bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study on the influence of sediment erosion of Francis turbine runner under different water heads
Authors: Wang Jinliang , Wang Jiabing , Wang Zhengwei 
Published: October 2024

Abstract
The average measured sediment concentration of the river section where Wanjiazhai Hydropower Station is located over the years is 5.7kg/m 3, The maximum measured sediment concentration reaches 37.6kg/m 3, The erosion of the flow components of hydraulic turbines caused by sand containing water flow is becoming increasingly severe, coupled with the frequent impact of load changes during peak shaving operation, the problems exposed during the operation of hydraulic turbines are becoming more prominent, which affects the stable operation of the units. This article uses numerical simulation and experimental testing to study the sediment wear characteristics and hydraulic performance of the water turbine at Wanjiazhai Hydropower Station. Research has revealed the effects of working head on impeller wear. The increase in working head will exacerbate the impact wear on the main channel wall of the unit. The surface of water turbine blades is the main wear area, and the high-speed impact of particles causes an increase in the wall wear rate. The probability of particles coming into contact with the wall at the outlet increases, resulting in rapid wear at this point. The increase in head will intensify the wear intensity of the unit surface, and the flow velocity in the gap indicates that the local high-speed jet in the gap is the main cause of gap wear. Therefore, in order to ensure the efficient anti-wear performance of the water turbine, multiple factors need to be comprehensively considered to cope with sediment wear of the water turbine, including regular cleaning, optimized structural design, use of wear-resistant materials, replacement of worn parts, and optimization of operating parameters. These measures help to reduce the damage of sediment wear to water turbines and extend their service life.
Optimization and Regulation Method for Large Blade-regulating Pump Stations Considering Safety Constraints
Authors: Tan Yuxiang , Liang Yunhui , Qian Lihua , Yuan Zhibo 
Published: October 2024

Abstract
In plain areas, making flood control and drought resistance a heavy task. Large water pumping stations undertake the important task of water lifting and scheduling. Due to the physical characteristics of large pumping stations, they are often affected by the upstream and downstream water levels during water lifting scheduling, resulting in low head operating conditions. Low head operating conditions can easily cause pumping stations to operate at excessive power, thereby affecting the health of pumping station equipment. Based on the head efficiency curve of a large blade regulating pump station in this article, by optimizing the regulating mathematical model and considering constraints such as water level, flow rate, power, efficiency, and blade angle adjustment time interval under low head conditions, a dynamic programming calculation method is adopted to construct an optimized regulating method for the pump station. Based on real-time water level, various operating data of the unit are optimized to ensure the blade angle, power, and the flow rate and other parameters are all within the safety constraint range. And various operating data could be used to guiding the real-time optimization and adjustment of the pumping station, and additionally providing the operating foundation for the intelligent pumping station.
Numerical study on unsteady characteristics of backflow vortex cavitation in an axial flow pump
Authors: Cai Shuting , Huang Renfang , An Yi , Wang Yiwei , Li Ning 
Published: October 2024

Abstract
Axial pumps play a crucial role in various industries such as agriculture, construction, and chemical engineering, exhibiting optimal efficiency under design conditions. However, in practical applications, these pumps often operate under off-design conditions due to environmental constraints, which would lead to a series of problems such as increased vibration, elevated noise levels, and a shortened pump lifespan, thereby endangering its safe and stable operation. This study addresses the issue by using a modified RNG k-ε turbulence model combined with the Zwart cavitation model to simulate the cavitation characteristics of an axial-flow pump. The calculated cavitation characteristics are consistent with the experimental results, proving the exactitude of the numerical approach. A noteworthy observation is the severe cavitation occurrences at the backflow vortex, termed backflow vortex cavitation. This phenomenon undergoes inception, development, and eventual collapse constantly. According to the severity of the backflow vortex cavitation, different periods are divided into the bimodal stage and small-peak stage. Significantly, it is identified that the backflow vortex cavitation interacts with the impeller blades, as the impeller moves, thereby inducing blade vibration, and noise, and exacerbating cavitation erosion. The research results offer a theoretical foundation that is beneficial to enhancing the safe and stable operation of axial flow pumps.
Study on the Performance of Pressure Balance Pipe of Pump-turbine
Authors: Liu Jiayi , Zhang Fei , Zhu Baoshan , Chen Zhenmu 
Published: October 2024

Abstract
For pump-turbine, axial water thrust can cause damage to the unit. It is important to realise automatic levelling by using pressure balance pipe. To study the influence of the pressure balance pipe on the performance of the reversible pump-turbine, axial water thrust and pressure fluctuation have been carried out for reversible pump-turbine with different guide vane opening and different operating heads by numerical and experimental analysis. The unsteady simulation results for the full flow channel of the pump-turbine show that the 298 mm guide blade opening meets the test standards of flow and power. Furthermore, CFD tests were carried out for different water heads at 298mm guide vane opening. At last, under the typical working conditions of 298mm guide vane opening and 400 m water head, pressure fluctuation, the axial water thrust in the vaneless zone are analyzed.
Wear Measurement of a Francis Runner damaged by sediment erosion: A case study
Authors: Poudyal Atmesh , Neopane Hari Prasad , Chitrakar Sailesh 
Published: October 2024

Abstract
Hydropower is one the biggest sources of electricity all over the world and the largest by far in Nepal. Francis Turbines are extensively used in hydropower plants due to flexible ranges of head and discharge. Sediment erosion has been a major cause of damage and efficiency reduction in Francis Turbine components. As a stepping stone towards making erosion resilient turbine components, the measurement of wear due to erosion is essential. This study was conducted on the 35 MW Francis Runner installed at the Middle Marsyangdi Hydro Power Station of Nepal. The Runner was found to be heavily damaged after three years of continuous operation. The approach of measuring wear at various sections of the Runner using basic hand tools was adopted. The outer wearing rings on both the hub and shroud sections were found to be substantially reduced in diameter due to erosion, correlating to typical side wall erosion occurring in Francis Turbines. Substantial erosion was found on the blade inlets at both the hub and shroud sections, correlating to typical leakage gap erosion from the guide vanes. Substantial cavitation wear was found at the suction side of the blades at both the inlet and outlet of blades as well as at the wearing rings on both the hub and shroud sections. The wear on blades was found to be substantially higher at the outlet of the Runner with all 13 blades cracked at the outlet. The eroded mass of the Runner calculated through volumetric analysis was found to be 294 kg. The result was compared to the mass obtained by using a weight scale before and after the restoration of the Runner at a commercial workshop and a 5.16 % error was obtained which seems acceptable considering the simplicity of the process. The cost estimation for repairing the damaged Runner was also done based on the obtained result of eroded mass.
Three-dimensional modelling and numerical analysis of Pelton turbine runner buckets
Authors: Wang H B , Li D Y , Fu X L , Gong R Z , Wang H J 
Published: October 2024

Abstract
The Pelton turbine, a hydraulic prime mover, harnesses high-pressure water jets’ kinetic energy to drive the rotation of its runner buckets, converting water energy into mechanical energy. Due to its straightforward design and applicability in high to super high head scenarios, it has been a mainstay in power stations for many years. The bucket, a critical component of the Pelton turbine’s runner, plays a pivotal role in the unit’s performance. Using Non-Uniform Rational B-Splines (NURBS) to develop a parametric water bucket model enhances adaptability. Also, performing unsteady numerical simulations on the model analyses its hydraulic characteristics and flow state distribution. The numerical calculations fundamentally capture the unsteady flow conditions within the rotating buckets, with the results of the flow pattern distribution largely aligning with those documented in existing research. This provides a reference for enhancing the hydraulic performance of Pelton turbine runners.
Study on Internal Flow Characteristics and Pressure Pulsation Features of Pump-Turbine under the no-load Startup Condition with Different Heads
Authors: Dong Haiyang , Lu Yonggang , Wang Long , Liu Zhiwang , Mei Xiang , Zhang Shuaishuai , Wang Zhengwei 
Published: October 2024

Abstract
Unstable operation during the no-load startup of pumped storage hydroelectric power plants is a significant factor affecting the successful grid connection of units. To investigate the internal flow and pressure pulsation characteristics during the no-load startup of pump-turbine under varying heads, the vertical single-stage mixed-flow reversible pump-turbine is studied. Numerical simulations are performed using the SST k-ω turbulence model, and the Fast Fourier Transform (FFT) method is employed to analyze the pressure pulsation signals. A comparative study is conducted on the pressure pulsation characteristics and internal flow features at different positions under various heads. The results indicate that the pressure pulsation in the draft tube cone region is the most severe, with the dominant blade passing frequency (fBPF
) and its harmonics caused by rotor-stator interaction (RSI) in the spectra of pressure pulsations at various heads in the draft tube cone region. Additionally, the pressure pulsation amplitude increases as the head decreases, while low-frequency pulsation signals are prevalent throughout the entire flow passage. Compared to the flow condition, the influence of rotor-stator interaction on pressure pulsation is more significant. During the no-load startup at the highest head, the pump-turbine exhibits the most vortex structures and the poorest flow condition, while the intensity of pressure pulsation in the draft tube cone region is the lowest. These research findings provide a basis for the stable no-load startup of pump-turbine.
Analysis of Aerostatic Performance of a Flexure Pivot Tilting Pad Air Journal Bearing
Authors: Zhong Yi , Böhle Martin 
Published: October 2024

Abstract
Aerostatic performance of a flexure pivot tilting pad air journal bearing is examined with several numerical simulation under various working conditions. The air pressure distribution in the bearing clearance is obtained by solving the Reynolds equation with the finite difference method (FDM). The code consists of 3 main parts: mass flow rate equilibrium, moment equilibrium, and shaft equilibrium. They are used to study the gas pressure at the downstream of the nozzles, the motion of pads, and the position of the shaft in the bearing, respectively. Code accuracy is verified by comparing the results with those in other articles. This work lays the foundation for future research.
Numerical study of the influence of structural parameters on the performance of annular ejector
Authors: Liu Kang , Cao Zhengqing , Fang Kaiyue , Zhang Xinchen , Yang Xuelong 
Published: October 2024

Abstract
Compared with the central ejector, the annular ejector is widely used in refrigeration, coal mining and chemical industry because the working fluid enters the suction chamber through the annular nozzle, the contact area with the ejection fluid increases, and the ejection fluid does not need to change the flow direction. In order to solve the problem of low performance of annular gas ejector, this paper designs an annular gas ejector with reference to the relevant model, and the axial length and suction angle of the mixing tube of the annular gas ejector are mainly studied. The results show that there is an optimal value for the length of the ring gas ejector mixing tube, and the length of the mixing tube is too long or too short is not conducive to the gas extraction of the ring gas ejector. Under the same annular gap, with the increase of the jet angle, the amount of gas consumed in the primary stream does not change much, and the gas to be pumped decreases, resulting in the performance of the annular gas ejector being reduced, which is not conducive to the suction of the ejector.
Fluid-Solid coupling analysis of PTFE impeller in hydraulic turbines for sewage resource utilization
Authors: Wang Shenghui , Kou Jiawen , Luo Xianwu , Xiao Yexiang , Wang Chengpeng , Li Jiacheng 
Published: October 2024

Abstract
Hydraulic turbines, vital energy-saving devices, convert pressure energy from liquid fluids into mechanical energy. As wastewater resource utilization and zero discharge industries proliferate, relevant research is of great interest. In order to design a suitable medium and low pressure hydraulic turbine for industrial water treatment, we conducted a study analyzing the stress and strain characteristics of a PTFE turbine impeller by means of bi-directional fluid-structure coupling numerical simulation. Our findings suggest that the impeller’s maximum equivalent stress and maximum deformation fall within acceptable material limits, with stress concentration at the blade-cover plate interface. The blade experiences maximum deformation at its midpoint due to high liquid pressure on the volute periphery. Fluid solid coupling reduces the maximum equivalent stress of the impeller by about 1.65MPa and the maximum deformation of the blade by about 0.05mm. The equivalent stress at the sampling point fluctuates periodically, with a significant change in stress amplitude at the sampling point of the cover plate on one side of the support surface, increasing susceptibility to fatigue damage.
Capacitor State Monitoring of MMC Photovoltaic Grid Connected Inverter Based on Capacitance Voltage Difference
Authors: Guo Xiaoxuan , Sun Huijie , Zhou Milu 
Published: October 2024

Abstract
Due to the high degree of modularity and high energy transmission efficiency, MMC is widely used in the field of photovoltaic grid connection. This paper focuses on the abnormal fluctuations of capacitor voltage caused by capacitor aging in MMC submodule, and comes up with a capacitance monitoring method based on the voltage fluctuation difference of submodule capacitors. The validity of the raised method is validated through simulation and experiments.
A video speed measurement method for UAV targeting ground targets based on kalman filtering
Authors: Wu Yuxin , Zhang Zhilong 
Published: October 2024

Abstract
Measuring the velocity information of moving targets, as an application scenario for drone target velocity measurement, is an important focus in the process of drone intelligence reconnaissance. To improve the speed and accuracy of unmanned aerial vehicles (UAVs) in locating and measuring moving targets, a reliable target localization and velocity model based on UAV reconnaissance video frames and Kalman filtering is proposed. This algorithm model can complete the localization and velocity measurement tasks of moving targets under complex conditions without the need to obtain ranging information from drones. To verify the algorithm, the Monte Carlo simulation method was used for simulation experiments. The experimental results show that the error of this velocity measurement algorithm can meet the accuracy requirements of unmanned aerial vehicles for ground-moving targets.
Orientation method based on lunar hour angle
Authors: Wang Zhihui , Ding Xiaoqiu , Wang Fangcao , Xu Shunfu 
Published: October 2024

Abstract
Astronomical orientation is a crucial technique for obtaining high-precision azimuths. However, at night, this often relies on the North Star, which can be challenging to locate and identify. An orientation method is proposed based on the lunar hour angle as an alternative. By applying theories from astronomy and geodesy, we conduct an in-depth study of the key points and calculation steps for using a theodolite to measure the moon. By observing the moon’s edge and center and combining this with the observer’s geographic location and observation time, we calculate the lunar hour angle to determine the true north azimuth. To improve computational efficiency, an application has been developed to assist with observation and data processing. Practical applications and tests have validated the feasibility and effectiveness of this lunar hour angle-based orientation method. This method addresses the limitations of traditional North Star orientation, offering an efficient and convenient approach to orientation.
APMP Pilot Study on High Transmittance Haze
Authors: Liu Wen-Chun , Koo Annette , Molloy Ellie , Wu Houping , Leecharoen Rojana , Zhang Jing , Liu Yuanjie , Suryani Dini , Yu Hsueh-Ling 
Published: October 2024

Abstract
This article presents the results of the Asia Pacific Metrology Programme (APMP) pilot comparison on high transmittance haze (TH), specifically TH >40 %. Various methods, including ASTM D1003, ISO 14782, the double beam method, and the double compensation method were employed. The results revealed that ASTM D1003 is still influenced by failure to compensate for sphere throughput, even in high TH artefacts. In contrast, the other methods exhibit good consistency, as expected. This article also analyses the total transmittance (TT) and diffuse transmittance (DT) obtained using the double compensation method, theoretically capable of determining accurate TT, DT, and TH, discussing the possibility of inconsistency in the reflectance between the sphere wall and the white plate affecting the agreement.
Characterisation of an LED-based integrating sphere source for detection of changes of AERONET Europe radiometers
Authors: Schwind K.M. , Nevas S. , Sperfeld P. , Pape S. 
Published: October 2024

Abstract
Within the framework of the EMPIR project 19ENV04 MAPP “Metrology for aerosol optical properties” an LED-based source was built for monitoring responsivity changes of Cimel filter radiometers from the AERONET Europe network. The developed LED device was flanged to integrating spheres to fill the field of view of the radiometers. Here we present the characterisation results of the LED-based integrating sphere source. The spectra of the radiant flux leaving a BaSO4-based integrating sphere showed positive wavelength dependent drift, which had not been reported in literature yet and did not appear by using incandescent lamps with the integrating spheres. This report shows approaches to reduce such drifts and an alternative using a PTFE-based integrating sphere, which was also tested for stability, reproducibility and homogeneity.
Innovative design of hole-carrying materials utilizing spiro-OMeTAD for halide hybrid perovskite solar cells
Authors: Yang Li , Zhao Liqian , Cai Liyun , Miao Jinniu , Qu Yandong , Guo Huiying , Yang Mingming , Du Peng 
Published: October 2024

Abstract
During the enhancement of photovoltaic conversion efficiency of perovskite cells, the study of hole transporting materials that match them is crucial. This work uses quantum mechanical calculation methods to systematically study 40 spiro [fluorene-9,9’-xanthene] (SFX) and spirobixanthene (SBX) spiro-core structure molecules designed based on spiro-OMeTAD as research objects. It systematically studies the effects of heteroatoms, methoxy and diphenylamine substitutions at different positions on the geometric conformation, molecular orbitals and energy levels, molecular reorganization energy, and UV-visible absorption spectra of all designed molecules. Based on the above research, the objective of this research is to furnish theoretical guidance for the design and development of hole transporting materials that can match various new types of perovskite materials.
Effect of different heat inputs on the microstructure and mechanical properties of the laser welded joint of CLF-1 steel
Authors: Shi Haicheng , Zhang Guoyu , Cao Dongxu , Li Wuhong , Xu Guojian 
Published: October 2024

Abstract
In this study, we examined the effects of various heat inputs on the microstructure and mechanical properties of the laser-welded joints of CLF-1 low-activation ferritic/martensitic steel medium-thick plates, which are used in the Test Blanket Module (TBM). The results indicate that under four different welding heat inputs (2727 J/cm, 3000 J/cm, 3563 J/cm, and 4500 J/cm), the weld microstructure is primarily composed of a large amount of lath martensite and a small amount of δ-Fe. As the heat input increases, the average width of lath martensite in the weld microstructure progressively increases, while the average volume fraction and width size of δ-Fe experience a significant increase. When the heat input surpasses 3563 J/cm, δ-Fe exhibits a dense aggregation. The tensile properties of the joints created under different heat inputs are superior to those of the base material. At the lowest heat input, the maximum impact toughness of the weld reaches 40 J.
Mechanical and electrical properties of two-dimensional BN doped with carbon group elements: first-principles calculations
Authors: Liu Heng , Xing Mengjiang , Fan Qingyang 
Published: October 2024

Abstract
Research of low-dimensional nanomaterials provides a direction for solving the problems of energy and environmental pollution. In this work, the regulation mechanism of doping carbon group elements X (X = C, Si, Ge, Pb, Sn) on mechanical and electrical properties of 2D monolayer BN are investigated by first-principles calculations. Two doping sites were selected, replace B atoms (B15N16X) or N atoms (B16N15X). Lower relative enthalpies and the elastic constants, which conforming to the mechanical stability standard, fully prove the stability of the doping system. Compared with B15N16X, B16N15X has larger structural distortion, smaller elastic constants and modulus, and is more inclined to ductility. With the increase of atomic radius, the deformation degree increases and the elastic parameters decrease. C-doped by replacing B atoms improves the elastic mechanical properties of monolayer BN. Sn-doped and Pb-doped modulate the monolayer BN into ductility. More importantly, all doped configurations exhibit magnetism. The indirect band gap of the undoped system can also be modulated into a direct band gap, B15N16C, B16N15Si and B16N15Ge all have direct band gaps in the spin-down direction. Asymmetric impurity energy levels DOS further verify the magnetism of the reference system.