bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical processing and thermal stability of the equiatomic high entropy alloy TiVZrNbHf under vacuum and hydrogen pressure
Authors: Schweiger Lukas , Römer Felix , Gizer Gökhan , Burtscher Michael , Kiener Daniel , Pistidda Claudio , Schökel Alexander , Spieckermann Florian , Eckert Jürgen
Published: June 2024

This study investigates the potential of nanostructuring the equiatomic high entropy alloy TiVZrNbHf by high-pressure torsion to improve its already promising hydrogen absorption properties. The detailed microstructural analysis of the material after processing demonstrates that a homogenous single-phase nanocrystalline structure can be obtained despite shear band development. Due to the metastable character of many high entropy alloys, this analysis was complemented by investigating the thermal stability of the alloy under both vacuum and hydrogen pressure. For the latter, the material was characterized via in situ X-ray diffraction during hydrogen charging at 500 °C, giving a detailed insight into the phase evolution during initial absorption and subsequent cycling. These experiments evidenced the inherent metastability of TiVZrNbHf, which resulted in its decomposition into a bcc, hcp, and C14 Laves phase under both vacuum and hydrogen atmospheres. Despite decomposition, the material retained its nanocrystalline structure under hydrogen pressure, presumably due to hydride formation, while significant grain growth occurred under vacuum. These findings deepen the understanding of the deformation and hydrogen charging behavior of this promising high entropy alloy, suggesting an approach for engineering such alloys for enhanced stability and performance, particularly in solid-state hydrogen storage applications.
A chaotic map with two-dimensional offset boosting
Authors: Wang Zhihao , Li Chunbiao , Li Yongxin , Liu Sicong , Akgul Akif
Published: June 2024

A chaotic map with two-dimensional offset boosting is exhaustively studied, which is derived from the Lozi map and shows the controllability of amplitude control. The mechanism of two-dimensional offset boosting is revealed based on the cancelation of offset-involved feedback terms. Furthermore, the coexistence of homogeneous multistability and heterogeneous multistability is disclosed when the offset boosting turns to the initial condition. It is also found that the independent constant term rescales the amplitude of all the sequences without changing the Lyapunov exponents. More strikingly, the parameters for amplitude control and offset boosting are bound together introducing hybrid control. The circuit implementation based on the microcontroller unit is used to validate the theoretical analysis and numerical simulations. This chaotic map is applied for particle swarm optimization showing its stronger performance and robustness in solving optimization problems.
Exploring surface properties and premelting in crystals
Authors: Tipeev Azat O. , Gurashkin Alexander L. , Zanotto Edgar D.
Published: June 2024

Crystal surfaces play a pivotal role in governing various significant processes, such as adsorption, nucleation, wetting, friction, and wear. A fundamental property that influences these processes is the surface free energy, γ. We have directly calculated γ(T) for low-index faces of Lennard-Jones (LJ), germanium, and silicon crystals along their sublimation lines using the computational cleavage technique. Our calculations agree well with experimental values for Si(111) and Ge(111), highlighting the accuracy of the method and models used. For LJ crystals, we identified a premelting onset at Tpm = 0.75Tm, marked by a sharp increase in atom mobility within the second outermost surface layer. Notably, Tpm closely aligned with the endpoint of the LJ melting line at negative pressures, Tend = 0.76Tm. We hypothesize that the emergence and coexistence of a liquid film atop the LJ crystal at Tpm < T < Tm correspond to the metastable melting line under negative pressures experienced by stretched crystal surfaces. Furthermore, our study of thin LJ crystal slabs reveals that premelting-induced failure leads to recrystallization below the homogeneous freezing limit, offering a promising avenue to explore crystal nucleation and growth at extremely deep supercoolings. Finally, no evidence of premelting was detected in the model crystals of Ge and Si, which is consistent with the experimental observations. Overall, our findings offer valuable insights into crystal surface phenomena at the atomic scale.
3.3 kV-class NiO/β-Ga2O3 heterojunction diode and its off-state leakage mechanism
Authors: Wan Jiangbin , Wang Hengyu , Zhang Chi , Li Yanjun , Wang Ce , Cheng Haoyuan , Li Junze , Ren Na , Guo Qing , Sheng Kuang
Published: June 2024

This Letter demonstrates a high-performance 3.3 kV-class β-Ga2O3 vertical heterojunction diode (HJD) along with an investigation into its off-state leakage mechanism. The vertical β-Ga2O3 HJD with field plate assisted deep mesa (FPDM) termination was fabricated using a self-aligned technique to etch the deep mesa to a depth of 9 μm, thereby reducing electric field crowding at the anode edge. In addition, a thick dielectric is deposited to fill the trench, facilitating the utilization of a field plate to further reduce the electric field at the anode edge. TCAD (Technology Computer Aided Design) simulations show significant suppression of electric field crowding at the anode edge. The fabricated HJD exhibits a high current swing of ∼1010 over a temperature range from 25 °C to 175 °C. The specific on-resistance (Ron,sp) is extracted to be 3.9 mΩ cm2, and the breakdown voltage is 3.42 kV with the FPDM termination. These conduction and blocking characteristics lead to a high power figure of merit of 3 GW/cm2, which is one of the highest among multi-kilovolt β-Ga2O3 diodes. Furthermore, the off-state current leakage mechanism of the HJD under a reverse bias up to 2000 V was investigated. The fitted results reveal that the leakage current is primarily dominated by Poole–Frenkel (PF) emission, with the trap level of PF extracted to be 0.36 eV below the conduction band of NiO.
Cold obstacle influence on nanofluid convection in porous cavity
Authors: Akram U. , Tang Z.
Published: June 2024

Enclosure design has a substantial influence on thermal engineering procedures and technology, such as electronics, thermal exchangers, power engines, heating systems, solar panels, and nuclear power plants. Triangular enclosures with different aspect ratios are used for multiple-purpose optimization and enhanced thermal efficiency in microchannels. Triangle enclosures with cold cylinders are often used to reduce heat loss in thermal exchange devices and nanoscale thermal sinks. The objective of the current study is to explore the natural convection of a hybrid nanofluid within a wavy-bottom triangular porous cavity containing an embedded cold inverted triangle, all under the influence of an inclined magnetic field. The inner inverted triangle maintains a lower temperature, while the wavy bottom wall of the outer triangular cavity acts as an isothermal heat source at high temperatures. The space between the inner and outer triangles is filled with hybrid nanofluid (Ag–MgO– water). The numerical solution for the modeled mathematical framework is derived using the open-source finite element program COMSOL. A wavy triangle enclosure is used in this work to analyze key elements, such as the Hartmann number, Ha, the Rayleigh number, Ra, the volume fraction, ϕ, the Darcy number, Da, and the inclination, γ. The local distribution of streamlines, velocity profile, isotherms, and entropy production are demonstrated along with the average Nusselt number. The findings reveal that the heat transfer rate and the total entropy generation increase with increase in Da, while their values decrease with increase in Ha. The value of Nu is raised with increase in the volume fraction ϕ and Rayleigh number Ra. The velocity profile shows increase with increase in the volume fraction ϕ and Rayleigh number Ra.
Event-triggered protocol-based adaptive impulsive control for delayed chaotic neural networks
Authors: Diao Weilu , He Wangli
Published: June 2024

This article focuses on the synchronization problem of delayed chaotic neural networks via adaptive impulsive control. An adaptive impulsive gain law in a discrete-time framework is designed. The delay is handled skillfully by using the Lyapunov–Razumikhin method. To improve the flexibility of impulsive control, an event-triggered impulsive strategy to determine when the impulsive instant happens is designed. Additionally, it is proved that the event-triggered impulsive sequence cannot result in the occurrence of Zeno behavior. Some criteria are derived to guarantee synchronization for delayed chaotic neural networks. Eventually, an illustrative example is presented to empirically validate the effectiveness of the suggested strategy.
Micro-structured lateral thermal lens for increased output power and narrowed beam divergence in kilowatt-class 9xx nm diode laser bars
Authors: Miah M. J. , Martin D. , Ginolas A. , Elattar M. , Della Casa P. , Grützner S. , Strohmaier S. , Knigge A. , Tränkle G. , Crump P.
Published: June 2024

Local temperature non-uniformity is a critical limit to power in large-area semiconductor lasers, playing a larger role than the conversion efficiency and temperature sensitivity in the most efficient modern devices. For the specific case of kilowatt-level edge-emitting diode laser bars, we demonstrate that laterally re-distributing current locally within each emitter using a customized micro-structuring of the electrical contact can flatten the thermal profile, based on the thermal design using COMSOL. The concept is demonstrated experimentally in adapted bars that contain eight broad-area emitters, each having wide (∼1100 μm) stripes and a 4 mm long resonator. Each emitter in the laser bar has an electrical contact layer that is electrically structured into parallel sub-contacts using implantation, essential to prevent lateral lasing, implemented here with a period of 29 μm. The width of the individual sub-contacts is narrowed in the device center and then monotonically increased toward the emitter edges to collect a higher proportion of heat at the edges, for a fivefold reduction in the thermal lens, despite a significant (20%) overall increase in electrical and thermal resistance. Two performance benefits are observed. First, the slope varies more slowly with average temperature, recovering (here) around half of the efficiency penalty from in-stripe temperature non-uniformity, and hence increasing the power conversion efficiency at 800 W optical output power by around 5%. Second, the lateral far field (95% power content) is narrowed by around 2° at 800 W optical output power, corresponding to a reduction of around half of the thermal contribution.
Silicon (100) surface passivation-driven tuning of Ag film crystallinity and its impact on the performance of Ag/n-Si mid-infrared Schottky photodetector
Authors: Sharma Krishna Hari , Dong Yao-Han , Chiang Po-Hsien , Su Zih-Chun , Lin Ching-Fuh
Published: June 2024

The utilization of metal/semiconductor Schottky devices for plasmonic harvesting of hot carriers holds immense potential in the field of sub-bandgap photodetection. In this work, we explore a surface passivation scheme using air plasma exposure to modify the Si (100) surface and subsequently the crystal orientation of the deposited Ag film for photon detection in the mid-infrared (MIR) regime. This tailoring was achieved by varying the plasma exposure duration (0, 150, 300, 450, and 600 s). As a result, we could tune the crystal orientation of Ag from the (200) to the (210) crystal plane, with the Ag (111) orientation present in all devices. Furthermore, the photo-response behavior under MIR exposure at λ = 4.2 µm was studied both experimentally and using COMSOL simulations. It was observed that both photoelectric (PE) and photothermal (PT) effects contributed to the photo-response behavior of all devices. The Ag/Si device exposed to air plasma for 300 s exhibited the maximum PE-driven response (2.73 µA/W), while the device exposed to air plasma for 600 s showed a significant PT-driven response (13.01 µA/W). In addition, this strategy helped reduce the reverse leakage current by up to 99.5%. This study demonstrates that MIR detection at longer wavelengths can be optimized by tailoring the crystal orientation of the metal film.
Development of differential pressure flowmeter and its application in coalbed methane wells
Authors: Li Lei , Wang Ming , Wang Dahai , Li Yue
Published: June 2024

Coalbed methane (CBM) is an increasingly important unconventional natural gas. Production logging can provide important information about the production status of each layer in a CBM well, which is crucial for developing and adjusting development plans. However, currently, only open-hole logging is done for CBM wells, and there is no mature technology for production testing of wells that produce low amounts of gas. To address this issue, a new method has been proposed in this paper for measuring the production profile of CBM wells. This method is based on the pressure difference method and measures the gas–liquid two-phase flow in a 125 mm vertical rising circular tube. The researchers established a simulation model of the CBM wellbore pressure difference method and obtained four flow patterns: bubble flow, slug flow, churn flow, and annular flow. We studied the relationship between the pressure difference and gas and water flow rates at different positions and spacing between measuring points in the wellbore. A differential pressure flowmeter without a throttling device was developed, and gas–liquid dynamic experiments were carried out through a simulation experiment platform to verify the feasibility of the flowmeter. Two well field tests were conducted in Shanxi CBM fields using differential pressure flowmeters, which accurately and quantitatively measured the stratified gas production of CBM wells. This technology can help improve the productivity and development efficiency of CBM wells.
Performance degradation assessment of rolling bearing under vibration signal monitoring based on optimized variational mode decomposition and improved fuzzy support vector data description
Authors: Hu Chaoqun , Chen Zhe , Li Yonghua , Yin Xuejiao
Published: June 2024

Performance degradation assessment methods for rolling bearings under vibration signal monitoring typically involve extracting signal degradation features and inputting them directly into unoptimized assessment models. However, this method often fails to characterize degradation trends and detect early faults in bearings effectively. Moreover, it is susceptible to interference from outliers and false signal fluctuations, posing challenges for accurate performance degradation assessment. To solve the above problems, a novel performance degradation assessment method of rolling bearings based on optimized variational mode decomposition to construct the maximum information degradation feature set and improved hippopotamus optimization algorithm optimized fuzzy support vector data description is proposed. This method effectively suppresses the signal degradation feature pollution caused by the redundancy of irrelevant frequency components, realizes the screening of effective degradation feature sets, and further improves the accuracy of bearing performance degradation assessment. Through experimental verification, this research method uses early healthy rolling bearing samples to establish an assessment model, which can adaptively determine the starting point and degradation trend of bearing degradation. In comparison with other methods for performance degradation assessment under vibration monitoring, it offers distinct advantages.
Inhibition of NLRP3 inflammasome activation by A20 through modulation of NEK7
Authors: Yu Jiayun , Li Hanwen , Wu Yongyao , Luo Min , Chen Siyuan , Shen Guobo , Wei Xiawei , Shao Bin
Published: June 2024

The NLRP3 inflammasome, a pivotal component of innate immunity, has been implicated in various inflammatory disorders. The ubiquitin-editing enzyme A20 is well known to regulate inflammation and maintain homeostasis. However, the precise molecular mechanisms by which A20 modulates the NLRP3 inflammasome remain poorly understood. Here, our study revealed that macrophages deficient in A20 exhibit increased protein abundance and elevated mRNA level of NIMA-related kinase 7 (NEK7). Importantly, A20 directly binds with NEK7, mediating its K48-linked ubiquitination, thereby targeting NEK7 for proteasomal degradation. Our results demonstrate that A20 enhances the ubiquitination of NEK7 at K189 and K293 ubiquitinated sites, with K189 playing a crucial role in the binding of NEK7 to A20, albeit not significantly influencing the interaction between NEK7 and NLRP3. Furthermore, A20 disrupts the association of NEK7 with the NLRP3 complex, potentially through the OTU domain and/or synergistic effect of ZnF4 and ZnF7 motifs. Significantly, NEK7 deletion markedly attenuates the activation of the NLRP3 inflammasome in A20-deficient conditions, both in vitro and in vivo. This study uncovers a mechanism by which A20 inhibits the NLRP3 inflammasome.
European spruce bark beetle, Ips typographus (L.)
Authors:   Fera Science, Audsley Neil , Avila Gonzalo ,   Plant & Food Research, Ioratti Claudio ,   Fondazione Edmund Mach, Caron Valerie ,   CSIRO Health and Biosecurity, Ferracini Chiara ,   Università di Torino, Bukovinszki Tibor ,   Netherlands Food and Consumer Product Safety Authority, Kenis Marc ,   CABI, Milonas Panagiotis ,   Benaki Phytopathological Institute, Herz Annette ,   Julius Kühn-Institut, Trdan Stanislav ,   University of Ljubljana, Fatu Ana-Christina ,   Institute for Sustainable Plant Protection, Sabbatini-Peverieri Giuseppino ,   Agricultural Research Council South Africa, Lesieur Vincent ,   CSIRO Health and Biosecurity, Borowiec Nicolas ,   Institut Sophia Agrobiotech, Collatz Jana ,   Agroscope, Tanner Rob ,   European and Mediterranean Plant Protection Organization, McGee Conor ,   Department of Agriculture Food and the Marine Ireland
Published: June 2024

The European spruce bark beetle (Ips typographus), widespread across Eurasia, is a major pest of coniferous forests in Europe, primarily attacking Norway spruce (Picea abies). High beetle populations can result in significant damage, especially following environmental stressors like storms. Although there has been no classical biological control program against I. typographus due to its non-invasive nature in other continents, the potential introduction of this beetle into new areas like North America could necessitate such measures. Natural enemies in Europe include numerous parasitoids, predators and pathogens. Notably, the parasitoid Tomicobia seitneri shows high specificity and parasitism rates (20-100%) and is a prime candidate for biological control. Other potential candidates include the braconid Coeloides bostrichorum and the clerid beetle Thanasimus formicarius, though the latter's broad prey range limits its suitability for classical biological control. Pathogens like Ips typographus entomopoxvirus also show some specificity but require further study regarding their impact on beetle mortality.
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Authors:   Fera Science, Audsley Neil , Avila Gonzalo ,   Plant & Food Research, Ioratti Claudio ,   Fondazione Edmund Mach, Caron Valerie ,   CSIRO Health and Biosecurity, Ferracini Chiara ,   Università di Torino, Bukovinszki Tibor ,   Netherlands Food and Consumer Product Safety Authority, Kenis Marc ,   CABI, Milonas Panagiotis ,   Benaki Phytopathological Institute, Herz Annette ,   Julius Kühn-Institut, Trdan Stanislav ,   University of Ljubljana, Fatu Ana-Christina ,   Institute for Sustainable Plant Protection, Sabbatini-Peverieri Giuseppino ,   Agricultural Research Council South Africa, Lesieur Vincent ,   CSIRO Health and Biosecurity, Borowiec Nicolas ,   Institut Sophia Agrobiotech, Collatz Jana ,   Agroscope, Tanner Rob ,   European and Mediterranean Plant Protection Organization, McGee Conor ,   Department of Agriculture Food and the Marine Ireland
Published: June 2024

Saperda candida (Coleoptera: Cerambycidae) is native to the eastern USA and southeastern Canada. It was detected in Germany in 2008, where eradication efforts were undertaken. This beetle primarily infests woody hosts within the Rosaceae family, with Cydonia, Malus and Pyrus being significant cultivated hosts in North America. The larvae cause severe damage by girdling the trunks of young trees, leading to tree death. Improved pest management in the mid-20th century reduced its impact in orchards. Despite being an EPPO A1 Pest and an EU A1 quarantine pest, no classical biological control has been attempted. Potential natural enemies include 5 hymenopterous parasites (Cenocoelius saperdae, Echthrus niger, Monogonogastra agrili, Xylophrurus nubilipennis luctuosus and Sarcophaga sp.), which are not present in the EPPO region. Additional predators such as spiders, ants, click beetles, carabid beetles and several woodpecker species also contribute to natural control.
Nesting BiVO4 nanoislands in ZnO nanodendrites by two-step electrodeposition for efficient solar water splitting
Authors: Güler Ali Can , Antoš Jan , Masař Milan , Urbánek Michal , Machovský Michal , Dagupati Rajesh , Žitňan Michal , Velázquez José J , Galusek Dušan , Kuřitka Ivo
Published: June 2024

Photoanodes with a large electrochemically active surface area, rapid charge transfer, and broadband light harvesting capacity are required to maximize the photoelectrochemical (PEC) water splitting performance. To address these features, we demonstrate that 3D hierarchal ZnO nanodendrites (NDs) can be sensitized with BiVO4 nanoislands by chemical and thermal treatments of electrodeposited Bi metal films. The flat band measurements and optical characterization suggested that the resulting heterojunction had type-II band alignment with a viable charge transfer from BiVO4 to ZnO NDs. In parallel, PL analysis revealed inhibition of the charge recombination rate by the electron transfer between BiVO4 and ZnO NDs. Upon AM 1.5 G illumination, BiVO4/ZnO NDs heterojunction yielded the highest photocurrent efficiency (0.15 mA·cm−2 at 1.2 V vs. NHE), which was attributed to its enhanced surface area (due to the presence of small dendrite branches), extended broadband light absorption extending from UV to visible light regions, and the most efficient interfacial charge transfer as proven by electrochemical impedance spectroscopy (EIS) studies. Besides, the incident photon-to-current conversion efficiency and applied bias photon-to-current efficiency tests confirmed an improved spectral photoresponse of the heterojunction based photoanode, particularly towards the visible light spectrum. The results outline a promising synthesis route for building heterojunctions between visible light active and wide band gap semiconductors for the use as a highly efficient photoanodes in a PEC cell.
Theoretical insight on structure, electronic, and optical properties of two d
0–d
10 electron transition-metal oxyhalides SHG materials
Authors: Hu Jinyu , Zhang Jiamei , Zhao Huiyan , He Chao , Wang Xihu
Published: June 2024

Materials containing mixed anions, particularly, oxyhalides containing asymmetric functional building units, may lead to the discovery of excellent nonlinear optical (NLO) materials. In the present work, the geometric structure, mechanical properties, electronic structure and optical properties of two d
0–d
10 electron transition-metal oxyhalides Cs2CdV2O6Cl2 and Cs3CdV4O12Br have been systematically determined based on density functional theory. The asymmetric functional building units [V2O7], [V4O13], [CdO2Cl4] and [CdO4Br2] exhibit varying degrees of second-order Jahn−Teller distortions, contributing differently to the macroscopic nonlinearity. Mechanical properties reveal that the two oxyhalides are structurally and mechanically stable. Detailed electronic and optical properties of the two oxyhalides are provided. Optical anisotropy character is exhibited along different polarization vectors, giving a large birefringence for satisfying the phase-matching condition. Maximum absolute values of static second harmonic generation (SHG) coefficients are 4.47 pm V−1 for Cs2CdV2O6Cl2 and 3.72 pm V−1 for Cs3CdV4O12Br, suggesting that Cs2CdV2O6Cl2 and Cs3CdV4O12Br are potential NLO crystals with large SHG coefficients. In particular, unique 3D framework structures give a polar structure superposition of individual moments for asymmetric functional building units. Thus, maximum magnitudes of the total microscopic dipole are achieved, having the largest influence on the SHG response. This study elucidates the relationship between the structure and properties of transition-metal oxyhalides, providing valuable insights for designing NLO materials with excellent performance.
First-principles study of Stone–Wales defects in monolayer and Bernal-stacked hexagonal boron nitride
Authors: Wang Mingyuan , Zhang Quan , Jiang Yun-cai , Hussain Shahid , Liu Guiwu , Wan Neng , Lei Shuang-Ying , Leifer Klaus
Published: June 2024

Recently, Stone–Wales (SW) defects gradually attracted people’s research interest because of their unique properties. The theoretical research indicated that the SW defect in hexagonal boron nitride (h-BN) can lead to new defect levels in bandgap, making h-BN apply in ultraviolet emitters. However, the SW defect is always observed in graphene and rarely observed in h-BN in the experiments. Here, we confirmed the SW defects are not easily formed in h-BN under thermodynamic conditions by first-principles calculations. Specifically, the monolayer h-BN with SW defect (h-BN-SW) has the weak bond strength, dynamic stability and high-temperature thermal stability, facilitating the healing of SW defects under high-temperature conditions and the role of hydrogen. Additionally, we found the SW defect in AB stacked h-BN (AB-h-BN) have good mechanical stability, dynamic stability and thermodynamic stability than h-BN-SW, especially for AB-h-BN-2SW (2SW defects formed in upper and lower layer of AB-h-BN, respectively), which can meet the requirements for its application in electronic devices. Even under thermodynamic conditions, the formation of SW defects is extremely challenging. Electron beam irradiation technology provides a window for the generation of SW defects in h-BN. This offers opportunities for the introduction and control of SW defects, while also creating potential for their application in electronic devices. Moreover, we found that the absorption peak broadens, and a new absorption peak appears with the generation of SW defects, which is mainly induced by the decrease of bandgap and the generation of defect levels. Our research can provide theoretical guidance at atomic scale for designing and applying h-BN with SW defect in the experiments.
The electronic structure, optical property and n-type conductivity for W-doped α-Ga2O3: hybrid functional study
Authors: Chang Jinyan , Kang Sixin , Chen Yu , Fan S W
Published: June 2024

Based on the hybrid functional method, the electronic structure, optical property and electron effective mass of α-Ga2O3, together with the properties for intrinsic and extrinsic defects incorporated into α-Ga2O3 are studied. Obtained results indicate the α-Ga2O3 possesses a wide band gap (5.31 eV), small electron effective mass (0.22 m0) and a high visible light transmittance. The nonstoichiometric α-Ga2O3 is not an excellent n-type semiconductor. To improve the n-type conductivity, the W-doped α-Ga2O3 is studied. We find that W
Ga is a promising n-type defect due to its relatively small ionization energy ϵ(0/+) (0.30 eV). When the equilibrium fabrication method is selected, the WO2 is a promising dopant source. Using the equilibrium fabrication method, the defect complex (V
O+ W
Ga) would be formed, and the ionization energy ϵ(0/+) for defect complex (V
O + W
Ga) would decrease to 0.08 eV, which implies that a great number of free electrons could be induced in the samples. We expect that this work can promote the understanding of the n-type conductivity for α-Ga2O3 and provide significant insights for the development of a transparent n-type semiconductor.
Tunable high-Q resonances based on the asymmetric nanohole array of phase-change material
Authors: Jiang Xin-Yuan , Zhang Yu-Jie , Fang Bin , Zhang Dong-Qin , Pan Gui-Ming , Jin Zhong-Wei , Hong Zhi , Shu Fang-Zhou
Published: June 2024

Dielectric metasurfaces have made great progress over the past decade to enhance light-matter interaction. Recently, dielectric nanohole structures have been employed for the creation of dielectric metasurfaces. However, the optical characteristics of most dielectric nanohole structures remain fixed once they are manufactured. This study investigates the optical properties of Ge2Sb2Te5 (GST) film perforated with a periodic dual nanohole array. The GST dual nanohole array is capable of supporting multiple guided resonances and bound states in the continuum (BICs). By introducing asymmetry in the radius, BICs can be transformed into quasi-BICs with high-Q resonances. The wavelengths of guided resonances and quasi-BICs can be dynamically controlled through the phase transition of GST. Furthermore, modifying the gap allows for the achievement of active high-Q electromagnetically induced transparency, resulting from the interaction between one guided resonance and one quasi-BIC mode. The GST asymmetric nanohole array holds potential for applications in optical modulators, slow-light devices, and nonlinear optical devices.
Parallel processing of sensor signals using deep learning method for aero-engine remaining useful life prediction
Authors: Wang Tianyu , Li Baokui , Fei Qing , Xu Sheng , Ma Zhihao
Published: June 2024

Accurately predicting the remaining useful life of aerospace engines is crucial for enhancing the reliability of aviation equipment. While some methods have taken note of the challenges posed by vast sensor data and complex signal interrelationships, there is still room for improvement in performance. This paper proposes a novel deep learning model that utilizes a parallel structure to independently process inputs from various sensor signals. Each branch in this parallel structure employs a combination of an improved Inception module and a novel feature filtering module as a feature extractor. The improved Inception module boasts a larger perceptual field to ensure the integrity of feature information. The feature filtering module calculates the importance weights of feature information through convenient computation, allowing the network to focus more on feature information without significantly increasing computational complexity. Finally, the feature extractor is combined with a gated recurrent unit module to learn features from sensor signals. Extensive experiments were conducted on the C-MAPSS standard dataset, comparing the proposed method with other state-of-the-art methods. Ablation experiments were performed on the new generation N-CMAPSS standard dataset. The results of the experiments confirm the superiority and rationality of the proposed prediction method.
Anomaly detection method for urban river water quality based on background model prediction using three-dimensional fluorescence
Authors: Zhang Qiuhao , Yu Jie , Shi Jiegen , Xue Fangjia , Hou Dibo , Zhang Guangxin
Published: June 2024

Three-dimensional fluorescence spectroscopy has great potential for detecting water quality anomalies in urban rivers and protecting against organic pollution. However, current detection methods inadequately address critical application scenarios, such as fluctuations in river water background, low concentration of pollutants, and the fluorescence peaks overlap between pollutants and background. In this paper, a fluorescence spectrum feature extraction method which is effective for the above scenarios was proposed. The proposed method involves a sequential process. First, the original spectrum undergoes preprocessing using a novel method. Next, an alternating residual tri-linearization technique is applied to establish a predictive model for river water spectrum changes. Subsequently, the background model is utilized for spectrum decomposition and reconstruction of the test sample. This reconstructed spectrum is then used to derive the residual spectrum by comparison with the original. Finally, frequency domain features are extracted from the residual spectrum to enable classification, while the background model undergoes real-time updates. In the three meaningful scenarios mentioned above, the accuracy of the proposed method for anomaly detection reached 99%, 82%, and 98%, respectively. Our accuracy is higher than several typical benchmark methods.
MKurt-LIA: mechanical fault vibration signal measurement scheme with frequency tracking capability for bearing condition monitoring
Authors: Zhang Meng
Published: June 2024

Monitoring the operational status of rolling bearings is crucial to ensuring the reliable operation of mechanical equipment, and it is considered as an important task of prognostics and health management in mechanical industry. Finding fault pattern directly from vibration signals measured on bearings can be challenging due to strong noise. Lock-in amplifiers (LIAs) can effectively measure the strength of weak fault signals distorted by noise, thus providing insights for fault diagnosis. However, LIAs are sensitive to the reference frequency, and an incorrect reference frequency can render the measurement even meaningless. In this study, a measurement scheme of LIA with the ability to track time-varying fault frequencies is proposed for measuring fault vibration signal components of in-service bearings, termed MKurt-LIA. The MKurt spectrum is employed for searching the local fault frequencies in the time domain, overcoming the negative impact introduced by using theoretical fault characteristic frequencies calculated based on bearing geometry in previous works. Guided by the statements in Guide to the Expression of Uncertainty in Measurement and its supplements, this work demonstrates through the analysis of propagation of distributions that the negative impact of fault frequency deviation on measurement results is significant and cannot be ignored. Experimental results confirm that the MKurt-LIA scheme effectively measures the amplitude of fault frequency components during bearing service, enabling the detection of fault evolution in the early stages where fault characteristics are completely submerged in the time domain waveform. MKurt-LIA scheme fully respects the fact that fault frequency always deviates from theoretical value, and achieves significantly robust performance in assessing in-service bearing’s operation condition.
A non-intrusive volumetric camera calibration system
Authors: Gunady Ian E , Ding Liuyang , Singh Devdigvijay , Alfaro Bryan , Hultmark Marcus , Smits Alexander J
Published: June 2024

When acquiring quantitative data using cameras, calibration is required to establish the mapping relation between the image space and physical space. Calibration targets with known dimensions are often used, with the most popular being physical targets. In setups where physical access is a challenge, using physical targets may not be possible, and so we develop an adaptive non-intrusive calibration target capable of conducting volumetric calibrations in free space. The calibration target is formed by two intersecting laser beams traversed in the test domain. A novel algorithm is presented for accurately finding the beam intersections, even at small crossing angles. The error sources are assessed along with their scaling behavior with respect to key parameters. The performance of the calibration method is evaluated by using it to examine a test object with known dimensions.
Cage-by-cage supramolecular polymerization via panel-decorated triphenylphosphine organic cage
Authors: Mu Gui-Fang , Yang Cuiqin , Wang Yixin , Yan Qiang
Published: June 2024

Significant efforts have been dedicated to designing porous organic cage compounds with geometric complexity and topological diversity. However, the use of these cage molecules as premade building units for constructing infinite cage-based superstructures remains unexplored. Here, we report the use of a panel-decorated phosphine organic cage as a special monomer to achieve supramolecular polymerization, resulting in cage-by-cage noncovalent polymers through the synergy of metal-coordination and intercage π–π dimerization. At a monomer concentration of 122 mM, the average degree of polymerization reaches 17, corresponding to a molecular weight of 26 kDa. The obtained cage-based supramolecular polymers can further hierarchically self-assemble into vesicular morphologies or one-dimensional nanofiber architectures. Selective control over the cosolvents can regulate their structural hierarchy and assembled morphology. This approach paves a new way for the construction of cage-based hierarchical assemblies and materials.
Nontrivial d-electrons driven superconductivity of transition metal diborides
Authors: Wang Yu , Tang Ju-Hong , Xu Hong-Rui , Zhou Guanghui , Ouyang Gang , Deng Hui-Xiong , D’Agosta Roberto , Yang Kaike
Published: June 2024

Leveraging the progress of first-principles modelings in understanding the mechanisms of superconductivity of materials, in this work we investigate the phonon-mediated superconducting properties of transition metal diborides. We report that TaB2 and NbB2 show superconducting transition temperatures as high as 27.0 and 26.0 K at ambient conditions, respectively, comparable with those obtained for CaB2 or MgB2. By mode-by-mode analysis of the electron-phonon-coupling, we reveal that the high superconducting temperature of transition metal diborides is due mainly to the strong coupling between d electrons of the transition metals and the acoustic phonon modes along out-of-plane vibrations. This fact is distinct from that of CaB2 or MgB2, where the superconductivity stems mainly from the boron px
and py
orbitals, which couple strongly to the optical phonon modes dominated by in-plane B atomic vibrations. Further, we find that transition metal diborides present only a superconducting gap at low temperatures, whereas CaB2 or MgB2 are double superconducting gap superconductors. In addition, we investigate the strain effect on the superconducting transition temperatures of diborides, predicting that Tc
can be further enhanced by optimizing the phonon and electronic interactions. This study sheds some light on the exploring high Tc
boron-based superconductor materials.
Lattice imperfections and high-harmonic generation in correlated systems
Authors: Hansen Thomas , Bojer Madsen Lars
Published: June 2024

We study effects of lattice imperfections on high-harmonic generation from correlated systems using the Fermi–Hubbard model. We simulate such imperfections by randomly modifying the chemical potential across the individual lattice sites. We control the degree of electron–electron interaction by varying the Hubbard U. In the limit of vanishing U, this approach results in Anderson localization. For nonvanishing U, we rationalize the spectral observations in terms of qualitative k-space and real-space pictures. When the interaction and imperfection terms are of comparable magnitude, they may balance each other out, causing Bloch-like transitions. If the terms differ significantly, each electron transition requires a relatively large amount of energy and the current is reduced. We find that imperfections result in increased high-harmonic gain. The spectral gain is mainly in high harmonic orders for low U and low orders for high U.
Shell-model study of58Ni using quantum computing algorithm
Authors: Bhoy Bharti , Stevenson Paul
Published: June 2024

This study presents a simulated quantum computing approach for the investigation into the shell-model energy levels of58Ni through the application of the variational quantum eigensolver (VQE) method in combination with a problem-specific ansatz. The primary objective is to achieve a fully accurate low-lying energy spectrum of58Ni. The chosen isotope,58Ni is particularly interesting in nuclear physics through its role in astrophysical reactions while also being a simple but non-trivial nucleus for shell-model study, it being two particles outside a closed shell. Our ansatz, along with the VQE method are shown to be able to reproduce exact energy values for the ground state and first and second excited states. We compare a classical shell model code, the values obtained by diagonalization of the Hamiltonian after qubit mapping, and a noiseless simulated ansatz+VQE simulation. The exact agreement between classical and qubit-mapped diagonalization shows the correctness of our method, and the high accuracy of the simulation means that the ansatz is suitable to allow a full reconstruction of the full nuclear wave function.
Time crystal embodies chimeralike state in periodically driven quantum spin system
Authors: Rahaman Mahbub , Sakurai Akitada , Roy Analabha
Published: June 2024

Chimera states are a captivating occurrence in which a system composed of multiple interconnected elements exhibits a distinctive combination of synchronized and desynchronized behavior. The emergence of these states can be attributed to the complex interdependence between quantum entanglement and the delicate balance of interactions among system constituents. The emergence of discrete-time crystal (DTC) in typical many-body periodically driven systems occurs when there is a breaking of time translation symmetry. Coexisting coupled DTC and a ferromagnetic dynamically many-body localized (DMBL) phase at distinct regions have been investigated under the controlled spin rotational error of a disorder-free spin-1/2 chain for different types of spin-spin interactions. We contribute a novel approach for the emergence of the DTC-DMBL-chimeralike state, which is robust against external static fields in a periodically driven quantum many-body system.
Corrigendum: Life cycle assessment of wind turbine blade recycling approaches in the United States (2023 IOP Conf. Ser.: Mater Sci Eng. 1293 012027)
Authors: Sproul Evan , Williams Michelle , Rencheck Mitchell L. , Korey Matthew , Ennis Brandon L.
Published: June 2024

Please see Article PDF for corrigendum text.
Research on the spatio-temporal evolution and impact of China’s industrial green development from the perspective of digital economy--based on analysis of 279 cities in China
Authors: Zhou Mengxing , Zhang Jinghua , Huang Ling , Lu Qiuping , Yuan Huimei , Bao Lingxin
Published: June 2024

Empowering industrial green development with the digital economy represents a crucial approach to advancing the green transformation of China’s economy and achieving high-quality economic development. Based on panel data from 279 cities in China from 2011 to 2021, this article uses the spatial econometrics model and threshold effect model to explore the spatial effect and nonlinearity of digital economy (DE) on industrial green development (IGD). The results show that, both DE and IGD exhibit fluctuating upward trends in China. There exists stronger spatial linkage effect in the eastern coastal areas, but this effect is weaker in the central and western regions. Furthermore, DE has significantly promoted IGD, and the conclusion remains robust after a series of endogeneity and robustness tests. Additionally, the promotion of the DE for IGD is characterized by regional spillovers and non-linear dynamics. The research results can serve as a theoretical support and decision-making basis for China to enhance industrial green development, promote the construction of an ecological civilization, and implement sustainable development strategies.
Efficient degradation of methyl red dye from the aqueous solution by individual bacterial and their consortium in a sugarcane bagasse waste-based media
Authors: Patel Bhakti , Desai Reema , Yadav Virendra Kumar , Choudhary Nisha , Ansari Mohammad Javed , Alharbi Sulaiman Ali , Patel Rajat , Thakkar Avani , Patel Ashish
Published: June 2024

Dye is one of the major pollutions around the whole world which have adverse effects on the environment and human beings. There is a requirement for an efficient, reliable, sustainable, and eco-friendly approach to the removal of dyes. In the present research, three individual bacterial strains Enterobacter aerogenes (MBX6), Klebsiella pneumoniae (MBC34), and Micrococcus luteus (MBC23) and their consortium was used to remove Methyl Red (MR) dye. The dye removal was observed at different initial concentrations of dye, nutrient media, additives in the nutrient media and sugarcane bagasse extract as a bacterial growth medium. The outcomes of the study showed that the bacterial consortium exhibits better removal efficiencies (63.6%) than individual bacterial strains and the dye removal percentage (75.19%) enhanced with increasing concentration of sucrose (3%) which was used as media additive. The addition of the sugar in nutrient medium resulted in more effective dye removal. The maximum removal of MR dye (98.6%) was achieved when the consortium was grown in a media containing pure sugarcane bagasse extract. The use of sugarcane bagasse extract (agricultural waste product) as a novel growth medium for the cultivation of bacteria possessing dye removal capabilities can offer a sustainable and cost-effective solution for industrial wastewater treatment.
Integrating multimodal Raman and photoluminescence microscopy with enhanced insights through multivariate analysis
Authors: Di Benedetto Alessia , Pozzi Paolo , Valentini Gianluca , Comelli Daniela
Published: June 2024

This paper introduces a novel multimodal optical microscope, integrating Raman and laser-induced photoluminescence (PL) spectroscopy for the analysis of micro-samples relevant in Heritage Science. Micro-samples extracted from artworks, such as paintings, exhibit intricate material compositions characterized by high complexity and spatial heterogeneity, featuring multiple layers of paint that may be also affected by degradation phenomena. Employing a multimodal strategy becomes imperative for a comprehensive understanding of their material composition and condition. The effectiveness of the proposed setup derives from synergistically harnessing the distinct strengths of Raman and laser-induced PL spectroscopy. The capacity to identify various chemical species through the latter technique is enhanced by using multiple excitation wavelengths and two distinct excitation fluence regimes. The combination of the two complementary techniques allows the setup to effectively achieve comprehensive chemical mapping of sample through a raster scanning approach. To attain a competitive overall measurement time, we employ a short integration time for each measurement point. We further propose an analysis protocol rooted in a multivariate approach. Specifically, we employ non-negative matrix factorization as the spectral decomposition method. This enables the identification of spectral endmembers, effectively correlated with specific chemical compounds present in samples. To demonstrate its efficacy in Heritage Science, we present examples involving pigment powder dispersions and stratigraphic micro-samples from paintings. Through these examples, we show how the multimodal approach reinforces material identification and, more importantly, facilitates the extraction of complementary information. This is pivotal as the two optical techniques exhibit sensitivity to different materials. Looking ahead, our method holds potential applications in diverse research fields, including material science and biology.