bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reflection and transmission of ultrasonic waves in a layered structure with a functionally graded porous piezoelectric base
Authors: Vashishth Anil K , Bareja Umang , Gupta Vishakha 
Published: June 2024

Abstract
The phenomenon of reflection and transmission of waves offers valuable insights into the internal composition and structural characteristics of materials. This study investigates the reflection and transmission of waves in functionally graded porous piezoelectric materials. These materials, distinguished by their customised electromechanical attributes and gradual property variations, present a promising avenue for optimizing performance across diverse applications, including ultrasonics. The reflection and transmission of ultrasonic waves in a novel structure, consisting of a fluid half-space (FHS) positioned above n porous piezoelectric layers, situated on top of a functionally graded porous piezoelectric half-space (FGPPHS) is studied in this paper. The material properties of FGPPHS are considered to vary along the vertical direction and and resulting equations are solved analytically and numerically. The transfer matrix method is employed to analytically determine the energy ratios and amplitude ratios for reflected and transmitted waves. Numerical computations are performed to study the impacts of frequency, gradation, angle of incidence, and porosity on the energy ratios. Furthermore, the influence of stacking of the number of porous piezoelectric layers above FGPPHS, and the choice of materials (Barium Titanate (BaTiO
3), PZT − 5H, PZT − 7H) in layers and half-space, on the energy ratios are studied. The absolute value of acoustic impedance is plotted for various angles of incidence and porosities. From the graph, it is found that the acoustic impedance can be controlled by adjusting porosity in the structure. This will be helpful in minimizing the energy loss at ceramic-medium interface and improving the mismatch of acoustic impedances at the interfaces of medical ultrasonic imaging devices or underwater sonar detectors, and NDE applications. Further, because of lower acoustic impedance, lower density and stiffness of porous piezoelectric materials, the outcomes of this study will be helpful in designing SAW devices.
An efficient pressure sensor based on environmental-friendly CNTs-graphene-PDMS film
Authors: Sadiq Hammad , Hu Hui , Huang Song , Rizwan Muhammad , Muhammad Abdullah , Nawaz Muhammad Asif , Zeeshan Muhammad 
Published: June 2024

Abstract
Given the rapid advancements in artificial intelligence, there is an escalating demand for wearable sensors. An efficient graphene-based material synthesized from the mesophase pitch of waste slurry oil was integrated into a cost-effective piezoresistive pressure sensor consisting of a conductive film made of carbon nanotubes (CNTs), graphene, and Polydimethylsiloxane (PDMS). A simple fabrication approach has been suggested to infuse PDMS with CNTs-graphene, resulting in a pressure sensor exhibiting superior conductivity, enhanced sensitivity, and quick responsiveness to diverse pressure variations. Moreover, films containing varying percentages of graphene were compared. Scanning electron microscopy was utilized to examine the surface and structural characteristics of the CNTs-graphene-PDMS film, alongside studying the pressure sensor's sensing capabilities. Various applications were examined for both the individual sensor and the array of sensors. The findings demonstrate the successful detection of diverse human motions, Morse code recognition, and effective discernment of various pressures by the fabricated pressure sensor, indicating its potential for applications in smart devices, robotics, and wearable sensors.
Rumor spreading and control in both homogeneous and heterogeneous networks with guidance mechanism
Authors: Wu Yanting , Liu Shijie , Li Xiaohan , Zhao Donghua , Liu Maoxing , Sun Yongzheng 
Published: June 2024

Abstract
In this paper, we study the influence of authoritative institutions on rumor propagation and establish an IHSQR model, where Q represents the guided individuals. We consider the homogeneous and heterogeneous network models, respectively. By analyzing the conditions for the global asymptotically stable of equilibria in these models, we show their behavior under various scenarios. For the homogeneous network model, a case study of the Haze rumor is given, which verifies the effectiveness of the model. For the heterogeneous network model, we introduce optimal control to determine the minimum guidance strength and cost. The results show that the guiding role has a significant impact on rumor spread. Specifically, the stronger the guiding role, the smaller the size of rumor spreading. Therefore, to control the spread of rumors, authoritative institutions can play an important guiding role in managing and mitigating rumor propagation.
Conditions and benefits of X-point radiation for the island divertor
Authors: Feng Y. , Winters V. , Zhang D. , Geiger J. , Gao Y. , Reiter D. , Helander P. , Beidler C.D. , Endler M. , Gradic D. , Jakubowski M. , König R. , Kremeyer T. , Krychowiak M. , Naujoks D. , Otte M. , Perseo V. , Reimold F. , Schlisio G. ,   the W7-X Team
Published: June 2024

AbstractWe present a method to geometrically quantify the three magnetic island chains with the poloidal mode numbersm= 4, 5, and 6 (referred to in this paper as high-iota, standard, and low-iota islands, respectively), on which the W7-X divertor relies. The focus is on a comparative study of their detachment performance using a series of models of different physical and geometrical complexity, ranging from one- to three-dimensional (1D to 3D). In particular, it aims to identify the key physical elements behind the correlation between impurity radiation and island geometry and the associated detachment stability. Assuming intrinsic carbon as a radiator, we scan the three island chains with the EMC3-Eirene code based on otherwise identical code inputs. We find that the three islands behave differently in the radiation distribution, in the development of the radiation zones during detachment, and in the ‘radiation costs’, defined as the product of impurity and electron density near the last closed flux surface. While the radiation costs for the iota = 5/4 and 5/5 island chains linearly increase with the total radiation, the low-iota island with iota = 5/6 shows a bifurcation behavior in the sense that the radiation costs initially increase and then decrease when the total radiation exceeds a critical level. Consistent with the numerical trends, stable detachment, which is experimentally easy and robust to achieve with the standard iota = 5/5 island chain, remains an experimental challenge with the low-iota configuration. Dedicated numerical experiments show that the recycling neutrals and the ratio of parallel to perpendicular heat transport, which depends closely on the field line pitch, play a significant role in the formation and evolution of the radiation layer. A deeper understanding of the underlying physics relies on simpler models that explain why and how flux expansion can reduce the radiation costs. From these insights, we derive the conditions in which detached plasmas can benefit from the expansion of flux surfaces around the X-point. We show and explain why the current divertor design limits the actual capability of the high-iota configuration and propose solutions. The work is presented within a theoretical/numerical framework but cites relevant experimental evidence to emphasize its practical significance.
Thermal conductivity of Al/AlN interpenetrating phase composites with different preform porosity
Authors: Yan Xiao , Zhao Chunzhi , Sasaki Gen 
Published: June 2024

Abstract
In this investigation, the thermal conductive (TC) properties of the Al/AlN interpenetrating phase composites (IPCs) with varying preform porosity at different temperatures (20°C to 200°C) were studied. The TC values obtained through experimentation were compared to predictions generated by analytical models. IPCs with higher preform porosity exhibit higher TC. The TC of IPCs exhibits an inverse temperature dependence. Theoretical models accurately predict the thermal conductivity of IPCs with high preform porosity.
Experimental study on the influence of welding structure details of TC4 titanium alloy under thermo-vibration coupling environment on vibration fatigue life
Authors: Liu Jianghua , Zhao Zicheng , Wang Bin , Wang Cunxian , Lv Jinfeng , Wen Yongshuai , Zhao Nan , Li Liyuan 
Published: June 2024

Abstract
The widespread application of titanium alloy materials in aerospace structural design makes them susceptible to thermo-vibration coupling fatigue failure in harsh vibration and thermal environments. Vibration fatigue issues significantly affect the safety and operational reliability of aircraft. In order to obtain optimal design details for titanium alloy welding structures under thermo-vibration coupling conditions, experimental specimens with different structural details of TC4 titanium alloy welding structures were designed to simulate actual structural designs. The structural details included skin with U-shaped supports at different angles, skin with L-shaped supports, and skin with T-shaped supports. A thermo-vibration coupling vibration fatigue test system was established, and vibration fatigue tests were conducted at a temperature of 150°C. All structural fatigue crack failures occurred at the welds. The experimental results were statistically analysed, and using the Chauvinet criterion, abnormal data points were removed. The influence of structural details on vibration fatigue life was determined through F-tests. It was found that for the skin with a U-shaped support structure, a support angle of 90° resulted in a longer vibration fatigue life. When comparing skin with T-shaped support and skin with L-shaped support structures, the T-shaped support structure exhibited a longer vibration fatigue life. Among the three structural types, the skin with a T-shaped support structure has the longest vibration fatigue life. These experimental conclusions serve as important references for the design of thin-walled structures in aircraft structural design.
Influence and mechanism of titanium doping on the electrochromic performance of nickel oxide nanofilm
Authors: Zhang Zuosheng , Zhang Yong , Shen Die 
Published: June 2024

Abstract
This research investigates the preparation and electrochromic performance of titanium-doped nickel oxide nanofilms. Through chemical bath deposition, nickel oxide doped with various ratios of titanium (NiO) films was successfully synthesized. The study extensively analyzes the structural features and properties of these films using such characterization techniques as X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy, among others. The experimental findings highlight that moderate titanium doping (0.3%) notably enhances the porous structure and crystalline properties of NiO films, leading to improved optical modulation (88%), coloring efficiency (CE up to 42.6 cm2/C), and cycle stability (maintaining 61% optical modulation after 500 cycles). However, excessive titanium doping tends to diminish the electrochromic response time. These results underscore the significant impact of titanium doping on the electrochromic performance of NiO films, providing essential insights for their potential applications in smart windows, displays, and related fields.
Finite element simulation analysis of vibration transmission characteristics of double shell based on ANSYS
Authors: Chen Zhe , Ding Chao , Liu Zhen , Sun Shilin 
Published: June 2024

Abstract
Ship noise contains a large number of low-frequency line spectrum features. It is difficult to distinguish where they come from and even more difficult to identify the ship’s target types using the line spectrum. Therefore, research on ship targets’ vibration transmission characteristics and radiation noise is of great importance for underwater target recognition. From the perspective of underwater acoustic target recognition, this article establishes a simplified finite element model of the double shell using ANSYS, calculates the displacement response of the double shell under harmonic loads, and conducts modal analysis, harmonic response analysis, and transient dynamic analysis, which verifies the consistency of vibration between the inner shell and outer shell. Marine experimental data show that the low-frequency line spectrum of ship noise is related to the vibration frequency of ship main engines. It may be caused by diesel engine vibration transmitted through ship hull vibration and can be used as an auxiliary feature for underwater acoustic target recognition.
Internal flow field changes and cavitation characteristics research of the high-pressure axial plunger pump
Authors: Zheng Xiaofeng , Zhou Kai 
Published: June 2024

Abstract
High pressure axial piston pumps have the characteristics of high power density, small volume and high integration degree and are used in coal machinery, construction machinery and other industrial fields. However, the cavitation impact of the oil flow field inside the pump directly affects the performance and stability of the plunger pump. Once the fault occurs, it will cause the equipment to stop, threatening the life of the current personnel. Taking the axial piston pump as the research object, this paper conducts a numerical simulation analysis of part of the basin model in the piston pump, discusses the fluid characteristics and cavitation mechanism in the piston pump, and provides a theoretical reference for the design and application of high pressure pumps.
Honeycomb structure design of automotive crash box
Authors: Jia Tang , Hui Guo , Shuang Huang 
Published: June 2024

Abstract
The crash box can protect the safety of passengers when a car collides. Due to its excellent mechanical properties, honeycomb structure can be applied to automotive crash boxes. Two kinds of crash boxes made of regular hexagonal honeycomb structure and re-entrant hexagonal honeycomb are designed. The research results indicate that, compared to the crash box made of hexagonal honeycombs, the crash boxes made of re-entrant hexagonal honeycombs have superior energy absorption ability. Furthermore, the influence of different structural parameters on the energy absorption performance (EAP) of the crash box made of re-entrant hexagonal honeycombs is analyzed. It is found that the total energy absorption and peak force increase with the increase of thickness and concave angle. The research in this article provides certain reference significance for the design of honeycomb structure crash boxes.
Surface-enhanced raman scattering properties of Au@TiO2 plasma exciton array structures
Authors: Wang Xinxin , Hui Kezhen , Liu Jiaming , Huang Jinghui , Xu Jianchun , Guo Limin , Wang Xiaohui 
Published: June 2024

Abstract
Surface Enhanced Raman Scattering (SERS) is an ultrasensitive spectroscopic analysis technique widely used for molecular detection. SERS is characterized by rapid analysis, trace detection, ultra-high sensitivity, non-destructive, etc., and can analyze the concentration, composition, and structure of the detected substances. It has a significant potential for application in many fields, such as biomedicine, trace detection, food safety, and environmental protection. However, fabrication of homogeneous, stable, and ultrasensitive SERS substrates remains a challenge for the practical application of SERS technology. Precious metals and semiconductors have been proven attractive and versatile for SERS detection. In this work, three-dimensional Au@TiO2 substrates were prepared using a facile strategy, and two different types of Raman probe molecules were used to demonstrate the versatility of the design. Using 4-MBA as the probe molecule, the enhancement factor of the TiO2 substrate could reach 1.52×104, and the detection limit was as low as 10-16 M. The results indicate that the Au@TiO2 substrate is simple to prepare, inexpensive, and serves as an excellent SERS substrate structure. 4-MBA and R6G dual probe molecules demonstrate the universality of the Au@TiO2 nanocavity array structure. In the meantime, the results of the simulations match the experimental results. It also demonstrates that the three-dimensional Au@TiO2 has the potential to be an excellent SERS substrate.
Investigation of a modified IEA 15MW wind turbine including a winglet with a new mid-fidelity acoustic toolchain
Authors: Seelemeyer Philipp , Appel Christina 
Published: June 2024

Abstract
This paper presents the applicability of a new hybrid tool chain for wind turbine rotor turbulent boundary-layer trailing-edge noise (TBL-TEN) to complex rotor geometries. The research introduces a rapid, high-fidelity 2D CFD/CAA method, which enables the assessment of innovative low-noise profile designs concerning TBL-TEN, coupled with a mid-fidelity extrapolation technique for the 3D analysis, aiming to minimize computational time essential for design processes. This procedure is applied here to compare the changes in performance, load distribution and noise reduction if a winglet is added to a large-scale wind turbine, using the example of the IEA Wind TCP Task 47 15-MW-reference turbine [12]. In the first step, a 3D CFD calculation of the entire turbine is performed in order to derive the local flow parameters and thus the input variables for the 2D CAA. These results for the 2D TEN are then extrapolated for the entire turbine using the fast summation and extrapolation method TAP (Turbine acoustic prediction) [1]. As only data for the TEN is included here, only this noise source for the winglet can be analyzed. For a more complete comparison, a 3D scale-resolving simulation was set up for a static wind tunnel situation in order to be able to qualitatively classify the tip/vortex interaction noise that was not recorded by the procedure mentioned above.
Improved RANS methodology to account for flow separation on rough blades
Authors: Gutiérrez R , Aranguren P , Zamponi R 
Published: June 2024

Abstract
The RANS inaccuracy in predicting flow separation becomes relevant in thick-modern blades, especially once they get dirt or eroded. The literature has tackled the problem by modifying the coefficient a
1 in the k − ω − SST turbulence model without considering its dependency on the adverse pressure gradient condition. This study aims to assess the mentioned dependency by estimating a
1 per blade side and angle of attack. Pressure-coefficient measurements for 18 %, 25 %, and 30 % thick airfoils in clean-inflow conditions at a Reynolds number based on chord of 3 × 106 are considered in the estimation. Hence, a unique variation of a
1 is obtained per each airfoil, justifying the need to adapt a
1 locally within the OpenFOAM code. This modification considerably improves the flow separation prediction with respect to the standard a
1 value and the fb
method. As a result, the CL
error is reduced by 8 %, whereas a certain CD
error remains for all the RANS solutions. Finally, an aeroelastic model of a 4.5 MW wind turbine reveals that the non-corrected RANS solution causes an overshoot of power and loads near rated power, whereas the corrected RANS replicates the shape of the power and loads curves. Consequently, the suggested methodology can be used to search for the required a
1 relation to local flow conditions.
Improvements to the Blade Element Momentum Formulation of OpenFAST for Skewed Inflows
Authors: Branlard E. , Jonkman J. , Lee B. , Jonkman B. , Singh M. , Mayda E. , Dixon K. 
Published: June 2024

Abstract
In this work, we modify the blade element momentum algorithm of OpenFAST to improve its predictions under large skewed inflow conditions. We use the well-known Glauert’s skew correction and introduce continuous extension of the model for high-thrust conditions. We present the rationale behind Glauert’s empirical model and discuss the different conventions possible for the axial induction factor. We verify the model against the higher-fidelity lifting-line vortex method and blade-resolved computational fluid dynamics, and we observe that the new implementation enhances the accuracy and reliability of OpenFAST’s aerodynamic modeling capabilities in conditions involving large skew angles. For the parametric studies run using the different codes, we find that the power changes with the skew angle as cos1.7(θ
skew) and the thrust as cos0.65(θ
skew). An analysis of the azimuthal variation of the induced velocities in the rotor plane reveals that current redistribution models used in blade element momentum codes may need to be refined.
A directivity correction for accurate semi-empirical wind turbine noise prediction
Authors: Saldaña O , Rautmann C , Plaza A 
Published: June 2024

Abstract
Public acceptance of wind farms is a significant challenge in the development of wind energy. The acoustic impact generated by wind turbines is a common concern among local residents. The primary noise source in wind turbines is generated by aerodynamics. Atmospheric turbulence reaching the blade leading edge or turbulent boundary layer passing the trailing edge produce the main aeroacoustic sources. The noise generated by these mechanisms is commonly predicted by means of semi-empirical models, which do not demonstrate great reliability when compared to acoustic measurements. This paper presents a correction to the directivity of airfoil noise radiation, resulting in improved sound pressure levels on the ground plane surrounding a wind turbine. This improvement is achieved without requiring any additional computational effort. The sound pressure levels perceived on the ground plane are known to have asymmetrical shape. Maximum noise levels correspond to observers directly in the upwind and downwind locations, whereas the minimum levels belong to the positions close to the rotor plane. Said asymmetrical shape is not represented in the semi-empirical models. The proposed correction takes into consideration the airfoil thickness in the radiation directivity equations, resulting in the expected asymmetrical shape of noise footprints on the ground plane around a wind turbine. The correction was found to not affect the accuracy of the spectrum predicted by the semi-empirical models when compared to dedicated field measurements under the standard IEC 61400-11 procedure. When implementing the proposed correction, the virtual NREL 5 MW wind turbine’s published noise footprints, which were originally calculated using computationally expensive methods, are accurately reproduced.
Numerical investigation of effects of riblets on wind turbine performance
Authors: Tubije J M , Jin Yaqing , Leonardi Stefano 
Published: June 2024

Abstract
In this study, systematically designed wind tunnel experiments were conducted to characterize the aerodynamic performance of a DU91-W2-250 airfoil with a riblet film. To quantify the impact of the riblet film on wind turbine performance, experimental results were used as input data for numerical simulations. Large-eddy simulations were conducted for the smooth and modified airfoils under uniform and turbulent inflow conditions. For the turbulent inflow simulations, staggered cubes were introduced upstream of the wind turbine to generate velocity fluctuations in the flow. Results from the numerical simulations show that improvements in the aerodynamic performance of the airfoil with riblets enhance the aerodynamic torque that drives the wind turbine, thereby increasing the power output. The improvement in the power coefficient with the use of the riblet film is higher for turbulent incoming wind compared to uniform flow conditions.