bluuebunny/crossref_metadata_2025 huggingface dataset:
A single dielectric nanoparticle for refractive index sensing
Authors: Peng Ruiguang , Wen JingDa , Zhao Qian
Published: October 2024

Refractive index sensing has great application potential in a wide range of chemical and biomedical fields, however, these sensors usually require large-area and fabrication-intense arrays of unit cells. Here, we propose an ultracompact sensor based on a single dielectric nanoparticle for refractive index sensing with a footprint smaller than 2 µm2 and numerically investigate its sensing performance. A single-mode resonance rather than multimodes interaction is adopted for the spectroscopic feature of refractometric sensing. The elaborate resonator geometry facilitates the excitation of the gapped-vortex mode and enables the exposure of electric hotspots outside the dielectric. Such design enhances the coupling to the sensing medium, thus exhibiting high sensitivity at the level of 345 nm RIU–1 with a figure of merit of 12.78 per RIU. The single-particle nanostructure together with the single-mode resonance exhibits robust sensing performance to dimension deviations. Importantly, a thin annular beam is employed as the illumination to increase the excitation efficiency of the single-mode resonance, which significantly improves the modulation depth without relying on the near-field coupling of array nanostructures. This work provides a miniaturization platform for the dielectric sensors and other application fields based on enhanced light-matter interaction.
Charge transfer induced phase transition in Li2MnO3 at high pressure
Authors: Khangal Ajinkya P , Patel Nishant N , Mishra Ajay K
Published: October 2024

Efficient and better energy storage materials are of utmost technological importance to reduce energy dependence on the fossil fuels. Li2MnO3 is one such material having potential to meet most of the requirements for energy storage. This material has been synthesized using solid state synthesis route. High pressure structural and vibrational studies on this material have been carried out upto ∼22 and 26 GPa respectively. These investigations show occurrence of a hitherto unknown second order phase transition to a new low symmetry phase whose symmetry is constrained to be monoclinic with space group P21/n at pressure of ∼2.3 GPa in Li2MnO3. The bulk modulus and its derivative determined by fitting the P–V data with third order Birch–Murnaghan equation of state are 113.3 ± 13.1 GPa and 4.1 ± 1.2 respectively. Mode Grüneisen parameter calculated for all the Raman modes show positive values which indicates the absence of any soft mode in this material. A microscopic mechanism based on bond-charge transfer is invoked and applied to understand the spectroscopic changes occurring in this material which also manifests second order structural phase transition. Enhancement in covalent character of Li–O bonds in the Li–O polyhedra is inferred based on the spectroscopic observation and above mechanism.
Fluorescence microscopic image enhancement method based on multi-saliency guided filtering fusion
Authors: Hu Qiu , Zeng Haiwei , Miao Yanzi , Wang Kehui , Wu Shuangle , Li Wenhui , Zhang Zhiwang
Published: October 2024

Aiming at addressing the issues of colour deviation and clarity reduction in digital pathological imaging systems caused by complex environmental interferences such as uneven slice thickness, sample jitter, and background noise, this paper proposes a multi-saliency-guided filtering fusion enhancement method that combines energy saliency and Gaussian saliency. Firstly, a series of Gamma correction and spatial linear saturation adjustments are applied to enhance the contrast and colour saturation of blurred images, resulting in a sequence of pseudo-exposure images with improved contrast and saturation. Then, the pseudo-exposure images are decomposed into base and detail layers, and the fusion rules of energy saliency and Gaussian saliency-guided filtering are applied to each layer separately. Finally, clear microscopic images are obtained through two-scale reconstruction. This method overcomes the limitations of conventional deblurring algorithms that rely on prior estimation of scene depth and complex depth mapping processes. Experimental results on a dataset of cytological bright-field microscopic imaging samples show that the clarity evaluation metrics, including peak signal-to-noise ratio, root mean square error, and structural similarity index, have significantly improved, indicating that the proposed method can effectively improve the colour fidelity of the samples while eliminating noise interference and enhancing the clarity of cellular texture structures.
Application of NiS modified WS2/TiO2 heterostructure in photocathodic protection
Authors: Wu Hanbing , Bai Zhiming , Cheng Hongmei , Zhou Zhengqing , Zhang Zhibo
Published: October 2024

Stainless steel, as a popular corrosion resistant material, is still vulnerable to pitting corrosion in the marine environment. Therefore, in order to ensure the safety of stainless steel in the marine environment, it is necessary to implement corresponding protective measures. Titanium dioxide (TiO2), as an N-type semiconductor with excellent photoelectric properties, is widely used in the field of cathodic protection. However, as a photogenerated cathodic corrosion protection material, TiO2 has the disadvantages of low conductivity and high carrier recombination rate. Therefore, WS2 and NIS were introduced in this paper to modify it. TiO2/WS2/NiS (TWN) composites with Type-Ⅱ heterojunction structure were prepared by hydrothermal method and titration method. The results reveal TWN5 showed the best photoelectrochemical (PEC) performance, and the photocurrent density was 69% higher than that of a pure TiO2 photoanode, and the photochemical and photocathodic protection performance was significantly better than that of pure TiO2. Under simulated ocean conditions, the self-corrosion potential of 304ss combined with TW5 and TWN5 photoanodes is reduced to −0.64 V and −0.7 V, respectively. The main reason is that the contact surfaces of WS2 and TiO2 formed a Type II heterostructure, which accelerates the separation and diffusion processes of photoinduced carriers. In addition, the plasmon resonance effect of NiS improves the ability to absorb visible light, and the metallic-like feature of NiS also promotes charge separation.
The influence of continuum lowering on the equilibrium composition of plasma: case study of laser-induced plasma on a WC–Cu target
Authors: Ristić Miroslav , Krstevski Nikola , Ranković Dragan , Marković Milica , Šajić Aleksandra , Kuzmanović Miroslav
Published: October 2024

The composition of the plasma obtained by laser ablation of cermet WC–Cu is calculated under the assumption of local thermodynamic equilibrium. Special attention is paid to the effect of lowering the ionization potential, the influence of which in the Saha equations is reflected both through the exponential Boltzmann term and through the partition functions of atomic and ionic species present in the plasma. The effects of these two terms are separated and quantified. It has been shown that the correction to the partition functions due to the reduction of the ionization potential is of greater importance than the correction to the Boltzmann term at higher temperatures for atomic species. It is thus necessary for the precise determination of the plasma composition, especially at higher temperatures. The effect of lowering the ionization potential on different types of atoms as well as on different ionic states is analyzed. The change of the partition function due to the lowering of ionization energy also affects the concentration of single charged ions in an amount comparable to the correction of the Boltzmann term.
Resonant solitary states in complex networks
Authors: Niehues Jakob , Yanchuk Serhiy , Berner Rico , Kurths Jürgen , Hellmann Frank , Anvari Mehrnaz
Published: October 2024

Partially synchronized solitary states occur frequently when a synchronized system of networked oscillators with inertia is perturbed locally. Several asymptotic states of different frequencies can coexist at the same node. Here, we reveal the mechanism behind this multistability: additional solitary frequencies arise from the coupling between network modes and the solitary oscillator’s frequency, leading to significant energy transfer. This can cause the solitary node’s frequency to resonate with a Laplacian eigenvalue. We analyze which network structures enable this resonance and explain longstanding numerical observations. Another solitary state that is known in the literature is characterized by the effective decoupling of the synchronized network and the solitary node at the natural frequency. Our framework unifies the description of solitary states near and far from resonance, allowing to predict the behavior of complex networks from their topology.
Electromagnetic compatibility study of trackside antenna array miniaturization in the subway tunnel
Authors: Zhou Wen-Ying , Xu Jin-Jing , Lu Mai , Li Yu-Xin
Published: October 2024

To improve the compatibility of the subway tunnel’s electromagnetic environment and reduce the radiation impact of trackside antennas on subway workers. This paper proposes a miniaturized dual-band trackside antenna array by using metamaterial units. Its operation bandwidth is 2.33 ∼ 2.56 GHz and 3.24 ∼ 3.45 GHz, which could simultaneously satisfy the signal cover demands of the communications-based train control (CBTC) and the civil 5G wireless communication system. The proposed miniaturized antenna array has a maximum gain of 14.4 dBi and a maximum channel capacity of 13.9 bps Hz−1 at a signal-to-noise ratio (SNR) of 20 dB, which can effectively improve the quality of wireless communication systems. The number of trackside antennas with a single operation frequency band is reduced, and the distance between the antennas is enlarged at the same time. Besides that, we analyze the radiation impact on the tunnel electromagnetic environment of the proposed trackside antenna array. In particular, the electromagnetic dose absorbed by the human model of a tunnel worker is quantized. The results show that the electric field strength in the tunnel reduces by 4.11% at least after antenna array miniaturization, and the specific absorption rate (SAR) absorbed by the worker model’s trunk, skull, brain, heart, and liver is reduced by a maximum of 19.02%, 33.16%, 28.27%, 41.75%, and 74.54%, respectively, further lowering the human electromagnetic exposure risk. Therefore, a miniaturized trackside antenna array could reduce the interference from other radiation sources in the tunnel while providing a new idea for electromagnetic protection for subway workers.
Extraction of two-magnon scattering and detection of inverse spin Hall effect up to 40 GHz in low-damping Fe65Co35/Pt bilayer thin film
Authors: Koteswara Rao B S R , Sahu Savita , Basheed G A
Published: October 2024

We report an investigation of the inverse spin Hall effect (ISHE), as a measure of the pure spin current (J

S
), induced by spin pumping in a Fe65Co35/Pt bilayer using coplanar waveguide ferromagnetic resonance (CPW-FMR) in the in-plane (IP) geometry over the broadband microwave frequency range of 8–40 GHz. From the IP-FMR measurements, the defect-induced two-magnon scattering (TMS) contribution is evaluated by analyzing the frequency dependence of FMR linewidth using Arias and Mills approach [Arias R and Mills D L (1999 Phys. Rev. B 60, 7395), Mills D L and Arias R (2006 Physica B 384 147–151)]. Here, we have determined a very low Gilbert damping constant (α

G
) for Fe65Co35 bare film around 1.3 × 10−3, which is essential for the high spin current (>107 A/m2) generation. The enhanced value of α

G
≈3.2 × 10−3 obtained for Fe65Co35/Pt bilayer film is due to spin pumping damping, α

SP
= 1.9 × 10−3, confirmed by the ISHE induced DC voltage (V

DC
) signal measured across the edges of Pt layer. Out-of-plane (OP) angular ISHE measurements have been performed to disentangle spin pumping from spin rectification effects in the V

DC
signal. Further, we evaluated the effective spin-mixing conductance

g

eff

↑
↓

= 3.33 × 1019 m−2, which is higher than the values reported in FeCo-alloy-based bilayer systems. The present study aims to detect the J

S
injected by low-damping Fe65Co35 thin films, leading to the realization of energy-efficient spintronic devices.
Dynamic quantum secret sharing with identity verification based on quantum walks
Authors: Feng Lu , Zhou Ri-Gui , Zhang Xiao-Xue
Published: October 2024

A dynamic quantum secret sharing protocol with authentication is proposed based on quantum walks. The protocol can share specific secrets and also update the secret information periodically based on the existing quantum walks structure. Participants can be added or removed while keeping the original secret unchanged. This is more flexible in practical applications. Before the secrets are shared, each participant is authenticated to ensure the legitimacy of all participants’ identities. In addition, the protocol uses single photons as quantum resources, avoiding the complex preparation of entangled states, which makes the protocol more advantageous and potential in practical applications. Security analyses show that the protocol is resistant to collusion attack and other common attacks.
Development of a novel automated algorithm for patient dosimetry in computed tomography: a step towards the facilitation of size-specific dose estimates and organs dosimetry estimations in a busy clinical workflow
Authors: Sekkat Hamza , Khallouqi Abdellah , Madkouri Youssef , El Atifi Wiam , Rhouch Imane , El rhazouani Omar , Tahiri Zakaria , Talbi Mohammed , Halimi Abdellah
Published: October 2024

Accurate dosimetry in computed tomography (CT) is essential for patient safety and effective radiation management. This study presents the development of an automated algorithm designed to enhance patient dosimetry by facilitating size-specific dose estimates (SSDE) and organ dose estimations. Utilizing a Python-based script, the proposed method integrates advanced image preprocessing, contour detection, and mathematical calculations to quantify key metrics from CT images. This automated approach addresses the limitations of manual measurement techniques. A retrospective analysis was conducted on CT axial images from examinations acquired with an 80-detector scanner. The algorithm processes DICOM images, converts pixel values to Hounsfield Units, applies Gaussian smoothing, windowing, and thresholding, followed by morphological operations to refine segmentation. It measures the water equivalent diameter (Dw) and estimates both region SSDE and organ doses, incorporating tissue attenuation. Validation was performed using an adult anthropomorphic ATOM phantom, with organ doses measured by optically stimulated luminescence dosimeters. The results demonstrated the algorithm’s potential in estimating SSDE and organ doses. Validation of the automated method revealed strong correlations for Dw and SSDE between the proposed method and manual measurements of five expert reviewers ranging from 0.86 to 0.99 for determination coefficient. Comparative analysis of organ doses showed close agreement between results from experimental setup against the proposed algorithm. The automated algorithm estimated brain dose with a mean of 21.8 mGy, while measurements from the ATOM phantom and CT Expo indicated 19.74 mGy and 23.05 mGy, respectively. For lung doses, the automated algorithm estimated 12.5 mGy compared to 11.0 mGy from the ATOM phantom and 13.1 mGy from CT Expo. Liver doses were measured at 12.7 mGy by the automated method, versus 12.1 mGy from the ATOM phantom and 11.1 mGy from CT Expo. This study shows the potential of automated image analysis techniques in enhancing dosimetry accuracy in CT examinations.
Atmospheric neutron single event effects for multiple convolutional neural networks based on 28-nm and 16-nm SoC
Authors: Zhao 赵 Xu 旭 , Du 杜 Xuecheng 雪成 , Ma 马 Chao 超 , Hu 胡 Zhiliang 志良 , Yang 杨 Weitao 卫涛 , Zheng 郑 Bo 波
Published: October 2024

The single event effects (SEEs) evaluations caused by atmospheric neutrons were conducted on three different convolutional neural network (CNN) models (Yolov3, MNIST, and ResNet50) in the atmospheric neutron irradiation spectrometer (ANIS) at the China Spallation Neutron Source (CSNS). The Yolov3 and MNIST models were implemented on the XILINX 28-nm system-on-chip (SoC). Meanwhile, the Yolov3 and ResNet50 models were deployed on the XILINX 16-nm FinFET UltraScale+MPSoC. The atmospheric neutron SEEs on the tested CNN systems were comprehensively evaluated from six aspects, including chip type, network architecture, deployment methods, inference time, datasets, and the position of the anchor boxes. The various types of SEE soft errors, SEE cross-sections, and their distribution were analyzed to explore the radiation sensitivities and rules of 28-nm and 16-nm SoC. The current research can provide the technology support of radiation-resistant design of CNN system for developing and applying high-reliability, long-lifespan domestic artificial intelligence chips.
Deep learning-based spike sorting: a survey
Authors: Meyer Luca M , Zamani Majid , Rokai János , Demosthenous Andreas
Published: October 2024

Objective. Deep learning is increasingly permeating neuroscience, leading to a rise in signal-processing applications for extracellular recordings. These signals capture the activity of small neuronal populations, necessitating ‘spike sorting’ to assign action potentials (spikes) to their underlying neurons. With the rise in publications delving into new methodologies and techniques for deep learning-based spike sorting, it is crucial to synthesise these findings critically. This survey provides an in-depth evaluation of the approaches, methodologies and outcomes presented in recent articles, shedding light on the current state-of-the-art. Approach. Twenty-four articles published until December 2023 on deep learning-based spike sorting have been examined. The proposed methods are divided into three sub-problems of spike sorting: spike detection, feature extraction and classification. Moreover, integrated systems, i.e. models that detect spikes and extract features or do classification within a single network, are included. Main results. Although most algorithms have been developed for single-channel recordings, models utilising multi-channel data have already shown promising results, with efficient hardware implementations running quantised models on application-specific integrated circuits and field programmable gate arrays. Convolutional neural networks have been used extensively for spike detection and classification as the data can be processed spatiotemporally while maintaining low-parameter models and increasing generalisation and efficiency. Autoencoders have been mainly utilised for dimensionality reduction, enabling subsequent clustering with standard methods. Also, integrated systems have shown great potential in solving the spike sorting problem from end to end. Significance. This survey explores recent articles on deep learning-based spike sorting and highlights the capabilities of deep neural networks in overcoming associated challenges, but also highlights potential biases of certain models. Serving as a resource for both newcomers and seasoned researchers in the field, this work provides insights into the latest advancements and may inspire future model development.
Surrogate model of turbulent transport in fusion plasmas using machine learning
Authors: Li H. , Wang L. , Fu Y.L. , Wang Z.X. , Wang T.B. , Li J.Q.
Published: October 2024

The advent of machine learning (ML) has revolutionized the research of plasma confinement, offering new avenues for exploration. It enables the construction of models that effectively streamline the simulation process. While previous first-principles simulations have provided physics-based transport information, they have been inadequate fast for real-time applications or plasma control. In order to address this challenge, we introduce SExFC, a surrogate model based on the Gyro-Landau Extended Fluid Code (ExFC). An approach of physics-based database construction is detailed, as well the validity is illustrated. Through harnessing the power of ML, SExFC offers the capability to deliver rapid and precise predictions, facilitating real-time applications and enhancing plasma control. The proposed model integrates the recurrent neural network (RNN) algorithm, specifically leveraging the Gated Recurrent Unit (GRU) for iterative prediction of flux evolutions based on radial profiles. Therefore, the SExFC model has the potential to enable rapid and physics-based predictions that can be seamlessly integrated into future real-time plasma control systems.
The effects of zonal fields on energetic-particle excitations of reversed-shear Alfvén eigenmode: simulation and theory
Authors: Chen Liu , Liu Pengfei , Ma Ruirui , Lin Zhihong , Qiu Zhiyong , Wang Wenhao , Zonca Fulvio
Published: October 2024

By employing both nonlinear gyrokinetic simulation and analytical theory, we have investigated the effects of zonal (electromagnetic) fields on the energetic particle’s (EPs) drive of reversed-shear Alfvén eigenmodes (AEs) in tokamak plasmas. Contrary to the conventional expectation, simulations with zonal fields that are turned on and off in the EP dynamics while keeping the full nonlinear dynamics of the thermal plasma indicate that zonal fields further enhance the instability drive and thus lead to a higher saturation level. These puzzling simulation results can be understood analytically in terms of the general fishbone-like dispersion relation with the correspondingly different EP phase-space structures induced by the zonal fields. Analytical expressions for the zonal fields that are beat driven by the reversed-shear AEs are also derived, and shown to be in good agreement with the simulation results.
Engineering evaluation and reflection on the operation stability of large-scale tubular pump
Authors: Wang Hao , Wang Baoluo , Cao Jiaqiao , Zhu Quanrong , Song Mengbin , Wang Chaoyue , Wang Fujun
Published: October 2024

Large-scale tubular pumps are widely used in the fields such as low-head agricultural irrigation, water diversion project and urban drainage. For this pump type, the rotation axis is perpendicular to the gravity direction, resulting in the operation instability risks induced by the constant static pressure difference. However, due to the large size of prototype pumps and the difficulty of field tests, there is currently a lack of on-site monitoring data, which makes it difficult to truly understand the actual operation of large-scale tubular pumps and to provide engineering experience with direct guidance for similar projects. To fill this research gap, this paper takes the largest shaft-well tubular pump in China as an example, and the on-site monitoring of the prototype is carried out. On the one hand, the distribution characteristics of stability indexes such as pressure fluctuations, vibrations and shaft swings are quantified, and it is proved that the performance of large-scale tubular pumps cannot be estimated only by the hydraulic model experiments. On the other hand, the potential risks to be addressed such as the phenomenon of pressure polarization oscillation, low-speed-induced dry friction of bearing shells, and the cantilever-induced bending deformation of pump shaft are reflected, which should be paid more attention to in the future development. These research results can provide valuable engineering experience for the safe and stable operation of large-scale tubulars.
Effect of volute structure on the performance of double suction centrifugal pump
Authors: Chi Gao , Chenhao Li , Xingqi Luo , Xitong Wu , Guojun Zhu
Published: October 2024

This study aims to investigate the impact of the double volute structure on the internal flow dynamics and hydraulic performance of a double-suction pump. To achieve this, a double-suction centrifugal pump was selected as the research subject, and three-dimensional turbulence numerical simulations were conducted under various working conditions using the Reynolds average method (RANS) and RNG k-ε turbulence model. The results of the simulation are compared with the experimental data, which demonstrates the validity of the numerical simulation. This study analyzes the impact of the splitter on the flow field within the volute and impeller, as well as its effect on the radial force of the impeller. The results indicate that the water flow has a significant impact on the head of the splitter, resulting in a noticeable high-pressure zone on the pressure side of the blade in close proximity to the starting end of the splitter; Under off-design conditions, a significant recirculation zone exists between the end of the splitter and the pump outlet, and it increases as the deviation from the designed condition increases; In the case of a small flow rate, the flow inhomogeneity near the starting end of the splitter is serious, and there are large zones of low speed on the outside of the splitter; The double volute structure can make the inlet velocity of the volute more evenly distributed along the circumferential direction, and can be effectively utilized to reduce the radial force exerted on the impeller, thereby improving its performance.
Application of voiceprint monitoring technology in the construction of smart pumping stations
Authors: Liu Xueqin , Guo Ziyang , Wang Yan , Zhang Rentian , Liang Yunhui
Published: October 2024

In this paper the aim is to realize the real-time monitoring of the operating status of the equipment in the smart pumping station based on the principles of voiceprint monitoring and the characteristics of the pumping stations. To achieve this aim, the data of pumping stations were firstly collected, preprocessed and the feature values were extracted. Then, the data were used to train a convolutional neural network (CNN) deep learning recognition model. Finally, a voiceprint samples database and a model library of the operating status were established and a voiceprint monitoring system for the vibration state of the pumping station equipment was constructed based on the CNN deep learning recognition model. A case study of a mixed-flow pumping station was carried out. In this case study, a voiceprint detection system was arranged on site and the operation status of the equipment can be monitored and evaluated through practical application of the system. Further, the health status of the equipment can be effectively diagnosed and evaluated, and abnormal faults can be analyzed and predicted. The results indicate that the reliability of equipment operation has improved through the application of voiceprint monitoring technology which provides an effective technical means for the construction of smart pumping stations.
Hemolysis analysis of centrifugal blood pump based on numerical simulation
Authors: Shi Suxuan , Han Jinying , Luo Yi
Published: October 2024

The operation of blood pump will cause mechanical damage to red blood cells and lead to hemolysis. Based on this, CFD technology is used to simulate the three-dimensional flow field of centrifugal blood pump. According to the analysis of velocity field, pressure field and stress field; Based on the hemolysis power function model, the hemolysis performance of blood pump is predicted by Lagrange particle tracking method, and the impeller structure is adjusted to improve its flow performance and reduce the hemolysis index. The research results can provide a basis for the structural improvement and performance improvement of centrifugal heart pump.
Design Improvement for Interventional Blood Pumps Based on Flow Analysis
Authors: Cai Zhenghao , Jian Meng , Xu Zhonghua , Zhang Mingkui , Luo Xianwu
Published: October 2024

Interventional blood pumps serve as a crucial component for temporary mechanical circulatory support in the treatment of heart failure, specifically designed to improve blood circulation recovery and survival rate in patients undergoing treatment for acute cardiovascular diseases. This study aims to design a novel interventional blood pump with a focus on achieving exceptional hydraulic performance and superior blood compatibility based on numerical simulation, which considers the interactions between the blood pump and the upstream (drainage cannula) and downstream (aorta) flow fields, establishing a full-scale flow field analysis. For the numerical method, the Reynolds-Averaged Navier-Stokes (RANS) equations coupling with the k-ɛ turbulence model are solved. The result indicates that high shear stress exists around the leading and trailing edges of impeller blades and there is a jet at the outlet of impeller, and the blade leading and trailing edge, and the outlet of the impeller are the dominant regions for higher hemolysis occurrence. It is also noted that the presence of an interventional blood pump generates significant vortex structures within the aorta. To effectively reduce the hemolysis index, back-sweep concept is applied to this study also optimize the impeller’s leading edge. The analysis result confirms that the back swept leading edge of impeller blade helps improve the blood compatibility for interventional blood pumps.
Numerical analysis of performance and internal flow characteristics of a gas-liquid multiphase rotodynamic pump
Authors: Yang Jiahang , Li Huichuang , Liang Ao , Hu Liwei , Zhang Wenwu
Published: October 2024

Inlet Gas Void Fraction (IGVF) and rotating speed are key parameters influencing the flow characteristics of gas-liquid multiphase pumps. To explore the influence of these two factors on the flow characteristics of gas-liquid multiphase rotodynamic pumps, CFD simulations were carried out based on the Euler two-fluid model to analyze the flow characteristics in an axial-flow pump at three different rotating speeds (1450 r/min, 2200 r/min, 2950 r/min) with different IGVFs. The numerical results indicate that the pump efficiency and head are first increased and then decreased with the increase of IGVF. When the IGVF is 5%, the head and efficiency reach their maximum values. This is attributed to the minimum vorticity and turbulence kinetic energy in the impeller passage at IGVF= 5%, and the small vortex range at the hub of the guide vane, thus resulting in the stable two-phase flow state in the impeller and guide vane. At the same IGVF, with the increase of the rotating speed, the head and efficiency of the multiphase pump increase accordingly. This is closely related to the smallest vortex range formed by gas-liquid flow separation at n=2950 r/min, indicating a better flow state.
Role of wall roughness on the energy performance for a mixed flow pump with tip clearance
Authors: Han Bingfu , Tan Lei , Han Yadong
Published: October 2024

This study delves into the intricate influence of wall roughness on the mixed flow pump energy performance, particularly focusing on the simultaneous presence of tip clearance. Utilizing a well-performing mixed flow pump with a tip clearance of 0.8 mm as the subject of investigation, the research employs numerical simulation at different roughness to comprehensively analyse the effects of wall roughness on pump head, efficiency, and cavitation performance. The numerical simulation employs the SST k-ω model and the equivalent sand-gain roughness model to simulate the turbulent flow account for wall roughness. The findings discerned that both head and efficiency are inversely related to wall roughness, with decrements amplified at elevated flow rates. Notably, the ‘hump’ in head performance near 60% of the design flow rate is significantly influenced by roughness beyond 31.6μm. Additionally, efficiency exhibits a minor uptick at 0.56μm roughness before a subsequent decline. The study also highlights the multifaceted impact of roughness on the internal flow structures, including vortex and cavitation patterns. These insights emphasize the importance of balancing roughness levels to enhance energy efficiency and cavitation resistance, crucial for the practical application and long-term reliability of such machinery.
Study on cavitation characteristics of a waterjet pump under off-design conditions
Authors: Zou Xingke , Guo Qiang , Huang Xianbei
Published: October 2024

Water jet pump is widely used in power field, and ordinary axial impeller is the key component of energy conversion. Because of the existence of tip clearance, the tip leakage flow through the clearance is inevitably accompanied by energy loss. Taking the axial-flow water jet pump as the research object, the condition is that the pump runs under the condition of deviating from the design condition. Considering the influence of vortex and cavitation, the improved numerical model is used to simulate the internal flow field. SST-CC turbulence model considering rotation correction and modified Zwart cavitation model based on vortex identification correction are selected. The cavitation performance and Vortex characteristics under off-design conditions are analyzed. The results show that flow loss is mainly reflected in turbulence dissipation and wall dissipation, which the turbulence dissipation and wall dissipation of impeller section account for the largest proportion. Because the cavitation area of water jet pump is mainly concentrated in the impeller, the turbulent dissipation is mainly related to the characteristics of turbulence kinetic energy and turbulent vortex. The research results can provide an effective basis for the analysis and design of axial-flow water jet pump.
Study on the inlet backflow characteristics and particle deposition of screw mixed-flow deep-sea mining pump under small flow conditions
Authors: Rennian Li , Dengxue Ma , Zhengjing Shen , Fengyi Jiang , Liuhao Liu , Wei Han
Published: October 2024

When a screw mixed-flow deep-sea mining pump operates under small flow conditions, significant backflow occurs at the impeller inlet and in the inlet pipe, which seriously affects the pump performance. To investigate this backflow characteristic, this paper presents a numerical study of the internal flow field of the mining pump based on the CFD-DEM coupling method. The flow state at the impeller inlet, the velocity distribution law in the inlet pipe, and the particle motion state under the flow rate condition of 0.52Qd
are obtained. The results show that, when the pump operates under small flow conditions, the leakage from the tip gap of the impeller head causes a screw high-speed backflow with the same rotation direction as the impeller on the wall of the inlet pipe. The backflow intensity attenuates as it propagates towards the pump inlet. The backflow mixes with the main flow in the middle of the pipe and reaches a balanced state, which causes the particles to deposit here. The deposition process can be divided into a formation stage and a stable stage. When the particles in the middle of the pipe reach the stable stage, their shape and position become stable. The velocity pulsation of the monitoring points near the wall is periodic, and its pulsation frequency is the same as the impeller rotation frequency.
Jet centrifugal pump internal flow numerical simulation and structural optimization
Authors: Mao Weibin , Ge Jie , Ren Bing , Gui Jianhui , Yang Xuelong
Published: October 2024

Jet centrifugal pump is essential equipment in multiple systems such as agricultural irrigation and energy production. This paper investigates the internal flow characteristics of jet centrifugal pumps at different flow rates and the cavitation behavior under high flow conditions by numerical simulation methods. Additionally, two performance optimization strategies are proposed based on simulation results. The findings indicate that high-velocity regions and low-pressure zones exist within the nozzle. As flow rate increases, the outlet velocity of the nozzle gradually decreases, and large areas of low pressure are observed near the inlet of the impeller. Cavitation occurs to varying degrees at flow rates of 4.056 m3/h and 3.840 m3/h. The turbulent kinetic energy contours for these conditions reveal uneven distribution within the jet nozzle, with higher values near the jet mixing layer, inner wall of the jet nozzle and impeller inlet. Structural optimization using hemispherical bolts significantly reduces the turbulent kinetic energy around the bolts, resulting in an increase in head ranging from 1.68% to 6.70% across various flow rates. Shortening the clearance between the impeller and the rear cover reduces energy losses, leading to an increase in head ranging from 2.72% to 5.86%.
Solid-liquid flow characteristics of twin-screw pump under solid-containing transportation
Authors: Wang Zhenhao , Sun Shuaihui , Guo Pengcheng , Ma Jinyang
Published: October 2024

Twin-screw pumps have the wear risk when the fluid contains particles. In order to clarify the flow characteristics of the twin-screw pump under solid-containing transportation, the solid-liquid flow characteristics research on a twin-screw pump are carried out using numerical simulation and experimental methods in this paper. The results show that the particle concentration has a small effect on the volumetric efficiency and hydraulic efficiency of the twin-screw pump under each differential pressure, but the presence of particles could increase the volumetric efficiency limitedly. The velocity of main flow and the turbulent kinetic energy have been restrained by the particles in the tooth chamber, and the inhibition phenomenon is more significant with the increase of particle concentration. The particles in the tooth chamber are inhaled by the leakage flow at the tooth-tip clearance. Some particles hit the tooth-tip and cause the abrasion, others flow into the tip clearances, which decreases the leakage flow velocity and results in a higher volumetric efficiency than that of the pure-liquid condition. The results of the study will provide a theoretical basis for the study of solid-containing transportation and particle wear in twin-screw pumps.
Numerical Study on Pressure Fluctuation in Electric Coolant Pump
Authors: Zhang Lin , Zhu Dongdong , Gu Yandong , Zhou Zhiqiang , Ouyang Xili , Bian Junjie
Published: October 2024

Adjusting the flow rate of an electronic coolant pump (ECP) over a wide range can cause significant internal pressure fluctuations, leading to vibration and noise. This study uses numerical simulation to compare pressure fluctuations at the backflow orifice and within the impeller of an ECP at various flow rates. The backflow creates periodic disturbances in the impeller inlet region. As the flow rate increases, the axial influence range of the backflow on the impeller inlet decreases, reducing the amplitude of pressure fluctuations by up to 7.9%. The characteristic frequencies of pressure fluctuations at the backflow orifice include the blade passing frequency and its first harmonic. Within the impeller, the pressure fluctuation amplitude increases with both flow direction and flow rate, with characteristic frequencies encompassing the rotational frequency, BPF, and its first harmonic. At low flow rates, the overall variation of pressure fluctuations inside the impeller shows an opposite trend compared to design and high flow rates. The impact of the rotational frequency on pressure fluctuations inside the impeller is significantly smaller at the design flow rate than at other flow rates. This study offers insights that can help optimize ECP design and enhance their operational performance.
Analysis of submersible axial flow pump fitted with variable IGV at design and off-design conditions
Authors: Sonawat Arihant , Hwang Do-Hyun , Kim Youn-Sung
Published: October 2024

Submersible axial flow pump is capable of generating large flow rate at high efficiency and is widely used in agriculture, irrigation, water supply and drainage in factories, urban areas, etc. Pumps are always designed to operate at the designed conditions of flowrate and head, but in certain practical applications, their off- design operation seems to be more important, like if there is waterflooding due to heavy rainfall or in case of variable flowrate, variable head operations or long-distance water supply. These situations arise for limited operation (time) and hence it is not economical to change the existing pumping system. The present work deals with the analysis of submersible axial flow pump at design as well as off-design conditions. This off-design operation was controlled by the variable inlet guide vane (VIGV) with the task of making it energy efficient for all conditions. The scope of this work was to investigate the performance of selected pump at designed rotational speed, at designed flowrate (Q/Qd
=1) as well as Q/Qd
=0.8 and Q/Qd
=1.2, using Computational Fluid Dynamics (CFD) and at various VIGV angles in the range of ±25°. The fluid flow analysis was performed using commercial CFD tool ANSYS CFX v17.0. From the numerical study, it was concluded that the performance of the considered AFP significantly increased due to the presence of VIGV at positive rotation angles. The best performance was observed for IGV angle of +25° for all flowrates. As compared to the reference case of 0° IGV rotation, the performance of the AFP increased by 28.42% in terms of head ratio and 0.235% in terms of hydraulic efficiency, for +25° IGV angle, at the designed flowrate. Also, an increment of 69.05% in terms of head ratio and 14.49% in terms of hydraulic efficiency was observed at overload condition of Q/Qd
=1.2.
Signals denoising of leakage pressure in water supply pipelines using an improved wavelet filter algorithm
Authors: Wu Luochang , Wang Sai , Yan Jianguo
Published: October 2024

Accurate identification of leakage pressure signal is crucial for leakage detection and location of water supply pipelines. However, there is a lot of noise signals in the negative pressure waves generated during leakage accidents, making it difficult to identify leakage signals, and thus seriously affecting the accuracy of leakage detection. Therefore, in this study, we carried out leakage test of water transmission pipeline on our self-built test platform for transient flow with long-distance water transmission pipeline (pipeline length is 160 m, and diameter is 100 mm), and obtained the transient leakage pressure signals under various flow rates (15–55 m3/h). An improved wavelet filtering algorithm was proposed to filter the leakage pressure signal by optimizing the calculation of decomposition layers and the threshold processing strategy, and then compared with the traditional wavelet filtering method. The results show that the improved algorithm can denoise the leakage signals effectively, and the signal-to-noise ratio (SNR), mean square error (MSE) and mean absolute percentage error (MAPE) are all superior to those of the traditional wavelet algorithm. The results can provide support for leakage detection and location of water supply pipeline systems.
The Optimization Strategy of Pump-Valve Combined Scheduling and Pump Unit Reselection in Heating Systems
Authors: Li Chen , Qiu Baoyun , Yan Tianxu , Wang Huijie , Zhao Fangling , Qi Guipeng
Published: October 2024

This research successfully implemented time and spatial division control for residential heating through theoretical analysis and optimization, with the goal of meeting occupants’ comfort requirements and achieving energy savings and emissions reduction. Firstly, the investigation calculated the optimal heating capacity for different functional areas within the buildings at various times. Secondly, by considering the heat transfer characteristics of the heating system, as well as pipe and valve resistance properties, and the performance of the centrifugal pump, the research established a system heat balance equation and a combined system hydraulic balance equation incorporating frequency conversion and valve adjustment to meet precise heating demands. Finally, the investigation reselected the pump based on the actual flow rate and head of the pump station unit. The heating optimization calculations were applied to a residential building in Zhengzhou, revealing that the combined optimization of frequency conversion and valve adjustment, along with the optimized selection of pump station units, resulted in energy consumption savings of 38% and 33% reduction in heating output compared to the original design. The overall operating costs were correspondingly reduced by 32%. Thus, this research suggests that optimizing the heating system through the joint adjustment of pumps and valves can achieve energy efficiency while delivering precise heating to fulfill occupants’ comfort requirements.
Study on Fault Prediction Method of Hydropower Equipment Based on Equipment Health State Detection
Authors: Sun Y X , Zhao X
Published: October 2024

With the continuous development of China’s electric power industry, the installed capacity of power plants is increasing, and hydropower units are developing in the direction of large capacity and high efficiency. As the complexity of the equipment is getting higher and higher, different equipment are more and more different, showing different characteristics when faults occur, which puts forward higher requirements for the safe and stable operation of hydropower units. In response to the above problems, this paper develops a set of human-machine closed-loop remote fault diagnosis reasoning machine system with self-learning function and a set of equipment health state monitoring and prediction system. This remote fault diagnosis system reasoning machine system can reduce the cost of unit equipment fault diagnosis, improve the diagnosis efficiency, and ensure the safe, stable and economic operation of the unit.
Numerical and experimental examination of performance curve instabilities of a centrifugal fan
Authors: Förster S , Neff F , Nikolajew E , Sterle L , Baum A , Kunz J , Böhle M
Published: October 2024

This paper investigates the performance curve instability of centrifugal fans used in industrial applications such as sintering or pelletizing plants. The study focuses on experimental and numerical analyses of the fan’s performance curve during operation. Model measurements of an optimized fan reveal instabilities in the characteristic curve around 73 % and 42 % of the volume flow at best efficiency point (Q/Qref) resulting in a sudden drop in pressure coefficient and the onset of low-frequency noise emission. Numerical investigations using ANSYS CFX predict the flow pattern accurately. Excellent agreement is observed between measured and calculated data for flow conditions, with deviations below 1 % in pressure coefficient. Notably, the calculated instability range occurs earlier at lower flow rates, leading to a 6 % shift in the data. The flow exhibits a detachment zone on the blade suction side and a complete blockage of a single impeller passage, corresponding to the pressure drop in the performance curve. Further investigations reveal that rotor-stator interaction causes the abrupt impeller rotating stall phenomena, significantly impacting pressure generation at lower flow rates. A FFT analysis confirms the presence of rotating stall, with its dominant frequency observed and multiple harmonics. The comparison of separation frequency with existing literature supports the assumption that rotating stall is the cause of the instability.