bluuebunny/crossref_metadata_2025 huggingface dataset:
Electronic and structural properties of group IV materials and their polytypes
Authors: Ziembicki Jakub , Scharoch Paweł , Polak Maciej P. , Wiśniewski Michał , Kudrawiec Robert
Published: October 2024

Nanotechnology’s impact on semiconductor industry advancement, particularly through the engineering of nanostructures like nanowires, opens new possibilities for material functionality due to the tunable physical properties of nanostructures compared to bulk materials. This paper presents a comprehensive study on group IV semiconductors and their binaries across four polytypes: 2H, 3C, 4H, and 6H, focusing on their optoelectronic application potential. Deep understanding of these polytypes is particularly relevant for nanowire-based technologies. Through first principles modeling, we examine the structural and electronic properties of these materials, emphasizing their band structure, stability, and the feasibility for light-emitting applications. We use a generalized Ising model to discuss materials stability and tendency for polytypism. We also determine relative band edge positions and employ a six-band k⋅p  model for a detailed understanding of the materials’ electronic properties. Due to the comprehensive nature of this study, we provide insight on the chemical trends present in all of the studied properties. Our theoretical predictions align well with the existing experimental data, suggesting new avenues for nanostructure-based device development. The discussion extends to the implications of these findings for the fabrication of optoelectronic devices with the studied IV–IV materials, highlighting the challenges and opportunities for future research in nanowire synthesis and their applications.
Facets evolution of selected area grown GaAs in circular windows on Ge-on-Si and Ge substrates
Authors: Chen Zheqian , Wang Bing , Han Yu , Cai Xinlun , Yu Siyuan
Published: October 2024

We report the epitaxial growth of GaAs on Ge buffers on Si (001) substrates covered by SiO2 masks patterned with 3 μm diameter circular windows by metalorganic chemical vapor deposition. The influence of As partial pressure on the crystal quality and facet evolution of GaAs was investigated. Scanning electron microscopy and atomic force microscopy revealed that the GaAs within the window region exhibited a relatively flat (001) crystal facet. Under high As partial pressures, the {111} facets of GaAs showed a pronounced orientation preference. At lower As partial pressures, the {111} and {110} facets of GaAs were roughly equally represented, aligning with the facet distribution structure predicted under As-rich conditions by the equilibrium crystal shape theory. The growth condition of high As partial pressure can effectively improve the growth quality of GaAs and obtain smooth GaAs film with a lower roughness. Due to the polarity mismatch between GaAs and Ge, antiphase domains persisted. We obtained GaAs samples free from antiphase domains and threading dislocations by utilizing a Ge 6° offcut toward (111) substrate. This work introduces a feasible approach for heteroepitaxial integration of III-V semiconductor lasers, in particular the vertical cavity surface emitting lasers (VCSELs) on silicon substrates via direct growth, and the modulation of sidewall crystal facets for VCSELs.
Tunnel magnetoresistive sensors with non-hysteretic resistance–magnetic field curves using noncollinear interlayer exchange coupling through RuFe spacers
Authors: Kulkarni Prabhanjan D. , Nakatani Tomoya
Published: October 2024

Magnetic stabilization of the ferromagnetic layers of magnetoresistive elements is a key technological requirement for fabricating highly sensitive and accurate magnetic sensors. Here, we report on a tunnel magnetoresistive (TMR) sensor wherein the free layer (FL) magnetization is stabilized by combining exchange bias, noncollinear interlayer exchange coupling through a RuFe spacer, and orange-peel ferromagnetic coupling. This method facilitates stabilization of the FL magnetization over a wide range of noncollinear angles with respect to the pinning direction by controlling the composition of the RuFe spacer. Moreover, the uniaxial anisotropy induced in the FL by annealing plays an important role in the resistance–magnetic field (R–H) curve, which was studied both experimentally and through simulation. The TMR devices exhibited negligible hysteresis even in the major R–H loops, which is promising for magnetic field-sensing applications.
Heat transport and flow structure in vertical convection over rough sidewalls
Authors: Meng Xiaohui , Wu Jian-Zhao , Chong Kai Leong , Zhou Quan
Published: October 2024

We employ the direct numerical simulation to study the heat transfer behavior and flow structures in a vertical convection system with rough sidewalls. The parameters are chosen with Rayleigh number spanning the range of 1×108≤Ra≤3×1010 and Prandtl number fixed at 1.0. The results reveal that the impact of rough walls on the Nusselt number Nu and the Reynolds number Re is influenced by the height of the rough element h. When h is not sufficiently high, the roughness impedes the flows within the boundary layer and traps massive heat between rough elements, and both Nu and Re are lower than those in the smooth-wall case. However, the extent of the Nu and Re reduction regimes decreases as Ra increases. For sufficiently large Ra, the reduction regime for both Nu and Re may vanish, and roughness breaks up the limitation of the thermal boundary layer and facilitates the eruption of thermal plumes from roughness tips, resulting in the enhancement of both Nu and Re. Based on these results, the critical heights hc for Nu and hcr for Re are identified. Both exhibit similar scaling behavior with Ra, with hc consistently being larger than hcr for the same value of Ra.
Contribution of three-magnon scattering to Gilbert damping at elevated temperatures
Authors: Chen Yifei , Victora R. H.
Published: October 2024

Gilbert damping is a key parameter representing the energy loss in the Landau–Lifshitz–Gilbert equation, which describes the dynamics of magnetization and is crucial in micromagnetic simulations. We have developed an analytical method to calculate Gilbert damping based on the contributions from the three-particle magnon scattering process. By incorporating the exchange, anisotropic, and demagnetization energies, we applied this method to determine Gilbert damping at different temperatures. Our calculation shows that, near the Curie temperature, the calculated damping equals around 80% of the results obtained from the coarse-graining method proposed by Feng and Visscher in 2001, which means that three-magnon scattering gives a dominant contribution to Gilbert damping. This research may give useful insights into the relationship between Gilbert damping and magnons.
Scaling law of aero-optical steady-distortion for hemisphere-on-cylinder conformal-window turrets across the subsonic, transonic, and supersonic flows
Authors: Ren Xiang , Yu Huahua , Zhang Feizhou , Hu Peng , Su Hua
Published: October 2024

Aero-optical steady-distortion reduces the far-field quality of the forward-looking laser beam of an airborne turret. It has a complex relation with the viewing angle of the laser beam and the flow around the turret at different flight speeds. In this paper, the aero-optical steady-distortion, including the fixed tip/tilt and steady-lensing wavefront, for a hemisphere-on-cylinder turret with a conformal window is analyzed at different freestream Mach numbers (Ma∞=0.3–1.7) and window angles. Computational fluid dynamics and particle-based ray-tracing methods are combined to simulate the steady-state flow over the turret and its aero-optical effect. The scaling laws of the fixed tip/tilt and steady-lensing wavefront for the forward-looking laser beam are summarized under these subsonic, transonic, and supersonic flows. The results show that the scaling factor Ma∞2 is only applicable to the wavefront distortion caused by low-velocity flows, while the relevant scaling factors Ma∞2/[1+(γ+1)Ma∞2(γ+1)/(γ−1)] and (γ−1)/(2γ)Ma∞γ/(γ−1) are effective across subsonic/transonic and supersonic flows. The fixed tip/tilt is discussed separately, and its scaling factor and scaling law differ from the steady-lensing wavefront. In addition, the fixed tip/tilt and steady-lensing wavefront within these flow regimes are only related to the viewing angle, not the elevation angle.
Application of convolutional neural network for efficient turbulence modeling in urban wind field simulation
Authors: Zhao Rui , Zhong Siyang , You Ruoyu
Published: October 2024

Accurate flow field estimation is crucial for the improvement of outdoor environmental quality, but computational fluid dynamics (CFD) based on the widely used Reynolds-averaged Navier–Stokes method has limitations in this regard. This study developed a turbulence modeling framework based on a convolutional neural network (CNN) to model turbulence in urban wind fields. The CNN model was trained by learning the Reynolds stress patterns and spatial correlations with the use of high-fidelity datasets. Next, the model was integrated into the CFD solver to generate accurate and continuous flow fields. The generalization capability of the proposed framework was initially demonstrated on the simplified benchmark configurations. The validated framework was then applied to case studies of urban wind environments to further assess its performance, and it was shown to be capable of delivering accurate predictions of the velocity field around an isolated building. For more complex geometries, the proposed framework performed well in regions where the flow properties were covered by the training dataset. Moreover, the present framework provided a continuous and smooth velocity field distribution in highly complicated applications, underscoring the robustness of the proposed turbulence modeling framework.
Analysis of the flow field characterization on the cavitation water jet applied to planar and curved surfaces
Authors: Wang Jiaxiang , Wang Zunce , Xu Yan , Liu Haishui , Yan Yuejuan , Zhang Jinglong , Li Sen , Ge Mingming
Published: October 2024

Cavitation water jet technology offers a sustainable alternative to traditional high-energy, high-pollution production or cleaning methods in the biodiesel, injector, and turbine industries. Although widely applied, the dynamics of cavitation cloud evolution and erosion patterns on various surface constraints require further investigation. This paper examines how planar and differently curved surface constraints affect the spatiotemporal evolution of the cavitation cloud under submerged conditions. The flow field is experimentally observed by using a high-speed camera. Proper orthogonal decomposition is employed to analyze the characteristics of the cavitation flow field across these surface constraints. Additionally, large eddy simulation is used to explore the internal flow dynamics and progression of the cavitation cloud under varying target surface constraints. The findings provide deeper insight into the spatiotemporal evolution patterns of cavitation clouds against planar and curved surfaces, expanding the application of cavitation jet technology in diverse energy generation and conversion fields.
Multi-channel simultaneous emission non-invasive flow measurement system
Authors: Fang Lide , Sun Yiqian , Wang Zhongliang , Yuan Xinyue , Wang Mi
Published: October 2024

A multi-channel simultaneous emission non-invasive flow velocity measurement system is introduced and validated in this paper, which adapts to industrial large-diameter pipelines. In particular, the ultrasonic simultaneous emission mode is applied to the whole system to achieve real-time flow measurement. This technology reduces measurement errors in ultrasonic flow measurements caused by changes in fluid state and timing variations. Sixteen non-invasive ultrasonic transducers are used in the system, together with the precision measurement circuit, efficient data acquisition system and real-time display upper computer program. The flow rate can be accurately measured and displayed without interrupting the fluid flow. Furthermore, a period-invariant dual-threshold method is applied to locate feature points in the ultrasonic signals to ensure that high accuracy and stability are maintained in the final result.
A thorough experimental assessment of THz-TDS plasma diagnostic techniques for nuclear fusion applications
Authors: Galatola Teka G. , Peng K. , Alonzo M. , Bombarda F. , Koch-Dandolo C. L. , Senni L. , Taschin A. , Zerbini M.
Published: October 2024

In this paper, the study of a plasma diagnostic system based on the THz time domain spectroscopy technique is presented. Such a system could potentially probe a large part of the electromagnetic spectrum currently covered by several other diagnostics in a single measurement. This feature, keeping in mind the basic requirements for plasma diagnostics in nuclear fusion experiments, such as robustness and hard environment applicability, as well as durability and low maintenance, makes the diagnostic of great interest. A conceptual design of the THz-TDS diagnostic has been developed, starting from the well-established classical microwave and far infrared plasma diagnostics landscape. The physical constraints and required instrumental characteristics have been studied and are described in detail here, together with the solutions available for each type of plasma measurement. Specific experimental laboratory tests of the different experimental configurations have been carried out, evaluating the capacity and potential of the novel diagnostic, together with the instrumental constraint, within the diagnostic parameter space.
Target cell lysis using magnetophoresis: A numerical study with experimental validation
Authors: Dezhkam Rasool , Topaheidari Mohammadmahdi , Rostami Zohreh , Shamloo Amir
Published: October 2024

Cell lysis is one of the main steps in the deoxyribonucleic acid (DNA) extraction process, which makes vital information about organisms accessible for analysis. In the chemical cell lysis process, cells and lysis buffer mix, and the cell membrane is eliminated, and then DNA and other intracellular components are released. Mixing is not an easy step in microfluidic systems, and it reduces the chemical cell lysis efficiency. Therefore, a novel method has been implemented to address this issue. In this work, a magnetophoretic separation method is utilized to eliminate the mixing process and guide target cells directly inside the lysis buffer flow; integrating cell separation and cell lysis into a single platform enhances lysis efficiency. This method selectively lyses only the target cells that are pre-labeled with the antibody from the mixture of cells. These phenomena are combined in one simple straight channel and decrease the area used by the system, which is a desired goal in microsystems. Both numerical and experimental methods are utilized to separate magnetized cancer cells as circulating tumor cells from blood cells and guide them to a region having an appropriate concentration of lysis buffer. To optimize the system, parameters including inlet velocity, number of magnets, and distance between magnets and channel were studied, whereby 8 mm and five magnets were considered for optimum values of distance and number of magnets, respectively. According to the results, the fluid velocity was the key parameter for the target cell lysis phenomenon due to its influence on both mass transfer and cell separation phenomena. It was observed that lower velocities resulted in more cell separation efficiency, and higher velocities had better outcome in mass transfer. Finally, between a wide range of velocities from 0.1 to 50 mm/s, the 10 mm/s velocity was selected as the optimum inlet velocity, which showed 100% separation efficiency and a concentration of 0.55 mM for the target outlet.
The neurotrophic factor MANF regulates autophagy and lysosome function to promote proteostasis in
Caenorhabditis elegans
Authors: Taylor Shane K. B. , Hartman Jessica H. , Gupta Bhagwati P.
Published: October 2024

The conserved mesencephalic astrocyte-derived neurotrophic factor (MANF) is known for protecting dopaminergic neurons and functioning in various other tissues. Previously, we showed that
Caenorhabditis elegans manf-1
null mutants exhibit defects such as increased endoplasmic reticulum (ER) stress, dopaminergic neurodegeneration, and abnormal protein aggregation. These findings suggest an essential role for MANF in cellular processes. However, the mechanisms by which intracellular and extracellular MANF regulate broader cellular functions remain unclear. We report a unique mechanism of action for MANF-1 that involves the transcription factor HLH-30/TFEB-mediated signaling to regulate autophagy and lysosomal function. Multiple transgenic strains overexpressing MANF-1 showed extended lifespan of animals, reduced protein aggregation, and improved neuronal survival. Using fluorescently tagged MANF-1, we observed tissue-specific localization of the protein, which was dependent on the ER retention signal. Further subcellular analysis showed that MANF-1 localizes within cells to the lysosomes and utilizes the endosomal pathway. Consistent with the lysosomal localization, our transcriptomic study of MANF-1 and analyses of autophagy regulators demonstrated that MANF-1 promotes proteostasis by regulating autophagic flux and lysosomal activity. Collectively, our findings establish MANF as a critical regulator of stress response, proteostasis, and aging.
Hydroelectric energy conversion of waste flows through hydroelectronic drag
Authors: Coquinot Baptiste , Bocquet Lydéric , Kavokine Nikita
Published: October 2024

Hydraulic energy is a key component of the global energy mix, yet there exists no practical way of harvesting it at small scales, from flows with low Reynolds number. This has triggered a search for alternative hydroelectric conversion methodologies, leading to unconventional proposals based on droplet triboelectricity, water evaporation, osmotic energy, or flow-induced ionic Coulomb drag. Yet, these approaches systematically rely on ions as intermediate charge carriers, limiting the achievable power density. Here, we predict that the kinetic energy of small-scale “waste” flows can be directly and efficiently converted into electricity thanks to the hydroelectronic drag effect, by which an ion-free liquid induces an electronic current in the solid wall along which it flows. This effect originates in the fluctuation-induced coupling between fluid motion and electron transport. We develop a nonequilibrium thermodynamic formalism to assess the efficiency of such hydroelectric energy conversion, dubbed hydronic energy. We find that hydronic energy conversion is analogous to thermoelectricity, with the efficiency being controlled by a dimensionless figure of merit. However, in contrast to its thermoelectric analogue, this figure of merit combines independently tunable parameters of the solid and the liquid, and can thus significantly exceed unity. Our findings suggest strategies for blue energy harvesting without electrochemistry, and for waste flow mitigation in membrane-based filtration processes.
Digital play as procedures
Authors: Kato Hiloko
Published: October 2024

This article aims to analyse the participants’ multimodal interaction in the innovative technology
of Spacecraft: A New Way Home, a co-located multiplayer VR game designed as a master’s thesis
artefact at the Zurich University of the Arts in the discipline of Game Design. Using fine-grained sequential
analyses, three practices are investigated in particular: first, practices that rely heavily on social rules,
providing security and guidance in the unknown virtual space; second, practices that are based on the technological
rules of VR, expressed in terms of a certain kind of digital — here, VR — literacy; third, practices that are imposed
by the game itself as a rule-based artefact, coining the general frame of the game in which digital play occurs. This
amalgamation of the three practices can be understood as a fundamental framework by which to comprehend digital play
procedures in general.
Dissolved concentration and lifetime of ozone ultrafine bubbles
Authors: Miyazaki Atsuhiro , Komazawa Shin , Ogata Satoshi
Published: October 2024

Ozone has a broad potential application scope, including sterilization, water purification, and wastewater treatment. However, these applications are limited by its instability and short lifetime. Ozone ultrafine bubbles (UFBs) were observed to increase the dissolved concentration and lifetime of ozone; however, the mechanism involved has not yet been comprehensively analyzed. This study aims to experimentally elucidate the effect of ozone conversion to UFBs on ozone concentration and lifetime. We analyzed the two methods primarily used for ozone UFB generators: ozone direct dissolution and ozone pressure mixing and dissolution. We measured the dissolved ozone concentration and lifetime of the ozone UFBs. Furthermore, we measured the particle size distribution, from which we calculated the specific surface area per unit volume. We experimentally demonstrated that the ozone direct dissolution method achieved an increase in the concentration of dissolved ozone due to the increase in the ozone transfer as the specific surface area increased. However, the lifetime achieved was considered to be insufficient for use as a disinfectant solution. We used the ozone pressure mixing and dissolution method to achieve the concentration lifetime required for use as a disinfectant, with a flow rate of 40 l min−1 when the number of bubbles was proportional to the flow rate. This represents a considerable advancement in the use of ozone UFB water as a portable disinfectant.
Topological signatures of triply degenerate fermions in Heusler alloys: an ab initio study
Authors: Dhori Bhautik R , Mohanta Aritri , Jha Prafulla K
Published: October 2024

Triply degenerate nodal point (TP) fermions, lacking elementary particle counterparts, have been theoretically anticipated as quasiparticle excitations near specific band crossing points constrained by distinct space-group symmetries instead of Lorentz invariance. Here, based on first-principles calculations and symmetry analysis, we demonstrate the presence of TP fermions in Heusler alloys. Furthermore, we predict that these Heusler alloys are dynamically stable, exhibiting TP fermions along four distinct C
3 axes in the F-43m space group. We show that α-LiCaPdSb harbours peculiar Fermi arcs and surface states on the (111) and (001) crystal facets, owing to the coexistence of threefold rotational and time reversal symmetry. More interestingly, a modest tensile strain can increase the distance of fermions along the Γ-L high symmetric line by as much as 21.10%, which give rise to measurable Fermi arcs. Furthermore, we investigate non-trivial topological insulator phase in β-LiCaPdSb, by changing the chemical environment through placing transition metal atoms at various Wyckoff positions. The β-LiCaPdSb harbour a semi-metallic nature, and by breaking cubic symmetry, it undergoes a transition from semi-metal to a non-trivial topological insulator. In addition, for the first time, rare-earth LaPtBi half-Heusler alloy is examined under strain to uncover multiple band inversions associated with the TP fermionic phase. The observed multiple band inversion is entirely unaffected by spin–orbit coupling. We show that the LaPtBi compound hosts TP fermions, which are linked to a

Z

2

topological invariant. Remarkably, with clear band crossings and multiple band inversion, we point out the possibilities of the LaPtBi for displaying a rich topological phase diagram. Our work provides a prototype material platform for experimental detection through angle-resolved photoemission spectroscopy or scanning tunnelling spectroscopy and practical spintronic applications.
Recent advances in understanding and manipulating magnetic and electronic properties of EuM2X2 (M = Zn, Cd; X = P, As)
Authors: Chen Xiyu , Dong Shuai , Wang Zhi-Cheng
Published: October 2024

Over the past five years, significant progress has been made in understanding the magnetism and electronic properties of CaAl2Si2-type EuM
2
X
2 (M = Zn, Cd; X = P, As) compounds. Prior theoretical work and experimental studies suggested that EuCd2As2 had the potential to host rich topological phases, particularly an ideal magnetic Weyl semimetal state when the spins are polarized along the c axis. However, this perspective is challenged by recent experiments utilizing samples featuring ultra-low carrier densities, as well as meticulous calculations employing various approaches. Nonetheless, the EuM
2
X
2 family still exhibit numerous novel properties that remain to be satisfactorily explained, such as the giant nonlinear anomalous Hall effect and the colossal magnetoresistance effect. Moreover, EuM
2
X
2 compounds can be transformed from semiconducting antiferromagnets to metallic ferromagnets by introducing a small number of carriers or applying external pressure, and a further increase in the ferromagnetic transition temperature can be achieved by reducing the unit cell volume. These features make the EuM
2
X
2 family a fertile platform for studying the interplay between magnetism and charge transport, and an excellent candidate for applications in spintronics. This paper presents a comprehensive review of the magnetic and transport behaviors of EuM
2
X
2 compounds with varying carrier densities, as well as the current insights into these characteristics. An outlook for future research opportunities is also provided.
Strain induced phase transitions and hysteresis in aluminium nitride: a density functional theory study
Authors: Namir O , Chen J , Belabbas I
Published: October 2024

Computer atomistic simulations based on density functional theory were carried out to investigate strain induced phase transitions in aluminium nitride (AlN). The wurtzite to graphitic and graphitic to wurtzite transformations were investigated at the atomic level and their physical origins were identified. Both phase transitions were found to be of the first order. The wurtzite to graphitic phase transition takes place in the tensile regime at a strain value of +7%. The driving force for this transformation was identified to be an elastic instability induced by tensile strain. A hysteresis was demonstrated where the graphitic structure is separated from the wurtzite by a kinetic energy barrier. The origin of the observed hysteresis is due to the asymmetry of bond formation and bond breaking associated with the wurtzite to graphitic and graphitic to wurtzite transitions, respectively. A dynamic instability taking place at +3%, along the graphitic path, prevents the hysteresis to fully occur. The possible occurrence of the hysteresis has then to be taken into account when growing the graphitic phase by heteroepitaxy. Otherwise, maintaining the graphitic structure at low strain, through the hysteresis, offers new possibilities in the development of novel future applications.
A multi-level prediction model of concrete dam displacement considering time hysteresis and residual correction
Authors: Xu Bo , Zhang Hu , Xia Hui , Song Dalai , Zhu Zhenhao , Chen Zeyuan , Lu Junyi
Published: October 2024

Displacement directly reflects the operational status of dams and exhibits time hysteresis. Moreover, data-driven predictive models fail to account for all physical mechanisms, leaving valuable information uncaptured in residuals. Hence, this study establishes a multi-level displacement prediction model for concrete dams considering the time hysteresis of monitoring data and residual correction. Initially, employing Bayesian optimization gated recurrent units (BO-GRU) and considering multivariate time series (MTS) prediction, a single-level displacement prediction model, MTS-BO-GRU, is developed to capture displacement time hysteresis. Subsequently, acknowledging the chaotic characteristics in residual sequences, a random forest (RF) model is utilized in conjunction with univariate time series (UTS) prediction to correct residual sequences, resulting in the UTS-RF model. The corrected values are then combined with the predicted values of the MTS-BO-GRU model to establish the MTS-BO-GRU+ multi-level displacement prediction model. Finally, employing an in-service concrete dam as a case study, the performance of the proposed multi-level model is compared to validate and evaluate its superiority. Results demonstrate that the MTS-BO-GRU+ model, considering displacement time hysteresis and residual correction, exhibits the best predictive performance. Additionally, MTS prediction effectively captures displacement time hysteresis, while the UTS-RF model efficiently identifies valuable information in residual sequences. This research provides scientific basis and technical support for dam safety monitoring, health service diagnosis, and operational management, offering new insights for structural health monitoring.
Hydraulic valve fault diagnosis based on EEWT and POA-KELM
Authors: Chen Rongchun , Chen Chao , Kelimu Muhetaer
Published: October 2024

With the wide application of hydraulic systems in the industrial and mechanical fields, the analysis and study of hydraulic valve failures have become increasingly important. This study aims to identify and analyze possible faults by analyzing the operating status of hydraulic valves under different loads. In this study, we propose using a combination of two phases for the failure analysis of hydraulic valves. The first stage is the signal processing stage, in which the pressure signals of hydraulic valves under different loads are collected, the pressure signals are decomposed using the extended empirical wavelet transform (EEWT) to obtain a series of sub-signal components, and the 17 eigenvectors of these components are computed, and the feature selection is carried out using the method of sequence backward selection. Next is the classification stage, where the features selected in the first stage are input into a kernel extreme learning machine (KELM) classifier improved by the Pelican optimization algorithm (POA) to classify and identify the anomalous signals. The experimental results show that the fault diagnosis method based on EEWT and POA-KELM can effectively detect and recognize hydraulic valve faults.
Denoising diffusion probabilistic model enhanced tool condition monitoring method under imbalanced conditions
Authors: Fu Yuandie , Zhong Meipeng , Huang Junfeng , Jiang Youhui , Sun Weifang , Lou Yongjian , Wang Gonghai , Zhou Yuqing
Published: October 2024

In recent years, tool condition monitoring (TCM) based on deep learning has been widely considered and achieved remarkable success. However, these methods typically require relatively large training samples to produce significant results, which are both imbalanced and rather troublesome to obtain in the practical application of TCM. To address this issue, a novel TCM method combined with multiscale permutation entropy (MPE), denoising diffusion probabilistic model (DDPM) and a residual network (ResNet) is proposed under conditions of sample imbalance. First, the one-dimensional sensing signal data is converted to a grayscale recurrence plot (RP) by minimizing the MPE of the signals in each channel. Second, combine and splice these grayscale RPs from different channels in each sample into color RPs. After that, the generated RP images using DDPM are added to the imbalanced dataset to augment the data to achieve a balanced state of the dataset. Finally, the balanced mixed data set of real and fake samples is input into a ResNet for recognition and monitoring tool conditions. TCM experiments are conducted to verify the performance of the proposed method with imbalanced dataset, and the results of experimental investigation demonstrate that the accuracy of the proposed method improved by 2%–18.8% compared to that of the other four sample augmentation methods using ResNet18 when the imbalance rate is 1:200.
Detection of delamination using laser-generated Lamb waves with improved wavenumber analysis
Authors: Yang Shixi , Guo Zixuan , He Jun , Cheng Qichao , Xiong Xin
Published: October 2024

Delamination is a typical failure mode in multilayered materials, which may potentially threaten the safety and reliability of the materials if not detected promptly. This paper proposes a novel quantitative detection method for delamination in multilayered materials based on laser-generated Lamb waves with improved wavenumber analysis. First, a three-dimensional (3D) finite element model is established to simulate the interaction between delamination and laser-generated Lamb waves. The propagation characteristics of Lamb waves in multilayered materials without defects and with delamination of three different shapes, i.e. rectangular, circular and triangular are analyzed. And the mechanism that delamination can lead to the appearance of scattered wave and new wavenumber components is investigated, facilitating the quantitative detection of delamination. Then, an improved wavenumber analysis method for quantitative detection of delamination is proposed. The new wavenumber components caused by delamination are extracted by broadband adaptive wavenumber filtering to reduce imaging interference and artifacts caused by irrelevant components, and the spatial wavenumber spectrum is obtained by fast broadband local wavenumber estimation algorithm to enhance the delamination imaging accuracy and spatial resolution. The experimental results indicate that, across various experimental scenarios, the proposed method achieves superior imaging precision compared to traditional wavenumber filtering or local wavenumber estimation methods, and can quantitatively identify delamination defects of various shapes and sizes.
Nonzero-sum game-based decentralized approximate optimal control of modular robot manipulators with coordinate operation tasks using value iteration
Authors: Dong Bo , Gao Yuhang , An Tianjiao , Jiang Hucheng , Ma Bing
Published: October 2024

Accurate trajectory tracking and appropriate contact force are crucial for the coordinated operation-oriented control of modular robot manipulators (MRMs). Considering the practical need for precision in system control, resource optimization, and disturbance compensation within the context of the coordinated operation tasks (COTs) of MRMs, this paper employs a value iteration (VI) technique to devise a decentralized approximate optimal control strategy grounded in nonzero-sum game (NZSG) theory. To obtain more accurate, reliable, and safe control, a dynamic model of the MRM is established using joint torque feedback technology; then, the problem of optimal control for MRM systems focused on coordinated operation-oriented control is reformulated as an NZSG involving multiple subsystems. The present study, grounded in the theoretical framework of the adaptive dynamic programming (ADP) algorithm, employs an event-triggered NZSG strategy, utilizing VI to resolve the coupled Hamilton–Jacobian equations, culminating in the derivation of the Nash equilibrium solutions. Through stringent stability analysis, it is established that the trajectory tracking error for the closed-loop MRM system engaged in COTs is uniformly ultimately bounded. The proposed method’s efficacy is subsequently corroborated through experimental validation.
Improved DV-Hop algorithm based on geometric Brownian motion model under communication interference
Authors: Zhang Lieping , Huang Zichen , Yin Yameng , Tan Mingyang , Zhang Cui
Published: October 2024

In a mobile sensor network, a traditional positioning algorithm is unable to locate unknown nodes when losing anchor positions caused by communication interference. To solve this problem, an improved DV-Hop algorithm based on a geometric Brownian motion (GBM) model was proposed including two main stages: location of sink node (LSN) and location of blind node (LBN). In the LSN stage, if the signal transmission of anchors is normal, the GBM model records the moving positions of the anchors. If not, the GBM model predicts the estimated average positions of the anchors using recorded data. Then, the trial count of the GBM model is optimized to further improve the prediction accuracy and computational overhead. In the LBN stage, the unknown nodes’ positions are obtained by the DV-Hop algorithm. In a traditional DV-Hop algorithm, the approximate minimum hop number and average hop distance may lead to huge deviation between true position and estimated position. To improve the positioning accuracy in the LBN stage, the strategies of multi-communication radius and hop distance weighting were adopted. The simulation results demonstrated that the proposed algorithm has the capability to resist communication interference and adaptability at different node speeds , maintaining a relatively high accuracy in locating unknown nodes.
Formation of the hard-magnetic epsilon iron oxide phase from akaganéite nanoparticles
Authors: Joseph Navya , Gopi Surya , Ullrich Aladin , Albrecht Manfred , Thomas Senoy
Published: October 2024

Elongated akaganéite (β-FeOOH) nanoparticles were prepared by a forced hydrolysis route using FeCl3
·6H2O employing various urea concentrations. β-FeOOH nanoparticles stabilized within the SiO2 matrix were annealed at different temperatures, ranging from 500 °C to 1300 °C. It was observed that β-FeOOH underwent a temperature-induced conversion to γ-Fe2O3 and subsequently to ϵ-Fe2O3. Due to the ϵ-Fe2O3 phase formation, the coercivity rapidly increased to 16 kOe for samples annealed at 900 °C and reached values up to 21.5 kOe when annealed at 1200 °C. At a higher temperature of 1300 °C, the ϵ-Fe2O3 phase transforms mainly into the α-Fe2O3 phase, which causes the coercivity to rapidly drop to negligible values.
NiO/MnO2 coated on carbon felt as an electrode material for supercapacitor applications
Authors: Azizi Sadegh , Askari Mohammad Bagher , Rozati Seyed Mohammad , Masoumnezhad Mojtaba
Published: October 2024

Transition metal oxides have demonstrated excellent capability for charge storage when used in supercapacitor electrodes. This study undertook the hydrothermal synthesis of bimetallic nickel and manganese oxide (NiO/MnO2) on a carbon-felt (CF) substrate. NiO/MnO2/CF electrode was characterized and examined in a three-electrode system in a potassium hydroxide electrolyte. Cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge analyses revealed Faradaic behavior during charge storage, a specific capacity of 1627 F g−1, and a stability of 96.8% after 5000 consecutive charge-discharge cycles. Subsequent investigations were conducted in a two-electrode system for constructing a symmetrical supercapacitor using the NiO/MnO2/CF electrode. The energy and power densities were determined as 43Wh kg−1 and 559 W kg−1. Additionally, the stability of the constructed supercapacitor device was examined over 5000 consecutive cycles, verifying a 92% stability through charge-discharge cycles. Finally, the fabricated supercapacitor was utilized to power an LED lamp, successfully maintaining the illumination for 53 s.
Piezoelectric dispenser printing and intense pulsed light sintering of AgNW/PEDOT:PSS hybrid transparent conductive films
Authors: Noh Youngwook , Cho Kwan Hyun
Published: October 2024

A hybrid transparent conductive films (TCFs) combining silver nanowires (AgNWs) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) was fabricated using a piezoelectric dispenser printing method. The innovation lies in optimizing the ink composition and employing intense pulsed light sintering to enhance the TCF’s performance. The optimized AgNW/PEDOT:PSS mixture, with an 8:2 ratio, achieved a figure of merit (FOM) of 28.05 × 10−3 Ω−1, corresponding to a sheet resistance of 9.93 Ω sq−1 and a transmittance of 88.0%. This represents a significant improvement over the pre-sintering FOM of 24.09 × 10−3 Ω−1. Additionally, the hybrid TCFs exhibited outstanding structural stability, maintaining functionality after 7000 mechanical bending cycles. The results enable applications in flexible optoelectronic devices, and highlight the potential of this method to produce high-performance, flexible, and durable transparent electrodes, advancing the development of next-generation optoelectronic devices.
Generalized invariant measures for non-autonomous conformal iterated function systems
Authors: Nakajima Yuto , Takahashi Yuki
Published: October 2024

We consider Non-autonomous Conformal Iterated Function Systems (NCIFS) in the overlapping case. We focus on the parameterized families of NCIFS that satisfy the transversality condition, and give a dimension formula for the generalized invariant measure for a.e. parameter. We also give a sufficient condition that the generalized invariant measure is absolutely continuous for a.e. parameter.
Slow descent of a spinning washer on a vertical threaded rod
Authors: Cross Rod
Published: October 2024

An experiment is described where a washer falls very slowly down a threaded rod since the friction force on the washer is equal and opposite the gravitational force.
Sparse-Laplace hybrid graph manifold method for fluorescence molecular tomography
Authors: Wang Beilei , Li Shuangchen , Zhang Heng , Zhang Lizhi , Li Jintao , Yu Jingjing , He Xiaowei , Guo Hongbo
Published: October 2024

Objective. Fluorescence molecular tomography (FMT) holds promise for early tumor detection by mapping fluorescent agents in three dimensions non-invasively with low cost. However, since ill-posedness and ill-condition due to strong scattering effects in biotissues and limited measurable data, current FMT reconstruction is still up against unsatisfactory accuracy, including location prediction and morphological preservation. Approach. To strike the above challenges, we propose a novel Sparse-Laplace hybrid graph manifold (SLHGM) model. This model integrates a hybrid Laplace norm-based graph manifold learning term, facilitating a trade-off between sparsity and preservation of morphological features. To address the non-convexity of the hybrid objective function, a fixed-point equation is designed, which employs two successive resolvent operators and a forward operator to find a converged solution. Main results. Through numerical simulations and in vivo experiments, we demonstrate that the SLHGM model achieves an improved performance in providing accurate spatial localization while preserving morphological details. Significance. Our findings suggest that the SLHGM model has the potential to advance the application of FMT in biological research, not only in simulation but also in in vivo studies.
Study on the impact of bowtie filter on photon-counting CT imaging
Authors: Zhang Xin , Xie Jixiong , Su Ting , Zhu Jiongtao , Xia Dongmei , Zheng Hairong , Liang Dong , Ge Yongshuai
Published: October 2024

Objective. The aim of this study was to investigate the impact of the bowtie filter on the image quality of the photon-counting detector (PCD) based CT imaging. Approach. Numerical simulations were conducted to investigate the impact of bowtie filters on image uniformity using two water phantoms, with tube potentials ranging from 60 to 140 kVp with a step of 5 kVp. Subsequently, benchtop PCD-CT imaging experiments were performed to verify the observations from the numerical simulations. Additionally, various correction methods were validated through these experiments. Main results. It was found that the use of a bowtie filter significantly alters the uniformity of PCD-CT images, depending on the size of the object and the x-ray spectrum. Two notable effects were observed: the capping effect and the flattening effect. Furthermore, it was demonstrated that the conventional beam hardening correction method could effectively mitigate such non-uniformity in PCD-CT images, provided that dedicated calibration parameters were used. Significance. It was demonstrated that the incorporation of a bowtie filter results in varied image artifacts in PCD-CT imaging under different conditions. Certain image correction methods can effectively mitigate and reduce these artifacts, thereby enhancing the overall quality of PCD-CT images.
Robust optimization incorporating weekly predicted anatomical CTs in IMPT of nasopharyngeal cancer
Authors: Chan Mark Ka Heng , Zhang Ying
Published: October 2024

Objective. This study proposes a robust optimization (RO) strategy utilizing virtual CTs (vCTs) predicted by an anatomical model in intensity–modulated proton therapy (IMPT) for nasopharyngeal cancer (NPC). Methods and Materials. For ten NPC patients, vCTs capturing anatomical changes at different treatment weeks were generated using a population average anatomy model. Two RO strategies of a 6 beams IMPT with 3 mm setup uncertainty (SU) and 3% range uncertainty (RU) were compared: conventional robust optimization (cRO) based on a single planning CT (pCT), and anatomical RO incorporating 2 and 3 predicted anatomies (aRO2 and aRO3). The robustness of these plans was assessed by recalculating them on weekly CTs (week 2–7) and extracting the voxel wise–minimum and maximum doses with 1 mm SU and 3% RU (voxmin\voxmax1mm3%). Results. The aRO plans demonstrated improved robustness in high-risk CTV1 and low-risk CTV 2 coverage compared to cRO plans. The weekly evaluation showed a lower plan adaptation rate for aRO3 (40%) vs. cRO (70%). The weekly nominal and voxmax1mm3% doses to OARs, especially spinal cord, are better controlled relative to their baseline doses at week 1 with aRO plans. The accumulated dose analysis showed that CTV1&2 had adequate coverage and serial organs (spinal cord and brainstem) were within their dose tolerances in the voxmin\voxmax1mm3%, respectively. Conclusion. Incorporating predicted weekly CTs from a population based average anatomy model in RO improves week–to–week target dose coverage and reduces false plan adaptations without increasing normal tissue doses. This approach enhances IMPT plan robustness, potentially facilitating reduced SU and further lowering OAR doses.
Key issues review: useful autonomous quantum machines
Authors: Antonio Marín Guzmán José , Erker Paul , Gasparinetti Simone , Huber Marcus , Yunger Halpern Nicole
Published: October 2024

Controlled quantum machines have matured significantly. A natural next step is to increasingly grant them autonomy, freeing them from time-dependent external control. For example, autonomy could pare down the classical control wires that heat and decohere quantum circuits; and an autonomous quantum refrigerator recently reset a superconducting qubit to near its ground state, as is necessary before a computation. Which fundamental conditions are necessary for realizing useful autonomous quantum machines? Inspired by recent quantum thermodynamics and chemistry, we posit conditions analogous to DiVincenzo’s criteria for quantum computing. Furthermore, we illustrate the criteria with multiple autonomous quantum machines (refrigerators, circuits, clocks, etc) and multiple candidate platforms (neutral atoms, molecules, superconducting qubits, etc). Our criteria are intended to foment and guide the development of useful autonomous quantum machines.