bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrodynamic analysis of an oscillating water column array in presence of variable bathymetry
Authors: Zhao Xuanlie , Zhou Jiachun , Geng Jing
Published: September 2024

In this study, hydrodynamic analysis of an oscillating water column (OWC) array in the presence of the variable bathymetry (seafloor depth) is performed by using a semi-analytical potential-flow solver. Within the framework of linear theory, the boundary-value problem associated with wave diffraction and radiation by an OWC array with variable bathymetry is formulated and the semi-analytical hydrodynamic model is developed using the matched eigenfunction expansion method. The fluid domain above variable bathymetry is mathematically discretized into multiple subdomains using the boundary approximation method. The Haskind relation and the energy flux conservation law are used to verify the semi-analytical model. The hydrodynamic performance of the OWC array in the presence of the ripple and coral reef bathymetries are investigated in further. Pronounced oscillations are observed for the curve of reflection coefficient Cr and hydrodynamic efficiency η for cases with ripple and coral reef bathymetries. Bragg resonance is identified as the triggering of the strong oscillations in Cr and η for case of ripple bathymetry. The primary frequency of Bragg resonance and the peaked value of Cr converge as the ripple number increases (i.e., Ns > 3). Particularly, for cases with coral reef bathymetry, the wave resonance modal in open-ended basins results in a significant wave amplification at the weather side of the OWC array.
Investigation of the shock wave load characteristics in deep-water explosions based on high-order compressible multiphase fluids
Authors: Shen Chao , Yan Bo , Pei Du , Jiang Xiong-Wen , Mao Haibin , Yu Jun
Published: September 2024

We present a high-order compressible multiphase fluid solver to investigate the shock wave dynamic characteristics in deep-water explosions with energetic material detonation. The spatial terms of the system equations are discretized using fifth-order weighted essentially non-oscillatory reconstruction in characteristic space and Lax–Friedrich's splitting, while the temporal terms are discretized using a third-order total variation diminishing (TVD) Runge–Kutta scheme. The multiphase interface is captured by the level-set method combining modified ghost fluid method , and a programmed burn model is proposed to describe the phase transition from unreacted material to gaseous products and the release of detonation chemical energy. The solver is validated through comparison with other literature results and experimental results. The early shock wave characteristics of trinitrotoluene (TNT) and RS211 charges at different water depths are investigated, and numerical results indicate that the peak value of relative pressure and wave speed increase approximately linearly with increasing water depth. The near-field explosions of cylindrical TNT charges under different water depth conditions are examined using two different initiation patterns, revealing that the shape of the explosive charge significantly influences near-field underwater explosions.
Thermoelectric properties of InGaN/GaN superlattices structure with high indium composition quantum dots
Authors: Kang Junjie , Ma Qun , Li Yang , Fu Song , Yi Xiaoyan , Wang Junxi , Li Jinmin , Liang Meng , Wang Lai , Liu Zhiqiang
Published: September 2024

High indium composition InGaN is a promising material for thermoelectric harvesting application, which can work at high temperature and extreme environments. Due to the strong composition segregation, high indium composition InGaN material usually forms localized quantum dots, which advantageously enhances the thermoelectric (TE) properties. In this research, the two-dimensional InGaN/GaN superlattices (SLs) structured TE material with high In composition of 35% quantum dots is first grown and characterized. Using open-circuit voltage measurement, the Seebeck coefficient (S) exhibits a high value of −571 μV/K. Analysis indicates this relatively high S value is related to the increased density of electron states near the Fermi level induced by the reduced dimensionality, resulting in a power factor of 11.83 × 10−4W/m·K2. The dense boundary between InGaN quantum dots also increases the interface phonon scattering, thereby suppressing the heat transportation and leading to a low thermal conductivity (k) value of 19.9 W/m·K. As a result, a TE figure of merit (ZT) value of 0.025 is demonstrated in the sample. This work first clarifies the impact of embedded quantum dots in InGaN/GaN SLs structure on TE properties. It is very conductive for the design and fabrication of low-dimensional GaN based TE device.
Numerical investigation of the multiphase flow and loading state of underwater semiclosed initial interrupted bubbles
Authors: Liu Haotian , Li Shangming , Fu Debin
Published: September 2024

The pulsation of bubbles and the impact load from reverse flow, generated by the evolution of semiclosed initial intermittent bubble multiphase flow during underwater launches, are crucial factors affecting launch safety. This paper employs the mixture multiphase flow model and the interphase heat and mass transfer model to simulate the interaction between the gas inside a partially enclosed cylinder and the water medium outside the cylinder, combined with simulation and piggybacking experiments, to analyze the flow process and load state. The numerical model is further utilized to study the evolution of the multiphase flow field of the semienclosed initial intermittent bubble, the pulsating load of the bubble, the impact load of the inverted water flow, and the influence of structural dimensions on the load. The results show that the initial intermittent bubble in the mouth of the cylinder experiences an expansion–contraction–expansion pulsation process, and as the migration of the interface between the phases results in significant pressure pulsation, the peak pulsation can exceed twice the pressure difference between the initial gas pressure inside the cylinder and the hydrostatic pressure at the mouth of the cylinder. At the late stage of bubble pulsation, a large amount of water with pulsating bubbles flows into the semiclosed cylinder, and the pulsation-induced velocity and gravity are used to form a high-speed inverted water flow. The interaction between the inverted water and the gas inside the cylinder generates an oscillating shock load where the maximum shock load is significantly greater than the ambient pressure load. Additionally, the effect of structural dimensions on the load state under the same intermittent conditions is examined.
Influence of rotating wheels on Reynolds number sensitivity of passenger vehicle drag
Authors: Josefsson Erik , Urquhart Magnus , Sebben Simone
Published: September 2024

Rotating wheels are essential to replicate realistic forces and flow fields during aerodynamic testing of passenger vehicles. Previous studies have found that the drag coefficient typically reduces with increased speed under rotating wheel conditions but is stable with stationary wheels. This paper investigates this velocity sensitivity for two vehicles, the aerodynamic research vehicle DrivAer and a production vehicle. Experiments with the DrivAer indicate that the drag reduction with increased speed cannot be explained by pressure changes on the vehicle body; instead, the effect is attributed to local flow changes around the wheels. Using numerical simulations, it is found that the separation at the front wheels' outer tire shoulder increases for lower velocities, thus resulting in higher drag coefficient and causing Reynolds number sensitivity. The degree of drag reduction is less for the DrivAer squareback than for the notchback due to the separation over the notchback's rear window. No direct difference is measured between various tires and rims. To assess the generality of the findings with the DrivAer, the results are compared to experiments with a production vehicle. It is observed that the drag sensitivity is less and only occurs if the rear wheels are rotating. Pressure measurements in the wheelhouses and around the wheel drive units confirm the front wheel separation's dependence on velocity and highlight the complex interaction between the front wheel wakes and rear wheel rotational state.
Low-voltage operatable top-gated organic transistors based on the solution-processed binary polymers dielectric for simplifying the manufacturing flow of arrayed AMOLED
Authors: Su Jing , Lin Yijie , Wei Haitian , Yan Zhenxiang , Wang Wei , Xie Wenfa
Published: September 2024

The complex process flow is an important factor that hinders the development of active-matrix organic light-emitting diode (AMOLED) displays. Organic thin-film transistors (OTFTs) are one of the promising candidates as the pixel circuits for AMOLEDs. Both the architecture and the fabrication of OTFTs are crucial elements to determine the process flow and cost of the AMOLEDs. In this Letter, we develop a strategy to significantly simplify the process flow and reduce the cost of AMOLEDs by constructing top-gated OTFTs with a solution-processed vertically phase separated binary polymer dielectric as the pixel circuits. The design on the OTFTs considers both the process flow and the device performance in terms of mobility and operating voltages. The mechanism to improve device performances is discussed. Finally, a 3 × 4 arrayed AMOLED is demonstrated, in which a high mobility over 0.3 cm2/Vs is obtained on the switching and driving OTFTs, and luminance over 300 cd/m2 is achieved on the OLEDs at the supplied low operating voltages of 10 V. This strategy provides a competitive technological route for the manufacturing of AMOLEDs.
Transient shear banding during startup flow: Insights from nonlinear simulations
Authors: Sharma Shweta , Joshi Yogesh M. , Shankar V.
Published: September 2024

We study the dynamics of shear startup of Johnson–Segalman and non-stretching Rolie-Poly models using nonlinear simulations. We consider startup to shear rates in both monotonic and nonmonotonic regions of the constitutive curve. For the Johnson–Segalman model, which exhibits a shear stress overshoot during startup, our nonlinear simulations show that transient shear banding is absent regardless of whether the startup shear rate is in the monotonic or nonmonotonic regions of the constitutive curve. In the latter case, while there is clearly an inhomogeneity en route to the banded state, the magnitude of the extent of banding is not substantially large compared to that of the eventual banded state. Marked inhomogeneity in the velocity profile is predicted for the nonstretching Rolie-Poly model only if the solvent to solution viscosity ratio is smaller than O(10−3), but its occurrence does not appear to have any correlation with the stress overshoot during startup. The comparison of the present nonlinear results with the results obtained within the framework of linearized dynamics show that nonlinearities have a stabilizing effect and mitigate the divergence of perturbations (as predicted within the linearized dynamics) during shear startup. We argue that the neglect of inertia in the nonlinear simulations is not self-consistent if the solvent to solution viscosity ratio is very small, and that inertial effects need to be included in order to obtain physically realistic results. Furthermore, our study demonstrates a pronounced sensitivity of shear startup in the nonstretching Rolie-Poly model when a random white noise with zero mean is used as the initial perturbation. Finally, this study clearly emphasizes that stress overshoot during shear startup does not always result in transient shear banding, notwithstanding whether the shear rates is in the monotonic or nonmonotonic part of the constitutive curve.
Flow past a rotating porous sphere in the existence of a toroidal magnetic field
Authors: Sharma Bharti , Srivastava Neetu
Published: September 2024

This model consists of a porous spherical body rotating in an incompressible conducting fluid in the existence of a toroidal magnetic field. The toroidal field is generated by an electric dipole along the axis of symmetry. The model is split into two parts—the clear fluid region and the porous sphere. The clear fluid area is driven by the momentum equation and the permeable sphere region is driven by the Brinkman equation. The study is being done for the scenario where the impact of viscous force is much more than inertia force. The expression is found for fluid velocity and stream function by the superposition method. The results depict the impact of rotational parameters and the Darcy number on separation parameter. It is shown that the separation is low for the highly permeable sphere.
Performance improvement of multi-blade centrifugal fan based on impeller outlet flow control
Authors: Lei Jian , Cui Qin , Qin Guoliang
Published: September 2024

The impeller of the multi-blade centrifugal fan significantly impacts the fan's internal flow field and aerodynamic performance. To improve the axial flow distribution along the impeller and suppress the blade passage backflow at the impeller outlet of multi-blade centrifugal fans, a method of variable chord length blade design is proposed. Simultaneously, optimization models are established with static pressure and efficiency as objectives. By altering the control points of the Bezier curve, the leading-edge profile of the impeller is optimized. The results indicate that using variable chord length blades can expand the operating range of the multi-blade centrifugal fan. The maximum flow rate improvement reaches 10.6%. Significant enhancements in the aerodynamic efficiency of the multi-blade centrifugal fan are observed at low flow rates, with a maximum improvement of 4.9%. The variable chord length blade design method enables adjustment of the axial flow distribution at the impeller outlet to better match the impeller's flow requirements. This leads to increased outlet flow on both the shroud and hub sides of the impeller, consequently reducing the backflow area on both sides and improving the blade passage backflow phenomenon. Moreover, variable chord length blades facilitate a more uniform circumferential flow distribution at the impeller outlet, reducing the diversion pressure of the volute tongue, mitigating flow separation within the blade passage, weakening the interaction between the impeller and the volute tongue, and lowering energy losses in the impeller–volute tongue regions. Consequently, this enhances the aerodynamic performance of multi-blade centrifugal fans.
The origin of ferroelectricity in HfO2 from orbital hybridization and covalency
Authors: Yang Jiangheng , Liao Jiajia , Huang Jin , Peng Ren-Ci , Yang Qiong , Liao Min , Zhou Yichun
Published: September 2024

Fluorite-structured HfO2 ferroelectrics exhibit remarkable ferroelectricity owing to the robust thickness scalability, rendering them promising for next-generation ferroelectric memories. Unlike the well-understood perovskite structured ferroelectrics, such as Pb(Zr,Ti)O3, the origin of ferroelectricity in HfO2 remains elusive, which impedes the experimental fabrication of pure and stable ferroelectric orthorhombic phase in films. This study seeks to elucidate its origin by analyzing the covalent nature of local chemical bonding and changes in orbital hybridization and by catching the typical feather of the half-unit-cell spacer/polar layer in the orthorhombic phase. Notably, we find that the differences in the hybridization intensity of the 2s orbitals of two types of O atoms (OI and OII) and 5d orbitals of Hf atoms play a crucial role in inducing ferroelectric distortion. Furthermore, we demonstrate that the intrinsic mechanisms of stress in enhancing the ferroelectricity of HfO2 originate from the modulation of orbital hybridization intensity of the Hf–O bonds. These insights provide a vital theoretical foundation for further exploration of ferroelectric phase transitions and property modulation in HfO2 and similar fluorite-structured ferroelectrics.
Frictional pressure drop of the vertically upward gas–liquid two-phase flow in an airlift pump system
Authors: Zhu Jingyu , Du Yanlian , Fu Mengdi , Han Xuanhe , Li Meng , Ruan Rongqian , Shen Yijun
Published: September 2024

Airlift pumps (ALPs) are promising in the oil and chemical industry, owing to their advantages such as a simple structure, convenient operation, wide applicability, high cost-effectiveness, environmental friendliness, safety, and reliability. However, there are few studies on the frictional pressure drop of vertically upward gas–liquid two-phase flow in ALPs. Therefore, this study presents an experimental investigation of the frictional pressure drop in the vertically upward gas–liquid two-phase flow in ALPs. Experiments were conducted in a vertical pipe with a total length of 3.245 m and a two-phase section of 2.8 m; the working pressure of the air compressor was 0.4 MPa, pipe diameter was 0.05 m, submergence ratio ranged from 0.6 to 0.85, and gas superficial velocity ranged from 0 to 4 m/s. A total of 74 sets of experimental data were obtained, and the frictional pressure drop models of 36 classical gas–liquid two-phase flows were evaluated. The results indicated that classical gas–liquid two-phase flow models significantly underestimated the experimental results. By analyzing the experimental data, visualizing the internal flow field, and performing theoretical derivations, a new frictional pressure drop correlation was established for the vertically upward gas–liquid two-phase flow in ALPs. The results demonstrated that the new model could accurately predict the frictional pressure drop of ALPs with mean percentage error, mean absolute percentage error, and root mean square percentage error values of 7.8%, 12.18%, and 25.86%, respectively.
Accurate deep learning-based filtering for chaotic dynamics by identifying instabilities without an ensemble
Authors: Bocquet Marc , Farchi Alban , Finn Tobias S. , Durand Charlotte , Cheng Sibo , Chen Yumeng , Pasmans Ivo , Carrassi Alberto
Published: September 2024

We investigate the ability to discover data assimilation (DA) schemes meant for chaotic dynamics with deep learning. The focus is on learning the analysis step of sequential DA, from state trajectories and their observations, using a simple residual convolutional neural network, while assuming the dynamics to be known. Experiments are performed with the Lorenz 96 dynamics, which display spatiotemporal chaos and for which solid benchmarks for DA performance exist. The accuracy of the states obtained from the learned analysis approaches that of the best possibly tuned ensemble Kalman filter and is far better than that of variational DA alternatives. Critically, this can be achieved while propagating even just a single state in the forecast step. We investigate the reason for achieving ensemble filtering accuracy without an ensemble. We diagnose that the analysis scheme actually identifies key dynamical perturbations, mildly aligned with the unstable subspace, from the forecast state alone, without any ensemble-based covariances representation. This reveals that the analysis scheme has learned some multiplicative ergodic theorem associated to the DA process seen as a non-autonomous random dynamical system.
Comparative study of the sealing mechanism and performance between magnetic fluid and magnetorheological fluid seals
Authors: Dou Xuankai , Yang Xiaolong , Sun Chao , Gao Shanghan , Xuan Haofeng
Published: September 2024

Magnetic fluid and magnetorheological fluid are two of the most effective magnetic media seals, yet the sealing effectiveness of both has not been compared systematically. To investigate the differences between magnetic fluid and magnetorheological fluid seals, a comparative experimental device is proposed to study the sealing mechanism and performance of the two sealing media at different temperatures. Numerical simulation is used to study the magnetic field distribution of the comparative experimental device and calculate the theoretical pressure resistance (PR) of the two sealing media, respectively. The correctness of the theoretical PR formula of the magnetic media seals with additional temperature coefficient is verified by the comparative experimental results. The results show that the number of resumptions of the magnetorheological fluid film decreases with increasing temperature, while the magnetic fluid film consistently undergoes only one recovery. In addition, the self-healing capability and PR of magnetorheological fluid seals are better than that of magnetic fluid seals, and it is less affected by temperature and has stronger temperature adaptability.
A perspective on mechanoluminescence and multipiezo in ferroelectric materials
Authors: Uchiyama Tomoki , Zheng Xu-Guang , Xu Chao-Nan
Published: September 2024

The discovery of innovative mechanoluminescence materials of SrAl2O4 and ZnS, which emit repeatable light [repeatable mechanoluminescence (ML), hereafter simply ML] even by soft touch, has trigged intense research interest in material/device/system development for applications across various fields. This perspective presents an overview of the crystal structures, mechanisms, and ML behaviors of most promising systems, namely, SrAl2O4-, ZnS-, LiNbO3-, and Sr3Sn2O7-based ferroelectric materials. These multipiezo materials, which simultaneously exhibit intrinsic piezoluminescence (true elastic deformation induced ML and no friction effect) and piezoelectricity, show distinct and valuable characteristics by integrating mechanical force, electric field, and light for stress sensing and other applications. Recent studies indicated the critical role of crystal structure, doping, and piezoelectric properties in achieving robust and reliable ML performance. These findings suggest that ML materials hold substantial promise for applications in stress/force sensing, structural health monitoring, mechanically activated lighting, and advanced imaging techniques. Further investigation and advancement of multipiezo materials could yield breakthroughs, further augmenting their usefulness across various industries and scientific domains. Exploring ferroelectric ML materials offer new prospects for developing advanced materials with unique electro-mechano-optical properties.
Group hydrodynamic analysis of two manta rays under spacing and phase-difference coupling
Authors: Gao Pengcheng , Tian Xushun , Huang Qiaogao , Pan Guang , Chu Yong , Bai Jingyi
Published: September 2024

Highly biosimilar manta ray morphological and kinematic models are first established, followed by a numerical study of the hydrodynamic characteristics of two manta rays swimming in tandem under the same/reverse phase-difference conditions based on the immersed boundary method. The results show that, compared to single swimming, under the same/reverse phase-difference conditions, the propulsive performance of leader manta rays are all significantly improved only when the tandem spacing is small (thrust increase up to 4.27%, efficiency increase up to 4.76%), while the propulsive performance curves of follower show fluctuating variation with the change of the spacing. It is especially worth noting that when the tandem spacing is not conducive to improving the propulsive performance, it can be improved by adjusting the motion phase difference, to realize that the wake between the individuals can be converted from collision interference to absorption and fusion, and to realize that the propulsive performance can be changed from inferior to superior. The findings of this paper provide a new idea for improving the underwater vehicle group propulsion performance based on coupled regulation of formation and motion parameters.
Postnominal flagging and OV in Sinitic
Authors: Hölzl Andreas
Published: September 2024

Sinitic languages are known for their SVO order and mostly isolating morphology. This study addresses eleven
languages of four different areas in Hunan, Yunnan, Sichuan, and Qinghai/Gansu provinces in China that possess SOV order and
developed a postnominal flagging system. This study presents a synchronic description as well as a diachronic analysis of the
flagging systems in these languages, focusing on typological properties (ergative or secundative alignment) and the role of
language contact. The existence of four separate areas with limited mutual contact allows a contrastive approach and inferences on
the role of different contact languages (Tibetic, Mongolic, Tujia) or different types of language contact (borrowing of flags,
shared grammaticalization). The study argues against OV order and postnominal flagging as defining features of the “Amdo
Sprachbund”, showing that these are universally present in all four areas and are better understood as the result of contact
between two Eurasian macro areas.
An insight on the last two decades of global research on animal tuberculosis: Bibliometric analysis
Authors: Abdullah Alhusayni Latifah , Marzok Mohamed , Hegazy Yamen , El-Gohary Fatma A. , El-Khodery Sabry
Published: September 2024

Animal tuberculosis is of global concern because of its economic and zoonotic importance. Bibliometric analysis is an important methodology used to analyze articles and other publications in literature. In this study, we performed quantitative studies on animal tuberculosis for the last two decades by March 2024. The data were retrieved from the Web of Science (WOS) database. Statistical data were set for each studied item using the VOSviewer software, with a focus on the top ten results for each item. A total of 11,155 documents were finally included in the evaluation. Results revealed that author Vordermeier H.M. had the highest number of published papers (151, 1.35%), and the publications in 2021 (693, 6.21%) were at the forefront. The United States Department of Health and Human Services was the top funding agency (1093, 9.79%), and the USA was the top nation in publications (3137, 28.12%). The most publications were in English (10898, 97.69%) and the highest publications in WOS categories were collected from Veterinary Sciences (2588, 23.2%). Research articles were the most abundant form (9271, 83.11%). Citation meso indicated that tuberculosis and leprosy (6628, 59.4%) were the top and Elsevier was the main publisher (2577, 23.1%). The results of this bibliometric analysis indicate a growing number of studies on tuberculosis in animals, which reflects the re-emergence of the disease to an alarming degree. The results can help to establish the possible forthcoming plans for its prevention and control.
Non-linear AC dielectric properties of epoxy composites filled with core–shell SiC particles
Authors: Yu Chenfeng , Han Yongsen , He Jiawang , Wang Xinyu , Zheng Huan , Sun Yunlong , Li Zhonghua
Published: September 2024

Core–shell structured silicon carbide (SiC)/epoxy (EP) composites exhibit superior non–linear DC conductivity. However, the high voltage alternative current dielectric properties of the composites are rarely reported. In this paper, the time–domain measurement was employed to obtain the basic dielectric characteristics, AC conductivity, and relative permittivity of the SiC/EP and SiC@Al2O3/EP composites under less than the breakdown strength of the SiC/EP (i.e. the amplitude of 1–5 kV mm−1). In addition, in the high AC electric field (i.e. the amplitude of 6–20 kV mm−1), the non–linear AC dielectric properties of the SiC@Al2O3/EP composite are also investigated. The experimental results suggest that the SiC@Al2O3/EP composite shows more obvious non–linear AC dielectric properties than the SiC/EP composite. In the high AC electric field, the AC conductivity of the SiC@Al2O3/EP composite presents the relaxation phenomenon, which is attributed to the excitation field and its derivative. This work lays a foundation for further research on the AC steady–state and transient dielectric properties of the field grading materials, which are widely used to homogenize the nonuniform electric field distribution in many electrical and electronic equipment.
Thermal transport in C6N7 monolayer: a machine learning based molecular dynamics study
Authors: Wan Jing , Li Guanting , Guo Zeyu , Qin Huasong
Published: September 2024

The successful synthesis of a novel C6N7 carbon nitride monolayer offers expansive prospects for applications in the fields of semiconductors, sensors, and gas separation technologies, in which the thermal transport properties of C6N7 are crucial for optimizing the functionality and reliability of these applications. In this work, based on our developed machine learning potential (MLP), molecular dynamics (MD) simulations including homogeneous non–equilibrium, non–equilibrium, and their respective spectral decomposition methods are performed to investigate the effects of phonon transport, temperature, and length on the thermal conductivity of C6N7 monolayer. Our results reveal that low–frequency and in–plane phonon modes dominate the thermal conductivity. Notably, thermal conductivity decreases with an increase in temperature due to temperature–induced increase in phonon–phonon scattering of in–plane phonon modes, while it increases with an extension in sample length. Our findings based on MD simulations with MLP contribute new insights into the lattice thermal conductivity of holey carbon nitride compounds, which is helpful for the development of next–generation electronic and photonic devices.
What can we learn from the experiment of electrostatic conveyor belt for excitons?
Authors: Zhao T T , Li Rui , Liu C S
Published: September 2024

Motivated by the experiment of electrostatic conveyor belt for indirect excitons (Winbow et al 2011 Phys. Rev. Lett.
106 196806), we studied the exciton patterns for understanding the exciton dynamics. By analyzing the exciton diffusion, we found that the patterns mainly came from the photoluminescence of two kinds of excitons. The patterns near the laser spot came from the hot excitons which can be regarded as the classical particles. However, the patterns far from the laser spot come from the cooled or coherent excitons. Considering the finite lifetime of Bosonic excitons and of the interactions between them, we built a time-dependent nonlinear Schrödinger equation including the non-Hermitian dissipation to describe the coherent exciton dynamics. The real-time and imaginary-time evolutions were used alternately to solve the Schrödinger equation to simulate the exciton diffusion accompanied by the exciton cooling in the moving lattices. By calculating the escape probability, we obtained the transport distances of the coherent excitons in the conveyor, consistent with the experimental data. The cooling speed of excitons was found to be important in coherent exciton transport. Moreover, the plateau in the average transport distance cannot be explained by the dynamical localization-delocalization transition induced by the disorders.
The Fusiongram: a periodic weak fault feature extraction strategy and its application in bearing fault diagnosis
Authors: Xue Zhengkun , Zhang Wanyang , Xue Linlin , Shi Jinchuan , Shan Xiaoming , Luo Huageng
Published: September 2024

The weak periodic transient impact responses caused by localized defects in rolling bearings are often obscured by complex interferences, such as white noise, random transient impact responses, and periodic responses from system operations. Meanwhile, the fault feature information contributing to damage detection may be distributed across different frequency bands in the vibration signal. Therefore, under the influence of complex interference, it is a challenging problem to accurately select frequency bands containing rich fault feature information and utilize the useful information from multiple frequency bands to serve fault diagnosis. To overcome this problem, this research introduces a novel signal processing strategy, termed as Fusiongram, for extracting weak periodic fault features amidst the influence of complex interferences. Firstly, the method of complementary hierarchical decomposition is proposed, in which the signal is decomposed into multiple components with overlapping frequency contents. Then, an index with interference resistance is constructed to select the components carrying rich damage feature information. Finally, the adaptive threshold denoising and multicomponent normalized averaging techniques are employed to fuse the information from the squared envelope spectra (SES) of the selected components, thus obtaining the reconstructed SES for fault diagnosis. The Fusiongram is able to achieve the goal of weak fault feature extraction from signals with complex interference. The analysis results of numerical simulation and experimental testing verify the effectiveness and advantages of the proposed strategy.
Fault diagnosis of the harmonic reducer based on dual-path convolutional network with multi-channel hybrid attention mechanism
Authors: Li Kai , Yang Ronggang , Wei Tianci , Yang Yiwen , Xiang Jiawei
Published: September 2024

Harmonic reducers are prone to wear and other failures due to continuous deformation of the flexure wheel during operation. To evaluate the sorts of faults in harmonic reducers under various operating situations, a fault diagnosis method (MADCNN-BiGRU) based on dual-path convolution neural network (DCNN) with multi-channel hybrid attention mechanism (MCHAM) and bidirectional gated recurrent unit (BiGRU) was proposed. Firstly, a novel MCHAM focuses on the critical information part of the vibration signal and can effectively suppress the noise and redundant information. Secondly, a new soft threshold function is constructed to regulate the attention weights dynamically. Thirdly, BiGRU obtains feature information for different time series locations to identify the faults correctly. Fourthly, a harmonic reducer test rig is established to collect vibration signals of harmonic reducers with different faults under various operating situations. The comparative experimental results demonstrate that MADCNN-BiGRU has excellent capacity for robustness and generalization, and can effectively diagnose under various operating situations.
Long-time prediction of multi-indicator water quality based on the improved WaveNet under time series decomposition and phase space reconstruction
Authors: Chen Ying , Wu Zhen , Shen Zhen , Zhang Hongbo , Yuan Junjun , Cai Mingfa
Published: September 2024

Long–time prediction of water quality indicator such as chlorophyll–a (Chl–a) is crucial for water process engineering and environmental management. In order to capture the characteristics of long–time series and reduce the limitations of traditional long–time prediction strategies, this paper proposes a novel hybrid model by combining data decomposition, phase space reconstruction, feature fusion and improved WaveNet. Firstly, the original data is decomposed into several subsequences through time series decomposition. Then, the subsequences with chaotic characteristics are integrated with multiple features for phase space reconstruction. Next, the decomposed and reconstructed subsequences are fed back into the improved WaveNet model separately. Finally, the prediction results are obtained by summing the predicted values of the subsequences. In this paper, the reliability of the method is assessed using the dissolved oxygen, water temperature, pH and Chl–a data of a monitoring station in the Beihai coastal sea area, ablation experiments are conducted to demonstrate the effectiveness of each module in the proposed model, and comparisons with multiple benchmark and hybrid models show that the proposed model exhibits better performance in long–time prediction of coastal water quality in the next fourteen days.
Three-dimensional visualization of large-area, nanoscale topography measurements
Authors: Natinsky Eva , Connolly Liam G , Cullinan Michael
Published: September 2024

High-resolution metrology is a critical area of development for nanoscale manufacturing, especially as it affects production throughput and fabrication quality. Atomic force microscopy (AFM) is one of the most popular tools for nanometrology, and high-resolution AFM often requires a significant time commitment and produces datasets of several million points. It is therefore critical for the development of data processing techniques to keep pace with the requirements of analyzing this type of data, and for these techniques to be portable as miniaturization in AFM is becoming more common. This work presents a data fitting algorithm designed for reducing the parameters of large-area data sets which utilizes well-established spline fitting techniques. In this paper we show that basis-spline fitting can be used to accurately represent large AFM data sets, including data sets with noisy data and sharp features, while achieving at least 90% parameter reduction in all test cases.
Plasma edge and scrape-off layer turbulence in gyrokinetic simulations of negative triangularity plasmas
Authors: Bernard T N , Halpern F D , Francisquez M , Hammett G W , Marinoni A
Published: September 2024

Gyrokinetic simulations in the long-wavelength or drift-kinetic limit are carried out of DIII-D inner-wall-limited (IWL) plasmas to investigate the effect of triangularity on edge and scrape-off layer (SOL) turbulence. The effect of neutral interactions and triangularity on plasma blobs is explored due to the impact blobs can have in setting the SOL width or introducing impurities through interactions with plasma-facing components. Seeded blob simulations with neutrals in shaped SOL scenarios demonstrate that increasing elongation, triangularity, or Shafranov shift decreases radial blob velocities, but neutral interactions have a minor effect. Fully turbulent simulations of DIII-D IWL plasmas include both open- and closed-field-line regions. The negative triangularity (NT) simulation has lower average core Te
, lower normalized Te
fluctuations, and lower fluxes, but a greater number of coherent structures (blobs) identified with increased size and velocity, on average. Density and electron temperature profiles are within a factor of 2 of experimental values. The increased trapped electron particle fraction in NT simulations is consistent with previous studies.
Voltametric detection of methylene blue dye in water at green and chemically synthesized Ag/MWCNT modified electrode
Authors: Mokole Seleke J , Fayemi Omolola E
Published: September 2024

A well-known textile dye, methylene blue (MB) was electrochemically detected by using glassy carbon electrode (GCE), modified with green and chemically synthesized silver nanoparticles (AgNPs) decorating the surface of functionalized multiwalled carbon nanotubes (fMWCNT). The green and chemical methods were used to synthesize AgNPs, which decorated MWCNT forming MWCNT/Agchm and MWCNT/Aggrn nanocomposite. Comprehensive characterization of the nanomaterials was carried out using energy-dispersive x-ray spectroscopy (EDX) detector-equipped scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy (UV), and x-ray diffraction (XRD). Using XRD, particle sizes were found to be 26.81, 10.05, 5.36, 19.26, and 17.48 nm for Agchm, Aggrn, MWCNT, Agchm/MWCNT, and Aggrn/MWCNT, respectively. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV) were employed for the investigation of the electrochemical properties and behaviour of MWCNT, Agchm, Aggrn, Agchm/MWCNT, and Aggrn/MWCNT electrodes, and higher electron transport capabilities and improved electrochemical activity towards MB on Agchm/MWCNT electrode were demonstrated by the results. Electroanalysis of methylene blue at the modified electrodes with square wave technique SWV was successful. At Agchm/MWCNT modified electrode, a low limit of detection (LOD) of 4.684 and limit of quantification (LOQ) of 14.194 pM, for MB, while at Aggrn/MWCNT modified electrode , an LOD and LOQ of 2.935 and 8.895 pM, were recorded respectively. In real sample analysis, the recovery percentage for Agchm/MWCNT ranged from 90 to 98% (n =3), and Aggrn/MWCNT showed a recovery percentage ranging from 97 to 103% (n = 3). Both electrodes’ remarkable recovery rate attest to their dependability and sensitivity in MB detection.
Plasma P-tau217 Demonstrates Excellent Diagnostic and Prognostic Performance as a Blood-Based Biomarker for Alzheimer Disease in Older Adults
Authors: Dyer Adam , Dolphin Helena , Morrison Laura , O'Connor Antoinette , Sedgwick Gavin , Young Conor , Killeen Emily , Gallagher Conal , McFeely Aoife , Connolly Eimear , Davey Naomi , Doyle Paddy , Claffey Paul , Lyons Shane , Gaffney Christine , Ennis Ruth , McHale Cathy , Joseph Jasmine , Knight Graham , Kelly Emmet , O'Farrelly Cliona , Fallon Aoife , O'Dowd Sean , Lawlor Brian , Bourke Nollaig , Kennelly Sean
Published: September 2024

Background

There has been unprecedented progress in the development of blood-based biomarkers (BBMs such as p-tau217 to detect Alzheimer Disease (AD) pathology – characterised by the accumulation of Amyloid-Beta (Aβ) and hyper-phosphorylated tau (T). However, BBM performance in “real-world” memory clinic contexts remains unclear.

Methods

Using high-sensitivity immunoassays, plasma p-tau217 was assessed in 554 participants. Two cohorts were studied: (i) a memory clinic validation cohort of 108 older adults (69 ± 6.5 years; 54.6% female) with early cognitive symptoms and paired plasma/cerebrospinal fluid (CSF) at time of diagnostic Lumbar Puncture (LP) and (ii) a broader replication cohort of 446 individuals ranging from cognitively-unimpaired middle-aged adults to older adults with established AD with 18-month follow-up. Plasma P-tau217 performance was examined against clinically established CSF Aβ+/T+ cut-offs using Area-Under the Curve (AUC) analysis. Plasma cut-offs were optimised vs CSF based on maximal Youden index.

Results

In the memory clinic cohort, plasma p-tau217 exhibited excellent performance for the detection of Aβ pathology (AUC: 0.91, 0.86-0.97). Plasma p-tau217 was nearly 4-fold higher in Aβ+ (13.89; 7.36-19.0pg/mL) vs Aβ- (3.72; 2.80-4.09pg/mL, U = 230, p<0.001) participants. Plasma p-tau217 was superior in the identification of Aβ vs T pathology (p<0.05, DeLong Test) and outperformed p-tau181 and other BBMs(all p<0.05, DeLong Test). In the replication cohort, plasma p-tau217 maintained >90% accuracy for clinical AD and was significantly associated with clinically meaningful cognitive decline over 18 months (Odds Ratio 1.40; 1.06-1.85, p=0.02). In the initial memory clinic cohort, application of plasma p-tau217 as a diagnostic test would have reduced the need for LPs by over half (56.5%).

Conclusion

Plasma p-217 demonstrates excellent diagnostic and prognostic performance in older adults with AD, representing an amyloid-responsive measure which also predicts meaningful cognitive decline in established AD. Incorporation of plasma p-tau217 in memory clinic settings may substantially reduce the need for over half of diagnostic LPs.
Irish Hip Fracture Database Frailty Index Predicts Delirium Incidence and Length of Stay in Older Adults Admitted with Hip Fractures
Authors: Bradley Eoin , Fitzpatrick Donal , Lannon Rosaleen , McCarroll Kevin , Romero-Ortuno Roman
Published: September 2024

Background

The Irish Hip Fracture Database (IHFD) Frailty Index was developed with the National Office for Clinical Audit has been shown to predict adverse outcomes in older adults with fractures in retrospective review of national data. Here we examined the tool prospectively in clinical practice and its ability to predict delirium and length of stay.

Methods

We prospectively collected data on all hip fracture patients admitted to an acute orthopaedic floor from October 2022 to May 2024. Patients aged < 60 years or those with atypical femoral or peri-prosthetic fractures were excluded. The 21-item frailty index was applied to all eligible patients. Delirium diagnosis was based on a composite of clinical diagnosis and a 4AT score ≥ 4. Regression analysis was used to examine the relationship between delirium and length of stay with Frailty Index, age and sex.

Results

A total of 260 patients were included in the study, of whom 72% were female. The mean age was 80 ± 10 years, and 7.7% were nursing home residents. Additionally, 24.2% of patients were discharged directly home, while 40.3% were discharged to rehabilitation. Delirium developed in 24.6% of patients, and 24.9% of patients had a LOS exceeding 30 days. Higher frailty index scores were significantly associated with both LOS (p = 0.001) and delirium (p = 0.013) in both unadjusted and adjusted analyses. There was no significant association between age or sex and LOS or delirium in adjusted analysis.

Conclusion

The IHFD Frailty Index facilitates a pro-active risk stratification that is based on comorbidities and functional status. IHFD Frailty index independently predicted delirium and length of stay while age did not. Further studies integrating this tool into everyday practice in the care of older patients with hip fractures is warranted.
Elevated Bone Turnover Markers After One Infusion Of Zoledronic Acid Post Denosumab Cessation
Authors: Jamil Intan Juliana , Fitzpatrick Donal , Bradley Eoin , Sherry Sophie , O'Carroll Claire , Carraher Jennifer , Steen Geogina , Fallon Nessa , Maher Niamh , Lannon Rosaleen , McCarroll Kevin
Published: September 2024

Background

Denosumab is a commonly used to treat osteoporosis though should not be stopped without transitioning to bisphosphonates to reduce the risk of rebound bone loss and fracture. Recent NOGG guidelines recommend IV zoledronic acid (ZA) six months after the last denosumab injection with further infusions based on bone turnover markers (BTM).

Methods

We collated data (over the past 5 years) on the first follow up BTM measured after zoledronic acid treatment given to patients where denosumab was stopped. ZA was administered between 6-7 months after the last denosumab injection. The bone resorption marker (C-Telopeptide type I collagen, CTX ng/ml) was measured at different time points: 4 months, 4-6 months, and between 6-12 months. A subtherapeutic CTX was defined as > 0.300 ng/ml.

Results

There were 95 patients, 93% female, mean age 67.8 years and duration of denosumab therapy 4.6 years. Bone markers were significantly elevated from baseline at all timepoints. Mean CTX at 4 months was 0.450, 6 months 0.470 and 6-12 months 0.65. Overall, 45% had a subtherapeutic CTX at 4 months, 45% at 6 months and 70% between 6-12 (mean 9 months) and this was predicted by time from first ZA infusion (P=0.03).

Conclusion

Nearly half of patients had subtherapeutic BTM at 4-6 months and the majority at 6-12 months after receiving ZA. For patients on denosumab therapy for a similar duration (4-5 years), our results support the routine administration of a second ZA six months after their first ZA. Delays in administering a second infusion may result in a substantial rise in bone resorption markers and significant bone loss. This highlights the need for timely access to ZA for such patients transitioning off denosumab therapy.