bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental verification of guided-wave lumped circuits using dielectric rod
Authors: Wang Kun , Zhang Xuchun , Wang Zanyang , Shi Haoyang 
Published: June 2024

Abstract
This paper presents a method to realize equivalent lumped inductance/capacitance by adjusting the relative permittivity, diameter, and offset of the dielectric rod. The dielectric rod is used to replace the traditional reactance matching elements (metallic diaphragm, pin, and resonant window) in the substrate integrated waveguide, which avoids the problem of short circuit in the upper and lower metal plate of the substrate integrated waveguide, and has the advantage of high regulatory freedom, low radiation loss, and low crosstalk. Based on this method, three air rod filters are designed and verified by experiments. The three filters are designed based on the diameter and offset of a single dielectric hole and the offset of symmetrical dielectric rods. Compared with conventional filters, this method greatly adjusts the degree of freedom of media regulation in the substrate integrated waveguide. The experimental results are in good agreement with theoretical analysis and simulation results. It provides an effective platform for the design of substrate integrated waveguide functional lumped circuits.
A density functional theory study of CO oxidation on single-atom Zn supported on PtX2 (X = S, Se, Te)
Authors: Chen Sainan , Zhang Xilin , Kang Wenli , Li Xiaodong , Yang Zongxian 
Published: June 2024

Abstract
CO oxidation on Zn doped Platinum-based transition metal sulfides (Zn/PtX2, X = S, Se, Te) was systematically explored by density functional theory calculations. The geometric stability, electronic structure and catalytic properties of the three Zn/PtX2 catalysts were studied. CO oxidation on Zn/PtX2 along the Langmuir–Hinshelwood and Eley-Rideal mechanisms has been comparatively demonstrated. It is found that surface defect can stabilize Zn single atom, and the oxidation of CO on Zn/PtX2 is facilitated along the Langmuir–Hinshelwood mechanism. The dissociation of OOCO intermediate of Zn/PtSe2 catalyst is the rate-limiting step with an energy barrier of 0.27 eV. This work demonstrates that Zn single atoms on suitable substrate possess satisfied CO oxidation activity.
Prospects for weighing neutrinos in interacting dark energy models using joint observations of gravitational waves and γ-ray bursts*
Authors: Feng 冯 Lu 露 , Han 韩 Tao 涛 , Zhang 张 Jing-Fei 敬飞 , Zhang 张 Xin 鑫 
Published: June 2024

Abstract
Cosmological observations can be used to weigh neutrinos, but this method is model-dependent, with results relying on the cosmological model considered. If we consider interactions between dark energy and dark matter, the neutrino mass constraints differ from those derived under the standard model. On the contrary, gravitational wave (GW) standard siren observations can measure absolute cosmological distances, helping to break parameter degeneracies inherent in traditional cosmological observations, thereby improving constraints on neutrino mass. This paper examines the constraints on neutrino mass within interacting dark energy (IDE) models and explores how future GW standard siren observations could enhance these results. For multi-messenger GW observations, we consider the joint observations of binary neutron star mergers by third-generation ground-based GW detectors and short γ-ray burst observations by missions similar to the THESEUS satellite project. Using current cosmological observations (CMB+BAO+SN), we obtain an upper limit on the neutrino mass in the IDE models of 0.15 (or 0.16) eV. With the inclusion of GW data, the upper limit on the neutrino mass improves to 0.14 eV. This indicates that in the context of IDE models, the improvement in neutrino mass constraints from GW observations is relatively limited. However, GW observations significantly enhance the constraints on other cosmological parameters, such as matter density parameter, the Hubble constant, and coupling strength between dark energy and dark matter.
Cross section measurement for the 232Th(n, f ) reaction in the 4.50−5.40 MeV region using a time projection chamber*
Authors: Bai 白 Haofan 浩帆 , Yi 易 Han 晗 , Sun 孙 Yankun 艳坤 , Hu 胡 Yiwei 益伟 , Liu 刘 Jie 杰 , Wu 邬 Zepeng 泽鹏 , Xia 夏 Cong 聪 , Ren 任 Wenkai 文凯 , Cao 曹 Wentian 文田 , Fan 樊 Tieshuan 铁栓 , Zhang 张 Guohui 国辉 , Fan 樊 Ruirui 睿瑞 , Li 李 Yang 样 , Jiang 蒋 Wei 伟 , Chen 陈 Yonghao 永浩 , Lv 吕 You 游 , Ning 宁 Changjun 常军 , Jia 贾 Weihua 伟华 , Zhang 张 Zhiyong 志永 , Chen 陈 Haolei 昊磊 , Chen 陈 Zhen 朕 , Zhao 赵 Maoyuan 懋源 , Feng 封 Changqing 常青 , Liu 刘 Shubin 树彬 
Published: June 2024

Abstract
Accurate cross sections of neutron induced fission reactions are required in the design of advanced nuclear systems and the development of fission theory. Time projection chambers (TPCs), with their track reconstruction and particle identification capabilities, are considered the best detectors for high-precision fission cross section measurements. The TPC developed by the back-streaming white neutron source (Back-n) team of the China Spallation Neutron Source (CSNS) was used as the fission fragment detector in measurements. In this study, the cross sections of the 232Th(n, f) reaction at five neutron energies in the 4.50−5.40 MeV region were measured. The fission fragments and α particles were well identified using our TPC, which led to a higher detection efficiency of the fission fragments and smaller uncertainty of the measured cross sections. Ours is the first measurement of the 232Th(n, f) reaction using a TPC for the detection of fission fragments. With uncertainties less than 5%, our cross sections are consistent with the data in different evaluation libraries, including JENDL-4.0, ROSFOND-2010, CENDL-3.2, ENDF/B-VIII.0, and BROND-3.1, whose uncertainties can be reduced after future improvement of the measurement.
Comparative analysis of jet and underlying event properties across various models as a function of charged particle multiplicity at 7 TeV*
Authors: Waqar Maryam , Alrebdi Haifa I. , Waqas Muhammad , Al-mugren K.S. , Ajaz Muhammad 
Published: June 2024

Abstract
In this study, a comprehensive analysis of jets and underlying events as a function of charged particle multiplicity in proton-proton (pp) collisions at a center-of-mass energy of

TeV is conducted. Various Monte Carlo (MC) event generators, including Pythia8.308, EPOS1.99, EPOSLHC, EPOS4

, and EPOS4

, are employed to predict particle production. The predictions from these models are compared with experimental data from the CMS collaboration. The charged particles are categorized into those associated with underlying events and those linked to jets, and the analysis is restricted to charged particles with

and

GeV/c. By comparing the MC predictions with CMS data, we find that EPOS

, EPOSLHC, and Pythia8 consistently reproduce the experimental results for all charged particles, underlying events, intrajets, and leading charged particles. For charged jet rates with

GeV/c, EPOS4

and Pythia8 perform exceptionally well. In the case of charged jet rates with

GeV/c, EPOSLHC reproduces satisfactorily good results, whereas EPOS4

exhibits good agreement with the data at higher charged particle multiplicities compared to the other models. This can be attributed to the conversion of energy into flow when "Hydro=on," leading to an increase in multiplicity. The EPOSLHC model describes the data better owing to the new collective flow effects, correlated flow treatment, and parameterization compared to EPOS1.99. However, the examination of the jet

spectrum and normalized charged

density reveals that EPOS4

, EPOS4

, and EPOSLHC exhibit good agreement with the experimental results, whereas Pythia8 and EPOS1.99 do not perform as well owing to the lack of correlated flow treatment.
The FRB-searching Pipeline of the Tianlai Cylinder Pathfinder Array
Authors: Yu Zijie , Deng Furen , Sun Shijie , Niu Chenhui , Li Jixia , Wu Fengquan , Wang Wei-Yang , Wang Yougang , Zuo Shifan , Shu Lin , Hao Jie , Liu Xiaohui , Ansari Reza , Pen Ue-Li , Stebbins Albert , Timbie Peter , Chen Xuelei 
Published: June 2024

Abstract
This paper presents the design, calibration, and survey strategy of the Fast Radio Burst (FRB) digital backend and its real-time data processing pipeline employed in the Tianlai Cylinder Pathfinder Array. The array, consisting of three parallel cylindrical reflectors and equipped with 96 dual-polarization feeds, is a radio interferometer array designed for conducting drift scans of the northern celestial semi-sphere. The FRB digital backend enables the formation of 96 digital beams, effectively covering an area of approximately 40 square degrees with the 3 dB beam. Our pipeline demonstrates the capability to conduct an automatic search of FRBs, detecting at quasi-real-time and classifying FRB candidates automatically. The current FRB searching pipeline has an overall recall rate of 88%. During the commissioning phase, we successfully detected signals emitted by four well-known pulsars: PSR B0329+54, B2021+51, B0823+26, and B2020+28. We report the first discovery of an FRB by our array, designated as FRB 20220414A. We also investigate the optimal arrangement for the digitally formed beams to achieve maximum detection rate by numerical simulation.
Calculating the Excitation Temperature for H2CO Absorption Lines in Molecular Clouds
Authors: Bu Jia , Esimbek Jarken , Zhou Jianjun , Komesh Toktarkhan , Tang Xindi , Li Dalei , He Yuxin , Tursun Kadirya , Zhou Dongdong , Imanaly Ernar , Sailanbek Serikbek 
Published: June 2024

Abstract
The excitation temperature T
ex for molecular emission and absorption lines is an essential parameter for interpreting the molecular environment. This temperature can be obtained by observing multiple molecular transitions or hyperfine structures of a single transition, but it remains unknown for a single transition without hyperfine structure lines. Earlier H2CO absorption experiments for a single transition without hyperfine structures adopted a constant value of T
ex, which is not correct for molecular regions with active star formation and H ii regions. For H2CO, two equations with two unknowns may be used to determine the excitation temperature T
ex and the optical depth τ, if other parameters can be determined from measurements. Published observational data of the 4.83 GHz (λ = 6 cm) H2CO (110−111) absorption line for three star formation regions, W40, M17 and DR17, have been used to verify this method. The distributions of T
ex in these sources are in good agreement with the contours of the H110α emission of the H ii regions in M17 and DR17 and with the H2CO (110−111) absorption in W40. The distributions of T
ex in the three sources indicate that there can be significant variation in the excitation temperature across star formation and H ii regions and that the use of a fixed (low) value results in misinterpretation.
Analysis of the factors influencing the guide vane hydraulic torque of Francis turbine
Authors: Ji X Y , Xie M X , Song C K , Lai X 
Published: June 2024

Abstract
The model test is commonly used to measure the guide vane hydraulic torque. With the development of numerical simulation technology, it is possible that numerical simulation can substitute for model test to study guide vane torque. In order to study the characteristic of guide vane torque, numerical simulation of tandem cascade based on CFX software are performed for operation points under different guide vane openings. In this paper, numerical calculation of guide vane torque takes singly periodic tandem cascade with the refined mesh of the boundary layer as the research object, and hydraulic force and torque characteristic of guide vane are computed under different guide vane openings. Furthermore, the influence of stay vane profile, turbine rotational speed, guide vane periodicity and mass flow rate on guide vane torque has been researched and analysed. Considering all relative influences, the calculation results of guide vane torque with singly periodic tandem cascade were modified. The result shows the modified method is more reasonable to analyse the guide vane torque by numerical simulation.
Numerical simulation study of hydraulic performance of the ball valve implied in ultra-high head Pelton turbine
Authors: Liu J , Wang J J , Gong S , Wang Z N , Liang Q W 
Published: June 2024

Abstract
This paper is deal with the hydraulic performance of the ball valve served in ultra-high head Pelton turbine systems, the Moving Particle Simulation method is used for numerical simulation uncommonly instead of the Finite Volume method. A valve rotating range of 0 degree to 90 degree is simulated by the software Particleworks, according to the pressure change through the valve, we get the flow resistance coefficient which is consistent with those of other similar literature. The change of the internal flow distribution can be visually observed. At the small rotation degree, the flow velocity entering the ball valve is very high and the disturbance in flow field is large. With the rotation degree increases, the flow in ball valve and the outlet pipe is gradually stabilized, the pressure difference before and after the ball valve is gradually reduced. It brings reference value for the structure and size design of the ball valve in the future.
Analysis of Internal Flow and Vibration Characteristics of Tubular Turbine Considering Dynamic Change of Liquid Level in Reservoir Area
Authors: Zhao Yaping , Ren Yajing , Li Yanrong , Feng Jianjun , Luo Xingqi 
Published: June 2024

Abstract
The tubular turbine of the tidal power station is often affected by different incoming waves in the actual operation, which seriously affects the operation performance. Based on this, the real tubular turbine including upstream and downstream reservoir areas was selected as the research object, and numerical wave generation was conducted using the inlet wave generation method. The second-order Stokes wave was used to study the flow condition and vibration characteristics of the turbine in the upstream reservoir area. The results show that under the action of second-order Stokes wave, the pressure amplitude is obviously increased compared with that without liquid level fluctuation, and the flow velocity in the internal flow field is accelerated. During the wave periods, the pressure values at the runner outlet, the draft tube inlet and outlet all show periodic changes, wave energy decays and the pressure gradually decreases and weakens periodically with the shift of position. The vortex belt of draft tube has the spiral characteristics in the wave process, which will produce more axial vibration and affect the output of the unit in actual operation. These findings have theoretical significance for the actual operation, maintenance and hydraulic design of tidal tubular turbines.
Analysis of ultra-low frequency oscillation mechanism of hydraulic turbine governor under different control modes
Authors: Li G , Feng C , Zheng Y 
Published: June 2024

Abstract
As the southwest power grid with a high proportion of hydropower was transformed into UHV AC-DC network structure, some ultra-low frequency oscillations have appeared in the power grid. In this paper, according to the characteristics of the hydropower unit governor, a small disturbance model was established, and the influence of various parameters of the hydropower unit governor on the system stability in primary frequency modulation was discussed by using the eigenvalue analysis method, and the power mode and the opening mode were compared. The results showed that the parameter adjustable range of the opening mode was larger than that of the power mode. This paper lays a foundation for further research on suppression methods of ultra-low frequency oscillations.
Study on the hydraulic turbine modeling method based on IGSA-NN revision strategy
Authors: Chen Jinbao , Wang Yunhe , Hu Wenqing , Zou Yidong , Zheng Yang , Xiao Zhihuai 
Published: June 2024

Abstract
With the further increase of renewable energy such as wind power and photovoltaic in the power grid, the hydraulic turbine regulating system (HTRS) faces enormous challenges. As simulation modeling is the basis for studying the optimal control of HTRS, it is crucial to establish a high-precision model of HTRS. As the core component of the HTRS, the hydro-turbine contains extremely complex nonlinearity, which model accuracy directly affects the accuracy of the HTRS simulation platform. However, current modeling methods have certain disadvantages such as large modeling errors and making the structure of the HTRS simulation platform more complex. Therefore, this paper proposes a data modification strategy (IGSA-NN) based on the BP neural network (BPNN) and an improved gravity search algorithm (IGSA) and then achieves high-precision modeling of the hydro-turbine combining the BPNN and actual operation data. Finally, the accuracy of the hydro-turbine model is verified by the actual operation data, and the method to build the simulation platform of the HTRS which contains both real and virtual components is given. The research results have a certain guiding significance for hydro-turbine modeling.
Evaluation on structural characteristics of the spiral case influenced by external concrete
Authors: Lu Zhaohui , Luo Yutong , Guo Qiao , Zhang Shaozheng 
Published: June 2024

Abstract
As hydropower is developing vigorously, hydraulic-turbine units have to experience higher head to balance the large power production and consumption on the grid. It requests for higher level of structural strength and stability during operation. Water-filled and pressure-retaining spiral case is commonly used in the power houses of large-scale hydropower stations, which has a good joint bearing capacity of internal water pressure. In this paper, finite element models of the water-filled and pressure-retaining spiral case with and without external concrete under preloading pressure are established, which are used to simulate the structural characteristics when the water-filling process and concrete pouring process are completed. The results show that the maximum stress and deformation of the spiral case are significantly reduced by almost 50% under the support of concrete. Both of them are located at the inner edge and are about 200.80 MPa and 0.60 mm, respectively. The reason why the maximum stress and deformation positions of the spiral case changes after the external concrete being poured is the structural characteristics of concrete, which determine its stress and deformation distribution, and then affect the restraint effect of the corresponding area on the spiral case. The concrete can share parts of the preloading pressure from the spiral case that greatly improves the joint bearing capacity and stability of the overall structure. The conclusions in this paper can also be applied to evaluate the influence of external concrete on the spiral case structural characteristics for similar spiral case structure.
Research on the spiral case and external concrete structural response under limit operation state
Authors: Luo Yutong , Li Zonghua , Zhang Xiaopeng 
Published: June 2024

Abstract
As the key component of hydroelectric generating units, the spiral case is primarily responsible to make the fluid flow out in a uniform and axisymmetric way. The structural response of the spiral case and external concrete under hydraulic pressure will have an effect on the operational security and power generation efficiency of the whole unit. In this paper, a three-dimensional fluid-structure coupling model of the spiral case and concrete under limit operation state is established. Based on the computational fluid mechanics theory, the flow domain inside the spiral case is simulated to study the stress and deformation structural response of the spiral case and external concrete under the action of maximum inner hydraulic pressure. The value and position of the maximum stress and deformation are determined. The fluid-structure coupling simulation shows that severe turbulence occurs in the middle of the flow channel. The maximum equivalent stress of the spiral case is located near its tongue and there would possibly be a risk of local structural damage. The external concrete can effectively share part of the load from the spiral case, so as to keep the strength and stiffness of the overall structure being within safe levels under the limit state. The results can provide support to the structural optimization and construction of the spiral case, which is helpful for the safety and stability of station operation.
Effect of the operating head for hydraulic performance and flow of a Pelton turbine
Authors: Yanhao Li , Zishi Liu , Yexiang Xiao , Quanwei Liang , Jie Liu , Haijun Li 
Published: June 2024

Abstract
The unsteady multi-phase flow simulation in rotating buckets of a model Pelton turbine under various operating heads was performed with the SST-CC turbulence model. The hydraulic performance of the turbine and the flow pattern in the rotating bucket under different operating heads were discussed. The results showed that there was an optimal operating head for the Pelton turbine. The waste of the additional kinetic energy carried by the outflow under off-design heads accounted for the decline in the turbine efficiency. Moreover, the temporal and spatial distribution of the outflowing loss varied with operating head. In the case of high operating head, the outflowing loss last only a short period of time after the water sheet flow started to discharge, and the obvious region of loss was near the bucket root. In the case of low operating head, the outflowing loss occurred during the second half of jet-receiving for the bucket, with the position of high outflowing velocity distributed along the entire brim.
Analysis of the bucket surface cavitation characteristics of a model Pelton turbine
Authors: Jie Liu , Yexiang Xiao , Zishi Liu , Quanwei Liang , Nianhao Yang , Zongqiu Hu , Qingpin Du 
Published: June 2024

Abstract
The internal flow in the rotating bucket of high-head Pelton turbine is complex problem with features of multiphase flow and free surface. As the runner rotating, high speed water jets continuously impact the buckets, which would cause the cavitation on the bucket surface. As proved by field practice, cavitation and cavitation erosion surely exists in the Pelton turbine, which is harmful for the hydraulic performance and the unit. This paper investigated the unsteady 3D water-air-vapour multiphase cavitation flow on the bucket surface of a model Pelton turbine under a high operating head. Results showed cavitation occurred during the process of the bucket cut into the water jet on both sides of the bucket cutout edge. The cavitation on the bucket front surface last for about 20 transient steps with a maximum vapor volume fraction of about 3%, while severe cavitation occurred on the rear surface of the splitter with the duration twice of that on the front surface and a maximum vapour volume fraction of approximately 100%.
Numerical method analysis of the multi-nozzle distributor hydraulic performance for a Pelton turbine
Authors: Yilin Zhu , Jie Liu , Yexiang Xiao , Quanwei Liang , Haijun Li , Qingpin Du , Zhaoning Wang 
Published: June 2024

Abstract
The distributor hydraulic efficiency is very important for a Pelton turbine. In order to improve the turbine efficiency and the jet flow stability from the injector, it’s necessary to optimize the design of the distributor. In this paper, the flow behaviors and the hydraulic efficiency of a model Pelton turbine distributor with and without six-nozzle domain were conducted numerically. Comparison of numerical simulation results of different cases with different boundary condition settings and domain was analyzed. The predicted results show that the results of the distributor with six-nozzle domain are agree well with the measured results and the hydraulic performances is quite different from other cases.