bluuebunny/crossref_metadata_2025 huggingface dataset:
A dynamic turbine tip clearance measurement method based on laser self-mixing interferometric ranging considering Doppler effect
Authors: Wu Jun , Chen Yang , Guo Runxia , Chen Jiusheng
Published: August 2024

In view of the Doppler effect caused by rotating blades during dynamic measurement, which reduces the accuracy of tip clearance measurement, a dynamic measurement method of turbine tip clearance based on laser self-mixing interferometric ranging considering the Doppler effect is proposed. Firstly, a self-mixing interference model based on the three-mirror Fabry–Pérot cavity model is proposed. Then, the relationship between distance, frequency, and rotational speed is constructed which lays the foundation for the dynamic measurement of the blade tip clearance. What’s more, the composition of the dynamic self-mixing interferometry system including each experimental measurement parameter is described. Finally, the experimental validation is performed to investigate the relationship between the actual measured distance and frequency after compensating for Doppler shift as well as the accuracy of blade tip clearance measurement. Experimental results demonstrate that as the rotational speed gets faster, greater Doppler frequency shift is generated. Meanwhile, the effect on the accuracy of measurement of blade tip clearance is more obvious. The method considering the influence of Doppler effect effectively improves the reliability and accuracy of the dynamic measurement system of blade tip clearance. The standard deviation of dynamic measurement of blade tip clearance can reach up to 13 μm.
Horizontal rearrangement frequency domain chirplet transform: algorithm and applications
Authors: Xiaofan Huang , Dezun Zhao , Lingli Cui
Published: August 2024

Based on the idea of optimal time–frequency analysis (TFA) theory, a time–frequency post-processing method called horizontal rearrangement frequency domain chirplet transform (HRFCT) is proposed. The proposed method is designed to analyze non-stationary transient signals with nonlinear group delay (GD), aiming at obtaining energy-concentrated and accurate time–frequency representation (TFR). First, based on the image characteristics of the constructed amplitude function, the selection criteria of GD are defined, that is, the local maximum of amplitude function and the local minimum of absolute value of derivative of amplitude function are calculated. Next, according to the calculated GD, the coefficients on the GD trajectory are adaptively extracted, and the coefficients that cause the TFR to be blurred are discarded. Finally, the analysis result of a two-component simulation signal demonstrates the satisfactory performance of the HRFCT, and compared with four advanced TFA methods, the competitiveness of the HRFCT is verified. Additionally, the application of the HRFCT in the processing of constant and variable speed bearing signals highlights its prospects in transient signal analysis and rotating machinery condition monitoring.
Effect of UEVC parameters on cutting surface quality and subsurface damage of single crystal γ-TiAl alloy via atomic simulation
Authors: Chen Yuncui , Zhou Baocheng , Zhu Huibin , Li Haiyan , Feng Ruicheng , Cao Hui , Lei Chunli
Published: August 2024

TiAl alloys are favored by the aerospace industry due to its excellent mechanical properties. However, its intrinsic brittleness, the use of conventional cutting (CC) process leads to the problems of high cutting force and high cutting temperature, which in turn affects the machined surface quality. Ultrasonic elliptical vibratory cutting (UEVC) has been proved to be an effective method to improve the surface quality and reduce the subsurface damage of difficult-to-machine materials. This paper compares the effects of CC and UEVC processes on cutting forces and subsurface damage based on molecular dynamics simulation methods, and the effects of elliptical vibration frequencies and amplitude ratios (AR) on surface morphology, roughness, and subsurface damage are investigated. The results show that the cutting force and subsurface damage in the UEVC process are reduced compared with that in the CC. Due to the vibration frequency, the subsurface damage is mainly dominated by atomic clusters, and both surface and subsurface masses show an optimization trend as the vibration frequency decreases. In terms of the AR, the surface quality is better at an AR of 2/3, with less activation of immovable dislocations, and the degree of subsurface damage decreases as the AR increases, and a relatively stable defective structure emerges when the AR is 1/2. The simulation results facilitate an atomic-scale comprehension of the removal mechanism of UEVC and further provide a theoretical foundation for the surface mass and subsurface damage mechanism and optimization of vibrational parameters of UEVC single crystal γ-TiAl alloy.
Stability of viscous contact wave for the full compressible Navier–Stokes–Korteweg equations with large perturbation
Authors: Dong Wenchao
Published: August 2024

This study focuses on the stability of the viscous contact wave for the one-dimensional full Navier–Stokes–Korteweg equations with density-temperature dependent transport coefficients and large perturbation. Our findings demonstrate a Nishida–Smoller type result, indicating that the solution remains stable under large perturbation as long as

γ
−
1

is sufficiently small. Notably, the smallness of the capillary coefficient is unnecessary. We then employ the initial layer analysis technique to investigate the asymptotic behaviour in the

W

k
,
p

norm. We show that the capillary term has a smoothing effect, which implies that the strong solution is indeed a smooth one. Our results represent an improvement over those previously reported in Chen and Sheng (2019 Nonlinearity
32 395–444). Furthermore, by applying the method in this study to the isothermal case, we can achieve a better outcome than Germain and LeFloch (2016 Commun. Pure Appl. Math.
69 3–61).
Machine learning aided line intensity ratio method for helium–hydrogen mixed recombining plasmas
Authors: Kajita Shin , Nishijima Daisuke , Fujii Keisuke , Tanaka Hirohiko , Vernimmen Jordy , van der Meiden Hennie , Classen Ivo , Ohno Noriyasu
Published: August 2024

The helium line intensity ratio (LIR) with the help of a collisional radiative (CR) model has long been used to measure the electron density,

n
e

, and temperature,

T
e

, and its potential and limitations for fusion applications have been discussed. However, it has been reported that the CR model approach leads to deviations in helium–hydrogen mixed plasmas and/or recombining plasmas. In this study, a machine learning (ML) aided LIR method is used to measure

n
e

and

T
e

from spectroscopic data of helium–hydrogen mixed recombining plasmas in the divertor simulator Magnum-PSI. To analyze mixed plasmas, which have more complex spectral shapes, the spectroscopy data were used directly for training instead of separating the intensities of each line. It is shown that the ML approach can provide a robust and simpler analysis method to deduce

n
e

and

T
e

from the visible emissions in helium–hydrogen mixed plasmas.
Modeling of an electro-active pseudo-trilayer based on PEDOT, a semi-conductor polymer
Authors: Tixier M , Pouget J
Published: August 2024

Electroactive polymers are smart materials that can be used as actuators, sensors, or energy harvesters. We focus on a pseudo trilayer based on PEDOT, a semiconductor polymer: the central part consists of two interpenetrating polymers and PEDOT is polymerized on each side; the whole blade is saturated with an ionic liquid. A pseudo trilayer is obtained, the two outer layers acting as electrodes. When an electric field is applied, the cations move towards the negative electrode, making it swell, while the volume decreases on the opposite side; this results in the bending of the strip. Conversely, the film deflection generates an electric potential difference between the electrodes. We model this system and establish its constitutive relations using the thermodynamics of irreversible processes; we obtain a Kelvin–Voigt stress–strain relation and generalized Fourier’s and Darcy’s laws. We validate our model in the static case: we apply the latter to a cantilever blade subject to a continuous potential electric difference at the constant temperature. We draw the profiles of the different quantities and evaluate the tip displacement and the blocking force. Our results agree with the experimental data published in the literature.
Elastic-plastic conductor damage evaluation at over 0.4% strain using a high-stress REBCO coil
Authors: Bang Jeseok , Bradford Griffin , Kim Kwangmin , Lee Jonathan , Polyanskii Anatolii , Larbalestier David
Published: August 2024

Recent reports on screening current stress simulations of high-field REBCO magnets frequently present peak stresses over 1 GPa. However, this result is probably an unrealistic artifact of purely elastic calculations, considering the macroscopic yield and fracture stresses of approximately 900 MPa and less than 1.1 GPa for Hastelloy substrate-coated conductors. Here, we evaluate elastic-plastic conductor damage at over 0.4% strain using a high-stress REBCO coil exposed to a high field to explore this elastic-plastic regime. The coil was located off-center in a low-temperature superconductor magnet so as to induce a significant screening current in the enhanced radial field. Voltage taps, a Hall sensor, and two strain gauges were used for the instrumentation. We obtained strains exceeding 0.4% near the outward edge during the coil current charge from 350 A to 390 A, where the coil was exposed to external axial and radial magnetic fields of 13 T and 0.5 T. Post mortem results showed wavy plastic deformation, electrical damage, and REBCO defects. An elastic-plastic simulation reproduced the measured strains and predicted that ∼1 GPa stress is sufficient to induce ∼0.9% strain, thus validating our initial concerns with purely elastic models. This paper provides our experimental and simulation results.
Thermal degradation analysis and optimization of controlled heat treatment for stacked high temperature superconducting tapes
Authors: Yang Shige , Tang Bohan , Yue Zhilai , Yu Hui , Xie Bowen , Li Sicheng , Chen Yanquan , Niu Rui , Zhao Jun , Zhou Peng , Chen Wenge , Jiang Shili , Jiang Donghui , Kuang Guangli
Published: August 2024

High temperature superconducting (HTS) tapes have crucial applications for generating high magnetic fields with minimal power input. Given a single tape has a limited current-carrying capacity, stacked tapes are common, fabricated through methods like solder soldering or epoxy impregnation requiring heat treatment. In this work, we have investigated the efficient region for vacuum heat treatment applicable of commercial HTS tapes, analysed the thermal degradation principles and accordingly proposed a controlled heat treatment process for stacked HTS tapes to achieve more precise regulation of the critical current (

I

c

). This heat treatment process was explored using a specialized multi-temperature zone vacuum system. Critical parameters in this process include heat treatment temperature, duration and pressure on the tape. A series of experiments were conducted at 77 K in a self-field to investigate how these parameters affect the superconductivity performance of stacked HTS tapes. Based on the experimental results, an optimal heat treatment process has been proposed. Under the current process, with the heat treatment temperature set at 200 °C, duration at 20 min, and pressure on the tape at 12 MPa, the samples exhibit favourable properties characterized by a smooth and neat appearance without defects such as pinholes or false soldering, and the superconductivity performance can be consistently maintained at more than 97%. The obtained measurements were compared with simulated results, demonstrating an error margin within 0.5%. Moreover, precise control of

I

c

is achieved, tailored to tape and stacking specifications, allowing manageable degradation as required. This heat treatment process for stacked HTS tapes holds significant importance, especially in the context of designing cable-in-conduit conductors fabricated with stacked HTS tapes. It serves as a valuable reference for further advancements in this field.
Molybdenum low-resistance thin-film resistors for cryogenic devices
Authors: Korneeva Yu P , Dryazgov M A , Porokhov N V , Osipov N N , Krasilnikov M I , Korneev A A , Tarkhov M A
Published: August 2024

We present a study of thin-film Mo resistors for NbN electronics operating at cryogenic temperatures. The key step is the 0.5–1.5 keV ion cleaning–activation of NbN before Mo deposition, which allows us to obtain a high-quality Mo/NbN interface. This, together with an additional Al bandage layer in the area of the contact pads, allows us to reduce the contact resistance below 1 Ω. The quality of the interfaces is confirmed by transmission electron microscopy and x-ray reflectometry.
Effect of nitrogen content on the structure and superconductivity of reactive sputtered NbTiN thin films
Authors: Zhang L , Zhong Y L , Xie J J , Jin H , Zhao W B , Peng W , Chen L , Wang Z
Published: August 2024

In this research, we have studied the structural and electrical properties of NbTiN films deposited on MgO and SiO2/Si substrates by reactive dc sputtering. The formation of stoichiometric NbTiN is very sensitive to N concentration and can be easily adjusted by changing the discharge current and Ar: N2 ratio along the current–voltage curves (IVCs) of the NbTi target. Excessive or insufficient N concentration in NbTiN leads to sublattice expansion or distortion, resulting in a decrease in critical temperature T
c. At Ar: N2 ratio of 30:4 and discharge current of 2.2 A, T
c as high as 15.8 K and 15.3 K has been obtained for 200 nm thick NbTiN/MgO and NbTiN/SiO2/Si samples, respectively. In addition, the critical density J
c of the 4 μm-wide and 7 nm-thick NbTiN film grown on MgO substrate at 2 K reaches 19.2 MA cm−2, which is approximately twice as high as the 10.9 MA cm−2 of the same-sized NbTiN film grown on SiO2/Si substrate. Therefore, by further fine-tuning the N concentration in combination with the IVCs of the target, high-quality stoichiometric NbTiN can be obtained.
Telescope imaging beyond the Rayleigh limit in extremely low SNR
Authors: Choi Hyunsoo , Choi Seungman , Menart Peter , Deka Angshuman , Jacob Zubin
Published: August 2024

The Rayleigh limit and low signal-to-noise ratio (SNR) scenarios pose significant limitations to optical imaging systems used in remote sensing, infrared thermal imaging, and space domain awareness. In this study, we introduce a stochastic sub-Rayleigh imaging (SSRI) algorithm to localize point objects and estimate their positions, brightnesses, and number in low SNR conditions, even below the Rayleigh limit. Our algorithm adopts a maximum likelihood approach and exploits the Poisson distribution of incoming photons to overcome the Rayleigh limit in low SNR conditions. In our experimental validation, which closely mirrors practical scenarios, we focus on conditions with closely spaced sources within the sub-Rayleigh limit (0.49–1.00 R) and weak signals (SNR less than 1.2). We use the Jaccard index and Jaccard efficiency as a figure of merit to quantify imaging performance in the sub-Rayleigh region. Our approach consistently outperforms established algorithms such as Richardson–Lucy and CLEAN by 4X in the low SNR, sub-Rayleigh regime. Our SSRI algorithm allows existing telescope-based optical/infrared imaging systems to overcome the extreme limit of sub-Rayleigh, low SNR source distributions, potentially impacting a wide range of fields, including passive thermal imaging, remote sensing, and space domain awareness.
Integrability and multiple kinks, lumps, and breathers solutions to an extended (3+1)-dimensional Calogero-Bogoyavlenskii-Schiff fluid model
Authors: Wazwaz Abdul-Majid , Alhejaili Weaam , El-Tantawy Samir A
Published: August 2024

This study focuses on analyzing a newly constructed extended (3+1)-dimensional Calogero-Bogoyavlenskii-Schiff (CBS) fluid model. The Painlevé test is employed to verify the integrability of this newly extended model. We demonstrate that the inclusion of additional terms does not kill the integrability of the standard model. Hirota’s bilinear approach is employed to formally determine multiple soliton \kink solutions. In addition, we rigorously investigate the particular conditions of the parameters to provide lump solutions. In contrast to lump solutions, we obtain breather wave solutions without any requirement for constraints on the used parameters. Various techniques, including the family of tanh and tan procedures, are used to derive different traveling wave solutions with differing physical structures. The obtained solutions are examined and numerically discussed for several arbitrary functions.
Observation of the quantum Zeno effect on a NISQ device
Authors: Alessandrini Andrea , Ciaramelletti Carola , Paganelli Simone
Published: August 2024

We study the Quantum Zeno Effect (QZE) on a single qubit on IBM Quantum Experience devices under the effect of multiple measurements. We consider two possible cases: the Rabi evolution and the free decay. SPAM error mitigations have also been applied. In both cases we observe the occurrence of the QZE as an increasing of the survival probability with the number of measurements.
Dual-wavelength superscattering in plasmonic core-shell nanostructures for transparent structural color
Authors: Yan Rujiang , Li Yan , Yu Qunxing , Zhong Facheng , Chu Bo , Yang Tian , Huang Zhong , Shao Li , Li Yonggang , Yu Zhanjun , Du Yinxiao
Published: August 2024

Structural coloration generates some of the most vibrant colors in nature and has numerous applications. Inspired by the recently reported transparent displays relying on wavelength-selective scattering, we address the novel problem of transparent structural color, which requires nanoparticles to have a narrow-band and broad-angle scattering response. Although superscattering beyond the single-channel limit has important prospects for enhancing transparent displays, it has not yet been reported. Here, we propose a simple dielectric-gold core–shell nanoparticle capable of superscattering at blue (λ = 450 nm) and green (λ = 532 nm) wavelengths, along with a dipolar surface plasmon resonance (SPR) at the red wavelength (λ = 640 nm), making it suitable for full-color transparent displays. We demonstrate that the superscattering at λ = 450 nm arises from the overlap of the epsilon-near-zero (ENZ) dipolar and quadrupolar modes. Furthermore, the coupling of conventional quadrupolar and dipolar modes can also enhance the scattering efficiency at λ = 532 nm, breaking the single-channel limit. Lastly, we show that the optimized nanoparticles can confine the scattering light within the forward hemisphere at λ = 450 nm and 532 nm, due to the interaction of quadrupolar and dipolar modes. Additionally, they exhibit dipole far-field radiation characteristics at λ = 640 nm with a wide angular beamwidth > 60°. The simple structural nature and unique scattering properties of proposed dielectric-gold core–shell nanoparticles hold promise applications in full-color transparent displays, spectroscopy, and biomedical imaging.
Envisaging quantum capacitance in modified germanene: a first principle investigation
Authors: Khan Md Shahzad , Khan Z R , Alshammari Abdullah S , Bouzidi M , Ahmad Nafis , Mohamed Mansour
Published: August 2024

Two-dimensional (2D) nanomaterials with enhanced quantum capacitance have been in high demand over the past few years due to super capacitors application. A number of 2D nanosheet, including MoS2, arsenene, antimonene, and germanene, have also been explored for the same reason. The present investigation aims to explore modified germanene such as monovacant germanene/divacant germanene(MVG/DVG) and their derivatives, such as Ns substituted MVG/DVG and transition metal incorporated MVG. It is observed that 1N-MVG/3N-MVG shows the characteristics of a p-type semiconductor, while 3N-MVG/4N-DVG is considered as semiconductor. A robust binding of under-coordinated Ge to transition metals (TMs) at MVG surfaces suggests such functionalization can be accomplished. Except Ti and Co other studied TMs-MVG show metallic nature. Furthermore, it is revealed that there is an asymmetric CQ dispersion in 1N-MVG, 2N-MVG, 3N-MVG, and 4N-DVG, as opposed to the pristine germanene/MVG/DVG. Additionally, it is predicted that TMs such as Ti, V, Cr, Mn, Fe and Co incorporated MVG can provide high quantum capacitance (CQ). Enormous amount of CQ is noticed for 3N-MVG with maximum of 726 μF cm−2 in the positive biased region. Among TM-MVG, V-MVG and Mn-MVG are well suited to serve as anodes for asymmetric super capacitors due to their CQ peak of 978 μF cm−2 and 1180 μF cm−2, respectively, in negative bias region.
Influence of HfO2 oxide layer on crystallization properties of In3SbTe2 phase change material
Authors: Pathak Anushmita , Pandey Shivendra Kumar
Published: August 2024

Phase Change Memory (PCM) represents a potential paradigm in the realm of non-volatile memory technologies, and several phase change materials are studied for utilization in PCM devices. This work employs a less explored In3SbTe2 (IST) phase change material (active layer) integrated with an oxide (HfO2) layer and investigates the influence of the oxide layer on the active layer. The oxide layer remains amorphous when annealed at 400 °C, and it doesn’t alter the crystallization temperature (290 °C) of the active layer in IST with HfO2 thin-film. However, after crystallization, the grain size of the active layer is reduced to ∼8.23 nm in IST with HfO2 thin-film, compared to only IST thin-film. XPS core-level spectra (In 3d, Sb 3d, Te 3d) of IST active layer reveal the peak shifting towards higher binding energy at 300 °C and 400 °C annealed films, implying bond energy increase with crystallization and film stability improves. The Hf or O atoms of the oxide layer don’t diffuse into the active layer with annealing, suggesting no interference with the phase switching property of IST. A higher optical bandgap of 1.154 eV in as-deposited IST with HfO2 thin-film compared to the only IST thin-film illustrates better stability of the amorphous state in the film with the oxide layer. In addition, the fabricated PCM device using the IST with the oxide layer demonstrates phase switching at a lower threshold voltage of (2.1 ± 0.1) V, compared to the IST-based device. The findings indicate that the enhanced structural and electrical switching characteristics of IST phase change layer coupled with an oxide layer make it beneficial for data storage PCM applications.
In-situ deposited anti-aging TiN capping layer for Nb superconducting quantum circuits
Authors: Tao 陶 Hao-Ran 浩然 , Du 杜 Lei 磊 , Guo 郭 Liang-Liang 亮亮 , Chen 陈 Yong 勇 , Zhang 张 Hai-Feng 海峰 , Yang 杨 Xiao-Yan 小燕 , Xu 徐 Guo-Liang 国良 , Zhang 张 Chi 驰 , Jia 贾 Zhi-Long 志龙 , Duan 段 Peng 鹏 , Guo 郭 Guo-Ping 国平
Published: August 2024

The performance of Nb superconducting quantum devices is predominantly limited by dielectric loss at the metal–air interface, where Nb2O5 is considered the main loss source. Here, we suppress the formation of native oxides by in-situ deposition of a TiN capping layer on the Nb film. With TiN capping layers, no Nb2O5 forms on the surface of the Nb film. The quality factor Q
i of the Nb resonator increases from 5.6 × 105 to 7.9 × 105 at low input power and from 6.8 × 106 to 1.1 × 107 at high input power. Furthermore, the TiN capping layer also shows good aging resistance in Nb resonator devices, with no significant performance fluctuations after one month of aging. These findings highlight the effectiveness of TiN capping layers in enhancing the performance and longevity of Nb superconducting quantum devices.
BIDSAlign: a library for automatic merging and preprocessing of multiple EEG repositories
Authors: Zanola Andrea , Del Pup Federico , Porcaro Camillo , Atzori Manfredo
Published: August 2024

Objective. This study aims to address the challenges associated with data-driven electroencephalography (EEG) data analysis by introducing a standardised library called BIDSAlign. This library efficiently processes and merges heterogeneous EEG datasets from different sources into a common standard template. The goal of this work is to create an environment that allows to preprocess public datasets in order to provide data for the effective training of deep learning (DL) architectures. Approach. The library can handle both Brain Imaging Data Structure (BIDS) and non-BIDS datasets, allowing the user to easily preprocess multiple public datasets. It unifies the EEG recordings acquired with different settings by defining a common pipeline and a specified channel template. An array of visualisation functions is provided inside the library, together with a user-friendly graphical user interface to assist non-expert users throughout the workflow. Main results. BIDSAlign enables the effective use of public EEG datasets, providing valuable medical insights, even for non-experts in the field. Results from applying the library to datasets from OpenNeuro demonstrate its ability to extract significant medical knowledge through an end-to-end workflow, facilitating group analysis, visual comparison and statistical testing. Significance. BIDSAlign solves the lack of large EEG datasets by aligning multiple datasets to a standard template. This unlocks the potential of public EEG data for training DL models. It paves the way to promising contributions based on DL to clinical and non-clinical EEG research, offering insights that can inform neurological disease diagnosis and treatment strategies.
Plasma performance enhancement and impurity control using a novel technique of argon–hydrogen mixture fueled glow discharge wall conditioning in the ADITYA-U tokamak
Authors: Jadeja K.A. , Ghosh J. , Patel K.M. , Patel A.B. , Tanna R.L. , Patel Kiran , Arambhadiya B.G. , Galodiya K.D. , Kumar Rohit , Aich S. , Raj Harshita , Pradhan L. , Chowdhuri M.B. , Manchanda R. , Ramaiya N. , Yadava Nandini , Patel Sharvil , Shah Kajal , Modi Dipexa , Gauttam A. , Singh K. , Dolui S. , Kumar Ankit , Hegde B. , Kumawat A. , Shah Minsha , Rajpal R. , Nagora U. , Atrey P.K. , Pathak S.K. , Purohit Shishir , Adhiya A. , Kumar Manoj , Assudani Kumudni , Kumavat D. , Jha S.K. , Shah K.S. , Makwana M.N. , Gupta Shivam , Nair Supriya , Mishra Kishore , Raju D. , Chattopadhyay P.K. , Kataria B.R.
Published: August 2024

Effective control of impurities and precise regulation of the fueling gas are supreme prerequisites for optimal operation in any fusion device. Conventional wall-conditioning methods fall short of achieving optimal wall conditioning. Conventional wall-conditioning methods, such as vessel baking and H2/(D2)-fueled glow discharge cleaning (GDC), are generally required to remove wall-absorbed impurities in bulk after vessel venting. The excess amount of hydrogen, injected during H2 GDC, can be reduced by helium (He)-fueled GDC. However, He removal from the vessel is more challenging due to its low molecular mass, very low condensation temperature, and inert characteristics. In ADITYA-U, optimal wall conditioning cannot be achieved using H2 followed by He-fueled GDC when applied for extended periods spanning hours or days. A GDC with a mixture of argon and hydrogen (Ar–H2) is introduced in the ADITYA-U tokamak to obtain better wall conditioning than H2 followed by He GDC. In Ar–H2 GDC, long-lived ArH+ ions are formed in sufficient numbers and accelerated toward the vessel wall with high momentum. This results in the breaking of high energy bonds of impurities with the wall/plasma facing components, which is not possible by H+, H2
+, H3
+ ions in H2 GDC due to their lower momentum. An optimal blend ratio of Ar to H2 is established at 15%–20% for the mixture. This composition ensures that the introduction of high-Z Ar does not adversely affect tokamak plasma operations. The C- and O-containing impurities are reduced beyond the limit of the prolonged operation of H2 GDC. Relative low pressures of dominant impurities such as CO, CH4, and H2O are obtained due to the Ar–H2 GDC compared to routinely operated H2 GDC. A comparison study of H2 GDC and the developed Ar–H2 GDC is performed in terms of wall conditioning and tokamak plasma operation. The encouraging results of the Ar–H2 GDC are obtained in both wall cleaning and tokamak operation scenarios in the midsize tokamak ADITYA-U. This development and application of Ar–H2 GDC are beneficial for large-sized fusion devices, leading to improved impurity reduction, reduced operational fuel consumption (H2/D2/He), and enhanced control over fuel recycling/extraction.
Growth, poverty trap and escape
Authors: Bose Indrani
Published: August 2024

The well-known Solow growth model is the workhorse model of the theory of economic growth, which studies capital accumulation in a model economy as a function of time with capital stock, labour and technology-based production as the basic ingredients. The capital is assumed to be in the form of manufacturing equipment and materials. Two important parameters of the model are: the saving fraction

s

of the output of a production function and the technology efficiency parameter

A

, appearing in the production function. The saved fraction of the output is fully invested in the generation of new capital and the rest is consumed. The capital stock also depreciates as a function of time due to the wearing out of old capital and the increase in the size of the labour population. We propose a stochastic Solow growth model assuming the saving fraction to be a sigmoidal function of the per capita capital

k

p

. We derive analytically the steady state probability distribution

P
(

k

p

)

and demonstrate the existence of a poverty trap, of central concern in development economics. In a parameter regime,

P
(

k

p

)

is bimodal with the twin peaks corresponding to states of poverty and well-being, respectively. The associated potential landscape has two valleys with fluctuation-driven transitions between them. The mean exit times from the valleys are computed and one finds that the escape from a poverty trap is more favourable at higher values of

A
.

We identify a critical value of

A

c

below (above) which the state of poverty (well-being) dominates and propose two early signatures of the regime shift occurring at

A

c

. The economic model, with conceptual foundations in nonlinear dynamics and statistical mechanics, shares universal features with dynamical models from diverse disciplines like ecology and cell biology.
Mesoporous silica thin film as effective coating for enhancing osteogenesis through selective protein adsorption and blood clotting
Authors: Li Zhe , Qin Bowen , Liu Huan , Du Shimin , Liu Yunxian , He Lixing , Xu Boya , Du Liangzhi
Published: August 2024

The role of blood clots in tissue repair has been identified for a long time; however, its participation in the integration between implants and host tissues has attracted attention only in recent years. In this work, a mesoporous silica thin film (MSTF) with either vertical or parallel orientation was deposited on titania nanotubes surface, resulting in superhydrophilic nanoporous surfaces. A proteomic analysis of blood plasma adsorption revealed that the MSTF coating could significantly increase the abundance of acidic proteins and the adsorption of coagulation factors (XII and XI), with the help of cations (Na+, Ca2+) binding. As a result, both the activation of platelets and the formation of blood clots were significantly enhanced on the MSTF surface with more condensed fibrin networks. The two classical growth factors of platelets-derived growth factors-AB and transformed growth factors-β were enriched in blood clots from the MSTF surface, which accounted for robust osteogenesis both in vitro and in vivo. This study demonstrates that MSTF may be a promising coating to enhance osteogenesis by modulating blood clot formation.
Study on in vivo and in vitro degradation of polydioxanone weaving tracheal stents
Authors: Huang Haihua , Wang Yuchen , Zeng Jun , Ma Yanxue , Cui Zelin , Zhou Yongxin , Ruan Zheng
Published: August 2024

The appropriate degradation characteristics of polydioxanone (PDO) are necessary for the safety and effectiveness of stents. This study aimed to investigate the degradation of PDO weaving tracheal stents (PW stents) in vitro and in vivo. The degradation solution of S. aureus (SAU), E. coli (ECO), P. aeruginosa (PAE), and control (N) were prepared, and the PW stents were immersed for 12 weeks. Then, the radial support force, weight retention, pH, molecular structure, thermal performance, and morphology were determined. Furthermore, the PW stents were implanted into the abdominal cavity of rabbits, and omentum was embedded. At feeding for 16 weeks, the mechanical properties, and morphology were measured. During the first 8 weeks, the radial support force in all groups was progressively decreased. At week 2, the decline rate of radial support force in the experimental groups was significantly faster compared to the N group, and the difference was narrowed thereafter. The infrared spectrum showed that during the whole degradation process, SAU, ECO and PAE solution did not lead to the formation of new functional groups in PW stents. In vitro scanning electron microscope observation showed that SAU and ECO were more likely to gather and multiply at the weaving points of the PW stents, forming colonies. In vivo experiments showed that the degradation in the concavity of weaving points of PW stents was more rapid and severe. The radial support loss rate reached more than 70% at week 4, and the radial support force was no longer measurable after week 8. In omentum, multinuclear giant cells and foreign giant cells were found to infiltrate. PW stents have good biocompatibility. The degradation rate of PW stents in the aseptic conditions in vivo was faster than in the bacteriological environment in vitro.
Cooperative food bank: a collective insurance regime to govern food insecurity and nitrogen pollution under risk
Authors: Liao Wenying , Vasconcelos Vítor V , Levin Simon A , Oppenheimer Michael
Published: August 2024

Risks, such as climate change, disease outbreak, geopolitical tension, may exacerbate food insecurity by negatively impacting crop yield. Additional agricultural nitrogen input may partly offset yield losses, with a corresponding increase in nitrogen pollution. The problems of food insecurity and nitrogen pollution are urgent and global but have not been addressed in an integrated fashion. Current efforts to combat food insecurity occur primarily through the United Nations’ World Food Program at the international level, and, at the local community level, through food banks. The international program to monitor and reduce global nitrogen pollution is in its early stage. Food provision and nitrogen pollution reduction from agriculture presents a dual challenge that requires an integrated solution. Here, we propose a cooperative food bank, where membership is a matter of choice and is not coerced. Membership requires participants to reduce nitrogen pollution in agriculture but creates a risk-buffering system, providing food compensation when participants are affected by risk factors. We delineate the structure of the cooperative food bank, its operation, from the short-term mobilization of resources to long-term capacity building. Lastly, we assess the feasibility of its implementation and highlight the potential major roadblocks to its implementation within the current socio-political context. The cooperative food bank showcases a novel solution that simultaneously tackles food insecurity and nitrogen pollution via governance. We hope this proposal will stimulate a research agenda and policy discussions focused on integrated approaches to effective governance regimes for linked socio-environmental problems.
Quantifying the impact of dams on global streamflow over the period of 1985–2014
Authors: Han Dongyang , Liu Pan , Zhang Lu , Cheng Lei , Cheng Qian , Zhang Xiaojing , Liu Weibo , Yin Jiabo
Published: August 2024

Abstract

The number of dams globally has increased dramatically over the past few decades, providing reliable water resources by regulating natural streamflow. However, assessing the impact of dams on natural streamflow at a large scale remains a challenge due to lack of dam storage variation data. Here we analyzed flow regulation by dams from 1985 to 2014 over 153 basins globally using satellite remote sensing data. Two-thirds of global basins are regulated below 10%, and the high degree of regulation is mainly distributed in underdeveloped regions such as Central Asia and East Asia. Only 27% of basins have an increasing regulation trend from 1985 to 2014 and no basins show a decreasing trend. The gross domestic production, climatic water deficit and runoff show significant correlations with the flow regulation. We provide a global scale assessment of flow regulation by dams to support global water resources management.
A new global hybrid map of annual herbaceous cropland at a 500 m resolution for the year 2019
Authors: Fritz Steffen , Lesiv Myroslava , See Linda , Schepaschenko Dmitry , Pérez Guzmán Katya , Laso Bayas Juan Carlos , Schepaschenko Maria , Georgieva Ivelina , Collivignarelli Francesco , Meroni Michele , Kerdiles Hervé , Rembold Felix , McCallum Ian
Published: August 2024

The global spatial extent of croplands is a crucial input to global and regional agricultural monitoring and modeling systems. Although many new remotely-sensed products are now appearing due to recent advances in the spatial and temporal resolution of satellite sensors, there are still issues with these products that are related to the definition of cropland used and the accuracies of these maps, particularly when examined spatially. To address the needs of the agricultural monitoring community, here we have created a hybrid map of global cropland extent at a 500 m resolution by fusing two of the latest high resolution remotely-sensed cropland products: the European Space Agency’s WorldCereal and the cropland layer from the University of Maryland. We aggregated the two products to a common resolution of 500 m to produce percentage cropland and compared them spatially, calculating two kinds of disagreement: density disagreement, where the two maps differ by more than 80%, and absence-presence of cropland disagreement, where one map indicates the presence of cropland while the other does not. Based on these disagreements, we selected continuous areas of disagreement, referred to in the paper as hotspots of disagreement, for manual correction by experts using the Geo-Wiki land cover application. The hybrid map was then validated using a stratified random sample based on the disagreement layer, where the sample was visually interpreted by a different set of experts using Geo-Wiki. The results show that the hybrid product improves upon the overall accuracy statistics in the areas where the underlying cropland layer from the University of Maryland was improved with the WorldCereal product, but more importantly, it represents an improved spatially explicit cropland mask for early warning and food security assessment purposes.
Contrasting East Asian climate extremes in 2020 and 2022 tied to zonal flow
Authors: He Chao , Collins Matthew , Zhou Tianjun , Jiang Xingwen , Wu Peili , Dunstone Nick
Published: August 2024

Subtropical East Asia (STEA) experienced a historic flood in the summer of 2020, and historic drought and heatwaves in the summer of 2022. Previous studies emphasized the role of western Pacific subtropical high (WPSH), but there is a paradox that the contrasting climate extremes over STEA in 2020 and 2022 are both associated with anomalously strong WPSH. Given that local vertical motion has a dominant control on precipitation variability, here we investigate the mechanism for the variability of vertical motion in STEA. In most extratropical regions of the Northern Hemisphere, ascent (descent) motion aligns with southerly (northerly) flow in the troposphere due to the northward tilting isentropic surfaces. However, isentropic surfaces tilt eastwards over STEA in the summer due to the existence of a strong warm center over the Tibetan Plateau (TP). Thus, the ascent motion over the STEA is insensitive to the strength of southerly flow related to the intensity of the WPSH but sensitive to the strength of westerly flow related to the meridional shift of subtropical jet. The notably strong WPSH in 2020 and 2022 increased water vapor transport into STEA but had little impact on atmospheric vertical motion. However, the East Asian subtropical jet displaced southwards (northwards) in the summer of 2020 (2022), leading to anomalous westerly (easterly) flows in the mid-upper troposphere from TP to STEA on the jet’s southern flank, prompting anomalous ascent (descent) motion in STEA that contributed to the flood (drought) conditions in 2020 (2022). Our results highlight the essential role of anomalous zonal flow in generating surface climate extremes over STEA in the summer because of its strong control of vertical motion.
Graph limit of the consensus model with self-delay
Authors: Haskovec Jan
Published: August 2024

It is known that models of interacting agents with self-delay (reaction-type delay) do not admit, in general, the classical mean-field limit description in terms of a Fokker–Planck equation. In this paper we propose the graph limit of the nonlinear consensus model with self-delay as an alternative continuum description and study its mathematical properties. We establish the well-posedness of the resulting integro-differential equation in the Lebesgue Lp
space. We present a rigorous derivation of the graph limit from the discrete consensus system and derive a sufficient condition for reaching global asymptotic consensus. We also consider a linear variant of the model with a given interaction kernel, which can be interpreted as a dynamical system over a graphon. Here we derive an optimal (i.e. sufficient and necessary) condition for reaching global asymptotic consensus. Finally, we give a detailed explanation of how the presence of the self-delay term rules out a description of the mean-field limit in terms of a particle density governed by a Fokker–Planck-type equation. In particular, we show that the indistinguishability-of-particles property does not hold, which is one of the main ingredients for deriving the classical mean-field description.
Study on antibacterial characteristics and mechanism of synergistic modification of calcined gypsum from phosphogypsum by inorganic antibacterial materials
Authors: Fu Juan , Fang Shuang-Ming , Luo Jie , Peng Zhu , Li Zi-Ling , Cheng Jin-Ke
Published: August 2024

Mold on the phosphogypsum wallboard seriously hinders the resource utilization of phosphogypsum, and incorporating inorganic antibacterial materials can effectively inhibit mold growth. In this study, Escherichia coli and wallboard mold were used as experimental strains, and the antibacterial activity of antibacterial material-modified calcined gypsum from phosphogypsum (CPG) was determined using the inhibition zone method and mold surface growth area analysis. Characterization techniques such as XRF, XRD, and SEM were used to study the phase composition and microstructure of the samples, and an antibacterial model was constructed to explore the antibacterial mechanism. The results indicated that using E. coli as an indicator bacterium, ZnO-0.05TiO2-CPG exhibited the best bactericidal effect, while ZnO-CPG exhibited the best bacteriostatic effect. Against mold, ZnO contents of 2.5% or 5% demonstrated strong antibacterial properties, with compressive strengths of 10.1 MPa and 9.95 MPa, respectively, meeting the requirements of ≥3.50 MPa for compressive strength according to the ‘Lightweight Partition Plates for Building’ standard (GB/T 23451 2009). The superior antibacterial performance of ZnO compared to TiO2 is attributed to the slow release of Zn2+, which disrupts cell membranes and the generated reactive oxygen species inhibit cell growth.
Forming quality and static properties of self-piercing riveted joints of hot-rolled steel and aluminum alloy sheets
Authors: Jia Yinglian , He Shisong , Li Xiaoyang
Published: August 2024

The self-piercing riveting (SPR) Forming and tensile tests of hot-rolled steel sheet BR1200HS and aluminum alloy sheet AA 6082-T6 were simulated by Simufact Forming software. The test results show that the diameter of the rivet leg opening, which is the most important parameter affecting the mechanical properties of the joints, shows a first increase and a second decrease with the increase of rivet length, and the Max. tensile loads of the joints have the same variation law. The larger the diameter of the rivet leg opening, the greater the Max. tensile load of the joint, and the greater the effective plastic strain of the rivet of the joint. The rivet length of the joints in the five preferred SPR formation schemes obtained were all 6.5 mm, and only one scheme had a rivet hardness of H4, the rest were H5. The SPR experiment is used to verify the current finite element simulation data can get the final research conclusion. The finite element simulation (FEM) would greatly reduce the test times of the SPR test, save the test consumables and save the test cost.
Strength, microstructure and bonding mechanism of borosilicate glass-to-SA105 carbon steel seals
Authors: Liu Zheng , Cai Yangyang , Gong Keqian , Zhou Chao , Wang Chen , Zhao Yuna , Zhang Yong
Published: August 2024

The bonding strengths, microscopic characteristics and fracture properties of borosilicate glass-to-SA105 carbon steel seals were investigated, and two different glass-to-metal bonding mechanisms were compared. First, a mechanical interlocking mechanism was found via precipitates formed from chemical reactions at the interface of the seal bonded to unoxidized SA105 carbon steel. Second, a transitional layer mechanism was proven by the dissolution of metal oxides, which was on the surface of preoxidized SA105 carbon steel, into the glass. The bonding strength results showed that both mechanisms effectively contributed to the joining of dissimilar phases, but the effect of the latter mechanism was more prominent than that of the former mechanism. Various microstructures and chemical compositions of the surface oxide scales were obtained by applying different preoxidation conditions to SA105 carbon steel. Additionally, different sealing interfaces were reported through this process. The width of the interfacial transitional layer ranged from 0.5 μm to 1.5 μm, and the strength of the seal was closely related to this width. The sealing of SA105 carbon steel that was preoxidized at 800 °C for 30 min with a moderate width of the transitional layer had an optimal shear strength of 25.4 MPa. However, a wide transitional layer composed of the remaining oxide scales deteriorated the strength of the seal. In addition, fracture analysis of the seals after the shear test was conducted, and the intrinsic correlations between the macroscopic shear strength and microscopic bonding mechanism were established. The present work should provide a reference for the characterization of bonding strength in joining dissimilar materials.