVV), control over the harmonic plane is achieved, reducing harmonic currents and eliminating common-mode voltage. Then, the control error of the flux is reduced by increasing the number of vectors to achieve the purpose of reducing the flux ripple. Finally, through duty cycle modulation, multi-vector model predictive torque control extends the modulation range to the entire sector plane. Simulation results confirm that this strategy can effectively suppress harmonic currents and common mode voltage.
Power system planning considering demand side response
Authors: Miao Linxin , Qi Yuchen , Li Haoen , Jiang Yumeng , Huang Ruanming , Song Tianli , Xue Kun , Cui Min , Liu Ziqiu
Published: May 2024

The large-scale integration of wind power into the grid requires the redesign and expansion of the transmission network. The volatility of wind power and the limited application of energy storage have prompted the inclusion of demand-side response in transmission planning to improve the resilience of the grid. In this paper, a power system planning model that incorporates demand-side response is developed and the model is solved by using a greedy stochastic adaptive search process. Based on the results of the Garver 6-node test, the old and new models are compared to validate the effectiveness of the power system planning model considering demand side response.
A single-objective optimization model for power systems with the introduction of line-heavy load rate index constraints
Authors: Han Xingning , Zhao Feifei , Zhang Wenjia , Qi Wanchun
Published: May 2024

The increasing penetration of new energy sources in new power systems has exacerbated the volatility and complexity of power system currents. Grid planning is facing higher challenges. Established grid planning models usually use the upper and lower limits of grid transmission capacity as constraints, but this may lead to long-term heavy load operation of certain lines and increase system risks. Therefore, this paper designs a line-heavy load rate constraint and establishes a single-objective optimization model for grid planning based on this constraint. Example analyses verify the effectiveness of adding line-heavy load rate constraints in planning and the reasonableness of the single-objective optimization model.
Outer Barrel services chain characterisation for the ATLAS ITk Pixel detector
Authors: Flores Sanz de Acedo Leyre ,   the ATLAS ITk Pixel collaboration
Published: May 2024

For the high-luminosity upgrade of the ATLAS Inner Tracking detector of the ATLAS experiment, a new pixel detector will be installed to allow for a bigger bandwidth and cope with the increased radiation among other challenges. This contribution will present the evaluation of the Outer Barrel Pixel layer services chains. A full data transmission study covering data merging will be presented from the pixel module all the way to the FELIX data acquisition system, using most of the components foreseen for the detector. Challenges and results of the services chain of the Outer Barrel will be highlighted.
Testing and characterisation of the prototype readout chip for the High-Luminosity
LHC upgrade of the CMS Inner Tracker
Authors: Grippo Michael ,   the CMS Tracker Group
Published: May 2024

This contribution describes the characterisation and validation campaign of the prototype
of the CMS Readout Chip (CROC), a 65 nm CMOS pixel readout ASIC for the CMS Inner Tracker upgrade
for High Luminosity LHC. This validation campaign includes tests with single-chip and multi-chip
modules, irradiation campaigns, test beams and wafer-level tests. The main results obtained in the
testing of the CROC prototype will be outlined. Key improvements and fixes that have been
implemented in the final version of the chip before the October 2023 submission will be described.
Investigation of low gain avalanche detectors exposed to proton fluences beyond 1015
n
eq cm-2
Authors: Sorenson J. , Hoeferkamp M.R. , Kramberger G. , Seidel S. , Si J.
Published: May 2024

Low gain avalanche detectors (LGADs) deliver excellent
timing resolution, which can mitigate mis-assignment of vertices
associated with pileup at the High Luminosity LHC and other future
hadron colliders. The most highly irradiated LGADs will be subject
to 2.5 × 1015
n
eq cm-2
of hadronic fluence during HL-LHC operation; their performance must
tolerate this. Hamamatsu Photonics K.K. and Fondazione Bruno Kessler
LGADs have been irradiated with 400 and 500 MeV protons
respectively in several steps up to
1.5 × 1015
n
eq cm-2. Measurements of the acceptor removal constants of
the gain layers, evolution of the timing resolution and charge
collection with damage, and inter-channel isolation characteristics,
for a variety of design options, are presented here.
Multi-scale deep residual shrinkage networks with a hybrid attention mechanism for rolling bearing fault diagnosis
Authors: Zhang Xinliang , Wang Yanqi , Wei Shengqiang , Zhou Yitian , Jia Lijie
Published: May 2024

The fault diagnosis of rolling bearings based on deep
networks is hindered by the unexpected noise involved with
accessible vibration signals and global information abatement in
deepened networks. To combat the degradation, a multi-scale deep
residual shrinkage network with a hybrid attention mechanism
(MH-DRSN) is proposed in this paper. First, a spatial domain
attention mechanism is introduced into the residual shrinkage module
to represent the distance dependence of the feature maps. Then, a
hybrid attention mechanism considering both the inner-channeled and
cross-channeled characteristics is constructed. Through the
comprehensive evaluation of the feature map, it provides a soft
threshold for the activation function and realizes the feature-map
selection adaptively. Second, the dilated convolution with different
dilation rates is implemented for multi-scale context information
extraction. Through the feature combination of the DRSN and the
dilated convolution, the global information of the rolling bearing
fault is strengthened and preserved as the fault diagnosis network
is deepened. Finally, the performance of the proposed
fault-diagnosis model is validated on the dataset from Case Western
Reserve University (CWRU). The experimental results show that,
compared with common convolution neural networks, the proposed
neural diagnosis model provides a higher identification accuracy and
better robustness under noise interference.
Imaging of low Z masked with high Z (Pb, U) materials using 14 MeV neutron
Authors: Bishnoi Saroj , Patel Tarun , Sarkar P.S. , Pant L.M.
Published: May 2024

An experimental study has been performed using 14 MeV neutrons for imaging of low Z material (particularly composed of C, H, O elements) masked with thick layers of dense and high Z materials. The experimental setup consists of a D-T neutron generator, a metallic collimator and an imaging system. The imaging system is designed with a polypropylene zinc sulphide scintillator screen integrated with a lens coupled 16-bit ICCD camera. Imaging capability of the system was investigated using iron test samples with holes and line pair features. The minimum hole size of 2 mm could be imaged at a contrast of 36% and a line of 2 mm width visible at a contrast of 24% indicating the system's resolution of ∼ mm. Low Z samples such as water (H2O) and polyethylene (C2H2)
n
placed behind thick layers of Pb (40 mm) and Uranium (35 mm), were imaged successfully. These images reveal the system's ability towards low Z material imaging in the presence of heavier metals. Good contrast images acquired at a lower neutron yield of ∼ 5 × 108 n/sec of D-T neutron generator has provided a possibility to realise fast neutron imaging having moderate resolution (∼ mm) with a smaller footprint and an economical system design for field applications.
Performance of a first full-size WOM-based liquid scintillator detector cell as prototype for the SHiP Surrounding Background Tagger
Authors: Alt J. , Bezshyyko O. , Böhles M. , Brignoli A. , Conaboy A. , Deucher P. , Eckardt C. , Ernst A. , Fischer H. , Hollnagel A. , Jadidi M. , Lacker H. , Lyons F. , Molzberger T. , Ochoa S. , Orlov V. , Reghunath A. , Rehbein F. , Schaaf M. , Scharf C. , Schmidt J. , Schumann M. , Vagts A. , Wurm M.
Published: May 2024

As a prototype detector for the SHiP Surrounding Background
Tagger (SBT), we constructed a cell
(120 cm × 80 cm × 25 cm) made from corten steel that is filled with liquid
scintillator (LS) composed of linear alkylbenzene (LAB) and
2,5-diphenyloxazole (PPO). The detector is equipped with two
Wavelength-shifting Optical Modules (WOMs) for light collection of
the primary scintillation photons. Each WOM consists of an acrylic
tube that is dip-coated with a wavelength-shifting layer on its
surface. Via internal total reflection, the secondary photons
emitted by the molecules of the wavelength shifter are guided to a
ring-shaped array of 40 silicon photomultipliers (SiPMs) coupled to
the WOM for light detection. The granularity of these SiPM arrays
provides an innovative method to gain spatial information on the
particle crossing point. Several improvements in the detector design
significantly increased the light yield with respect to earlier
proof-of-principle detectors.

We report on the performance of this prototype detector during an
exposure to high-energy positrons at the DESY II test beam facility
by measuring the collected integrated yield and the signal
time-of-arrival in each of the SiPM arrays. The resulting detection
efficiency and reconstructed energy deposition of the incident
positrons are presented, as well as the spatial and time resolution
of the detector. These results are then compared to Monte Carlo
simulations.
Gradients of properties increase the morphing and stiffening performance of bioinspired synthetic fin rays
Authors: Das Saurabh , Kunjam Prashant , Ebeling Jona Faye , Barthelat Francois
Published: May 2024

State-of-the-art morphing materials are either very compliant to achieve large shape changes (flexible metamaterials, compliant mechanisms, hydrogels), or very stiff but with infinitesimal changes in shape that require large actuation forces (metallic or composite panels with piezoelectric actuation). Morphing efficiency and structural stiffness are therefore mutually exclusive properties in current engineering morphing materials, which limits the range of their applicability. Interestingly, natural fish fins do not contain muscles, yet they can morph to large amplitudes with minimal muscular actuation forces from the base while producing large hydrodynamic forces without collapsing. This sophisticated mechanical response has already inspired several synthetic fin rays with various applications. However, most ‘synthetic’ fin rays have only considered uniform properties and structures along the rays while in natural fin rays, gradients of properties are prominent. In this study, we designed, modeled, fabricated and tested synthetic fin rays with bioinspired gradients of properties. The rays were composed of two hemitrichs made of a stiff polymer, joined by a much softer core region made of elastomeric ligaments. Using combinations of experiments and nonlinear mechanical models, we found that gradients in both the core region and hemitrichs can increase the morphing and stiffening response of individual rays. Introducing a positive gradient of ligament density in the core region (the density of ligament increases towards the tip of the ray) decreased the actuation force required for morphing and increased overall flexural stiffness. Introducing a gradient of property in the hemitrichs, by tapering them, produced morphing deformations that were distributed over long distances along the length of the ray. These new insights on the interplay between material architecture and properties in nonlinear regimes of deformation can improve the designs of morphing structures that combine high morphing efficiency and high stiffness from external forces, with potential applications in aerospace or robotics.
Research of biomimetic corrugation on the blade flutter suppression in large-scale wind turbine systems
Authors: Zhang Lijun , Wang Kaifei , Zhang Xu , Liu Shibo , Jing Zhengjun , Lu Jiahui , Cui Xudong , Liu Jing
Published: May 2024

Aiming at the blade flutter of large horizontal-axis wind turbines, a method by utilizing biomimetic corrugation to suppress blade flutter is first proposed. By extracting the dragonfly wing corrugation, the biomimetic corrugation airfoil is constructed, finding that mapping corrugation to the airfoil pressure side has better aerodynamic performance. The influence of corrugation type, amplitude λ, and intensity on airfoil flutter is analyzed using orthogonal experiment, which determines that the λ has the greatest influence on airfoil flutter. Based on the fluctuation range of the moment coefficient ΔC
m, the optimal airfoil flutter suppression effect is obtained when the type is III, λ= 0.6, and intensity is denser (n = 13). The effective corrugation layout area in the chord direction is determined to be the leading edge, and the ΔC
m of corrugation airfoil is reduced by 7.405%, compared to the original airfoil. The application of this corrugation to NREL 15 MW wind turbine 3D blades is studied, and the influence of corrugation layout length in the blade span direction on the suppressive effect is analyzed by fluid-structure interaction. It is found that when the layout length is 0.85 R, the safety margin S
f reaches a maximum value of 0.3431 Hz, which is increased 2.940%. The results show that the biomimetic corrugated structure proposed in this paper can not only improve the aerodynamic performance by changing the local flow field on the surface of the blade, but also increase the structural stiffness of the blade itself, and achieve the effect of flutter suppression.
Distinct responses of tropical cyclone activity to spatio-uniform and nonuniform SST warming patterns
Authors: Xu Mingrui , Zhan Ruifen , Zhao Jiuwei
Published: May 2024

Most previous studies have reported a decrease in global tropical cyclone (TC) genesis frequency (TCGF) under anthropogenic warming. However, little attention has been drawn to the influence of sea surface temperature (SST) warming patterns on TCGF changes. Here, we investigate the impacts of three distinct SST warming patterns on global TCGF: uniform SST warming, nonuniform (El Niño-like) SST warming, and a combination of both. Results show that spatio-uniform SST warming has a limited impact on global TCGF, instead redistributing the TC genesis locations. Conversely, nonuniform SST warming significantly suppresses global TCGF. The combined warming produces a similar decrease in TCGF to nonuniform warming albeit with differences in spatial distribution. This indicates the dominant role of nonuniform SST warming in affecting TCGF and highlights the nonlinearity of the process. Further analysis shows that these differences in TCGF primarily stem from the distinct responses of tropical circulations to the three warming patterns.
Anomalous and ultraslow diffusion of a particle driven by power-law-correlated and distributed-order noises
Authors: Tomovski Z , Górska K , Pietrzak T , Metzler R , Sandev T
Published: May 2024

We study the generalised Langevin equation (GLE) approach to anomalous diffusion for a harmonic oscillator and a free particle driven by different forms of internal noises, such as power-law-correlated and distributed-order noises that fulfil generalised versions of the fluctuation-dissipation theorem. The mean squared displacement and the normalised displacement correlation function are derived for the different forms of the friction memory kernel. The corresponding overdamped GLEs for these cases are also investigated. It is shown that such models can be used to describe anomalous diffusion in complex media, giving rise to subdiffusion, superdiffusion, ultraslow diffusion, strong anomaly, and other complex diffusive behaviours.
An algebraic formulation of nonassociative quantum mechanics
Authors: Schupp Peter , Szabo Richard J
Published: May 2024

We develop a version of quantum mechanics that can handle nonassociative algebras of observables and which reduces to standard quantum theory in the traditional associative setting. Our algebraic approach is naturally probabilistic and is based on using the universal enveloping algebra of a general nonassociative algebra to introduce a generalized notion of associative composition product. We formulate properties of states together with notions of trace, and use them to develop Gel’fand–Naimark–Segal constructions. We describe Heisenberg and Schrödinger pictures of completely positive dynamics, and we illustrate our formalism on the explicit examples of finite-dimensional matrix Jordan algebras as well as the octonion algebra.